Severing by tearing or breaking – Methods
Reexamination Certificate
1999-04-01
2001-07-31
Rada, Rinaldi I. (Department: 3724)
Severing by tearing or breaking
Methods
C225S002000, C225S004000, C225S005000
Reexamination Certificate
active
06267282
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the production of semiconductor chips. The present invention also relates to a system for handling brittle workpieces such as laser bars. More particularly, the present invention relates to a method and an apparatus for cleaving a laser bar into semiconductor chips.
BACKGROUND OF THE INVENTION
There are currently several different apparatus and methods used to cleave a laser bar into discrete semiconductor chips. One known method involves the use of mechanically applied pressure to a laser bar. By this method, a laser bar is grasped by a mechanical device at opposing places and a force is directed at both opposing places, creating a plane of stress at which ultimately the laser bar is broken. The use of mechanically applied pressure in this manner, however, sometimes provides an uneven, ragged cleave edge.
Another method involves passing a high velocity stream of gas over the laser bar to induce cleavage. There is an ergonomic disadvantage to this method in that it is noisy. A further disadvantage is that a large volume of gas is required to induce cleavage.
SUMMARY OF THE INVENTION
The present invention provides an apparatus for cleaving a laser bar. The apparatus includes a support, at least one flexible barrier, a movable member positioned between the support and the flexible barrier, and a chamber for exerting pressure on the flexible barrier. The chamber is located on the flexible barrier and it has an outer periphery. The laser bar is moved between the support and the flexible barrier within the outer periphery of the chamber to apply bending forces to the laser bar.
In a preferred embodiment of the invention, the laser bar has a plurality of score marks to induce cleaving at the score marks.
In another preferred embodiment of the invention, the pressure includes a force induced by gas pressure in the chamber.
In another preferred embodiment of the invention, the member is left stationary and two film layers, one positioned above and the other below the laser bar, are moved over the member to apply bending forces on the laser bar.
The present invention also provides a method of cleaving a laser bar into chips. The method includes the steps of positioning a movable member between a flexible barrier and a supporting structure, locating a laser bar between the flexible barrier and the movable plate, sealing a chamber to the flexible barrier, exerting a pressure on the laser bar, and moving the member along the supporting structure. The movement and the pressure cause the laser bar to cleave into chips.
In a preferred embodiment of the invention, the downward force includes gas pressure and the gas is introduced to the chamber in pulses.
An object of the present invention is to provide an energy efficient and low noise method and apparatus for cleaving a semiconductor bar into discrete chips.
Another object of the present invention is to provide an apparatus and method for cleaving a semiconductor bar to create clean cleave edges.
Another object of the present invention is to provide an apparatus and method for cleaving a semiconductor bar which does not require a large volume of gas.
These and other advantages will become apparent from the following detailed description of preferred embodiments of the invention.
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Freund Joseph Michael
Gault William Andrew
Przybylek George John
Romero Dennis Mark
Stayt, Jr. John William
Agere Systems Optoelectronics Guardian Corp.
Dickstein , Shapiro, Morin & Oshinsky, LLP
Flores-Saánchez Omar
Rada Rinaldi I.
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