JPH08107104A - Oxide film mask forming method and selective growth method - Google Patents

Abstract

PURPOSE: To make it possible to form a mask of arbitrary size on an arbitrary position by a method wherein an oxide film is formed on a plurality of regions having different oxide film strength, and a selective mask oxide film is selectively remained by the difference in rate of removal of the oxide film. CONSTITUTION: For example, an N-type AlGaAs layer 42a, as an oxide film forming layer, and an N-type AlAs layer 42b are formed on an N-type GaAs substrate 41. Then, resist patterns 43, having two stripe-like windows 44 facing to <011<-> > direction, are formed. Then, selective etching is conducted on one of apertures as far as to AlGaAs, and on the other aperture part as far as to GaAs, and an oxide film is formed on the whole area. The strength of the oxide films in three regions having different constituent elements is in the order of AlAs > AlGaAs > GaAs. Then a removing treatment is conducted by an oxide film removing process until the oxide film only on GaAs, where most easily removable oxide film is formed, is completely removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound semiconductor device, and more particularly to a method for forming an oxide film mask and a selective growth method used in manufacturing the device.

[0002]

2. Description of the Related Art A process technology for compound semiconductors, especially a selective growth technology for optical integrated circuits, is extremely important. However, it is far less reliable and versatile than Si. What makes the selective growth of compound semiconductors difficult is that the following requirements cannot be achieved. 1) Removal of surface contamination 2) Stable surface reconstruction 3) Cleaning while leaving the fine processing pattern 4) Removal of damage during fine processing 5) Formation of selected area (positioning and fineness) 6) Selection mask Selectivity, reliability (when using selective mask) 7) Complete removal of selective mask (when using selective mask) 8) High throughput Among the above, 1) to 4) are regrowth before selective growth However, some effective means are being proposed recently. Items 5) to 8) are directly related to selective growth.

Several approaches have been proposed to achieve these. a) A stable dielectric film (such as SiO ₂ or SiNx) is patterned by a photolithography technique to form a selective mask, which is selectively grown by LPE or MOCVD, and the selective mask is peeled off after the growth (for example, K. Shimoyama).
et al. , Journal of Crystal
l Growth, 107 (1991) 767). b) A thin oxide layer is formed on the surface of GaAs or the like by UV irradiation or the like, and the oxide layer is selectively stripped by EB drawing (for example, Y. Hiratani et al., Jour.
nal of Crystal Growth, 11
1 (1991) 570). c) A nucleation pattern is drawn on a GaAs substrate by EB or ion implantation to grow an epilayer having a different lattice constant, such as InP (for example, J. Ahopelt).
et al. , Proceedings 20th
International Symposium
on Gallium Arsenide and re
late Compounds, Freibur
g, 1993). d) By light (heat) excitation by PL or the like in a growth atmosphere,
The substrate is selectively activated while drawing a pattern (eg, Doi et al., Applie).
d Physics Letters, 48, 17
87 (1986)).

Since b) to d) are essentially in-situ processes and maskless, there is no problem with 1) and 5). In particular, it is considered to be effective in fabricating low-dimensional superstructures that are expected in the future. However, it is not always possible to meet the demand for selective growth, which is required now or in the future, that is, "arbitrary position, arbitrary size, arbitrary structure, and low cost". This is because any of these methods requires an extremely expensive device, has no flexibility in the device size that can be selectively grown, and cannot expect reliability and throughput for the time being.

The method a) is currently the mainstream method,
Since photolithography technology can be used freely, it has been partially used as a selective growth method for integration of heterogeneous devices. However, there are problems in selective growth and reliability in selective growth, and difficulty in efficiently forming and removing the dielectric film mask, and since the problems of selective growth have not been fundamentally solved, the applications that can be used are extremely limited. Has been done.

[0006]

As described above, in the compound semiconductor device, there is known a mask forming method capable of efficiently forming a mask for selective growth and efficiently removing the mask. Didn't. Moreover, such a selective growth method has not been known. An object of the present invention is to provide an oxide film mask forming method and a selective growth method which have a wide application range and high reliability for a compound semiconductor device.

[0007]

According to the gist of the present invention, a plurality of regions having different oxide film strengths (etching resistance) of an oxide film formed thereon are formed, and an oxide film is further formed thereon. However, the selective mask oxide film is selectively left as a mask due to the difference in the removal rate of the oxide film formed on each region.

