TW201824729A - Electrostatic chuck and manufacturing method of electrostatic chuck capable of maintaining an adsorption force relative to a workpiece more satisfactorily after stopping the electric power supply to an electrode - Google Patents

Abstract

The present invention provides an electrostatic chuck capable of maintaining an adsorption force relative to a workpiece more satisfactorily after stopping the electric power supply to an electrode. The bipolar electrostatic chuck holds the workpiece by a pair of comb-teeth electrodes disposed on the main surface side of a plate-like substrate. The comb-teeth electrode has a plurality of branch portions spaced apart from each other and arranged side by side, a backbone portion connected to the plurality of branch portions, and a backbone portion connected to a plurality of another branch portions. The pair of comb-teeth electrodes is disposed for allowing the branch portions to be alternately arranged and spaced apart from each other. The branch portion is formed by thick-width regions and the thin-width regions of electrodes having different widths, which are alternately arranged in the extending direction. Another branch portion is formed by thick-width portions and the thin-width regions of electrodes having different widths, which are alternately arranged in the extending direction. The thin-width region of the comb-teeth electrode on the other side is disposed adjacent to the thick-width region of the comb-teeth electrode on one side. The manufacturing method of the electrostatic chuck comprises steps of covering an insulating layer on the main surface side of the plate-like substrate, covering a metal layer on the insulating layer of the substrate to serve as an electrode, and forming a comb-teeth electrode by using a laser beam to leave a region used as the comb-teeth electrode and remove the metal layer. In the step of covering the insulating layer or the metal layer, the back surface side opposite to the main surface side of the substrate is also covered by the insulating layer or the metal layer. The method further comprises a step of forming a keep area on the insulating layer by covering the comb-teeth electrode to form the keep area for holding the workpiece after the step of forming the comb-teeth electrode.

Description

Electrostatic chuck and manufacturing method thereof

FIELD OF THE INVENTION The present invention relates to an electrostatic chuck and a method for manufacturing the same.

BACKGROUND OF THE INVENTION Conventionally, when various processing devices such as a CVD device, a grinding device, a laser processing device, and a tool cutting device are used to process a workpiece such as a semiconductor wafer, a protective member is attached to the workpiece so that Techniques for protecting a mounting surface of a protection member of a workpiece or preventing damage to the workpiece are known. Generally, a protective member is a so-called hard substrate made of glass or ceramic, which is attached with an adhesive tape such as a back grind tape, a dicing tape, or a wax. As described above, when the protective member is attached with an adhesive on the workpiece, it takes time to attach and peel the protective member to the workpiece. In addition, a part of the protective member may become disposable after use.

As a protective member that does not use an adhesive, there are an electrostatic chuck or a vacuum chuck. For example, Patent Document 1 discloses an electrostatic support disk including a disk body having a flat electrical insulating layer on which an electrode portion is embedded, and a disk body disposed on and adsorbed on a processed object (wafer). An elastic member in a region where the peripheral edge portion faces the electrically insulating layer. This electrostatic support disc is an electrostatic force generated by applying a voltage to an electrode portion to adsorb a workpiece to be disposed on an electrically insulating layer. Prior Art Literature Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2016-051836

Summary of the Invention The problem to be solved by the invention is to facilitate the handling of the workpiece during processing and transportation, etc. It is desirable that the electrostatic chuck has a stronger adsorption force so that the power supply to the electrode portion is stopped after the power supply to the electrode portion is stopped. Can still maintain the adsorption force on the workpiece. The electrostatic chuck described in the aforementioned Patent Document 1 is formed by flatly forming an electrical insulating layer that adsorbs a workpiece, or by forming an elastic member corresponding to a peripheral portion of the workpiece so as to prevent foreign matter from entering. The gap between the object to be processed and the electrostatic support plate obtains a strong adsorption force. However, there is still room for improvement in maintaining the adsorption force on the workpiece after the power supply to the electrode portion of the electrostatic chuck is stopped.

The present invention has been made in view of the above, and an object of the present invention is to provide an electrostatic chuck that can better maintain the adsorption force on a workpiece after power supply to an electrode is stopped. Means to solve the problem

In order to solve the above-mentioned problems and achieve the object, the present invention is a bipolar electrostatic chuck that holds a workpiece by a pair of comb-shaped electrodes set on the main surface side of a plate-like substrate, and the comb-shaped electrode is characterized in that: A plurality of branch portions are arranged side by side with a gap therebetween, and a backbone portion connecting the branch portions is provided. A pair of the comb-shaped electrodes are alternately alternated with each other and are set at intervals. The branch portion is extended. A thick area and a thin width area having different electrode thicknesses are alternately formed in the direction, and the fine width area of the comb-shaped electrode on the other side is arranged adjacent to the thick-width area of the comb-shaped electrode on one side.

