JP2007070142A - Plasma-resistant electrode-buried body, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma-resistant electrode-buried body in which plasma resistance is improved. <P>SOLUTION: The plasma-resistant electrode-buried body is produced by placing metal electrodes on a Y<SB>2</SB>O<SB>3</SB>calcined body, pouring Y<SB>2</SB>O<SB>3</SB>slurry thereon, drying the slurry, and thereafter joining the stacked body by hot pressing at 1,650 to 1,900°C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma-resistant electrode embedded body and a method of manufacturing the same, and more particularly to an electrostatic chuck for fixing a silicon wafer or the like used in a semiconductor manufacturing process, and a plasma-resistant electrode embedded body such as a ceramic heater embedded with a resistance heating element. And a manufacturing method thereof.

  In an electrostatic chuck that is used as a plasma-resistant electrode embedded body in CVD, PVD, ion sputtering, etching, etc. during a semiconductor manufacturing process and fixes a silicon wafer or the like, a metal or a metal component and silicon carbide or A material made of a raw material mixed with a ceramic component of aluminum nitride is used. An insulating layer made of amorphous ceramic is applied to the surface of the base material, and further, an insulating film made of amorphous ceramic made of oxide is applied. Has been proposed (Patent Document 1). Since the thing of this patent document 1 consists of several layers from which a material differs, a film | membrane peeling and a crack are easy to generate | occur | produce at the time of use.

  In addition, as a method for manufacturing an electrostatic chuck in which a metal electrode is embedded in a ceramic base material such as silicon nitride, silicon carbide, or aluminum nitride, a first ceramic molded body is manufactured by uniaxial pressing, and the first ceramic molded body A metal electrode is placed on the ceramic electrode, and further, ceramic powder is filled thereon and pressed by a uniaxial press to produce a preform. After that, a hot press firing method is proposed for the preform. (Patent Document 2).

  Further, a hot press firing method is proposed in which a release sheet-like material is interposed between a molded body raw material powder and a lower mold in order to prevent cracks from occurring in the molded body during mold release according to Patent Document 2 ( Patent Document 3).

  Furthermore, a ceramic molded body is produced using aluminum nitride powder containing 5% by weight of yttria, a surface electrode is placed on the molded body, aluminum nitride powder is filled thereon, and a hot press firing method is proposed. (Patent Document 4).

  In recent years, there has been a demand for an electrode embedded body with improved plasma resistance. The present inventors have focused on the fact that yttria is superior in plasma resistance compared to other ceramics, and the entire electrode embedded body is made of yttria. The production of the present invention has led to the present invention. In addition, yttria is extremely small in strength of the sintered body and causes the generation of cracks at the time of manufacture, but the present inventors use a calcined body in the portion that becomes the base-side sintered body portion on which the metal electrode is placed, The slurry is used for the portion that becomes the mounting-side sintered body portion that covers the metal electrode and is provided with the wafer mounting surface, and the hot press firing conditions are set to achieve the present invention.

In the hot press firing methods described in Patent Documents 2 to 4, it is impossible to manufacture an electrode embedded body using yttria as a whole without generation of cracks.
JP-A-2005-72286 Japanese Patent Laid-Open No. 10-249843 Japanese Patent Laid-Open No. 10-264121 Japanese Patent Laid-Open No. 7-273164

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a plasma-resistant electrode embedded body with improved plasma resistance.

  Moreover, it aims at providing the manufacturing method of the plasma-resistant electrode embedded body which does not generate | occur | produce a crack at the time of manufacture.

  In order to achieve the above-described object, a plasma-resistant electrode-embedded body according to the present invention comprises an yttria base material and a metal electrode embedded in the yttria base material.

In the plasma-resistant electrode-embedded body according to the present invention, a metal electrode is placed on a Y ₂ O ₃ calcined body, Y ₂ O ₃ slurry is poured thereon, and after the slurry is dried, the laminate is 1650. It is produced by bonding by hot pressing at ˜1900 ° C.

A method of manufacturing a plasma resistance electrode buried body according to the present invention, Y ₂ O ₃ prepared calcined body, place the metal electrode to the Y ₂ O ₃ calcined on the body, Y ₂ O ₃ thereon The slurry is poured, and after the slurry is dried, the laminate is bonded by hot pressing at 1650 to 1900 ° C.

Preferably, the pressure during the hot pressing is 0.05 to 0.3 ton / cm ² , and the keeping time at the maximum temperature is 1 to 15 hours.

  The plasma-resistant electrode embedded body according to the present invention can provide a plasma-resistant electrode embedded body with improved plasma resistance.

  Moreover, according to the manufacturing method of the plasma-resistant electrode embedded body which concerns on this invention, the manufacturing method of the plasma-resistant electrode embedded body which does not generate | occur | produce a crack at the time of manufacture can be provided.

  Hereinafter, an embodiment of a plasma-resistant electrode embedded body according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a longitudinal sectional view of an yttria electrostatic chuck as an embodiment of the plasma-resistant electrode embedded body of the present invention.