Therefore, in the present application, as an oxide film mask forming method, there is provided an oxide film mask forming method of forming an oxide film mask on a compound semiconductor, wherein one of the constituent elements and the composition ratio of the constituent elements is formed on the compound semiconductor surface. Or, after providing a plurality of regions different from each other, the compound semiconductor surface is entirely oxidized to form an oxide film on the surface of each of the plurality of regions, and the oxide film formed in the plurality of regions is removed. Of the plurality of regions, the oxide film is removed from the first region in which the oxide film to be formed is relatively easy to be removed, and the oxide film is left in the regions other than the first region to be oxidized. A method for forming an oxide film mask, which comprises forming a film mask, which is a selective growth method for performing selective growth on a compound semiconductor as a selective growth method, comprising: On the other hand either the composition ratio of the constituent elements,
Alternatively, after providing a plurality of regions different from each other, the compound semiconductor surface is entirely oxidized to form an oxide film on the surface of each of the plurality of regions, and the oxide film formed in the plurality of regions is removed. By the process, the oxide film is removed from the first region of the plurality of regions where the oxide film to be formed is relatively easily removed, and the oxide film is left in the regions other than the first region to leave the oxide film. There is provided a selective growth method characterized in that a mask is formed, epitaxial growth is performed, and selective growth is performed in the first region.

Further, in this selective growth method, after the selective growth is performed on the first region, the remaining oxide film is removed, so that a region other than the first region is removed.
The oxide film to be formed is more difficult to remove than the first region, and the oxide film is removed from the second region, which is easier to remove than the other regions, and the oxide film is left in the other regions to form an oxide film mask. Form and perform epitaxial growth,
There is provided a selective growth method characterized by performing selective growth also in the second region, and in these selective growth methods, the epitaxial growth is performed by a gas source molecular beam epitaxial growth method. A method of providing a selective growth method, further comprising providing a plurality of regions in which one or both of the constituent elements and the composition ratio of the constituent elements are provided in the oxide film mask forming method and the selective growth method. Either one of the composition ratios of the elements and the constituent elements, or a plurality of compound semiconductor layers having different composition ratios are stacked, and in a desired region,
Provided is an oxide film mask forming method and a selective growth method, wherein a part of the stacked compound semiconductor layers is removed to expose a desired constituent element or a compound semiconductor having a desired composition ratio of constituent elements. Further, in the oxide film mask forming method and the selective growth method, one of the constituent elements and the composition ratio of the constituent elements, or each of a plurality of regions in which both are different from each other, is a compound semiconductor Al _X Ga _{1- In X} As or Ga _X In _1-X As _Y P _1-Y , X,
Provided are an oxide film mask forming method and a selective growth method, wherein Y is selected in a range of 0 or more and 1 or less, and further, in the oxide film mask forming method and the selective growth method, the oxidation is performed. The method of forming a film is
Provided are an oxide film mask forming method and a selective growth method, which are ECR-excited dry etching containing oxygen as a main component, and further, in the oxide film mask forming method and the selective growth method, a compound semiconductor surface is provided. Before forming an oxide film on the surface of each of the plurality of regions by completely oxidizing the compound semiconductor surface after providing a plurality of regions in which one or both of the constituent elements and the composition ratio of the constituent elements are different from each other In addition, a method of forming an oxide film mask and a method of selective growth are characterized by removing residual contaminants on the surface of a compound semiconductor.

Further, in this method, the method of removing the residual contaminants mainly comprises removing residual contaminants other than oxygen, and removing the oxide film. Method and selective growth method,
Further, in this method, there is provided an oxide film mask forming method and a selective growth method, wherein the step of removing residual contaminants other than oxygen is ECR-excited dry etching containing oxygen as a main component.

Further, there is provided the above-described oxide film mask forming method and selective growth method, wherein the step of removing the oxide film is a step of irradiating an As molecular beam in hydrogen plasma. A method for forming an oxide film mask and a selective growth method, characterized in that the hydrogen plasma is supplied by ECR excitation.

[0012]

The function of the present invention will be specifically described below.

FIG. 1 is a schematic view of an apparatus for forming an oxide film mask and performing selective growth according to the present invention. Reference numeral 31 is a load lock chamber, 32 is a first etching chamber for forming an oxide layer, 33 is a second etching chamber for removing an oxide film, 34 is a growth chamber for regrowth, and 35 is a vacuum tunnel for connecting the respective processes. .

