JP2006100630A - Apparatus and method of plasma processing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of plasma processing in which reliability is high and a throughput is high in the detachment and attachment of a wafer from and to a substrate electrode. <P>SOLUTION: The method of plasma processing in an apparatus of plasma processing includes steps of: lowering the output of a high frequency power (RF) applied to a material to be processed to the output in which an etching treatment is not advanced at the time of ending a treatment (T1); setting a phase difference between a high frequency wave applied to the material to be processed and a high frequency wave applied to an antenna electrode at "0 degree"; turning off an ESC power supply after a cooling gas discharge is ended (T2); and discharging a stored charge to the material to be processed (T3). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plasma processing apparatus, and more particularly to a plasma processing apparatus and a plasma processing method suitable for performing a surface treatment of a semiconductor element or the like using plasma.

  When performing an etching process using a plasma processing apparatus, the process gas is ionized and activated to speed up the process, and a high frequency bias power is supplied to the material to be processed so that ions are incident vertically. High-precision etching processing such as anisotropic shape is realized. In the conventional plasma processing apparatus, the high frequency applied to the substrate electrode and the high frequency applied to the antenna electrode facing the substrate electrode are controlled independently of each other (see, for example, Patent Document 1). In general, the energy of ions incident on the material to be processed is determined by the self-bias potential generated by the bias power supplied to the material to be processed, and the self-bias potential is the ratio of the effective earth area to the electrode area in the processing chamber. (For example, refer nonpatent literature 1). Therefore, due to the increased plasma potential, the plasma diffuses to the outer peripheral portion and is not sufficiently confined in the processing chamber, and the amount of foreign matter generated increases due to sputtering on the inner wall of the vacuum vessel and attachment / detachment of reaction products. There was a possibility.

  In response to these problems, it is possible to arbitrarily control the self-bias potential of both electrodes by applying a phase-controlled bias voltage having the same frequency to the substrate electrode and the antenna electrode (see, for example, Patent Document 2). ).

In addition, the wafer, which is the material to be processed, is electrostatically adsorbed on the electrostatic adsorption film on the substrate electrode, introduces a rare gas to the backside of the wafer, increases the heat transfer efficiency with the substrate electrode, and supplies bias power to the wafer. However, the temperature is adjusted. However, in the semiconductor manufacturing process, various films are often formed on the back surface of the wafer from the process, and it has been necessary to make the desorption characteristics more reliable.
JP 09-321031 A JP 2002-174766 A B. Glow Discharge Processes by Champman (John Wiley & Sons, Inc., New York, 1980)

  In the conventional semiconductor manufacturing apparatus described above, in order to improve the yield during semiconductor manufacturing, the desorption to the substrate electrode of the wafer is required to be increased in speed and reliability from the viewpoint of improving throughput and yield. .

  It is an object of the present invention to provide a plasma processing method and a plasma processing apparatus that have high reliability and high throughput for desorption of a wafer to a substrate electrode.

  In the plasma processing apparatus of the present invention, the self-bias potential of the wafer is adjusted by controlling the phase of the high frequency applied to the substrate electrode and the high frequency applied to the antenna electrode facing the substrate electrode, and the wafer is forcibly charged. By discharging the charged charges, it is possible to reliably perform the desorption characteristic of the wafer to the substrate electrode.

That is, the present invention relates to a processing chamber to which an evacuation apparatus is connected and whose inside can be decompressed, a gas supply device for supplying gas into the processing chamber, a substrate electrode on which a processing material can be placed, and a processing material to be adsorbed on the substrate electrode An electrostatic adsorption film for controlling the temperature of the material to be processed, a cooling gas introduction mechanism, an antenna electrode for radiating electromagnetic waves for generating plasma facing the substrate electrode, a high-frequency power source and an antenna connected to the substrate electrode A plasma processing apparatus comprising a high-frequency power source connected to an electrode and a control means for controlling the entire processing apparatus,
It has means for controlling the phase difference between the high frequency supplied to the substrate electrode and the high frequency supplied to the antenna electrode, and has means for discharging the charge accumulated in the material to be processed by controlling the phase difference at the end of processing. Features.

