Patent Application
20050236111
1. Field of the Invention
The present invention relates to a processing apparatus for performing a desired process on a substrate to be processed on a table in a processing chamber. More particularly, the present invention relates to a processing apparatus that employs a method for heating the substrate on the table.
2. Description of the Related Art
In a single-wafer process, a substrate to be processed is placed on a table in a processing chamber that is in a vacuum state. Typically this process comprises steps such as etching, deposition, oxidation, and sputtering performed during the manufacturing of semiconductor devices or FPDs (Flat Panel Displays). Process gas is then supplied to the inside of the processing chamber while the temperature of the substrate is kept constant on the table. In that process, plasma is often used to accelerate ionization, chemical reaction or the like of the process gas.
The methods for controlling the temperature in that type of process are generally categorized into a cooling method for cooling a substrate on the table to maintain a constant substrate temperature, and a heating method for heating a substrate on the table to maintain a constant substrate temperature. Known conventional heating methods include: a plasma-heat-input method for heating a substrate with incident heat from plasma, a lamp heating method for heating a substrate with heat radiated from a lamp provided above the table, and a hot-plate method for heating a substrate with heat generated by the resistance of a heating wire provided inside the table. In the hot-plate method, an electrostatic chuck is provided above the table or on the upper surface of the table in order to improve the efficiency and uniformity of heat conduction from the table to the substrate. The substrate is pressed against the table with the electrostatic absorbing force provided by the electrostatic chuck.
However, the plasma-heat-input method has the disadvantage that the substrate temperature is sensitive to change in the plasma and therefore controlling temperature independently of the plasma is difficult. The lamp heating method has the disadvantage that it is difficult to attach the lamp to the processing chamber for mechanical reasons, or for reasons of space. For instance, in a parallel-plate type plasma processing apparatus, the table is used as a lower electrode and an opposing upper electrode is arranged above the table. It is therefore usual that space for the lamp cannot be made within the processing chamber. In the hot-plate method, the heating wire is incorporated into the table and a feed line is drawn from an external heater power supply to the heating wire. This complicates the structure of the inside of the table and increases its fabrication costs. When the hot-plate method is combined with the use of an electrostatic chuck, both the heating wire and wiring for the electrostatic chuck must be provided in the table, along with their feed lines. The structure inside the table becomes very complicated, and expensive to fabricate.
The present invention was made in view of the disadvantages of the aforementioned conventional techniques. It is an object of the present invention to provide a processing apparatus which can control the temperature of a substrate to be processed on a table at a desired temperature by a heating method that does not complicate the structure inside the table and requires no special heating arrangement.
In order to achieve the above object, the first processing apparatus of the present invention comprises: a processing chamber for providing a processing space in which a predetermined process is performed on a substrate to be processed; a table on which the substrate is placed in the processing chamber; a conductor provided inside the table so as to be close to a substrate-placed surface of the table; a direct-current power supply for applying a direct-current voltage for electrostatic absorption to the conductor via a first feed line; a radio-frequency power supply, electrically connected at one output terminal to the conductor via a second feed line, for outputting radio-frequency radiation for heating; and a radio-frequency bypass circuit for cutting off a direct current and allowing the radio-frequency radiation to pass between a predetermined node provided in the middle of the first feed line and the other output terminal of the radio-frequency power supply, wherein a radio-frequency current output from the radio-frequency power supply flows in a closed circuit including the radio-frequency power supply, the second feed line, the conductor, the first feed line, and the radio-frequency bypass circuit, and Joule heat in the conductor heats the substrate on the table.
In the first processing apparatus described above, the radio-frequency current output from the radio-frequency power supply flows through the conductor provided inside the table via the first and second feed lines, thereby causing the conductor to generate Joule heat that heats the substrate on the table by thermal conduction. The first feed line is also used for applying the direct-current voltage for electrostatic absorption from the direct-current power supply to the conductor inside the table. Due to the operation of the radio-frequency bypass circuit, feeding of the radio-frequency radiation for heating and feeding of the direct-current voltage for electrostatic absorption can be achieved simultaneously in the first feed line.
