JP4603865B2 - Manufacturing method of silicon substrate with oxide film and silicon substrate with oxide film - Google Patents

Description

  The present invention relates to a method for manufacturing a silicon substrate with an oxide film having an oxide film with a thickness of 5 μm or more and few particles adhering to the surface, and a silicon substrate with an oxide film.

  Silicon substrates with an oxide film have been widely used in the field of semiconductors, and examples of common manufacturing methods include thermal oxidation and CVD, which are widely used. Since the oxide film is used as an insulating film, the oxide film thickness is comparatively thin and an angstrom order film is used.

  On the other hand, silicon substrates with oxide films are also used in optical waveguide device applications for optical communication and MEMS (Micro Electro Mechanical System) applications, but a much thicker oxide film is desired compared to the semiconductor field. An oxide film having a thickness of several μm (especially 5 μm or more) to 20 μm or more is required. There are two problems in producing this thick oxide film: production efficiency and surface particles. For example, when the thermal oxidation method widely used in the semiconductor field is applied to the production of an oxide film having a thickness of 15 μm, the production time is about 1000 hours and the production efficiency is very poor. Furthermore, due to the long oxidation time, there is a high probability that particles will adhere to the surface, and problems remain in quality.

  Recently, a method of thermally oxidizing polysilicon (References 1 and 2) has been reported as a fast oxidation method. The manufacturing method repeats the process of “depositing polysilicon on the substrate and oxidizing the polysilicon layer by oxidizing the substrate” until the desired oxide film thickness is reached. The production efficiency is difficult to improve. In addition, since the surface of the oxide film is rough and a thick oxide film is formed only on one side of the silicon substrate, there is a quality problem that the substrate is likely to warp due to non-uniform thermal stress distribution in the subsequent process.

On the other hand, the thermal oxidation method is attractive in that a dense and high-quality oxide film can be obtained on both the front and back surfaces of a silicon substrate by a simple operation. In the case of producing a thick oxide film of several μm or more, it is known that the progress of oxidation has a relationship in which the square of the oxide film thickness is proportional to the oxidation time according to the diffusion rule of oxygen atoms. That is, the thicker the oxide film thickness, the greater the time required for oxidation. As a method for improving the oxidation rate at the time of forming a thick oxide film, a method is adopted in which the oxidizing atmosphere is an atmosphere containing water vapor and, in some cases, is further pressurized. However, in general, when pressure thermal oxidation is performed, there are many particles on the surface of the oxide film, and countermeasures have been reported in Document 3, but the result is 10 / cm ² even after improvement. When particles of this level are present on the substrate surface, they are unsuitable for the use of bonded substrates (for example, SOI substrates) that are widely applied in MEMS applications and the like, and further improvements are required.

JP 2002-148462 A JP 2003-192328 A JP 2002-323635 A

The present invention has been made in view of the above problems, and a method for manufacturing a silicon substrate having a high-quality oxide film having a film thickness of 5 μm or more and an extremely small number of particles adhering to the surface, and oxidation An object is to provide a silicon substrate with a film.
It is another object of the present invention to provide a method and a composite substrate for manufacturing a high-quality composite substrate by using a silicon substrate with an oxide film having a small number of surface particles and bonding this to another substrate. .

The present invention has been made to solve the above problems, and is a method for manufacturing a silicon substrate with an oxide film having an oxide film having a thickness of 5 μm or more, wherein the silicon substrate is heat-treated in an atmosphere containing water vapor. Then, an oxide film with a predetermined thickness exceeding 5 μm is formed on the surface, and the surface of the silicon substrate with the oxide film is etched using a solution containing at least an HF solution so that the oxide film thickness remains at least 5 μm. It performs a process, then, that you provide a method of manufacturing a silicon substrate with an oxide film, characterized in that for cleaning.

Thus, if the silicon substrate is heat-treated in an atmosphere containing water vapor to form an oxide film on the surface, the surface of the silicon substrate with the oxide film is etched with a solution containing an HF solution, and then washed to obtain a dense Thus, a silicon substrate having a high quality oxide film can be obtained with very few particles adhering to the substrate surface.
Here, the “predetermined film thickness” formed by the above-mentioned heat treatment means a film thickness obtained by adding a desired film thickness (5 μm or more) of the oxide film to be left to a thickness to be removed in etching. In this way, if an oxide film having an amount exceeding the desired film thickness that will be the final product in the heat treatment is formed in consideration of the film thickness that is to be etched in advance, it is 5 μm or more even after the etching process is performed. A silicon substrate having an oxide film with a desired film thickness can be obtained.
Note that whether the oxidation heat treatment is performed under normal pressure or under pressure may be selected depending on the time required for forming the required film thickness and the convenience of the manufacturing apparatus, and the present invention can be applied to both.