  Further, the present invention is a means for controlling the phase in the plasma processing apparatus, wherein the control means reduces the output of the high frequency power applied to the material to be processed to an output at which the etching process does not proceed after completion of cooling gas exhaustion. The means is a means for setting the phase difference between the high frequency applied to the material to be processed and the high frequency applied to the antenna electrode to 0 degree, and further, an adsorption force monitor for monitoring the adsorption force between the material to be processed and the substrate electrode The adsorption force monitor is a means for measuring the adsorption force by measuring the leakage current of the electrostatic adsorption film.

  The present invention further comprises a pusher pin for raising the material to be treated and a pressure / displacement sensor for detecting the electrostatic adsorption pressure and the displacement of the pusher pin, and the pusher pin is brought into close contact with the material to be treated. Further, the adsorption force is measured by a pressure / displacement sensor.

  The present invention relates to a processing chamber to which an evacuation device is connected and whose inside can be decompressed, a gas supply device for supplying gas to the processing chamber, a substrate electrode on which a processing material can be placed, and a processing material to be adsorbed on the substrate electrode Electrostatic adsorption film, cooling gas introduction mechanism for controlling the temperature of the material to be processed, antenna electrode for radiating electromagnetic waves for generating plasma opposed to the substrate electrode, high frequency power source connected to the substrate electrode, and antenna electrode Connected high-frequency power supply, control means for controlling the entire processing apparatus, high-frequency power supply connected to the substrate electrode and means for controlling the high-frequency phase applied to the high-frequency power supply connected to the antenna electrode, phase control at the end of processing A means for releasing the charge accumulated in the material to be processed, a pusher pin for raising the material to be processed, and an adsorption force monitor for monitoring the adsorption force between the material to be processed and the substrate electrode A plasma processing method in a plasma processing apparatus, wherein a charge accumulated in a processing material is discharged by controlling a phase difference between a high frequency applied to the processing material and a high frequency applied to the antenna electrode at the end of processing. And

  Further, the present invention provides the above plasma processing method, wherein after the cooling gas exhaust is finished, the output of the high frequency power applied to the material to be processed is reduced to an output at which the etching process does not proceed, and the high frequency applied to the material to be processed and the antenna electrode are reduced. An adsorption force monitor is provided on the substrate electrode to release the charge accumulated in the material to be processed with a phase difference from the applied high frequency of 0 degree and to monitor the adsorption force between the material to be processed and the substrate electrode. It is characterized in that the adsorption force is measured by measuring the leakage current of the electrostatic adsorption film.

  Further, the present invention provides the above plasma processing method, wherein the adsorption force monitor includes a pusher pin, an electrostatic adsorption pressure, and a pressure / displacement sensor that detects displacement of the pusher pin, the pusher pin is brought into close contact with the workpiece, The adsorption force is measured by a pressure / displacement sensor.

  The present invention adjusts the self-bias potential of the wafer by controlling the phase of the bias applied to each of the electrodes opposed to the substrate electrode, and forcibly discharges the charge charged on the wafer. It is possible to perform the desorption property to the electrode with high reliability. Therefore, it is possible to improve the plasma processing reliability and throughput.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a longitudinal sectional view of an etching apparatus which is an embodiment of a plasma processing apparatus to which the present invention is applied. In the etching apparatus, a processing chamber 104, a dielectric window 102 (for example, made of quartz), and an antenna electrode 103 (for example, made of Si) are installed and sealed on an upper portion of a vacuum vessel 101 whose upper portion is opened, thereby processing chamber 105. Form. The upper electrode 103 has a porous structure for flowing an etching gas, and is connected to the gas supply device 107. Further, a vacuum exhaust device (not shown) is connected to the vacuum vessel 101 via a vacuum exhaust port 106.

  A high frequency power source 108 (for example, a frequency of 100 MHz to 450 MHz) and an antenna bias power source 113 are connected to the upper portion of the antenna electrode 103 via a coaxial line 111, a filter 110, a matching unit 109, and a matching unit 112. The antenna bias power supply 113 (for example, a frequency of 400 kHz to 4 MHz) can control oscillation by an external trigger signal.

