Wafer processing device and electrostatic adsorption method

Abstract

To apply an appropriate clamping voltage to an electrostatic chuck to prevent various problems related to wafer clamping during wafer processing before and after electrostatic chuck regeneration processing.SOLUTION: A wafer processing device F includes a processing chamber 1 that processes a wafer W, an electrostatic chuck 2 that attracts and supports the wafer W in the processing chamber 1, attracting electrodes 3a, 3b built in the electrostatic chuck 2, and a control device C that sets attracting voltages to be applied to the attracting electrodes 3a, 3b. The control device C sets a second attracting voltage during wafer processing immediately after the regeneration processing of the electrostatic chuck 2, and the second attracting voltage is lower than the first attracting voltage that has been set during wafer processing immediately before the regeneration processing of the electrostatic chuck 2, such that the magnitude of the attracting force generated by the electrostatic chuck 2 falls within a predetermined allowable range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wafer processing apparatus that performs a predetermined process on a wafer supported by an electrostatic chuck, and an electrostatic adsorption method using the electrostatic chuck. [Background technology]

[0002] 2. Description of the Related Art In wafer processing in semiconductor manufacturing equipment, an electrostatic chuck is used to attract and support a wafer in a predetermined position. During operation of semiconductor manufacturing equipment, particles adhere to the wafer support surface of the electrostatic chuck. For example, particles are generated by friction between the wafer and the wafer support surface, and adhere to the wafer support surface. As the amount of particles adhering to the wafer support surface increases, the electrostatic clamping force of the electrostatic chuck decreases. If the electrostatic clamping force decreases excessively, the chuck cannot properly support the wafer, making it impossible to continue wafer processing.

[0003] In order to recover the reduced electrostatic clamping force, various processes are performed on the wafer support surface of the electrostatic chuck. These processes for recovering the electrostatic clamping force are called electrostatic chuck regeneration processes or electrostatic chuck regeneration. Specific examples of the regeneration treatment of the electrostatic chuck include the heat treatment described in Patent Document 1, oxygen plasma treatment, chemical treatment, ultraviolet irradiation treatment, and the like. By performing either of these processes on the wafer support surface to remove particles adhering to the wafer support surface, the electrostatic adsorption force of the electrostatic chuck is restored. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 10-189699 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 does not clarify what attracting voltage should be applied to the electrostatic chuck in wafer processing before and after the regeneration process of the electrostatic chuck. If the attracting voltage is set inappropriately, various problems related to wafer attracting may occur. Specific examples of defects include wafer cracking, wafer bouncing, and wafer falling off. Wafer cracking occurs when the wafer is attached with excessive chucking force. Wafer cracking and bouncing occur when the wafer is released under a large residual chucking force. Wafer falling off occurs when the wafer is supported by a small chucking force.

[0006] A primary object of the present invention is to apply an appropriate attracting voltage to an electrostatic chuck during wafer processing before and after regenerating the electrostatic chuck, thereby suppressing the occurrence of various problems related to wafer attracting. [Means for solving the problem]

[0007] The wafer processing equipment includes: a processing chamber for processing the wafer; an electrostatic chuck that attracts and supports the wafer in the processing chamber; an adsorption electrode built into the electrostatic chuck; a control device that sets an attraction voltage to be applied to the attraction electrode, The control device sets a second attracting voltage, which is smaller than the first attracting voltage set during the wafer processing immediately before the regeneration process of the electrostatic chuck is performed, during the wafer processing immediately after the regeneration process of the electrostatic chuck is performed, so that the magnitude of the attracting force generated by the electrostatic chuck falls within a predetermined allowable range.

[0008] By performing the electrostatic chuck regeneration process, the magnitude of the chucking force generated by the electrostatic chuck is maintained within a preset tolerance range, thereby suppressing the occurrence of various problems related to wafer chucking.

[0009] The control device sets the clamping voltage so that the magnitude of the clamping force generated by the electrostatic chuck is substantially constant during wafer processing before and after performing the regeneration processing of the electrostatic chuck.

[0010] If the magnitude of the attracting force generated by the electrostatic chuck is substantially constant before and after the regeneration process of the electrostatic chuck, it becomes easy to uniformly perform wafer processing on a plurality of wafers.

