JP3499394B2 - Microwave integrated circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a microwave integrated circuit formed on a semi-insulating semiconductor substrate such as GaAs.

[0002]

2. Description of the Related Art In recent years, miniaturization of microwave solid-state circuits has
GaA semiconductors such as matching circuits and FETs for cost reduction
A monolithic microwave integrated circuit (hereinafter, MMIC) integrated on a semi-insulating semiconductor substrate such as s is widely used.

FIG. 4 is an equivalent circuit showing an example of an amplifier using a GaAs FET. In the figure, 401 is Ga
As FETs, 402 to 405 are transmission circuits forming a matching circuit, 406 and 407 are DC blocking capacitors, 41
0 is a stabilizing resistor.

A resistor denoted by reference numeral 410 in FIG. 4 is a FET.
FE used in MMIC connected in series to the gate electrode of
It has a function of absorbing characteristic variations of T401 and suppressing operations such as parasitic oscillation of FET. Normally, the resistance value is selected in proportion to the input impedance on the gate side of the connected FET, for example, in inverse proportion to the gate width.

To realize the above resistor, there are a method using a high resistance metal thin film, a method using a conductive region of a semiconductor and a pair of ohmic electrodes, and the like.
In many cases, a structure using a conductive region and a pair of ohmic electrodes is adopted because of good compatibility with the T process.

FIG. 5 shows a conventional example of a resistor having a structure using a conductive region and a pair of ohmic electrodes. In the figure, 501a and 501b are AuGe / Ni, for example.
, Respectively, and are opposed to each other at a constant interval to form a pair of ohmic electrodes. Reference numeral 502 in the figure denotes a conductive region selectively formed on the semi-insulating semiconductor substrate. This conductive region is formed, for example, by selectively implanting Si ions into a semi-insulating GaAs substrate.

In order to obtain a desired resistance value with the resistor having such a structure, the surface resistivity of the conductive region of the semiconductor is changed or the interval between the ohmic electrodes forming a pair (the length of the resistor) is changed. Alternatively, it can be realized by changing the length (B in the drawing, the width of the resistor) that overlaps the conductive region on the opposite sides of the ohmic electrode.

[0008]

In recent years, as the output power of MMIC has increased, the gate width of FET has become larger, and as a result,
The input and output impedances of the FET are low. Correspondingly, the resistance value required for the resistor of the matching circuit such as the stabilizing resistor is also low, and for example, for an FET having a gate width of 10 mm, a value of about 5 to 6 Ω is generally set. Required.

In order to realize a low resistance value with the resistor of the above-mentioned conventional example, the surface resistivity of the conductive region is lowered by increasing the impurity concentration, the electrode interval of the ohmic electrodes is narrowed, and the resistance is opposite. A low resistance value can be realized by increasing the length of the side. However, if the electrode interval is made too narrow, the yield will decrease due to a short circuit, or a high electric field will be generated when a voltage is applied, and this will lead to defects such as destruction. For this reason, in general, it is often not narrower than an interval of several microns.

Also, the surface resistivity of the conductive region does not decrease even if the impurity concentration is increased by a certain amount or more. Therefore, when a lower resistance value is required, the resistance value is lowered by increasing the length B of the opposite sides of the ohmic electrode. For this reason, a high output M that requires a low resistance value
In a MIC or the like, not only the FET is large due to the high output, but also the resistor as a matching element is large, resulting in a very large element area of the MMIC. For this reason, the degree of integration is not increased, which causes a decrease in yield and an increase in MMIC unit price.

The present invention solves the above-mentioned drawbacks and provides a microwave integrated circuit having a resistor having an active region and a pair of ohmic electrodes and having a structure capable of realizing a low resistance value in a small area. The purpose is to provide.

[0012]

[0013]

[0014]

[Means for Solving the Problems] To solve the above problems
The present invention relates to a microwave integrated circuit in which a semiconductor conductive region and a pair of ohmic electrodes are arranged in a desired region on a semi-insulating semiconductor substrate, and a spiral ohmic pair is formed on the semiconductor conductive region. It is characterized in that an electrode is formed.

[0015]

[0016]

Further, in a microwave integrated circuit in which a field effect transistor is arranged on a semi-insulating semiconductor substrate, and a conductive region of a semiconductor and a pair of ohmic electrodes are arranged in a desired region on the semi-insulating semiconductor substrate. A pair of spiral ohmic electrodes is formed on the conductive region of the semiconductor.

Further, a conductive region of a semiconductor formed by selective ion implantation on the semi-insulating semiconductor substrate is used.

[0019]

The pair of ohmic electrodes are AuGe / N.
i.

The pair of ohmic electrodes is AuGe / P.
and t.

The microwave integrated circuit according to the present invention constitutes a pair of electrodes in which ohmic electrodes are alternately opposed to each other, and has, for example, a spiral structure. Therefore, the length of the electrodes facing each other can be increased in the same area as the conventional one, and low resistance can be realized in a small area.

