Trench device structure and fabrication

A vertical-current-flow device, comprising:

• a trench which includes an insulated gate and which extends down into first-conductivity-type semiconductor material;
• a glass layer containing a dopant above said insulated gate;
• permanent charge that forms an inversion layer at the semiconductor surface adjacent to said glass layer;
• a doped polysilicone layer above said glass layer;
• source and body diffusions of opposite conductivity types adjacent a sidewall of said trench;
• a drift region positioned to receive majority carriers which have been injected by said source, and which have passed through said body diffusion;
• and
• a drain region positioned to receive majority carriers which have passed through said drift region;
• wherein said gate is capacitively coupled to control inversion of a portion of said body region;
• further comprising a lightly doped diffusion between said source diffusion and said body diffusion.

A high-density vertical power device, comprising:

• at least one active device area;
• at least one buried gate electrode, in a patterned trench within said active device area, which is capacitively coupled to control vertical current flow through semiconductor material adjacent to at least part of said buried gate electrode, between a source which lies alongside said trench and a drain which lies below said trench;
• and
• at least one buried source contact electrode, in said patterned trench above said gate electrode, which makes contact to said source;
• permanent charge embedded in sidewalls of said patterned trench, between said buried gate electrode and said buried source contact electrode;
• wherein said buried gate electrode and said buried source contact electrode have patterns which are identical within said active device areas, but differ elsewhere.