JP2932942B2 - Plasma processing equipment - Google Patents

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, and more particularly, to a plasma processing apparatus suitable for performing processes such as etching, ashing, and CVD using a plasma on a semiconductor element substrate, a glass substrate for a liquid crystal display, etc. It relates to a processing device.

[0002]

2. Description of the Related Art Plasma generated when energy such as electromagnetic waves is externally applied to a reaction gas is widely used in an LSI manufacturing process and the like. Particularly, dry etching technology using plasma has become an indispensable basic technology in the semiconductor industry.

[0003] Generally, a high frequency of 13.56 MHz is used as an excitation means for generating plasma. However, the use of microwaves can provide a low-temperature and high-density plasma, and the structure and operation of the apparatus can be reduced. There are advantages such as simplicity. However, in a conventional plasma processing apparatus using microwaves, it is difficult to generate uniform plasma over a large area, and thus it is difficult to uniformly process a large-diameter semiconductor substrate.

On the other hand, as a plasma processing apparatus capable of uniformly generating microwave plasma over a large area, the present applicant has disclosed Japanese Patent Application Laid-Open Nos. 62-5600 and 62-99481. A method using a dielectric line proposed in US Pat. This plasma processing apparatus has a configuration in which an opening on the upper surface of a reaction vessel is sealed with a microwave introduction plate through which microwaves can pass, and a dielectric line into which microwaves are introduced is formed above the microwave introduction plate.

FIG. 4 is a cross-sectional view schematically showing an example of this type of plasma processing apparatus. In the figure, reference numeral 11 denotes a hollow rectangular parallelepiped metal reaction vessel. This reaction vessel 11
Is formed using a metal such as stainless steel, the peripheral wall has a double structure, and the inside thereof is a cooling water flow chamber 18. During operation of the apparatus, cooling water flows through the cooling water flow chamber 18 to cool the periphery of the reaction vessel 11.

The upper part of the reaction vessel 11 is a plasma generation chamber 20, and the upper part of the plasma generation chamber 20 is made of a dielectric plate made of quartz glass, pyrex glass, alumina ceramics or the like having microwave permeability and heat resistance. The microwave introduction plate 34 formed by using the microwave introduction plate 34 is provided, and the inside of the reaction vessel 11 is connected to the microwave introduction plate 34 via an O-ring (not shown) arranged on the upper wall 18 a of the cooling water flow chamber 18. And hermetically sealed. A reaction chamber 21 is formed below the plasma generation chamber 20 via a partition plate 17 having a mesh structure. The reaction chamber 21 is provided in the reaction chamber 21 for mounting the sample S at a position facing the microwave introduction plate 34. A sample table 23 is provided. An exhaust port 14 connected to an exhaust device (not shown) is formed on a lower wall of the reaction chamber 21, and a gas for supplying a required reaction gas into the reaction vessel 11 is provided on one side wall of the plasma generation chamber 20. The supply pipe 19 is connected.

On the other hand, a dielectric line 32 is provided above the reaction vessel 11, and a metal plate 32a made of aluminum (Al) or the like is provided above the dielectric line 32. A dielectric layer 32b is fixed to the lower surface of the metal plate 32a with bolts or the like. The dielectric layer 32b is formed using fluororesin, polyethylene, or polystyrene having a small dielectric loss. A microwave oscillator 16 is connected to a dielectric line 32 composed of a metal plate 32 a and a dielectric layer 32 b via a waveguide 15, and microwaves from the microwave oscillator 16 are insulated through the waveguide 15. It is to be introduced into the body track 32.

In the case where the surface of the sample S such as a semiconductor substrate mounted on the sample table 23 is subjected to an ashing process, an etching process, or the like using the plasma processing apparatus having the above-described configuration, the exhaust gas is first exhausted from the exhaust port 14. Go to reaction vessel 11
After setting the inside to a required degree of vacuum, a reaction gas such as O ₂ , Ar, or CF _{4 is} supplied from the gas supply pipe 19 into the plasma generation chamber 20. Further, during operation of the apparatus, cooling water flows into the cooling water flow chamber 18 to cool the periphery of the reaction vessel 11. Then
The microwave oscillator 16 is operated to oscillate microwaves, and the microwaves are transmitted through the waveguide 15 to the dielectric line 3.
Introduce to 2. As a result, an electric field is formed below the dielectric line 32, and the formed electric field passes through the microwave introduction plate 34 and is introduced into the plasma generation chamber 20. On the other hand, the gas supplied from the gas supply pipe 19 is
And is turned into plasma by microwave irradiation. Among the plasma, electrically neutral radicals mainly pass through the mesh-shaped partition plate 17 and spread into the reaction chamber 21, reach the surface of the sample S placed on the sample stage 23, and perform ashing and the like. An etching process or the like is performed.

