JP2003179129A - Electrostatic chuck device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic chuck device in which the bonding force between an electrostatic chuck and a base plate is not deteriorated and contamination hardly occurs over a long period even when a resin-made adhesive is used in the device. <P>SOLUTION: This electrostatic chuck device is constituted by bonding the electrostatic chuck (5) to the base plate (3) through a bonding layer (7) composed of a silicon resin, and on the base plate (3), an insulating ring (1) is arranged so that the ring (9) is engaged with the outside end section of the chuck (5). The chuck (5) has a step part (chuck-side step part) (21) formed on its outer peripheral surface by partially reducing its diameter from the chucking surface (19) side, while the insulating ring (9) has a step part (ring-side step part) (23) formed on its inner peripheral surface by partially reducing its diameter from the base plate (3) side. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck device that can be used for fixing a semiconductor wafer in, for example, a dry etching device used when manufacturing a semiconductor wafer.

[0002]

2. Description of the Related Art Conventionally, in an electrostatic chuck, for example, in a semiconductor manufacturing apparatus, a semiconductor wafer (silicon wafer) which is an object to be adsorbed is fixed and processed such as dry etching, or a semiconductor wafer is adsorbed and fixed. It is used for the purpose of correcting warpage and adsorbing and transporting semiconductor wafers.

As the electrostatic chuck, for example, a disk-shaped ceramic insulator (dielectric) is provided with a suction surface (chuck surface) for attracting a semiconductor wafer on the surface thereof, and a single insulator is provided inside the insulator. It is known that an electrode or a pair of electrodes is embedded. When a semiconductor wafer is fixed by this electrostatic chuck (for example, one having a pair of electrodes), a high DC voltage is applied between the pair of electrodes to generate Coulomb force or Johnson-Rahbek force. The force is used to attract and fix the semiconductor wafer.

When the semiconductor wafer is attracted and fixed by the electrostatic chuck and well-known dry etching using plasma, for example, is performed, the temperature of the semiconductor wafer rises and it may not be possible to perform suitable etching. Therefore, techniques for cooling semiconductor wafers have been developed.

That is, since the degree of etching (etching rate) decreases as the temperature of the semiconductor wafer rises, an apparatus in which an aluminum base is bonded to the side opposite to the chuck surface of the electrostatic chuck for cooling the semiconductor wafer (hereinafter An electrostatic chuck device is used).

[0006]

When joining the aluminum base and the electrostatic chuck made of ceramic, a method of using indium having excellent thermal conductivity (Japanese Patent Laid-Open No. 9-45) is used.
However, it is not necessarily preferable in all respects.

That is, at the time of joining the electrostatic chuck and the aluminum base, it is necessary to raise the temperature to 250 ° C. or more in order to sufficiently melt the indium, but the thermal expansion of the electrostatic chuck made of ceramic and the alumina base. Since the coefficients are different, there is a problem that the surface of the electrostatic chuck is warped due to the difference in coefficient of thermal expansion after cooling.

As a countermeasure against this, there is a method of joining the electrostatic chuck and the aluminum base with an adhesive made of silicon resin. However, since silicon resin has weak plasma resistance, dry etching or the like is repeated for a long period of time. When,
There is a problem that the electrostatic chuck may peel off from the alumina base.

There is also a problem that impurities such as polysilicon and a cross-linking agent are generated from the silicone resin as contamination (dust). The present invention has been made to solve the above problems, and provides an electrostatic chuck device in which the bonding force does not decrease over a long period of time even when a resin adhesive is used and contamination is unlikely to occur. With the goal.

[0010]

Means for Solving the Problems and Effects of the Invention (1) The invention of claim 1 is an electrostatic chuck device in which an electrostatic chuck is bonded to a base member using a resin adhesive, and a side surface of the electrostatic chuck. In addition, the electrostatic chuck device is characterized in that a concave portion and / or a convex portion is provided in a ring shape along the outer periphery thereof, and an insulating ring is arranged so as to engage with the concave portion and / or the convex portion. Is the gist.

In the present invention, a ring-shaped concave or convex portion (hereinafter also referred to as a processed portion) is provided along the outer periphery of the side surface of the electrostatic chuck, and the insulating ring is arranged so as to engage with the processed portion. Therefore, the distance (creeping distance) from the chuck surface side of the electrostatic chuck to the joint portion with the resin adhesive is longer than that of the conventional one in which there is no processed portion on the outer periphery. Therefore, there is an effect that deterioration or peeling of the resin adhesive is unlikely to occur due to plasma during the dry etching.

