JP3974475B2 - Electrostatic chuck apparatus and substrate processing method using the apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic chuck apparatus for attracting and holding a substrate such as a semiconductor wafer, and more particularly to an electrostatic chuck apparatus that realizes rapid adsorption and detachment of a substrate and no vibration of the substrate.
[0002]
[Prior art]
As a method for attracting and holding a substrate such as a semiconductor wafer in a semiconductor manufacturing apparatus or the like, a so-called electrostatic chuck that attracts and holds a substrate by electrostatic force has been conventionally used. These have a single electrode and apply some voltage to the ground potential to the electrode, while the substrate is grounded via plasma etc., which occurs between the substrate and the electrode A so-called monopole-type electrostatic chuck that uses electrostatic force, or a pair of or a plurality of pairs of electrodes, a voltage is applied between the electrodes, and charges of opposite polarity induced on the substrate and the electrodes There is a so-called dipole type electrostatic chuck that uses the electrostatic force generated between the two.
[0003]
The voltage applied to the single electrode or a pair or a plurality of pairs of electrodes may be a DC voltage or a single-phase AC voltage.
[0004]
Examples of devices of this type include JP-A-7-273177, JP-A-9-213780, JP-A-6-244271, and the like.
[0005]
[Problems to be solved by the invention]
However, the conventional technique has the following problems. First, in the method of applying a DC voltage, in both the monopole type and the dipole type, charges are accumulated on the back surface of the substrate while the substrate is adsorbed, and the accumulation of this charge makes it difficult to remove the substrate. In particular, when the substrate is in contact with plasma as in a plasma processing apparatus, the substrate has a negative potential with respect to the ground potential through the plasma. The charge accumulation process becomes more complicated. Conventionally, as a method for removing the accumulated electric charge, for example, as shown in Japanese Patent Application Laid-Open No. 7-273177 and Japanese Patent Application Laid-Open No. 9-213780, a process of applying a reverse voltage called neutralization is performed. is doing. However, in any case, there is a problem that the throughput of the apparatus is lowered due to the process of static elimination.
[0006]
On the other hand, the method of applying a single-phase AC voltage as disclosed in Japanese Patent Laid-Open No. 6-244271 does not accumulate charges on the back surface of the substrate, and therefore requires a charge removal process when the substrate is detached. It is a way not to. However, at the moment when the voltage becomes zero, the adsorption force becomes zero, and as a result, there is a problem that the substrate vibrates.
[0007]
It is an object of the present invention to eliminate the need for a static elimination process when the substrate is detached as in the case of applying the DC voltage, and to vibrate the substrate as in the case of applying the single-phase AC voltage. It is an object of the present invention to provide an electrostatic chuck apparatus and a substrate processing method using the apparatus.
[0008]
[Means for Solving the Problems]
As a means for solving the problems of the conventional technique, an electrostatic chuck device that applies an n-phase AC voltage of n = 2 or more is proposed. FIG. 1 is a drawing showing a basic configuration when a three-phase AC voltage is applied when n = 3. In FIG. 1, a substrate 5 is placed on a sample stage 9 made up of an R-phase electrode 1, an S-phase electrode 2, a T-phase electrode 3, and an insulator 4. Thus, the three-phase AC power source 6 is connected. When the switch 11 is turned on and off, the substrate 5 is attracted and detached.
[0009]
FIG. 3 shows temporal changes in voltage applied between the R-phase electrode 1, the S-phase electrode 2, and the T-phase electrode 3 and the substrate 5. Further, FIG. 4 shows a change with time of the adsorption force applied between the substrate 5 and the sample stage 9. As shown in FIG. 4, the adsorption force applied to the substrate 5 and the sample stage 9 does not become zero, and as a result, the substrate does not vibrate.
[0010]
In addition, since the DC component of the voltage applied to the electrodes 1, 2, and 3 is zero, charges are not accumulated on the back surface of the substrate as in the case of applying a DC voltage. Further, even when the substrate and the plasma are in contact with each other as in the plasma processing apparatus and the substrate has a negative potential with respect to the ground potential, the primary side and the secondary side of the three-phase AC power source 6 are insulated, and the electrodes 1, 2, 3 is maintained at a floating potential with respect to the ground potential, so that no DC voltage is generated between the substrate 5 and the electrodes 1, 2 and 3, and there is no charge on the back surface of the substrate. There is no accumulation. As a result, the neutralization process as in the conventional method is not required, and the substrate is quickly adsorbed and detached by turning the switch 11 on and off.
[0011]
That is, by applying a three-phase AC voltage, it is possible to realize an electrostatic chuck that does not require static elimination processing, realizes quick substrate adsorption and detachment, and does not vibrate the substrate.
[0012]
The above effect can be similarly obtained when an n-phase AC voltage of n = 4 or more is applied. FIG. 2 is a diagram showing a basic configuration when a four-phase AC voltage is applied when n = 4.
