JPH1154520A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device such as a bipolar transistor which can be effectively applied to a sound circuit, and to provide a manufacturing method of the semiconductor device. SOLUTION: A polycrystalline silicon base electrode layer 15 is formed on the surface of the semiconductor substrate 11, excluding an emitter region, where an element formation region is provided using a LOCOS oxide film 12. The base electrode layer 15 is covered by a first insulating layer 16 in such a manner that the surface and the side face of the layer 15 are surrounded by perforating an aperture on the emitter region, and an aperture part 114 is formed by isotropic etching the semiconductor substrate 11 using the first insulating layer 16 as a mask. A base layer 13 is formed in the aperture part 114 by performing an epitaxial growth method, and besides, an emitter layer 14 is formed by epitaxial growth. To be more precise, as a prescribed base layer 13 and an emitter layer 14 are formed by the epitaxial growth in a self- matching manner, a burst noise free bipolar transistor can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device which is a high-precision analog bipolar transistor used in, for example, an acoustic system and a method of manufacturing the same.

[0002]

2. Description of the Related Art Hitherto, bipolar transistors have been used in acoustic circuits. In a semiconductor device used in an audio system having such a high-precision analog bipolar analog circuit, the generation of burst noise is suppressed as much as possible. Is required.

In forming a bipolar transistor, a commonly used ion implantation technique is employed as a means for introducing impurities for forming an emitter and a base region and the like. When such an ion implantation technique is used for forming the emitter and base regions, it has a feature that the reproducibility of the implantation amount of the impurity is good, so that the accuracy of the semiconductor element characteristics is improved. Is valid. However, due to the ion implantation damage caused by the ion implantation, burst noise is generated,
This is a major problem when used in audio systems.

On the other hand, it is conceivable to form a diffusion layer of a predetermined impurity using a solid phase diffusion method in order to form the emitter and base regions. However, when such a solid-phase diffusion method is used, the generation of burst noise can be surely suppressed, but the concentration of the solid-phase diffusion source has a large variation, and the interface state with the semiconductor substrate is increased. Causes a large variation in the impurity concentration of the emitter and base regions after the heat treatment, which leads to deterioration in the variation in the characteristics of the semiconductor element.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and can be effectively applied to an acoustic bipolar circuit, in particular, in such a manner that the occurrence of burst noise is reliably suppressed. An object of the present invention is to provide a semiconductor device which is a bipolar transistor and a method for manufacturing the same.

[0006]

In a semiconductor device according to the present invention, a base layer of a first conductivity type is formed on a semiconductor substrate, and an emitter layer of a second conductivity type is formed in the base layer. A base electrode layer is formed on the surface of the semiconductor substrate corresponding to the base layer, and a first insulating layer is formed so as to protect the surface and the side surface of the base electrode layer.
Here, the base layer and the emitter layer are composed of an epitaxially grown layer formed in an opening by etching on the surface of the semiconductor substrate, and are formed by diffusing first and second impurities into the epitaxially grown layer.

In the method of manufacturing a semiconductor device, a base electrode layer is formed on a surface of a semiconductor substrate with a conductive material, and a surface portion and a side portion of the base electrode are covered, and an opening is formed corresponding to the emitter layer. The formed first insulating layer is formed. An opening is formed in the semiconductor substrate by using an opening corresponding to the emitter layer of the first insulating layer, and a base layer of the first conductivity type is formed in the opening by epitaxial growth. An emitter layer of the second conductivity type is formed inside the base layer by epitaxial growth corresponding to the surface of the semiconductor substrate, and the first insulating layer covers a base electrode layer connected to the base layer. Further, it is used as a mask in an etching process of a semiconductor substrate for forming a base region.

