JPS60105224A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain uniform impurity diffusion region through simplification of impurity coating (solid phase-solid phase) diffusion process and prevention of exfoliation of impurity coated layer by hot diffusion of impurity after forming a mask which prevents external diffusion of impurity on a semiconductor substrate having diffusion source layer pattern. CONSTITUTION:The Sb2O3 layer patterns 2a, 2b having the shape corresponding to the pattern shape of buried diffusion region are formed on a P type Si substrate and the SiO2 layer 3 is then formed thereon by the CVD method. This CVD-SiO2 film 3 presses the Sb2O3 layer patterns 2a, 2b which are the impurity diffusion sources to the substrate surface, preventing exfoliation (floating) of Sb2O3 layer patterns 2a, 2b from the surface of Si substrate 1 by the hot diffusion process. Moreover, this SiO2 film has the function as the mask which suppresses external diffusion of impurity and prevents auto-doping of impurity to the region except the region where diffused region may be formed. The material is then heated under the mixed gas ambient of O2 and N2. Thereby, Sb is hot diffused into the P type Si substrate 1 from the Sb2O3 layer patterns 2a, 2b and the N<+> type buried duffusion regions 4a, 4b are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming an impurity diffusion region by solid phase-solid phase diffusion.

fb) Conventional technology and problems For example, in the manufacturing process of bipolar ICs, - When forming high impurity diffusion regions such as buried diffusion regions 9 isolation diffusion regions in a semiconductor substrate, the solid phase-solid phase diffusion method is used. is used.

When forming an impurity diffusion region such as the above-mentioned buried diffusion region 1 separation diffusion region in a semiconductor substrate using the conventional solid phase-solid phase diffusion method, for example, a thickness of 0.5 mm is formed on the semiconductor substrate surface to block impurities. A semiconductor substrate having the thermally oxidized film is formed by forming a thermally oxidized film of about 4 to 0.5 [μm], forming openings corresponding to the planar pattern of the diffusion region to be formed in the thermally oxidized film. An impurity diffusion source layer (for n-type, antimony oxide 5btQ, l5 phosphorus oxide P, 0.0, etc., for p-type, boron oxide B, 0.0, boron nitride BN, etc.) is coated and formed on top. The substrate was heated for 100 minutes in an inert atmosphere such as nitrogen.
A method of selectively diffusing impurities from the impurity diffusion source layer into the semiconductor substrate through the openings in the impurity oxide film by heating at a temperature of about 0 to 1300 degrees Celsius for a certain period of time. was being carried out.

However, in this method, if the sides of the openings in the impurity blocking oxide film are formed steeply,
Rei 100 Hers is lazy W l-ri τ-ka tomo l silent lγ
A problem arises in that the 7 & 7 impurity diffusion source layer peels off and the impurity 0 degrees in the diffusion region becomes non-uniform.

Therefore, in the past, a so-called selective oxidation method was used to selectively thermally oxidize the semiconductor substrate surface using an oxidation-resistant film (usually a silicon nitride film as a mask) to form a block film with tapered openings on the sides. This prevents the impurity diffusion source layer from peeling off, making the process extremely complicated.

(C) Purpose of the Invention The present invention has been made for the purpose of simplifying the impurity coating (solid phase-solid phase) diffusion process and preventing peeling of the impurity coating layer to obtain a uniform impurity diffusion region.

(di) Structure of the Invention That is, the present invention is a method for manufacturing a semiconductor device, in which when forming an impurity diffusion region, an impurity diffusion source layer pattern corresponding to the planar shape of the diffusion region is formed on a semiconductor substrate, and the diffusion source is The present invention is characterized by a step of forming a mask for preventing outward diffusion of impurities on a semiconductor substrate having a layer pattern, and then thermally diffusing impurities from the diffusion source layer pattern into the semiconductor substrate.

(e) Embodiment of the Invention An embodiment of the present invention will be described in detail below using process cross-sectional views shown in FIGS. 1 to 8.

Note that the same parts in these figures are indicated by the same symbols.

For example, an npn type bipolar IC can be manufactured using the method of the present invention.
For example, as shown in FIG.
P-type silicon (
For example, an antimony oxide (SL) 2 (Ja) layer, which is an n-type impurity diffusion source, with a thickness of about 0.2 [μm] is formed on the S-based substrate 1 by a coating method such as a spin code method, and then by a normal glue lithography technique. Selective etching is performed to form layer patterns 5b2o, layer patterns 2a, 2b, etc. having a shape corresponding to the pattern shape of the buried diffusion region on the p-type S1 substrate 1.

Next, as shown in FIG. 2, the above S b, U, J-
Patterns 2a and 2b are formed on a Si substrate 1 with a thickness of 0.3 [μm] using a normal chemical vapor deposition (CVD) method.
For example, a silicon dioxide (SiC) film 3 is formed to a certain extent. This CVI)-8 inch, film 3 is formed by pressing the sb, o, 3 layer patterns 2a, 2b, etc., which are impurity diffusion sources, onto the substrate surface, and applying the thermal diffusion process to the sb, o, layer patterns 2a, 2, etc.
Prevents peeling (lifting) from one surface of the Si substrate such as b, suppresses outward diffusion of impurities, and at the same time prevents impurities from being auto-doped in regions other than where the diffusion region is intended to be formed. It has a mask function.

