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One-Step Laser Diode Die-Bonding Method

IP.com Disclosure Number: IPCOM000036931D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Richard, H: AUTHOR

Abstract

With hitherto applied methods and apparatus, a conductive organic flux substance is used for laser diode bonding. During heat treatment, this results in the deposition of a film of organic substance on the laser mirror, thereby deteriorating the performance of high-quality devices. This can be avoided with the herein described one-step bonding method employing an eutectic compound.

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One-Step Laser Diode Die-Bonding Method

With hitherto applied methods and apparatus, a conductive organic flux substance is used for laser diode bonding. During heat treatment, this results in the deposition of a film of organic substance on the laser mirror, thereby deteriorating the performance of high-quality devices. This can be avoided with the herein described one-step bonding method employing an eutectic compound.

The method is illustrated in the figure. The mounting cube 1, which can consist of Cu, is placed in a holder 2 where it is latched. Then, submount 3, its upper and lower surfaces covered with a thin layer of an eutectic compound (e.g., 80% Au/20% Sn) having a thickness of about 4 mm, is precisely mounted on the mounting cube 1 using a vacuum-operated capillary tube 4. Submount 3 serves as heat spreader and thermal expansion match and may consist of a Cu/W compound. Subsequently, the laser diode 5 is placed on submount 3, again using capillary tube 4. Through the latter, a continuous pressure of about 12 g is applied to the laser diode.

Throughout the bonding process, carried out in a forming gas atmosphere (e.g., H2/N2), pre-heating plate 6 is maintained at a constant temperature of about 240oC. For bonding, a light source 7 with focussing mirror 8 produces a "hot spot", increasing the temperature of the mounting cube to about 320oC. The high temperature is maintained until melting of the eutectic compound. This takes about 30 to 40 seconds and c...