JP4132873B2 - Plasma processing apparatus and power supply member thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus and a power supply member thereof, and more particularly to a plasma processing apparatus in which a power supply member has a heat shut-off mechanism and a power supply member thereof.
[0002]
[Prior art]
In plasma processing performed in semiconductor manufacturing processes, liquid crystal display manufacturing processes, etc., a processing gas is introduced into an airtight processing vessel equipped with electrodes, and high-frequency power is applied to the electrodes to convert the processing gas into plasma. The surface of the object to be processed is subjected to predetermined processing such as etching and film formation.
[0003]
The plasma processing apparatus that performs the plasma processing includes a power supply member for electrically connecting the high-frequency power source and the electrode in order to apply high-frequency power to the electrode. This power supply member is also referred to as a conduction rod (hot return) or a power supply rod. This power supply member has heretofore been formed of a good conductor such as aluminum or copper in order to minimize loss of high-frequency power supplied to the electrodes from a high-frequency power source.
[0004]
FIG. 4 is a schematic cross-sectional view of a plasma etching apparatus 10 which is an example of a plasma processing apparatus provided with a conventional power supply member. As shown in FIG. 4, the plasma etching apparatus 10 includes, for example, a lower electrode 14 that serves as a mounting table, on which a semiconductor wafer W is mounted, for example, in a substantially cylindrical grounded airtight processing container 12. It is provided to be movable. The bottom surface portion of the processing container 12 and the bottom surface portion of the lower electrode 14 are hermetically connected by a bellows 20 formed in a substantially cylindrical bellows shape, and the inside of the processing container 12 is kept airtight.
[0005]
An upper electrode 18 is provided to face the lower electrode 14 and is grounded through the processing container 12. A gas introduction port 16 connected to a gas introduction system (not shown) is provided in the upper portion of the processing vessel 12, and a processing gas is introduced into the processing vessel 12 from a plurality of gas discharge ports 19 provided in the upper electrode 18. Introduce. For example, a mixed gas of C ₄ F ₆ gas, Ar gas, and O ₂ gas is used as the processing gas. An exhaust pipe 22 connected to an exhaust mechanism (not shown) is provided at the lower portion of the processing container 12, and the inside of the processing container 12 is maintained at a predetermined degree of vacuum by being evacuated through the exhaust pipe 22. Be drunk.
[0006]
A power supply member 50 for supplying, for example, high frequency power of 13.56 MHz from the high frequency power supply 26 via the matching unit 24 is provided below the lower electrode 14. As described above, the power supply member 50 is formed of a good conductor such as aluminum or copper, and is configured to efficiently transmit the high frequency power supplied from the high frequency power supply 26 to the lower electrode 14.
[0007]
The processing gas introduced into the processing vessel 12 is in a plasma state by the electric power supplied from the high-frequency power source 26, and is subjected to the energy of ions and radicals accelerated by the self-bias voltage generated in the vicinity of the lower electrode 14 between the electrodes. An etching process is performed to a process body.
[0008]
[Problems to be solved by the invention]
By the way, the lower electrode 14 is maintained at a predetermined temperature by a temperature adjusting mechanism (not shown) including a heater, a refrigerant supply unit, a temperature measuring member and the like embedded therein. A heat transfer gas (for example, He gas) is supplied between the semiconductor wafer W and the lower electrode 14 from a heat transfer gas supply mechanism (not shown) at a predetermined pressure, and the heat from the lower electrode 14 is transferred to the semiconductor wafer. It is configured to efficiently transmit to W, and the temperature of the semiconductor wafer W can be controlled.
[0009]
As described above, the lower electrode 14 also serves as a temperature control body of the semiconductor wafer W. For example, when etching polysilicon or the like, the lower electrode 14 is etched at 60 ° C. or more, and a silicon oxide film or the like is etched. In this case, the temperature is controlled from about 0 ° C to -20 ° C. At this time, a good conductor having a low electric resistance generally has a high thermal conductivity, and the power supply member 50 formed of a good conductor directly connected to the lower electrode 14 has a temperature equivalent to that of the lower electrode 14.
[0010]
However, if the power supply member 50 reaches a high temperature of, for example, 60 ° C. or higher, there is a risk that the operator may be burned during maintenance. In addition, there is a problem that it takes time to wait for the temperature to drop for safety and the efficiency is poor.
