Fabrication processes for forming dual depth trenches using a dry etch that deposits a polymer
AssigneeMicron Technology, Inc.
InventorsXiaolong Fang, Ramakanth Alapati, Tuman E. Allen
Life of this patent
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Abstract
Trench isolation structures and methods to form same for use in the manufacture of semiconductor devices are described. The trench isolation structures are formed using several processing schemes that utilize disclosed dry etching processes to form a significant depth Δ between an array trench depth and a periphery trench depth. One etching method creates a trench delta depth utilizing a single dry etch step, while two other etching methods create a trench Δ depth by utilizing three dry etch steps.
Claims38
1-20. (canceled)
A fabrication process for forming dual depth trenches in a semiconductor memory device, the fabrication process comprising:
- performing a first dry etch step to etch an array trench and a periphery trench into a substrate to a depth;
- performing a second dry etch to increase the depth of the array trench and the depth of the periphery trench while depositing a polymer on sidewalls of the array trench and sidewalls of the periphery trench, the polymer covering a bottom of the array trench but not a bottom of the periphery trench, to create a trench Δ depth between the array trench depth and the periphery trench depth;
- and
- performing a third etch step to remove any remaining polymer deposited in the bottom of the array trench and to remove any induced kinks from the sidewalls of the periphery trench.
30-37. (canceled)
A fabrication process for forming dual depth trenches, the fabrication process comprising:
- performing a first dry etch to etch an array trench and a periphery trench into a semiconductor to a depth;
- and
- performing a second dry etch to increase the depth of the array trench and the depth of the periphery trench while depositing a polymer on sidewalls of the array trench and sidewalls of the periphery trench, the polymer covering a bottom of the array trench but not a bottom of the periphery trench, to create a trench Δ depth between the array trench depth and the periphery trench depth.
A fabrication process for forming dual depth trenches, the fabrication process comprising performing a dry etch to increase a depth of a periphery trench while depositing a polymer on sidewalls of an array trench and sidewalls of the periphery trench, the polymer covering a bottom of the array trench but not a bottom of the periphery trench, to create a trench Δ depth between the array trench depth and the periphery trench depth.
Dependencies are inferred from the claim text.