TW202312266A - Silicon wafer cleaning method and production method, method for evaluating concentration of hydrogen peroxide in cleaning fluid, and method for managing hydrogen peroxide concentration in cleaning fluid - Google Patents

Abstract

The present invention pertains to a cleaning method that roughens silicon wafers. The silicon wafer cleaning method: obtains beforehand the relationship between the cleaning temperature, the NH4OH concentration, the H2O2 concentration, and the roughening amount for the front and rear surfaces or the rear surface of a study silicon wafer that has an exposed bare surface without a native oxide film, when cleaning the wafer in a cleaning fluid that includes ammonium hydroxide and is an aqueous solution having a hydrogen peroxide concentration of 0-0.15 wt%; determines, based on the relationship, roughening cleaning conditions such as cleaning temperature, NH4OH concentration and H2O2 concentration; and roughens the front and rear surfaces or the rear surface of the silicon wafer to be roughened, which has an exposed bare surface without a native oxide film, by cleaning the silicon wafer to be roughened, under the determined roughening cleaning conditions. As a result, the present invention provides: a cleaning method whereby the front and rear surface or the rear surface of a silicon wafer can be roughened; a silicon wafer production method whereby a silicon wafer of which only one surface has been selectively roughened can be obtained; and a method for evaluating and a method for managing hydrogen peroxide concentration in minute amounts in a cleaning fluid that affects the roughening behavior.

Description

Cleaning method and manufacturing method of silicon wafer, method for evaluating hydrogen peroxide concentration in cleaning solution, and method for managing hydrogen peroxide concentration

The present invention relates to a cleaning method and manufacturing method of a silicon wafer, as well as a method for evaluating the concentration of hydrogen peroxide in the cleaning solution and a method for managing the concentration of hydrogen peroxide. Roughen the reverse side or reverse side.

The manufacturing steps of silicon wafers for semiconductor devices may be composed of the following steps: a single crystal manufacturing step of growing a single crystal rod using the Czochralski method (CZ method) or the like; Slicing and processing into a mirror-like wafer processing step; further, in order to increase added value, sometimes a tempering step for heat treatment and an epitaxial growth step for forming an epitaxial layer are sometimes included.

This mirror-like process includes a DSP (double-side polishing) step and a subsequent CMP (single-side polishing) step. More specifically, from the viewpoint of particle quality and handling, the DSP-processed wafer can be transported to the CMP step in a state of being stored in water after washing as needed without drying. Therefore, in the CMP step, it is necessary to carry the wafer stored in water to the CMP apparatus by gripping with a robot or the like. In addition, after CMP processing, it is also necessary to pick up a wafer wetted with abrasives, pure water, etc., and transfer it to a cleaning step as necessary.

In such a wafer processing step, it is necessary to transport the wafer in a wet environment instead of a dry environment, but especially in such a wet environment, when the wafer absorbed by the chuck is detached, it may occur even if the chuck is released. Still can not be separated and cause the situation of poor handling. As its reason, it is considered to be affected by the roughness of the wafer surface to be clamped. It is considered that if the roughness of the wafer surface to be clamped is too good, the contact area with the chuck will increase, and even if the clamp is released , the wafer still becomes difficult to detach, but it is considered that if the surface roughness of the wafer is poor, the contact area decreases and the wafer becomes easy to detach. Generally speaking, the surface of the wafer being clamped is more or less likely to form fixture marks and cause quality degradation. Therefore, the surface of the fixture is mostly the reverse side of the silicon wafer. Therefore, from the viewpoint of reducing poor handling, a wafer manufacturing method that can be roughened only on the reverse side of the silicon wafer is particularly desired.

As a general cleaning method for silicon wafers, there is a method called RCA cleaning. The so-called RCA cleaning is based on the purpose of combining SC1 (Standard Cleaning 1, standard cleaning solution 1) cleaning, SC2 ((Standard Cleaning 2, standard cleaning solution 2) cleaning, DHF (Diluted Hydrofluoric Acid, diluted Hydrofluoric acid) cleaning to implement the cleaning method. The so-called SC1 cleaning is a cleaning method, which mixes ammonia water and hydrogen peroxide water in any proportion, and etches the surface of the silicon wafer with an alkaline cleaning solution, thereby digging out the adhered particles. Lift-off, and further use the electrostatic repulsion between the silicon wafer and the particles to prevent the particles from reattaching to the silicon wafer and remove the particles. In addition, the so-called SC2 cleaning is a cleaning method, which uses a cleaning solution prepared by mixing hydrochloric acid and hydrogen peroxide water in an arbitrary ratio to dissolve and remove metal impurities on the surface of the silicon wafer. In addition, the so-called DHF cleaning is a cleaning method, which uses diluted hydrofluoric acid to remove the chemical oxide film on the surface of the silicon wafer. Further, ozone water with strong oxidizing power is sometimes used for cleaning to remove organic matter still attached to the surface of the silicon wafer and to form a chemical oxide film on the surface of the silicon wafer after DHF cleaning. The cleaning of the silicon wafer can be performed by combining these cleanings according to the purpose. Among them, SC1 is cleaning accompanied by etching, and therefore it is generally known that the surface roughness of the wafer increases after SC1 cleaning.

In addition, as a means of evaluating the surface roughness of the wafer, a Haze value obtained by an AFM (Atomic Force Microscopy, Atomic Force Microscopy) Sa (three-dimensional calculated average height) value and a particle counter can be used as an index. gainer. Haze is a value representing the so-called haze, which is widely used as an index of the roughness of the silicon surface, and the higher the degree of Haze, the rougher the surface of the wafer is. In Haze inspection using a particle counter, the throughput is very high, and the entire wafer surface can be inspected.

Patent Document 1 describes a method that uses a dilute aqueous solution to clean a silicon wafer to form a natural oxide film with different thicknesses. In the dilute aqueous solution, the composition of ammonium hydroxide, hydrogen peroxide and water is 1:1: 5～1:1:2000 range. Patent Document 2 states that during SC1 cleaning, if the concentration of OH ⁻ electrolytically separated from ammonium hydroxide is high, direct etching of Si is preferentially induced, and the surface roughness of the wafer increases. In addition, Patent Documents 3 to 6 also disclose techniques related to cleaning of semiconductor substrates such as silicon wafers.