[0011] To detect the chucking force of the electrostatic chuck, It is desirable to have a capacitance meter that measures the capacitance between the wafer and the chucking electrode.

[0012] When setting the second clamping voltage, The control device When the number of times that the electrostatic chuck has been regenerated is equal to or greater than a predetermined number of times, it is desirable to change the second clamping voltage to a smaller value.

[0013] The electrostatic adsorption method is In wafer processing before and after the regeneration process of the electrostatic chuck, a second attracting voltage that is smaller than a first attracting voltage that was applied to the attracting electrode of the electrostatic chuck during wafer processing immediately before the regeneration process of the electrostatic chuck is performed is applied to the attracting electrode of the electrostatic chuck during wafer processing immediately after the regeneration process of the electrostatic chuck is performed, so that the magnitude of the attracting force generated by the electrostatic chuck falls within a predetermined allowable range.

[0014] By performing the electrostatic chuck regeneration process, the magnitude of the chucking force generated by the electrostatic chuck is maintained within a preset tolerance range, thereby suppressing the occurrence of various problems related to wafer chucking.

[0015] The electrostatic adsorption method is The attracting voltage is applied so that the magnitude of the attracting force generated by the electrostatic chuck is substantially constant during wafer processing before and after the regeneration processing of the electrostatic chuck is performed.

[0016] If the magnitude of the attracting force generated by the electrostatic chuck is substantially constant in wafer processing before and after performing the regeneration processing of the electrostatic chuck, it becomes easy to uniformly perform wafer processing on multiple wafers. [Effects of the Invention]

[0017] By performing the electrostatic chuck regeneration process, the magnitude of the chucking force generated by the electrostatic chuck is maintained within a preset tolerance range, thereby suppressing the occurrence of various problems related to wafer chucking. [Brief explanation of the drawings]

[0018] [Figure 1] Schematic cross-sectional view showing the configuration of the processing chamber in the wafer processing apparatus. [Figure 2] FIG. 10 is an explanatory diagram showing an example of the relationship between the chucking force and the chucking voltage. [Figure 3] FIG. 10 is an explanatory diagram showing an example of the relationship between the chucking force and the chucking voltage. [Figure 4] FIG. 10 is an explanatory diagram showing another example of the relationship between the chucking force and the chucking voltage; [Figure 5] FIG. 10 is an explanatory diagram showing another example of the relationship between the chucking force and the chucking voltage; [Figure 6] FIG. 10 is an explanatory diagram showing another example of the relationship between the chucking force and the chucking voltage; [Figure 7] FIG. 10 is an explanatory diagram showing another example of the relationship between the chucking force and the chucking voltage; [Figure 8] Graph showing an example of stepwise change in chucking voltage [Figure 9] Graph showing an example of changing the clamping voltage in a curved manner [Figure 10] Flowchart for setting the chucking voltage [Figure 11] Flowchart for setting the chucking voltage DETAILED DESCRIPTION OF THE INVENTION

[0019] 1 is a schematic cross-sectional view showing the configuration inside a processing chamber 1 of a wafer processing apparatus F. The wafer processing apparatus F is a semiconductor manufacturing apparatus such as an etching apparatus, a film formation apparatus, or an ion implantation apparatus. An electrostatic chuck 2 that attracts and supports a wafer W is disposed in the processing chamber 1. 1, the electrostatic chuck 2 is disposed on the floor of the processing chamber 1. This configuration is an example, and the electrostatic chuck 2 does not need to be disposed in a specific location. For example, the electrostatic chuck 2 supporting the wafer W may be configured to change its position during processing of the wafer W.

[0020] The electrostatic chuck 2 has a pair of built-in chucking electrodes 3a, 3b. By applying chucking voltages V1, -V1 of opposite polarities to these chucking electrodes 3a, 3b, the wafer W is attracted to the electrostatic chuck 2. When the wafer W is attracted to the electrostatic chuck 2, the capacitance between the wafer W and the chucking electrodes 3a, 3b changes depending on the chucking state (support state). When the wafer W is strongly attracted, the value of the capacitance increases. Conversely, when the wafer W is weakly or insufficiently attracted, the value of the capacitance decreases. The magnitude of the chucking force of the electrostatic chuck 2 can be indirectly measured from the value of the capacitance. The wafer processing apparatus F is equipped with a capacitance meter D as a device for measuring this capacitance.

