JPS59114826A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To facilitate reduction of width of patterns of electrodes and so forth, especially submicronization of that by a method wherein a second conductive film 2 having larger directivity than a first conductive film 1 is formed on the first conductive film, after which the exposed area of the first conductive film is selectively removed using the second conductive film as a mask. CONSTITUTION:An SiO2 film 4 is etched using a resist film 5 as a mask and further N type operation layer 2 is etched. Next, a first metallic film 6 form a Schottky contact for N type operation layer 2 is formed on the surface of said layer 2 under the resist film 5 and the opening of the film 5. A second metallic film 7 of low resistance and being suitable for forming electrodes is formed on the first metallic film 6 by making method of large directivity. After the resist film 5 is stripped to be removed, the exposed area of the first metallic film 6 is removed using the second metallic film 7 as a mask. Thus the gate electrode composed of the first metallic film 6 and the second metallic film 7 is formed. After that, the SiO2 film 4 is removed and a protective insulating film 8 consisting of SiO2 or the like is newly formed and a necessary wiring 9 is arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and in particular, to a method for manufacturing a semiconductor device, in particular a pattern width of 1 [
The present invention relates to a manufacturing method, such as polarization, suitable for achieving a polarization of less than 1 μm.

(b) Background of the Technology As a microwave conductor device, an incillary field effect transistor (hereinafter abbreviated as GaAs MESFET), which is made of gallium-arsenide compound (GaAs) as a semiconductor material, is generally used. This is because the carrier mobility of GaAs compound semiconductors is much higher than that of silicon (Si), etc., and also because Schottky barrier field effect transistors have a simpler structure and manufacturing process than other semiconductor devices. This is because the GaAs MESFET provides excellent high frequency characteristics because it is suitable for miniaturization of length.

That is, in a GaAs MES FET, by shortening the gate length, the cutoff frequency and maximum oscillation frequency can be increased in approximately inverse proportion to the gate length.

It is also known that the minimum noise figure is approximately inversely proportional to the cutoff frequency and proportional to the frequency. On the other hand, for bipolar transistors, the minimum noise figure increases in proportion to the square of the frequency, so GaAs MES FETs are also superior to bipolar transistors as low-noise amplification elements in the microwave band.

(c) Problems with the Prior Art In order to maximize the excellent high frequency characteristics of GaAs MES FETs, which have the above-mentioned features, efforts are being made to shorten the gate length to the submicron region.

This technology, which is generally called ultra-fine processing, is a combination of resist patterning technology and etching technology that faithfully forms electrodes, semiconductor regions, etc. on the semiconductor substrate using the patterned mask. As a result of Shusho's efforts, development is progressing strongly in various fields such as resist materials and methods of use for ultrafine processing, phosphorography methods such as electron beam exposure, and etching techniques using dry processes.

However, in order to implement these technologies industrially, there are many problems that need to be solved, such as the flatness of the semiconductor substrate surface, and the gate length in the mask is 0.5 [μm].
Even if obtained, the gate length of semiconductor confectionery is 0.8 [μm]
It is extremely difficult to realize this over the entire surface of a semiconductor substrate using conventional methods that utilize light.

Conventionally, GaAsMES has been commonly used as a means of shortening gate length.
Instead of aluminum (At), which is used as a gate material for FETs, two or more metal layers are stacked using, for example, molybdenum (Mo)-gold (Au), and the top layer metal is masked. A manufacturing method in which the underlying metal is side-etched has been proposed. However, in this method, control before etching is difficult, and fluctuations in gate length and therefore FET characteristics become extremely large.

Under the current situation as described above, there is a demand for a manufacturing method that can immediately implement submicronization of patterns such as the gate electrode length of GaAs MES FETs.

(d) Purpose of the Invention An object of the present invention is to provide a manufacturing method that can easily reduce the pattern width of electrodes, etc. of a semiconductor device, and in particular can easily realize submicron pattern width.

(e) Structure of the Invention The object of the present invention is to provide a first film on a semiconductor substrate;
forming a second film in contact with the first film, providing a required opening in the second film and selectively removing the first film using the second film as a mask; Thereafter, a first conductive film is formed on the exposed surface of the semiconductor substrate, and then a second conductive film is formed on the first conductive film with greater directivity than the first conductive film, and at least the This is achieved by a method for manufacturing a semiconductor device, which includes the step of selectively removing exposed portions of the first conductor film using the second conductor film as a mask after removing the second conductor film.