That is, since the resin adhesive is not exposed to the plasma region, deterioration or peeling of the resin adhesive is small, and therefore even if the electrostatic chuck is used for a long period of time, the electrostatic chuck is difficult to peel off from the base member. There is an advantage. Further, since the resin adhesive is not exposed in the plasma region, it is possible to prevent impurities from being generated as contamination from the resin adhesive.

The term "engagement" used here means not only the state in which the electrostatic chuck side and the insulating ring side are in contact with each other at the processing portion, but also
This also includes a state in which the electrostatic chuck is in close proximity with a slight distance, and the configuration of the processed portion of the electrostatic chuck and the unevenness on the inner peripheral surface side of the insulating ring formed corresponding to the unevenness (however, the mating member It becomes a concave part for a convex part and a convex part for a concave part.)
Therefore, it is necessary to increase the creepage distance.

(2) In the invention of claim 2, the resin adhesive is
The electrostatic chuck device according to claim 1, wherein the electrostatic chuck device is one selected from silicon, polyimide, and epoxy. The present invention exemplifies a resin adhesive, and by using silicon, polyimide, epoxy, etc., it is adversely affected by the above-mentioned heating at the time of bonding (since it is not necessary to raise the temperature as in the case of conventional indium). Without this, the electrostatic chuck and the base member can be firmly joined.

(3) The invention according to claim 3 provides the electrostatic chuck device according to claim 1 or 2, characterized in that a step is formed as the concave portion and / or the convex portion. The present invention exemplifies a preferred shape of the concave portion and / or the convex portion, and if it is a step, not only the processing on the electrostatic chuck side but also the processing on the opposing insulating ring side is easy. .

(4) The invention according to claim 4 provides the electrostatic chuck device according to claim 3, wherein the step is a step having a small diameter on the chuck surface side of the electrostatic chuck. The present invention exemplifies the shape of the step. For example, as shown in FIG. 1, by making the chuck surface side of the electrostatic chuck a step having a small diameter, the insulating ring can be fitted from above in the figure. , Can be easily placed in the appropriate position.

(5) According to the invention of claim 5, the insulating ring is
An electrostatic chuck device according to claim 4, wherein a step (ring-side step) that engages with a step (chuck-side step) of the electrostatic chuck is provided along the inner circumference thereof.

The present invention exemplifies the shape of the insulating ring. For example, as shown in FIG. 1, the insulating ring is provided for a chuck-side step having a small diameter on the chuck surface side of the electrostatic chuck. By engaging the ring-side step with the chuck-side step so as to be fitted from above, the chuck-side step can be easily arranged at an appropriate position.

(6) According to the invention of claim 6, the insulating ring is
A ceramic ring, which is a ceramic ring.
The gist of any one of the electrostatic chuck devices is. The present invention exemplifies an insulating ring.

(7) According to a seventh aspect of the invention, the surface of the insulating ring on the side of the attracted member is 5 times larger than the chuck surface of the electrostatic chuck.
2. The diameter is reduced by 0 μm or more.
The gist is the electrostatic chuck device according to any one of 1 to 6.

In the present invention, since the surface of the insulating ring on the side of the member to be attracted is pulled down by 50 μm or more from the chuck surface of the electrostatic chuck when the insulating ring is arranged, for example, a semiconductor wafer is attracted and fixed to the chuck surface. In case,
This has the effect of preventing the semiconductor wafer from hitting the insulating ring and being damaged or displaced.

(8) The invention of claim 8 is characterized in that the outer diameter of the chuck surface of the electrostatic chuck is set to be smaller than the outer diameter of the attracted member to be attracted to the chuck surface. The gist is the electrostatic chuck device according to any one of items 1 to 7.

In the present invention, for example, as shown in FIG. 1, since the outer diameter of the chuck surface of the electrostatic chuck is set to be smaller than the outer diameter of the member to be attracted to the chuck surface, dry etching is performed. The creeping distance from the plasma region to the resin adhesive is long. Therefore, deterioration and peeling of the resin adhesive can be further prevented, so that peeling and contamination of the electrostatic chuck described above can be effectively prevented.

