Wafer chuck having thermal plate with interleaved heating and cooling elements

Abstract

A workpiece chuck includes a thermal plate assembly which includes both heating and cooling capability. The heating element can be a resistive heater in a coiled configuration disposed in a plane. The cooling can be performed via a cooling fluid circulated through cooling tubes which are also disposed in a coiled configuration in a plane. The plane of the heating element and the cooling tubes can be the same plane, and that plane can be a center plane of the thermal plate assembly. By locating the heating and cooling in the same plane, uniform heating and cooling are achieved. Also, by locating the heating element and cooling tubes in the center of the thermal plate, distortions such as doming and dishing in the thermal plate are eliminated such that the wafer can be held extremely flat on the chuck. The heating element and cooling tubes are coiled in an interleaved fashion to provide uniform heating and cooling while allowing them to simultaneously occupy the same plane.

Description

RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 465,716, filed Jun. 19, 2003, which is a continuation of U.S. patent application Ser. No. 09 / 900,285, filed Jul. 6, 2001, now U.S. Pat. No. 6,700,099, which is based on U.S. Provisional Patent Application Ser. No. 60 / 217,036, filed on Jul. 10, 2000. The contents of all of these applications and patent are incorporated herein in their entirety by reference.BACKGROUND OF THE INVENTION [0002] A workpiece chuck can be used to hold workpieces such as semiconductor wafers during processing and testing. Because integrated circuits formed in a wafer under test are commonly tested over temperature, the workpiece chuck can include a temperature control system for controlling the temperature of the wafer during testing. As integrated circuits become smaller and more densely integrated, positioning tolerances for testing systems such as wafer probers decrease. With very small positioning tolera...

AI Technical Summary

Benefits of technology

[0011] This configuration provides the chuck of the invention with flexibility according to the setting in which the chuck is being used. For example, one type of top surface assembly may be required where the test being performed requires the chuck to be able to absorb a large amount of power. In another test, the top surface assembly may be required to provide low electrical capacitance, high voltage or high electrical isolation performance. In still another test, the top surface assembly may be required to provide for very low signal leakage. In each of these tests, the top surface assembly may be fabricated differently to provide optimal performance under the specific testing parameters. In a conventional chuck system, this would require the user to obtain several different chucks, one for each test type. However, in accordance with this aspect of the invention, the thermal plate assembly of the invention provides a universal type mount which can accommodate all of the various top surface assemblies. As a result, the user need only have a single thermal plate assembly. The user can then purchase only the top surface assemblies required for the tests to be performed. This results in considerable cost savings to the user.

[0012] In another aspect, the invention is directed to an approach to eliminating the negative effects resulting from the relative movement of layers of the workpiece chuck over temperature. When two adjacent chuck layers have different thermal expansion coefficients, they tend to rub each other over temperature. This can cause abrasion of the surfaces which can degrade chuck performance. This is especially true in one particular example where a top surface assembly made of a hard abrasive ceramic material is located adjacent to the cast aluminum housing of the thermal plate assembly. To reduce these effects, one or more adjacent surfaces can be coated with a hard coating, such as hard anodize.

Problems solved by technology

This requirement is especially challenging in a temperature-control chuck where the chuck must maintain mechanical and electrical stability over a wide range of temperatures.

At temperature extremes, particularly at high temperatures, conventional wafer chucks tend to distort due to thermal expansion and contraction and the integrity of the materials of which the chucks are constructed.

For example, chucks made of softer materials will tend to distort at high temperature.

This problem is exacerbated by the increasing mechanical loads on the chuck introduced by the test system, i.e., the wafer prober.

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