Multi-station deposition apparatus and method

BACKGROUND OF THE INVENTION

P-0001[0001] 1. Field of the Invention

P-0002[0002] The present invention relates to chemical vapor deposition processes. More particularly, the invention relates to a multi-station deposition apparatus and method.

P-0003[0003] 2. Description of the Background Art

P-0004[0004] As the size of integrated circuit (IC) devices decreases, the deposition techniques used to form very thin films on substrates has become the focus of much interest. To deposit thin films into ultra-high aspect ratio vias and trenches (e.g., aspect ratios on the order of 20:1), atomic layer deposition (ALD) has been used.

P-0005[0005] An ALD technique deposits a thin film having a thickness of less than 50 Å by alternating the supply of reactant gases and purging gases. Each reactant gas is adsorbed onto the wafer as a monolayer, i.e., a layer being substantially one atom thick. The monolayers of various reactant gas react with one another to form a thin film. A thin film having a high aspect ratio, good uniformity, as well as good electrical and physical properties can be formed using an ALD process. Also, the ALD films have a lower impurity density than those formed by other deposition methods.

P-0006[0006] ALD generally involves positioning a wafer in a chamber, generating a vacuum in the chamber, and applying certain reactant gases in short bursts (or pulses) to form a thin film upon the substrate. A purge gas may be applied in between reactant gas bursts. Each burst results in the adsorption of a monolayer of gas. The application of gas bursts may be repeated to deposit a thicker film. Once a film of desired thickness is formed, a purge gas is used to remove residual reactant gases from the chamber, the chamber vacuum is released, and the wafer is removed from the chamber.

P-0007[0007] In one particular example of ALD, a thin tungsten layer may be formed by alternately pulsing silane (SiH₄) gas and tungsten hexafluoride (WF₆) gas into a chamber. The reaction between the adsorbed gases on the surface of the wafer produces a thin tungsten film. After the thin layer is formed, hydrogen-reduced tungsten hexafluoride can be used to “bulk fill” tungsten onto the nucleation layer. Such an ALD-based process results in very good step coverage of ultra-high aspect ratio trenches and vias.

P-0008[0008] One method believed to overcome the inherent slowness of an ALD process is a batch process that simultaneously processes many wafers. Some batch processes involve stacks of processing zones having multiple wafers placed in the zones. Within each zone, a laminar flow of reactant gases is supplied over each wafer in the stack. Although effective at simultaneously processing multiple wafers, the stacked zone processing technique has limited throughput.

P-0009[0009] Therefore, there is a need in the art for a method and apparatus for ALD processing of multiple wafers simultaneously such that wafer throughput is improved.

SUMMARY OF THE INVENTION

P-0010[0010] The present invention is a method and apparatus for performing atomic layer deposition (ALD) processes or chemical vapor deposition (CVD) processes upon multiple wafers simultaneously.

P-0011[0011] In one embodiment, the multi-wafer deposition apparatus comprises a series of deposition stations that are positioned upon a rotating platen. Above each station on the rotatable platen is at least one gas delivery nozzle or showerhead that dispense reactant gases. The nozzles at each station supply gases that perform the various stages of the deposition process to form a particular film or film combination upon a wafer. Each station is separated from other stations by a gas curtain. The gas curtains produce a barrier to inhibit reactant gases used in one station from passing to an adjacent station.

P-0012[0012] In operation, a wafer is positioned on a wafer support in a first station using a wafer transfer robot. A gas nozzle (or showerhead) dispenses a first reactant gas into a region above the wafer such that the first reactant gas is adsorbed upon the wafer. A burst of the first reactant gas may be followed by a burst of purge gas. Alternatively, the purge gas may be continuously supplied to the nozzle and a burst of reactant gas may be inserted into the purge gas flow. The purge gas removes any residual reactant gas that was not adsorbed onto the wafer. The first reactant gas is constrained to the first station by gas curtains formed on either side of the wafer support. The curtains form radials from a center hub of the rotatable platen to the edge of the platen. An inert purge gas is used to form the curtains.

P-0013[0013] Next, the platen is rotated to position the wafer in the first station beneath a second nozzle that supplies another reactant gas. A pulse of the second reactant gas is applied to the wafer and the second reactant gas reacts with the first reactant gas to form a layer of material. Such a deposition process forms a thin layer (sometimes referred to as a monolayer) in an atomic layer deposition (ALD) mode.

P-0014[0014] While the first station is receiving the second gas at the second platen position, a second wafer can be placed in a second station on the platen and have the first reactant gas applied thereto. At each platen position, the wafer temperature can be adjusted to optimize the reaction and/or adsorption that is to occur at that position. The same reactant gases may be applied from additional nozzles such that the film can be increased in thickness. Alternatively, the wafers can be repeatedly returned to the first two nozzles to increase the film thickness, leaving other nozzles for other gases, e.g., bulk fill gases.

P-0015[0015] In another alternative embodiment, each station may be used to deposit multiple gases either sequentially or simultaneously such that the apparatus deposits material in a chemical vapor deposition mode. If the gases are supplied sequentially, a purge gas may be supplied to the wafer in between each of the applications of reactant gas. To facilitate dispensing one or more gases in a station, a multi-zone nozzle is used. A multi-zone nozzle comprises a plurality of conduits that each couple to a plenum and each plenum provides gas to a disbursement port.

