Polycrystalline silicon thin film transistor of liquid crystal display and manufacturing method thereof

A polycrystalline silicon TFT for an LCD, comprising:

• an active pattern formed on a substrate;
• a gate insulating layer formed on the substrate including the active pattern;
• a gate line formed on the gate insulating layer to cross the active pattern, said gate line including a gate electrode for defining a first impurity region, a second impurity region and a channel region;
• a first insulating interlayer formed on the gate insulating layer including the gate line;
• a data line formed on the first insulating interlayer;
• a second insulating interlayer formed on the first insulating interlayer including the data line;
• a pixel electrode formed at the second insulating interlayer and connected with the first impurity region through a second contact hole which is formed through the gate insulating layer, the first insulating interlayer and the second insulating interlayer on the first impurity region;
• and
• an electrode formed on the second insulating layer and formed from a same layer as in the pixel electrode, the electrode connecting the data line and the second impurity region through a first contact hole which is formed through the gate insulating layer and the first and second insulating interlayers on the second impurity region and a third contact hole which is formed at the second insulating interlayer on the data line.

A method of manufacturing a polycrystalline silicon TFT for an LCD, comprising steps of:

• forming an active pattern on a substrate;
• forming a gate insulating layer on the substrate including the active pattern;
• forming a gate layer on the gate insulating layer;
• patterning the gate layer to form a gate line and performing an ion-implanting process to form a first impurity region and a second impurity region at the active pattern;
• forming an insulating interlayer on the insulating layer and on the gate line;
• partially etching the insulating interlayer and the gate insulating layer to form a first contact hole for exposing the second impurity region and a second contact hole for exposing the first impurity region;
• forming a conductive layer on the insulating interlayer including the first and second contact holes;
• and
• patterning the conductive layer to form a data line which is connected through the first contact hole to the second impurity region and a pixel electrode which is connected through the second contact hole to the first impurity region.

A method of manufacturing a polycrystalline silicon TFT for an LCD, comprising steps of:

• forming an active pattern on a substrate;
• forming a gate insulating layer on the substrate including the active pattern;
• forming a gate layer on the gate insulating layer;
• patterning the gate layer to form a gate line and performing an ion-implanting process to form a first impurity region and a second impurity region at the active pattern;
• forming a first insulating interlayer on the insulating layer including the gate line;
• forming a data line on the first insulating interlayer;
• forming a second insulating interlayer on the first insulating interlayer including the data line;
• partially etching the second insulating interlayer, the first insulating interlayer or the gate insulating layer to form a first contact hole for exposing the second impurity region, a second contact hole for exposing the first impurity region and a third contact hole for exposing the data line;
• forming a conductive layer on the second insulating interlayer;
• and
• patterning the conductive layer to form an electrode which connects the data line and the second impurity region through the first and third contact holes, and a pixel electrode which is connected through the second contact hole to the first impurity region.