JPH02119229A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To enhance a high-frequency characteristic of a lateral-type transistor and to realize a high density by a method wherein an emitter diffusion layer and a collector diffusion layer are formed by diffusing an impurity from polycrystalline silicon in order to prevent the impurity from being dispersed largely into a substrate and to prevent a base width from becoming wider than a maximum pattern of a mask. CONSTITUTION:An emitter region, a base region and a collector region E, B, C which have been arranged in a transverse direction on one main face of a semiconductor substrate 3 of a second conductivity type have respective recessed parts whose cross-sectional shape is nearly rectangular; polycrystalline silicon 6-1, 6-3, 6-2 as electrodes is filled into the recessed parts; the emitter region and the collector region E, C have individually an emitter diffusion layer and a collector diffusion layer 5-1, 5-2 formed by diffusing an impurity of a first conductivity type into the semiconductor substrate 3 from the polycrystalline silicon 6-1, 6-2 inside the respective recessed parts; junction faces of the diffusion layers 5-1, 5-2 opposite to each other are nearly parallel to each other; the base region B has a base contact layer 8 formed by diffusing an impurity of a second conductivity type into the semiconductor substrate 3 from the polycrystalline silicon 6-3 inside the recessed part.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lateral transistor device and an integrated circuit device in which a large number of these devices are integrated on the same semiconductor substrate.

2. Description of the Related Art As shown in FIG. 2, a conventional lateral transistor includes a second conductivity type semiconductor layer 3 on the entire surface of a first conductivity type semiconductor substrate 1 in which a second conductivity type buried region 2 is formed. An insulating film 4 is formed on the surface of the semiconductor layer 3, and recesses to become the emitter, base, and collector of the lateral transistor are formed by silicon etching using the insulating film 4 as a mask. An impurity of the first conductivity type is diffused into the region to become the collector, and an impurity of the second conductivity type is diffused to the region to become the base. form 8. Then, an AL electrode 7-1.7-2.7-3 is formed to cover the diffusion region.

Problems to be Solved by the Invention In the conventional structure, a high concentration of impurities is diffused directly into the semiconductor substrate, which inevitably causes the impurities to spread widely throughout the semiconductor substrate, which not only hinders high density. This increases the junction capacitance and improves the high frequency characteristics.Furthermore, since the electrodes ?-1 and 7-2 cover the recesses, they are smaller than the minimum pattern dimension a of the mask (see Figure 2). The fact that the base width is always wide has also been a problem in terms of increasing density and improving high frequency characteristics.

The present invention was attempted in view of the above-mentioned problems, and improves the high frequency characteristics of lateral transistors without causing impurities to spread significantly into the semiconductor substrate and without making the base width wider than the minimum pattern of the mask. It is an object of the present invention to provide a semiconductor device and a method for manufacturing the same that can realize improved performance and higher density.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a semiconductor device in which an emitter, a collector, and a base region are each disposed laterally on the whole surface of a second conductivity type semiconductor substrate. The emitter, base, and collector regions each have a recess whose cross-sectional shape is approximately rectangular, and polycrystalline silicon is embedded as an electrode in the recess. A structure in which the polycrystalline silicon in the recessed portion does not extend over a surface region of the semiconductor substrate sandwiched between the circuit portions of the emitter and collector regions, and An emitter and collector diffusion layer is formed by diffusing a first conductivity type impurity from polycrystalline silicon in the recess into the semiconductor substrate, and in a portion where the emitter and the collector region face each other, the emitter and the collector diffusion layer are substantially parallel to each other, and in the base region, a base contact layer is formed by diffusing a second conductivity type impurity from the polycrystalline silicon in the recess into the semiconductor substrate. This is a semiconductor device having a structure similar to that shown in FIG.

Operation As described above, in the present invention, the emitter and collector diffusion layers are formed by diffusing impurities from polycrystalline silicon, so even if the impurities are diffused in a high concentration, the emitter and collector diffusion layers are formed thickly (without spreading) in the semiconductor substrate. A diffusion layer, a collector diffusion layer, and a base contact layer can be formed.Furthermore, since the structure is such that polycrystalline silicon is buried in the recess as an electrode using the method described above, the base width can be formed using the minimum dimension of the mask. can.

