THIN FILM TRANSISTOR AND A MANUFACTURING METHOD THEREOF

摘要

PURPOSE: A method for manufacturing a thin film transistor(TFT) is provided to effectively control off-current, by making a thickness of a channel region of an active region thinner in a drain region than in a source region, so that a drain area can be reduced and a carrier mobility of an electron or hole is decreased. CONSTITUTION: The first silicon layer(204) is formed on an insulating substrate(200). The first mask pattern covering a predetermined region is formed on the first silicon layer. The second silicon layer covering the first mask pattern is formed on the insulating substrate. The second silicon layer is crystallized to form an active layer(220). The second mask pattern is formed on the active layer which exposes a portion corresponding to the first mask pattern and covers a peripheral portion of the first mask pattern. The active layer and first mask pattern are eliminated to form a groove on the first silicon layer by using the second mask pattern as a mask. The second mask pattern is removed. A gate electrode(216) is formed by intervening a gate insulating layer on the groove. Impurity ions of the first conductivity type are doped to the active layer to form a source/drain region. Source/drain electrodes respectively connected to the source/drain regions are formed on the active layer.