[0011]
Further, when the power supply member 50 is at a low temperature of, for example, 0 ° C. to −20 ° C., when it is exposed to the atmosphere as shown in FIG. 4, dew condensation occurs on the surface of the power supply member 50, and high-frequency creeping transmission occurs. There was a problem that there was a risk of happening.
[0012]
The present invention has been made in view of the above problems of the conventional plasma processing apparatus and its power supply member, and the object of the present invention is to cut off heat transmission while efficiently transmitting high-frequency power. It is an object of the present invention to provide a new and improved plasma processing apparatus and power supply member thereof.
[0013]
[Means for Solving the Problems]
In order to solve the above-described problems, according to the present invention, a processing gas is introduced into an airtight processing container and a high-frequency power is applied to form plasma of the processing gas. A power supply member that is provided in a plasma processing apparatus that performs plasma processing and electrically connects a high-frequency power source that generates high-frequency power and an electrode portion to which the high-frequency power is applied, the first power supply member being formed of a conductor Provided are a power supply member having a member, and a dielectric second member interposed between the first member and at least one layer, and a plasma processing apparatus including the power supply member. The second member is preferably formed of any one of alumina ceramic, bulk yttria, or zirconia.
[0014]
According to such a configuration, the first member of the conductor is directly connected to the high-frequency power source and the electrode unit, and at least one layer is provided on the first member, and the second member formed of a dielectric having low thermal conductivity is provided. Power can be transmitted efficiently and heat conduction can be cut off.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of a plasma processing apparatus and its power supply member according to the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.
[0016]
1 is a schematic cross-sectional view of a plasma etching apparatus 100 as an example of the plasma processing apparatus according to the present embodiment, FIG. 2 is a schematic cross-sectional view showing a power supply member 150, and FIG. 3 is a schematic view showing a power supply member 160. It is sectional drawing.
[0017]
As shown in FIG. 1, in the plasma etching apparatus 100, for example, a lower electrode 104 serving as a mounting table, on which a semiconductor wafer W is mounted, is mounted, for example, in a substantially cylindrical grounded airtight processing container 102. It can be moved up and down. The bottom surface portion of the processing container 102 and the bottom surface portion of the lower electrode 104 are hermetically connected by a bellows 120 formed in a substantially cylindrical bellows shape, and the inside of the processing container 102 is kept airtight.
An upper electrode 108 is provided to face the lower electrode 104 and is grounded through the processing container 102. In the present embodiment, high-frequency power is applied only to the lower electrode 104, but high-frequency power may be applied to the upper electrode 108.
[0019]
A gas introduction port 106 connected to a gas introduction system (not shown) is provided at the upper portion of the processing vessel 102, and processing gas is introduced into the processing vessel 102 from a plurality of gas discharge ports 109 provided in the upper electrode 108. Introduce. For example, a mixed gas of C ₄ F ₆ gas, Ar gas, and O ₂ gas is used as the processing gas.
[0020]
An exhaust pipe 110 connected to an exhaust mechanism (not shown) is provided at the lower part of the processing container 102, and the processing container 102 is kept at a predetermined vacuum level by being evacuated through the exhaust pipe 110. Be drunk. Further, magnets may be provided outside the both side walls of the processing vessel 102 to apply a magnetic field perpendicular to the electric field. In this case, it is preferable that the intensity of the magnetic field of the magnet is variable.
[0021]
The lower electrode 104 is maintained at a predetermined temperature by a temperature adjustment mechanism (not shown) including a heater, a refrigerant supply unit, a temperature measurement member and the like embedded therein. A heat transfer gas (for example, He gas) is supplied between the semiconductor wafer W and the lower electrode 104 from a heat transfer gas supply mechanism (not shown) at a predetermined pressure, and heat from the lower electrode 104 is supplied to the semiconductor wafer W. The temperature of the semiconductor wafer W can be controlled.
[0022]
A high frequency power source 114 is connected to the lower electrode 104 via a power supply member 150 and a matching unit 112. The frequency of the high frequency power supply 114 is, for example, 13.56 MHz. The configuration of the power supply member 150, which is a feature of the present invention, will be described later.
[0023]
As described above, the processing gas introduced into the processing container 102 is in a plasma state by the power supplied from the high-frequency power source 114 via the matching unit 112 and the power supply member 150 and is generated in the vicinity of the lower electrode 104 between the electrodes. The object to be processed is etched by the energy of ions and radicals accelerated by the self-bias voltage.
