Semiconductor structure and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-2016013316-A1
Application number	US-201414328061-A
Country	US
Kind code	A1
Filing date	Jul 10, 2014
Priority date	Jul 10, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

Some embodiments of the present disclosure provide a semiconductor structure including a substrate and an epitaxy region partially disposed in the substrate. The epitaxy region includes a substance with a lattice constant that is larger than a lattice constant of the substrate. The concentration profile of a substance in the epitaxy region is monotonically increasing from a bottom portion of the epitaxy region to a of the epitaxy region. A first layer of the epitaxy region has a height to width ratio of about 2. The first layer is a layer positioned closest to the substrate, and the first layer has an average concentration of the substance from about 20 to about 32 percent. A second layer disposed over the first layer. The second layer has a bottom portion with a concentration of the substance from about 27 percent to about 37 percent.

First claim

What is claimed is:

1 . A semiconductor structure, comprising:
a substrate; and an epitaxy region, partially disposed in the substrate, comprising
a substance with a first lattice constant larger than a second lattice constant of the substrate; a concentration profile of the substance being monotonically increased from a portion closest to the substrate to a portion further away from the substrate; and
a multilayer structure, each layer thereof having an average concentration of the substance different from other layers, the multilayer structure comprising:
a first layer in proximity to an interface between the epitaxy region and the substrate, and the average concentration of the substance in the first layer is from about 20 to about 32 percent, the first layer comprising:
a bottom thickness; and
a lateral thickness,
wherein a thickness ratio of the bottom thickness and the lateral thickness is about 2; and

a second layer, positioned over the first layer, comprising
a bottom portion, having a concentration of the substance from about 27 percent to about 37 percent; and
a dopant.

2 . The semiconductor structure of claim 1 , wherein the substance is selected from a group four element in a periodic table.

3 . The semiconductor structure of claim 1 , wherein the bottom thickness of the first layer is from about 14 nanometers to about 17 nanometers.

4 . The semiconductor structure of claim 1 , wherein the bottom portion comprises a vertical thickness of from about 9 nanometers to about 14 nanometers.

5 . The semiconductor structure of claim 1 , wherein the dopant in the second layer comprises a doping concentration from about 1.8E20/cm 3 to about 2.6E20/cm 3 .

6 . The semiconductor structure of claim 1 , wherein the first layer comprises a dopant at a doping concentration below 1E19/cm 3 .

7 . The semiconductor structure of claim 1 , further comprising at least a gate and a spacer on the substrate and in proximity to the epitaxy region.

8 . A semiconductor structure, comprising:
a gate on top of a substrate; and an epitaxy region, disposed in at least one of a drain region and a source region in proximity to the gate, the epitaxy region comprising:
a germanium concentration profile being monotonically increased from a portion closest to the substrate to a portion further away from the substrate; and
a multilayer structure comprising:
a first layer in proximity to an interface between the epitaxy region and the substrate; and
an average germanium concentration in the first layer is from about 20 to about 32 percent, the first layer comprising:
a bottom thickness; and
a lateral thickness,
wherein a thickness ratio of the bottom thickness and the lateral thickness is about 2; and

a second layer, positioned over the first layer, comprising:
a bottom portion, having a germanium concentration from about 27 percent to about 37 percent.

9 . The semiconductor structure of claim 8 , wherein the bottom thickness of the first layer is from about 14 nanometers to about 17 nanometers.

10 . The semiconductor structure of claim 8 , wherein the bottom portion comprises a vertical thickness of from about 9 nanometers to about 14 nanometers.

11 . The semiconductor structure of claim 8 , wherein the second layer comprises a boron concentration of from about 1.8E20/cm 3 to about 2.6E20/cm 3 .

12 . The semiconductor structure of claim 8 , wherein the germanium concentration in the second layer comprises a grading profile.

13 . The semiconductor structure of claim 8 , wherein the first layer further comprises a boron doping concentration below 1E19/cm 3 .

14 . The semiconductor structure of claim 8 , wherein the germanium concentration in the first layer comprises a grading profile with a difference between a greatest concentration and a lowest concentration being 10 percent.

15 . A method for fabricating semiconductor structure, comprising:
forming a recess in a substrate; and forming an epitaxy region, comprising a multilayer structure with a substance having a first lattice constant larger than a second lattice constant of the substrate, comprising:
forming a first layer in proximity to an interface between the epitaxy region and the substrate with an average concentration of the substance from about 20 to about 32 percent by an in situ growth; and
forming a second layer over the first layer, a bottom portion of the second layer having a concentration of the substance from about 27 percent to about 37 percent by an in situ growth operation; and
forming dopants in the first layer and the second layer.

16 . The method of claim 15 , wherein the forming the recess comprises etching the substrate by a wet etching, a dry etching, or a combination thereof.

17 . The method of claim 15 , wherein the forming the epitaxy region comprises performing a cyclic deposition etch operation, a selective epitaxial growth, or a combination thereof.

18 . The method of claim 15 , wherein forming dopants in the first layer comprises performing an in situ doping or an ion-implantation operation with a dopant selected from a group consisting essentially of III-V elements.

19 . The method of claim 15 , wherein forming dopants in the second layer comprises performing an in situ doping or an ion-implantation operation using boron.

20 . The method of claim 15 , further comprising forming a cap layer with substantially the second lattice constant over the second layer.

Assignees

• Taiwan Semiconductor Mfg

Inventors

• Kuang Shin-Jiun
• Yu Tsung-Hsing
• Sheu Yi-Ming

Classifications

• H10P14/3444

  P-type · CPC title

• H10P14/3411

  Silicon, silicon germanium or germanium · CPC title

• H10P14/2925

  Surface structures · CPC title

• H10P14/271

  characterised by the preparation of substrate for selective deposition · CPC title

• H10P14/24

  using chemical vapour deposition [CVD] · CPC title