JPH03250767A - Manufacture of heterojunction bipolar transistor - Google Patents

Abstract

PURPOSE:To prevent an etching mask from being peeled even in a fine collector pattern by a method wherein when a collector mesa is formed, one part of the collector mesa is formed by performing a dry etching and moreover, a dry etching is performed vertically to the collector mesa. CONSTITUTION:At the time of the formation of a collector mesa comprising a collector layer 13 consisting of an AlxGa1-xAs layer (0<x<=1) and a collector contact layer 12 consisting of an InyGa1-yAs layer (0<=y<=1), one part of the collector mesa is formed by performing a reactive ion etching or reactive ion beam etching using CCl4, Cl2 or BCl3. Moreover, a reactive ion etching or reactive ion beam etching using CCl4, Cl2 or BCl3 is performed vertically to the collector mesa, whereby the collector mesa is formed. Thereby, an etching mask 11 is never peeled even in a fine collector pattern and the collector mesa can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heterojunction bipolar transistor (hereinafter referred to as HBT) which can be used in ultra-high speed devices and ultra-high frequency devices.
(abbreviated as )).

2. Description of the Related Art In recent years, compound semiconductor devices have attracted attention as light-emitting devices or ultrahigh-speed devices.

In particular, HBTs are very promising as ultra-high-speed devices.
In order to take advantage of this feature, various etching techniques are being used to miniaturize devices, such as forming a mesa shape by wet etching and vertical etching by dry etching.

Hereinafter, an example of a method for manufacturing an HBT using the above-mentioned conventional etching will be described with reference to the drawings.

FIGS. 2(a), 2(b), and 2(d) are cross-sectional views of an HBT showing a conventional method for manufacturing an HBT by etching. In FIGS. 2(a), (b), (c), and (d), 21 is an etching mask from AuGe/former 8U which also serves as an emitter electrode, 22 is an emitter contact layer made of low resistance n-type GaAs, and 23 is n-type AlxGa+-
An emitter layer made of xAs (0<x≦0.3), 24 a base layer made of n-type GaAs, 25 a collector layer made of n-type GaAs, 26 a semi-insulating GaAs substrate, 27
is reactive ion etching.
28 is a base electrode made of TI/MUU.

A method for manufacturing the HBT having the above configuration will be described below.

The sample shown in FIG. 2(a) on which the etching mask 21 which also serves as an emitter electrode is formed is subjected to RIE using a plasma 27 using BCIa as an etching gas to dry a part of the emitter contact layer 22 and the emitter layer 23. After etching, the result will be as shown in Figure 2(b). Further, the sample shown in FIG. 2(b) was wet-etched to remove the remainder of the emitter layer 23 using an etching solution consisting of an aqueous sodium hydroxide solution, hydrogen peroxide, and water.
As shown in FIG. 2C, the base layer 24 is exposed, and the emitter mesa is formed without narrowing by side etching, compared to the case where the emitter mesa is formed only by wet etching. Further, as shown in FIG. 2(d), the base electrode 28 can be formed in a self-aligned manner by vacuum evaporation using the emitter electrode as a mask.

29 is a part of the emitter electrode formed at the same time. (For example, 19871EEE HIT-SD
igest pp969-972).

Problems to be Solved by the Invention However, in this conventional example, during wet etching, the etching mask 21 and the emitter contact layer 22 form a metal-semiconductor junction, and the etching solution acts uniformly. In particular, in the case of fine emitter patterns, the etching mask 21 tends to peel off as shown by the broken line in FIG. 2(C), making accurate etching impossible. Here, even if the structure of the HBT is a collector-up structure in which the emitter and seven collectors are reversed, the problem remains that the etching mask easily peels off in a fine collector pattern.

In view of the above problems, the present invention provides a method for manufacturing an HBT that can form a collector mesa without peeling off the etching mask even in a fine collector pattern.

Means for Solving the Problems In order to solve the above problems, the manufacturing method of the present invention provides HBT
In forming the collector mesa, a part of the collector mesa is formed by dry etching, and then dry etching is performed perpendicularly to the collector mesa.

According to the present invention, a part of the collector mesa is formed by dry etching, and dry etching is performed perpendicularly to the collector mesa, so that even in a fine collector pattern, the collector mesa can be formed without peeling off the mask. can be formed.

Furthermore, a base electrode can be formed in a self-aligned manner using the collector electrode.

EXAMPLE Hereinafter, a method for manufacturing an HBT by etching according to an example of the present invention will be described with reference to the drawings.

