JPH036381A - Microwave plasma processing equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a microwave plasma processing apparatus that utilizes electron cyclotron resonance, and is particularly concerned with improving plasma processing efficiency and reducing contamination and foreign matter contamination of substrates. The present invention relates to a plasma processing apparatus suitable for processing.

[Conventional technology]

As described in Japanese Patent Application Laid-Open No. 195124/1984, the conventional apparatus draws plasma generated on the ECR surface of a discharge tube into a substrate processing chamber using a divergent magnetic field and a grid, and then uniformly spreads it onto a substrate using a horn-shaped metal cylinder. The board was processed by flowing it so that it was.

[Problems to be Solved by the Invention] The above-mentioned conventional technology does not take into account the problems that occur when plasma hits objects that extend into space, such as the inner wall of a vacuum container, conductive tubes, and grids.
There have been problems in that due to substrate contamination and the generation of foreign substances, semiconductor devices with appropriate device characteristics cannot be manufactured, and yields are low.

The present invention aims to solve the above-mentioned disadvantages.

[Means to solve the problem]

In order to achieve the above object, the present invention provides EC in a vacuum container.
ECR only in the - part of the space where the R condition is satisfied
It is designed to generate plasma.

Further, in order to limit the generation of ECR plasma to a part of the space, a tube for guiding microwaves is installed at least in the substrate processing chamber space.

Furthermore, the magnetic lines of force that cross the ECR plasma generation surface and head toward the substrate are prevented from hitting the inner wall of the vacuum chamber or the wall of the waveguide tube at least on the upstream side of the substrate.

In addition, in order to further achieve the above purpose, the discharge tube was eliminated,
This structure has a microwave waveguide window inside the substrate processing chamber.

[Effect]

In the microwave plasma device, the ECR plasma is
It is limited to a space where the magnetic field strength satisfies the ECR conditions and where the introduced microwave is guided. Further, the generated ECR plasma flows in the direction of magnetic field lines. Therefore, a region that extends toward the substrate in a part of the inner wall of the vacuum container, or a region different from the wall surface to maintain vacuum, is created to guide microwaves to a part of the container space. By creating an ECR condition and making sure that the magnetic lines of force that cross the region and head toward the substrate do not hit the inner wall of the vacuum chamber, at least on the upstream side of the substrate, the ECR plasma flow will flow from the generation position to the substrate without touching the substrate. reach. Therefore, sputtering of charged particles or deposition of deposits on the inner wall of the container, etc. is prevented, and contamination of substrate processing and contamination of foreign matter can be significantly reduced.

Further, since plasma is generated not only at the ECR position but also by ordinary microwave discharge, the closer the ECR surface and the microwave introduction window are located, the more the above-mentioned contamination and foreign matter generation can be reduced. Therefore, by eliminating the discharge tube section and installing a microwave introduction window in the substrate processing chamber, contamination and foreign matter generation can be further reduced.

〔Example〕

Hereinafter, the present invention will be explained in detail using the drawings.

Embodiment 1 FIG. 1 is a cross-sectional view of the main part of one type of microwave plasma processing apparatus based on the present invention.

This device consists of a microwave waveguide 1 (the oscillator for the microwave 2 is not shown), a microwave introduction window 3. A discharge chamber 4, a processing chamber 6 for processing the substrate 5. Magnetic field generating coils 7 and 8. Exhaust port 9 (
(exhaust system is omitted), reaction gas nozzles 10 and 11 (reaction gas supply system is omitted), and a waveguide 12 that guides microwaves into the processing chamber 6. The microwave introduction window 3 is made of transparent quartz, and the discharge chamber 4. The processing chamber 6 and waveguide 12 are made by AQ.

By means of the magnetic field coils 7 and 8, the ECR position can be located within the waveguide 12 as shown in 14b in the figure, that is, it can be restricted to a part of the space within the processing chamber 6, and the ECR surface can be 13 in the figure shows the lines of magnetic force that cross the
As shown in FIG. 3B, the waveguide can be directed toward the substrate without touching the inner wall of the waveguide 12 or the inner wall of the processing chamber 6. As a result, E
As shown at 15b in the figure, the CR plasma flow can flow onto the substrate without touching at least the object surface in the processing chamber space on the upstream side of the substrate.

