JP3526284B2 - Substrate surface treatment method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, in constructing an element structure on a substrate for semiconductor element formation, etc. without damaging a necessary thermal oxide film formed on the substrate or the element structure. The present invention relates to a substrate surface treatment method capable of selectively removing a natural oxide film formed on a substrate.

[0002]

2. Description of the Related Art A fine electric circuit having source, drain and gate elements is represented by a MOS (metal oxide film-silicon) type semiconductor device using high-purity single crystal silicon as a substrate. SiO for the gate insulating material
_Two membranes may be used. In recent years, the thickness of this gate oxide film has been reduced, but what is particularly important in the process of forming this thin film is a uniform and uniform high-quality substance (Si
O ₂ ) is to form the gate oxide film. This is one of the important factors that particularly affect the product yield when manufacturing fine devices.

Further, in addition to the above, in order to form a thinner and higher quality gate oxide film in accordance with the recent tendency of thinning the gate oxide film, the surface of the silicon substrate before forming the gate oxide film is advanced. Cleanliness becomes more important. To this end, impurities such as metal and organic substances that adhere to the surface of the substrate as the main components, various fine particles floating in the manufacturing environment, and even a device such as a natural oxide film formed on the silicon surface are used. It is necessary to provide a substrate in a very clean state in which various unnecessary obstructive factors are completely removed from the surface.

Conventionally, in order to realize a clean substrate surface, a cleaning treatment which also serves as a surface treatment is always performed before forming the gate oxide film. This is generally called pre-furnace cleaning. Then, a wet treatment with dilute hydrofluoric acid is usually used for removing the natural oxide film, which is one step of the pre-furnace cleaning. Furthermore, a dry process in which pre-furnace cleaning is performed in a gas phase is also known, and, for example, in JP-A-9-102490, a process with a gas containing steam or alcohol and a process with anhydrous hydrogen fluoride gas are repeated. Accordingly, a method of removing the natural oxide film is disclosed. The present inventors have already proposed a method of selectively removing a natural oxide film by using an inert gas heated to room temperature or higher and anhydrous hydrogen fluoride gas (see Japanese Patent Application No. 2000-135881).

[0005]

However, in the wet treatment which has been widely practiced in the past, a large amount of concentrated and high-temperature chemical liquid is used to remove impurities on the outermost surface of the substrate. Therefore, the waste liquid treatment after the treatment is performed. I have a problem. Further, there is a limit to the cleanliness of the chemical liquid itself used in the wet treatment, and there is a possibility that cross contamination may occur due to this. Furthermore, in terms of processing performance, there is also a problem in wet processing that it is difficult to perform the intended processing with good reproducibility due to the difference between the set value and the true value with respect to the chemical concentration, the processing time, and the like.

On the other hand, the above-mentioned Japanese Patent Laid-Open No. 9-102, in which an etching treatment is carried out in a gas phase using a gas etching medium.
According to the method described in Japanese Patent No. 490, unlike the case of the wet treatment, it is possible to perform the intended treatment with good reproducibility without worrying about cross contamination due to the chemical solution. However, the vapor-phase etching treatment method does not significantly impair the required thermal oxide film.
The etching of the thermal oxide film of about 3 nm (20 to 30 Å) is inevitable. Therefore, when the process is pre-furnace cleaning of the substrate in the formation of an ultra-thin gate, the etching amount of the oxide film by the vapor phase etching process may exceed the allowable range of the required thermal oxide film. , Not applicable. In addition, deterioration of electrical characteristics is inevitable due to occurrence of microroughness (fine irregularities) on the surface of the oxide film due to vapor-phase etching of the oxide film.

On the other hand, the method of the above-mentioned Japanese Patent Application No. 2000-135881, which has been already proposed by the present inventors, selectively suppresses the etching of the required thermal oxide film and selectively removes the natural oxide film. This is a very effective method in that it can etch the substrate, and can be applied to cases such as pre-furnace cleaning of a substrate in forming an ultrathin gate. However,
According to the study by the present inventors, the occurrence of microroughness on the oxide film surface cannot be avoided even by such a method.
It was found to be difficult to apply in applications such as natural oxide film removal before gate formation.

Therefore, the object of the present invention is to prevent the required thermal oxide film formed on the substrate from being damaged beyond the allowable range, and without causing microroughness on the film surface after the treatment. Another object of the present invention is to provide a method for treating a substrate surface, which removes a natural oxide film formed on a silicon substrate selectively and uniformly to provide an extremely clean substrate surface. An object of the present invention is to provide a method for treating a substrate surface, which is particularly useful in manufacturing a semiconductor device in which a thinner and higher quality gate oxide film needs to be formed.