BRIEF DESCRIPTION OF THE DRAWINGS

P-0016[0016] The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:

P-0017[0017]FIG. 1 is a perspective view of an embodiment of a deposition apparatus according to the present invention;

P-0018[0018]FIG. 2 is a top plan view of a rotatable platen used in the apparatus of FIG. 1;

P-0019[0019]FIG. 3 is a plan view of a gas distribution manifold

P-0020[0020]FIG. 4 is a cross-sectional view of the gas distribution manifold of FIG. 3 taken a long line <b>4</b>-<b>4</b>;

P-0021[0021]FIG. 5 is a cross-sectional view of a showerhead;

P-0022[0022]FIG. 6 is a schematic view of one station of the apparatus of FIG.

P-0023[0023]FIG. 7 depicts a flow diagram of the operation of one embodiment of the present invention;

P-0024[0024]FIG. 8 is a perspective view of a second embodiment of an atomic layer deposition apparatus according to the present invention;

P-0025[0025]FIG. 9 is a cross sectional view of another embodiment of a nozzle—specifically a multi-zone nozzle;

P-0026[0026]FIG. 10 is a plan view of one embodiment for the multi-zone nozzle of FIG. 9;

P-0027[0027]FIG. 11 is a plan view of an alternative embodiment of the multi-zone nozzle of FIG. 9;

P-0028[0028]FIG. 12 is a block diagram of a gas delivery system for a multi-zone nozzle of FIG. 9; and

P-0029[0029]FIG. 13 is a flow diagram of the operation of an embodiment of the invention that dispenses gas in a chamber using a multi-zone nozzle.

P-0030[0030] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.

DETAILED DESCRIPTION

P-0031[0031]FIG. 1 is a perspective view of an embodiment of a deposition apparatus <b>100</b> according to the present invention. While FIG. 1 provides an illustration of the entire embodiment, FIG. 2 depicts a top plan view of a rotatable platen <b>102</b> so as to clearly depict the plurality of deposition stations, <b>202</b>A-<b>202</b>F within the apparatus <b>100</b>. To best understand the invention, FIGS. 1 and 2 should be viewed simultaneously. The apparatus <b>100</b> comprises a chamber <b>150</b>, a gas supply <b>170</b> for supplying gases to the chamber <b>150</b>, a gas dispensing system <b>104</b> for dispensing gases, and a wafer platen <b>102</b> for supporting wafers <b>200</b> in the chamber <b>150</b> during processing. The apparatus <b>100</b> is controlled by a controller <b>160</b>. Although the embodiments of the invention described herein are discussed with respect to semiconductor wafer processing, other substrates may be processed in lieu of semiconductor wafers.

P-0032[0032] To supply wafers to the apparatus <b>100</b>, a wafer transfer module <b>180</b> communicates with the apparatus <b>100</b>. The wafer transfer module <b>180</b> comprises a loadlock and a wafer transfer robot. The details of the wafer transfer module <b>180</b> are not shown, since module <b>140</b> does not form a part of the present invention. The loadlock accepts wafers from a factory interface and temporarily stores the wafers prior to and after processing. A wafer transfer robot moves the wafers from the load lock into the stations <b>202</b>A-<b>202</b>F for processing. To facilitate wafer access to the chamber <b>150</b>, the chamber wall contains a slit valve or other form of portal.

P-0033[0033] The chamber <b>150</b> defines a volume <b>151</b> within which a partial vacuum is maintained during wafer processing. The vacuum is created in a well-known manner by at least one vacuum pump <b>153</b>. The chamber <b>150</b> has a substantially cylindrical shape and houses the gas dispensing system <b>104</b> and the wafer platen <b>102</b>.

P-0034[0034] The platen <b>102</b> is, in one embodiment, circular in shape having a point of rotation disposed in the center of the platen <b>102</b>. The platen <b>102</b> is fixed in the horizontal and vertical planes and rotates about its central axis in the horizontal plane.

P-0035[0035] The platen <b>102</b> is subdivided into wedge-shaped segments by purge gas curtain distributors <b>204</b>A-<b>204</b>F. These segments are referred to herein as stations <b>202</b>A-<b>202</b>F. Each of the curtain distributors <b>204</b>A-<b>204</b>F produce a vertical curtain of purge gas that isolates the gases used at any one instant within any one station from adjacent stations.

P-0036[0036] Each station <b>202</b>A-<b>202</b>F comprises a wafer support <b>206</b>A-<b>206</b>F. The wafer supports <b>206</b>A-<b>206</b>F are arranged in an equidistantly spaced circular pattern about the hub <b>117</b>. The wafer supports <b>206</b>A-<b>206</b>F are affixed to the hub <b>117</b> by a plurality of radial arms <b>208</b>A-<b>208</b>F. The radial arms <b>208</b>A-<b>208</b>F contain wires that supply electrical signals to the support pedestals <b>206</b>A-<b>206</b>F. The wafer supports <b>206</b>A-<b>206</b>F may be wafer pedestals that retain the wafer using mechanical clamp rings, vacuum chucks, or electrostatic chucks. Additionally, each individual support may contain a wafer thermal control (heating and/or cooling) element. As such, the wafer temperature may be independently adjusted at each process position as the platen is rotated.

