JP2005347545A - Electrostatic chuck device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic chuck device capable of suppressing wear of a surface of a suction stage projecting from a body to be sucked and sticking of reaction products even when the sucked body varies in size is handled. <P>SOLUTION: The electrostatic chuck device 101 comprises an electrostatic chuck stage 102, a power source 103 for an electrostatic chuck, and a changeover switch 104. Respective paired electrodes are arranged so that electrostatic charging regions do not project from a semiconductor wafer 5, and the changeover switch section 104 can apply voltages in pair units to switch the electrostatic regions in steps. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrostatic chuck device that is provided in a semiconductor manufacturing apparatus such as a plasma etching apparatus or an ion implantation apparatus and that electrostatically adsorbs a semiconductor wafer as an object to be adsorbed.

  FIG. 5 shows a cross-sectional view of a main part of a plasma etching apparatus as an example of a semiconductor device provided with a conventional electrostatic chuck device. Although there are two types of electrostatic chuck devices, a bipolar type and a single type, FIG. 5 shows a bipolar type electrostatic chuck device as an example.

  The plasma etching apparatus 1 mainly sucks and holds a vacuum chamber 2, a lower electrode 3 and an upper electrode 4 that are disposed opposite to each other, and a semiconductor wafer 5 that is disposed on the lower electrode 3 as an object to be adsorbed. And an RF power source 7 for generating plasma disposed outside.

  The vacuum chamber 2 is provided with a gas introduction port 8 for introducing a reactive gas and a gas exhaust port 9 for exhausting unnecessary gas. The upper electrode 4 is grounded, the lower electrode 3 is connected to the RF power source 7, and a high frequency voltage is applied to the lower electrode 3 to excite plasma in the space between the lower electrode 3 and the upper electrode 4.

  The plasma etching apparatus 1 is used in such a manner that the semiconductor wafer 5 is first placed on the electrostatic chuck apparatus 6 and electrostatically adsorbed, and then the inside of the vacuum chamber 2 is evacuated to react from the gas inlet 8. After introducing the property gas, the RF power source 7 is turned on to excite plasma in the space between the lower electrode 3 and the upper electrode 4. Then, the surface of the semiconductor wafer 5 is etched with ions or neutral radicals generated in the plasma. At this time, not only the semiconductor wafer 5 but also the surface of the electrostatic chuck device 6 that protrudes from the semiconductor wafer 5 is exposed to the plasma, and is undesirably etched and worn down.

  Then, after the plasma etching is completed, the RF power source 7 is turned off and unnecessary gas is exhausted from the gas exhaust port 9, and then the semiconductor wafer 5 is detached from the electrostatic chuck device 6. The above operation is repeated, and the plasma etching operation is sequentially performed on the next semiconductor wafer 5.

  Next, details of the configuration of the electrostatic chuck device will be described with reference to FIGS. 6 and 7 show a bipolar electrostatic chuck device, and FIG. 8 shows a unipolar electrostatic chuck device. 6A is a plan view, FIG. 6B is a side sectional view taken along line XX of FIG. 6A, and FIGS. 7 and 8 are side sectional views.

  First, as shown in FIG. 6, the bipolar electrostatic chuck device 6 includes an electrostatic chuck stage unit 10 and an electrostatic chuck power supply unit 11. The electrostatic chuck stage unit 10 is an assembly in which, for example, a pair of substantially semicircular flat plate electrodes 12 and 13 are separated from each other by a predetermined distance L1 (for example, several mm) and placed in an insulator 14 having a high dielectric constant. The electrostatic chuck power supply unit 11 is connected to the plate electrodes 12 and 13 and can apply a potential difference to the plate electrodes 12 and 13.

  The distance L1 is set to such a size that the opposing area between the flat plate electrodes 12 and 13 and the semiconductor wafer is not reduced so much that the withstand voltage between the flat plate electrodes 12 and 13 can be secured. Further, in order to obtain a sufficient Coulomb force, the insulator 14 on the surface side of the electrostatic chuck stage portion 10 on which the semiconductor wafer is placed is formed to be relatively thin.

