# US 2023/0054419 A1 · Wafer temperature measurement in an ion implantation system

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- Number: US 2023/0054419 A1
- Document ID: US20230054419A1
- Status: Published application
- Kind: A1
- Application number: 17/796,609
- Filed: 2021-01-29
- Published: 2023-02-23
- Earliest claimed: 2020-01-30
- Assignees: Advanced Ion Beam Technology, Inc.
- Applicants: Advanced Ion Beam Technology, Inc.
- Inventors: Chien-Li CHEN; Steven R. WALTHER
- Web page: https://patentgrep.com/patent/US20230054419A1

## CPC

- H10P 72/0602: {Temperature monitoring}
- C23C 14/48: Ion implantation
- C23C 14/541: {Heating or cooling of the substrates}
- G01B 7/08: {using capacitive means}
- G01B 11/08: for measuring diameters
- G01K 3/005: {Circuits arrangements for indicating a predetermined temperature (fire detection G08B17/00)}
- G01S 7/4814: {of transmitters alone}
- G01S 17/08: for measuring distance only (indirect measurement G01S17/46; active triangulation systems G01S17/48)
- H01J 37/20: Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support
- H01J 37/3171: {for ion implantation}
- H10P 30/20: into semiconductor materials, e.g. for doping
- H10P 72/0434: {mainly by convection}
- H10P 72/0436: {mainly by radiation}
- H10P 72/0471: {comprising at least one ion or electron beam chamber}
- H10P 74/203: {Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects}
- H10P 74/238: {comprising acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection or in-situ thickness measurement}
- H10P 95/90: Thermal treatments, e.g. annealing or sintering
- H01J 2237/2001: Maintaining constant desired temperature
- H01J 2237/2482: Optical means
- H10P 74/20: characterised by the properties tested or measured, e.g. structural or electrical properties
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

The present disclosure relates generally to ion implantation, and more particularly, to systems and processes for measuring the temperature of a wafer within an ion implantation system. An exemplary ion implantation system may include a robotic arm, one or more load lock chambers, a pre-implantation station, an ion implanter, a post-implantation station, and a controller. The pre-implantation station is configured to heat or cool a wafer prior to the wafer being implanted with ions by the ion implanter. The post-implantation station is configured to heat or cool a wafer after the wafer is implanted with ions by the ion implanter. The pre-implantation station and/or post-implantation station are further configured to measure a current temperature of a wafer. The controller is configured to control the various components and processes described above, and to determine a current temperature of a wafer based on information received from the pre-implantation station and/or post-implantation station.

## Claims

### Claim 1

A method for controlling wafer temperature in an ion implantation system having an ion implanter and a processing station, the method comprising:
implanting a wafer with ions from an ion beam while maintaining the wafer at a first predetermined temperature within a processing chamber of the ion implanter;
heating or cooling the wafer at the processing station;
after heating or cooling the wafer, at the processing station:
measuring a first distance from a first position of a laser source to a first point on an edge of the wafer by directing a first laser beam from the laser source at the first position to the first point;
measuring a second distance from a second position of the laser source to a second point on the edge of the wafer by directing a second laser beam from the laser source at the second position to the second point;
measuring a third distance from a third position of the laser source to a third point on the edge of the wafer by directing a third laser beam from the laser source at the third position to the third point;
determining a current diameter of the wafer based at least on the measured first distance, second distance, and third distance; and
determining a current temperature of the wafer based on the determined current diameter of the wafer; and
in accordance with the determined current temperature of the wafer satisfying a predetermined condition:
forgoing continuing to heat or cool the wafer at the processing station; and
removing the wafer from the processing station.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
in accordance with the determined current temperature of the wafer not satisfying the predetermined condition, continuing to heat or cool the wafer.

### Claim 3 (depends on 1)

The method of claim 1, wherein a laser unit of the ion implantation system includes the laser source and a laser sensor, and
wherein measuring the first distance from the first position of the laser source to the first point on the edge of the wafer comprises:
determining a first amount of time for the first laser beam to return to the laser sensor after reflecting off of the first point on the edge of the wafer; and
determining the first distance based on the first amount of time.