  As shown in FIG. 1, the yttria electrostatic chuck 1 of the present embodiment is entirely made of yttria raw material, has a disk shape, and further has a mounting side sintered body portion provided with a wafer mounting surface 2a. 2, a base-side sintered body portion 3 that is integrally joined to the mounting-side sintered body portion 2, and a metal electrode 4 embedded between the sintered bodies 2 and 3.

  In the figure, reference numeral 5 denotes a voltage supply terminal.

  The material of the metal electrode is preferably one of Mo, W, and Ta, or a compound thereof, and the metal electrode is partially functionally using a mesh-like metal wire knitted. It is preferable to provide a shape provided with a hole for feeding or a hole for gas penetration.

  According to the plasma-resistant electrode embedded body of the above-described embodiment, improvement in plasma resistance is realized.

  Furthermore, the yttria electrostatic chuck of the present embodiment is manufactured by the following process.

For example, as shown in FIG. 2, prepared Y ₂ O ₃ calcined 3A as a base-side sintered body, place the metal electrode 4 on the Y ₂ O ₃ calcined 3A, placing thereon The Y ₂ O ₃ slurry 2A that forms the stationary-side sintered body portion is poured, and after the slurry is dried, the laminate is joined by hot pressing.

The temperature of hot pressing is preferably 1650 to 1900 ° C., the pressure is 0.05 to 0.3 ton / cm ² , and the keeping time at the maximum temperature is preferably 1 to 15 hours.

If the temperature is lower than 1650 ° C., the portion using the slurry is not preferable because the density after firing is small, and if it is higher than 1900 ° C., the durability of the mold deteriorates. When the pressure is less than 0.05 ton / cm ² , the portion using the slurry has a low density after firing, and when it is greater than 0.3 ton / cm ² , the life of the mold is shortened. If the keep time is shorter than 1 hour, the portion using the slurry has a low density after firing, and if it is longer than 15 hours, the productivity decreases.

As a method of making the Y ₂ O ₃ calcined body, a slurry obtained by mixing Y ₂ O ₃ raw material powder, a sintering aid, pure water, and a binder is made into a granulated powder having a particle size of about 100 μm with a spray dryer. ₂ O ₃ granulated powder is formed by CIP, degreased, fired in an oxidizing and reducing atmosphere, and processed into a disk shape.

As a method for preparing the Y ₂ O ₃ slurry, Y ₂ O ₃ raw material powder, a sintering aid, pure water, a dispersion material, and resin balls are put in a pot, and the pot is rotated.

  The laminate is composed of a slurry dried body that forms the mounting-side sintered body portion, an electrode, and a calcined body that forms the base-side sintered body portion. A metal electrode is placed on the calcined body, and the slurry is placed. Pour it, put it in a dryer and make it completely dry. Instead of placing the temporary metal electrode on the fired body, an electrode layer may be formed on the sintered body by a screen printing method.

  The method for producing a plasma-resistant electrode embedded body according to the present invention has the following characteristics.

(1) Effect of using Y ₂ O ₃ slurry The reason for using the slurry is to eliminate voids at the bonding interface before hot pressing, prevent carbon from entering during hot pressing, and improve strength and performance. . On the other hand, when the oxide calcined bodies are hot-pressed and the cross-section of the sintered bonded body is observed, the bonding interface becomes black. The carbon powder coming from the material enters and agglomerates at the bonding interface, resulting in deterioration of strength and performance. Moreover, since this method uses hot press firing, even if a slurry is used, the portion using this slurry is in a state of good density after firing.

(2) Effect of using the Y ₂ O ₃ calcined body By using the Y ₂ O ₃ calcined body, even if it cracks during the temperature increase of the hot press, the cracked portion is buried and cracked during the sintering. It is possible to obtain a joined body without any. On the other hand, when a Y ₂ O ₃ sintered body is used, the sintered body breaks during hot pressing. This is because in the initial stage of hot press pressurization, the amount of shrinkage of the slurry portion is large, so that the Y ₂ O ₃ sintered body is in a shoulder-like state where partial pressure is applied to the Y ₂ O ₃ sintered body. Can not withstand that pressure and will crack.

  Moreover, since the calcined body absorbs moisture when the slurry is poured, cracks during drying of the slurry can be minimized.

  The flatness of the calcined body is better than a method in which a metal is embedded in the powder, and the warpage of the metal electrode can be reduced.

(3) Effect of using Mo, W, Ta as material of metal electrode Since the bonding is performed by hot pressing, the electrode is preferably a refractory metal. Among refractory metals, W 2 and Mo, which have a thermal expansion coefficient close to that of Y ₂ O ₃ , are particularly preferable because they hardly cause cracks during firing.

(4) Effect of using mesh-shaped electrode The metal electrode has a force that extends in the outer peripheral direction during hot pressing. This is because during hot pressing, the vertical direction is constrained by the press, but in the horizontal direction there is a slight gap between the carbon jig and the dried slurry layer, so that force is generated by moving in the outer circumferential direction. . Since the mesh is knitted, it can absorb elongation. On the other hand, in a lattice-like material that hardly absorbs elongation, the metal itself is elongated, so that a metal with low ductility may be cut.