  FIG. 7 shows the charged state and charged region of each part when the semiconductor wafer is attracted by such a bipolar electrostatic chuck device 6. When the electrostatic chuck power supply unit 11 is turned on and a DC voltage (for example, about 1 kv) is applied between the flat plate electrodes 12 and 13, the flat plate electrodes 12 and 13 are charged positively and negatively, respectively, and the insulator 14 thereon is Dielectric polarization is performed, and the semiconductor wafer 5 is electrostatically adsorbed using Coulomb force. In this case, the entire region almost directly above the plate electrodes 12 and 13 is a strong charged region.

  Next, as shown in FIG. 8, the monopolar electrostatic chuck device 15 includes a single plate electrode 16 (for example, a circle) inside the insulator 14, and the semiconductor wafer 5 is grounded. Yes. Then, the electrostatic chuck power supply unit 11 applies a DC voltage to the plate electrode 16 to charge it, dielectrically polarizes the insulator 14 thereon, and electrostatically attracts the semiconductor wafer 5 using Coulomb force. In this case, the region directly above the plate electrode 16 is a strong charged region.

  Here, the conventional bipolar or monopolar electrostatic chuck devices 6 and 15 as described above have the following two problems. First, the first problem is that the insulator 14 on the surface of the electrostatic chuck stage 10 protruding from the semiconductor wafer 5 is gradually etched and worn out during plasma etching.

  In particular, in the region protruding from the semiconductor wafer 5, the region where the plate electrodes 12, 13, and 16 are charged immediately below (region A in FIGS. 7 and 8) has a large amount of charge due to induction polarization, and thus plasma. As a result, the physical impact force of ions and radicals from the substrate increases, and there is a risk that the amount of depletion will increase as compared to the region where there is no plate electrode 12, 13, 16 charged immediately below (region B in FIGS. 7 and 8). It was. FIG. 9 schematically shows the difference in the amount of wear between the region A and the region B. FIG. 9A shows the case of the bipolar electrostatic chuck device 6, and FIG. 9B shows the case of the monopolar electrostatic chuck device 15.

  The second problem is that an electric field is generated in a region (region A) where the plate electrodes 12, 13 and 16 charged immediately below are present, and therefore there is no region where the plate electrodes 12, 13, and 16 charged directly below are present. Compared to (Region B), the reaction product 17 generated by plasma etching tends to adhere. FIG. 10 schematically shows the difference in the adhesion amount of the reaction product 17 in the region A and the region B. FIG. 10A shows the case of the bipolar electrostatic chuck device 6, and FIG. 10B shows the case of the monopolar electrostatic chuck device 15.

  Furthermore, when the depletion of the insulator 14 on the surface of the electrostatic chuck stage 10 as the first problem proceeds and the adhesion of the reaction product 17 as the second problem overlaps, FIG. As shown in FIG. 11B, in the case of the bipolar type, even if the withstand voltage between the flat plate electrodes 12 and 13 (interval L1 portion) is deteriorated or even in the case of the single pole type, As a result, the withstand voltage between the electrode 16 and the semiconductor wafer 5 may be deteriorated, and as a result, the electrostatic attraction force may be reduced.

As one means for solving such a problem, as shown in FIG. 12, there is a configuration in which the distance between the flat plate electrodes 12 and 13 below the region protruding from the semiconductor wafer 5 is partially enlarged (L1 <L2). Proposed. (For example, refer to Patent Document 1).
JP 2003-7811 A

  However, in such a configuration in which the distance between the plate electrodes 12 and 13 is partially enlarged, in addition to the fact that the dimensions are fixed, the withstand voltage can be increased by increasing the distance in the region where the plate electrodes 12 and 13 face each other. Although strengthening is possible, it cannot be said that it is sufficient because there is still a charged region protruding from the semiconductor wafer 5.

