JP2007528938A - Cleaning tantalum-containing deposits from process chamber components - Google Patents

Abstract

A method for cleaning a tantalum-containing deposit from a surface of a process chamber component includes immersing the surface of the component in a cleaning solution having a weight ratio of HF to HNO ₃ of about 1: 8 to about 1:30. . In other variations, the cleaning solution has a molar ratio of KOH to H ₂ O ₂ of about 6: 1 to about 10: 1. In yet another variation suitable for cleaning copper surfaces, the cleaning solution includes HF and oxidizer in a HF to oxidizer molar ratio of at least about 6: 1. Tantalum-containing deposits can be removed from the surface with little erosion of the surface.
[Selection] Figure 1

Description

Cross reference

  This application is referred to as “Method for Cleaning Coated Process Chamber Components” and is assigned to Applied Materials and filed on Nov. 25, 2002, US Patent Application No. 10 / 304,535 to Wang et al. Brueckner et al., U.S. patent application, filed Dec. 19, 2003, entitled "Cleaning of chamber surfaces to recover metal-containing compounds", a continuation-in-part of the issue. This is a continuation-in-part of 10 / 742,604. Both disclosures are incorporated herein in their entirety.

background

  The present invention relates to cleaning and cleaning and recovering metal-containing residues from the surface of processing chamber components.

  In processing a substrate such as a semiconductor wafer or display, the substrate is placed in a process chamber and exposed to an activation gas to deposit or etch the material on the substrate. During such processing, processing residues are generated and deposited on the interior surface of the chamber. For example, in a sputter deposition process, the material sputtered from the deposition target on the substrate can cause the surface of other components in the chamber, such as deposition rings, coverings, shadow rings, inner shields, top shields, wall liners, It also deposits on the focus ring. In subsequent process cycles, the deposited process residues “peel” from the chamber component surfaces and fall onto the substrate and become contaminated. Therefore, the deposited process residue is periodically cleaned from the chamber surface.

  However, it is difficult to clean process deposits containing metals such as tantalum from chamber components, particularly when the components are made of metal-containing materials. When tantalum is sputter deposited on the substrate, a portion of the sputtered tantalum deposit is deposited on the adjacent chamber component surface. These tantalum process deposits are difficult to remove because cleaning solutions suitable for their removal are often reactive with other metals such as titanium used to form chamber components. Such cleaning of the tantalum-containing material from the surface can erode components and requires frequent replacement. When cleaning textured metal surfaces, such as those formed by the “Lavacoat®” process, erosion of the metal surface can be particularly problematic. These surfaces have gaps and narrow holes where tantalum-containing process residues remain, making it difficult to remove these residues with conventional cleaning processes.

  When conventional cleaning methods are used to clean tantalum, the amount of tantalum-containing material produced in these processes is not recovered. In many tantalum deposition processes, it is estimated that only about half of the sputtered tantalum material is deposited on the substrate and the rest is deposited on component surfaces inside the chamber. Conventional cleaning methods are often disposed of with the tantalum material in which the cleaning solution used is dissolved. Thus, after cleaning the chamber surface, a large amount of tantalum material is discarded, resulting in an estimated loss of about 30,000 pounds of tantalum per year. Disposal of tantalum is environmentally undesirable and costly because high purity tantalum is expensive and a new cleaning solution must be obtained.

  In one variation, it is desirable to be able to use process chamber components with copper surfaces during substrate processing. The copper surface has a small thermal gradient, so the stress between the copper surface and any residue deposited on the surface can be minimized. However, it can be very difficult to clean process residues from such surfaces, making it difficult to implement components with copper surfaces. This is in part because the copper surface is typically very easily etched and eroded by a similar cleaning solution that can etch and remove tantalum-containing deposits from the component surface. Also, it is undesirable that the copper surface can be eroded even by cleaning solutions that do not erode excessively other metal surfaces such as aluminum or stainless steel surfaces.

  Thus, it would be desirable to have a method for cleaning metal-containing residues and deposits, such as tantalum-containing deposits, from the surface of a component without excessive surface erosion. Furthermore, it would be desirable to have a method for cleaning tantalum-containing deposits from the surface of a component containing copper. It is also desirable to reduce the disposal of tantalum material that cleans the chamber surface. Furthermore, it would be desirable to have a method for recovering a cleaning solution used to clean tantalum-containing residues.

  These features, aspects, and advantages of the present invention will be better understood with regard to the following description, appended claims, and accompanying drawings that illustrate embodiments of the invention. However, it should be understood that each of the features can generally be used in the present invention and not only in conjunction with the specific drawings, and that the present invention includes any combination of these features. Should.

Explanation

  A process chamber component 22 having a surface 20 is cleaned to remove metal-containing process deposits 24, such as, for example, tantalum-containing deposits 24 that are generated during processing of the substrate 104, as shown in FIG. Is done. The tantalum-containing deposit can include, for example, at least one of tantalum metal, tantalum nitride, and tantalum oxide. Performing a cleaning process that removes the tantalum-containing deposit 24 can reduce the formation of contaminating particles in the chamber 106, improve substrate yield, and allow recovery of tantalum from the cleaning solution. Can do. The chamber component 22 to be cleaned is one that accumulates metal and tantalum containing process deposits 24, for example, a portion of a gas distribution system 112 that supplies process gas into the chamber 106, a substrate that supports the substrate 104 within the chamber 106. A support 114, a gas energizer 116 that activates process gas, a chamber enclosure wall 118, a shield 120, or a gas exhaust 122 that exhausts gas from the chamber, an exemplary embodiment of which is shown in FIG.

