# US 2014/0151750 A1 · Heterojunction bipolar transistor

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- Number: US 2014/0151750 A1
- Document ID: US20140151750A1
- Status: Published application
- Kind: A1
- Application number: 13/689,838
- Filed: 2012-11-30
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Renata A. Camillo-Castillo; Jeffrey B. Johnson
- Web page: https://patentgrep.com/patent/US20140151750A1

## CPC

- H10D 10/021: {of heterojunction BJTs [HBT]}
- H10D 10/891: {comprising lattice-mismatched active layers, e.g. SiGe strained-layer transistors}
- H10D 62/822: comprising only Group IV materials heterojunctions, e.g. Si/Ge heterojunctions
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/2905: {Silicon, silicon germanium or germanium}
- H10P 14/3411: {Silicon, silicon germanium or germanium}
- H10P 14/3444: {P-type}
- H10D 62/117: {Shapes of semiconductor bodies}
- H10D 62/137: {Collector regions of BJTs}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Structures and methods of making a heterojunction bipolar transistor (HBT) device that include: an n-type collector region disposed within a crystalline silicon layer; a p-type intrinsic base comprising a boron-doped silicon germanium crystal that is disposed on a top surface of an underlying crystalline Si layer, which is bounded by shallow trench isolators (STIs), and that forms angled facets on interfaces of the underlying crystalline Si layer with the shallow trench isolators (STIs); a Ge-rich, crystalline silicon germanium layer that is disposed on the angled facets and not on a top surface of the p-type intrinsic base; and an n-type crystalline emitter disposed on a top surface and not on the angled lateral facets of the p-type intrinsic base.

## Claims

### Claim 1

A heterojunction bipolar transistor (HBT) device, comprising:
an n-type collector region disposed within a crystalline substrate layer that is bounded by shallow trench isolators (STIs);
a p-type intrinsic base comprising a silicon germanium (SiGe) crystal that is disposed on a top surface of said crystalline substrate layer and that forms angled facets on interfaces of said crystalline substrate layer with said STIs;
a Ge-rich SiGe crystalline layer disposed on said angled facets and not on a top surface of said SiGe crystal; and
a n-type diffusion-doped crystalline emitter disposed on said top surface and not on said angled facets of said SiGe crystal.

### Claim 2 (depends on 1)

The HBT device of claim 1, said p-type intrinsic base comprising a boron-doped silicon germanium (B+-doped Si1-x1Gex1) crystal, a Ge mole fraction, x1, of said B+-doped Si1-x1Gex1 crystal ranging from 10% to 40%.

### Claim 3 (depends on 2)

The HBT device of claim 2, said p-type intrinsic base further comprising carbon (C) to form a B+-doped Si1-x1-yGex1Cy crystal, a carbon mole fraction, y, of said B+-doped Si1-x1-yGex1Cy crystal ranging from 0.01% to 0.10%.

### Claim 4 (depends on 2)

The HBT device of claim 2, a Ge mole fraction, x2, of said Ge-rich, crystalline Si1-x2Gex2 layer being greater than or equal to said Ge mole fraction, x1, of said B+-doped Si1-x1Gex1 crystal.

### Claim 5 (depends on 1)

The HBT device of claim 1, further comprising a p-type extrinsic base layer disposed on said Ge-rich, crystalline Si1-x2Gex2 layer, said p-type extrinsic base layer comprising one of: a highly B+-doped crystalline Si layer and a highly B+-doped crystalline Si1-x3Gex3 layer, a Ge mole fraction, x3, of said highly B+-doped crystalline Si1-x3Gex3 layer ranging up to 40%.

### Claim 6 (depends on 5)

The HBT device of claim 5, further comprising an insulating layer disposed on said p-type extrinsic base layer and not over said top surface of said p-type intrinsic base.

### Claim 7 (depends on 5)

The HBT device of claim 5, further comprising:
an n-type emitter lead disposed on said n-type diffusion-doped crystalline emitter; and
insulating sidewalls that insulate said n-type diffusion-doped crystalline emitter and said emitter lead, which are disposed over said top surface of said p-type intrinsic base, from said Ge-rich crystalline Si1-x2Gex2 layer, said p-type extrinsic base layer, and said insulating layer, which are disposed over said angled facets of said p-type intrinsic base.

### Claim 8 (depends on 7)

The HBT device of claim 7, said n-type emitter lead, said n-type diffusion-doped crystalline emitter stack, and said n-type collector region comprising an n-type impurity of one of phosphorus (P) and arsenic (As).