  In a conventional electrostatic chuck device, a region that protrudes from an object to be adsorbed and a region that has a charged plate electrode directly below has a large amount of charge due to induction polarization during processing such as plasma etching. The physical impact force of ions and radicals increases and the amount of wear increases, and the reaction product tends to adhere due to the electric field, and the pressure resistance between each plate electrode or between the plate electrode and the adsorbed material As a result, there is a possibility that the electrostatic attraction force is reduced.

  An object of the present invention is to provide an electrostatic chuck device capable of suppressing the depletion of the surface of the adsorption stage portion protruding from the object to be adsorbed and the adhesion of the reaction product even when handling the object to be adsorbed of various sizes. Is to provide.

  In the electrostatic chuck device of the present invention, a voltage is applied to an electrode disposed inside an insulator to be charged, and an electrostatic chuck device that electrostatically adsorbs an object to be attracted placed on the insulator. The electrostatic chuck device is variable according to the size of the object to be attracted.

  According to the electrostatic chuck device of the present invention, even when handling an object to be adsorbed of various sizes, it is possible to suppress the surface of the adsorption stage portion protruding from the object to be adsorbed, and the adhesion of the reaction product, It is possible to prevent the deterioration of pressure resistance between the electrodes or between the electrode and the object to be adsorbed, and as a result, the electrostatic attraction force can be maintained.

  The present invention aims at suppressing the desorption of the surface of the adsorption stage portion protruding from the adsorbed material and the adhesion of the reaction product even when handling the adsorbed material of various sizes. This was realized by changing the charging area according to the conditions.

  An example of the electrostatic chuck device of the present invention will be described with reference to FIGS. 1 and 2 show a bipolar electrostatic chuck device, and FIGS. 3 and 4 show a monopolar electrostatic chuck device. 1A is a plan view, FIG. 1B is a side sectional view taken along line XX in FIG. 1A, FIG. 2 is a side sectional view, FIG. 3A is a plan view, and FIG. (B) is a sectional side view taken along line XX in FIG. 3 (a), and FIG. 4 is a sectional side view.

  As shown in FIG. 1, the bipolar electrostatic chuck device 101 of the present invention includes an electrostatic chuck stage unit 102, an electrostatic chuck power source unit 103, and a changeover switch unit 104. Here, it is assumed that there are three types of sizes of the semiconductor wafer 5 to be handled, and an example in which the charging area is changed in three stages will be described.

  The electrostatic chuck stage unit 102 is an assembly in which a plurality of partial electrode groups 105a, 105b, 105c, 106a, 106b, and 106c are arranged in an insulator 14 having a high dielectric constant. The partial electrode 105a and the partial electrode 106a are assembled. Are symmetrically arranged in pairs (referred to as pair electrode 1) at a predetermined distance L1 in the center of the electrostatic chuck position, and the partial electrode 105b and partial electrode 106b are symmetrically arranged in pairs (outside the pair). Further, the partial electrode 105c and the partial electrode 106c are symmetrically arranged in pairs (referred to as the pair electrode 3) on the outside thereof.

  Here, each size of the three-stage charged region formed by the combination of each pair of electrodes (pair electrode 1, pair electrode 1 + pair electrode 2, pair electrode 1 + pair electrode 2 + pair electrode 3) has three kinds of sizes handled. Each pair of electrodes is arranged so as not to protrude from the semiconductor wafer 5. In addition, the space | interval L2 between each adjacent partial electrode is taken as the dimension which can insulate both.

  The electrostatic chuck power supply unit 103 is connected to each of the partial electrode groups 105a, 105b, 105c, 106a, 106b, and 106c, and the changeover switch unit 104 can apply a voltage to each paired electrode in pairs. The charging region can be switched stepwise by selecting a combination of paired electrodes and applying a voltage.