  Referring to FIG. 4 illustrating an embodiment of physical vapor deposition 106, components 22 that can be cleaned include chamber enclosure wall 118, chamber shield 120 including upper and lower shields 120a, b, target 124, and cover ring 126. A deposition ring 128, a support ring 130, an insulating ring 132, a coil 135, a coil support 137, a shutter disk 133, a clamp shield 141, and a surface 134 of the substrate support 114. The component 22 may have a surface 20 that includes at least one of metals, such as titanium, stainless steel, aluminum, copper, and tantalum. The surface 20 can also include at least one of ceramic materials, such as aluminum oxide, aluminum nitride, and silicon oxide.

  The cleaning step of removing process deposit 24 can include exposing the surface 20 of component 22 to an acidic cleaning solution that can at least partially remove process deposit 24 from surface 20 of component 22. . The acidic solution can react with and be removed from the process deposit 24 from the surface 20 of the component 22, for example, by reacting with the process deposit 24 to form a chemical species that readily dissolves in the acidic solution. Contains acidic species. However, after the process deposit 24 is removed from that portion of the component 22, the acidic solution does not corrode excessively and does not damage the exposed portion of the surface 20 of the component 22. The surface 20 can be exposed to the acidic solution by dipping, dipping or contacting portions of the surface 20 with the acidic solution. The surface 20 of the coating component 22 can be exposed to an acidic solution for about 3 minutes to 15 minutes for about 8 minutes, but may be immersed for other times depending on the composition and thickness of the process deposition material.

The composition of the acidic cleaning solution is selected by the composition of the surface 20 and the composition of the process deposit 24. In one variation, the acidic solution includes hydrofluoric acid (HF). Hydrofluoric acid can react and dissolve with impurities that are accumulated on the surface 20. The acidic solution can additionally or alternatively include a non-fluorinated acid, such as nitric acid (HNO ₃ ). Non-fluorinating agents can provide less aggressive chemical species and allow cleaning and preparation of the surface 20 with reduced formation of erosion cracks through the underlying component structure. Further, in one variation, the acidic solution provided to clean the surface 20 can include low concentrations of acidic species suitable to reduce corrosion of the component 22. A suitable concentration of acidic species may be, for example, less than about 15M acidic species, such as about 2 to about 15M acidic species. For component 22 with surface 20 comprising aluminum oxide or stainless steel, suitable acidic solutions are from about 2 M to about 8 MHF, such as about 5 M HF, about 2 M HNO ₃ to about 15 MHNO ₃ , such as about 12 M HNO. ₃ can be included. In the case of element 22 with a surface 20 comprising titanium, a suitable acidic solution can comprise from about 2M to about 10 MHNO ₃ . In one variation, a suitable acidic solution can include 5MHF and 12M HNO ₃ .

The cleaning method immerses the surface 20 in a solution having a ratio of HF to HNO ₃ chosen to remove the tantalum-containing deposits with little erosion of the surface 20 and in particular without eroding the metal surface 20. It has further been found that can be improved for cleaning tantalum-containing residues. In particular, it has been found that choosing a sufficiently low ratio of HF to HNO ₃ can reduce erosion of the surface 20, and in particular, erosion of the metal surface 20. A suitable ratio of HF to HNO ₃ may be a ratio that is less than about 1: 8 by mass. For example, the cleaning solution can comprise a weight ratio of HF to HNO _{3 of} about 1: 8 to about 1:30, about 1:12 to about 1:20, such as about 1:15. Desirably, the concentration of HF in the solution is maintained at less than about 10% mass, such as from about 2% to about 10%, even 5% by weight. The concentration of HNO _{3 in} the solution is desirably at least about 60% by weight, such as about 60% to 67% by weight, 65% by weight.

The result of the improved cleaning is believed to at least partially form an etch resistant protective layer on the surface where HNO ₃ reacts with the surface 20, eg, a metal surface, to prevent etching of the surface 20. . At a sufficiently low ratio, HNO ₃ and HF work together to remove tantalum-containing deposits with little erosion of surface 20. As the HF etches and dissolves the tantalum-containing deposit, a portion of the surface 20 is exposed. HNO ₃ also has a low etch rate, but etches tantalum-containing deposits because strong oxidants react and oxidize with exposed portions of surface 20 to form a protective etch resistant layer. Thus, by maintaining a sufficiently high HNO ₃ concentration for the concentration of HF in the solution, an excess amount of HNO ₃ can be used to protect the surface 20 from erosion. A cleaning solution having an improved ratio of HF to HNO ₃ with a sufficiently high HNO ₃ concentration for HF is particularly suitable for cleaning metal surfaces 20 comprising, for example, at least one of titanium, stainless steel, aluminum, and tantalum. It is a thing.

  In the cleaning process, fresh HF can be added to the cleaning solution to replenish depleted HF. For example, HF in solution is consumed by reacting with the tantalum-containing deposit 24 to form a tantalum fluoride compound. The consumption of HF gradually delays the removal of tantalum-containing deposits from the surface 20. The addition of fresh HF can cause the tantalum-containing deposit 24 to be removed from the surface 20 at the desired rate.