That is, in the semiconductor device manufactured as described above, since the base layer and the emitter layer are both formed by epitaxial growth, there is no influence of damage due to ion implantation. In addition to being free from burst noise, arbitrary base and emitter profiles can be formed, and element characteristics can be controlled with higher precision than in the solid phase diffusion method. Furthermore, since the base and the emitter can be formed in a self-aligned manner using the first insulating layer as a mask, the effect of reducing the size of the element can be exhibited, and a small and highly reliable semiconductor device can be easily obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a cross-sectional structure of the semiconductor device, in which an n ⁺ -type buried layer 112 is formed on the surface of a p-type silicon substrate 111, and an n-type epitaxial growth layer 113 is further formed on the surface. The semiconductor substrate 11 is constituted by the above. An element formation region is set on the surface of the semiconductor substrate 11 so as to be surrounded by the LOCOS oxide film 12, and a p-type base layer 13 of an epitaxial growth layer is formed at the center of the element formation region. An emitter layer 14 is also formed at the center of the layer 13 by epitaxial growth.

The surface of the semiconductor substrate 11 on which the base layer 13 and the emitter layer 14 are formed is connected to the base layer 13 on the side surface thereof, and an electrode is formed on the base of polycrystalline silicon. A layer 15 is formed, and the surface and side surfaces of the base electrode layer 15 are covered with a first insulating layer 16.

The surface of the semiconductor substrate 11 on which the base layer 13 and the emitter layer 14 are formed and the base electrode layer 15 covered with the first insulating layer 16 is formed is a protective insulating layer.
Derivation electrodes 18 and 19 which are covered with 17 and penetrate through the insulating layer 17 to reach the base electrode layer 15 and the emitter layer 14 are formed.
Although not shown in this figure, the collector electrode is led out so as to be connected to the buried layer 112 of the semiconductor substrate 11.

Here, the base layer 13 and the emitter layer 14
Are formed as epitaxial growth layers containing predetermined impurities in openings formed by etching on the surface of the semiconductor substrate 11 using the first insulating layer 16 as a mask. And is basically free of burst noise without being generated, and is effective when used in a sound circuit. Further, an arbitrary base / emitter profile can be formed, and element characteristics can be controlled with high accuracy.

FIG. 2 shows a sectional structure of a semiconductor device according to a second embodiment. In this embodiment, a second insulating layer 20 is provided between a base electrode layer 15 and a semiconductor substrate. Is formed. The second insulating layer 20 forms a junction capacitance between the base layer 13 and the emitter layer 14, and thus enables a high-speed operation of the semiconductor device (bilateral transistor).

Further, as shown in a third embodiment shown in FIG. 3, a base layer is provided between the base electrode layer 15 and the semiconductor substrate.
A diffusion layer 21 of a p-type impurity having the same conductivity type as that of 13 is formed. By forming the diffusion layer 21 in this manner, the base resistance can be effectively reduced, high-speed operation can be performed and high-frequency noise can be reduced, and it can be effectively applied to sound.

FIG. 4 shows, for example, the manufacturing steps of the semiconductor device according to the first embodiment shown in FIG. 1 in sequence. First, as shown in FIG. The semiconductor substrate 11 is formed by forming the layer 112 and further forming the epitaxial growth layer 113. An element isolation region is set on the surface of the semiconductor substrate 11 by the LOCOS oxide film 12, and a region surrounded by the LOCOS oxide film 12 is an element formation region. Leaving the base region portion of
A base electrode layer 15 of a polycrystalline silicon layer is formed on the OCOS oxide film 12.

Next, as shown in FIG. 1B, a first insulating layer 16 made of, for example, silicon nitride is formed so as to cover the surface and side surfaces of the base electrode layer 15 made of polycrystalline silicon. The first insulating layer 16 is formed so as to also serve as a mask used in a later step. That is, an opening 161 is formed corresponding to the emitter region in the base region.

Then, as shown in FIG. 2C, the semiconductor substrate 1 is passed through the opening 161 using the first insulating layer 16 as a mask.
The surface of 1 is isotropically etched to form an opening 114. The opening 114 serves as a base and emitter forming portion. As shown in FIG. 3D, a p-type base layer 13 is formed inside the opening 114 by an epitaxial growth method.
And an n-type emitter layer 14 is formed by the epitaxial growth method.

