JPH01134914A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a buried collector layer by a method wherein a window is provided by conducting an anisotropic etching method on a two-layer film, the surface of a substrate is isotropically etched, impurities are diffused into the substrate and an oxide film is formed on the surface of the substrate with a mask used only once. CONSTITUTION:The second conductive type impurity containing film 12 and a film 13, which becomes a mask material, are deposited on the first conductive type semiconductor substrate 11. A window is provided by conducting anisotropical etching on a two-layer deposited film, isotropical etching is conducted on the surface of the substrate 11 through the window 15, and a recessed part 16 is formed on the substrate 11. The second conductive type diffusion layer 17 is formed by diffusing the impurities contained in the impurity- containing film 12 into the substrate 11, and an oxide film 18 is formed on the surface of the exposed substrate 11. The first conductive type impurities are diffused into the substrate 11 through the intermediary of the oxide film 18. The film 13 which becomes a mask material, the oxide film 18 and the impurity-containing film 12 are removed. An epitaxial layer 20 is grown. As a result, a buried collector layer is formed by using a mask only once.

Description

[Detailed Description of the Invention] [Required] Regarding a method for diffusing a buried collector in a semiconductor device and forming a step for recognizing the buried collector layer, the buried collector layer can be formed using a simpler process with fewer masks than before. and a step of depositing a second conductivity type impurity-containing film and a film serving as a mask material on a first conductivity type semiconductor substrate; a process of anisotropically etching the films deposited on the substrate to open windows through these films, and isotropically etching the surface of the semiconductor substrate through the windows to form a recess in the substrate; impurities contained in the impurity-containing film; a step of diffusing impurities into the substrate to form a second conductivity type diffusion layer and forming an oxide film on the exposed surface of the substrate; a step of diffusing the first conductivity type impurity into the substrate through the oxide film; The present invention includes a method for manufacturing a semiconductor device characterized by including a step of removing an impurity-containing film and a step of growing an epitaxial layer.

[Industrial Application Field] The present invention relates to diffusion of a buried collector in a semiconductor device and a method of forming a step for recognition of a buried collector layer.

[Conventional technology]

In manufacturing a semiconductor device, a buried collector layer and a step for recognizing the collector layer are formed in a semiconductor substrate. To explain this with reference to Figure 3,
As shown in FIG. 3A, an impurity-containing film 3 such as glass doped with arsenic, antimony, etc. is formed on a semiconductor substrate 31.
2. Sequentially grow a silicon dioxide (5i02) film 33.

Next, these films (31, 33) are patterned corresponding to the spread of the buried collector layer to be formed as shown in FIG.

Next, thermal oxidation and diffusion of impurities in the impurity-containing film 32 (
When drive-in is performed, a SiO2 film 35 is formed on the surface of the substrate, and an N+ type impurity diffusion layer 36 is formed in the semiconductor substrate.

Below, the island 34, the SiO+ film 34 are all 34, and the entire surface is covered again with 5
i02IQ and the island 5i02B'A for alignment for recognition of the collector layer to be formed.
Formed by patterning A, implanted with boron ions (B+) to form a P+ type diffusion layer for channel cut, and epitaxially grown single crystal silicon on the entire surface, a buried collector layer is formed under this epitaxially grown layer. It is formed.

[Problem that the invention seeks to solve]

By selectively diffusing the buried collector from the impurity-containing film using the method described above, forming a 5i02 step (island) for alignment, and forming the collector layer and channel cut layer apart, the Is breakdown voltage If we try to maintain this above a certain level, the process becomes longer and the number of masks increases.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method of forming a buried collector layer and a step for recognizing the buried collector layer using a simpler process by reducing the number of masks than the conventional method.

Means for Solving Problem C] The above problem is solved by the step of depositing a second conductivity type impurity-containing film and a film serving as a mask material on a first conductivity type semiconductor substrate;
a famous step of anisotropically etching the films deposited in the two layers to open a window through these films, and isotropically etching the surface of the semiconductor substrate through the window to form a recess in the substrate;
A step of diffusing the impurity contained in the impurity-containing film into the substrate to form a second conductivity type diffusion layer and forming an oxide film on the exposed surface of the substrate, a step of diffusing the first conductivity type impurity into the substrate through the oxide film, and a mask material. The present invention is solved by a method for manufacturing a semiconductor device characterized by including a step of removing a film, an oxide film, and an impurity-containing film, and a step of growing an epitaxial layer.