Further, in the etching process, the concentration of HF is not to want to use a 5-30% solution.

  When the HF concentration of the solution used in this etching process is less than 5%, the etching time required for obtaining the same effect is longer than that in the case of 5 to 30%, which is inefficient. Further, if it exceeds 30%, in order to obtain the same effect, it is necessary to etch more of the oxide film, which is inefficient.

Further, in the above etching process, the surface of the silicon substrate with an oxide film, is not to desired to simultaneously scrubbing process is performed etching treatment.

  In this way, by carrying out the scrub treatment, particles adhering to the substrate surface can be physically removed, and a silicon substrate having a high-quality oxide film with extremely few particles can be obtained more reliably. It becomes possible.

Then, in the cleaning, at least SC-1 cleaning, not to want to do any of the SC-2 cleaning.

  Thus, by performing at least one of SC-1 cleaning and SC-2 cleaning after the etching process, particles adhering to the substrate surface can be surely removed, and a high-quality oxide film is provided. A silicon substrate can be obtained. In this case, the particles can be more reliably reduced by performing both SC-1 cleaning and SC-2 cleaning.

Further, in the present invention that provides a method of manufacturing a composite substrate, characterized in that to produce a silicon substrate with an oxide film produced by the oxidation film-coated silicon substrate manufacturing method of the present invention by affixing to another substrate.

  If the silicon substrate with an oxide film manufactured by the method for manufacturing a silicon substrate with an oxide film of the present invention is used, particles adhering to the substrate surface are very few, and can be bonded to other substrates without any problem. A composite substrate such as an SOI substrate with few (voids) can be easily manufactured.

Further, it is a silicon substrate with an oxide film having an oxide film having a thickness of 5 μm or more, and the number of particles adhering to the surface of the silicon substrate with an oxide film is 0.01 / cm ² or less. that provides an oxide film with a silicon substrate, wherein.

As described above, according to the present invention, the oxide film has a thickness of 5 μm or more, and the number of particles adhering to the surface of the silicon substrate with an oxide film is 0.01 / cm ² or less. A silicon substrate can be obtained and can be sufficiently used for optical waveguide device applications and MEMS applications for optical communication.

Using the silicon substrate with an oxide film of the present invention, Ru can be easily fabricated composite substrate.
If the silicon substrate with an oxide film of the present invention is used, the number of particles adhering to the substrate surface is extremely small, so that a high-quality composite substrate with few voids can be obtained by bonding with another substrate without any problem.

  The “particles” used above are detected as particles having a particle size of 0.3 μm or more using a foreign substance inspection apparatus (manufactured by Hitachi Electronics Engineering).

A method of manufacturing a silicon substrate with an oxide film having an oxide film having a film thickness of 5 μm or more as in the present invention, wherein the silicon substrate is heat-treated in an atmosphere containing water vapor to have a predetermined film thickness exceeding 5 μm An oxide film is formed on the surface, and the surface of the silicon substrate with the oxide film is etched using a solution containing at least an HF solution so that the film thickness of the oxide film remains at 5 μm or more. In particular, particles on the substrate surface can be efficiently removed by etching treatment, and a silicon substrate with an oxide film having a high quality oxide film having a film thickness of 5 μm or more and an extremely small number of particles can be manufactured. .
Further, the present invention is a silicon substrate with an oxide film having an oxide film with a thickness of 5 μm or more, and the number of particles adhering to the surface of the silicon substrate with an oxide film is 0.01 / cm ^2. The following silicon substrate with an oxide film has very few particles adhering to the substrate surface, and can be easily bonded to other substrates without problems and is sufficient for optical waveguide device applications and MEMS applications for optical communications. It is possible to produce a high-quality composite substrate that can be used.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.
In optical waveguide device applications and MEMS applications for optical communication, a thick oxide film is desired compared to the semiconductor field, and in particular, a thickness of 5 μm or more is required. In manufacturing, the manufacturing efficiency and particles adhering to the surface of the substrate were cited as problems.

  In the method of thermally oxidizing polysilicon as a high-speed oxidation method, the process becomes complicated, and it is difficult to improve the production efficiency, and the oxide film surface is roughened or a thick oxide film is formed only on one side of the silicon substrate. There was a quality problem that the substrate is likely to warp due to the non-uniformity of the thermal stress distribution.

