JPS60158627A - Controlling method of surface reaction - Google Patents

Abstract

PURPOSE:To control a surface reaction at the surface of a sample not to be injected with energy particles at a vacuum etching device by a method wherein the sample is held at a temperature whereat vapor pressure of a reaction product becomes to 1/10 or less of vapor pressure at the room temperature, and the temperature thereof is set to the temperature or more whereat vapor pressure of the reaction product becomes to pressure or more of a vacuum vessel. CONSTITUTION:Particles having energy larger than heat energy is injected continuously or intermittently to a solid sample 8 put in an atmosphere of gas of at least one kind in a vacuum vessel, and the surface of the sample 8 is etched and modified. At this time, the sample 8 is held at the temperature whereat vapor pressure of a reaction product becomes to 1/10 or less of vapor pressure at the room temperature. Moreover the temperature thereof is set to the temperature or more whereat vapor pressure of the reaction product becomes to pressure or more of the vacuum vessel. Accordingly, a surface reaction at the surface not injected with energy particles is controlled with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to etching of solids and modification of the surface of solids, and particularly to a method of controlling surface reactions suitable for processing and modification with high dimensional accuracy.

[Background of the invention]

In the conventional semiconductor manufacturing process using high-energy particles, the temperature of the solid sample and solid material was kept at water temperature, so the solid temperature was relatively high, and the active gas and solid reacted easily, causing ions, electrons, The drawback is that it is difficult to precisely control the effect of promoting surface reactions using energetic particles such as lasers. In particular, dry etching has the disadvantage that it is difficult to control the reaction between reactive neutral particles such as radicals in the plasma and the solid, and that the etching under the mask becomes thick.

[Purpose of the invention]

An object of the present invention is to provide a method for highly accurately controlling surface reactions on surfaces where energetic particles do not enter when high-energy particles are incident on a solid for treatment.

[Summary of the invention]

In dry etching, high-energy particles such as ions and electrons and neutral particles such as radicals are simultaneously incident on a horizontal surface, while only neutral particles are incident on the sidewall. Kito's analysis shows that high-energy particle irradiation creates a pseudo-high-temperature state on the very surface of a solid, which has the effect of greatly activating reactions between gas particles and radicals and surface electrons. Understood.

On the other hand, in the sidewall, reactions occur between radicals and solids, and between gas molecules and solids, at temperatures comparable to water.

Therefore, it was found that in order to reduce the side etching without changing the etching in the depth direction, it is sufficient to lower the temperature of the sample (solid).

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a high-frequency discharge parallel plate cathode-coupled plasma etching apparatus in which a sample stage 1 and a counter electrode 2 are equipped with a cooling device (water temperature or lower, -120 DEG C. or higher). The cooling device uses the principle of a heat pipe, and consists of a solvent reservoir 3, a pipe 4, and an exhaust device 5. By changing the solvent, the above temperature can be easily achieved, and it has excellent stability. The device is typically capable of maintaining a set temperature of ±1.5°C for one hour.

Plasma is generated between both electrodes by applying g-frequency power to the sample stage 1. The gas inlet is the boat 6.

FIG. 2 shows the results of etching Po1y-Si with SF6 gas using this apparatus. Etching conditions are 5X10Pa, high frequency crab 200W (power density 0
．． 2 W/a1), and PolySi (thickness 1,
2 μm) mask material is photoresist Az135.
0J was used. Figure 2 shows the relationship between the sample stage temperature and the side etching amount (dimensional shift amount: the dimension from the edge of the mask) at the end of etching. I found out that it gets smaller. Furthermore, the amount of side etching is determined by the fact that the vapor pressure of SiF4, which is a reaction product of Poly-Si and SF8 gas plasma, is 1710% of the vapor pressure at room temperature.
At a temperature below, that is, at a temperature below about -10°C, the side etching amount at 20°C is 0.8 μm, which is 174 or below, which becomes remarkable. At this time, the etching rate in the depth direction does not change. A similar development is
It was also confirmed in other electronic materials such as AQ, W, resist, and MO. That is, in this method, side etching can be extremely reduced by maintaining the sample at a temperature where the vapor pressure of the reaction product is 1/10 or less of the vapor pressure at room temperature. However, if the temperature is too low, gas leakage to the cooling part occurs, making etching impossible. It has been found that this gas adsorption occurs when the vapor pressure of SF6, which is the gas to be introduced, at the sample temperature becomes lower than the gas pressure of the vacuum container.

Therefore, the temperature must be higher than the temperature at which the vapor pressure is higher than the vacuum vessel pressure.

In the above temperature range, the amount of side etching can be extremely small, as shown in FIG.
This is an excellent method for etching SI.

This reaction control method is also effective for other etching apparatuses such as microwave etching apparatuses and ion beam etching apparatuses, and it has also been found that cooling of the vacuum chamber itself is also relevant to controlling the plasma etching reaction. However, in this case, measures against dew droplets, such as a double structure, were required.

The present invention is also effective using ion beams, electrobeams, and lithography. With lithography, it was possible to form high-precision patterns by limiting the spread of these beams to only the horizontal floor space.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an etching apparatus used to carry out the present invention, and FIG. 2 is a curve diagram showing the effects of the present invention. ■... Sample stage (electrode), 2... Counter electrode, 3...
Solvent reservoir, 4...pipe, 5...pump, 6...
Gas inlet hole, Fig. 1 Fig. 2 (2) 1) -21) -di/ -, (ρ Temperature (C)

Claims (1)

[Claims] (1) Particles having energy greater than thermal energy are continuously or intermittently incident on a solid sample placed in an atmosphere of at least one type of gas in a vacuum container, and the solid surface is etched. and a system for modifying the surface of a solid, in which at least one safe gaseous reaction product of the reaction between the atmospheric gas and the solid sample is heated to a vapor pressure of the product at room temperature. 1. A method for controlling a surface reaction, comprising: maintaining the temperature at a temperature at which the vapor pressure is 1/10 or less, and performing the treatment in a state where the vapor pressure of the atmospheric gas at that temperature does not fall below the vacuum vessel pressure. 2. A surface reaction control method according to claim 1, characterized in that a beer L-pipe is used to control the solid surface temperature.