In addition, SC1 cleaning solution, especially when used at high temperature, will cause the concentration of ammonium hydroxide and hydrogen peroxide to decrease due to decomposition and evaporation reactions. Therefore, it is desirable to monitor the concentration of the liquid drug and adjust it in such a way as to keep the concentration constant. As a method for evaluating the concentration of the SC1 cleaning solution, the concentration measurement method is performed by absorbance and refractive index. Although it is known to have high accuracy, its concentration range is still relatively limited. In particular, under the present circumstances, it is difficult to evaluate the situation of low-concentration liquid medicines. [Prior Art Literature] (patent documents)

Patent Document 1: Japanese Patent Application Laid-Open No. 7-66195. Patent Document 2: Japanese Unexamined Patent Publication No. 2011-82372. Patent Document 3: Japanese Patent Application Laid-Open No. 7-240394. Patent Document 4: Japanese Patent Application Laid-Open No. H10-242107. Patent Document 5: Japanese Patent Application Laid-Open No. 11-121419. Patent Document 6: Japanese PCT Publication No. 2012-523706.

[Problem to be solved by the invention] As mentioned above, in order to reduce the poor handling in the processing steps, a silicon wafer with a rough backside to be clamped is required. The present invention is formed to solve the above problems, and provides the following technologies: a cleaning method capable of roughening the front and back surfaces of a silicon wafer; A silicon wafer with one side roughened; and, an evaluation method, a management method capable of evaluating or managing the trace concentration of hydrogen peroxide in the cleaning solution which affects the roughening behavior. [Technical means to solve the problem]

In order to achieve the above object, the present invention provides a method for cleaning a silicon wafer, which is characterized in that the silicon wafer is roughened, and has the following steps: The cleaning solution concentration investigation step is to obtain in advance the amount of roughening of the front and back sides or the back surface of the roughened silicon wafer for investigation, the temperature of the cleaning solution, the concentration of ammonium hydroxide in the cleaning solution, and the cleaning solution The correlative relationship between the concentration of hydrogen peroxide in the above-mentioned roughened silicon wafer for investigation is obtained by roughening the silicon wafer for investigation with no natural oxide film but exposed bonding surface by cleaning with cleaning solution Or, the cleaning solution contains ammonium hydroxide and is an aqueous solution with a hydrogen peroxide concentration of 0-0.15% by weight; The roughening cleaning condition determination step is to determine the temperature of the cleaning solution, the concentration of the cleaning solution, Rough cleaning conditions of ammonium hydroxide concentration and hydrogen peroxide concentration; and, A roughening and cleaning step, which uses the roughening and cleaning conditions determined in the roughening and cleaning condition determination step to clean the silicon wafer to be roughened, which has no natural oxide film and exposes the bonding surface, to The roughening object performs roughening on the front and back sides or the back side of the silicon wafer.

According to such a cleaning method of a silicon wafer, a silicon wafer can be manufactured, the front and back or the back surface of which is roughened by a desired amount of roughening. Further, more appropriate roughening and cleaning conditions can be selected by investigating the concentration dependence of hydrogen peroxide on the amount of roughening. In particular, roughening cleaning conditions can be selected so that variations in the amount of roughening can be reduced, and cleaning can be performed.

At this time, in the cleaning solution concentration investigation step, the Haze value can be obtained by using a particle counter before and after the cleaning of the silicon wafer for investigation, and the increase in the Haze value after the cleaning can be used as the roughening value. quantity.

According to such a method, the roughening behavior and the amount of roughening can be monitored simply and with high throughput.

In addition, when the roughening and cleaning conditions are to be determined in the roughening and cleaning condition determining step, the roughening and cleaning conditions can be determined as follows: The hydrogen peroxide concentration is within a concentration range in which the variation in the amount of roughening relative to the variation in the concentration of hydrogen peroxide is not more than a specific value, and the silicon crystal to be roughened after the cleaning in the roughening cleaning step On the round surface, the natural oxide film formed in this cleaning remained.

According to such a method, even if the concentration of hydrogen peroxide in the cleaning solution changes, it is possible to more stably supply a wafer roughened with a desired amount of roughening. In addition, a wafer with a further sufficient roughness can be obtained.

In addition, in the step of determining roughening and cleaning conditions, the temperature of the cleaning solution can be set to 80° C. or higher.

According to such a method, fluctuations in the amount of roughening relative to fluctuations in the concentration of hydrogen peroxide can be further reduced, and roughened wafers can be supplied more stably.

In addition, the present invention provides a silicon wafer manufacturing method, which is characterized in that a silicon wafer can be obtained. The silicon wafer is cleaned by the silicon wafer cleaning method of the present invention. One side of the silicon wafer is subjected to CMP processing, and only the side opposite to the aforementioned side is selectively roughened.

In this way, by grinding only one side after roughening the front and back sides, it is possible to produce a wafer in which one side is in a good surface condition and selectively select only the side opposite to the side. made by roughening.

In addition, the present invention provides a method for manufacturing a silicon wafer, which is characterized in that a silicon wafer can be obtained. The silicon wafer is cleaned by the method for cleaning a silicon wafer of the present invention, and the single-chip cleaning method is used to clean the silicon wafer. Clean the backside for roughening.

This makes it possible to produce a wafer that is roughened by cleaning only the backside.

In addition, the present invention provides a method for evaluating the concentration of hydrogen peroxide in the cleaning solution, which is characterized in that it has the following steps: The cleaning solution concentration investigation step is to obtain in advance the amount of roughening of the front and back sides or the back surface of the roughened silicon wafer for investigation, the temperature of the cleaning solution, the concentration of ammonium hydroxide in the cleaning solution, and the cleaning solution The correlative relationship between the concentration of hydrogen peroxide in the aforementioned roughened silicon wafer for investigation has a natural oxide film and is roughened by cleaning with the aforementioned cleaning solution containing hydrogen Ammonium oxide and is an aqueous solution with a hydrogen peroxide concentration of 0 to 0.15% by weight; and, The hydrogen peroxide concentration evaluation step is based on the above-mentioned correlation obtained in advance in the cleaning solution concentration investigation step, based on the amount of roughening of the front and back sides or the back side of the roughened silicon wafer, and the temperature of the cleaning solution to be evaluated. , the concentration of ammonium hydroxide in the cleaning solution of the aforementioned evaluation object, the concentration of hydrogen peroxide in the cleaning solution of the aforementioned evaluation object is evaluated, and the roughened silicon wafer is a silicon wafer with a natural oxide film by The aforementioned cleaning solution for evaluation is roughened by cleaning, and the cleaning solution for evaluation is an aqueous solution containing at least ammonium hydroxide.

Such a method for evaluating the concentration of hydrogen peroxide in the cleaning solution can accurately evaluate the concentration of a small amount of hydrogen peroxide that affects the roughening behavior.

In addition, the present invention provides a method for managing the concentration of hydrogen peroxide in the cleaning solution, which is characterized in that the hydrogen peroxide in the cleaning solution of the aforementioned evaluation object is evaluated by the method for evaluating the concentration of hydrogen peroxide in the cleaning solution of the present invention concentration, Based on the evaluation result, the concentration of hydrogen peroxide in the evaluated cleaning solution is adjusted.