[0024]
Next, an operation when performing an etching process using the plasma etching apparatus 100 will be described. First, the semiconductor wafer W is placed on the lower electrode 104 in the processing chamber 102, and the processing chamber 102 is evacuated to a predetermined vacuum level or less by an exhaust mechanism (not shown) through the exhaust pipe 110. Thereafter, a predetermined processing gas is introduced into the processing container 102 from the gas introduction port 106 through the gas discharge port 109 at a predetermined flow rate, and adjusted to a predetermined degree of vacuum.
[0025]
The lower electrode 104 is adjusted so that the semiconductor wafer W is maintained at a predetermined temperature by a temperature adjusting mechanism inside thereof. For example, when etching polysilicon or the like, the lower electrode 104 is controlled to 60 ° C. or higher, and when etching a silicon oxide film or the like, the temperature is controlled from about 0 ° C. to −20 ° C. Subsequently, for example, high frequency power of 13.56 MHz is applied from the high frequency power source 114 via the matching unit 112 and the power supply member 150. By applying this high frequency power, the processing gas in the processing container 102 is turned into plasma, and a predetermined etching process is performed on the surface of the object to be processed.
[0026]
The power supply member 150, which is also referred to as a conduction rod (Hot / Return), will be described. As shown in FIG. 2, the power supply member 150, which is a feature of the present invention, includes three portions of conductors 152, 156 and a dielectric 154. Have. The conductors 152 and 156 are formed of a good conductor having a low electrical resistance such as aluminum or copper, and have a substantially cylindrical shape with a bottom area A, for example. The dielectric 154 is formed of a dielectric having low thermal conductivity and has a substantially cylindrical shape having a thickness d and a bottom area A. The shapes of the conductors 152, 156, and the dielectric 154 may be cylindrical or a column having a plurality of columnar cavities inside.
[0027]
In order to reduce the loss due to the electrostatic coupling of the high-frequency power between the conductors 152 and 156, it is preferable to increase the capacitance of the power supply member 150. The electrostatic capacity of the power supply member 150 is proportional to the dielectric constant of the dielectric 154 and the bottom area A, and inversely proportional to the thickness d. Therefore, the dielectric constant and the bottom area A are as large as possible, and the thickness d is as thin as possible. There is a need. The bottom area A is preferably as large as possible in the design of the plasma etching apparatus 100, and the thickness d is preferably thin as long as the dielectric 154 can be processed.
[0028]
Further, in order to thermally cut off the lower electrode 104 and the conductor 156, the dielectric 154 is preferably a material having low thermal conductivity. As a material of the dielectric 154, for example, alumina ceramic, bulk yttria, zirconia, or the like can be used in consideration of dielectric constant and thermal conductivity.
[0029]
According to the above configuration, the dielectric 154 is provided on the power supply member 150 that supplies high-frequency power to the lower electrode 104, and, for example, high-frequency power of 10 MHz or higher is efficiently transmitted, while the heat of the lower electrode 104 is transmitted to the power supply member 150. Since conduction to the lower conductor 156 can be blocked, danger during maintenance, reduction in work efficiency, and condensation on the surface of the power supply member 150 can be prevented.
[0030]
As shown in FIG. 3, a power feeding member 160 may be used instead of the power feeding member 150. The power supply member 160 has five parts: conductors 162, 166, 170 and dielectrics 164, 168. The conductors 162, 166, and 170 are made of a good conductor having a low electrical resistance, such as aluminum or copper, and have a substantially cylindrical shape with a bottom area A, for example. The dielectrics 164 and 168 are formed of a dielectric material having low thermal conductivity, and have a substantially cylindrical shape having thicknesses d1 and d2 and a bottom area A, respectively. The shapes of the conductors 162, 166, 170 and the dielectrics 164, 168 may be cylindrical or a columnar shape having a plurality of columnar cavities inside.
[0031]
In order to reduce the loss due to the electrostatic coupling of the high-frequency power between the conductors 162 and 166 and the conductors 166 and 170, it is preferable to increase the capacitance of the power supply member 160. The capacitance between the conductors 162 and 166 is proportional to the dielectric constant of the dielectric 164 and the bottom area A, and is inversely proportional to the thickness d1, and the capacitance between the conductors 166 and 170 is the dielectric constant of the dielectric 168. , And the bottom area A, and inversely proportional to the thickness d2, the dielectric constant and the bottom area A must be as large as possible, and the thicknesses d1 and d2 must be as thin as possible.
