Pulse train annealing method and apparatus

Abstract

The present invention generally describes apparatuses and methods used to perform an annealing process on desired regions of a substrate. In one embodiment, pulses of electromagnetic energy are delivered to a substrate using a flash lamp or laser apparatus. The pulses may be from about 1 nsec to about 10 msec long, and each pulse has less energy than that required to melt the substrate material. The interval between pulses is generally long enough to allow the energy imparted by each pulse to dissipate completely. Thus, each pulse completes a micro-anneal cycle. The pulses may be delivered to the entire substrate at once, or to portions of the substrate at a time. Further embodiments provide an apparatus for powering a radiation assembly, and apparatuses for detecting the effect of pulses on a substrate.

1 . An apparatus for treating a substrate, comprising:
 a body portion;   a substrate support coupled to the body portion;   a source of electromagnetic radiation disposed in a radiation assembly, the radiation assembly coupled to the body portion;   one or more power supplies coupled to the radiation assembly; and   a controller coupled to the power supply, the radiation assembly, or both to direct pulses of electromagnetic energy toward the substrate support, wherein the controller is configured to operate an optical switch disposed between the source of electromagnetic radiation and the body portion.   
     
     
         2 . The apparatus of  claim 1 , wherein the source of electromagnetic radiation is a laser. 
     
     
         3 . The apparatus of  claim 1 , wherein the optical switch is a Pockels cell. 
     
     
         4 . The apparatus of  claim 1 , wherein the optical switch is configured to change state in less than 1 μsec. 
     
     
         5 . An apparatus for treating a substrate, comprising:
 a body portion;   a substrate support coupled to the body portion;   a source of electromagnetic radiation disposed in a radiation assembly, the radiation assembly coupled to the body portion;   one or more power supplies coupled to the radiation assembly; and   a controller coupled to the power supply, the radiation assembly, or both to direct pulses of electromagnetic energy toward the substrate support, wherein the controller is configured to pulse the power from the one or more power supplies to the radiation assembly.   
     
     
         6 . The apparatus of  claim 5 , wherein the controller pulses the power from the one or more power supplies to the radiation assembly by operating an electrical switch. 
     
     
         7 . The apparatus of  claim 6 , wherein the source of electromagnetic radiation is a laser, and the electrical switch discharges one or more capacitors. 
     
     
         8 . The apparatus of  claim 5 , wherein the source is electromagnetic radiation comprises two or more lasers, and the controller delivers a shaped pulse from the source of electromagnetic radiation. 
     
     
         9 . A method of treating a substrate, comprising:
 disposing the substrate on a substrate support;   stepping an energy source facing successive treatment zones of the substrate by moving the energy source, the substrate support, or both;   generating pulses of electromagnetic energy toward each of the successive treatment zones of the substrate; and   sub-melt annealing each treatment zone at least about 100 times.   
     
     
         10 . The method of  claim 9 , wherein generating the pulses of electromagnetic energy comprises interrupting a continuous beam of laser energy. 
     
     
         11 . The method of  claim 10 , wherein interrupting the continuous beam of laser energy comprises operating an optical switch disposed between the energy source and the substrate. 
     
     
         12 . The method of  claim 9 , wherein each pulse is tailored to a selected energy profile. 
     
     
         13 . The method of  claim 12 , wherein generating each tailored pulse comprises combining two or more pulses. 
     
     
         14 . A method of treating a substrate, comprising:
 positioning the substrate on a substrate support;   exposing successive treatment zones of the substrate surface to pulses of electromagnetic energy, wherein each pulse has energy less than that required to melt the treatment zone, and the pulses are separated by a duration selected to dissipate the energy of each pulse within the substrate before the next pulse arrives.   
     
     
         15 . The method of  claim 14 , wherein generating the pulses of electromagnetic energy comprises interrupting a continuous beam of laser energy. 
     
     
         16 . The method of  claim 14 , wherein each successive treatment zone is exposed to at least about 100 pulses of electromagnetic energy. 
     
     
         17 . The method of  claim 14 , further comprising preheating the substrate. 
     
     
         18 . The method of  claim 14 , wherein each pulse is tailored to a selected energy profile.