With such a method for managing the concentration of hydrogen peroxide in the cleaning solution, the concentration of hydrogen peroxide can be managed with high precision, and roughening can be performed stably. [Effect of the invention]

As long as the silicon wafer cleaning method of the present invention is used, the front and back surfaces or the reverse surface of the silicon wafer can be roughened. In addition, as long as the silicon wafer manufacturing method of the present invention is used, it is possible to manufacture a wafer in which one side of the wafer is in a good surface state and only the surface opposite to the surface is selectively roughened. . In addition, as long as it is the hydrogen peroxide concentration evaluation method and management method in the cleaning solution of the present invention, it is possible to accurately evaluate and manage a trace amount of hydrogen peroxide concentration in the cleaning solution for roughening cleaning.

Hereinafter, as an example of an embodiment, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. Firstly, the method and mechanism of the roughening phenomenon in the present invention are described. In Fig. 2, the wafer with the bonding surface exposed and after DSP is cleaned by changing the SC1 composition (liquid composition NH ₄ OH:H ₂ O ₂ :H ₂ O), cleaning temperature, and cleaning time (marked as level 1 to level 12), use the particle counter to obtain the roughness index, that is, the Haze value, and display the difference with the Haze value obtained in advance before washing. The amount of increase in the Haze value after this washing (hereinafter also referred to as the amount of Haze increase) is an example of the amount of roughening. Higher values indicate rougher surfaces. In addition, the surface observation results of Ref (standard product) without roughening and SEM (Scanning Electronic Microscopy) of levels 5 and 9 are also shown together.

The liquid agents used are 28% by mass ammonia water (NH ₄ OH) and 30% by mass hydrogen peroxide water (H ₂ O ₂ ), which are also indicated by mass (wt) % respectively. Furthermore, the so-called mass % is a concentration expressed as a percentage of the mass ratio between the cleaning solution and the solute (ammonium hydroxide, hydrogen peroxide) contained therein, and may also be expressed as wt%.

It can be seen that the Haze value significantly increases at levels 5, 6, 8, 9, and 12. If the SEM image is further observed, unevenness can be observed at level 5 and level 9, but such unevenness is not observed in the standard product. From the above analysis, it can be seen that at these levels, the surface has obvious roughness and has been roughened. On the other hand, in levels 3, 4, and 11, the increase was about 0.8 to 0.9 ppm, and the amount of increase, that is, the degree of roughening, was small and could not be said to have been roughened. Furthermore, the number of LLS (Localized Light Scatter, localized light scatterer) is also very large, and the defect quality deteriorates significantly. From the fact that the state of the surface after cleaning is a water-repellent surface, it is considered that the bonding surface is exposed during cleaning and etching of Si progresses remarkably to form etching pits. In other levels, the surface state is hydrophilic, but the increase in Haze is also slight.

The roughening mechanism will be described in detail. In SC1 cleaning, hydrogen peroxide acts as an oxidizing agent, and Si is oxidized to form SiO ₂ (natural oxide film, hereinafter also simply referred to as oxide film). Ammonium hydroxide releases OH ^- through ionization reaction, and SiO ₂ on the wafer surface is etched by this OH ^- . In the general liquid chemical (cleaning liquid) composition (for example, NH ₄ OH: H ₂ O ₂ : H ₂ O = 1: 1: 10), there is often an oxide film on the wafer during cleaning, and the bonding The surface (Si) is not exposed, and the thickness of the formed oxide film is often about 1nm without depending on the cleaning time. This is known to be due to a balance between oxidation rate and etching rate. That is to say, in liquid chemicals with H ₂ O ₂ above a certain concentration, the oxidation rate of Si generated by H ₂ O ₂ is faster than the etching rate of SiO ₂ generated by ^OH- , so it can explain the An oxide film is not exposed and often exists on the wafer. In other words, if H ₂ O ₂ is below a certain concentration, the etching rate generated by ^OH- will become faster than the oxidation rate of Si generated by H ₂ O ₂ , so the oxidation will be too late to keep up and proceed. Etching reaction of Si by OH ^- generation. In such a case, Si will be exposed after washing and thus become a water-repellent surface.

It can be seen that the roughened level of the liquid chemical composition here is, for example, NH ₄ OH:H ₂ O ₂ :H ₂ O=1:0.4:1000 at level 5, and the ratio of H ₂ O ₂ is lower than that of NH ₄ OH. Therefore, it is considered that if such a liquid chemical is used to clean the silicon wafer on the joint surface, the surface state after cleaning will be a hydrophilic surface, so the oxidation reaction will proceed at first to form an oxide film, but the oxidation rate is relatively slow, so SiO ₂ Etching of SiO 2 is relatively advantageous, and SiO ₂ is etched, and Si is etched where Si is partially exposed, thereby roughening.

Thus, the roughening phenomenon in the present invention is a phenomenon that proceeds in a range where the oxidation reaction and the etching reaction are in balance. In addition, in order to stably progress the roughening, it is necessary to perform washing with a liquid composition and a liquid chemical concentration in which these reactions are stable.

Based on the above, the cleaning method of the present invention will be described. Fig. 1 is a flow chart showing an example of the method for cleaning a silicon wafer according to the present invention. (Step S1: cleaning solution concentration investigation step) In S1 in FIG. 1 , the cleaning solution concentration investigation step is performed as a preliminary test for selecting roughening cleaning conditions that can stably progress the roughening phenomenon. That is, it is a step of obtaining in advance the correlation between the amount of roughening and the temperature of the cleaning solution, the concentration of ammonium hydroxide in the cleaning solution, and the concentration of hydrogen peroxide in the cleaning solution. Here, the above-mentioned so-called roughening amount means that silicon wafers for investigation (without natural oxide film) are bonded to each other by using a cleaning solution (an aqueous solution containing ammonium hydroxide and a hydrogen peroxide concentration of 0 to 0.15 wt%). The amount of roughening of the front and back surfaces (or the back surface) obtained by roughening by washing the exposed surface) can be, for example, the above-mentioned Haze increase amount. As long as it is the amount of Haze increase, the roughening behavior and the amount of roughening can be monitored easily and efficiently, which is preferable. Furthermore, as an example of the above-mentioned cleaning solution, when the concentration of hydrogen peroxide is set to 0 wt%, it can be made as an aqueous solution containing ammonium hydroxide, and in addition, if the concentration of hydrogen peroxide is not 0 wt%, it can be set to Aqueous solution containing ammonium hydroxide and hydrogen peroxide.

Hereinafter, a more specific example will be given and described with respect to the cleaning solution concentration investigation procedure. Figure 3 shows the increase in Haze before _and after cleaning when a silicon wafer for investigation without a natural oxide film on the bonding surface was cleaned at 80°C for 3 minutes. The H ₂ O ₂ concentration was varied among three levels of 0.13 and 0.25 wt%. For the case where the NH ₄ OH concentration is 0.03 wt%, the state of the surface after washing is also shown (○ is the water-repellent surface, ● is the hydrophilic surface).

