JPH02254170A - Plasma treating device - Google Patents

Abstract

PURPOSE:To increase the area of a region subjected to treatment and the rate of treatment by fitting a flat coil to the side of a sample stand reverse to the sample holding side in a device for treating a sample by irradiation with plasma generated by utilizing microwaves. CONSTITUTION:Microwaves are introduced into a plasma generation chamber 1, plasma is generated and a sample 11 on a sample stand 10 is treated with a plasma jet 8 led from the chamber 1. A flat coil 15 is fitted to the side of the stand 10 reverse to the sample holding side. The distribution of a magnetic field near the stand 10 is controlled by the coil 15 and a uniform high rate of plasma treatment is obtd.

Description

[Detailed description of the invention] 1 industrial use! l! f] The present invention relates to a plasma processing apparatus used for forming a thin film on the surface of a material or etching the surface of a material by using plasma and the ions contained therein, and particularly relates to a plasma processing apparatus used for etching various types of semiconductor integrated circuits. The present invention relates to a plasma processing apparatus that is compatible with device manufacturing processes.

[Prior art] As a plasma generation method used for thin film formation and etching, there is a plasma generation method that utilizes electron cyclotron co-pulsation by microwave excitation, which has the characteristics of low gas pressure, high ionization rate, and high activity. It has been revealed that excellent processing characteristics can be exhibited by selecting the introduced gas and controlling the ion energy.

FIG. 7 shows a basic configuration diagram of a conventional plasma processing apparatus that utilizes microwave electron cyclo1-ron resonance plasma. Here, 1B is a plasma generation chamber, 2 is a sample chamber, and 12 is a plasma generation chamber.
3 is an exhaust path, and 3 is a microwave introduction window, which is made of, for example, a quartz glass plate. 4 is a rectangular waveguide for introducing microwaves. Reference numeral 9 denotes a plasma extraction window for guiding the plasma generated in the plasma generation chamber 1 to the fitting 11 placed on the fitting 10. Reference numeral 13 denotes a magnetic coil for generating a magnetic field strength that satisfies the electron cyclo-l-ron mutual duck condition in a suitable region inside the plasma generation chamber 1;
It is also used to form a divergence 611 field for forming the plasma flow 8. A microwave source (not shown) is configured using, for example, a magnetron with a frequency of 2.45 GHz. Reference numeral 5 designates a cooling channel for the plasma generation chamber, and 6 and 7 designate a first gas introduction system and a second gas introduction system for gas regulators, which are used singly or in combination depending on the processing purpose.

For example, to form a silicon nitride film, gas is introduced from the first gas introduction system 6 and 5it14 gas is introduced from the second gas introduction system 7. In the case of etching, cf! from the first gas guide 16 or the second waste introduction system 7! , 2SF6.02 etching gas is introduced.

The in-plane distribution of the sample during processing such as thin film formation or etching depends on the plasma density formed by the plasma generation table ≦ 1, the density of the drawn plasma flow, etc. Because it has ζJ, it is necessary to further improve the homogeneity when applying it to large-area samples. Thin film formation and etching reactions are mainly promoted by electrons that move along the magnetic field lines of the divergent magnetic field and by ions generated by collisions between electrons and gas molecules, so the divergent magnetic field distribution can be controlled. By doing so, it is possible to improve the distribution of plasma processing speed within the fitting surface.

FIG. 8 shows a schematic configuration diagram of a plasma processing apparatus to which a conventional magnetic field distribution correction coil is added. Try this diagram! The four chambers are shown in an enlarged view, and the configuration of the other NS portions is the same as in FIG. 7. A solenoid coil 14 is disposed on the back side of the fitting table 1o, and a reverse current is passed through the magnetic coil 13 for the divergent magnetic field to control the divergent magnetic field distribution within the sample plane.

