JPH01184876A - Semiconductor device - Google Patents

Abstract

PURPOSE:To decrease the resistance of a gate electrode, and improve high frequency characteristics, by arranging a plurality of unit gate electrodes of narrow width in parallel, and forming a specified width of gate electrode. CONSTITUTION:A source electrode 2, a drain electrode 3 and a gate electrode 4 are formed on a semiconductor substrate 1, on a specified part of which an active layer is formed. A gate electrode 4 is made of heat-resistant metal like tungsten, and a specified electrode width of 300-2000mum is obtained, by arranging a plurality of unit gate electrodes having a specified width of 10-50mum in parallel. A source electrode 2 and a drain electrode 3 also are formed so as to correspond with the gate electrode arrangement. As a result, even if heat-resistant metal of high specific resistivity is used, the resistance of the gate electrode can be low, so that high frequency characteristics like noise characteristics can be remarkably improved. Further, since it is unnecessary to coat the heat-resistant metal with low specific resistivity metal like gold, the deterioration of Schottky characteristics can be avoided.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a semiconductor device, and more specifically, for example, a transistor having a gate electrode formed of a heat-resistant metal such as tungsten silicide, particularly a microwave This invention relates to a semiconductor device in which the same gate electrode structure is improved in a transistor used in an IC.

[Conventional technology]

Conventionally, semiconductor devices in which this type of gate electrode is formed of a heat-resistant metal such as tungsten silicide generally have a large gate resistance, and when applied to a microwave IC, for example, In order to avoid problems with high-frequency characteristics such as noise characteristics, in this case, a structure is generally created in which a low-resistance metal such as gold is further layered on top of a heat-resistant metal such as tungsten silicide, which serves as the gate electrode. In this way, the gate resistance is lowered.

FIG. 3 shows an outline of the plane pattern of a conventional semiconductor device configured as described above, and FIG. 14 shows a cross section taken along the line IV--IV in FIG. 3. .

That is, in the conventional configurations shown in FIGS. 3 and 4, reference numeral 11 (not shown) is a semiconductor substrate on which an active layer is formed at a predetermined portion thereof, 12 is a source electrode thereof, and 13 is a drain electrode thereof. , 14 indicates a gate electrode using a heat-resistant metal such as tungsten silicide, and these constitute a transistor as is known in the art. Ground conductor, 16 interlayer insulating film, 1
7 is a low resistance metal layer such as gold layered on the gate electrode 14.

At this time, the unit gate electrode width as the gate electrode 14 is usually formed to be about 100 to 200 μl, and the total gate electrode width in a transistor applied to a microwave IC etc. is 300~2000μ
It is made to about m.

However, in the case of transistors used in the microwave IC, especially transistors used in circuits that require low noise, the gate resistance and source resistance each have a large effect on the noise characteristics of the transistor. It is known.

In this case, the noise characteristics of the transistor can be expressed by the following equation. Namely.

blood F = 1+ and fT is Takumi ... - (1) ■ It is.

In this equation (1), F is the noise figure, K/ is the fitting parameter, JT is the frequency at which the current amplification is 1, f is the operating frequency, 3- is the mutual conductance, R) is the gate resistance, Rs is the source resistance.

Further, gate resistance R> can be similarly expressed by the following equation. Namely.

R1=Station P”3T/N (P=ni?/Gin・Yo) --
-----(2).

In this equation (2), K) is the gate metal resistivity, WET is the total width of the gate electrode, dl is the thickness of the gate electrode, Ilc# is the gate length, and N is the number of gate fingers.

In this case, the gate electrode of the transistor has a structure in which a plurality of the above-described unit gate electrodes 5 are arranged in parallel. When using gold, it is about 3Ω/mouth, and when using gold, a low resistance metal, it is about 0Ω.
．． 2Ω/mouth.

[Problem to be solved by the invention]

As mentioned above, conventionally, when applying a transistor using a gate electrode formed of a heat-resistant metal such as tungsten silicide to a microwave IC, etc., due to the large gate resistance, tungsten silicide or the like is used as the gate electrode. It is necessary to further layer a low-resistance metal such as gold on top of the heat-resistant metal to lower the gate resistance, which unavoidably complicates the manufacturing process of the device. There is a disadvantage that the manufacturing yield is also reduced, and on the other hand, the low resistance metal of the upper layer is
There was a problem that it could react with the underlying heat-resistant metal or diffuse into the heat-resistant metal, deteriorating its Schottky properties.

Therefore, an object of the present invention is to simplify the structure of the gate electrode using tungsten silicide or the like as much as possible, in view of such a bending point in the conventional device, and also to reduce the gate resistance. It was made possible to lower the An object of the present invention is to provide a semiconductor device of this type.

[Means to solve the problem]

In order to achieve the above-mentioned object, a semiconductor device according to the present invention provides a transistor structure having a gate electrode of a predetermined width formed using a heat-resistant metal such as tungsten silicide.
An assembly of individual unit electrodes having a predetermined width of about the same size as pus,
When a plurality of these unit gate electrodes are arranged in parallel and applied to a microwave IC, the desired three
The width of the gate electrode is about 00 to 2000 μm.

