JPH06275566A - Microwave plasma treating device - Google Patents

Abstract

PURPOSE:To obtain a microwave plasma treating device which can perform high-quality treatment by increasing the treating ability of the device, such as the ashing speed, etc., by positioning a partition plate having a plurality of holes at specific distances from the lower surface of a microwave introducing window and from the upper surface of a sample stage. CONSTITUTION:A plasma generating chamber 11 and reaction chamber 12 are formed in the cooling water passage 18 of a reactor 10. The top of the chamber 11 is airtightly sealed with a microwave introducing window 19 and a sample stage 15 for placing samples S is provided in the chamber 12. The chambers 11 and 12 are separated from each other by a partition plate 14 having a plurality of holes 14a and the plate 14 is positioned at a distance of 20-45mm from the lower surface of the window 19 and at another distance of 20-45mm from the upper surface of the stage 15. Therefore, the number of ions transmitted through the plate 14 is reduced, because the frequency of collisions between ions is increased in the chamber 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma processing apparatus, and more particularly, it utilizes plasma generated by introducing microwaves to perform etching processing, ashing processing, etc. on a semiconductor element substrate, for example. The present invention relates to a microwave plasma processing device used as an applying device.

[0002]

2. Description of the Related Art In the manufacturing process of LSI, various processes are often performed by using plasma generated when energy is externally applied to a reaction gas. In particular, dry etching technology using plasma is
It has become an indispensable technology in the SI manufacturing process.

In general, the excitation means for generating plasma uses microwaves and RF (Radio Frequency).
ncy) is sometimes used. When using microwave,
Compared with the case where RF is used, there are advantages that plasma can be obtained at a lower temperature and a higher density, contamination by electrodes is less, and the device configuration and its operation are simple. However, in the conventional plasma device using microwaves, the area of the plasma generation region is small, and it is difficult to generate plasma uniformly in this plasma generation region. Therefore, it is necessary to uniformly process a large-diameter semiconductor substrate. Was difficult.

A device using a dielectric line is known as a device having a large plasma generation area and capable of uniformly generating microwave plasma (Japanese Patent Laid-Open No. 62-5600). And JP-A-63-994.
No. 81). FIG. 6 is a sectional view schematically showing a conventional microwave plasma processing apparatus using a dielectric line,
In the figure, 10 indicates a reactor. The reactor 10 is formed by using a metal such as stainless steel, and the peripheral wall 1 of the reactor 10 is formed.
0a has a double structure in which a cooling water passage 18 is formed, and inside the cooling water passage 18, a plasma generation chamber 11 and a reaction chamber 12 each having a horizontal cross section of about 290 × 290 mm are formed. Has been formed. The upper part of the plasma generation chamber 11 is hermetically sealed by a microwave introduction window 19, which is transparent to microwaves, has a small dielectric loss, and is heat-resistant quartz glass, It is formed by using a dielectric plate such as alumina. A sample table 15 for mounting the sample S is arranged in the reaction chamber 12, and an exhaust port 16 connected to an exhaust device (not shown) is formed in the lower wall of the reaction chamber 12 to generate plasma. A gas supply pipe 17 for supplying a desired reaction gas into the reactor 10 is connected to one side wall of the chamber 11. The plasma generation chamber 11 and the reaction chamber 12 are partitioned by a partition plate 13 having a plurality of holes 13a. The partition plate 13 has a distance D from the lower surface of the microwave introduction window 19 of about 7 mm and the sample stage 15 It is arranged at a location where the distance d between the and is approximately 60 mm.

On the other hand, the dielectric line 2 is provided above the reactor 10.
0 is provided, a frame body 21 formed by using a metal plate such as aluminum is provided on the upper and side portions of the dielectric line 20, and a fluorine having a small dielectric loss is provided on the lower surface of the frame body 21. A dielectric layer 22 made of resin, polyethylene, polystyrene or the like is attached. A microwave oscillator 24 is connected to the dielectric line 20 via a waveguide 23, and the microwave from the microwave oscillator 24 is introduced into the dielectric line 20 via the waveguide 23. ing.