For example, focusing on the case where the concentration of NH ₄ OH is 0.03 wt%, it can be seen that the amount of increase in Haze varies depending on the concentration of H ₂ O ₂ . When the concentration of H ₂ O ₂ is 0 wt% and 0.007 wt%, the increase of Haze is small. The reason is that if the concentration of H ₂ O ₂ is too low, the oxidation rate becomes too slow, and only the etching action on Si proceeds. This point coincides with the fact that the surface state after washing only with a low concentration level of H ₂ O ₂ is a water-repellent surface (the bonded Si surface is exposed). As mentioned above, in the case of a water-repellent surface, etching of Si becomes remarkable and LLS quality (LLS number) deteriorates, so it is desirable to roughen within the range which becomes a hydrophilic surface. When the concentration of H ₂ O ₂ is 0.019 wt% to 0.078 wt%, the surface state is hydrophilic and the increase of Haze is relatively large, which results in roughening. Then, below 0.09 wt% is a hydrophilic surface, but the increase in Haze becomes smaller. The reason is that the concentration of H ₂ O ₂ is too high, so the oxidation rate of Si becomes significantly faster than the etching rate, and the etching effect becomes relatively weak.

Furthermore, the step of investigating the cleaning concentration is preferably performed with a plurality of levels of NH ₄ OH concentration and cleaning temperature. As shown in the figure, the increase in Haze increases as the NH ₄ OH concentration increases, so when setting a desired increase in Haze (amount of deterioration) in step S2 described later, there may be cases where there are multiple levels of investigation results. Easy to select rough cleaning conditions.

In addition, as a result of investigation by the inventors, when the concentration of H ₂ O ₂ exceeds 0.15 wt%, even if the concentration of NH ₄ OH is increased within a practical range, the oxidation rate will be increased without roughening. Therefore, in step S1, as mentioned above, it is carried out when the concentration of H ₂ O ₂ is 0-0.15 wt%.

(Step S2: Roughening and cleaning condition determination step) Then, based on the result of S1, the roughening and cleaning condition determination step of S2 is carried out. That is, it is a step in which the temperature of the cleaning solution, the concentration of ammonium hydroxide in the cleaning solution, and the concentration of hydrogen peroxide in the cleaning solution are determined based on the correlation of S1. net condition. Furthermore, the value of the expected Haze increase can be determined according to its degree.

In this step, in particular, the purpose is to select a roughening cleaning condition that stabilizes the variation of the Haze increase relative to the variation of the H ₂ O ₂ concentration based on the correlation obtained in S1. In Fig. 3, it can be seen that when the concentration of NH ₄ OH is 0.03 wt%, the change of Haze increase is small in the range of 0.032-0.078 wt%, and it is stable. At this time, for example, by setting the H ₂ O ₂ concentration to 0.05 wt%, even if the H ₂ O ₂ concentration in the cleaning solution fluctuates unexpectedly, the change in the amount of Haze increase is relatively small, showing Since it is stable, roughening can be performed more stably with a desired increase amount of Haze without greatly deviating from the desired increase amount of Haze. In this way, the _{H2O2 concentration} selected as one of the roughening and cleaning conditions is preferably below a small value ( _expected value) corresponding to the change in the amount of Haze increase relative to the change in the _H2O2 concentration. The range of H ₂ O ₂ concentration is determined. This specific value can be appropriately set with a numerical value equal to or greater than 0 depending on the required accuracy and the like.

Then, focusing on the case where the concentration of NH ₄ OH is 0.13 wt% and 0.25 wt%, when the concentration of H ₂ O ₂ is low, the oxidation rate is slow, which will become an advantage in etching, and the increase of Haze will change greatly, and it can be judged that unstable. Therefore, it is not desirable to perform roughening in this range. Since the etching rate becomes faster as the NH ₄ OH concentration becomes higher, it is considered that the variation becomes larger than 0.03 wt%. However, it is known that as the H ₂ O ₂ concentration increases, there is a H ₂ O ₂ concentration range in which the increase in Haze is stable, similar to the case of 0.03 wt%. If the concentration of NH ₄ OH is different, the H ₂ O ₂ concentration range required to stabilize the increase in Haze will also change. Therefore, roughening can be performed more stably by obtaining the appropriate concentration range of H ₂ O ₂ in advance. .

Also, from the viewpoint that the increase in Haze increases as the NH ₄ OH concentration increases, desired roughness (increase in Haze) can also be formed by adjusting the NH ₄ OH concentration. For example, when one wants to obtain a wafer with a Haze increase of 5 ppm, the following roughening cleaning conditions can be selected: the concentration of NH ₄ OH is set to 0.03 wt% and the concentration of H ₂ O ₂ is set to 0.05 wt%, at 80 °C for 3 minutes. On the other hand, when it is desired to obtain a wafer with a Haze increase of 30 ppm, the following roughening cleaning conditions can be selected: the concentration of NH ₄ OH is set to 0.25 wt% and the concentration of H ₂ O ₂ is set to 0.07 wt% , at 80°C for 3 minutes. By ascertaining in advance the change in the amount of Haze increase with respect to the concentration of H ₂ O ₂ in this way, it is possible to select roughening cleaning conditions for more stable roughening.

In addition, in this step S2, the roughening is determined so that the natural oxide film formed in the cleaning in S3 remains on the surface of the silicon wafer to be roughened after cleaning in step S3 described later. The cleaning conditions and the degree of roughening can also be more sufficient, which is preferable. It is also possible to obtain a hydrophilic surface, and it is also possible to prevent deterioration of the number of LLS.

Next, the influence of the temperature of the cleaning solution (cleaning temperature) will be described. Figure 4 shows the change in Haze increase when cleaning is performed at cleaning temperatures of 45°C and 60°C when the NH ₄ OH concentration is 0.03 wt%, 0.25 wt%, and the cleaning time is 3 minutes . In all three levels, although the increase in Haze is still the condition, compared to Fig. 3 in the case of 80°C, it can be seen that the H ₂ O ₂ concentration range in which the increase in Haze stabilizes is narrower as described above. Therefore, it can be interpreted that a more stable roughening can be easily selected by setting the cleaning temperature at 80° C. or higher and performing the cleaning liquid concentration investigation step of S1 or the roughening cleaning condition determination step of S2. Wash condition. The reason for this is considered to be that the oxidation action of hydrogen peroxide is stable when the temperature is high. The upper limit of the cleaning temperature is not particularly limited, for example, it may be 90°C.

However, it does not necessarily need to be 80°C or higher, and there is a region where the increase in Haze increases at 60°C or lower, so the roughening can still proceed, and the cause can also be suppressed by shortening the life of the liquid drug, for example. The variation of Haze increase caused by the change of H ₂ O ₂ concentration in the cleaning solution.