### Claim 9

A heterojunction bipolar transistor (HBT) device, comprising:
an n-type collector region disposed within a crystalline silicon (Si) layer that is bounded by shallow trench isolators (STIs);
a p-type intrinsic base comprising a boron-doped carbon-containing silicon germanium (B+-doped Si1-x1-yGex1Cy) crystal that is disposed on a top surface of said crystalline Si layer and that forms angled facets on interfaces of said crystalline Si layer with said STIs;
a Ge-rich, crystalline Si1-x2Gex2 layer disposed on said angled facets and not on a top surface of said B+-doped Si1-x1-yGex1Cy crystal; and
an n-type diffusion-doped Si crystalline emitter disposed on said top surface and not on said angled facets of said B+-doped Si1-x1-yGex1Cy crystal.

### Claim 10 (depends on 9)

The HBT device of claim 9, a Ge mole fraction, x1, of said B+-doped carbon-containing Si1-x1-yGex1Cy crystal ranging from 10% to 40%, and a carbon mole fraction, y, of said B+-doped carbon-containing Si1-x1-yGex1Cy crystal ranging from 0.01% to 0.10%.

### Claim 11 (depends on 9)

The HBT device of claim 9, said Ge-rich, crystalline Si1-x2Gex2 layer further comprising carbon (C) to form a Ge-rich, crystalline Si1-x2-yGex2Cy layer, a carbon mole fraction, y, of said Ge-rich, crystalline Si1-x2-yGex2Cy layer ranging up to 0.10%.

### Claim 12 (depends on 9)

The HBT device of claim 9, further comprising a p-type extrinsic base layer disposed on said Ge-rich, crystalline Si1-x2Gex2 layer, said p-type extrinsic base layer comprising one of: a highly B+-doped crystalline Si layer and a highly B'-doped crystalline Si1-x3Gex3 layer, a Ge mole fraction, x3, of said highly B+-doped crystalline Si1-x3Gex3 layer ranging up to 40%.

### Claim 13 (depends on 12)

The HBT device of claim 12, further comprising an insulating layer disposed on said p-type extrinsic base layer and not over said top surface of said p-type intrinsic base.

### Claim 14 (depends on 13)

The HBT device of claim 13 further comprising:
an n-type emitter lead disposed on said n-type diffusion-doped Si crystalline emitter; and
insulating sidewalls that insulate said n-type diffusion-doped Si crystalline emitter and said emitter lead, which are disposed over said top surface of said p-type intrinsic base, from said Ge-rich crystalline Si1-x2Gex2 layer, said p-type extrinsic base layer, and said insulating layer, which are disposed over said angled facets of said p-type intrinsic base.

### Claim 15

A method of making a heterojunction bipolar transistor (HBT) device, comprising:
forming an n-type collector region within a crystalline silicon (Si) layer that is bounded by shallow trench isolators (STIs);
epitaxially growing a p-type intrinsic base that comprises a boron-doped silicon germanium (B+-doped Si1-x1Gex1) crystal on a top surface of said crystalline Si layer, said B+-doped Si1-x1Gex1 crystal forming angled facets on interfaces of said crystalline Si layer with said STIs;
depositing a sacrificial layer on a top surface and not on said angled facets of said B+-doped Si1-x1Gex1 crystal;
epitaxially growing a Ge-rich crystalline Si1-x2Gex2 layer on said sacrificial layer and on said angled facets of said B+-doped Si1-x1Gex1 crystal;
epitaxially growing a p-type extrinsic base layer comprising a highly B+-doped crystalline Si layer on said Ge-rich crystalline Si1-x2Gex2 layer;
etching an emitter opening through a central portion of at least said highly B+-doped crystalline Si layer, said Ge-rich crystalline Si1-x2Gex2 layer, and said sacrificial layer to said top surface of said B+-doped Six-x1Gex1 crystal; and
forming an n-type diffusion-doped Si crystalline emitter on said top surface of said B+-doped Si1-x1Gex1 crystal in said emitter opening.

### Claim 16 (depends on 15)

The method of claim 15 further comprising, forming an insulating layer on said highly B+-doped crystalline Si layer, before etching said emitter opening.