[0009]

The above objects can be achieved by the present invention described below. That is, according to the present invention, the necessary thermal oxide film and natural oxide film are mixed on the same substrate.
A method for treating a surface of a silicon substrate, comprising at least the following steps (1) to (8), and sequentially performing these steps. (1) Step of supplying vapor to the substrate surface before the first etching step (2) Using HF vapor , the thermal oxide film is etched
First etching step of etching the surface portion of the natural oxide film under the condition that the natural oxide film having a high oxygen concentration is etched (3) Step of supplying vapor to the substrate surface after the first etching step (4) Inert gas (5) Supplying vapor to the substrate surface before the second etching step (6) Purging the inside of the chamber and the substrate surface by (6) HF vapor at the interface portion of the native oxide film with the substrate
The thermal oxide film is not etched and the SiO ₂ / Si interface is used.
Second etching step for etching under the condition that a portion is etched (7) Step for supplying vapor to the substrate surface after the second etching step (8) Step for rinsing with deionized water and spin drying

As a result of diligent studies on the above-mentioned problems of the prior art, the present inventors have found that a substrate surface on which the required thermal oxide film and a natural oxide film are mixed is formed on the same substrate. In order to effectively suppress the generation of micro-roughness on the surface of the thermal oxide film that can be seen in the case of vapor phase cleaning, it is effective to perform the treatment according to the following procedure. The inventors have found the present invention and have reached the present invention.

That is, first, the condition that the etching selectivity between the surface portion of the natural oxide film having a high oxygen concentration and the thermal oxide film is the best (that is, the condition that the thermal oxide film is not etched but the natural oxide film is etched). Is etched (first etching step) to remove only the surface portion of the natural oxide film.
Subsequently, the reaction is converged by supplying vapor, and the surface of the substrate is purged with an inert gas to remove the influence of the first etching, and then the second etching step is performed. The second etching step is performed with SiO _{2 having} a low oxygen concentration.
/ Si interface and the thermal oxide film have the best etching selectivity (that is, the thermal oxide film is not etched and
SiO ₂ under the condition that the ₂ / Si interface is etched)
Etching is applied to the / Si interface portion. As a result of these treatments, the native oxide film on silicon can be selectively removed without damaging the required thermal oxide film beyond the allowable range.

Further, if an inert gas, preferably an inert gas containing a large amount of water vapor, is supplied for a sufficient time after the second etching treatment and before the rinsing treatment with deionized water, the second etching treatment activates. The substrate surface in a stable state can be quickly brought to a stable state, and as a result,
It is possible to suppress the etching of the thermal oxide film that occurs in the rinse treatment step, and effectively suppress the occurrence of microroughness on the surface of the thermal oxide film that is caused by etching.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to preferred embodiments. Hereinafter, an example of an apparatus that can implement the method of the present invention will be described with reference to the drawings. A flow chart of the apparatus is shown in FIG. 1 in FIG. 1 is an etching chamber for performing an etching process, and 2 on the lower side thereof is a rinse chamber for performing a rinse and spin drying process. Reference numeral 3 is a reaction gas line (for example, anhydrous hydrogen fluoride gas) introduced into the etching chamber, and 4 is an exhaust line. The line 5 is a line for supplying an inert gas (for example, nitrogen gas) from the back surface side for preventing the reaction gas from flowing around the back surface of the substrate during etching. The amount of the inert gas from the supply line 5 to the back surface side is determined by the mass flow controller (hereinafter referred to as M
FC hereinafter) is adjusted at 8 _1.

As shown in FIG. 1, the flow rate of the anhydrous hydrogen fluoride gas which is a reaction gas is adjusted by the MFC 7 from the liquid anhydrous hydrogen fluoride bottle 6 made of nickel as a gas through a pipe. And this anhydrous hydrogen fluoride gas is
It is introduced into the etching chamber 1 together with the nitrogen gas whose flow rate is adjusted by the MFC shown by 8 in FIG. In addition, deionized water is stored up to about half the tank capacity in a tank 9 called a vapor tank, and water vapor is etched by flowing nitrogen gas whose flow rate is adjusted by MFC8 ₂ as a carrier gas on the water surface. It is introduced into the chamber 1. This vapor tank 9 is always
The temperature is controlled to 25 ° C. Further, in order to adjust the exhaust pressure in the chamber 1 to a constant value, as shown in FIG.
The back pressure controller 10 is attached. Line 1 connected to rinse chamber 2
1 is a supply line of deionized water at the time of rinsing. Line 12 is a drain line for deionized water after rinsing.