[0021] The chucking force may be measured directly using a force sensor. However, a measurement method using a force sensor requires the force sensor to be placed near the wafer. There is a concern that placing a force sensor near the wafer may interfere with wafer processing. Furthermore, when wafer processing is performed using plasma or ion beams, there is a concern that a force sensor disposed near the wafer may be sputtered by the plasma or ion beam, causing the force sensor to break down. Furthermore, there is a concern that particles generated by sputtering may get mixed into the wafer W, resulting in defective wafer processing.

[0022] As a method for indirectly measuring the chucking force, a displacement meter may be used instead of the capacitance meter D. In the measurement using the displacement meter, the chucking force of the electrostatic chuck 2 can be indirectly measured by measuring the displacement of the wafer W when the wafer W is attracted to the electrostatic chuck 2. However, even when measuring the chucking force using a displacement meter, it is necessary to place the displacement meter near the wafer W, and there are concerns that the various problems mentioned in measurements using force sensors may occur.

[0023] On the other hand, when measuring the clamping force using a capacitance meter D, it is only necessary to attach the capacitance meter D to the supply line for the voltage that applies the clamping voltage, and there is no need to place a measurement means near the wafer W. This avoids the problems that were a concern when using measurements using force sensors or displacement meters.

[0024] The measurement value of the capacitance meter D is transmitted to the control device C. The control device C sets the value of the chucking voltage based on the measurement value of the capacitance meter D, information on the setting value manually set by the device operator, etc. In the configuration of FIG. 1, the chucking voltages V1 and -V1 set by the control device C are applied to the chucking electrodes 3a and 3b.

[0025] 2 and 3 are graphs showing how the attracting force changes over time when a constant attracting voltage is applied to the attracting electrodes 3 a and 3 b. In FIG. 2 and FIG. 3, the regeneration process of the electrostatic chuck 2 is performed at time A. The values ​​of the attraction voltage in Fig. 3 are expressed as absolute values, and this also applies to Figs. 5, 7, and 9, which will be described later. 2, before the regeneration process of the electrostatic chuck 2 is performed, the attracting force of the electrostatic chuck 2 gradually decreases over time. Immediately after the regeneration process of the electrostatic chuck 2 is performed, the decreased attracting force recovers rapidly, but then decreases again over time.

[0026] When the attracting force of the electrostatic chuck 2 is subjected to large up and down movements, the state of support of the wafer W on the electrostatic chuck 2 changes significantly. If the attracting force is strong, the wafer W is strongly supported by the electrostatic chuck 2. Conversely, if the attracting force is weak, the wafer W is weakly supported by the electrostatic chuck 2.

[0027] When the wafer W is firmly supported by the electrostatic chuck 2, the degree of contact between the wafer W and the electrostatic chuck 2 is high, and heat transfer between them is promoted. When the wafer W is weakly supported by the electrostatic chuck 2, the degree of contact between the wafer W and the electrostatic chuck 2 is low, and heat transfer between them is suppressed. Differences in heat transfer depending on the support state of the wafer W result in large differences in wafer temperature during wafer processing.

[0028] Furthermore, when the wafer W is strongly supported by the electrostatic chuck 2 during wafer processing, if the attracting voltage is turned off (to zero) after the wafer processing, a large residual attracting force is generated between the wafer W and the electrostatic chuck 2. Conversely, when the wafer W is weakly supported by the electrostatic chuck 2 during wafer processing, if the attracting voltage is turned off (to zero) after the wafer processing, the residual attracting force generated between the wafer W and the electrostatic chuck 2 becomes small. Due to such differences in the residual attracting force, it is necessary to change the process required to release the wafer W from the electrostatic chuck 2 for each wafer W.

[0029] As shown in FIG. 3, if the attracting voltage is always kept constant, the attracting force increases sharply immediately after the regeneration process of the electrostatic chuck 2, which increases the probability of wafer attracting problems such as wafer cracking and wafer bounce.

