JP2003063900A - Method for treating surface of single crystal semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating the surface of the single crystal semiconductor substrate, capable of uniformly and easily forming many minute protrusions having distributions and configurations which are different for the upper surface from the lower surface, in the technology for forming a random pyramid-like texture on the surface of the single crystal semiconductor substrate. SOLUTION: Dispersed and minute but a little larger protrusions 14b are formed on the upper surface 12b of the single crystal semiconductor substrate where bubbles stay in an etching solution, and delicately minute protrusions 14a are formed on the lower surface 12a of the single crystal semiconductor substrate which bubbles, ascending from the lower part of an etching bath, collide the lower surface 12a and move therealong. Thus, many random pyramid- like textures, having distributions and configurations which are different for the upper surface 12a from the lower surface 12b, can uniformly and easily be formed on the surface 12 of the single crystal semiconductor substrate 10.

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method for treating a surface of a single crystal semiconductor substrate in which a large number of fine projections are uniformly formed on the surface of the single crystal semiconductor substrate. 2. Description of the Related Art In order to increase the luminous efficiency of an LED or the conversion efficiency of a photovoltaic cell by lowering the reflectance of the surface of a single crystal semiconductor substrate, the surface of the single crystal semiconductor substrate is reduced. In some cases, a so-called random pyramid texture, which is a surface treatment structure in which a large number of pyramidal microprojections are uniformly formed, is provided. Such a surface treatment of the single crystal semiconductor substrate is also called a texture treatment, and by this texture treatment, the apex angle of the minute projection provided on the light emitting surface of the LED or the light receiving surface of the solar cell is 90 ° or less, for example, 70.5 °. Therefore, the reflectance of the LED light emitting surface or the solar cell light receiving surface is reduced,
And the conversion efficiency of the solar cell is improved. In addition, the minute projections provided on the lower surface of the single crystal semiconductor substrate improve the characteristics of the LED or solar cell by realizing the formation of a point contact surface when forming the lower surface electrode. According to the prior art, the above-mentioned conventional random pyramid texture is obtained by adding a single crystal semiconductor substrate to, for example, a 0.5 wt% solution of sodium hydroxide in a boiling state.
It is formed by immersion for about a minute. However, the microprojections obtained by such a method are usually about 10 μm in height, and it is not possible to obtain a resist smaller than about several μm in thickness of a resist applied by a spinner or the like in a photolithography process. Was. In the case where an electrode pattern is formed by screen printing on the surface of the conventional single crystal semiconductor substrate on which such fine projections having a height of about 10 μm are formed, there is no problem. Alternatively, when a thin and fine electrode pattern is to be formed by using a sputtering method or the like, the electrode material is entirely fixed on a resist from which a predetermined electrode pattern has been removed by sputtering or the like, and then the resist is removed. Then, since the thickness of the resist used for photolithography is relatively thin, about several μm, there has been an inconvenience that the electrode material locally remains on the tops of the fine projections in a region other than the predetermined electrode pattern. Further, in the above-described conventional texture processing, a plurality of minute projections formed on the surface of the semiconductor substrate may be formed unevenly. For example, if the minute projections are formed unevenly on the lower surface of the single crystal semiconductor substrate, Since the area ratio and the distribution of the contact region become unstable, there is a disadvantage that the characteristics of the LED or the solar cell may vary. In order to solve the above-mentioned disadvantages of the prior art, the present applicant previously modified the surface of a single-crystal semiconductor substrate to a hydrophobic surface, and applied the modified surface of the single-crystal semiconductor substrate to the hydrophobic surface. We have applied for a texture processing technology that performs anisotropic etching after attaching organic molecules. Japanese Patent Application 2000-14
