JPS6273719A - Dry etching apparatus - Google Patents

Abstract

PURPOSE:To raise the etching rate of a dry etching apparatus by setting the area ratio of an electrode opposed to an electrode for placing a wafer to the specific value or higher. CONSTITUTION:Since high frequency energy applied between a high frequency electrode 2 for placing a wafer 7 and an opposed electrode 21 of ground potential is converted to energy of plasma, the surface area of the electrode of the ground potential is preferably increased, while the electrode 2 is preferably of sufficient size for placing the wafer and preferably of smaller surface area to thereby increase the plasma density near the surface of the wafer. Thus, the etching rate can be improved, and the selection ratio of the primary film and that of a resist film can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to dry etching, and more particularly to a dry etching apparatus suitable for manufacturing large scale semiconductor devices.

[Background of the invention]

Parallel plate type dry etching equipment, which is currently widely used for dry etching, generates plasma by applying a high frequency voltage to parallel plate electrodes.

On the other hand, it is known that by changing the area ratio between parallel plate electrodes, the inter-sheath voltage generated on the electrode surface changes. The sheath is the dark space between the plasma generated by the discharge and the polarization.

This phenomenon is caused by solid state technology (5oli
ct 5tate Technology) Japanese version,
According to pages 84 to 91 of the July 1983 issue, it is used to change the amount of sputtering on one electrode in parallel plate type sputtering equipment, etc., and as a hexagonal columnar electrode structure as a modification of the parallel plate type. It was said to be effective when performing etching with a large ion bombardment effect.

In addition, as shown in Japanese Patent Application Laid-open No. 60-12754, there is a method in which a part of the electrode is divided to change the area of the electrode, but the etching gas pressure has not been considered, and As for the effect on etching of changing the area ratio, only the effect of increasing the energy of the ions was considered. As a result, in order to obtain selectivity with the substrate, it was considered necessary to perform etching with low power and pressure as the etching process conditions, so a method of changing the electrode area ratio was It was thought that it would be better to etch many wafers at the same time and slowly so that the
501165).

Therefore, it has not been considered that the method of changing the electrode area ratio is effective for high-speed etching cleaning.

[Purpose of the invention]

An object of the present invention is to clarify the relationship between the electrode area ratio and etching characteristics, and to provide a dry etching apparatus that has a high etching rate and can perform etching with a high selectivity.

[Summary of the invention]

Considering the etching gas pressure, it has been found that in a parallel plate type etching apparatus, it is effective to make the high frequency electrode for alflfing Ueno-- c6 to 4 times that of the counter electrode button.

Therefore, the ratio of the areas of the two electrodes, which is a technical element that cannot be changed, is set to 2 to 3, depending on the device shape ((depending on the shape of the device, t'fIi facing the high jη wave electrode).

That is, it can be said that the outline of the present invention is to set the electrode area ratio, which is difficult to control compared to Jilc2 degrees, introduced gas pressure, applied high frequency power, etc., to be as large as possible in advance.

[Embodiments of the invention]

An embodiment of the etching processing apparatus according to the present invention is shown in FIG. 1 and will be described and explained below.

Inside the processing chamber 1, there are a high frequency electrode 2 and one opposing pole 3, which are designed to press the wafer 7 at the highest frequency range. Opposite pole 5, processing chamber 1 is grounded to ground 1,
The high-frequency abrasive pole 2 is fixed to the processing chamber 1 via an insulating material 4,
It is followed by a high frequency power source 8. Cooling water for controlling the temperature is sent to the straight pole 2 from a water supply pipe 9, and water is also drained from a drain pipe 10. The processing chamber 1 has a gas supply pipe 5. An exhaust pipe 6 is provided, and is connected to an etching gas supply Be and an exhaust device (not shown), respectively.

Etching gas is supplied to the processing chamber 1 from the gas supply W5,
While exhausting with exhaust pipe 6, 0.01 To r r ~ number'
Maintain a predetermined pressure of forr. When the wafer 7 is placed on the high frequency electrode 2 and high frequency power is supplied from the high frequency power source 8, plasma is generated between the high frequency electrode 2 and the counter electrode 30.

The thin film on the wafer is etched by the ions and radicals of the etching gas generated in this plasma.

In such an etching process device, the high frequency electrode 2
The zero dimension was set to 20077 Lm, which is the same as that of the opposing tfM 5, and FIG. 2 shows the results of investigating the bundling of the etch rate when the pressure inside the processing chamber was changed for the aluminum film.

Etch rate increases with increasing pressure, 0.17o
It is maximum at rr. The etch rate at that time is about soon
m7 minutes. Next, set the high frequency electrode 20 dimension to 100mm.
When the same power per unit area is applied to this, the etch rate is not much different from that of 2Q Qmrn under low gas pressure conditions, but the maximum etch rate is
Gas pressure was obtained at 0.18 Torr, then Etschley) +'! Approximately 60 On+" 7 minutes, which is twice as much as a 200 mm electrode, can be obtained.