Using this apparatus, a silicon oxide film and a SiO2 film were deposited on a silicon wafer of 150 mmlφ as a substrate to be processed, and the degree of foreign matter contamination in the deposited film and the deposited surface was examined. In order to confirm the effectiveness of the apparatus of the present invention, we first investigated the situation when depositing with a conventional apparatus.

FIG. 2 shows a cross section of the main parts of a conventional device. The difference from the device of the present invention shown in FIG. 1 is that there is no magnetic field coil 8, and the EC
The R position is located inside the discharge tube as shown at 14a in the figure, and the magnetic field lines cross the wall of the discharge tube section as shown at 13a, and the ECR plasma 15a is This point touches the inner wall of the discharge tube section.

For the SiO2 film, oxygen, O2, was introduced at a rate of 100 [mQ/ml1nl] through the first gas supply nozzle, and monosilane, 5iHa, was introduced at 20[mQ/ml1nl] through the second gas supply nozzle.
nl was introduced, the pressure inside the processing chamber 6 was set to 0.2 [Pa] by adjusting the exhaust flow rate, and μ waves were introduced for deposition. The number of foreign particles contained in the deposited film was evaluated by XPS analysis, and the number of foreign particles on the surface of the deposited film was evaluated using a face plate defect analyzer. Deposited film thickness: 200 Cn m/m1nl
The number of AQ atoms contained in the film when the μ-wave power is varied is shown in A in FIG. 2, with the value at 1000 [W] μ-wave power being 100. Further, when a 5iOz film with a thickness of 200 [nm] is deposited on one film at a μ-wave power of 500 [W], the dependence of the number of surface foreign particles on the number of processed films is shown as A in FIG. Next, increase the current value flowing through the field coil 7, and calculate the number of AQ atoms and the number of surface foreign objects when the ECR position is set to 12 in Figure 2.
It is shown as A' in FIG. At this time, the magnetic field lines are the second
As shown at Ba' in the figure, the ECR plasma flow crosses the μ-wave waveguide 12 toward the side of the processing chamber, and as a result, the ECR plasma flow spreads above the substrate as shown at 15a'. Next, an experiment was conducted using the apparatus of the present invention shown in Fig. 7-1, with the conditions other than the direction of the lines of magnetic force being the same. The results are shown as B in FIGS. 3 and 4. It is clear from the results shown in Figures 3 and 4 that the amount of AQ mixed into the film, that is, the amount of the constituent material of the inner wall of the device, and the number of foreign particles on the surface are affected by the ECR plasma flow coming from the discharge tube. It can be seen that the smaller the area that the plasma flow touches from the waveguide surface in the processing chamber, the less the influence of foreign particles. moreover,
By controlling the magnetic lines of force to prevent the ECR plasma from touching the inside of the waveguide in the processing chamber or at least the walls of the processing chamber on the upstream side of the substrate, the influence of foreign particles can be reduced compared to when using the conventional device described above. It can be seen that the degree of contamination is about 5 to 7 times lower, and the number of foreign substances on the surface is about 10 to 15 times lower.

By making the ECR plasma position a part of the space within the substrate processing and furthermore aiming to flow the ECR plasma to the substrate without touching other objects, it is possible to avoid sputtering or deposits on the inner wall of the vacuum chamber due to the plasma. It can be seen that since it is possible to significantly reduce the amount of adhesion of substances, it is possible to reduce substrate contamination and foreign substances during plasma processing. Also,
The deposition rate under conditions A and A' above is approximately 100 [
n m/min, the velocity distribution within the wafer is ±12[
%], but under condition B, the divergence of the ECR plasma flow toward the substrate was suppressed, so the deposition rate was approximately 150%.
[n m /min], and the speed distribution was ±4 [%]. This indicates that controlling the direction of the magnetic field lines makes the plasma flow more efficient and uniform.

Example 2.

A p-type silicon substrate (150[IIf1
1] After forming a 20 [nm] thick thermal oxide film on φ), deposit polycrystalline silicon to a thickness of 300 [nm], and then using a substrate patterned with resist, using chlorine and CQ2 gas. Etched.