When the microwave plasma processing apparatus configured as described above is used to perform the ashing process on the surface of the sample S placed on the sample table 15, first, the plasma generation chamber 11 is evacuated from the exhaust port 16. After setting the reaction chamber 12 to a required degree of vacuum, the reaction gas is supplied from the gas supply pipe 17. Also, circulate the cooling water in the cooling water passage 18,
The plasma generation chamber 11 and the reaction chamber 12 are maintained at a predetermined temperature. Next, a microwave is oscillated by the microwave oscillator 24, and this microwave is introduced into the dielectric line 20 via the waveguide 23. Then, an electric field is formed below the dielectric line 20, and the formed electric field is applied to the microwave introduction window 1
It is supplied to the plasma generation chamber 11 through 9 and plasma is generated. Neutral particles such as radicals in the generated plasma mainly pass through the holes 13a and are guided to the periphery of the sample S in the reaction chamber 12 to ash the resist on the sample S.

[0007]

With the recent advances in LSI manufacturing technology, there has been a demand for a microwave plasma processing apparatus which has a high processing performance such as ashing speed (hereinafter simply referred to as processing performance) and is capable of high-quality processing. Has been.

FIG. 7 shows a conventional device described above, in which the distance D between the lower surface of the microwave introduction window 19 and the partition plate 13 is 7 mm.
FIG. 6 is a curve diagram showing the ashing rate when the distance d between the partition plate 13 and the upper surface of the sample table 15 is fixed to 60 mm and is gradually shortened from 60 mm. As is clear from this figure, in the above-mentioned conventional microwave plasma processing apparatus, when the sample table 15 is arranged close to the partition plate 13, the processing performance can be increased as the sample table 15 is closer to the partition plate 13. Become. However, when the sample table 15 is disposed close to the partition plate 13, there is a problem in that the sample S is damaged by ions, and thus it is difficult to improve the processing performance while maintaining high quality.

The present invention has been made in view of such problems, and an object thereof is to provide a microwave plasma processing apparatus capable of further improving the processing performance while maintaining high quality.

[0010]

In order to achieve the above object, a microwave plasma processing apparatus according to the present invention comprises a microwave oscillator, a waveguide for transmitting microwaves, and a waveguide connected to the microwave oscillator. A microwave plasma processing apparatus comprising: a dielectric line; a reactor having a microwave introduction window arranged opposite to the dielectric line; and a sample stage provided in the reactor, wherein the microwave introduction window is provided. The distance from the lower surface of the sample table is 20 to 45 mm and the distance from the upper surface of the sample table is 25 mm.
It is characterized in that a partition plate having a plurality of holes is arranged at a position of about 45 mm.

[0011]

The present inventors have found that the distance between the partition plate and the lower surface of the microwave introduction window (hereinafter referred to as the height of the plasma generation chamber) D and the distance between the partition plate and the upper surface of the sample table (hereinafter, the sample table height). Sat) d was variously changed, and the relationship between the processing performance and the damage was investigated. The survey results are shown in Table 1.

[0012]

[Table 1]

As is clear from this result, the processing performance and damage are influenced by the height D of the plasma generating chamber and the height d of the sample table, and the processing performance is further improved by the change of each distance described above. , Or that the sample S may be damaged. For example, when the height D of the plasma generation chamber is 17 mm, the height d of the sample table is
Is 20 to 50 mm, the treatment performance is superior or better than that of the conventional one, but damage is caused, and when the sample table height d is 60 mm, the damage is eliminated, but the treatment performance is different from the conventional one. It remains about the same.
Further, for example, when the height D of the plasma generating chamber is 47 mm, the processing performance is superior to the conventional one when the height d of the sample table is 20 mm, but damage occurs, and the sample table When the height d is 30 to 60 mm, damage is eliminated, but the processing performance is improved to a slightly better level or substantially the same level as the conventional one. Then, as indicated by a double-lined frame in the table, the plasma generation chamber height D is 20 to 45 mm, and the sample stage height d is 25.
With the device set to ~ 45 mm, damage can be prevented and the processing performance is significantly improved.

Regarding this cause, when the height D of the plasma generating chamber is set to 20 to 45 mm, the frequency of collision of ions in the plasma increases, and the number of ions passing through the holes of the partition plate decreases. Therefore, unless the distance d between the sample table and the partition plate is within 25 mm, the damage to the sample S by the ions is considered to be eliminated. On the other hand, since neutral particles such as radicals pass through the holes of the partition plate without decreasing, the sample S can be efficiently etched unless the distance d between the sample table and the partition plate exceeds 45 mm. It is considered that the ashing process is performed.