  In addition, the substrate electrode 115 on which the processing object 116 can be placed is installed under the vacuum vessel 101 and connected to the substrate bias power source 119 via the matching unit 118. In addition, the substrate electrode 115 has an electrostatic adsorption film (not shown) on the upper portion, and can supply a cooling gas between the workpiece 116 and the electrostatic adsorption film. The pressure of these cooling gases can be controlled to an arbitrary pressure. The substrate bias power source 119 can control oscillation by an external trigger signal. In addition, an electrostatic adsorption DC power source (electrostatic chuck (ESC) power source) 123 is connected to the substrate electrode 115 via a filter 117 in order to electrostatically attract the material 116 to be processed.

  The antenna bias power supply 113 and the substrate bias power supply 119 are connected to the phase controller 120 so that the phase of the high frequency output from the antenna bias power supply 113 and the substrate bias power supply 119 can be controlled. . The phase can be set to a desired phase based on the signals from the phase detection probes 121 and 122. Here, the phase was mainly 180 ° ± 45 °.

  In the plasma processing apparatus configured as described above, the inside of the processing chamber 105 is depressurized by a vacuum exhaust device (not shown), and then an etching gas is introduced into the processing chamber 105 by the gas supply device 107 and adjusted to a desired pressure. . The high frequency power oscillated from the high frequency power supply 108 propagates through the coaxial line 111 and is introduced into the processing chamber 105 through the upper electrode 103 and the dielectric window 102. A matching unit 109 is connected between the high-frequency power source 108 and the coaxial line 111 and operates to efficiently supply the high-frequency power output from the high-frequency power source 108 into the processing chamber 105. In addition, high-density plasma is generated in the processing chamber 105 by the interaction with the magnetic field formed by the magnetic field generating coil 114 (for example, a solenoid coil). In particular, when a magnetic field intensity (for example, 160 G) that causes electron cyclotron resonance is formed in the processing chamber, high-density plasma can be generated efficiently.

  High frequency power from the antenna bias power supply 113 is supplied to the antenna electrode 103 via the matching unit 112 and the coaxial line 111. At this time, a filter 110 is installed between the matching unit 109 and the matching unit 112 and the coaxial line 111, and the filter 110 efficiently inputs high-frequency power output from the high-frequency power source 108 toward the coaxial line 111. The high-frequency power output from the antenna bias power supply 113 acts to efficiently input the coaxial bias 111 toward the coaxial line 111.

  In addition, the material to be processed 116 placed on the substrate electrode 115 is supplied with high frequency power from the plate bias power source 119 via the matching unit 118 and is subjected to surface treatment (for example, etching treatment). The substrate electrode 115 is connected to a DC power source for electrostatic attraction (electrostatic chuck (ESC) power source) 123 so that the workpiece 116 can be adsorbed. A filter 117 is connected between the electrostatic attraction DC power source 123 and the matching unit 118 so that the power output from the substrate electrode 115 and the electrostatic attraction DC power source 123 is efficiently input to the substrate electrode 115. Works.

  Further, the phase and power supply controller 124 has a structure capable of controlling the phase and power supply output in a sequence determined based on the discharge start and etching end signals.

  FIG. 2 shows the relationship between the Vdc / Vpp ratio indicating the self-bias potential of the wafer as the material 116 to be processed and the bias phase difference. Here, Vdc is a value obtained by subtracting ½ of Vpp (peak-to-peak voltage) of the bias voltage from the maximum value of the bias voltage. The Vdc / Vpp ratio has a minimum value of -0.45 at a phase difference of 180 degrees, and a maximum value of about -0.15 at a phase difference of 0 degrees. In addition, this measurement result is an experimental result obtained when the electrode distance between the upper antenna electrode 103 and the substrate electrode 115 is about 70 mm wide. When the same measurement is performed at about 20 mm to 40 mm where the electrode distance is narrow, Similarly, when the phase difference is 180 degrees, the Vdc / Vpp ratio is about −0.45, but when the phase difference is 0 degree, the Vdc / Vpp ratio is about 0. This is because the function of the side wall as a ground decreases with a narrow electrode interval. FIG. 2 shows that the self-bias potential of the wafer can be arbitrarily controlled by changing the phase difference.

