Stepped edge structure of an EEPROM tunneling window

Details Stepped edge structure of an EEPROM tunneling window Stepped edge structure of an EEPROM tunneling window

1998-09-04

1999-06-29

Thomas, Tom

Active solid-state devices (e.g., transistors, solid-state diode

Field effect device

Having insulated electrode

257315, H01L 29788

Patent

active

059172150

ABSTRACT:
The present invention provides a structure and a method of forming a stepped trench oxide structure for a semiconductor memory device. The stepped trench oxide structure has "oxide steps" (e.g., 252 or 34A, 34B, 34C) in the gate oxide 20 surrounding the tunnel oxide layer 30. The oxide steps 34 are formed where the oxide thinning effect normally thins the tunnel oxide 30 around the perimeter of the tunnel oxide layer 30. The oxide steps 34 252 compensate for the oxide thinning effect and eliminate the problems associated with the oxide thinning effects. The oxide steps are preferably formed using one photo mask to form two different sized openings using different photoresist exposure times. The preferred method comprises forming a first tunneling opening 220A in a first (gate) oxide layer 220. Then, forming a second oxide layer 250 over said exposed substrate and said first oxide layer 220. A second opening 250A (smaller than the first opening) is formed in the second oxide layer thereby forming a first step 252. Next, a third oxide layer 270 is formed over said exposed substrate, the first oxide layer 220 and the second oxide layer 250 thereby propagating the first step 252. The oxide thinning edge effect is eliminated by the first step.

REFERENCES:
patent: 5352618 (1994-10-01), Larsen et al.
patent: 5379253 (1995-01-01), Bergemont
patent: 5422505 (1995-06-01), Shirai
patent: 5534455 (1996-07-01), Liu

Affiliated with

Also associated with

Rating

Stepped edge structure of an EEPROM tunneling window does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Stepped edge structure of an EEPROM tunneling window, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stepped edge structure of an EEPROM tunneling window will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1377746