This is the surface treatment method for a single crystal semiconductor substrate described in the '864 Application. According to this technique, the surface of the single crystal semiconductor substrate is modified into a hydrophobic surface, and anisotropic etching is performed after the organic molecules are suitably attached. The quadrangular pyramid-shaped microprojections are uniformly formed, and a thin and fine electrode pattern can be formed, and a surface treatment of a single crystal semiconductor substrate that gives a desired area ratio and distribution to a contact region can be performed. Incidentally, the random pyramid texture formed on the surface of the single crystal semiconductor substrate preferably has different distributions and properties on the upper surface and the lower surface of the single crystal semiconductor substrate. By providing minute protrusions and providing sparse and coarse minute protrusions on the lower surface, the reflectance of the LED light emitting surface or the solar cell light receiving surface is reduced by the fine protrusions provided on the upper surface, ie, the LED light emitting surface or the solar cell light receiving surface. Thereby, the luminous efficiency of the LED or the conversion efficiency of the solar cell is improved, and the minute projections provided on the lower surface realize the formation of a point contact surface when forming the electrode, thereby improving the characteristics of the LED or the solar cell. However, the surface treatment method for a single crystal semiconductor substrate described in the prior application of the present applicant eliminates the disadvantages of the prior art, while, for example, a single crystal semiconductor substrate. In order to form two or more types of microprojections having different distributions and properties on the surface of a semiconductor substrate, there remain problems that a plurality of etching baths are required and that the process becomes complicated. In addition, in order to form a random pyramid texture having different distribution and properties on the upper surface and the lower surface according to the conventional technology, it is necessary to protect one surface and etch the other surface, and a strong alkaline aqueous solution is used for the texture treatment at a high temperature. Therefore, it is not possible to use a usual method such as forming a photoresist or covering one side by applying a tape or the like, and the only option is to protect with an oxide film or a nitride film. In this case, it is necessary to add a step of subjecting the single crystal semiconductor substrate to high temperature or vacuum, which causes an increase in cost and a problem that the single crystal semiconductor substrate itself is deteriorated. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for forming a random pyramid texture on the surface of a single crystal semiconductor substrate, in which the distribution is distributed between upper and lower surfaces. Another object of the present invention is to provide a surface treatment method for a single crystal semiconductor substrate, which can uniformly and easily form a large number of microprojections having different properties. Means for Solving the Problems To achieve the above object, the gist of the present invention is to perform a surface treatment for forming a large number of uniform fine projections on the surface of a single crystal semiconductor substrate. A surface treatment method for a single crystal semiconductor substrate, wherein the surface of the single crystal semiconductor substrate is 60 to 9 with respect to a vertical direction.
The surface treatment is performed by immersing the substrate in an etching solution so as to form an angle of 0 °, and setting the temperature of the etching solution to a temperature at which bubbles are continuously generated in the etching solution. Here, the angle formed by the plane and the straight line generally means the minimum angle among a plurality of angles stretched between the plane and the straight line. Therefore, the angle formed by the surface of the single crystal semiconductor substrate and the vertical direction is defined by the surface and the vertical direction. Is the minimum angle among the plurality of angles spanned by
It is. According to the present invention, a sparse and large texture is formed on the upper surface of the single crystal semiconductor substrate on which bubbles stay in the etching solution, and bubbles rising from the lower portion of the etching bath collide. A small and fine texture is formed on the lower surface of the single crystal semiconductor substrate flowing along the plane. That is, according to the present invention, when forming a random pyramid texture on the surface of a single crystal semiconductor substrate, a single crystal can be formed uniformly and easily with a large number of fine projections having different distributions and properties on the upper surface and the lower surface. A surface treatment method for a semiconductor substrate can be provided. An embodiment of the present invention will be described below in detail with reference to the drawings. In the following examples, dimensional ratios and the like in each drawing are not necessarily drawn accurately. FIG. 1 shows a single crystal semiconductor substrate 10 made of a group IV element or a group III-V element such as silicon, germanium, gallium-arsenic, etc. It is a process drawing explaining the process of forming the random pyramid texture which is the surface treatment structure which consists of the quadrangular pyramid-shaped minute projections 14 formed.
