Method of storing a data bit in a phase change alloy material with an electron beam

Abstract

Alloy memory structures and methods are disclosed wherein a layer or volume of alloy material changes conductivity subsequent to introduction of a electron beam current-induced change in phase of the alloy, the conductivity change being detected using current detection means such as photon-emitting P-N junctions, and being associated with a change in data bit memory state.

1 . A method of storing a data bit comprising:
 exposing a volume of fast-write alloy to an electron beam to heat the volume of fast-write alloy to a temperature equivalent to about 110% of the melting temperature for the fast-write alloy;   cooling the volume of fast-write alloy along a cooling profile associated with an amorphous phase and a stored data bit memory state.   
   
   
       2 . The method of  claim 1  wherein cooling the volume of fast-write alloy along a cooling profile comprises cooling past the recrystallization temperature for the volume of fast-write alloy within 2 nanoseconds. 
   
   
       3 . The method of  claim 1  wherein cooling the volume of fast-write alloy comprises a cooling rate that is faster than a crystal nucleation and growth rate to avoid a formation of a highly-ordered crystalline structure. 
   
   
       4 . The method of  claim 1  wherein the fast-write alloy is used in high-speed optical storage devices. 
   
   
       5 . The method of  claim 1  wherein the fast-write alloy comprises combinations of Germanium, Antimony, and Tellurium. 
   
   
       6 . The method of  claim 1  wherein the fast-write alloys comprises combinations of Silver, Indium, Antimony, and Tellurium. 
   
   
       7 . The method of  claim 1  wherein the amorphous phase has relatively low electrical conductivity. 
   
   
       8 . The method of  claim 1  wherein a relatively fast cooling is achieved by avoiding further e-beam irradiation. 
   
   
       9 . The method of  claim 8  wherein the relatively fast cooling prevents the heated material from nucleating relatively large, contiguous crystals based upon adjacent crystallites of a same material positioned around a boundary of a heated region. 
   
   
       10 . The method of  claim 5  wherein the melting temperature is 616 degrees Celsius. 
   
   
       11 . The method of  claim 5  wherein the recrystallization temperature is 142 degrees Celsius. 
   
   
       12 . The method of  claim 1  wherein the fast-write alloy is melted since an amorphous phase result is desired. 
   
   
       13 . The method of  claim 1  wherein a faster cooling profile is achieved by avoiding thermal mass in an adjacent structure during the cooling. 
   
   
       14 . The method of  claim 1  wherein the cooling at a data cell location may be controllably speeded up by not irradiating structures immediately surrounding the location to create thermal mass around the location. 
   
   
       15 . The method of  claim 1  wherein the electron beam is modulated to a higher energy to write the data bit. 
   
   
       16 . The method of  claim 1  wherein writing the data bit is accomplished at a higher energy than reading the data bit.