JPS59132623A - Electrode for dry etching - Google Patents

Abstract

PURPOSE:To enable to perform etching having uniformity by a method wherein a ring type body risen up from an RF electrode is provided surrounding the electrode thereof on the circumference of a wafer. CONSTITUTION:When a current is flowed to an RF electrode 1, plasma is generated in front of a wafer 3, and the ionized compositions of etching gas in a vacuum chamber 2 dash against the surface of the wafer 3 to etch the wafer thereof, while because a ring type body 7 risen up from the RF electrode 1 is provided on the circumference of the wafer 3, density of plasma in front of the wafer is decreased, and the generating ratio of the radicals thereat is reduced. Accordingly, the quantity of the radicals to diffuse to the peripheral part of the wafer 3 from the circumference of the wafer 3 is reduced, distribution of the etching speed of the wafer 3 can be made to distribution having no great difference between the peripheral part and the central part of the wafer 3, and ununiform distribution of the etching speed as usual can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates primarily to a dry etching electrode suitable for dry etching of highly chemically reactive substances.

Conventionally, a method is known in which a wafer is placed in front of an RF electrode in a vacuum chamber and the wafer is etched by a plasma atmosphere generated in front of the wafer, but the film formed on the wafer is made of polysilicon, aluminum, etc. If the material is etched mainly through a chemical reaction, the etching rate tends to be high at the periphery of the wafer, resulting in an uneven etching distribution.

The present invention aims to solve these inconveniences, and includes a wafer provided in front of the RP electrode in the vacuum chamber.
In a type of etching method in which the wafer is etched by a plasma atmosphere generated in front of the wafer, an annular body is provided around the wafer and floating from the RF electrode.

To explain the embodiment of the present invention with reference to the drawings, in FIG. S10 on front +41
．． N (attached through 51', polysilicon, A
t indicates a wafer having a film made of a highly chemically reactive substance such as Eli, R4, etc. When an RF power source (6) of, for example, 15.56 MHz is connected to the RF electrode film, the electrode (11 Plasma is generated in front of the wafer (3) to ionize the etching gas in the chamber (2), and the electrolyte and etching gas mixture combine with the composition of the wafer (3) and fly away, etching the entire surface of the wafer (3). do.

In this case, the surface of the wafer (3) is officially masked as is well known, and the unmasked surface is etched, and depending on the material of the wafer (3), the vacuum chamber (2) is SF, and aot4 mixed gas, aot4 gas or 07.
An etching gas such as gas is injected.

The above configuration is not particularly different from the conventional configuration, but in the configuration of the present invention, the wafer (3) is surrounded and the RF
At1 quartz or other conductive material floated from the electrode (1),
A circular, square, etc. annular body (7) made of a non-conductive material is provided, and by increasing the discharge impedance in front of the annular body (7), the plasma density in front of the annular body (7) is reduced and the peripheral area of one wafer (3) is reduced. This suppresses the etching speed, which tends to become faster during etching, and allows uniform etching to be performed over the entire surface of the wafer (3). In the illustrated example, the annular body (7) is RI
This spacer (
The thickness of 8) was adjusted so that the flying distance d that would provide the optimum etching distribution was set.

To explain its operation, when the RF voltage +11 is energized, plasma is generated in front of the wafer (3), and the composition of the etching gas in the ionized vacuum chamber (2) is transferred to the wafer (3).
3) and etches it, but the surface of the wafer (3) is etched.
3) is surrounded by an annular body floating from the R/F electrode (1).
7), the plasma density in front of it is weakened and the radical generation rate there is reduced. This reduces the amount of radicals diffusing from the periphery of the wafer (31) to the periphery of the wafer (31), and
As shown by curve A in FIG. 2, the etching rate distribution can be made such that there is no significant difference between the peripheral area B and central area 0 of the wafer (3). It is possible to improve the speed distribution.

In this way, according to the present invention, the wafer is surrounded by RIF! By providing an annular body floating from the pole, it is possible to suppress the etching rate, which tends to be faster at the periphery of the wafer, and to approximate the etching rate at the center of the wafer, allowing for uniform etching. It is effective in uniformizing the etching of substances that are highly reactive and cause a larger difference in etching rate at the periphery than at the center.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view showing an embodiment of the present invention;
The figure is a distribution diagram of the etching rate of a wafer. (11... RIF electrode (2)... Vacuum chamber (3)... Ueno A (4)...
・・・Front side (7)・・・Annular external body 2 people Figure 2

Claims (1)

[Claims] In a method in which a wafer is provided in front of an RF electrode in a vacuum chamber and the wafer is etched by a plasma atmosphere generated in front of the wafer, the wafer is bent around the wafer and floated from the R1 electrode. Dry etching electrode 0 provided with an annular body