According to the microwave plasma processing apparatus of the present invention, the distance from the lower surface of the microwave introduction window is 20 to 4.
5 mm and at a distance of 25 to 45 mm from the sample stand,
Since the partition plate having a plurality of holes is arranged, the collision frequency of ions in the plasma generation chamber is increased, and the number of ions passing through the holes of the partition plate is reduced,
Since the sample S is not damaged, and the sample S is held in the region where the neutral particles such as radicals are present at a high density, the sample S can be processed quickly and the processing performance can be improved. .

[0016]

EXAMPLES AND COMPARATIVE EXAMPLES Examples of a microwave plasma processing apparatus according to the present invention will be described below with reference to the drawings. It should be noted that components having the same functions as those of the conventional example are designated by the same reference numerals.

FIG. 1 is a sectional view schematically showing an embodiment of a microwave plasma processing apparatus according to the present invention. The structure of the apparatus shown in FIG. 1 is the same as that shown in FIG. Since it is the same as the conventional microplasma processing apparatus shown in FIG. 1, detailed description thereof will be omitted here, and only the configuration different from the conventional one will be described. Reference numeral 10 in the drawing denotes a reactor, and a horizontal cross-sectional shape is approximately 290 × 290 mm inside the cooling water passage 18 in the reactor 10.
A plasma generation chamber 11 and a reaction chamber 12 are formed. The upper portion of the plasma generation chamber 11 is hermetically sealed by the microwave introduction window 19, and the sample S is placed in the reaction chamber 12.
A sample table 15 for mounting the is mounted. The plasma generation chamber 11 and the reaction chamber 12 are partitioned by a partition plate 14 having a plurality of holes 14a. The partition plate 14 has a distance of 20 to 45 mm from the lower surface of the microwave introduction window 19 and the upper surface of the sample table 15. It is arranged at a distance of 25 to 45 mm.

A case in which the sample S is subjected to an ashing process using the microwave plasma processing apparatus configured as described above will be described. Table 2 shows the plasma generation chamber height D and sample stage height d in the apparatus of the example, and Table 3 shows the processing conditions.

[0019]

[Table 2]

[0020]

[Table 3]

As a comparative example, an apparatus having the plasma generation chamber height D and the sample stage height d shown in Table 4 was used.

[0022]

[Table 4]

FIG. 2 is a curve diagram showing the results of measuring the ashing rate in the case of using the apparatus of the example and the comparative example. The black circles in the figure show the case of the apparatus of the example. The marks other than indicate the case of the device of the comparative example. As is clear from this figure, the plasma generation chamber height D and the sample stage height d in the conventional apparatus were 7 mm and 60 mm, respectively.
In the case of the device according to the example, the ashing rate could be increased by about 1.6 times as compared with the case of mm.

Next, using the devices of Examples and Comparative Examples, MN
A sample S having an OS (Metal Nitride Oxide Semiconductor) structure was processed and produced, and damage was evaluated by flat band shift. As shown in FIG. 3, the sample S having the MNOS structure has a thickness of about 3 nm of SiO ₂ on the surface of the p-type Si substrate 31.
The film 32 is formed, and the thickness is about 40 nm on the SiO ₂ film 32.
The Si ₃ N ₄ film 33 was formed, and the poly Si film 34 having a thickness of about 400 nm was formed on the Si ₃ N ₄ film 33. The damage evaluation due to the flat band shift is one of the damage evaluation methods in the processing step at the time of manufacturing the device, and is a method of evaluating whether or not a constant voltage is applied due to valence electrons during the processing. That is, when a voltage is applied, the characteristics of the device change and cause a malfunction, so it is evaluated that damage has occurred.

FIG. 4 shows the height D of the plasma generating chamber as an example.
Is 27 mm and the sample stage height d is 40 mm, and as a comparative example, the plasma generation chamber height D is 7 mm and the sample stage height d is
When the sample S having the MNOS structure is processed using a device having a height of 40 mm and a height D of the plasma generation chamber of 17 mm and a height d of the sample stand of 40 mm, the flat band voltage on the diameter Y axis of the sample S. It is a curve figure showing the result of having measured the distribution of _deltaVfb . As is clear from this figure, damage occurs in the device of the comparative example, but in the device of the example, the flat band voltage ΔV _fb is zero at all parts on the diameter Y axis, and the damage is It did not occur.

Table 1 above shows a summary of the results of the ashing process performance and the presence / absence of damage using the apparatus according to the example and the apparatus according to the comparative example.

