JP3736264B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus and a plasma processing method capable of uniformly processing a target object provided with an insulating substrate.
[0002]
[Background Art and Problems to be Solved by the Invention]
In a plasma processing apparatus, for example, a dry etching apparatus used for manufacturing a semiconductor, a semiconductor wafer is generally used as an object to be processed, and the semiconductor wafer is exposed to plasma in a state of being mounted and fixed on a lower electrode. Dry etching is performed. Prior to dry etching, when a semiconductor wafer is placed on the lower electrode, first, the semiconductor wafer whose lower surface peripheral edge is supported by the object holder of the transfer mechanism is transferred above the lower electrode. . Then, the lifter pin protrudes from the lower electrode through the pin hole formed in the lower electrode toward the vicinity of the center of the object to be processed. In this state, the object holding part of the transport mechanism is lowered. The semiconductor wafer is delivered to the lifter pins. Thereafter, the object holder of the transport mechanism is moved outside the plasma processing apparatus. Then, the lifter pin protruding from the pin hole is retracted and retracted from the lower electrode. As a result, the object to be processed is placed on the lower electrode, and then plasma processing is performed.
[0003]
During the plasma treatment, a voltage is applied between the lower electrode and the upper electrode, and the semiconductor wafer placed on the lower electrode has almost the same potential as the lower electrode. Plasma processing is performed by gathering on the wafer. Therefore, the region of the semiconductor wafer corresponding to the pin hole described above has a potential slightly different from that of the lower electrode, and etching in that region may proceed at a speed different from that of the surrounding region. However, since the object to be processed in semiconductor manufacturing is generally a semiconductor wafer having high electrical conductivity, even in the region corresponding to the pin hole in the object to be processed, the potential is almost the same as the surrounding region, and the etching rate is also high. Almost equal.
[0004]
However, when the base material of the object to be processed is formed of a nonconductor such as glass, for example, when the glass substrate used for the liquid crystal panel is the base material of the object to be processed, the region corresponding to the pin hole, A potential difference may occur between the surrounding areas and the etching rate may be significantly different. Thus, when the base material of the object to be processed is a nonconductor, the uniformity of the plasma processing may be impaired in the region corresponding to the pin hole and the surrounding region.
[0005]
The present invention has been made in view of the above points, and its purpose is to provide a region corresponding to a pin hole for a lifter pin and its surroundings even when the substrate of the object to be processed is a non-conductor. It is an object of the present invention to provide a plasma processing apparatus and a plasma processing method in which plasma processing is substantially uniform in the region.
[0006]
[Means for Solving the Problems]
(1) A plasma processing apparatus according to the present invention comprises:
An airtight container, a plasma generation source disposed in the airtight container, a lower electrode disposed in the airtight container and on which a workpiece is placed, and an upper electrode facing the lower electrode in the airtight container And a lifter pin that is inserted into a through-hole provided in the lower electrode so that the object to be processed can be pushed up from the lower electrode, is made of a conductive material, and has the same potential as the lower electrode. In the processing apparatus, the lifter pin further includes a covering portion that covers the tip region made of a softer material than the tip region, and the covering portion is formed of a conductive material. And
[0007]
According to the present invention, even when the lifter pin is covered with a soft material in order to prevent damage to the object to be processed, the lifter pin is interposed between the tip region of the lifter pin and the outer surface of the covering portion covering the tip region. Almost no potential difference occurs. Therefore, by bringing the lifter pin into contact with the object to be processed through the covering portion, the region corresponding to the through hole of the lower electrode in the object to be processed is directly aligned with the tip region of the lifter pin having the same potential as the lower electrode. The same potential as that in the case of contacting the object to be processed can be obtained. Therefore, the potential distribution of the object to be processed including the region corresponding to the through hole can be made substantially uniform, and the object to be processed can be uniformly plasma-processed.
[0008]
(2) The plasma processing apparatus according to the present invention further includes an elastic body that elastically contacts the lifter pin with the object to be processed.
[0009]
According to the present invention, since the lifter pin is brought into contact with the object to be processed by the elasticity of the elastic body, the lifter pin can be reliably brought into contact with the object to be processed. Further, since the lifter pin is pressed against the object to be processed by being pressed through the elastic body, an excessive force is applied to the object to be processed by using an elastic body having an appropriate elastic constant with an appropriate amount of deformation. It is possible to prevent the object to be processed from being damaged or damaged.
