# US 2014/0191374 A1 · Film thickness metrology

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- Number: US 2014/0191374 A1
- Document ID: US20140191374A1
- Status: Published application
- Kind: A1
- Application number: 13/738,194
- Filed: 2013-01-10
- Published: 2014-07-10
- Earliest claimed: 2013-01-10
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Carlos Strocchia-Rivera
- Web page: https://patentgrep.com/patent/US20140191374A1

## CPC

- H10P 74/203: {Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects}
- H10D 62/10: Shapes, relative sizes or dispositions of the regions of the semiconductor bodies; Shapes of the semiconductor bodies
- H10D 89/00: Aspects of integrated devices not covered by groups H10D84/00 - H10D88/00
- H10P 50/642: {Chemical etching}
- H10P 74/23: {characterised by multiple measurements, corrections, marking or sorting processes}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

Methods for determining a target thickness of a conformal film with reduced uncertainty, and an integrated circuit (IC) chip having a conformal film of the target thickness are provided. In an embodiment, a first critical dimension of a structure disposed on a wafer is measured. Said structure has at least one vertical surface. A first conformal film is deposited over the structure covering each of a horizontal and the vertical surface of the structure. A second critical dimension of the covered structure is then measured. The target thickness of the conformal film is determined based on difference between the first CD measured on the structure and the second CD measured on the covered structure.

## Claims

### Claim 1

A method comprising:
measuring a first critical dimension (CD) of a structure disposed on a wafer, the structure having at least one vertical surface and at least one horizontal surface;
depositing a first conformal film over the structure to form a coated structure, wherein the first conformal film covers each of the horizontal surface and the vertical surface of the structure;
measuring a second CD of the coated structure; and
determining a target first conformal film thickness based on a difference between the first CD and the second CD.

### Claim 2 (depends on 1)

The method of claim 1,
wherein the structure includes a trench,
wherein the first CD is a width of the trench prior to the depositing of the first conformal film, and
wherein the second CD is a width of the coated trench after the depositing of the first conformal film.

### Claim 3 (depends on 1)

The method of claim 1,
wherein the structure is a raised feature, and the raised feature is one of a fin or a ridge,
wherein the first CD is a width of the raised feature prior to the depositing of the first conformal film, and
wherein the second CD is a width of the raised feature after the depositing of the first conformal film.

### Claim 4 (depends on 1)

The method of claim 1, wherein the target first conformal film thickness is determined according to the equation,
t=|½[CD1−CD2]|
where
t=target first conformal film thickness;
CD1=the first CD; and
CD2=the second CD.

### Claim 5 (depends on 1)

The method of claim 1, wherein the determining of the target first conformal film thickness further comprises accounting for an uncertainty associated with measuring each of the first CD of the structure and the second CD of the structure.

### Claim 6 (depends on 5)

The method of claim 5, wherein the target first conformal film thickness is determined according to the equation,
t=|½[CD1−CD2±√(δ12+δ22)]|
where
t=target first conformal film thickness;
CD1=the first CD;
CD2=the second CD;
δ1=an uncertainty associated with a measurement of CD1; and
δ2=an uncertainty associated with a measurement of CD2.

### Claim 7 (depends on 1)

The method of claim 1, wherein the measuring of the first CD and the second CD further comprises using critical dimension scanning electron microscopy (CD SEM).

### Claim 8 (depends on 1)

The method of claim 1, wherein the measuring of the first CD and the second CD further comprises using atomic force microscopy (AFM).

### Claim 9 (depends on 1)

The method of claim 1, further comprising:
after the measuring of the second CD of the coated structure, depositing a second conformal film over the coated structure, wherein the second conformal film covers each of a horizontal and a vertical surface of the coated structure;
measuring a third CD of the coated structure; and
determining a target second conformal film thickness based on a difference the second CD and the third CD.

