Thin film transistor having lightly doped regions

A semiconductor device comprising a pixel portion and a driver circuit for driving said pixel portion formed over a same substrate, said pixel portion comprising:

• an n-channel type thin film transistor over said substrate, said n-channel type thin film transistor comprising:
• a semiconductor layer having at least a source region, a drain region, a channel forming region, and a lightly doped region;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region is disposed so as not to overlap said gate electrode, and an offset region is formed between said channel forming region and said lightly doped region, and
• said driver circuit comprising:
• a first and a second n-channel type thin film transistors over said substrate, each of said first and said second n-channel type thin film transistors comprising:
• a semiconductor layer having at least a source region, a drain region, a channel forming region, and a lightly doped region;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region of said first n-channel type thin film transistor is disposed so as to entirely overlap said gate electrode of said first n-channel type thin film transistor,
• wherein said lightly doped region of said second n-channel type thin film transistor is disposed so as to partly overlap said gate electrode of said second n-channel type thin film transistor.

A semiconductor device comprising a pixel portion and a driver circuit for driving said pixel portion formed over a same substrate, said pixel portion comprising:

• an n-channel type thin film transistor over said substrate, said n-channel type thin film transistor comprising:
• a semiconductor layer having at least a source region, a drain region, a channel forming region, and a lightly doped region;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region is disposed so as not to overlap said gate electrode, and
• said driver circuit comprising:
• a first and a second n-channel type thin film transistors over said substrate, each of said first and said second n-channel type thin film transistors comprising:
• a semiconductor layer having at least a source region, a drain region, a channel forming region, and a lightly doped region;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region of said first n-channel type thin film transistor is disposed so as to entirely overlap said gate electrode of said first n-channel type thin film transistor,
• wherein said lightly doped region of said second n-channel type thin film transistor is disposed so as to partly overlap said gate electrode of said second n-channel type thin film transistor.

A semiconductor device comprising a pixel portion and a driver circuit for driving said pixel portion formed over a same substrate, said pixel portion comprising:

• an n-channel type thin film transistor over said substrate, said n-channel type thin film transistor comprising:
• a semiconductor layer having at least a source region, a drain region, a channel forming region, and a lightly doped region;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region is disposed so as not to overlap said gate electrode, and
• said driver circuit comprising:
• a first and a second n-channel type thin film transistors over said substrate, each of said first and said second n-channel type thin film transistors comprising:
• a semiconductor layer having at least a source region, a drain region, a channel forming region, and a lightly doped region comprising an n-type impurity between 2×1016 and 5×1019 atoms/cm3;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region of said first n-channel type thin film transistor is disposed so as to entirely overlap said gate electrode of said first n-channel type thin film transistor,
• wherein said lightly doped region of said second n-channel type thin film transistor is disposed so as to partly overlap said gate electrode of said second n-channel type thin film transistor.

A semiconductor device comprising a pixel portion and a driver circuit for driving said pixel portion formed over a same substrate, said pixel portion comprising:

• an n-channel type thin film transistor over said substrate, said n-channel type thin film transistor comprising:
• a semiconductor layer having at least a source region, a drain region, a channel forming region, and a lightly doped region comprising an n-type impurity between 1×1016 and 5×1018 atoms/cm3;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region is disposed so as not to overlap said gate electrode, and
• said driver circuit comprising:
• a first and a second n-channel type thin film transistors over said substrate, each of said first and said second n-channel type thin film transistors comprising:
• a semiconductor layer having at least a source region, a drain region, a channel forming region, and a lightly doped region comprising an n-type impurity between 2×1016 and 5×1019 atoms/cm3;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region of said first n-channel type thin film transistor disposed so as to entirely overlap said gate electrode of said first n-channel type thin film transistor,
• wherein said lightly doped region of said second n-channel type thin film transistor is disposed so as to partly overlap said gate electrode of said second n-channel type thin film transistor.

A semiconductor device comprising:

• a pixel thin film transistor and a driver circuit for driving said pixel thin film transistor over a substrate, said pixel thin film transistor comprising:
• a semiconductor layer having at least a pair of impurity regions, a channel forming region, and a lightly doped region interposed between at least one of said pair of impurity regions and said channel forming region, said lightly doped region having a length of 3.5 μm or less along said channel forming region;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region does not overlap said gate electrode, and
• said driver circuit comprising:
• a first and a second n-channel type thin film transistors over said substrate, each of said first and said second n-channel type thin film transistors comprising:
• a semiconductor layer having at least a pair of impurity regions, a channel forming region, and a lightly doped region interposed between at least one of said of impurity regions and said channel forming region;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region of said first n-channel type thin film transistor entirely overlaps said gate electrode of said first n-channel type thin film transistor, and
• wherein said lightly doped region of said second n-channel type thin film transistor partially overlaps said gate electrode of said second n-channel type thin film transistor.

A semiconductor device comprising:

• a pixel thin film transistor and a driver circuit for driving said pixel thin film transistor over a substrate, said pixel thin film transistor comprising:
• a semiconductor layer having at least a pair of impurity regions, a channel forming region, and a lightly doped region interposed between at least one of said pair of impurity regions and said channel forming region, said lightly doped region having a length of 3.5 μm or less along said channel forming region;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region does not overlap said gate electrode, and
• said driver circuit comprising:
• a first and a second n-channel type thin film transistors over said substrate, each of said first and said second n-channel type thin film transistors comprising:
• a semiconductor layer having at least a pair of impurity regions, a channel forming region, and a lightly doped region interposed between at least one of said pair of impurity regions and said channel forming region, said lightly doped region containing an n-type impurity between 2×1016 and 5×1019 atoms/cm3;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region of said first n-channel type thin film transistor entirely overlaps said gate electrode of said first n-channel type thin film transistor, and
• wherein said lightly doped region of said second n-channel type thin film transistor partially overlaps said gate electrode of said second n-channel type thin film transistor.

A semiconductor device comprising:

• a pixel thin transistor and a driver circuit for driving said pixel thin film transistor over a substrate, said pixel thin film transistor comprising:
• a semiconductor layer having at least a pair of impurity regions, a channel forming region, and a lightly doped region interposed between at least one of said pair of impurity regions and said channel forming region, said lightly doped region having a length of 3.5 μm or less along said channel forming region, and containing an n-type impurity between 1×1016 and 5×1018 atoms/cm3;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region does not overlap said gate electrode, and
• said driver circuit comprising:
• a first and a second n-channel type thin film transistors over said substrate, each of said first and second n-channel type thin film transistors comprising:
• a semiconductor layer having at least a pair of impurity regions, a channel forming region, and a lightly doped region interposed between at least one of said pair of impurity regions and said channel forming region;
• and
• a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween,
• wherein said lightly doped region of said first n-channel type thin film transistor entirely overlaps said gate electrode of said first n-channel type thin film transistor, and
• wherein said lightly doped region of said second n-channel type thin film transistor partially overlaps said gate electrode of said second n-channel type thin film transistor.