Ceramic substrate, ceramic heater, electrostatic chuck and wafer prober for use in semiconductor producing and inspecting devices

Abstract

A ceramic substrate for semiconductor manufacture and / or inspection which is conducive to decrease in α-rays radiated, to prevent electrical errors, and to decrease an electrostatic chucking force such as heater or wafer prober, generation of particles, and circuit defects. The ceramic substrate is configured such that the level of α-rays radiated from the surface of the ceramic substrate is not higher than 0.250 c / cm2·hr.

Description

TECHNICAL FIELD [0001] The present invention relates essentially to the ceramic substrate, ceramic heater, electrostatic chuck and wafer prober for semiconductor manufacture and / or inspection and more particularly to a ceramic substrate for semiconductor manufacture and / or inspection which is conducive to the prevention of electrical errors, decrease in electrostatic chucking force, generation of particles, and circuit defects. BACKGROUND ART [0002] Semiconductor devices are manufactured through a process which comprises coating a photosensitive resin as an etching resist on a semiconductor wafer and etching the uncoated area. [0003] While the photosensitive resin is applied in the form of a liquid to the surface of a semiconductor wafer by means of a spin coater or the like, it must be dried after coating to dissipate the solvent etc. and the thus-coated semiconductor wafer is set on a heater and heated. It is also necessary to heat the silicon wafer by, for example, sputtering. [0...

AI Technical Summary

Benefits of technology

[0068] Moreover, the ceramic substrate is preferably in the form of a disk with a diameter of not less than 200 mm. Ceramic substrates having such large areas are more probable to cause troubles related with α-rays so that the effect of the invention is more pronounced.

[0069] The ceramic substrate is preferably free of pores but, if it is porous, the porosity rate is preferably not greater than 5% and the maximum pore diameter is preferably not more than 50 μm. If these limits are exceeded, the α-rays passing through the air entrapped in the pores produce a plasma to reduce the insulation resistance at high temperature (not less than 200° C.).

[0070] The present invention is now described in detail with reference to each embodiment or application.

[0071] The ceramic heater according to the present invention comprises a heating element formed on the surface or internally of a ceramic substrate wherein the level of α-rays radiated from the surface of said ceramic substrate is not higher than 0.250 c / cm2·hr and substantially within the range of 0.0001 to 0.250 c / cm2·hr.

[0072] The ceramic heater of the present invention, wherein the level of α-rays radiated from the surface of the ceramic substrate is not higher than 0.025 c / cm2·hr, is free from the disadvantage that the creation of electron-hole pairs in the semiconductor wafer caused by the α-rays would affect temperature data through the consequent charging of the resultant static electrocity and / or direct introduction of thermoelectrical noise to the thermocouples. Furthermore, if the level of α-rays is confined to not more than 0.025 c / cm2·hr, static electrocity on the semiconductor wafer is not likely to occur, therefore the deposition of ceramic particles thereon can be reduced.

[0073] In the present invention, ideally the level of α-ray emission is equal to nil but it is technically and economically difficult to achieve an emission level less than 0.0001 c / cm2·hr. On the other hand, if the emission level of α-rays exceeds 0.025 c / cm2·hr, ceramic particles tend to be deposited on the semiconductor wafer due to the static charge generated by α-rays so that the semiconductor wafer may sustain a damage crippling its function.

Problems solved by technology

As a result, the semiconductor wafer itself is statically charged and this statistic electricity attracts particles from the ceramic substrate or triggers erratic actions of the ceramic heater and wafer prober due to the thermocouples embedded in the ceramic substrate.

Thus, the above-mentioned problems with the prior art, regardless of whether the ceramic substrate is applied to a heater, an electrostatic chuck or a wafer prober, are likely to be derived from the electron-hole pairs which α-rays create in the semiconductor wafer.

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