A thin film semiconductor device comprising: a flexible substrate (SUB) extending in a first direction and a second direction perpendicular to the first direction; and a thin film transistor (TFT) disposed on the substrate (SUB) and comprising a semiconductor layer comprising a source region (SR), a drain region (DR), and a channel region (CR) between the source region (SR) and the drain region (DR), wherein a part of the source region (SR) is spaced apart from the drain region (DR) and partially surrounds the drain region (DR), and wherein a part of the drain region (DR is spaced apart from the source region (SR) and partially surrounds the source region (SR), wherein the source region (SR) and the drain region (DR) have a line shape and are identical in shape and can be exchanged in position by a 180 degree rotation, and characterized in that the channel region (CR) comprises a channel length (L) defined as a distance between the source region (SR) and the drain region (DR) and a channel width (W) defined along a direction perpendicular to the channel length (L), and the channel length (L) is uniform, wherein the channel region (CR) comprises a plurality of first portions (C1) having channel lengths (L) perpendicular to the first direction and a plurality of second portions (C2) having channel lengths (L) in a direction perpendicular to the second direction, wherein an area occupied by the first portions (C1) and an area occupied by the second portions (C2) are adjusted so that an average channel length of the thin film transistor (TFT) remains unchanged upon the thin film semiconductor device being rolled, folded or subjected to tensile forces. a flexible substrate (SUB) extending in a first direction and a second direction perpendicular to the first direction; and a thin film transistor (TFT) disposed on the substrate (SUB) and comprising a semiconductor layer comprising a source region (SR), a drain region (DR), and a channel region (CR) between the source region (SR) and the drain region (DR), wherein a part of the source region (SR) is spaced apart from the drain region (DR) and partially surrounds the drain region (DR), and wherein a part of the drain region (DR is spaced apart from the source region (SR) and partially surrounds the source region (SR), wherein the source region (SR) and the drain region (DR) have a line shape and are identical in shape and can be exchanged in position by a 180 degree rotation, and characterized in that the channel region (CR) comprises a channel length (L) defined as a distance between the source region (SR) and the drain region (DR) and a channel width (W) defined along a direction perpendicular to the channel length (L), and the channel length (L) is uniform, wherein the channel region (CR) comprises a plurality of first portions (C1) having channel lengths (L) perpendicular to the first direction and a plurality of second portions (C2) having channel lengths (L) in a direction perpendicular to the second direction, wherein an area occupied by the first portions (C1) and an area occupied by the second portions (C2) are adjusted so that an average channel length of the thin film transistor (TFT) remains unchanged upon the thin film semiconductor device being rolled, folded or subjected to tensile forces. <EOS>