### Claim 10 (depends on 9)

The method of claim 9, wherein the determining of the target second conformal film thickness further comprises accounting for an uncertainty associated with a measurement of each of the second CD of the coated structure and the third CD of the coated structure,
wherein the target second conformal film thickness is determined according to the equation,
t2=|½[CD2−CD3±√(δ22+δ32)]|
where
t2=target second conformal film thickness;
CD2=the second CD;
CD3=the third CD;
δ2=an uncertainty associated with a measurement of CD2; and
δ3=an uncertainty associated with a measurement of CD3.

### Claim 11

A method comprising:
depositing a first conformal film over a wafer having a structure thereon, thereby forming a coated structure, the structure including at least one vertical surface and at least one horizontal surface;
measuring a first critical dimension (CD) of the structure;
performing an etch to remove a partial thickness of the first conformal film from each of the at least one vertical surface and at least one horizontal surface;
measuring a second CD of the coated structure; and
determining a target first conformal film thickness based on a difference between the first CD and the second CD.

### Claim 12 (depends on 11)

The method of claim 11,
wherein the structure includes a trench,
wherein the first CD is a width of the trench prior to the depositing of the first conformal film, and
wherein the second CD is a width of the trench after the depositing of the first conformal film.

### Claim 13 (depends on 11)

The method of claim 11,
wherein the structure is a raised feature, and the raised feature is one of a fin or a ridge,
wherein the first CD is a width of the raised feature prior to the depositing of the first conformal film, and
wherein the second CD is a width of the raised feature after the depositing of the first conformal film.

### Claim 14 (depends on 11)

The method of claim 11, wherein the target first conformal film thickness is determined according to the equation,
t=|½[CD1−CD2]|
where
t=target first conformal film thickness;
CD1=the first CD; and
CD2=the second CD.

### Claim 15 (depends on 11)

The method of claim 11,
wherein the determining the target first conformal film thickness further comprises accounting for an uncertainty associated with measuring each of the first CD of the structure and the second CD of the coated structure, and
wherein the target first conformal film thickness is determined according to the equation,
t=|½[CD1−CD2±√(δ12+δ22)]|
where
t=target first conformal film thickness;
CD1=the first CD;
CD2=the second CD;
δ1=an uncertainty associated with a measurement of CD1; and
δ2=an uncertainty associated with a measurement of CD2.

### Claim 16 (depends on 11)

The method of claim 11, wherein the measuring of the first CD and the second CD further comprises using one of critical dimension scanning electron microscopy (CD SEM) or atomic force microscopy (AFM).

### Claim 17

An integrated circuit (IC) chip comprising:
a wafer;
at least one structure having at least one vertical surface and at least one horizontal surface, the at least one structure being disposed on the wafer; and
a first conformal film over the wafer including the at least one structure, wherein the first conformal film has a first thickness, and wherein the first thickness is represented by the following equation:
t=|½[CD1−CD2]|
where
t=the first target thickness;
CD1=a first critical dimension (CD); and
CD2=a second CD.

### Claim 18 (depends on 17)

The IC chip of claim 17,
wherein the structure is a trench,
wherein the first CD is a width of the trench, and
wherein the second CD is a width of a trench opening in the first conformal film.

### Claim 19 (depends on 17)

The IC chip of claim 17,
wherein the structure is a raised feature, and the raised feature is one of a fin or a ridge,
wherein the first CD is a width of the raised feature, and
wherein the second CD is a combined width of the raised feature and the first conformal film over the raised feature.

### Claim 20 (depends on 17)

The IC chip of claim 17, wherein the first conformal film thickness accounts for an uncertainty associated with each of the first CD and the second CD, wherein the target first conformal film thickness is represented by the equation,
t=|½[CD1−CD2±√(δ12+δ22)]|
where
t=first conformal film thickness;
CD1=the first CD;
CD2=the second CD;
δ1=an uncertainty associated with a measurement of CD1; and
δ2=an uncertainty associated with a measurement of CD2.