JPH06196446A - High frequency magnetic field excitation treatment device - Google Patents

Abstract

PURPOSE:To prevent the damage such as crystal dislocation and the like caused by plasma irradiation damage to the wafer surface when the thin film on the wafer is etched. CONSTITUTION:The outer wall 1, which forms the outer shell of a plasma generating chamber 9, is formed in hollow conical shape, and high frequency coil 3 is wound in uniform density on the surface of conical circumferential surface of the outer wall 1. Material 12 to be etched is provided on the lower part of the plasma generating chamber 9. High frequency power is applied to a high frequency application coil 3, and a high frequency magnetic field 10 is generated by diverging and attenuating it toward the material 12 to be etched, and plasma etching is conducted by discharging plasma without any electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma etching apparatus or a plasma CVD apparatus used in high frequency magnetic field excitation, particularly in semiconductor manufacturing processes.

[0002]

2. Description of the Related Art A conventional plasma etching apparatus is a method of etching a material to be etched by applying a high frequency wave on a coaxial electrode or a high frequency wave on a counter electrode, that is, a plasma by a capacitive inductive coupling method. The generation method was used.

However, in recent years, for example, 256M-DR
The gate oxide film of an element having a high degree of integration due to AM or the like is extremely thin, and the conventional etching apparatus cannot damage the material to be etched due to plasma irradiation.

Therefore, in recent years, a method of ionizing / exciting a gas gas by using microwaves or a method of ionizing the gas gas by microwaves and causing an electron resonance by using a normal magnetic field to absorb electromagnetic wave energy into electrons, thereby A method of increasing the plasma density is used (for example, JP-A-60-1).
34423, JP-A-63-17529, etc.).

As another method, there is a photoexcitation method in which a photoelectric effect is added to the above-mentioned conventional technique, or a magnetic field assisted excitation method in which a normal magnetic field is generated by an electromagnet or a permanent magnet and a high frequency is applied to the capacitive electrode. (For example, JP-A-63-305516 and JP-A-56-155535).

[0006]

In the capacitive inductive coupling system, which is one of the conventional plasma etching apparatuses, plasma is generated by the electric field generated between the electrodes.
The generation of accelerated ions is large, and this causes the material to be etched to receive collision energy, which causes a problem that damage such as crystal dislocation is large.

Further, in the method using the microwave, the plasma irradiation damage to the material to be etched is small,
It is relatively difficult to generate high-density plasma near the material to be etched, and the etching rate of the material to be etched does not become relatively high.

Further, in order to maintain a high etching rate, a method of applying a high frequency to the material to be etched in addition to the Mythro wave is adopted, but these make the apparatus complicated and make the etching controllability difficult. There was a problem that it would be expensive.

It is an object of the present invention to provide a high frequency magnetic field excitation processing apparatus which prevents damage such as crystal dislocation due to plasma irradiation damage generated on the wafer surface.

[0010]

In order to achieve the above-mentioned object, a high frequency magnetic field excitation processing apparatus according to the present invention has a plasma generating part, and treats a reactive gas which has been turned into plasma by passing through the high frequency magnetic field. A high-frequency magnetic field excitation processing apparatus for treating an object to be processed by bringing it into contact with an object, wherein the plasma generation part generates a high-frequency magnetic field divergently attenuated from an inlet of a reaction gas toward the object to be processed. is there.

Further, the plasma generating portion has an outer wall and a high frequency applying coil, and the outer wall surrounds a space between the introduction port of the reaction gas and the object to be processed and forms a truncated cone-shaped plasma generating chamber. The high frequency applying coil is wound around the conical peripheral surface of the outer wall with a uniform winding density.

Further, the plasma generating portion has an outer wall and a high frequency applying coil, and the outer wall surrounds a space between the introduction port of the reaction gas and the object to be processed to form a cylindrical plasma generating chamber. The high frequency applying coil is wound around the cylindrical peripheral surface of the outer wall while reducing the winding density on the object side.

[0013]

Function: A high-frequency magnetic field whose magnetic field density decreases toward the material to be etched forms an electrodeless plasma discharge.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic view showing a plasma etching apparatus according to Embodiment 1 of the present invention.

In FIG. 1, the plasma etching apparatus according to the present invention has a plasma generating section and an etching section.

The plasma generator is constructed as follows. That is, the plasma generation chamber 9 is formed by being surrounded by the outer wall 1 having a hollow truncated cone shape inside.
A pipe-shaped high-frequency applying coil 3 also serving as a cooling pipe is wound around the conical peripheral surface of with a uniform winding density. An etching gas introducing pipe 2 is provided on the top of the plasma generating chamber 9.

The high frequency applying coil 3 has high frequency conducting tubes 4 and 5 connected to both ends thereof. Coil 3 and conduction tubes 4, 5
Is connected to the inside of the pipe, and the cooling medium flows in the pipe. Furthermore, the coil 3 and the conduction tubes 4, 5
Is electrically connected through the tube wall, and high frequency power is applied. The tube wall of the high frequency conduction tube 5 on the outlet side is grounded via the capacitor 17.

