JP2013084723A - Method and apparatus for cleaning substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for cleaning a substrate, capable of preventing a water mark from remaining on a silicon surface, and contributing to space saving of the cleaning apparatus.SOLUTION: A method for cleaning a substrate includes: conveying a wafer to a hydrofluoric acid tank 4 and subjecting the wafer to wet etching using an HF solution in the hydrofluoric acid tank 4 to expose a silicon surface of the wafer; conveying the wafer to a pure water rinse tank 5 to rinse the wafer in the pure water rinse tank 5; conveying the wafer to a drying device 6 to dry the wafer in the drying device 6; after the etching using the HF solution and the rinsing and the drying of the wafer, conveying the wafer to an alkaline tank 2 to subject the wafer to alkaline cleaning in the alkaline tank 2 to form a thin chemical oxide film on the silicon surface; and conveying the wafer to a pure water rinse tank 3 to rinse the wafer in the pure water rinse tank 3.

Description

  The present invention relates to a substrate cleaning method and a substrate cleaning apparatus, and more particularly to a technique that can contribute to space saving of a cleaning apparatus while preventing a watermark from remaining on a silicon surface.

In general, in a so-called wafer process of a semiconductor device, a semiconductor element is formed on a wafer by repeating a photolithography technique. It is known that a watermark is generated in the washing process of the wafer process. As a means for suppressing the formation of a watermark, the method of Patent Document 1 is known.
It is understood that the cleaning method disclosed in Patent Document 1 is performed by the following procedure. That is, as shown in FIG. 7, first, treatment with hydrofluoric acid (HF) is performed to remove the natural oxide film formed on the silicon surface of the wafer (step S13), and then the residue of hydrofluoric acid is washed away. For this purpose, the wafer is rinsed with pure water (step S14). Further, the wafer is treated with an alkali (including hydrogen peroxide) chemical solution to form a thin silicon oxide film on the surface thereof (step S15), and the wafer is rinsed with pure water to wash away residual components of the alkaline chemical solution (ie, Washing with water) (step S16). Thereafter, the wafer is spin-dried (step S17).

  In other words, the cleaning method disclosed in Patent Document 1 states that “the natural oxide film formed on the silicon surface of the wafer is etched with hydrofluoric acid and rinsed with pure water. Next, the wafer immediately after rinsing is not dried. In this cleaning method, the wafer in a state where water droplets are attached is immersed in a liquid containing an oxidizing agent to form a chemical oxide film on the surface thereof, and then the formed chemical oxide film is maintained until the end.

  It is understood that such a cleaning method is performed using a cleaning apparatus 200 as shown in FIG. That is, as shown in FIG. 8, the cleaning apparatus 200 includes an alkali tank 202 and a pure water rinse tank 203 between a wafer input port (ie, loader) 201 and a wafer discharge port (ie, unloader) 209. A hydrofluoric acid tank 204, a pure water rinse tank 205, an alkali tank 206, a pure water rinse tank 207, and a drying device 208. The tanks 202 to 207 and the drying device 208 are arranged in one direction from the wafer input port 201 toward the discharge port 209 in accordance with the procedure of the cleaning process. In this cleaning apparatus 200, an alkaline tank 206 is disposed immediately after the pure water rinse tank 205 in order to suppress the generation of watermarks.

In addition, the alkali tank 202 and the pure water rinse tank 203 in front of the hydrofluoric acid tank 204 are tanks for performing a pretreatment for the hydrofluoric acid treatment. The purpose of this pretreatment is to remove foreign matters such as particles and organic substances that may adhere to the wafer surface. Alkaline tanks 202 and 203 pure water rinse tanks for performing the pretreatment are generally prepared in a cleaning apparatus having a hydrofluoric acid tank.
In addition, the above pretreatment may be omitted depending on the type of film forming process, diffusion process, and the like subsequent to the cleaning process performed by the cleaning apparatus 200. In that case, as indicated by a two-dot chain line arrow in FIG. 8, the wafer passes through the alkali tank 202 and the pure water rinse tank 203 from the wafer insertion port 201 and is directly transferred to the hydrofluoric acid tank 204.

