WO2010073578A1

WO2010073578A1 - Plasma generating apparatus and plasma processing apparatus

Info

Publication number: WO2010073578A1
Application number: PCT/JP2009/007046
Authority: WO
Inventors: 細野卓; 湊壮史; 嘉瀬慶久
Original assignee: 芝浦メカトロニクス株式会社
Priority date: 2008-12-24
Filing date: 2009-12-21
Publication date: 2010-07-01
Also published as: TW201119518A; JPWO2010073578A1

Abstract

A highly reliable plasma generating apparatus and a highly reliable plasma processing apparatus, by which generation of abnormal electric discharge can be suppressed using an extremely simple configuration without making the processing time long and configuration complicated, and by which plasma can be securely generated in an appropriate space. A microwave blocking plate (14) is arranged below a wafer (6). The microwave blocking plate (14) is composed of an upper plate (14a) and a side plate (14b) attached perpendicular to the upper plate (14a). On the upper plate (14a) of the microwave blocking plate (14), a plurality of hole sections (15) having a diameter smaller than 1/4 of the wavelength of microwaves are formed on the entire circumference.

Description

Plasma generator and plasma processing apparatus

The present invention relates to a plasma generator and a plasma processing apparatus that generate plasma in a processing tank using microwaves, and in particular, at the start of discharge in microwave discharge, discharge is surely performed in a space where plasma is to be generated. The present invention relates to a plasma generation apparatus and a plasma processing apparatus in which the above occurs.

In recent years, material processing technology using plasma has been remarkably advanced, and various plasma treatments such as ashing, dry etching, thin film deposition, and surface modification are performed in manufacturing processes of semiconductors and liquid crystal displays. Therefore, high performance is always required for plasma generators.

Among them, a plasma generator using microwave discharge is highly demanded because it has little damage to the wafer, and is used in conventional techniques such as Patent Document 1 and Patent Document 2. The technique described in Patent Document 1 irradiates a process gas containing at least oxygen atoms and hydrogen atoms with microwaves from a slot antenna, generates plasma directly on a wafer that is a substrate to be processed, and then the substrate to be processed. This is a method of removing the resist on the surface.

In the downflow etching apparatus described in Patent Document 2, the microwave is shielded by the shielding action of the shower head, so that only radicals out of the plasma generated in the plasma generating part are caused to flow into the etching part, and isotropic is caused by the radicals. Etching is performed. In the technique of Patent Document 2, oxygen plasma is generated in an oxygen plasma generator, and the reaction product in the etching chamber is irradiated with the oxygen plasma to remove the reaction product.

A plasma generator applied to such a technique will be specifically described with reference to FIG. FIG. 5 is a schematic view of a plasma generator employed in a general ashing apparatus. As shown in FIG. 5, an ashing chamber 5 that is a processing tank is provided, and a waveguide 2 is attached to the upper portion thereof. A magnetron 1 that oscillates microwaves is disposed at the end of the waveguide 2.

Further, a slot antenna 3 is formed on the lower surface of the waveguide 2, and a quartz microwave transmission window 4 is provided below the slot antenna 3. Further, gas inlets 8 for introducing the process gas 11 into the ashing chamber 5 are provided at the left and right ends of the microwave transmission window 4.

A sample stage 7 is provided inside the ashing chamber 5, and a wafer 6 having a photoresist on the surface is placed on the sample stage 7. A circular heater table 10 is attached to the lower surface of the sample table 7. In addition, a sample stand may be called including a heater table. Further, an exhaust port 9 is formed near the bottom of the ashing chamber 5.

In the plasma generator having the above configuration, when the magnetron 1 oscillates the microwave, the waveguide 2 guides the microwave and radiates the microwave from the slot antenna 3 toward the microwave transmission window 4.

At this time, since the inside of the ashing chamber 5 is exhausted from the exhaust port 9 and the process gas 11 is introduced through the gas introduction port 8, the microwave radiated from the slot antenna 3 excites the process gas 11. As a result, plasma 12 (indicated by a dotted line) is generated. Moreover, since the wafer 6 is heated and held using the heater table 10, the photoresist on the surface of the wafer 6 can be efficiently removed.

JP 2002-158210 A JP-A-7-130713

However, the conventional plasma generator as described above has the following problems. That is, in a plasma generation apparatus using microwaves, when discharge is started at a low pressure, it is difficult for the microwaves to remain above the substrate to be discharged, and in the space above the substrate to be processed. There is a phenomenon that discharge is difficult to start.

