JPH0974103A - Semiconductor device and method of manufacturing the same - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To form a contact between SiGe and Si.
Suppress the segregation of. Sn is introduced into a region containing Ge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for forming a junction between semiconductors having different band gaps, particularly for forming a junction between a Si layer and a layer composed of Si and Ge. More specifically, it relates to a method for obtaining a very steep interface between these layers.

In the present specification, "on a substrate" or "...
Although the expression "above" is used, they mean the direction of crystal growth, not the direction during manufacturing or the direction of a finally manufactured device.

[0003]

2. Description of the Related Art A hetero bipolar transistor (hereinafter referred to as "HBT") is well known as a semiconductor device utilizing a junction of semiconductors having different band gaps. GaAs type is well known, but S
Also for i-type (hereinafter referred to as “SiHBT”), a structure using a layer composed of Si and Ge (hereinafter referred to as “SiGe layer”) as a base and a structure in which a SiC layer is provided between a base and an emitter are known. . SiGe layer or SiC
The layers are formed in very thin layers, at most 100 Angstroms. When the SiGe layer is used, a superlattice in which Si layers and Ge layers each having a thickness of several atomic layers are alternately stacked, or a solid solution of Si and Ge is used.

In order to manufacture an HBT based on a SiGe layer, a SiGe layer is crystal-grown on a Si substrate on which a Si layer for collector is formed, and then Si is further crystal-grown to form an emitter. . These crystal growths are based on Molecular Beam Epitaxy (hereinafter “MB”).
"E").

[0005]

However, when forming a SiGe layer, there is a problem that Ge segregates. Ge
If the segregation occurs, the interface between the base and the emitter will be blurred and the characteristics of the HBT will deteriorate. In order to prevent this, conventionally, Sb or B is added to the portion containing Ge.
i was being added. However, Sb, Bi
Is an n-type impurity with respect to Si and Ge, and it was not possible to control segregation and the degree of n-type independently.

The present invention solves such a problem and solves the problem of Si.
A final object is to provide a semiconductor device having good characteristics using contact between Ge and Si. Therefore, manufacturing of a semiconductor device capable of growing a SiGe layer on a Si substrate while suppressing segregation of Ge. The purpose is to provide a method.

[0007]

A first aspect of the present invention is a method of manufacturing a semiconductor device, which comprises Si and G on a Si substrate.
In a method of manufacturing a semiconductor device including a step of crystal-growing a layer made of e, Sn is contained in at least a layer containing Ge.
It is characterized by introducing (tin). The step of growing a crystal includes a growth step by MBE, and it is preferable to introduce Sn together with Si and Ge in this growth step.

A second aspect of the present invention is a semiconductor device manufactured by the above method, which is characterized in that Sn is added to at least a layer containing Ge in a layer made of Si and Ge. The layer made of Si and Ge is SiHBT
Is preferably formed as a base layer.

Sn is introduced to suppress the segregation of Ge. Sn is a group IV element like Si and Ge,
There is no electrical impact due to its introduction. Therefore, SiHB
When manufacturing T, a film structure that maximizes the characteristics as HBT and suppression of segregation can be achieved at the same time.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining a method of manufacturing a semiconductor device according to the present invention. This method uses a general Si-MBE apparatus. This apparatus includes a reaction tank 1 whose inside is kept in an ultrahigh vacuum, and a plurality of molecular beam sources 2, 3, 4 are connected to the reaction tank 1. A substrate holder 11 is provided in the reaction tank 1 at a position where the molecular beams from the molecular beam sources 2, 3, and 4 are incident, and the Si substrate 12 is attached to the substrate holder 11. The reaction tank 1 is also provided with a shutter 13 for interrupting the molecular beams from the molecular beam sources 2, 3, 4.

The molecular beam sources 2 and 3 are for Si and Ge, respectively. By injecting the molecular beam from the molecular beam source 2 into the Si substrate 12, Si crystal can be grown on the Si substrate 12. Further, SiGe can be grown by simultaneously injecting the respective molecular beams from the molecular beam sources 2 and 3 into the Si substrate 12.

When the present invention is carried out, the molecular beam source 4 for Sn is further used, and the Sn molecular beam is incident on the Si substrate 12 at the same time as the molecular beams of Si and Ge. Si
For example, the ratio of Ge to Ge is 8 to 2, and Sn is 4 from Ge
Reduce by about a few digits. That is, the Sn concentration is about the same as the normal n-type or p-type impurity concentration. As a result, Sn is introduced into the SiGe layer, and segregation of Ge can be suppressed.

FIG. 2 shows the SiH produced by the above method.
It is sectional drawing which shows the structure of BT. This SiHBT is Si
The substrate is provided with an n-type Si collector layer 21, a p-type SiGe base layer 22 and an n-type Si emitter layer 23 which are epitaxially laminated on the substrate, and a collector electrode 24, a base electrode 25 and an emitter electrode 26 are connected to each. p-type Si
The Ge base layer 22 contains Sn to suppress the segregation of Ge.
Is added. Since Sn is the same group IV element as Si and Ge, it does not become an n-type or p-type dopant, and does not affect the electrical characteristics of the p-type SiGe base layer 22. Therefore, the p-type SiGe base layer 22
Segregation of Ge can be suppressed irrespective of the electrical characteristics of.

Although the NPN transistor has been described as an example here, the present invention can be similarly implemented in the case of a PNP transistor. When Sb or Bi is added to the SiGe base layer as in the prior art, only a PNP transistor having an n-type base can be realized, but the present invention can also realize an NPN transistor.

[0015]

As described above, in the method of manufacturing a semiconductor device of the present invention, Sn is introduced in order to suppress the segregation of Ge when the layer of Si and Ge is grown by crystal growth. Sn is a group IV element like Si and Ge, and its introduction has no electrical effect. Therefore, particularly in the case of manufacturing SiHBT, there is an effect that a film structure that maximizes the characteristics as HBT and suppression of segregation can be achieved at the same time.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method for manufacturing a semiconductor device of the present invention.

FIG. 2 is a cross-sectional view showing the structure of SiHBT.

[Explanation of symbols]

 1 Reaction Tanks 2, 3, 4 Molecular Beam Source 11 Substrate Holder 12 Si Substrate 13 Shutter 21 n-type Si Collector Layer 22 p-type SiGe Base Layer 23 n-type Si Emitter Layer 24 Collector Electrode 25 Base Electrode 26 Emitter Electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Kobayashi 2-11-13 Nakamachi, Musashino-shi, Tokyo Inside Teratech Co., Ltd. Inside

Claims (4)

[Claims] 1. A method of manufacturing a semiconductor device, comprising a step of crystal-growing a layer of Si and Ge on a Si substrate, wherein Sn is introduced into at least the layer of Ge. . 2. The crystal growing step includes a growth step by molecular beam epitaxy, in which Si is grown.
The method for manufacturing a semiconductor device according to claim 1, wherein Sn is introduced together with Ge. 3. A semiconductor device having a layer made of Si and Ge, wherein Sn is added to at least a layer containing Ge in the layer made of Si and Ge. 4. The semiconductor device according to claim 1, wherein the layer composed of Si and Ge is formed as a base layer of a Si hetero bipolar transistor.