Figure 1 (a Hb) (c) (d) (e) shows the process of the HBT manufacturing method by etching of the present invention.
It is a sectional view of BT. Figure 1 (a) (b) (c)
In (d He ), 11 is an etching mask that also serves as a collector electrode, +2 is a collector contact l- layer made of low resistance n-type 1nAs, 13 is a collector layer made of n-type GaAs, and I4 is a base made of n-type GaAs. layer,
15 is an emitter layer made of n-type AIB, Ga@, 7As, IG is a semi-insulating GaAs substrate, +7 is a plasma for performing RIE, and 18 is a base electrode made of AuZn.

The operation of the method for manufacturing the HBT having the above structure will be described below with reference to FIG.

The sample shown in FIG. 1(a) on which the etching mask 11 which also serves as a collector electrode is formed is etched with an etching gas of CCl4.
Collector contact layer I was formed by RIE used as 7A.
2 and the collector layer I3 are subjected to plasma dry etching, resulting in a structure as shown in FIG. 1(b).

Furthermore, the sample in Fig. 1(b) was subjected to RIE using CCl4 gas 17B perpendicular to the collector mesa, that is, in a direction perpendicular to the dry etching direction with plasma gas +7A, as shown in Fig. 1(c) and (d). A collector mesa is completed by dry etching (FIG. 1(d)). In the etching of the laminated structure shown in FIGS. 1(c) and 1(d), etching is performed perpendicular to the direction of the collector mesa (X direction), that is, in the lateral direction, and even in the case of a fine collector pattern,
During dry etching, etching mask 11 and In
The etching mask 11 will not be peeled off from the collector contact layer 12 since the plasma of the cut 17B acts uniformly on the junction with the collector contact layer 12 made of As. Furthermore, as shown in FIG. 1(e),
The base electrode I8 can be formed in a self-aligned manner by vacuum evaporation using the collector electrode 11 as a mask.

As described above, according to this embodiment, when forming a collector mesa made of InAs and GaAs by etching, a part of the collector mesa is formed by dry etching, and then dry etching is performed perpendicularly to the collector mesa to form a fine etching. Even in such a collector pattern, the collector mesa is formed without the etching mask 11 peeling off from the collector contact layer 12. Further, since the base electrode is also formed by self-alignment using the collector electrode as a mask, it is possible to form a fine HBT with small parasitic capacitance and parasitic resistance.

In this example, the collector contact layer 12 is made of nAs, but InvGa+-xAs (0≦y≦1)
Although the collector layer 13 is made of GaAs, it may be made of A
It may also be IJa+-xAs (0<x≦1).

In this example, CCIa was used as the etching gas.
However, C12 or BC+a may also be used.Although reactive ion etching was used as the etching method, reactive ion beam etching may also be used.

Effects of the Invention As described in section 2, the present invention provides HBT AlxGa+-Js
A collector layer consisting of a layer (0x≦1) and InyGa, x
When forming a collector mesa including a collector contact layer made of an As layer (0≦y≦1), a part of the collector mesa is formed by reactive ion etching or reactive ion beam etching using CCl4, C12, or BCIi, Furthermore, the present invention is characterized in that the collector mesa is formed by performing reactive ion etching or reactive ion beam etching using CC11, C12, or BOh perpendicularly to the collector mesa. By using the HBT manufacturing method of the present invention, a collector mesa can be formed even in a fine collector pattern without peeling off the etching mask. Furthermore, since the base electrode is also formed in self-alignment using the collector electrode as a mask, it is possible to form a fine HBT with small parasitic capacitance and parasitic resistance.

[Brief explanation of drawings]

FIG. 1 is a process cross-sectional view illustrating an HBT manufacturing method according to an embodiment of the present invention, and FIG. 2 is a process cross-sectional view explaining a conventional HBT manufacturing method. 11... Etching mask, 12...
Collector contact layer, 13... Collector layer,
14. Old... Base layer, 15... Emitsuta layer,
18... base electrode, 2... etching mask, 22... emitter contact layer, 23...
・・・・・・Emitsuta layer, 24 ・・・・Base layer, 2
5... group/collector layer, 28... base electrode.

Claims (3)

[Claims] (1) When forming the collector mesa of the heterojunction bipolar transistor, a method for manufacturing a heterojunction bipolar transistor is characterized in that a part of the collector mesa is formed by dry etching, and further dry etching is performed perpendicular to the collector mesa. (2) Collector mesa is Al_xGa_1_-_xAs
A collector layer consisting of a layer (0<x≦1) and In_yGa_
2. The method of manufacturing a heterojunction bipolar transistor according to claim 1, wherein the transistor has a laminated structure including a collector contact layer consisting of a 1_-_yAs layer (0≦y≦1). (3) Dry etching is CCl_4 or Cl_2
The method for manufacturing a heterojunction bipolar transistor according to claim 1, wherein the method is reactive ion etching using BCl_3 or reactive ion beam etching.