Japanese Patent Laid-Open No. 11-016866

By the way, in the manufacturing site of a semiconductor device, the space saving is an always demanded problem. There has also been a demand for space saving in the cleaning apparatus.
Therefore, the present invention has been made in view of such circumstances, and a substrate cleaning method that can contribute to space saving of the cleaning device while preventing the watermark from remaining on the silicon surface, and An object of the present invention is to provide a substrate cleaning apparatus.

  In order to solve the above problems, the present inventor has found the following points. That is, in the prior art, after removing the natural oxide film, the wafer is rinsed with pure water, and the chemical oxide film is formed without drying the rinsed wafer. However, if a chemical oxide film is formed on the silicon surface of the wafer by alkali cleaning even after the wafer is dried, the same effect (watermark prevention) as in the prior art can be obtained.

  That is, in order to solve the above-described problem, a substrate cleaning method according to one aspect of the present invention includes a first step of exposing a silicon surface of a substrate by wet etching, and the substrate after the first step. A second step of washing with water, a third step of drying the substrate after the second step, and an alkali cleaning of the substrate after the third step to form a silicon oxide film on the silicon surface. And a fifth step of washing the substrate with water after the fourth step.

  Here, examples of the “substrate” include a substrate made of single crystal silicon (that is, a silicon wafer), an SOI (Silicon On Insulator) wafer, and the like. As the “silicon surface” of the substrate, for example, in the case of a silicon wafer, the surface of the silicon wafer, the surface of a single crystal silicon film formed directly or indirectly on the surface of the silicon wafer, a polycrystalline silicon film Or the surface of an amorphous silicon film. In the case of an SOI wafer, the surface of a silicon layer (also referred to as an SOI layer) of the SOI, the surface of a single crystal silicon film formed directly or indirectly on the surface of the SOI layer, the surface of a polycrystalline silicon film, or Examples include the surface of an amorphous silicon film.

The wet etching performed in the “first step” is, for example, wet etching using a liquid containing hydrofluoric acid (HF). Hereinafter, the liquid containing HF is also referred to as an HF solution. The water washing performed in the “second step” and the “fifth step” is, for example, washing using pure water. By washing with pure water, for example, the HF solution used in the first step can be washed away from the silicon surface. The alkali cleaning performed in the “third step” is, for example, cleaning using a liquid containing ammonia water (NH ₄ OH) and hydrogen peroxide water (H ₂ O ₂ ).

  With such a cleaning method, a watermark (that is, a thin oxide film locally generated on the silicon surface due to water droplets) is formed on the silicon surface during the transition from the second process to the third process. May be. However, in the fourth step, the watermark can be etched by alkali cleaning. In parallel with the watermark etching, a thin silicon oxide film (that is, a chemical oxide film) can be formed on the silicon surface. Thereby, it is possible to prevent the watermark from remaining on the silicon surface in the cleaned substrate.

  Moreover, if it is said cleaning method, a board | substrate will be once dried at a 3rd process. Thereby, before performing a 4th process, a board | substrate can be waited in or out of a washing | cleaning apparatus, and the tank (namely, alkali tank) by which an alkali cleaning is performed at a 4th process is used efficiently. Can do. For this reason, the number of alkali tanks can be reduced (for example, to one tank), which can contribute to space saving of the cleaning device.

  The “substrate” in the present invention corresponds to, for example, a wafer 50 described later. As the “silicon surface”, for example, the surface of a polycrystalline silicon film 54 described later or the silicon surface 61 corresponds. In addition, the “first process” corresponds to, for example, step S3 described later. The “second process” corresponds to, for example, step S4 described later. As the “third step”, for example, step S5 described later corresponds. As the “fourth step”, for example, step S6 described later corresponds. As the “fifth step”, for example, step S7 described later corresponds.

