Optics: measuring and testing – Inspection of flaws or impurities – Surface condition
Reexamination Certificate
1999-07-06
2001-06-19
Font, Frank G. (Department: 2877)
Optics: measuring and testing
Inspection of flaws or impurities
Surface condition
C414S225010, C414S416060
Reexamination Certificate
active
06249342
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the handling of wafers, and more particularly to handling and testing semiconductor wafers in a wafer testing apparatus.
The manufacture of integrated circuit (IC) chips begins with blank, unpatternd semiconductor wafers. These wafers undergo a number of sometimes critical process steps before being formed into the final IC chip form. A substandard wafer can affect the yield (i.e., number) of usable IC chips on a wafer. It is therefore desirable to have a machine for testing wafers to ensure that the wafers meet a desired standard to maximize wafer yield.
Testing of the wafers typically involves an automated process utilizing automated wafer handling machines. In this process, the automated wafer handling machines continuously handle and test the wafers. The automated process tends to be more efficient than manual testing and handling of wafers since an automated process is typically faster, more precise, and less prone to contamination than a manual process.
One of the major uses of the automated wafer handling machines is for testing or processing the wafers to determine or change certain wafer characteristics (such as by depositing a film or removing a wafer layer). For example, automated wafer handling machines are often used to determine the orientation of a wafer, which provides a standard reference against which the location and characteristics of test points on the wafer may be measured.
A conventional art wafer handling machine has a four degree of freedom. In this machine, the wafer cassette moves up and down, the chuck rotates, the arm moves from left to right. However, one of the drawbacks of the conventional wafer handling machines is movement of the wafers within the wafer cassette. For example, when the wafer cassette moves up and down to allow a robot arm to remove a wafer from the cassette or place a wafer into the cassette, the wafers within the cassette may be subject to unwanted jarring. The vibrations caused by the jarring are potentially harmful due to the creation of particle contaminants.
In addition, the conventional wafer handling machines typically include a motor for each degree of freedom for a total of four motors. Generally, moving parts in a machine or apparatus such as motors are more prone to failure and require more maintenance than non-moving parts. Further the use of such number of motors typically require complex and costly mechanisms that require more maintenance, which is undesirable in production environments.
Thus, what is needed is an apparatus and method that can efficiently move and test wafers without moving the wafer carrier or cassette. In addition, what is needed is an apparatus and method that can move and test wafers using less number of motors so as to reduce the cost and maintenance involved with the motors.
SUMMARY OF THE INVENTION
The present invention fills these needs by providing an apparatus and a method for handling and testing wafers in an integrated system. It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device, or a method. Several inventive embodiments of the present invention are described below.
In one embodiment, the present invention provides a wafer handling and testing apparatus. The wafer handling and testing apparatus includes a support assembly, a wafer handling assembly, and a probe assembly. The support assembly is capable of supporting a wafer to be tested and is also capable of rotating the wafer for testing. The wafer handling assembly is arranged to move the wafer to and from the support assembly. The wafer handling assembly is capable of moving the along a first axis and a second axis. The first axis is preferably orthogonal to the second axis. The probe assembly is arranged to test the wafer when the wafer is placed on the support assembly.
In another embodiment, an integrated wafer handling and testing apparatus includes supporting means, handling means, and testing means. The supporting means supports a wafer to be tested and is capable of rotating the wafer in an x-y plane. The handling means moves the wafer to and from the wafer support assembly and is capable of moving the wafer along a first axis and a second axis, which are orthogonal to each other. The testing means tests the wafer when the wafer is placed on the support means.
In yet another embodiment, the present invention provides a method for handling a wafer from a stationary wafer carrier for testing. The stationary wafer includes a plurality of wafers to be tested. The method includes (a) selecting a wafer to be tested; (b) picking up the wafer; (c) moving the wafer along an x-axis and a z-axis to a support assembly for testing; (d) placing the wafer on the support assembly; (e) rotating the supporting assembly to place the wafer at a desired test position; and (f) testing the wafer at the desired test position to determine a wafer characteristic.
Advantageously, the present invention efficiently moves and tests wafers without moving the wafer carrier or cassette by providing a wafer handling assembly that has two degrees of freedom along the first axis and the second axis. In addition, by enabling the wafer handling assembly to move along the second axis, a support assembly need not move along the second axis, thereby eliminating the need for a motor in some embodiments of the present invention.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading the following detailed description of the invention and studying the accompanying drawings.
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patent: 4775281 (1988-10-01), Prentakis
patent: 4818169 (1989-04-01), Schram et al.
patent: 4907931 (1990-03-01), Mallory et al.
patent: 5479108 (1995-12-01), Cheng
patent: 5546179 (1996-08-01), Cheng
patent: 5679060 (1997-10-01), Leonard et al.
patent: 6053688 (2000-04-01), Cheng
Font Frank G.
Nguyen Sang H.
Oppenheimer Wolff & Donnelly LLP
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