P-0037[0037] An actuator <b>155</b> causes the platen to move relative to the gas dispensing system <b>104</b>. In one embodiment, the platen <b>102</b> may be caused to rotate by a direct drive motor, a concentric drive hub mechanism, a geared hub, a belt driven hub mechanism, or any technique commonly known in the art for obtaining rotation of an object. The direction of rotation of the platen <b>102</b> is indicated by the arrows <b>118</b>. To facilitate rotation, the platen <b>102</b> is mounted to a platen support <b>108</b> that is coupled to an actuator <b>155</b>. In alternative embodiments, as discussed below, the gas dispensing system <b>104</b> may be caused to rotate or both the platen <b>102</b> and the gas dispensing system <b>104</b> may be caused to simultaneously rotate.

P-0038[0038] A gas dispensing system <b>104</b> is disposed directly above the platen <b>102</b> and is generally supported by the top of chamber <b>150</b>. The system <b>104</b> is supplied various gases from the gas supply <b>170</b> via gas lines <b>116</b>, <b>126</b> and <b>128</b>. The gas dispensing system <b>104</b> comprises a plurality of nozzle assemblies <b>120</b>A-<b>120</b>F that are coupled to a gas distribution manifold <b>130</b>. The gas dispensing system <b>104</b> distributes gases to the nozzle assemblies <b>120</b>A-<b>120</b>F from the various reactant gas lines <b>126</b> and <b>128</b> as well as the purge gas lines <b>116</b>.

P-0039[0039] As is discussed in detail with respect to FIGS. 3, 4 and <b>5</b> below, gases are carried by the gas lines <b>126</b>, <b>128</b> and <b>116</b> to the gas distribution manifold <b>130</b>. The gas distribution manifold <b>130</b> distributes gases to the nozzle assemblies <b>120</b>A-<b>120</b>F. As discussed further below, the manifold <b>130</b> could supply reactant gases sequentially to each of the nozzles or the manifold <b>130</b> could simultaneously supply a plurality of gases to each nozzle.

P-0040[0040] The apparatus <b>100</b> is controlled by controller <b>160</b>. Controller <b>160</b> comprises a central processing unit (CPU) <b>162</b>, a memory <b>164</b> and support circuits <b>166</b>. The CPU <b>162</b> is a microprocessor or microcontroller that executes software stored in the memory <b>166</b> to produce control signals for the apparatus <b>100</b>. The control signals include, but are not limited to, gas pulse timing, gas pressure control, platen rotation control, wafer ingress and egress, wafer temperature, and the like. The CPU <b>162</b> is coupled to various well-known support circuits <b>164</b> that include cache, power supplies, input/output circuits, clock circuits and the like. The memory <b>166</b> may include at least one of random access memory, read only memory, removable storage, disk drives and the like. The memory <b>166</b> stores software such as process routine <b>168</b> that is executed by the CPU to cause the ALD apparatus <b>100</b> to perform various processes and methods in accordance with the invention.

P-0041[0041]FIG. 3 depicts a bottom plan view of one embodiment of a gas distribution manifold <b>130</b> and FIG. 4 depicts a cross-section of the manifold <b>130</b> taken along line <b>4</b>-<b>4</b> in FIG. 3. The manifold <b>130</b> comprises a distribution plate <b>300</b> defining a plurality of conduits <b>302</b> and <b>304</b> that connect the reactant gas lines <b>126</b> and <b>128</b> to the nozzle assemblies <b>120</b>A-<b>120</b>F. The conduits <b>302</b> and <b>304</b> extend radially from the inlet ports <b>306</b> and <b>308</b> to the outlet ports <b>310</b> and <b>312</b>. The conduits <b>302</b> and <b>304</b> are fabricated at different levels within the plate <b>300</b> to maintain isolation of the gases that are carried to each station. A third inlet port (not shown) may be used to supply a purge gas from the purge gas line <b>116</b> to one or more of the nozzle assemblies. Alternatively, the purge gas may be coupled to either port <b>306</b> or <b>308</b>, or both, using a valve within the gas supply <b>170</b>. As such, purge gas could be continuously supplied and reactant gas could be “switched” in using a valve to form a burst of reactant gas in the purge gas flow. In a further alternative embodiment, each individual nozzle assembly could be supplied with a different gas, i.e., six inlet ports could be coupled to six outlet ports to supply a different gas to each of the six nozzle assemblies <b>120</b>A-<b>120</b>F. The manifold can be designed to couple any number of reactant and purge gas conduits to any number of outlet ports.

P-0042[0042]FIG. 5 depicts a cross-sectional view of a nozzle assembly, e.g., assembly <b>120</b>A. The nozzle assembly <b>120</b>A comprises a conduit <b>500</b> and a showerhead <b>502</b>. The conduit <b>500</b> defines a bore <b>504</b> that extends the length of the conduit and sealably couples to outlet port (<b>310</b> or <b>312</b> of FIG. 3). The conduit is generally bolted to the manifold <b>300</b> using an O-ring <b>506</b> to form a gas tight seal between the conduit <b>500</b> and the manifold <b>300</b>. Other techniques for attaching the nozzle assembly <b>120</b>A to the manifold <b>300</b> are readily available and known to those skilled in the art. The showerhead <b>502</b> comprises a plenum <b>508</b> for distributing gas from the bore <b>504</b> to a plurality of apertures <b>510</b>. The pattern of the apertures <b>510</b> is designed to uniformly supply gas across a wafer (as discussed below). In some embodiments of the invention, a showerhead may not be used and the bore <b>504</b> may be terminated with a spray nozzle.

