摘要:
A method (200) of forming a NAND type flash memory device includes the steps of forming an oxide layer (202) over a substrate (102) and forming a first conductive layer (106) over the oxide layer. The first conductive layer (106) is etched to form a gate structure (107) in a select gate transistor region (105) and a floating gate structure (106a, 106b) in a memory cell region (111). A first insulating layer (110) is then formed over the memory cell region (111) and a second conductive layer (112, 118) is formed over the first insulating layer (110). A word line (122) is patterned in the memory cell region (111) to form a control gate region and source and drain regions (130, 132) are formed in the substrate (102) in a region adjacent the word line (122) and in a region adjacent the gate structure (107). A second insulating layer (140) is formed over both the select gate transistor region (105) and the memory cell region (111) and first and second contact openings are formed in the second insulating layer (140) down to the gate structure (107) and the control gate region, wherein a depth (X) through the second insulating layer (140) down to the gate structure (107) and down to the control gate region are approximately the same, thereby eliminating a substantial overetch of the gate structure contact opening.
摘要:
A NAND flash memory system is programmed with minimal program disturb and pass disturb during self-boosting without resorting to impurity implantation for bit line isolation, to p-well biasing or to bit line biasing techniques. A program voltage is applied to a selected word line in the form of a plurality of short pulses while synchronously applying a pulsed pass voltage to the unselected word lines until the selected cell is programmed. The duration of the pulses and the time between pulses are chosen to minimize the program disturb of unselected cells, especially unselected cells on the selected word line, without causing pass disturb of any cell in the array.