Method and apparatus for enhanced chamber cleaning

0001The present invention relates to improved methods and devices for increasing chamber cleaning speeds. More specifically, the present invention relates to methods and devices that effectively increase the etching rate of reactive species that etch accumulated material from processing chamber components.

0002The manufacture of liquid crystal displays, flat panel displays, thin film transistors and other semiconductor devices is done in multiple chambers, each designed to perform a specific process on a substrate. Many of these processes result in substances (eg, chemical vapor deposition, physical vapor deposition, thermal vapor deposition, etc.) that are layered on the substrate, etched from the substrate surface, etc. ) Accumulates. Such accumulated material can collapse from the surface of the chamber and enter sensitive devices that are processed inside the chamber. Therefore, the accumulated material must often be cleaned from within the process chamber (eg, every 1 to 6 substrates).

0003An in situ dry cleaning process is preferred for cleaning the chamber surface. In an insitu dry cleaning process, one or more gases dissociate in the treatment chamber into one or more reactive gas species (eg, fluoride ions, radicals). Reactive species clean the chamber surface by forming volatile compounds with substances that have accumulated on the chamber surface. Such an in-situ cleaning process reduces both the number of particles and the system down time required for more interrupted cleaning processes that require the chamber to be opened. Remote Plasma Source Cleaning (RPSC) is a further improvement over In situ Plasma Cleaning. In the RPSC, the wash gas dissociates in another chamber, after which the dissociated reactive species flows downstream into the processing chamber that cleans / etches the material from the chamber surface. Since RPSC completely dissociates the cleaning gas, it can save a lot of money both economically and environmentally. In addition, the RPSC reduces chamber consumables by eliminating the adverse ionic impact associated with the in situ plasma cleaning process.

<p num="0004"><patcit num="1"><text>International Publication No. 00/003064</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 11-281307</text></patcit><patcit num="3"><text>International Publication No. 96/015287</text></patcit><patcit num="4"><text>Japanese Unexamined Patent Publication No. 10-256244</text></patcit></p>

<p num="0005"> Unfortunately, both the in-situ cleaning process and the remote plasma source cleaning process are routinely time consuming and highly gas consuming, as described below. Therefore, unfavorably, the cost per substrate processed in the processing chamber increases. Moreover, in remote plasma source cleaning (RPSC), large variations in cleaning rates are often found between processing chambers cleaned by the same cleaning process. Therefore, there is a need for improved methods and equipment for etching accumulated material from the chamber surface.</p>

<p num="0006"> We have found that the chamber cleaning rate is increased when the surface of the chamber exposed to the reactive species of the cleaning gas is mirror-polished. The chamber surface is preferably untreated, most preferably untreated aluminum. The untreated chamber surfaces used herein are those that have not been pretreated to enhance cleaning (eg, anodized or disclosed in US Patent Application No. 09 / 322,893 filed May 29, 1999. By applying a coating like that). The surface of such a processing chamber already has a good cleaning rate. Mirror polishing is a process that reduces the roughness of some surfaces and thus the surface area. We have two goals by mirror polishing: (i) reducing the surface area of some parts to reduce the total number of sites where the wash radical inactivation process occurs; (ii) binding to the wash radicals. It is believed that the removal of surface impurities, which can be reduced in number, is achieved. Therefore, it is believed that mirror polishing preserves the wash radicals and makes the RPSC effective.</p><p num="0007"> The present invention includes an apparatus for processing a substrate in a chamber and cleaning accumulated material from the chamber components. The device is exposed to reactive species during the cleaning process, as well as a reactive gas species generator adapted to generate reactive gas species that chemically etch the processing chamber and accumulated material from the chamber components. Includes at least one mirror polished surface or component to be made. Preferably, in order to maximize the effect on chamber cleaning efficiency, at least one mirror polishing is the proportion of surface area exposed to large components such as gas distribution plates or backing plates and / or reactive species. Large multiple small components (eg, chamber shadow frame, wall liner, surface area, gas conductance line, etc.).</p><p num="0008"> Mirror-polished surfaces exposed to reactive species not only improve cleaning rates, but can also significantly reduce variations in cleaning speed differences between treatment chambers, significantly increase process chamber throughput, and perform cleaning. The amount of precursor gas required for the cleaning can also be reduced. NF₃It is beneficial to reduce the consumption of precursor gas both economically and environmentally (for example, global warming) because of the high cost associated with such precursor gas. Further, the mirror-polished surface does not introduce dissimilar substances into the processing apparatus and does not have the problem of adhesion experienced by most conventional surface treatments. Other objects, features and advantages of the present invention will be fully apparent from the detailed description of the preferred embodiments below, the claims and the accompanying drawings described above.</p>

