Forming titanium nitride layer on substrate using CVD

The invention relates to a process for preparing strength of titanium nitride layers with a nearly 100% Edge coverage, using a CVD Traversing ens with specially selected Prekusoren. The inventions furthermore relates to titanium nitride layers with egg ner almost 100% step coverage.

Titanium nitride layers have been due to their recorded properties as a diffusion barrier in scale integrated circuits, a central importance tion. In the prior art, therefore, have so far also Numerous processes for the deposition of titanium nitride layers on substrates using ver different Prekusoren and different method conditions described. is the method, taken the approach that the layers by means of a CVD process, preferably by means of a plasma assisted CVD process can be prepared. This here investigated at most and precursor used is the tetrakis (dimethylamido) titanium (DMATi).

In a recent study by A. Weber et al, in J. Electrochem. Soc., Vol. 141, Nr. 3, March 1994 on the deposition of titanium nitride, under USAGE tion of DMATi, by means of an ECR plasma process at Substrate temperatures in the range of 100 to 600 ° C. In This publication, in particular the influence of the Substrate temperature described.

In DE 41 32 560 also discloses a process, for plasma-assisted deposition of layers from the Gas phase (PECVD), be a microwave excitation wrote. This procedure shall include among others serve the step coverage of the deposited increasing layer.

However, it has now been found that with the method of the prior art, only an insufficient edges can be reached covering. The edge coverage However, particularly for the use of titanium nitride as adhesives, contact and barrier layer in höchstin tergrierten circuits of the utmost importance. For the function as a diffusion barrier must namely that Layer with high conformity deposited Who the.

Assuming it is therefore the object of the prior invention, a novel method and corre to provide sponding layers available, a almost as complete as possible edge coverage allowed union.

The object is according to the method by the characterizing nenden features of claim 1, in view of the Titanium nitride layers by characterizing Watch male of claim 9, dissolved.

The sub-claims show advantageous Weiterbildun gen on.

According to the invention is therefore to proceed such that from finally with titanium alcoholates as precursor a Remoteplasma- or plasma downstream process gear processed is. Surprisingly, it has been found that if such process conditions met be, titanium nitride layers are produced Kings NEN, the aufwei a nearly 100% step coverage sen. This is obviously due to the fact that when plasmagestützen Down invention stream or remote procedure an almost selective Cleavage of the alkoxide occurs. Also favorable continued to the low chemical reactivity of the Ti tanalkoholate, since thus the film formation process slower than in the precursors of Stan the art and the layer-forming species such have enough time to surface diffusion. It has shown that described above with this surrounded process, even a step coverage of 100% can be achieved. Also advantageous in which he The method according to the invention is that the Titanalkohola te non-toxic and the reaction products not kor are rosiv.

As alkoxides can inventively all Alko alkoxides of the formula Ti (OR) ₄ used who the wherein R is an alkyl group. Especially before given to it, if the alkyl residue is selected from the group -CH₃, -C₂H₅, n-C₃H₇, i-C₃H₇, n-C₄H₉, i-C₄H₉, t- C₄H₉. Very particularly preferred is the use of of isopropylate.

When the nitrogen-containing plasma gases it is before given to when either ammonia or Stick substance is. The use of a nitrogen-containing Plas magases the novel process is zwin quietly, since the precursor employed yes no nitrogen contains. This measure has been of A. We ber et al Electrchem in (J. Am. Soc., Vol. 141, Nr. 3 March 1994) noted, which is determined, that the nitrogen of the titanium nitride layer exclusively Lich from the plasma gas and not the precursor comes.

Preferably in the present process it is if, in addition, an excitation of the plasma either, by means of high frequency wave or micro wave with len, with or without magnetic field amplification or with Help an electron cyclotron resonance (ECR) mode, takes place. Advantageously, the Abscheidetem temperatures in the range of 100 to 600 ° C.

Substrates can all of the prior art, known for chemical vapor deposition processes, employed who the. Examples include silicon, silicon dioxide, Metals, ceramics.

The invention further relates to titanium nitride layers by means of a plasma-assisted CVD Process are produced. The invention Titanium nitride layers are characterized particularly from that it has a nearly 100% step coverage on exhibit and their oxygen and carbon content preferably <2 at%. This surprising result is obviously due to the fact that when inventive manufacturing process, the alkoxide groups are removed and from the reaction chamber be removed, so that the source of oxygen, and Carbon contamination is removed. show order to titanium nitride layers of the invention de NEN, compared to the prior art z. B. the Schich th as in Mayr and Stock (DE 35 12 825 A1), he data sheet, clearly superior. These layers wei sen namely oxygen and Kohlenstoffkontamina tion of <10 at%.

Further features, details and advantages of the inventions will become apparent from the following Description, a preferred embodiment of Invention and from the drawing. Here zei gene:

<b>Fig.</b> 1 the schematic construction of an inventive to the invention apparatus for carrying out the procedural proceedings.

The exemplary apparatus, in accordance with <b>Fig.</b> 1, consists from a recipient <b>1</b>Who here has a height of having 350 mm and a diameter of 500 mm. in the recipients <b>1</b>Is a substrate table <b>2</b>, with a Diameter of 100 mm arranged. The substrate table<b>2</b>, This is a heating supply <b>3</b>, over a management <b>4</b>, In contact so that it at a temperature is up to 1000 ° C acted. About the Sub strattisch <b>2</b> is a gas distribution ring <b>5</b> arranged, in via the feed <b>6</b>supplied, the precursor can be. The recipient<b>1</b> is a Pumpenan order, here turbo molecular pump <b>7</b>Associated with a backing pump <b>8th</b> in communication evacuated. The suction performance of the turbomolecular pump is up to 1500 l / s the of the backing pump to 60 m³ / h. The plasma gas is via the feed line <b>9</b> into the recipient <b>1</b> supplied. In the embodiment of <b>Fig.</b> 1, the Vorrich constructed device that the recipient <b>1</b> with an ECR chamber <b>10</b> is connected, the obe with appropriate reindeer magnet <b>11</b> and lower magnets <b>12</b> is provided. The ECR chamber in turn communicates with a micro wave number generator <b>13</b> appropriate in conjunction, sd Microwaves can be coupled.

With a device as described above was titanium (IV) isopropoxide (heated to 25 ° C) feeding <b>6</b> and the gas distribution ring <b>5</b> in the Recipients introduced. The feeding of the precursor carried out without carrier gas, in the downstream area ECR microwave plasma. When conducted Ver examined the following process conditions were eingehal th:

15 sccm nitrogen2 sccm titanium (IV) isopropoxideMW Power: 400 Wupper magnet: 180 Alower magnet: 120 ASubstrate temperature: 300 ° CPressure: 0.12 Pa100 nm thick TiN layerGrowth rate: 2 nm / minResistivity:. 800 μΩcmLayer composition Ti: 48 at%, N: 48 at%, O: 1.9 at%, C: 1.8 at%Compliance 100% in 1 × 1 micron contact hole.