  According to the method for manufacturing a plasma-resistant electrode embedded body of the present embodiment, a method for manufacturing a plasma-resistant electrode embedded body that does not generate cracks during manufacturing is realized.

(Test 1)
(1) The firing temperature is shifted to 5 levels (1600 ° C, 1650 ° C, 1700 ° C, 1750 ° C, 1800 ° C), and the pressure is 2 levels (0.1 ton / cm ² , 0.2 ton / cm ² ) under nitrogen atmosphere Then, a sample of the joined body was prepared, the dielectric layer portion of the sample was ground, and the thickness of the dielectric layer was 1 mm.

1) The sample was cut and the cut surface was examined for thickness variation by a two-dimensional measuring machine.
2) Further, the density of the Y ₂ O ₃ defatted powder layer after hot pressing, the surface of the sample, and the presence or absence of internal cracks were investigated.

(2) The results of 2) and 3) are shown in Table 1.

When the firing temperature is 1600 ° C., which is outside the range of the present invention, the density after firing of ₃ parts of the slurry Y ₂ O is unsuitable regardless of the keeping time and pressure, and the overall judgment is also unsuitable as a plasma-resistant electrode embedded body. Met.

  On the other hand, when the firing temperature was within the range of the present invention, there was no variation, no occurrence of peeling / cracking, and both were good.

Regarding the density after firing of ₃ parts of the slurry Y ₂ O, when the firing temperature is 1650 ° C. within the range of the present invention, it is partially inappropriate regardless of the keeping time and pressure, and the overall judgment is also plasma resistant electrode Although it was partially unsuitable as an embedded body, it was possible to use it by selective adoption.

Further, when the firing temperature is 1700 ° C., 1750 ° C., and 1800 ° C. within the range of the present invention, the keep time is 1 hour, regardless of the pressure, the density after firing is partially inappropriate, and the overall judgment is also plasma resistant electrode Although it is partially unsuitable as an embedded body, with a keep time of 3 hours and 5 hours, if the firing temperature is 1700 ° C. to 1800 ° C. and the pressure is 0.1 ton / cm ² or more, the density after firing is all good, It became favorable as a plasma electrode embedded body.

(Test 2)
(1) For comparison, unlike the manufacturing method of the present invention, an electrode is sandwiched between Y ₂ O ₃ powder and Y ₂ O ₃ powder, formed by a uniaxial pressure molding machine, and hot-pressed. A body was prepared and the same investigation as in Test 1 was performed.

(2) The results are shown in Table 2.

  Even if the press conditions were within the scope of the present invention, all of the comparative examples had variations in the dielectric layer thickness, and the overall judgment was unsuitable as a plasma-resistant electrode embedded body.

(Test 3)
(1) By using the method of the present invention, the joined raw material is manufactured by changing the used raw material from Y ₂ O ₃ (Example) to AlN (Comparative Example 1) and Al ₂ O ₃ (Comparative Example 2). Exposure was carried out and the etching amount was examined.

“Etching conditions” Gas: F system, flow rate: CF4 = 100 cc / min,
Supply power: Ps / pb = 500 w / 40 w, ion bombardment energy: 88 eV,
Plasma density: 1.7 × 10 ¹¹ : Atoms / cm ² , gas pressure: 4 mTorr

(2) The results are shown in Table 3.

  The etching rate of the examples was as small as 100 Å / h, and it was found that the plasma resistance was 10 times better than Comparative Examples 1 and 2 at 1000 Å / h.

The conceptual diagram of the yttria electrostatic chuck as one embodiment of the present invention. The conceptual diagram of the manufacturing method of the yttria electrostatic chuck as one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Yttria electrostatic chuck 2 Placement side sintered body part 3 Base side sintered body part 4 Metal electrode

Claims (4)

A plasma-resistant electrode embedded body comprising an yttria base material and a metal electrode embedded in the yttria base material. It is manufactured by placing a metal electrode on a Y ₂ O ₃ calcined body, pouring a Y ₂ O ₃ slurry on the Y ₂ O ₃ calcined body, and bonding the laminate by hot pressing at 1650 to 1900 ° C. after drying the slurry. A plasma-resistant electrode embedded body characterized by A Y ₂ O ₃ calcined body is prepared, a metal electrode is placed on the Y ₂ O ₃ calcined body, a Y ₂ O ₃ slurry is poured onto the Y ₂ O ₃ calcined body, and after drying the slurry, the laminate is 1650-1900 ° C. A method for producing a plasma-resistant electrode-embedded body characterized by bonding by hot pressing. The plasma-resistant electrode embedded body according to claim 3, wherein the pressure at the time of hot pressing is 0.05 to 0.3 ton / cm ² , and the keeping time at the maximum temperature is 1 to 15 hours. Manufacturing method.

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