Next, the influence of washing time will be described. Fig. 5 shows that in the cleaning solution with the concentration of NH ₄ OH 0.03 wt% and the concentration of H ₂ O ₂ 0.05 wt%, at the cleaning temperature of 80°C, at 30, 60, 180, 360 The amount of Haze increase when washing with the washing time in seconds. It can be seen that the longer the washing time, the greater the increase in Haze. Therefore, in addition to the concentration of NH ₄ OH, the concentration of H ₂ O ₂ and the cleaning temperature, the degree of roughening can be further adjusted by adjusting the cleaning time. The concentration of NH ₄ OH can be adjusted as above, and the washing time can also be adjusted to control the degree of roughening, as long as it is used appropriately according to needs. In this way, the acquisition of the correlation in S1 and the determination of the roughening cleaning conditions in S2 can also be performed in further consideration of the cleaning time.

(Step S3: roughening and washing step) Next, in the roughening and cleaning step of step S3, the silicon wafer to be roughened, which does not have a natural oxide film on the bonding surface, is cleaned under the roughening and cleaning conditions determined in S2. This is a step of roughening the front and back (or back) of the silicon wafer to be roughened by this cleaning. In this way, by implementing the step of S3 through the aforementioned S1 and S2, the aforementioned roughened wafer with the desired Haze increase can be reliably obtained. In addition, in particular, it is possible to manufacture with a stable roughening degree without greatly deviating from the desired increase in Haze (that is, the variation in the increase in Haze is small).

Next, a description will be given of the cleaning method when carrying out the cleaning of the present invention. Nowadays, most wafer cleaning methods use liquids such as liquid chemicals and pure water, which is called wet cleaning. Among them, the main methods are divided into a batch method in which a large number of wafers are cleaned at once, and a single wafer method in which individual wafers are processed one by one. In the batch type, both the front and back sides of the wafer are immersed in the liquid chemical in terms of device configuration, so if the cleaning of the present invention is performed, the front and back sides will be roughened. On the other hand, in the single-wafer type, liquid chemicals are sprayed while rotating the wafer, so only one side of the wafer can be cleaned. According to the investigation of the present inventors, the present invention can roughen both the batch method and the single chip method. An appropriate method can be selected in consideration of wafer manufacturing steps.

As mentioned above, to produce a wafer with only the backside rough, only the backside can be cleaned if it is a single wafer type, and both front and back sides can be roughened together when it is a batch type. Therefore, like the silicon wafer manufacturing method of the present invention, it is desired that after cleaning by the cleaning method of the present invention, the quality of the front side, in particular, be made good by the polishing step. For example, use a batch cleaning machine to implement the wafer cleaning method of the present invention to roughen both the front and back sides of the silicon wafer, and then perform a single-sided process such as CMP grinding on one side (that is, the front side). By grinding, it is possible to manufacture a wafer which is selectively roughened only on the surface opposite to the surface (that is, the back surface). As long as it is such a wafer, it can be manufactured stably without causing chucking failure even in a wet environment.

Next, with regard to the cleaning solution used for roughening in the above-mentioned cleaning method of the present invention, a method for evaluating and managing the concentration of hydrogen peroxide in the cleaning solution will be described. As mentioned above, since the roughening behavior of the present invention strongly depends on the concentration of hydrogen peroxide, the roughening can be performed more stably by controlling the concentration of hydrogen peroxide. As a method for evaluating the liquid drug concentration of a general SC1 cleaning solution, there is a concentration measurement method based on absorbance and refractive index, and it is also known that its accuracy is high. However, when the inventors used the absorbance method to detect the concentration of the cleaning solution prepared with a concentration of NH ₄ OH of 0.25 wt% and a concentration of H ₂ O ₂ of 0.07 wt% in order to perform roughening and cleaning, although the detection The concentration of NH ₄ OH was 0.24 wt%, but the concentration of H ₂ O ₂ was below the lower limit of detection and could not be detected.

Therefore, the inventors made use of the above-mentioned roughening behavior to study the point that it is impossible to evaluate and manage the H ₂ O ₂ concentration. Fig. 6 is a flow chart showing the method for evaluating and managing the concentration of hydrogen peroxide in the cleaning solution according to the present invention. (Step S11: Cleaning solution concentration investigation step) Initially, as in the cleaning solution concentration investigation step of S11, it is the following investigation step: for the silicon wafer (with a natural oxide film) for investigation, the amount of roughening (such as Haze increase) is obtained in advance. amount) and the temperature of the cleaning solution (an aqueous solution containing ammonium hydroxide with a hydrogen peroxide concentration of 0-0.15 wt%) and the correlation between the concentration of ammonium hydroxide in the cleaning solution and the concentration of hydrogen peroxide in the cleaning solution . Furthermore, as an example of the above-mentioned cleaning solution, when the concentration of hydrogen peroxide is 0 wt%, it can be made as an aqueous solution containing ammonium hydroxide, and in addition, if the concentration of hydrogen peroxide is not 0 wt%, it can be used as a solution containing Aqueous solution of ammonium hydroxide and hydrogen peroxide (SC1 cleaning solution).

Here, different from the cleaning solution concentration investigation step of step S1 in the cleaning method of the silicon wafer of the present invention (using the silicon wafer without a natural oxide film as the investigation), in the cleaning method of the present invention The reason why the cleaning liquid concentration investigation step of the step S11 of the method for evaluating the concentration of hydrogen peroxide in the liquid is used is as follows. In the cleaning method, in particular, it is necessary to seek a region where the variation in the amount of roughening relative to the fluctuation of the amount of hydrogen peroxide is small and stable. Even if a product without a natural oxide film is used, the tendency as shown in Fig. 3 can be obtained, but such In some cases, on the contrary, it becomes impossible to obtain the concentration of hydrogen peroxide corresponding to the amount of roughening without any difference. On the other hand, when there is a natural oxide film, as described later, the higher the concentration of hydrogen peroxide tends to decrease the amount of roughness, so the concentration of hydrogen peroxide can be obtained without any difference from the amount of roughening.

Hereinafter, a more specific example will be given for the cleaning solution concentration investigation step. First, prepare a silicon wafer for investigation with a natural oxide film, and use a particle counter to obtain the Haze value before cleaning in order to calculate the increase in Haze. In addition, as a formation method of a natural oxide film, general SC1 cleaning and ozone water cleaning are mentioned. Such cleaning is not particularly limited as long as a natural oxide film can be formed after cleaning. Preferably: the mixing ratio (volume ratio) of the SC1 cleaning solution is, for example, NH ₄ OH:H ₂ O ₂ :H ₂ O=1:1:10, the temperature is 30-80°C, and the cleaning time is 90-360 Second. Preferably, the concentration of the ozone water is in the range of 3-25 ppm, the temperature is 10-30° C., and the cleaning time is 60-360 seconds.