[0009]

Incidentally, in such a plasma processing apparatus, a larger area (for example, 50
In the case of generating plasma at 0 mm × 500 mm), simply increasing the area of the dielectric line 32 simply reduces the power density of the microwave in inverse proportion to the area of the dielectric line 32. Therefore, for example, when doubling the plasma generation area, it is necessary to double the power of the microwave in order to obtain the same processing speed in processing such as etching. With the apparatus having such a configuration, the same microwave power density can be obtained, and the etching processing speed becomes the same. However, in order to double the capacity of the microwave power supply, it is necessary to modify the microwave oscillator itself, which causes a problem that the device becomes very expensive and the device itself becomes large. Was.

As described above, in order to generate a large-area plasma, the size of the dielectric line 32 must be increased.
Needs to be increased, and the volume of the reaction vessel 11 also needs to be increased. In particular, when used for manufacturing a liquid crystal display, the area of the processing substrate is 400 mm.
In many cases, the area is larger than × 400 mm, and the dielectric line 32, the microwave introduction plate 34, and the like also need a larger area. In this case, there were problems in the following points.

First, when the area of the dielectric line 32 is increased, the dielectric layer 32b becomes heavier, so that the adhesion between the metal plate 32a on the dielectric line 32 and the dielectric layer 32b is not easy, and the microwave power is increased. Is applied, the dielectric layer 32
An uneven temperature distribution is likely to occur in b. For this reason, there has been a problem that the dielectric line 32 is easily deformed and the plasma processing speed is likely to be unstable.

In order to produce a large-sized microwave introducing plate 34 having sufficient mechanical strength to maintain the inside of the reaction vessel 11 in a vacuum, the thickness of the microwave introducing plate 34 is considerably increased. The microwave introduction plate 34 itself becomes considerably heavy and expensive in this case. Further, when the microwave introduction plate 34 becomes thicker, the temperature of the surface in contact with the gas plasma inside the reaction vessel 11 is greatly increased because it is heated by this gas plasma, but the temperature does not rise much on the surface in contact with the atmosphere. . This is because the thermal conductivity of the microwave introduction plate 34 is usually small, but due to such a large temperature difference between both surfaces of the microwave introduction plate 34, a large strain is generated in the microwave introduction plate 34, and However, there is a problem in that such a problem easily occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and enables a large-area substrate, such as a glass substrate for a liquid crystal display, to be uniformly plasma-processed, and enables long-term continuous operation. It is an object to provide a relatively inexpensive plasma processing apparatus.

[0014]

In order to achieve the above object, a plasma processing apparatus according to the present invention is provided with a microwave introduction path and connected to the microwave introduction path and arranged to form a microwave waveguide. A plasma processing apparatus comprising: a dielectric layer; a microwave introduction plate facing the dielectric layer with a hollow layer interposed; and a metal reaction vessel in which an upper opening is hermetically sealed with the microwave introduction plate. Wherein the dielectric layer, the hollow layer, and the microwave introduction plate are divided by a metal plate, and a plurality of microwave introduction paths are connected to each of the divided dielectric layers.

[0015]

According to the plasma processing apparatus of the present invention, the dielectric layer, the hollow layer, and the microwave introduction plate are divided by the metal plate, and a plurality of microwave introduction paths are connected to the divided dielectric layers. I have. For this reason, the area of each divided dielectric layer can be small, so that it is easy to adhere to the upper metal plate, and the temperature distribution of the dielectric layer during operation hardly occurs. Also, as for the microwave introduction plate, since the area of each divided microwave introduction plate is reduced, the mechanical strength that can withstand the vacuum inside the reaction vessel can be small, and therefore, the microwave introduction plate The thickness can be reduced. As a result, the difference between the temperature on the side of the plasma generation chamber of the microwave introduction plate and the temperature on the side of the hollow layer is reduced, and the thermal strain applied to the microwave introduction plate is also reduced. Disappears.

