HK1158361B

HK1158361B - Method for inspecting electrostatic chuck, and electrostatic chuck apparatus

Info

Publication number: HK1158361B
Application number: HK11112487.2A
Authority: HK
Inventors: 藤泽博
Original assignee: 创意科技股份有限公司
Priority date: 2008-10-20
Filing date: 2009-10-19
Publication date: 2013-08-30

Description

Method for inspecting electrostatic chuck and electrostatic chuck device

Technical Field

The present invention relates to a method of inspecting an electrostatic chuck in an electrostatic chuck device and an electrostatic chuck device, the electrostatic chuck device including a bipolar electrostatic chuck having two chucking electrodes in a dielectric medium, and a chuck power supply for supplying a dc voltage for chucking to the bipolar electrostatic chuck.

Background

In the inspection after the bipolar electrostatic chuck is manufactured, the inspection after the electrostatic chuck is mounted in a use apparatus such as a semiconductor manufacturing apparatus, and the like, conventionally, the presence or absence of an abnormality in the electrostatic chuck is inspected.

As a method for checking the presence or absence of an abnormality in the electrostatic chuck, conventionally, for example, the following is performed: leakage current [ steady-state current after power-on (i.e., current stabilized at a constant value) ] flowing through the two adsorption electrodes of the electrostatic chuck in a state where an adsorbate such as a substrate is not mounted is measured using two ammeters provided between the two adsorption electrodes and the chuck power supply.

Patent document 1 does not describe a method for checking whether or not there is an abnormality in the electrostatic chuck, but describes two ammeters similar to those described above and an example of a waveform of a current flowing through the two ammeters. The leakage current corresponds to a steady-state current of a current when no substrate is disposed, as described in fig. 3 of patent document 1.

However, in the conventional inspection method described in patent document 1, although it is known whether or not the insulation of the dc current is poor, it is impossible to determine an abnormality of the capacitance in the electrostatic chuck. Since the electrostatic chuck is a member that electrostatically adsorbs an object to be adsorbed, an abnormality in the electrostatic capacitance in the electrostatic chuck causes an abnormality in the adsorption force with respect to the object to be adsorbed. In addition, the determination of whether or not an object is present on the electrostatic chuck or whether or not the object is normally attracted may be adversely affected. Therefore, it is important to detect not a poor insulation of the direct current but an abnormality of the electrostatic capacitance.

In the inspection method of patent document 1, it is known where insulation failure occurs in the electrostatic chuck based on the magnitude of the leakage current, but it is not possible to determine which suction electrode has an abnormality in the periphery. For example, it is impossible to determine which of the two adsorption electrodes has an abnormality in the periphery thereof or has an abnormality between the two adsorption electrodes. When there is a difference in the measurement values of the two galvanometers, it may be possible to estimate which attraction electrode the abnormal portion is closer to, but this estimation is not necessarily accurate.

In addition, unlike patent document 1, on a mounting table of a glass substrate including an electrostatic chuck having a chuck electrode between a lower dielectric layer and an upper dielectric layer and a lower electrode disposed below the electrostatic chuck, the following method is proposed as a method for diagnosing the insulating state of the dielectric layer before starting the use of the electrostatic chuck (patent document 2): a DC diagnostic voltage lower than that in the case of holding a glass substrate by suction is applied to a chuck electrode of an electrostatic chuck, the electrical characteristics (voltage, current) of the electrostatic chuck at that time are measured, and whether the electrostatic chuck is usable or not is determined from the obtained measurement data and preset setting data.

However, in the diagnostic method for an electrostatic chuck described in patent document 2, as in the case of patent document 1, it is possible to determine whether or not insulation failure has occurred at any position in the electrostatic chuck by comparing the measurement data with the setting data, but it is impossible to determine which suction electrode has an abnormality at its periphery.

Patent document 1: japanese laid-open patent publication No. 11-330, 220 (FIGS. 1, 3)

Patent document 2: japanese patent laid-open No. 2008-047, 564 (FIGS. 1 and 2)

Disclosure of Invention

However, since the electrostatic chuck is a member that electrostatically adsorbs an object to be adsorbed, an abnormality in electrostatic capacitance in the electrostatic chuck becomes a cause of an abnormality in the adsorption force with respect to the object to be adsorbed, and in particular, in a bipolar electrostatic chuck that has a positive adsorption electrode and a negative adsorption electrode arranged along the surface of a dielectric body in the dielectric body and electrostatically adsorbs the object to be adsorbed, it is important to determine which of the two adsorption electrodes has an abnormality in the periphery thereof or between the two adsorption electrodes, and to easily determine which of the electrodes has a failure such as a disconnection, an electrode falling off, or a short circuit to the ground, in addition to being useful for securing normal adsorption and tracking of an improper position at the time of manufacturing and actual operation.