In order to solve the above-mentioned problems and achieve the object, the present invention is the above-mentioned method for manufacturing an electrostatic chuck, which includes an insulating layer coating step of covering an insulating layer on a main surface side of a plate-shaped substrate, and the insulating layer on the substrate. A metal layer coating step for covering the metal layer as an electrode, and a comb electrode forming step for removing the metal layer by using laser light to leave a region that becomes the comb electrode.

In addition, it is preferable that in the insulating layer coating step or the metal layer coating step, the insulating layer or the metal layer is also coated on the back surface side of the substrate opposite to the main surface side.

Further, it is preferable to include a holding surface insulating layer coating step. The holding surface insulating layer coating step is to cover the comb-shaped electrode after the comb-shaped electrode forming step, thereby holding the holding surface of the workpiece. Surface insulation.

In addition, it is preferable that a planarization step is provided. The planarization step is performed by cutting a surface covered by the insulating layer coating step, the metal layer coating step, or the holding surface insulating layer coating step by a tool. flattened. Invention effect

The electrostatic chuck and the manufacturing method of the electrostatic chuck according to the present invention have the effect of being able to better maintain the adsorption force on the workpiece after the power supply to the electrode is stopped.

Embodiments for Implementing the Invention Embodiments (embodiments) for implementing the invention will be described in more detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the constituent elements described below include things that can be easily conceived by a person having ordinary knowledge in the technical field or substantially the same. In addition, the structures described below can be appropriately combined. Moreover, various structures can be omitted, replaced, or changed without departing from the gist of the present invention.

The electrostatic chuck and the manufacturing method of the electrostatic chuck according to the embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the electrostatic chuck 1 of the embodiment; FIG. 2 is a plan view showing the electrostatic chuck 1 of FIG. 1; and FIG. 3 is a cross-sectional view taken along line II-II in FIG. 2. FIG. 4 is an enlarged view showing a pair of comb-teeth electrodes 3 included in the electrostatic chuck 1. FIG. 5 is a perspective view showing a wafer W as a workpiece held by the electrostatic chuck 1 shown in FIGS. 1 to 3.

The electrostatic chuck 1 of the embodiment is a bipolar holding a wafer W (to-be-processed object) shown in FIG. 5 by a pair of comb-shaped electrodes 3 provided on the main surface 2a (see FIG. 3) of the plate-shaped substrate 2 Type of electrostatic chuck. In this embodiment, the wafer W is a disc-shaped semiconductor wafer and an optical element wafer using silicon, sapphire, gallium or the like as a base material. As shown in FIG. 5, the wafer W is formed with elements D in respective regions defined by a plurality of predetermined division lines S crossing the front surface WS. As the element D, IC (Integrated Circuit), LSI (Large Scale Integration), MEMS (Micro Electro Mechanical Systems), and the like can be formed in each region. The electrostatic chuck 1 according to this embodiment is used as a supporting member for supporting the wafer W in each step when a dicing process is performed in which the wafer W is divided into a plurality of element wafers along a plurality of predetermined division lines S. used.

As shown in FIGS. 1 and 2, the electrostatic chuck 1 of the embodiment is formed in a disc shape. The electrostatic chuck 1 may be formed in a rectangular shape. As shown in FIG. 3, the electrostatic chuck 1 includes the above-mentioned substrate 2 and the above-mentioned pair of comb-shaped electrodes (electrode circuits) 3, and includes: a metal layer 4, which is coated on the main surface 2 a side of the substrate 2 and is opposite to the main surface 2 a The back surface 2b side; the insulating layer 5 includes an inner insulating layer 5a covering the surface (main surface 2a, back surface 2b) of the substrate 2 and an outer insulating layer (holding surface insulating layer) 5b covering the metal layer 4; and The electrode terminal portion 6 is connected to a pair of comb-shaped electrodes 3. In addition, in FIG. 2, the description of the outer insulating layer 5 a is omitted for simplification of description.

The substrate 2 is a relatively rigid plate-shaped substrate formed of silicon, glass, quartz, or ceramic. In this embodiment, the substrate 2 is formed in a disc shape. The substrate 2 may be formed on a flat plate. The substrate 2 has, for example, a diameter of about 300 mm, and the substrate 2 has a thickness of about 100 μm to 800 μm.