When plasma is generated, microwaves generated from individual microwave oscillators are introduced into microwave waveguides including a dielectric layer via microwave introduction paths. In the plasma processing apparatus according to the present invention, the dielectric layer,
The hollow layer and the microwave introduction plate are divided into a plurality by a metal plate, and the microwaves are cut off by the metal plate, so that the microwaves introduced from the individual microwave oscillators are not mixed, An electric field is formed in each of the microwave waveguides, and passes through each of the microwave introduction plates to turn the gas in the metal reaction vessel into plasma.
In this case, no plasma is generated in a very close portion immediately below the metal plate that divides the microwave introduction plate, etc., but the plasma diffuses in the horizontal direction as the distance from the microwave introduction plate increases, and to some extent the microwave introduction plate In a distant region, a plasma having a sufficiently uniform ion current density distribution is generated. Further, if the plasma processing apparatus having the conventional configuration is simply enlarged, individual components such as a microwave oscillator and a microwave introduction plate become very expensive. The price itself of the wave introduction plate and the like is reduced, and the total price of the apparatus is kept low.

As described above, according to the plasma processing apparatus having the above-described structure, a large-area plasma can be generated without increasing the area of each microwave introduction plate, microwave waveguide, and the like. The plasma processing is performed uniformly on a large-area substrate by the apparatus. In addition, even in the case of long-term continuous operation, a failure such as a breakage of the microwave introduction plate hardly occurs.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the plasma processing apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view schematically showing a plasma processing apparatus according to an embodiment, and FIG. 2 is a plan view thereof.

In the plasma processing apparatus according to the embodiment shown in FIGS. 1 and 2, the basic materials, functions, operations, etc., of the components constituting the apparatus are the same as those of the plasma processing apparatus described in the prior art. Therefore, a detailed description of each component is omitted here, and only a portion different from the conventional plasma processing apparatus will be described.

The plasma processing apparatus according to the embodiment has two microwave oscillators (not shown), each of which is a waveguide 15 serving as a microwave introduction path.
a and 15b are connected to the dielectric line 12, which is a microwave waveguide. The dielectric layers 12a and 12b constituting the dielectric line 12 are divided into two by a metal microwave introduction plate support 12c. Similarly, the hollow layers 24a and 24b and the microwave introduction plates 22a and 22b are also divided. Each is divided into two by the microwave introduction plate support 12c. Each of the divided microwave introduction plates 22 a and 22 b is connected to the upper wall 1 of the cooling water flow chamber 18.
8a and O placed on the microwave introduction plate support 12c.
It is hermetically sealed via a ring (not shown).

Next, the operation of the thus configured plasma processing apparatus will be described. A sample S such as a semiconductor substrate is placed on a sample table 23 in the reaction vessel 11, and the reaction vessel 11
After the inside of the reaction vessel 11 is set at a predetermined pressure by exhausting the gas in the chamber, CF ₄ , O ₂ , and the like are supplied from the gas supply pipes 19a and 19b.
A gas such as Ar is supplied. At this time, the waveguides 15a and 15b and the dielectric
2 (dielectric layers 12a, 12b), microwave introduction plate 22
Microwaves are introduced into the plasma generation chamber 20 via a and 22b. The microwave introduction plate support 12c which divides the dielectric layers 12a, 12b, etc. is made of metal and blocks microwaves, so that microwaves oscillated from individual microwave oscillators are not mixed with each other. Instead, they are separately introduced into the plasma generation chamber 20 to generate gas plasma. Plasma is hardly generated in a portion of the plasma generation chamber 20 very close to the microwave introduction plate support 12c, but the plasma diffuses in the horizontal direction as the distance from the microwave introduction plates 22a and 22b increases. If is disposed at an appropriate position, the plasma processing can be uniformly applied to the sample S.

Next, in order to evaluate the uniformity of the plasma generated by the plasma processing apparatus having the above configuration, the reaction vessel 1 was evaluated.
The ion current density distribution of the plasma in 1 was measured. In the plasma processing apparatus, the width of the microwave introduction plate support 12c supporting the microwave introduction plates 22a and 22b is 80 mm, and the dimensions of the quartz glass microwave introduction plates 22a and 22b are 250mm × 5
It was 00 mm x 20 mm. Therefore, the total area of the two microwave introduction plates 22a and 22b is 500 × 500 mm
Met. Also, the dielectric layers 12a and 12b are 300 m
A fluororesin having dimensions of mx 500 mm x 20 mm was used.

