JP3839628B2 - Plasma processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus, and more particularly to a plasma processing apparatus for processing an object to be processed using plasma generated by irradiating a process gas with microwaves.
[0002]
[Prior art]
As an apparatus for processing an object to be processed such as a silicon wafer for manufacturing a semiconductor or a glass substrate for a liquid crystal display, there is a plasma processing apparatus for performing a dry etching process or an ashing process on the object to be processed using microwave plasma.
[0003]
There are several types of plasma processing apparatuses. For example, a process gas is introduced into a discharge tube formed of a dielectric material, and a microwave guided through a microwave waveguide is converted into the discharge tube. Some irradiate an internal process gas to generate plasma inside the discharge tube.
[0004]
In this type of plasma processing apparatus, by generating plasma inside the discharge tube, active species are generated from the process gas, and the active species are led to a processing chamber formed inside the vacuum vessel to be processed. Then, the surface is subjected to surface treatment such as dry etching or ashing.
[0005]
As another example of the plasma processing apparatus, a microwave is guided to a vacuum container through a microwave waveguide, and a vacuum is transmitted through a microwave transmission window member made of a plate-like dielectric provided in the vacuum container. A microwave is introduced into the interior of the container, and this microwave is irradiated to the process gas introduced into the interior of the vacuum container to generate plasma inside the vacuum container. There is a type that performs processing.
[0006]
This type of plasma processing apparatus is further configured to bring the plasma generated inside the vacuum container into contact with the surface of the object to be processed, and to treat the surface of the object to be processed with active species in the plasma, and the inside of the vacuum container. Is separated into a plasma generation region and a processing chamber, and the surface treatment is performed by guiding the downflow from the plasma to the surface of the object to be processed.
[0007]
In addition, quartz, alumina, sapphire, etc. can be used as a dielectric material for forming the aforementioned discharge tube or microwave transmission window member.
[0008]
As the process gas, for example, when etching a thin film on the surface of the object to be processed, oxygen gas (O ₂ ) or a gas obtained by adding a fluorine-based gas such as CF ₄ or NF ₃ to the oxygen gas is used. The
[0009]
In the above-described conventional plasma processing apparatus, the dielectric used as the discharge tube or the microwave transmission window member is usually a ceramic, and generally the ceramic has a hardness of an element indicating the mechanical strength of the material. Is superior, but the toughness is inferior to other materials. Therefore, there are restrictions on the mechanical strength and machining accuracy of the dielectric, and parts such as an O-ring are used in the portion where the dielectric is used.
[0010]
Therefore, when the periphery of the dielectric constituting the discharge tube or the like is covered with a metal member made of a metal material for the purpose of cooling or fixing the discharge tube or the like, if the dielectric and the metal member are directly brought into contact, the dielectric It is necessary to process both surfaces of the portion where the body and the metal member are in contact with each other with high machining accuracy, and it is necessary to devise a structure for making the stress applied to the dielectric uniform. For this reason, if it is attempted to completely eliminate the possibility of damage to the dielectric, the processing cost increases and the design difficulty increases.
[0011]
For these reasons, when the periphery of the dielectric constituting the discharge tube or the like is covered with a metal member made of a metal material, the dielectric and the metal member must not be in direct contact with each other.
[0012]
Therefore, conventionally, a gap is provided between the dielectric and the metal member, and a material having flexibility and heat resistance is inserted into the gap to fill the gap for the purpose of fixing and cooling the dielectric. I was doing. As a material for filling the gap, a fluorine-based resin or a silicone-based resin can be used.
[0013]
In the above-described conventional plasma processing apparatus, as a method for cooling the dielectric, the metal member disposed opposite to the dielectric is cooled, and the dielectric is indirectly cooled by cooling the metal member. I try to cool it down.
[0014]
Here, as a medium for cooling the metal member, a gas such as air or nitrogen gas can be used, or a solid such as a heat conductive sheet having flexibility and a relatively high heat resistance temperature can be used.