As the base member, it is possible to use a member made of metal having a thermal conductivity coefficient larger than that of the electrostatic chuck. For example, by using a metal base member made of aluminum, heat of the semiconductor wafer generated during dry etching can be quickly released.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example (embodiment) of an embodiment of an electrostatic chuck device of the present invention will be described. (Embodiment) Here, for example, an electrostatic chuck device in which an electrostatic chuck capable of adsorbing and holding a semiconductor wafer is joined to a base plate will be described as an example.

A) First, the structure of the electrostatic chuck device of this embodiment will be described. 1 is an explanatory view showing a cross section of the electrostatic chuck device and the semiconductor wafer, and FIG. 2 is an exploded perspective view of the electrostatic chuck device and the semiconductor wafer. Figure 1
As shown in FIG. 3, in the electrostatic chuck device 1 of the present embodiment, the disc-shaped electrostatic chuck 5 having a diameter smaller than that of the base plate 3 is joined to the disc-shaped base plate 3 by the joining layer 7 made of silicon resin. An insulating ring 9 is arranged on the base plate 3 so as to engage with the outer end of the electrostatic chuck 5.

The base plate 3 has a diameter of 350 mm, for example.
B. It is a plate material made of aluminum having a thickness of 20 mm, and is used to release heat from the semiconductor wafer 17 side through the electrostatic chuck 5. The electrostatic chuck 5 has a pair of internal electrodes 13 and 15 embedded in a ceramic substrate (insulator: dielectric) 11 made of, for example, an alumina sintered body. The surface (upper part in the figure) of the above is an adsorption surface (chuck surface) 19 for adsorbing and fixing the semiconductor wafer 17.

The electrostatic chuck 5 has, for example, a diameter of 300.
A disc-shaped plate material having a thickness of 3 mm and a thickness of 3 mm. Part) 21 is provided. The outer diameter of the chuck surface 19 of the electrostatic chuck 5 is the chuck surface 1
It is set to be smaller than the outer diameter of the semiconductor wafer 17 adsorbed on the substrate 9.

The electrostatic chuck 5 is provided with a heater electrode 22 (see FIG. 3) in order to correspond to a process requiring heat treatment.
(See) is buried. The insulating ring 9 is a ceramic insulator made of, for example, an alumina sintered body, and has a substantially L-shaped cross section (along the central axis). That is, the insulating ring 9 has, for example, an outer diameter of 350 mm ×
Although it is an annular member having an inner diameter of 294 mm and a thickness of 2 mm, a step portion (ring side step portion) 23 cut by 25 mm in the radial direction is provided along the inner peripheral surface from the base plate 3 side to the position 1 mm. ing.

Therefore, as shown in FIG.
By inserting the insulating ring 9 from above, the chuck side step portion 21 and the ring side step portion 23 as shown in FIG.
And (engage in contact or with a small gap). That is, the concave portion 25 on the outer peripheral surface of the electrostatic chuck 5 and the insulating ring 9
The convex portion 27 on the inner peripheral surface of the insulating chuck 9 is engaged with the convex portion 29 on the outer peripheral surface of the electrostatic chuck 5, and the concave portion 31 on the inner peripheral surface of the insulating ring 9 is engaged.

As a result, between the electrostatic chuck 5 and the insulating ring 9, the path from the chuck surface 19 side to the base plate 7 side becomes a bent path at two points, and the distance (creep distance) is set. It can be set long. In the present embodiment, the surface of the insulating ring 9 on the semiconductor wafer 17 side is 50 μm or more lower than the chuck surface 19 of the electrostatic chuck 5.

When the electrostatic chuck device 1 having the above-described structure is used, a ±
A direct current voltage of 1500 V is applied to generate a suction force (Coulomb force and Johnson-Rahbek force) for sucking the semiconductor wafer 17, and the semiconductor wafer 17 is sucked and fixed using this suction force.

Although not particularly shown, the electrostatic chuck device 1 is provided with a plurality of through holes penetrating in the vertical direction of FIG. 1, and a chuck surface 19 is provided with a groove connected to the opening of the through hole. A gas for cooling the semiconductor wafer 17 may be supplied to the chuck surface 19 side via the. The through hole can also be used when the semiconductor wafer 17 sucked and held on the chuck surface 19 is peeled from the chuck surface 19 by inserting a pin from the back side of the base plate 3.