As shown in the plan view of FIG. 2 and the perspective view of FIG. 3, only one microprojection 14 protrudes from, for example, the (100) plane of single crystal semiconductor substrate 10 and has a height H of 1 μm to several μm. And a bottom side L, and the four inclined surfaces are (111) surfaces. The apex angle of the quadrangular pyramid-shaped minute projection 14 is, for example, 70.5 °. The single crystal semiconductor substrate 10 is used, for example, as a substrate for a solar cell, an LED, or the like. The step shown in FIG. 1 is incorporated before the step of forming an insulating protective film made of, for example, SiO ₂ or the step of forming an electrode in the steps of manufacturing a solar cell or an LED. FIG. 4 is a view showing a state in which a plurality of single crystal semiconductor substrates 10 are set on a carrier 16 which is an example of an instrument used for surface treatment of the single crystal semiconductor substrate 10 of the present invention. FIG. 3B is a plan view, and FIG. According to the present invention, the single crystal semiconductor substrate is immersed in an etching solution so that the surface thereof has an angle of 60 to 90 °, for example, a value at which a certain effect can be obtained with respect to the vertical direction. As shown, in this embodiment, the surface treatment was performed on the single crystal semiconductor substrate 10 with the angle being 90 ° which is the maximum value, that is, horizontal. When the angle between the single crystal semiconductor substrate 10 and the vertical direction is smaller than 60 °, no air bubbles remain on the upper surface 12b of the single crystal semiconductor substrate 10, and the upper surface 12b and the lower surface 12b do not remain.
Since the etching conditions a are similar, significant differences in distribution and properties between the upper surface and the lower surface of the formed microprojections 14 are unlikely to occur. Hereinafter, the surface treatment step of the single-crystal semiconductor substrate 10 of the present embodiment shown in FIG. 1 will be described in detail. Unless otherwise specified, for example, as shown in FIG. It is assumed that a series of surface treatments are performed on a plurality of single crystal semiconductor substrates 10. First, in a dehydration step P1 of FIG. 1, a single crystal semiconductor substrate
Dehydration baking is performed for about 10 minutes at a temperature of about 0 ° C., and water is removed from the surface 12. The single crystal semiconductor substrate 10 that has been subjected to the dehydration treatment in the dehydration step P1 is subjected to a subsequent organic molecule attachment step P
2, is immersed in a liquid such as HMDS (hexamethyldisilazane), that is, an organic molecule solution or an organic liquid having a relatively high reactivity with the single crystal semiconductor substrate 10 for about 1 minute, whereby the organic molecules are converted into the single crystal semiconductor. Attached to surface 12 of substrate 10. In the organic molecule attaching step P2, the surface 12 of the single crystal semiconductor substrate 10
By adhering the organic molecules to the substrate, the base point of the minute protrusion 14 is uniformly provided prior to the anisotropic etching step P4 described later. The single crystal semiconductor substrate 10 having the organic molecules adhered to the surface 12 in the organic molecule attaching step P2 is pulled out of the organic molecule solution or the organic liquid, air-dried for about 3 minutes, and then dried for the first time. in the drying step P3 is fully dried by such as N ₂ blowing, it removed the residual liquid fraction. This is to prevent anisotropic etching unevenness from occurring in the anisotropic etching step P4 described later. In the subsequent anisotropic etching step P4, the single crystal semiconductor substrate 10 dried in the first drying step P3 is subjected to anisotropic etching using an apparatus as schematically shown in FIG. (Texture processing) is performed. First, while a base 20 and a heater 22 are installed in, for example, a square beaker 18, an alcohol such as IPA (isopropanol) is added to a strong alkaline solution such as KOH or K ₂ CO _{3 at a} predetermined ratio. Is mixed, and the heater 22 is heated to, for example, 70 to 75 ° C. Subsequently, the single crystal semiconductor substrate 10 is immersed in the etching solution heated to such a temperature. Here, several tens of seconds after the single crystal semiconductor substrate 10 is put in the etching solution, it is checked whether or not bubbles are generated on the surface 12 of the single crystal semiconductor substrate 10. It is necessary to adjust to keep the reaction rate constant. Further, the single crystal semiconductor substrate 1
If the number of bubbles is so large that observation of the surface is impossible, IPA is added little by little to the etching solution until the surface can be observed. One to two minutes after the start of the anisotropic etching, black spots start to appear on the surface 12 of the single crystal semiconductor substrate 10, and after ten minutes, the single crystal semiconductor substrate 1
0, which was not visible on the surface 12 of the surface 12, and became approximately 20 minutes after the start of etching.