Then, prepare the aforementioned cleaning solution at various temperatures, change the concentration of NH ₄ OH and H ₂ O ₂ (further change the cleaning time as needed), and clean the silicon wafer for investigation with a natural oxide film After roughening the front and back (or back), use the particle counter to obtain the Haze value. Fig. 7 is a result showing the increase of Haze with respect to the H ₂ O ₂ concentration when the cleaning temperature is 80°C, the cleaning time is 3 minutes, and the NH ₄ OH concentration in the cleaning solution is 0.03 wt%. Unlike the tendency in the case of the joint surface (for example, Fig. 3 ), it can be seen that the higher the H ₂ O ₂ concentration, the more the Haze increase tends to decrease. In this way, the correlation among cleaning temperature, NH ₄ OH concentration, H ₂ O ₂ concentration and Haze increase is obtained in advance. Furthermore, according to the investigation results of the inventors, when the concentration of H ₂ O ₂ exceeds 0.15 wt%, the increase amount of Haze becomes a value close to 0, which is difficult to use as an index. On the other hand, the present invention is an evaluation method for a cleaning solution having an H ₂ O ₂ concentration of 0.15 wt % or less, which can accurately evaluate the H ₂ O ₂ concentration even in such a small amount.

(Step S12: hydrogen peroxide concentration evaluation step) Then, like the hydrogen peroxide concentration evaluation step of step S12, use the evaluation object cleaning solution (including at least an aqueous solution of ammonium hydroxide) to detect _{H2O2 concentration} , and use S11 The specific cleaning temperature (further specific cleaning time) in the obtained correlation is used to clean the silicon wafer with the natural oxide film as in S11 to obtain the Haze increase. In addition, the NH ₄ OH concentration can be measured and obtained by a conventional method, for example. In particular, if the washing temperature (and washing time) is set in advance, the steps of S11 and S12 can be performed at the same washing temperature, which can be easily performed. Then, based on the correlation obtained in S11, the H ₂ O ₂ concentration can be estimated from the Haze increase amount obtained above, the cleaning temperature (and cleaning time), and the NH ₄ OH concentration.

(Step S13: Hydrogen Peroxide Concentration Management Step) In addition, like the hydrogen peroxide concentration management step of Step S13), the hydrogen peroxide concentration in the cleaning solution can also be adjusted according to the evaluation result obtained in S12. For example, after cleaning for a specific period of time using a cleaning solution prepared so that the concentration of NH ₄ OH is 0.03 wt% and the concentration of H ₂ O ₂ is 0.05 wt%, the evaluation method of the present invention is used to evaluate H ₂ O ₂ concentration, when it is judged to be 0.04 wt%, hydrogen peroxide water can be added so that the H ₂ O ₂ concentration becomes 0.05 wt%. Conversely, when it is judged to be 0.06 wt%, pure water can be added so that the H ₂ O ₂ concentration becomes 0.05 wt%. By implementing such a management method, it is possible to increase the life of the liquid chemical, and to manufacture a roughened wafer in which the increase in Haze is stable. By doing so, it is possible to accurately evaluate and even manage a very small amount of H ₂ O ₂ concentration of 0 to 0.15 wt % in the cleaning solution, and to stably manufacture a desired roughened wafer. [Example]

Hereinafter, the present invention will be further described based on examples, but these examples are illustrative and not limited to interpretation. (Example 1) As shown in the cleaning method of the present invention in FIG. 1 , the step of investigating the concentration of the cleaning solution in S1 of the preliminary test was carried out in advance. The particle counter SP3 manufactured by KLA Co., Ltd. was used to obtain the Haze value of the silicon wafer without natural oxide film on the bonding surface after DSP processing (silicon wafer for investigation). Next, use 28% by mass of ammonia water (NH ₄ OH) and, if necessary, 30% by mass of hydrogen peroxide (H ₂ O ₂ ), and prepare NH ₄ at a cleaning solution temperature of 80°C. OH concentration of 0.03 wt% and 0.25 wt% of two levels of cleaning solution, change the concentration of H ₂ O ₂ in the range of 0 to 0.15 wt%, and use the cleaning time of 3 minutes to clean the above-mentioned After bonding the silicon wafer on the surface, use SP3 to obtain the Haze value, and calculate the roughness index, that is, the Haze increase amount, from the difference before and after cleaning. Figure 8 shows the relationship between the increase in Haze, the concentration of NH ₄ OH and the concentration of H ₂ O ₂ when the cleaning temperature is 80°C.

Then, the roughening and cleaning condition determination step of S2 is implemented. The purpose is to produce wafers with two levels of Haze increase of 10 ppm and 30 ppm. Based on the correlation relationship in Fig. 8 obtained in S1, the roughening and cleaning conditions for obtaining such increased amounts of Haze are determined. Regarding 10 ppm, focusing on the case where the NH ₄ OH concentration is 0.03 wt%, it can be seen that the H ₂ O ₂ concentration is in the range of about 0.03-0.08 wt%, and the Haze increase has a stable range of about 5-6 ppm. Therefore, in the next step S3, for the cleaning solution used for roughening the target silicon wafer, the concentration of NH ₄ OH is set to 0.03 wt%, and the concentration of H ₂ O ₂ is set to 0.03-0.08 wt%. 0.05 wt% within the range, and set the cleaning temperature to 80°C. Regarding the cleaning time, the increase of Haze is positively correlated with the cleaning time. Based on the increase of Haze of 5-6 ppm at 3 minutes, the cleaning time is set to 6 minutes which is twice the time of 3 minutes. With this setting, a Haze increase of about 10 ppm is expected.

With respect to 30 ppm, focusing on the case where the concentration of NH ₄ OH is 0.25 wt%, it can be seen that when the concentration of H ₂ O ₂ is in the range of 0.05-0.09 wt%, Haze increases by about 30 ppm and becomes stable. Based on this point, for the cleaning liquid, the concentration of NH ₄ OH was set to 0.25 wt%, the concentration of H ₂ O ₂ was set to 0.07 wt% in the range of 0.05 to 0.09 wt%, and the cleaning temperature was set to 80 ℃. The washing time was set to 3 minutes in the same manner as in the case of S1 from the point of increasing the amount of Haze which was 30 ppm at 3 minutes.

