JPH0622263B2 - Method for manufacturing semiconductor substrate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor substrate, and more particularly to a method for manufacturing a semiconductor substrate using a dielectric isolation method using selective epitaxial growth.

[Conventional technology]

Conventionally, in this type of semiconductor substrate manufacturing method, the P ^{+ type} channel stopper 302 is formed under the insulating oxide film 303 as shown in FIG. 3, but it can be bonded to the N ^{+ type} buried layer 306. In order to prevent the capacity from increasing and the frequency characteristics to deteriorate, the margin 311 is taken into consideration in consideration of misalignment and lateral spread of diffusion.

[Problems to be solved by the invention]

In the above-mentioned conventional method for manufacturing a semiconductor substrate, in order to prevent the capacitance from increasing and the frequency characteristics from deteriorating due to the junction between the P ^{+ type} channel stopper and the N ^{+ type} buried layer, misalignment, lateral spread, etc. Since the margin is taken into consideration, there is a drawback that the element size becomes large.

The characteristics of the dielectric isolation method are high integration and high speed due to capacitance reduction. However, when the conventional method is used, no significant improvement can be expected in terms of high integration and capacitance reduction.

In contrast to the conventional method of forming a P ^{+ type} channel stopper and an N ^{+ type} buried layer in the dielectric isolation method using selective epitaxial growth, the present invention self-aligns the P ^{+ type} channel stopper and the N ^{+ type} buried layer. To form with P
There is an advantage that it is not necessary to take a margin between the ⁺ channel stopper and the N ^{+ type} buried layer, the element size can be reduced, and further, the junction capacitance can be reduced to increase the speed.

[Means for solving problems]

A method of manufacturing a semiconductor substrate of the present invention comprises a step of forming a high-concentration layer on the surface of a semiconductor substrate of the first conductivity type with the same conductivity type as that of the semiconductor substrate and further forming an insulator, and forming the insulator into a semiconductor element. Selectively removing only a region to be formed and further removing a part of the semiconductor substrate by penetrating the high concentration layer in the region, and each of the insulator, the high concentration layer and a part of the semiconductor substrate. And selectively forming an epitaxial layer having a conductivity type opposite to that of the first conductivity type only in the region where is removed.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 (a), (b), and (c) are vertical cross-sectional views showing the steps of the first embodiment of the present invention.

Reference numeral 101 is a P ^{− type} semiconductor substrate, and an insulating oxide film 103 is formed on this semiconductor substrate to a thickness of about 1 to 2 μm. At this time, P
P between the ^{− type} semiconductor substrate 101 and the insulating oxide film 103
^{A + type} channel stopper 102 is formed (FIG. 1 (a)).

Then, dry etching is performed using the photoresist as a mask to selectively remove the insulating oxide film 103, P ^{+ -type} channel stopper 102, and P ^{− -type} semiconductor substrate 101 (a part thereof) to form a hole 104 (first). Figure 1 (b)).

After that, a semiconductor substrate is formed by selectively growing the N-type epitaxial layer 105 only in the holes 104 (FIG. 1 (c)).

2 (a), (b), and (c) are vertical sectional views showing steps of the second embodiment of the present invention.

The hole 204 is formed by the same process as that of the first embodiment (FIGS. 2A and 2B).

After that, N-type epitaxial growth is selectively performed in the holes 204, but the N-type epitaxial layer 205 is used for the purpose of lowering the collector resistance when the NPN transistor is formed.
And 207, an N ^{+ -type} buried layer 206 is formed (FIG. 2 (c)). The N ^{+ -type} buried layer 206 can be formed by growing the N-type epitaxial layer 205 and then introducing an N-type impurity at a high concentration, and the amount of the impurity introduced can be controlled during the formation of the N-type epitaxial layer. It is also possible to do

FIG. 4 is a vertical sectional view of an application example in which an NPN transistor is formed by using the second embodiment. N in FIG. 2 (c)
The P type base layer 408, N ⁺
Forming a shaped collector layer 410, ^{N +} -type emitter layer 409 constituting the NPN transistor.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to form a high-concentration channel stopper of the first conductivity type without any limitation. Since it is not necessary to obtain a margin, there is an effect that the speed of the transistor can be increased by reducing the size of the element and reducing the capacity.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a process of Example 1 of the present invention,
FIG. 3 is a vertical cross-sectional view showing a process of Embodiment 2 of the present invention, FIG. 3 is a vertical cross-sectional view of a structural example by a conventional semiconductor substrate manufacturing method,
FIG. 4 is a vertical cross-sectional view of the structure of an application example of the present invention. 101,201,301 ...... P ^- type semiconductor substrate, 10
1,202,302 ... P ^{+ type} channel stopper, 1
03, 203, 303 ... Insulating oxide film, 104, 20
4 ... Hall, 105,205,207,307 ... N
-Type epitaxial layer, 206, 306 ... N ^{+ -type} buried layer, 308, 408 ... P-type base layer, 309, 409
... N ^{+ type} emitter layer, 310, 410 ... N ^{+ type} collector layer.

Claims (1)

[Claims] 1. A step of forming a high-concentration layer on the surface of a semiconductor substrate of the first conductivity type with the same conductivity type as that of the semiconductor substrate and further forming an insulator, and selecting this insulator only in a region where a semiconductor element is formed. And further removing a part of the semiconductor substrate by penetrating the high concentration layer in the region, and the region in which the insulator, the high concentration layer and a part of the semiconductor substrate are removed, respectively. And a step of selectively forming an epitaxial layer having a conductivity type opposite to that of the first conductivity type, the method for manufacturing a semiconductor substrate.