JPH02181936A - Formation of fine electrode - Google Patents

Abstract

PURPOSE:To prevent an electrical characteristic in an electrode part from being deteriorated even when a width of an insulating film deciding an electrode-length size is made small and to prevent a yield from being lowered by a method wherein an interface of a semiconductor substrate in which the electrode is formed is formed so as not to come into contact with a resist. CONSTITUTION:An insulating film 11 deciding a gate-length size is formed on a semiconductor substrate 10; a resist 12 does not come into direct contact with the substrate 11 in a part in which a gate electrode is formed; a yield is not deteriorated by a residual scum of the resist. In order to form a pattern, for upper-part electrode use, which reduces a resistance, the insulating film 11 is exposed by using an ion beam whose energy has been controlled; the film is etched to an extent that a resist pattern does not reach the semiconductor substrate 10. Then, the insulating film 11 is removed; an electrode metal 16 is evaporated; a T-shaped electrode can be formed by a lift-off method. The gate-length size of the obtained T-shaped electrode and a size of the upper- part electrode are exposed to light individually; since their sizes are controlled separately, they can be set to arbitrary values.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a method for forming micro electrodes, and particularly to a method for forming micro electrodes with a T-shaped cross section with reduced resistance.

[Prior Art] Conventionally, as a method for forming electrodes to reduce the resistance of fine electrodes,
A method described in Japanese Patent Publication No. 61-77370 entitled "Pattern Formation Method" is known. The formation method described in the above publication was used as the second method.
Shown in Figures (a) to (C). That is, as shown in FIG. 2(a), a low-sensitivity positive resist 21 is first applied to the semiconductor substrate 20.
Then, a high-sensitivity positive resist 22 is coated on the low-sensitivity positive resist 21, and an electron beam 23 is applied on top of the low-sensitivity positive resist 21.
Expose to light. Next, after developing and forming a 1-shaped resist pattern, a metal 24 is formed as shown in FIG. 2(b).
and removing the resist 21, 22 and the deposited metal 24 on the resist 22 by organic cleaning.
As shown in FIG. 2(C), a TV-type electrode 25 is formed to reduce electrode resistance.

[Problems to be Solved by the Invention] Although the above-described formation method is improved over electrodes formed using conventional single-layer resist in that the resistance of the electrode can be reduced, the gate length is Since it is determined by the width, as the resist thickness increases, the value decreases to 0.
It becomes difficult to obtain a gate length of 25/1ffl or less.

In addition, since the resist is directly coated and formed on the semiconductor substrate, as the resist opening becomes smaller, some resist remains in the opening.
In the formation of electrodes below the rabbit level, there was a problem in that the contact between the electrodes and the semiconductor substrate was poor, resulting in deterioration of electrical characteristics and yield.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for eliminating such conventional drawbacks and forming an electrode with reduced resistance with a high yield.

[Means for Solving the Problems] The present invention involves forming a silicon dioxide insulating film on a semiconductor substrate, and patterning the insulating film to form an insulating film pattern leaving a desired dimension corresponding to the drooping portion. a step of forming a positive resist on the insulating film pattern; and a step of forming a positive resist on the insulating film pattern; A step of locating the insulating film pattern by exposing and developing a predetermined area corresponding to the upper dimension of the electrode centering on the film pattern, and removing the oriented insulating film pattern by wet etching. a step of vapor depositing an electrode metal; and a step of removing unnecessary metal on the resist 1 and above the resist 1 to form a metal pattern having a T-shaped cross section. Electron (*This is the formation method.

[Function] In the present invention, since the insulating film that determines the gate length is formed on the semiconductor substrate, and the substrate is not in direct contact with the regime 1~ in the gate electrode forming area, yield is reduced due to resist scum remaining. No deterioration occurs. Regarding the formation of the upper electrode pattern to reduce resistance,
Etching is performed using an energy-controlled ion beam to the extent that the insulating film is exposed and the resist pattern does not reach the semiconductor layer. Next, by removing the insulating film and depositing an electrode metal, it becomes possible to form a single-shaped electrode using a lift-off method. The gate length dimension and the upper electrode dimension of the single-shaped electrode, which are iq, are each exposed independently and the dimensions are controlled separately, so they can be set to arbitrary values.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIGS. 1(a) to (()) are schematic cross-sectional views of an electrode part showing an embodiment of the present invention in the order of steps. First, FIG. 1(a)
As shown in the figure, silicon dioxide (Si0
2) The insulating film 11 is formed to a thickness of 2,000 to 5,000 wafers, and then a negative resist 12 is coated on the insulating film 11. Next, as shown in FIG. 1(b),
After exposing and developing the negative resist 12, using the remaining negative resist 12 as a mask 1;3, the exposed insulation 1tA11 is removed by etching, and the insulation 11 under the mask 13 is replaced with a dummy gate. 14.