By using oxygen plasma in the first etching chamber 32, a thin and strong oxide layer can be formed.

At this time, the state of the oxide film formed by the layer exposed on the surface (for example, GaP and AlP) is different.

A vacuum tunnel 35 is provided in the second etching chamber 33.
Oxide film removal can be carried out without being exposed to a new contamination source by transferring via the. The effect of removing the oxide film is increased by irradiating the wafer with an As beam as well as the hydrogen plasma that is normally used when removing the oxide film. Moreover, since the oxide film can be removed at a P desorption temperature (up to 350 ° C.) or lower, damage to the crystal is extremely small. This oxide film removal method is disclosed in detail in Japanese Patent Application No. 6-144604 filed by the same applicant as the present application.

FIG. 2 schematically shows the relationship between the etching rate of the oxide film and the substrate temperature in the case of only hydrogen plasma, the case of As beam irradiation only, and the case of using both of them. It was found that the combination of both as compared with As molecular beam alone or ECR etching of hydrogen has an oxide film removing ability higher than the sum etching rate of both and has extremely low damage to the crystal. Although the mechanism is not clear, it is supposed that ECR-induced H ^* + H ⁺ accelerates oxygen desorption by As.

The removal time of the oxide layer formed in the previous oxide film forming step depends on the constituent elements of the exposed epitaxial layer and the composition ratio of the constituent elements. For example,
Comparing GaP and AlP, the time for removing the oxide film by the method of the present invention is three times longer in AlP. This is because AlP is easier to form a stronger oxide film, that is, the oxide film is hard to be removed. The most characteristic part of the present invention is to utilize this difference in oxide film removal time.
That is, the oxide film is removed in the region where the oxide film removal time is short, the oxide film is not completely removed and remains in the region where the oxide film removal time is long, and the remaining oxide film serves as a mask.

Growth is performed in the next growth chamber. For the oxide film according to the present invention, gas source molecular beam epitaxial (gas source MBE) in which components are supplied by a gas source.
Method, especially CBE method (Chemical Beam Ep)
It was found that itaxy) has the largest selection ratio and that high quality crystals can be obtained. This is a normal gas source M
When BE supplies a group III-V element, group V is supplied by a gas source, while group III is supplied as a solid, whereas in CBE, both group III and group V are supplied by gas, and therefore the substrate It is thought that the diffusion length on the surface is due to the longer CBE. Similarly, the metal organic chemical vapor deposition method (MOCVD method) using a gas source is excellent in selectivity, but is not compatible with high vacuum. Therefore, in the present invention, it is desirable to use the gas source MBE or CBE.

[0020]

【Example】

(Embodiment 1) As a first embodiment of the present invention, an example in which the oxide film mask forming method and the selective growth method of the present invention are used for manufacturing a buried laser will be described.

FIG. 3 is a schematic view of the manufacturing process. For example, after growing an n-type AlAs layer 42 (thickness 100 nm) as an oxide film forming layer on a (100) n-type GaAs substrate 41, <011
A resist pattern 43 having a window 44 on a stripe having a width of 5 μm is formed along the _> direction (FIG. 3A). After that, AlAs in the opening was selectively etched with a hydrofluoric acid-based etchant. After that, the resist was removed (FIG. 3B), and then the process apparatus of FIG. 1 was loaded.
Here, the surface residual contaminants were removed from the above-mentioned Japanese Patent Application No. 6-114460.
Complete removal by the contaminant removal method described in detail in Section 4.

Here, the method for removing the contaminant will be described. This contaminant removal method mainly includes a step of removing contaminants other than oxygen and a step of removing an oxide film that is a contaminant. As a step of removing contaminants other than oxygen, oxygen is the main component. As a step of removing the oxide film by performing ECR-excited dry etching, the oxide film removing method of irradiating As molecular beam in hydrogen plasma was used. The ECR-excited dry etching containing oxygen as a main component for removing contaminants other than oxygen is the same as the oxide film formation process used below, even if various parameters such as gas pressure and etching time are made different. This is a process, and both were performed in the first etching chamber 32. Also, the process of removing the oxide film that is a contaminant is the same process as the oxide film removing process for forming the oxide film mask and the oxide film removing process for finally removing the oxide film mask, which will be used below. Both were performed in the second etching chamber 33. In the present embodiment, since the first and second etching chambers and the growth chamber 34 for performing epitaxial growth are connected by the vacuum tunnel 35, after the residual contaminants are removed, the selective growth without receiving new contamination. It can be performed. In this embodiment, the contaminants are removed as described above. However, after the selective growth region is formed at a desired position by the selective etching as described above, if the contaminants are not exposed, the contaminants are not removed. If the oxide film does not adhere even if it adheres, it is not necessary to perform the above-mentioned removal of contaminants, and the following process can be performed.

