JP2005270830A - Apparatus and method for cleaning tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning apparatus for effectively cleaning a metal stuck to a tool in the tool used in a dry etching apparatus, a CVD (chemical vapor deposition) apparatus, or the like, used in a process for manufacturing a semiconductor, a liquid crystal substrate or a solar battery. <P>SOLUTION: Cleaning by nitric acid and a hydrogen peroxide aqueous solution is carried out using a first cleaning unit (steps S1 to S3). Next, heat treatment loaded with oxygen is carried out to the cleaned tool obtained in the first cleaning unit 1 using a heating unit (step S4). Further, cleaning with an ozone aqueous solution loaded with hydrochloric acid is carried out to the cleaned tool obtained in the heating unit 2 using a second cleaning unit (steps S5 and S6). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cleaning apparatus and a cleaning apparatus for cleaning a jig composed of a ceramic member used in a semiconductor or liquid crystal substrate, a dry etching apparatus used in the manufacturing process of a solar cell, a CVD (chemical vapor deposition) apparatus, and the like. It is about the method.

  Various jigs made of ceramic members or quartz members are used in semiconductor or liquid crystal substrate manufacturing apparatuses (hereinafter referred to as semiconductor manufacturing apparatuses) including dry etching apparatuses and CVD apparatuses. As an example of the apparatus, these jigs include a ceramic dome, a focus ring, a step window, a filler ring, a cover clamp, an edge ring, and a susceptor. Among these jigs, the ceramic dome, focus ring, step window, filler ring, cover clamp, and edge ring are made of a ceramic member, and the susceptor is made of a quartz member. The ceramic member and the quartz member are largely based on the know-how of the semiconductor device manufacturer and the device manufacturer in response to the problem of the member processing accuracy and the problem of the generation of contaminants from the member. Among these jigs, the shape of the ceramic dome is shown in FIG. 9A, and the shape of the focus ring is shown in FIG. 9B. In particular, ceramic domes and focus rings are used in metal dry etching equipment. In the ceramic dome shown in FIG. 9A, for example, the outer diameter is 380 mm, the inner diameter is 360 mm, and the height is 90 mm. In the focus ring shown in FIG. 9B, the outer diameter is 280 mm, the inner diameter is 205 mm, and the height is 60 mm. It is.

  In the past, jigs that were contaminated in the original semiconductor manufacturing process were often outsourced to external specialists for cleaning mainly with high-concentration chemicals. In this case, the jig was removed from the apparatus, and a professional contractor took it home and cleaned it with his own cleaning apparatus. Then, the cleaned jig is sealed in a resinous bag and transported to a semiconductor manufacturing factory again. Such a method also takes time for setup and requires inventory of spare parts. Such outsourcing costs cannot be ignored.

In order to repeatedly use a jig composed of a ceramic member or a quartz member, there is a demand for a cleaning apparatus that can clean each member without etching at low cost. As a conventional technique related to these jig cleaning apparatuses, there is a cleaning method as disclosed in Patent Document 1. Here, for cleaning the ceramic member, a treatment mainly composed of an alkaline chemical solution is performed, and then a high temperature treatment is performed to remove deposits such as reactive products on the surface. In particular, hydrofluoric acid and sulfuric acid have been used for removing metals.
JP 2003-55070 A

In the cleaning method disclosed in Patent Document 1, it is described that a chemical for removing adhered foreign matter on the surface of a member is an alkaline chemical, and an acidic chemical is also used for a foreign substance containing metal. However, the use of an alkaline chemical may cause a great problem particularly in a process for a Si wafer. This is because if the metal ion M ⁺ with respect to the alkali hydroxyl group OH ⁻ remains in the semiconductor manufacturing apparatus as the metal atom M, the diffusion coefficient with respect to Si is high, so that the metal M such as Na forms an unintentional impurity layer. Because. In addition, when an alkaline chemical solution and an acidic chemical solution are used in combination, the generation of salt is a concern. A plurality of treatment tanks and exhaust are required, and the apparatus becomes large, the waste liquid equipment becomes complicated, and the cost increases.

