JPH01243430A - Etching method for molybdenum silicide - Google Patents

Abstract

PURPOSE:To enable the easy formation of a fine pattern, by using resist containing Si as a mask, and using Cl2 gas as etching gas. CONSTITUTION:Resist containing Si is used as a mask at the time of etching, and Cl2 gas or mixed gas of Cl2 gas and O2 gas is used as etching gas. That is, the resist containing Si has large resistance to O2 reactive ion etching (RIE). Resist, wherein Si content is large and the composition of the skeletal structure of polymer is approximate to SiO2 has resistance also to RIE using chlorine gas. Thereby, the selection ratio of the etching rates of molybudenum silicide to SiO2, as well as the selection ratio of molybudenum silicide to the etching mask can be made large at the same time, so that the fine pattern formation can be easily realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for etching molybdenum silicide used in the manufacture of electronic devices.

[Prior Art] Conventionally, polysilicon has been most commonly used as the gate electrode material for silicon MOS transistors.
As device patterns become finer, there is a need to reduce the resistance of gate electrode materials, and in recent years molybdenum silicide has been used as a low-resistance electrode material. Anisotropic etching of molybdenum silicide was carried out using a parallel plate internal electrode type RF discharge reactive ion etching (RIE) device using an organic photoresist consisting of novolac resin and diazonaphthoquinone as an etching mask.
)tL, CF3Cl! , CF2 Cj! 2.CFCJ
! By using a gas containing C and F, such as a+Q2, that contains a large amount of U for removing C, anisotropy can be achieved due to the sidewall protection effect of the organic photoresist and the gas containing C and F. Etching has been achieved.

[Problems to be Solved by the Invention] However, when a halogenated carbon containing C and F is used as an etching gas, it is difficult to increase the etching rate selectivity between molybdenum silicide and 5i02. In order to increase the selectivity with 5i02, it is possible to use α2 alone, which does not contain C or F, but with CJlz alone, it is necessary to increase the selectivity of the etching rate between molybdenum silicide and organic photoresist. As a result, variations in pattern dimensions occur in fine patterns.

Therefore, in the conventional method, molybdenum silicide and 5i0
It is not possible to obtain a large selectivity in etching rate with respect to etching rate No. 2 and organic photoresist, and therefore it has been difficult to form fine patterns of molybdenum silicide, not only gate electrodes, but also molybdenum silicide.

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned conventional problems and provide an etching method suitable for forming fine patterns of molybdenum silicide.

[Means for Solving the Problems] The present invention provides a method for etching molybdenum silicide by etching molybdenum silicide by reactive etching or electron cyclotron resonance plasma etching, in which a Si-containing resist is used as a mask during etching of molybdenum silicide. , Cl2 gas or C as an etching gas for molybdenum silicide.
This is a molybdenum silicide etching method characterized by using a mixed gas of 12 gas and 02 gas.

[Effect] Si-containing resists have high resistance to 02RIE, but they have a high Si content, especially when the composition of the polymer skeleton structure is 5.
Those close to i02 are also resistant to RIH using chlorine-based gas. Therefore, a Si-containing resist is used as an etching mask instead of an organic photoresist, and C
By using a chlorine-based gas such as 12 as the etching gas for molybdenum silicide, it is possible to increase the etching rate selectivity between molybdenum silicide and 5i02, and at the same time increase the selectivity between molybdenum silicide and the etching mask. This makes it easier to form fine patterns of molybdenum silicide than with conventional methods. Furthermore, by adding 02 to α2, carbon, hydrogen, etc. in the S1-containing resist react with 02 and are removed from the resist, thereby further increasing the etching rate ratio between the Si-containing resist or 5i02 and molybdenum silicide. It can be made large.

[Example] Next, embodiments of the present invention will be described in detail.

In this example, the Si-containing resist has a molecular weight of 7000. m and n in the formula are 15 to 20
I used the one from The Si content in this Si-containing resist is about 28 weight percent, and the polymer skeleton is silsesquioxane, which is close to the 5i02 composition.