(Function) That is, in the present invention, it is formed using a heat-resistant metal such as tungsten silicide, and
By providing a unit gate electrode with a predetermined width on the order of μm, and increasing the number of gate fingers and arranging them in parallel, it is possible to achieve the desired width of 300 to 2000 μm when applied to microwave ICs. In order to obtain a gate electrode width of about 100%, it is possible to reduce the resistance of the gate electrode itself with an extremely simple structure, without having to layer a low-resistance metal such as gold on top of a heat-resistant metal such as tungsten silicide. , it is possible to significantly improve high frequency characteristics such as noise characteristics in transistors.

〔Example〕

Hereinafter, one embodiment of a semiconductor device according to the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 is a plan pattern diagram schematically showing the general structure of a semiconductor device to which this embodiment is applied, and FIG. 2 is a sectional view taken along line nn in FIG. 1 of the semiconductor device.

That is, in the embodiment configurations of FIGS. 1 and 2 as well, the reference numeral '1 indicates a semiconductor substrate in which each active layer is formed at a predetermined portion (although not shown), 2 is a source electrode, and 3 is a Drain electrode 4 is a heat-resistant metal 1, for example,
A gate electrode using tungsten silicide,
Each of these electrodes is arranged and formed in parallel with each other as expected on each of the active layers, and the gate electrode 4 is formed as a unit gate electrode having a predetermined width of about 10 to 50 μm. By arranging and forming a plurality of unit gate electrodes in parallel, this S can also achieve the desired 300 to 200
A gate electrode width of about 0μ is obtained, and
The source electrode 2 and the drain electrode 3 are also arranged and formed as expected, corresponding to the arrangement and formation of each gate electrode 4.

Furthermore, 2a is a wiring layer for interconnecting each of the source electrodes 2 through contact holes 2b;
3a is a wiring layer for interconnecting each of the drain electrodes 3; 4a is a wiring layer for interconnecting each of the gate electrodes 4 through contact holes 2b; 5 is a wiring layer on the back side of the substrate; A ground conductor 6 is provided on the substrate, and 6 is an interlayer insulating film formed on the substrate.

Therefore, in the transistor having the structure of this embodiment, a plurality of unit gate electrodes 4 each made of a heat-resistant metal and having a narrow width of about 10 to 50 μm are arranged in parallel and applied to a microwave IC. In order to obtain the desired gate electrode width of about 300 to 2000 μm in cases where There is no need to stack the gate electrode 4, and the structure is extremely simple compared to similar transistors.
The resistance of the transistor itself can be significantly lowered, and the high frequency characteristics such as the noise characteristics of the transistor can be greatly improved.As mentioned above, this can be easily applied to microwave ICs that require low noise characteristics. It can be made applicable.

In the above embodiments, the present invention is applied to the gate electrode of a transistor made of a heat-resistant metal. However, as long as the electrode is made of a heat-resistant metal, it can also be applied to a base electrode of a bipolar transistor, a diode, etc. It goes without saying that the substrates used in these target devices do not necessarily have to be semi-insulating substrates, but rather conductive substrates. It goes without saying that the present invention can be applied to any case, and similar effects and effects can be obtained in each case.

〔Effect of the invention〕

As detailed above, according to the present invention, in a transistor structure having a gate electrode formed using a heat-resistant metal, the gate electrode is a unit electrode having a predetermined width of about 10 to 50 μm, and the unit gate electrode is By arranging multiple wires in parallel to obtain the desired gate electrode width of about 300 to 2000 μm, the resistance of the gate electrode itself can be significantly reduced, which improves the noise characteristics of this type of transistor. In addition to being able to significantly improve high frequency characteristics, this method has excellent features such as being relatively simple in structure and easy to implement.

[Brief explanation of the drawing]

FIG. 1 is a planar pattern diagram schematically showing the general configuration of an embodiment of a semiconductor device according to the present invention, and FIG. 2 is a cross-sectional view taken along line nn in FIG. 1 of the semiconductor device, and FIG. FIG. 3 is a plan pattern diagram schematically showing the general structure of a conventional semiconductor device, and FIG. 4 is a sectional view taken along line IV--IV in FIG. 3 of the semiconductor device. 1... Semiconductor substrate, 2... Source electrode, 2a...
... Wiring layer of source electrode, 3... Drain electrode,
3a... Wiring layer for drain electrode, 4... Gate electrode, 4a... Wiring layer for gate electrode, 5... Ground conductor, 6... Interlayer insulating film. Agent Masuyo Oiwa” Figure 3 Figure 4

Claims (1)

[Claims] In a transistor structure having a gate electrode of a predetermined width formed using a heat-resistant metal such as tungsten silicide, the gate electrode of the predetermined width is an aggregate of individual unit electrodes each having a predetermined width of about 10 to 50 μm. When multiple unit gate electrodes are arranged in parallel and applied to microwave ICs, the expected
A semiconductor device characterized in that a gate width of about 2000 μm is obtained.