Method of making high density mask ROM having a two level bit li

Details Method of making high density mask ROM having a two level bit li Method of making high density mask ROM having a two level bit li

1997-10-15

2000-03-14

Chaudhari, Chandra

Semiconductor device manufacturing: process

Making field effect device having pair of active regions...

Having insulated gate

438282, 438529, H01L 218246

Patent

active

060372273

ABSTRACT:
A mask ROM uses a bit line structure having a vertically graded dopant distribution or a distinct two level dopant distribution. A bit line might include a highly doped region buried deeply within the substrate that is connected to a comparatively lightly doped region formed above the more highly doped region. The vertical structure of the bit line allows the bit line to be less resistive than the simpler shallow bit line structure conventionally used. The vertical structure (i.e., the two level or graded structure) of the bit line allows the bit line to have a lower doping immediately adjacent the channel region, which reduces the likelihood of punchthrough. The deeper, highly doped portions of the bit line are narrow and laterally confined so that well defined antipunchthrough implantations can be formed which lie between but separated from the more highly doped portions of the bit lines. This aspect of the structure reduces the likelihood of punchthrough while limiting the extent of overlap between the buried bit lines and the antipunchthrough implantation.

REFERENCES:
patent: 4649629 (1987-03-01), Miller et al.
patent: 4717684 (1988-01-01), Katto et al.
patent: 5470774 (1995-11-01), Kunitou
patent: 5538914 (1996-07-01), Chiu et al.
patent: 5670402 (1997-09-01), Sogawa et al.

Affiliated with

Also associated with

Rating

Method of making high density mask ROM having a two level bit li does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method of making high density mask ROM having a two level bit li, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of making high density mask ROM having a two level bit li will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-168788