Accordingly, a main object of the present invention is to provide a method and an apparatus for determining which attraction electrode in a bipolar electrostatic chuck has an abnormality in electrostatic capacitance.

The inspection method of an electrostatic chuck of the present invention is characterized in that,

in an electrostatic chuck device including a bipolar electrostatic chuck having a positive attraction electrode and a negative attraction electrode arranged along a surface of a dielectric body in the dielectric body and attracting an object to be attracted by static electricity, and a chuck power supply for supplying a positive DC voltage and a negative DC voltage to the positive attraction electrode and the negative attraction electrode of the electrostatic chuck, respectively, with reference to a ground potential portion,

a positive auxiliary electrode and a negative auxiliary electrode are provided in the dielectric body of the electrostatic chuck and on the back side of the positive chucking electrode and the negative chucking electrode so as to face the chucking electrodes with a predetermined gap therebetween, respectively, and the auxiliary electrodes are connected to the ground potential portion,

a determination step of measuring at least three transient currents, namely (a) a 1 st transient current flowing between a positive chucking electrode of the electrostatic chuck and the chuck power supply, (b) a 2 nd transient current flowing between a positive auxiliary electrode of the electrostatic chuck and the ground potential portion, (c) a 3 rd transient current flowing between a negative chucking electrode of the electrostatic chuck and the chuck power supply, and (d) a 4 th transient current flowing between a negative auxiliary electrode of the electrostatic chuck and the ground potential portion, respectively, and calculating a 5 th transient current, which is a difference between the 1 st transient current and the 2 nd transient current or a difference between the 3 rd transient current and the 4 th transient current, when the positive and negative dc voltages are applied to or disconnected from the chuck power supply in a state where no adherend is placed on the electrostatic chuck, the obtained transient currents are compared with reference values of the transient currents obtained from a normal electrostatic chuck, and an abnormality of the electrostatic capacitance around each of the chucking electrodes in the electrostatic chuck is determined.

The electrostatic chuck device of the present invention is characterized in that,

the electrostatic chuck device is provided with a bipolar electrostatic chuck having a positive attraction electrode and a negative attraction electrode arranged along a surface of a dielectric body in the dielectric body and attracting an object to be attracted by static electricity, and a chuck power supply for supplying a positive direct current voltage and a negative direct current voltage to the positive attraction electrode and the negative attraction electrode of the electrostatic chuck, respectively, with reference to a ground potential portion, and comprises:

a positive auxiliary electrode and a negative auxiliary electrode provided in the dielectric of the electrostatic chuck and on the back side of the positive attraction electrode and the negative attraction electrode so as to face the attraction electrodes with a predetermined gap therebetween; a 1 st current meter connected between the positive clamping electrode of the electrostatic chuck and the chuck power supply to measure a 1 st transient current flowing therebetween; a 2 nd current meter connected between the positive auxiliary electrode of the electrostatic chuck and the ground potential portion to measure a 2 nd transient current flowing therebetween; a 3 rd current meter connected between the negative chucking electrode of the electrostatic chuck and the chuck power supply to measure a 3 rd transient current flowing therebetween; a 4 th current meter connected between the negative auxiliary electrode of the electrostatic chuck and the ground potential portion to measure a 4 th transient current flowing therebetween; a computing unit for computing a 5 th transient current obtained as a difference between the 1 st transient current and the 2 nd transient current or a difference between the 3 rd transient current and the 4 th transient current; and

and a determination device configured to measure at least three transient currents among the 1 st to 4 th transient currents measured by at least three of the 1 st to 4 th ammeters, calculate the 5 th transient current calculated by the calculation unit, and compare each of the obtained transient currents with a reference value of each transient current obtained from a normal electrostatic chuck, to determine an abnormality of an electrostatic capacitance in the electrostatic chuck, when the positive and negative dc voltages are applied to or disconnected from the electrostatic chuck from the chuck power supply in a state where an object to be attracted is not placed on the electrostatic chuck.

The 1 st or 2 nd transient current is a current corresponding to the magnitude of the capacitance between the positive chucking electrode and the positive auxiliary electrode of the electrostatic chuck. The 3 rd or 4 th transient current is a current corresponding to the magnitude of the capacitance between the negative attraction electrode and the negative auxiliary electrode of the electrostatic chuck. The 5 th transient current is a current corresponding to the size of the capacitance between the positive and negative chucking electrodes of the electrostatic chuck.

Therefore, the determination of which attraction electrode in the bipolar electrostatic chuck has an abnormality in electrostatic capacitance can be made as follows, that is, the presence or absence of an abnormality in the electrostatic capacitance can be determined by measuring at least three transient currents in the 1 st to 4 th transient currents, and comparing the 5 th transient current, which is obtained as the 1 st or 2 nd transient current, the 3 rd or 4 th transient current, and the difference between the 1 st transient current and the 2 nd transient current or the difference between the 3 rd transient current and the 4 th transient current, with predetermined reference values (corresponding 1 st to 5 th transient currents obtained from a normal electrostatic chuck of the same specification as the electrostatic chuck), and in addition to the determination of whether or not an abnormality occurs in the electrostatic capacitance in the vicinity of which attraction electrode in the bipolar electrostatic chuck, it is also possible to determine whether or not an abnormality occurs in the electrostatic capacitance between both attraction electrodes.

