JPS63221684A - Manufacture of microwave integrated circuit - Google Patents

Abstract

PURPOSE:To shorten a developing period which can reduce the irregularity in characteristics by measuring the characteristics of a microwave transistor 2a formed on a GaAs wafer 1, and connecting a receiver designed on the basis of the measured result to the transistor. CONSTITUTION:A gate electrode 13, a source electrode 18 and a drain electrode 19 are formed on a GaAs wafer 11. These electrodes 18, 19 are, for example, formed in a 3-layer structure of Ti, Pt, Au. Thus, a microwave field effect transistor is formed on the wafer 11. In order to form that for measuring characteristics, the leads of the electrodes 13, 18 are formed in a pattern capable of contacting with ON wafer measuring probe like electrodes 4a-4c. Then, the characteristics of the transistor are measured in the wafer state as it is. A receiver is designed by the measured results and frequency characteristics to be required to form a receiver connected to the electrodes 13, 18, 19 of the transistor. After an MIC containing the receiver is formed in this manner, a chip is separated from the wafer 11, and sealed in a package.

Description

[Detailed Description of the Invention] [Summary] After microwave transistors are formed in an array on a GaAs wafer, the characteristics of the microwave transistors are measured using an on-wafer measurement probe, etc., and a distribution corresponding to the characteristics is determined. Passive circuits such as constant matching circuits are formed to be compatible with microwave transistors, and GaAs
Even if the characteristics of microwave transistors differ from wafer to wafer, microwave integrated circuits with desired characteristics can be manufactured.

[Industrial application field]

The present invention relates to a method for manufacturing a microwave integrated circuit in which microwave transistors such as field effect transistors and distributed constant matching circuits connected thereto are formed in an array on a GaAs wafer.

Microwave integrated circuits (MICs) are divided into two types: hybrid type, in which a passive circuit is formed on a dielectric substrate, and transistor chips and circuit element chips are mounted on the dielectric substrate; It is broadly divided into the monolithic (n+onolithic) type, which forms a matching circuit, etc. together with active elements such as transistors, etc. Recently, the monolithic type, which uses a GaAs substrate as a semiconductor substrate, has been relatively frequently adopted.

In such a monolithic microwave integrated circuit, it is necessary to form a passive circuit such as an optimal matching circuit that corresponds to the characteristics of the microwave transistor as an active element, and it is possible to manufacture it with a simple process. It is requested.

C. Prior Art] Conventional methods for manufacturing microwave integrated circuits include, for example, the third method for manufacturing microwave integrated circuits.
As shown in the figure, only microwave transistors are formed in an array on a GaAs wafer 31, and then separated into chips consisting of a single microwave transistor and incorporated into a microwave circuit. The transistor characteristics are measured, and based on the measurement results, microwave integrated circuits (MI
C), and based on the design, fabricate an MIC using a new GaAs wafer. Then, it was separated into chips and incorporated into a microwave circuit, and the characteristics of the MIC were measured.
If the desired characteristics are not obtained, the design is carried out again and the MIC is fabricated using a new GaAs wafer.

Figure 4 is an explanatory diagram of a two-stage amplifier circuit, and shows the M
An example of an IC pattern is shown. In the same figure,
41 is a GaAs substrate (a chip separated from a wafer);
42.43 is electric field effect.

In the transistor, G is a gate, D is a drain, S is a source, 44 to 48 are capacitors, and 49 to 52 are inductances.

When manufacturing such a MIC, conventionally, as described above, field effect transistors are manufactured in an array on a GaAs wafer, separated into chips, and their characteristics are measured.Based on the measurement results, Field effect transistor 41
．． 42, capacitors 44 to 48 and inductance 49
Based on the design, the pattern of the passive circuit that can be formed simultaneously with the formation of the electrodes of the field effect transistors 41 and 42 using a new GaAs wafer is based on the design. It is formed during the process to manufacture the MIC.

