Method of cleaving semiconductor diode laser wafers

Abstract

Thick double heterostructure (Al,Ga)As wafers comprising layers of gallium arsenide and gallium aluminum arsenide on a metallized n-GaAs substrate are separated into individual devices for use as diode lasers. In contrast to prior art techniques employed with thinner wafers of mechanically cleaving the wafer in mutually orthogonal directions, the wafer is first separated into bars of diodes by a process which comprises (a) forming channels of substantially parallel sidewalls about 1 to 4 mils deep into the surface of the n-GaAs substrate (b) etching into the n-GaAs substrate with an anisotropic etchant to a depth sufficient to form V-grooves in the bottom of the channels and (c) mechanically cleaving into bars of diodes. The cleaving may be done by prior art techniques using a knife, razor blade or tweezer edge or by attaching the side of the wafer opposite to the V-grooves to a flexible adhesive tape and rolling the assembly in a manner such as over a tool of small radius. The diode bars may then, following passivation, be further cleaved into individual diodes by the prior art technique of mechanically scribing and cleaving. Processing in accordance with the invention results in good length definition and uniformity, high device yields and low density of striations on laser facets. The inventive process permits handling of thicker wafers on the order of 6 to 10 mils or so, which are cleaved only with great difficulty by prior art techniques. Such thicker wafers are less susceptible to breaking during handling and permit fabrication of shorter diode (cavity) length, which in turn is related to lower threshold current for device operation.

Dependencies are inferred from the claim text.