  A jig composed of a ceramic member and a quartz member is not manufactured on the premise of being disposable. Therefore, by cleaning and regenerating these jigs, it is possible to reduce the manufacturing cost of a substrate such as a semiconductor or a liquid crystal substrate. In recent years, semiconductors and liquid crystal substrates have been miniaturized, and in semiconductor manufacturing apparatuses and liquid crystal panel manufacturing apparatuses, concerns about metal contamination from various jigs have been raised, greatly improving the cleaning degree of jigs in board manufacturing. It has become a challenge. In particular, in the semiconductor process, copper (Cu) is increasingly used in the wiring process, and there is a concern that copper cross-contamination may occur when the jig is cleaned. Cu, like the metal element Na of sodium hydroxide, which is one of the alkaline chemicals, has a high diffusion coefficient for the semiconductor substrate, and the presence of these metal atoms in the atmosphere of the semiconductor process controls the impurity concentration in each semiconductor layer. Cause serious trouble. In addition, when conventional cleaning methods are used for new materials such as Cu introduced in the circuit formation of Si wafers, problems such as corrosion of members, excessive etching, or reattachment of contaminants due to the new materials occur. . These problems also occur in the manufacturing process of a liquid crystal panel (system liquid crystal) in which a drive circuit is simultaneously formed on an active substrate.

  The present invention has been made in view of such conventional problems, and it is a jig that can remove foreign substances and metals by using only an acidic chemical solution, and can reduce the cleaning cost. A cleaning device and a cleaning method are realized.

  In order to solve this problem, a jig cleaning method of the present invention is a cleaning method for cleaning a jig used in a manufacturing process of a semiconductor or a liquid crystal substrate, and the jig is cleaned with nitric acid and hydrogen peroxide water. A first cleaning step, a heating step of heating the jig obtained in the first cleaning step in an atmosphere to which oxygen is added, and a jig obtained in the heating step are cleaned with ozone water to which hydrochloric acid is added And a second cleaning step.

  Here, the jig may be made of a ceramic member or a quartz member.

  Here, in the second cleaning step, an acidic chemical solution that maintains PH and a redox potential at which the metal to be contaminated is dissolved may be used.

  In order to solve this problem, a jig cleaning apparatus of the present invention is a cleaning apparatus for cleaning a jig used in a manufacturing process of a semiconductor, a liquid crystal substrate, or a solar cell, and the jig includes nitric acid and hydrogen peroxide solution. A first cleaning unit for cleaning by the above, a heating unit for performing heat treatment with addition of oxygen to the jig obtained by the first cleaning unit, and a hydrochloric acid for the jig obtained by the heating unit. And a second cleaning unit that performs a cleaning process with ozone water to which is added.

  Here, the first cleaning unit may regenerate and circulate at least one of nitric acid and hydrogen peroxide solution, and may add the hydrogen peroxide solution to the cleaning tank at an appropriate time.

  Here, the second cleaning unit may remove metal adhering to the jig to prevent metal contamination in the substrate manufacturing process.

  Here, the jig may be made of a ceramic member or a quartz member.

  As described above in detail, according to the present invention, it is possible to effectively clean the jig contaminated with a metal that adheres to the jig and easily diffuses from the surface of the substrate. Further, since the chemical solution and heating gas used for cleaning can be easily procured on the existing substrate manufacturing line, the jig cleaning process can be easily set up near the line of the substrate manufacturing apparatus.

  A jig cleaning apparatus and a cleaning method according to an embodiment of the present invention will be described with reference to the drawings. Here, the cleaning object is a jig made of a ceramic member or a quartz member, but the cleaning object may be a glass substrate, a semiconductor substrate, or a solar cell substrate. In heating devices, dry etching devices, and CVD devices used in semiconductor processes, the temperature at which the jig is exposed often exceeds, for example, the softening point of glass. With regard to jigs composed of such members, they do not cause elastic deformation at high temperatures (heat resistance), are inert to various semiconductor materials, are insulators, and are not eroded by acids or alkaline liquids. (Chemical resistance) and that it can be easily molded into a predetermined shape. However, other members may be used as long as these conditions are satisfied.