In addition, in the present invention, since the presence or absence of an abnormality in the electrostatic capacitance in the bipolar electrostatic chuck is determined using the measured or calculated 1 st to 5 th transient currents, there are advantages in comparison with the case of using the conventional voltages and currents: it is possible to obtain a large amount of information on the electrostatic capacitance that is the basis of the function of the electrostatic chuck.

In the present invention, it is preferable that the determination step (determination means) includes (a) a 1 st step (1 st function) of measuring at least one of the 1 st and 2 nd transient currents when the positive and negative dc voltages are applied to the electrostatic chuck from the chuck power supply, and determining an abnormality in the electrostatic capacitance between the positive suction electrode and the positive auxiliary electrode of the electrostatic chuck by comparing a time until the transient current drops to a predetermined ratio of a peak value thereof with a corresponding time of a normal electrostatic chuck; (b) a 2 nd step (function 2) of measuring at least one of the 3 rd and 4 th transient currents, comparing a time period until the transient current falls to a predetermined ratio of a peak value thereof with a corresponding time period of a normal electrostatic chuck, and determining an abnormality in electrostatic capacitance between a negative suction electrode and a negative auxiliary electrode of the electrostatic chuck; (c) and a 3 rd step (function 3) of comparing a peak value of a 5 th transient current obtained as a difference between the 1 st transient current and the 2 nd transient current or a difference between the 3 rd transient current and the 4 th transient current with a corresponding peak value of a normal electrostatic chuck, and determining an abnormality of the electrostatic capacitance between the positive chucking electrode and the negative chucking electrode of the electrostatic chuck. In this way, by using the time until the peak value of the measured transient current falls to a predetermined ratio to determine whether or not there is an abnormality in the electrostatic capacitance, the influence of the impedance to the power supply and the wiring of the electrostatic chuck and the interference of the ambient electromagnetic field is less likely to be exerted, and thus there is an advantage that more accurate determination can be performed.

In the present invention, it is preferable that the positive auxiliary electrode of the electrostatic chuck is formed in a shape corresponding to the positive chucking electrode, and the negative auxiliary electrode is formed in a shape corresponding to the negative chucking electrode. Accordingly, the capacitance between each attracting electrode and each auxiliary electrode is increased, and accordingly, the transient current flowing through the capacitance is increased and decreased. As a result, it becomes easy to determine the change of the transient current or the abnormality of the capacitance.

According to the present invention, by measuring at least three transient currents among the 1 st to 4 th transient currents, obtaining the 5 th transient current, and comparing the obtained transient currents with predetermined reference values to determine the abnormality of the electrostatic capacitance, it is possible to determine which attraction electrode in the bipolar electrostatic chuck has the electrostatic capacitance abnormality in the vicinity thereof, and it is also possible to determine the electrostatic capacitance between the attraction electrodes has the abnormality.

Drawings

Fig. 1 is a diagram showing an embodiment of an electrostatic chuck device for carrying out the inspection method of the present invention.

Fig. 2 is a schematic top view of the electrostatic chuck of fig. 1.

Fig. 3 is a diagram showing an example of simulation results of each transient current of a normal electrostatic chuck.

FIG. 4 shows the electrostatic capacitance C between the positive adsorption electrode and the positive auxiliary electrode of the electrostatic chuck₁A diagram showing an example of simulation results of each transient current in a case where the current is larger than normal.

FIG. 5 shows the electrostatic capacitance C between the positive adsorption electrode and the positive auxiliary electrode of the electrostatic chuck₁A graph showing an example of simulation results of each transient current in a case where the transient current is smaller than that in a normal state.

FIG. 6 shows the electrostatic capacitance C between the negative attraction electrode and the negative auxiliary electrode of the electrostatic chuck₂A diagram showing an example of simulation results of each transient current in a case where the current is larger than normal.

FIG. 7 shows the electrostatic capacitance C between the negative attraction electrode and the negative auxiliary electrode of the electrostatic chuck₂A graph showing an example of simulation results of each transient current in a case where the transient current is smaller than that in a normal state.

FIG. 8 shows the electrostatic capacitance C between the positive and negative chucking electrodes of the electrostatic chuck₃A diagram showing an example of simulation results of each transient current in a case where the current is larger than normal.

FIG. 9 shows the electrostatic capacitance C between the positive and negative chucking electrodes of the electrostatic chuck₃A graph showing an example of simulation results of each transient current in a case where the transient current is smaller than that in a normal state.