[0012]
(3) The plasma processing apparatus according to the present invention is characterized in that, in (1), the covering portion is formed of a resin having a thickness of 10 μm to 100 μm.
[0013]
According to the present invention, the covering portion is made of a resin having a thickness of 10 μm to 100 μm, and there is almost no potential difference between the tip region of the lifter pin and the outer surface of the covering portion covering the tip region. Therefore, by bringing the lifter pin into contact with the object to be processed through the covering portion, the region corresponding to the through hole of the lower electrode in the object to be processed is directly aligned with the tip region of the lifter pin having the same potential as the lower electrode. The same potential as that in the case of contacting the object to be processed can be obtained. Therefore, the potential distribution of the object to be processed including the region corresponding to the through hole can be made substantially uniform, and the object to be processed can be uniformly plasma-processed. In addition, since the lifter pins come into contact with the object to be processed through the covering portion formed of a material softer than the tip region, the possibility of damaging the object to be processed is low.
[0016]
(4) The plasma processing apparatus according to the present invention further includes a fixing mechanism that fixes the object to be processed to the lower electrode.
[0017]
According to the present invention, the object to be processed can be reliably adhered to the lower electrode by the fixing mechanism, and the object to be processed can have a uniform potential distribution. Further, even when the lifter pin comes into contact with the object to be processed with elasticity, the object to be processed does not float from the lower electrode.
[0018]
(5) A plasma processing method according to the present invention is a method of performing plasma processing on an object to be processed using the plasma processing apparatus according to claim 1, wherein the plasma processing method is provided on the lifter pin in a state of protruding from the lower electrode. A placing step of placing the object to be treated, a fixing step in which the lifter pin is in contact with the object to be treated, and the object to be treated is fixed on the lower electrode, and the fixing step. A plasma processing step of plasma processing the object to be processed in a fixed state.
[0019]
According to the present invention, the lifter pin located in the through hole of the lower electrode is in contact with the object to be processed while the object to be processed is fixed on the lower electrode and subjected to the plasma treatment. Therefore, since the lifter pin having the same potential as that of the lower electrode is in contact with the object to be processed even in the portion where the through hole of the lower electrode is located, the potential distribution of the object to be processed including the region corresponding to the through hole is uniform. Thus, the object to be processed can be uniformly plasma processed.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described more specifically with reference to the drawings.
[0021]
1. <Structure of plasma processing apparatus>
FIG. 1 is a schematic cross-sectional view showing the overall configuration of an etching apparatus 10 as a plasma processing apparatus in the present embodiment. As shown in this figure, the etching apparatus 10 includes an airtight container 20, a high frequency power supply 30, an upper electrode 40, a lower electrode 50, and a lifter pin 60.
[0022]
The shape and material of the airtight container 20 are not particularly limited. For example, the airtight container 20 has a cylindrical shape and is formed of aluminum having an anodized surface, and the plasma generation source 30, the upper electrode 40, and the lower electrode 50 are provided inside. Is housed in. The airtight container 20 can be opened and closed by an opening / closing mechanism (not shown) such as a gate valve mechanism. When the opening / closing mechanism is closed, the airtight container 20 is in an airtight state, and a desired vacuum state (for example, several Pa to several Pa) by a vacuum pump (not shown) connected to the exhaust pipe 22. It can be about 10 Pa.
[0023]
The shape and material of the upper electrode 40 are not particularly limited. For example, the upper electrode 40 has a hollow disk shape, is formed of aluminum, and the surface is anodized, and an electrode lifting mechanism 44 such as an air cylinder or a ball screw is formed in the upper portion of the airtight container 20. And can be moved up and down via a connecting rod. The upper electrode 40 is connected to a reaction gas supply pipe 24 that introduces at least one of a reaction gas such as argon, helium, sulfur hexafluoride, and carbon tetrafluoride from a gas supply source (not shown) into the hollow portion. Has been. In addition, a large number of small holes (not shown) are provided on the lower surface of the upper electrode 40, and the reaction gas can flow into the hermetic container 20 from the small holes. The upper electrode 40 is connected to a high frequency power source 30 having a power of about 500 to 1500 W and a frequency of about 300 kHz to 13 MHz, for example. On the outer periphery of the upper electrode 40 and the periphery of the lower surface, a shield ring 42 made of an insulating material such as a tetrafluoroethylene resin is used so that plasma is generated in a region of approximately the same size as the object 90 to be processed held by the lower electrode 50. Is provided. The upper electrode 40 may be formed of carbon or silicon.