P-0043[0043]FIG. 9 depicts a vertical, cross-sectional view of another embodiment of a nozzle <b>900</b> and FIG. 10 depicts a plan view of the nozzle <b>900</b>. The nozzle <b>900</b> comprises a plurality of zones <b>902</b>, <b>904</b>, <b>906</b> through which different gases may be dispensed. In some instances, such as in a CVD mode that will be discussed with reference to FIG. 12 below, all the zones may supply the same gas to a processing station.

P-0044[0044] Each zone <b>902</b>, <b>904</b>, and <b>906</b> comprises a plurality of conduits <b>908</b>, <b>910</b>, and <b>912</b> that are each coupled to respective plenums (shown in phantom as <b>924</b>, <b>926</b>, and <b>928</b>) that distribute gas to at least one respective port <b>914</b>, <b>916</b>, <b>918</b> located in the faceplate <b>922</b>. Gases that are supplied by a manifold (similar to the manifold in FIGS. 3 and 4 that has been adapted to distribute a plurality of gases to the nozzles) to each conduit <b>908</b>, <b>910</b> and <b>912</b> flows to the port(s) <b>914</b>, <b>916</b> and <b>918</b> in each respective zone <b>902</b>, <b>904</b>, and <b>906</b> without mixing. Although the embodiment shown has a plurality of ports linearly arranged in each zone, other arrangements such a single port having a circular or rectangular shape (i.e., a slot), a two dimensional array of ports, combinations of port shapes and the like may be used and are considered to be within the scope of the invention. Furthermore, the embodiment shown depicts three zones, however, more or less zones are contemplated as being within the scope of the invention. Also, each zone may have a different shape or size of the port arrangement to tailor the ports to the type of gas and a desired gas disbursement pattern.

P-0045[0045] In operation, the wafer <b>200</b>, positioned on the rotating platen, moves in a direction represented by arrow <b>920</b> beneath the nozzle <b>900</b>. In this manner, as few as a single multi-zone nozzle can be used to deposit a film upon a plurality of wafers. However, to increase wafer throughput a plurality of nozzles is generally used.

P-0046[0046] As a wafer moves beneath the nozzle <b>900</b>, the gas G₁from port <b>914</b> is adsorbed by the wafer <b>200</b> as the wafer passes beneath the port <b>914</b>. The amount of gas applied to the wafer is defined by the speed of rotation of the platen. As the wafer moves beneath port <b>916</b>, a second gas G₂is applied to the wafer. Then, as the wafer <b>200</b> moves beneath port <b>918</b>, a third gas G₃is applied to the wafer. In one embodiment of the invention, gases G₁and G₃are reactive gases and gas G₂is a purge gas. If, for example, gas G₁were silane, gas G₃were tungsten hexafluoride and gas G₂was Argon, then gas G₁would be adsorbed first, gas G₂would remove any excess silane from the wafer surface, and lastly gas G₃would provide tungsten to react with the silane to form a thin tungsten film on the wafer. A detailed process description is described with respect to FIG. 13 below.

P-0047[0047]FIG. 11 depicts a plan view of another embodiment of a faceplate <b>1108</b> of a nozzle <b>1116</b>. In this embodiment, each gas exits the faceplate <b>1108</b> through zones <b>1102</b>, <b>1104</b>, and <b>1106</b> defined by gas disbursement channels <b>1110</b>, <b>1112</b>, and <b>1114</b>. The channels <b>1110</b>, <b>1112</b>, and <b>1114</b> are arcuate, where the arc of each channel is similar to the arc of the edge of a substrate (wafer) that is being processed. The peak of each arc (along line <b>1118</b>) is aligned with the path of the wafer beneath the nozzle <b>1116</b> on the rotating platen. Such arcuate channels <b>1110</b>, <b>1112</b> and <b>1114</b> are intended to supply gas uniformly to the substrate such that all points on the substrate in an arcuate swath are exposed to the gas simultaneously. As with the previous embodiment, the disbursement channels are merely examples of a type of distribution ports. Those skilled in the art will understand that the channels could be replaced with holes, arrays of holes, holes of various shapes, or combination of holes and channels. The size and shape of each zone may be tailored to the dispersion rate, adsorption dynamics, process parameters, device or substrate topography and gas residence times desired for each particular gas.

P-0048[0048]FIG. 12 depicts a dual plumbed, gas distribution system <b>1200</b> to be used with the multi-zone gas nozzles <b>900</b>/<b>1116</b>. The system <b>1200</b> comprises three gas supplies <b>1202</b>, <b>1204</b>, and <b>1206</b>, a plurality of mass flow controllers (MFC) <b>1208</b>, <b>1210</b>, <b>1212</b> and <b>1214</b>, a plurality of two position valves <b>1216</b>, <b>1218</b>, <b>1220</b>, a plurality of gas splitters <b>1222</b>, <b>1224</b>, and <b>1226</b> and a premix chamber <b>1228</b>. The intent of the system is to permit gases from each supply <b>1202</b>, <b>1204</b> and <b>1206</b> to be provided to the lines <b>1230</b>, <b>1232</b>, and <b>1234</b> that carry gas to the nozzles <b>900</b>/<b>1116</b> as well as allowing premixed combinations of gases to be provided to one or more of the lines <b>1230</b>, <b>1232</b>, <b>1234</b>. For example, a single gas can be supplied to each line in an ALD mode or a premixed combination of gases may be simultaneously supplied to all the lines in a CVD mode.

