Image display device using transistors each having a polycrystalline semiconductor layer, as well as manufacturing method of such image display device

An image display device using transistors each having a polycrystalline Si layer, comprising:

• a gate electrode formed on an upper surface of the polycrystalline Si layer with an insulating film interposed therebetween, a drain region being formed in the polycrystalline Si layer on one side of the gate electrode, and a source region being formed in the polycrystalline Si layer on another side of the gate electrode;
• activated boron added to the polycrystalline Si layer in an area underlying the gate electrode;
• and
• activated phosphorus added to the polycrystalline Si layer in an area excluding the area underlying the gate electrode,
• the polycrystalline Si layer having areas which respectively extend from the area underlying the gate electrode to the drain region and the source region and in which the activated boron is distributed to gradually decrease from the area underlying the gate electrode toward the drain region and the source region, respectively.

A manufacturing method of an image display device, comprising:

• a step of adding an N-type impurity to an amorphous Si layer formed on an upper surface of a substrate;
• a step of forming an N-type polycrystalline Si layer by irradiating the amorphous Si layer with laser light;
• a step of forming an insulating film on an upper surface of the N-type polycrystalline Si layer;
• a step of selectively adding a P-type impurity to an area between a drain region and a source region of the N-type polycrystalline Si layer;
• and
• a step of forming a gate electrode on a part of the area to which the P-type impurity is added.