JPH0812929B2 - Manufacturing method of microwave integrated circuit - Google Patents

Description

DETAILED DESCRIPTION [Outline] After forming microwave transistors in an array on a GaAs wafer, the characteristics of the microwave transistors are measured by an on-wafer measuring probe, and a distribution corresponding to the characteristics is measured. A passive circuit such as a constant matching circuit is formed corresponding to the microwave transistor. Even if the characteristics of the microwave transistor are different for each GaAs wafer, a microwave integrated circuit with desired characteristics can be manufactured. It is possible.

[Industrial applications]

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

Microwave integrated circuits (MICs) are a hybrid type in which a passive circuit is formed on a dielectric substrate, and a transistor chip or a circuit element chip is mounted on the dielectric substrate, and a transistor on a semiconductor substrate. Monolithic (mo
Nolithic) type, and recently as a semiconductor substrate
The monolithic type using a GaAs substrate is relatively often used.

In such a monolithic microwave integrated circuit, it is necessary to form a passive circuit such as an optimum matching circuit corresponding to the characteristics of the microwave transistor as an active element, which can be manufactured by a simple process. Is requested.

[Conventional technology]

A conventional method for manufacturing a microwave integrated circuit is, for example, as shown in FIG. 3, forming only an array of microwave transistors on a GaAs wafer 31 and then forming a chip including a single microwave transistor. , The microwave integrated circuit is incorporated into a microwave circuit, the characteristics of the microwave transistor are measured, and a microwave integrated circuit (MIC) including a passive circuit such as a distributed constant matching circuit is designed based on the measurement result. MIC using new GaAs wafer based on design
To produce. Then, it is separated into chips and incorporated in a microwave circuit, the characteristics of the MIC are measured, and if the desired characteristics cannot be obtained, the MIC is manufactured again by designing again and using a new GaAs wafer.

FIG. 4 is an explanatory diagram of a two-stage amplifier circuit, showing a case where a field effect transistor is used as a microwave transistor.
It is an example of a MIC pattern. In the figure, 4
1 is a GaAs substrate (chip separated from the wafer), 42 and 43 are field effect transistors, G is a gate, D is a drain, S
Is a source, 44 to 48 are capacitors, and 49 to 52 are inductances.

In the case of manufacturing such an MIC, conventionally, as described above, a field effect transistor is manufactured in an array shape on a GaAs wafer, and the characteristics are measured by separating each into chips, and based on the measurement result, the electric field Effect transistors 41 and 42,
A MIC including a passive circuit composed of capacitors 44 to 48 and inductances 49 to 52 is designed, and based on this design, a new GaAs wafer can be used to form a passive element that can be formed simultaneously with the formation of the electrodes of the field effect transistors 41 and The circuit pattern is
It is formed in the same process and a MIC is manufactured.

[Problems to be solved by the invention]

As described above, in the conventional manufacturing method, only the microwave transistor is designed and manufactured first, its characteristics are measured, and the MIC is designed and manufactured based on the measurement result. This is repeated for each product type. It is a thing. Therefore, at least the first GaAs wafer is not used as a product because it is used only for measuring the characteristics of the microwave transistor, which causes a cost increase in the production of a wide variety of products in small quantities.

GaAs for measuring the characteristics of microwave transistors
Since the wafer is different from the GaAs wafer for manufacturing the MIC, even if the microwave transistor is manufactured in the same process, the characteristics may vary. Therefore,
There was a drawback that the yield was low.

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

[Means for solving problems]

The method of manufacturing a microwave integrated circuit of the present invention divides a manufacturing process of a microwave transistor and a manufacturing process of a passive circuit such as a distributed constant matching circuit, which will be described with reference to FIG.

An array of a plurality of microwave transistors 2 including at least a microwave transistor 2a such as a field effect transistor having electrodes 4a, 4b, 4c for measuring characteristics of a gate G, a source S, a drain D, etc. on a GaAs wafer 1 And then the characteristics measurement electrodes 4a, 4b, 4c formed on the GaAs wafer 1 are used to measure the characteristics of the microwave transistor 2a. Based on the design of the passive circuit 3 such as a distributed constant matching circuit, the passive circuit 3 based on the design is used as the microwave transistors 2, 2a.
And a step of forming so as to be connected to.

[Action]

Passive circuit 3 such as distributed constant matching circuit on GaAs wafer 1.
The microwave transistors 2 and 2a are formed by securing a region in which the microwave transistors 2 and 2a are formed. In this case, all or some of the microwave transistors 2a are, as shown in an enlarged manner, electrodes for characteristic measurement. 4a, 4b, 4c are formed,
The characteristics of the microwave transistor 2a are measured by using the electrodes 4a, 4b, and 4c without using chips, and using an on-wafer measurement probe or the like.

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

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a process explanatory view of an embodiment of the present invention, (a)
As shown in FIG. 3, for example, Si is ion-implanted into the GaAs wafer 11 to form the n-layer 12, and the gate electrode 13 and the lower electrode 14 of the capacitor are formed. The gate electrode 13 is made of, for example, Ti, W, Mo or the like, or a compound thereof with Si, and constitutes a Schottky gate. Further, the gate electrode 13 and the lower electrode 14 can be simultaneously formed of the same material.