P-0049[0049] In an ALD mode, gas from supply <b>1202</b> is coupled through a gas splitter (a T-coupler) <b>1222</b> to the MFC <b>1208</b>. The MFC <b>1228</b> meters the amount of gas that is supplied to the two-position valve <b>1216</b>. In a first position, the valve <b>1216</b> directs the gas from the MFC <b>1208</b> to the line <b>1230</b>. Similarly, in an ALD mode, gas supply <b>1206</b> provides gas through the MFC <b>1214</b> to the two-position valve <b>1220</b> and to line <b>1234</b>. Also in the ALD mode, gas supply <b>1204</b> is coupled through a two-position valve <b>1218</b> to line <b>1232</b>. In this manner, metered amounts of gas are supplied separately to each zone of the nozzles. The dosing of the wafer can be synchronized with the rotation of the platen. As is described further with reference to FIG. 6 below, each station <b>202</b>A-<b>202</b>F of FIG. 2 deposits a pair of gases as needed to complete a single deposition of a layer. The thickness of the layer may be controlled by the speed of rotation of the platen. The repeated rotation of the platen causes additional layers to be accumulated with each pass of the wafer under a multi-zone nozzle. Consequently, the process can be used for high conformity deposition of seed layers and bulk fill of materials.

P-0050[0050] In a CVD mode, gas from supplies <b>1202</b> and <b>1206</b> is coupled through splitters <b>1222</b> and <b>1224</b> to MFCs <b>1210</b> and <b>1212</b> and into the premix chamber <b>1228</b>. In the premix chamber, the gases are caused to mix. Generally, these gases are reactants that will react when they are exposed to a heated substrate, i.e., a silane and tungsten hexafluoride reaction to produce tungsten. The mixed gases are coupled from the premix chamber <b>1228</b> through a three-way splitter to a second input port of valves <b>1216</b>, <b>1218</b> and <b>1220</b>. Through manipulation of the valves <b>1216</b>, <b>1218</b>, and <b>1220</b> into a second valve position, the premixed gases may be applied to one or more (including all) the zones of the multi-zone nozzles <b>900</b>/<b>1116</b>.

P-0051[0051] As such, the multi-zone nozzle may be used for both ALD and CVD deposition as disclosed in detail with respect to FIG. 13 below. In short, the apparatus of FIG. 1 may deposit an ALD film using the multi-zone nozzle to form a highly conformal seed layer and then switch to the CVD mode to complete a bulk fill process without stopping the rotation of the platen. As such, considerable throughput performance improvement is achieved. In addition, different reactants could be used during seed and bulk deposition. For example, in an illustrative WF₆chemistry, the ALD mode may use WF₆and B₂H₆to form a first tungsten layer and then switch to WF₆and SiH₄to form a second tungsten layer over the first layer. The second layer will bulk fill a feature with tungsten. The first layer may be a nucleation layer or seed layer. Such a technique would require additional gas supplies and plumbing to adapt the gas distribution system of FIG. 12 to supply the various gases to the nozzles. This WF₆chemistry is illustrative of one possible chemistry, it is to be appreciated that other chemistries may be used.

P-0052[0052]FIG. 6 depicts a schematic diagram of a single station <b>140</b>A of the apparatus <b>100</b> of FIG. 1. The station <b>140</b>A comprises a nozzle assembly <b>120</b>A, a wafer support <b>206</b>A, and a pair of purge curtain distributors <b>204</b>A, <b>204</b>F. The nozzle assembly <b>120</b>A is coupled to a reactant gas supply <b>600</b> (and, possibly, also a purge gas supply <b>602</b>) and the purge curtain distributors <b>204</b>A, <b>204</b>F are coupled to a purge gas supply <b>602</b>. If the nozzle is a multi-zone nozzle, then it is coupled to a plurality of gas supplies such as shown in FIG. 12.

P-0053[0053] The wafer support <b>206</b>A may comprise an electrode <b>604</b> and an embedded temperature control element <b>606</b>. The electrode <b>206</b>A is coupled to a voltage supply <b>608</b> that applies a voltage to the electrode and the wafer (to facilitate chucking of the wafer <b>200</b> by electrostatic force). Alternatively, a clamp ring or vacuum could be used to retain the wafer <b>200</b> on the support <b>206</b>A.

P-0054[0054] The temperature control element <b>606</b> may be a resistive heater element that is coupled to a heater power supply <b>610</b>. The temperature element <b>606</b> could also be a fluid jacket or some other temperature control element. The temperature control element <b>606</b> is energized to maintain the wafer <b>200</b> at a predefined temperature. Alternatively, or in addition to the embedded element <b>606</b>, one or more heater lamps <b>616</b> and a lamp heater power supply <b>618</b> may be used to heat the wafer <b>200</b>. If a process required wafer cooling, then the temperature control element <b>606</b> would be a cooling plate or element. The wafer support could contain both a heating and cooling element that can be used to selectively heat or cool a wafer. Furthermore, external energy sources such as a laser, a microwave power source, or a RF power source may be used in pulse or steady state mode to activate the precursor used in the reaction, i.e., additional energy sources can be used to activate oxygen in the formation of Al₂O₃using an ALD technique.