B) Next, the electrostatic chuck device 1 of this embodiment.
The manufacturing method will be described with reference to FIG. First, a method of manufacturing the electrostatic chuck 5 will be described. (1) As raw materials, alumina powder as main component: 92% by weight, MgO: 1% by weight, CaO: 1% by weight, SiO
₂ : Mix 6% by weight, wet pulverize with a ball mill for 50 to 80 hours, and then dehydrate and dry.

(2) Next, this powder (as a ratio (outer weight%) to the powder) methacrylic acid isobutyl ester: 3% by weight, butyl ester: 3% by weight, nitrocellulose: 1% by weight, dioctyl phthalate: 0.5 wt% was added, and as a solvent, trichlor-ethylene,
Add n-butanol and mix in a ball mill to form a fluid slurry.

(3) Next, this slurry was degassed under reduced pressure, poured out into a flat plate and gradually cooled, and the solvent was diffused to a thickness of 0.
An 8 mm third alumina green sheet 37 is formed. (4) In addition, a ceramic component is slightly mixed with tungsten powder, and a slurry is prepared by the same method as described above to obtain a metallized ink.

(5) Then, the pattern 4 of the heater electrode 22 is formed on the third alumina green sheet 37 by the ordinary screen printing method using the metallized ink.
Print 1. (6) Next, the second alumina green sheet 35 manufactured in the same manner as the third alumina green sheet 37 is placed on the surface of the third alumina green sheet 37 on which the pattern 41 of the heater electrode 22 is printed.

(7) Next, the second alumina green sheet 3
An electrostatic chuck pattern, that is, the internal electrodes 13, 15 is formed on the surface of the electrode 5 by screen printing using a metallized ink using tungsten alone or a metallized ink in which tungsten and molybdenum are mixed to form a slurry.
The patterns 43 and 45 are printed.

(8) Next, the electrostatic chuck patterns 43, 4
The first alumina green sheet 33 and the fourth alumina green sheet 39, which are similar to each other, are laminated on the second alumina green sheet 35 on which the number 5 is printed and on the lower surface side of the third alumina green sheet 37, respectively, and thermocompression-bonded to each other, and the total thickness About 5
mm.

The internal electrodes 13, 15 are drawn out through the through holes 47, 49 from the back surface of the fourth alumina green sheet 39 in the lowermost layer, and terminals for applying a voltage to the internal electrodes 13, 15 (not shown). No) is provided. Similarly, the heater electrode 22 also has a through hole (not shown).

(9) Next, the thermocompression-bonded sheet is cut into a predetermined disc shape (for example, an 8-inch disc shape). (10) Next, the cut sheet is placed in a reducing atmosphere for 14
Bake at 00 to 1600 ° C. By this firing, the size is reduced by about 20%, so that the thickness of the fired ceramic body is about 4 mm.

(11) Then, after firing, the ceramic body is processed to have a total thickness of 3 mm and the chuck surface 19 has a flatness of 30 μm or less. Also,
By the cylindrical polishing, the diameter of the outer peripheral surface of the electrostatic chuck 5 on the chuck surface 19 side is reduced so that the chuck-side step portion 21 is formed.

(12) Next, the terminals are plated with nickel, and the nickel terminals are brazed or soldered. (13) Next, silicon resin is applied to the electrostatic chuck 5 side, the base plate 3 side, or both, and then the electrostatic chuck 5 and the base plate 3 are joined so that the axial centers thereof coincide with each other.
After that, the electrostatic chuck device 1 is completed.

Next, a method of manufacturing the insulating ring 9 will be described. Here, the disk-shaped quartz glass is polished to a predetermined thickness, and the flatness is set to 30 μm or less, and then the ring-shaped is formed by the machining process. Then, the insulating ring 9 manufactured as described above is fitted from above the electrostatic chuck device 1 and placed on the base plate 3. This allows
The chuck side step portion 21 of the electrostatic chuck 5 and the insulating ring 9
And the ring-side stepped portion 23 are engaged with each other.

C) Next, the effect of this embodiment will be described. In this embodiment, the chuck side step portion 21 of the electrostatic chuck 5 is used.
Since this is a structure in which the ring-side step portion 23 of the insulating ring 9 is engaged, the electrostatic chuck 5 has a structure different from that having no step.
The distance (creeping distance) from the chuck surface 19 side to the bonding layer 7 is long. Therefore, there is an effect that deterioration or peeling of the silicon resin is less likely to occur due to plasma during the dry etching.