[0015]
Further, in the conventional plasma processing apparatus described above, when a gap exists in the vicinity of the discharge tube or the microwave transmission window member, oxygen in the air reacts with electromagnetic waves such as ultraviolet rays from the plasma generated inside the discharge tube. Ozone is generated. Since ozone has a strong reactivity, there is a problem of influence on the human body, and there is a possibility of deteriorating parts used in the apparatus. Furthermore, since ozone reacts with a chlorine gas detector, a gas detector installed around the apparatus may malfunction due to the presence of ozone.
[0016]
Therefore, conventionally, in order to prevent the generation of ozone, a relatively stable gas such as nitrogen is caused to flow in the vicinity of the discharge tube or the microwave transmission window member, and the periphery of the discharge tube or the like is made an atmosphere of a stable gas.
[0017]
[Problems to be solved by the invention]
The dielectric constituting the discharge tube and the microwave transmission window member is exposed to plasma to be etched by reacting with the activated process gas, or the substance contained in the dielectric and the process gas. Reacts. For this reason, at the time of surface treatment such as etching or ashing, the plasma distribution changes with the etching of the discharge tube or the like, and the treatment speed fluctuates, or impurities adhere to the surface of the object to be treated. . Such dielectric etching and generation of impurities can be reduced to some extent by cooling the dielectric.
[0018]
However, when a gas is used as the cooling medium, the cooling method is indirect cooling, so the cooling efficiency is poor, sufficient cooling performance cannot be obtained, and a large amount of gas must be used to increase the cooling efficiency. I must.
[0019]
On the other hand, when a solid such as a heat conductive sheet is used as a cooling medium, if the cooling medium is composed of a rigid member made of a hard substance such as a metal, a sufficient contact area cannot be obtained, and the cooling effect can be biased. For this reason, when the cooling medium is composed of a solid, it is necessary to use a material having a certain degree of elasticity, and for example, it is necessary to use a heat conductive sheet made of a fluorine resin or a silicone resin.
[0020]
However, these resin materials have a heat-resistant temperature and a melting point of about 200 ° C. at the maximum, and on the other hand, the temperature of the surface of the dielectric constituting the discharge tube etc. is 300 ° C. to 400 ° C. or higher. There is. For this reason, there is a possibility that the heat conductive sheet made of a resin material may deteriorate due to heat, and it is difficult to completely eliminate the possibility of combustion of the heat conductive sheet. However, when the discharge tube or the like is cooled by the heat conductive sheet, the surface opposite to the surface that contacts the discharge tube or the like is cooled so that the temperature of the heat conductive sheet is not increased so much during the cooling. be able to.
[0021]
However, even in such a case, it is impossible to deny the possibility of deterioration of the heat conductive sheet or heat fusion with the surface of the discharge tube or the like, and the cooling capacity is lowered when the heat conductive sheet is deteriorated and the surface is cured. In addition, if the heat conductive sheet is fused to the discharge tube or the like, the heat conductive sheet cannot be reused. Further, if the heat conductive sheet is deformed or rotated in the middle like the discharge tube, the heat conductive sheet is deformed. The shape of the sheet and the axis of rotation are no longer symmetrical, and rotation and reversal movements are limited. Further, due to the fusion of the heat conductive sheet and the discharge tube or the like, when the used discharge tube or the like is discarded, it becomes difficult to separate and collect.
[0022]
In order to increase the cooling efficiency of the discharge tube or the like, it is preferable to use a liquid cooling medium. As such a liquid cooling medium, a fluorine-based liquid dielectric can be used. However, this liquid dielectric is very expensive, and toxic fluorine gas may be generated by thermal decomposition. In addition, in the case of direct cooling with liquid, it is necessary to completely remove the liquid remaining inside when replacing the dielectric that is the object to be cooled, or performing operations such as cleaning the interior by opening the vacuum vessel to the atmosphere. These operations cannot be performed. Further, in the case of direct cooling with a liquid, there is a possibility that the liquid flows into the vacuum container when the dielectric is damaged for some reason.
[0023]
In addition, when there is a space around the discharge tube or the microwave transmitting member, as described above, a relatively stable gas such as nitrogen is flowed to prevent the generation of ozone, so that the atmosphere is free of oxygen. However, considerable equipment is required to create such a stable gas atmosphere, and a sufficient amount of gas such as nitrogen must be prepared according to the frequency of use.