  In the cleaning method, in the first step, wet etching is performed in a first tank that stores a liquid containing hydrofluoric acid, and in the second process, in a second tank to which pure water is supplied. The substrate is washed with water, and in the fourth step, the substrate is washed with an alkali in a third tank in which a liquid obtained by mixing ammonia water and hydrogen peroxide solution is stored. In the fifth step, pure water is supplied. The substrate may be washed with water in a fourth tank. The “first tank” of the present invention corresponds to, for example, a hydrofluoric acid tank 4 described later, and the “second tank” corresponds to, for example, a pure water rinsing tank 5 described later, and “third tank”. For example, an alkali tank 2 described later corresponds, and as the “fourth tank”, a pure water rinse tank 3 described later corresponds, for example.

  Further, in the above-described cleaning method, before performing the first step, the substrate is subjected to alkali cleaning in the third tank, and the substrate after the alkali cleaning is washed in water in the fourth tank. , May be further included. With such a cleaning method, even when foreign matters such as particles and organic substances are adhered to the silicon surface, these foreign matters can be removed before the first step. The pretreatment process and the fourth process also serve as the third tank, and the pretreatment process and the fifth process serve as the fourth tank. For this reason, it can further contribute to the space-saving of a washing | cleaning apparatus. The “pretreatment process” of the present invention corresponds to, for example, steps S1 and S2 described later.

  A substrate cleaning apparatus according to another aspect of the present invention includes: a first tank that exposes a silicon surface of a substrate by wet etching; and a second tank that rinses the substrate from which the silicon surface is exposed in the first tank. A tank, a drying apparatus for drying the substrate washed with water in the second tank, and a third tank for forming a silicon oxide film on the silicon surface by alkali cleaning the substrate dried by the drying apparatus. And a fourth tank for rinsing the substrate on which the silicon oxide film has been formed in the third tank. With such a cleaning apparatus, the above-described cleaning method can be realized. Therefore, it is possible to contribute to space saving of the cleaning device while preventing the watermark from remaining on the silicon surface.

  According to the present invention, it is possible to prevent the watermark from remaining on the silicon surface of the substrate. Moreover, it can contribute to space saving of a washing | cleaning apparatus.

The figure which shows the structural example of the washing | cleaning apparatus 100 which concerns on embodiment of this invention. The figure which shows the conveyance method of the wafer 50 in the washing | cleaning apparatus 100. FIG. The flowchart which shows the cleaning method of the wafer 50 which concerns on embodiment of this invention. The figure which shows the state of the wafer 50 in a washing | cleaning process. The figure which shows the modification in embodiment of this invention. The figure explaining the effect of alkali cleaning. The flowchart which shows the washing | cleaning method concerning a prior art example. The figure which shows the structural example of the washing | cleaning apparatus 200 which concerns on a prior art example.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. Note that, in each drawing described below, parts having the same configuration are denoted by the same reference numerals, and repeated description thereof is omitted.
(1) Cleaning Device FIG. 1 is a conceptual diagram illustrating a configuration example of a cleaning device 100 according to an embodiment of the present invention.
As shown in FIG. 1, the cleaning apparatus 100 is an apparatus for cleaning a substrate (hereinafter simply referred to as a wafer) such as a silicon wafer or an SOI wafer. The cleaning apparatus 100 includes a wafer inlet (ie, a loader) 1, an alkali tank 2, a pure water rinse tank 3, a hydrofluoric acid tank 4, a pure water rinse tank 5, a drying device 6, and a wafer discharge port. (That is, unloader) 7.

