Sanyo Electric Co., Ltd.

Other

Sony Corporation

Sanyo Electric., Ltd.

Ken Wakita

Hidenori Ogata

Yoshihiro Morimoto

Kazuhiro Imao

Kiyoshi Yoneda

Tsutomu Yamada

Takashi Kuwahara

Yushi Jinno

Masahiro Minegishi

Shiro Nakanishi

Takashi Hagino

Toshio Monzen

For obtaining p-Si by irradiating a laser beam to an a-Si layer to polycrystallize, an energy level in a region to be irradiated by the laser beam is set such that a level at the rear area of the region along a scan direction of the laser beam is lower than that at the front area or the center area of the region. The energy level at the front area or the center area of the region is set such that it is substantially equal to or more than the upper limit energy level which maximizes a grain size of the p-Si obtained. Since an energy profile is set as described above, when the laser beam is scanned on the a-Si layer, an irradiated energy of the laser on the region is gradually lowered from the upper limit as the laser beam passes through, which allows the semiconductor layer to be annealed within an optimal energy level during the latter half of the annealing process.

Laser anneal method of a semiconductor layer

A thin film transistor which can be used in an LCD display panel includes an insulator substrate, a gate electrode located on the insulator substrate, an insulator film provided on the insulator substrate and the gate electrode, and a polycrystalline silicon film located on the insulator film. A channel is defined in a first portion of the polycrystalline silicon film over the gate electrode, and a drain and a source are defined in second and third portions of the polycrystalline silicon film over the insulator substrate. Grain sizes of the drain and source are equal to or greater than a grain size of the channel.

Thin film transistor and method of fabricating the same

A laser annealing apparatus is provided in which laser light is irradiated onto an amorphous semiconductor layer placed inside an annealing chamber through a chamber window, thereby poly-crystallizing the amorphous semiconductor film. Inside the annealing chamber a low degree vacuum (about 1.3&times;10 Pa to about 1.3 Pa) is maintained at a room temperature. An inert gas such as nitrogen, hydrogen, or argon is introduced into the atmosphere while maintaining the low degree vacuum. As a result, the surface smoothness of the polycrystalline semiconductor layer is comparable to that resulting from high degree vacuum annealing, while, unlike high degree vacuum annealing, there is less contamination of the chamber window and productivity is improved.

Method for manufacturing polycrystalline semiconductor layers and thin-film transistors and laser annealing apparatus

For obtaining p-Si by irradiating a laser beam to an a-Si layer to polycrystallize, an energy level in a region to be irradiated by the laser beam is set such that a level at the rear area of the region along a scan direction of the laser beam is lower than that at the front area or the center area of the region. The energy level at the front area or the center area of the region is set such that it is substantially equal to or more than the upper limit energy level which maximizes a grain size of the p-Si obtained. since an energy profile is set as described above, when the laser beam is scanned on the a-Si layer, an irradiated energy of the laser on the region is gradually lowered from the upper limit as the laser beam passes through, which allows the semiconductor layer to be annealed within an optimal energy level during the latter half of the annealing process.

Thin film transistor suitable for use in an active matrix type display and method of fabricating the same

Laser anneal processing of a semiconductor layer is repeated in a number of steps. Grain size is increased using high energy ELA for a first step, and grain sizes are uniformed using ELA with low energy for a later step. As a defective crystallization region occurs in an excessive energy region during the ELA for the first step, in the ELA for the second time, excessive energy is removed and the defective crystallization region is eliminated by reducing the energy to an optimal value, thereby improving the crystallinity of a p-Si layer.

Laser anneal method for a semiconductor device

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Gifu, Japan

Ken Wakita