As is clear from these results, in the microwave plasma processing apparatus according to the embodiment, the distance from the lower surface of the microwave introduction window 19 is 20 to 45 mm, and the sample stage 1
5 Place multiple holes 1 at a distance of 25 to 45 mm from the top surface.
Since the partition plate 14 having 4a is arranged, the collision frequency of ions in the plasma generation chamber 11 increases,
Since the number of ions that pass through the holes 14a of the partition plate 14 is reduced, damage to the sample S can be eliminated, and the sample S is retained in a region where neutral particles such as radicals are present at a high density. The sample S can be subjected to the ashing process quickly, and the ashing process performance can be improved.

In the above-described embodiment, the case where the sample S is subjected to the ashing treatment has been described, but the same effect can be obtained when the etching treatment is performed.

FIG. 5 is a sectional view schematically showing a microwave plasma processing apparatus according to another embodiment, which is the same as the apparatus shown in FIG. 1 except for the dielectric line and the waveguide. Therefore, detailed description thereof will be omitted here, and FIG.
The configuration will be described only for the points different from those shown in FIG. In the figure, reference numeral 10 denotes a reactor, and a frame body 41 formed of a metal plate such as aluminum is disposed above the reactor 10, and a top surface of the frame body 41 is vertically guided. The pipe 43 is connected. Further, the microwave oscillator 24 is connected to the waveguide 43, and the microwave from the microwave oscillator 24 is introduced into the plasma generation chamber 11 via the waveguide 43. Also reactor 1
The inside of the cooling water passage 18 at 0 has a plasma generation chamber 11 and a reaction chamber 12 each having a horizontal cross-sectional shape of approximately 290 × 290 mm.
Are formed, and the plasma generation chamber 11 and the reaction chamber 12 are formed.
And are separated by a partition plate 14 having a plurality of holes 14a.

Also in the microwave plasma processing apparatus configured as described above, the distance from the lower surface of the microwave introduction window 19 is 20 to 45 mm and the distance from the sample stage 15 is 25.
It is desirable to dispose the partition plate 14 at a position of about 45 mm, and it is possible to obtain substantially the same effect as in the case of the device of the above embodiment.

[0031]

As described in detail above, in the microwave plasma processing apparatus according to the present invention, the distance from the lower surface of the microwave introduction window is 20 to 45 mm and the distance from the upper surface of the sample table is 25 mm. Since a partition plate having a plurality of holes is arranged at a position of ~ 45 mm, the frequency of collision of ions in the plasma generation chamber increases, and the number of ions passing through the holes of the partition plate decreases. The damage to the sample S can be eliminated, and the sample S is held in a region where neutral particles such as radicals are present at a high density.
The processing can be performed quickly and the processing performance can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an embodiment of a microwave plasma processing apparatus according to the present invention.

FIG. 2 is a curve diagram showing the results of measuring the ashing rate in the case of using the apparatus of the example and the comparative example, in which the black circles indicate the case of the apparatus of the example, The mark indicates the case of the device of the comparative example.

FIG. 3 is a cross-sectional view schematically showing a sample S having a MNOS structure used for damage evaluation by flat band shift.

FIG. 4 is a curve diagram showing the results of measuring the distribution of the flat band voltage ΔV _fb on the diameter Y axis of the sample S when the sample S having the MNOS structure was treated using the devices of the example and the comparative example. Is.

FIG. 5 is a sectional view schematically showing a microwave plasma processing apparatus according to another embodiment.

FIG. 6 is a sectional view schematically showing a conventional microwave plasma processing apparatus using a dielectric line.

FIG. 7 shows the ashing rate when the distance D between the lower surface of the microwave introduction window and the partition plate is fixed to 7 mm and the distance d between the partition plate and the upper surface of the sample table is gradually shortened from 60 mm in the conventional apparatus. FIG.

[Explanation of symbols]

 10 Reactor 14 Partition Plate 14a Hole 15 Sample Stage 19 Microwave Introduction Window 20 Dielectric Line 23 Waveguide 24 Microwave Oscillator

Claims (1)

[Claims] 1. A reactor having a microwave oscillator, a waveguide for transmitting microwaves, a dielectric line connected to the waveguide, and a microwave introduction window arranged to face the dielectric line. And a sample stage provided in the reactor, the distance from the lower surface of the microwave introduction window is 20 to 45 mm, and the distance from the upper surface of the sample stage is 25. A microwave plasma processing apparatus characterized in that a partition plate having a plurality of holes is arranged at a position of about 45 mm.