Example A first example of the structure and manufacturing method of the present invention is described below.
This will be described along Figures A to D.

[A] A highly concentrated second conductive type semiconductor region 2 is provided on a first conductive type semiconductor substrate 1, a second conductive type semiconductor layer 3 is grown, and an insulating film 4 is further formed thereon.

[After forming emitter, base, and collector patterns on the Bco insulating film 4, the insulating layer M4 is etched according to the pattern, and then the second conductive type semiconductor layer 3 is etched.
to form the emitter, collector, and base regions. Then, polycrystalline silicon is deposited, and the polycrystalline silicon is buried in the recessed portions using an etch-back method, polishing, etc., and the polycrystalline silicon emitter electrode 6-1, the collector electrode 6-2, and the base electrode 6- are made of polycrystalline silicon.
form 3.

[The surface of the C collector polycrystalline silicon 6-3 is covered with a mask so that impurities of the first conductivity type are not introduced into the emitter polycrystalline silicon 6-1 and collector polycrystalline silicon 6-2. Impurities are introduced by ion implantation, solid phase diffusion, etc., and the impurities of the first conductivity type are diffused into the semiconductor layer 3 from the polycrystalline silicon to form an emitter diffusion layer 5-1 and a collector diffusion layer 5-2. . Next, the surfaces of the emitter and collector polycrystalline silicon 6-1, 8-2 are covered with a mask so that impurities of the second conductivity type are not introduced into the base polycrystalline silicon 6-3, and the second conductivity type impurities are introduced into the base polycrystalline silicon 6-3. is introduced by ion implantation, solid-phase diffusion, etc., and impurities of the second conductivity type are diffused into the semiconductor layer 3 from the polycrystalline silicon to form the base contact layer 8.

[D] Emitter, collector, base polycrystalline silicon 6-
1.6-2.6-3 After forming an insulating film on the surface, contacts are opened alternately as shown in the figure, and metal electrodes are formed on the emitter, collector, and base, respectively. (7-L
7-2.7-3) In this example, [in C, emitter diffusion layer 5-1, collector diffusion layer 5-2
When forming the base contact layer 8, the emitter and collector diffusion layers were formed first and then the base contact layer was formed, but it does not matter which one is formed first. Also,
CB], [C], polycrystalline silicon electrode 6
-1.8-2.6-3 is buried in the recess of the second conductivity type semiconductor layer 3, and then the first and second semiconductor layers are buried in the polycrystalline silicon.
Although the emitter diffusion layer 5-1, the collector diffusion layer 5-2, and the base contact layer 8 were formed by introducing conductivity type impurities, the polycrystalline silicon into which the first conductivity type impurities were introduced was used in the emitter and collector regions. Emitter diffusion layer 5-1, collector diffusion layer 5-2, and base contact layer 8 may be formed by embedding polycrystalline silicon into which second conductivity type impurities have been introduced into the base region.

Furthermore, [in Dco, when forming the metal electrode,
Although the electrodes were arranged alternately as shown in the figure,
The electrode arrangement may be such that (distance between the emitter recess and the collector recess) can be made the minimum dimension of the mask. moreover,
Before forming the metal electrode, a polycrystalline silicon electrode 6-1 or 6-2 is formed so that b can be the minimum dimension of the mask.
Alternatively, a new polycrystalline silicon electrode may be formed on 6-3 to serve as an extraction electrode, and then a metal electrode may be formed on the extraction electrode. Moreover, polycrystalline silicon electrode 6-1.
In at least one electrode of 6-2.6-3, the bottom surface or one or more side surfaces may be covered with an insulator.