  Here, a cleaning technique in the semiconductor manufacturing apparatus will be described. As described in the section “Problems to be Solved by the Invention”, in the cleaning technology for new materials, the proper pH and redox are obtained after understanding the characteristics of all coexisting members and the adhesion mechanism of contamination. It is necessary to select a potential. The functions necessary for cleaning the trace contamination are summarized into three as shown in FIG.

  First, it is necessary to separate the contaminating particles P from the substrate S (function f1). Secondly, it is necessary to prevent redeposition of contamination in the liquid onto the substrate (function f2). Third, what is needed is a film etching function (function f3, not shown in FIG. 1). The function f1 is an object of the present invention. In the case of metal contamination, the metal tends to be separated from the substrate or the jig mainly by the solvent. Important parameters for metal dissolution are the solvent pH, redox potential, temperature, and the presence or absence of complexing agents. Of these, PH and redox potential are fundamental. In the matrix of PH and oxidation-reduction potential, it is important that the state of the metal in the thermodynamic equilibrium state, that is, the PH-potential diagram, considers the dissolution of the metal in the liquid.

FIG. 2 shows a PH-potential diagram of the Cu—H ₂ O system. In order to dissolve a metal such as Cu, the pH and potential of the solution may be controlled so that the dissolution regions indicated by Q1 and Q2 in the figure are obtained. For example, in the RCA cleaning method, HPM for removing metal contamination is a mixture of a strong acid (HCl) and a hydrogen peroxide solution (H ₂ O ₂ ), which is a strong oxidant, and therefore has an extremely low pH, and other than Si. Most metals can be dissolved.

  In view of such dissolution conditions, as a result of various trials and errors in the cleaning method, foreign matters on the surface of the ceramic member and the quartz member adhering to the substrate manufacturing process, for example, copper is a mixed solution of nitric acid and hydrogen peroxide solution. It was confirmed that it could be removed by oxidative decomposition by treatment (20% nitric acid, 10% hydrogen peroxide solution) and subsequent high-temperature treatment (900-1300 ° C) in an electric furnace. Moreover, it was not necessary to dare to use alkaline chemicals.

  FIG. 3 shows the overall configuration of the cleaning apparatus in the present embodiment. The cleaning apparatus includes a first cleaning unit 1 that performs mixed acid treatment on an object to be cleaned using nitric acid and hydrogen peroxide solution, and an electric furnace for an object to be cleaned obtained by the first cleaning unit 1. It comprises a heating unit 2 that performs high-temperature heating, and a second cleaning unit 3 that performs final cleaning of the jig using ozone water on the object to be cleaned obtained by the heating unit 2.

  FIG. 4 is a configuration diagram showing details of the first cleaning unit 1. The cleaning unit 1 has a cleaning tank 5 in which an object to be cleaned 4 is immersed. A nitric acid supply pipe 6, a hydrogen peroxide water supply pipe 7, and a pure water supply pipe 8 are connected to the cleaning tank 5. Yes. In addition, a chemical tank recycling tank 10 is provided at the lower part of the cleaning tank 5, connected to the cleaning tank 5 via a valve V 3, and connected to a waste liquid pipe 9 via a valve V 1. Further, a valve V2 is provided to directly discard the chemical solution in the cleaning tank 5, and is connected to the waste liquid pipe 9 through this valve. A valve V <b> 3 is provided between the cleaning tank 5 and the reuse tank 10. The chemical solution in the reuse tank 10 can be circulated through the circulation pump (P) 11, the circulation filter (F) 13, and the valve V5. The chemical solution in the reuse tank 10 can flow into the cleaning tank 5 through the valve V4, the circulation pump 11, the circulation filter 13, and the valve V6. Furthermore, a hydrogen peroxide solution replenishment tank 14 is provided outside the clarification tank 5, and the hydrogen peroxide solution can be replenished to the cleaning tank 5 by the operation of the replenishment pump (P) 15.