Turns black overall. The time when the surface 12 becomes uniformly black is a measure of the end of the anisotropic etching, and the single crystal semiconductor substrate 1 is 5 to 10 minutes after the surface 12 becomes uniformly black.
0 is pulled up from the etching solution. Through the anisotropic etching step P4, the single crystal semiconductor substrate 10
Are formed on the surface 12 of the surface of the substrate 12 in the form of a quadrangular pyramid having a nucleus or an apex as an adhesion site of the organic molecule attached in the organic molecule attachment step P2. In the anisotropic etching step P4, the single crystal semiconductor substrate 10 is immersed in an etching solution so that its surface 12 is perpendicular to the vertical direction, that is, horizontal. Since the temperature of the liquid is a temperature at which bubbles are continuously generated in the etching solution, the generated bubbles stay on the upper surface 12b of the single crystal semiconductor substrate 10 shown in FIG. 12a
In this case, bubbles rising from the bottom of the etching bath collide and flow along the plane. As described above, since the upper surface 12b and the lower surface 12a of the single crystal semiconductor substrate 10 have different states in which anisotropic etching is performed, a large number of microprojections 14 having different distributions and properties on the upper surface and the lower surface are formed. It is thought to be formed. As a result, the surface 1 on the upper side of the single crystal semiconductor substrate where bubbles stay in the etching solution
2b are formed with sparse and large microprojections 14b,
Small and fine microprojections 14a are formed on the lower surface 12a of the single crystal semiconductor substrate in which bubbles generated in the etching solution and rising from the bottom collide and flow along the surface. In the anisotropic etching step P4,
The single crystal semiconductor substrate 10 having the surface 12 on which a number of microprojections 14a and 14b are formed is immersed in, for example, HCl having a hydrogen ion concentration of 20% for about one minute in the subsequent neutralization step P5, so that the surface thereof is The strong alkaline solution, which is the etchant remaining in 12, is removed by a neutralization reaction. The single crystal semiconductor substrate 10 from which the strong alkaline solution on the surface 12 has been removed in the neutralization step P5 is first subjected to a primary rinsing for about 30 seconds in a subsequent cleaning step P6. This primary rinsing causes the HCl on the surface 12
And the like, and then subjected to a secondary rinse for about 5 minutes with cold running water, so that the single crystal semiconductor substrate 10
Is cleaned. The single crystal semiconductor substrate 10 cleaned in the above-mentioned cleaning step P6 is subjected to a subsequent second drying step P7.
After water on the surface 12 is removed by, for example, N ₂ blow, dehydration baking is performed for about 10 minutes at a temperature of about 150 ° C. by, for example, an oven. As described above, through the steps P1 to P7 shown in FIG. 1, a large number of microprojections 14a and 14b having different distributions and properties on the upper surface and the lower surface are uniformly formed on the surface 12 of the single crystal semiconductor substrate 10. FIG. 6 shows a large number of fine particles having different distributions and properties on the upper surface (lower surface in the surface treatment step) 12a and the lower surface (upper surface in the surface treatment step) 12b through the process of FIG. It is a perspective view showing solar cell 30 using single crystal semiconductor substrate 10 in which a projection was formed uniformly. The single crystal semiconductor substrate 10 of this solar cell 30 contains, for example, boron as an impurity at 1 × 10 ¹⁶ c.