[0013]
In addition, the above effect can be obtained in the same manner when a two-phase AC voltage of n = 2 is applied. FIG. 15 is a diagram illustrating a basic configuration in the case of applying a two-phase AC voltage when n = 2. FIG. 16 is a diagram showing temporal changes in the R-phase voltage and the S-phase voltage of the two-phase AC power supply 19. By shifting the phase of the R-phase voltage and the S-phase voltage by 90 °, the adsorption force applied to the substrate 5 and the sample stage 9 does not become zero, and as a result, the substrate does not vibrate.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 5 shows an embodiment of the electrostatic chuck device in the present invention when a three-phase AC voltage is applied when n = 3. The substrate 5 is placed on a sample stage 9 composed of an R-phase electrode 1, an S-phase electrode 2, a T-phase electrode 3, and an insulator 4. 5 shows an example in which the electrodes 1, 2, and 3 are covered with the insulator 4 on the mounting surface of the substrate 5. However, the back surface of the substrate 5 is covered with the insulator like a liquid crystal substrate. In this case, the electrodes 1, 2, and 3 may be exposed on the mounting surface of the substrate 5. As the voltage and frequency applied to the electrodes 1, 2, and 3, the optimum voltage and frequency are selected depending on the material of the insulator 4, the material of the substrate, and the like. FIG. 5 shows the case where the effective value of the voltage applied to the electrodes 1, 2, and 3 is 400 V, and the frequency is 50 Hz or 60 Hz. A commercial three-phase AC power supply 13 is connected to the R-phase electrode 1, the S-phase electrode 2, and the T-phase electrode 3 via a transformer 10, a switch 11, and an overcurrent protector 12. In FIG. 5, the transformer 10 shows an example of Δ-Y connection, but this may be any of Δ-Δ connection, Y-Δ connection, and YY connection. The winding ratio of the transformer 10 is 1: 2 so that the effective value of the secondary phase voltage is 400V. When the voltage applied to the electrodes is different or when the connection of the transformer 10 is different, the turns ratio must be set to match the turn ratio. The frequency of the AC voltage to be applied is 50 Hz or 60 Hz supplied as a commercial power source. In the transformer 10, the primary side and the secondary side are insulated, and even if the substrate 5 becomes a negative potential with respect to the ground potential via the plasma in a plasma processing apparatus or the like, the transformer 10 is not connected between the substrate 5 and the electrodes 1, 2, and 3. In this case, no DC voltage is generated and no charge is accumulated. By turning the switch 11 on and off, the substrate is adsorbed and detached.
[0015]
FIG. 6 is a drawing showing a reference example not included in the present invention of an electrostatic chuck device in the case of applying a three-phase AC voltage when n = 3. In FIG. 6, when the output command 15 of the inverter 14 is turned on and off, the substrate is attracted and detached. By changing the command value of the voltage command 16 and the frequency command 17 from the controller 18 to the inverter 14, the three-phase AC voltage and the frequency applied between the electrodes 1, 2, 3 and the substrate 5 are changed. Can be easily changed.
[0016]
FIG. 7 is a plan view showing a reference example not included in the present invention of the sample stage 9 in the electrostatic chuck apparatus in the case of applying a three-phase AC voltage when n = 3. The ratio of the area ratios of the R-phase electrode 1, the S-phase electrode 2, and the T-phase electrode 3 is set to 1.
[0017]
8, FIG. 9, and FIG. 10 are plan views showing a reference example not included in the present invention of the sample stage 9 in the electrostatic chuck apparatus in the case of applying a three-phase AC voltage when n = 3. The ratio of the area ratios of the R-phase electrode 1, the S-phase electrode 2, and the T-phase electrode 3 is set to 1.
[0018]
11 and 13 are views showing an embodiment of a substrate processing method using an electrostatic chuck device. FIG. 11 is a diagram showing a substrate processing apparatus in this embodiment. In FIG. 11, the sample stage 9 is installed in the vacuum container 20, and the substrate 5 is placed on the sample stage 9. A process gas 21 and a microwave power 24 are introduced into the vacuum container, and a plasma 23 is generated. FIG. 13 is a flowchart showing a substrate processing method in this embodiment. After the substrate 5 is placed on the sample table 9 in the procedure 41, the substrate 5 is adsorbed on the sample table 9 in the procedure 42. After the substrate 5 is processed by the procedure 44, the substrate 5 is detached from the sample stage 9 in the procedure 46, and the substrate 5 is unloaded in the procedure 47.
[0019]
The electrostatic chuck apparatus according to the present invention can be applied to a method other than the above-described substrate processing method using plasma. FIG. 12 and FIG. 14 are diagrams showing a reference example not included in the present invention of the substrate processing method using the electrostatic chuck device. FIG. 12 is a diagram showing a substrate processing apparatus in a reference example not included in the present invention . The sample stage 9 is installed in the vacuum container 20, and the substrate 5 is placed on the sample stage 9. A process gas 21 is introduced into the vacuum vessel. FIG. 14 is a flowchart showing a substrate processing method when the apparatus shown in FIG. 12 is used. After the substrate 5 is placed on the sample stage 9 in the procedure 51, the substrate 5 is adsorbed on the sample stage 9 in the procedure 52. After the substrate 5 is processed by the procedure 54, the substrate 5 is detached from the sample stage 9 in the procedure 56, and the substrate 5 is unloaded in the procedure 57.