  FIG. 5 is a configuration diagram of the heating unit 2. This unit uses an electric furnace that performs high-temperature heat treatment. The heating unit 2 is provided with a plurality of heaters 16, a heat treatment table 17 on which the object to be cleaned 4 is placed, put in and out of the unit, and move up and down, and an oxygen supply pipe 18. Such a heating unit 2 may be one conventionally used as one facility of a semiconductor manufacturing apparatus.

  FIG. 6 is a configuration diagram of the second cleaning unit 3. The cleaning unit 3 is for cleaning the object to be cleaned 4 obtained by the heating unit 2 using ozone water added with hydrochloric acid. The cleaning unit 3 is provided with a cleaning table 19 on which the object to be cleaned 4 is placed. As the cleaning table 19, a plate-like member having a large number of holes is used in order to inject the cleaning liquid from the upper part and the lower part of the article 4 to be cleaned. The washing table 19 is preferably made of vinyl chloride or Teflon (registered trademark) having high chemical resistance.

  In the upper space and the lower space of the cleaning table 19, there are a nozzle N1 connected to the pure water pipe 20, a nozzle N2 connected to the nitrogen pipe 21, and a nozzle N3 connected to the ozone water pipe 22 added with hydrochloric acid. It is attached. On the outside of the cleaning table 19, an ozone water generation and preparation unit 23 and a hydrochloric acid water dilution unit 25 are provided. Pure water is supplied to both units through the pure water pipe 20. Further, a hydrochloric acid supply pipe 24 is connected to the hydrochloric acid water dilution unit 25 and 30 wt% hydrochloric acid is supplied and diluted to 5 wt% in the unit. Then, it is passed through the ozone water preparation unit 23. Each pipe is provided with a valve. In order to easily control the hydrochloric acid concentration, a hydrochloric acid dilution unit 25 is used.

  An operation of the jig cleaning apparatus configured as described above, that is, a jig cleaning method will be described. FIG. 7 is a process diagram showing the cleaning method in the present embodiment. Hereinafter, each cleaning step will be described with reference to FIGS.

  In the cleaning tank 5 of FIG. 4, nitric acid / hydrogen peroxide water is stored by injection from the supply pipes 6, 7, and 8. When the chemical solution in the reuse tank 7 becomes below the specified purity, it flows into the waste liquid pipe 9 via the valve V1. When the chemical solution in the cleaning tank 5 is directly discarded, the chemical solution is caused to flow through the waste liquid pipe 9 by opening the valve V2. Further, when the chemical solution in the cleaning tank 5 is reused, the valve V3 is opened and the chemical solution is flowed to the reuse tank 10. The chemical solution in the reuse tank 10 closes the valve V <b> 1 and opens the valve V <b> 4 to operate the circulation pump 11, and filters unnecessary substances with the circulation filter 13. When it is reused, it is returned to the cleaning tank 5 through the valve V6. When the cleaning tank 5 is refilled with the hydrogen peroxide solution, the refill pump 15 is operated to supply the hydrogen peroxide solution in the refill tank 14. In addition, when pure water is replenished to the cleaning tank 5 as pure water cleaning after chemical treatment, a pure water pipe 8 and a pure water shower nozzle 12 are used.

For example, after an object 4 to be cleaned such as a ceramic dome shown in FIG. 9A is placed in the treatment tank 5, a mixed solution of nitric acid and hydrogen peroxide solution is introduced by the method described above to perform immersion treatment (FIG. 9). 7 step S1). In this case, the concentration of nitric acid (HNO ₃ ) is 20%, the concentration of hydrogen peroxide (H ₂ O ₂ ) is 10%, and the immersion time is 3H. When the object 4 to be cleaned is heavily contaminated, hydrogen peroxide is replenished and charged using the auxiliary tank 14 in order to promote oxidative decomposition. After the immersion treatment, the chemical solution is recovered in the reuse tank 10 by opening the valve V3. The above process is referred to as a first cleaning process.

