JPH05144777A - Low temperature dry etching apparatus - Google Patents

Abstract

PURPOSE:To provide a parallel plate dry etching apparatus with a good cooling efficiency, a high safety and reliability, and a low running cost capable of controlling a substrate accurately at any an arbitrary temperature from cryogenic temperature to room temperature. CONSTITUTION:A parallel plate dry etching apparatus for low temperature dry etching apparatus comprises an etching chamber 10, reaction gas supply means 14, etching chamber exhaust means 20, cooling means 18, a thermometer 22, an RF power line 16, heat transfer control means 40 which consists of a gas supply line for heat transfer control and the cooling means 18 for cooling an electrode plate 12 on which an etched substrate 100 is placed to a crogenic temperature and controls heat transfer between the electrode plate 12 and the etched substrate 100 by the flow rate of gas for heat transfer control, and temperature control means 52 for controlling the heat transfer control means 40 by measuring the temperature of the etched substrate 100 with the thermometer 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel plate type low temperature dry etching apparatus used for manufacturing semiconductor devices, liquid crystal display devices and the like.

[0002]

2. Description of the Related Art Dry etching is one of the fine processing techniques.
It is a key process technology that holds two keys. High dimensional accuracy machinability is important for dry etching technology.
Examples include etching selectivity, throughput, processing uniformity, damage, and contamination.

A low temperature dry etching technique, which is one field of the dry etching technique, is drawing attention. This low-temperature dry etching technique is a technique that newly adds a function of controlling the surface reaction by plasma by keeping the wafer temperature low. That is, regarding the chemical reaction and physical sputtering in the reactive ion etching, the chemical reaction is frozen by lowering the temperature of the wafer surface, and the processability with high dimensional accuracy, the etching selectivity, the high etching rate, the resist and the substrate It is intended to control the selectivity and the like.

In order to etch a wafer by cooling it to, for example, 0 ° C. or lower, it is necessary to control the temperature of the wafer during etching and to cool the wafer. "Low temperature etching technology for submicron process", Semicon NE
WS1989, 11 (Hitachi Central Research Laboratory) pp 148-154 discloses a low temperature microwave etching apparatus and a low temperature reactive ion etching apparatus.
In these devices, the temperature of the substrate to be etched is monitored with a thermocouple. Liquid nitrogen is used as a coolant, and the substrate to be etched is cooled by accumulating the liquid nitrogen in a container arranged below the electrode on which the wafer is mounted.

A semiconductor manufacturing apparatus such as an ion implantation apparatus or an ion milling apparatus equipped with a means for holding a wafer at 100 to 120 ° C. is disclosed in, for example, Japanese Patent Laid-Open No. 63-1336.
It is known from Japanese Patent No. 31. In these semiconductor manufacturing apparatuses, low-pressure air is interposed between a rotating disk and a plurality of wafers mounted on the top surface of the rotating disk, and the temperature of the wafer is controlled by the molecular heat conduction of the air. .. The means for holding the wafer at a constant temperature comprises an automatic pressure adjusting means for automatically adjusting the pressure of the low pressure air, specifically, an air reservoir.

An etching apparatus for controlling a wafer at a predetermined temperature before plasma etching or reactive ion etching is disclosed in, for example, Japanese Patent Laid-Open No. 63-141317.
It is known from the publication. In this etching apparatus, the temperature of the wafer is controlled by heating and cooling an inert gas.

[0007]

In the above low temperature microwave etching apparatus or low temperature reactive ion etching apparatus, the following points are considered to be problems. (1) Since the temperature of the wafer is controlled by using liquid nitrogen and a heater together, the cooling efficiency is poor, a large amount of liquid nitrogen and electric power are consumed, and the operating cost of the apparatus becomes enormous. In addition, the device may be condensed and frozen. (2) It is possible to use CFC as an alternative to liquid nitrogen, but from cryogenic temperature (-140 ° C) to room temperature (+2
There is no Freon circulation refrigerator that can variably control the temperature up to 0 ° C. Further, when the Freon circulation refrigerator and the heater are used together, adiabatic expansion occurs because the Freon gas circulation system is a closed loop. As a result, the CFC gas circulation system is damaged or the circulation system becomes a high pressure, and there is a high risk. (3) When liquid nitrogen or CFC circulation refrigerator and a heater are used together, a rapid thermal cycle is continuously applied to the components of the equipment. As a result, the seal portion of the device and the coating material are likely to be damaged or leak due to the difference in the coefficient of thermal expansion of each material.