0009<figref num="1">It is a side view of the processing apparatus arranged according to this invention.</figref>

0010FIG. 1 is a side view of the processing apparatus 10 arranged according to the present invention. Applied Kamatsu Technology's AKT-1600 PECVD equipment described in U.S. Pat. No. 5,788,778 and incorporated herein by reference, U.S. Pat. No. 5,812,403 and incorporated herein by reference in its entirety. Appropriate processing equipment, such as Applied Materials' GIGAFILL®, thermal deposition chambers, etc., can be modified as described herein. The AKT-1600 PECVD processing apparatus 10 arranged according to the present invention for convenience is shown in FIG. The AKT-1600 PECVD processor 10 is designed for the manufacture of active matrix liquid crystal displays and can be used to deposit amorphous silicon, silicon dioxide, silicon oxynitride or silicon nitride known in the art. ..

0011FIG. 1 will be described. The processing apparatus 10 has a deposition chamber 11 having a gas distribution plate 12 including an aperture 12a-u and a backing plate adapted to send processing gas or cleaning gas to the deposition chamber 11, and a substrate 16 processed in the deposition chamber 11. Includes a susceptor 14 in support of. The susceptor 14 includes a heating element 18 (for example, a resistance heater) coupled to a heater control unit 20 that raises the temperature of the substrate 16 to a processing temperature and maintains the substrate 16 at the processing temperature during processing. The lift mechanism 22 is coupled to the susceptor 14 so that the substrate 16 can be lifted from the susceptor 14 as described below. In particular, a plurality of lift pins 26 (fixed and supported by the lift pin holders 28) penetrate the susceptor 14 (by the plurality of lift pin apertures 30) and come into contact with the substrate 16 when the susceptor 14 is lowered by the lift mechanism 22. , The substrate 16 is lifted from the susceptor 14. The deposition chamber 11 also overhangs the chamber wall liner 29, which can block and remove and clean the material from accumulating on the chamber wall, and the substrate edge, thus accumulating or accumulating material on the substrate edge. Includes a shadow frame 31 to prevent it.

0012In addition to the above functions, the gas distribution plate 12 and the susceptor 14 each function as upper and lower electrodes of parallel plates that generate plasma in the deposition chamber 11. For example, the susceptor 14 can be grounded and the gas distribution plate 12 can be coupled to the RF generator 32 via a matching network 34. Therefore, RF plasma can be generated between the gas distribution plate 12 and the susceptor 14 by applying the RF power supplied by the RF generator via the matching network 34. The vacuum pump 36 is coupled to a deposition chamber 11 that evacuates / pumps before, during, or after processing as required.

0013The processing device 10 further includes a first gas supply device 38 coupled to an inlet 40 of a deposition chamber 11 that supplies processing gas by a backing plate 13 and a gas distribution plate 12. The first gas supply device 38 includes a valve controller system 42 (for example, a computer-controlled mass flow controller, a flow meter, etc.) coupled to the inlet 40 of the deposition chamber 11, and a plurality of process gas sources 44a coupled to the valve controller system 42. Contains 44b. The valve controller system 42 regulates the flow rate of the processing gas to the deposition chamber 11. The individual processing gas used depends on the material deposited in the deposition chamber 11.

0014In addition to the first gas supply device 38, the processing device 10 supplies cleaning gas (eg, to remove accumulated material from various inner surfaces of the chamber 11) during cleaning of the deposition chamber 11 (gas). It includes a second gas supply device 46 coupled to the inlet (via the conductance line 48). The second gas supply device 46 is a precursor gas source 52 and a small amount carrier gas source 54 coupled to the remote plasma chamber 50 and the remote plasma chamber 50 coupled to the gas conduction line 48 via the valve controller system 56 and the valve controller system 58, respectively. Includes. A typical precursor cleaning gas is NF, which is well known in the art.₃, CF₄, SF₆, C₂F₆, CCl₄, C₂Cl₆Etc. are included. If a small amount of carrier gas is used, it may contain a non-reactive gas compatible with the cleaning gas used (eg, argon, helium, hydrogen, nitrogen, oxygen, etc.). The precursor carrier gas source and the low volume carrier gas sources 52, 54 may include, if desired, a single gas source containing a suitable mixture of the precursor carrier gas and the low volume carrier gas.