The metal layer 4 is a coating film layer made of a metal material coated on the inner insulating layer 5a. In this embodiment, the metal layer 4 is a polyimide film (for example, a copper foil polyimide film made by UBE EXSYMO CO., LTD.) With a metal foil added to one side thereof. form. Moreover, in this embodiment, the metal layer 4 is formed flatly along the surface (main surface 2a, back surface 2b) of the substrate 2. The metal layer 4 on the main surface 2a side of the substrate 2 is formed by a laser ablation removal pattern to constitute a pair of comb-shaped electrodes 3. As shown in FIG. 3, the metal layer 4 is also covered on a part of the side surface 2 c of the substrate 2, and the metal layer 4 covered on the side surface 2 c forms the electrode terminal portion 6.

The pair of comb-shaped electrodes 3 includes a positive electrode 31 and a negative electrode 32. As shown in FIG. 2, the positive electrode 31 includes a plurality of branch portions 311 extending straight in one direction along the main surface 2 a of the substrate 2, and a stem portion 312 extending along the outer edge portion of the substrate 2. The plurality of branch portions 311 are arranged side by side with a gap from the outer edge portion 2d side of the substrate 2 on which the electrode terminal portion 6 is formed toward the opposite outer edge portion 2e side. Each branch portion 311 is connected to the backbone portion 312 at one end. As shown in FIG. 2 and FIG. 4, each branch portion 311 is formed in a comb-tooth shape, and a thick-width area 311 a and a thin-width area 311 b having different electrode thicknesses are formed alternately at a certain interval in the extending direction. In the present embodiment, the thick-width region 311a has a shape that expands into a circular shape from the thin-width region 311b.

As shown in FIG. 2, the negative electrode 32 includes a plurality of branch portions 321 extending straight in one direction along the main surface 2 a of the substrate 2, and a stem portion 322 extending along the outer edge portion of the substrate 2. The plurality of branch portions 321 are arranged side by side with a gap therebetween from the outer edge portion 2d side of the substrate 2 to the outer edge portion 2e side. Each branch portion 321 is connected to the base portion 322 at one end portion (the end portion opposite to the base portion 312 of the positive electrode 31). As shown in FIGS. 2 and 4, each of the branch portions 321 is formed in a comb-tooth shape, and the thick-width regions 321 a and the thin-width regions 321 b having different thicknesses of the electrodes are alternately formed at a predetermined interval in the extending direction. In the present embodiment, the thick-width region 311a has a shape that expands into a circular shape from the thin-width region 311b.

As shown in FIG. 2, the branch portions 311 and 321 of the positive electrode 31 and the negative electrode 32 alternately alternate with each other, and are set at intervals. That is, the positive electrode 31 and the negative electrode 32 are spaced apart from each other in sequence from the branch portion 311 of the positive electrode 31 and the branch portion 321 of the negative electrode 32 from the outer edge portion 2d side of the substrate 2 to the outer edge portion 2e side. The intervals come side by side.

As shown in FIGS. 2 and 4, the thin-width regions 311 b and 321 b of the comb-shaped electrode 3 on the other side are arranged adjacent to the thick-width regions 311 a and 321 a of the comb-shaped electrode 3 on one side. That is, the thick-width area 321 a of the branch portion 321 of the negative electrode 32 is arranged between the fine-width areas 311 b of the two branch portions 311 adjacent to each other of the positive electrode 31. Further, a thick-width region 311 a of the branch portion 311 of the positive electrode 31 is arranged between the thin-width regions 321 b of the two branch portions 321 of the negative electrode 32 adjacent to each other. Accordingly, the interval between the branch portion 311 of the positive electrode 31 and the branch portion 321 of the negative electrode 32 can be further shortened. In the present embodiment, the width D1 of the thick-width regions 311a and 321a is set to 0.3 mm, and the width D2 of the thin-width regions 311b and 321b is set to 0.133 mm. The interval P1 between the center of the branch portion 311 and the center of the adjacent branch portion 321 is 0.4 mm, and the interval P2 between the adjacent branch portion 311 and the branch portion 522 is 0.135 mm.

The insulating layer 5 is an insulating coating film that covers a metal layer 4 (a pair of comb-shaped electrodes 3) around the substrate 2. The insulating layer 5 is formed of, for example, a polyimide resin. As shown in FIG. 3, the insulating layer 5 includes an inner insulating layer 5a and an outer insulating layer (holding surface insulating layer) 5b. The inner insulating layer 5a is a part of the main surface 2a, the back surface 2b, and the side surface 2c covering the substrate 2. The outer insulating layer 5 b is coated on a metal layer 4 (a pair of comb-shaped electrodes 3) other than the electrode terminal portion 6. The outer insulating layer 5b covers a pair of comb-shaped electrodes 3. The outer insulating layer 5b is a holding surface 5c on which the wafer W is held. In this embodiment, the inner insulating layer 5a and the outer insulating layer 5b are formed flat along the surface (the main surface 2a or the back surface 2b) of the substrate 2.

