Semiconductor device and process for producing the same

A process for producing a semiconductor device, which comprises the following steps:

• (a) a step of thermally oxidizing a semiconductor substrate, thereby forming a first silicon oxide film as a pad oxide film on the surface of the semiconductor substrate, then depositing a silicon nitride film as an anti-oxidation film on the first silicon oxide film, and then selectively etching the silicon nitride film, the first silicon oxide film and the semiconductor substrate residing in an element isolation region while masking an element region, thereby trenching a groove on the surface of the semiconductor substrate,
• (b) a step of etching the first silicon oxide film exposed to the inside wall of the groove, thereby recessing the first silicon oxide film from the inside wall of the groove towards an active region to an extent of 5 to 40 nm,
• (c) a step of thermally oxidizing the semiconductor substrate, thereby forming a second silicon oxide film on the inside wall of the groove just before fully filling the second silicon oxide film in the recess space formed up to the edge of the recessed first silicon oxide film and rounding the shoulder edge of the groove at the same time,
• (d) a step of depositing a third silicon oxide film on the surface of the semiconductor substrate, thereby embedding the third silicon oxide film in the groove,
• (e) a step of heat-treating (or annealing) the semiconductor substrate, thereby sintering the third silicon oxide film embedded in the groove,
• (f) a step of removing the third silicon oxide film on the silicon nitride film, while leaving the third silicon oxide film only in the groove, thereby forming an element isolation groove embedded with the third silicon oxide film, and
• (g) a step of removing the silicon nitride film on the surface o the active region whose circumference is confined by the element isolation groove and then forming a semiconductor element in the active region.

A process for producing a semiconductor device, which comprises the following steps:

• (a) a step of thermally oxidizing a semiconductor substrate, thereby forming a first silicon oxide film on the surface of the semiconductor substrate, then depositing a silicon nitride film on the first silicon oxide film, up to the edge of the recessed first silicon oxide film and then selectively etching the silicon nitride film and and rounding the shoulder edge of the groove at the the first silicon oxide film residing in an element isolation region while masking an element region,
• (b) a step of isotropically and shallowly etching the semiconductor substrate in the element isolation region, thereby forming an undercut on the semiconductor substrate at the edge of the element isolation region,
• (c) a step of selectively etching the semiconductor substrate in the element isolation region, thereby trenching a groove on the surface of the semiconductor substrate,
• (d) a step of thermally oxidizing the semiconductor substrate, thereby forming a second silicon oxide film on the inside wall of the groove and rounding the shoulder edge of the groove at the same time,
• (e) a step of depositing a third silicon oxide film on the surface of the semiconductor substrate, thereby embedding the third silicon oxide film in the groove,
• (f) a step of heat-treating (or annealing) the semiconductor substrate, thereby sintering the third silicon oxide film embedded in the groove,
• (g) a step of removing the third silicon oxide film on the silicon nitride film, while leaving the third silicon oxide film only in the groove, thereby forming an element isolation groove embedded with the third silicon oxide film, and
• (h) a step of removing the silicon nitride film on the surface of an active region whose circumference is confined by the element isolation groove, and then forming a semiconductor element in the active region.

A process for producing a semiconductor device, which comprises the following steps:

• (a) a step of thermally oxidizing a semiconductor substrate, thereby forming a first silicon oxide film on the surface of the semiconductor substrate, then depositing a first silicon nitride film on the first silicon oxide film and then selectively etching the first silicon nitride film, the first silicon oxide film and the semiconductor substrate residing in an clement isolation region while masking an element region, thereby trenching a groove on the surface of the semiconductor substrate,
• (b) a step of etching the first silicon oxide film exposed to the inside wall of the groove, thereby recessing the first silicon oxide film from the inside wall of the groove to an extent of 5 to 40 nm towards an active region,
• (c) a step of thermally oxidizing the semiconductor device, thereby forming a second silicon oxide film on the inside wall of the groove just before fully filling the second silicon oxide film in the recess space formed up to the recessed first silicon oxide film, and rounding the shoulder edge of the groove at the same time,
• (d) a step of depositing a second silicon nitride film on the semiconductor substrate including the inside of the groove by chemical vapor deposition,
• (e) a step of depositing a third silicon oxide film on the surface of the semiconductor substrate, thereby embedding the third silicon oxide film in the groove,
• (f) a step of heat treating (or annealing) the semiconductor substrate, thereby sintering the third silicon oxide film embedded in the groove,
• (g) a step of removing the third silicon oxide film and the second silicon nitride film on the first silicon nitride film, while leaving the third silicon oxide film and the second silicon nitride film only in the groove, thereby forming an element isolation groove embedded with the third silicon oxide film and the second silicon nitride film,
• (h) a step of removing the first silicon nitride film on the surface of the active region whose circumference is confined by the element isolation groove by etching,
• (i) a step of thermally oxidizing the third silicon oxide film in the element isolation groove, thereby increasing the thickness of the film and filling a recess formed by simultaneous removal of the second silicon nitride film at the shoulder edge of the element isolation groove during the removal of the first silicon nitride film by etching, and
• (j) a step of forming a semiconductor element in the active region.