In a preferred embodiment of the present invention, the table includes: a conductive body electrically connected to the one output terminal of the radio-frequency power supply via the second feed line; and an electrostatic chuck which is provided on the conductive body and includes the conductor and dielectric portions sandwiching the conductor therebetween from upper and lower sides. In this structure, the conductive body and the conductor are coupled by alternating-current coupling or capacity coupling via the dielectric portion. The radio-frequency current from the radio-frequency power supply flows from the conductive body to various portions of the conductor via the dielectric portion and flows from the various portions of the conductor to the conductive body via the dielectric portion. Thus, the various portions of the conductor, i.e., the entire conductor generate Joule heat.
In another embodiment, the table may include a ceramic body including the conductor therein. In this structure, an electrostatic chuck is also formed by the conductor and ceramic portions sandwiching the conductor therebetween. In this case, the second feed line may be connected directly to the conductor.
According to the present invention, the second processing apparatus comprises: a processing chamber for allowing plasma to be generated or introduced therein; a first electrode on which a substrate to be processed is placed in the processing chamber; an electrostatic chuck that is provided on the first electrode and includes an electrode portion and dielectric portions sandwiching the electrode portion therebetween from upper and lower sides; a direct-current power supply for applying a direct-current voltage for electrostatic absorption to the electrode portion of the electrostatic chuck via a first feed line; a first radio-frequency power supply, electrically connected at one output terminal to the first electrode via a second feed line, for outputting first radio-frequency radiation for heating; a radio-frequency bypass circuit for cutting off a direct current and allowing the first radio-frequency radiation to pass between a first node provided in the middle of the first feed line and the other output terminal of the first radio-frequency power supply; a second radio-frequency power supply, electrically connected at one output terminal to the first electrode via a third feed line and the second feed line, for outputting second radio-frequency radiation for radio-frequency bias; and a first filter circuit, provided in the middle of the first feed line so as to be closer to the electrode portion of the electrostatic chuck than the first node, for allowing the direct-current voltage from the direct-current power supply and the first radio-frequency radiation from the first radio-frequency power supply to pass therethrough and cutting off the second radio-frequency radiation from the second radio-frequency power supply. In this processing apparatus, the first radio-frequency current output from the first radio-frequency power supply flows in a closed circuit including the first radio-frequency power supply, the second feed line, the electrode portion of the electrostatic chuck, the first feed line, the first filter circuit, and the radio-frequency bypass circuit, and Joule heat in the electrode portion of the electrostatic chuck heats the substrate on the table.
In the second processing apparatus described above, the first radio-frequency current output from the first radio-frequency power supply flows through the electrode portion of the electrostatic chuck via the first and second feed lines, thereby causing the electrode portion to generate Joule heat that heats the substrate on the table by thermal conduction. The first feed line is also used for applying the direct-current voltage for electrostatic absorption from the direct-current power supply to the electrode portion of the electrostatic chuck. The second feed line is also used for feeding the second radio-frequency radiation for radio-frequency bias from the second radio-frequency power supply to the first electrode. In the first feed line, both feeding of the radio-frequency radiation for heating and feeding of the direct-current voltage for electrostatic absorption can be achieved due to the operation of the radio-frequency bypass circuit.
In a preferred embodiment of the present invention, a second filter circuit for allowing the first radio-frequency radiation from the first radio-frequency power supply to pass therethrough and cutting off the second radio-frequency radiation from the second radio-frequency power supply is provided in the middle of the second feed line so as to be closer to the one output terminal of the first radio-frequency power supply than a second node at which the third feed line and the second feed line are connected. By providing the second filter circuit as described above, it is possible to protect the first radio-frequency power supply against the second radio-frequency radiation for radio-frequency bias and use the second feed line for both the first and second radio-frequency radiations. It is preferable that a third filter circuit for allowing the second radio-frequency radiation from the second radio-frequency power supply to pass therethrough and cutting off the first radio-frequency radiation from the first radio-frequency power supply be provided in the middle of the third feed line. That third filter circuit can protect the second radio-frequency power supply against the first radio-frequency radiation for heating.