Thereafter, as shown in FIG. 1C, after removing the negative resist used as the mask 13 by oxygen (02) plasma and organic cleaning, the positive resist (for example, P
MMA) 15 is coated on the semiconductor substrate 10 to a thickness of 1βm so as to cover the dummy gate 14 formed of an insulating film. Next, it includes the dummy gate 14 in the center and reaches up to the dummy gate 14, but the substrate 1
The positive type resistors 1 to 15 are exposed with an ion beam 18 having a range that does not reach zero. For example, if PMMA is used as the positive resist 15, 260 keV,
When the ion energy and ion species of S + are 0.8
The range is 1 JIn. By doing so, after development, as shown in FIG. 1(d), a groove pattern 19 that does not reach the substrate 10 can be formed, and it is possible to locate the dummy goose 1 to 14.

Next, as shown in FIG. 1(e), the dummy gate 14 is removed by etching. Next, as shown in FIG. 1 ([), the electrode metal 16, for example aluminum (Aβ)
Deposit. Next, as shown in FIG. 1 (()), the positive type resist 15 and the unnecessary electrode metal 16 on the resist 15 are removed by organic cleaning or oxygen (02) plasma, thereby forming a cross section T. Shape low resistance electrode 1
You can get 7.

Note that the ion species and energy described in the above example are just examples, and as long as the ion species has a range that allows the dummy gate to be located in a predetermined regime l~thickness, Be ions in addition to 3i ions can be used. or Au ions, etc., and the energy is 100 to 300 keV depending on the thickness of the resist.
It is variable between.

Further, the metal may be any other material that can be used as an electrode, such as titanium (T i ), platinum (Pt), gold (Au), or a combination thereof.

[Effects of the Invention] As explained above, according to the method for forming a fine electrode of the present invention, the interface of the semiconductor substrate on which the electrode is formed is not in contact with the resist, so the width of the insulating film, which determines the length of the electrode, can be reduced. However, the electrical characteristics of the electrode portion do not deteriorate or the yield decreases.

In addition, since the exposure that determines the electrode length and the exposure that forms the overhanging claw are controlled separately, the electrode length can be set to 0.251, for example.
Even if the length is shorter than JIn, the dimensions of the lower part of the electrode and the protrusion of the upper part can be freely controlled, making it possible to form electrodes 1~ with sufficiently low resistance.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an electrode part showing an example of the present invention in the order of steps, and FIG. 2 is a schematic cross-sectional view of the electrode part showing a conventional method of forming a fine electrode in the order of steps. , 20... Semiconductor substrate 11... Insulating film 1
2... Negative resist 13... Mask 14.
...Dummy gate 15...Positive resist 16...
Electrode metal 17...cross section T'? - type low resistance electrode 18...Ion beam 19...Interval pattern 21...Low sensitivity positive resist 22...High sensitivity positive resist (~ 23...Electron beam 24...Vapor deposited metal 2
5...to Den 4

Claims (1)

[Claims] (1) A step of forming a silicon dioxide insulating film on a semiconductor substrate, patterning the insulating film to form an insulating film pattern leaving a desired dimension corresponding to the lower part of the electrode, and applying a positive resist on the insulating film pattern. and forming a predetermined area corresponding to the upper dimension of the electrode around the insulating film pattern with an ion beam of energy having a range that does not reach the semiconductor substrate but reaches the insulating film pattern. A step of locating the insulating film pattern by exposure and development, a step of removing the locating insulating film pattern by wet etching, a step of vapor depositing an electrode metal, and a step of removing the resist and unnecessary material on the resist. A method for forming a microelectrode, comprising the step of removing metal to form a metal pattern having a T-shaped cross section.