“Start of discharge” means that electrons accelerated by an electric field are ionized and propagated by collision with neutral particles, gas is turned into plasma, and discharge is continued. When a microwave electric field is used, since there is usually no electrode, the wall of the treatment tank or the like becomes a secondary electron emission source and discharge starts.

Taking the plasma generator shown in FIG. 5 as an example, the area of the wall surface portion where the lower space of the sample stage 7 on which the wafer 6 is placed and the wall surface portion of the ashing chamber 5 can be a secondary electron emission source is large. The amount of secondary electron emission increases. Therefore, the probability that discharge is started in these spaces is increased.

That is, the start of discharge spreads not in the upper space of the wafer 6 where discharge is to occur but in another space, and the abnormal discharge 13 is generated in the space where the plasma 12 should be unnecessary. When such an abnormal discharge 13 occurs, the power consumption for generating the plasma 12 necessary for the plasma processing of the wafer 6 increases unnecessarily.

In particular, the abnormal discharge 13 generated in the space from the lower surface of the heater table 10 to its leg portion does not contribute to the generation of the plasma 12 above the wafer 6 and simply damages the lower surface of the heater table 10 or its leg portion. It was an urgent need to suppress it.

As a method for solving the above problem, it is conceivable to increase the pressure of the process gas. However, a process for returning the process gas to a low pressure again after the discharge is stabilized is necessary. Therefore, the process gas pressure adjustment work has increased, and the processing time has been extended accordingly.

Also known is a technique of providing a trigger discharge section such as a glow lamp as a secondary auxiliary device in order to prevent the occurrence of abnormal discharge 13. However, a member to be used only at the start of discharge must be provided. For this reason, the number of maintenance target members also increases, and simplification of the configuration has been desired.

As described above, in a plasma generator using microwaves or a plasma processing apparatus using the generator, it is difficult to generate a discharge in a desired space at the start of discharge at a low pressure. Therefore, it is conceivable to increase the pressure of the process gas or to provide a trigger discharge part. However, these techniques have caused new problems such as a longer processing time and a complicated configuration.

The present invention has been proposed to solve the above-described problems, and its purpose is to suppress the occurrence of abnormal discharge with a very simple configuration while avoiding a prolonged processing time and a complicated configuration. An object of the present invention is to provide a highly reliable plasma generating apparatus and plasma processing apparatus capable of reliably generating plasma in an appropriate space.

In order to achieve the above object, a plasma generator of the present invention is a plasma generator for generating plasma by introducing a process gas and a microwave into a processing tank that accommodates a substrate to be processed. A microwave blocking material is disposed below the substrate to be processed. In order to achieve the above object, the plasma processing apparatus of the present invention is characterized by using the above-described plasma generator.

According to the plasma generator and the plasma processing apparatus of the present invention, it is possible to prevent the occurrence of abnormal discharge in the lower space of the substrate to be processed by a very simple configuration in which the microwave blocking material is provided below the substrate to be processed. Even when the discharge is started in the microwave discharge under the low pressure environment, the discharge is likely to occur above the substrate to be processed, and the reliability is greatly improved.

The schematic diagram of typical embodiment which concerns on this invention. The principal part top view of this embodiment. The schematic diagram of typical embodiment which concerns on this invention. The schematic diagram of other embodiment which concerns on this invention. The schematic diagram of a general ashing device.

Hereinafter, typical embodiments of the plasma generating apparatus according to the present invention will be described in detail with reference to FIGS. 1 and 3 are schematic views of the present embodiment, and FIG. 2 is a plan view of the main part of the present embodiment. The present embodiment is applied to the ashing device as in the conventional example shown in FIG. 5, and the same members as those in the conventional example shown in FIG. .

(1) Representative embodiment [configuration]
As shown in FIGS. 1 and 3, the present embodiment is characterized in that a microwave blocking plate 14 is disposed below the wafer 6 placed on the sample stage 7. The microwave blocking plate 14 includes an upper surface plate 14a and a side surface plate 14b attached perpendicularly to the upper surface plate 14a.

Here, the microwave blocking plate 14 constitutes the microwave blocking material of the present invention. The shape of the upper surface plate 14 a of the microwave blocking plate 14 is a ring shape, and the inner diameter thereof is substantially equal to or slightly larger than the outer diameter of the heater table 10, and the outer diameter is that of the side wall portion of the ashing chamber 5. The inner diameter (dimension in the left-right direction in FIG. 1) is substantially equal to or slightly smaller.

That is, the upper surface plate 14 a of the microwave blocking plate 14 can move up and down in the space between the periphery of the sample table 7 and the side wall of the ashing chamber 5, and microwaves pass between the sample table 7 and the side wall of the ashing chamber 5. The dimension is such that there is no gap (for example, smaller than 1/4 of the microwave wavelength).

