Semiconductor device and method of manufacturing the same

A method of manufacturing an active matrix type device, said method comprising the steps of:

• introducing a material for promoting crystallization of silicon into an amorphous semiconductor film comprising silicon;
• crystallizing the amorphous semiconductor film to form a crystalline semiconductor film;
• forming at least a semiconductor island by patterning the crystalline semiconductor film, said semiconductor island including a channel region therein;
• forming a gate insulating film on the semiconductor island;
• forming a gate electrode over the semiconductor island having the gate insulating film therebetween;
• selectively introducing phosphorus into regions of the semiconductor island with the gate insulating film and the gate electrode as a mask in order to form a source region and a drain region and a pair of light doped regions;
• wherein the source and drain regions are rendered amorphous while the channel region remains crystalline;
• wherein one of the light doped regions is formed between the source region and the channel region while the other of the light doped regions is formed between the drain region and the channel region;
• annealing the semiconductor island to diffuse the material from the channel region where the phosphorus has not been introduced toward the source and drain regions where the phosphorus has been introduced through the pair of light doped regions;
• irradiating the semiconductor island with a light,
• wherein a first concentration of phosphorus in the source and drain regions is higher than a second concentration of the material in the channel region after the step of heating the semiconductor island to diffuse the material,
• wherein each of the source region and the drain region comprises phosphorus at a concentration in a range of 1×1020 to 2×1021 cm3, and each of the pair of light doped regions comprises phosphorus at a concentration in a range of 1×1017 to 2×1018 cm3.

A method of manufacturing a thin film transistor comprising the steps of:

• disposing a material for promoting crystallization of silicon in contact with an amorphous semiconductor film comprising silicon formed over a substrate;
• crystallizing the amorphous semiconductor film;
• patterning the crystallized semiconductor film into a semiconductor island;
• forming a gate insulating film on the semiconductor island;
• forming a gate electrode over a portion of the semiconductor island with the gate insulating film interposed therebetween;
• introducing phosphorus into portions of the semiconductor island with the gate insulating film and the gate electrode as a mask in order to form a source region, a drain region, a channel region and a pair of light doped regions in the semiconductor island;
• wherein one of the pair of light doped regions is formed between the source region and the channel region while the other of the pair of light doped regions is formed between the drain region and the channel region;
• wherein the channel region is defined between the pair of light doped regions;
• wherein the source and drain regions are rendered amorphous while the channel region remains crystalline;
• annealing the semiconductor island so that the material diffuses from the channel region toward the source and drain regions through the pair of light doped regions;
• irradiating the semiconductor island with a light,
• wherein a first concentration of phosphorus in the source and drain regions is higher than a second concentration of the material in the channel region after the step of heating the semiconductor island to diffuse the material,
• wherein each of the source region and the drain region comprises phosphorus at a concentration in a range of 1×1020 to 2×1021 cm−3, and each of the pair of light doped regions comprises phosphorus at a concentration in a range of 1×1017 to 2×1018 cm−3.