[Problem that the invention seeks to solve]

As mentioned above, the conventional manufacturing method is to first design and manufacture only a microwave transistor, measure its characteristics, and then
The MIC is designed and manufactured based on the measurement results.
This is repeated for each variety. Therefore, at least the first GaAs wafer is used only for measuring the characteristics of microwave transistors and cannot be used as a product, which causes an increase in cost in high-mix, low-volume production.

Also, GaA for measuring the characteristics of microwave transistors.
S wafers and GaAs wafers for manufacturing MICs are different, so even if microwave transistors are manufactured in the same process, variations in characteristics may occur.

Therefore, there was a drawback that the yield was low.

An object of the present invention is to easily obtain desired characteristics with little variation.

(Means for solving the iJf problem) The method for manufacturing a microwave integrated circuit of the present invention separates the manufacturing process of a microwave transistor and the manufacturing process of a passive circuit such as a distributed constant matching circuit, This will be explained with reference to FIG.

A gate G and a source S are formed on the GaAs wafer 1.

A step of forming a plurality of microwave transistors 2 in an array including at least a microwave transistor 2a such as a field effect transistor having electrodes 4a, 4b, 4C for measuring characteristics such as the drain D, and then forming the GaAs
The electrodes 4a, 4 for measuring the characteristics formed on the wafer 1
b and 4c, measure the characteristics of the microwave transistor 2a, design a passive circuit 3 such as a distributed constant matching circuit based on the measurement results, and use the passive circuit 3 based on the design as the microwave transistor 2a. This includes a step of forming the transistors 2 and 2a so as to be connected thereto.

[Effect]

A microwave transistor 2.2a is formed by securing an area on the GaAs wafer 1 in which a passive circuit 3 such as a distributed constant matching circuit can be formed. As shown in the enlarged view, 2a forms electrodes 4a, 4b, and 4c for measuring characteristics, and these electrodes 4 are formed without being separated into chips.
A, 4b, and 4c are used to measure the characteristics of the microwave transistor 2a using an on-wafer measurement probe or the like.

Next, based on the measured characteristics of the microwave transistor 2a, a passive circuit 3 such as a distributed constant matching circuit is designed by giving conditions such as the operating frequency and bandwidth. In this step, for example, if the frequencies used are different, the design can be carried out in parallel for each frequency used. Then, based on the designed pattern, a passive circuit 3 is formed by performing processes such as metal film deposition and patterning so as to be connected to the microwave transistors 2 and 2a formed previously, and finally, It is separated into chips and sealed in a package.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a process explanatory diagram of an embodiment of the present invention. As shown in (a), for example, Si is implanted into a GaAs wafer 11 by ion implantation to form nNl2, and a gate electrode 13 and a gate electrode 13 are formed. For example, the lower electrode 14 of a capacitor is formed. The gate electrode 13 is made of, for example, Ti, W, Mo, or a compound of these and Si, and constitutes a Schottky gate. Further, the gate electrode 13 and the lower electrode 14 can be formed simultaneously from the same material.

Next, as shown in (b), an insulating layer 15 such as S i 02
is formed over the entire surface and annealed to activate nJi12.

Next, the insulating layer 15 is etched by reactive ion etching or the like. As a result, the insulating layer 15 remains only on the side walls of the gate electrode 13 and the lower electrode 14, and the rest is removed. This remaining insulating layer is indicated by 151 in the drawings from (C) onwards. Then, using the gate electrode 13 having the remaining insulation JIi 15° on the sidewall as a mask, an n layer is formed by ion implantation. Next, an ohmic contact layer 16 of Au-Go/Ni is formed, and a resist layer 17 is applied thereon. (C) shows this state.

Next, as shown in (d), etching is performed by reactive ion etching or the like. Since the resist layer 17 is thinly applied on the gate electrode 13 and the lower electrode 14, the resist layer 17 and the ohmink contact layer 16 above them are removed.

Next, the resist layer 17 is removed, and a source electrode 18 and a drain electrode 19 are formed on the ohmic contact layer 16, as shown in (e). These electrodes 18 and 19 can have a three-layer structure of Ti, Pt, and Au, for example.

