JPH04236428A - Plasma processor - Google Patents

Abstract

PURPOSE:To enable uniform generation of plasma for wider area by ECR excitation under a lower pressure. CONSTITUTION:A plurality of permanent magnets 21 are radially provided around a reactor 1 at equal intervals, with the one pole S or N directed toward the reactor 1 and the other pole directed toward the outside and with the pole of the permanent magnet 1 directed toward the reactor 1 converted to the different pole alternately at the circumferencial direction of the reactor 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus that performs processes such as film formation and etching using plasma generated by electron cyclotron resonance (ECR) excitation.

0002

[Prior Art] A plasma device using ECR can generate highly active plasma at low gas pressure, and can draw out a relatively large-diameter plasma flow, so it has been used as a device that can be applied to film formation, etching, etc. Research and development is underway. FIG. 3 is a longitudinal sectional view showing a conventional plasma processing apparatus (Japanese Patent Application Laid-Open No. 133636/1983) configured as a film forming apparatus. The plasma generation chamber 31 is formed in a cylindrical shape and has a microwave inlet 31b sealed with a quartz glass plate 31a at the center of its upper wall, and a plasma extraction window 31c at the center of its lower wall. A microwave waveguide 32 is connected to the microwave inlet 31b,
Further, a sample chamber 33 is arranged facing the plasma extraction window 31c, and an excitation coil 34 is arranged concentrically to surround the plasma generation chamber 31 and the waveguide 32. An exhaust port 33a is opened in the lower wall of the sample chamber, and the sample chamber 3
A sample S is placed on a sample stage 35 in the sample table 3.

Reference numeral 36 indicates a gas supply system connected to the plasma generation chamber 31, and 37a and 37b indicate a cooling water supply system and a drainage system. In such a plasma processing apparatus, after setting the inside of the plasma generation chamber 31 and the sample chamber 33 to a predetermined degree of vacuum,
A magnetic field is formed in the plasma generation chamber 31 by the excitation coil 34, and while microwaves are introduced into the plasma generation chamber 31 through the microwave introduction port 31b, gas is supplied through the gas supply system 36 to enter the plasma generation chamber 31. Generate plasma. The generated plasma is projected around the sample S by the divergent magnetic field formed by the excitation coil 34, and a surface reaction is caused by the ions and radical particles in the plasma flow on the surface of the sample S, thereby forming a film. ing.

[0004] However, in such a conventional apparatus, the density of the plasma extracted into the sample chamber 33 through the plasma extraction window 31c is large at the center and small at the periphery. This made it difficult to perform uniform treatment. As a countermeasure to this problem, a plasma processing apparatus as shown in FIG. 4 has been proposed, which uses microwaves to generate plasma over a large area (Japanese Patent Application Laid-open No. 1983-1999-1).
5600). In this plasma processing apparatus, the inside of a metal container 51 is partitioned into upper and lower parts by heat-resistant plates 52 with small dielectric loss, and a dielectric layer 55 is provided on the inner surface of the ceiling wall of an upper chamber 53 to form a microwave waveguide. form,
One end of the waveguide 56 is connected to a microwave oscillator 57.
Connect to. Further, a gas introduction pipe 58 and an exhaust pipe 59 are connected to the peripheral wall of the lower chamber 54, and a sample S is placed at the bottom thereof. 60 is a heater for adjusting the temperature of the sample S.

[0005]

[Problems to be Solved by the Invention] However, when attempting to perform anisotropic etching that suppresses the microloading effect in order to miniaturize LSIs, low pressure (1 mTorr)
However, the above-mentioned conventional apparatus has the disadvantage that it is difficult to generate highly active plasma at a pressure of 1 mTorr or less. The present invention has been made in view of the above circumstances, and its object is to provide a plasma processing apparatus capable of uniformly generating plasma over a large area by ECR excitation under low pressure.

[0006]

[Means for Solving the Problems] A plasma processing apparatus according to the present invention generates microwaves using a dielectric line and a magnetic field using a magnetic field generating means in a metal container in which a sample to be processed is placed. In a plasma processing apparatus that generates plasma in a metal container by electron cyclotron resonance excitation, the magnetic field generating means includes a plurality of magnets arranged around the metal container with one magnetic pole facing toward the metal container, and The magnetic poles adjacent to each other in the circumferential direction are arranged so as to be different magnetic poles from each other.