As described above, the contaminants other than oxygen are removed in the first etching chamber 32, the oxide film which is the contaminant is removed in the second etching chamber 33, and then the vacuum tunnel 35 is again used.
To transfer to the first etching room. Here, ECR etching is performed using high-purity oxygen. Etching conditions are gas pressure 3.0E-3 Torr, ECR power 10
0 W and an etching time of 10 minutes were used. As a result, Ga
A "weak" oxide film covers the surface on the As surface, and a "strong" oxide film covers the surface on AlAs (FIG. 3C). The thickness of these oxide films is several nm to several tens of nm and is extremely stable as compared with atmospheric oxide films and the like because it does not contain impurities other than oxygen.

Next, vacuum transfer to the second etching chamber 33 through the vacuum tunnel 35 is performed to excite ECR of high-purity hydrogen, and an As molecular beam is applied to the heated wafer by using a gas cell, and an oxide film is formed. Remove 45. The conditions at this time are as follows: gas pressure 5E-4 Torr, ECR power 10
0 W, substrate temperature 300 ° C., arsine flow rate 2 SCCM, cracking temperature 900 ° C., processing time 30 minutes. Under this condition, the oxide film on GaAs is completely removed and A
A sufficient oxide film remains on the 1As surface.

Next, it is transferred to the growth chamber through the vacuum tunnel 35, and crystal growth by CBE is performed. The reason why CBE is used is that a sufficiently large selection ratio can be obtained for this oxide film. Under conditions of a substrate temperature of 500 ° C. and a V / III ratio of 20, the n-type AlGaAs clad layer 47 and AlGaA
An s / GaAs quantum well active layer 48, a p-type AlGaAs cladding layer 49, and a p-type GaAs contact layer 50 were grown. At this time, neither a single crystal nor a polycrystal grows on AlAs having an oxide film. This is because the oxide film of this embodiment is kept extremely clean and there is no nucleus for poly growth, so that the growth with an extremely high selectivity is performed. Also, set the stripe direction to <
As a result of selecting the 011_> direction, the cross section becomes a triangular shape due to the plane orientation dependence of the growth rate, and the growth stops when the apexes of the triangle are formed.

After this, the second tunnel is conducted via the vacuum tunnel 35.
Transfer back to the etching room and using the previous conditions this time A
The process is performed until the oxide film on 1As is completely removed.

Next, it is transferred to the growth chamber 34 via the vacuum tunnel 35, and the buried growth is performed this time. The growth conditions are the same as the above except that the V / III ratio is 5, and p-type AlGa
An As layer 51, an n-type AlGaAs layer 52, and a p-type contact layer 53 were grown. As a result, since there is no selection mask, A
It also grows on lAs. The buried laser is completed by completely filling the previously grown triangular epitaxial layer. The V / III ratio is set to 5 in order to relax the dependence of the growth rate on the plane orientation.
May be used.

(Embodiment 2) As a second embodiment, an example in which the present invention is applied to a two-wavelength laser array will be described.
FIG. 4 is a schematic diagram for explaining the manufacturing process. First, for example, as an oxide film forming layer, n
-Type AlGaAs layer 42 (a) and n-type AlAs layer 42
After stacking (b), a resist pattern 43 having two stripe-shaped windows 44 with a width of 5 μm at intervals of 50 μm along the <011_> direction is formed by photolithography (FIG. 4A). . After that, two kinds of hydrofluoric acid type etchants were used to selectively etch one of the openings up to AlGaAs and the other up to GaAs. After that, an oxide film is formed on the entire surface (see FIG. 4).
(C)). As is clear from the figure, in this embodiment, three regions having different constituent elements are formed and an oxide film is formed on each of the three regions. The strength of the oxide film in each region is in the order of AlAs>AlGaAs> GaAs.