0015The high power source generator 60 (eg, microwave or RF generator) is used to ignite and maintain the plasma within the remote plasma chamber 50, where the cleaning gas dissociates into active cleaning chemicals / radicals (as described below). ) Power the remote plasma chamber 50. It is preferred that the flow restrictor 62 be arranged along the gas conductance line 48 so that a pressure difference can be maintained between the remote plasma chamber 50 and the deposition chamber 11.

0016During cleaning of the deposition chamber 11, precursor gas is sent from the precursor gas source to the remote plasma chamber 50. The flow rate of the precursor gas is set by the valve controller system 56. The high power generator 60 sends power to the remote plasma chamber 50 to activate the precursor gas to form one or more reactive species (eg, fluorine radicals) that travel to the deposition chamber 11 by the gas conductance line 48. .. In this way, the remote plasma chamber 50 functions as a "reactive species generator" that binds to the deposition chamber 11 and sends reactive species. It should be noted that the susceptor 14 and the gas distribution plate 12 also act as reactive species generators coupled to the deposition chamber 11 because the applied RF power can dissociate the precursor gas.

0017One or more reactive species generated by the remote plasma chamber 50 travel through the inlet 40, the backing plate 13, and the gas distribution plate 12 to the deposition chamber 11. A small amount of carrier gas is used to assist in transporting one or more reactive species to chamber 11 and / or plasma initiation in the deposition chamber if chamber cleaning or RF plasma is used during chamber cleaning / A small amount of carrier gas source 54 can be supplied to the remote plasma chamber 50 to aid in stabilization.

0018NF₃Specific cleaning process parameters for the deposition chamber 11 when precursor cleaning gas is used include a precursor gas flow rate of about 2 liters per minute and a deposition chamber pressure of about 0.5 torr. Microwave power of 3-12kW, preferably 5kW, is NF₃It is supplied to the remote plasma chamber 50 by a high power microwave generator to activate the precursor gas. Preferably, the remote plasma chamber 50 is maintained at a pressure of at least 4.5 torr, preferably about 6 torr. Other cleaning process parameter ranges / chemical properties are described in previously incorporated US Pat. No. 5,788,778.

0019As mentioned above, problems common to conventional cleaning processes include low cleaning rates and large variations in cleaning speed differences between process chambers. We found that the variation in cleaning rate and the difference in cleaning rate between chambers depends on the condition of the inner surface of the chamber, and that the remote plasma source (eg, remote plasma chamber 50) and the chamber (eg, deposition chamber 11) (" It was discovered that the inner surface between "downstream surfaces") affects the cleaning rate. In particular, the surface-controlled inactivation process binds reactive species used during cleaning (eg, etching active species such as F radicals) and does not assist in chamber cleaning (eg, F radicals). In the case of F₂) Is considered to be formed. This surface-controlled inactivation process appears to occur on untreated material surfaces, including both bare aluminum and anodized aluminum surfaces.

0020We have found that by mirror polishing one or more untreated downstream components, high cleaning rates are achieved and variations in cleaning rate differences between chambers are significantly reduced. Mirror polishing components that may significantly affect cleaning performance include chamber gas distribution plates and backing plates. A percentage of the chamber components must be mirror-finished to affect the improvement in chamber cleaning speed. This percentage may vary, but a high percentage is preferred to achieve high speed cleaning rates, with 100% mirror polishing of the untreated exposed surface being most preferred. By using the RF plasma with the remote plasma source in the processing chamber, that is, by supplying power to the electrode 12 to form a gas of radicals entering from the remote plasma source, or by secondarily introducing a cleaning gas into the plasma. It should be noted that by doing so, an increase in cleaning rate (eg, up to 15%) can be achieved. However, the application of RF power must be limited to avoid damage to the processing chamber components due to ionic impact.

0021The processing device 11 of FIG. 1 will be described. The exposed surface or surface of one or more downstream components of the treatment apparatus 11 so as to affect the increase in cleaning rate and the reduction in the variation in cleaning rate difference between the deposition chamber 11 and other deposition chambers (not shown). The untreated surface is mirror-polished (mirror-polished surface 64). Mirror polishing is a process known to those of skill in the art and is commonly used to polish optical lenses and semiconductor substrates. Mirror polishing usually requires a pad that is in contact with and relative to the surface to be polished to be coated with an abrasive slurry.

