Semiconductor transistor with precise geometries and related manufacture method thereof

A semiconductor transistor comprising:

• a semiconductor substrate with an original surface;
• an active region formed based on the semiconductor substrate, the active region having a fin structure;
• a shallow trench isolation region surrounding the active region;
• a gate structure of the semiconductor transistor crossing over the fin structure and covering a first portion of the shallow trench isolation region;
• a first conductive region and a second conductive region of the semiconductor transistor located within the active region;
• a canal along a longitudinal direction of the gate structure;
• and
• an inner spacer filled in the contacted to a sidewall of the gate structure, wherein a width of the inner spacer limited by the canal;
• wherein the fin structure comprises a fin body and a fin base, the fin body is covered by the gate structure, and the inner spacer at least covers sidewalls of the fin body.

A semiconductor transistor comprising:

• a semiconductor substrate with an original surface;
• an active region formed based on the semiconductor substrate, the active region having a fin structure;
• a shallow trench isolation region surrounding the active region;
• a gate structure of the semiconductor transistor crossing over the fin structure and covering a first portion of the shallow trench isolation region;
• a first conductive region and a second conductive region of the semiconductor transistor located within the active region;
• and
• an inner spacer contacted to a sidewall of the gate structure;
• wherein the fin structure comprises a fin body and a fin base, the fin body is covered by the gate structure;
• and the inner spacer at least covers sidewalls of the fin body;
• wherein the fin structure has a perpendicular profile along a direction substantially perpendicular to the original surface, and the perpendicular profile of the fin structure provides a first step-like transition or non-gradual transition.

A manufacture method for a semiconductor transistor, comprising:

• based on a semiconductor substrate, forming a fin structure which comprises a fin body and a fin base;
• forming a gate structure over the fin structure;
• forming a gate spacer over the fin structure;
• and
• controlling a width of the fin body in the gate structure, such that the width of the fin body in the gate structure and outside the gate spacer is narrower than that of the fin body under the gate spacer, wherein the fin structure has a lateral profile along a direction substantially parallel to the original surface, and the lateral profile of the fin structure comprises a rounded corner under the gate spacer.