After that, in the oxide film removing step, processing is performed until only the oxide film on GaAs where the oxide film that is most easily removed is formed can be completely removed, and then the laser structure having the wavelength λ1 is formed in the growth chamber 34. (47-50)
Crystal growth is performed (FIG. 4D).

Then, vacuum transfer is performed to the second etching chamber, and Ga
Al with an oxide film that is easily removed next to As
Processing is performed until the oxide film on GaAs can be removed, vacuum transfer is performed to the growth chamber, and a laser structure having a wavelength λ2 (54-
57) is epitaxially grown (FIG. 4E).

Next, the film is transferred again to the second etching chamber, where A
The process is performed until the oxide film of 1As is completely removed, and the film is transferred to the growth chamber, where the same buried growth as in Example 1 (51-5
By performing 3), a laser array having wavelengths λ1 and λ2 can be realized (FIG. 4 (e)).

As in the present embodiment, by providing three or more Al _X Ga _{1 -X} As (0≤X≤1) having different compositions exposed to the regions, selective growth having different configurations is performed at a plurality of positions. Therefore, the multi-wavelength laser array as in this embodiment can be realized.

Example 3 In Examples 1 and 2, III
The example in which the difference in the composition of the group element (Al) causes the difference in the strength of the oxide film has been described. Next, an example according to the difference in the composition of the V group element will be described.

When the oxide film forming step and the oxide film removing step in the present invention are used, InGaAs>InGaAsP>
It was found that the oxide film formed on each compound semiconductor was strong in the order of InP. Therefore, this relationship is described in Example 1.
It can be used as it is in the device manufacturing process of (2) and (2). That is, in Examples 1 and 2, as the oxide film forming layer, for example, InGaAs instead of AlAs was used.
By using InGaAsP instead of lGaAs, a buried laser and a multi-wavelength laser array can be manufactured with high reliability and at low cost. In the present embodiment, P which is easily desorbed is contained as a constituent element, and it is conceivable that P is desorbed depending on conditions such as temperature when the oxide film is removed. In that case, P is removed when the oxide film is removed. It is good to give a partial pressure to it.

(Embodiment 4) The present invention can be applied to a material system in which Al, As, and P are mixed. For example, considering AlGaInP / AlGaAs lattice-matched to GaAs, the oxide film forming step and the oxide film removal in the present invention are considered. It was found that the oxide film formed on each compound semiconductor was strong in the order of AlGaAs>AlGaInP> GaInP when the process was used. Therefore, this relationship can be directly used in the device manufacturing process of the first and second embodiments. That is, in Examples 1 and 2, by using, for example, InGaP instead of AlAs and AlGaInP instead of AlGaAs as the oxide film forming layer, a buried laser or a multi-wavelength laser array can be manufactured with high reliability and at low cost. . Similar to the third embodiment, a partial pressure may be applied to P when the oxide film is removed depending on the conditions.

Although each of the above-described embodiments describes only the method of manufacturing a laser, it can be applied to other devices and integrated with other devices, such as a photodetector, an optical modulator, an optical waveguide, and the like. Needless to say, it is possible to accumulate.

Although the gas source (arsine) is used as the As molecular beam used in the oxide film removing step of the above embodiment, a solid source may be used. However, in order to enhance the effect of removing the oxide film, it is desirable to pass through a thermal decomposition device such as a cracking furnace.

[0038]

The effects of the present invention are as follows. 1. For the area where the selective growth is performed, the conventional photolithography process having excellent reliability and economy can be used, and the position and size of the area can be freely determined. 2. Selective growth is possible without using a dielectric mask such as SiO ₂ and throughput and versatility are remarkably improved. 3. Residual contaminants can be removed by the same process as the oxide film forming process and the oxide film removing process in the present invention. 4. Between constituent elements and regions with different composition ratios of constituent elements,
Since it suffices that the oxide films formed on these regions have different strengths, there are many combinations of such constituent elements and composition ratios of constituent elements, and the present invention can be applied to various material systems. . 5. Since the oxide film mask can be removed without damaging the compound semiconductor therebelow, a good device can be obtained. 6. A region for selective growth can be easily determined, and subsequent mask formation and selective growth can be performed without breaking vacuum, so that a high quality device can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view of an apparatus configuration for realizing an oxide film mask forming method and a selective growth method of the present invention.

