TECHNICAL FIELD

This application is a National Stage of International Application No. PCT/KR2019/014528 filed Oct. 31, 2019, claiming priority based on Korean Patent Application No. 10-2018-0136671 filed Nov. 8, 2018, the entire contents of which are incorporated herein by reference.

The present invention relates to an electrostatic chuck for fixing a semiconductor wafer, etc. by an electrostatic force, more particularly, to an electrostatic chuck capable of improving adsorption and desorption response characteristics of a semiconductor wafer by reducing a leakage current due to high volume resistivity and a method of manufacturing the same.

BACKGROUND ART

An electrostatic chuck (ESC) is a device that horizontally fixes a semiconductor wafer or LCD glass substrate by using an electrostatic force, and is largely classified into a Coulomb-type electrostatic chuck and a Johnson-Rahbek-type electrostatic chuck according to the adsorption method. Among them, the Johnson-Rahbek-type electrostatic chuck generally has a low volume resistivity characteristic of 1×109˜1×1012Ω·cm, charges electric charges on the wafer adsorption surface of the dielectric due to its low volume resistivity characteristics, and fixes the wafer through electrostatic attraction of these surface charges. On the other hand, the Coulomb-type electrostatic chuck fixes the wafer by using electrostatic attraction between different charges existing on the upper and lower surfaces of the dielectric. In the Coulomb-type electrostatic chuck, only when the volume resistivity of the dielectric is 1×1015Ω·cm or more, the leakage current is small and the wafer desorption performance is excellent, and as the size of the semiconductor wafer is increased, sufficient electrostatic adsorption force may not be uniformly formed over the entire wafer contact surface.

Meanwhile, for electrostatic chuck, a material mainly made of aluminum such as aluminum oxide (Al2O3) or aluminum nitride (AlN) is used. However, since the sintered body of aluminum oxide has a volume resistivity rate of 1×1014Ω·cm or more at room temperature, the electrostatic chuck should be manufactured using the Coulomb-type method rather than the Johnson-Rahbek-type method, in order to use aluminum oxide as the main raw material and to have sufficient adsorption rate and excellent current response characteristics.

However, the conventional Coulomb type electrostatic chuck has a problem in that the volume resistivity is not high when it is out of a specific temperature range, and it is not easy to maintain the volume resistivity even under a specific temperature, and thus the adsorption force is unstable. In addition, the conventional electrostatic chuck has a disadvantage in that there is a large amount of current leaking from the electrostatic chuck to the substrate, and the response speed at the time of substrate desorption is slow, and thus good desorption response cannot be obtained. Accordingly, there is a need to develop a novel Coulomb-type electrostatic chuck which is capable of solving the above problems.

DISCLOSURE

Technical Problem

Therefore, the present invention relates to an electrostatic chuck capable of improving adsorption and desorption response characteristics of a semiconductor wafer by reducing a leakage current by high volume resistivity and a method of manufacturing the same.

Technical Solution

In order to achieve the above objects, the present invention relates to an electrostatic chuck, which is a sintered body in which an electrode is impregnated so as to fix a semiconductor wafer by electrostatic force, and which comprises alumina; a sintering aid; and a rare earth composite oxide comprising two to five different rare earth metals, has adsorption and desorption response characteristics of a semiconductor wafer of two seconds or less, and has a volume resistivity at room temperature of 1.0E+16 to 1.0E+17 Ω·cm.

In addition, the present invention provides a method of manufacturing the electrostatic chuck comprising the steps of a) preparing a rare earth composite oxide containing 2 to 5 different rare-earth metals by wet-mixing two or more different rare-earth metal oxide powders and a solvent under milling, and then drying, granulating and heat-treating it; b) supplying alumina, a sintering aid, alcohol and a binder to the prepared rare earth composite oxide, and then mixing them; c) drying the mixture in step b) to remove the alcohol component; d) molding and processing the dried mixture to prepare a pre-molded body; e) degreasing the pre-molded body to remove the binder component; and f) sintering the degreased pre-molded body and then polishing it.

Advantageous Effects

According to the electrostatic chuck and its manufacturing method according to the present invention, the leakage current is reduced by high volume resistivity, so adsorption and desorption response characteristics of the semiconductor wafer can be improved.