2 to 4 schematically show the structure of the processing chamber portion constituted by the etching chamber 1 and the rinsing chamber 2 in the above flow chart. Figure 2
It is a schematic cross section which shows the state of the etching chamber 1 at the time of installing or removing a board | substrate in a process chamber. Reference numeral 21 in FIG. 2 is a turntable for setting and rotating the substrate 20, and 24 under the turntable is a motor therefor. Then, the substrate 20 can be fixed by a vacuum chuck at the center of the turntable 21 and rotated up to 3,000 rpm. 22
Is a thin film (diffuser membrane) made of PTFE for uniformly supplying the gas entering the etching chamber 1 from the supply port 3 onto the substrate 20. Also, 2
A membrane of high-molecular polyethylene (exhaust membrane) is also attached to 3 so that the gas can be uniformly exhausted from the exhaust port 4.

FIG. 3 is a schematic cross-sectional view showing the state of the etching chamber 1 when performing the etching process in the above-mentioned processing chamber. As shown in FIG. 3, the gas is uniformly introduced through the diffuser membrane 22 described above and exhausted by the exhaust membrane 23, so that the gas is uniformly supplied onto the substrate 20. There is. Further, FIG. 4 is a schematic cross-sectional view showing a state of the rinse chamber 2 when performing rinsing and spin drying in the rinse chamber 2 below the etching chamber 1. As shown in FIG. 4, in this case, the substrate 2 is moved from the etching position described in FIG.
0 itself, and the turntable 21 and the like holding it, do not move, and the etching chamber 1 and the rinsing chamber 2 move upward. Then, in this state, deionized water is sprayed from the supply line 11 at the time of rinsing shown in FIG. 1 through the rinse nozzle 25 to the vicinity of the center of the substrate 20, preferably at 450 ml / min. The deionized water after rinsing is drained from the drain 13 at the bottom, as shown in FIGS. 1 and 4.

In the method for treating a substrate surface of the present invention, the above-mentioned apparatus is used to sequentially perform the following steps (1) to (8). Each of the steps (1) to (8) will be described below. Step (1) In step (1), an inert gas (vapor) containing water vapor or alcohol is supplied to the substrate surface. The purpose of the step (1) is to uniformly deposit water vapor or alcohol having a catalytic action for etching, which will be described later, on the surface portion of the substrate using an inert gas as a carrier. That is, water or the like, which serves as a reaction catalyst for etching, is uniformly and evenly adhered to the substrate surface before the next first etching step, so that non-uniform etching or microroughness is generated on the surface in the next step (2). It is possible to prevent it from occurring. The amount of vapor supplied in this step is preferably 150 to 200 L, and the inert gas used is usually
Nitrogen gas is used. As the reaction catalyst for the etching used in the step (1), it is preferable to use water vapor, but isopropyl alcohol (IP
It is also possible to use alcohols such as A).

Step (2) This step is the first etching step performed after the vapor supply performed in step (1), and is intended to etch the surface portion of the natural oxide film formed on the substrate. . In the first etching step, an anhydrous hydrogen fluoride gas and a reaction gas (HF vapor) added with water vapor or alcohol are used with an inert gas as a carrier. In this step, it is preferable to perform the treatment for 20 to 30 seconds using anhydrous hydrogen fluoride gas of 5 to 8 [× 10 ^-2 vol%] at this time.

Step (3) Step (3) is a step of supplying vapor to the surface of the substrate, and is carried out for the purpose of promptly converging the etching process in the first etching step of the previous step (2). That is,
By supplying the vapor to the substrate surface in this step, the HF vapor remaining on the substrate surface after the etching step is quickly removed, and the etching process is converged at a desired stage. In the step (3), the amount of vapor supplied to the substrate surface is preferably 500 to 700 L, and the same vapor as that used in the step (1) is preferably used.

Step (4) In step (4), the first etching treatment in step (2) is converged by supplying vapor in step (3), and then the chamber and the substrate surface are purged with an inert gas. . The purpose of the step (4) is the step (2).
By replacing the HF vapor in the chamber supplied in the first etching step of performing the first etching process of step 1 with an inert gas, the first etching process can be performed with respect to the second etching process in step (6). It is to prevent the influence of HF vapor. The amount of the inert gas supplied in this step is preferably 200 to 400L. As the inert gas used, the same inert gas as that used in the step (1) or the like can be used.