[0023]

1 is a plan view showing an embodiment of the present invention. In FIG. 1, 101a and 101b are a first ohmic electrode and a second ohmic electrode made of, for example, AuGe / Ni, which are opposed to each other in a comb shape at regular intervals to form a pair of ohmic electrodes. is doing. Further, 102 in the figure is a conductive region selectively formed on the semi-insulating semiconductor substrate. This conductive region is formed by selectively implanting Si ions into a semi-insulating GaAs substrate, for example.

A pair of ohmic electrodes 101a and 101b
Can be formed using the pattern of the source electrode and drain electrode of the FET. Therefore, a resistor having a low resistance value can be realized in a small area without increasing the number of manufacturing steps.

As shown in the figure, in the resistor according to the present invention, a pair of ohmic electrodes face each other in a comb shape. Therefore, the length corresponding to the length B of the facing sides in the conventional example is obtained by multiplying the length A by the number n of facing electrode pairs facing each other in a comb shape (4 pairs in the embodiment in the drawing). The length is A × n. Therefore, for example, in order to realize a resistance value of 5Ω, an area of about 3500 μm ² was required in the case of the conventional example, but according to the present invention, when the number of facings is 4, it becomes 1000 μm ² , which is an area. A reduction of about 70% is possible. Therefore, a lower resistance value can be realized in the same area as compared with the conventional example.

FIG. 2 shows another embodiment according to the present invention.
Shown in. In this case, the electrodes at both ends of the comb-teeth type ohmic electrode are longer than those in the example of FIG. 1, and the conductive regions are formed in all the comb-teeth type gaps. Therefore, the opposing length can be made longer than A × n in the case of FIG. 1, so that lower resistance can be realized in the same area.

In the present invention, the FET is formed on the same semi-insulating semiconductor substrate, but it is omitted in the description. FETs not shown often form opposing comb-teeth type electrodes, and the pair of ohmic electrodes 101a and 101b are FE.
It can be formed by utilizing the pattern of the T source electrode and the drain electrode. Therefore, it is possible to realize a resistor having a low resistance in a small area without increasing the number of manufacturing steps.

Another embodiment of the present invention is shown in FIG. In the above description, the case where the pair of ohmic electrodes are comb-teeth type has been described, but the present invention can be implemented even when the pair of ohmic electrodes has the spiral shape shown in FIG.

Thus, according to the present invention, with the same area,
Since a resistance value lower than the conventional one can be realized, a resistor having a higher degree of integration can be provided. Therefore, the microwave integrated circuit having the same function can be realized on a small semiconductor substrate, and the manufacturing cost can be reduced.

Although AuGe / Ni is used as the ohmic electrode in the above embodiment, AuGe / Pt may be used and the semi-insulating substrate may be InP instead of GaAs. The method of forming the conductive region is not limited to the ion implantation method, and the present invention can be implemented.

It is apparent from the above description that the number of branched electrode branches, the length of the electrode branches, and the shape of the conductive region are not limited to those shown in FIGS. 1 and 2. Further, the shape of the spiral is not limited to the shape shown in FIG.

[0032]

According to the present invention, since a low resistance value can be realized in the same area, a resistor having a higher degree of integration and a microwave semiconductor having a higher degree of integration can be provided.

[Brief description of drawings]

FIG. 1 is a plan view illustrating the present invention.

FIG. 2 is a plan view illustrating the present invention.

FIG. 3 is a plan view illustrating the present invention.

FIG. 4 is an equivalent circuit diagram of an amplifier using a conventional FET.

FIG. 5 is a plan view illustrating a conventional example.

[Explanation of symbols]

101a ... First ohmic electrode 101b ... second ohmic electrode 102 ... Conductive region A ... Length A 201a ... First ohmic electrode 201b ... second ohmic electrode 202 ... Conductive area 301a ... First ohmic electrode 301b ... second ohmic electrode 302 ... Conductive area 401 ... GaAs FET 402-405 ... Transmission line 406, 407 ... DC blocking capacitors 408, 409 ... Capacitor for high frequency short circuit 410 ... Stabilizing resistance 501a ... First ohmic electrode 501b ... Second ohmic electrode 502 ... Conductive area B ... Length B

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 27/04 H01L 21/822

Claims (5)

(57) [Claims] 1. A desired region on a semi-insulating semiconductor substrate,
In a microwave integrated circuit in which a conductive region of a semiconductor and a pair of ohmic electrodes are arranged, a vortex is formed on the conductive region of the semiconductor.
A microwave integrated circuit comprising a pair of spiral ohmic electrodes. 2. A field effect transistor on a semi-insulating semiconductor substrate.
In a microwave integrated circuit in which a transistor is arranged and a conductive region of a semiconductor and a pair of ohmic electrodes are arranged in a desired region on the semi-insulating semiconductor substrate, a pair of spiral ohmic layers is formed on the conductive region of the semiconductor. A microwave integrated circuit having a conductive electrode. 3. A selective ion on the semi-insulating semiconductor substrate.
Using conductive regions of the semiconductor formed by ion implantation
The microwave integrated circuit according to claim 1 or 2, wherein: 4. The pair of ohmic electrodes is made of AuGe / Ni.
The microwave integrated circuit according to claim 1 or 2, further comprising: 5. The pair of ohmic electrodes is AuGe / Pt.
The microwave integrated circuit according to claim 1 or 2, further comprising: