JP2000243820A - Electrostatic chuck and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit the aegreasing and suppress the generation of worpage by containing conductive metal silicide into the electrode layer of electrostatic chuck consisting of ceramic dielectric body layer, electrode layer and ceramic base body. SOLUTION: As the raw material for a dielectric layer 1 of an electrostatic chuck, an alumina material ceramics, an aluminum nitride material ceramics or the like is used, as the raw material for an insulator substrate 3, an alumina, an aluminum nitride, a silicon nitride or the like can be used and when a compound layer of the same main component as that of the layer 1 is used, the generation of a warpage of an electrode layer 2 and a crack in the layer 2 due to the reaction of the layer 1 to the substrate 3 and a difference between the shrinkage factors of the layer 1 and the substrate 3 at the time of a firing can be prevented. As the conductive material for the layer 2, a paste containing a conductive metal silicide of a high oxidation resistance is pasted on a molded material consisting of the raw material for the layer 1 or the substrate 3 by a screen printing or the like. The molded material consisting of the raw material for the layer 1 and the molded material consisting of the raw material for the substrate 3 are superposed holding the layer 2 between both molded materials and after a degreasing of the molded materials is performed in the atmosphere, the molded materials are set on a hot press device and the molded materials are integrally fired by pressing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck for electrostatically holding and transporting a wafer or the like in a semiconductor manufacturing apparatus or the like.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing apparatus,
When performing film formation processing or etching processing on an i-wafer or the like, it is necessary to hold the wafer while maintaining its flatness. As such holding means, a mechanical holding method, a vacuum suction method, and an electrostatic suction method have been proposed. ing. Of these, the electrostatic chuck method is a method of holding a wafer by an electrostatic chuck,
It has been widely used because of its excellent flatness of the wafer processing surface and its use in vacuum.

Conventional electrostatic chucks include those utilizing Coulomb force as an attraction force and those utilizing Johnsen-Rahbek force. As an electrostatic chuck utilizing Coulomb force, CaTiO ₃ , PbTiO ₃ -La ₂ are used as dielectrics.
There are those using an O ₃ system or the like (for example,
517, etc.).

[0004] The Johnsen-Rahbek force is a force generated when a minute current flows through a small gap at an interface between a dielectric and a wafer, and is induced by charging and polarization. ¹² to 10 ¹³ Ω · c
m. Al ₂ O ₃ -T is used as a dielectric for an electrostatic chuck utilizing the Johnsen-Rahbek force.
Ceramics in which a transition metal element is added to alumina, such as iO ₂ , or ceramics containing AlN as a main component are used (for example, Japanese Patent Publication No. 6-97675;
-16044, JP-A-8-55899).

[0005] As a method of manufacturing the electrostatic chuck, an electrode layer is formed by printing, plating, or the like on one of a dielectric and an insulating base made of ceramic which has been molded and fired in advance. There is a method of bonding a substrate. However, in this method, the dielectric and the insulator base must be separately processed and bonded, and the processing cost is high.
Further, since the heat resistance of the adhesive is lower than that of the ceramic, there is a problem that the usable temperature is determined by the physical properties of the adhesive.

As a method for solving this problem, as a method of manufacturing an electrostatic chuck, a dielectric molded body made of a ceramic raw material formed in advance, instead of bonding a dielectric made of a ceramic fired in advance and an insulating substrate. There is a manufacturing method of integrally firing the and the insulator base body.

[0007]

An example of a typical method of manufacturing an electrostatic chuck by integral firing will be described. A ceramic raw material slurry to which a binder and a dispersant are added is tape-formed. Laminating the obtained ceramic sheets,
A high-melting point metal such as W or Mo is printed on the laminate as an electrode material by screen printing or the like, and another laminate of ceramic sheets is laminated, pressed, and then integrally fired under normal pressure to manufacture. It is common.

In such a manufacturing method, when the carbon content of the binder and the dispersant contained in the molded product and the printed electrode layer remains during firing, the electric resistance of the dielectric material is extremely lowered, The disadvantage that the leakage current to the adsorbent during use becomes large occurs.

To avoid such inconvenience, usually,
After removing the carbon content in the binder and the dispersant by degreased the molded body, firing is performed.

[0010] Degreasing is performed in an inert atmosphere such as argon or nitrogen. This is because, since the electrode material contained in the electrode layer is fine particles, if it is degreased at a temperature of about 500 ° C. in the air, it will be oxidized and will not function as an electrode.

However, when degreasing is performed in an inert atmosphere, it is difficult to stably remove the carbon content, and the electrical resistance of the obtained dielectric material tends to vary.

