# US 10,499,876 B2 · Test key design to enable X-ray scatterometry measurement

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- Number: US 10,499,876 B2
- Document ID: US10499876B2
- Status: Granted
- Kind: B2
- Application number: 15/725,857
- Filed: 2017-10-05
- Published: 2019-01-31
- Granted: 2019-12-10
- Earliest claimed: 2017-07-31
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Shyh-Shin Ferng; Chung-Li Huang; Yi-Hung Lin; Chungwei Wang
- Web page: https://patentgrep.com/patent/US10499876B2

## CPC

- A61B 6/584: {determining position of components of the apparatus or device using images of the phantom}
- A61B 6/08: Auxiliary means for directing the radiation beam to a particular spot, e.g. using light beams
- A61B 6/483: {involving scattered radiation}
- G01N 23/201: by measuring small-angle scattering
- G01T 1/243: {Modular detectors, e.g. arrays formed from self contained units (constructional or manufacturing details H10W90/00)}
- H10D 84/00: Integrated devices formed in or on semiconductor substrates that comprise only semiconducting layers, e.g. on Si wafers or on GaAs-on-Si wafers
- H10P 74/27: {Structural arrangements therefor}
- H10W 46/00: Marks applied to devices, e.g. for alignment or identification
- A61B 6/44: {Constructional features of apparatus for radiation diagnosis}
- G06T 2207/10116: X-ray image
- H10P 74/203: {Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects}
- H10P 95/00: Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass
- H10W 46/301: {for alignment}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- 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)
- G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

A method includes forming a test key. The formation of the test key includes forming a first plurality of semiconductor strips, and cutting the first plurality of semiconductor strips into an array of a second plurality semiconductor strips, with each row of the array being formed from one strip in the first plurality of semiconductor strips, forming isolation regions in recesses between the second plurality of semiconductor strips, and recessing the isolation regions. The top portions of the second plurality of semiconductor strips protrude higher than the isolation regions form semiconductor fins, which form a fin array. An X-ray beam is projected on the test key. A diffraction pattern is obtained from scattered X-ray beam scattered from the test key.

## Claims

### Claim 1

A method comprising:
forming a test key comprising:
forming a first plurality of semiconductor strips;
cutting the first plurality of semiconductor strips into an array of a second plurality semiconductor strips, wherein each row of the array is formed from one strip in the first plurality of semiconductor strips;
forming isolation regions in recesses between the second plurality of semiconductor strips; and
recessing the isolation regions, wherein top portions of the second plurality of semiconductor strips protrude higher than the isolation regions to form semiconductor fins, and the semiconductor fins form a fin array;
projecting an X-ray beam on the test key; and
obtaining a diffraction pattern from scattered X-ray beam scattered from the test key.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first and the second plurality of semiconductor strips are formed using a manufacturing technology, and spacings of the second plurality semiconductor strips in a same row is a minimum spacing of the manufacturing technology.

### Claim 3 (depends on 1)

The method of claim 1, wherein the first plurality of semiconductor strips has a uniform pitch.

### Claim 4 (depends on 1)

The method of claim 1, wherein the array has a first uniform pitch between rows of the fin array, and a second uniform pitch between columns of the fin array.

### Claim 5 (depends on 1)

The method of claim 1 further comprising determining a parameter from the diffraction pattern, with the parameter selected from a pitch of the semiconductor fins, a width of the semiconductor fins, and a height of the semiconductor fins.

### Claim 6 (depends on 1)

The method of claim 1, wherein the forming the test key further comprises:
forming a plurality of gate structures covering first portions of the semiconductor fins; and
etching second portions of the semiconductor fins extending beyond the plurality of gate structures to form recesses.

### Claim 7 (depends on 1)

The method of claim 1, wherein the forming the test key further comprises:
forming an inter-layer dielectric over the semiconductor fins;
forming an array of recesses in the inter-layer dielectric to expose portions of the semiconductor fins; and
forming a high-k dielectric layer extending into the array of recesses.

### Claim 8 (depends on 7)

The method of claim 7, wherein the forming the test key further comprises forming a metal layer over the high-k dielectric layer.

### Claim 9 (depends on 1)

The method of claim 1, wherein the test key is a composite test key comprising:
a plurality of sub-test keys, with each of the sub-test keys comprising a plurality of semiconductor fins forming a sub-array; and
random patterns of semiconductor fins filling spaces between the sub-test keys.

### Claim 10 (depends on 1)

The method of claim 1, wherein the test key has a non-rectangular contour.

### Claim 11

A method comprising:
forming an array of semiconductor fins, wherein the semiconductor fins have a same length, and the array has a plurality of rows and a plurality of columns;
forming additional features over the semiconductor fins, wherein the additional features comprise at least a plurality of columns, with each column over a column of the semiconductor fins;
obtaining an X-ray diffraction pattern from the array of semiconductor fins and the additional features; and
determining dimensions of the additional features from the X-ray diffraction pattern.

### Claim 12 (depends on 11)

The method of claim 11, wherein the forming the additional features comprises forming gate structures, each extending throughout an entire column of the semiconductor fins.

### Claim 13 (depends on 12)

The method of claim 12, wherein the forming the additional features further comprises:
etching portions of the semiconductor fins not covered by the gate structures to form recesses extending into isolation regions, wherein the determining the dimensions comprises determining depths of the recesses.

### Claim 14 (depends on 11)

The method of claim 11, wherein the forming the additional features comprises:
forming an inter-layer dielectric over the semiconductor fins;
etching the inter-layer dielectric to form an additional array of recesses extending into the inter-layer dielectric;
forming a high-k dielectric layer extending into the additional array of recesses; and
forming a metal layer over the high-k dielectric layer, wherein the determining dimensions of the additional features comprises determining thicknesses of the high-k dielectric layer and the metal layer.

### Claim 15 (depends on 11)

The method of claim 11, wherein the obtaining the X-ray diffraction pattern comprises projecting an X-ray beam onto the array and the additional features, and receiving the X-ray diffraction pattern from scattered X-ray beam scattered from the array and the additional features.

### Claim 16 (depends on 11)

The method of claim 11, further comprising forming a plurality of semiconductor fins around the array, wherein the plurality of semiconductor fins is allocated in a random pattern.

### Claim 17 (depends on 11)

The method of claim 11, wherein the array of semiconductor fins has a size greater than about 50 μm×50 μm.

### Claim 18

A method comprising:
forming a test key comprising:
forming an array of semiconductor fins, wherein the semiconductor fins have a same length, and the array has a plurality of rows and a plurality of columns;
forming a plurality of gate structures overlying the semiconductor fins, wherein the plurality of gate structures is distributed substantially uniformly throughout the array, and the plurality of gate structures has a lengthwise direction perpendicular to a lengthwise direction of the semiconductor fins; and
etching portions of the semiconductor fins not covered by the plurality of gate structures to form recesses extending into isolation regions;
obtaining an X-ray diffraction pattern from the test key; and
determining dimensions of the semiconductor fins and the plurality of gate structures from the X-ray diffraction pattern.

### Claim 19 (depends on 18)

The method of claim 18, wherein each of the plurality of gate structures extends from a first end of the array to an opposite second end of the array.

### Claim 20 (depends on 18)

The method of claim 18, wherein the determining the dimensions comprises determining depths of the recesses and at least one of pitches, widths, and heights of the semiconductor fins.