ELECTROSTATIC CHUCK AND MANUFACTURING METHOD THEREOF

Abstract

An electrostatic chuck includes: a base body formed of an aluminum nitride sintered body containing samarium; and an electrode embedded in the base body and containing molybdenum, wherein a portion of the base body from the electrode to a base body surface is formed into a dielectric layer, and the base body surface is formed into a substrate mounting surface on which a processing target is sucked and mounted, and a content of samarium-aluminum oxide phases in the base body in a vicinity of the electrode is set at 2.5% or less in terms of an area ratio.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an electrostatic chuck according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a mesh-like electrode embedded in a base body of FIG. 1.

FIG. 3 is a perspective view showing an electrode made of punching metal.

FIG. 4 is an SEM photograph of a cross section in a part of the base body manufactured by using a method according to the embodiment of the present invention, in which magnification is 200 times.

FIG. 5 is an SEM photograph of a cross section in the vicinity of the mesh-like electrode in the base body manufactured by using the method according to the embodiment of the present invention, in which the magnification is 400 times.

FIG. 6 is an SEM photograph of a cross section in a part of a base body manufactured by using a method according to a comparative example, in which the magnification is 200 times.

FIG. 7 is an SEM photograph of a cross section in the vicinity of a mesh-like electrode in a base body manufactured by using a method according to a comparative example, in which the magnification is 400 times.

FIG. 8 is a schematic view showing an image obtained by binarizing the SEM photograph of FIG. 5, in which black portions represent samarium-aluminum oxide phases, and a white portion represents the other portion.

FIG. 9 is a schematic view showing an image obtained by binarizing the SEM photograph of FIG. 7, in which black portions represent the samarium-aluminum oxide phases, and a white portion represents the other portion.

FIG. 10 is a graph showing results of crystal phase analyses by means of an XRD for Present invention examples 2 and 6 in Examples.

Claims

1. An electrostatic chuck, comprising: a base body including an aluminum nitride sintered body containing samarium; andan electrode containing molybdenum, the electrode embedded in the base body,wherein a portion of the base body from the electrode to a base body surface is formed into a dielectric layer, and the base body surface is formed into a substrate mounting surface on which a processing substrate is sucked and mounted, anda rate of content of samarium-aluminum oxide phases in the base body in a vicinity of the electrode is set at 2.5% or less in terms of an area ratio.

2. The electrostatic chuck according to claim 1, wherein the electrode is a mesh-like electrode formed by combining a plurality of linear bodies, and the rate of content of samarium-aluminum oxide phases is a ratio of an occupied area of the samarium-aluminum oxide phases precipitated on a cross-sectional portion within a predetermined area perpendicular to the linear bodies.

3. The electrostatic chuck according to claim 1, wherein the samarium-aluminum oxide phases include SmAl11O18 phases.

4. A manufacturing method of an electrostatic chuck, comprising: forming a preliminary molded body made of ceramics containing samarium oxide and aluminum nitride;disposing an electrode containing molybdenum on a predetermined outer surface of the preliminary molded body, then disposing source material powder of the aluminum nitride containing the samarium oxide on the predetermined outer surface and the electrode, and pressure-molding the preliminary molded body, the electrode, and the source material powder, thereby forming a molded body in which the electrode is embedded; andheating and sintering the molded body, and then cooling the molded body to room temperature,wherein a cooling rate in the cooling step is 200° C./hour or more.

5. The manufacturing method of an electrostatic chuck according to claim 4, wherein the cooling rate is set at 300 to 900° C./hour.

6. The manufacturing method of an electrostatic chuck according to claim 4, wherein a molar ratio of samaria to alumina is set at 0.28 by adding, to source material of the aluminum nitride powder, aluminum oxide of an amount corresponding to an oxygen amount of the source material powder, so as to constantly set an oxygen amount in the sintered body and SmAl11O18 phases are precipitated in the sintered body.