In addition, in such a method, it is inevitable that the internal electrode is warped by 50 to 200 μm or more in the firing step, and the distance between the suction surface and the internal electrode is not constant, so that the suction force is not sufficient. There was a problem of becoming uniform. Furthermore, in the manufacture of a large electrostatic chuck having a wafer size of 12 inches or more, the warpage becomes extremely large.
There has also been a problem that the manufacturing yield is significantly reduced.

[0013]

As a method for stabilizing the electric resistance of a dielectric and reducing the warpage of a molded body during firing, a conductive metal silicide having high oxidation resistance is used. By using the electrode material, degreasing in the atmosphere is possible, and it is found that warping can be remarkably suppressed by performing integrated firing by hot pressing instead of conventional integrated firing under normal pressure. It was completed. That is, the present invention is as follows. (1) An electrostatic chuck comprising a ceramic dielectric layer, an electrode layer, and a ceramic substrate, wherein the electrode layer contains a conductive metal silicide. (2) The conductive metal silicide is TaSi ₂ , NbSi ₂ , WS
The electrostatic chuck according to item (1), wherein the electrostatic chuck comprises one or more selected from i ₂ and MoSi ₂ . (3) The electrostatic chuck according to any one of (1) to (3), wherein the main composition of the dielectric and the base is the same compound. (4) The electrostatic chuck according to any one of (1) to (3), wherein the ceramic dielectric is an alumina ceramic. (5) The electrostatic chuck according to (4), wherein the dielectric is alumina to which TiO ₂ is added. (6) The electrostatic chuck according to item (4), wherein the dielectric is alumina to which Ti ₂ O ₃ is added. (7) The electrostatic chuck according to (1) or (2), wherein the dielectric is an aluminum nitride ceramic. (8) In a method for manufacturing an electrostatic chuck including a ceramic dielectric layer, an electrode layer, and a ceramic substrate, a molded body (A) of a dielectric material and a molded body (B) of an insulating substrate material are formed and then molded. After applying a paste containing a conductive metal silicide as an electrode material to one main surface of the body (A) and / or the molded body (B), the molded body and the electrode paste are degreased in an air atmosphere, and then, A method for manufacturing an electrostatic chuck, comprising: laminating an electrode layer between a compact (A) and a compact (B) so as to be sandwiched between them; (9) The conductive silicide is TaSi ₂ , NbSi ₂ , WS
The method for manufacturing an electrostatic chuck according to item (8), comprising one or more selected from i ₂ and MoSi ₂ . (10) The method according to (8) or (9), wherein at least one of the molded body (A) of the dielectric raw material and the molded body (B) of the insulating substrate raw material is manufactured by CIP molding. Manufacturing method of electrostatic chuck (11) wherein at least one of the molded body (A) of the dielectric raw material and the molded body (B) of the insulating substrate raw material is produced by doctor blade molding (8) or (9) The method for manufacturing the electrostatic chuck according to the item (9). (12) The electrostatic chuck according to any one of the items (8) to (11), wherein the main composition of the dielectric and the base is the same compound. (13) The method for manufacturing an electrostatic chuck according to any one of (8) to (12), wherein the ceramic dielectric is an alumina ceramic. (14) TiO ₂ is added to the dielectric. Alumina Wherein (13) the production method of the electrostatic chuck according to (13), characterized in that the electrostatic method of manufacturing a chuck (15) dielectric according is alumina with the addition of Ti ₂ O ₃ in terms . (16) The method for manufacturing an electrostatic chuck according to any one of (8) to (12), wherein the dielectric is an aluminum nitride ceramic.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, by using a conductive metal silicide having high oxidation resistance as an electrode material, degreasing in an air atmosphere becomes possible, and carbon can be stably removed. .

Metal silicide may be used alone as the conductive material of the electrode, but additives such as frit may be added for the purpose of improving sinterability, adjusting the coefficient of thermal expansion, and the like.

As the conductive metal silicide, TaS
When i ₂ , NbSi ₂ , WSi ₂ , and MoSi ₂ are used, the coefficient of thermal expansion and the melting point are close to those of ceramics used as a dielectric or a base, particularly, an alumina-based ceramic. More preferred.

Known dielectric ceramics can be used as the dielectric, and alumina ceramics, aluminum nitride ceramics, and the like are used as described in claims 4 to 7. In the case of alumina ceramics, TiO
_2. By adding a transition metal oxide such as Ti ₂ O ₃ , the volume resistivity of the dielectric can be controlled in the range of 10 ⁹ to 10 ¹³ Ω · cm, and a strong adsorption force due to the Johnsen-Rahbek force is developed. Alumina, aluminum nitride, silicon nitride, and the like can be used as the insulator substrate. As shown in claims 3 and 12, when a compound having the same main composition as the dielectric is used, the dielectric during firing, Troubles such as warpage and cracks due to a reaction between insulator substrates and differences in shrinkage can be prevented, which is more preferable. Here, the term "main composition is the same" means that the ceramics have substantially the same firing shrinkage behavior and thermal expansion coefficient. Therefore, in the case of alumina and aluminum nitride, as long as the firing shrinkage behavior and the coefficient of thermal expansion are substantially the same, there may be a slight difference in the type and amount of the auxiliary agent to be added. For the molded body of the dielectric and insulator substrates, a binder, a dispersant, etc. are added to the raw material powder, and CI
Those manufactured by P (hydrostatic pressure) molding, press molding, doctor blade molding, or the like are used. The electrode is formed by applying a paste containing the above-described material on a molded body of a dielectric or insulating substrate by screen printing or the like.
After sandwiching the electrodes, the molded bodies of the dielectric and insulator substrates are superimposed, degreased in the air, and then set in a hot press apparatus, followed by pressurized integrated firing. The fired sample is processed into a predetermined shape to complete an electrostatic chuck. If the warpage during firing does not cause much problem, firing may be performed integrally at normal pressure instead of hot press firing. Further, when forming the suction portions on both surfaces, the dielectric molded body may be superposed on the upper and lower surfaces of the molded body of the insulator substrate, and then degreasing and integral firing may be performed.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.

(Example 1) 5% by weight of TiO ₂ powder was added to α-Al ₂ O ₃ powder, distilled water, a binder, and a dispersant were added, followed by ball mill mixing. The slurry was granulated with a spray drier to obtain granulated powder having a particle size of about 70 μm. Two of these were disc-shaped and CIP-molded to obtain molded bodies of dielectric and insulator substrates, respectively. TaSi on dielectric compact
After screen printing of the _two pastes, the molded bodies of the insulating substrates were overlaid. After degreasing in the air at 500 ° C., it is set in a hot press, and 1500 ° C. in an argon gas.
It baked under pressure at 30 MPa for 2 hours. Grinding the dielectric part of the obtained sintered body to a thickness of 300 μm,
Further, the whole was processed into a disk shape having a diameter of 200 mm and a thickness of 5 mm. A hole having a diameter of 5 mm was made in the insulator portion, and a lead electrode was connected thereto, thereby producing an electrostatic chuck as shown in FIG.

When the electric resistivity of the dielectric material of this electrostatic chuck was measured, it was stable at 1 × 10 ¹¹ Ωcm. A DC voltage of 500 V was applied to this electrostatic chuck in a vacuum for 20 seconds, and the suction force when the silicon wafer was sucked was measured. As a result, a uniform suction force of 4500 g / cm ² was shown. The electrostatic chuck was cut, and the warpage of the internal electrode was measured. As a result, it was found that the warpage was extremely small at a maximum of 11 μm.

Example 2 Y ₂ O ₃ was used as a sintering aid.
0 wt% AlN powder, ethanol, binder,
The ball mill was mixed with the dispersant. The slurry was granulated with a spray drier to obtain granulated powder having a particle size of about 50 μm. Two pieces of this were CIP-molded into a disk shape in the same manner as in Example 1 to obtain molded bodies of dielectric and insulator substrates, respectively. After screen printing the NbSi ₂ paste onto the molded body of the dielectric, superposed compact of the insulator substrate. 500 ° C,
After degreased in the air, it was set in a hot press and baked under pressure at 1850 ° C. and 30 MPa for 2 hours in nitrogen. The dielectric portion of the obtained sintered body is ground to a thickness of 300 μm, and the entire body is 200 mm in diameter and 5 mm in thickness.
Was processed into a disk shape. A hole having a diameter of 5 mm was made in the insulator portion, and a lead electrode was connected thereto, thereby producing an electrostatic chuck as shown in FIG. When the electrical resistivity of the dielectric material of this electrostatic chuck was measured at 300 ° C., it was stable at 1.1 × 10 ¹⁰ Ωcm. A DC voltage of 500 V was applied to this electrostatic chuck in a vacuum for 20 seconds, and the suction force when the silicon wafer was suctioned was measured. As a result, 4800 g / cm ^{2 was obtained.}
Showed a uniform adsorption force. The electrostatic chuck was cut, and the warpage of the internal electrode was measured. As a result, it was found that the warpage was as small as 10 μm at the maximum.