Through the above steps, a microwave field effect transistor is formed on the GaAs wafer 11. In addition, when using a transistor for measuring characteristics, the lead-out portion of the gate electrode 13, the lead-out portion of the source electrode 18, and the lead-out portion of the drain electrode 19 are connected to the lead-out portions of the electrodes 4a, 4b, and 4c in the enlarged portion of FIG. The pattern is formed so that it can be contacted with an on-wafer measurement probe.

Next, the characteristics of the transistor are measured in the wafer state without separating it into chips. A passive circuit such as a distributed constant matching circuit is designed based on this measurement result and the required frequency characteristics. For example, λ/4 stub (λ = wavelength)
etc., the dimensions are determined by the frequency used. Once the passive circuit is designed, first the GaAs wafer 1 is
1. A passive circuit is formed connected to each electrode 13.18.19 of the field effect transistor formed on 1.

For example, when connecting a capacitor of a passive circuit to the drain electrode 19, as shown in FIG. Correspondingly, the upper electrode 21 is formed so as to be connected to the drain electrode 19, and the upper electrode 21 is designed to have a facing area that provides a desired capacitance.

In addition, passive circuits including λ/4 stubs etc. may be
An insulating layer such as SiO2 is formed on the field effect transistor formed on the As wafer 11, and holes are formed in the insulating layer to connect to the electrodes 13, 18, and 19 of the field effect transistor. , then by depositing a metal layer over the entire surface and etching it into the desired pattern. That is, a passive circuit connected to the electrodes 13, 18, 19 of the field effect transistor is formed.

After the MIC including the passive circuit is formed in this way, the G
The aAs wafer 11 is separated into chips and sealed in a package.

The manufacturing process of the field effect transistor shown in (a) to (e) above shows the self-line technology using the insulating layer 15° on the side wall of the gate electrode 13, but the field effect transistor can be manufactured using other manufacturing processes. It is also possible to manufacture In that case as well, at least one field effect transistor for measuring characteristics is formed in one GaAs wafer.

Since it forms a passive circuit that corresponds to the measured characteristics, even if there are variations in the GaAs wafer,
It becomes possible to form an MIC with desired characteristics.

〔Effect of the invention〕

As explained above, the present invention measures the characteristics of the microwave transistor 2a formed on a GaAs wafer 1 in the wafer state without separating it into chips, and develops the passive circuit 3 based on the measurement results. , is formed by connecting it to the previously formed microwave transistor 2.2a, which has the advantage of not wasting the GaAs wafer for characteristic measurement, and also allows passive circuits that correspond to the measured characteristics. 3, it has the advantage that variations in characteristics as an MIC can be reduced.

In addition, the passive circuits 3 corresponding to the required characteristics such as bandwidth are designed, and the designed passive circuits 3 are formed using commonly manufactured microwave transistors, which allows for a wide variety of products. There is an advantage that the development period can be shortened even in the case of small quantity production.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the principle of the present invention, Fig. 2 is an explanatory diagram of the process of an embodiment of the present invention, Fig. 3 is an explanatory diagram of the manufacturing process of a conventional example, and Fig. 4 is an explanatory diagram of a two-stage amplifier circuit. be. 1 is a GaAs wafer, 2.2a is a microwave transistor, 3 is a passive circuit, and 4a, 4b, and 4c are electrodes for measuring characteristics.

Claims (1)

[Claims] A method for manufacturing a microwave integrated circuit in which a microwave transistor (2) and a passive circuit (3) such as a distributed constant matching circuit are integrated on a GaAs wafer (1), On the GaAs wafer (1), there are electrodes (4) for measuring characteristics.
A, 4b, 4c) microwave transistor (
a step of forming a plurality of microwave transistors (2) in an array, including at least a plurality of microwave transistors (2a); Measure the characteristics of the microwave transistor (2a), design a passive circuit (3) such as the distributed constant matching circuit corresponding to the characteristics, and connect the passive circuit (3) to the microwave transistor (2,
2a) A method for manufacturing a microwave integrated circuit, comprising the step of connecting and forming a microwave integrated circuit.