[0030] In consideration of the above-mentioned problems, the present invention sets the applied voltage as shown in the graph of Fig. 5. The amount of particles deposited on the wafer support surface of the electrostatic chuck 2 increases over time. As the amount of particles increases, the attracting force of the electrostatic chuck 2 decreases. In this embodiment, the attracting voltage is increased over time to compensate for the decreased attracting force, thereby keeping the attracting force constant as shown in FIG.

[0031] The clamping force is recovered by regenerating the electrostatic chuck 2. If the same clamping voltage is applied before and after performing the regeneration process on the electrostatic chuck 2, there is a concern that the clamping force will increase sharply after performing the regeneration process on the electrostatic chuck 2, which may cause various problems. To address this concern, in order to maintain a constant attracting force during wafer processing before and after the regeneration process of the electrostatic chuck 2, the voltage applied immediately after the regeneration process is set to be smaller than the voltage applied immediately before the regeneration process. The voltage applied immediately before regeneration is a voltage applied to the attracting electrodes 3 a, 3 b of the electrostatic chuck 2 to attract and support the wafer W during wafer processing using an ion beam, plasma, or the like that was performed immediately before the regeneration processing was performed. The voltage applied immediately after regeneration is a voltage applied to the attracting electrodes 3 a, 3 b of the electrostatic chuck 2 to attract and support the wafer W during wafer processing using an ion beam, plasma, or the like, which is performed immediately after the regeneration process.

[0032] The above-described configuration prevents a large change in the support state of the wafer W, thereby suppressing various problems related to wafer attraction. Furthermore, by making the magnitude of the attracting force generated by the electrostatic chuck 2 substantially constant in wafer processing before and after performing the regeneration processing of the electrostatic chuck 2, it becomes easy to uniformly perform wafer processing on a plurality of wafers W.

[0033] 4 illustrates a configuration for maintaining a constant attracting force during wafer processing before and after regeneration processing of the electrostatic chuck 2. However, the attracting force does not necessarily need to be maintained at a specific value; it may be maintained at a level that can be considered substantially constant, within a range of ± a few percent from the specific attracting force. If the attracting force is substantially constant, the supporting state of the wafer W can be maintained almost constant.

[0034] Ideally, it is desirable to keep the chucking force substantially constant in wafer processing before and after performing the regeneration processing of the electrostatic chuck 2. However, if it is difficult to control the chucking force to be substantially constant, the chucking force may be controlled to fall within a preset allowable range instead of controlling the chucking force to be substantially constant. The allowable range of the chucking force that allows processing of the wafer W (including wafer processing in the processing chamber 1 and removal of the wafer W from the electrostatic chuck 2) to be performed without problems varies depending on the configuration of the wafer processing apparatus F. Taking this into consideration, the allowable range of the chucking force is individually set in advance depending on the configuration of the wafer processing apparatus F, and the chucking force is controlled so that it falls within the set allowable range. The unique value for making the attraction force substantially constant is a value within an allowable range, and the control for making the attraction force substantially constant is performed within a preset allowable range.

[0035] 6 and 7, the clamping voltage is set so that the clamping force falls within the allowable range. Specifically, the clamping voltage is set as shown in FIG. 7 so that the clamping force falls within the allowable range X shown in FIG. In the embodiment shown in FIGS. 6 and 7 , similarly to the embodiment shown in FIGS. 4 and 5 , the attracting voltage applied immediately after the regeneration of the electrostatic chuck 2 is made smaller than the attracting voltage applied immediately before the regeneration of the electrostatic chuck 2.

[0036] The clamping voltage is not limited to a voltage that changes linearly over time as shown in FIGS. 5 and 7. For example, the clamping voltage may be changed in steps as shown in FIG. 8. Similarly, the clamping voltage may be changed in a curved manner as shown in FIG. 9. Furthermore, a combination of these types of changes may also be used.

[0037] 10 is a flowchart illustrating a method for setting the clamping voltage. As in the electrostatic clamping methods described in the above embodiments, a relatively large clamping voltage Va (first clamping voltage) is applied in the wafer processing performed immediately before the regeneration of the electrostatic chuck 2 (process S1). Thereafter, if the electrostatic capacitance value falls below the reference value or the operation time of the wafer processing apparatus F exceeds the reference time, the regeneration process of the electrostatic chuck 2 is started (process S2). In the wafer processing performed immediately after the regeneration of the electrostatic chuck 2, an attracting voltage Vb (second attracting voltage) smaller than the first attracting voltage is applied (process S3).