[Effect]

In the present invention, (1) an impurity-containing film is deposited on a semiconductor substrate, a 5-inch two-layer film is grown on the film by CVD, (2) the film is anisotropically etched, and then the semiconductor substrate is etched. (3) oxidize the exposed semiconductor substrate surface and at the same time diffuse impurities into the semiconductor substrate surface; (4) dope only the thinly oxidized region with impurities for channel cutting; (5) This method removes oxide films and impurity-containing films, and performs epitaxial growth after (6) oxidation, so a mask only needs to be used once, and the diffusion layer (
The alignment marks for recognition (collector layer) are formed by a self-alignment method.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments.

FIG. 1 shows a cross-sectional view of the process of an embodiment of the present invention.

Refer to FIG. 1(a): As in the conventional example, an impurity-containing film 12 is deposited on a P-type semiconductor (silicon) substrate 11 to a thickness of 1,000 to 1,500 wafers, and a mask material and a mask material are deposited thereon by CVD. SiO2 film 1
3 will grow to a total thickness of 1,300 to 4,000 people. A resist film 14 is formed on the 5i02 film 13 and patterned as shown by dotted lines in the figure.

Figure 1 (see BL: 5i02 film 13, impurity-containing film 12 by anisotropic etching)
Etch and open window 15. Resist film 14
The semiconductor substrate is uniformly etched using wet etching, for example, to form recesses 15 in the semiconductor substrate.
is formed, and then the resist film 14 is removed. By this isotropic etching, a part of the substrate below the impurity-containing film 12 is hollowed out and removed, so that the N''b layer and the P''b layer, which will be formed in a later step, will not collide. Moreover, when wet etching is used, the substrate surface is not damaged as in the case of dry etching, and there is an advantage that the epitaxial layer grown in a later step is not damaged.

FIG. 1 (See C1: When annealing is performed to drive-in the impurities in the impurity-containing film to the substrate surface, an N+ type wide diffusion layer N''b layer) 17 is formed on the surface layer of the semiconductor substrate 11, while A 5i02 film 18 is formed on the exposed surface of the substrate.In the next step, ions will be implanted through the 5iOz film 18, so if it is necessary to protect the substrate surface, S is added to the substrate surface.
A total of 18 iO2 films 18 are formed, and then drive-in is performed.

Refer to FIG. 1(d): When boron ions (B1) are implanted into all 18 of the SiO2 films 18 using the impurity-containing film 12.5i02 film 13 as a mask, B+ (as shown in the figure) is selectively implanted into all 18 of the SiO2 films 18. (schematically indicated by a broken line 19) is inserted.

Refer to FIG. 1(e): When the 5i02 film 13.1B and the impurity-containing film 12 are removed and the epitaxial layer 20 is grown, the epitaxial layer 2
A recess 21 corresponding to the recess 16 is formed on the surface of 0,
This recess 21 serves as an alignment mark for recognition of the N+ type wide diffusion layer (collector layer) 17. In addition, a P-type channel cut layer (P"b layer) 2 is formed in the part where B1 is ion-implanted.
2 is formed by heat during epitaxial growth.

In the above method, the mask is used only when patterning the resist film 14, making the process simpler than in the conventional method, and wet etching is used to form the recesses on the semiconductor substrate, so there is no damage to the substrate. Moreover, since the impurity-containing film is made of glass doped with inexpensive impurities, there is an advantage that the cost is reduced.

In another embodiment of the present invention, instead of using an impurity-containing film, impurity ions are implanted into the surface of the semiconductor substrate, and the steps include: +1) forming a buried collector layer (N"b) on the entire surface of the substrate; 800℃～
Perform low-temperature oxidation at 900°C, then etch the oxide film and substrate, (2) perform oxidation and N"b annealing to diffuse N"b, and if P+b for channel cut is required. After ion implantation of p''b and removal of the oxide film, epitaxial growth is performed.
Since the entire surface of the substrate is oxidized after the ``b'' ion implantation, no crystal defects occur during oxidation, and the N''b layer and the p''b layer do not come into contact with each other at a high concentration, so that the Is breakdown voltage is improved.