A p-type layer 32 made to be p-type by being diffused at a concentration of about m ⁻³ , an n-type layer 34 made to be n-type by diffusing phosphorus as an impurity, and a surface oxidation of single crystal semiconductor substrate 10. An anti-reflection film 36 made of SiO ₂ or the like is sequentially provided from the lower side to the upper side. The upper surface 12a of the n-layer 34 is a light-receiving surface,
It functions as an emitter layer to which light enters. This n
The layer 34 has, for example, an impurity concentration of 1 × 10 ^{17 to} 5 × 10 ¹⁹ cm ⁻³ and a thickness of 0.5 to 10 μm.
On the upper surface 12a, a portion of the antireflection film 36 corresponding to the pattern of the upper electrode 38 is removed by etching using a photolithography method or the like, and the upper electrode 38 is fixed to the removed portion by sputtering or the like. Have been. Here, a preferable shape of the minute protrusion 14a formed on the upper surface 12a of the single crystal semiconductor substrate 10 is as follows.
When the height shown in FIG. 3 is H ≦ 2 (μm), and H is larger than 2 μm, when an electrode pattern is to be formed on the upper surface 12a of the single crystal semiconductor substrate 10 by, for example, sputtering or the like, predetermined height is determined by photolithography. After the electrode material is completely fixed on the resist from which the electrode pattern has been removed by sputtering or the like and then the resist is removed, the thickness of the resist used for photolithography is relatively thin, about several μm. In such a region, an inconvenience such as that the electrode material locally remains on the tops of the minute projections 14a occurs. On the lower surface 12b, a lower electrode 40 is formed through a process as shown in FIG. First, the single crystal semiconductor substrate 10 is heated and H
The surface of a substrate material such as silicon constituting the single crystal semiconductor substrate 10 is oxidized by bringing ₂ O or O ₂ into contact, and an insulating protective film 42 which is a high-temperature oxide layer is formed. FIG. 7A shows this state. Next, the resist 44 is made to have a thickness of 3 to 4 μm by a method such as spin coating.
It is applied over the lower surface 12b with a thickness of about m. At this time, the relatively large minute projections 1 formed on the lower surface 12b
4b has a height of about 7 to 8 μm and is exposed through the resist 44 in the thickness direction. FIG. 7B shows this state. Subsequently, the lower surface 12b is brought into contact with the etching solution by, for example, immersion in the etching solution, and the portion that penetrates through the resist 44 in the thickness direction and is exposed, that is, the protruding end portion of the minute projection 14b is removed, and the insulating protection of the top portion is performed. The film 42 is locally removed. FIG. 7C
Shows this state after the resist 44 is removed. Subsequently, the lower electrode 40 is fixed to the lower surface 12b by, for example, sputtering. In this state, the lower electrode 4 is passed through a locally removed portion of the insulating protective film 42, that is, through the conduction window 46.
0 and the p layer 32 in the single crystal semiconductor substrate 10 are electrically connected. Therefore, in the present embodiment, when the lower electrode 40 is formed by the above process, the lower electrode 4 can be formed without removing a part of the insulating protection film 42 by etching or the like.
Since the 0 and the p-layer 32 are conducted, a patterning process such as photolithography can be omitted, and the process can be simplified. In addition, since the lower electrode 40 and the p-layer 32 are in contact with each other in a very small area, and most of the p-layer 32 is covered with the insulating protective film 42, recombination loss at the interface between the metal and semiconductor can be reduced efficiently. Since the electrode 40 functions as a mirror, incident light of a long wavelength that could not be absorbed due to the thickness of the p-layer 32 is efficiently re-absorbed. [Experimental Example] Hereinafter, an experimental example performed by the present inventors to verify the effect of the present invention will be described.
The present inventors prepared a plurality of p-type single-crystal silicon wafers having a wafer resistivity of 0.1 to 10 (Ωcm) as a single-crystal semiconductor substrate. First, a mixed solution of KOH and IPA was used as an etching solution. 1 and the concentration of KOH (wt%) and the concentration of IPA (wt
%), The temperature of the etching solution (° C.), and the etching time (minutes) are variously changed, and the surface treatment is performed on the single crystal silicon wafer.
