Method and device for a split-gate flash memory with an extended word gate below a channel region

摘要

A split gate memory cell is fabricated with a word gate extending below an upper surface of a substrate having the channel region. An embodiment includes providing a band engineered channel with the word gate extending there through. Another embodiment includes forming a buried channel with the word gate extending below the buried channel.

主权项

1. A method comprising:
providing a memory gate stack over a channel region; providing a word gate extending from an upper portion at an upper surface of the memory gate stack to a lower portion below an upper surface of a substrate at the channel region and below an upper surface of the substrate at source and drain regions, wherein the lower portion of the word gate contacts both the channel region and a source or drain region, and wherein the upper portion of the word gate and the lower portion of the word gate have the same width; and planarizing the memory gate stack and the word gate such that an upper surface of the memory gate stack and an upper surface of the word gate are substantially coplanar.