In another preferred embodiment of the present invention, a second electrode is arranged in the processing chamber to be opposed to the first electrode with a predetermined space therebetween. In this case, the second radio-frequency radiation, that is supplied from the second radio-frequency power supply to the first electrode, can serve as radio-frequency radiation for generating plasma between the first and second electrodes. Alternatively, third radio-frequency radiation for generating plasma can be supplied from a third radio-frequency power supply to the second electrode via a fourth feed line. In the first feed line, it is preferable that the first filter circuit cut off the third radio-frequency radiation from the third radio-frequency power supply.
According to the present invention, the third processing apparatus comprises: a processing chamber for allowing plasma to be generated or introduced therein; a first electrode on which a substrate to be processed is placed in the processing chamber; an electrostatic chuck that is provided on the first electrode and includes an electrode portion and dielectric portions sandwiching the electrode portion therebetween from upper and lower sides; a direct-current power supply for applying a direct-current voltage for electrostatic absorption to the electrode portion of the electrostatic chuck via a first feed line; a first radio-frequency power supply, electrically connected at one output terminal to the first electrode via a second feed line, for outputting first radio-frequency radiation for heating; a radio-frequency bypass circuit for cutting off a direct current and allowing the first radio-frequency radiation to pass between a first node provided in the middle of the first feed line and the other output terminal of the first radio-frequency power supply; a second electrode arranged in the processing chamber to be opposed to the first electrode; a third radio-frequency power supply for supplying third radio-frequency radiation for plasma generation to the second electrode via a fourth feed line; and a first filter circuit, provided in the middle of the first feed line so as to be closer to the electrode portion of the electrostatic chuck than the first node, for allowing the direct-current voltage from the direct-current power supply and the first radio-frequency radiation from the first radio-frequency power supply to pass therethrough and cutting off the third radio-frequency radiation from the third radio-frequency power supply. In this processing apparatus, the first radio-frequency current output from the first radio-frequency power supply flows in a closed circuit including the first radio-frequency power supply, the second feed line, the electrode portion of the electrostatic chuck, the first feed line, the first filter circuit, and the radio-frequency bypass circuit, and Joule heat in the electrode portion of the electrostatic chuck heats the substrate on the table.
In the third processing apparatus described above, the first radio-frequency current output from the first radio-frequency power supply flows through the electrode portion of the electrostatic chuck via the first and second feed lines, thereby causing the electrode portion to generate Joule heat that heats the substrate on the table by thermal conduction. The first feed line is also used for applying the direct-current voltage for electrostatic absorption from the direct-current power supply to the electrode portion of the electrostatic chuck. Due to the operation of the radio-frequency bypass circuit, both feeding of the radio-frequency radiation for heating and feeding of the direct-current voltage for electrostatic absorption can be achieved in the first feed line.
It is preferable that a second filter circuit for allowing the first radio-frequency radiation from the first radio-frequency power supply to pass therethrough and cutting off the third radio-frequency radiation from the third radio-frequency power supply be provided in the middle of the second feed line. That second filter circuit can protect the first radio-frequency power supply against the second radio-frequency radiation for plasma generation.
According to the present invention, the fourth processing apparatus comprises: a processing chamber for providing a processing space in which a predetermined process is performed on a substrate to be processed; a table on which the substrate is placed in the processing chamber, the table including a dielectric portion; a first conductor provided inside the table to be close to a substrate-placed surface of the table; a second conductor provided below the first conductor to be opposed to the first conductor with the dielectric portion partially or entirely sandwiched between the first and second conductors; and a radio-frequency power supply for applying radio-frequency radiation for heating between the first and second conductors, wherein the substrate on the table is heated by heat generated by dielectric loss of the dielectric portion to which an electric field of the radio-frequency radiation from the radio-frequency power supply is applied.