Next, the above substrate is subjected to a heating process, for example: Nitrogen (N2) = 2
:10 in a mixed gas at a temperature of about 1250C) for a predetermined period of time to thermally diffuse sb from the sb, o, layer patterns 2a, 2b, etc. into the p-type Si substrate 1, as shown in FIG. For example, 1o20 (atm/
(n with a surface concentration of about +j3 and a depth of about 3 [μm]
Green mold buried diffusion regions 4a, 4b, etc. are formed.

Then, cVD-
8i0. The film 3, sb, o, layer patterns 2a, 2b, etc. are removed, and a p-type Sl plate 1 having n-type buried diffusion regions 4a, 4b selectively on the surface is formed as shown in FIG. Ru. As mentioned above, due to the function of the mask film, 5b2o,
Since the layer patterns 2a, 2b, etc. are prevented from peeling off, the n-type buried diffusion regions 4a, 4b, etc., which are distributed over the entire substrate surface, are all formed to have a uniform surface impurity concentration.
Moreover, auto-doping in areas other than the buried diffusion region is also prevented.

Next, as shown in FIG. 5, the buried diffusion layer 4a is formed.

On the p-type Si substrate 1 on which 4b, etc. are formed, an .
A type 8i epitaxial layer 5 is formed, and then a p-type epitaxial layer 5 having a shape corresponding to the pattern of the isolation diffusion region and having a thickness of about 0.2 Cμm is formed on the epitaxial layer 5 in the same manner as described above. Impurity diffusion source layer patterns (for example, boron oxide CBxO5) layer patterns 5a, (5b, 6c, etc.) are formed, and on the substrate having the B, 06 layer patterns 6a, 6b, 6c, etc., a thickness of about 03 [μm] is formed. CVD-8io,
A film 7 is formed.

Next, the above substrate is heated for a predetermined time at about 1100 ('C) in a mixture of Ot:N, = 2:10, and B,
B is diffused from O, layers 6b, 5c, etc. into the epitaxial layer 5, and as shown in FIG.
, 8b, 8c, etc. are formed. In this case as well, C'VI)-
8iU, due to the action of film 7, B2011 layer pattern 6a
.

Separation diffusion regions 8 ar 8 b+ 8 c and the like having a uniform impurity concentration are prevented from peeling off, and auto-doping of B into other regions is also prevented.

Next, CVD-etching is performed using normal wet etching treatment.
8iU, membrane 7 and B, 05 layer butter 76 a r 6
ba60 etc. are removed, and a nm5
1: An r-bitaxial layer 5 is formed, and the epitaxial layer 5 has p→ type isolation diffusion regions 8a, 9b, 8c.
A substrate to be processed separated into a plurality of transistor forming regions 9a, 9b, etc. is formed by the above steps.

Next, as shown in FIG. 8, each transistor formation region is filled with n+
Mold collector contact region 10a.

10b, etc., pfM heath regions 11a, llb, etc., n→ type emitter regions 12a, 12b, etc. are sequentially formed, and thereafter, although not shown, an insulating film is formed, an electrode contact BB is formed, a wiring layer is formed, etc., and the bipolar IC is completed. do.

As shown in the above embodiments, the method of the present invention is particularly used when forming a buried diffusion region or a separate diffusion region in a bipolar IC, but it can also be used for solid phase-solid phase diffusion in diffusion regions other than those mentioned above. Of course, 0 is also applied when forming by.

(Effects of the Invention As explained above with reference to the embodiments, the method of the present invention is to apply a substance that serves as a diffusion source for impurities on a semiconductor substrate, and to spread the impurity from the diffusion source into the semiconductor substrate. When selectively diffusing impurities, there is no need to form a blocking film on the semiconductor substrate surface through a complicated process, and the diffusion source is prevented from peeling off, resulting in a uniform impurity concentration over the entire substrate surface. It is possible to disperse and form diffusion regions having the following characteristics, and auto-doping of impurities to the substrate surface other than the diffusion regions is also prevented.

Therefore, the present invention aims to improve the quality and manufacturing yield of semiconductor integrated circuit devices such as bipolar ICs, and to shorten the manufacturing process.
It is effective against

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 8 are process cross-sectional views in one embodiment of the present invention. In the figure, 1 is a p-type silicon substrate, 2a and 12b are antimony oxide layer patterns, 3 and 7 are chemical vapor deposition triposition silicon films, 4a and 4b are mouth-to-type buried diffusion regions, and 5 is n-type silicon. -Epitaxial L 6a. 6b and 5c are boron oxide layer patterns, and 8a18b and 8C are p→ type isolation diffusion regions. Figure 1 Figure 2 Figure 3 Leap 4Z Figure S Figure 77 Factor g

Claims (1)

[Claims] An impurity diffusion source layer pattern corresponding to the planar shape of the diffusion region is formed on a semiconductor substrate, and a mask film for preventing outward diffusion of impurities is formed on the semiconductor substrate having the diffusion source layer pattern. 1. A method of manufacturing a semiconductor device, comprising the step of thermally diffusing impurities from a diffusion source layer pattern into the semiconductor substrate.