Detailed Description

The present invention will be described in detail below with reference to embodiments shown in the drawings.

In the following embodiments, a case will be described in which the inspection of the electrostatic chuck is performed using the transient current when the positive and negative dc voltages are applied from the chuck power supply to the electrostatic chuck, but the inspection of the electrostatic chuck can also be performed using the transient current when the positive and negative dc voltages are disconnected from the chuck power supply to the electrostatic chuck.

Fig. 1 is a diagram showing an embodiment of an electrostatic chuck device for carrying out the inspection method of the present invention. Fig. 2 is a schematic top view of the electrostatic chuck of fig. 1.

The electrostatic chuck device comprises: a bipolar electrostatic chuck 4 for electrostatically attracting an adherend (e.g., a substrate such as a wafer) 2; and a chuck power supply 26 for supplying a positive dc voltage + V and a negative dc voltage-V to the positive chucking electrode 8 and the negative chucking electrode 10 of the electrostatic chuck 4, respectively, with reference to the ground potential portion GND.

The electrostatic chuck 4 has a pair of positive and negative chucking electrodes 8 and 10 disposed along the surface of a dielectric 6 such as ceramic in the vicinity of the surface. In this embodiment, both the adsorption electrodes 8 and 10 are semicircular and arranged in a circular shape facing each other in the same plane, as in the example shown in fig. 2. However, the shape of the pair of adsorption electrodes 8 and 10 is not limited to this, and may be other shapes, for example, comb-like shapes.

In the dielectric 6 of the electrostatic chuck 4, the positive auxiliary electrode 12 and the negative auxiliary electrode 14 are disposed so as to face the respective suction electrodes 8 and 10 with a gap therebetween, on the back sides of the positive suction electrode 8 and the negative suction electrode 10 (in other words, on the opposite side of the suction surface of the object 2). Both auxiliary electrodes 12 and 14 do not necessarily have to have shapes corresponding to the attraction electrodes 8 and 10, but in this embodiment, the positive auxiliary electrode 12 has a shape corresponding to the positive attraction electrode 8, and the negative auxiliary electrode 14 has a shape corresponding to the negative attraction electrode 10. More specifically, in this embodiment, the auxiliary electrodes 12 and 14 are semicircular in shape having substantially the same size as the attracting electrodes 8 and 10, respectively, and are arranged in a circular shape facing each other in the same plane.

In fig. 1, the auxiliary electrodes 12 and 14 are illustrated as being smaller than the attracting electrodes 8 and 10, but this is for convenience of illustration only. In fig. 2, the auxiliary electrodes 12, 14 overlap the adsorption electrodes 8, 10, and are therefore not shown in the figure.

A 1 st electrostatic capacitance C is formed between the positive adsorption electrode 8 and the positive auxiliary electrode 12 in a state where the adsorbate 2 is not placed₁A 2 nd electrostatic capacitance C is formed between the negative adsorption electrode 10 and the negative auxiliary electrode 14₂A 3 rd electrostatic capacitance C is formed between the positive adsorption electrode 8 and the negative adsorption electrode 10₃. These are illustrated in fig. 1 by an equivalent circuit.

In this embodiment, the electrostatic chuck 4 has a support base 16 that supports the dielectric 6 and the like. When the mount 16 is made of a conductor such as a metal, the mount 16 is usually electrically grounded.

The chuck power supply 26 has: a positive power supply 28 for outputting the positive dc voltage + V from its positive output terminal 32 with reference to a ground terminal 36; and a negative power supply 30 for outputting the negative dc voltage-V from a negative output terminal 34 with reference to a ground terminal 36. The two DC voltages + V and-V are equal in magnitude and opposite in polarity.

Between the positive chucking electrode 8 of the electrostatic chuck 4 and the chuck power supply 26 (more specifically, the positive output terminal 32 of the chuck power supply 26), a 1 st transient current I for measuring a current flowing therebetween is connected₁The 1 st ammeter 21. A current limiting resistor 38 is connected in series to the line of the ammeter 21 as necessary.

Between the positive auxiliary electrode 12 of the electrostatic chuck 4 and the ground potential portion GND, a 2 nd transient current I for measuring a current flowing therebetween is connected₂2 nd ammeter 22. In other words, the positive auxiliary electrode 12 is connected to the ground potential portion GND (i.e., grounded) via the ammeter 22. Since the ground terminal 36 of the chuck power supply 26 is also connected to the ground potential portion GND, the positive auxiliary electrode 12 can be said to be connected to the ground terminal 36 of the chuck power supply 26 via the ammeter 22.

Between the negative chucking electrode 10 of the electrostatic chuck 4 and the chuck power supply 26 (more specifically, the negative output terminal 34 thereof), there is connected a measuring circuit for measuring the 3 rd transient current I flowing therethrough₃The 3 rd ammeter 23. A current limiting resistor 40 having the same resistance value as that of the current limiting resistor 38 is connected in series as necessary to the line of the ammeter 23.

