Semiconductor processing method for providing large grain polysilicon films

A semiconductor processing method of providing a polysilicon thin film transistor layer atop a semiconductor wafer comprising the following sequential steps:

• depositing a first layer of arsenic atop a semiconductor wafer to a thickness of less than or equal to about 5 Angstroms;
• depositing a second layer of silicon over the arsenic layer to a thickness of from about 300 Angstroms to about 400 Angstroms, the second layer having an outer surface;
• first annealing the wafer at a temperature of at least about 550.degree. C. for a time period sufficient to impart crystallization in the second layer and providing a predominately polysilicon second layer, the first annealing step imparting diffusion of arsenic within the second layer to promote size growth of individual polysilicon grains;
• and
• outgassing arsenic from the wafer by second annealing the wafer at a temperature of at least about 900.degree. C. for a time period sufficient to outgas arsenic from the polysilicon layer.

A semiconductor processing method of providing a polysilicon layer atop a semiconductor wafer comprising the following sequential steps:

• depositing a first layer of arsenic atop a semiconductor wafer;
• depositing a second layer of silicon over the arsenic layer, the second layer having an outer surface;
• providing a capping layer atop the second layer outer surface to prevent arsenic out-diffusion from the second layer during a first annealing step;
• first annealing the wafer at a temperature of at least about 550.degree. C. for a time period sufficient to impart growth of polycrystalline silicon grains in the second layer and providing a predominately polysilicon second layer, the first annealing step imparting diffusion of arsenic within the second layer to promote size growth of individual polysilicon grains;
• removing the capping layer;
• and
• with the capping layer being removed, outgassing arsenic from the polysilicon layer.

A semiconductor processing method of providing a polysilicon layer atop a semiconductor wafer comprising the following sequential steps:

• depositing a first layer of arsenic atop a semiconductor wafer to a thickness of less than or equal to about 5 Angstroms;
• depositing a second layer of silicon over the arsenic layer to a thickness of from about 300 Angstroms to about 400 Angstroms, the second layer having an outer surface;
• providing a capping layer atop the second layer outer surface to prevent arsenic out-diffusion from the second layer during a first annealing step;
• first annealing the wafer at a temperature of at least about 550.degree. C. for a time period sufficient to impart crystallization in the second layer and providing a predominately polysilicon second layer, the first annealing step imparting diffusion of arsenic within the second layer to promote size growth of individual polysilicon grains;
• and
• removing the capping layer;
• outgassing arsenic from the wafer by second annealing the wafer at a temperature of at least about 900.degree. C. for a time period sufficient to outgas arsenic from the polysilicon layer.