Method for forming memory array bitlines comprising epitaxially grown silicon and related structure
View Patent ↗According to one exemplary embodiment, a method of fabricating a bitline in a memory array includes forming a trench in a substrate, where the trench has sidewalls and a bottom surface. The method further includes performing a selective epitaxial process to partially fill the trench with selective epitaxially grown silicon, where the selective epitaxially grown silicon is situated on the sidewalls and bottom surface of the trench. The selective epitaxially grown silicon is doped in the selective epitaxial process. The method further includes performing a silicon reflow process to cause the selective epitaxially silicon to be redistributed in the trench. The method further includes performing a number of selective epitaxial process/silicon reflow process cycles to substantially fill the trench with the selective epitaxially grown silicon. The method further includes extending a top surface of the selective epitaxially grown silicon in the trench above an ONO stack to form the bitline.
1. A method for fabricating a bitline in a memory array, said method comprising steps of:
forming a trench in a substrate, said trench having sidewalls and a bottom surface;
performing a selective epitaxial process to partially fill said trench with selective epitaxially grown silicon, said selective epitaxially grown silicon being situated on said sidewalls and said bottom surface of said trench;
performing a silicon reflow process, wherein said silicon reflow process causes said selective epitaxially grown silicon to be redistributed in said trench, wherein said silicon reflow process comprises a hydrogen ambient bake process, and wherein said selective epitaxially grown silicon is doped in said selective epitaxial process.
2. The method of claim 1 further comprising a step of performing a plurality of selective epitaxial process/silicon reflow process cycles to substantially fill said trench with said selective epitaxially grown silicon.
3. The method of claim 2 further comprising a step of extending a top surface of said selective epitaxially grown silicon in said trench above an ONO stack situated on said substrate to form said bitline.
4. The method of claim 1 wherein said step of forming said trench in said substrate comprises forming said trench in an ONO stack situated on said substrate and extending said trench into said substrate.
5. The method of claim 2 wherein said step of performing said plurality of selective epitaxial process/silicon reflow process cycles comprises performing between two and eight selective epitaxial process/silicon reflow process cycles.
6. A method for fabricating a bitline in a memory array, said method comprising steps of:
forming a trench in a substrate, said trench having sidewalls and a bottom surface;
performing a selective epitaxial process to partially fill said trench with selective epitaxially grown silicon, said selective epitaxially grown silicon being situated on said sidewalls and said bottom surface of said trench;
performing a silicon reflow process, wherein said silicon reflow process causes said selective epitaxially grown silicon to be redistributed in said trench, wherein said silicon reflow process comprises a hydrogen ambient bake process, and wherein said selective epitaxially grown silicon is doped in said selective epitaxial process.
7. The method of claim 6 further comprising a step of performing a plurality of selective epitaxial process/silicon reflow process cycles to substantially fill said trench with said selective epitaxially grown silicon.
8. The method of claim 7 further comprising a step of extending a top surface of said epitaxially grown silicon in said trench above an ONO stack situated on said substrate to form said bitline.
9. The method of claim 6 wherein said step of forming said trench in said substrate comprises forming said trench in an ONO stack situated on said substrate and extending said trench into said substrate.