  FIG. 3 shows temporal changes in RF power, phase difference, wafer back surface cooling gas pressure, electrostatic adsorption power supply (ESC) voltage, and electrostatic adsorption force between the wafer and the electrostatic adsorption film at the end of the etching process. . The time until the time T1 is the actual etching processing time, and the time after that is the time for detaching the wafer adsorbed on the electrostatic adsorption film. At times T1 to T2, the back surface cooling gas is exhausted, and the wafer bias (RF) output is decreased to a weak output that does not allow the etching to proceed with the phase difference 180. After the end of exhaust of the back surface cooling gas (time T2), the output voltage of the electrostatic adsorption power supply (ESC) is set to 0 V and the phase difference is set to 0 degree. Then, the electric charge accumulated on the electrostatic adsorption film and the back surface of the wafer is discharged through the ESC power supply, and at the same time, the phase difference is set to 0 degree, so that the wafer potential is forced to 0 V. Is done. Therefore, the attractive force between the wafer and the substrate electrode decreases rapidly (time T3). Thereafter, the bias power is turned off at time T4, the source power source for plasma generation is turned off at time T5, and all the processes are completed.

  Next, the configuration of the suction force monitor will be described with reference to FIGS. 4 (a) and 4 (b). The adsorption force monitor of FIG. 4A includes an electrostatic adsorption film 130 provided on the surface of the substrate electrode 115, a pusher pin 131 for raising the wafer, a sensor 132 such as a pressure / displacement meter, and a pusher pin drive mechanism 134. An ammeter 135, an RF power source 119, and an ESC power source 123. In the configuration of FIG. 4 (a), the leakage current of the electrostatic adsorption film 130 changes depending on the voltage applied between the films. Therefore, the adsorption force can be measured by measuring the leakage current with an ammeter 135. is there. 4B includes an electrostatic adsorption film 130 provided on the surface of the substrate electrode 115, a pusher pin 131 for raising the wafer, a sensor 132 such as a pressure / displacement meter, and a control unit 133. A pusher pin drive mechanism 134, an RF power source 119, and an ESC power source 123. 4B, the pusher pins 131 for raising the wafer are brought into close contact with the wafer after the processing is completed, a certain pressure is applied to the pusher pins 131, and the pressure change and displacement are monitored by the sensor 132. It is possible to measure the adsorption force. When any one of these monitors and control devices is used, it is possible to detect the time T3 shown in FIG. Therefore, when the adsorption force monitor is used, the time T4 can be set at the same time as the time T3, and the throughput can be improved.

  Although the etching apparatus has been described in the above embodiment, the same effect can be obtained in other plasma processing apparatuses that supply high-frequency power to the substrate electrode, such as an ashing apparatus and a plasma CVD apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS The longitudinal cross-sectional view which shows the etching apparatus which is the 1st Example using this invention. The characteristic view which shows the relationship between a self-bias voltage and a phase difference. The time diagram which shows time changes, such as each parameter output at the time of completion | finish of an etching. The longitudinal cross-sectional view which shows the structure of an adsorption power monitor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Vacuum container 102 ... Dielectric window 103 ... Antenna electrode 104 ... Processing container 105 ... Processing chamber 106 ... Vacuum exhaust port 107 ... Gas supply apparatus 108 ... High frequency power supply 109 ... Matching device 110 ... Filter 111 ... Coaxial line 112 ... Matching device 113 ... Antenna bias power source 114 ... Magnetic field generating coil 115 ... Substrate electrode 116 ... Material to be processed 117 ... Filter 118 ... Matching device 119 ... Substrate bias power source 120 ... Phase controller 121, 122 ... Phase detection probe 123 ... DC for electrostatic adsorption Power supply 124 ... Phase and power supply controller? ? ?
DESCRIPTION OF SYMBOLS 130 ... Electrostatic adsorption film 131 ... Pusher pin 132 ... Sensor 133 ... Control part 134 ... Pusher pin drive mechanism 135 ... Ammeter