[0024]
Further, an upper electrode cooling block 48 for cooling the upper electrode 40 is provided in contact with the upper surface of the upper electrode 40. In the upper electrode cooling block 48, a coolant can be circulated from a coolant circulator (not shown) via a coolant pipe 49.
[0025]
The lower electrode 50 has a disk shape, is formed of aluminum, has a surface anodized, is disposed below the hermetic container 20, and is electrically grounded. The lower electrode 50 also serves as a mounting table for the object to be processed 90 (for example, a glass substrate), and the mounting surface, that is, the upper surface is formed in a somewhat convex shape. An object to be processed that is held in a target object holder of a transport mechanism (not shown) and is carried in is placed on the lower electrode 50. Further, a through hole 52 is provided in the vicinity of the center of the lower electrode 50 for allowing the lifter pin 60 that pushes up the object to be processed to pass therethrough. Further, a clamp ring 80 for fixing the periphery of the object 90 to be mounted to the lower electrode 50 with a desired clamp load is provided on the upper outer periphery of the lower electrode 50 via a connecting rod 81, such as a ring lifting mechanism 82 such as an air cylinder. It can be moved up and down. The clamp ring 80 is made of aluminum and has a surface anodized. The fixing mechanism that fixes the object to be processed includes the clamp ring 80, the connecting rod 81, and the ring elevating mechanism 82 described above.
[0026]
Further, a lower electrode cooling block 56 is provided at the lower part of the hermetic container 20 in contact with the lower surface of the lower electrode 50. In the lower electrode cooling block 56, a coolant such as water can be circulated from a coolant circulator (not shown) via a cooling pipe 57.
[0027]
In the etching apparatus 10 as the plasma processing apparatus of the present embodiment, a plasma generating part is formed by the upper electrode 40 connected to the reaction gas supply pipe 24 and the high frequency power source 30 and the grounded lower electrode 50, and the upper electrode is formed. Plasma is generated in the space between 40 and the lower electrode 50.
[0028]
Three or four lifter pins 60 are provided, and are formed so as to be able to push up the workpiece 90 through the through hole 52 provided in the lower electrode 50. Specifically, the lifter pin 60 is connected to a pin lifting mechanism 62 such as an air cylinder through a connecting portion 66. Further, as shown in FIG. 2 as a partially enlarged longitudinal sectional view in the vicinity of the tip, the lifter pin 60 is formed by covering the main body 63 with a covering portion 64 having a bottomless hollow cylindrical shape. The main body 63 of the lifter pin 60 is made of a conductive material such as stainless steel and has the same potential as the lower electrode 50. The covering portion 64 of the lifter pin 60 is softer than the main body portion, and is a resin having a thickness of 10 μm to 100 μm, more preferably a resin having a thickness of 20 μm to 70 μm, such as a polyimide resin, a fluororesin, a silicon resin, or an organic type, It is formed of the resin in which an inorganic pigment is dispersed. As shown in FIG. 1, the lifter pin 60 is to be processed 90 placed on the lower electrode 50 at least while plasma is generated from a plasma generation source, that is, during plasma processing. It is made into the state contact | abutted to the lower surface of this. A spring 67 as an elastic body is incorporated in the connecting portion 66 that connects the lifter pin 60 and the pin lifting mechanism 62. The lifter pin 60 is elastically brought into contact with the workpiece 90 by the action of the spring 67.
[0029]
As described above, in the etching apparatus 10 which is the plasma processing apparatus according to the present embodiment, the lifter pin 60 is brought into contact with the object 90 by the elasticity of the spring 67, so that the lifter pin 60 is securely attached to the object 90. Can be contacted. Further, when the lifter pin 60 is pressed by the pin lifting mechanism 62 via the spring 67, the lifter pin 60 is pressed against the workpiece 90. Therefore, the lifter pin 60 can be pressed against the workpiece 90 with an appropriate pressing force by using the spring 67 having an appropriate elastic constant with an appropriate amount of deformation, and an excessive force is applied to the workpiece 90 from the lifter pin 60. It can prevent that the to-be-processed object 90 is damaged or damaged by adding.
