JPS6351674A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form buried layers of different concentration in one process, consisting of ion implantation and diffusion accomplished in succession, by a method wherein a substrate is covered on its surface with a thin oxide film, the thin oxide film is locally removed, and then a polycrystalline silicon layer is formed thereon. CONSTITUTION:An N-type diffusion layer 15 is formed on a P-type substrate 14, an oxide film 16 is formed, a portion is removed from the oxide film 16 for the formation of a P-type diffusion layer, and then a thin oxide film 17 is formed. Next, a portion for the formation of an insulating layer and P-N-P transistor collector buried layer is removed from the thin oxide film 17, and then a polycrystalline silicon layer 18 is grown. A process follows wherein boron ions are implanted, diffused, and high- concentration drive-in is accomplished, after which the polycrystalline silicon layer 18 is subjected to oxidation. After the removal of the entire oxide film, there are a high-concentration buried layer 19 and low-concentration buried layer 20. An epitaxial growth process is accomplished, which results in a high-concentration P-type buried layer 19 and low-concentration P-type buried layer 20. After this, an insulating layer and collector 22 are formed simultaneously, and then a P-N-P transistor emitter 23 and base contact 24 are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device in which buried layers having different degrees of d1 are formed in a single process.

[Conventional technology]

Conventionally, in order to form buried layers with different concentrations, a buried layer with a low concentration is first formed, and then a buried layer with a high concentration is formed in separate steps.

[Problem that the invention seeks to solve]

The above-described conventional manufacturing method has the disadvantage that the steps are long because they are formed separately.

In the conventional manufacturing method described above, the buried J- with different concentrations was formed in separate steps, whereas the present invention leaves a thin oxide g ,
The oxide film is removed from areas where a buried layer with high concentration will be formed.
The originality of this method is that it is a method for manufacturing a semiconductor device in which buried layers with different concentrations can be formed by forming polysilicon on the entire surface and successively performing ion implantation and diffusion.

[Means for solving problems]

The present invention forms buried layers with different concentrations in a single process by forming polysilicon after forming areas where a thin oxide film is left and areas where the oxide film is removed. This is a method of manufacturing a semiconductor device that can be performed.

〔Example〕

Next, a manufacturing method of the present invention will be explained with reference to the drawings. FIG. 1 is a longitudinal sectional view of Example 1 of the present invention.

After forming the oxide film 2 on the P-type substrate 1, photolithography is used to remove the oxide film 2 in the part where the buried layer will be formed.
After removing the resist, a thin oxide film 3 of, for example, 100A is formed, and after removing the oxide film 3 at the negative part, for example, the part where the buried layer of the collector of the NPN transistor is to be formed, by photolithography. , the resist 3 is removed.

[FIG. 1(a)] After this, after growing polysilicon to, for example, 700A,
E=70KeV, Φ=5X1015cm so that phosphorus enters the plate of P-type N-type impurity.
After ion implantation, phosphorus diffusion is performed. [Figure 1 (b)
] Thereafter, when the phosphorus is pressed at a high temperature, phosphorus is diffused into the polysilicon on the thin oxide film 3 and is prevented from being diffused into the P-type substrate 1, which is prevented by the thin oxide film 3. After this,
When polysilicon is oxidized and the oxide film is completely removed, P
A heavily doped N-type impurity layer 5 and a lightly doped N-type impurity layer 6 are formed in a mold substrate 1 . FIG. 1(C) Thereafter, by epitaxial growth, a heavily doped N-type buried layer 5 and a lightly doped N-type buried layer 6 are formed. Figure 1 (d
) After that, if collector rinsing 9 is performed using the oxide film as a mask, the collector rinsing 9 will form a highly concentrated N-type buried layer 5 at a low temperature.
You can contact with. Thereafter, the base 10, emitter 12, and collector contact 11 are formed, but since the buried layer 6 with a low concentration is directly under the base 10, the rise of the buried layer 6 is small even if the epitaxial thickness is small, and the base The epitaxial thickness immediately below can be increased, and the withstand voltage of the NPN transistor can be increased. FIG. 1(e) and FIG. 2 are longitudinal cross-sectional views of a second embodiment of the present invention.

An N-type diffusion/1i 15 is formed on the P-type substrate 14. FIG. 2 (al) After this, after forming the oxide film 16, the oxide film in the part where the P-type diffusion layer will be formed is removed by photolithography.
A thin oxide film 17 is formed. Thereafter, the thin oxide film on the part where the insulating layer is to be formed and the part where the buried layer of the collector of the PNP transistor is to be formed is removed, and the entire polysilicon 18 is grown. [FIG. 2(b)] After this, ions of a P-type impurity such as boron are implanted into the silicon, and then boron is diffused. After oxidizing the polysilicon 18 which has been indented with a high eyelid, the oxide film is completely removed to form a high concentration embedment r-Jl 9 and a low concentration embedment /1520. FIG. 2 (C1) After this, when epitaxial growth is performed, a high-concentration P-type buried layer 19 and a low-concentration P-type buried layer 20 are formed. to form PNP
Emitter 23 and base contact 24 of the transistor
form. [Fig. 1(e)] The buried M+i 19 directly under the collector 22 has a high concentration, and the buried layer 20 directly under the emitter 23 has a low concentration, so even if the epitaxial thickness is thin, the pace width of the PNP transistor can be secured. , and has the advantage of being able to provide insulation through low-temperature heat treatment.

〔Effect of the invention〕

As explained above, in the present invention, a portion where a thin oxide film is formed and a tube portion from which the oxide film is removed are formed on the same substrate, and polysilicon is formed on this, so that ion implantation and diffusion are continued. By doing so, it is possible to form buried layers with different concentrations in a single process.

[Brief explanation of the drawing]

FIGS. 1A to 1E are longitudinal sectional views of Example 1 of the present invention, and FIGS. 2A to 2E are longitudinal sectional views of Example 2. 1.14...・P type substrate, 2, 3,
13゜16.47.25...Oxide film, 4,18
...Polysilicon, 5, 6.15...N-type buried layer, 7,21...N-type epitaxial layer,
8.10,22,23・°°...P diffused layer, 9,1
1, 12.24...N-type diffusion layer, 19.20
...P-type buried layer.ゝ、Representative Patent Attorney Yu Uchihara "Town Figure 1 Figure 2 Figure ζ

Claims (1)

[Claims] A step of forming an oxide film on a semiconductor substrate, a step of removing the oxide film, a step of forming a thin oxide film, a step of removing a part of the thin oxide film, a step of growing polysilicon, and an impurity A method for manufacturing a semiconductor device, comprising the steps of ion-implanting and diffusing polysilicon, oxidizing the polysilicon, and epitaxially growing the polysilicon after removing the oxide film.