JPS6247132A - Parallel flat plate type dry etching device - Google Patents

Abstract

PURPOSE:To uniformly etch the entire surface of a wafer by differentiating a distance between electrodes at the center and the periphery of a sample to be etched. CONSTITUTION:The lower surface of an electrode 4 opposed to an electrode 3 for placing a sample 5 is stepwisely formed from the center toward the peripheral edge, and a distance l2 between electrodes at the center of the sample 5 and a distance l1 between the electrodes at the periphery are l1>l;2. Thus, an electric field between the electrodes becomes small toward the periphery, the sample is substantially uniformly treated at etching ending time to be effective in microminiaturization. The electrode structure may be formed in a cup- shape in addition to the stepwise shape.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is applicable to semiconductor devices, especially L/L devices that require fine processing precision.
This invention relates to a parallel plate type dry etching apparatus for dry etching of SI and VLSI.

[Conventional technology]

In recent years, etching technology using gas plasma has been widely used as a microfabrication technology for various semiconductor devices, especially LSIs. As r and sr become more highly functional and dense, etching patterns are entering the sub-micron range, and their processing shapes are becoming increasingly difficult. Dry etching technology has become popular as an indispensable technology for such microfabrication.

Dry etching modes include plasma etching,
Examples include etching, ivy etching, and ion beam etching. Etching directionality includes isotropy and anisotropy, and anisotropic etching has become mainstream, especially for microfabrication. Sputter etching and ion beam etching are usually used for anisotropic etching, but here we will explain the processed shape of parallel plate-shaped sputter etching, especially the cross-sectional shape of the pattern processed by etching.

A schematic diagram of a parallel plate type dry etching apparatus is shown in FIG. In the figure, 3 and 4 are electrodes installed in the etching reaction tank 1, 2 is a high frequency power source, and 5 is a sample to be etched.

Conventionally, the anisotropy of etching depends on the type of gas, gas pressure, gas flow rate, and, especially in parallel plate type devices, the high frequency power, the electrode material.

It is known that it depends on many parameters such as electrode spacing. Furthermore, in a flat substrate as a sample to be etched, the etching speed m is different between the periphery and the center of the substrate, and generally the periphery is etched faster.

For LSI devices, for which it is important to uniformly etch the same semiconductor substrate, it is undesirable from the standpoint of device reliability that the etching ends at different times at the periphery and center of the semiconductor substrate. The reaction mechanism of etching is considered to be a complex reaction of physical and chemical reactions. Reactive ion bombardment on the surface to be etched can be viewed as a physical reaction, and the bias and electric field distribution between the electrodes are major parameters.

[Problem that the invention seeks to solve]

Conventionally, as shown in FIG. 3, the counter electrode 4 above the sample 5 to be etched is parallel to the surface of the sample. As mentioned above, it is known that the time at which etching is completed at the periphery and the center of the sample differs depending on various factors, and that etching at the center ends later than at the periphery. In conventional parallel plate type dry etching equipment, the etching end time is different between the central part and the peripheral part of the surface of the sample to be etched.
There were many defects such as 15 etc., where the surrounding parts were quickly etched, which also caused a big problem in terms of reliability.

This is largely due to the fact that the electrode facing the surface of the sample to be etched is parallel to the surface of the sample to be etched.

The present invention provides a parallel plate dry etching apparatus that uniformly etches the surface of a sample to be etched.

[Failure to solve the problem]

The present invention is a parallel plate type dry etching apparatus in which a sample to be etched is placed on one of two parallel electrodes and an electric field is formed between the two electrodes to etch the sample. This is a parallel plate type dry etching apparatus characterized in that the distance between the two electrodes is different from the distance between the electrodes and the peripheral portion.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, in this embodiment, the F surface of the electrode 4, which faces the electrode 3 on which the sample 5 to be etched is placed, is formed in a step-like manner from the center toward the periphery. Inter-electrode distance t2 and inter-electrode distance t with respect to the peripheral area
1 (11>12).

The electric field distribution between the electrodes 3 and 4 is made smaller toward the periphery with respect to the center of the sample 5 to be etched.

According to the present invention, the electrode structure is such that the electric field distribution between the electrodes decreases toward the periphery from the center of the sample to be etched, so the electric field distribution differs between the center and the periphery of the sample to be etched. When etching is completed at the center and the periphery, the etching is done evenly at almost the same time, there is little unevenness in etching within the sample, and an etched shape that is effective for microfabrication can be expected. Although this embodiment has a stepped electrode structure, it is also possible to use a bowl-shaped electrode structure or a linear one-curve shape.

〔Effect of the invention〕

As explained above, the present invention uses a parallel plate type etching apparatus to change the electric field distribution by varying the distance between the electrodes facing the surface of the sample to be etched from the center to the periphery. This has the effect of allowing uniform etching to be performed all the way to the periphery.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view of a conventional parallel plate type etching apparatus, and FIG. 3 is a sectional view of a conventional electrode. l... Etching reaction tank, 2... High frequency power supply, 3,
4... Electrode, 5... Sample to be etched Patent applicant
NEC Corporation Figure 3

Claims (1)

[Claims] (1) In a parallel plate type dry etching apparatus in which a sample to be etched is placed on one of two parallel electrodes and an electric field is formed between both electrodes to etch the sample to be etched, the central part of the sample to be etched is A parallel plate type dry etching apparatus characterized in that the distance between the two electrodes and the peripheral part are different from each other.