A process for producing a semiconductor device, which comprises the following steps:

• (a) a step of thermally oxidizing a semiconductor substrate, thereby forming a first silicon oxide film on the surface of the semiconductor substrate, then depositing a first silicon nitride film on the first silicon oxide film, and then selectively etching the first silicon nitride film, the first silicon oxide film and the semiconductor substrate residing in an element isolation zone while masking an element region, thereby trenching a groove on the surface of the semiconductor substrate,
• (b) a step of etching the first silicon oxide film exposed to the inside wall of the groove, thereby recessing the first silicon oxide film from the inside wall of the groove towards an active region to an extent of 5 to 40 nm,
• (c) a step of thermally oxidizing the semiconductor substrate, thereby forming a second silicon oxide film on the inside wall of the groove just before fully filling the second silicon oxide film in the recess space formed up to the recessed first silicon oxide film, and rounding the shoulder edge of the groove at the same time,
• (d) a step of depositing a second silicon nitride film on the semiconductor substrate including the inside of the groove by chemical vapor deposition,
• (e) a step of depositing a third silicon oxide film on the surface of the semiconductor substrate, thereby embedding the third silicon oxide in the groove,
• (f) a step of removing the third silicon oxide film and the second silicon nitride film on the first silicon nitride film, while leaving the third silicon oxide film and the second silicon nitride film only in the groove, thereby forming an element isolation groove embedded with the third silicon oxide film and the second silicon nitride film,
• (g) a step of heat-treating (or annealing) the semiconductor substrate, thereby sintering the third silicon oxide film embedded in the groove, and oxidizing the surface of the first silicon nitride film and the surface of the second silicon nitride film on the shoulder edge of the element isolation groove,
• (h) a step of removing the first silicon nitride film on the surface of the active region whose circumference is confined by the element isolation groove by and the oxide film on the surface of the first silicon nitride film by etching, and
• (i) a step of forming a semiconductor element in the active region.

A process for producing a semiconductor device, which comprises the following steps:

• (a) a step of thermally oxidizing a semiconductor substrate, thereby forming a first silicon oxide film on the surface of the semiconductor substrate, then depositing a silicon nitride film on the first silicon oxide film, and then selectively etching the silicon nitride film, the first silicon oxide film and the semiconductor substrate residing in an element isolation region while masking an element region, thereby trenching a groove on the surface of the semiconductor substrate,
• (b) a step of etching the first silicon oxide film exposed to the inside wall of the groove, thereby recessing the first silicon oxide film from the inside wall of the groove towards an active region to an extent of 5 to 40 nm,
• (c) a step of depositing a second silicon oxide film on the surface of the semiconductor substrate, thereby embedding the second silicon oxide film in the groove.
• (d) a step of thermally oxidizing the semiconductor substrate, thereby sintering the second silicon oxide film embedded in the groove, forming a third silicon film on oxide film on the inside wall of the groove and rounding the shoulder edge of the groove at the same time,
• (e) a step of removing the second silicon oxide film on the silicon nitride film, while leaving the second silicon oxide film only in the groove, thereby forming an element isolation groove embedded with the second silicon oxide film, and
• (f) a step of removing the silicon nitride film on the surface of the active region whose circumference is confined by the element isolation groove, and then forming a semiconductor element in the active region.