As shown in FIGS. 1 and 3, the electrode terminal portion 6 is formed on a side surface 2 c of the substrate 2. The electrode terminal portion 6 includes a positive electrode terminal portion 6 a and a negative electrode terminal portion 6 b. The positive electrode terminal portion 6 a and the negative electrode terminal portion 6 b are disposed close to each other and disposed on the side surface 2 c of the substrate 2. In addition, the positive electrode terminal portion 6 a and the negative electrode terminal portion 6 b may be disposed at any position on the side surface 2 c of the substrate 2, or may be disposed on the main surface 2 a side of the substrate 2. As shown in FIG. 2, the positive electrode terminal portion 6 a is a stem portion 312 connected to the positive electrode 31, and the negative electrode terminal portion 6 b is a stem portion 322 connected to the negative electrode 32. The positive electrode terminal portion 6a applies a positive voltage from a power supply device (not shown), and the negative electrode terminal portion 6b applies a negative voltage from a power supply device (not shown).

When the wafer W is held by the electrostatic chuck 1, first, the wafer W is placed on the holding surface 5c of the outer insulating layer 5b. Then, when a positive voltage is applied to the positive electrode 31 through the positive electrode terminal portion 6a from a power supply device (not shown), and a negative voltage is applied to the negative electrode 32 through the negative electrode terminal portion 6b, the positive electrode 31 and Positive and negative charges are brought closer between the negative electrode 32 and the wafer W to generate an electrostatic force (Gradient force). By this electrostatic force, the wafer W can be attracted to the electrostatic chuck 1. Further, in the embodiment, the voltage applied to the pair of comb-shaped electrodes 3 through the electrode terminal portion 6 from a power supply device (not shown) is preferably 1000 V or more and 2000 V or less.

Next, the manufacturing method of the electrostatic chuck of this embodiment is demonstrated based on a figure. FIG. 6 is a flowchart showing a flow of a method for manufacturing an electrostatic chuck according to the embodiment. FIG. 7 is a cross-sectional view showing the substrate 2 of the electrostatic chuck 1 covered with the inner insulating layer 5a. FIG. 8 is a cross-sectional view showing a state where the inner insulating layer 5a is flattened. FIG. 9 is a cross-sectional view showing the substrate 2 of the electrostatic chuck 1 covered with the metal layer 4. FIG. 10 is a sectional view showing a state where the comb-shaped electrode 3 is formed. FIG. 11 is a sectional view showing a state where the wafer W is held by the electrostatic chuck 1.

As shown in the figure, the manufacturing method of the electrostatic chuck according to the embodiment includes an inner insulating layer coating step ST1, an inner insulating layer planarization step ST2, a metal layer coating step ST3, a comb electrode forming step ST4, an outer insulating layer coating step ST5, And an outer insulating layer planarization step ST6.

The inner insulating layer covering step ST1 is a step of covering the surface of the substrate 2 with the inner insulating layer 5a. As shown in FIG. 7, in the inner insulating layer coating step ST1, for example, a polyimide resin having insulation properties is applied to the entire main surface 2a, the back surface 2b, and the side surface 2c of the substrate 2 with a squeegee. One part and fixed by heating. Furthermore, in the inner insulating layer coating step ST1, a polyimide resin having insulation properties may be applied to the main surface 2a and the back surface 2b of the substrate 2 by spin coating.

The inner insulating layer planarization step ST2 is a step of planarizing the inner insulating layer 5a along the surface (the main surface 2a or the back surface 2b) of the substrate 2. As shown in FIG. 8, in the inner insulating layer planarization step ST2, an electrostatic clamp is placed on a work clamp table 101 of the cutting device 100 having a holding surface 101 a formed of porous ceramics or the like with a support member 110 interposed therebetween. The main surface 2a side or the back surface 2b side of the disc 1 described above. Next, a disc-shaped cutter wheel 104 of the cutting unit 102 of the cutting device 100 is used with a spindle 103 of the cutting unit 102 to drive an axis parallel to the vertical direction (upper and lower directions in the figure) with a drive motor (not shown). Way rotation drive. In addition, the cutting unit 102 is moved in a downward direction in the drawing by a processing feed mechanism (not shown), and the cutter wheel 104 and the work clamp table 101 are relatively moved in a direction parallel to the holding surface 101a, so that The cutting tool 105 of the cutting wheel 104 cuts the surface of the inner insulating layer 5a to flatten it. By cutting both the main surface 2a side and the back surface 2b side of the electrostatic chuck 1, the inner insulating layer 5a can be flattened. In addition, in the inner insulating layer flattening step ST2, the surface of the inner insulating layer 5a may be ground and flattened by a grinding stone of a grinding device (not shown).