Further, as a thermal oxidation method, there is a method of improving the oxidation rate when forming a thick oxide film, and there is a means for making the oxidizing atmosphere an atmosphere containing water vapor and, in some cases, further pressing. However, in general, when pressure oxidation is performed, the number of particles on the surface of the oxide film increases, and even in the improved method, the limit is about 10 / cm ^{2, and} the bonded substrate is widely used for MEMS applications. There was a problem that it was unsuitable for use.

Accordingly, the inventors of the present invention provide a method for manufacturing a silicon substrate with an oxide film having an oxide film having a thickness of 5 μm or more, wherein the silicon substrate is heat-treated in an atmosphere containing water vapor, and the predetermined film thickness exceeds 5 μm. An oxide film is formed on the surface, and the surface of the silicon substrate with the oxide film is etched using a solution containing at least an HF solution so that the oxide film thickness remains at 5 μm or more, and then cleaned. A method for manufacturing a silicon substrate with a film has been devised.
In such a manufacturing method, the surface of the oxide film is dissolved by performing an etching process in particular, and particles adhering to the substrate surface can be efficiently removed. A silicon substrate having a quality oxide film can be obtained.
In addition, if an oxide film having an amount exceeding the desired film thickness finally required in the heat treatment is formed in consideration of the film thickness (etching allowance) to be etched in advance, even after the etching process is performed. A silicon substrate having an oxide film having a film thickness of 5 μm or more can be obtained.
The present inventors found these things and completed the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic explanatory view showing a method for growing an oxide film on a substrate.
An example of an apparatus for producing a thermal oxide film on the silicon substrate 1 will be described.
First, a film thickness value obtained by adding an etching amount to a desired oxide film thickness is calculated in advance. For example, when the desired oxide film thickness is 5 μm and the thickness to be etched is 0.4 μm, the film thickness actually formed in the heat treatment is 5.4 μm. In this way, if an extra etching amount is formed in addition to the desired oxide film thickness, the desired thickness can be obtained without dividing the desired film thickness even after the subsequent etching process. A silicon substrate having an oxide film can be obtained.
Note that an etching amount suitable for removing particles adhering to the surface is about 0.4 μm.

  Next, as a method of forming an oxide film on the silicon substrate, for example, a thermal oxidation furnace 10 as shown in FIG. 1 is used, and a thermal oxide film is formed on both surfaces of the silicon substrate 1. The application of the present invention does not depend on the wafer diameter. The oxide film forming method may be a thermal oxidation method, and atmospheric pressure oxidation and pressure oxidation may be selected depending on the equipment used and the convenience of the oxide film thickness to be formed. However, the atmosphere is assumed to contain water vapor in order to improve the oxidation rate and obtain a dense one.

As a configuration example of the thermal oxidation furnace 10 to be used, a quartz furnace core tube 3 is set coaxially in a cylindrical cantal heater module 4. The heater module 4 is divided into three equal parts, and the inside of the core tube 3 can be soaked within ± 1 ° C. Nozzles 7 to 9 are inserted into the tail part of the quartz core tube 3, and hydrogen, oxygen, and nitrogen as carrier gas are supplied from each nozzle to cause a thermal reaction, thereby generating water vapor in the core tube and generating an atmosphere containing water vapor. Create it. Further, an exhaust pipe 6 was provided at the lower part of the core tube 3 on the side opposite to the nozzles 7 to 9. The silicon substrate 1 is set in a quartz holder 2 at equal intervals, inserted into the core tube 3, and closed with a silicon carbide cap 5. An oxidation condition is set and heat treatment is performed to form an oxide film on the silicon substrate.
As the oxidizing conditions, for example, a heater set temperature of 1000 ° C. and a pressure in the furnace core tube of 5 atm can be obtained, and a silicon substrate on which an oxide film having a thickness of about 10.5 μm is grown in an oxidation time of 70 hours can be obtained.

  It can be confirmed from the measurement result of the foreign matter inspection apparatus that a large number of particles are adhered to the surface of the silicon substrate with an oxide film thus obtained. These particles can hardly be removed by cleaning with an SC-1 solution (ammonia + hydrogen peroxide mixed solution) or an SC-2 solution (hydrochloric acid + hydrogen peroxide mixed solution) used in a general semiconductor manufacturing process. This is because the particles and the oxide film surface react and adhere strongly in the long-term thermal oxidation treatment. That is, if the surface including the reaction portion can be removed, a silicon substrate having a high-quality oxide film with extremely few particles can be obtained.