FIG. 2 is a graph showing the relationship between the etch rate and the substrate temperature in the oxide film removing step used in the present invention.

FIG. 3 is a diagram showing each step of the first embodiment of the present invention.

FIG. 4 is a diagram showing each step of the second embodiment of the present invention.

[Explanation of symbols]

 31 load lock chamber 32 first etching chamber 33 second etching chamber 34 growth chamber 35 vacuum tunnel 41 substrate 42 oxide film forming layer 43 resist mask 44 opening (selective growth region) 45 oxide film

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // H01S 3/18

Claims (12)

[Claims] 1. A method of forming an oxide film mask for forming an oxide film mask on a compound semiconductor, comprising a plurality of regions on a compound semiconductor surface, wherein one or both of constituent elements and composition ratios of constituent elements are different from each other. After that, the compound semiconductor surface is entirely oxidized to form an oxide film on the surface of each of the plurality of regions, and the oxide film formed in the plurality of regions is removed. An oxide film mask is formed by removing the oxide film from a first region in which the oxide film to be formed is relatively easy to remove and leaving the oxide film in a region other than the first region. Method for forming oxide film mask. 2. A selective growth method for performing selective growth on a compound semiconductor, comprising the steps of providing a compound semiconductor surface with a plurality of regions having different constituent elements, different composition ratios of constituent elements, or both. Forming a portion of the plurality of regions by oxidizing the entire surface of the compound semiconductor to form an oxide film on each surface of the plurality of regions and removing the oxide film formed in the plurality of regions. The oxide film is removed from the first region where the oxide film to be removed is relatively easy to be removed, and the oxide film is left in regions other than the first region to form an oxide film mask, and epitaxial growth is performed. 1. A selective growth method characterized by performing selective growth in a region 1. 3. After performing selective growth in the first region,
Due to the step of removing the residual oxide film, the oxide film to be formed, of the regions other than the first region, is more difficult to be removed than the first region and is easier to be removed than the other regions. 3. The oxide film is removed, the oxide film is left in the other regions to form an oxide film mask, epitaxial growth is performed, and selective growth is also performed in the second region. Selective growth method. 4. The selective growth method according to claim 2, wherein the epitaxial growth is performed by a gas source molecular beam epitaxial growth method. 5. A method of providing a plurality of regions in which one or both of the constituent elements and the composition ratio of the constituent elements are different from each other is one of the constituent elements and the composition ratio of the constituent elements, or both of them are different from each other. A plurality of compound semiconductor layers are stacked, and the stacked compound semiconductor layers are partially removed in a desired region to expose a compound semiconductor having a desired constituent element or a composition ratio of a desired constituent element. The oxide film mask forming method and the selective growth method according to claim 1. 6. One of the constituent elements and the composition ratio of the constituent elements, or each of a plurality of regions having different composition ratios, is made of a compound semiconductor such as Al _X Ga _1-X As or Ga _X In.
_1-X As _Y P _1-Y, wherein X and Y are each selected in the range of 0 or more and 1 or less.
5. A method for forming an oxide film mask and a selective growth method according to any one of 5 to 6. 7. The method of forming an oxide film mask and the selective growth method according to claim 1, wherein the method of forming the oxide film is ECR-excited dry etching containing oxygen as a main component. 8. A compound semiconductor surface is provided with a plurality of regions in which one or both of constituent elements and composition ratios of constituent elements are different from each other, and then the compound semiconductor surface is entirely oxidized to form each of the plurality of areas. 8. The method for forming an oxide film mask and the selective growth method according to claim 1, wherein residual contaminants on the surface of the compound semiconductor are removed before the oxide film is formed on the surface of the oxide semiconductor. 9. The oxide film mask according to claim 8, wherein the method of removing the residual contaminants mainly comprises removing residual contaminants other than oxygen, and removing the oxide film. Forming method and selective growth method. 10. The oxide film mask forming method and selective growth method according to claim 9, wherein the step of removing residual contaminants other than oxygen is ECR-excited dry etching containing oxygen as a main component. . 11. The method for forming an oxide film mask and the selective growth method according to claim 1, wherein the step of removing the oxide film is a step of irradiating an As molecular beam in hydrogen plasma. 12. The method for forming an oxide film mask and the selective growth method according to claim 11, wherein the hydrogen plasma is supplied by ECR excitation.