[Problems to be solved and attempted by the invention] Although it is possible to improve the uniformity to some extent with the configuration shown in Fig. 8, since the coil is solenoid-shaped, the control of the divergent magnetic field distribution is only partial, resulting in flatness. It is difficult to obtain a uniform processing speed distribution, the volume of the coil is large, so it is necessary to secure an installation location separate from the sample stage, and in order to prevent the generation of Mifs and dust from the coil, it is difficult to install the coil. There are various problems with the device configuration, such as installation outside the sample chamber. If the magnetic field distribution in the sample plane can be controlled over a wide range to an optimal distribution, and if a small and thin coil can be created, significant improvements in characteristics such as an expansion of the processing area and an increase in processing speed can be expected, as well as ease of equipment configuration.

The present invention solves the above-mentioned conventional drawbacks, and provides a plasma processing apparatus that can control the divergent magnetic field distribution of plasma flow over a wide range, improve the uniformity of processing speed, and improve the processing area and processing speed. The purpose is to

[Means for Solving the Problems] The present invention provides a plasma processing apparatus that generates plasma using microwaves and processes the sample by irradiating the sample with plasma or mainly ions in the plasma. It is characterized in that at least one flat coil for controlling the magnetic field distribution in the vicinity of the sample stand surface is provided on the opposite side of the sample holding surface of the fitting stand.

[Function] The flat coil of the present invention is a thin disk-shaped coil spirally wound in the diametrical direction, and the magnetic field distribution near the sample stage surface of the divergent magnetic field extracted from the plasma generation chamber is determined by the winding density of the coil. By setting the distribution, the distance between the fitting table and the coil, and the coil current, it is possible to control over a wide range and achieve a flat plasma processing rate with good uniformity. The combination of the coil and sample stand is possible because the overall thickness of the coil is thin, so it is possible to configure the sample stand and the body, and in order to cool the sample, cooling water can be circulated to the four sample samples. The structure VzuJl is
It can also be used in conjunction with coil cooling and is effective. Furthermore, even when adopting the electrostatic absorption S method for holding the sample on the sample stage and the RF application J method for applying bias to the sample,
It is possible to incorporate the flat coil of the present invention into a fitting table.

[Example] The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the configuration of a plasma processing apparatus in which the present invention is implemented. FIG. 1 shows an enlarged view of the sample chamber, and the configuration of other parts is the same as that in FIG. 7. A sample 11 on a sample stage 10 is subjected to plasma treatment by a plasma flow 8 introduced through a plasma extraction window 9 of the plasma generation chamber 1 . A flat coil 15 was placed on the back surface of the sample stage 10 so that its central axis coincided with that of the magnetic coil 13 for generating a divergent magnetic field. The flat coil has a structure in which it is spirally wound in the diametrical direction from the central axis.
In the experimental example, a polyimide-coated copper wire with a wire diameter of 1.5 mm was used as the coil wire, and in order to increase the magnetic field strength, it was stacked in two layers, and the overall thickness of the coil was approximately 1 mm, and the diameter was lO~
It is about 70cm.

With this configuration, the magnetic field distribution within the sample plane of the plasma flow drawn by the emitted magnetic field is controlled by the flat coil that generates a magnetic field in the opposite direction to the emitted magnetic field. The magnetic field strength in the four planes of the test case with only the divergent magnetic field is at the center or high < (115
G) It gradually decreased toward the circumference (9 from the center)
It has a distribution of 100G at the position of cm 1lIff.

In order to confirm the effect of using the flat coil of the present invention, a film formation experiment was conducted using a silicon oxide film. In this experiment, the film formation conditions were 02:30cc/m1nSit14:
30cc/+nj port, microwave power 200W. A 5-inch to 6-inch S] wafer was used as the sample.

FIG. 2 shows a schematic configuration diagram of a disk-shaped flat coil. The coil has a diameter of 14 cm and has a high winding density that is spirally wound sequentially from the central axis in the diametrical direction, and the coil and sample are 5 m long.
mmf. FIG. 3 shows the magnetic field distribution and film formation rate distribution when this disc-shaped flat coil is used. The &H magnetic field distribution of this coil has a pyramid shape where the magnetic field is strongest at the center of the coil. The film formation rate distribution obtained is that when the coil current is 5.5 cm, the center 4 cm range is flat, and when the coil current is 7.5 cm, the center 7 cm range is flat, compared to when no coil is used. Ta.