  In one variation, the composition of the cleaning solution can be optimized for cleaning tantalum-containing deposits from a metal surface 20 comprising copper. In particular, a cleaning solution containing hydrofluoric acid (HF) and an oxidizer in a preselected molar ratio does not etch the copper surface 20 excessively and erodes the copper surface 20 almost without tantalum-containing deposits. It has been found to provide 24 improved cleanings. In one variation, the cleaning solution comprises a molar ratio of HF to oxidizing agent of at least about 6: 1, such as about 9: 1, at least about 20: 1. For example, the cleaning solution may comprise a molar ratio of HF to oxidizing agent of about 6: 1 to 40: 1, such as about 9: 1 to 20: 1. A suitable concentration of HF in the cleaning solution may be at least about 3M, such as 3M-20M. Suitable concentrations of oxidizing agent in the cleaning solution may be less than about 3M, such as about 0.1M to 3M, even less than about 1M, such as about 0.1M to about 1M. An improved cleaning solution containing HF and oxidizer in a preselected ratio results in good etch selectivity of the tantalum-containing deposit 24 on the copper surface 20, for example at least about 40: 1, even at least about 50: 1. Can also give selectivity.

The oxidizer can oxidize other compounds and materials, such as tantalum-containing deposits, and typically includes oxygen-containing compounds. In one variation, a suitable oxidant includes nitric acid (HNO ₃ ). Result of good cleaning, any one or a combination can be given as in addition to HNO ₃ or substitutes, hydrogen peroxide _{(H 2 O} 2), sulfurous acid _(H 2 _SO 3), and ozone ( It has further been found that it can be obtained with oxidizing agents comprising at least one of O ₃ ). For example, ozone can be supplied in a desired ratio of cleaning solution by bubbling ozone gas through the cleaning solution.

In one exemplary variation of a cleaning solution suitable for cleaning tantalum-containing deposits from the surface 20 of a component comprising copper, the oxidant includes HNO ₃ . For example, the cleaning solution may comprise (i) about 45% by volume of a HF stock solution having a concentration of about 49% by weight HF and (ii) about 5% by volume of a stock solution of HNO ₃ having a concentration of about 70% by weight HNO _3. ˜about 10% by volume can be formed. The remainder of the solution contains water and is preferably deionized. Such solutions, 10 volume% HNO ₃ in the case of the solution to about 9: For 1, 5 volume% HNO ₃ solution to about 19: contains a molar ratio of 1 of HF and HNO _3.

The discovery that a solution containing a preselected ratio of HF and oxidizer was able to clean the tantalum-containing deposit 24 without excessively etching the copper surface 20 is that copper is typically oxidized like HNO _3. It was not anticipated because it could be easily eroded by such agents because it is very susceptible to chemical attack by agents. Also, the tantalum-containing deposit 24 is typically not etched at a desired high rate by a solution containing only HF. However, it has been found that combining HF and oxidant in a preselected molar ratio can provide a synergistic effect, thereby resulting in improved cleaning of the tantalum-containing deposit 24. Without limiting the discovery to any particular chemical mechanism, the oxidant may act to increase the cleaning rate achieved by HF in solution to etch tantalum-containing deposits from the surface 20 at a high etch rate. It is supposed to be possible. However, it is desirable that the concentration of oxidant be kept low with respect to the concentration of HF, since an excess of oxidant results in rapid etching and erosion of the copper surface 20. Improved HF and oxidant cleaning solutions because component surfaces 20 containing metals other than copper, such as aluminum or stainless steel surfaces, may often require a cleaning solution with a much lower molar ratio of HF to HNO _3. The copper cleaning ability is even more surprising. Accordingly, cleaning of the copper surface 20 with an improved cleaning solution having a preselected ratio of HF and oxidant provides unexpectedly good cleaning results and is configured with the copper surface 20 in the substrate processing chamber 106. Provides efficient use of element 22.

5-6B are graphs showing comparative data for surface cleaning with various cleaning solutions. FIG. 5 is a graph showing comparative data for cleaning solutions containing HF and HNO ₃ at a ratio that is relatively less than the desired molar ratio of at least about 6: 1. In order to obtain comparative data, the copper surface 20 was prepared by adding HF and HNO ₃ to (i) 2: 1 of the solution shown by line 200 in FIG. 5 and (ii) 1: 2 moles of the solution shown by line 202. Soaked in a cleaning solution containing the ratio. The solution represented by line 200, was formed by combining 49 wt.% HF stock solution 1 volume, 70 wt% HNO ₃ stock solution 1 volume of deionized water 1 volume. The solution represented by line 202 was formed by combining 1 part by volume of 49 wt% HF stock solution and 4 parts by volume of deionized water. The mass percent of the copper erosion method from each surface was measured at various intervals in the cleaning process and this weight percent was graphed against the increased cleaning time. FIG. 5 shows that both cleaning solutions produced an undesirably high level of erosion of the copper surface, with the cleaning solution shown by line 200 eroding about 20% by weight of the copper surface after only about 5 minutes. The cleaning solution represented by line 202 erodes slightly above about 25% by weight after about 5 minutes and above 30% after about 10 minutes. Therefore, the cleaning solution showed undesirable results in cleaning the copper surface 20.