### Claim 17 (depends on 16)

The method of claim 16, said forming an n-type diffusion-doped Si crystalline emitter on said top surface of said B+-doped Si1-x1Gex1 crystal in said emitter opening further comprising:
forming insulating sidewalls on said emitter opening;
epitaxially growing a crystalline Si cap on said top surface of said B+-doped Si1-x1Gex1 crystal between said insulating sidewalls;
forming an n-type doped non-crystalline polysilicon on said crystalline Si cap between said insulating sidewalls; and
annealing said n-type doped non-crystalline polysilicon to form an n-type doped emitter lead, from which an n-type impurity diffuses into said crystalline Si cap to form said n-type diffusion-doped crystalline emitter of said HBT.

### Claim 18 (depends on 15)

The method of claim 15, said epitaxially growing of said p-type intrinsic base further comprising adding a carbon-containing gas to an admixture of boron-containing, silicon-containing, and germanium-containing gases to epitaxially grow a B+-doped Si1-x1-yGex1Cy crystal.

### Claim 19

A method of making a heterojunction bipolar transistor (HBT) device, comprising:
forming an n-type collector region within a crystalline silicon (Si) layer that is bounded by shallow trench isolators (STIs);
epitaxially growing a p-type intrinsic base that comprises a boron-doped silicon germanium (B+-doped Si1-x1Gex1) crystal on a top surface of said crystalline Si layer, said B+-doped Si1-x1Gex1 crystal forming angled facets that are disposed on interfaces of said crystalline Si layer with said STIs;
depositing a sacrificial layer on a top surface and not on said angled facets of said B+-doped Si1-x1Gex1 crystal;
epitaxially growing a Ge-rich crystalline Si1-x2Gex2 layer on said sacrificial layer and on said angled facets of said B+-doped Si1-x1Gex1 crystal;
epitaxially growing a p-type extrinsic base layer comprising a highly B+-doped crystalline Si layer on said Ge-rich crystalline Si1-x2Gex2 layer;
forming an insulating layer on said highly B+-doped crystalline Si layer;
etching an emitter opening through a central portion of said insulating layer, said highly B+-doped crystalline Si layer, said Ge-rich crystalline Si1-x2Gex2 layer, and said sacrificial layer to said top surface of said B+-doped Si1-x1Gex1 crystal;
epitaxially growing a crystalline Si cap on said top surface of said B+-doped Si1-x1Gex1 crystal;
forming an n-type doped non-crystalline polysilicon on said crystalline Si cap; and
annealing said n-type doped non-crystalline polysilicon to form an n-type doped crystalline emitter, from which an n-type impurity diffuses into said crystalline Si cap to form an n-type diffusion-doped Si crystalline emitter of said HBT.

### Claim 20 (depends on 19)

The method of claim 19 further comprising forming insulating sidewalls on said emitter opening, before epitaxially growing said crystalline Si cap.

### Claim 21 (depends on 19)

The method of claim 19, said epitaxially growing of said B+-doped carbon-containing Si1-x1-yGex1Cy crystal comprising an admixture of: one of silane (SiH4) and disilane (Si2H6) gases, one of germane (GeH4) and digermane (Ge2H6) gases, borane (B2H6) gas, and methylsilane (CH3SiH3) gas.

### Claim 22 (depends on 21)

The method of claim 21, a Ge mole fraction, x1, of said B+-doped carbon-containing Si1-x1-yGex1Cy crystal ranging from 10% to 40%, and a carbon mole fraction, y, of said B+-doped carbon-containing Si1-x1-yGex1Cy crystal ranging from 0.01% to 0.10%.

### Claim 23 (depends on 19)

The method of claim 19, said epitaxially growing of said Ge-rich, Si1-x2Gex2 layer including an admixture of: one of silane (SiH4) and disilane (Si2H6) gases, and one of germane (GeH4) and digermane (Ge2H6) gases.

### Claim 24 (depends on 23)

The method of claim 23, a Ge mole fraction, x2, of said Ge-rich, crystalline Si1-x2Gex2 layer being greater than or equal to a Ge mole fraction, x1, of said B+-doped carbon-containing Si1-x1-yGex1Cy crystal of said p-type intrinsic base.

### Claim 25 (depends on 19)

The method of claim 19, said epitaxially growing of said p-type extrinsic base layer further comprising adding one of germane (GeH4) and digermane (Ge2H6) gases to an admixture of one of silane (SiH4) and disilane (Si2H6) gases and borane gas, to form a highly B+-doped crystalline Si1-x3Gex3 layer, a Ge mole fraction, x3, of said highly B+-doped crystalline Si1-x3Gex3 layer ranging up to 40%.