[0024]
In order to prevent the generation of ozone with certainty, the gap between the dielectric discharge tube and the surrounding metal member is filled with some filling material, or the gap is sealed with some sealing member. It is also conceivable to create an oxygen-free atmosphere around the discharge tube or the like. However, in this case as well, as in the case of the above-described heat conductive sheet, there is a problem that the filling material or the sealing member causes heat fusion with the dielectric constituting the discharge tube or the like, or deteriorates due to heat. To do.
[0025]
In addition, when a metal member is arranged around the dielectric, there is flexibility between the metal member and the dielectric in order to prevent the dielectric having poor toughness from being damaged by contact with the metal member. Although a method of inserting a filling material can be considered, in this case as well, as in the case of the above-described heat conductive sheet, there is a problem that the filling material causes thermal fusion with the dielectric or deteriorates due to heat. To do.
[0026]
The present invention has been made in consideration of the above-described circumstances, and the object of the present invention is to ensure sufficient cooling efficiency by bringing a sheet member into contact with a discharge tube or a microwave transmission window member, and An object of the present invention is to provide a plasma processing apparatus capable of preventing deterioration of a sheet member due to heat fusion between a tube or a microwave transmission window member and a sheet member, ultraviolet rays, or the like.
[0027]
[Means for Solving the Problems]
In order to solve the above problems, the present invention introduces a process gas into a discharge tube formed of a dielectric, and irradiates the process gas inside the discharge tube with a microwave through a microwave waveguide. In the plasma processing apparatus for generating plasma and supplying the active species in the plasma to the surface of the object to be processed, the discharge tube is connected at the connection between the microwave waveguide and the discharge tube. A metal member made of a metal material disposed around the flexible tube member, and a flexible sheet member provided around the discharge tube and the metal member, the sheet member facing the discharge tube A pair of heat-resistant layers made of a heat-resistant material arranged on the inner circumference side and the outer circumference side facing the metal member, and a heat conductive layer made of a heat-conductive material arranged between the pair of heat-resistant layers, It is characterized by including.
[0028]
In order to solve the above problems, the present invention introduces a microwave guided through a microwave waveguide made of a metal material into a vacuum vessel through a microwave transmission window member formed of a dielectric, In the plasma processing apparatus in which a plasma is generated by irradiating the process gas introduced into the vacuum container with the microwave, and the surface of an object to be processed is processed by the plasma, the microwave waveguide and the microwave A flexible sheet member disposed between the wave transmission window member and the sheet member disposed on a side facing the microwave transmission window member and a side facing the microwave waveguide; It includes a pair of heat resistant layers made of a heat resistant material and a heat conductive layer made of a heat conductive material disposed between the pair of heat resistant layers.
[0029]
Preferably, the heat conductive layer is made of a silicone sheet formed of a silicone material.
[0030]
Preferably, at least one of the pair of heat-resistant layers is made of a metal sheet formed of a metal material.
[0031]
Preferably, the metal sheet is an aluminum foil formed of aluminum.
[0032]
Preferably, at least one of the pair of heat resistant layers is made of a sheet made of a polyimide material.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
First Embodiment Hereinafter, a plasma processing apparatus according to a first embodiment of the present invention will be described with reference to the drawings.
[0034]
As shown in FIG. 1, the plasma processing apparatus according to the present embodiment includes a vacuum vessel 1 that can be evacuated, and a processing chamber 2 is formed inside the vacuum vessel 1. Is provided with a mounting table 4 on which the workpiece 3 is mounted. Here, the workpiece 3 is a silicon wafer for semiconductor manufacturing, a glass substrate for liquid crystal display, or the like.
[0035]
A discharge tube 6 made of a dielectric material is connected to the vacuum vessel 1 through a gas introduction tube 5, and the discharge tube 6 includes a gas introduction port 7 for introducing a process gas (reactive gas), and discharges. A discharge chamber 9 is formed inside the tube 6. A microwave waveguide 10 for supplying microwaves to the inside of the discharge tube 6 is connected to the discharge tube 6. Here, quartz, alumina, sapphire, or the like can be used as the dielectric forming the discharge tube 6.