Between the negative auxiliary electrode 14 of the electrostatic chuck 4 and the ground potential portion GND, a 4 th transient current I for measuring a current flowing therebetween is connected₄The 4 th ammeter 24. In other words, the negative auxiliary electrode 14 is connected to the ground potential portion GND (i.e., grounded) via the ammeter 24. Alternatively, the negative auxiliary electrode 14 may be said to be connected to the ground terminal 36 of the chuck power supply 26 via the ammeter 24.

The chuck power supply 26 is a DC power supply, so the transient current I is described above₁～I₄The current is essentially a current that flows in a transient state when the chuck power supply 26 is turned on, that is, when the positive and negative dc voltages + V, -V are applied from the chuck power supply 26 to the electrostatic chuck 4. This point will be further described later with reference to fig. 3 and the drawings subsequent to fig. 3.

In addition, when the chuck power supply 26 is turned on, the transient current I₅Flows through the electrostatic capacitor C₃. The transient current I₅Is the above-mentioned transient current I according to kirchhoff's law₁And I₂Difference between the two or the above-mentioned transient current I₃And I₄The difference in current. Specifically, the transient current I can be obtained by the following numerical expression 1 or 2₅。

[ numerical formula 1]I₅＝I₁-I₂

[ numerical formula 2]I₅＝I₃-I₄

Transient current I measured by galvanometers 21-24₁～I₄Is supplied to the determination device 42. In this embodiment, the determination device 42 has a function of calculating the transient current I according to the above-described expression 1 or expression 2 in addition to the function described later₅The operation unit of (2). The determination device 42 is configured using a computer, for example.

In order to inspect the electrostatic chuck 4, the following determination step is performed in the inspection method of the present embodiment.

That is, the transient current I is measured when the positive and negative DC voltages + V and-V are applied from the chuck power supply 26 to the electrostatic chuck 4 in a state where the object 2 is not placed on the electrostatic chuck 4₁～I₅In, including the transient current I₅At least four transient currents. Specifically, at least four transient currents of the combinations shown in table 1 were measured, respectively. All five transient currents I can also be measured and calculated₁～I₅. Then, the measured and calculated transient currents are compared with predetermined reference values, respectively, to determine an abnormality in the electrostatic capacitance in the electrostatic chuck 4.

[ Table 1]

Combination of	C₁For judgment	C₂For judgment	C₃For judgment	I₅For calculation
					1	I₁	I₃	I₅	I₂
2	I₁	I₃	I₅	I₄
					3	I₁	I₄	I₅	I₂
4	I₁	I₄	I₅	I₃
					5	I₂	I₃	I₅	I₁
6	I₂	I₃	I₅	I₄
					7	I₂	I₄	I₅	I₁
8	I₂	I₄	I₅	I₃

I in Table 1₅Calculated transient current, except for electrostatic capacitance C₁、C₂、C₃In addition to the transient current for determination, the transient current required for the transient current I5 is calculated according to the above expression 1 or expression 2.

The above transient current I₁、I₂The capacitance C is equal to the capacitance C₁The magnitude of (c) corresponds to the current. The above transient current I₃、I₄The capacitance C is equal to the capacitance C₂The magnitude of (c) corresponds to the current. The above transient current I₅The capacitance C is equal to the capacitance C₃The magnitude of (c) corresponds to the current. Therefore, by performing the determination step as described above, it is possible to determine which of the adsorption electrodes 8 and 10 in the electrostatic chuck 4 has the electrostatic capacitance C in the periphery thereof₁Or C₂It is possible to determine that an abnormality has occurred in the electrostatic capacitance C3 between the two attracting electrodes 8, 10.

That is, according to this inspection method, by providing the auxiliary electrodes 12 and 14 corresponding to the two adsorption electrodes 8 and 10, respectively, it is possible to measure the transient current I as the return current from the two auxiliary electrodes 12 and 14₂、I₄And pressSince the transient current I5 flowing between the two attracting electrodes 8, 10 can be calculated as described in the above equation 1 or equation 2, the capacitance C can be easily captured₁～C₃A change in (c).

The above case will be further described below together with a more specific example of the above determination step. In the following embodiment, the above-described determination step is composed of the following 1 st to 3 rd steps.

(a) Step 1: measuring the above transient current I₁And I₂And a time period until the transient current falls to a predetermined ratio of the peak value thereof is compared with a time period of a normal electrostatic chuck having the same specification as the electrostatic chuck 4 as the corresponding time period, to determine the electrostatic capacitance C between the positive chucking electrode 8 and the positive auxiliary electrode 12 of the electrostatic chuck 4₁Is abnormal.

The predetermined ratio of the peak value is, for example, 1/e of the peak value. e is the base of the natural logarithm and is 2.718. The predetermined ratio is not limited to this, and the following description will be given by way of example. The predetermined ratio in the following step 2 is also the same.