In the experiment, chlorine was supplied from the first gas supply pipe at a rate of 20 mQ/mi.
n waves were introduced, the μ wave power was 500 [W waves, the pressure was o. i[Pa
]. The experiment was conducted using conditions A' and B shown in Example 1 regarding the apparatus. The evaluation was performed by etching the polycrystalline silicon, removing the resist, using the polycrystalline silicon remaining after the etching as an electrode, and measuring the dielectric breakdown electric field strength between it and the lower silicon substrate. The area showing 8 [MV/cm] or more under condition A' was 57 [%] of the total MO8 area, but under condition B it was 94 [%]. From this, it can be seen that if the ECR plasma flow is introduced into the substrate without touching the object, plasma processing can be optimized, probably due to the difference in the amount of impurities taken in.

Embodiment 3 FIG. 5 is a diagram showing the main parts of one embodiment of a microwave plasma processing apparatus based on the present invention. The difference with the apparatus shown in FIG. 1 is that instead of installing a waveguide in the processing chamber, the processing A region 12c with a diameter of the chamber 6c or less is formed, and the ECR1 is placed in this region.
4c was positioned. Using this device, the conditions other than the above were the same as those shown in Example B, and
A film was deposited, and the number of Afl atoms mixed into the deposited film and the number of surface foreign substances were investigated. In the figure, 13c and 14c indicate magnetic lines of force and ECR positions. As a result, the number of mixed AQ atoms showed the same value as B shown above, but the number of surface foreign substances was about 10% higher. This is due to the rate at which uncharged radicals generated on the ECR plasma generation surface adhere to the processing chamber wall, but the device shown in this figure has a higher rate of adhesion to the processing chamber wall than the device shown in Fig. 1. This is thought to be due to the fact that there were fewer disturbances in the treatment chamber, and as a result, the amount of radicals deposited on the inner walls of the processing chamber increased. However, as in one embodiment of the present invention, there is a method of introducing the plasma flow to the substrate without touching other objects, even if the ECR plasma generation base wave tube is not particularly installed and is limited to a part of the processing chamber. However, it has been found that the influence of foreign objects can be avoided to a greater extent than when using conventional equipment.

Embodiment 4 FIG. 6 is a cross-sectional view of a main part of an embodiment of a plasma processing apparatus according to the present invention. The feature of this apparatus is that the discharge part is eliminated and the microwave introduction window is made into at least a part of the processing chamber. Using this apparatus 1-2, a 15 [nm] thick gate insulating film was formed on a 150 [mmφ] substrate, and in the subsequent process an n-gate MOS was formed.
For comparison, we manufactured transistors and investigated the yield.
Equipment conditions for A, A', and B shown in Example 1, Example 3
FIG. 7 shows the yield of MO8 production with respect to the number of processed substrates, assuming the apparatus conditions shown in FIG. D shows the results using this device. The conditions for comparison were the same except that the gate film was formed using different device conditions. As is clear from these results, under the condition (A) in which the ECR plasma was brought into contact with an object other than the substrate from the discharge section, the yield was O from the point exceeding 30 sheets, and under the condition (A) in which the ECR plasma was contacted from the processing chamber to an object other than the substrate, it was around 50 sheets. However, in the situation (B, C, D) where the ECR plasma flow flows to the substrate without touching the object, the yield is 50% even when 50 sheets are processed. In addition, the lower the rate of contact of radicals generated at the ECR position with the processing chamber wall (comparison of B and C), and the lower the rate of contact of plasma due to microwave discharge (comparison of C and D), the lower the yield. I know it's going to be expensive.

Embodiment 5 - Figure 9 shows an improvement to the apparatus shown in Embodiment 4 so that it can process large-area substrates and to reduce the amount of foreign matter caused by plasma sputtering in the waveguide installed in the processing chamber. 2 shows a cross-sectional view of the main parts of the device. In order to prevent the strength of the magnetic field applied to the center of the device from decreasing due to the enlarged diameter of the processing chamber, the magnetic field coil is coated with a highly magnetic metal plate 16 to prevent foreign matter, especially metal, from entering the substrate. In order to avoid this, the inner wall of the conductive tube 12 is covered with silicone material
coated with. Using this apparatus, the substrate to be processed is 350 [
After that, SiN, non-doped amorphous silicon, and then phosphorus and P-doped amorphous silicon are formed using this equipment, and then various processes are performed to manufacture a liquid crystal display. The number of defects was investigated. In order to compare the degree of foreign matter contamination, a similar experiment was conducted using the apparatus shown in FIG. 8 from which the coating film 17 was removed. Letting the former be E and the latter D',
FIG. 9 shows the dependence of the number of defects on the number of substrates processed. The results show that the number of defects generated using the device coated with silicon material is significantly lower than that of the device not coated.

