Large grain size polysilicon films formed by nuclei-induced solid phase crystallization
AssigneeMatrix Semiconductor, Inc.
InventorShuo Gu
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Abstract
A method to enhance grain size in polysilicon films while avoiding formation of hemispherical grains (HSG) is disclosed. The method begins by depositing a first amorphous silicon film, then depositing silicon nuclei, which will act as nucleation sites, on the amorphous film. After deposition of silicon nuclei, crystallization, and specifically HSG, is prevented by lowering temperature and/or raising pressure. Next a second amorphous silicon layer is deposited over the first layer and the nuclei. Finally an anneal is performed to induce crystallization from the embedded nuclei. Thus grains are formed from the silicon bulk, rather than from the surface, HSG is avoided, and a smooth polysilicon film with enhanced grain size is produced.
Claims18
A method for crystallizing silicon, comprising:
- embedding deposited silicon nuclei within a matrix of amorphous silicon;
- and
- crystallizing from the embedded silicon nuclei.
A method for crystallizing silicon, comprising:
- depositing a first layer of amorphous silicon;
- depositing silicon nuclei on the first layer of amorphous silicon;
- depositing a second layer of amorphous silicon over the first layer and the nuclei, wherein conversion of the first layer to hemispherical grains before deposition of the second layer is substantially prevented;
- and
- annealing the first and second layers of amorphous silicon to induce crystallization.
A method for crystallizing silicon, comprising:
- depositing a first layer of amorphous silicon;
- depositing silicon nuclei on the first layer of amorphous silicon;
- changing conditions to inhibit formation of hemispherical grains;
- depositing a second layer of amorphous silicon over the first layer and nuclei;
- and
- annealing the nuclei and silicon layers.
Dependencies are inferred from the claim text.