Step (5) In step (5), vapor is uniformly supplied to the substrate surface. The purpose of this step is to use an inert gas as a carrier and, as in the case of the above step (1), to uniformly adhere vapor or alcohol having a catalytic action in etching to the substrate surface portion by the supply of vapor. Then, in the next second etching step (6), non-uniform etching and occurrence of microroughness on the surface are effectively prevented. The amount of vapor supplied in this step is 150 to 20 as in the case of step (1).
It is preferably 0L. As the vapor to be used, the same ones as those mentioned in the step (1) can be used.

Step (6) Step (6) is a second etching step in which the interface portion of the natural oxide film with the substrate is etched with HF vapor. The purpose of this second etching step (6) is to perform the etching process by targeting the interface portion between the natural oxide film and silicon which could not be removed in the first etching step of the first time. In this process, 10 to 15 [× 10 ^-2 v
It is preferable to perform the treatment for 3 to 6 seconds using anhydrous hydrogen fluoride gas having a concentration of [ol%]. That is, the etching gas having a higher concentration than that in the first etching step is used and the etching is performed for a short time.

Step (7) In step (7), 1000 to 1500 L of vapor is supplied to the substrate surface. The step (7) is performed for the purpose of quickly converging the second etching process, and by supplying the vapor to the substrate surface, the HF vapor remaining on the substrate surface after the second etching step is also performed. Is removed, and the etching process is quickly converged. As a result, the active sample surface after etching can be made inactive, and it is effective that the thermal oxide film is nonuniformly etched during the rinsing in the next step (8) to cause microroughness on the surface. It can be prevented. In this step, it is preferable to further use an inert gas containing a large amount of water vapor as the vapor for 20 to 40 seconds.
This is preferable because the silicon surface from which the natural oxide film has been removed by HF vapor can be terminated with hydrogen.

Step (8) Step (8) is a step of rinsing with deionized water and spin drying, and by this step, the HF vapor and vapor components remaining on the substrate surface, and further the substrate The deposits and the like on the surface are washed away with deionized water and further dried to complete a good treatment of the substrate surface in the vapor phase.

In the method of the present invention, the apparatus of the flow chart shown in FIG. 1 is used, and the step (1) described above is applied to the substrate surface on which the required thermal oxide film and natural oxide film are mixed. )
By performing the etching treatment with anhydrous hydrogen fluoride gas and water vapor or alcohol in two steps according to the procedure of (8) to (8), the thermal oxide film formed on the substrate surface does not exceed the allowable range and is not damaged. The natural oxide film is removed.

The reaction formulas for etching the natural oxide film (SiO ₂ ) formed on the silicon substrate when using anhydrous hydrogen fluoride gas which is the etching gas used in the present invention and steam together with the gas are shown below. It was But,
The chemical formulas given here are hypothetical and do not limit the invention in any way.

[0027]

The above formula (1) is a reaction formula in a system in which steam is not added. In etching the natural oxide film (SiO ₂ ) with anhydrous hydrogen fluoride gas, water vapor H _{2 is used.}
O acts as a catalyst. On the other hand, in the case of a system in which H ₂ O is not added, if there is a film containing water such as a natural oxide film, the water in the film serves as a catalyst to promote the etching reaction. However, if the film itself does not contain much moisture, such as a thermal oxide film, it is hardly etched or the reaction rate of etching is very slow.
As a result, the natural oxide film can be selectively etched on the surface of the substrate where the thermal oxide film and the natural oxide film are mixed. However, when the thermal oxide film is etched in the above, the moisture is unevenly attached to the surface of the thermal oxide film by the outside air, so that only the portion where the moisture is attached may be etched. Occur. Therefore, when the natural oxide film is etched in a gas phase composed of an inert gas and anhydrous hydrogen fluoride gas, microroughness occurs on the surface of the thermal oxide film.

On the other hand, the above (2-1) and (2
The equation (2) is a reaction equation when water vapor is used as a catalyst and an etching treatment is carried out in the presence of H ₂ O. In this case, since the surface of the natural oxide film (SiO ₂ ) is replaced by the hydroxyl group by H ₂ O and then etched by anhydrous hydrogen fluoride, the volatile reaction product SiF ₄ and the non-volatile reaction product Occurs [[2-1) and (2-
2) Expression]. At this time, the non-volatile reaction product is Si,
It is composed of elements such as O, F and H, and exists in an ionic state in H ₂ O which is a side reaction product. As a result, efficient etching is performed. Further, in the method of the present invention,
Before supplying anhydrous hydrogen fluoride gas which is an etching gas, only water vapor or alcohol is first uniformly supplied onto the substrate, and then an etching process is performed. Therefore, the reactions shown in the above equations (2-1) and (2-2) occur uniformly on the surface of the substrate, and uniform etching can be performed without generation of microroughness.