This shows that the processing characteristics can be significantly improved by applying a non-metallic coating to the surface that comes in contact with plasma generated by microwave discharge.

As described above, according to this embodiment, in the microwave plasma processing apparatus, the ECR plasma generation part is limited to one space in the vacuum container, and the direction of the magnetic field lines is controlled, so that the ECR plasma is generated at least on the upstream side of the substrate. It can be seen that if the plasma is allowed to flow to the substrate without touching objects other than the substrate, contamination of the substrate from the materials constituting the inner wall of the vacuum container and deposits caused by the plasma can be reduced, and the yield in semiconductor device manufacturing can be improved. It has also been found that the above effects are further promoted by reducing the plasma generation area due to the flow of radicals and microwave discharge, and by improving the material of the wall of the vacuum vessel that comes into contact with the plasma.

〔Effect of the invention〕

As a result, the yield rate and reliability in semiconductor device manufacturing can be improved. Also,
Since the yield and reliability are significantly increased, it is possible to produce, for example, a high-resolution liquid crystal display.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one form of a microwave plasma processing apparatus according to the present invention, FIG. 2 is a diagram showing a conventional type apparatus, FIG.
FIG. 4 is a diagram showing the dependence of the relative value of the number of AQ atoms mixed into the deposited film on the μ-wave power, and the dependence of the number of foreign substances on the substrates on the number of processed substrates; FIGS. 5 and 6; FIG. FIG. 8 is a diagram showing one form of the device of the present invention, FIG. FIG. 9 is a diagram showing the dependence of the manufacturing yield of semiconductor devices on the number of processed semiconductor devices. 2...μ wave, 4...discharge section, 5...substrate, 6.processing chamber, 7.8...magnetic field coil, 12...μ wave waveguide,
13a-d-magnetic field lines, 14 a-e-E CR conditions, 15a-b...ECR plasma region, 16...metal material, 17 silicon film, A, A'...no magnetic field line control, B
...15 ECR plasma is generated in the waveguide of the processing chamber, CECR plasma is generated in a part of the processing chamber, D...No discharge part, D'...No waveguide inner wall coating, E waveguide The inner wall of the pipe is covered.

Claims (8)

[Claims] 1. In a plasma processing apparatus consisting of a vacuum vessel having a microwave introduction window, an exhaust system, and a reaction gas introduction system, and a magnetic field necessary to cause electron cyclotron resonance (ECR), the charged particles generated on the ECR surface are transferred to the substrate to be processed. A microwave plasma processing apparatus characterized by processing a substrate by flowing it to the substrate without touching the side wall of the vacuum chamber on the upstream side and an object surface located in the space on the upstream side. 2. Claim 1, characterized in that the diameter of the plasma generating section at the ECR position in the direction perpendicular to the central axis of the apparatus is longer than the diameter of the microwave introduction window and shorter than the diameter of the vacuum vessel at the substrate position. The microwave plasma processing apparatus according to item 1. 3. In an apparatus in which the vacuum vessel is separated into a discharge tube section and a substrate processing chamber, a waveguide for guiding introduced microwaves is installed in a part of the space of the substrate processing chamber, and the ECR 3. The microwave plasma processing apparatus according to claim 1 or 2, wherein: 4. Claims 1 to 3 are characterized in that the lines of magnetic force that cross the surface where plasma is generated by the ECR and go toward the substrate do not collide with the inner wall of the vacuum container or the inner wall of the conductive tube on the upstream side of the substrate. The microwave plasma processing apparatus described above. 5. Claims 1 to 4 are characterized in that the substrate processing chamber has overlapping discharge tube sections, and the microwave introduction window forms at least a part of the wall surface above the substrate of the substrate processing chamber. Microwave plasma processing equipment. 6. 6. The microwave plasma processing apparatus according to claim 1, wherein at least the inner wall of the conductive tube is coated with a material having a different component from that of the conductive tube. 7. A microwave plasma processing device characterized in that at least a part of a magnetic field coil is covered with a ferromagnetic material. 8. A method for manufacturing a semiconductor device, comprising manufacturing a semiconductor device using the apparatus according to any one of claims 1 to 7.