[0030]
Further, since the lifter pin 60 comes into contact with the object to be processed 90 through the covering part 64 formed of a softer material than the main body part 63, the possibility of damaging the object to be processed 90 is further reduced. be able to.
[0031]
Further, as described above, since the covering portion 64 is formed of resin, it has almost no electrical conductivity, but its thickness is about 10 μm to 100 μm, and the outer surface of the covering portion 64 and the tip of the main body portion 63. The thickness is such that there is almost no potential difference between the region. Therefore, by bringing the lifter pin 60 into contact with the object 90 via the covering portion 64, the region corresponding to the through hole of the lower electrode 50 in the object 90 is lifted at the same potential as the lower electrode 50. The potential can be made substantially the same as when the tip region of the pin 60 directly contacts the workpiece 90. As a result, even when the substrate is made of a material having low conductivity, such as glass or ceramic, uniform plasma treatment is performed in the region corresponding to the through hole and the surrounding region. Is possible.
[0032]
Further, in the etching apparatus 10 of the present embodiment, the workpiece 90 is fixed to the lower electrode 50 by a fixing mechanism including the clamp ring 80, the connecting rod 81, and the ring lifting mechanism 82. . Therefore, the target object 90 can be securely adhered to the lower electrode 50 by the fixing mechanism, and the target object 90 can have a uniform potential distribution. Further, the object 90 is not lifted from the lower electrode 50 due to the pressing force of the lifter pin 60 that contacts the object 90 with elasticity.
[0033]
2. <Operation of plasma processing apparatus>
Next, operation | movement of the etching apparatus 10 as a plasma processing apparatus of this embodiment is demonstrated.
[0034]
First, the lifter pin 60 is projected from the lower electrode 50. And the to-be-processed object 90 is carried into the airtight container 20 by the lower-surface peripheral part being supported by the to-be-processed object holding | maintenance part of the conveyance mechanism which is not shown in figure, and it shows as a typical fragmentary sectional view in FIG. It is placed on the lifter pin 60.
[0035]
Thereafter, by operating the pin lifting mechanism 62 to lower the lifter pin 60 and retracting it from the lower electrode 50, the workpiece 90 is moved to the lower electrode 50 as shown in a schematic partial sectional view in FIG. It is assumed that it is placed on top.
[0036]
And after moving the to-be-processed object holding | maintenance part of a conveyance mechanism to the exterior of the airtight container 20, the airtight container 20 is sealed. Thereafter, the ring elevating mechanism 82 is operated to lower the clamp ring 80, and the object 90 is pressure-bonded to the lower electrode 50. Thereafter, the lifter pin 60 is lifted somewhat again by the pin lifting mechanism 62, and the lifter pin 60 comes into contact with the workpiece 90 with an appropriate pressing force as shown in a schematic partial sectional view in FIG. State.
[0037]
The inside of the airtight container 20 is evacuated to a predetermined degree of vacuum, for example, about several Pa to several tens Pa by a vacuum pump (not shown). Further, the upper electrode 40 connected by the connecting rod 45 is lowered by the operation of the electrode lifting mechanism 44, and the electrode interval with the lower electrode 50 is set to an appropriate interval, for example, about several mm.
[0038]
Next, a reaction gas such as argon, helium, sulfur hexafluoride, carbon tetrafluoride or the like is supplied from a gas supply source (not shown) to the upper electrode 40 via the reaction gas supply pipe 24, and this reaction gas is supplied. Flows into the airtight container 20 through a small hole (not shown) on the lower surface of the upper electrode 40. At the same time, a high-frequency voltage is applied to the upper electrode 40 by the high-frequency power source 30 to generate plasma in a space between the grounded lower electrode 50. The object 90 on the lower electrode 50 is etched by this plasma.
[0039]
When the etching is completed, the reverse of the above process, that is, the clamp ring 80 is lifted to release the pressure-bonding between the workpiece 90 and the lower electrode 50, and the lifter pin 60 is lifted to push the workpiece 90 up. In this state, the workpiece 90 is received and held from below by the workpiece holder of the transport mechanism and is taken out from the airtight container 20.
[0040]
3. <Modification>
3.1 In the above, the example in which the high frequency power supply 30 is connected to the upper electrode 40 and the lower electrode 50 is grounded has been described. However, the applied potential may be reversed to ground the upper electrode 40 and connect the high frequency power supply 30 to the lower electrode 50. Even in this case, the lower electrode 50 and the lifter pin 60 are set to the same potential.