### Claim 4 (depends on 1)

The method of claim 1, wherein the determination of the current diameter of the wafer is further based on the first position, second position, and third position of the laser source.

### Claim 5 (depends on 1)

The method of claim 1, wherein the laser source is disposed outside of a chamber of the processing station.

### Claim 6 (depends on 1)

The method of claim 1, wherein a laser unit of the ion implantation system includes the laser source and a laser sensor, and
wherein the laser unit moves between the first position, second position, and third position along a track.

### Claim 7 (depends on 6)

The method of claim 6, wherein a path taken by the laser unit when moving along the track is a straight line that is parallel to an x-axis,
wherein each of the first position, second position, and third position is defined as a coordinate on the x-axis,
wherein a path taken by each of the first laser beam, second laser beam, and third laser beam to the first point, second point, and third point, respectively, is perpendicular to the x-axis and parallel to a y-axis,
wherein each of the measured first distance, second distance, and third distance is defined as a coordinate on the y-axis, and
wherein determining the current diameter of the wafer based at least on the measured first distance, second distance, and third distance comprises:
determining an x-axis coordinate and a y-axis coordinate defining a center point of the wafer based on the x-axis coordinates defining the first position, second position, and third position and the y-axis coordinates defining the measured first distance, second distance, and third distance; and
determining the current diameter of the wafer based on the x-axis coordinate and the y-axis coordinate corresponding to the center point of the wafer.

### Claim 8 (depends on 1)

The method of claim 1, wherein the first distance, second distance, and third distance are measured while heating or cooling the wafer.

### Claim 9 (depends on 1)

The method of claim 1, wherein the determination of the current temperature is further based on a predetermined wafer diameter corresponding to a second predetermined temperature and a linear thermal expansion coefficient of a material of the wafer.

### Claim 10 (depends on 1)

The method of claim 1, further comprising:
after positioning the wafer at the processing station and prior to heating or cooling the wafer at the processing station, at the processing station:
measuring a first reference distance from the first position of the laser source to a first reference point on the edge of the wafer by directing a first reference laser beam from the laser source at the first position to the first reference point;
measuring a second reference distance from the second position of the laser source to a second reference point on the edge of the wafer by directing a second reference laser beam from the laser source at the second position to the second reference point;
measuring a third reference distance from the third position of the laser source to a third reference point on the edge of the wafer by directing a third reference laser beam from the laser source at the third position to the third point; and
determining a reference diameter of the wafer based at least on the measured first reference distance, second reference distance, and third reference distance; and
wherein the determination of the current temperature is further based on the first predetermined temperature, the reference diameter of the wafer, and a linear thermal expansion coefficient of a material of the wafer.

### Claim 11 (depends on 1)

The method of claim 1, wherein the processing station is a post-implantation station, and wherein the predetermined condition includes a requirement that the determined current temperature of the wafer be greater than or equal to a third predetermined temperature.

### Claim 12 (depends on 1)

The method of claim 1, wherein the processing station is a pre-implantation station, and wherein the predetermined condition includes a requirement that the determined current temperature be less than or equal to the first predetermined temperature.

### Claim 13

A non-transitory computer-readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by one or more processors of a controller of an ion implantation system, cause the controller to:
control an ion implanter of the ion implantation system to implant ions into a wafer while maintaining the wafer at a first predetermined temperature within a processing chamber of the ion implanter;
control a processing station of the ion implantation system to heat or cool the wafer at the processing station;
after heating or cooling the wafer:
control a laser source of the processing station to direct a first laser beam from the laser source at a first position to a first point on the edge of the wafer;
determine a first distance from the first position of the laser source to the first point on the edge of the wafer based on detecting a reflection of the first laser beam using a laser sensor of the post-implantation station;
control the laser source to direct a second laser beam from the laser source at a second position to a second point on the edge of the wafer;
determine a second distance from the second position of the laser source to the second point on the edge of the wafer based on detecting a reflection of the second laser beam using the laser sensor;
control the laser source to direct a third laser beam from the laser source at a third position to a third point on the edge of the wafer;
determine a third distance from the third position of the laser source to the third point on the edge of the wafer based on detecting a reflection of the third laser beam using the laser sensor;
determine a current diameter of the wafer based at least on the first distance, second distance, and third distance; and
determine a current temperature of the wafer based on the determined current diameter of the wafer; and
in accordance with the determined current temperature of the wafer satisfying a predetermined condition:
control the processing station to forgo continuing to heat or cool the wafer at the processing station; and
control a robotic arm of the ion implantation system to remove the wafer from the processing station.

