Isotropic polycrystalline silicon
AssigneeSharp Laboratories of America, Inc.
InventorsMasao Moriguchi, Apostolos T. Voutsas, Mark A. Crowder
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Abstract
A high-quality isotropic polycrystalline silicon (poly-Si) and a method for fabricating high quality isotropic poly-Si film are provided. The method includes forming a film of amorphous silicon (a-Si) and using a MISPC process to form poly-Si film in a first area of the a-Si film. The method then anneals a second area, included in the first area, using a Laser-Induced Lateral Growth (LILaC) process. In some aspects, a 2N-shot laser irradiation process is used as the LILaC process. In some aspects, a directional solidification process is used as the LILaC process. In response to using the MISPC film as a precursor film, the method forms low angle grain boundaries in poly-Si in the second area.
Claims20
A high quality isotropic polycrystalline silicon film, the film comprising:
- a metal induced solid phase crystallization (MISPC) polycrystalline region with:
- metal atoms in a concentration of less than 1 e17 atoms/square centimeter;
- and,
- approximately equiaxial crystal domains having diameters in a range of 0.1 to 1 micron (μm);
- and,
- in the MISPC region, a low angle grain boundary region having a first plurality of parallel grain boundaries and, orthogonal to the first plurality, a second plurality of parallel grain boundaries.
A high quality isotropic polycrystalline silicon film, the film comprising:
- a metal induced solid phase crystallization (MISPC) polycrystalline region with:
- metal atoms in a concentration of less than 1 e17 atoms/square centimeter;
- and,
- approximately equiaxial crystal domains having diameters in a range of 0.1 to 1 micron (μm);
- and,
- in the MISPC region, a directional solidification polycrystalline region with:
- high aspect ratio crystal domains separated by parallel grain boundaries configured in a first dimension and having widths in a range of 0.1 to 1 μm;
- and,
- crystal defects spatially confined to the first dimension.
A thin film transistor (TFT) with a channel region formed from high quality isotropic polycrystalline silicon (poly-Si), the TFT comprising:
- a transparent substrate;
- a diffusion barrier overlying the transparent substrate;
- overlying the diffusion barrier, a high quality isotropic poly-Si layer with:
- metal atoms in a concentration of less than 1 e17 atoms/square centimeter;
- approximately equiaxial crystal domains having diameters in a range of 0.1 to 1 micron (μm);
- a first plurality of parallel grain boundaries and, orthogonal to the first plurality, a second plurality of parallel grain boundaries;
- transistor source and drain regions;
- and,
- a transistor channel region interposed between the source and drain regions;
- an oxide gate insulator layer with a thickness of less than 1000 angstroms (A) overlying the poly-Si layer;
- and,
- a gate electrode overlying the oxide gate insulator layer.
A thin film transistor (TFT) with a channel region formed from high quality isotropic polycrystalline silicon (poly-Si), the TFT comprising:
- a transparent substrate;
- a diffusion barrier overlying the transparent substrate;
- overlying the diffusion barrier, a high quality isotropic poly-Si layer with:
- metal atoms in a concentration of less than 1 e17 atoms/square centimeter;
- high aspect cratio crystal domains separated by parallel grain boundaries configured in a first dimension and having widths in a range of 0.1 to 1 micron;
- crystal defects spatially confined to the first dimension;
- transistor source and drain regions;
- and,
- a transistor channel region interposed between the source and drain regions;
- an oxide gate insulator layer with a thickness in a range of 20 to 500 angstroms overlying the poly-Si layer;
- and,
- a gate electrode overlying the oxide gate insulator layer.
Dependencies are inferred from the claim text.