P-0055[0055] In operation, using a single zone nozzle, the wafer is positioned on the support <b>206</b>A and retained. A reactant gas (e.g., silane) is supplied to the nozzle assembly <b>120</b>A. The gas is typically supplied as a short pulse or burst of gas <b>612</b> that exits the showerhead <b>502</b> proximate the wafer <b>200</b>. Alternatively, a continuous flow of purge gas may be supplied from gas supply <b>600</b> and intermittent bursts of reactant gas may be injected into the continuous flow of purge gas using a valve <b>620</b>. The temperature of the wafer <b>200</b> is maintained by the temperature control element <b>606</b> to facilitate adsorption of the silane on the surface of the wafer <b>200</b>. Purge gas is continuously supplied to the purge curtain distributors <b>204</b>A and <b>204</b>B such that a curtain <b>614</b>A and <b>614</b>F of purge gas is formed on either side of the wafer support <b>206</b>A. The curtains <b>614</b>A and <b>614</b>F ensure that the reactant gas <b>612</b> is constrained to a volume near the wafer support <b>206</b>A.

P-0056[0056]FIG. 7 depicts a flow diagram of a method <b>700</b> of operation for the apparatus <b>100</b> as controlled by controller. The method <b>700</b> represents the operation of the apparatus <b>100</b> for depositing a tungsten layer upon a semiconductor wafer using a reaction between SiH₄and WF₆. In this example, the tungsten deposition is repeated three times (i.e., one pass through a six station ALD apparatus <b>100</b>) to form a relatively thin tungsten layer. To increase the thickness, a wafer may be repeatedly processed by the six stations.

P-0057[0057] The method <b>700</b> begins at step <b>702</b> and proceeds to step <b>704</b> wherein the purge gas curtains are formed between the stations. These curtains are maintained throughout the remaining steps of the method. At step <b>706</b>, wafers are loaded onto each wafer support to fill all the wafer processing positions. Each position is defined by a nozzle assembly, i.e., position <b>1</b> is beneath nozzle assembly <b>120</b>A, position <b>2</b> is beneath nozzle assembly <b>120</b>B, and so on. In step <b>706</b>, as each wafer is loaded, a retention force is applied to retain the wafer on the support. At step <b>708</b>, the wafer temperature is set at each position, then at step <b>710</b>, a pulse of SiH₄is applied to the wafer in positions <b>1</b>, <b>3</b> and <b>5</b>. After the gas is applied at positions <b>1</b>, <b>3</b><b>5</b>, the platen is turned, at step <b>712</b>, to the next position. At step <b>714</b>, a pulse of WF₆is applied to the wafers in positions <b>2</b>, <b>4</b> and <b>6</b>. At step <b>716</b>, the method queries whether the processing is to continue. If the query is affirmatively answered, steps <b>708</b>-<b>714</b> are repeated to deposit another tungsten layer, e.g., a mono-layer. If the query is negatively answered, the wafers are unloaded at step <b>718</b> and the method stops at step <b>720</b>. The foregoing process is described having the steps of the process performed in sequential order, however, one or more of the steps may be performed simultaneously and such a process is considered to be within the scope of the invention.

P-0058[0058] Alternatively, wafers may be loaded one at a time into the apparatus. As each wafer is loaded, the temperature can be set and the silane adsorbed upon the wafer. After the platen is rotated, the WF₆may be applied to the wafer, and a new wafer positioned at position <b>1</b> for silane adsorption. As each new wafer is added to the apparatus, a process can be accomplished at each position. Once all the positions are filled with wafers, the processing may be applied at each position as the platen is rotated.

P-0059[0059] After a pass through the method <b>700</b>, both reactant gases (e.g., SiH₄and WF₆) have been dispensed over the wafer substrates <b>306</b> in short bursts. After each burst of reactant gas, a purge gas such as argon may be applied through each nozzle assembly or the purge gas may be continuously applied. As such, steps <b>710</b> and <b>714</b> may each be followed by a flow of purge gas. Reactant gases are prevented from mixing outside their respective stations by the purge gas curtains. The aforementioned method steps <b>708</b> through <b>714</b> may be repeated between 10 and 50 cycles in order to achieve a desired deposition of thickness of tungsten on the wafer.

P-0060[0060] Other processing methods may be employed by this embodiment of the invention. One such method is to continuously flow reactant gases (and/or purge gases) from the nozzle assemblies while separating the stations with the inert gas purge curtains. The platen would be continuously rotated such that a different reactant gas would be applied to a wafer at each position for a time period defined by the rotation speed of the platen. Employing this processing method, less than 30 cycles may be required before the desired deposition thickness is formed on the wafers. To enhance wafer throughput, the platen rotation speed may be modulated in a sinusoidal pattern such that rotation is slowed as a reactive gas is being applied and rotation speed is increased when the wafers are passing through a purge gas curtain.

P-0061[0061] In a further embodiment of the invention, the stations may be adapted to perform a complete metallization step as well as other integrated circuit fabrication process. For example, positions <b>1</b> and <b>2</b> could be used to deposit a first tungsten layer by having a wafer repeatedly visit position <b>1</b> for a SiH₄application and position <b>2</b> for a WF₆application. Once a first layer is complete, the wafer can be moved to position <b>3</b> where a hydrogen reduced tungsten bulk deposition process could be performed to deposit a second layer upon the first layer. Stations <b>4</b>, <b>5</b> and <b>6</b> could be used for processing a second set of wafers in a similar manner.