Next, the diameter of pole 2 is 100 mm, 150 m.
Aluminum film Q, sio, rg when changing to m5200mm
The results of examining the etching rate ratio (selectivity ratio) of
As shown in the figure. It can be seen that even if 161 frequency power is applied per unit area, the smaller the electrode diameter is, the better the selection ratio is. Furthermore, the effect of changing φD due to the difference in selection ratio in the valley diameter is considered to be strongly dependent on the surface type of the frequency n/2.

A high frequency σ of 1:1J is applied between the high frequency temporary electrode 2 on which the wafer 7 is placed and the counter electrode 21 which is at ground potential.
) Energy is considered to be converted into plasma energy, so it is better to make the surface area of the electrode at ground potential large.On the other hand, if the high frequency electrode 2 is large enough to place the wafer, The smaller the surface area, the better.

This is because the glazma density near the wafer surface can be increased.

Increasing the area ratio of the high frequency electrode 2 and the counter electrode 3 in this way has a great effect on improving the etching rate and the selection ratio.

The area ratio of the high-frequency electrode 2 and the five opposing electrodes does not simply depend on the electrode dimensions (as mentioned above, it has a large relationship with the way plasma is generated). Therefore, the size of the VC counter electrode was increased to 500 mm as shown in FIG. 4 in order to further increase the area ratio.
No difference in effectiveness was observed as the drug did not spread.

However, the distance between the opposing polarization 5 and the still frequency electrode 2 is approximately 100
mm, and if this distance is set to a value greater than this, there is a risk that the plasma will be stably maintained and Ic<.

The plasma generation region 20 is controlled by gas pressure, high frequency power, and '?
i! , the pole spacing depends on the country, but the area 20 can be expanded by increasing the discharge conditions by λ, so the counter electrode 6 needs to be set as large as possible.

In addition, the plasma generation area expands when the gas pressure is low,
It gets smaller when it's high. Since a high etching rate condition means a high gas pressure condition (FIG. 2), it is important to increase the area ratio of the high frequency electrode and the counter electrode that are in contact with the plasma under this condition.

A specific example of such a case is shown in FIGS. 5 and 6 and will be described below.

In FIG. 5, the periphery of the counter electrode 21 is made into a cylindrical shape so that the plasma comes into contact with the cylindrical surface and the disk portion. With this electrode, the plasma does not need to spread, and the cylindrical part has a large area, so a large area ratio can be obtained with commercial gas pressure.

In FIG. 6, the surface of the counter electrode 22 is made uneven so that the surface with which the plasma comes into contact is roughened.

In this case, it is necessary that the size of the unevenness is larger than the size of the gap generated between the plasma and the t-pole, so that the plasma can penetrate into the instep of the unevenness.

It is also clear that the structure shown in FIG. 5 and the structure shown in FIG. 6 may be combined.

Furthermore, in this 81st example, the etching selectivity for etching, SiO, and yQ was mainly explained with respect to the etching of an aluminum film, but it has also been experimentally confirmed that the selectivity with respect to a resist film is the same as above. Furthermore, from the results of these selectivity ratios,
The present invention is polysilicon.

Effective against molybdenum silicide, tungsten silicide, tungsten, and other substances where radicals ignite the reaction.

〔Effect of the invention〕

According to the present invention, it is possible to improve the etching rate, increase the J4 selectivity (+J) with the underlying layer, and improve the selectivity with the resist film.This has the effect of increasing the processing capacity by about twice that of the conventional etching process. In addition, etching problems of the underlying film can be reduced, dimensional changes in the resist can be reduced, etching can be performed with high dimensional accuracy, and the yield in manufacturing semiconductor devices can be improved.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the basic configuration of the present invention, Figures 2 and 3.
4 is a diagram showing the etching characteristics according to the present invention, FIG. 4 is a diagram showing a situation in which plasma is generated in the electrode of the present invention, and FIGS. 5 and 6 are diagrams showing other embodiments of the present invention. 1... Processing chamber 2... High frequency electrode 3...
Counter electrode 7...Wafer 8...High frequency electrode＼, Agent 9f-Buried soil Masaru Ogawa Male closed 1 figure ¥2 figure, Input pressure 5 figure force,; CCI, + Inte anti-harm force 44 diagram

Claims (1)

[Claims] 1. A dry etching apparatus having an electrode on which a wafer is placed and an electrode opposite thereto, means for applying a high frequency voltage between the electrodes, and means for introducing and discharging an etching gas. A dry etching apparatus characterized in that the ratio of the area of the electrode on which the is placed and the electrode facing the electrode is 1:2 or more. 2. A dry etching apparatus according to item 1, wherein the opposing electrodes are composed of a flat plate and a cylinder. 3. The dry etching apparatus according to item 1, wherein the surfaces of the opposing electrodes have an uneven shape.