6A and 6B are graphs showing unexpectedly good cleaning results obtained with a solution containing HF and HNO ₃ having a preselected ratio. In FIG. 6A, the copper surface is (i) a comparative solution containing only HF as indicated by line 204 at a concentration of about 15M, and (ii) HF and HNO ₃ as indicated by line 206 in a molar ratio of about 20: 1. Soaked in a solution containing the improved solution containing. A comparative solution was formed by combining 1 volume part of 49 wt% HF stock solution and 1 volume part of deionized water. Improved cleaning solution was formed by combining the 49 wt% HF stock solution 10 volume portion, and a 70 wt% HNO ₃ stock solution 1 volume part of deionized water 10 volume portion. The weight percent of the copper eroded method consisting of each surface was measured at various intervals in the cleaning process and graphed against the cleaning time increasing the eroded weight percent.

FIG. 6A is a diagram showing the percent weight loss of copper obtained from cleaning copper surface 20 with a comparative cleaning solution containing HF and an improved cleaning solution containing both HF and HNO _{3 in} a molar ratio of about 20: 1. is there. The comparative solution produced little or no erosion of the copper surface. The improved solution containing both HF and HNO ₃ has less copper surface erosion, but erosion occurs at a very low rate, and is a much lower copper weight loss percentage than the comparative cleaning solution shown by lines 200 and 202 in FIG. There were very few. For example, with the improved cleaning solution shown by line 206, the percent weight loss of copper after cleaning slightly over 100 minutes was only slightly less than 0.15%. By comparison, after only 5 minutes of cleaning, the comparative solution shown by lines 200 and 202 in FIG. 5 yields a weight loss percentage of copper slightly above 20% and 25%, which is preselected for HF and HNO _3. The weight loss percentage is more than 100 times that of an improved cleaning solution having a high ratio. Even after about 350 minutes of cleaning, an improved cleaning solution having a preselected ratio of HF and HNO ₃ resulted in a slight loss of copper from the surface 20 slightly more than about 0.20 weight percent. . Thus, an improved cleaning solution having a preselected ratio of HF and HNO ₃ provides improved cleaning of the copper surface 20 with little erosion of the copper surface 20.

FIG. 6B shows the result of exposing the tantalum surface to a cleaning solution having the same composition as FIG. 6A. The wash results obtained with the comparative solution containing about 15 MHF are shown in line 208 and the wash results obtained with the improved solution containing HF and HNO ₃ in a preselected ratio of about 20: 1 are shown in line 210. It is shown in To obtain the data in this figure, tantalum-containing surfaces are immersed in each of the cleaning solutions, and the mass percent of tantalum erosion methods from each surface is measured at various intervals in the cleaning process to determine the cleaning ability of each solution. did. A graph of each solution was shown against the increased cleaning time as the weight percent eroded.

The results shown in FIG. 6B show that an improved cleaning solution having a preselected ratio of HF and HNO ₃ provides better cleaning of tantalum containing materials than a solution having only HF. For example, after about 150 minutes of cleaning, the improved solution of HF and HNO ₃ shown in line 210 removed more than 5 weight percent tantalum from the surface. By comparison, a solution containing only HF, indicated by line 208, removed only about 1 weight percent tantalum at the same time. Furthermore, a comparison of FIGS. 6A and 6B shows the high selectivity between tantalum and copper exhibited by an improved cleaning solution that includes a preselected ratio of HF and HNO ₃ . As shown in line 206 of FIG. 6A, the improved cleaning solution results in a loss of about 0.22 weight percent of copper after a cleaning time of about 350 minutes, as shown in line 210 of FIG. Tantalum slightly above the weight percent was removed from the surface at the same time. Thus, the improved cleaning solution can exhibit a selectivity of about 50: 1 tantalum and copper. Thus, a solution having a preselected ratio of HF and an oxidizing agent such as HNO ₃ effectively cleans tantalum-containing deposits from the surface of the component containing copper with little erosion of the component surface. Give improved results.

In yet another variation, the tantalum-containing deposit 24 can be cleaned from the surface 20 by immersing the surface 20 in a cleaning solution comprising KOH and H ₂ O ₂ . The cleaning solution has a ratio of KOH to H ₂ O ₂ that is chosen to remove the tantalum-containing deposits with little erosion of the surface 20 and in particular little erosion of the metal surface. A suitable ratio of KOH to H ₂ O ₂ is about 6: 1 to 10: 1, for example about 7.5: 1 by mole. Ratios less than or greater than the desired ratio range can reduce selectivity to tantalum-containing deposits and can result in etching and erosion of the surface 20, respectively. Suitable concentrations of KOH in the solution are, for example, from about 5M to about 12M, from about 5M to about 10M, such as 7M. A suitable concentration of H ₂ O ₂ in the solution is, for example, from about 0.5M to about 2.5M, from about 0.5M to about 2M, such as 1M. It has also been found that maintaining the proper temperature of the cleaning solution comprising KOH and H ₂ O ₂ can improve the removal of the tantalum-containing deposit 24 by increasing the deposit removal rate. Suitable temperatures for the cleaning solution need only be at least about 70 ° C, such as about 80-95 ° C, at least 90 ° C.