Then, implement the roughening and cleaning step of S3. Using the two levels of roughening cleaning conditions with the Haze increase target determined in S2 as 10 ppm and 30 ppm, the joints after DSP processing were bonded using a batch type cleaning machine with 5 pieces for each level. The silicon wafer without natural oxide film on the surface (silicon wafer to be roughened) is cleaned to roughen both sides, and the Haze value is obtained by using SP3, and the Haze increase is calculated. The average value of Haze increase for wafers with a target of 10 ppm was 10.7 ppm, and the average value of Haze increase for wafers with a target of 30 ppm was 31.2 ppm. Degree of wafer. In addition, the LLS quality is 1 pcs on a wafer with a target of 10 ppm and 0 pcs on a wafer with a target of 30 ppm, which is good.

For wafers with target Haze increases of 10 ppm and 30 ppm, which were roughened on both sides in this way, the surface side was subjected to CMP processing with a processing allowance of 500 nm. When the number of LLS was evaluated using SP5/19nmUP manufactured by KLA Co., Ltd. for each wafer processed by CMP, it was 12 pcs when the target was 10 ppm, and 9 pcs when the target was 30 ppm. The level 1 of the comparative example mentioned later has the same and favorable quality. Afterwards, when the handling test was repeated 200 times, it was possible to achieve the result that there was no defect at all for 200 times of handling in both levels. In this handling test, the back side of each wafer stored in water was clamped, and the wafer was Unloading (unchuck) is carried out on the stage of the grinder.

(Example 2) Next, based on the evaluation method of the present invention shown in FIG. 6 , the evaluation of the concentration of hydrogen peroxide in the cleaning solution for stably performing roughening cleaning was evaluated. Based on the results of S2 and S3 in Example 1, the cleaning solution with an NH ₄ OH concentration of 0.03 wt%, an H ₂ O ₂ concentration of 0.05 wt%, and a temperature of 80°C was evaluated so that the increase in Haze was 10 ppm. concentration of hydrogen peroxide. Initially, as in the cleaning solution concentration investigation step of S11, the relationship between cleaning temperature (80°C), NH ₄ OH concentration (0.03 wt%), H ₂ O ₂ concentration and roughening amount was obtained. Specifically, firstly, the silicon wafer is cleaned by using a cleaning solution of NH ₄ OH:H ₂ O ₂ :H ₂ O=1:1:10 at 80°C for 3 minutes to produce natural Wafers with oxide film (silicon wafers for investigation) use SP3 to obtain the Haze value. Then, in the cleaning solution with NH ₄ OH concentration of 0.03 wt% and cleaning temperature of 80°C, the concentration of H ₂ O ₂ was changed to clean the silicon wafer with natural oxide film for 3 minutes. Use SP3 to obtain the Haze value of the cleaned wafer and calculate the Haze increase. The result is the same as in Fig. 7. That is, when the H ₂ O ₂ concentration is 0.05 wt%, it is 41 ppm, and when it is 0.02 wt%, it is 181 ppm, and the amount of roughening (that is, the amount of Haze increase) is obtained with the increase of H ₂ O ₂ concentration. ) will become smaller correlation.

Then, the hydrogen peroxide concentration evaluation step of S12 is implemented. First, 200 silicon wafers were cleaned with the cleaning solution to manufacture double-sided roughened silicon wafers. In order to evaluate the concentration of hydrogen peroxide in the cleaning liquid (evaluation target cleaning liquid) of 200 wafers after cleaning, after cleaning the wafers with the natural oxide film for which the Haze value has been obtained, use SP3 to obtain the Haze value and Calculate the Haze increase. As a result, the increased amount of Haze was 60 ppm. Referring to the correlation in Fig. 7, the concentration of H ₂ O ₂ in the cleaning solution to be evaluated is about 0.04 wt%. From the fact that the target H ₂ O ₂ concentration before washing 200 tablets was 0.05 wt%, it was judged that the concentration decreased by about 0.01 wt%. It is considered that the cause may be the influence of the liquid chemicals attached to the wafer and the pure water (rinse) tank after 200 wafer cleaning.

Next, H ₂ O ₂ is added to the cleaning liquid so that the target H ₂ O ₂ concentration becomes 0.05 wt % in the hydrogen peroxide concentration management step of S13 . After that, for confirmation, after cleaning the wafer with the natural oxide film for which the Haze value was obtained, the Haze value was obtained using SP3 and the Haze increase was calculated. As a result, 40 ppm was found, and H ₂ O ₂ was found to be about 0.05 wt% based on the correlation, and it was confirmed that the concentration of H ₂ O ₂ was as expected.

From the above results, it can be seen that by using the cleaning method of the present invention, the front and back surfaces (especially the back surface) of the silicon wafer can be sufficiently roughened to exhibit roughness suitable for adsorption by chucking. Furthermore, it can be seen that by using the hydrogen peroxide concentration evaluation method and management method in the cleaning solution of the present invention, it is possible to evaluate or even manage a trace amount of hydrogen peroxide concentration, which was difficult in the past.

(Comparative example) Prepare a silicon wafer with no natural oxide film on the bonding surface after DSP processing, and use SP3 to perform Haze evaluation. Next, using a batch type washing machine, washing was performed under six levels of conditions (liquid composition, washing temperature, and washing time) shown in Table 1. 28% by mass of ammonia water (NH ₄ OH) and 30% by mass of hydrogen peroxide water (H ₂ O ₂ ) were used to prepare the cleaning solution. Use SP3 to evaluate the wafer after cleaning, obtain the Haze value and calculate the Haze increase.

In all the levels in Table 1, the Haze increase amount was 1 ppm or less, which was smaller than 10 ppm and 30 ppm in Example 1, and it was judged that there was no roughening. After performing CMP processing with a processing allowance of 500nm for level 1 and level 5 wafers, when using SP5/19nmUP to evaluate the number of LLS, it is 10 pcs in level 1 and 342 pcs in level 5. It is considered that although the LLS degree of Level 1 is the same as that of Example 1, but Level 5 has an advantage in etching during the roughening and cleaning step, and the formed etch pits will remain in the CMP step, thereby deteriorating the quality of LLS. Next, the same chucking test as in Example 1 was carried out 200 times for wafers of level 1 and level 5. The defect that the wafer could not be separated from the chuck occurred 4 times in Level 1 and 3 times in Level 5 . In addition, the concentration of H ₂ O ₂ in the cleaning solution at level 5 was detected by an absorbance-based densitometer, but it was below the detection lower limit and could not be evaluated.