In addition, in the electrostatic capacitance C₁In the determination of (3), the transient current I may be measured₁And I₂And both are used for the determination. This improves the accuracy of determination. Transient current I in the following 2 nd step₃And I₄The same applies. However, in the following simulation, the electrostatic capacitance C₁Using the transient current I for determination₁In the electrostatic capacitor C₂Using the transient current I for determination₃The following description will be given by way of example.

(b) And a 2 nd step: measuring the above transient current I₃And I₄The time until the transient current drops to a predetermined ratio of the peak value thereof is compared with the time of a normal electrostatic chuck having the same specification as the electrostatic chuck 4 as the corresponding time, and the negative attraction electrode 10 and the negative auxiliary electrode of the electrostatic chuck 4 are determinedElectrostatic capacitance C between electrodes 14₂Is abnormal.

(c) And a 3 rd step: calculating the above transient current I₅The peak value of the transient current is compared with a peak value of a normal electrostatic chuck having the same specification as that of the electrostatic chuck 4 as the peak value corresponding thereto, and the electrostatic capacitance C between the positive attraction electrode 8 and the negative attraction electrode 10 of the electrostatic chuck 4 is determined₃Is abnormal.

The above-described steps 1 to 3 will be described in more detail with reference to table 2, in which table 2 integrates fig. 3 to 9, which are the results of a simulation using the equivalent circuit of the device shown in fig. 1, and the contents of the determination.

[ Table 2]

FIG. 3 shows the above-mentioned transient current I of the normal electrostatic chuck 4₁～I₅An example of (1). The power is turned on at the timing of time 0. The same applies to other figures. For transient current I₃Adding brackets to represent and to the transient current I₁The curves coincide. With respect to transient current I₄The same applies. The same applies to other figures.

The transient current I of the normal electrostatic chuck 4 is measured in advance₁、I₃Time t to 1/e of peak value P₁And set it as the reference value for comparison in the above-mentioned 1 st and 2 nd steps. The time t₁For example, it may be stored in the determination device 42. In addition, the transient current I₁～I₄Is used for simplicity in the following description and in the drawings, the same reference P, but at the transient current I₁～I₄Are not limited to the same value.

Then, the normal transient current I of the electrostatic chuck 4 is calculated in advance₅Peak value P of₁And the ratio is set to the ratio in the step 3A relatively high reference value. The peak value P₁For example, it may be stored in the determination device 42.

In the simulation, the current data of the normal electrostatic chuck 4 shown in fig. 3 was used as a reference for comparison, but in the actual inspection of the electrostatic chuck 4, the current data of the normal electrostatic chuck of the same specification as that of the electrostatic chuck 4 to be inspected was used. The two data are actually the same, and therefore the two data are not distinguished in the following description.

Electrostatic capacity C in electrostatic chuck 4₁In the case of an abnormality, for example, fig. 4 shows an example of a case (for example, 150nF) larger than a normal state (for example, 100nF), and fig. 5 shows an example of a case (for example, 30nF) smaller than the normal state. Comparing with FIG. 3, the transient current I₁、I₂And significantly changed.

As the above-mentioned step 1, a transient current I is measured₁Time t until 1/e of peak value P₂(case of FIG. 4), t₃(case of fig. 5), and the time t of the normal electrostatic chuck 4 is compared with₁A comparison is made. In the case of the example of FIG. 4, t₁＜t₂Thus, it is determined as the electrostatic capacitance C₁Larger than normal. In the case of the example of FIG. 5, t is₁＞t₃Thus, it is determined as the electrostatic capacitance C₁Smaller than normal. This is because: as is well known from transient phenomena, a transient current flowing through a capacitor immediately after a dc power supply is turned on becomes longer in charging time with a large capacitor and gradually decays with time, and becomes shorter in charging time with a small capacitor and rapidly decays with time. Thus, the capacitance C can be determined₁Is abnormal.

As an electrostatic capacitance C₁The reason for the increase in size is, for example, that the distance between the positive adsorption electrode 8 and the positive auxiliary electrode 12 is equivalently smaller. The reason for this is, for example, that the dielectric 6 thermally contracts, and the material of the positive adsorption electrode 8 diffuses toward the periphery by electron migrationThe case of (3), the case of melting and solidifying the electrode material to the periphery of the positive adsorption electrode 8 by the discharge generated at the periphery, and the like.

As an electrostatic capacitance C₁The reason for the reduction is, for example, disconnection to the positive chucking electrode 8, and an equivalent increase in the distance between the positive chucking electrode 8 and the positive auxiliary electrode 12. The latter reason may be, for example, expansion of the dielectric 6 due to heat, peeling of the dielectric 6 around the positive adsorption electrode 8, or the like.

