The Secretary of State for Defence in Her Britannic Majesty's Government

National Research Development Corporation

Anthony G Cullis

Hugh C Webber

Nigel G Chew

Paul Bailey

A digital storage device comprises a crystalline substrate such as silicon in which pockets of amorphous substrate material represent one of the binary logic states; the absence of amorphous material represents the other logic state. The amorphous material is formed by irradiation with a laser beam. Typically the radiation for silicon is at 347 nanometers, 2.5 nanosecond pulse length. The power density varies with crystalline orientation; for (001) silicon it is typically 0.3 J/cm.sup.2 and for (111) silicon it is 0.3 to 0.6 J/cm.sup.2. Erasure of the information is achieved by laser annealing the amorphous material back to its crystalline form.

Method for preparing digital storage device by laser application

An integrated circuit comprises a substrate having a plurality of components electrically isolated by regions of amorphous material formed by laser irradiation. Typically the laser radiation has a wavelength less than 400 nm a pulse length between 0.1 and 10 .mu.sec, and a power density between 0.1 and 0.8 J/cm.sup.2. The substrate material may be Si, Ge, GaAs, GaAlAs, InAs, InP, InAlP.

Integrated circuits

A laser beam diffuser for use in laser beam annealing comprises a silica laser beam guiding pipe, having a diffusing surface or layer at one end and a polished surface at the other end. The diffusing surface may be a ground surface. A bend or bends removes axial component of speckle produced by the ground surface. Adjacent the polished end the pipe may be of reduced cross section.

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Worcester, United Kingdom

Anthony G Cullis