That is, since the silicone resin is not exposed to the plasma region, the silicone resin is less deteriorated and peeled off.
Therefore, even if the electrostatic chuck 5 is used for a long period of time, there is an advantage that the electrostatic chuck 5 is hard to be peeled off from the base member 3. Further, since the silicon resin is not exposed to the plasma region, it is possible to prevent impurities from being generated from the silicon resin as contamination.

Further, the outer diameter of the chuck surface 19 of the electrostatic chuck 5 is the semiconductor wafer 1 attracted to the chuck surface 19.
Since it is set to be smaller than the outer diameter of 7, the creepage distance described above is also long, and thus the deterioration and peeling of the silicone resin can be further prevented and the electrostatic chuck 5
It is possible to effectively prevent the peeling and the occurrence of contamination.

Moreover, in this embodiment, the surface of the insulating ring 9 on the semiconductor wafer 17 side is more than 50 μm lower than the chuck surface 19 of the electrostatic chuck 5, so the semiconductor wafer 17 is fixed to the chuck surface 19 by suction. In this case, the semiconductor wafer 17 has the effect of not hitting the insulating ring 9 and being damaged or displaced.

Needless to say, the present invention is not limited to the above-mentioned embodiments, and can be carried out in various modes without departing from the gist of the present invention. (1) For example, in the above-described embodiment, a pair of internal electrodes is provided in the electrostatic chuck, but in addition to this, one electrode is embedded in the electrostatic chuck, and the embedded electrode and the object to be attracted (semiconductor). It is also possible to apply a voltage to the (wafer) side and cause the object to be adsorbed to the chuck surface by Coulomb force.

(2) The insulating ring is preferably an annular integral type, but it is also possible to combine a plurality of arcuate members and use them integrally. (3) The insulating ring can be placed on the base member, but it can also be placed on equipment other than the electrostatic chuck device.

(4) It is preferable that the step portion of the electrostatic chuck has a small diameter on the chuck surface side because it is easy to engage with the insulating ring, but other than that, for example, the base plate side has a small diameter. Good. In that case, the insulating ring may be composed of a plurality of parts, and may be arranged so as to be sandwiched, for example, from the left and right.

In the case of adopting such a structure, it is possible to increase the creepage distance by providing a ring-shaped concave portion (groove) or convex portion along the outer circumference of the electrostatic chuck in addition to the step. .

[Brief description of drawings]

FIG. 1 is an explanatory view showing an electrostatic chuck device and a semiconductor wafer of an embodiment in a broken manner.

FIG. 2 is an exploded perspective view of an electrostatic chuck device and a semiconductor wafer according to an embodiment.

FIG. 3 is an explanatory view showing the electrostatic chuck of the embodiment in an exploded manner.

[Explanation of symbols]

1 ... Electrostatic chuck device 3 ... Base plate 5 ... Electrostatic chuck 7 ... Bonding layer 9 ... Insulation ring 13, 15 ... Internal electrodes 17 ... Semiconductor wafer 19 ... Chuck surface 21, 23 ... stepped portion

Claims (8)

[Claims] 1. An electrostatic chuck device in which an electrostatic chuck is bonded onto a base member using a resin adhesive, and a concave portion and / or a convex portion is formed in a ring shape along the outer periphery of the side surface of the electrostatic chuck. And an insulating ring arranged so as to be engaged with the recess and / or the projection. 2. The electrostatic chuck device according to claim 1, wherein the resin adhesive is one selected from silicon, polyimide, and epoxy. 3. The electrostatic chuck device according to claim 1, wherein a step is formed as the concave portion and / or the convex portion. 4. The electrostatic chuck device according to claim 3, wherein the step has a small diameter on the chuck surface side of the electrostatic chuck. 5. The insulating ring, along its inner circumference,
The electrostatic chuck device according to claim 3, further comprising a step that engages with a step of the electrostatic chuck. 6. The electrostatic chuck device according to claim 1, wherein the insulating ring is a ceramic ring. 7. The electrostatic chuck according to claim 1, wherein the surface of the insulating ring on the side of the attracted member is pulled down by 50 μm or more from the chuck surface of the electrostatic chuck. apparatus. 8. The outer diameter of the chuck surface of the electrostatic chuck is set to be smaller than the outer diameter of a member to be attracted to the chuck surface.
7. The electrostatic chuck device according to any one of 7.