[0036]
As shown in FIG. 2, microwaves (MW) are emitted from the inside of the microwave waveguide 10 toward the discharge tube 6 on the surface of the microwave waveguide 10 facing the discharge tube 6. The slit 11 is formed. Further, a metal member 14 made of a metal material is disposed at a connection portion between the microwave waveguide 10 and the discharge tube 6 so as to surround the discharge tube 6.
[0037]
Further, as shown in FIG. 3, a flexible sheet member 12 is interposed between the discharge tube 6 and the metal member 14 and is in close contact with the surface of the discharge tube 6. 12, the gap between the discharge tube 6 and the metal member 14 is filled.
[0038]
The sheet member 12 includes a pair of heat resistant layers 12a and 12c made of a heat resistant material disposed on the inner peripheral side facing the discharge tube 6 and the outer peripheral side facing the metal member 14, and a pair of heat resistant layers 12a and 12c. And a heat conductive layer 12b made of a heat conductive material.
[0039]
The heat conductive layer 12b is configured by a silicone sheet formed of a silicone material having high heat conductivity and high flexibility. Here, the silicone sheet is made of a simple silicone material that does not contain additives such as boron nitride, and is inexpensive and has sufficient cooling capacity. The pair of heat-resistant layers 12a and 12c are made of a metal sheet (metal foil) formed of a metal material, and preferably made of an aluminum foil made of aluminum.
[0040]
In addition, an aluminum tape in which an adhesive layer is applied to an aluminum foil can be used, and by using the aluminum tape, the aluminum foil and the silicone sheet are bonded and integrated, so that the attachment and removal work of the sheet member 12 can be performed. It becomes easy.
[0041]
In addition, at least one of the pair of heat-resistant layers 12a and 12c can be configured by a sheet formed of a polyimide material instead of the metal sheet. Here, an advantage of using a polyimide sheet is that polyimide is a dielectric and has a small dielectric loss, and therefore does not have an electrical adverse effect on discharge.
[0042]
Further, a pair of heat-resistant layers 12a and 12c made of a metal sheet or a polyimide sheet can be formed in a bag shape, and a heat conductive layer 12b made of a silicone sheet can be accommodated therein.
[0043]
Further, the metal member 14 is provided with a cooling mechanism 13 by water cooling to improve the cooling efficiency of the discharge tube 6 and prevent ozone generation.
[0044]
In the present embodiment having the above-described configuration, the process gas supplied from the gas inlet 7 into the discharge tube 6 is irradiated with microwaves, and the process gas is turned into plasma inside the discharge tube 6, so that the process gas enters the process gas. Active species are generated. This active species is supplied to the surface of the workpiece 3 in the processing chamber 2 via the gas introduction pipe 5 and subjected to surface treatment such as etching treatment or ashing treatment.
[0045]
According to this embodiment, since the flexible sheet member 12 is filled between the metal member 14 and the discharge tube 6, the metal member 14 and the discharge tube 6 are fixed to each other without being brought into direct contact with each other. In addition, the generation of ozone can be prevented by blocking electromagnetic waves such as ultraviolet rays and microwaves from the plasma in the discharge tube 6. By fixing the discharge tube 6 via the metal member 14, it is possible to use the discharge tube 6 in an upright state, and the degree of freedom in apparatus configuration is increased and the installation space can be reduced.
[0046]
In addition, the sheet member 12 is formed in a multilayer structure by the heat conductive layer 12b having sufficient heat conductivity and the heat-resistant layers 12a and 12c, and is brought into close contact with the surface of the discharge tube 6 by utilizing its flexibility. Therefore, it is possible to ensure sufficient heat transfer between the metal member 14 and the discharge tube 6 and increase the cooling efficiency of the discharge tube 6.
[0047]
Further, since the heat conductive layer 12b made of a silicone sheet is sandwiched between a pair of heat resistant layers 12a and 12c made of a metal sheet or polyimide from both sides, the heat conductive layer 12b and the heat conductive layer 12b facing the discharge tube 6 The heat fusion with the discharge tube 6 can be prevented, and the pair of heat-resistant layers 12a and 12c can surely prevent the heat conductive layer 12b from being deteriorated due to ultraviolet rays or ozone from the plasma.