Effects of the Invention As is clear from the above description, the present invention provides a semiconductor device in which an emitter, a collector, and a base region are each disposed laterally on the entire surface of a second conductivity type semiconductor substrate. The base and collector areas are
It has a recess whose cross-sectional shape is approximately rectangular, and polycrystalline silicon is embedded in the recess as an electrode,
The polycrystalline silicon in the recess in at least one of the emitter and collector regions does not extend over at least a surface region of the semiconductor substrate sandwiched between the recesses in the emitter and collector regions, The emitter and the collector regions have emitter and collector diffusion layers formed by diffusing a first conductivity type impurity into the semiconductor substrate from the polycrystalline silicon in the respective recesses, and the emitter and the collector regions In the opposing portions, the bonding surfaces of the diffusion layers of the emitter and the collector are substantially parallel to each other, and in the base region, impurities of the second conductivity type are diffused into the semiconductor substrate from the polycrystalline silicon in the recess. Since the structure has a base contact layer formed using a polycrystalline silicon, impurities are diffused from the polycrystalline silicon into the semiconductor substrate. Emitter diffusion layer, collector diffusion layer,
A base contact layer can be formed. moreover,
Since the structure is such that polycrystalline silicon is used as an electrode and is buried in the recess by the method described above, the base width can be formed using the minimum dimension of the mask.

Therefore, the present invention has the following effects.

First of all, the emitter diffusion layer, collector diffusion layer, and base contact layer can be formed without spreading widely in the semiconductor substrate, making it suitable for extremely high density, and the emitter-base capacitance and collector-base capacitance are small. This also leads to improved high frequency characteristics. Furthermore, since the emitter diffusion layer and the collector diffusion layer are substantially parallel to each other, the opposing area can be further increased, and a high current amplification factor can be obtained. Second, since the base width can be formed with the minimum dimension of the mask, the base width can be made thinner than in the past, resulting in a higher current amplification factor and improved high frequency characteristics.

As described above, the practical effects of the present invention are significant.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the manufacturing process of an embodiment of the present invention, and FIG. 2 is a sectional structural view of a conventional semiconductor device. DESCRIPTION OF SYMBOLS 1...1st conductivity type semiconductor substrate, 2.Φ.2nd conductivity type semiconductor region, 3.PHI..2nd conductivity type semiconductor substrate, 4..Insulating film, 5-1..Emitter diffusion layer, 5- 2. Fist Φ Collector diffusion ff, 8-1φ... Emitter polycrystalline silicon electrode, 6-2... Collector polycrystalline silicon electrode, 6-3.
...Base polycrystalline silicon electrode, 7-1.7-2.7-
3... Metal electrode, 8... Fist base contact layer. Name of agent: Patent attorney Shigetaka Kurino

Claims (2)

[Claims] (1) On one main surface of the second conductivity type semiconductor substrate, an emitter,
In a semiconductor device in which a collector region and a base region are arranged in a horizontal direction, each of the emitter region, the base region, and the collector region has a recessed portion whose cross section is approximately rectangular, and polycrystalline silicon is disposed within the recessed portion. Polycrystalline silicon embedded as an electrode in the recess in at least one of the emitter and collector regions,
At least a structure that does not extend over a surface region of the semiconductor substrate sandwiched between the recesses of the emitter and collector regions, and in the emitter and collector regions, a first conductivity type is formed from the polycrystalline silicon in the respective recesses. It has an emitter and a collector diffusion layer formed by diffusing impurities into the semiconductor substrate, and in a portion where the emitter and the collector region face each other, the bonding surfaces of the emitter and the collector diffusion layers are substantially mutual to each other. A semiconductor device comprising a base contact layer which is parallel to the semiconductor substrate and is formed by diffusing a second conductivity type impurity from polycrystalline silicon in the recess into the semiconductor substrate in the base region. (2) A step of simultaneously providing recesses to serve as emitter, collector, and base regions on one main surface of the second conductivity type semiconductor substrate so that the cross-sectional shape thereof is approximately rectangular, and forming polycrystalline silicon in the recesses to form electrodes The polycrystalline silicon in the recess in at least one of the emitter and collector regions does not extend over at least a surface region of the semiconductor substrate sandwiched between the recesses in the emitter and collector regions. burying polycrystalline silicon in the recess, diffusing impurities of a first conductivity type from the polycrystalline silicon in the emitter region and the collector region into the semiconductor substrate, and simultaneously burying the emitter and collector diffusion layers; forming the diffusion layer so that the bonding surfaces of the diffusion layers of the emitter and collector are substantially parallel to each other in a portion where the emitter and collector regions face each other; A method for manufacturing a semiconductor device, comprising at least the step of diffusing a second conductivity type impurity from polycrystalline silicon in a recessed portion of a base region into the semiconductor substrate to form a base contact layer.