Crystalline semiconductor film manufacturing method, substrate coated with crystalline semiconductor film, and thin-film transistor

A substrate coated with a crystalline semiconductor film, said substrate comprising:

• a base material;
• a plurality of gate electrodes arranged above said base material;
• an insulating film formed over said gate electrodes;
• and
• a crystalline semiconductor film formed to cover said insulating film formed over the gate electrodes arranged above said base material,
• wherein said crystalline semiconductor film includes:
• a first area formed from crystal grains with an average size of 40 nm to 60 nm and seamlessly formed over an area where said gate electrodes are arranged;
• and
• a second area formed from crystal grains with an average size of 25 nm to 35 nm and located adjacent to the first area.

A bottom-gate thin-film transistor comprising:

• a gate electrode;
• an insulating film formed on said gate electrode;
• a crystalline semiconductor film formed on said insulating film;
• and
• a source-drain electrode formed on said crystalline semiconductor film,
• wherein said crystalline semiconductor film is formed from crystal grains with an average size of 40 nm to 60 nm, and
• each of the crystal grains are formed by:
• irradiating an amorphous semiconductor film with a continuous-wave laser beam to increase a temperature of the amorphous semiconductor film to a range of 600° C. to 800° C., the continuous-wave laser beam having a light intensity distribution which is continuously convex upward on each of major and minor axes;
• crystallizing the amorphous semiconductor film irradiated with the continuous-wave laser beam in said irradiating, at the temperature increased to the range of 600° C. to 800° C.;
• and
• increasing a crystal grain size of the crystallized amorphous semiconductor film, as a result of an increase in an in-plane temperature of the crystallized amorphous film to a range of 1100° C. to 1414° C. by latent heat released in said crystallizing of the amorphous semiconductor film irradiated with the continuous-wave laser beam,
• wherein the light intensity distribution continuously convex upward is defined on the major axis to ensure a certain width of an area included in the amorphous semiconductor film and increased in temperature to the range of 1100° C. to 1414° C. by the latent heat.

A substrate coated with a crystalline semiconductor film, said substrate comprising:

• a base material;
• a plurality of source-drain electrodes arranged above said base material;
• an insulating film formed over the source-drain electrodes;
• and
• a crystalline semiconductor film formed to cover said insulating film formed over the source-drain electrodes arranged above said base material,
• wherein said crystalline semiconductor film includes:
• a first area formed from crystal grains with an average size of 40 nm to 60 nm and seamlessly formed over an area where said source-drain electrodes are arranged;
• and
• a second area formed from crystal grains with an average size of 25 nm to 35 nm and located adjacent to the first area.

A top-gate thin-film transistor comprising:

• a source-drain electrode;
• a crystalline semiconductor film formed on said source-drain electrode;
• an insulating film formed on said crystalline semiconductor film;
• and
• a gate electrode formed on said insulating film,
• wherein said crystalline semiconductor film is formed from crystal grains with an average size of 40 nm to 60 nm, and
• each of the crystal grains are formed by:
• irradiating an amorphous semiconductor film with a continuous-wave laser beam to increase a temperature of the amorphous semiconductor film to a range of 600° C. to 800° C., the continuous-wave laser beam having a light intensity distribution which is continuously convex upward on each of major and minor axes;
• crystallizing the amorphous semiconductor film irradiated with the continuous-wave laser beam in said irradiating, at the temperature increased to the range of 600° C. to 800° C.;
• and
• increasing a crystal grain size of the crystallized amorphous semiconductor film, as a result of an increase in an in-plane temperature of the crystallized amorphous film to a range of 1100° C. to 1414° C. by latent heat released in said crystallizing of the amorphous semiconductor film irradiated with the continuous-wave laser beam,
• wherein the light intensity distribution continuously convex upward is defined on the major axis to ensure a certain width of an area included in the amorphous semiconductor film and increased in temperature to the range of 1100° C. to 1414° C. by the latent heat.