In the semiconductor manufacturing apparatus described in Japanese Patent Laid-Open No. 63-136331, the low pressure gas consisting of air is used merely to improve heat transfer between the cooling surface and the wafer, and the temperature of the wafer is It is controlled exclusively by the flow rate of the cooling fluid flowing through the cooling channel. That is, the wafer cannot be controlled to an arbitrary temperature by appropriately adjusting the amount of low pressure gas. Further, it has no control means for controlling the amount of low-pressure gas by measuring the temperature of the wafer.

In the etching apparatus described in Japanese Patent Laid-Open No. 63-141317, the temperature of the wafer is controlled by heating and cooling the inert gas, and the wafer is in direct contact with the inert gas. The technique disclosed in this publication cannot keep the wafer at a low temperature.

Therefore, an object of the present invention is a parallel plate type which is excellent in cooling efficiency, high in safety and reliability, low in operating cost, and capable of accurately controlling a substrate to any temperature from extremely low temperature to normal temperature. It is to provide a dry etching apparatus.

[0011]

The above object can be achieved by a parallel plate type low temperature dry etching apparatus constructed as follows. That is, the apparatus of the present invention comprises an etching chamber, a reaction gas supply unit, an etching chamber exhaust unit, a cooling unit, a thermometer, and an RF power supply system.
Further, (A) a cooling means for cooling the electrode plate on which the substrate to be etched is placed to an extremely low temperature, and (B) a gas supply system for heat transfer control, which are used for the transfer between the electrode plate and the substrate to be etched. Heat transfer control means for controlling heat by the flow rate of the heat transfer control gas; and (C) temperature control means for controlling the heat transfer control means by measuring the temperature of the substrate to be etched by the thermometer. It is characterized by having.

The heat transfer control gas is preferably an inert gas such as nitrogen or helium gas.

The low temperature dry etching apparatus of the present invention comprises:
A load lock chamber for loading / unloading the substrate to be etched into / from the etching chamber, and a load lock chamber evacuation unit may be provided.

The low temperature dry etching apparatus of the present invention may be, for example, a low temperature reactive ion etching apparatus, a low temperature plasma CVD apparatus, a low temperature ECR etching apparatus, or any other apparatus that requires wafer temperature control within a vacuum apparatus. it can.

[0015]

According to the present invention, by the cooling means, for example, -1
The electrode plate is cooled to an extremely low temperature of about 40 ° C. The heat transfer from the electrode plate to the substrate to be etched is controlled by the flow rate of the heat transfer control gas. The flow rate of the heat transfer control gas is accurately controlled by measuring the temperature of the substrate to be etched with a thermometer. As a result, the temperature of the substrate to be etched is changed from an extremely low temperature of −140 ° C. to + 20 ° C.
It can be arbitrarily maintained or changed to a desired temperature up to room temperature of about ° C with high precision.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A low temperature dry etching apparatus of the present invention will be described below with reference to FIG.

The apparatus of the present invention includes an etching chamber 10 for performing a dry etching process, an electrode plate (cathode electrode).
12, reaction gas supply means 14, RF power supply system 16, cooling means 18, etching chamber exhaust means 20, thermometer 2
2. A load lock chamber 24 for loading / unloading the substrate into / from the etching chamber 10 and a load lock chamber exhausting means 26. Further, the apparatus of the present invention comprises heat transfer control means 40 and temperature control means 52.