[0020]
【The invention's effect】
The electrostatic chuck device of the present invention does not accumulate charges on the back surface of the substrate as in the case of applying a DC voltage by applying an n-phase AC voltage of n = 2 or more, and also has a single-phase AC voltage. An electrostatic chuck device that does not require neutralization processing, realizes quick substrate adsorption and detachment, and does not vibrate the substrate, because the adsorption force does not become zero as in the case of applying Can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a basic configuration when a three-phase AC voltage is applied when n = 3.
FIG. 2 is a diagram showing a basic configuration when a four-phase AC voltage is applied when n = 4.
FIG. 3 is a diagram illustrating a change with time of a voltage applied between electrodes 1, 2, 3 and a substrate 5 when a three-phase AC voltage is applied when n = 3.
FIG. 4 is a diagram showing a change with time of an adsorption force applied between a substrate 5 and a sample stage 9 when a three-phase AC voltage is applied when n = 3.
FIG. 5 shows an example of an electrostatic chuck device when a three-phase AC voltage is applied when n = 3.
FIG. 6 is a reference example not included in the present invention of an electrostatic chuck device in the case of applying a three-phase AC voltage when n = 3.
FIG. 7 is a plan view showing a reference example not included in the present invention of the sample stage 9 in the electrostatic chuck device in the case of applying a three-phase AC voltage when n = 3.
FIG. 8 is a plan view showing a reference example not included in the present invention of the sample stage 9 in the electrostatic chuck device in the case of applying a three-phase AC voltage when n = 3.
Figure 9 is a plan view showing a reference example not included in the present invention the sample stage 9 of the electrostatic chuck apparatus when applying the three-phase AC voltage in the case of n = 3.
FIG. 10 is a plan view showing a reference example not included in the present invention of the sample stage 9 in the electrostatic chuck device in the case of applying a three-phase AC voltage when n = 3.
FIG. 11 shows an embodiment of a substrate processing apparatus using an electrostatic chuck device.
FIG. 12 is a reference example not included in the present invention of a substrate processing apparatus using an electrostatic chuck device;
FIG. 13 is a flowchart showing one embodiment of a substrate processing method using an electrostatic chuck device.
FIG. 14 is a flowchart showing a reference example not included in the present invention of a substrate processing method using an electrostatic chuck device;
FIG. 15 is a diagram showing a basic configuration in the case of applying a two-phase AC voltage when n = 2.
FIG. 16 is a diagram showing temporal changes in the R-phase voltage and the S-phase voltage of the two-phase AC power supply when applying a two-phase AC voltage when n = 2.

Claims (4)

In the electrostatic chuck device for applying an AC voltage, the AC voltage is an n-phase AC voltage of n = 2 or more, and an electrode that applies the n-phase AC voltage and an insulator that insulates between the electrodes. An electrostatic chuck device comprising a sample stage and a circuit for applying the n-phase AC voltage ,
The application circuit for the n-phase AC voltage insulates the primary side and the secondary side of the n-phase AC power source, and maintains the secondary side for supplying the n-phase AC voltage to each electrode at a floating potential with respect to the ground potential. The primary side and the secondary side of the n-phase AC power source are insulated by an insulating transformer, and a switch for turning on / off the adsorption force is provided on the primary side of the insulating transformer. Electrostatic chuck device. 2. The electrostatic chuck device according to claim 1, wherein an area ratio of the electrodes to which the n-phase AC voltage is applied is configured such that a value of an area ratio of the electrodes of each phase is 1. Electric chuck device. In the electrostatic chuck according to claim 1, wherein the n-phase AC voltage is set to n = 3, the electrostatic chuck apparatus characterized by being configured to utilize three-phase AC power of a commercial. In a substrate processing method for processing a substrate with a vacuum processing apparatus having an electrostatic chuck for applying an AC voltage, the electrostatic chuck has an AC voltage of n = 2 or more, and an electrode to which the n-phase AC voltage is applied And a sample stage made of an insulator that insulates between the electrodes, and a circuit that applies the n-phase AC voltage,
  A step of locking the substrate with an electrostatic attraction force after loading and mounting the substrate on the sample stage installed in the vacuum vessel, a step of introducing a process gas into the vacuum vessel, and a step of being locked by the introduced process gas. Plasma processing of the substrate, comprising: a step of vacuum processing the substrate, a step of stopping the introduction of the process gas after the vacuum processing, a step of turning off the electrostatic adsorption force, and a step of unloading the substrate after the vacuum processing A substrate processing method for performing
  The application circuit for the n-phase AC voltage insulates the primary side and the secondary side of the n-phase AC power source, and maintains the secondary side for supplying the n-phase AC voltage to each electrode at a floating potential with respect to the ground potential. Configured as
  Insulation between the primary side and the secondary side of the n-phase AC power supply is performed by an insulation transformer, and a switch for turning on and off the adsorption force is provided on the primary side of the insulation transformer,
  A substrate processing method characterized by eliminating the need for charge removal processing of a substrate when the substrate is detached after vacuum processing.

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