JPS61100935A - Dry etching equipment - Google Patents

Abstract

PURPOSE:To allow a semiconductor wafer surface to have a uniform etching rate, by spouting a reaction gas from spouting orifices of independent system so that the flow of the reaction gas is properly distributed to the orifices in the central portion and to the orifices in the peripheral portions. CONSTITUTION:A mixture gas is distributed to a plurality of separate reaction gas systems, for example to three system A, B and C, so that the mixture reaction gas is spouted independently from spouting orifices 24, 25 and 26 provided in a reaction gas spouting device 13. The reaction gas spouting orifices of the three systems are arranged concentrically such that four spouting orifices 27 for the reaction gas of the A system are arranged along the outermost concentric circle (a), that four spouting orifices 28 for the reaction gas of the B system are arranged along the intermediate concentric circle (b) and that a single spouting orifice 29 for the reaction gas of the C system is arranged at the center (c). According to such arrangement, a larger quantity of reaction gas is spouted from the spouting orifices arranged along the outer peripheral circles while a smaller quantity of reaction gas is spouted from the central orifice. Consequently, such inconvenience that the central portion of a semiconductor wafer tends to be etched at a higher rate than the peripheral portion can be effectively prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a dry etching apparatus, and particularly to an improved method for supplying a reactive gas for ion etching in a dry etching method.

In recent years, the degree of integration of semiconductor integrated circuits has been remarkable, and VLS
The integration density of I has further improved due to advances in fine pattern formation technology.

Along with the miniaturization of patterns, the role of dry etching technology will also increase, and as semiconductor wafers gradually become larger, there is a need for methods and equipment that can perform uniform dry etching over the entire surface of large-diameter semiconductor wafers. It becomes necessary.

[Conventional technology]

FIG. 2 is a cross-sectional view for explaining a conventional ion etching apparatus.

There is a container 1 for an ion etching device, a wafer stand 2 is located inside the container, and a semiconductor wafer 3 is placed on the wafer stand 2.

An electrode 4 is arranged facing the semiconductor wafer, and a reaction gas is supplied into the container through a reaction gas supply hole 5 provided in the container.

The container can be evacuated to a vacuum, and an exhaust hole 6 is attached.

A high frequency voltage is usually used as the voltage for ionizing the reaction gas, and the high frequency voltage is applied between the electrode 4 and the semiconductor device C3, the normal frequency is 13.56 MHz, and the high frequency power is about 350 W.

Generally, the etching effect in the ion etching method is as follows when the reaction gas pressure is set to 0.1 to 0.2 Torr.
As the chemical reaction factors become larger, the etching rate becomes better and the uniformity of etching also becomes better.

Reactive gases include chlorine gas, carbon tetrachloride, boron chloride, etc.
In order to improve the etching rate and etching uniformity, the type of gas may be changed, but it is difficult to obtain a large effect.

In general, when ion etching is performed, there is a difference in the etching rate between the center of the wafer and the periphery of the wafer, and the etching rate in the center is usually about 1.5 times that of the periphery. many.

Such a phenomenon becomes more noticeable as the size of the wafer becomes larger, and is a serious problem with wafers that are becoming larger these days, and there is a desire to improve this problem.

[Problem that the invention seeks to solve]

In the ion etching apparatus having the above configuration, the method of ejecting the reaction gas onto the surface of the semiconductor wafer in the container of the ion etching apparatus is conventionally uniform over the wafer surface, so that the temperature distribution of the semiconductor wafer and The problem is that if there is non-uniformity in the ion density distribution, etc., the ion etching effect will become non-uniform as a result, resulting in the problem of local differences in etching rate on the wafer surface. .

[Means for solving problems]

The present invention provides a dry etching apparatus that solves the above-mentioned problems, and the method is such that the mixed reaction gas supplied to the dry etching apparatus is divided into a plurality of independent supply systems, and the reaction gas is The ejection holes connected to each supply system are arranged on a plurality of concentric circles on the reaction gas ejection surface, and the flow rate of each of the reaction gases is independently controlled,
This can be achieved by a dry etching apparatus characterized in that the etching rate is made uniform by rotating the semiconductor wafer to be dry etched.