FIG. 6 shows the electrostatic capacitance C of the electrostatic chuck 4₂Fig. 7 shows an example of an abnormal case, for example, a case (for example, 150nF) larger than a normal case (for example, 100nF), and an example of a case (for example, 30nF) smaller than the normal case. Comparing with FIG. 3, the transient current I₃、I₄And significantly changed.

As the above-mentioned 2 nd step, the transient current I is measured₃Time t until 1/e of peak value P₄(case of FIG. 6), t₅(case of fig. 7) and compares it with the time t of the normal electrostatic chuck 4₁A comparison is made. T in the case of the example of FIG. 6₁＜t₄Thus, it is determined as the electrostatic capacitance C₂Larger than normal. T in the case of the example of FIG. 7₁＞t₅Thus, it is determined as the electrostatic capacitance C₂Smaller than normal. Thus, the capacitance C can be determined₂Is abnormal.

Static capacitance C₂Examples of the cause of the increase or decrease in the capacitance C₁The same applies.

In this way, the electrostatic capacitance C can be determined independently of each other by the above-described 1 st step and 2 nd step₁Abnormal and electrostatic capacitance C₂Thus, it is possible to easily determine whether an abnormality occurs in the electrostatic capacitance in the vicinity of the positive attraction electrode 8 or the negative attraction electrode 10 of the electrostatic chuck 4.

FIG. 8 shows the electrostatic capacitance C of the electrostatic chuck 4₃Abnormal situationFig. 9 shows an example of a case (for example, 30nF) in which the frequency is larger than the normal frequency (for example, 10nF), and an example of a case (for example, 3nF) in which the frequency is smaller than the normal frequency. Comparing with FIG. 3, the transient current I₅And significantly changed.

As the above-mentioned 3 rd step, the transient current I is measured₅Peak value P of₂(case of FIG. 8), P₃(situation of fig. 9) and compares it with the peak value P of the normal electrostatic chuck 4₁A comparison is made. P in the case of the example of FIG. 8₁＜P₂Thus, it is determined as the electrostatic capacitance C₃Larger than normal. P in the case of the example of FIG. 9₁＞P₃Thus, it is determined as the electrostatic capacitance C₃Smaller than normal. Thus, the capacitance C can be determined₃Is abnormal.

As an electrostatic capacitance C₃The reason for the increase in size is, for example, (a) the distance between the attraction electrodes 8 and 10 is equivalently decreased, and (b) the dielectric constant of the dielectric 6 between the attraction electrodes 8 and 10 is increased. As the cause of (a), for example, a case where the material of the both attracting electrodes 8, 10 diffuses between the both attracting electrodes 8, 10 by electron transfer, a case where the electrode material melts and solidifies toward the opposite electrode due to electric discharge generated between the both attracting electrodes 8, 10, or the like is considered.

As an electrostatic capacitance C₃The reason for the reduction is, for example, a case where a part of one or both of the suction electrodes 8 and 10 is defective, a case where the dielectric constant of the dielectric 6 is reduced with time, or the like.

In this way, it can be easily determined by the above-described step 3 that an abnormality has occurred in the electrostatic capacitance between the two attracting electrodes 8, 10.

As described above, the auxiliary electrodes 12 and 14 of the electrostatic chuck 4 are preferably shaped to correspond to the chucking electrodes 8 and 10, respectively. When so arranged, the electrostatic capacitance C₁、C₂Increased in size, and accordingly flows through the electrostatic capacitance C₁、C₂Transient current I of₂、I₄Also become large and slowTherefore, the change of the transient current or the capacitance C can be easily determined₁、C₂Is abnormal.

In this embodiment, the determination device 42 calculates the transient current I as described above₅And a function of performing processing (i.e., transient current measurement, comparison, and electrostatic capacitance abnormality determination) substantially the same as in the determination step. More specifically, this embodiment includes a 1 st function of performing a process having substantially the same contents as those of the 1 st step, a 2 nd function of performing a process having substantially the same contents as those of the 2 nd step, and a 3 rd function of performing a process having substantially the same contents as those of the 3 rd step. In other words, the determination device 42 is provided with a unit having such a function.

Therefore, the electrostatic chuck device of the present embodiment including the electrostatic chuck 4, the chuck power source 26, the ammeters 21 to 24, and the determination device 42 can exhibit the same operational effects as those described for the inspection method.

