JPH02246113A - Dryetching device - Google Patents

Abstract

PURPOSE:To prevent a material of a ring from attaching to a substrate and to avoid pattern defects by holding down the substrate with the ring which consists of a material of the same quality as that of a film to be etched. CONSTITUTION:A dry etching device is provided with a quartz ring 2 which is arranged to overlap a periphery section of a lower electrode 1. A silicon substrate 4 whereon a silicon oxide film 3 is formed is held down by a weight of the ring 2 itself at an edge section in the inner side of the quartz ring 2. The silicon substrate 4 whereon the silicon oxide film 3 is formed in etched by using the quartz ring 2 in this way. Accordingly, a radical 7 in plasma reacts and is exhausted as a reaction product even if the ring 2 is sputtered by an ion 5 in plasma, thereby producing no pattern defects caused by sputtered alumina.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a dry etching device used in an LSI manufacturing process.

BACKGROUND OF THE INVENTION In recent years, with the miniaturization and high integration of semiconductor devices, microfabrication technology using dry etching has become difficult.

For example, when processing a silicon oxide film using a resist as a mask, it is necessary to increase the degree of vacuum and high frequency power to improve anisotropy in order to prevent side etching. However, increasing the degree of vacuum and high frequency power increases the amount of ions generated and the ion energy, and the high degree of vacuum lengthens the mean free path of the ions, making it easier for a large number of high-energy ions to collide with the substrate. As a result, the temperature of the substrate increases, the resist shrinks due to the heat, and the edges of the resist pattern may become uneven.

Conventionally, in order to solve this problem, in a dry etching device consisting of an upper electrode 111 and a lower electrode 8 as shown in FIG. The technology used was to flow helium gas to increase the cooling efficiency of the substrate IO. The reason why alumina is used as the material for the ring is that it is easy to process and has excellent mechanical strength. If this technique is used, the effect of cooling the substrate 10 will be enhanced, and unevenness of pattern edges due to thermal contraction of the resist will not occur, making microfabrication techniques in the submicron region easier.

Problems to be Solved by the Invention The problems of the above-mentioned dry etching apparatus will be described below with reference to FIG. The conventional dry etching device is shown in Figure 3(a).
As shown in FIG.
5, the alumina ring 14 is sputtered, and the sputtered alumina IB adheres to the surface of the silicon oxide film 17. As a result, as shown in FIG. 3(b), the alumina 1G adhering to the surface of the silicon oxide film 17 serves as a mask, and the shape of the alumina IB is transferred, resulting in pattern defects. The number of pattern defects caused by sputtering alumina is on the order of several hundred for an 8-inch diameter substrate, which poses a problem of extremely lowering the manufacturing yield of VLSIs.

The present invention was developed in view of the above-mentioned problems, and an object of the present invention is to provide a dry etching apparatus that can prevent pattern defects.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention includes a ring that holds down a substrate on which a film to be etched is formed, at least in part,
The film is made of the same material as the film to be etched.

Effect of the present invention With the above-described configuration, if a ring of the same quality as the film to be etched is used, even if the material of the ring is sputtered by ions in the plasma, the material of the ring itself reacts with the radicals in the plasma and generates reaction products. Even if it does adhere to the substrate surface, it will be etched and exhausted, so the ring material rarely adheres to the substrate.

Therefore, it is possible to prevent pattern defects that occur when conventional alumina weights are used.

Embodiment FIG. 1 is a structural diagram of a dry etching apparatus in an embodiment of the present invention. Embodiments of the present invention will be described below with reference to FIG.

In the dry etching device, a quartz ring 2 is arranged so as to overlap the periphery of a lower electrode 1. At the inner edge of the quartz ring 2, a silicon oxide film 3 is formed by the weight of the ring 2. J has a structure for holding down the formed silicon substrate 4. Also, at this time, it is important to flow helium gas from the lower electrode 1 on the back surface of the silicon substrate 4 to enhance the cooling effect. In this case, the etching gas is CHF5, 02F@% CF4 and 0
A mixed gas of 2 is used. Since the silicon substrate 4 on which the silicon oxide film 3 is formed is etched using the quartz ring 2 in this way, even if the quartz ring 2 is sputtered by the ions 5 in the plasma, the sputtered quartz 6 The radicals 7 in the plasma react with each other and are exhausted as reaction products. Therefore, pattern defects due to sputtered alumina do not occur, unlike when a ring made of alumina is used.

Here, FIG. 4 shows comparative data on the number of pattern failures of rings made of alumina and rings made of quartz. Number of defective patterns for each pattern on a 6-inch wafer when using an alumina ring (
The total number of pattern defects (1, 3, 5 μm) was 475, and the number of pattern defects when using a quartz ring was 12, which is a significant improvement.

In this example, a silicon oxide film was used as the film to be etched, and a quartz ring was used as a holding ring for the substrate.
A similar effect can be obtained by using a holding ring made of the same material as the film to be etched.

Furthermore, a similar effect can be obtained by using an alumina ring coated with quartz instead of a quartz ring.

Effects of the Invention As is clear from the above explanation, since the substrate is held down by a ring made of the same material as the film to be etched, even if the material of the ring is sputtered by ions in the plasma,
The sputtered ring material creates reaction products with radicals in the plasma and is exhausted. Therefore, since the material of the ring does not adhere to the substrate, pattern defects can be prevented, and the yield of large-scale integrated circuits can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of a dry etching apparatus according to an embodiment of the present invention, FIG. 2 is a structural diagram of a conventional dry etching apparatus, and FIG. 3 is a diagram for explaining problems in the conventional technique.
FIG. 4 is a diagram showing comparative data between the prior art and the present invention. 1. Lower electrode, 2. Quartz ring, 3.
・Silicon oxide film, 4... silicon substrate, 5...
・Ion, 6...quartz, 7...radical.

Claims (1)

[Claims] A dry etching apparatus having a cooling mechanism and a mechanism for applying high-frequency power, wherein a ring that holds down a substrate on which a film to be etched is formed is at least partially made of the same material as the film to be etched. Device.