A process for producing a semiconductor device, which comprises the following steps:

• (a) a step of thermally oxidizing a semiconductor substrate, thereby forming a first silicon oxide film on the surface of the semiconductor substrate, then depositing a silicon nitride film on the first silicon oxide film, and then selectively etching the silicon nitride film, the first silicon oxide film and the semiconductor substrate residing in an element isolation region, thereby trenching a groove on the surface of the semiconductor substrate,
• (b) a step of etching the first silicon oxide film exposed to the inside wall of the groove, thereby recessing the first silicon oxide film from the inside wall of the groove towards an active region to an extent of 5 to 40 nm,
• (c) A step of depositing a second silicon oxide film on the surface of the semiconductor substrate, thereby embedding the second silicon oxide film in the groove,
• (d) a step of removing the second silicon oxide film on the silicon nitride film, while leaving the second silicon oxide film only in the groove, thereby forming an element isolation groove embedded with the second silicon oxide film,
• (e) a step of thermally oxidizing the semiconductor substrate, thereby sintering the second silicon oxide film embedded in the groove, forming a third silicon oxide film on the inside wall of the groove and rounding the shoulder edge of the groove at the same time, and
• (f) a step of removing the silicon nitride film on the surface of the active region whose circumference is confined by the element isolation groove, and then forming a semiconductor element in the active region.

A process producing a semiconductor device, which comprises the following steps:

• (a) A step of thermally oxidizing a semiconductor substrate, thereby forming a first silicon oxide film on the surface of the semiconductor substrate, then depositing a silicon nitride film on the first silicon film, and then selectively etching the silicon nitride film, the first silicon oxide film and the semiconductor substrate residing in an element isolation region while masking an element region, thereby trenching a groove on the surface of the semiconductor substrate,
• (b) a step of etching the first silicon oxide film exposed to the inside wall of the groove, thereby recessing the first silicon oxide film from the inside wall of the groove towards an active region to an extent of 5 to 40 nm,
• (c) a step of thermally oxidizing the semiconductor substrate, thereby forming a second silicon oxide film on the inside wall of the groove just before fully filling the second silicon oxide film in the recess space formed up to the edge of the recessed first silicon oxide film, and rounding the shoulder edge of the groove at the same time,
• (d) a step of depositing a polycrystalline silicon film on the surface of the semiconductor substrate,
• (e) a step of depositing a third silicon oxide film on the surface of the semiconductor substrate, thereby embedding the third silicon oxide film in the groove,
• (f) a step of heat-treating (or annealing) the semiconductor substrate, thereby sintering the third silicon oxide film embedded in the groove and oxidizing the polycrystalline silicon film to convert at least a portion thereof to a silicon oxide film,
• (g) a step of removing the third silicon oxide film and the silicon oxide film o n the silicon nitride film, while leaving the third silicon oxide film and the silicon oxide film only in the groove, thereby forming an element isolation groove embedded with the third silicon oxide film and the silicon oxide film, and
• (h) a step of removing the silicon nitride film on the surface of the active region whose circumference is confined by the element isolation groove, and then forming a semiconductor element in the active region.

A process for producing a semiconductor device, which comprises the following steps:

• (a) a step of thermally oxidizing a semiconductor substrate, thereby forming a first silicon oxide film on the surface of the semiconductor substrate, then depositing a silicon nitride film on the first silicon oxide film, and then selectively etching the silicon nitride film, the first silicon oxide film and the semiconductor substrate residing in an clement isolation region while masking an element region, thereby trenching a groove on the surface of the semiconductor substrate,
• (b) a step of etching the first silicon oxide film exposed to the inside wall of the groove, thereby recessing the first silicon oxide film from the inside wall of the groove towards an active region to an extent of 5 to 40 nm,
• (c) a step of thermally oxidizing the semiconductor substrate, thereby forming a second silicon oxide film on the inside wall of the groove just before fully filling the second silicon oxide film in the recess space formed up to the edge of recessed first silicon oxide film and rounding the shoulder edge of the groove at the same time,
• (d) a step of depositing a polycrystalline silicon film on the surface of the semiconductor substrate
• (e) a step of depositing a third silicon oxide film on the surface of the semiconductor substrate, thereby embedding the third silicon oxide film in the groove,
• (f) a step of removing the third silicon oxide film and the polycrystalline silicon film on the silicon nitride film, while leaving the third silicon oxide film and the polycrystalline silicon film in the groove, thereby forming an element isolation groove embedded with the third silicon oxide film and the polycrystalline silicon film,
• (g) a step of heat-treating (or annealing) the semiconductor substrate, thereby sintering the third silicon oxide film embedded in the groove and oxidizing the polycrystalline silicon film to convert at least a portion thereof to a silicon oxide film, and
• (h) a step of removing the silicon nitride film on the surface of the active region whose circumference is confined by the element isolation groove, and then forming a semiconductor element in the active region.