The electrode plate 12 is arranged in the etching chamber 10. The substrate to be etched 100 is the electrode plate 12
Placed on top. The electrode plate 12 can be made of, for example, a material called a clad steel plate in which stainless steel and aluminum are bonded together by an explosive force. A mechanical chuck or an electrostatic chuck can be used to grip the substrate to be etched 100 on the electrode plate 12. A counter electrode is provided above the substrate to be etched (not shown).

The cooling means 18 comprises a refrigerator 18A, a refrigerant circulation system 18B, and a cooling jacket (not shown) provided in the electrode plate 12. By using, for example, Freon gas as the coolant and circulating the coolant in the cooling means, the electrode plate 12 can be cooled to an extremely low temperature.

The heat transfer control means 40 comprises a heat transfer control gas supply system. The heat transfer control gas supply system includes a heat transfer control gas supply source 42, for example, a mass flow controller, and a flow rate control unit 44 for controlling the flow rate of the heat transfer control gas.
And a heat transfer control gas passage 46. The heat transfer control gas supply system includes a vacuum gauge 48 for measuring the pressure in the heat transfer control gas passage 46, and a pump 50 for exhausting the heat transfer control gas from the heat transfer control gas passage. Is preferably provided. The vacuum gauge 48 is, for example, a Pirani vacuum gauge,
The pump 50 can be, for example, a rotary pump. The heat transfer control gas is composed of nitrogen gas.

On the surface of the electrode plate 12 which comes into contact with the substrate 100 to be etched, for example, a groove-shaped void 12A is provided. In order to improve the heat transfer between the electrode plate 12 and the substrate 100 to be etched, the heat transfer control gas is supplied from the heat transfer control gas passage 46 to the void 12A.

The temperature control means 52 can be composed of, for example, a central processing unit. Temperature control means 52
Is connected to the output of the thermometer 22 and the input of the flow control means 44. Then, the temperature control means 52 controls the flow rate control means 44 based on the temperature of the substrate to be etched 100 measured by the thermometer 22. As a result, the flow rate of the heat transfer control gas flowing through the heat transfer control gas passage 46 is controlled.

A vacuum gauge 48 and a pump 50 are provided in the heat transfer control gas supply system, and the output part of the vacuum gauge 48 is connected to the temperature control means 52. Then, the flow rate of the heat transfer control gas flowing through the heat transfer control gas flow path 46 is monitored with high accuracy by monitoring the flow rate of the heat transfer control gas flowing through the heat transfer control gas flow path 46 with the vacuum gauge 48. Can be controlled.

The reaction gas supply means 14 includes a mass flow meter 14A, and various gases such as CHF ₃ , CH ₄ and HBr are supplied to the etching chamber 10 through the reaction gas supply system 14.

The RF power supply system 16 includes a DC high voltage power supply arranged outside the etching chamber and a frequency of 13.56.
It consists of an RF power source of MHz, a matching box, and an RF waveguide connected to the matching box and the electrode plate 12 (these are not shown). RF power is sent to the electrode plate 12 from the matching box through the RF waveguide.

The etching chamber exhaust means 20 exhausts the reaction gas and reaction products in the etching chamber 10. The etching chamber exhaust means 20 includes an etching chamber exhaust port 20A provided in the etching chamber 10, a turbo molecular pump connected to the etching chamber exhaust port 20A, a dry pump, and an exhaust gas treatment device (these are not shown). Become.

The load lock chamber exhaust means 26 is a mechanical booster pump and a dry pump (not shown).
Consists of.

The thermometer 22 preferably comprises a fluorescent fiber thermometer. This thermometer measures the temperature by utilizing the fluorescence relaxation characteristic of the fluorescent substance (the property that the time required for the fluorescent substance to decay the fluorescence upon receiving light of a specific wavelength changes depending on the ambient temperature). Is. For example, an optical fiber probe having a magnesium phosphor adhered to the tip thereof is brought into contact with the substrate to be etched, pulsed light for excitation is emitted from the light source, the returning fluorescence is received, arithmetic processing is performed, and temperature is displayed. The temperature detection part of the glass fiber fluorescent fiber thermometer is in contact with the substrate to be etched (not shown in FIG. 1), and thereby the temperature of the cooled substrate to be etched 100 is accurately measured. be able to.