### Claim 14

An ion implantation system, comprising:
an ion implanter;
a processing station; and
a controller,
wherein the controller comprises memory and one or more processors, and
wherein the memory stores one or more programs, the one or more programs comprising instructions, which when executed by the one or more processors, cause the controller to:
control an ion implanter of the ion implantation system to implant ions into a wafer while maintaining the wafer at a first predetermined temperature within a processing chamber of the ion implanter;
control the processing station of the ion implantation system to heat or cool the wafer at the processing station;
after heating or cooling the wafer:
control a laser source of the processing station to direct a first laser beam from the laser source at a first position to a first point on the edge of the wafer;
determine a first distance from the first position of the laser source to the first point on the edge of the wafer based on detecting a reflection of the first laser beam using a laser sensor of the post-implantation station;
control the laser source to direct a second laser beam from the laser source at a second position to a second point on the edge of the wafer;
determine a second distance from the second position of the laser source to the second point on the edge of the wafer based on detecting a reflection of the second laser beam using the laser sensor;
control the laser source to direct a third laser beam from the laser source at a third position to a third point on the edge of the wafer;
determine a third distance from the third position of the laser source to the third point on the edge of the wafer based on detecting a reflection of the third laser beam using the laser sensor;
determine a current diameter of the wafer based at least on the first distance, second distance, and third distance; and
determine a current temperature of the wafer based on the determined current diameter of the wafer; and
in accordance with the determined current temperature of the wafer satisfying a predetermined condition:
control the processing station to forgo continuing to heat or cool the wafer at the processing station; and
control a robotic arm of the ion implantation system to remove the wafer from the processing station.

### Claim at position 15

15-26. (canceled)

### Claim 27

A method for controlling wafer temperature in an ion implantation system having an ion implanter and a processing station, the method comprising:
implanting a wafer with ions from an ion beam while maintaining the wafer at a first predetermined temperature within a processing chamber of the ion implanter;
positioning the wafer between a top capacitive sensor and a bottom capacitive sensor of the processing station, wherein a top side of the wafer faces the top capacitive sensor and a bottom side of the wafer faces the bottom capacitive sensor;
heating or cooling the wafer at the processing station;
after heating or cooling the wafer, at the processing station:
determining a first distance between the top side of the wafer and the top capacitive sensor based on a top capacitance measured by the top capacitive sensor;
determining a second distance between the bottom side of the wafer and the bottom capacitive sensor based on a bottom capacitance measured by the bottom capacitive sensor;
determining a current thickness of the wafer based on the first distance, the second distance, and a predefined distance at which the top capacitive sensor and the bottom capacitive sensor are positioned; and
determining a current temperature of the wafer based on the determined current thickness of the wafer; and
in accordance with the determined current temperature of the wafer satisfying a predetermined condition:
forgoing continuing to heat or cool the wafer at the processing station; and
removing the wafer from the processing station.

### Claim 28 (depends on 27)

The method of claim 27, further comprising:
in accordance with the determined current temperature of the wafer not satisfying the predetermined condition, continuing to heat or cool the wafer.

### Claim 29 (depends on 27)

The method of claim 27, wherein the first distance and the second distance are determined while heating or cooling the wafer.

### Claim 30 (depends on 27)

The method of claim 27, wherein the determination of the current temperature of the wafer is further based on a predetermined wafer thickness corresponding to a second predetermined temperature and a linear thermal expansion coefficient of a material of the wafer.