[0007]

[Operation] According to the present invention, a strong magnetic field is formed in an annular shape along the periphery of the metal container, increasing the plasma density near the periphery of the metal container, and making the plasma density uniform as a whole. .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic front sectional view of a plasma processing apparatus according to the present invention. In the figure, reference numeral 1 denotes a hollow cylindrical reactor, and the entire reactor except for the upper wall is made of metal.In particular, the surrounding wall has a double structure and is provided with a water passage chamber 11 for cooling water inside. The upper wall of the reactor 1 is hermetically sealed with a heat-resistant plate 12 that allows microwaves to pass therethrough and has a small dielectric loss, such as a quartz glass or Al2O3 plate. A sample S is placed inside the reactor 1 using a holder (not shown), and a gas supply pipe 13 is provided through the upper circumferential wall, and an exhaust pipe 14 is provided on the bottom wall. are connected to each other.

Above the heat-resistant plate 12, there is a conductive plate 17, such as an Al plate, large enough to cover the upper surface of the reactor 1 with a required space between it and the heat-resistant plate 12, and a conductive plate 17, for example, an Al plate, on the lower surface thereof. The dielectric line 16 is formed by arranging a dielectric layer 18 having a small dielectric loss and made of, for example, fluororesin, in a laminated state. A microwave oscillator 20 is connected to the side of the dielectric line 16 via a waveguide 19.
The microwave oscillated from the waveguide 19 and the dielectric line 1
6 to form an electric field inside the reactor 1.

In the apparatus of the present invention, a plurality of permanent magnets 21 constituting the magnetic field generating means 2 are arranged along the outside of the upper peripheral wall of the reactor 1. FIG. 2 is an explanatory diagram showing the arrangement of the permanent magnets 21. Each of the permanent magnets 21 has a radial shape with one magnetic pole facing the reactor 1 side and the other magnetic pole facing outward. The magnetic poles of the permanent magnets 21 adjacent in the direction are arranged so as to have different magnetic poles from each other, so that an annular magnetic field 21a is formed within the reactor 1.

The number of permanent magnets 21 is not particularly limited, but in order for adjacent magnetic poles in the circumferential direction to be different magnetic poles, an even number is required, and two permanent magnets cannot form a sufficient magnetic field. It is desirable that there be at least four or more.

In the apparatus of the present invention, an electric field is generated in the reactor 1 through the dielectric line 16, a magnetic field is generated by the magnetic field generating means, and gas is further supplied through the gas supply pipe 13. .

This creates a magnetic field 21a as shown in FIG.
Plasma is generated in a wide area around the area, and it is possible to generate uniform plasma over a large area. Moreover, since the permanent magnet 21 is used to generate the magnetic field, the size can be significantly reduced compared to the case where an excitation coil is used. Of course, if miniaturization is not particularly required, an excitation coil may be used in place of the permanent magnet. Furthermore, since the dielectric line 16 is used, the influence of plasma on the microwave is small, and the propagation characteristics are stabilized.

[Test Example] A test was conducted to form a SiN film on a Si wafer using the plasma processing apparatus shown in FIG. A dielectric layer made of fluororesin was used for the dielectric line 16. A Si wafer with a diameter of 8 inches was set in reactor 1, and the reactor 1 was heated under a predetermined pressure.
N2 and SiH4 gases were introduced into the chamber to generate plasma and form a SiN film on the wafer surface. It was confirmed that the formed SiN film was uniform and homogeneous.

[0015]

[Effects of the Invention] With the device of the present invention, uniform and highly active plasma can be obtained over a wide area, the configuration of the entire device is simplified, and film formation or etching with excellent film quality is possible. The present invention has excellent effects such as:

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional view of the device of the present invention.

FIG. 2 is a schematic diagram showing the arrangement of permanent magnets in the magnetic field generating means in the device of the present invention.

FIG. 3 is a schematic longitudinal sectional view of a conventional device.

FIG. 4 is a schematic longitudinal sectional view of another conventional device.

[Explanation of symbols]

1 Reactor 11 Water flow room 12 Heat resistant board 13 Gas supply pipe 14 Exhaust pipe 16 Dielectric line 17 Conductive plate 18 Dielectric layer 19 Waveguide 20 Microwave oscillator S Sample

Claims (1)

[Claims] [Claim 1] Microwaves are generated by a dielectric line in a metal container in which a sample to be processed is placed, and a magnetic field is generated by a magnetic field generating means, and plasma is generated in the metal container by electron cyclotron resonance excitation. In the plasma processing apparatus, the magnetic field generating means arranges a plurality of magnets around a metal container with one magnetic pole facing toward the metal container, and magnetic poles adjacent to each other in the circumferential direction are different magnetic poles from each other. A plasma processing apparatus characterized in that it is arranged and configured so that