In the plasma processing apparatus having such a configuration, Ar is introduced as a plasma gas from the gas supply pipes 19a and 19b, the pressure in the reaction vessel 11 is set to 10 mTorr, and the microwave power is set to 3 kW. Raised.

FIG. 3 is a graph showing an ion current density distribution at a predetermined position in the reaction vessel 11. The in-plane position shown in FIG.
2b, a position in a plane 100 mm away from the microwave introduction plates 22a and 22b in the direction of the sample table 23 from the microwave introduction plates 22a and 22b, and the point P shown in FIG. A position separated by a predetermined distance in the direction and the y-axis direction (also shown in FIG. 2) is shown. As is clear from the results shown in FIG. 3, the microwave introduction plate support 12c
In the plane 100 mm away from the plasma, the plasma is sufficiently diffused, the influence of the microwave introduction plate support 12c is eliminated, the ion current density distribution becomes uniform, and the sample S can be uniformly subjected to etching or ashing. it can.

Next, the plasma generation conditions were set in the same manner as the above conditions, and the operation of the plasma processing apparatus was started for 5 minutes by discharging for 1 minute.
Although the minute stop was repeated 25 times as one cycle, cracks did not occur in the microwave introduction plates 22a and 22b, the temperature distribution was uniform, and the processing speed was stable.

As described above, in the plasma processing apparatus according to the embodiment, a uniform ion current density distribution can be obtained over a wide area of about 480 × 480 mm on the surface of the reaction vessel 11 where plasma processing can be performed. It has been confirmed that plasma treatment such as etching treatment can be performed sufficiently uniformly on a large-area substrate such as a glass substrate for a liquid crystal display.

In the above embodiment, the dielectric layer 1
2a, 12b and the like are divided into two, and the description has been given of the plasma processing apparatus provided with two microwave oscillators and the like. In another embodiment, the dielectric layer and the like are divided into three or more, It may have the same number of microwave oscillators or the like. In the above embodiment, the two microwave oscillators and the waveguides 15a and 15b are arranged in a straight line with the dielectric line 12 interposed therebetween. Wave oscillator and waveguide 15
a and 15b may be adjacently disposed on two parallel lines.

With the plasma processing apparatus having such a configuration, the total area capable of performing the plasma processing is increased, and a substrate or the like having a larger area can be uniformly etched.

[0030]

As described above in detail, in the plasma processing apparatus according to the present invention, a microwave introduction path and a dielectric connected to the microwave introduction path and arranged to form a microwave waveguide are provided. Layer, a microwave introduction plate opposed to the dielectric layer with a hollow layer interposed therebetween, and a plasma processing apparatus including a metal reaction vessel whose upper opening is hermetically sealed with the microwave introduction plate, Since the dielectric layer, the hollow layer and the microwave introduction plate are divided by a metal plate and a plurality of microwave introduction paths are connected to the divided dielectric layers, a relatively inexpensive device, A large area sample can be uniformly subjected to plasma processing. In addition, even when the plasma processing apparatus is operated continuously, it is possible to prevent occurrence of failures such as cracking of the microwave introduction plate and thermal deformation of the dielectric line.

[Brief description of the drawings]

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

FIG. 2 is a plan view schematically showing the plasma processing apparatus according to the embodiment.

FIG. 3 is a graph showing an ion current density distribution in a reaction vessel.

FIG. 4 is a cross-sectional view schematically illustrating an example of a conventional plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Reaction container 12 Dielectric line 12a, 12b Dielectric layer 12c Microwave introduction plate support 15a, 15b Waveguide 22a, 22b Microwave introduction plate 24a, 24b Hollow layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ identification code FI H01L 21/302 H (58) Field surveyed (Int.Cl. ⁶ , DB name) H05H 1/46 C23C 4/00 H01L 21 / 3065

Claims (1)

(57) [Claims] A microwave introduction path, a dielectric layer connected to the microwave introduction path and arranged to form a microwave waveguide, and a microwave introduction path opposed to the dielectric layer with a hollow layer interposed therebetween. In a plasma processing apparatus comprising a plate and a metal reaction vessel whose top opening is hermetically sealed with the microwave introduction plate, the dielectric layer, the hollow layer and the microwave introduction plate are formed of a metal plate. A plasma processing apparatus, wherein a plurality of divided microwave introduction paths are connected to respective divided dielectric layers.