In the fourth processing apparatus, when the radio-frequency radiation from the radio-frequency power supply is applied across the first and second conductors, the inside of the dielectric portion of the table generates heat due to dielectric loss under the radio-frequency electric field formed between the first and second conductors. Thus, the substrate on the table is heated by thermal conduction. In order to hold the substrate on the table, a direct-current voltage for electrostatic absorption can be applied to the first conductor.
According to the processing apparatus of the present invention, the temperature of the substrate to be processed on the table can be controlled at a given temperature by a heating method that does not make the structure inside the table complicated and requires no special heating arrangement, due to the aforementioned structures and operations.
Preferred embodiments of the present invention are now described with reference to the accompanying drawings.
On the bottom of the chamber 10, a columnar support 14 is arranged on an insulation plate 12 formed of ceramic or the like. The support 14 is formed of aluminum, for example. A disc-like susceptor 16 that is formed of aluminum, for example, is provided on the support 14. The susceptor 16 serves as both a table and a lower electrode. A substrate to be processed, for example, the semiconductor wafer W, is placed on the susceptor 16.
An electrostatic chuck 18 for holding the semiconductor wafer W with a Coulomb force or a Johnson-Rahbeck force is provided on the upper surface of the susceptor 16. The electrostatic chuck 18 includes an electrode portion 20 formed by a conductive plate or film, and a pair of dielectric or insulation sheets 22 and 24 which sandwich the electrode portion 20 therebetween. To the electrode portion 20 is electrically connected an output terminal of a direct-current power supply 28 via a feed line 26. By application of a direct-current voltage from the direct-current power supply 28, the electrostatic chuck 18 absorbs and holds, the semiconductor wafer W with the Coulomb force or Johnson-Rahbeck force. It is preferable to use high-melting point metal such as tungsten, molybdenum, or nickel as the material for the electrode portion 20. The feed line 26 is accommodated in an insulation sheath (not shown) that extends from under the chamber 10 and runs through the bottom plate of the chamber 10, the insulation plate 12, the support 14, and the susceptor 16. It is preferable that the feed line 26 be connected to the center of the electrode portion 20 of the electrostatic chuck 18.
On the upper surface of the susceptor 16, a focus ring 30 that is formed of silicon, for example, for improving the uniformity of etching is provided to surround the electrostatic chuck 18. A cylindrical inner wall member 32 formed of quartz, for example, is bonded to the side faces of the susceptor 16 and the support 14.
A refrigerant compartment 34 extending in the circumferential direction, for example, is provided inside the support 14. To this refrigerant compartment 34, refrigerant or cooling water at a predetermined temperature is supplied for circulation from an external chiller unit (not shown) via supply lines 36a and 36b. The process temperature of the semiconductor wafer W on the susceptor 16 can be controlled by the temperature of the refrigerant.
A showerhead 38, parallel to and opposed to the susceptor 16, is provided as an upper electrode of the ground potential. The showerhead 38 includes a lower electrode plate 40 having a number of gas supply holes 40a, and an electrode support 42 for supporting the electrode plate 40 in such a manner that the electrode plate 40 is attachable and detachable. A buffer chamber 44 is provided inside the electrode support 42 and has a gas inlet 44a to which a gas supply line 48 from a process gas supply 46 is connected. An insulation blocking member 49 in the form of a ring formed of alumina, for example, is air-tightly provided between the showerhead 38 and the sidewall of the chamber 10.
An exhaust outlet 50 is provided at the bottom of the chamber 10. An exhaust system 54 is connected to the exhaust outlet 50 via an exhaust tube 52. The exhaust system 54 includes a vacuum pump such as a turbo-molecular pump, capable of reducing the pressure in the plasma processing space of the chamber 10 to a desired degree of vacuum. A gate valve 56, for opening and closing the entrance through which the semiconductor wafer W is carried into the chamber 10, is attached to a sidewall of the chamber 10.