[0038] The wafer support surface of the electrostatic chuck 2 is worn out by the regeneration process. Specifically, the dielectric layer that constitutes the wafer support surface is worn out. Due to the wear of the dielectric layer, the more times the electrostatic chuck 2 is regenerated, the stronger the clamping force becomes, even if the same clamping voltage is set after the regeneration.

[0039] FIG. 11 is a flowchart showing a method for setting the attracting voltage in consideration of the decrease in attracting force due to the number of times of regeneration. The processes with the same reference numerals as those in the flowchart of Fig. 10 are the same as those described in Fig. 10, and therefore will not be described again. In the flowchart of Fig. 11, after the playback process in process S2, it is determined whether the number of playbacks is below a reference value Z (process S4). Next, if the number of reproductions is below the reference value Z, the clamping voltage Vb (second clamping voltage) smaller than the first clamping voltage is applied, as in FIG. 10 (step S5). On the other hand, if the number of reproduction times is equal to or greater than the reference value Z, an attraction voltage Vc (a new second attraction voltage) smaller than the attraction voltage Vb is applied.

[0040] 11, the current number of reproductions is compared with a reference value Z, but multiple reference values ​​may be set as the comparison target. Each time the current number of reproductions becomes equal to or greater than one of the multiple reference values, the second clamping voltage is set to be smaller than the previously set clamping voltage. Note that "reducing the clamping voltage" means reducing the value of the clamping voltage by an absolute value that is unrelated to the polarity of the clamping voltage.

[0041] The electrostatic chuck to which the present invention is applied is not limited to the hyperbolic electrostatic chuck 2 illustrated in Fig. 1. For example, the present invention can be applied to electrostatic chucks of other conventionally known configurations, such as a monopolar type having one attracting electrode or a three-phase AC type having three attracting electrodes. In addition, in an electrostatic chuck having a plurality of chucking electrodes, the magnitude of the chucking voltage applied to the electrodes may be different for each electrode.

[0042] Furthermore, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0043] 1 Processing chamber 2. Electrostatic chuck 3a, 3b Adsorption electrode F Wafer processing equipment C Control device D Capacitance meter W wafer

Claims

1. a processing chamber for processing the wafer; an electrostatic chuck that attracts and supports the wafer in the processing chamber; an adsorption electrode built into the electrostatic chuck; a control device that sets an attraction voltage to be applied to the attraction electrode, the control device sets a second attracting voltage, which is lower than the first attracting voltage set during the wafer processing immediately before the regeneration process of the electrostatic chuck is performed, so that the magnitude of the attracting force generated by the electrostatic chuck falls within a predetermined allowable range, during the wafer processing immediately after the regeneration process of the electrostatic chuck is performed.

2. 2. The wafer processing apparatus according to claim 1, wherein the control device sets the attracting voltage so that a magnitude of an attracting force generated by the electrostatic chuck is substantially constant during wafer processing before and after performing a regeneration process on the electrostatic chuck.

3. 2. The wafer processing apparatus according to claim 1, further comprising a capacitance meter for measuring a capacitance between the wafer and the attraction electrode.

4. The control device 2. The wafer processing apparatus according to claim 1, wherein the second attracting voltage is changed to a smaller value when the number of times the electrostatic chuck has been regenerated is equal to or greater than a predetermined number.

5. a second attracting voltage that is smaller than a first attracting voltage that is applied to an attracting electrode of the electrostatic chuck during wafer processing immediately before performing a regenerating process of the electrostatic chuck, so that a magnitude of an attracting force generated by the electrostatic chuck falls within a predetermined allowable range during wafer processing before and after performing a regenerating process of the electrostatic chuck.

6. 6. The electrostatic attraction method according to claim 5, wherein the attracting voltage is applied to the attracting electrode so that the magnitude of the attracting force generated by the electrostatic chuck is substantially constant during wafer processing before and after performing the regeneration processing of the electrostatic chuck.

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