It was created. 8 to 11 show the results. The shape of the microprojections formed in this experiment was a pyramid shape, and the height H was almost equal to the length L of one side of the bottom. In the results shown in FIGS. 8 to 11, sparse and large microprojections 14b are formed on the upper surface 12b,
A wafer having small fine protrusions 14a formed on the lower surface 12a is indicated by a circle, and the fine protrusions 1 on the upper and lower surfaces are indicated by a circle.
4 is uniform and no difference is generated is indicated by a triangle. In the experimental results, which are indicated by "x" in the experiment results, "texture coarsening" indicates that the height H of the fine projections is larger than 2 μm. Next, a mixed solution of K ₂ CO ₃ and IPA is used as an etching solution, and K ₂ C
O ₃ concentration (wt%), IPA concentration (wt%),
The surface of the single crystal silicon wafer was subjected to various changes in the temperature (° C.) of the etching solution and the etching time (minutes) to prepare Example Samples B (Sample Nos. 1 to 64). 12 to 14 show the results. Since the meanings of △, Δ, and × are the same as those of the sample A of the example, the description is omitted. According to the experimental results shown in FIGS. 8 to 14, in Examples A and B, regardless of the resistivity of the single-crystal silicon wafer, it depends solely on the structure of the etching solution and the temperature of the etching solution. It can be seen that the surface treatment structure formed on the surface of the single crystal silicon wafer has changed. As described above, the surface treatment structure formed on the wafer is related to the composition of the etching solution and the processing temperature because the present invention uses the temperature of the etching solution as the temperature at which bubbles are continuously generated in the etching solution. It is considered that this is because the surface treatment is performed, and the etching is performed on the single crystal semiconductor substrate in a state where the temperature of the etching solution is kept at least 5 ° C. lower than the temperature at which the mixture boils and boils. It is presumed that the application is preferable. As described above, according to the present embodiment, sparse and large microprojections 14b are formed on the upper surface 12b of the single crystal semiconductor substrate on which bubbles stay in the etching solution and rise from the bottom of the etching bath. When small random fine protrusions 14a are formed on the lower surface 12a of the single crystal semiconductor substrate where the air bubbles collide and flow along the plane, when forming a random pyramid texture on the surface 12 of the single crystal semiconductor substrate 10, A large number of random pyramid textures having different distributions and properties on the upper surface 12a and the lower surface 12b can be uniformly and easily formed. In the solar cell 30 using the single-crystal semiconductor substrate 10 subjected to the surface treatment according to the present embodiment, small and fine minute projections 14a are formed on the upper surface 12a. In this case, the electrode material does not remain locally on the tops of the minute projections 14a. Further, since the sparse and large fine protrusions 14b are formed on the lower surface 12b, the lower electrode 40 and the p layer 32 are in contact with each other in a very small area, and most of the p layer 32 is formed of the insulating protective film 42.
, The recombination loss at the metal-semiconductor interface can be efficiently reduced, and the lower electrode 40 acts as a mirror, so that the long wavelength incident light that could not be absorbed by the thickness of the p-layer 32 can be efficiently absorbed. Reabsorbed. Although the embodiment of the present invention has been described in detail with reference to the drawings, the present invention is not limited to this, and may be applied to other embodiments. For example, in the above embodiment, a strong alkaline solution, ie, KOH or K ₂ C
Although a mixed solution of O ₃ and an alcohol, ie, IPA, was used, the present invention is not limited to this, and an etching solution suitable for a type of a single crystal semiconductor substrate to be subjected to a surface treatment is provided. Is appropriately selected and used. In the above-described embodiment, the single-crystal semiconductor substrate 10 is immersed in the etching solution so that the surface 12 is perpendicular to the vertical direction. The minimum value of the range in which the effect of the present invention can be obtained, for example, 6 in accordance with the shape of the anisotropic etching apparatus, the number of single crystal semiconductor substrates, etc.