The metal layer coating step ST3 is a step of coating the metal layer 4 as a pair of comb-shaped electrodes 3 on the inner insulating layer 5 a of the substrate 2. As shown in FIG. 9, in the metal layer coating step ST3, a metal foil is coated on the inner insulating layer 5 a that is covered on a part of the main surface 2 a, the back surface 2 b, and the side surface 2 c of the substrate 2 by heating and pressure bonding. Polyimide film. In the embodiment, the surface of the metal layer 4 (that is, the metal foil portion) can be flattened along the surface of the substrate 2 by using a polyimide film.

The comb-electrode formation step ST4 is to perform pattern removal on the metal layer 4 on the main surface 2a side of the substrate 2 by laser ablation to leave a region that becomes a pair of comb-electrodes 3 to form a pair of comb-electrodes 3 step. The comb-electrode forming step ST4 is performed using the laser processing apparatus 120. In the comb-electrode forming step ST4, first, the electrostatic chuck 1 (substrate 2) is transported to a work chuck 121 of a laser processing apparatus 120 having a holding surface 121a formed of a porous ceramic or the like, and supported therebetween. The member 110 sucks and holds the back surface 2b side of the substrate 2 on the work clamp table 121. Thereafter, as shown in FIG. 10, while the work chuck 121 and the laser light irradiation unit 122 of the laser processing device 120 are relatively moved, the laser light is irradiated from the laser light irradiation unit 122 to a predetermined position of the electrostatic chuck 1. Thereby, as shown in FIG. 10, the metal layer 4 is pattern-removed to form a pair of comb-shaped electrodes 3 shown in FIGS. 1 and 2. In addition, a metal foil polyimide film covering a part of the side surface 2 c of the substrate 2 forms the electrode terminal portion 6.

The outer insulating layer covering step (holding surface insulating layer covering step) ST5 is a step of covering the outer insulating layer 5b on the main surface 2a side and the back surface 2b side of the substrate 2. In the outer insulating layer coating step ST5, for example, a polyimide resin having insulating properties is applied to a pair of comb-shaped electrodes 3 and an inner insulating layer 5a formed on the main surface 2a of the substrate 2 with a doctor blade, and the It is fixed by heating. In addition, for example, a polyimide resin having insulating properties is applied to the metal layer 4 formed on the back surface 2b of the substrate 2 with a doctor blade, and is fixed by heating. Thereby, as shown in FIG. 3, both the main surface 2a side and the back surface 2b side of the substrate 2 can be covered with the outer insulating layer 5b. In addition, in the outer insulating layer coating step ST5, a polyimide resin having insulation properties may be applied to the pair of comb-shaped electrodes 3 and the metal layer 4 by spin coating.

The outer insulating layer planarization step ST6 is a step of planarizing the outer insulating layer 5b along the surface (the main surface 2a or the back surface 2b) of the substrate 2. In the outer insulating layer planarization step ST6, although not shown, the surface of the outer insulating layer 5b is ground using the cutting device 100 similarly to the inner insulating layer planarization step ST2. Thereby, as shown in FIG. 3, the outer insulating layer 5b can be planarized. With the above processing, the manufacturing of the electrostatic chuck 1 of this embodiment is completed. With the electrostatic chuck 1 manufactured in this way, as shown in FIG. 11, the back surface WR side of the wafer W can be held on the holding surface 5c of the outer insulating layer 5b to implement the division of the wafer W into a plurality of elements Each step includes dicing processing of a wafer, laser processing for forming a modified layer inside by laser light, and grinding processing for grinding the surface for thinning.