The alkali tank 2 is a tank for storing an alkaline solution so as to be discharged. The alkaline solution stored in this tank is, for example, a liquid in which ammonia water (NH ₄ OH), hydrogen peroxide water (H ₂ O ₂ ), and pure water (H ₂ O) are mixed at a preset ratio. . For example, the mixing ratio of each component of the alkaline solution is NH ₄ OH: H ₂ O ₂ : H ₂ O = 1: 2: 10 in volume ratio. Moreover, the alkali solution in the alkali tank 2 is hold | maintained at the temperature of 70 to 90 degreeC, for example.

  The pure water rinsing tanks 3 and 5 are tanks for storing pure water so as to be discharged. For example, the pure water rinsing tanks 3 and 5 are supplied with pure water by shower or the like from the upper side of the tank toward the inside of the tank. Moreover, the pure water rinse tanks 3 and 5 vibrate the pure water in a tank with an ultrasonic wave. As described above, the pure water rinsing tanks 3 and 5 supply pure water to the wafers in the tank and vibrate the pure water with ultrasonic waves as necessary. Thus, the wafer is rinsed with pure water (that is, washed with water).

The hydrofluoric acid tank 4 is a tank for storing the HF solution so that it can be discharged. The HF solution is, for example, a liquid in which HF and pure water are mixed at a preset ratio. For example, the mixing ratio of each component of the HF solution is HF (49%): H ₂ O = 1: 99 in volume ratio. That is, the HF solution is, for example, a 0.5% HF aqueous solution.
The drying apparatus 6 is an apparatus that dries the wafer after rinsed with pure water and washed away residual components such as an alkaline solution or an HF solution. As a method for drying the wafer in the drying apparatus 6, for example, IPA drying or Marangoni drying in which moisture is replaced with IPA (isopropyl alcohol) or drying, spin drying in which the wafer is rotated at high speed to remove moisture by centrifugal force, etc. Is mentioned.

  Further, as shown in FIG. 2, the cleaning apparatus 100 includes a transfer arm 10 that transfers a plurality of (for example, one lot = 25) wafers 50 while being accommodated in a cassette 60. The transfer arm 10 moves in a direction (hereinafter also referred to as a forward direction) from the wafer insertion port to the wafer discharge port, or in the opposite direction, and between one tank and the other tank (or one tank). And the drying device). As will be described later, the transfer arm 10 includes an alkali tank 2, a pure water rinse tank 3, a hydrofluoric acid tank 4, a pure water rinse tank 5, a drying device 6, between the wafer input port 1 and the wafer discharge port 9. The wafer 50 can be transferred while performing cleaning, rinsing, or drying treatment in the order of the alkaline tank 2, the pure water rinsing tank 3, and the drying device 6, respectively.

(2) Cleaning Method FIG. 3 is a flowchart showing a method for cleaning the wafer 50 according to the embodiment of the present invention. 4A and 4B are cross-sectional views showing the state of the wafer 50 in the cleaning process.
Here, the case where the wafer 50 shown in FIG. 4A is cleaned using the cleaning apparatus shown in FIG. 1 will be described. The wafer 50 is a silicon wafer, and a polycrystalline silicon film 54 is deposited on the silicon surface 51 via an insulating film 52 or an insulating film 53. Here, the insulating film 52 is, for example, a LOCOS (local oxidation of silicon) film for element isolation. The insulating film 53 is a gate insulating film, for example. The polycrystalline silicon film 54 is a gate electrode film, for example. As shown in FIG. 4A, the surface of the polycrystalline silicon film 54 has irregularities reflecting the step G of the insulating films 52 and 53.

  In step S <b> 1 of FIG. 3, first, a plurality of wafers 50 accommodated in the cassette 60 are loaded into the wafer loading slot 1. The introduced wafer 50 is carried into the alkali tank 2 by the transfer arm 10. In this alkaline tank 2, the wafer 50 is immersed and washed in an alkaline solution, and foreign matters such as particles and organic substances are removed from the surface thereof. Further, by contacting the alkaline solution in the alkaline bath 2, a thin silicon oxide film (that is, a chemical oxide film) (not shown) is formed on the surface of the polycrystalline silicon film 54 shown in FIG. . The thickness of the chemical oxide film is, for example, several inches.

