JPH04280628A - Dry-etching device - Google Patents

Abstract

PURPOSE:To eliminate the uneven etchig step due to the differences both in the concentration and the pressure of a reactive gas between the central part and the peripheral part of a wafer. CONSTITUTION:A chamber 11 is sectioned by grounded meshes 12. These meshes work as upper electrodes, gas exhaust ports and gas leading-in ports. A gas leading-pipe 13 is arranged above these meshes 12 while an exhaust dispersion sheet 15 is provided above the pipe 13. A variable conductance valve 17 and a turbo-pump 16 are provided on the surface of the chamber 1. On the other hand, a high-freuqncy impression electrode 18 is provided beneath the gas leading-in pipe 13 and the meshes 12.

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 used in an etching process in the manufacture of ICs.

0002

[Prior Art] Conventionally, this type of device was
There was one disclosed in No. 1-86546.

FIG. 2 shows a block diagram of the main parts of a conventional device.

In dry etching, a reactive gas is introduced into the processing chamber and set at a predetermined pressure, and then RF is applied between the upper electrode and the lower electrode to turn the reactive gas into plasma, and the sample placed on the lower electrode is heated. It is etched.

[0005] An apparatus in which the electrodes are flat on both the upper and lower sides and placed in parallel as shown in FIG. 2 is called a parallel plate type dry etching apparatus and is generally used.

The operation of the apparatus shown in FIG. 2 will be described below as an example.

Inside the processing chamber 1, a lower electrode 3 and an upper electrode 2 are installed facing each other.

Inside the upper electrode 2, reaction gas reservoirs 4, 4a are provided at the center and periphery thereof.

The reaction gas is discharged from the gas introduction pipes 6, 6a into the processing chamber through a large number of reaction gas introduction holes 5, 5a provided at the bottom of each of the reaction gas reservoirs 4, 4a.

The released reaction gas is partially consumed by etching a sample (not shown) placed on the lower electrode 3, and is then exhausted from an exhaust port 8 provided around the lower electrode 3. be done.

Etching uniformity can be improved to some extent by changing the ratio of reaction gases flowing through the gas introduction pipes 6, 6a.

0012

However, with the above-described apparatus, a problem has arisen in that it is difficult to obtain uniform etching as the diameter of the wafer increases.

The following points can be cited as causes of non-uniform etching.

■ Fresh reaction gas is supplied to the center of the wafer, whereas at the periphery of the wafer, a part of the reaction gas has already been consumed in the center and a part of the reaction gas has been newly supplied at the periphery. A mixture of reactant gases is supplied. This causes a difference in the concentration of the reactive gas between the center and the periphery of the wafer, resulting in non-uniform etching.

(2) A pressure difference occurs between the center and the periphery of the wafer due to the relationship between the conductance and the supplied gas flow rate, resulting in non-uniform etching.

As described above, the present invention solves the problems of conventional equipment, such as non-uniform etching due to the difference in concentration of reactive gas between the center and periphery of the wafer, and conductance and supply problems between the center and periphery of the wafer. An object of the present invention is to provide a dry etching apparatus that can eliminate uneven etching caused by pressure differences caused by the relationship between gas flow rates.

[0017]

[Means for Solving the Problems] The dry etching apparatus of the present invention has a gas inlet and an exhaust gas installed opposite to the wafer installation part of the reaction chamber so that the gas inlet and exhaust are uniform within the surface of the wafer to be etched. It has a mesh that includes an opening and an exhaust port.

[0018]

[Operation] The dry etching apparatus of the present invention introduces a predetermined flow rate of reaction gas through the gas introduction pipe, adjusts the variable conductance valve to an appropriate opening degree, and sets the pressure inside the reaction chamber to a predetermined pressure. When the pressure stabilizes at a predetermined set value, high frequency power is applied to the high frequency application electrode. Exhaust gas from etching the object to be processed is uniformly exhausted from the reaction chamber through the mesh.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a reactive ion etching apparatus to which the present invention is applied. First, the configuration of this device and each component will be explained.

The cylindrical chamber 11 is delimited by a grounded mesh 12. The mesh 12 used is a thin plate made of aluminum with a thickness of 0.5 mm, in which openings of 3 mm diameter are evenly provided over the entire surface, and the opening ratio is about 50%. The mesh 12 has the roles of an upper electrode, a gas exhaust port, and a gas inlet.

[0021] Above this mesh 12 is a gas introduction pipe 13.
is provided. The gas introduction pipe 13 is branched into an octopus shape so that its end face is evenly provided over the entire surface of the mesh. After the branching of the gas introduction pipe 13, stainless steel piping with an outer diameter of 1/8 inch is used, and before the branching, stainless steel piping with a diameter of 3/8 inch is used. The end face of the gas introduction pipe 13 is in contact with the opening of the mesh 12, and the reaction gas is introduced into the reaction chamber 14 through the mesh 12.

An exhaust dispersion plate 15 is provided above the gas introduction pipe. The exhaust dispersion plate 15 is made of an aluminum plate with a thickness of 1 mm, with openings of 10 mm in diameter provided over the entire surface to give an aperture ratio of about 40%. The openings are arranged so that the openings are denser at the periphery than at the center, and the conductance is adjusted so that exhaust is uniformly carried out over the entire surface of the mesh 12.

[0023] On the upper surface of the chamber 11 is a turbo pump 1.
6 and a variable conductance valve 17 are provided. The gas in the reaction chamber 14 is exhausted by the turbo pump 16 through the mesh 12, the openings of the exhaust dispersion plate 15, and the variable conductance valve 17.

Next, the operation of this device will be explained.

An object to be processed consisting of a semiconductor wafer is placed on the high frequency application electrode 18 .

With the variable conductance valve 17 fully open, the chamber 11 is evacuated to a high vacuum by the turbo pump 16.

A predetermined flow rate of reaction gas is introduced through the gas introduction pipe 13, and the variable conductance valve 17 is adjusted to an appropriate opening degree, thereby setting the pressure inside the reaction chamber 14 to a predetermined pressure.

When the pressure becomes stable at a predetermined set value, high frequency power is applied to the high frequency application electrode 18.

Exhaust gas from etching the object to be processed is uniformly exhausted from the reaction chamber 14 through the mesh 12, and fresh reaction gas is uniformly introduced into the reaction chamber 24 through the mesh 12, so that the reaction The gas composition and pressure within the chamber 14 become constant, and a uniform etching rate can be obtained within the surface of the object to be processed.

[0030]

Effects of the Invention As is clear from the above explanation, a mesh including a gas inlet and an exhaust port is provided on the opposite surface of the wafer installation part of the reaction chamber, so that the reaction gas can be uniformly introduced to the wafer installation part. By exhausting the exhaust gas, the following effects can be obtained.

(2) Since the gas composition and pressure within the chamber are uniform, a uniform etching rate can be obtained.

(2) Since the area of the exhaust port can be increased, the exhaust efficiency is improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts of a reactive ion etching apparatus to which the present invention is applied.

FIG. 2 is a sectional view of main parts of a conventional dry etching apparatus.

[Explanation of symbols]

11 Chamber 12 Mesh 13 Gas introduction pipe 14 Reaction chamber 15 Exhaust dispersion plate 16 Turbo pump 17 Variable conductance valve 18 High frequency application electrode 19 Rotary pump

Claims (1)

[Claims] 1. A dry etching apparatus comprising: a wafer installation part provided in a reaction chamber; and a mesh including a gas inlet and an exhaust port provided opposite to the wafer installation part.