In yet another variation of the cleaning method, the metal surface 20 is cleaned with an electrochemical etching process. In this process, for example, as shown in FIG. 2, the surface 20 of the component 22 acts as an anode and is connected to the positive terminal 31 of the voltage source 30. The metal surface 20 is immersed in an electrochemical bath 33 having a bath solution containing an electrolyte. The electrochemical bath solution can also or alternatively include at least one of an oxidant, such as HF, HNO ₃ , KOH, H ₂ O ₂ , that selectively etches tantalum-containing deposits. For example, an electrochemical cell can include one of the HF / HNO ₃ or KOH / H ₂ O ₂ cleaning solutions. The bath solution may also contain other cleaning agents such as HCl, H ₂ SO ₄ , methanol. In one variation, the bath selectively electrochemically etches tantalum-containing deposits with a solution containing HF, H ₂ SO ₄ , and methanol. The cathode 34 connected to the negative terminal 32 of the voltage source 30 is also immersed in the tank 33. Application of a bias voltage from the voltage source 30 to the metal surface 20 and the cathode 34 may result in a tantalum-containing residue at the surface 20 that can transform the tantalum-containing deposit 24, eg, tantalum metal, into an ionic form that is soluble in the electrochemical etch bath solution. It induces a change in the oxidation state of 24, thereby “etching” the tantalum-containing deposit 24 from the surface 20. Electrochemical etching process conditions, such as the voltage applied to the metal surface 20, the pH of the electrochemical solution, and the temperature of the solution, selectively tantalum-containing deposits from the metal surface 20 with little erosion. It is desirable to maintain for removal.

  These cleaning methods are particularly suitable for the textured surface 20, for example as shown in FIG. A component 22 having a textured surface reduces particle generation in the process chamber by providing a “sticky” surface to which process residues adhere. In one variation, the component 22 for cleaning tantalum-containing deposits is manufactured with a component whose surface has been textured with a “Lavacoat®” process, eg, a “surface-textured chamber component” West et al., US patent application Ser. No. 10 / 653,713, filed Sep. 2, 2002, Popiolkowski et al., US patent application Ser. No. 10 / 099,307, filed Mar. 13, 2002, referred to as “cleaning”. Including the components described in US patent application Ser. No. 10 / 622,178 to Popiolkowski et al., Filed Jul. 17, all of which are co-assigned to Applied Materials, the entire disclosure of which is incorporated herein by reference. Is incorporated throughout the book. Component 22 can include a coating component having a textured surface, such as a plasma spray coating or a twin wire arc spray coating, eg, filed November 25, 2002, co-assigned to Applied Materials. Of Wang et al., US patent application Ser. No. 10 / 304,535, the disclosure of which is incorporated herein in its entirety.

  The “Lavacoat®” textured metal surface 20 is formed by generating an electromagnetic energy beam and sending the beam to the surface 20 of the component 22. The electromagnetic energy beam is preferably an electron beam, but can also include protons, neutrons, X-rays, and the like. The electron beam is typically focused on a region of the surface 20 for some time during which the beam interacts with the surface 20 to form features on the surface. It is believed that the beam forms a feature by heating a region of the surface 20, in some cases to the melting temperature of the surface material. Rapid heating causes some of the surface material to be released outwards, resulting in indentations 23 in areas where the material has been released and bumps 25 in areas where the released material will redeposit. After the desired features are formed in the region, the beam is scanned to different parts of the component surface 20 to form the features in the new region. The final surface 20 can comprise a honeycomb-like structure of indentations 23 and ridges 25 formed in the surface 20. The features formed by this method are typically macroscopic in size, and the indentations have a diameter of about 0.1 mm to about 3.5 mm, for example, a diameter of about 0.8 mm to about 1.0 mm. It may be a range. The “Lavarcoat®” textured surface 20 has a total surface roughness average of about 2500 microinches (63.5 microns) to about 4000 microinches (101.6 microns). Average is defined as the average of the absolute value of the displacement from the average line of the feature along the surface 20.

This cleaning method shows surprisingly good results for cleaning such textured surfaces with little erosion of the surface 20. For example, in the case of a textured metal surface 20 formed from titanium, the above cleaning method may clean tantalum-containing residues from the surface 20 while eroding less than about 1 mg / cm ² of titanium from the metal surface 20 per hour. it can. In contrast, conventional tantalum cleaning processes can erode more than about 5 mg / cm ² of titanium from the titanium surface of component 22. As another example, a solution of KOH and H ₂ O ₂ having a selected molar ratio of about 6: 1 to 10: 1 and a temperature of about 80-95 ° C. is the rate at which the titanium component surface 20 is eroded. Tantalum-containing deposits can be cleaned at a rate approximately 20 times faster and the surface 20 can be cleaned with little excessive erosion.

When the cleaning of the component surface 20 is complete, the cleaning solution may be a metal-containing material, such as at least one of tantalum metal and tantalum oxide, and can be treated to recover the tantalum-containing material. Recovering the tantalum-containing material from the cleaning solution can reduce environmental pollution through disposal of tantalum and can also reduce costs associated with proper disposal of waste tantalum. The recovered tantalum-containing material can be reused for substrate processing, for example, the recovered tantalum material can be used to form a tantalum-containing target for a physical vapor deposition process. In addition to tantalum recovery, the cleaning solution used can be processed to allow reuse of the cleaning solution. For example, the cleaning solution can be processed to recover a reusable solution of HF and HNO ₃ .

