Methods for processing an amorphous silicon thin film sample into a polycrystalline silicon thin film are disclosed. In one preferred arrangement, a method includes the steps of generating a sequence of excimer laser pulses, controllably modulating each excimer laser pulse in the sequence to a predetermined fluence, homoginizing each modulated laser pulse in the sequence in a predetermined plane, masking portions of each homoginized fluence controlled laser pulse in the sequence with a two dimensional pattern of slits to generate a sequence of fluence controlled pulses of line patterned beamlets, each slit in the pattern of slits being sufficiently narrow to prevent inducement of significant nucleation in region of a silicon thin film sample irradiated by a beamlet corresponding to the slit, irradiating an amorphous silicon thin film sample with the sequence of fluence controlled slit patterned beamlets to effect melting of portions thereof corresponding to each fluence controlled patterned beamlet pulse in the sequence of pulses of patterned beamlets, and controllably sequentially translating a relative position of the sample with respect to each of the fluence controlled pulse of slit patterned beamlets to thereby process the amorphous silicon thin film sample into a single or polycrystalline silicon thin film.

Methods for producing uniform large-grained and grain boundary location manipulated polycrystalline thin film semiconductors using sequential lateral solidification

A high energy, high repetition rate workpiece surface heating method and apparatus are disclosed which may comprise a pulsed XeF laser operating operating at or above 4000 Hz and producing a laser output light pulse beam at a center wavelength of about 351 nm; an optical system narrowing the laser output light pulse beam to less than 20 µm in a short axis of the laser output light pulse beam and expanding the laser output light pulse beam to form in a long axis of the beam workpiece covering extent of the long axis; the optical system including a field stop intermediate the laser and the workpiece; the workpiece comprising a layer to be heated; wherein the optical system focuses the laser output light pulse beam at a field stop with a magnification sufficient to maintain an intensity profile that has sufficiently steep side walls to allow the field stop to maintain a sufficiently steep beam profile at the workpiece without blocking the beam profile at too high an intensity level 2. The apparatus may also have a high average power in the laser output light pulse beam as delivered to the workpiece and a linebow correction mechanism in a short axis optical assembly. The linebow correction mechanism may comprise a plurality of weak cross cylinders. The system may comprise a catadioptric projection system. The line width due to laser diffraction and divergence may be less than geometric limitations. The system may project adjacent peaks of the nominal XeF spectrum to improve overall depth of focus through the separate center wavelengths of each respective adjacent peak having a different focal plane at the workpiece. The system may comprise a linebow is correction mechanism within a field stop optical assembly correcting linebow at the field stop plane and within a workpiece projection optical assembly correcting linebow at the workpiece plane.

Laser thin film poly-silicon annealing optical system

Herein is provided an improved method of sequential lateral solidification of crystalline semiconductor film The improvement consists of using a pulse laser to create two distinct zones of molten crystals The laser creates these zones by laterally and in stepwise fashion moving the substrate film beneath it The crystals form predetermined patterns as they cool A computer program in memory controls the movement of the substrate film

Line scan sequential lateral solidification of thin films

Systems and methods for reducing a surface roughness of a polycrystalline or single crystal thin film produced by the sequential lateral solidification process are disclosed. In one arrangement, the system includes an excimer laser (110) for generating a plurality of excimer laser pulses of a predetermined fluence, an energy density modulator (120) for controllably modulating the fluence of the excimer laser pulses such that the fluence is below that which is required to completely melt the thin film, a beam homoginizer (144) for homoginizing modulated laser pulses in a predetermined plane, a sample stage (170) for receiving homoginized laser pulses to effect melting of portions of the polycrystalline or single crystal thin film corresponding to the laser pulses, translating means for controllably translating a relative position of the sample stage (170) with respect to the laser pulses, and a computer (110) for coordinating the excimer pulse generation and fluence modulation with the relative positions of the sample stage (170) to thereby process the polycrystalline or single crystal thin film by sequential translation of the sample stage (170) relative to the laser pulses.

Surface planarization of thin silicon films during and after processing by the sequential lateral solidification method

From polycrystalline to single crystalline silicon on glass

We crystallize amorphous silicon films with a frequency doubled Nd:YVO4 laser operating at a repetition frequency of up to 50 kHz. A sequential lateral solidification process yields polycrystalline silicon with grains longer than 100 μm and a width between 0.27 and 1.7 μm depending on film thickness and laser repetition frequency. The average grain size is constant over the whole crystallized area of 25 cm2. Thin film transistors with n- type and p-type channels fabricated from the polycrystalline films have average field effect mobilities of μn = 467 cm2/Vs and μp = 217 cm2/Vs respectively. As a result of the homogeneous grain size distribution, the standard deviation of the mobility is only 5%.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1946427400584838

Karine Mourgues

Papers

Nd:YVO 4 Laser Crystallization for Thin Film Transistors with a High Mobility