P-0062[0062] In another embodiment of the invention using single zone nozzles, each station is supplied with both reactant gasses and a purge gas. Each reactant gas is simultaneously applied to a wafer synchronously, while the wafer is stationary. The gases are applied using an ALD technique of short bursts of gas followed by purge gas application. For such synchronous operation with the same gas being applied at all stations simultaneously, the purge gas curtains may be unnecessary. To complete a metallization process, bulk deposition at all the stations may follow the ALD deposition process.

P-0063[0063] Furthermore, the process may be adapted to load all the wafers into the apparatus, set the process temperature and then soak all the wafers in a first soaking gas. Such an initial process may deposit a silicide layer (e.g., titanium silicide), upon the wafer. The silicide layer deposition is followed by a purge step where a purge gas is applied to the wafers through all the nozzles. Thereafter, a first reactant gas is supplied through all the nozzles as the platen rotates, followed by an application of a second reactant gas. Another reactant gas or a purge gas may be applied prior to the process ending. In this manner, the apparatus is capable of deposing a first and second layer, where, for example, a silicide layer can be deposited prior to depositing a nucleation layer.

P-0064[0064]FIG. 13 depicts a flow diagram of a process <b>1300</b> for depositing a layer using a multi-zone nozzle. As one embodiment of the process, the process is described as used to deposit a first tungsten layer using an ALD mode, followed by an optional tungsten bulk fill process using a CVD mode. Those skilled in the art will realize that the process <b>1300</b> may be adapted to use various other gases to deposit other films.

P-0065[0065] The process <b>1300</b> begins at step <b>1302</b> and proceeds to step <b>1304</b> wherein the purge curtains are formed. At step <b>1306</b>, the wafers are loaded onto the wafer supports. At step <b>1308</b>, the apparatus <b>100</b> establishes an appropriate wafer temperature for each wafer. At step <b>1310</b>, the platen is rotated and the various gases are applied to the multi-zone nozzles. In one embodiment, the first zone encountered by the wafer as it rotates into each station delivers silane, the second zone delivers a purge gas and the third zone delivers tungsten hexafluoride. As the wafer passes beneath the nozzles that disperse these gases, the process operating in the ALD mode forms a first tungsten layer. The rotation speed of the platen can be adjusted to increase or decrease the thickness of the deposited layer. At step <b>1312</b>, the process <b>1300</b> queries whether the ALD mode processing is complete. If the query is negatively answered the process continues to rotate the platen and apply the gases to continue to form the first layer. The more stations that a wafer passes through, the thicker the first layer becomes.

P-0066[0066] When the query of step <b>1312</b> is affirmatively answered, the process proceeds to the query in step <b>1320</b>. The query in step <b>1320</b> requests whether an optional bulk deposition process is to be initiated using a CVD mode. If the query of step <b>1314</b> is negatively answered, the process continues to step <b>1320</b> where the wafers are removed from the apparatus and the process is stopped at step <b>1322</b>. However, if the query is affirmatively answered, the process <b>1300</b> proceeds to step <b>1316</b>. At step <b>1316</b>, the platen is rotated while gases are applied that will bulk fill the features on the wafer i.e., a second layer is deposited upon the first layer. The bulk fill process may be a CVD process wherein one or more zones has a mixture of gases applied to the multi-zone nozzle. The mixed gases, for example, WF₆and SiH₄, do not react in the gas phase such that they can be mixed and supplied to the wafer simultaneously. The gases react with one another upon the heated wafer surface to form a tungsten layer. At step <b>1218</b>, the process queries whether the CVD process is complete. If the query is negatively answered, the process continues the CVD deposition. Otherwise, the process removes the wafers at step <b>1320</b> and stops at step <b>1322</b>.

P-0067[0067] Although the foregoing description of the method describes the process steps as performed in a sequential order, some of the steps may be performed simultaneously or in a different order to deposit one or more layers of material in accordance with the invention. Furthermore, the apparatus <b>100</b> can also be used to deposit layers of material separately using either the CVD mode or the ALD mode.

P-0068[0068] Referring to FIG. 8, another embodiment of the present invention is shown, wherein the gas distribution system <b>804</b> radiates outward from a central hub <b>830</b> that is mounted to a rotating platen assembly <b>802</b>. In this embodiment, as in the previous, a wafer transfer module <b>180</b>, including a wafer transfer robot (not shown), is coupled to the apparatus <b>800</b>. The apparatus <b>800</b> is comprised of a rotating platen assembly <b>802</b> and a gas distribution system <b>804</b>.

P-0069[0069] The platen assembly <b>802</b> comprises a plurality of wafer supports <b>810</b>A-<b>810</b>E and rotates, for example, in the direction of the arrow <b>814</b>. The platen <b>802</b> and wafer supports <b>810</b>A-<b>810</b>E are similar to platen <b>102</b> and supports <b>206</b>A-<b>206</b>F of FIG. 2. As such, the platen and its supports shall not be described further. During processing, the platen may rotate to position the wafers beneath the gas sources or, alternatively, the platen may be stationary and the gas sources may be moved into position above the wafers.