As described above, the electrostatic chuck 1 of this embodiment is a branch portion 311 of a positive electrode 31 constituting a pair of comb-shaped electrodes 3 having a thick width region 311 a and a thin width region 311 b, and constitutes a pair of comb-shaped electrodes 3. The branch portion 321 of the negative electrode 32 has a thick width region 321 a and a thin width region 321 b. Thereby, the respective branch portions 311 and 321 accumulate electric charges in a region where the thick width is changed to the thin width. As a result, each of the branch portions 311 and 321 can generate a strong electrostatic force (gradient force) in a region where the thick width is changed to the thin width, and the attractive force for attracting the wafer W can be further increased. In addition, even if the power supply to the pair of comb-shaped electrodes 3 is stopped, the temporarily generated charges can be maintained for a longer period of time, and the attractive force formed by the electrostatic chuck 1 can be maintained even after the power supply is stopped. . As a result, in each step after the wafer W is subjected to dicing or the like, it is not necessary to provide a power supply device to each device, and it is not necessary to supply power when the wafer W is transferred. Therefore, the slicing processing equipment of the wafer W can be simplified, and the operation processing during the processing or transportation of the wafer W can be made easier.

In the electrostatic chuck 1 of this embodiment, the thin-width regions 311b and 321b of the comb-shaped electrode 3 on the other side are arranged adjacent to the thick-width regions 311a and 321a of the comb-shaped electrode 3 on one side. Thereby, as described above, the interval between the branch portion 311 of the positive electrode 31 and the branch portion 321 of the negative electrode 32 can be further shortened and arranged. In this way, the distance between the positive electrode 31 and the negative electrode 32 can be narrowed, thereby making it possible to further increase the electrostatic force obtained by applying a voltage to the positive electrode 31 and the negative electrode 32. As a result, the attractive force of the electrostatic chuck 1 can be improved.

The manufacturing method of the electrostatic chuck 1 of this embodiment includes: an inner insulating layer covering step ST1 of covering the main insulating layer 5a on the main surface 2a side of the plate-like substrate 2; and covering the inner insulating layer 5a of the substrate 2 as a comb-shaped electrode. The metal layer coating step ST3 of the metal layer 4 of 3, and the comb electrode electrode forming step ST4 of the metal layer 4 is removed by using laser light to leave a region to become the comb electrode 3. In this way, a pair of comb-shaped electrodes 3 can be formed by pattern-removing the metal layer 4 by laser ablation to form a pair of comb-shaped electrodes 3 easily and inexpensively with high accuracy. Expected construction.

In the inner insulating layer coating step ST1, the inner insulating layer 5a is also coated on the back surface 2b side of the substrate 2 opposite to the main surface 2a side, and in the metal layer coating step ST3, the substrate 2 and the main surface are coated. The back surface 2b side opposite to the 2a side is also covered with the metal layer 4, and in the outer insulation layer coating step ST5, the back surface 2b side of the substrate 2 opposite to the main surface 2a side is also covered with the outer insulation layer 5a. As a result, compared with the case where the inner insulating layer 5a, the metal layer 4, and the outer insulating layer 5b are covered only on the surface 2a of the substrate 2, the stress acting on the substrate 2 can be laminated on the main surface 2a side and the back surface by laminating each layer. Type 2b equilibrium is formed. As a result, it becomes possible to suppress the deformation | transformation of the board | substrate 2 more favorably in the manufacturing method of the electrostatic chuck 1. However, the inner insulating layer 5a, the metal layer 4, and the outer insulating layer 5b may be omitted from the back surface 2b side of the substrate 2.

In addition, after the comb-electrode forming step ST4, an outer insulating layer coating step (holding surface insulating layer coating step) ST6 is provided, which covers the comb-shaped electrode 3 and forms a holding surface holding the wafer W (processed object). The outer insulating layer (holding surface insulating layer) 5b of 5c. This makes it possible to favorably hold the wafer W (to-be-processed object) by the holding surface 5c.

In addition, an inner insulating layer planarization step ST2 and an outer insulating layer planarization step ST6 are provided. The inner insulating layer planarization step ST2 is a method in which the surface of the inner insulating layer 5a coated on the substrate 2 in the inner insulating layer coating step ST1 is formed by a cutter. The outer insulating layer planarization step ST6 is performed by cutting with a tool to planarize. The outer insulating layer coating step (holding surface insulating layer coating step) ST5 is formed by cutting the surface of the outer insulating layer 5b with a tool. Perform flattening. As described above, the metal layer 4 is made of a polyimide film to which a metal foil is added, whereby the surface (metal foil portion) can be formed flat along the substrate 2. That is, the electrostatic chuck 1 of the present embodiment is formed with the inner insulating layer 5a, the metal layer 4, and the outer insulating layer 5b flatly along the surface of the substrate 2. Thereby, when the wafer W is placed on the electrostatic chuck 1, a gap cannot be formed between the wafer W and the holding surface 5c, and the adsorption force of the wafer W by the electrostatic chuck 1 can be further increased. In particular, by forming the outer insulating layer 5b forming the holding surface 5c of the holding wafer W flatly, it is possible to further improve the adsorption force. However, the inner insulating layer planarization step ST2 and the outer insulating layer planarization step ST6 may be omitted.