Here, the base layer thus formed
Reference numeral 14 denotes a state in which the insulating layer 17 is electrically connected to the base electrode layer 15 made of polycrystalline silicon which has already been formed. Is formed. Then, if necessary, this insulating layer
An opening extending to the base electrode layer 15 and the emitter layer 14 is formed in the opening 17 and a conductive material such as aluminum is buried in the opening, so that the lead-out electrodes 18 and 17 shown in FIG.
19 are formed to complete the bipolar transistor.

That is, by manufacturing a bipolar transistor by such a manufacturing method, the base layer 13 is formed.
In addition, the emitter layer 14 is formed in a self-aligned manner with respect to the opening 161 of the first insulating layer 16, which is effective in reducing the size of the element, and is particularly effective in manufacturing a high-frequency bipolar transistor. When the base layer 13 and the emitter layer 14 are successively formed by selective epitaxial growth, variations in device characteristics due to interface instability between the substrate and the substrate, which has been a problem in the conventional polyemitter process, do not occur. Further, since there is no particularly complicated process, it is effective in reducing the number of manufacturing steps.

[0020]

As described above, according to the semiconductor device and the method of manufacturing the same according to the present invention, since both the base layer and the emitter layer are formed by a continuous epitaxial growth method, the present invention is applicable to acoustic devices and the like. In this case, it is possible to make the device effective and burst noise-free, to achieve high-precision characteristics and to be effective for downsizing, and to greatly simplify the manufacturing process.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram illustrating a semiconductor device of a first example according to an embodiment of the present invention.

FIG. 2 is a cross-sectional configuration diagram illustrating a semiconductor device according to a second embodiment.

FIG. 3 is a cross-sectional configuration diagram illustrating a semiconductor device according to a third embodiment.

FIGS. 4A to 4D are diagrams for sequentially explaining manufacturing steps of the semiconductor device according to the first embodiment;

[Explanation of symbols]

11 ... semiconductor substrate, 111 ... silicon substrate, 112 ... buried layer,
113: epitaxial growth layer, 114: opening, 12: LO
COS oxide film, 13 ... base layer, 14 ... emitter layer, 15 ...
Base electrode layer, 16: first insulating layer, 17: insulating layer, 18, 19
... Outgoing electrode, 20... Second insulating layer, 21.

Claims (4)

[Claims] A first conductive type base layer formed in an element formation region of a semiconductor substrate; a second conductive type emitter layer formed in the base layer; and a base layer corresponding to the base layer. A base electrode layer made of a conductive material formed on a surface portion of the semiconductor substrate; and a first insulating layer formed to protect a surface portion and a side surface portion of the base electrode layer; The layer and the emitter layer are formed by an epitaxial growth layer formed in an opening formed by etching on the surface of the semiconductor substrate, and are configured by diffusing first and second impurities into the epitaxial growth layer. Semiconductor device. 2. The semiconductor device according to claim 1, wherein a second insulating layer is formed between said base layer formed by said epitaxial growth and said semiconductor substrate. 3. The semiconductor device according to claim 1, wherein a diffusion layer of a first conductivity type is formed on said semiconductor substrate in contact with said base layer formed by said epitaxial growth. 4. A substrate forming step of forming a semiconductor substrate; a base electrode forming step of forming a base electrode layer on the surface of the semiconductor substrate with a conductive material; and covering a surface portion and a side portion of the base electrode layer. A first insulating layer forming step of forming an opening corresponding to the emitter region; and etching the semiconductor substrate from the opening of the first insulating layer corresponding to the emitter region to form an opening in the semiconductor substrate. Forming a base layer epitaxially grown in an opening formed in the semiconductor substrate by etching and forming a first conductive type base layer; and forming a surface of the semiconductor substrate inside the base region. Forming an emitter layer of a second conductivity type, which is epitaxially grown to correspond to the following. A method for manufacturing a semiconductor device, wherein a base electrode layer connected to the base layer is covered and used as a mask in an etching process of a semiconductor substrate on which the base layer is formed.