JPH02230730A - Etching method - Google Patents

Abstract

PURPOSE:To perform an etching without fears on contamination of a sample and damage of the sample with good controllability at an atomic layer order by providing the sample to be etched in the atmosphere of a gas, and applying a high electric field. CONSTITUTION:A gas is introduced through a gas introducing port 3 so that a gas atmosphere characterized by adequate gas species and gas pressure is obtained in a vacuum chamber 5. Then, a voltage is applied from a high voltage source 4. At this time, gas molecules and a sample to be etched 1 form a reaction product under the application of a high electric field. Or the sample is sequentially etched away from its surface layer by the adsorption of the gas molecule and the decrease in evaporation electric field of the sample. In this way, the etching without the contamination and the damage of the sample can be performed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for etching a sample.

BACKGROUND ART Conventionally, wet etching using a solution, dry etching using reactive particles, and the like have been used as relatively fine etching processing methods. Among these, wet etching is performed by selectively using a chemical that dissolves the sample to be etched into a solution, and controlling the temperature, solution concentration, and etching time.

Dry etching can be roughly divided into physical sputter etching and reactive etching. Furthermore, reactive ion etching can be divided into many types depending on the ratio of ions to plasma, ion acceleration energy, etc. Physical sputtering uses the kinetic energy of ions to repel atoms of the sample to be etched. Reactive ion etching uses ions or radicals that are reactive with the sample to be etched, and performs etching by utilizing kinetic energy and the reactivity between the ions or plasma and the sample. Etching is performed using parameters such as gas pressure, acceleration voltage, ion to plasma ratio, and etching time.

[Problem to be solved by the invention] The etching method described above has the following problems.

That is, in wet etching, if the solution is not sufficiently stirred during etching, uneven concentration and temperature of the solution will occur, resulting in uneven etching depth. Although physical sputter etching has low selectivity for the sample to be etched, the etching rate is slow and ions may enter the sample or damage the sample. Although reactive etching improves selectivity and etching rate, ion invasion and damage due to ion kinetic energy still remain.

In terms of processing controllability, wet etching allows processing up to micron order, and dry etching allows processing up to submicron order.

However, finer etching or etching on the order of atomic layers has been difficult due to poor controllability.

An object of the present invention is to provide an etching method that does not contaminate or damage a sample and has controllability on the atomic order.

[Means for Solving the Problems] The present invention provides a method for installing a sample to be etched in a gas atmosphere,
This is an etching method characterized by etching by applying a high electric field.

[Function] In the present invention, by placing the sample to be etched in a gas atmosphere and applying a high electric field, the atmospheric gas absorbs about one atomic layer on the sample surface.

There are two etching mechanisms in the next step.

One is that due to the influence of physically adsorbed gas molecules, the bonding energy between the atoms in the top layer of the sample and the atoms below it decreases, and as a result, the evaporation electric field decreases, and as a result, they are desorbed from the top layer in order at a low electric field.

The other is that due to chemisorption, the bonds between atoms in the top layer of the sample and atoms in the second layer are broken, and molecules composed of gas atoms polarized by the high electric field and atoms in the top layer of the sample are attracted by the high electric field. It is a matter of detachment. If inert nitrogen or the like is used as the gas, the former physical adsorption model applies. The latter chemical adsorption model applies when active oxygen, fluorine, chlorine gas, etc. are used.

By selecting an appropriate type of atmospheric gas, etching on the order of atomic layers can be achieved using the electric field size and gas pressure as parameters, and since the gas molecules are generated only by thermal kinetic energy, irradiation damage is minimized. It didn't happen,
No impurities enter the sample. Furthermore, this etching method allows the sample to be kept at an extremely low temperature, and there is no damage to the sample or change in impurity distribution due to temperature rise during etching.

[Example] Next, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of an example of an apparatus for carrying out the method of the present invention. A sample to be etched 1 is placed in the vacuum chamber 5, and a counter electrode 2 is installed at a position facing the sample 1. Sample 1 and counter electrode 2 are connected to high voltage power supply 4
The device is connected to a high electric field so that a high electric field can be applied. Further, the vacuum chamber 5 is provided with a gas inlet 3 .

First, a gas is introduced through the gas inlet 3 so that the inside of the vacuum chamber 5 becomes a gas atmosphere with appropriate gas types and gas pressures. Next, a voltage is applied by the high voltage power supply 4. At this time, the gas molecules and the sample to be etched either form a reactant under the application of a high electric field, or the gas molecules are adsorbed, and the evaporation electric field of the sample decreases, so that they are sequentially etched away from the surface layer of the sample. To go.

In the manner described above, etching could be performed without contaminating or damaging the sample.

FIG. 2 is an explanatory diagram showing a method of etching a sample to be etched into an arbitrary pattern. A material having a higher etching electric field than the sample to be etched 1 is selected for the portion to be left in the etching, and is covered as an etching mask 6 over the sample surface. By exposing the thus prepared sample to a gas atmosphere and applying a high electric field, only the portions not covered by the mask are selectively etched away. Etching depth is controlled by gas pressure, electric field strength, and etching time.

[Effects of the Invention] As explained above, according to the etching method of the present invention, etching can be performed with controllability on the atomic layer order without fear of contaminating the sample or damaging the sample.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an example of an apparatus for implementing the method of the invention, and FIG. 2 is an explanatory diagram when the method for forming an arbitrary pattern by the present etching method is implemented. 1... Sample to be etched 2... Counter electrode 3.
...Gas inlet 4...High voltage power supply 5...
Vacuum chamber 6...etching mask

Claims (1)

[Claims] (1) An etching method characterized by etching a sample to be etched by placing it in a gas atmosphere and applying a high electric field.