[0030]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the embodiments are merely examples, and the present invention is not limited to these embodiments. An 8-inch bare silicon wafer and a wafer with a thermal oxide film having a thickness of 5 nm (50 Å) were prepared as processing samples. Then, the bare silicon wafer is subjected to a wet treatment with sulfuric acid / hydrogen peroxide which is generally used for removing organic contaminants from the substrate for semiconductor device formation, and a natural oxide film on the surface thereof is 1 to 1.5 nm (10 to 15 nm).
Å) Grow.

The wafer with the thermal oxide film and the bare silicon wafer on which the natural oxide film has grown are etched by the apparatus having the flow shown in FIG. 1 in which the method for treating the substrate surface of the present invention can be carried out. Processed. The processing chamber at this time is an anhydrous hydrogen fluoride vapor processing apparatus (EXCALIBUR (registered trademark) ISR: FSI Interna) having a processing chamber of a closed structure made of vinylidene fluoride (PVDF).
(manufactured by tional Co., Ltd.). The temperature inside the processing chamber was maintained at 30 ° C. by a heater, and the supply gas was also maintained at 24 ° C. The anhydrous hydrogen fluoride gas used had a purity of 99.9%. Nitrogen gas was used as the carrier gas.

<Embodiment 1> The wafers used for the treatment are a bare silicon wafer on which the above-mentioned natural oxide film is grown and a wafer with a thermal oxide film. These wafers were processed by the above anhydrous hydrogen fluoride vapor processing apparatus. In this example, the wafer was placed in the processing chamber, and in the state shown in FIG. 3, before starting the etching process in the etching chamber 1, first, the air in the chamber was purged with nitrogen gas. After that, 170 L of H ₂ O vapor consisting of nitrogen gas containing water vapor
Was uniformly supplied to the surface of the wafer 20 from the gas supply line 3. Next, from the gas supply line 3, the concentration of anhydrous hydrogen fluoride gas in nitrogen gas was 6.9 × 10 ^-2 vol%.
The HF vapor adjusted so that the above was supplied for 20 seconds. After that, the supply of HF vapor was stopped, the same H ₂ O vapor 544L as previously used was supplied again, and then 222L of nitrogen gas alone was supplied from the gas supply line 3 to purge the inside of the chamber. After that, H ₂ again
After supplying 70 L of O vapor, the concentration of anhydrous hydrogen fluoride gas in the nitrogen gas was 13.8 × from the gas supply line 3.
10 ⁻² vol% HF vapor was fed for 5 seconds. Then, the supply of this HF vapor was stopped, and the same H ₂ O vapor 1288L as used previously was supplied again for 30 seconds. During the process from the start to the process, the wafer is
Rotation speed of 50 rpm as the turntable 21 rotates
I rotated it.

After that, with the processing chamber in the state shown in FIG. 4, in the cup of the rinsing chamber 2, a rinse nozzle 25 is shown near the center of the wafer 20 rotated at a rotation speed of 1,000 rpm, as shown in FIG. 450 ml / min of deionized water was supplied from the tank 9 for 10 seconds, and the supply of deionized water was stopped. Then, the wafer 20 is
Spin drying was performed at 000 rpm for 10 seconds. Also,
Nitrogen gas was constantly supplied from the gas supply line 3 also during the rinse and spin drying.

With respect to the bare silicon wafer with a natural oxide film treated by the above method, the contact angle before and after the treatment was measured, and the results are shown in Table 1. The measurement was performed at three different points on the wafer surface. As a result, as shown in Table 1, the contact angle of the wafer surface after the treatment was increased to 40 ° or more, and it was confirmed that the native oxide film was uniformly etched.

[0035]

Regarding the wafer with the thermal oxide film,
The thickness of the thermal oxide film was measured before and after the treatment, and the results are shown in Table 2.
It was shown to. The measurement was performed at three different points on the wafer surface. As a result, as shown in Table 2, the loss of the oxide film was suppressed to about 0.3 nm (3Å).

