# US 2014/0191325 A1 · Fin-Shaped Field Effect Transistor (FINFET) Structures Having Multiple Threshold Voltages (Vt) and Method of Forming

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- Number: US 2014/0191325 A1
- Document ID: US20140191325A1
- Status: Published application
- Kind: A1
- Application number: 13/735,227
- Filed: 2013-01-07
- Published: 2014-07-10
- Earliest claimed: 2013-01-07
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Murshed M. Chowdhury; Benjamin R. Cipriany; Brian J. Greene; Arvind Kumar
- Web page: https://patentgrep.com/patent/US20140191325A1

## CPC

- H10D 84/853: {comprising FinFETs}
- H10D 84/0193: {the components including FinFETs}
- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

Various embodiments include fin-shaped field effect transistor (finFET) structures that enhance work function and threshold voltage (Vt) control, along with methods of forming such structures. The finFET structures can include a p-type field effect transistor (PFET) and an n-type field effect transistor (NFET). In some embodiments, the PFET has fins separated by a first distance and the NFET has fins separated by a second distance, where the first distance and the second distance are distinct from one another. In some embodiments, the PFET or the NFET include fins that are separated from one another by non-uniform distances. In some embodiments, the PFET or the NFET include adjacent fins that are separated by distinct distances at their source and drain regions.

## Claims

### Claim 1

A fin-shaped field effect transistor structure (finFET) structure comprising:
a substrate having a first portion and a second portion separated by an isolation region;
a p-type field effect transistor region (PFET) over the first portion, the PFET including:
a plurality of PFET metal fins having a first PFET fin, a second PFET fin adjacent the first fin, and a third PFET fin adjacent the second fin, wherein the first PFET fin is separated from the second PFET by a first distance, and the second PFET fin is separated from the third PFET fin by the first distance; and
an n-type field effect transistor region (NFET) over the second portion, the NFET including:
a plurality of NFET metal fins having a first NFET fin, a second NFET fin adjacent the first fin, and a third NFET fin adjacent the second fin, wherein the first NFET fin is separated from the second NFET by a second distance, and the second NFET fin is separated from the third NFET fin by the second distance, wherein the second distance is distinct from the first distance.

### Claim 2 (depends on 1)

The structure of claim 1, further comprising:
a gate metal over the plurality of PFET fins and the plurality of NFET fins, the gate metal spanning the first distance between the plurality of PFET fins and the second distance between the plurality of NFET fins,
wherein the first distance and the second distance cause the gate metal to have a distinct pitch in the PFET than a pitch in the NFET.

### Claim 3 (depends on 2)

The structure of claim 2, wherein the distinct pitch in the PFET and the NFET causes the PFET to have a distinct work function from a work function in the NFET.

### Claim 4 (depends on 2)

The structure of claim 2, wherein the gate metal does not fill the first distance and does not fill the second distance, the gate metal leaving a first recess between the first PFET fin and the second PFET fin, and a second recess between the first NFET fin and the second NFET fin, the first recess having a distinct width from the second recess.

### Claim 5 (depends on 4)

The structure of claim 4, further comprising:
a connector metal over the gate metal, the connector metal filling the first recess and the second recess, the connector metal having a first width between the first PFET fin and the second PFET fin and a second width between the first NFET fin and the second NFET fin, wherein the first width of the connector metal is distinct from the second width of the connector metal.

### Claim 6 (depends on 4)

The structure of claim 4, further comprising a gate oxide layer between the gate metal and each of the plurality of PFET fins and the plurality of NFET fins.

### Claim 7 (depends on 1)

The structure of claim 1, wherein the first distance is greater than the second distance.

### Claim 8 (depends on 1)

The structure of claim 1, wherein the second distance is greater than the first distance.

### Claim 9 (depends on 1)

The structure of claim 1, wherein each of the plurality of PFET fins and the plurality of NFET fins have a substantially uniform thickness.

