US 7,072,165 B2Granted

MEMS based multi-polar electrostatic chuck

AssigneeAxcelis Technologies, Inc.

InventorsPeter L. Kellerman, Shu Qin, Douglas A. Brown

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Abstract

The present invention is directed to a semiconductor processing apparatus and a method for clamping a semiconductor substrate and controlling a heat transfer associated therewith. According to one aspect of the present invention, a multi-polar electrostatic chuck and associated method is disclosed which provides a controlled and uniform heat transfer coefficient across a surface thereof. The multi-polar electrostatic chuck comprises a semiconductor platform having a plurality of protrusions that define gaps therebetween, wherein a distance or depth of the gaps is uniform and associated with a mean free path of the cooling gas therein. The electrostatic chuck is permits a control of a backside pressure of a cooling gas within the plurality of gaps to thus control a heat transfer coefficient of the cooling gas. The plurality of protrusions further provide a uniform contact surface, wherein a contact conductivity between the plurality of protrusions and the substrate is controllable and significantly uniform across the substrate.

Claims47

Dependent claims

A multi-polar electrostatic chuck for clamping a substrate and controlling a heat transfer associated therewith, the electrostatic chuck comprising:

a clamping plate, the clamping plate further comprising:
a semiconductor plafform;
a first electrically conductive layer formed over a top surface of the semiconductor plafform, wherein the first electrically conductive layer comprises a plurality of portions, wherein the plurality of portions are generally electrically isolated from one another, therein defining a plurality of poles associated with the electrostatic chuck;
and
a plurality of electrically insulative protrusions formed over the first electrically conductive layer, the plurality of protrusions extending a first distance from a top surface of the first electrically conductive layer, wherein the plurality of protrusions are operable to generally contact the substrate, therein defining a protrusion contact area that is entirely electrically insulative, and wherein the plurality of protrusions generally define a plurality of gaps therebetween having a second distance associated therewith;
a base plate operable to transfer thermal energy from the substrate through the clamping plate;
and
a plurality of electrodes electrically connected to the respective plurality of portions of the first electrically conductive layer, wherein the plurality of electrodes are further operable to be connected to a voltage source.

5 more elements

A method of clamping a substrate and controlling a heat transfer associated therewith, the method comprising:

placing the substrate on a clamping plate having a plurality of electrically insulative protrusions extending from a first electrically conductive layer formed over a semiconductor plafform, the plurality of protrusions defining a protrusion contact area that is entirely electrically insulative, the plurality of protrusion further defining plurality of gaps therebetween and a first distance between the substrate and a top surface of the first electrically conductive layer, wherein the first distance is associated with a mean free path of a cooling gas within the gaps;
applying a voltage between at least two regions of the first electrically conductive layer, wherein an electrostatic force generally attracts the substrate to the clamping plate;
and
controlling a pressure of the cooling gas in the gaps, wherein a heat transfer coefficient of the cooling gas within the gaps is primarily a function of pressure and substantially independent of the gap distance.

1 more element

Dependencies are inferred from the claim text.