JPS6154630A - Dry etching process - Google Patents

Abstract

PURPOSE:To improve the dimensional precision of pattern and coating property of step difference while changing the sectional shape of processed silicide by a method wherein the concentration of O2 gas mixed with F base main gas is changed remarkable. CONSTITUTION:Electrodes 4, 5 are arranged in an airtight chamber 3 and after grounding the electrode 5, temperature controlling solution is circulated in a vessel 7 to control temperature. The gas flow rate controlled 8 and properly mixed by operating valves 9 is fed to the chamber 3 to be exhausted 10. The electrodes are supplied with high frequency voltage under specific pressure to cause plasma discharge for etching the film on wafer 11. When etching e.g. MoSi2 utilizing CF4O2 gas, if anisotropic etching is performed with O2 gas concentration of around 40%, pattern with the same dimension L as that of resist mask is formed while with O2 gas concentration of around 10%, tappered etching may be performed to improve the coating property of upper film while if O2 concentration is reduced, anisotropic etching sidewall of lower layer 25 with large step difference may be perfectly performed leaving no residual nonetched part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a dry etching method for etching silicide in a semiconductor manufacturing process.

[Background of the invention]

Improvement of silicide etching technology in the semiconductor manufacturing process is an important matter that greatly influences the realization of higher integration and higher speed of semiconductor devices.

This etching is performed using a plasma of 02 gas and a fluorine-based main gas such as CF4, SF, NF, etc., and it has been known that the concentration of 02 gas is a parameter that greatly influences the etching rate of silicide. However, the details of the processed shape of silicide were not known. In addition, the etching of chrysanthemum is explained in detail in the following literature.

(i) RIEJ of r Po1y-8i'/Ta5iz
W, Beinuogl.

B, ) (aster, J, una, 1983.5o
lid 5tateTehnol.

(2) [81g using a low frequency excitation parallel plate reactor]
Etching of polycide structure by glow discharge JM,
1. Co@, 8. H, Rogers, 0ctob
Er.

1983.5olid 5tate Technol.

(3) “RI El Hisaku Nishioka 0cto with polycide structure
ber.

1983, 8emieonduetor World
[Object of the invention] The present invention has been made in view of the above circumstances.
The purpose is to provide a dry etching method for silicide that can control the processed shape of silicide and flexibly respond to the characteristics and processes of semiconductor devices.

[Summary of the invention]

In order to achieve such an objective, the present invention is based on the results of analyzing the influence of 02 gas concentration on the processed shape of silicide, and the present invention independently controls the flow rate of two or more gases in a chamber and mixes them simultaneously. Using an etching device that can introduce gas, the line width and cross-sectional shape of the silicide can be controlled by changing the O2 gas concentration.

[Embodiments of the invention]

Next, the present invention will be explained in detail using examples.

FIG. 1 is a block diagram of a dry etching apparatus showing an embodiment of the present invention. In the figure, a chamber 3 is attached to a stage 1 in an airtight manner via an O-ring 2, and an upper electrode 4 and a lower electrode 5 are arranged inside the chamber 3. A high frequency power source 6 is connected between both electrodes, and the lower electrode 5
is grounded. Further, the lower electrode 5 has a temperature control tank 7,
Temperature-controlled liquid is constantly circulated.

Gas is supplied to a plurality of (three in the illustrated example) mass flow controllers (MFC) 8A to 80! - are supplied into the chamber 3 by opening the valves 98 to 9C with their flow rates controlled.In etching silicide, for example, the flow rate of CFa, etc. is controlled by MFC8A.
The flow rate of 02 is controlled by F08B, and the mixture is mixed before reaching chamber 3 and supplied to chamber 3. Although omitted in the figure, exhaust is performed through the exhaust port 10 by a vacuum exhaust device. After the pressure in the chamber 3 stabilizes to the set etching pressure, a high frequency voltage is applied between the two electrodes by the high frequency power supply 6, causing plasma discharge between the two electrodes, and a chemical reaction and a physical reaction occur on the wafer 11. The film deposited on the surface is etched.

Here, CF4, SF'6. The cross-sectional shape of the processed silicide varies greatly depending on the concentration of the 02 gas added to the main gas such as NF. For example, in Figure 2, CF4 has 02
silicide (data Mo51) using a gas mixed with
This figure shows the relationship between the taper angle θ of the cross section of the silicide film 21 with respect to the lower layer film 22 and the OX gas concentration (0!/CF4 +02) when etching the silicide film 21 shown in FIG. However, by changing the OX gas concentration from 10 degrees to 40 degrees, the taper angle of the silicide can be changed from 30 degrees to 90 degrees.

Therefore, in cases where the pattern dimensions need to be strictly controlled, such as the gate part of Mo8, the zero snow gas concentration is increased to around 40 inches, and completely anisotropic etching without tapering is performed. As shown in FIG. 4, gate dimensions equivalent to those of the resist pattern 23 can be obtained.

In addition, as shown in FIG.
In an element structure where disconnection is a problem at the stepped portion, step coverage of the upper layer film 24 can be improved by mixing a small amount of 02 gas (approximately 15 cm) and etching to create a taper, as shown in FIG. It can be improved. In addition, t and t3 in the figure are the film thicknesses of the upper layer film 24 at the step portion, and 11<1. It is.

Furthermore, in a process using an element cross-sectional structure with a large step difference in the lower layer 25 as shown in FIG.
Although an unetched portion remains as shown by the dashed dotted line, if the zero gas concentration is controlled to a small amount as described above, this residual portion can be eliminated as shown in FIG. 2(b).

〔Effect of the invention〕

As explained above, according to the present invention, O! By changing the concentration of gas,
It is possible to control the processed cross-sectional shape of silicide, improve pattern dimensional accuracy and step coverage, and make it possible to achieve higher integration and speed of semiconductor devices.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a dry etching apparatus showing an embodiment of the present invention, and FIG. A diagram showing the relationship between gas concentration and the taper angle of a processed cross section of silicide, FIG. 3 is a cross-sectional view for explaining the taper angle, and FIGS. 4 to 6 are cross-sectional views for explaining the effects of various embodiments. It is a diagram. 3...chamber, 4...upper electrode, 5...φ
Lower electrode, 8A to 8C... Mass flow controller, 9A to 9C... Valve, 11... Group wafer, 2
1... Silicide film, 22--, Lower layer film, 23-
..., resist pattern, 24., ... upper layer film, 25.
book. '-7- , To-°〈< ■ (Yabi) Sha 6 figure/, X rh) (U) \l+/l

Claims (1)

[Claims] In the dry etching method, silicide is etched by a plasma of a fluorine-based main gas and O_2 gas using a dry etching device that has an upper electrode and a lower electrode spaced apart in a chamber. A dry etching method characterized in that each gas can be independently controlled in flow rate and introduced into a chamber as a mixed gas, and the line width and cross-sectional shape of silicide can be controlled by changing the O_2 gas concentration.