[0032]
The bottom area A is preferably as large as possible in the design of the plasma etching apparatus 100, and the thicknesses d1 and d2 are preferably thin as long as the dielectrics 164 and 168 can be processed.
[0033]
The dielectrics 164 and 168 are preferably made of a material having low thermal conductivity in order to thermally shield the lower electrode 104 and the conductor 170. Therefore, as materials for the dielectrics 164 and 168, for example, alumina, ceramic, bulk yttria, zirconia, or the like can be used in consideration of the dielectric constant and the thermal conductivity. According to the above configuration, since the two-layer dielectrics 164 and 168 having a heat blocking effect are provided, there is an effect that heat conduction can be further prevented while preventing loss of high frequency power of 10 MHz or more, for example.
[0034]
As described above, the power supply member 150 or 160 that transmits the power from the high-frequency power source 114 to the lower electrode 104 includes the dielectric 154 or the dielectrics 164 and 168 having a heat blocking effect. Can be efficiently transmitted to the lower electrode 104, and the temperature of the lower electrode 104, which also serves as a temperature control body, can be prevented from being conducted to the lower part of the power supply members 150 and 160, so that the lower electrode 104 is heated to 60 ° C. or higher. It is possible to safely and efficiently perform various processes including a process of etching polysilicon and a process of etching a silicon oxide film controlled to a low temperature of 0 to -20 ° C.
[0035]
While the preferred embodiments of the plasma processing apparatus and the power supply member according to the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such examples. It will be obvious to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.
[0036]
For example, when the plasma etching apparatus 100 is provided with the power supply members 150 and 160, the power supply members 150 and 160 have a substantially cylindrical shape. However, when the plasma processing apparatus has a rectangular column shape, for example, for manufacturing a liquid crystal display device, the power supply members 150 and 160 have a substantially rectangular column shape. Such differences in the outer shape are within the technical scope of the present invention.
[0037]
Further, the conductor and dielectric material forming the power supply member are not limited to the above. Although the case where the dielectric layer has one layer or two layers has been described, more dielectric layers may be formed. In addition, the position where the dielectric layer is arranged in the power supply member is determined in consideration of the design restrictions of the plasma processing apparatus, but the scope of the present invention is applicable as long as it has the same effect. It is understood that.
[0038]
【The invention's effect】
As described above, according to the present invention, at least one layer of dielectric is provided on the power supply member that supplies high-frequency power to the electrode in the plasma processing apparatus, and the high-frequency power is efficiently transmitted while being applied to the electrode. Since the generated heat can be blocked from conducting to the lower part of the power supply member, it is possible to safely and efficiently perform plasma treatment by preventing dangers during maintenance, lowering work efficiency, and condensation on the surface of the power supply member. .
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a plasma etching apparatus 100 according to an embodiment.
FIG. 2 is a schematic sectional view showing a power supply member 150. FIG.
3 is a schematic cross-sectional view showing a power feeding member 160. FIG.
4 is a schematic cross-sectional view of the plasma etching apparatus 10. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 Plasma etching apparatus 102 Processing container 104 Lower electrode 106 Gas inlet 108 Upper electrode 109 Gas outlet 110 Exhaust pipe 112 Matching device 114 High frequency power supply 120 Bellows 150 Feed member 152,156 Conductor 154 Dielectric

Claims (3)

A plasma processing apparatus for introducing a processing gas into an airtight processing container and applying a high frequency power to form a plasma of the processing gas and performing a predetermined plasma processing on a processing surface of an object to be processed is provided, A power supply member that electrically connects a high-frequency power source that generates high-frequency power and an electrode portion to which the high-frequency power is applied,
A first member formed of a conductor;
Wherein the first member, possess at least one layer, and a second member of the dielectric interposed in layers parallel to the processing surface of the object to be processed, the,
The power supply member , wherein the second member is formed of any one of alumina ceramic, bulk yttria, or zirconia . 2. The power supply member according to claim 1, wherein the second member is interposed in the first member in a layered manner in two or more layers in parallel with the processing surface of the object to be processed .   The plasma processing apparatus provided with the electric power feeding member of Claim 1 or Claim 2.

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