[0037] The results of Tables 1 and 2 above show that if the method of this example is used in the treatment of the substrate surface in which the required thermal oxide film and the natural oxide film are mixed on the same substrate, the thermal oxide film It shows that the natural oxide film grown on the silicon surface can be removed without exceeding the allowable range and damaging it.

<Example 2> 5 nm before actual gate oxidation
(50Å) The same treatment as in Example 1 was performed on a wafer in which the surface of the thermal oxide film and the surface of the silicon coexist. Then, the film thickness of the thermal oxide film before and after the treatment is measured at four different points,
The results are shown in Table 3. From this result, it was confirmed that even in the actual device wafer, the etching of the thermal oxide film was suppressed, and the natural oxide film could be removed in a state where the etching amount was almost even.

[0039]

[0040]

As described above, according to the present invention, when a thermal oxide film and silicon coexist on the substrate surface, the thermal oxide film is grown on the silicon surface without exceeding the allowable range. It is possible to selectively remove the natural oxide film.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an embodiment of a substrate surface treatment method of the present invention.

FIG. 2 is an explanatory diagram of an etching chamber in FIG.

FIG. 3 is a diagram illustrating an etching position in FIG.

FIG. 4 is a diagram illustrating a rinse chamber in FIG. 1.

[Explanation of symbols]

1: Etching chamber 2: Rinse chamber 3: Gas supply line 4: Exhaust line 5: Gas supply line to the rear surface of the substrate 6: Anhydrous hydrogen fluoride container 7: MFC for supplying anhydrous hydrogen fluoride 8, 8 ₁ , 8 ₂ : Inert gas supply MFC 9: Vapor tank 10: Back pressure controller 11: Rinse water supply line 12: Rinse water drain line 13: Drain 20: Substrate 21: Turntable 22: Diffuser membrane 23: Exhaust membrane 24: Motor 25: Rinse nozzle

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/302 H01L 21/304

Claims (8)

(57) [Claims] 1. A method of treating a surface of a silicon substrate in which a required thermal oxide film and a natural oxide film are mixed on the same substrate, including at least the following steps (1) to (8): The method for treating a substrate surface, which comprises sequentially performing the steps of. (1) Step of supplying an inert gas containing water vapor or alcohol (hereinafter referred to as vapor) to the substrate surface before the first etching step (2) Adding anhydrous hydrogen fluoride gas and water vapor or alcohol to the inert gas The reaction gas (hereinafter, referred to as HF vapor) is used, the thermal oxide film is not etched, and the oxygen concentration is high.
First etching step of etching the surface portion of the natural oxide film under the condition that the natural oxide film is etched (3) Step of supplying vapor to the substrate surface after the first etching step (4) Step of purging the substrate surface (5) Step of supplying vapor to the substrate surface before the second etching step (6) Applying HF vapor to the interface portion of the natural oxide film with the substrate
The thermal oxide film is not etched and the SiO ₂ / Si interface is used.
Second etching step for etching under the condition that a portion is etched (7) Step for supplying vapor to the substrate surface after the second etching step (8) Step for rinsing with deionized water and spin drying 2. In the first etching step (2), HF vapor containing anhydrous hydrogen fluoride gas at a concentration of 5 to 8 [× 10 ⁻² vol%] is used, and the etching treatment by the HF vapor is performed at 20 to 30. The method for treating a substrate surface according to claim 1, which is performed for a second. 3. In the second etching step (6), HF vapor containing anhydrous hydrogen fluoride gas at a concentration of 10 to 15 [× 10 ⁻² vol%] is used, and the etching treatment by the HF vapor is performed at 3 to 6 The method for treating a substrate surface according to claim 1, which is performed for a second. 4. The method for treating a substrate surface according to claim 1, wherein in the step (1) and / or the step (5), 150 to 200 L of vapor is supplied to the substrate surface. 5. The method for treating a substrate surface according to claim 1, wherein 500 to 700 L of vapor is supplied to the substrate surface in the step (3) after the first etching. 6. The method for treating a substrate surface according to claim 1, wherein in the purging step (4) with an inert gas, the inside of the chamber and the substrate surface are purged with 200 to 400 L of an inert gas. 7. The method for treating a substrate surface according to claim 1, wherein in the step (7) after the second etching, 1000 to 1500 L of vapor is supplied to the substrate surface. 8. In the step (7) after the second etching, an inert gas containing a large amount of water vapor is used as a vapor, the gas is treated for 20 to 40 seconds, and the silicon surface after the natural oxide film is removed by HF vapor is used. The processing method according to claim 1, wherein the hydrogen is terminated with hydrogen.