# US 10,319,855 B2 · Reducing series resistance between source and/or drain regions and a channel region

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- Number: US 10,319,855 B2
- Document ID: US10319855B2
- Status: Granted
- Kind: B2
- Application number: 15/714,491
- Filed: 2017-09-25
- Published: 2019-03-28
- Granted: 2019-06-11
- Earliest claimed: 2017-09-25
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Mona A. Ebrish; Oleg Gluschenkov
- Web page: https://patentgrep.com/patent/US10319855B2

## CPC

- H10D 30/794: {comprising conductive materials, e.g. silicided source, drain or gate electrodes}
- H10D 30/0227: {having both lightly-doped source and drain extensions and source and drain regions self-aligned to the sides of the gate, e.g. lightly-doped drain [LDD] MOSFET or double-diffused drain [DDD] MOSFET}
- H10D 30/024: {of fin field-effect transistors [FinFET]}
- H10D 30/0275: {forming single crystalline semiconductor source or drain regions resulting in recessed gates, e.g. forming raised source or drain regions}
- H10D 30/601: {having lightly-doped drain or source extensions, e.g. LDD IGFETs or DDD IGFETs (lightly doped source or drain extensions for TFTs H10D30/6715)}
- H10D 30/62: Fin field-effect transistors [FinFET]
- H10D 30/797: {being in source or drain regions, e.g. SiGe source or drain}
- H10D 62/021: {Forming source or drain recesses by etching e.g. recessing by etching and then refilling}
- H10D 62/151: {of IGFETs (of IGFETs having LDD or DDD structure H10D30/601; of thin film transistors H10D30/6713)}
- H10D 62/82: Heterojunctions
- H10P 14/3211: {Silicon, silicon germanium or germanium}
- H10D 62/832: being Group IV materials comprising two or more elements, e.g. SiGe
- H10P 30/204: {into Group IV semiconductors}
- H10P 30/208: {of electrically inactive species}
- H10P 30/221: {characterised by the angle between the ion beam and the mask}
- H10P 30/222: {characterised by the angle between the ion beam and the crystal planes or the main crystal surface (characterised by the angle between the ion beam and the mask H10P30/221)}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A method for reducing series resistance for transistors includes forming a conductive gate over and insulated from a semiconductor substrate, forming source and/or drain extension regions within the substrate and adjacent to respective source and/or drain regions, and forming source and/or drain regions within the substrate. The source and/or drain extension regions are formed from a material alloyed with a first dopant and a second dopant, the first dopant configured to increase a lattice structure of the material forming the source and/or drain extension regions.

## Claims

### Claim 1

A structure for reducing lateral series resistance for transistors, the structure comprising:
a conductive gate formed over and insulated from a semiconductor substrate;
a sub-fin region disposed in direct contact with the semiconductor substrate;
source and/or drain extension regions formed in direct contact with the sub-fin region; and
source and/or drain regions disposed in direct contact with the source and/or drain extension regions such that the source and/or drain extension regions are located directly between the sub-fin region and the source and/or drain regions;
wherein the source and/or drain extension regions are formed from a material alloyed with a first element and a second element, the first element configured to increase a lattice spacing of the material forming the source and/or drain extension regions, and the second element configured to increase electrical conductivity of the source and/or drain extension regions.

### Claim 2 (depends on 1)

The structure of claim 1, wherein the material forming the source and/or drain extension regions is silicon germanium (SiGe).

### Claim 3 (depends on 2)

The structure of claim 2, wherein the first element is tin (Sn) and the second element is gallium (Ga).

### Claim 4 (depends on 3)

The structure of claim 3, wherein the Sn enables higher solubility of the Ga in the SiGe forming the source and/or drain extension regions.

### Claim 5 (depends on 3)

The structure of claim 3, wherein the Sn has an atomic percentage (at %) between about 0.5 to about 1.5 resulting in Ga concentration of from about 2×1019 cm−3 to about 1×1020 cm−3.

### Claim 6 (depends on 5)

The structure of claim 5, wherein the Sn is added to SiGe having less than about 70% Ge to make the SiGe appear to have a higher percentage of Ge that allows for a higher concentration of Ga.

### Claim 7 (depends on 1)

The structure of claim 1, wherein a channel region is formed under the conductive gate and directly between the source and/or drain extension regions.

### Claim 8 (depends on 7)

The structure of claim 7, wherein spacers are formed adjacent the conductive gate such that the source and/or drain extension regions directly contact the spacers.

### Claim 9 (depends on 1)

The structure of claim 1, wherein the source and/or drain regions are doped with boron (B) and carbon (C).