  As this method, for example, a polishing method such as CMP is conceivable. However, when a substrate having particles on the surface of the oxide film is polished, scratches are likely to remain in the vicinity of the presence of the particles. When is used, the probability that a void will occur at that location increases. In recent bonding applications, substrates with various thicknesses are required. In particular, in the case of a thin substrate having a thickness of less than 350 μm, it is difficult to cope with a polishing machine.

On the other hand, by performing an etching process using a solution containing the HF solution of the present invention, a silicon substrate having a high-quality oxide film with very few particles adhering to the surface can be obtained. At this time, it is desirable to efficiently etch the portion where the particles react with the substrate surface, and a solution having an HF concentration of 5 to 30% can most effectively remove the particles on the substrate surface.
When a solution with a HF concentration higher than 30% is used, the effect is weak, and in order to obtain the same particle removal effect as when a 5-30% solution is used, more oxide films are etched. It is inefficient because it is necessary.
Further, when a solution having an HF concentration of less than 5% is used, the etching rate is insufficient, so that a lot of etching time is required and it becomes inefficient.
Note that, as described above, in order to obtain an oxide film having a desired film thickness finally obtained, it is necessary to form an extra oxide film for etching in the heat treatment step.

  Further, by scrubbing the substrate surface simultaneously with the etching, particles can be removed more reliably. As a scrubbing method, it is sufficient that scratches do not enter the substrate surface, and a general sponge or the like may be used.

After etching, for example, cleaning with chemicals, ultrasonic cleaning, rinsing with water, etc. can remove particles other than those caused by oxide film remaining on the substrate surface. The HF solution and the like can be washed away.
At this time, it is preferable to perform cleaning using at least one of the SC-1 solution and the SC-2 solution. These solutions are often used for cleaning in general semiconductor manufacturing processes, and have a high effect of removing foreign substances.

In this way, a silicon substrate having a high quality oxide film having a film thickness of 5 μm or more and very few particles adhering to the surface can be obtained.
In addition, since the oxide film is formed on both surfaces, the warpage of the substrate is small, and a bonded composite substrate including an SOI substrate can be easily manufactured with high quality.
For example, a silicon substrate with an oxide film according to the present invention and another silicon substrate are brought into close contact with each other, and then bonded and heat treated at 1000 ° C. for 5 hours in an oxidation heat treatment furnace to produce a bonded SOI substrate. When a void (unbonded portion) was observed in the transmission image, no void was confirmed, and a high-quality SOI substrate was obtained.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited thereto.
Example 1
An oxide film having a predetermined film thickness of 10 μm (desired film thickness of 10 μm and a predetermined etching amount of about 0.4 μm is formed in a heat treatment process) is formed on a silicon substrate having a diameter of 4 inches (10.16 cm).
As a heat treatment of the silicon substrate, a thermal oxidation furnace 10 as shown in FIG. 1 is used.
A quartz furnace tube 3 having a diameter of 350 mm and a length of 2000 mm is set coaxially in a cylindrical cantal heater module 4 having a diameter of 400 mm and a length of 2500 mm. The heater module 4 is divided into three equal parts, and the inside of the core tube 3 can be soaked within ± 1 ° C. Three nozzles 7 to 9 having a diameter of 10 mm and a length of 200 mm are inserted into the tail portion of the quartz furnace core tube 3. Hydrogen is 3.6 L / min, oxygen is 2.0 L / min, and nitrogen is 25 L / min as a carrier gas. To produce a water vapor in the core tube and create an atmosphere containing the water vapor. Further, an exhaust pipe 6 was provided at the lower part of the core tube 3 on the side opposite to the nozzles 7 to 9. The silicon substrate 1 is set in a quartz holder 2 at equal intervals, inserted into the core tube 3, and closed with a silicon carbide cap 5. An oxidation condition is set and heat treatment is performed to form an oxide film on the silicon substrate.
As oxidation conditions, the heater set temperature was 1000 ° C. and the pressure inside the furnace tube was 5 atm, and the oxidation took 70 hours.