Next, pure water is added to perform water washing (step S2). The washing with water here is performed by repeatedly draining by supplying from the supply pipe 8 and opening the valve V2, and by using the shower nozzle 12. The temperature of pure water is 25 ° C, and each cleaning time is 20 minutes. The number of replacements of pure water was 3 times. Thereafter, it was dried manually with an N ₂ gun. The drying time in this case was 10 minutes (step S3).

  Next, the article to be cleaned 4 is transferred to the heating unit 2 in FIG. After the object to be cleaned 4 is placed on the heat treatment table 17, the substrate is heated at a temperature rising gradient of 2 to 4 ° C. to perform 900 to 1300 ° C. treatment (step S4). In this case, oxygen is supplied at 3 to 5 l / min at the time of temperature rise and at the maximum temperature. The temperature decrease gradient is performed at 2 to 4 ° C./min, which is substantially the same as the temperature increase gradient. For the temperature gradient and the maximum temperature, optimum conditions are applied depending on the material, shape, and thickness of the article 4 to be cleaned. The above process is called a heating process.

  The object to be cleaned 4 thus heated is transferred to the second cleaning unit 3 in FIG. Nitrogen in the nitrogen pipe 21 is heated to dry the object 4 to be cleaned. An ozone water generation and preparation unit 23 and a hydrochloric acid water dilution unit 25 are provided outside the cleaning table 19, and pure water is supplied to both units through a pure water pipe 20. Further, a chlorine supply pipe 24 is connected to the hydrochloric acid water dilution unit 25 and 30 wt% hydrochloric acid is supplied.

  Hydrochloric acid-added ozone water is produced by the ozone water generating and blending unit 23, supplied to the object 4 to be cleaned at about 3 l / min, and cleaned by the upper and lower nozzles at the tip of the ozone water pipe 22 (step S5). Also for pure water cleaning, cleaning is performed at a flow rate of about 3 l / min with the upper and lower nozzles at the tip of the pure water pipe 20 (step S6). The above process is referred to as a second cleaning process. Blow drying is performed by injecting heated nitrogen gas at a flow rate of 30 l / min from the tip nozzle of the nitrogen pipe 21 (step S7).

  Semiconductor manufacturing equipment used in the semiconductor manufacturing process, for example, a poly-Si dry etching apparatus, a metal dry etching apparatus, a ceramic member or a quartz member incorporated in a chamber of a low temperature chemical vapor deposition apparatus (LTO-CVD) On the other hand, the evaluation test of the cleaning apparatus according to the present embodiment was performed. A jig made of a ceramic member was removed from the semiconductor manufacturing apparatus, the jig was washed in the process shown in FIG. 7, and then attached to the semiconductor manufacturing apparatus again for evaluation. As a result, it has been found that there is no problem with the amount of foreign matter and metal contamination and that it can be reused. In other words, it was found that it is suitable as a method for regenerating and cleaning jigs.

In addition to the above evaluation test, an evaluation test was also performed on the Si wafer. A test solution to which a predetermined amount of copper ions was added was attached to the Si wafer by spin coating. Using the cleaning device 3 shown in FIG. 3 or FIG. 6, cleaning with ozone water to which 1% hydrochloric acid was added was performed to evaluate the removal of copper. The result is shown in FIG. ICP-MS (inductively coupled plasma mass spectrometer) was used to detect the amount of copper deposited. For example, in the treatment for 1040 seconds, the copper adhesion amount before the treatment is 10 atoms / cm ² , whereas the copper adhesion amount after the treatment is 1 atoms / cm ² or less, and a removal effect of 1/10 or more is obtained. It was.

  As a first feature of the cleaning apparatus of the present invention, a chemical reprocessing system as shown in FIG. 4 is used for a mixed acid treatment tank unit of nitric acid and hydrogen peroxide water in order to reduce the cost of the chemical used for cleaning. That is. Further, as a second feature, as shown in FIG. 6, ozone water showing an effect excellent in removal performance of metals such as copper is used for the final cleaning.

