Method for fabricating low-defect-density changed orientation Si
View Patent ↗The present invention provides a method for forming low-defect density changed-orientation Si by amorphization/templated recrystallization (ATR) processes in which regions of Si having a first crystal orientation are amorphized by ion implantation and then recrystallized into the orientation of a template layer having a different orientation. More generally, the invention relates to the high temperature annealing conditions needed to eliminate the defects remaining in Si-containing single crystal semiconductor materials formed by ion-implant-induced amorphization and templated recrystallization from a layer whose orientation may be the same or different from the amorphous layer's original orientation. The key component of the inventive method is a thermal treatment for minutes to hours in the the temperature range 1250-1330° C. to remove the defects remaining after the initial recrystallization anneal. The invention also provides a low-defect density changed-orientation Si formed by ATR for use in hybrid orientation substrates.
1. A method for forming low-defect-density changed-orientation silicon comprising the steps of
selecting a substrate which includes a first silicon layer having a first orientation bonded to a second silicon layer having a second orientation different from the first;
amorphizing selected areas of the first silicon layer by ion implantation; and
recrystallizing the amorphized first silicon layer into the orientation of the second silicon layer using the second silicon layer as a crystal template, said recrystallization performed with a recrystallization process that produces a recrystallized material with a low defect density, said recrystallization process including a heat treatment for a time period of at least 10 seconds in the temperature range 1250-1350° C., wherein prior to said heat treatment a disposable cap is deposited and after said heat treatment said disposable cap is removed.
2. The method of claim 1 wherein the selected area amorphization is effected by implantation of Si and/or Ge ions.
3. The recrystallization process of claim 1 including a heat treatment for a time of at least 2 hours in the temperature range 1250-1350° C.
4. The heat treatment of claim 1 performed in at least one ambient selected from the group including vacuum, He, Ne, Ar, Kr, Xe, nitrogen and nitrogen-containing gases, oxygen and oxygen-containing gases, halogens and halogen-containing gases, carbon-containing gases, hydrogen and hydrogen-containing gases, and mixtures thereof.
5. The heat treatment of claim 1 performed in an ambient comprising Ar with 0.01 to 2% O 2 .
6. The method of claim 1 wherein at least one of said first and second silicon layers include dopants or impurities at a concentration below 2 atomic percent.
7. The method of claim 1 wherein said recrystallized Si material with a low defect density has one of the following orientations: 100, 110.
8. The method of claim 1 wherein said substrate includes embedded regions of insulator for at least some part of said recrystallization process.
9. A method for forming low-defect-density changed-orientation silicon comprising the steps of
selecting a substrate which includes a first silicon layer having a first orientation bonded to a second silicon layer having a second orientation different from the first;
amorphizing selected areas of the first silicon layer by ion implantation; and recrystallizing the amorphized first silicon layer into the orientation of the second silicon layer using the second silicon layer as a crystal template, said recrystallization performed with a recrystallization process that produces a recrystallized material with a low defect density, said recrystallization process including a heat treatment performed in an ambient comprising Ar with 0.01 to 2% O 2 for a time period of at least 10 seconds in the temperature range 1250-1350° C.