By performing such heat treatment, 50 silicon substrates on which an oxide film having an average film thickness of 10.7 μm was grown were obtained.
When the particle | grains of the board | substrate with an oxide film obtained in this way were measured with the foreign material inspection apparatus, the average number of particles per board | substrate was 825.2 pieces, and the board | substrate with 0 particle | grains was not confirmed.
Therefore, the surface of the oxide film is etched using a 25% HF aqueous solution for 1 minute, and then a cleaning process (SC-1 cleaning, SC-2 cleaning) generally performed for semiconductors is performed, and the number of particles is similarly measured. As a result, the average number of particles per substrate was 0.38 (0.0047 / cm ² ), and the number of substrates with 0 particles was 37. The etching amount at this time was 0.42 μm.
Further, using this substrate, another mirror-polished silicon substrate and a polished surface were bonded to each other at room temperature, and an SOI substrate was manufactured by bonding heat treatment at 1000 ° C. for 5 hours in an atmosphere containing water vapor. When this substrate was observed by infrared transmission, no void was generated.

From Example 1, it was possible to efficiently produce a silicon substrate having a very low quality oxide film having a target film thickness of 10 μm or more and 0.0047 particles / cm ² on the substrate surface.
Furthermore, an SOI substrate manufactured by bonding a manufactured substrate and another silicon substrate has no voids and has good quality, and can be sufficiently used for optical waveguide device applications and MEMS applications for optical communication.

(Example 2)
According to the same manufacturing method as in Example 1, 50 silicon substrates on which an oxide film having an average film thickness of 10.8 μm was grown were obtained.
The average number of particles per substrate was 850.3, and a substrate with zero particles was not confirmed.
Therefore, the surface of the oxide film is etched for 1 minute using a 25% HF aqueous solution, and at the same time, the substrate surface is scrubbed using a general sponge, and then a cleaning process (SC-1 cleaning, SC-2 cleaning). In the same manner, the number of particles was measured. As a result, the average number of particles per substrate was 0.12 (0.0015 particles / cm ² ), and 45 substrates were 0 particles. The etching amount at this time was 0.44 μm.
In addition, using this substrate, another silicon substrate and the polished surfaces were bonded to each other at room temperature, and an SOI substrate was manufactured by bonding heat treatment at 1000 ° C. for 5 hours in an atmosphere containing water vapor. When this substrate was observed by infrared transmission, no void was generated.

From Example 2, by performing scrubbing simultaneously with etching, a silicon substrate having a very high quality oxide film with a target film thickness of 10 μm or more and 0.0015 particles / cm ² on the substrate surface. Was able to be produced more efficiently.
The SOI substrate produced by bonding the produced substrate and another silicon substrate has good quality without voids, and can be sufficiently used for optical waveguide device applications and MEMS applications for optical communication.

(Example 3)
According to the same manufacturing method as in Example 1, 50 silicon substrates on which an oxide film having an average film thickness of 10.5 μm was grown were obtained.
The average number of particles per substrate was 832.1, and a substrate with zero particles was not confirmed.
Therefore, the surface of the oxide film was etched for 330 seconds using a 10% HF aqueous solution, and then the cleaning process (SC-1 cleaning, SC-2 cleaning) was performed. The average number of particles per unit was 0.53 (0.0065 particles / cm ² ), and there were 20 substrates with zero particles. The etching amount at this time was 0.39 μm.

Although the etching process time was somewhat longer than in Example 3, a silicon substrate similar to that in Example 1 having a target film thickness of 10 μm or more and 0.0065 particles / cm ² on the substrate surface was obtained. We were able to make it.

Example 4
According to the same manufacturing method as in Example 1, 50 silicon substrates on which an oxide film having an average film thickness of 10.5 μm was grown were obtained.
The average number of particles per substrate was 827.7, and no substrate with zero particles was confirmed.
Therefore, the surface of the oxide film was etched for 15 seconds using a 50% HF aqueous solution, followed by a cleaning step (SC-1 cleaning, SC-2 cleaning), and the number of particles was measured in the same manner. The average number of particles was 5.3 (0.065 particles / cm ² ), and a substrate with zero particles was not obtained. The etching amount at this time was 0.40 μm.

Here, this substrate was subjected to additional etching while confirming particles with a 50% HF aqueous solution. The particles could be removed after additional etching for 10 seconds. When the number of particles was confirmed after substrate cleaning, the average number of particles per substrate was 0.40 (0.0049 particles / cm ² ), and 32 substrates with zero particles were obtained. The total etching amount was 0.61 μm.

  In Example 4, the amount of etching required for particle removal increased compared with Example 1 although it was able to improve significantly compared with the past. As a result, the oxide film thickness becomes thinner than the target of 10 μm, and it is necessary to perform an additional oxidation treatment.