A flow chart illustrating an example of a method for cleaning the components and recovering the tantalum-containing material is shown in FIG. 3A. The first step of the method is cleaning by immersing the component surface 20 in a cleaning solution that dissolves tantalum and other metal-containing residues in the solution to form tantalum and metal-containing compounds, respectively. After the components are washed, a precipitating agent is added to the washing solution to precipitate the metal-containing compound from the solution and form a mixed solid. The mixed solids include a tantalum-containing compound, such as tantalum oxide, and can also include other metal-containing compounds, such as a compound including aluminum, titanium, and iron. In one variation, as shown by the arrows in FIG. 3A, the washed solution can be recovered and reused in the next component 22 once the mixed solids have precipitated and removed from the solution. it can. In one method of precipitating mixed solids, the wash solution is neutralized by adding a precipitating agent comprising an acid or base to bring the pH of the solution to a pH of less than about 1 to about 7. For example, in the case of a cleaning solution containing HF and HNO ₃ , a base can be added to neutralize the solution. In the case of a cleaning solution containing KOH and H ₂ O ₂ , an acid can be added to neutralize the solution. Suitable acids to neutralize can include at least one of HNO ₃ , H ₂ SO ₄ and H ₃ PO ₄ . Suitable bases to neutralize can include at least one of NaOH, KOH and CaCO ₃ . For example, the mixed solid is separated from the cleaning solution by filtering the mixed solid from the cleaning solution.

  In order to separate the tantalum-containing compound from other metal-containing compounds, a metal selective acid solution is added to the mixed solids. The metal selective acid solution includes a metal selective acid that dissolves the metal containing compound in the acid solution with little dissolution of the tantalum containing compound. Suitable metal selective acids can include, for example, HCl. The solid tantalum-containing compound is separated from the acid solution having the dissolved metal-containing compound, for example, by filtering the tantalum-containing solid or by decanting the acidic solution from the tantalum-containing solid. The tantalum-containing compound can then be converted to tantalum oxide, for example by heating.

Yet another method of cleaning the components and recovering the tantalum-containing material is illustrated in the flowchart of FIG. 3B. Component surface 20 is cleaned by immersing surface 20 in an aqueous cleaning solution to dissolve tantalum-containing compounds from surface 20. After cleaning the surface, the tantalum-containing compound is removed from the cleaning solution in a liquid extraction process. The extraction process involves combining an aqueous wash solution with an organic solution that is hardly miscible with the aqueous solution. The organic solution is a solution in which the tantalum-containing compound is very soluble, and the tantalum-containing compound can be extracted from the aqueous solution. Suitable organic solutions for extracting the tantalum-containing compound can include, for example, at least one of methyl isobutyl ketone, diethyl ketone, cyclohexane, diisobutyl ketone, and tributyl phosphate. When a tantalum-containing compound is extracted into an organic solution, for example, it is possible to separate the solution into separate organic and aqueous phases and separate one solution from the other, thereby separating the organic and aqueous solutions Is done. The separated aqueous solution can be retained and reused as a cleaning solution, as shown by the arrows in FIG. 3B. For example, the aqueous solution can include HF and HNO ₃ remaining in the aqueous solution during extraction and can be reused in a subsequent cleaning process that removes tantalum-containing residues from the metal surface 20.

  After the extraction process, the tantalum-containing compound in the organic solution can be decomposed thermally. In thermohydrolytic decomposition, the tantalum-containing compound is heated to a temperature at which the compound reacts with oxygen to form a tantalum oxide compound, for example, at least 120 ° C., eg, about 120 ° C. to about 180 ° C. . Organic solutions and any decomposition reaction products can also be evaporated from the tantalum oxide compound during the thermal hydrolytic decomposition process. Alternatively, the organic solution can be removed from the tantalum-containing compound in a separate step. The tantalum oxide compound can also be processed to form tantalum metal, for example, by heating the tantalum oxide compound in a furnace.

  An example of a suitable process chamber 106 having components that are cleaned to remove metal-containing deposits 24, such as tantalum-containing deposits 24, is shown in FIG. Chamber 106 may be part of a multi-chamber platform (not shown) having a cluster of interconnected chambers connected by a robotic arm mechanism that transfers substrate 104 between chambers 106. In the illustrated variation, the process chamber 106 can sputter deposit a material, eg, one or more of tantalum, tantalum nitride, titanium, titanium nitride, copper, tungsten, tungsten nitride, and aluminum, on the substrate 104. A sputter deposition chamber, also called a physical vapor deposition chamber or PVD chamber. The chamber 106 surrounds the process zone 109 and includes an enclosure wall 118 that includes a side wall 164, a bottom wall 166, and a ceiling 168. A support ring 130 can be disposed between the sidewall 164 and the sealing 168 to support the sealing 168. Other chamber walls may include one or more shields 120 that shield the enclosure wall 118 from the sputter environment.

  The chamber 106 includes a substrate support 114 that supports the substrate in the sputter deposition chamber 106. The substrate support 114 may be electrically floating and may include an electrode 170 that is biased with a power source 172, eg, an RF power source. The substrate support 114 can also include a movable shutter disk 133 that can protect the upper surface 134 of the support 114 when the substrate 104 is not present. In operation, the substrate 104 is introduced into the chamber 106 through a substrate loading port (not shown) on the sidewall 164 of the chamber 106 and mounted on the support 114. The support 114 can be lifted and lowered with a support lift bellows, and a lift finger assembly (not shown) moves the substrate to the support 114 while transporting the substrate 104 to and from the chamber 106. Can be used for lifting and lowering.

