JPH0652725B2 - Dry etching equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching apparatus, and more particularly to a dry etching apparatus which has very little side etching and can be etched with high dimensional accuracy.

[0002]

2. Description of the Related Art In a conventional semiconductor manufacturing process using high-energy particles, the temperature of a solid sample and a solid material is kept at a water temperature.

[0003]

Therefore, the solid temperature is relatively high, the active gas and the solid easily react, and it is difficult to precisely control the surface reaction promoting effect by energetic particles such as ions, electrons, and lasers. There was a drawback that it was. In particular, in dry etching, it is difficult to control the reaction between reactive neutral particles such as radicals in plasma and solids, so etching under a mask, that is, side etching is large, and etching with high dimensional accuracy is recommended. It was difficult. An object of the present invention is to solve the above-mentioned conventional problems, and when high energy particles are incident on a solid to perform etching, the surface reaction on the surface on which high energy particles are not incident is controlled with high accuracy to perform side etching. It is an object of the present invention to provide a dry etching apparatus capable of performing highly accurate etching with less heat.

[0004]

The above object can be achieved by providing a means for etching while keeping the temperature of the sample (solid) within a predetermined range, which is significantly lower than in the prior art.

[0005]

In dry etching, high energy particles such as ions and electrons and neutral particles such as radicals are simultaneously incident on the horizontal surface of the solid to be etched. As a result of the mechanism analysis, in the horizontal plane of the solid, the irradiation of high energy particles creates a pseudo "high temperature" state on the very surface of the solid.
Therefore, it was found that the reaction between the gas particles and radicals and the surface electrons is greatly activated and contributes to etching.

On the other hand, in a solid sidewall, reactions between radicals and solids, and gas molecules and solids occur at a cooled temperature.

Therefore, when the sample (solid) is etched at a remarkably low temperature, the etching in the depth direction does not change, the reaction in the side wall is suppressed, and the side etch becomes small.

[0008]

【Example】

Example 1 FIG. 1 shows a high frequency discharge parallel plate type cathodic couple type plasma etching apparatus, which comprises a sample stage 1 and a counter electrode 2.
Is equipped with a cooling device (water temperature or lower, −120 ° C. or higher). The cooling device uses the principle of a heat pipe, and is composed of a refrigerant reservoir 3, a pipe 4, and an exhaust device 5. By changing the refrigerant, the above temperature can be easily realized and the stability is excellent, and typically, the set temperature can be maintained at ± 1.5 ° C. in 1 hour.

High-frequency power is applied to the sample stage 1 to generate plasma between the electrodes 1 and 2. The gas inlet is port 6.

Using this apparatus, poly with SF ₆ gas is used.
The result of etching -Si is shown in FIG. Etching conditions are gas pressure: 5 × 10 Pa, high frequency power: 2
00W (power density 0.2 W / m ² ) and poly-
A photoresist (AZ1350J) film was used as a mask on the Si film (thickness 1.2 μm). FIG. 2 is a diagram showing the relationship between the sample stage temperature and the side etching amount (dimension shift amount: showing the dimension from the mask edge) at the time of completion of etching. It turned out to be smaller.

Further, the side etching amount is poly
-SiF ₄ which is a reaction product of Si and SF ₆ gas plasma
The vapor pressure of 1/10 or less of the vapor pressure at room temperature, that is, at a temperature of about −10 ° C. or less, the side etching amount at 20 ° C. is 1/4 or less of 0.8 μm,
Remarkably decreased. At this time, the etching rate in the depth direction hardly changes, which is a great feature of the present invention. Similar phenomenon is caused by Al, W, resist and Mo.
It was also confirmed by etching other electronic materials.

That is, side etching can be made extremely small by performing etching while holding the sample at a temperature at which the vapor pressure of the reaction product becomes 1/10 or less of the vapor pressure at room temperature. However, if the temperature is too low, gas adsorption to the cooling part occurs, making etching impossible. It was found that this gas adsorption occurs when the vapor pressure of the introduced gas SF _{6 at} the sample temperature becomes equal to or lower than the gas pressure in the vacuum container. Therefore, the temperature of the sample needs to be equal to or higher than the temperature at which the vapor pressure of the introduced gas becomes equal to or higher than the vapor pressure of the gas in the vacuum container.

[0013]

As shown in FIG. 2, when etching is performed at a temperature within the above range, the amount of side etching becomes extremely small, and the present invention provides an LSI having a high integration density.
It is extremely excellent as an etching device used for manufacturing.

The present invention is effective not only in the parallel plate type etching apparatus but also in other etching apparatuses such as a microwave etching apparatus and an ion beam etching apparatus. It was also found that the cooling of the vacuum container itself is related to the control of the gas etching reaction. However, in this case, it was necessary to take measures against fog droplets, such as using a double structure for the vacuum container.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an etching apparatus used for implementing the present invention.

FIG. 2 is a curve diagram showing the effect of the present invention.

[Explanation of symbols]

 1 ... Sample stand 2 ... Counter electrode 3 ... Refrigerant reservoir 4 ... Pipe 5 ... Pump 6 ... Gas introduction hole 7 ... rf power supply 8 ... Sample 9 ... Exhaust

Claims (4)

[Claims] 1. A vacuum container, a means for generating plasma of a predetermined processing gas, a sample stage for arranging a workpiece to be etched at a predetermined position in the vacuum container, and exhausting the inside of the vacuum container. And a vapor pressure of a reaction product generated by etching the work by causing a low-temperature heat medium to flow inside the sample table and the reaction product at room temperature. The dry etching apparatus is characterized by at least having a temperature equal to or less than 1/10 of the vapor pressure of, and a temperature at which the vapor pressure of the processing gas is equal to or higher than the gas pressure in the vacuum container. 2. The dry etching apparatus according to claim 1, wherein the dry etching apparatus is a parallel plate type etching apparatus. 3. The dry etching apparatus according to claim 1, wherein the dry etching apparatus is a microwave etching apparatus. 4. The dry etching apparatus according to claim 1, wherein the dry etching apparatus is an ion beam etching apparatus.