JP3166743B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device for growing a defect-free epitaxial film.

[0002]

2. Description of the Related Art The structure of a substrate to be processed on which a SiGe epitaxial base is grown as an epitaxial film is shown in FIG. In FIG. 3A, the surface of the substrate to be processed is covered with a nitride film 4 and has an opening 5, in which the single crystal silicon substrate 1 is exposed. Is covered with a nitride film 4, and near the bottom of the opening 5 where the single crystal silicon substrate 1 is exposed, a tunnel 6 having an enlarged opening diameter is formed. Is 100
The silicon oxide film 2 has a thickness of up to 1000 angstroms.

Also, a polysilicon 3 serving as a base extraction electrode extends above the tunnel 6, and a single crystal silicon substrate 1 is exposed at the bottom of the tunnel 6. FIG. 3 (b)
In the above, a SiGe epitaxial base 7 is selectively epitaxially grown on the single crystal silicon substrate 1 exposed in the opening 5.

At this time, polycrystalline SiGe 8 also grows from the polysilicon 3 above the tunnel 6. Since the polysilicon 3 is a base extraction electrode, when growing the SiGe epitaxial base 7, the polysilicon 3 is so contacted that the SiGe epitaxial base 7 and the polycrystalline SiGe 8 are in contact with each other.
Grow each.

FIG. 4 shows an SiGe epitaxial base 7.
Is shown. In FIG. 4A, a resist 9 is applied to a stack of a single crystal silicon substrate 1, a silicon oxide film 2, a polysilicon 3, and a nitride film 4 as a substrate to be processed, and then patterned using a lithography technique. Using the resist 9 as a mask, the opening 5 reaching the silicon oxide film 2 is formed by dry etching.

In this dry etching process, only the nitride film 4 and the polysilicon 3 are etched, and the silicon oxide film 2 is left. In FIG. 4B, after removing the resist, a nitride film 4 is deposited over the side surface and the bottom surface of the opening 5 by using the CVD method, and is again subjected to dry etching, as shown in FIG. 4C. The nitride film 4 on the bottom of the opening 5
Remove only a.

Next, the substrate to be processed is immersed in an aqueous solution of hydrofluoric acid to remove the silicon oxide film 2 at the bottom of the opening 5, and FIG.
As described above, an expanded tunnel 6 is formed in the opening 5 to expose the single crystal silicon substrate 1. The silicon oxide film 2 has an effect of protecting the single crystal silicon substrate 1,
This prevents the single crystal silicon substrate 1 , which is the growth surface, from being damaged during the dry etching process.

The SiGe epitaxial base 7 is shown in FIG.
As shown in (e), the single crystal silicon substrate 1 thus exposed is selectively epitaxially grown. The selective growth of SiGe epitaxial film is 1 × 10
UHV-CVD method for growing at a pressure of ^-3 Torr or less, and reduced pressure C performed at a pressure of about 10 to 100 Torr.
This is performed using the VD method.

[0009]

By the way, even under the condition that epitaxial growth can be performed without defects on the silicon bare substrate, even if the surface of the single crystal silicon substrate is protected by the silicon oxide film on the pattern substrate of the device, the epitaxial film grown on the Causes defects. The reason why such a defect occurs is considered as follows.

That is, during the dry etching process for forming the opening 5, the single crystal silicon substrate surface 1 is protected by the silicon oxide film 2, so that no single crystal silicon substrate 1 has any defects. By the dry etching of the silicon 3, a carbon-based deposit 10 is deposited on the silicon oxide film 2.

The carbon-based deposit 10 cannot be removed even if the silicon oxide film is etched with a hydrofluoric acid aqueous solution in the next step, and remains on the single-crystal silicon substrate 1 as it is. There is a problem that the SiGe epitaxial base 7 epitaxially grown on the substrate 1 becomes a defect.

An object of the present invention is to provide a method of manufacturing a semiconductor device in which a foreign substance is removed from the surface of a silicon oxide film before the silicon oxide film is removed, and a defect does not occur in an epitaxial film grown thereafter. .