  The support 114 may also include one or more rings that cover at least a portion of the upper surface 134 of the support 114 to prevent erosion of the support 114, such as a cover ring 126 and a deposition ring 128. In one variation, the deposition ring 128 at least partially surrounds the substrate 104 to protect the portion of the support 114 that is not covered by the substrate 104. The cover ring 126 surrounds and covers at least a portion of the deposition ring 128 to reduce particle deposition on both the deposition ring 128 and the underlying support 114.

  A process gas, such as sputtering gas, is provided with one or more gas sources 174 that pass to a conduit 176, each having a gas flow control valve 178, such as a mass flow controller, through which a set flow rate of gas is passed. Is introduced into the chamber 106 through a gas distribution system 112 containing a process gas source. Conduit 176 can route gas to a mixing manifold (not shown) that mixes the gases to form the desired process gas composition. The mixing manifold is routed to a gas distributor 180 having one or more gas outlets 182 in the chamber 106. The process gas can include a non-reactive gas, such as argon or xenon, that can energetically impact and sputter on the material from the target. The process gas can include a reactive gas, such as one or more of an oxygen-containing gas and a nitrogen-containing gas, that can react with the sputtered material to form a layer on the substrate 104. Spent process gas and by-products receive spent process gas from the chamber 106 and one or more exhausts that pass the spent gas through an exhaust conduit 186 with a throttle valve 188 that controls the pressure of the gas in the chamber. It is discharged through a discharge port 122 that includes a port 184. The exhaust conduit 186 is routed to one or more exhaust pumps 190. Typically, the sputtering gas pressure in the chamber 106 is set to a level below atmospheric pressure.

  The sputtering chamber 106 further includes a sputtering target 124 that faces the surface 105 of the substrate 104 and includes at least one of materials sputtered onto the substrate 104, such as tantalum and tantalum nitride. The target 124 is electrically isolated from the chamber 106 by an annular insulating ring 132 and connected to a power source 192. The sputtering chamber 106 also has a shield 120 to protect the wall 118 of the chamber 106 from sputtered material. The shield 120 may have a wall-like cylindrical shape having upper and lower shield portions 120 a and 120 b that block the upper and lower regions of the chamber 106. In the variation shown in FIG. 4, the shield 120 has an upper portion 120 a attached to the support ring 130 and a lower portion 120 b attached to the cover ring 126. A clamp shield 141 with a clamp ring can be provided to clamp the upper and lower shield portions 120a, b together. Alternative shield structures can be provided, for example, inner and outer shields. In one variation, one or more of the power source 192, the target 124, and the shield 120 operate as a gas energizer 116 that can activate a sputtering gas to sputter material from the target 124. Power supply 192 applies a bias voltage to target 124 for shield 120. The electric field generated in the chamber 106 from the applied voltage activates the sputtering gas to form a plasma that bombards and impacts the target 124 and the target 124 in order to sputter material onto the substrate 104. Support 114 with electrode 170 and support electrode power source 172 can also operate as part of gas energizer 116 by activating and promoting ionized material sputtered from target 124 toward substrate 104. Furthermore, a gas activation coil 135 may be provided that is output by the power source 192 and located within the chamber 106 to provide enhanced activation gas characteristics, such as improved activation gas density. The gas activation coil 135 may be supported within the chamber 106 by a coil support 137 that is attached to a shield 120 or other wall.

  The chamber 106 is controlled by a controller 194 that has program code with an instruction set that activates the components of the chamber 106 to process the substrate 104 within the chamber 106. For example, the controller 194 includes a substrate support 114 and a substrate positioning instruction set that activates one or more of the substrate transports to place the substrate 104 in the chamber 106; flow control to set the sputtering gas flow in the chamber 106; A gas flow control command set to operate valve 178; a gas pressure control command set to operate exhaust throttle valve 188 to maintain pressure in chamber 106; and a gas energizer 116 to set gas activation power level A gas energizer control instruction set for controlling; a temperature control instruction set for controlling the temperature in the chamber 106; and a process monitor instruction set for monitoring a process in the chamber 106.

  While exemplary embodiments of the present invention have been shown and described, those skilled in the art can construct other embodiments that incorporate the present invention and are also within the scope of the present invention. For example, chamber components other than the exemplary components described herein may be cleaned. Additional washing and recovery steps other than those described can also be performed. Furthermore, opposite or position terms illustrated for the exemplary embodiments have the same meaning. Accordingly, the appended claims should not be limited to the description of the preferred variations, materials, or spatial arrangements described herein to illustrate the invention.