0022As shown in FIG. 1, the inner surfaces of the deposition chamber 11, gas distribution plate 12, backing plate 13, susceptor 14, inlet 40, gas conductance line 48, chamber wall liner 29 and shadow frame 31 are mirror-polished surfaces 64. .. If desired, fewer components may be mirror-polished. However, the most advantageous coating of the mirror-polished surface 64 appears to be on the bare aluminum surface, as the bare aluminum surface cannot be successfully treated with a coating that enhances cleaning efficiency (slicing / peeling). .. Because mirror polishing of anodized aluminum (eg, customarily susceptors and shadow frames are anodized aluminum) can remove the anodized layer and thus interfere with the deposition process or cause an arc. It is not recommended.

0023The PECVD deposition chamber 11 of FIG. 1 will be described. The mirror-polished surface 64 significantly increases the cleaning rate and significantly reduces the variation in the difference in cleaning rate between chambers, without processing drift or changes in the properties of the PECVD film deposited in the deposition chamber 11. The mirror-polished surface 64 reduces the total surface area to which the wash radicals are exposed, thus causing a surface-controlled inactivation process (eg, maintaining a high and uniform F radical concentration) number of surface adsorption sites. To reduce.

0024When cleaning approximately 10,000 angstrom silicon nitride films, a 15.6% improvement in cleaning rate is achieved by first machining to 8 microinch and then mirror-polished to 2 microinch anodized diffuser and backing plate. Found in the used and washed AKT PECVD 3500 chamber. When cleaning approximately 10,000 angstrom silicon nitride films, AKT was cleaned using a Teflon® coated anodized diffuser first machined to 8 microinch and then mirror-polished to 2 microinch backing plate. A 6.8% improvement in cleaning rate was found in the PECVD 3500 chamber. Fluoropolymer coatings such as Teflon are disclosed in US Patent Application No. 09 / 322,893 (3622 / AKT), the disclosure of which is incorporated herein by reference. Therefore, the use of the present invention increases the process chamber throughput and reduces the amount of precursor gas required for cleaning.

0025NF₃Economical (eg, NF) due to the high cost associated with precursor gases such as₃Currently costs $ 100 / lb) and environmentally friendly (eg NF)₃Is a "greenhouse" gas), but the reduction in precursor gas consumption is also very beneficial. In addition, the mirror-polished surface is coated with many conventional surface coatings (eg, AlF) to prevent corrosion of the chamber surface or to prevent accumulated material from collapsing.₃), It is cheap and easy to manufacture. Furthermore, the present invention is believed to reduce variations in cleaning speed differences between processing chambers.

0026The above description discloses only preferred embodiments of the present invention, and changes in the above devices and methods included within the scope of the present invention will be readily apparent to those skilled in the art. For example, although the present invention has described PECVD chambers, it is understood that the present invention applies to a variety of process chambers, including thermal deposition chambers. In addition, cleaning processes using reactive species (eg, reactive species produced by RF plasma in a process chamber, or remote plasma source-generated reactive species, etc.) are mirror polished as described herein. It can be improved by using a surface. Further, it is believed that mirror polishing enhances cleaning when used on the downstream surface, but 2 microinch mirror polishing has been found to significantly enhance cleaning, which is preferred.

0027Therefore, although the present invention has been disclosed with preferred embodiments, it should be understood that other embodiments can also be included within the spirit and scope of the invention as defined by the claims.

Description of the sign

002810 ... processing device, 11 ... deposition chamber, 12 ... gas distribution plate, 12a-u ... aperture, 13 ... backing plate, 14 ... susceptor, 16 ... substrate, 18 ... heating element, 20 ... heater control unit, 22 ... lift mechanism , 28 ... Lift pin holder, 29 ... Chamber wall liner, 30 ... Lift pin aperture, 31 ... Shadow frame, 32 ... RF generator, 34 ... Matching network, 36 ... Vacuum pump, 38 ... First gas supply device, 40 ... Inlet , 42 ... valve controller system, 44a, 44b ... process gas source, 46 ... second gas supply device, 48 ... gas conduction line, 50 ... remote plasma chamber, 52 ... precursor gas source, 54 ... small amount carrier gas source, 56 ... Valve controller system, 60 ... high power generator, 62 ... flow restrictor, 64 ... mirror polished surface.