Laser heating of a two-layer system with constant surface absorption: an exact solution

The annealing of semiconductors is of critical importance for successful electronic device fabrication. The present review surveys the new field of transient annealing and covers all timescales below those available with the conventional furnace. The work outlined includes the use of techniques which rely upon transient energy deposition in semiconductors from laser, electron beam, ion beam and other radiant sources. The many advances which have been achieved using these transient annealing methods in both fundamental and applied areas of physics are described.

http://iopscience.iop.org/article/10.1088/0034-4885/48/8/002/pdf

Transient annealing of semiconductors by laser, electron beam and radiant heating techniques

The problem of heating a homogeneous slab of material induced by time‐dependent laser irradiance is studied. An exact solution for the temperature distribution of the slab is obtained using the Fourier series expansion technique. The temperatures for the front and rear surfaces are also obtained. The case of time‐independent laser irradiance is considered. The exact expressions for the thermal penetration depth and the critical time required to initiate melting (i.e., damage) are recovered and compared with the published data for this special case.

Heating a slab induced by a time‐dependent laser irradiance—An exact solution

Random layout of devices or active regions of the devices is allowed for a semiconductor integrated circuit based on an SOI technology using an anti-reflecting film (14). Openings (123) are provided for the anti-reflecting film (14) 'formed on a polycrystalline silicon layer (13), corresponding to the device regions wherein devices or active regions of the devices are to be formed. An orverlapped scan of a laser (LB) beam having diameter larger than the dimension of the openings (123) is applied on the silicon layer (13) through the openings and circumferential anti-reflecting film (14). Concaved temperature profile is achieved along every directions (m) across the openings due to the enhanced beam (LB) absorption by the circumferential anti-reflecting film (14), hence recrystallization nucleation of the silicon layer initiates at the center of each opening during the laser beam scan. Thus, self-aligned single crystal regions (113) are fabricated in the polycrystalline silicon layer (13) at the respective predetermined device regions. The channel region of an IG-FET is exclusively formed in the single crystal region (113) and the source or drain regions are formed in adjacent polysilicon regions.

A manufacturing method of an integrated circuit based on semiconductor-on-insulator technology

3-D VLSI technology in Japan and an example: a syndrome decoder for double error correction

Complete single crystalline silicon films over SiO2 have been produced with a heat‐sink structure designed for best utilization of temperature gradients during resolidification process induced by an incident cw Ar laser beam. The structure includes device regions with thin SiO2 layers which act as a heat sink to the substrate and the peripheral regions with thick SiO2 layers. By using this technique, residual grain boundaries in the laser recrystallized silicon over insulator can be eliminated. N‐channel metal‐oxide‐semiconductor field‐effect transistors fabricated in the recrystallized silicon films with a heat‐sink structure exhibit good device characteristics, having a surface electron mobility of 500 cm2/V s which is comparable to that of bulk devices.

N. Sasaki

Papers

Laser recrystallization of Si over SiO2 with a heat‐sink structure