[0048]
Second Embodiment Next, a plasma processing apparatus according to a second embodiment of the present invention will be described with reference to the drawings.
[0049]
FIG. 4 is a schematic diagram showing a schematic configuration of the plasma processing apparatus according to the present embodiment. This apparatus includes a vacuum vessel 20 that can be evacuated, and a processing chamber 21 is formed inside the vacuum vessel 20. Has been. In the processing chamber 21, for example, a mounting table 22 is provided for mounting a workpiece 23 having a surface coated with a resist.
[0050]
An outlet end 24 a of the microwave waveguide 24 is connected to the upper portion of the vacuum vessel 20, and the outlet end 24 a is used to radiate microwaves from the inside of the microwave waveguide 24 toward the processing chamber 21. The slit 27 is formed in an elongated shape along the tube axis direction of the microwave waveguide 24. A microwave transmission window member 25 made of a plate-like dielectric is provided between the outlet end 24 a of the microwave waveguide 24 and the processing chamber 21. Here, as a dielectric for forming the microwave transmission window member 25, quartz, alumina, sapphire, or the like can be used.
[0051]
A microwave transmitter (not shown) for generating a microwave (MW) is connected to an inlet end (not shown) of the microwave waveguide 24.
[0052]
A flexible sheet member 26 is interposed between the outlet end 24a of the microwave waveguide 24 and the microwave transmission window member 25, and is in close contact with the surface of the microwave transmission window member 25. The sheet member 26 fills the gap between the microwave transmission window member 25 and the outlet end 24 a of the microwave waveguide 24.
[0053]
The sheet member 26 includes a pair of heat-resistant layers 26a and 26c made of a heat-resistant material disposed on the side facing the microwave transmitting window member 25 and the side facing the outlet end 24a of the microwave waveguide 24, and a pair of heat-resistant layers. And a heat conductive layer 26b made of a heat conductive material disposed between the layers 26a and 26c.
[0054]
The heat conductive layer 26b is configured by a silicone sheet formed of a silicone material having high heat conductivity and high flexibility. Here, the silicone sheet is made of a simple silicone material that does not contain additives such as boron nitride, and is inexpensive and has sufficient cooling capacity. The pair of heat-resistant layers 26a and 26c are made of a metal sheet (metal foil) made of a metal material, and preferably made of an aluminum foil made of aluminum.
[0055]
Also, an aluminum tape in which an adhesive layer is applied to an aluminum foil can be used. By using the aluminum tape, the aluminum foil and the silicone sheet are bonded and integrated, so that the attachment and removal work of the sheet member 26 can be performed. It becomes easy.
[0056]
In addition, at least one of the pair of heat-resistant layers 26a and 26c can be configured by a sheet formed of a polyimide material instead of the metal sheet. Here, an advantage of using a polyimide sheet is that polyimide is a dielectric and has a small dielectric loss, and therefore does not have an electrical adverse effect on discharge.
[0057]
Further, a pair of heat-resistant layers 26a and 26c made of a metal sheet or a polyimide sheet can be formed in a bag shape, and a heat conductive layer 26b made of a silicone sheet can be accommodated therein.
[0058]
In the present embodiment configured as described above, the microwave radiated into the processing chamber 21 through the microwave transmission window member 25 is irradiated to the process gas supplied into the processing chamber 21, and the process gas is turned into plasma. Is done. The plasma-processed process gas reacts with the surface of the workpiece 3 and is subjected to surface treatment such as etching treatment or ashing treatment.
[0059]
And according to this embodiment, since the flexible sheet | seat member 26 was filled between the exit end 24a of the microwave waveguide 24, and the microwave transmission window member 25, the exit end 24a of the microwave waveguide 24 is filled. And the microwave transmitting window member 25 can be fixed to each other without being in direct contact with each other, and generation of ozone can be prevented by blocking electromagnetic waves such as ultraviolet rays and microwaves from the plasma.
[0060]
Further, the sheet member 26 is configured in a multilayer structure by the heat conductive layer 26b having sufficient heat conductivity and the heat resistant layers 26a and 26c, and the surface of the microwave transmitting window member 25 is utilized by utilizing its flexibility. Therefore, it is possible to secure sufficient heat transfer between the outlet end 24a of the microwave waveguide 24 and the microwave transmission window member 25 and to improve the cooling efficiency of the microwave transmission window member 25. .