[Table 1] level NH ₄ OH [wt%] H ₂ O ₂ [wt%] Washing temperature[℃] Washing time [minutes] Haze increase [ppm] 1 2.1 2.8 45°C 3 minutes 0.03 2 2.1 2.8 60℃ 3 minutes 0.07 3 2.1 2.8 80°C 3 minutes 0.12 4 0.25 0.33 80°C 3 minutes 0.23 5 0.03 0.007 80°C 3 minutes 0.7 6 0.03 0.1 80°C 3 minutes -0.7

In addition, this invention is not limited to the said embodiment. The above-mentioned embodiments are examples, and those that have substantially the same configuration as the technical ideas described in the claims of the present invention and can exert the same effects are included in the technical scope of the present invention.

none

Fig. 1 is a flow chart showing an example of the method for cleaning a silicon wafer according to the present invention. Figure 2 is a graph showing the relationship between the amount of Haze increase, the number of LLS, and the state of the display surface after cleaning the silicon wafer on the bonding surface with various liquid compositions, and SEM images of level 5 and level 9. Fig. 3 is a graph showing the increase amount of Haze with respect to the H ₂ O ₂ concentration in three levels of NH ₄ OH concentration at a cleaning solution temperature of 80°C. Fig. 4 is a graph showing the increase of Haze with respect to the concentration of H ₂ O ₂ when the temperature of the cleaning solution is 45°C or 60°C. Fig. 5 is a graph showing the increase in Haze with respect to the cleaning time after cleaning at a cleaning temperature of 80°C using a cleaning solution with a concentration of NH ₄ OH of 0.03 wt % and a concentration of H ₂ O ₂ of 0.05 wt % . Fig. 6 is a flow chart showing an example of the method for evaluating and managing the concentration of hydrogen peroxide in the cleaning solution according to the present invention. Fig. 7 is a graph showing the increase of Haze with respect to the concentration of H ₂ O ₂ when the cleaning temperature is 80°C and the NH ₄ OH concentration is 0.03 wt%, and it shows the investigation of the concentration of the cleaning solution after implementing S11 in the example A graph of the results (relationships) of the steps. Fig. 8 is a graph showing the increase of Haze with respect to the concentration of H ₂ O ₂ when the cleaning temperature is 80°C and the concentration of NH ₄ OH is two levels, and it shows the investigation of the concentration of the cleaning solution S1 in the example. A graph of the results (relationships) of the steps.

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Claims (9)

A method for cleaning a silicon wafer, characterized in that the silicon wafer is roughened, and has the following steps: The cleaning solution concentration investigation step is to obtain in advance the amount of roughening of the front and back sides or the back surface of the roughened silicon wafer for investigation, the temperature of the cleaning solution, the concentration of ammonium hydroxide in the cleaning solution, and the cleaning solution The correlative relationship between the concentration of hydrogen peroxide in the above-mentioned roughened silicon wafer for investigation is obtained by roughening the silicon wafer for investigation with no natural oxide film but exposed bonding surface by cleaning with cleaning solution Or, the cleaning solution contains ammonium hydroxide and is an aqueous solution with a hydrogen peroxide concentration of 0-0.15% by weight; The roughening cleaning condition determination step is to determine the temperature of the cleaning solution, the concentration of the cleaning solution, Rough cleaning conditions of ammonium hydroxide concentration and hydrogen peroxide concentration; and, A roughening and cleaning step, which uses the roughening and cleaning conditions determined in the roughening and cleaning condition determination step to clean the silicon wafer to be roughened, which has no natural oxide film and exposes the bonding surface, to The roughening object performs roughening on the front and back sides or the back side of the silicon wafer. The method for cleaning a silicon wafer as described in Claim 1, wherein, in the step of investigating the concentration of the cleaning solution, a particle counter is used to obtain a Haze value before and after the cleaning of the silicon wafer for the investigation, and the value of the previously cleaned The increase amount of the Haze value after cleaning was made into the said roughening amount. The method for cleaning a silicon wafer according to claim 1, wherein, when the roughening and cleaning conditions are to be determined in the step of determining the roughening and cleaning conditions, the roughening and cleaning conditions are determined in the following manner: The hydrogen peroxide concentration is within a concentration range in which the variation in the amount of roughening relative to the variation in the concentration of hydrogen peroxide is not more than a specific value, and the silicon crystal to be roughened after the cleaning in the roughening cleaning step On the round surface, the natural oxide film formed in this cleaning remained. The method for cleaning a silicon wafer according to claim 2, wherein, when the roughening and cleaning conditions are to be determined in the step of determining the roughening and cleaning conditions, the roughening and cleaning conditions are determined in the following manner: The hydrogen peroxide concentration is within a concentration range in which the variation in the amount of roughening relative to the variation in the concentration of hydrogen peroxide is not more than a specific value, and the silicon crystal to be roughened after the cleaning in the roughening cleaning step On the round surface, the natural oxide film formed in this cleaning remained. The method for cleaning a silicon wafer according to any one of claims 1 to 4, wherein in the step of determining roughening and cleaning conditions, the temperature of the cleaning solution is set to 80° C. or higher. A method for manufacturing a silicon wafer, characterized in that a silicon wafer is obtained, the silicon wafer is cleaned by the method for cleaning a silicon wafer described in any one of Claims 1 to 5, and the front and back sides One side of the roughened silicon wafer is subjected to CMP processing, and only the side opposite to the aforementioned side is selectively roughened. A method for manufacturing a silicon wafer, characterized in that a silicon wafer is obtained, the silicon wafer is cleaned by the method for cleaning a silicon wafer described in any one of Claims 1 to 5, and a single Sheets are roughened by washing only the back side. A method for evaluating the concentration of hydrogen peroxide in a cleaning solution, characterized in that it has the following steps: The cleaning solution concentration investigation step is to obtain in advance the amount of roughening of the front and back sides or the back surface of the roughened silicon wafer for investigation, the temperature of the cleaning solution, the concentration of ammonium hydroxide in the cleaning solution, and the cleaning solution The correlative relationship between the concentration of hydrogen peroxide in the aforementioned roughened silicon wafer for investigation has a natural oxide film and is roughened by cleaning with the aforementioned cleaning solution containing hydrogen ammonium oxide and is an aqueous solution with a hydrogen peroxide concentration of 0 to 0.15% by weight; and, The hydrogen peroxide concentration evaluation step is based on the above-mentioned correlation obtained in advance in the cleaning solution concentration investigation step, based on the amount of roughening of the front and back sides or the back side of the roughened silicon wafer, and the temperature of the cleaning solution to be evaluated. , the concentration of ammonium hydroxide in the cleaning solution of the aforementioned evaluation object, the concentration of hydrogen peroxide in the cleaning solution of the aforementioned evaluation object is evaluated, and the roughened silicon wafer is a silicon wafer with a natural oxide film by Roughened by washing with the cleaning solution of the aforementioned evaluation object, the cleaning liquid of the evaluation object is an aqueous solution containing at least ammonium hydroxide A method for managing the concentration of hydrogen peroxide in the cleaning solution, characterized in that the concentration of hydrogen peroxide in the cleaning solution of the aforementioned evaluation object is evaluated by the method for evaluating the concentration of hydrogen peroxide in the cleaning solution described in Claim 8 , Based on the evaluation result, the concentration of hydrogen peroxide in the evaluated cleaning solution is adjusted.

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