Example 3 0.5% of α-Al ₂ O ₃ powder
Weight% of Ti ₂ O ₃ powder, distilled water, acrylic binder and dispersant were added and mixed with a ball mill.
A slurry of 000 cP was obtained. This was molded into a doctor blade and then dried to obtain a sheet molded body having a thickness of about 300 μm. This was laminated on several sheets at a time, and cut into a disk to obtain a molded body of a dielectric or insulator substrate. After the WSi ₂ paste was screen-printed on the insulator substrate compact, the insulator substrate compact was laminated and pressed. After degreasing in air at 500 ° C., 1600 in argon atmosphere in an atmosphere firing furnace.
It baked at normal pressure for 4 hours. The dielectric portion of the obtained sintered body was ground so as to have a thickness of 2 mm, and the whole was further processed into a disk shape having a diameter of 300 mm and a thickness of 4 mm. A hole having a diameter of 5 mm was made in the insulator portion, and a lead electrode was connected thereto to manufacture an electrostatic chuck.

When the electric resistivity of the dielectric material of the electrostatic chuck was measured, it was stable at 1 × 10 ¹¹ Ωcm. A DC voltage of 500 V was applied to this electrostatic chuck in a vacuum for 20 seconds, and the suction force when the silicon wafer was sucked was measured. As a result, the suction force was 4300 g / cm ^{2 on} average. When the electrostatic chuck was cut and the warpage of the internal electrode was measured, the warp was 150 μm at the maximum, which was larger than in Examples 1 and 2, but functioned without any problem as an electrode layer.

For comparison, a laminate formed of a dielectric, an electrode, and an insulator substrate manufactured by the same method as above was degreased at 500 ° C. in the air, and the electrode material was oxidized. It did not function as an internal electrode.

[0025]

As described above, the use of the electrostatic chuck of the present invention and the method of manufacturing the same makes it possible to obtain a high-performance electrostatic chuck having a uniform suction force, which is extremely useful in industry.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a cross section of an electrostatic chuck according to the present invention.

[Explanation of symbols]

 1. 1. dielectric layer Electrode layer 3. 3. Insulator substrate Lead electrode 5. Adherend

Claims (16)

[Claims] 1. An electrostatic chuck comprising a ceramic dielectric layer, an electrode layer and a ceramic substrate, wherein the electrode layer contains a conductive metal silicide. 2. The conductive metal silicide is TaSi ₂ , NbS.
i _2, WSi _2, 1 kind selected from MoSi ₂ or 2
The electrostatic chuck according to claim 1, wherein the electrostatic chuck comprises at least one kind. 3. The electrostatic chuck according to claim 1, wherein the main composition of the dielectric and the base is the same compound. 4. The electrostatic chuck according to claim 1, wherein the ceramic dielectric is an alumina ceramic. 5. The electrostatic chuck according to claim 4, wherein the dielectric is alumina to which TiO ₂ is added. 6. The electrostatic chuck according to claim 4, wherein the dielectric is alumina to which Ti ₂ O ₃ is added. 7. The electrostatic chuck according to claim 1, wherein the dielectric is an aluminum nitride ceramic. 8. A method of manufacturing an electrostatic chuck comprising a ceramic dielectric layer, an electrode layer, and a ceramic substrate, wherein a molded body (A) of a dielectric material and a molded body (B) of an insulating substrate material are provided.
And then applying a paste containing a conductive metal silicide as an electrode material to one main surface of the formed body (A) and / or the formed body (B), and then forming the formed body and the electrode in an air atmosphere. The paste is degreased, and then the molded body (A)
A method for manufacturing an electrostatic chuck, comprising: laminating the electrode layer between the substrate and a molded body (B) so as to sandwich the electrode layer; 9. The conductive silicide is TaSi ₂ , NbSi ₂ ,
WSi _2, a manufacturing method of an electrostatic chuck according to claim 8, characterized in that it consists of one or more selected from the MoSi _2. 10. The method according to claim 8, wherein at least one of the molded body (A) of the dielectric raw material and the molded body (B) of the insulating substrate raw material is manufactured by CIP molding. Of manufacturing an electrostatic chuck. 11. The method according to claim 8, wherein at least one of the molded body (A) of the dielectric material and the molded body (B) of the insulating substrate material is manufactured by doctor blade molding. A manufacturing method of the electrostatic chuck according to the above. 12. The method for manufacturing an electrostatic chuck according to claim 8, wherein the main composition of the dielectric and the base is the same compound. 13. The method for manufacturing an electrostatic chuck according to claim 8, wherein the ceramic dielectric is an alumina ceramic. 14. The method according to claim 13, wherein the dielectric is alumina to which TiO ₂ is added. 15. The method according to claim 13, wherein the dielectric is alumina to which Ti ₂ O ₃ is added. 16. The method for manufacturing an electrostatic chuck according to claim 8, wherein the dielectric is an aluminum nitride ceramic.