[Effect]

The present invention is an ion etching method that supplies a plurality of reaction gases, in which each reaction gas is individually controlled by a mass flow meter and then mixed, and the mixed reaction gas is made into an independent system and connected to that system. The reactant gas flow rate from each independent system of ejection holes is arranged in multiple concentric circles on the ejection surface so that the gas is ejected from each of them at a different appropriate flow rate. This takes into consideration the uniformity of the etching rate on the surface of the semiconductor wafer by appropriately distributing the etching rate to the center and the periphery of the semiconductor wafer.

〔Example〕

FIG. 1 is a schematic principle diagram of an ion etching apparatus for explaining the present invention in detail.

A substrate 12 is disposed on the surface of a substrate pedestal 11, and a reaction gas ejection device 13 is disposed opposite thereto.

If there are three types of reaction gases, for example, there are tanks for chlorine gas 14, boron chloride 15, and carbon tetrachloride 16, each reaction gas is transferred to a mass flow meter 17.1.
8.19, the amount of gas is adjusted and introduced into the mixing device 20.

This mixed gas is generated by, for example, three reaction gas systems, A and B.
, C system, each of which is connected to a mass flow meter 21.
22. Controlled by 23, the reaction gas injection device 1
The mixed reaction gas is injected independently from the ejection holes 24, 25, and 26 provided in 3.

FIG. 2 is a sectional view of the lower part of the nozzle of the reactant gas nozzle 13, and the three systems of the above-mentioned mixed gas nozzles are divided into concentric circles, and the mixed gas of the A system is divided into the outermost concentric circle a. Four nozzle holes 27 are arranged in the center, four nozzle holes 28 are arranged in the middle concentric circle for the mixed gas of the B system, and one nozzle hole 28 is arranged in the center C of the C system. The state in which the jet holes 29 are arranged is shown.

With this arrangement, a large amount of reactive gas is emitted from the ejection holes arranged on the outer circumference, while a small amount of gas is ejected from the center, which prevents the problem of a high etching rate in the center. However, by controlling the gas amount using mass flow meters provided in each of the A, B, and C systems, even more appropriate control can be achieved.

As an example, three types of reaction gases are chlorine gas, boron chloride,
As carbon tetrachloride, each amount of chlorine gas: 65
sccms Boron chloride: 45secm% Carbon tetrachloride: 20sccm,.

Then, by setting the mixing ratio of these to A:B:C=1:3:5, the ion etching rate of the wafer can be made uniform.For example, the ion etching rate of the wafer can be made uniform by setting the mixing ratio of A:B:C=1:3:5. The difference in etching rate was about 5 times, but the present invention was able to improve it to about 1.1 to 1.2 times.

〔Effect of the invention〕

As described above in detail, the reactive gas injection device of the ion etching apparatus of the present invention can uniformly etch a wafer and has the great effect of providing high quality wafers.

[Brief explanation of drawings]

Figure 1 is a system diagram of the supply of reactive gas in the ion etching apparatus of the present invention, Figure 2 is a plan view of the reactive gas injection device of the ion etching apparatus of the present invention, and Figure 3 is a schematic diagram of a conventional ion etching apparatus. In the sectional view and figure, 11 is a substrate stand, 12 is a substrate, 13 is a reaction gas blowout device, 14 is a chlorine gas, 15 is a boron chloride tank, 16 is a carbon tetrachloride tank, and 17, 18, and 19 are respective tanks. Reaction gas mass flow meter, 20 is a mixing device, 21.22.23
is a mass flow meter, 24.25.26.27.28.
Reference numeral 29 indicates the ejection holes. Eye 4 Second Flash Figure 3

Claims (1)

[Claims] The mixed reaction gas supplied to the dry etching apparatus is divided into a plurality of independent supply systems, and the ejection holes connected to each of the reaction gas supply systems are arranged on a plurality of concentric circles on the reaction gas ejection surface. A dry etching apparatus characterized in that the flow rates of each of the reaction gases are independently controlled, and the semiconductor wafer to be dry etched is rotated so that the etching rate is made uniform.