First, about 100 layers of 5i02 were formed on a Si substrate by thermal oxidation, and then 5000 layers of molybdenum silicide were deposited by sputtering. On the molybdenum silicide substrate thus prepared, 20% of the St-containing polymer was applied.
% isoamyl acetate solution was applied by spin coating at 400 rpm, and then baked at 80° C. for 10 minutes. The resist film thickness at this time was 4,500.

After electron beam exposure was performed using a variable rectangular electron beam exposure machine, development was performed with isopropyl acetate. The exposure amount at this time was 70 μC/Cm2, and the development time was 1 minute.

Using the Si-containing resist patterned in the above steps as an etching mask, the parallel plate internal electrode type R
Anisotropic etching of molybdenum silicide was performed using an F discharge reactive ion etching device. The etching conditions at this time were: gas flow rate C1230sec, gas pressure 1
The power density was 0 Pa and the power density was 0.2 W/cm2. The etching speed when etching under these conditions was 1100 etching/min for molybdenum silicide and 90 etching/min for Si-containing resist.

It was about 70 people/min for 5i02. For 5,000 pieces of molybdenum silicide, the base layer 5i02 appeared by etching for 4 minutes and 30 seconds, and then by over-etching for 30 seconds, an anisotropic shape of molybdenum silicide was obtained.

Next, an example will be described in which a Si-containing resist patterned by the electron beam exposure process is applied to electron cyclotron resonance microwave plasma etching. The etching gas was (j!2203CCm, the gas pressure at this time was 5 x 10'Pa, and the microwave input was 80
0W, and bias RF power 20 on the substrate stage side.
− was applied. Etching speed is 2800 people/min for molybdenum silicide, 110 people/min for s+ containing resist, 90 people/min for 5io2.
It was about min. Electron cyclotron resonance plasma etching is originally an etching method with good processing accuracy, low damage, and low contamination. By the method of this example, for 5000 molybdenum silicides, the base 5i02 appeared in 2 minutes of etching, and then 15 An anisotropic shape of molybdenum silicide was obtained by over-etching for seconds.

Next, α is used as an etching gas for reactive ion etching.
An example in which a 2+02 mixed gas is used will be described. Cj as gas flow rate! 225SCCm1025s
ecm, gas pressure is 10 Pa, and power density is 0.2 W.
/cm2, the etching speed is 1020 etching/cm2 for molybdenum silicide, 75 etching/min for Si-containing resist, and 60 etching/min for 5io2, and by adding 02, the etching rate can be increased. I was able to make it bigger.

By the above method, a molybdenum silicide gate electrode with a pattern width of 0.35 μs could be formed.

In addition, since Cl2 gas can also be used as an etching gas for polysilicon, etching of polycide consisting of two layers of polysilicon and molybdenum silicide can be performed simultaneously with a high selectivity with 5i02. Ta.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a large etching rate selectivity between molybdenum silicide, 5i02, and the etching mask, and thus it is possible to easily form fine patterns of molybdenum silicide such as gate electrodes. In addition, by using a mixed gas of C12 gas and 02 gas as the etching gas, it is possible to greatly increase the above-mentioned selectivity.

In addition, etching of polycide consisting of 2M of polysilicon and molybdenum silicide is performed using S! It can be performed simultaneously with a large selection ratio with 02, and has the effect of simplifying the gate electrode formation process.

Claims (2)

[Claims] (1) In a molybdenum silicide etching method in which molybdenum silicide is etched by reactive etching or electron cyclotron resonance plasma etching, a Si-containing resist is used as a mask during etching of molybdenum silicide, and Cl_2 gas is used as an etching gas for molybdenum silicide. A method of etching molybdenum silicide, characterized in that it is used. (2) In a molybdenum silicide etching method in which molybdenum silicide is etched by reactive etching or electron cyclotron resonance plasma etching, a Si-containing resist is used as a mask during etching of molybdenum silicide, and Cl_2 gas is used as an etching gas for molybdenum silicide. A method for etching molybdenum silicide, characterized by using a mixed gas with O_2 gas.