P-0070[0070] The gas distribution system <b>804</b> comprise a plurality of arms or wands <b>812</b>, <b>822</b>, <b>824</b> and <b>826</b>, hereinafter referred to as gas dispensing arms, that transmit gas from the central hub <b>816</b> to a region above the wafers. Although four arms are depicted, more or less arms may be used depending upon the processes that are to be performed. The gas dispensing arms <b>812</b>, <b>822</b>, <b>824</b> and <b>826</b> may, for example, rotate above the platen in a direction that is opposite to the direction of rotation of the platen assembly <b>802</b>. The gas dispensing arms <b>812</b>, <b>822</b>, <b>824</b> and <b>826</b> may also rotate in an indexed manner, i.e., rotate using an intermittent rotational movement wherein the arms rotate into alignment with a particular wafer, stop, dispense gas, and then move to another wafer location.

P-0071[0071] The gas dispensing arms <b>812</b>, <b>822</b>, <b>824</b> and <b>826</b> project from a series of stacked gas manifolds <b>840</b> that form a portion of the central hub <b>816</b>. The manifolds <b>840</b> may rotate at different rates of speed independent of each other. Each segment of the manifold is stacked upon the other segments with one or more of the gas dispensing arms <b>812</b>, <b>822</b>, <b>824</b> and <b>826</b> projecting from the sides or top of the hub <b>816</b>. A series of nozzles <b>820</b> are located along the bottom of each of the gas dispensing arms <b>812</b>, <b>822</b>, <b>824</b> and <b>826</b> near the end thereof to allow gas to exit from the respective gas dispensing arms. The nozzles <b>820</b> are designed to project the gas downward at the substrate support <b>810</b>A-<b>810</b>F. The gas dispensing arms <b>812</b>, <b>822</b>, <b>824</b> and <b>826</b> are coupled to a gas supply <b>828</b> via gas supply lines <b>832</b>, <b>834</b> and <b>836</b>. Each gas-dispensing arm <b>812</b>, <b>822</b>, <b>824</b> and <b>826</b> may contain a different reactant gas or inert gas for use in the atomic layer deposition process.

P-0072[0072] In practice, wafers <b>806</b> are transferred from the wafer transfer module <b>180</b> by the wafer transfer robot (not shown) onto the wafer supports <b>810</b>A-<b>810</b>E. The wafer supports <b>810</b>A-<b>810</b>E secure the wafers <b>806</b> so as to prevent movement. Once secured, the wafer supports <b>810</b>A-<b>810</b>E are indexed until all the stations are loaded. A gas-dispensing arm <b>812</b>, <b>822</b>, <b>824</b> or <b>826</b> is queued to pass over at least one of the wafer supports <b>810</b>A-<b>810</b>E. As the gas-dispensing arm <b>812</b>, <b>822</b>, <b>824</b> or <b>826</b> passes over at least one of the wafer supports <b>810</b>A-<b>810</b>E, the arm <b>812</b>, <b>822</b>, <b>824</b> or <b>826</b> dispenses a first reactant gas (e.g., silane) over the wafer <b>806</b>, beginning the ALD process. The wafers <b>806</b> will adsorb some of the reactant gas and the rest will be purged away by an inert gas supplied by another gas dispensing arm passing over the wafer support. Subsequently, a second reactant gas dispensing arm <b>812</b>, <b>822</b>, <b>824</b> or <b>826</b> moves over the top of the wafer supports <b>810</b>A-<b>810</b>E and dispenses a second reactant gas (e.g., WF₆).

P-0073[0073] The second reactant gas reacts with the adsorbed gas on the wafer <b>806</b> to form a thin film on the wafers <b>806</b>. Another one of the gas dispensing arms <b>812</b>, <b>822</b>, <b>824</b> or <b>826</b> that dispenses an inert purge gas is also caused to rotate over the wafer supports <b>810</b>A-<b>810</b>E dispensing inert gases so as to prevent the accumulation of the reactant gas proximate the wafers. The inert gas may also be dispensed in intervals so as to prevent stray reactant gases from contaminating other wafers <b>806</b> on the substrate supports <b>810</b>A-<b>810</b>E. Purge gas could be supplied continuously from all the arms and intermittent bursts of reactant gas may be coupled to the appropriate arm at an appropriate time.

P-0074[0074] The rotational motion of the platen assembly <b>802</b> during processing may be continuous, intermittent (indexed) or stationary. The motion of the gas distribution arms <b>812</b>, <b>822</b>, <b>824</b> and <b>826</b> may be continuous, intermittent or the arms may be stationary. Generally speaking, either the arms or the platen rotate relative to one another to facilitate gas application to the wafers. If the arms are rotatable, each gas-dispensing arm <b>812</b>, <b>822</b>, <b>824</b> and <b>826</b> in one embodiment of the invention rotates independent of the others as well as being independent of the platen rotation. In another embodiment, the arms may rotate in unison. Each of the gas dispensing arm's movements may be adjusted so as to achieve optimum performance during the atomic layer deposition process. For example, the movement may be modulated in a sinusoidal manner to slowly rotate the arms as gas is being dispensed and rapidly rotate the arms as the arms are being moved into position over the next wafer.

P-0075[0075] As described above, the apparatus and method according to the present invention is more efficient and effective compared to the conventional, single chamber apparatus and methods. Therefore, layers of material formed on wafers by the present invention are more uniform and more quickly produced than by other methods.

P-0076[0076] Although various embodiments that incorporate the teachings of the present invention have been shown and described herein. Those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings.