Reducing variation by using combination epitaxy growth
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsYu-Hung Cheng, Yi-Hung Lin, Tze-Liang Lee, Chii-Horng Li
Life of this patent
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Abstract
A method for forming a semiconductor structure includes forming a gate stack over a semiconductor substrate in a wafer; forming a recess in the semiconductor substrate and adjacent the gate stack; and performing a selective epitaxial growth to grow a semiconductor material in the recess to form an epitaxy region. The step of performing the selective epitaxial growth includes performing a first growth stage with a first growth-to-etching (E/G) ratio of process gases used in the first growth stage; and performing a second growth stage with a second E/G ratio of process gases used in the second growth stage different from the first E/G ratio.
Claims19
A method comprising:
- forming a first recess and a second recess in a semiconductor substrate;
- and
- performing a selective epitaxial growth to grow a semiconductor material in the first recess and the second recess, wherein the selective epitaxial growth comprises:
- performing a first growth step, wherein in the first growth step, a selective growth is performed to grow a first semiconductor material in the first recess, and simultaneously, a selective etching is performed in the second recess;
- and
- after the first growth step, performing a second growth step to simultaneously grow a second semiconductor material in the first recess and the second recess, wherein in the second growth step, a first growth rate of the semiconductor material in the first recess is lower than a second growth rate of the semiconductor material in the second recess.
A method comprising:
- forming a first gate stack and a second gate stack over a semiconductor substrate;
- forming a first recess and a second recess in the semiconductor substrate and adjacent to the first and the second gate stacks, respectively, wherein the first recess has an area greater than an area of the second recess;
- and
- conducting a first process gas to grow a first semiconductor material in the first recess and simultaneously etch a surface layer of the semiconductor substrate exposed to the second recess;
- and
- conducting a second process gas to grow a second semiconductor material in the first and the second recesses simultaneously, wherein when the second process gas is conducted, a first growth rate of the second semiconductor material in the first recess is lower than a second growth rate of the second semiconductor material in the second recess.
A method comprising:
- forming a recess in a semiconductor substrate;
- performing an etching using a first process gas to expand the recess, with the first process gas selected from the group consisting essentially of GeH4, HCl, dichloro silane (DCS), and combinations thereof, wherein a first etch-to-growth (E/G) ratio of the etching is between about 1.2 and about 1.5, with the first E/G ratio being calculated using an equation:
- E/G ratio=FRHCl/(FRDCS+100×FRGeH4)
- wherein FRHCl, FRDCS, and FRGeH4 are flow rates of HCl, DCS, and GeH4, respectively;
- and
- after the etching, epitaxially growing a semiconductor region in the recess.
Dependencies are inferred from the claim text.