FIG. 1 is a schematic side view of an embodiment of a component having a surface having a metal-containing deposit thereon. FIG. 2 is a schematic side view of an embodiment of an electrochemical etching apparatus. FIG. 3A is a flowchart illustrating an embodiment of a method for recovering a tantalum-containing compound. FIG. 3B is a flowchart illustrating another embodiment of a method for recovering a tantalum-containing compound. FIG. 4 is a side cross-sectional view of an embodiment of a process chamber having one or more components that can clean metal-containing deposits in a cleaning process. FIG. 5 is a comparative graph of percent copper loss versus increase in cleaning time resulting from cleaning copper surfaces with different cleaning solutions containing HF and HNO ₃ . FIG. 6A shows the percentage of weight loss of copper relative to the increase in cleaning time obtained from cleaning the copper surface with a cleaning solution containing only HF and an improved cleaning solution having a preselected ratio of HF and HNO ₃ . It is a graph. FIG. 6B is a graph of percent loss of tantalum versus increase in cleaning time resulting from cleaning the tantalum surface with the cleaning solution of FIG. 6A.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Surface, 22 ... Process chamber component, 24 ... Metal-containing process deposit, 104 ... Substrate, 106 ... Chamber, 109 ... Process zone, 112 ... Gas distribution system, 114 ... Substrate support, 116 ... Energizer, 118 ... Enclosure wall, 120 ... shield, 122 ... gas outlet, 124 ... target, 126 ... cover ring, 128 ... deposition ring, 130 ... support ring, 132 ... insulation ring, 133 ... shutter disk, 134 ... surface, 135 ... coil, DESCRIPTION OF SYMBOLS 137 ... Coil support, 141 ... Clamp shield, 164 ... Side wall, 168 ... Sealing, 170 ... Electrode, 172 ... Power source, 174 ... Gas supply source, 176 ... Conduit, 178 ... Gas flow control valve, 180 ... Gas distributor, 182 ... Gas outlet, 186 ... Conduit, 88 ... throttle valve, 190 ... pump, 192 ... power supply, 194 ... controller.

Claims (15)

A method for cleaning tantalum-containing deposits from the surface of a process chamber component comprising:
Immersing the surface of the component in a cleaning solution comprising a weight ratio of HF to HNO ₃ of about 1: 8 to about 1:30;
Thereby, the tantalum-containing deposit can be removed from the surface with little erosion of the surface. Said method.   The method of claim 1, wherein the surface of the process chamber component comprises at least one of titanium, stainless steel, aluminum, and tantalum.   The method of claim 1, wherein the solution comprises less than about 10% by weight HF.   The method of claim 1, comprising immersing a surface of the process chamber component that is a textured surface having an average surface roughness of about 63.5 micrometers to about 101.6 micrometers.   The method of claim 1, comprising immersing a surface of the process chamber component that is a textured surface having an indentation having a diameter of about 0.1 mm to about 3.5 mm. A method for cleaning tantalum-containing deposits from the surface of a process chamber component comprising:
Immersing the surface of the component in a solution comprising a molar ratio of KOH: H ₂ O ₂ of about 6: 1 to about 10: 1;
The method, wherein the tantalum-containing deposit can thereby be removed from the surface with little erosion of the surface.   The method of claim 6, wherein the surface of the process chamber component comprises at least one of titanium, stainless steel, aluminum, and tantalum. The method of claim 6, wherein the solution comprises about 5 M to about 12 M KOH and about 0.5 M to about 2.5 M H ₂ O ₂ .   The method of claim 6, wherein the solution is maintained at a temperature of at least about 70 ° C. A method of cleaning a tantalum-containing deposit from a surface of a process chamber component, the surface comprising copper, the method comprising:
Immersing the surface of the component in a cleaning solution comprising HF and an oxidizing agent, wherein the molar ratio of HF to the oxidizing agent is at least about 6: 1;
The method, wherein the tantalum-containing deposit can thereby be removed from the surface with little erosion of the surface.   The method of claim 10, wherein the molar ratio of HF to oxidizing agent is from about 9: 1 to about 20: 1. The method of claim 10, wherein the oxidant comprises at least one of HNO ₃ , H ₂ O ₂ , H ₂ SO ₃ and O ₃ .   The method of claim 10, wherein the wash solution comprises about 3 M to about 20 M HF and about 0.1 M to about 3 M of the oxidizing agent. A method of cleaning tantalum-containing deposits and other metal-containing deposits from the surface of a process chamber component to recover tantalum-containing materials,
(A) immersing the surface of the component in an acidic cleaning solution or a basic cleaning solution, thereby dissolving the tantalum-containing deposit and other metal-containing deposits on the surface; Forming a metal-containing compound;
(B) treating the solution;
(I) adding a precipitant to the solution, thereby forming a mixed solid comprising the tantalum-containing compound and the metal-containing compound;
(Ii) filtering the mixed solids from the solution;
(Iii) a step of adding a metal-selective acid solution to the mixed solid content, wherein the metal-selective acid solution dissolves the metal-containing compound without substantially dissolving the tantalum-containing compound. Said process comprising:
(Iv) separating the tantalum-containing compound from the dissolved metal-containing compound;
Recovering the tantalum-containing compound by:
Said method. A method of cleaning a tantalum-containing deposit from a surface of a process chamber component to recover a tantalum-containing material,
(A) immersing the surface of the component in an aqueous cleaning solution comprising an acid or base, thereby dissolving the tantalum-containing deposit on the surface to form a tantalum-containing material in the solution When,
(B) treating the aqueous cleaning solution;
(I) mixing the aqueous solution with an organic solution capable of extracting the tantalum-containing material from the aqueous cleaning solution;
(Ii) separating the organic solution from the aqueous cleaning solution;
(Iii) decomposing the tantalum-containing material by thermal hydrolysis;
Recovering the tantalum-containing material by:
Said method.

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