A method of manufacturing a crystalline semiconductor film, said method comprising:

• irradiating an amorphous semiconductor film with a continuous-wave laser beam to increase a temperature of the amorphous semiconductor film to a first temperature which is lower than a melting point of the amorphous semiconductor film and at which the amorphous semiconductor film is crystallized by a solid phase growth mechanism, the continuous-wave laser beam having a light intensity distribution which is continuously convex upward on each of major and minor axes;
• crystallizing the amorphous semiconductor film irradiated with the continuous-wave laser beam in said irradiating, at the first temperature;
• and
• increasing a crystal grain size of the crystallized amorphous semiconductor film, as a result of an increase in an in-plane temperature of the crystallized amorphous semiconductor film to a second temperature by latent heat released in said crystallizing of the amorphous semiconductor film irradiated with the continuous-wave laser beam, the second temperature ranging from the melting point of the amorphous semiconductor film to a crystalline melting point,
• wherein the light intensity distribution continuously convex upward has a width where a light intensity is equal to or higher than a predetermined intensity in a major axis direction, and
• the width corresponds to a width of an area included in the amorphous semiconductor film and increased in temperature to the second temperature by the latent heat.

A bottom-gate thin-film transistor comprising:

• a gate electrode;
• an insulating film formed on said gate electrode;
• a crystalline semiconductor film formed on said insulating film;
• and
• a source-drain electrode formed on said crystalline semiconductor film,
• wherein said crystalline semiconductor film is formed from crystal grains with an average size of 40 nm to 60 nm, and
• each of the crystal grains are formed by:
• irradiating an amorphous semiconductor film with a continuous-wave laser beam to increase a temperature of the amorphous semiconductor film to a first temperature which is lower than a melting point of the amorphous semiconductor film and at which the amorphous semiconductor film is crystallized by a solid phase growth mechanism, the continuous-wave laser beam having a light intensity distribution which is continuously convex upward on each of major and minor axes;
• crystallizing the amorphous semiconductor film irradiated with the continuous-wave laser beam in said irradiating, at the first temperature;
• and
• increasing a crystal grain size of the crystallized amorphous semiconductor film, as a result of an increase in an in-plane temperature of the crystallized amorphous semiconductor film to a second temperature by latent heat released in said crystallizing of the amorphous semiconductor film irradiated with the continuous-wave laser beam, the second temperature ranging from the melting point of the amorphous semiconductor film to a crystalline melting point,
• wherein the light intensity distribution continuously convex upward is defined on the major axis to ensure a certain width of an area included in the amorphous semiconductor film and increased to the second temperature by the latent heat.

A top-gate thin-film transistor comprising:

• a source-drain electrode;
• a crystalline semiconductor film formed on said source-drain electrode;
• an insulating film formed on said crystalline semiconductor film;
• and
• a gate electrode formed on said insulating film,
• wherein said crystalline semiconductor film is formed from crystal grains with an average size of 40 nm to 60 nm, and
• each of the crystal grains are formed by:
• irradiating an amorphous semiconductor film with a continuous-wave laser beam to increase a temperature of the amorphous semiconductor film to a first temperature which is lower than a melting point of the amorphous semiconductor film and at which the amorphous semiconductor film is crystallized by a solid phase growth mechanism, the continuous-wave laser beam having a light intensity distribution which is continuously convex upward on each of major and minor axes;
• crystallizing the amorphous semiconductor film irradiated with the continuous-wave laser beam in said irradiating, at the first temperature;
• and
• increasing a crystal grain size of the crystallized amorphous semiconductor film, as a result of an increase in an in-plane temperature of the crystallized amorphous semiconductor film to a second temperature by latent heat released in said crystallizing of the amorphous semiconductor film irradiated with the continuous-wave laser beam, the second temperature ranging from the melting point of the amorphous semiconductor film to a crystalline melting point,
• wherein the light intensity distribution continuously convex upward is defined on the major axis to ensure a certain width of an area included in the amorphous semiconductor film and increased to the second temperature by the latent heat.