The plasma etching apparatus of the present embodiment includes three radio-frequency power supplies 58, 60, and 62 provided outside the chamber 10.
The radio-frequency power supply 58 causes the electrode portion 20 of the electrostatic chuck 18 to generate heat by resistance heating. This controls the temperature of the semiconductor wafer W on the susceptor 16 in the heating method. One output terminal of the radio-frequency power supply 58 is electrically connected to the susceptor 16 via a feed line 64, while the other output terminal is connected to the ground potential. The radio-frequency power supply 58 preferably outputs radiation of a frequency in a range from 1 to 100 kHz, for example, radio-frequency radiation of 10 kHz, with a power that is preferably variable and controllable. The feed line 64 is accommodated in an insulation sheath (not shown) extending from under the chamber 10 to the susceptor 16 through the bottom plate of the chamber 10, the insulation plate 12, and the support 14.
The radio-frequency power supply 60 is used for the application of RF bias. One output terminal of the radio-frequency power supply 60 is electrically connected to the susceptor 16 via a feed line 66, a node 68, and the feed line 64, while the other output terminal is connected to the ground potential. The radio-frequency power supply 60 preferably outputs radio-frequency radiation of a frequency in a range from 2 to 20 MHz, for example, radio-frequency radiation of 2 MHz.
The radio-frequency power supply 62 is used for the generation of plasma by radio-frequency discharge between the upper electrode 38 and the lower electrode 16. One output terminal of the radio-frequency power supply 62 is electrically connected to the upper electrode 38 via a feed line 70, while the other output terminal is connected to the ground potential. The radio-frequency power supply 62 preferably outputs radio-frequency radiation of a frequency in a range from 50 to 300 MHz, for example, radio-frequency radiation of 60 MHz. A matching section 72, for matching the output impedance of the radio-frequency power supply 62 with the load impedance may be provided in the middle of the feed line 70.
In the middle of the feed line 64, between the radio-frequency power supply 58 and the node 68, a low-pass filter (LPF) 74 is provided. This allows radio-frequency radiation for heating (10 kHz) from the radio-frequency power supply 58 to pass therethrough while cutting off radio-frequency radiation for RF bias (2 MHz) from the radio-frequency power supply 60 and radio-frequency radiation for plasma generation (60 MHz) from the radio-frequency power supply 62.
In the middle of the feed line 66, a bandpass filter (BPF) 76 is provided. This allows the radio-frequency radiation for RF bias (2 MHz) from the radio-frequency power supply 60 to pass therethrough while cutting off the radio-frequency radiation for heating (10 kHz) from the radio-frequency power supply 58 and the radio-frequency radiation for plasma generation (60 MHz) from the radio-frequency power supply 62. In the case of providing a high-pass filter (not shown) allowing the radio-frequency radiation for plasma generation (60 MHz) from the radio-frequency power supply 62 to pass between the susceptor 16 and the ground, the aforementioned bandpass filter (BPF) 76 can be replaced with a high-pass filter which only cuts off the radio-frequency radiation for heating (10 kHz) from the radio-frequency power supply 58.
A matching section (not shown), for matching the output impedance of the radio-frequency power supply 60 with the load impedance may be provided in the middle of the feed line 66, or at a point in the middle of the feed line 64 that is closer to the susceptor 16 than the node 68.
On the other hand, in the feed line 26, a low-pass filter 84 formed from a resistor 80 and a capacitor 82 is connected between the output terminal of the direct-current power supply 28 and the node 78. Additionally, a radio-frequency bypass circuit 88 is connected between the node 78 and the ground potential. The radio-frequency bypass circuit 88 is formed by a capacitor 86, for example. Moreover, a filter 90 is provided in the middle of the feed line 26 so as to be closer to the electrostatic chuck 18 than the node 78.