### Claim 10

A fin-shaped field effect transistor structure (finFET) structure comprising:
a substrate having a first portion and a second portion separated by an isolation region;
a p-type field effect transistor region (PFET) over the first portion, the PFET including:
a plurality of metal PFET fins having a first PFET fin, a second PFET fin adjacent the first fin, and a third PFET fin adjacent the second fin, wherein the first PFET fin is separated from the second PFET by a first distance, and the second PFET fin is separated from the third PFET fin by a second distance distinct from the first distance; and
an n-type field effect transistor region (NFET) over the second portion, the NFET including:
a plurality of metal NFET fins having a first NFET fin, a second NFET fin adjacent the first fin, and a third NFET fin adjacent the second fin, wherein the first NFET fin is separated from the second NFET by a third distance, and the second NFET fin is separated from the third NFET fin by a fourth distance distinct from the third distance,
wherein each of the plurality of PFET fins has a substantially uniform thickness, and wherein each of the plurality of NFET fins has a substantially uniform thickness.

### Claim 11 (depends on 10)

The structure of claim 10, further comprising:
a gate metal over the plurality of PFET fins, the gate metal spanning the first distance between the first PFET fin and the second PFET fin and the second distance between the second PFET fin and the third PFET fin,
wherein the first distance and the second distance cause the gate metal to have a distinct pitch between the first PFET fin and the second PFET fin and the second PFET fin and the third PFET fin.

### Claim 12 (depends on 11)

The structure of claim 11, wherein the distinct pitches in the PFET cause the PFET to have two distinct work functions.

### Claim 13 (depends on 11)

The structure of claim 11, wherein the gate metal does not fill the first distance and does not fill the second distance, the gate metal leaving a first recess between the first PFET fin and the second PFET fin, and a second recess between the second PFET fin and the third PFET fin, the first recess having a distinct width from the second recess.

### Claim 14 (depends on 13)

The structure of claim 13, further comprising:
a connector metal over the gate metal, the connector metal filling the first recess and the second recess, the connector metal having a first width between the first PFET fin and the second PFET fin and a second width between the second PFET fin and the third PFET fin, wherein the first width of the connector metal is distinct from the second width of the connector metal.

### Claim 15 (depends on 13)

The structure of claim 13, further comprising a gate oxide layer between the gate metal and each of the plurality of PFET fins and the plurality of NFET fins.

### Claim 16 (depends on 10)

The structure of claim 10, further comprising:
a gate metal over the plurality of NFET fins, the gate metal spanning the third distance between the first NFET fin and the second NFET fin and the fourth distance between the second NFET fin and the third NFET fin,
wherein the first distance and the second distance cause the gate metal to have a distinct pitch between the first NFET fin and the second NFET fin and the second NFET fin and the third NFET fin.

### Claim 17 (depends on 16)

The structure of claim 16, wherein the distinct pitches in the NFET cause the NFET to have two distinct work functions.

### Claim 18 (depends on 10)

The structure of claim 10, wherein at least one of the first distance, the second distance, the third distance or the fourth distance includes a non-uniform distance including a distinct pitch between a source region of two adjacent fins and a drain region of the two adjacent fins.

### Claim 19

A method of forming a fin-shaped field effect transistor structure (finFET) structure, the method comprising:
forming a set of non-uniformly spaced metal fins over a substrate, the non-uniformly spaced metal fins including: a first metal fin, a second metal fin separated from the first metal fin by a first distance, and a third metal fin separated from the second metal fin by a second distance distinct from the first distance;
depositing a gate metal over the set of non-uniformly spaced metal fins, the gate metal completely filling a space between the first fin and the second fin and only partially filling the space between the second fin and the third fin, leaving a recess between the second fin and the third fin; and
depositing a connector metal over the gate metal to substantially fill the recess,
wherein the non-uniformly spaced metal fins cause the finFET structure to have distinct work functions.

### Claim 20 (depends on 19)

The method of claim 19, further comprising forming a gate oxide layer over the set of non-uniformly spaced metal fins prior to forming the gate metal.