A process for producing a semiconductor device, same time, which comprises the following steps:

• (a) a step of oxidizing a semiconductor substrate, thereby forming a first silicon oxide film on the surface of the semiconductor substrate, then depositing a silicon nitride film on the first silicon oxide film, and then selectively etching the silicon nitride film, the first silicon oxide film and the semiconductor substrate residing in an element isolation region while masking an element region, thereby trenching a groove on the surface of the semiconductor substrate,
• (b) a step of etching the first silicon oxide film exposed to the inside wall of the groove, thereby recessing the first silicon oxide film from the inside wall of the groove towards an active region in an extent of 5 to 40 nm,
• (c) a step of heat-nitriding the semiconductor substrate, thereby forming a second silicon nitride on the inside wall of the groove,
• (d) a step of depositing a second silicon oxide film on the surface of the semiconductor substrate, thereby embedding the second silicon oxide film in the groove,
• (e) a step of heat-treating (or annealing) the semiconductor substrate, thereby sintering the second silicon oxide film embedded in the groove,
• (f) a step of removing the second silicon oxide film on the first silicon nitride film, while leaving the second silicon oxide film only in the groove, thereby forming an element isolation groove embedded with the second silicon oxide film, and
• (g) a step of removing the first silicon nitride film on the surface of the active region whose circumference is confined by the element isolation groove, and then forming a semiconductor element in the active region.

A process for producing a semiconductor device, which comprises the following steps:

• (a) a step of thermally oxidizing a semiconductor substrate, thereby forming a first silicon oxide film on the surface of the semiconductor substrate, then depositing a silicon nitride film on the first silicon oxide film and then selectively etching the silicon nitride film, the first silicon oxide film and the semiconductor substrate residing in an element isolation region while masking an element region, thereby trenching a groove on the surface of the semiconductor substrate,
• (b) a step of etching the first silicon oxide exposed to the inside wall of the groove, thereby recessing the first silicon oxide film from the inside wall of the groove towards an active region in an extent of 5 to 40 nm,
• (c) a step of thermally oxidizing the semiconductor substrate, thereby forming a second silicon oxide film on the inside wall of the groove, and then nitriding the second silicon oxide film, thereby converting at least a portion thereof to a silicon nitride film,
• (d) a step of depositing a third silicon oxide film on the surface of the semiconductor substrate, thereby embedding the third silicon oxide film in the groove,
• (f) a step of removing the third silicon oxide film on the first silicon nitride film, while leaving the third silicon oxide film only in the groove, thereby forming an element isolation groove embedded with the third silicon oxide film, and
• (g) a step of removing the first silicon nitride film on the surface of the active region whose circumference is confined by the element isolation groove, and then forming a semiconductor element in the active region.

A process producing a semiconductor device, which comprises the following steps:

• (a) a step of thermally oxidizing a semiconductor substrate, thereby forming a first silicon oxide film on the surface of the semiconductor substrate, then depositing a silicon nitride film on the first silicon oxide film, and then selectively etching the silicon nitride film, the first silicon oxide film and the semiconductor substrate residing in an element isolation region while masking an element region, thereby trenching a groove on the surface of the semiconductor substrate,
• (b) a step of etching the first silicon oxide film exposed to the inside wall of the groove, thereby recessing the first silicon oxide film from the inside wall of the groove towards an active region to an extent of 5 to 40 nm,
• (c) a step of depositing a polycrystalline silicon film on the semiconductor substrate, and then nitriding the polycrystalline silicon film, thereby converting at least a portion thereof to a silicon nitride film,
• (d) a step of depositing a second silicon oxide film on the surface of the semiconductor substrate, thereby embedding the second silicon oxide film in the groove,
• (e) a step of heat-treating (or annealing) the semiconductor substrate, thereby sintering the second silicon oxide film embedded in the groove,
• (f) a step of removing the second silicon oxide film on the first silicon nitride film, while leaving the second silicon oxide film only in the groove, thereby forming an element isolation groove embedded with the second silicon oxide film, and
• (g) a step of removing the first silicon nitride film on the surface of the active region whose circumference is confined by the element isolation groove, and then forming a semiconductor element in the active region.