[0061]
Further, since the heat conductive layer 26b made of a silicone sheet is sandwiched between a pair of heat resistant layers 26a and 26c made of a metal sheet or polyimide from both sides, heat conduction is performed by the heat resistant layer 26a facing the microwave transmitting window member 25. The heat-sealing between the layer 26b and the microwave transmission window member 25 can be prevented, and the pair of heat-resistant layers 26a and 26c can surely prevent the heat conductive layer 26b from being deteriorated due to ultraviolet rays or ozone from the plasma. .
[0062]
【The invention's effect】
As described above, according to the present invention, the flexible sheet member including the pair of heat-resistant layers and the heat conductive layer sandwiched between them is provided between the discharge tube and the metal member. The cooling efficiency of the sheet can be increased, the thermal fusion between the sheet member and the discharge tube can be prevented, and the deterioration of the heat conduction layer due to ultraviolet rays, ozone, etc. from the plasma can be reliably prevented.
[0063]
Further, according to the present invention, since the flexible sheet member including the pair of heat-resistant layers and the heat conductive layer sandwiched between them is provided between the microwave waveguide and the microwave transmission window member, The cooling efficiency of the microwave transmission window member can be increased, the thermal fusion between the sheet member and the microwave transmission window member can be prevented, and the deterioration of the heat conduction layer due to ultraviolet rays, ozone, etc. from the plasma can be reliably prevented. can do.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a plasma processing apparatus according to a first embodiment of the present invention.
2 is a perspective view showing a connection portion between a microwave waveguide and a discharge tube in the plasma processing apparatus shown in FIG.
3 is a longitudinal sectional view showing a connection portion between a microwave waveguide and a discharge tube in the plasma processing apparatus shown in FIG.
FIG. 4 is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 20 Vacuum container 2, 21 Processing chamber 3, 23 To-be-processed object 4, 22 Mounting stand 6 Discharge tube 9 Discharge chamber 10, 24 Microwave waveguide 11, 27 Slit 12, 26 Sheet member 12a, 12c, 26a, 26c Heat-resistant layers 12b and 26b Thermal conductive layer 14 Metal member 25 Microwave transmission window member

Claims (6)

A process gas is introduced into the inside of the discharge tube formed of a dielectric material, and plasma is generated by irradiating the process gas inside the discharge tube with a microwave through a microwave waveguide. In the plasma processing apparatus in which the seed is supplied to the surface of the object to be processed,
A metal member made of a metal material disposed around the discharge tube at a connection portion between the microwave waveguide and the discharge tube;
A flexible sheet member provided between the discharge tube and the metal member,
The sheet member includes a pair of heat-resistant layers made of a heat-resistant material disposed on an inner peripheral side facing the discharge tube and an outer peripheral side facing the metal member, and heat disposed between the pair of heat-resistant layers. And a heat conductive layer made of a conductive material. A microwave guided through a microwave waveguide made of a metal material is introduced into a vacuum vessel through a microwave transmission window member formed of a dielectric, and the process gas introduced into the vacuum vessel is introduced into the vacuum vessel. In the plasma processing apparatus that generates plasma by irradiating the microwave and processes the surface of the object to be processed by the plasma,
A flexible sheet member disposed between the microwave waveguide and the microwave transmission window member, the sheet member facing the microwave transmission window member and the microwave waveguide; A plasma treatment comprising: a pair of heat-resistant layers made of a heat-resistant material arranged on the side facing the substrate; and a heat conductive layer made of a heat-conductive material arranged between the pair of heat-resistant layers apparatus. The plasma processing apparatus according to claim 1, wherein the heat conductive layer is made of a silicone sheet formed of a silicone material. 4. The plasma processing apparatus according to claim 1, wherein at least one of the pair of heat-resistant layers is made of a metal sheet formed of a metal material. 5. The plasma processing apparatus according to claim 4, wherein the metal sheet is an aluminum foil formed of aluminum. 4. The plasma processing apparatus according to claim 1, wherein at least one of the pair of heat-resistant layers is made of a sheet formed of a polyimide material. 5.

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