Claims (9)

A processing chamber to which a vacuum exhaust device is connected and the inside of which can be depressurized, a gas supply device for supplying gas to the processing chamber, a substrate electrode on which a processing material can be placed, and electrostatic adsorption for adsorbing the processing material on the substrate electrode Cooling gas introduction mechanism for controlling the temperature of the film, the material to be treated, an antenna electrode for radiating electromagnetic waves for generating plasma facing the substrate electrode, a high frequency power source connected to the substrate electrode, and a high frequency connected to the antenna electrode A plasma processing apparatus comprising control means for controlling the power source and the entire processing apparatus,
Means for controlling the phase difference between the high frequency supplied to the substrate electrode and the high frequency supplied to the antenna electrode;
A plasma processing apparatus comprising means for discharging charges accumulated in a material to be processed by controlling a phase difference at the end of processing.   2. The plasma processing apparatus according to claim 1, wherein the control means is means for reducing the output of the high-frequency power applied to the material to be processed to an output at which the etching process does not proceed after the cooling gas exhaust, and the means for controlling the phase. A plasma processing apparatus, characterized in that the phase difference between the high frequency applied to the material to be processed and the high frequency applied to the antenna electrode is 0 degree.   3. The plasma processing apparatus according to claim 1, further comprising an adsorption force monitor that monitors an adsorption force between the material to be processed and the substrate electrode.   4. The plasma processing apparatus according to claim 3, wherein the adsorption force monitor is means for measuring the adsorption force by measuring a leakage current of the electrostatic adsorption film.   4. The plasma processing apparatus according to claim 3, further comprising a pusher pin for raising the workpiece, a pressure / displacement sensor for detecting electrostatic adsorption pressure and displacement of the pusher pin, the pusher pin being in close contact with the workpiece, A plasma processing apparatus that measures adsorption force with a displacement sensor. A processing chamber to which a vacuum exhaust device is connected and the inside of which can be depressurized, a gas supply device for supplying gas to the processing chamber, a substrate electrode on which a processing material can be placed, and electrostatic adsorption for adsorbing the processing material on the substrate electrode Cooling gas introduction mechanism for controlling the temperature of the film, the material to be treated, an antenna electrode for radiating electromagnetic waves for generating plasma facing the substrate electrode, a high frequency power source connected to the substrate electrode, and a high frequency connected to the antenna electrode Power supply, control means for controlling the entire processing apparatus, means for controlling the phase of the high frequency applied to the high frequency power supply connected to the substrate electrode and the high frequency power supply connected to the antenna electrode, and processing by controlling the phase at the end of processing A plasma treatment comprising means for discharging the charge accumulated in the material, a pusher pin for raising the material to be treated, and an adsorption force monitor for monitoring the adsorption force between the material to be treated and the substrate electrode. A plasma processing method in the apparatus,
A plasma processing method for discharging charges accumulated in a material to be processed by controlling a phase difference between the high frequency applied to the material to be processed and the high frequency applied to the antenna electrode at the end of the processing.   7. The plasma processing method according to claim 6, wherein after exhausting the cooling gas, the output of the high frequency power applied to the material to be processed is reduced to an output at which the etching process does not proceed, and is applied to the high frequency applied to the material to be processed and the antenna electrode. A plasma processing method, wherein a charge accumulated in a material to be processed is discharged with a phase difference from a high frequency of 0 degree.   8. The plasma processing method according to claim 6, wherein an adsorption force monitor that monitors an adsorption force between the material to be processed and the substrate electrode measures a leakage current of an electrostatic adsorption film provided on the substrate electrode. A plasma processing method characterized by measuring an adsorption force.   9. The plasma processing method according to claim 8, wherein the adsorption force monitor comprises a pusher pin, a pressure / displacement sensor for detecting electrostatic adsorption pressure and displacement of the pusher pin, the pusher pin is brought into close contact with the material to be treated, and pressure / displacement is further provided. A plasma processing method, wherein the adsorption force is measured by a sensor.

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