Next, in step S <b> 2, the wafer 50 is taken out from the alkali tank 2 by the transfer arm 10, and the taken wafer 50 is carried into the pure water rinse tank 3. In the pure water rinsing tank 3, the wafer 50 is rinsed with pure water, and the remaining components of the alkaline solution are washed away. Note that the above steps S1 and S2 are pre-processing of step S3.
Next, in step S <b> 3, the wafer 50 is taken out from the pure water rinse tank 3 by the transfer arm 10, and the taken wafer 50 is carried into the hydrofluoric acid tank 4. In this hydrofluoric acid tank 4, the wafer 50 is immersed in the HF solution, and the chemical oxide film is wet etched. The immersion time of the wafer 50 in the HF solution is, for example, about 10 minutes. As a result, the surface of the polycrystalline silicon film 54 is exposed under the chemical oxide film, and the surface of the wafer 50 changes from hydrophilic to hydrophobic. That is, the chemical oxide film is hydrophilic and the polycrystalline silicon film 54 is hydrophobic. When the chemical oxide film is completely removed, the surface of the wafer 50 becomes a polycrystalline silicon film 54 and becomes hydrophobic.

Next, in step S <b> 4, the wafer 50 is taken out from the hydrofluoric acid tank 4 by the transfer arm 10, and the taken wafer 50 is carried into the pure water rinse tank 5. In the pure water rinsing tank 5, the wafer 50 is rinsed with pure water, and the remaining components of the HF solution are washed away.
Next, in step S <b> 5, the wafer 50 is taken out from the pure water rinse tank 5 by the transfer arm 10, and the taken wafer 50 is carried into the drying device 6. In the drying apparatus 6, the wafer 50 is dried by IPA drying, Marangoni drying, spin drying, or the like.

  In addition, although the process so far (namely, process of step S1-5: 1st round) is a continuous process, it does not need to be a continuous process between this step S5 and S6. That is, the wafer 50 that has finished the drying process in step S5 once stands by inside or outside the cleaning apparatus 100 according to the processing status of other lots in the cleaning apparatus 100, and temporarily stops the cleaning process. Also good. Further, in the process of moving from step S4 to step S5, in most cases, water droplets are partially attached to the surface of the polycrystalline silicon film 54, and the surface of the polycrystalline silicon film 54 is caused by the water droplets. In some cases, a watermark 55 is formed (see FIG. 4A). However, in the present invention, the watermark 55 may be formed at this stage. This is because the watermark 55 can be removed in the next step S6.

  In step S <b> 6, the wafer 50 is taken out from the drying device 6 (or a standby area not shown) by the transfer arm 10, and the taken wafer 50 is carried into the alkaline tank 2. At this time, the transfer arm 10 moves from the drying device 6 toward the alkaline tank 2 (that is, in the reverse direction) as shown by the arrow in FIG. In this alkaline tank 2, the wafer 50 is immersed and washed in an alkaline solution, and foreign matters such as particles and organic substances are removed from the surface thereof. The immersion time of the wafer 50 in the alkaline solution is, for example, about 7 minutes.

  The natural oxide film is removed from the surface of the polycrystalline silicon film 54 by this alkali cleaning. In parallel with the removal of the natural oxide film, the surface of the polycrystalline silicon film 54 is brought into contact with an alkaline solution to form a chemical oxide film. For example, when the watermark 55 is formed on the surface of the polycrystalline silicon film 54, the watermark 55 is also removed together with the natural oxide film by alkali cleaning. Then, as shown in FIG. 4B, the chemical oxide film 56 is formed on the surface of the polycrystalline silicon film 54 from which the watermark 55 has been removed, with a thin and uniform thickness.