  In addition, the acidic chemical liquid and nitrogen gas used in the present embodiment, the heating unit is originally provided in a manufacturing factory having a semiconductor manufacturing apparatus, and the chemical liquid and gas required by the cleaning apparatus of the present invention are: Can be easily supplied on site. For this reason, the cleaning apparatus of the present invention can be installed in-line in a semiconductor manufacturing factory, a liquid crystal panel manufacturing factory, or a solar cell manufacturing factory.

  The cleaning apparatus and the cleaning method of the present invention can be used in a semiconductor substrate manufacturing process, a liquid crystal panel manufacturing process, and a solar cell manufacturing process. In particular, it is effective for a jig used in a CVD apparatus, a CVI apparatus, and a dry etching apparatus for processing a substrate, in which a substrate is formed at a high temperature in a sealed tank.

It is a conceptual diagram which shows the function required for washing | cleaning of trace contamination. It is a PH-redox potential diagram showing cleaning conditions for metal contamination. 1 is an overall configuration diagram of a cleaning device in an embodiment of the present invention. It is a block diagram which shows the detail of the 1st washing | cleaning unit which performs nitric acid / hydrogen peroxide water washing | cleaning. It is structural drawing which shows the detail of the heating unit which performs high temperature heat processing. It is a block diagram which shows the detail of the 2nd washing | cleaning unit which performs ozone water washing | cleaning which added hydrochloric acid. It is process drawing which shows the washing | cleaning method in embodiment of this invention. It is a figure which shows the result of having performed removal evaluation of the copper of the ozone water washing | cleaning which added 1% hydrochloric acid using the wafer. It is an external view which shows an example of a jig.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st washing | cleaning unit 2 Heating unit 3 2nd washing | cleaning unit 4 To-be-cleaned object (ceramics member, quartz member)
DESCRIPTION OF SYMBOLS 5 Washing tank 6, 7, 8 Supply piping 9 Waste liquid piping 10 Reuse tank 11 Circulation pump 12 Shower nozzle 13 Circulation filter 14 Replenishment tank 15 Replenishment pump 16 Heater 17 Heat treatment stand 18 Oxygen supply piping 19 Washing stand 20 Pure water piping 21 Nitrogen Piping 22 Ozone water piping 23 Ozone water generation and preparation unit 24 Hydrochloric acid supply piping 25 Hydrochloric acid water dilution unit V1-V6 Valve N1-N3 Nozzle

Claims (7)

  A cleaning method for cleaning a jig used in a manufacturing process of a semiconductor, a liquid crystal substrate, or a solar cell, wherein the jig is cleaned with nitric acid and hydrogen peroxide solution, and the first cleaning process. A heating step of heating the obtained jig in an atmosphere to which oxygen is added, and a second washing step of washing the jig obtained in the heating step with ozone water to which hydrochloric acid is added, How to wash the jig.   2. The jig cleaning method according to claim 1, wherein the jig is made of a ceramic member or a quartz member.   2. The method for cleaning a jig according to claim 1, wherein the second cleaning step uses an acidic chemical solution that maintains a pH and a redox potential at which the metal to be contaminated is dissolved.   A cleaning apparatus for cleaning a jig used in a manufacturing process of a semiconductor or a liquid crystal substrate or a solar cell, wherein the first cleaning unit cleans the jig with nitric acid and hydrogen peroxide, and the first cleaning unit. A heating unit for performing heat treatment with addition of oxygen to the obtained jig; a second cleaning unit for performing washing treatment with ozone water to which hydrochloric acid is added to the jig obtained with the heating unit; A jig cleaning apparatus comprising:   The jig cleaning unit according to claim 4, wherein the first cleaning unit recycles at least one of nitric acid and hydrogen peroxide solution, and adds the hydrogen peroxide solution to the cleaning tank in a timely manner. apparatus.   5. The jig cleaning apparatus according to claim 4, wherein the second cleaning unit removes metal adhering to the jig to prevent metal contamination in a substrate manufacturing process.   The said jig is comprised with a ceramic member or a quartz member, The cleaning apparatus of the jig of any one of Claims 4-6 characterized by the above-mentioned.

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