[0013]

In order to achieve the above object, in a method of manufacturing a semiconductor device according to the present invention, there is provided a method for manufacturing a semiconductor device. A method of manufacturing a semiconductor device for growing an epitaxial film, wherein the foreign matter removing process is performed after the dry etching process.
Of carbon deposits on silicon oxide film
To prevent foreign matter from adhering to the single crystal silicon substrate,
This is a process for preventing the occurrence of defects in the epitaxial film .

Further, the foreign matter removing process is performed on the substrate to be processed.
For removing the nitride film in the opening to be etched by dry etching.
Process, it remains as a contaminant on the surface of the silicon oxide film.
This is a process for removing carbon-based deposits .

[0015]

[0016]

[0017]

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) The present invention relates to a method of manufacturing a semiconductor device in which a SiGe epitaxial base is grown as an epitaxial film on a single crystal silicon substrate in an opening formed by performing a dry etching process on a substrate to be processed. Then, carbon-based deposits deposited on the substrate to be processed by dry etching are removed.

FIG. 1 shows a process of forming a substrate to be processed in the first embodiment. In FIG. 1A, the substrate to be processed is
It is a laminate of a single crystal silicon substrate 1, a silicon oxide film 2, polysilicon 3, and a nitride film 4. A resist 9 is applied to the surface of the nitride film 4 of the stacked body, and then the silicon oxide film 2 is formed by dry etching using the resist 9 patterned using lithography as a mask.
Is formed.

In the dry etching process, only the nitride film 4 and the polysilicon 3 are etched, and the silicon oxide film 2 is left. After removing the resist, a nitride film 4 is deposited by CVD as shown in FIG. 1B to cover the side surfaces with the nitride film, and dry-etched again, and as shown in FIG. The bottom nitride film 4a is removed by dry etching.

As a result, carbon-based deposits 10 are deposited on the surface of the silicon oxide film 2 as foreign substances. next,
As the foreign matter removal processing, the substrate to be processed is placed in an oxygen atmosphere at 80
Heat treatment is performed at 0 ° C. for 10 minutes to burn off carbon-based deposits 10 on the surface of the silicon oxide film 2 as shown in FIG.
Further, the silicon oxide film 2 is removed by immersion in an aqueous solution of hydrofluoric acid as shown in FIG. 1E, an expanded tunnel 6 is formed in the opening 5, and the single crystal silicon substrate 1 is formed in the opening 5. To expose.

In this embodiment, the SiGe epitaxial base 7 as an epitaxial film was grown using a UHV-CVD apparatus having a base pressure of 1 × 10 ⁻⁹ Torr or less.

Next, the SiGe epitaxial base 7
Prior to the growth of GaN, a heat treatment at 850 ° C. at 1 × 10 ⁻⁶ Torr or less was performed to evaporate the natural oxide film on the single crystal silicon substrate 1. The SiGe epitaxial base 7 is formed by using disilane and germane as a growth gas, and adding chlorine gas to improve selectivity at 650.degree.
^The test was performed under a pressure condition of ^-3 Torr or less.

Further, boron was doped into the SiGe epitaxial base 7 by simultaneously introducing diborane gas. As a result, the SiGe epitaxial base 7 was selectively formed on the single crystal silicon substrate 1 exposed in the opening 5 as shown in FIG.

In order to obtain a defect-free SiGe epitaxial base 7, the surface of the single crystal silicon substrate 1, which is the growth surface, must be free from defect damage and foreign matter. In the first embodiment, a heat treatment is performed in an oxygen atmosphere as a foreign matter removing process after the dry etching process to remove the carbon-based deposits 10 on the silicon oxide film 2 due to the dry etching process. This prevents foreign substances from adhering to the substrate 1 and prevents defects of the SiGe epitaxial base 7, which is an epitaxial film, from occurring. The carbon-based deposit 10 as a foreign substance is exposed to a high temperature of a heat treatment temperature of 800 ° C. or more in an oxygen atmosphere, reacts with oxygen, becomes CO or CO _2, and separates from the surface of the silicon oxide film.

(Embodiment 2) FIG. 2 shows a process of epitaxially forming a substrate to be processed in Embodiment 2. In the first embodiment, the carbon-based deposit 10 is removed by using a heat treatment in an oxygen atmosphere as the foreign matter removing process, whereas in the present embodiment, an oxygen plasma process is used.