  For example, as shown in FIG. 2 (a), the bipolar electrostatic chuck apparatus 101 is used in a pair of forming a minimum charged region in the case of a small semiconductor wafer 5 (size A1). A voltage is applied only to the electrode 1 (105a, 106a) so that the charged region does not protrude from the semiconductor wafer 5.

  Next, in the case of a slightly larger semiconductor wafer 5 (size A2), as shown in FIG. 2B, the voltage is obtained by combining the pair electrode 1 (105a, 106a) and the pair electrode 2 (105b, 106b). Is applied so that the charged region does not protrude from the semiconductor wafer 5.

  In this way, the semiconductor wafer 5 is electrostatically adsorbed by applying a voltage while selecting a pair of electrodes so as not to protrude from the semiconductor wafer 5 handled by the charged region and to obtain the maximum charged region. Further, by eliminating the charged region that protrudes from the semiconductor wafer 5 in this way, it is possible to suppress undesired wear of the surface of the electrostatic chuck stage 102 and adhesion of reaction products during plasma etching or the like.

  In the above description, the example in which the size of the charged region is switched to three levels has been described. However, the present invention is not limited to this, and the number of pair electrodes may be changed according to the type of size of the semiconductor wafer to be handled. Further, the shape of each partial electrode is not particularly limited, and may be any shape as long as a desired electrostatic attraction force can be secured in terms of the area facing the semiconductor wafer 5.

  Next, as shown in FIG. 3, the single-pole type electrostatic chuck device 201 of the present invention includes an electrostatic chuck stage unit 202, an electrostatic chuck power source unit 203, and a changeover switch unit 204. Here, it is assumed that there are three types of sizes of the semiconductor wafer 5 to be handled, and an example in which the charging area is changed in three stages will be described.

  The electrostatic chuck stage unit 202 is an assembly in which a plurality of partial electrode groups 205a, 205b, and 205c are arranged in an insulator 14 having a high dielectric constant. A circular partial electrode 205a is formed at the center of the electrostatic chuck position. A donut-shaped partial electrode 205b is arranged on the outer side, and a donut-shaped partial electrode 205c is arranged concentrically on the outer side.

  Here, each size of the three-stage charged area formed by the combination of the partial electrodes (205a, 205a + 205b, 205a + 205b + 205c) is a size that does not protrude from the three types of semiconductor wafers 5 to be handled. Thus, each partial electrode is arrange | positioned. In addition, the space | interval L2 between each adjacent partial electrode is taken as the dimension which can insulate both.

  The electrostatic chuck power supply unit 203 is connected to each of the partial electrode groups 205a, 205b, and 205c, and the changeover switch unit 204 can apply a voltage to each partial electrode. Thus, the charging region can be switched stepwise by applying a voltage.

  For example, the method of using such a monopolar electrostatic chuck apparatus 201 forms a minimum charged region in the case of a small semiconductor wafer 5 (size A1) as shown in FIG. A voltage is applied only to the partial electrode 205 a so that the charged region does not protrude from the semiconductor wafer 5.

  Next, in the case of a slightly larger semiconductor wafer 5 (size A2), as shown in FIG. 4B, a voltage is applied by combining the partial electrode 205a and the partial electrode 205b so that the charged region is the semiconductor wafer 5 Do not stick out.

  Thus, the semiconductor wafer 5 is electrostatically adsorbed by applying a voltage while selecting a partial electrode so that the charged area does not protrude from the semiconductor wafer 5 to be handled and the maximum charged area is obtained. . In addition, by eliminating the charged region that protrudes from the semiconductor wafer 5 in this way, it is possible to suppress undesired wear of the surface of the electrostatic chuck stage 202 and adhesion of reaction products during plasma etching or the like.

  In the above description, the example in which the size of the charged region is switched in three stages has been described. However, the present invention is not limited to this, and the number of partial electrodes may be changed according to the type of size of the semiconductor wafer to be handled. Further, the shape of each partial electrode is not particularly limited, and may be any shape as long as the area facing the object to be attracted can secure a desired electrostatic attraction force.