Next, as shown in (b), an insulating layer 15 such as SiO ₂ is formed on the entire surface and annealed to activate the n layer 12.

Next, the insulating layer 15 is etched by reactive ion etching or the like. Thereby, the gate electrode 13 and the lower electrode
The insulating layer 15 remains only on the side wall of the insulating layer 14 and the other portions are removed. This residual insulating layer is indicated by 15 'in the drawings after (c). Then, an n ⁺ layer is formed by ion implantation using the gate electrode 13 having the remaining insulating layer 15 'on the side wall as a mask. Next, an Au-Ge / Ni ohmic contact layer 16 is formed,
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. The resist layer 17 is a gate electrode
Since it is applied thinly on 13 and the lower electrode 14, etc., the resist layer 17 and ohmic contact layer 16 on the upper part thereof are removed.

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

Through the above steps, the microwave field effect transistor is formed on the GaAs wafer 11. When using a transistor for characteristic measurement, the gate electrode 13
Of the source electrode 18, the drain electrode 19, and the extended portion of the electrodes 4a, 4b, 4c of FIG.
As shown in FIG.

Next, the characteristics of the transistor are measured in a wafer state without being divided into chips. A passive circuit such as a distributed constant matching circuit is designed based on this measurement result and required frequency characteristics. For example, λ / 4 stub (λ = wavelength)
The dimensions of the above will be determined by the frequency used. When the passive circuit is designed, the passive circuit connected to the electrodes 13, 18 and 19 of the field effect transistor previously formed on the GaAs wafer 11 is formed.

For example, when connecting a capacitor of a passive circuit to the drain electrode 19, as shown in (f), a dielectric layer 20 is formed on the lower electrode 14, and the dielectric constant and the thickness of the dielectric layer 20 are changed. Correspondingly, an upper electrode 21 designed to have a facing area with which a desired capacitance is obtained is formed so as to be connected to the drain electrode 19.

In addition, the passive circuit including λ / 4 stub,
On the field effect transistor formed on the wafer 11,
An insulating layer such as SiO ₂ is formed, and a hole for connecting to the electrodes 13, 18 and 19 of the field effect transistor is formed in the insulating layer, and then a metal layer is deposited on the entire surface to form a desired pattern. It is formed by etching. That is, a passive circuit connected to the electrodes 13, 18 and 19 of the field effect transistor is formed.

After the MIC including the passive circuit is formed in this way, GaA
s Wafer 11 is separated into chips and enclosed in a package.

The manufacturing process of the field effect transistor shown in (a) to (e) above is a self-alignment technique using the insulating layer 15 'on the sidewall of the gate electrode 13, but the field effect transistor is manufactured by another manufacturing process. It is also possible to manufacture Even in that case, at least 1 is included in one GaAs wafer.
A field effect transistor for characteristic measurement is formed. Since the passive circuit corresponding to the measured characteristic is formed, it is possible to form the MIC having the desired characteristic even if the GaAs wafer has variations.

〔The invention's effect〕

As described above, according to the present invention, the characteristics of the microwave transistor 2a formed on the GaAs wafer 1 are measured in a wafer state without separating into chips, and the passive circuit 3 based on the measurement result is obtained. , It is formed by connecting to the previously formed microwave transistors 2 and 2a, and has the advantage that the GaAs wafer is not wasted for the characteristic measurement, and the passive circuit corresponds to the measured characteristic. 3 is formed, there is an advantage that variation in characteristics as the MIC can be reduced.

In addition, since the passive circuit 3 corresponding to the characteristics such as required bandwidth is designed, and the designed passive circuit 3 is formed by using the microwave transistor commonly manufactured in advance, it is possible to manufacture various kinds of products. There is an advantage that the development period can be shortened even in the case of small-quantity production.

[Brief description of drawings]

1 is an explanatory view of the principle of the present invention, FIG. 2 is an explanatory view of a process of an embodiment of the present invention, FIG. 3 is an explanatory view of a manufacturing process of a conventional example, and FIG. 4 is an explanatory view of a two-stage amplifier circuit. is there. 1 is a GaAs wafer, 2 and 2a are microwave transistors, 3
Is a passive circuit, and 4a, 4b, 4c are electrodes for measuring characteristics.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/78

Claims (1)

[Claims] 1. A microwave transistor (2) and a passive circuit (3) such as a distributed constant matching circuit on a GaAs wafer (1).
In the method of manufacturing a microwave integrated circuit in which and are integrated circuits, electrodes (4a, 4b,
4c) forming a plurality of microwave transistors (2) including at least the microwave transistor (2a) in an array form, and the characteristic measurement electrode () formed on the GaAs wafer (1). 4a, 4b, 4c), the characteristics of the microwave transistor (2a) are measured, a passive circuit (3) such as the distributed constant matching circuit corresponding to the characteristics is designed, and the passive circuit (3) is And a step of forming the microwave integrated circuit by connecting to the microwave transistor (2, 2a).