FIG. 2 shows changes in the temperature of the substrate 100 to be etched and the temperature of the electrode plate 12 when the apparatus of the present invention is used. A few minutes after starting the supply of the heat transfer control gas composed of nitrogen, the temperature of the substrate to be etched 100 and the electrode plate 1
It becomes almost equal to the temperature of 2.

FIG. 3 shows the degree of vacuum in the vacuum gauge 48 as 10P.
The temperature change of the to-be-etched substrate 100 when changing from a to 1000 Pa is shown. The degree of vacuum of the vacuum gauge 48 changes according to changes in the flow rate of the heat transfer control gas. As is clear from FIGS. 2 and 3, the temperature of the substrate to be etched can be easily and accurately controlled from extremely low temperature to normal temperature by changing the flow rate of the heat transfer control gas.

Although the low temperature dry etching apparatus of the present invention has been described above based on the preferred embodiments, the apparatus of the present invention is not limited to such embodiments. An inert gas such as helium gas can be used as the heat transfer control gas. Further, for example, the turbo molecular pump can be replaced with a diffusion pump or a cryopump. Any thermometer may be used as long as it can measure the temperature of the substrate to be etched accurately and stably. In addition to CFC gas, an antifreeze liquid, a silicon-based refrigerant, or an alcohol-based refrigerant may be used.

[0032]

According to the apparatus of the present invention, the temperature of the substrate to be etched is controlled from an extremely low temperature such as −140 ° C. to +
It can be arbitrarily maintained or changed to a desired temperature up to room temperature of about 20 ° C. with high precision.

Further, in the apparatus of the present invention, the substrate to be etched can be made to have an extremely low temperature without using liquid nitrogen, and the temperature of the substrate to be etched can be controlled without using a heater. .. Therefore, it is possible to prevent adiabatic expansion in the cooling means, which not only excels in the safety of the device but also makes it possible to reduce the operating cost of the device. Further, since the temperature of the substrate to be etched can be adjusted while the electrode plate is kept at an extremely low temperature, it is possible to prevent material damage or leak due to the difference in thermal expansion coefficient between different materials forming the cooling means. You can

[Brief description of drawings]

FIG. 1 is a schematic diagram of a low temperature dry etching apparatus of the present invention.

FIG. 2 is a diagram showing a temperature change of a substrate to be etched and a temperature of an electrode plate.

FIG. 3 shows the degree of vacuum in a vacuum gauge from 10 Pa to 1000.
It is a figure which shows the temperature change of the to-be-etched substrate when changing to Pa.

[Explanation of symbols]

 10 Etching Chamber 12 Electrode Plate 12A Gap 14 Reactive Gas Supply Means 14A Mass Flow Meter 16 RF Power Supply System 18 Cooling Means 18A Refrigerator 18B Refrigerant Circulation System 20 Etching Chamber Exhaust Means 20A Etching Chamber Exhaust Port 22 Thermometer 24 Load Lock Chamber 26 Load Lock Chamber evacuation means 40 Heat transfer control means 42 Heat transfer control gas supply source 44 Flow rate control means 46 Heat transfer control gas passage 48 Vacuum gauge 50 Pump 52 Temperature control means 100 Substrate to be etched

Claims (2)

[Claims] 1. An etching chamber, a reaction gas supply means,
A parallel plate type low temperature dry etching apparatus comprising an etching chamber exhausting means, a thermometer, and an RF power supply system, wherein (A) a cooling means for cooling the electrode plate on which the substrate to be etched is placed to an extremely low temperature; B) a heat transfer control means for controlling heat transfer between the electrode plate and the substrate to be etched according to the flow rate of the heat transfer control gas, and (C) a temperature of the substrate to be etched. And a temperature control unit that controls the heat transfer control unit by measuring the temperature with the thermometer. 2. The low temperature dry etching apparatus according to claim 1, wherein the heat transfer control gas is made of an inert gas.