Method of manufacturing a polycrystalline semiconductor thin film
A TFT and the like capable of realizing performances such as a low threshold voltage value, high carrier mobility and a low leak current easily. A TFT consists of a polycrystalline Si film having a small heat capacity part and a large heat capacity part, and the small heat capacity part is used at least as a channel part. The polycrystalline Si film is formed of a crystal grain film through laser annealing of an energy density with which the small heat capacity part melts completely but the large heat capacity part does not melt completely. Since the channel part is formed of large crystal grains grown from the boundaries between the small heat capacity part and the large heat capacity parts, it is possible to realize performances such as a low threshold voltage value, high carrier mobility and a low leak current by using a typical laser annealing device.
1. The method of manufacturing a polycrystalline semiconductor thin film, comprising:
a semiconductor film forming step in which a nonmonocrystalline semiconductor thin film including a large heat capacity part having a large heat capacity and a small heat capacity part having a small heat capacity is formed on a substrate; and
an annealing step in which a laser beam of an energy density with which the small heat capacity part melts completely but the large heat capacity part does not melt completely is irradiated to the non-monocrystalline semiconductor thin film, wherein
in the laser annealing step,
the laser beam is a pulse laser beam of a spot diameter processed to be in a linear shape having a short axis and a long axis, and
the laser beam is irradiated while being moved sequentially in a short axial direction with a moving distance not more than a grain diameter of a seed crystal of the non-single crystalline semiconductor thin film in the short axial direction.
2. The method of manufacturing the polycrystalline semiconductor thin film, as claimed in claim 1 , wherein the large heat capacity part only exists in a part of a region to which the laser beam is irradiated.
3. A method of manufacturing a polycrystalline semiconductor thin film, comprising:
a semiconductor thin film forming step in which a non-monocrystalline semiconductor thin film including a large heat capacity part having a large heat capacity and a small heat capacity part having a small heat capacity is formed on a substrate; and
an annealing step in which a laser beam of an energy density with which the small heat capacity part melts completely but the large heat capacity part does not melt completely is irradiated to the non-monocrystalline semiconductor thin film, wherein
in the semiconductor thin film forming step,
the small heat capacity part is interposed between two large heat capacity parts, and distances between the large heat capacity parts are made different depending on positions, to thereby form the non-monocrystalline semiconductor thin film.