(f) Embodiments of the Invention The present invention will be specifically described below by way of embodiments with reference to the drawings. 1 to 5 are cross-sectional views showing an embodiment of the present invention related to a GaAa METFET. See FIG. (AuGe)/Gold (A
Source/drain electrodes 3.3' are provided using u).

Next, an insulating film 4 made of, for example, silicon dioxide (Si02) is formed to a thickness of about 0.5 [μm] to cover the surface of this semiconductor substrate.

Refer to FIG. 2. A resist film 5 is coated on the 5in2 film 4 to a thickness of, for example, 0.7 [μ].
m], and the opening of the gate electrode pattern is formed by phosphorography with a width of 1 [μm] in the gate length direction, for example.

Next, using the resist film 5 as a mask, the SiO2 film 4 is etched using a mixed solution of, for example, hydrofluoric acid (HF) and ammonium fluoride (NH, F). Furthermore, the n-type active layer 2 is etched using, for example, a diluted mixture of hydrofluoric acid (HF) and hydrogen peroxide (H2O).

The source-drain current IDS is often controlled by such selective removal of the active layer 2.

See Figure 3. For example, tungsten silicide (WHS) can be produced using a less directional manufacturing method such as sputtering.
A first metal film 6 that forms a Schottky contact with the n-type active layer 2 is formed on the resist film 5 and the surface of the n-type active layer 20 between the openings of the resist film 5, as shown in FIG.

By forming the first metal film 6 using a less directional method such as a sputtering method, it is deposited on the etched cross section of the resist film 5 to approximately the same thickness as on the surface parallel to the substrate surface. do.

In this embodiment, this thickness is approximately 0.2 [μm].

Next, a second metal film 7 made of, for example, gold (Au), which has low resistance and is suitable for forming an electrode, is formed on the first metal film 6 by a highly directional manufacturing method such as a true steaming method. The width of the second metal film 7 at its bottom is approximately equal to the opening interval of the first metal film 6 deposited on the resist film 5. That is, in this example, the width is approximately 0.6
[μm].

After peeling and removing the resist film 5 (see FIG. 4), for example, carbon tetrafluoride (
The exposed portion of the first metal film 6 is removed using the second metal film 7 as a mask by a plasma etching method using a gas containing CF4) and oxygen (02). As a result, a gate electrode consisting of the first metal film 6 and the second metal film W7 is formed. In this embodiment, the gate length is approximately 0.6 [μm].

Refer to FIG. 5. The SiO2 film 4 is removed, a protective insulating film 8 made of 8102 or the like is provided again, and necessary wiring 9 is provided.

The embodiment described above is a so-called recess-type FET in which the thickness of the n-type active layer 2 in the gate electrode forming part is reduced, but the 5iC
The present invention can be implemented in a similar manner by setting a spacer layer such as the h-film 4 to a required thickness.

(g) As described in detail, according to the present invention, it is possible to industrially easily realize electrodes of semiconductor devices having a pattern width of about 1 [μm] or less, such as the gate a of an FET, for example. In addition, it is possible to manufacture semiconductor devices with excellent high-frequency characteristics and high-speed switching characteristics by controlling reproducibility.

[Brief explanation of the drawing]

Figures 1 to 5 show GaAs MES FETs with 75-
; In Figure 0, which is a cross-sectional view showing an embodiment of the present invention, 1 is a GaAs substrate, 2 is a nanometer dynamic i'F I'@
. 3.3' is the source/drain electrode, 4 is the 5jCh film,
5 is a resist film, 6 is a first metal film, 7 is a second metal film, 8 is a protective insulating film, and 9 is a wiring.

Claims (1)

[Claims] A first film and a second film in contact with the first film are formed on the semiconductor substrate, a required opening is provided in the second film, and the second film is used as a mask to form the second film. A first conductive film is selectively removed, a first conductive film is then formed on the exposed surface of the semiconductor substrate, and a second conductive film is formed on the first conductive film with greater directivity than the first conductive film. the second conductive film is formed, and after removing at least the second conductive film, the exposed portion of the first conductive film is selectively removed using the second conductive film as a mask. A method for manufacturing a semiconductor device.