FIG. 4 shows a schematic configuration diagram of a doughnut-shaped flat coil. The coil shape is 18cm in diameter with a center diameter of 10cm.
The coil was hollow, and the distance between this coil and the sample stage was set to 10 a+m in order to obtain a somewhat gentle magnetic field distribution. FIG. 5 shows the magnetic field distribution and film formation rate distribution when this doughnut-shaped flat coil is used. The magnetic field distribution of this coil has a trapezoidal shape, and the portion corresponding to the upper side of this trapezoid corresponds to the hollow diameter of the coil of 10 cm. The actual in-plane distribution of the sample is a combination of the diverging magnetic field distribution, and the outer peripheral portion with a diameter of 10 cm has a high magnetic field strength. As a result of using this coil, it was observed that the uniformity of the film formation rate distribution was improved over a wide range. For example, at a position ±6.5 cm from the center of the sample surface, the non-uniformity would be ±10% if the coil was not used. Whereas, the coil current 1
At 0 A, the nonuniformity was reduced to ±5%, which is half of the conventional level. FIG. 6 shows a schematic configuration diagram of a flat coil when winding density is considered. The coil has a structure in which the central part of the coil is wound with a certain interval, and the peripheral part is wound tightly.The magnetic field distribution of this coil takes a curved shape that gradually decreases from the central part of the coil to the circumference, making it easy to control the divergent magnetic field. In addition, the uniformity of the distribution within the sample plane can be further improved.

As a modification of the present invention, it is also possible to form a magnetic field distribution that provides the same effect by using a plate-shaped permanent magnet with a set magnetic field distribution, or by combining the present invention with a high magnetic permeability old material such as soft iron. . It is also possible to further improve the controllability of the magnetic field distribution by combining a plurality of flat coils.

[Effects of the Invention] As is clear from the above explanation, in the apparatus of the present invention, the flat coil is used to control the CC magnetic field component over a wide range, which improves the uniformity of the plasma processing speed. This has the advantage that it is possible to expand the plasma processing area, improve throughput, and in terms of the device configuration, it can be easily combined with a sample stage.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an embodiment of the present invention, Fig. 2 is a schematic cross-sectional view of a disc-shaped flat coil, and Fig. 3 is a diagram showing magnetic field distribution and 5in2 film formation film shape when using a disc-shaped flat coil. Figure 4 is a schematic cross-sectional view of a donut-shaped flat coil, Figure 5 is a diagram showing the magnetic field distribution and SiO□ film formation rate distribution when a donut-shaped flat coil is used, and Figure 6 is a diagram showing the winding speed. FIG. 7 is a schematic cross-sectional view of flat coils with different densities, FIG. 7 is a basic configuration diagram of a plasma processing apparatus, and FIG. 8 is a schematic diagram of an apparatus using a conventional magnetic field distribution correction coil. DESCRIPTION OF SYMBOLS 1... Plasma generation chamber, 2... Sample chamber, 3... Microwave introduction window, 4... Rectangular waveguide, 5... Cooling channel, 6... First gas introduction system, 7... Second gas guide system, 8... Plasma flow, 9... Plasma extraction window, 10... Sample stage, 11... Sample, 12... Exhaust system, 13... Magnetic coil, 1. Solenoid coil, 15. Flat coil.

Claims (1)

[Claims] 1) In a plasma processing apparatus that generates plasma using microwaves and processes a sample by irradiating the plasma or mainly ions in the plasma, a sample holding surface of a sample stage for holding the sample; A plasma processing apparatus characterized in that the opposite surface is provided with at least one flat coil for controlling the magnetic field distribution near the surface of the sample stage.