(Example 5)
According to the same manufacturing method as in Example 1, 50 silicon substrates on which an oxide film having an average film thickness of 10.6 μm was grown were obtained.
The average number of particles per substrate was 820.3, and no substrate with zero particles was confirmed.
Therefore, the surface of the oxide film was etched for 360 seconds using a 1.0% HF aqueous solution, and then the cleaning process (SC-1 cleaning, SC-2 cleaning) was performed. The average number of particles per sheet was 32.8 (0.40 particles / cm ² ), and a substrate with zero particles was not obtained.

Here, this substrate was additionally etched with 1.0% HF aqueous solution for 180 seconds, and the number of particles was confirmed after cleaning the substrate. The average number of particles per substrate was 29.8 (0.37 / cm3). ² ) A substrate with zero particles was not obtained, and the total etching amount at this time was 0.09 μm.

  In the fifth embodiment, the time required for the 0.4 μm etching equivalent to that in the first embodiment is calculated to be about 40 minutes, and the time required to obtain an etching amount from which particles are removed greatly increases.

When the surface of the oxide film is etched using a solution having an HF concentration lower than 5% or higher than 30% as in Examples 4 and 5, the time required for the etching process is increased, or a heat treatment step The thicker oxide film is formed in advance in consideration of the amount to be etched in the step, so that the present invention has a desired thickness of 5 μm or more and surface particles of 0.01 / cm 2. It is possible to obtain a silicon substrate with an oxide film of ² or less.
However, if the etching process is performed using a solution having an HF concentration of 5 to 30% as in Examples 1 to 3, the silicon substrate with an oxide film of the present invention can be more efficiently produced.

(Comparative Example 1)
The same manufacturing method as in Example 1 was performed to obtain 50 silicon substrates on which an oxide film having an average film thickness of 10.4 μm was grown.
The average number of particles per substrate was 847.6, and a substrate with zero particles was not confirmed.
After this, a cleaning step (SC-1 cleaning, SC-2 cleaning) was performed and the number of particles was measured in the same manner. The average number of particles per substrate was 823.3 (10.2 / cm ² ). A substrate with zero particles was not obtained.

  In Comparative Example 1, etching was not performed as a particle removal method, and only SC-1 cleaning and SC-2 cleaning were performed, but almost no particles could be removed. This is understood to be due to the fact that the particles and the oxide film surface react and adhere strongly in the long-term thermal oxidation treatment. As compared with the example, it can be seen that etching the surface of the oxide film as a particle removal method is highly effective and efficient.

  In addition, this invention is not limited to the said form. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

It is a schematic explanatory drawing which shows the method to grow an oxide film on a board | substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Holder, 3 ... Core tube, 4 ... Heater, 5 ... Cap,
6 ... exhaust pipe 7, 8, 9 ... nozzle, 10 ... thermal oxidation furnace.

Claims (7)

A method for manufacturing a silicon substrate with an oxide film having an oxide film having a thickness of 5 μm or more, wherein the silicon substrate is heat-treated in an atmosphere containing water vapor, and the remaining oxide film is etched to a desired thickness of 5 μm or more was added margin and the film corresponding to the thickness-up in thickness is formed on the surface of the oxidation film in excess of 5 [mu] m, the oxide film using a solution containing at least HF solution the surface of the oxide film-coated silicon substrate A method of manufacturing a silicon substrate with an oxide film, characterized in that an etching process is performed so that the film thickness remains at 5 μm or more, the film thickness of the oxide film is reduced, and then cleaning is performed.   2. The method for manufacturing a silicon substrate with an oxide film according to claim 1, wherein a solution having a HF concentration of 5 to 30% is used in the etching process.   3. The method for manufacturing a silicon substrate with an oxide film according to claim 1, wherein, in the etching process, the surface of the silicon substrate with an oxide film is subjected to a scrub process simultaneously with the etching process.   4. The method for manufacturing a silicon substrate with an oxide film according to claim 1, wherein at least one of SC-1 cleaning and SC-2 cleaning is performed in the cleaning. 5.   A method for producing a composite substrate, comprising: bonding a silicon substrate with an oxide film produced by the method for producing a silicon substrate with an oxide film according to any one of claims 1 to 4 to another substrate. . A silicon substrate with an oxide film having an oxide film with a thickness of 5 μm or more, and 0.01 particles / cm ² of particles having a particle diameter of 0.3 μm or more adhering to the surface of the silicon substrate with an oxide film. A silicon substrate with an oxide film, characterized in that:   A composite substrate produced by bonding the silicon substrate with an oxide film according to claim 6 to another substrate.

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