In this embodiment, after the inner insulating layer 5a is coated on the substrate 2 in the inner insulating layer coating step ST1, a polyfluorene-added polyimide is attached to the inner insulating layer 5a in the metal layer coating step ST2. A thin imine film is used to cover the metal layer 4 and the metal layer 4 is subjected to laser ablation processing in the comb electrode forming step ST4 to form a pair of comb electrode 3, but a metal layer 4 or a pair of comb electrode is formed The technique of 3 is not limited to this.

For example, the inner insulating layer coating step ST1 is omitted (the inner insulating layer 5a is omitted from the electrostatic chuck 1), and a double-sided tape is attached to the surface of the substrate 2 so as to be attached to the substrate 2 as a metal layer through the double-sided tape 4. Polyimide film with metal foil added is also acceptable.

The metal layer 4 may be a coating film made of a metal material, and it is not necessary to use a polyimide film to which a metal foil is added. For example, in the metal layer coating step ST3, the metal layer 4 may be coated on the inner insulating layer 5 by sputtering. Alternatively, the metal layer coating step ST3 and the comb-electrode forming step ST4 may be integrated steps, and the inner insulating layer 5 may be covered by screen printing or inkjet printing using solder made of a metal material, or the like. Thus, a metal layer 4 on the back surface 2a side of the substrate 2, a pair of comb-teeth electrodes 3, and an electrode terminal portion 6 are formed on the main surface 2a side of the substrate 2. As described above, when the metal layer 4 is formed by sputtering, screen printing, inkjet printing, or the like, a metal layer planarization step may be performed. The metal layer planarization step is performed by cutting the metal with the cutting device 100. The surface of the layer 4 is planarized.

The pair of comb-shaped electrodes 3 may be formed by performing photoetching on the metal layer 4. That is, in the comb-teeth electrode forming step ST5, first, a surface of the metal layer 4 is covered with a resist film, and a mask formed in advance along the pattern of the pair of comb-teeth electrodes 3 is used. A part of the resist film is pattern-removed by exposure, and the metal layer 4 is dry-etched or wet-etched through the pattern-removed photoresist film, thereby forming a pair of comb-shaped electrodes 3.

In addition, as long as the shape of the branch portions 311 and 321 of the pair of comb-shaped electrodes 3 is that the branch portion 311 of the positive electrode 31 has a thick width region 311a and a thin width region 311b, the branch portion 321 of the negative electrode 32 has a thick width region 321a and a thin The width region 321b, and the shape of the thin width regions 311b, 321b of the comb electrode 3 on the other side may be arranged adjacent to the thick width regions 311a, 321a of the comb electrode 3 on one side, and is not limited to this embodiment. As shown in the figure.

For example, in this embodiment, although the branch portions 311 and 321 of the comb-shaped electrode 3 are configured to extend straight in one direction along the substrate 2, each of the branch portions 311 and 321 may have a configuration of buckling or bending. . Moreover, in this embodiment, the formation interval between the thick width region 311a and the thin width region 311b and the formation interval between the thick width region 321a and the thin width region 321b are fixed. The formation interval may not be fixed.

12 to 16 are enlarged views showing the shape of a pair of comb-shaped electrodes 3 according to one modification. As shown in FIGS. 12 to 14, the thick area 311 a of the positive electrode 31 and the thick area 321 a of the negative electrode 32 may be formed in an oval shape. As shown in FIGS. 12 to 16, the width D1 of the thick width regions 311 a and 321 a, the width D2 of the thin width regions 311 b and 321 b, and the pitch P1 from the center of the branch portion 311 to the center of the adjacent branch portion 321. The distance P2 between the adjacent branch portions 311 and the branch portions 321 is not limited to the example shown in FIG. 4. The width D1 of the thick width regions 311a and 321a is preferably 0.3 mm to 0.6 mm, and the width D2 of the thin width regions 311b and 321b is preferably 0.1 mm to 0.6 mm. The interval P1 from the center of the branch portion 311 to the center of the adjacent branch portion 321 is preferably 0.4 mm or more and 1.0 mm or less. The interval P2 between the adjacent branch portion 311 and the branch portion 321 is 0.135. It is preferably at least 0.4 mm.