FIG. 2 shows the steps of this embodiment in cross section.

See Figure 2 fa): N-type impurities (arsenic) are added to the surface of the P-type silicon substrate 11.

Antimony, etc.) is ion-implanted at a high concentration. The ion-implanted N++ impurity is schematically indicated by a broken line 23 in the figure.

See Figure 2(b): The substrate surface is oxidized to form a 5i02 film 24, and the injected N
Incorporate + type impurities into 5iO211Q24.

The SiO+ film 24 serves as a mask material in the ion implantation described with reference to FIG. 2 (el).

Refer to FIG. 2(C): The 5iOz film 24 is patterned using a resist film (not shown), and the substrate 11 is etched by isotropic etching to form a recess 16 in the substrate. In addition, the mask is 1 here.
It is only used once. This recess has the effect of forming alignment marks and separating (shifting) the N''b layer and the P+6 layer.

FIG. 2 (see dl) A 5iOz film 18 is formed on the substrate surface by oxidation, and an N-type impurity contained in the 5i02 film 24 is diffused into the substrate surface by drive-in annealing to form an N''b layer 17.
form.

Figure 2 (see el: P-type impurity ions are implanted through the SiO2 film 18.

At this time, the SiO2 film 24 acts as a mask.

The implanted P-type impurity is schematically indicated by a broken line 19 in the figure.

See FIG. 2(f): When the SiO2 film (24, 18) is removed and the epitaxial layer 20 is grown, a recess 21 corresponding to the recess 16 is formed on the surface of the epitaxial layer, which is the same as in the embodiment of FIG. As in the case, the channel cut layer (P"b layer) 22 is formed in the substrate as an alignment mark.

In this embodiment, since the impurity-containing film of the first embodiment is formed by ion implantation of N+ type impurities, there is an advantage that controllability and reproducibility are improved.

〔Effect of the invention〕

As described above, according to the present invention, the mask only needs to be used once, the high concentration regions of the N''b layer and the P+6 layer do not collide, so the withstand voltage is improved, and the alignment marks do not induce crystal defects. It has the effect of being formed.

[Brief explanation of the drawing]

Figures 1(a) to (cl are sectional views of embodiments of the present invention, Figure 2+
a) to (f) are sectional views of other embodiments of the present invention, and FIG.
al~(0) is a sectional view of a conventional example. 1 and 2, 11 is a silicon substrate, 12 is an impurity-containing film, 13 is a 5iOz film, 14 is a resist film, 15 is a window, 16 is a recess, 17 is an N''b layer, 18 is a 5i02 film, 19 is a B+ ion, -20 is an epitaxial layer, 21 is a recess, 22 is a p''b layer, 23 is an N+ type impurity, and 24 is a 5i02 film. Patent Applicant Fujitsu Ltd. Representative Patent Attorney Akira Kukimoto 1 Tonu - 1, Takori ni Tsuya i4 E° 1 Cut C1] Mouth ≧ 1 1st
11 (Abandoned 8R invasion 5th example Zandome to 滌uta's A death bag JJ'l's Akishina prisoner Aimei's hard laugh 抛い 1 减切山耪 12 fig. Ehi J4! 'II piece ff 1 ε District] Figure 3

Claims (2)

[Claims] (1) A second conductivity type impurity-containing film (12) and a film serving as a mask material (13) on the first conductivity type semiconductor substrate (11)
a step of anisotropically etching the films deposited in the two layers to open a window (15) through these films, and isotropically etching the surface of the semiconductor substrate (11) through the window (15); The step of forming a recess (16) in the substrate, the step of forming the impurity-containing film (
12) is diffused into the substrate to form a second conductivity type diffusion layer (
17) and forming an oxide film (18) on the exposed surface of the substrate; a step of diffusing the first conductivity type impurity into the substrate through the oxide film (18); 18) A method for manufacturing a semiconductor device, comprising the steps of: removing the impurity-containing film (12); and growing an epitaxial layer (20). (2) Instead of the impurity-containing film (12) and the film (13) serving as a mask material, a mask material containing conductive impurities (23) provided on the surface of the semiconductor substrate (11) is used. A method according to claim 1.