# US 10,121,687 B2 · Monitoring method and apparatus for control of excimer laser annealing

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- Number: US 10,121,687 B2
- Document ID: US10121687B2
- Status: Granted
- Kind: B2
- Application number: 15/093,424
- Filed: 2016-04-07
- Published: 2016-08-11
- Granted: 2018-11-06
- Earliest claimed: 2014-03-03
- Assignees: Coherent LaserSystems GmbH & Co. KG
- Applicants: Coherent Lasersystems GmbH & Co. KG
- Inventors: Paul Van Der Wilt
- Web page: https://patentgrep.com/patent/US10121687B2

## CPC

- H10P 72/0604: {Process monitoring, e.g. flow or thickness monitoring}
- C30B 1/02: by thermal treatment, e.g. strain annealing (C30B1/12 takes precedence)
- C30B 29/06: Silicon
- G01N 21/21: Polarisation-affecting properties (G01N21/19 takes precedence)
- G01N 21/4788: {Diffraction (for sizing particles G01N15/0205)}
- G01N 21/8422: {Investigating thin films, e.g. matrix isolation method}
- G01N 21/8851: {Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges (G01N21/8806 and G01N21/93 - G01N21/95692 take precedence; optical measurement of dimensions G01B11/00; optical scanning G02B26/10; image transformation G06T3/00; computerised image enhancement G06T5/00; image processing per se for flaw detection G06T7/0002)}
- G01N 21/9501: {Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)}
- G02B 21/002: {Scanning microscopes (scanning near field optical microscopes G01Q60/18)}
- G02B 21/0092: {Polarisation microscopes}
- H10P 34/42: with electromagnetic radiation, e.g. laser annealing (laser cutting H10P54/20)
- H10P 74/203: {Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects}
- G01N 2021/8461: {Investigating impurities in semiconductor, e.g. Silicon}
- G01N 2021/8477: {Investigating crystals, e.g. liquid crystals}
- G01N 2201/06113: Coherent sources; lasers
- G01N 2201/068: Optics, miscellaneous
- G01N 2201/0683: Brewster plate; polarisation controlling elements
- G01N 2201/0697: Pulsed lasers
- G01N 2201/10: Scanning
- G01N 2201/105: Purely optical scan
- H10P 14/3411: {Silicon, silicon germanium or germanium}
- H10P 14/3816: {Pulsed laser beam}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- 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)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A method is disclosed evaluating a silicon layer crystallized by irradiation with pulses form an excimer-laser. The crystallization produces periodic features on the crystallized layer dependent on the number of and energy density ED in the pulses to which the layer has been exposed. An area of the layer is illuminated with light. A microscope image of the illuminated area is made from light diffracted from the illuminated are by the periodic features. The microscope image includes corresponding periodic features. The ED is determined from a measure of the contrast of the periodic features in the microscope image.

## Claims

### Claim 1

An apparatus for evaluating a semiconductor layer, said apparatus comprising:
a light source for generating a beam of light directed normal to a surface of the semiconductor layer to illuminate an area of the semiconductor layer crystallized by exposure to a plurality of laser-radiation pulses having an energy density on the layer, the crystallization producing a first group of periodic surface features on the semiconductor layer in a first direction, and a second group of periodic surface features in a second direction perpendicular to the first direction, wherein characteristics of the first and second groups of periodic surface features depend on the energy density of the laser-radiation pulses to which the semiconductor layer has been exposed;
a two-dimensional array detector arranged to capture light diffracted from the illuminated area by both the first and second groups of periodic surface features, and generating output signals corresponding to variations in brightness, with the variations in brightness of the light corresponding to characteristics of the first and second groups of periodic surface features in the illuminated area of the semiconductor layer; and
a processor that calculates the contrast in brightness based on the output signals that correspond to the variations in brightness along at least one of the first and second directions in order to evaluate the energy density of the laser-radiation pulses to which the semiconductor layer has been exposed.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the two-dimensional array detector generates an image and wherein the image is formed from rows and columns of pixels and the contrast is determined by measuring an amplitude of one of all rows and all columns of pixels in the image and taking a standard deviation from an average amplitude as a measure of the contrast of the periodic surface features.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein the two-dimensional array detector generates an image and wherein the image is formed from rows and columns of pixels and the contrast is determined by measuring an amplitude of one of all rows and all columns of pixels in the image and taking a difference between highest and lowest measured amplitude as a measure of the contrast of the periodic surface features.

### Claim 4 (depends on 1)

The apparatus of claim 1 further including a means for blocking at least a portion of zero order light from reaching the two dimensional array detector.

### Claim 5 (depends on 4)

The apparatus of claim 4, wherein the means for blocking the portion of zero order light is defined by a combination of a polarizer and an analyzer set at 90-degree relative rotation.

### Claim 6 (depends on 4)

The apparatus of claim 4, wherein the means for blocking the portion of zero order light is defined by a stop positioned along the central axis of the captured light.

### Claim 7 (depends on 1)

The apparatus of claim 1 further including a blue filter located in front of the two-dimensional array detector.

### Claim 8 (depends on 1)

The apparatus of claim 1 further including a green filter located in front of the two-dimensional array detector.