1‧‧‧ electrostatic chuck

2‧‧‧ substrate

2a‧‧‧Main face

2b‧‧‧ back

2c‧‧‧side

2d, 2e‧‧‧ outer edge

3‧‧‧comb electrode

31‧‧‧Positive electrode section

311, 321‧‧‧ branch

311a, 321a‧‧‧thick width area

311b, 321b‧‧‧‧thin width area

312, 322‧‧‧ cadres

32‧‧‧ negative electrode

4‧‧‧ metal layer

5‧‧‧ Insulation

5a‧‧‧Inner insulation layer

5b‧‧‧outer insulation

6‧‧‧ electrode terminal

6a‧‧‧Positive electrode terminal section

6b‧‧‧Negative electrode terminal

100‧‧‧ cutting device

101、121‧‧‧Work clamp

101a, 121a, 5c‧‧‧

102‧‧‧cutting unit

103‧‧‧ Spindle

104‧‧‧Cutter wheel

105‧‧‧Tools

110‧‧‧ support member

120‧‧‧laser processing device

122‧‧‧Laser light irradiation section

D1, D2‧‧‧Width

P1, P2‧‧‧interval (pitch)

W‧‧‧ Wafer

WS‧‧‧Front

WR‧‧‧Back

ST1 ~ ST6‧‧‧‧steps

FIG. 1 is a perspective view showing an electrostatic chuck according to the embodiment. FIG. 2 is a plan view showing the electrostatic chuck of FIG. 1. FIG. FIG. 3 is a cross-sectional view taken along the line II-II in FIG. 2. FIG. 4 is an enlarged view showing a pair of comb-shaped electrodes included in the electrostatic chuck. FIG. 5 is a perspective view showing a wafer as a workpiece held by an electrostatic chuck. FIG. 6 is a flowchart showing a flow of a method for manufacturing an electrostatic chuck according to the embodiment. FIG. 7 is a cross-sectional view showing a substrate with an electrostatic chuck covered with an inner insulating layer. FIG. 8 is a cross-sectional view showing a state where the inner insulating layer is planarized. 9 is a cross-sectional view showing a substrate of an electrostatic chuck covered with a metal layer. FIG. 10 is a sectional view showing a state where a comb-shaped electrode is formed. FIG. 11 is a sectional view showing a state where a wafer is held by an electrostatic chuck. FIG. 12 is an enlarged view showing the shape of a pair of comb-shaped electrodes according to a modification. FIG. 13 is an enlarged view showing the shape of a pair of comb-shaped electrodes according to a modification. FIG. 14 is an enlarged view showing the shape of a pair of comb-shaped electrodes according to a modification. FIG. 15 is an enlarged view showing the shape of a pair of comb-shaped electrodes according to a modification. FIG. 16 is an enlarged view showing the shape of a pair of comb-shaped electrodes as a modification.

Claims (5)

An electrostatic chuck is a bipolar electrostatic chuck that holds a pair of comb-shaped electrodes on one of the main surfaces of a plate-shaped substrate to hold a workpiece. The electrostatic chuck is characterized in that: the comb-shaped electrodes have: For the plurality of branch portions arranged side by side and the backbone portion connecting the plurality of branch portions, one pair of comb-shaped electrodes is set alternately with the branch portions alternately and spaced apart, and the branch portions are arranged in the extending direction. Thickness regions having different electrode thicknesses are alternately formed with the thin width regions, and the thin width regions of the comb-shaped electrodes on the other side are arranged adjacent to the thick width regions of the comb-shaped electrodes on one side. A manufacturing method of an electrostatic chuck as claimed in claim 1, comprising: an insulating layer coating step, covering the insulating layer on the main surface side of the plate-shaped substrate; a metal layer coating step, covering the insulating layer of the substrate as an electrode A metal layer; and a step of forming a comb-shaped electrode, removing the metal layer by leaving a region where the laser beam becomes the comb-shaped electrode. The manufacturing method of the electrostatic chuck according to claim 2, wherein in the insulating layer coating step or the metal layer coating step, the insulating layer or the metal layer is also coated on the back surface side of the substrate opposite to the main surface side. . For example, the method for manufacturing an electrostatic chuck according to claim 2 or 3, further comprising a holding surface insulating layer coating step. The holding surface insulating layer coating step is to cover and cover the comb tooth electrode after the comb electrode forming step to hold the comb electrode. Holding surface insulation layer on the holding surface of the workpiece. For example, the method for manufacturing an electrostatic chuck according to claim 2 or 3, further comprising a planarization step, wherein the planarization step includes cutting with a tool in the insulating layer coating step, the metal layer coating step, or the holding surface insulating layer coating step. The covered surface is flattened.