A plurality of holes 15 having a diameter smaller than ¼ of the microwave wavelength are formed on the upper surface plate 14a of the microwave blocking plate 14 over the entire circumference (see FIG. 2). The total area of the holes 15 is set to a size sufficient to smoothly exhaust the process gas 11 in the ashing chamber 5.

In addition, since the microwave has a property of transmitting through an insulator, the material of the microwave blocking plate 14 is preferably a metal material that reflects the microwave. The side plates 14b of the microwave blocking plate 14 are vertically moved with respect to a plurality of (for example, four) support arms 16 extending in the horizontal direction from the sample table 7 (from the heater table 10 integrated with the sample table 7 in this embodiment). It is provided freely. The microwave blocking plate 14 is normally in the raised position (state shown in FIG. 1), and is moved to the lowered position when performing maintenance or the like below the sample stage 7 (state shown in FIG. 3).

Here, when the microwave blocking plate 14 is raised, the upper surface level thereof, that is, the upper surface level of the upper surface plate 14a in this embodiment is set to a height that substantially coincides with the upper surface level of the sample stage 7. That is, at the rising end of the microwave shielding plate 14, the upper surface plate 14 a is disposed below the wafer 6 placed on the sample stage 7. Note that the microwave blocking plate 14 is moved in the vertical direction with respect to the support arm 16 by a drive mechanism such as a motor or an air cylinder (not shown).

[Function and effect]
The effect of this embodiment having the above configuration is as follows. That is, since the microwave blocking plate 14 is installed so as to fill the space between the periphery of the sample stage 7 and the side wall of the ashing chamber 5 and disposed below the wafer 6, the magnetron 1, the waveguide 2, the slot antenna 3, Microwaves supplied from the microwave supply means constituted by the microwave transmission window 4 do not reach the lower space of the wafer 6. More specifically, the diameter of the hole 15 provided in the upper surface plate 14a of the microwave blocking plate 14 is smaller than ¼ of the microwave wavelength, and the microwave does not pass therethrough.

Further, the total area of the holes 15 of the upper surface plate 14a is large enough to exhaust the process gas 11 in the ashing chamber 5 from the exhaust port 9, and is formed over the entire circumference of the upper surface plate 14a. . Therefore, even if the microwave blocking plate 14 is installed in the ashing chamber 5, the flow of the process gas 11 is not blocked by this, and the process gas 11 can be exhausted uniformly.

As described above, according to the present embodiment, the microwave blocking plate 14 is arranged, so that the microwave can be prevented from reaching the lower space of the wafer 6 and the occurrence of the abnormal discharge 13 can be reliably suppressed. it can. For this reason, discharge starts easily in the space above the wafer 6.

Therefore, plasma generation can be realized in an appropriate space without increasing power consumption, which can contribute to improvement of reliability. At this time, there is no need to increase the pressure of the process gas 11, and the pressure adjustment work of the process gas 11 can be omitted, so that a problem such as a prolonged processing time does not occur.

Furthermore, since there is no need for a trigger discharge section such as a glow lamp, there is an advantage that the configuration can be simplified. In addition, since the microwave blocking plate 14 is movable up and down, maintenance and the like below the sample stage 7 can be easily performed by moving it to the lowered position.

Further, since the microwave blocking plate 14 is disposed below the wafer 6, plasma discharge can be caused relatively near the wafer 6. Thereby, the effect that the discharge heat contributes to the increase in the temperature of the wafer 6 required for the process can be expected.

(2) Other Embodiments In the above-described embodiments, the microwave blocking plates 14 are arranged above and below the sample stage 7 via the support arm 16. However, you may arrange | position so that the microwave interruption | blocking board 14 can be directly moved up and down to the bottom part of the ashing chamber 5. FIG. In this case, the support arm 16 becomes unnecessary.

¡In order to achieve the prevention of abnormal discharge, the microwave block 14 does not need to move up and down. In this case, the upper surface level of the upper surface plate 14 a of the microwave blocking plate 14 may be fixed to the bottom or side wall of the ashing chamber 5 at a height that substantially matches the upper surface level of the sample stage 7. When the microwave blocking plate 14 is fixedly disposed on the side wall portion of the ashing chamber 5, the side plate 14b is not required.

Also in the hole portion 15 formed in the upper surface plate 14a of the microwave blocking plate 14, the number of rows of holes is not limited to one but may be a plurality of rows as long as microwaves are blocked. In addition, this invention is not limited to said embodiment, The shape of each member, a dimension, a material, etc. can be changed suitably.