The filter 90 allows the direct-current voltage from the direct-current power supply 28 and the radio-frequency radiation for heating (10 kHz) from the radio-frequency power supply 58 to pass therethrough while cutting off the radio-frequency radiation for RF bias (2 MHz) from the radio-frequency power supply 60 and the radio-frequency radiation for plasma generation (60 MHz) from the radio-frequency power supply 62. The radio-frequency bypass circuit 88 has the function of cutting off the direct-current voltage from the direct-current power supply 28 while allowing the radio-frequency radiation for heating (10 kHz) from the radio-frequency power supply 58 to pass therethrough. The low-pass filter 84 has the function of allowing the direct-current voltage from the direct-current power supply 28 to pass therethrough while cutting off the radio-frequency radiation for heating (10 kHz) from the radio-frequency power supply 58.
Next, etching in this plasma etching apparatus is described. First, the gate valve 56 is opened. The semiconductor wafer W to be processed is carried into the chamber 10 and is placed on the electrostatic chuck 18. Then, etching gas (in general, a mixed gas) is introduced, at a predetermined flow rate and a predetermined flow rate ratio, into the chamber 10 from the process gas supply 46. The pressure inside the chamber 10 is then adjusted to a set pressure by the exhaust system 54. A direct-current voltage is applied by the direct-current power supply 28 to the electrode portion 20 of the electrostatic chuck 18, thereby holding the semiconductor wafer W on the electrostatic chuck 18. The radio-frequency power supply 60 supplies radio-frequency radiation for RF bias to the susceptor (lower electrode) 16 at a predetermined power. The radio-frequency power supply 62 supplies radio-frequency radiation for plasma generation to the showerhead (upper electrode) 38 with a predetermined power. Thus, the etching gas emitted from the showerhead 38 is changed into plasma by the discharge of radio-frequency radiation between the electrodes 16 and 38. Radicals or ions generated by that plasma etch the main surface of the semiconductor wafer W.
In this plasma etching apparatus, the radio-frequency power supply 58 supplies radio-frequency radiation for heating (10 kHz) at a predetermined power through the feed line 64 and the susceptor 16 to the electrode portion 20 of the electrostatic chuck 18. Since the susceptor 16 and the electrode portion 20 of the electrostatic chuck 18 are coupled by alternating-current coupling or capacity coupling via the lower dielectric portion 24 of the electrostatic chuck 18, the radio-frequency current from the radio-frequency power supply 58 flows through the lower dielectric portion 24 from the susceptor 16 to various portions of the electrode portion 20 of the electrostatic chuck 18. The radio-frequency current that flows into the various portions of the electrode portion 20, flows to the feed line 26, and flows through the feed line 26, the filter 90, and the radio-frequency bypass circuit 88 in that order. Finally, the radio-frequency current flows to the ground, i.e., the other output terminal of the radio-frequency power supply 58.
During a cycle in which the polarity of the radio-frequency radiation for heating is the opposite of the above, the radio-frequency current from the other output terminal of the radio-frequency power supply 58 enters the filter 90 through the radio-frequency bypass circuit 88, then flows through the feed line 26, and finally flows into the electrode portion 20 of the electrostatic chuck 18. The radio-frequency current that flows into the electrode portion 20 from the feed line 26, flows from the various portions of the electrode portion 20 into the susceptor 16 via the lower dielectric portion 24 due to capacity coupling, and then flows through the feed line 64 from the susceptor 16 to the output terminal of the radio-frequency power supply 58.
The radio-frequency current flowing in the aforementioned manner from the radio-frequency power supply 58 to the electrode portion 20 of the electrostatic chuck 18 causes the generation of Joule heat in the electrode portion 20. The thus generated Joule heat is transferred to the semiconductor wafer W on the electrostatic chuck 18 by thermal conduction, so as to heat the semiconductor wafer W. The amount of heat provided to the semiconductor wafer W can be controlled by varying and adjusting the output power of the radio-frequency power supply 58, thereby allowing the temperature of the semiconductor wafer W to be controlled. In order to control the process temperature of the semiconductor wafer W at a desired temperature, the present embodiment also employs a method for varying and adjusting the temperature of the refrigerant supplied from the chiller unit to the refrigerant compartment 34 of the support 14.