That is, as shown in FIGS. 4A and 4B, by performing alkali cleaning after drying, the natural oxide film (including the watermark 55) formed on the surface of the polycrystalline silicon film 54 is etched. At the same time, a chemical oxide film 56 is newly formed. Thereby, the watermark 55 is removed from the surface of the polycrystalline silicon film 54.
Next, in step S <b> 7 of FIG. 3, the wafer 50 is taken out from the alkali tank 2 by the transfer arm 10, and the taken wafer 50 is carried into the pure water rinsing tank 3. In the pure water rinsing tank 3, the wafer 50 is rinsed with pure water, and the remaining components of the alkaline solution are washed away.

In step S <b> 8, the wafer 50 is taken out from the pure water rinse tank 3 by the transfer arm 10, and the taken wafer 50 is carried into the drying device 6. In the drying apparatus 6, the wafer 50 is dried by IPA drying, Marangoni drying, spin drying, or the like. Note that the processing in steps S6 to S8 (that is, the second round processing) is a continuous processing.
Further, in the process of moving from step S7 to step S8, the surface of the chemical oxide film 56 is entirely wetted with moisture. However, the polycrystalline silicon film 54 is covered with the chemical oxide film 56, and the polycrystalline silicon film 54 under the chemical oxide film 56 is oxidized by moisture on the chemical oxide film 56 at room temperature (for example, 25 ℃) can not happen. Therefore, it is possible to prevent the watermark from being formed again.

(3) Effects of the Embodiment According to the embodiment of the present invention, the watermark 55 may be generated on the surface of the polycrystalline silicon film 54 when step S5 of FIG. However, in the subsequent step S6, the thin chemical oxide film 56 can be formed on the surface of the polycrystalline silicon film 54 with a uniform thickness while the watermark 55 is etched. Therefore, it is possible to prevent the watermark 55 from remaining on the surface of the polycrystalline silicon film 54 in the wafer 50 after the cleaning process by the cleaning apparatus 100 is completed (that is, after being carried out from the wafer discharge port 7). .

  Further, according to the embodiment of the present invention, the wafer 50 is once dried in step S5. Thereby, before performing alkali cleaning of Step S6, wafer 50 can be made to stand by inside or outside cleaning device 100, and alkali tub 2 can be used efficiently. Further, the alkaline tank 2 is also used in step S1 and step S6. For this reason, compared with the conventional washing | cleaning apparatus 200 shown in FIG. 8, the tank number of the alkali tank 2 can be restrained to a required minimum number (for example, 1 tank). Further, the pure water rinsing tank 3 is also used in steps S2 and S7. As described above, the space saving of the cleaning device can be sufficiently achieved.

  Moreover, according to the embodiment of the present invention, in the alkaline bath 2, the alkaline solution is held at a temperature higher than room temperature (for example, 70 ° C to 90 ° C). For this reason, ammonia water and hydrogen peroxide water constituting the alkaline solution are easy to evaporate, and the concentration (mixing ratio) of the alkaline solution is likely to change. Therefore, it is necessary to periodically exchange the alkaline solution in the alkaline tank 2. . Here, the alkali tank 2 which the washing | cleaning apparatus 100 has is 1 tank, for example, compared with the conventional washing | cleaning apparatus 200, the number of tanks is small. Accordingly, the amount of the alkaline solution used can be reduced by the amount of the tank, and the cost for the cleaning process can be reduced.

(4) Modification In the above embodiment, steps S1 and S2 shown in FIG. 3 are pre-processing of step S3. The pretreatment in step S3 may be omitted depending on the type of film forming process, diffusion process, and the like subsequent to the cleaning process performed by the cleaning apparatus 100. For example, when silicide is formed on the polycrystalline silicon film 54 after the cleaning process, the steps S1 and S2 shown in FIG. 3 may be omitted. In that case, as shown by the two-dot chain line arrow in FIG. 5, the wafer 50 accommodated in the cassette 60 is passed through the alkali tank 2 and the pure water rinse tank 3 from the wafer inlet 1 to pass through the hydrofluoric acid tank. What is necessary is just to convey to 4 directly. This transfer is also performed by the transfer arm 10 shown in FIG.