  In the above description, the plasma etching apparatus has been described as the semiconductor manufacturing apparatus including the electrostatic chuck apparatus. However, the electrostatic chuck stage is not limited to the plasma etching apparatus but may be used in, for example, a processing apparatus such as an ion implantation apparatus by an ion beam. It goes without saying that the same effect can be obtained if the processing apparatus has a problem that the surface insulator is removed.

  INDUSTRIAL APPLICABILITY The present invention can be applied to an electrostatic chuck device that can suppress the desorption of the surface of the adsorption stage portion protruding from the adsorbed material and the adhesion of the reaction product even when handling the adsorbed material of various sizes. .

The top view and side sectional view of an example of the bipolar electrostatic chuck device of the present invention Side sectional view of an example of the bipolar electrostatic chuck device of the present invention The top view and sectional side view of an example of the monopolar electrostatic chuck apparatus of this invention Side sectional view of an example of a monopolar electrostatic chuck device of the present invention Cross-sectional view of the main part of a plasma etching apparatus equipped with a conventional electrostatic chuck device Plan view and sectional side view of a conventional bipolar electrostatic chuck device Side sectional view of an example of a conventional bipolar electrostatic chuck device Side sectional view of an example of a conventional monopolar electrostatic chuck device Explanatory drawing of problems in a conventional electrostatic chuck device Explanatory drawing of problems in a conventional electrostatic chuck device Explanatory drawing of problems in a conventional electrostatic chuck device Plan view of a conventional electrostatic chuck device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma etching apparatus 2 Vacuum chamber 3 Lower electrode 4 Upper electrode 5 Semiconductor wafer 6 Conventional electrostatic chuck apparatus 7 RF power source for plasma generation 8 Gas introduction port 9 Gas exhaust port 10 Electrostatic chuck stage unit 11 Power source for electrostatic chuck Portions 12 and 13 Plate electrode 14 Insulator 15 Conventional monopolar electrostatic chuck device 16 Single plate electrode 17 Reaction product 101 Bipolar electrostatic chuck device 102 Electrostatic chuck stage portion 103 Electrostatic of the present invention Power supply unit for chuck 104 Changeover switch unit 105a to 105c, 106a to 106c Partial electrode group 201 Monopolar electrostatic chuck device of the present invention 202 Electrostatic chuck stage unit 203 Power supply unit for electrostatic chuck 204 Changeover switch unit 205a to 205c Partial electrode group

Claims (6)

  In an electrostatic chuck apparatus that applies a voltage to an electrode disposed inside an insulator to be charged, and electrostatically attracts an object to be adsorbed placed on the insulator, the charging area is the size of the object to be adsorbed An electrostatic chuck device that is variable according to the conditions.   The electrostatic chuck device according to claim 1, wherein the charging region is a region that does not protrude from the object to be adsorbed when viewed from above the object to be adsorbed.   The electrostatic chuck apparatus according to claim 1, wherein the charging area is variable stepwise by the same number as the size of the object to be adsorbed.   The electrode is composed of a plurality of partial electrode groups to which a voltage can be individually applied, and an arbitrary partial electrode is selected from the partial electrode group and a voltage is applied to make the charging region variable. Item 4. The electrostatic chuck device according to any one of Items 1 to 3.   5. The electrostatic electrode according to claim 4, wherein in the case of a bipolar electrostatic chuck device, the partial electrode group is composed of a plurality of pairs of electrodes arranged symmetrically with respect to the center of the electrostatic chuck position. Chuck device.   In the case of a monopolar electrostatic chuck apparatus, the partial electrode group includes a circular electrode disposed at the center of the electrostatic chuck position, and at least one or more donut-shaped electrodes disposed so as to surround the concentric circle. The electrostatic chuck device according to claim 4, comprising:

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