As described above, in the present embodiment, it is not necessary to provide a special heating arrangement, such as a heating wire, inside the susceptor 16. Instead, the radio-frequency radiation for heating is supplied to the electrode portion 20 of the electrostatic chuck 18 for holding the semiconductor wafer W on the susceptor 16, thereby heating the semiconductor wafer W to a desired temperature by Joule heat in the electrode portion 20. In addition, the feed line 64 that is used for supplying the radio-frequency radiation for RF bias from the radio-frequency power supply 60 to the susceptor 16, and the feed line 26 that is used for supplying the direct-current voltage for electrostatic absorption from the direct-current power supply 28 to the electrode portion 20 of the electrostatic chuck 18, are also used for supplying radio-frequency radiation for heating from the radio-frequency power supply 58 to the electrode portion 20 of the electrostatic chuck 18. In the case of using feed lines 64 and 26 in the aforementioned manner, the radio-frequency power supply 58 is protected against radio-frequency radiation for RF bias (2 MHz) and radio-frequency radiation for plasma generation (60 MHz) by the low-pass filter (LPF) 74. The radio-frequency power supply 60 is protected against radio-frequency radiation for heating (10 kHz) and radio-frequency radiation for plasma generation (60 MHz) by the bandpass filter (BPF) 76. The direct-current power supply 28 is protected against all the radio-frequency radiations by the filter 90 and the low-pass filter 84.
In the present embodiment, the radio-frequency radiation for plasma generation is applied to the upper electrode (showerhead) 38, and the radio-frequency radiation for RF bias is applied to the lower electrode (susceptor) 16. However, the radio-frequency radiation for plasma generation or RF bias may be applied to the upper or lower electrode in a given manner, and various manners can be employed. For example, without applying the radio-frequency radiation for plasma generation to the upper electrode 38, two types of radio-frequency radiation, i.e., the radio-frequency radiation for RF bias and that for plasma generation, or one type of radio-frequency radiation for RF bias and plasma generation, can be applied to the lower electrode 16. Alternatively, the radio-frequency radiation for plasma generation can be applied to the upper electrode 38 while no RF bias is applied to the lower electrode 16, i.e., a self-bias method is employed.
In the second embodiment, a disc-like susceptor lower electrode 92 formed of aluminum, for example, is arranged at the bottom of the chamber 10 via the insulation plate 12. A susceptor 94 formed of a dielectric material such as ceramic, for example, is provided on the susceptor lower electrode 92. A susceptor upper electrode 96, in the form of a plate or sheet, is provided inside the susceptor 94 so as to be close to the upper surface (substrate-placed surface) of the susceptor 94. The material for the susceptor upper electrode 96 is preferably high-melting point metal such as tungsten, molybdenum, or nickel.
A radio-frequency power supply 98 causes the susceptor 94, formed of a dielectric material, to generate heat by radio-frequency heating. This allows control of the temperature of the semiconductor wafer W on the susceptor 94 in the heating method. One output terminal of the radio-frequency power supply 98 is electrically connected via a feed line 100 to the susceptor upper electrode 96. The other output terminal is electrically connected to the susceptor lower electrode 92 via the ground. The radio-frequency power supply 98 preferably outputs radio-frequency radiation of a frequency in a range from 1 MHz to 200 MHz, for example, radiation of 10 MHz. When radio-frequency radiation from the radio-frequency power supply 98 is applied across the susceptor upper electrode 96 and the susceptor lower electrode 92, the inside of the susceptor 94 generates heat due to dielectric loss from the radio-frequency electric field formed between the electrodes 96 and 92. The semiconductor wafer W on the susceptor 94 is then heated by thermal conduction. The amount of heat inside of the susceptor 94 can be controlled in a given manner by varying and controlling the output power of the radio-frequency power supply 98. Accordingly, the temperature of the semiconductor wafer W can be controlled to be at a given temperature.