[0041]
3.2 In the above, an example in which the lifter pin 60 is formed by covering the tip region of the main body 63 with the coating 64 made of resin is shown. However, the lifter pin may be formed only of the main body portion as long as the lower surface of the object to be processed can be brought into contact without being damaged. Even when this lifter pin is used, the lifter pin having the same potential as the lower electrode is in contact with the object to be processed even in the portion where the through hole of the lower electrode is located. In addition, the potential distribution of the object to be processed becomes uniform, and the object to be processed can be uniformly plasma processed.
[0042]
3.3 In the above, the example of the lifter pin 60 in which the main body portion 63 is formed by being covered with the covering portion 64 having a bottomless hollow cylindrical shape is shown. However, as shown in FIG. 4, a lifter provided with a covering portion 97 in which a resin film 98, for example, a polyimide resin film having a thickness of about 25 μm or a fluororesin film is bonded to an end of a main body 96 with an adhesive 99 having a thickness of about 10 to 25 μm. The pin 95 may be used. The adhesive is not particularly specified as long as it is not deteriorated due to an increase in temperature caused by heat transmitted from the object 90 or the like. Even when this lifter pin 95 is used, since the lifter pin having the same potential as that of the lower electrode is in contact with the object to be processed even in the portion where the through hole of the lower electrode is located, it corresponds to the through hole. The potential distribution of the object to be processed including the region becomes almost uniform, and the object to be processed can be subjected to plasma processing almost uniformly.
[0043]
3.4 In the above, an example is shown in which the lifter pin is formed by covering the tip of the main body with a resin softer than the main body and having an insulating property, for example, a polyimide resin. However, the covering portion may be formed of a conductive material that is softer than the main body portion, such as a resin material or a conductive polymer material in which carbon or metal is dispersed.
[0044]
3.5 Further, in the above, an example of a plasma etching apparatus is shown as an example of a plasma processing apparatus, but the present invention can also be applied to a plasma CVD apparatus, a sputtering apparatus, and an ion implantation apparatus.
[0045]
3.6 In the above, an example in which plasma is generated between the upper electrode 40 and the lower electrode 50 has been described. However, the plasma processing apparatus may be formed so that the plasma is generated in a region that is not in the space between the upper electrode 40 and the lower electrode 50 in the hermetic container 20 and is collected on the lower electrode 50.
[0046]
3.7 The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an etching apparatus according to an embodiment.
FIG. 2 is a longitudinal sectional view showing the vicinity of the tip of a lifter pin used in the etching apparatus of the embodiment.
FIGS. 3A, 3B, and 3C are partial cross-sectional views for explaining the operation of the etching apparatus according to the embodiment. FIGS.
FIG. 4 is a longitudinal sectional view showing the vicinity of a tip of a lifter pin in a modified example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Etching apparatus 20 Airtight container 40 Upper electrode 50 Lower electrode 52 Through-hole 60 Lifter pin 64 Covering part 67 Spring (elastic body)
90 workpiece

Claims (5)

  An airtight container, a plasma generation source disposed in the airtight container, a lower electrode disposed in the airtight container and on which a target object is placed, and an upper electrode facing the lower electrode in the airtight container And a lifter pin that is inserted into a through-hole provided in the lower electrode so that the object to be processed can be pushed up from the lower electrode, is made of a conductive material, and has the same potential as the lower electrode. In the processing apparatus, the lifter pin further includes a covering portion that covers the tip region made of a softer material than the tip region, and the covering portion is formed of a conductive material. A plasma processing apparatus.   The plasma processing apparatus according to claim 1, further comprising an elastic body that elastically contacts the lifter pin with the object to be processed.   The plasma processing apparatus according to claim 1, wherein the covering portion is formed of a resin having a thickness of 10 μm to 100 μm.   4. The plasma processing apparatus according to claim 1, further comprising a fixing mechanism that fixes the object to be processed to the lower electrode. 5.   A method for plasma-treating an object to be processed using the plasma processing apparatus according to claim 1, wherein the object to be processed is placed on the lifter pin protruding from the lower electrode; A fixing process in which the lifter pin is in contact with the object to be processed and the object to be processed is fixed on the lower electrode, and plasma for plasma processing the object to be processed in the fixing state by the fixing process A plasma processing method comprising: a processing step.

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