Method for coating facet edges of an optoelectrical device

Details Method for coating facet edges of an optoelectrical device Method for coating facet edges of an optoelectrical device

1999-09-16

2001-07-10

Talbot, Brian K. (Department: 1762)

Coating processes

Optical element produced

Polarizer, windshield, optical fiber, projection screen, or...

C427S126300, C427S282000, C427S284000

Reexamination Certificate

active

06258403

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to the coating of optoelectrical devices, such as semiconductor laser bars. More particularly, the present invention relates to an apparatus for holding an optoelectrical device during a coating process to inhibit any coating from adhering to portions of the device other than at predetermined facet edges.
BACKGROUND OF THE INVENTION
Semiconductor laser devices, such as double heterostructure laser diodes, are utilized in various applications, such as for optical sources in fiber optic communications. In the manufacture of such devices, double heterostructures are grown and processed on a wafer substrate using, for example, liquid phase epitaxy techniques. The wafer is then cleaved into typically solid rectangular laser bars containing many laser diodes. The laser diodes are functional at the laser bar level, and therefore electrical/optical testing is often performed at this level prior to cleaving the individual laser diodes from the bars.
Each laser bar has two end faces, or facets, formed during the cleaving process. Laser light is ultimately transmitted through the facets, so it is important for their surfaces to remain unperturbed and uncontaminated during handling of the laser bar. Following the cleaving operation on the wafer to form the laser bars, the facets are coated with an optical coating in a facet coating apparatus. A known apparatus for retaining laser bars during the facet coating processes is a facet coat holding fixture. The fixture also transports the bar to and from the facet coating process.
A problem encountered due to the coating process is that often the optical coating deposits on not only the laser bars but also the fixtures used for retaining the laser bars. This may lead to laser bars sticking to the fixtures and to the fixtures becoming contaminated by the optical coating, eventually leading to sticking and gauging of the fixture.
If a laser bar remains adhered to a fixture, an additional operation is then required to detach the laser bar from the fixture. One example of such an additional operation includes manually shaking the fixture to loosen the laser bar. Another example is physically prying the laser bar from the fixture with a pick or other similar device. Such operations result in a reduction in the yield of usable laser bars, since a number of the laser bars become damaged when pried or shaken from the fixture blades. Typically, as many as half of the laser bars may become damaged from these additional operations.
A second problem is that during the coating process, the coating may creep in between the laser bars and the fixtures, becoming deposited on the p-and/or n-bonding sides of the laser bars. This is referred to as overspray. The p-and n-bonding sides of the laser bars include bonding pads formed of gold, or another suitable conductive material. Deposition of the coating on the p- and n-bonding sides may lead to partial covering of the bonding pads, thereby reducing the possible sites for bonding with a solder material. Excessive deposition may reduce the possible sites for bonding to such an extent as to prevent contact bonding or cause a contact bonded laser to fail.
Due to the inherent problems in conventional methodologies related to the coating process, there exists a need for an improved fixture and method for withstanding the effects of overspraying and sticking.
SUMMARY OF THE INVENTION
The present invention provides a semiconductor device holder including a base and a pair of walls extending upwardly from the base. Each of the walls has a top surface for supporting a semiconductor device thereon. The walls are spaced apart to form a cavity with the base, the cavity being sized to receive an extending portion of a semiconductor device mounted on the top surfaces of the walls.
The present invention also provides a system for retaining an optoelectrical device. The system includes an optoelectrical device having first and second surfaces, first and second facet edges, and an element extending from the second surface. The system further includes a holding apparatus with a base and a pair of walls, each of the walls having a top surface upon which the second surface of the optoelectrical device rests with the element extending into a cavity formed by the base and walls.
The present invention also provides a method of coating an optoelectrical device. The method includes the steps of locating an optoelectrical device on a holding device and coating at least one of the facet edges of the optoclectrical device with a coating material. The optoclectrical device has first and second surfaces, first and second facet edges, and an element extending from said second surface. The holding apparatus has a base and a pair of walls, each wall has a top surface which supports the second surface of the optoclectrical device such that the extending element is located between the walls. The extending element is protected from being coated with a coating material by the walls.
These and other features and advantages of the invention will be more clearly understood from the following detailed description of the invention which is provided in connection with the accompanying drawings.


REFERENCES:
patent: 4695486 (1987-09-01), Stark
patent: 5179609 (1993-01-01), Blonder et al.
patent: 5550088 (1996-08-01), Dautartas et al.
patent: 5840122 (1998-11-01), Williams
patent: 5911830 (1999-06-01), Chakrabarti et al.
patent: 5935451 (1999-08-01), Dautartas et al.
patent: 5989637 (1999-11-01), Rizzo et al.
patent: 6026557 (2000-02-01), Freund et al.
patent: 6131263 (2000-10-01), Freund et al.

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