### Claim 31 (depends on 27)

The method of claim 27, further comprising:
after positioning the wafer at the processing station and prior to heating or cooling the wafer at the processing station, at the processing station:
determining a first reference distance between the top side of the wafer and the top capacitive sensor based on a top reference capacitance measured by the top capacitive sensor;
determining a second reference distance between the bottom side of the wafer and the bottom capacitive sensor based on a bottom reference capacitance measured by the bottom capacitive sensor; and
determining a reference thickness of the wafer based on the first reference distance, the second reference distance, and the predefined distance at which the top capacitive sensor and the bottom capacitive sensor are positioned,
wherein the reference thickness corresponds to the first predetermined temperature, and
wherein the determination of the current temperature of the wafer is further based on the reference thickness and a linear thermal expansion coefficient of a material of the wafer.

### Claim 32 (depends on 27)

The method of claim 27, wherein the processing station is a post-implantation station, and wherein the predetermined condition includes a requirement that the determined current temperature of the wafer be greater than or equal to a third predetermined temperature.

### Claim 33 (depends on 27)

The method of claim 27, wherein the processing station is a pre-implantation station, and wherein the predetermined condition includes a requirement that the determined current temperature of the wafer be less than or equal to the first predetermined temperature.

### Claim 34

A non-transitory computer-readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by one or more processors of a controller of an ion implantation system, cause the controller to:
control an ion implanter of the ion implantation system to implant ions into a wafer while maintaining the wafer at a first predetermined temperature within a processing chamber of the ion implanter;
control a robotic arm of the ion implantation system to position the wafer between a top capacitive sensor and a bottom capacitive sensor of a processing station, wherein a top side of the wafer faces the top capacitive sensor and a bottom side of the wafer faces the bottom capacitive sensor;
control the processing station to heat or cool the wafer at the processing station;
after heating or cooling the wafer:
obtain data representing a top capacitance from the top capacitive sensor;
determine a first distance between the top side of the wafer and the top capacitive sensor based on the data representing the top capacitance;
obtain data representing a bottom capacitance from the bottom capacitive sensor;
determine a second distance between the bottom side of the wafer and the bottom capacitive sensor based on the data representing the bottom capacitance;
determine a current thickness of the wafer based on the first distance, the second distance, and a predefined distance between the top capacitive sensor and the bottom capacitive sensor; and
determine a current temperature of the wafer based on the determined current thickness of the wafer; and
in accordance with the determined current temperature of the wafer satisfying a predetermined condition:
control the processing station to forgo continuing to heat or cool the wafer at the processing station; and
control the robotic arm to remove the wafer from the processing station.

### Claim 35

An ion implantation system, comprising:
an ion implanter;
a processing station; and
a controller,
wherein the controller comprises memory and one or more processors, and
wherein the memory stores one or more programs, the one or more programs comprising instructions, which when executed by the one or more processors, cause the controller to:
control an ion implanter of the ion implantation system to implant ions into a wafer while maintaining the wafer at a first predetermined temperature within a processing chamber of the ion implanter;
control a robotic arm of the ion implantation system to position the wafer between a top capacitive sensor and a bottom capacitive sensor of the processing station, wherein a top side of the wafer faces the top capacitive sensor and a bottom side of the wafer faces the bottom capacitive sensor;
control the processing station to heat or cool the wafer at the processing station;
after heating or cooling the wafer:
obtain data representing a top capacitance from the top capacitive sensor;
determine a first distance between the top side of the wafer and the top capacitive sensor based on the data representing the top capacitance;
obtain data representing a bottom capacitance from the bottom capacitive sensor;
determine a second distance between the bottom side of the wafer and the bottom capacitive sensor based on the data representing the bottom capacitance;
determine a current thickness of the wafer based on the first distance, the second distance, and a predefined distance between the top capacitive sensor and the bottom capacitive sensor; and
determine a current temperature of the wafer based on the determined current thickness of the wafer; and
in accordance with the determined current temperature of the wafer satisfying a predetermined condition:
control the processing station to forgo continuing to heat or cool the wafer at the processing station; and control the robotic arm to remove the wafer from the processing station.

### Claim at position 25

36-48. (canceled)