(description of reference numerals)

2: an adsorbate; 4: an electrostatic chuck; 6: a dielectric; 8: a positive adsorption electrode; 10: a negative adsorption electrode; 12: a positive auxiliary electrode; 14: a negative auxiliary electrode; 21-24: an ammeter; 26: a suction cup power supply; 42: a determination device; i is₁～I₅: current flow; c₁～C₃: an electrostatic capacitance; + V: a positive direct current voltage; -V: a negative dc voltage; GND: ground potential portion

Claims

1. An inspection method of an electrostatic chuck is characterized in that,

in the electrostatic chuck inspection method, a determination step is performed for measuring at least three transient currents, namely, a 1 st transient current flowing between (a) a positive chucking electrode of the electrostatic chuck and the chuck power supply, (b) a 2 nd transient current flowing between a positive auxiliary electrode of the electrostatic chuck and the ground potential portion, (c) a 3 rd transient current flowing between a negative chucking electrode of the electrostatic chuck and the chuck power supply, and (d) a 4 th transient current flowing between a negative auxiliary electrode of the electrostatic chuck and the ground potential portion, when the positive and negative dc voltages are applied to or disconnected from the electrostatic chuck from the chuck power supply in a state where no adherend is placed on the electrostatic chuck, and calculating a 5 th transient current, which is a difference between the 1 st transient current and the 2 nd transient current or a difference between the 3 rd transient current and the 4 th transient current, the obtained transient currents are compared with reference values of the transient currents obtained from a normal electrostatic chuck, and an abnormality of the electrostatic capacitance around each of the chucking electrodes in the electrostatic chuck is determined.

2. The method of claim 1, wherein the electrostatic chuck comprises a chuck body having a first surface and a second surface,

the determination step includes a step of applying the positive and negative DC voltages from the chuck power supply to the electrostatic chuck

A step 1 of measuring at least one of the 1 st and 2 nd transient currents, comparing a time period until the transient current falls to a predetermined ratio of a peak value thereof with a corresponding time period of a normal electrostatic chuck, and determining an abnormality of an electrostatic capacitance between a positive suction electrode and a positive auxiliary electrode of the electrostatic chuck;

a 2 nd step of measuring at least one of the 3 rd and 4 th transient currents, comparing a time period until the transient current falls to a predetermined ratio of a peak value thereof with a corresponding time period of a normal electrostatic chuck, and determining an abnormality in electrostatic capacitance between a negative suction electrode and a negative auxiliary electrode of the electrostatic chuck;

and a 3 rd step of comparing a peak value of a 5 th transient current obtained as a difference between the 1 st transient current and the 2 nd transient current or a difference between the 3 rd transient current and the 4 th transient current with a corresponding peak value of a normal electrostatic chuck, and determining an abnormality of the electrostatic capacitance between the positive chucking electrode and the negative chucking electrode of the electrostatic chuck.

3. The method of inspecting an electrostatic chuck according to claim 1 or 2,

the positive auxiliary electrode of the electrostatic chuck is in a shape corresponding to the positive adsorption electrode, and the negative auxiliary electrode is in a shape corresponding to the negative adsorption electrode.

4. An electrostatic chuck device, which is characterized in that,

a positive auxiliary electrode and a negative auxiliary electrode provided in the dielectric of the electrostatic chuck and on the back side of the positive attraction electrode and the negative attraction electrode so as to face the attraction electrodes with a predetermined gap therebetween;

a 1 st current meter connected between the positive clamping electrode of the electrostatic chuck and the chuck power supply to measure a 1 st transient current flowing therebetween;

a 2 nd current meter connected between the positive auxiliary electrode of the electrostatic chuck and the ground potential portion to measure a 2 nd transient current flowing therebetween;

a 3 rd current meter connected between the negative chucking electrode of the electrostatic chuck and the chuck power supply to measure a 3 rd transient current flowing therebetween;

a 4 th current meter connected between the negative auxiliary electrode of the electrostatic chuck and the ground potential portion to measure a 4 th transient current flowing therebetween;

a computing unit for computing a 5 th transient current obtained as a difference between the 1 st transient current and the 2 nd transient current or a difference between the 3 rd transient current and the 4 th transient current; and

5. An electrostatic chuck device according to claim 4,

the determination means includes a step of applying the positive and negative DC voltages from the chuck power supply to the electrostatic chuck

A 1 st function of measuring at least one of the 1 st and 2 nd transient currents, comparing a time until the transient current falls to a predetermined ratio of a peak value thereof with a corresponding time of a normal electrostatic chuck, and determining an abnormality of an electrostatic capacitance between a positive chucking electrode and a positive auxiliary electrode of the electrostatic chuck;

a 2 nd function of measuring at least one of the 3 rd and 4 th transient currents, comparing a time until the transient current falls to a predetermined ratio of a peak value thereof with a corresponding time of a normal electrostatic chuck, and determining an abnormality of an electrostatic capacitance between a negative suction electrode and a negative auxiliary electrode of the electrostatic chuck; and

and a 3 rd function of comparing a peak value of a 5 th transient current obtained as a difference between the 1 st transient current and the 2 nd transient current or a difference between the 3 rd transient current and the 4 th transient current with a corresponding peak value of a normal electrostatic chuck, and determining an abnormality of an electrostatic capacitance between a positive chucking electrode and a negative chucking electrode of the electrostatic chuck.

6. An electrostatic chuck device according to claim 4 or 5,