# US 12,216,057 B2 · Method and apparatus for measuring a lateral depth in a microstructure

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- Number: US 12,216,057 B2
- Document ID: US12216057B2
- Status: Granted
- Kind: B2
- Application number: 17/371,609
- Filed: 2021-07-09
- Published: 2022-01-20
- Granted: 2025-02-04
- Earliest claimed: 2020-07-14
- Assignees: Imec Vzw
- Applicants: Imec Vzw
- Inventors: Thomas Nuytten; Janusz Bogdanowicz
- Web page: https://patentgrep.com/patent/US12216057B2

## CPC

- G01B 11/22: for measuring depth
- G01N 21/65: Raman scattering
- G01B 15/00: Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons (characterised by the use of optical techniques G01B9/00, G01B11/00)
- H10D 62/121: {oriented parallel to substrates}
- H10P 74/203: {Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects}
- G01B 2210/56: Measuring geometric parameters of semiconductor structures, e.g. profile, critical dimensions or trench depth
- G03F 7/70625: {Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness}
- H10D 30/501: {FETs having stacked nanowire, nanosheet or nanoribbon channels}
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)

## Abstract

A method and apparatus are provided for a spectroscopic measurement for determining a lateral recess depth in the sidewall of a microstructure. The structure is formed on a larger substrate with the sidewall in an upright position relative to the substrate, and the recess extends essentially parallel to the substrate. The recess may be an etch depth obtained by etching a first layer relative to two adjacent layers, the layers oriented parallel to the substrate, the etch process progressing inward from the sidewall. An incident energy beam falling on the structure generates a spectroscopic response captured and processed respectively by a detector and a processing unit. The response comprises one or more peaks related to the material or materials of the substrate and the structure. According to the method, a parameter is derived from said one or more peaks, that is representative of the lateral recess depth.

## Claims

### Claim 1

A method for measuring a lateral recess depth in a microstructure positioned on a substrate, the method comprising the steps of:
directing an energy beam at the microstructure, the microstructure comprising:
an elongate sidewall in an upright position relative to the substrate and at least one lateral recess formed from the sidewall inwards and extending essentially parallel to a surface of the substrate, the at least one lateral recess having the lateral recess depth, and
at least one first layer oriented essentially parallel to the surface of the substrate, the at least one first layer being sandwiched between two adjacent layers oriented essentially parallel to the surface of the substrate, wherein the at least one first layer and the two adjacent layers extend from the elongate sidewall, wherein the at least one first layer is recessed relative to the adjacent layers, and wherein the at least one lateral recess is formed in the at least one first layer;
measuring a spectroscopic response generated by an interaction between an incident beam and the microstructure;
detecting one or more peaks in the response and deriving from said one or more peaks a parameter value that is representative of the lateral recess depth, said parameter value having a previously established one-on-one relation to the lateral recess depth; and
deriving the recess depth from the parameter value, using the previously established relation.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the lateral recess depth is an etch depth, formed in an etching process wherein the first layer is etched progressively with respect to the adjacent layers, the etching process progressing from the sidewall inwards.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the first layer is formed of a first material and the adjacent layers are formed of a second material different from the first material.

### Claim 4 (depends on 3)

The method according to claim 3, wherein:
the substrate is a silicon substrate,
the microstructure is a fin-shaped microstructure having two elongate sidewalls, and wherein the first layer and the adjacent layers extend between said two sidewalls,
the first material is SiGe and the second material is Si,
the energy beam is a laser beam and the spectroscopic response is a Raman response,
the fin-shaped microstructure comprises a silicon base portion that is uniform with the substrate, and on said base portion a stack of silicon nanosheets separated from each other and from the base portion by SiGe layers recessed relative to said Si nano-sheets,
the parameter value is a ratio between an intensity peak in a Raman spectrum related to vibrations of silicon atoms in the SiGe layers, and an intensity peak related to vibrations of silicon atoms in the silicon substrate, the base portion and/or the Si nanosheets, and
the previously established relation is linear.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the energy beam is a laser beam, the light of the laser beam being polarized in the length direction of the sidewall, and wherein the spectroscopic response is a Raman spectroscopic response.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the energy beam is an electron beam, and wherein the spectroscopic response is an Energy-Dispersive X-ray Spectroscopy response.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the energy beam is an X-ray beam, and wherein the spectroscopic response is an X-Ray photoelectron Spectroscopy response.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the energy beam is an ion beam, and wherein the spectroscopic response is a Secondary lon Mass Spectrometry response.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the previously established one-to-one relation is a linear relation.

### Claim 10 (depends on 1)

The method according to claim 1, wherein the method is performed in-line and in a semiconductor processing line.