In the present embodiment, the direct-current voltage from the direct-current power supply 28 may be applied to the susceptor upper electrode 96 through a feed line 102, a node 104, and the feed line 100 in order to hold the semiconductor wafer W on the susceptor 94 with an electrostatic absorbing force. In this case, a high-pass filter (HPF) or bandpass filter 106 may be provided between the node 104 and the radio-frequency power supply 98 and in the middle of the feed line 100. The filter allows radio-frequency radiation from the radio-frequency power supply 98 to pass therethrough while cutting off direct-current voltage from the direct-current power supply 28 and radio-frequency radiation from the radio-frequency power supply 62. Moreover, a filter 108 may be provided in the middle of the feed line 102 for allowing the direct-current voltage from the direct-current power supply 28 to pass therethrough while cutting off the radio-frequency radiation from each of the radio-frequency power supplies 98 and 62.
In the third embodiment, a coil 110 is provided under the susceptor 94, concentrically with the susceptor 94 or the susceptor electrode 96. A radio-frequency power supply 112 causes the electrode 96 inside the susceptor 94 to generate heat by radio-frequency heating in order to control the temperature of the semiconductor wafer W on the susceptor 94 in the heating method. The radio-frequency power supply 112 is electrically connected at its output terminal to the coil 110 via a feed line 114 and preferably outputs radio-frequency radiation of a frequency in a range from 1 kHz to 10 MHz, for example, radiation of 2 kHz. When the radio-frequency current from the radio-frequency power supply 112 flows through the coil 110, a radio-frequency electromagnetic field J formed by the coil 110 penetrates the susceptor electrode 96, causing the generation of an eddy current in the susceptor electrode 96. The thus generated eddy current causes the susceptor electrode 96 to generate heat, so that the semiconductor wafer W on the susceptor 94 is heated by thermal conduction. The amount of heat in the susceptor electrode 96 can be arbitrarily controlled by varying and controlling the output power of the radio-frequency power supply 112, allowing the temperature of the semiconductor wafer W to be controlled at a given temperature.
In the present embodiment, in order to hold the semiconductor wafer W on the susceptor 94 with an electrostatic absorbing force, the direct-current voltage from the direct-current power supply 28 may be applied to the susceptor upper electrode 96 via a feed line 116. Radio-frequency radiation for RF bias from the radio-frequency power supply 60 may be applied to the susceptor upper electrode 96 via a feed line 118, a node 117, and the feed line 116. Preferably, a filter 120 may be provided in the middle of the feed line 114. The filter 120 allows radio-frequency radiation for heating from the radio-frequency power supply 112 to pass therethrough while cutting off radio-frequency radiation for RF bias from the radio-frequency power supply 60 and that for plasma generation from the radio-frequency power supply 62. A high-pass filter (HPF) 122 may be provided in the middle of the feed line 118. This filter 122 allows radio-frequency radiation for RF bias from the radio-frequency power supply 60 to pass therethrough while cutting off direct-current voltage from the direct-current power supply 28.
In the second and third embodiments described above, the radio-frequency radiation for plasma generation or RF bias can be applied to the upper or lower electrode in a given manner and various modifications can be made. In the present invention, the feed line can be in any form, for example, in the form of a cable or a conducting bar.
The above description can also be applied to various plasma processing apparatuses, and particularly, an apparatus employing a parallel-plate type plasma generation method with capacity-coupling as described above is an example. The present invention can also be applied to other plasma generation methods, for example, a magnetron method and an ECR (Electron Cyclotron Resonance) method. Moreover, the type of plasma process is not limited to etching. The present invention can also be applied to any other plasma processes, for example, CVD (Chemical Vapor Deposition), oxidation, and sputtering. In addition, an object to be processed by the plasma process is not limited to a semiconductor wafer. For example, a glass substrate or a substrate for an LCD (Liquid Crystal Display) may be used as the object to be processed. Furthermore, the present invention can be also applied to a processing apparatus other than plasma processing apparatus.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-427020 | Dec 2003 | JP | national |