Specifically, the microwave blocking plate 14 may be detachably provided to the heater table 10. In this case, for example, the side plate 14b is shaped like a rod, and the end of the support arm 16 has a female screw, the end of the side plate 14b has a male screw corresponding to the female screw of the support arm 16, and the other side of the side plate 14b. A female screw is processed at the end, and a hole is opened in a portion that contacts the side plate 14b at the periphery of the top plate 14a. And when attaching the microwave interruption | blocking board 14 to the heater table 10, the support board 16 and the side board 14b are joined by screwing the side board 14b in the support arm 16, and the top board 14a is covered and screwed. When removing, reverse the operation.

As shown in FIG. 4, the installation location of the side plate 14b of the microwave blocking plate 14 is not the side wall portion side of the ashing chamber 5 as shown in FIG. 1, but the sample stage 7 side (heater table 10 side). good. By doing so, the support arm 16 can be shortened, and miniaturization of parts can be achieved.

In this case, as in the above-described embodiment, the side plate 14b of the microwave blocking plate 14 can be moved up and down via a drive mechanism such as a motor or an air cylinder with respect to the support arm 16 extending horizontally from the sample stage 7. Even if it is arranged directly so that it can move up and down at the bottom of the ashing chamber 5 without providing the support arm 16 in particular, the upper surface level of the upper surface plate 14a is set to a height that substantially matches the upper surface level of the sample stage 7. The ashing chamber 5 may be fixedly disposed on the bottom or side wall.

In any of the above-described embodiments, the preferred height of the upper surface level of the microwave blocking plate 14 at the rising end of the microwave blocking plate 14 or the fixed arrangement is set to a height that substantially matches the upper surface level of the sample stage 7. . However, the upper surface level of the microwave blocking plate 14 may be lower than the upper surface level of the sample stage 7. However, it is necessary to set a position higher than the limit at which abnormal discharge occurs in the space below the sample stage 7 as described in the problem. The limit position varies depending on the internal pressure of the ashing chamber 5, the intensity of the microwave, the type of etching gas, and the like.

In any of the above-described embodiments, the shape of the side plate 14b that constitutes the microwave blocking plate 14 that constitutes the microwave blocking material may be a bar shape instead of a plate. If comprised in this way, size reduction of components can be achieved. Further, in the above-described embodiment, the ashing process has been described as an example. However, the present invention can be applied to any processing apparatus using a plasma generator such as an etching apparatus, a thin film deposition apparatus, a surface processing apparatus, or a plasma doping apparatus. Moreover, although the wafer was illustrated as a to-be-processed substrate, it is applicable not only to this but the board | substrate processed by plasma.

DESCRIPTION OF SYMBOLS 1 ... Magnetron 2 ... Waveguide 3 ... Slot antenna 4 ... Microwave transmission window 5 ... Ashing chamber 6 ... Wafer 7 ... Sample stand 8 ... Gas introduction port 9 ... Exhaust port 10 ... Heater table 11 ... Process gas 12 ... Plasma 13 ... Abnormal discharge 14 ... Microwave blocking plate 14a ... Top plate 14b ... Side plate 15 ... Hole 16 ... Support arm

Claims

In a plasma generator for generating plasma by introducing a process gas and a microwave into a processing tank for storing a substrate to be processed,
A plasma generating apparatus, wherein a microwave blocking material is disposed in the processing tank below the substrate to be processed.
A sample stage on which the substrate to be processed is placed in the processing tank is installed,
The plasma generator according to claim 1, wherein the microwave blocking material is attached to the sample stage.
3. The plasma generating apparatus according to claim 2, wherein the microwave blocking material is provided so as to be movable in the vertical direction with respect to the sample stage.
The microwave blocking material has a ring-shaped top plate, and the inner diameter thereof is substantially equal to or slightly larger than the outer diameter of the sample table, and the outer diameter is substantially equal to the inner diameter of the side wall of the processing tank, or The plasma generator according to claim 2 or 3, wherein the plasma generator is formed slightly smaller.
4. The plasma generating apparatus according to claim 2, wherein the microwave blocking material is detachably provided on the sample stage.
The plasma generator according to any one of claims 1 to 3, wherein a hole having a diameter smaller than ¼ of a microwave wavelength is formed in the microwave blocking material.
The plasma generating apparatus according to claim 1, wherein the microwave blocking material is attached to a bottom portion or a side wall portion of the processing tank.
A plasma processing apparatus using the plasma generation apparatus according to any one of claims 1 to 3 as a plasma generation apparatus.