Also in the second embodiment, the processing for forming the opening 5 is the same as that in the first embodiment. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and description of each processing step is omitted. In the second embodiment, the carbon-based deposit 10 deposited on the bottom of the opening 5 shown in FIG.
In (d), it was removed by oxygen plasma treatment.
The oxygen plasma treatment was performed for 90 minutes.

In FIG. 2F, the SiGe epitaxial base 7 was formed by a low pressure CVD method. The natural oxide film on the single crystal silicon substrate 1 was removed with an aqueous solution of hydrofluoric acid immediately before introduction into the growth chamber. Further, a heat treatment at 850 ° C. was performed in a hydrogen atmosphere in a growth chamber before the epitaxial growth, and impurities such as oxygen attached to the single crystal silicon substrate 1 after the hydrofluoric acid treatment were removed immediately before.

In the second embodiment, the formation of the SiGe epitaxial base 7 is performed using dichlorosilane hydrogen-hydrogen chloride, and the growth pressure is set at 750 ° C. to 10-1.
Performed at 00 Torr. Thus, the SiGe epitaxial base 7 could be selectively formed on the single crystal silicon substrate 1 in the opening 5.

No defects were found in the SiGe epitaxial base 7 grown on the single-crystal silicon substrate 1 using the second embodiment. This is because the carbon-based deposit 10 reacted with oxygen and was separated from the silicon oxide film 2 in the form of CO or CO ₂ by the oxygen plasma treatment as the foreign matter removing treatment of the second embodiment. Although an example in which a silicon germanium alloy is used for the epitaxially grown film has been described, the same effect can be obtained even when the epitaxially grown film is silicon.

In the SiGe epitaxial base 7 formed by the conventional method, two to five concave defects were observed in the opening of 0.8 μm × 2 μm size. No defect was found in the opening of the substrate.

[0032]

As described above, the carbon-based deposits remaining as contaminants on the surface of the silicon oxide film due to the process of removing the bottom nitride film in the opening of the substrate to be processed by dry etching are converted to hydrofluoric acid. The silicon oxide film adheres to the surface of the silicon substrate without being completely removed by the treatment, and this causes a defect of the epitaxial film. According to the present invention, by performing the foreign matter removal treatment before removing the silicon oxide film, the silicon oxide film is removed. Thus, the carbon-based deposit can be completely removed, whereby a defect-free epitaxial film can be formed. In particular, as the removal processing of the foreign material, 800 ° C. or more heat treatment or in an oxygen atmosphere, by which processes exposed to O ₂ plasma state, to oxidize the carbonaceous contaminant, CO or C
O ₂ can be released from the surface of the silicon oxide film.

[Brief description of the drawings]

FIG. 1 is a diagram showing a process of forming a substrate to be processed in a first embodiment.

FIG. 2 is a view showing a process of forming a substrate to be processed in a second embodiment.

FIG. 3 is a diagram showing a structure of a substrate to be processed on which a SiGe epitaxial base is grown.

FIG. 4 is a view showing a step of forming a SiGe epitaxial base.

[Description of Signs] 1 Single-crystal silicon substrate 2 Silicon oxide film 3 Polysilicon 4, 4a Nitride film 5 Opening 6 Tunnel 9 Resist 10 Carbon-based deposit

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01L 21/205 H01L 21/31 H01L 21/3065 C23C 16/00 C30B 25/00 C30B 29/00

Claims (2)

(57) [Claims] 1. A single-crystal silicon substrate having an opening formed by performing a dry etching process and having a foreign matter removing process,
A method for manufacturing a semiconductor device for growing an epitaxial film , comprising:
-Based deposits on silicon oxide films due to tinting
To prevent foreign matter from adhering to the single crystal silicon substrate.
Process to prevent the occurrence of defects in the epitaxial film
A method for manufacturing a semiconductor device, comprising: 2. The foreign matter removing process is a process of removing a carbon-based deposit remaining as a contaminant on the surface of a silicon oxide film by a process of removing a nitride film in an opening formed on a substrate to be processed by dry etching. Claims characterized by the following:
2. The method for manufacturing a semiconductor device according to item 1 .