A suitable angle is appropriately selected from an angle range of 0 to 90 °. In the experimental example described above, a single crystal silicon wafer was subjected to surface treatment as a single crystal semiconductor substrate. However, the present invention is applied to a surface treatment of a single crystal semiconductor substrate such as germanium or gallium-arsenic. It is widely used and is not limited to surface treatment of a single crystal silicon wafer. Although not specifically exemplified, the present invention can be implemented with various modifications without departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram illustrating an example of a surface treatment process for forming a plurality of minute projections on a surface of a single crystal semiconductor substrate. FIG. 2 is a plan view illustrating a pyramid shape of a minute projection formed by the process of FIG. FIG. 3 is a perspective view illustrating a pyramid shape of a minute projection formed by the process of FIG. 1; FIG. 4 is a view showing a state in which a plurality of single crystal semiconductor substrates are set on a carrier which is an example of a tool used for surface treatment of a single crystal semiconductor substrate of the present invention. FIG. 5 is a schematic view showing a state of a surface treatment of a single crystal semiconductor substrate of the present invention. 6 is a perspective view showing a solar cell using a single-crystal semiconductor substrate on which a large number of fine projections having different distributions and properties on the upper surface and the lower surface are uniformly formed through the process of FIG. 7 is a diagram illustrating a state in which an electrode is formed on the upper surface of a single crystal semiconductor substrate on which sparse and large microprojections are formed through the process of FIG. 1; FIG. 8 is a table showing evaluation results of Example Sample A (Sample Nos. 1 to 22), which are the results of experiments conducted by the present inventors. FIG. 9 is a table showing evaluation results of Example Sample A (Sample Nos. 23 to 44), which are the results of experiments conducted by the present inventors. FIG. 10 is a table showing evaluation results of Example Sample A (Sample Nos. 45 to 66), which are the results of experiments conducted by the present inventors. FIG. 11 is a table showing evaluation results of Example Sample A (Sample Nos. 67 to 88), which are the results of experiments conducted by the present inventors. FIG. 12 is a table showing evaluation results of Example Samples B (Sample Nos. 1 to 22), which are the results of experiments conducted by the present inventors. FIG. 13 is a table showing evaluation results of Example Sample B (Sample Nos. 23 to 44), which are the results of experiments conducted by the present inventors. FIG. 14 is a table showing evaluation results of Example Sample B (Sample Nos. 45 to 64), which are the results of experiments conducted by the present inventors. [Description of Symbols] 10: Single crystal semiconductor substrate 12: Surface 12a: Upper surface of single crystal semiconductor substrate (lower surface in surface treatment step) 12b: Lower surface of single crystal semiconductor substrate (upper surface in surface treatment step) 14: Fine Projection 14a: Microprojection formed on upper surface of single crystal semiconductor substrate 14b: Microprojection formed on lower surface of single crystal semiconductor substrate

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Masashi Yamaguchi             3-18-17-204, Sugamo, Toshima-ku, Tokyo F term (reference) 4G077 AA02 AA03 BA04 BA05 BE41                       BE46 FG05 FG06 HA02                 5F041 AA03 CA34 CA74 CA99                 5F043 AA02 AA03 BB02 BB27 DD30                       EE35 FF10 GG10                 5F051 AA02 AA07 CB21 GA14

Claims (1)

Claims: 1. A method for treating a surface of a single-crystal semiconductor substrate, the method comprising performing a surface treatment for forming a large number of uniform fine protrusions on the surface of the single-crystal semiconductor substrate. The surface is 6
A single crystal semiconductor characterized by being immersed in an etching solution so as to form an angle of 0 to 90 °, and performing the surface treatment at a temperature of the etching solution at a temperature at which bubbles are continuously generated in the etching solution. Substrate surface treatment method.