On the other hand, the etching section includes an etching chamber 15
And a wafer holder 11.

The etching chamber 15 is surrounded by the outer wall 14 and is provided below the plasma generating chamber 9.

An etching gas 16 is introduced into the plasma generating chamber 9 from the etching gas introducing pipe 2. On the other hand, the high frequency generated by the high frequency power source 6 is applied to the high frequency applying coil 3 through the high frequency conducting tube 4 which also serves as a cooling pipe. By energizing the high frequency applying coil 3, a high frequency magnetic field 10 having a phase with the applied high frequency is generated. The high frequency magnetic field 10 has a characteristic of divergently decaying in the direction of the material to be etched. Outermost shell electrons of the atoms constituting the molecules of the etching gas 16 supplied from the etching gas introduction tube 2 absorb the high frequency magnetic field energy and are ionized / excited, and the electrons generated by the ionization absorb the high frequency magnetic field energy. To accelerate. Eventually, the electrons that make complicated motions in the high-frequency magnetic field 10 collide with the molecules of the etching gas 16. Upon collision, the molecule is ionized, and one electron becomes 2
Become individual. Each of the two electrons collides with another molecule and ionizes it. In this way, the glow discharge is generated by the so-called electron avalanche phenomenon in which the electrons increase in the mouse arithmetic formula.

Explaining the motion of the generated electrons, the electrons are rotated in the direction perpendicular to the direction of the magnetic force line by receiving the Lorentz force. The radius of gyration is almost inversely proportional to the strength of the magnetic field, and the direction of rotation changes every time the direction of magnetic force lines alternates. Furthermore, since the magnetic field density changes in the direction normal to the plane of rotation of the electrons, the rotation of the electrons causes distortion in the direction in which the magnetic field density decreases. That is, the electrons move in the direction of low magnetic field density while rotating. As a result, the plasma in the plasma generation chamber 9 becomes as if it were drawn out, reaches the material to be etched 12, and performs etching.

The cooling medium 7 flows into the high frequency applying coil 3 through the high frequency conducting tube 4, and the cooling medium 8 is discharged from the high frequency conducting tube 5. On the other hand, the etching chamber 14
The interior is evacuated 13.

(Second Embodiment) FIG. 2 is a diagram showing a second embodiment of the present invention. In the present embodiment, the plasma generating chamber 9 has a cylindrical shape, and the winding density of the high frequency applying coil 3 is reduced toward the etching target material 12.
Regarding the generation mechanism of plasma, the first embodiment described above is used.
It is the same principle as.

[0025]

As described above, according to the present invention, the high frequency applying coil is attached to the outer periphery of the plasma generating chamber to form the high frequency magnetic field in which the magnetic field density decreases toward the material to be etched. It can be performed. The plasma is mainly generated in the plasma generation chamber, and the majority of radical molecules are sometimes generated. The radical molecules fall on the surface of the material to be etched that is adjacent to the radical molecules, and are effective in promoting the etching. Since there is no electrode, a sufficient etching rate can be obtained despite the small amount of accelerated ions. Further, also in the distribution of the etching rate in the plane of the material to be etched, an appropriate spread of the magnetic field, that is, the spread of the plasma can be obtained, so that the distribution can be optimized.

Therefore, the structure can be constructed at a low cost, the etching rate is high while the plasma irradiation damage is suppressed, and the etching rate distribution can be controlled.

Further, by using the deposition gas instead of the etching gas, it can be applied to the plasma CVD, and the plasma irradiation damage can be suppressed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 1 outer wall for plasma generating chamber 2 etching gas introducing chamber 3 high frequency applying coil 4, 5 high frequency conducting tube also serving as cooling pipe 6 high frequency power supply 7, 8 cooling water 9 plasma generating chamber 10 high frequency magnetic field 11 wafer holder 12 wafer 13 vacuum exhaust 14 External wall for etching chamber 15 Etching chamber 16 Gas 17 Capacitor

Claims (3)

[Claims] 1. A high-frequency magnetic field excitation processing apparatus having a plasma generation part, wherein a reaction gas that has passed through a high-frequency magnetic field and turned into plasma is brought into contact with the object to be processed to process the object. The high frequency magnetic field excitation processing device, wherein the plasma generating unit generates a high frequency magnetic field that is divergently attenuated from the reaction gas inlet toward the object to be processed. 2. The plasma generating part has an outer wall and a high frequency applying coil, and the outer wall surrounds a space between the introduction port of the reaction gas and the object to be processed and forms a truncated cone-shaped plasma generating chamber. The high-frequency magnetic field excitation processing device according to claim 1, wherein the high-frequency applying coil is wound around the conical peripheral surface of the outer wall with a uniform winding density. 3. The plasma generating part has an outer wall and a high frequency applying coil, and the outer wall surrounds the space between the introduction port of the reaction gas and the object to be processed to form a cylindrical plasma generating chamber. The high-frequency magnetic field excitation coil according to claim 1, characterized in that the high-frequency application coil is wound around the cylindrical peripheral surface of the outer wall while reducing the winding density on the object side. Processing equipment.