(5) Others In the above embodiment, as shown in FIGS. 4A and 4B, the wafer 50 on which the polycrystalline silicon film 54 is deposited is the target of the cleaning process by the cleaning apparatus 100. Explained the case. However, in the present invention, the substrate to be cleaned is not limited to this.

  In the present invention, for example, a silicon wafer in a bare state (that is, a state in which no film is formed except for a natural oxide film), a SOI wafer in a bare state, or a state in which a single crystal silicon film is formed by an epitaxial growth method A substrate on which a watermark may be formed by a cleaning process, such as a wafer in which amorphous silicon is formed through an insulating film by a CVD method, may be the target of the cleaning process. Even in such a case, the same effect as the above embodiment can be obtained.

  That is, when the various substrates as described above are treated with the HF solution, the silicon oxide film is removed from the silicon surface 61 of the substrate as shown in FIG. Since the silicon surface 61 is hydrophobic, the substrate is in a state of repelling water droplets. Further, after rinsing with pure water, there is a possibility that a watermark 55 is formed on the silicon surface 61 as shown in FIG. However, in the present invention, after rinsing with pure water, the substrate is dried and then subjected to alkali cleaning. Thereby, the watermark can be removed from the silicon surface 61 as shown in FIG. In parallel with the removal of the watermark, a thin chemical oxide film 56 can be formed on the silicon surface 61 with a uniform thickness. Therefore, similarly to the above embodiment, it is possible to prevent the watermark from remaining on the silicon surface 61 after the cleaning process.

  Moreover, after etching with HF solution and rinsing with pure water, the substrate is once dried. Thereby, it becomes possible to make a board | substrate stand in or out of a washing | cleaning apparatus. Since the alkaline tank can be used efficiently and the number of alkaline tanks can be reduced, it is possible to contribute to space saving of the cleaning device.

1 Wafer slot (loader)
2 Alkaline tank 3 Pure water rinse tank 4 Hydrofluoric acid tank 5 Pure water rinse tank 6 Drying device 9 Wafer discharge port (unloader)
DESCRIPTION OF SYMBOLS 10 Transfer arm 50 Wafer 51 Silicon surface 52, 53 Insulating film 54 Polycrystalline silicon film 55 Water mark 56 Chemical oxide film 60 Cassette 61 Silicon surface 100 Cleaning apparatus

Claims (4)

A first step of exposing the silicon surface of the substrate by wet etching;
A second step of washing the substrate with water after the first step;
A third step of drying the substrate after the second step;
A fourth step of forming a silicon oxide film on the silicon surface by alkali cleaning the substrate after the third step;
And a fifth step of washing the substrate with water after the fourth step. In the first step, wet etching is performed in a first tank storing a liquid containing hydrofluoric acid,
In the second step, the substrate is washed with water in a second tank to which pure water is supplied,
In the fourth step, the substrate is alkali-cleaned in a third tank for storing a liquid obtained by mixing ammonia water and hydrogen peroxide water,
The substrate cleaning method according to claim 1, wherein, in the fifth step, the substrate is washed with water in a fourth tank to which pure water is supplied.   Before performing the first step, the substrate further includes a pretreatment step in which the substrate is alkali washed in the third tank and the substrate after the alkali washing is washed in the fourth tank. The method for cleaning a substrate according to claim 2. A first tank exposing the silicon surface of the substrate by wet etching;
A second tank for washing the substrate with the silicon surface exposed in the first tank;
A drying device for drying the substrate washed with water in the second tank;
A third tank for alkali cleaning the substrate dried by the drying apparatus to form a silicon oxide film on the silicon surface;
And a fourth tank for rinsing the substrate on which the silicon oxide film is formed in the third tank.

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