Acoustic measurement of fabrication equipment clearance

Patent metadata

Field	Value
Publication number	US-10794872-B2
Application number	US-201514942402-A
Country	US
Kind code	B2
Filing date	Nov 16, 2015
Priority date	Nov 16, 2015
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

A system and method for determining clearance between a fabrication tool and a workpiece is provided. In an exemplary embodiment, the method includes receiving a substrate within a tool such that a gap is defined there between. A transducer disposed on a bottom surface of the substrate opposite the gap provides an acoustic signal that is conducted through the substrate. The transducer also receives a first echo from a top surface of the substrate that defines the gap and a second echo from a bottom surface of the tool that further defines the gap. A width of the gap is measured based on the first echo and the second echo. In some embodiments, the bottom surface of the tool is a bottom surface of a nozzle, and the nozzle provides a liquid or a gas in the gap while the transducer is receiving the first and second echoes.

First claim

What is claimed is:

1. A method comprising:
delivering a fluid to a top surface of a substrate by moving a nozzle along the top surface of the substrate, wherein a gap is defined between the top surface of the substrate and the nozzle;
moving a transducer along a bottom surface of the substrate, wherein the moving of the transducer tracks the moving of the nozzle, such that the transducer remains aligned with the gap during the delivering of the fluid to the top surface of the substrate; and
measuring a width of the gap at multiple locations during the delivering of the fluid to the top surface of the substrate, wherein at each of the multiple locations, the measuring includes:
sending, by the transducer, an acoustic signal through the substrate towards the gap, and
receiving, by the transducer, a first echo of the acoustic signal from the top surface of the substrate and a second echo of the acoustic signal from the nozzle, wherein the width of the gap is based on the first echo and the second echo.

2. The method of claim 1 , wherein the delivering the fluid to the top surface of the substrate includes delivering a liquid to the top surface of the substrate during a cleaning process.

3. The method of claim 1 , wherein the delivering the fluid to the top surface of the substrate includes delivering gas to the top surface of the substrate during a cleaning process.

4. The method of claim 1 , wherein the delivering the fluid to the top surface of the substrate includes delivering a spin coating material to the top surface of the substrate during a spin-coating process.

5. The method of claim 1 , wherein, at each of the multiple locations, the measuring further includes:
determining a first time at which the first echo is received by the transducer and a second time at which the second echo is received by the transducer; and
determining a difference between the second time and the first time.

6. The method of claim 5 , wherein, at each of the multiple locations, the measuring further includes multiplying the difference between the second time and the first time by a speed of the acoustic signal through a material within the gap and dividing by two.

7. The method of claim 1 , further comprising determining whether the top surface of the substrate and a bottommost surface of the nozzle are parallel based on the width of the gap at the multiple locations.

8. The method of claim 1 , further comprising determining a uniformity of the gap based on the width of the gap at the multiple locations.

9. The method of claim 1 , wherein the transducer includes a transducer layer and an impedance matching layer, wherein the acoustic signal is conducted from the transducer layer to the substrate through the impedance matching layer.

10. The method of claim 9 , wherein the impedance matching layer has a thickness that is substantially equal to an integer multiple of a quarter of a wavelength corresponding with a center frequency of the transducer.

11. The method of claim 9 , wherein the impedance matching layer has an impedance between that of the transducer and that of the substrate.

12. A method comprising:
emitting, by a transducer, acoustic energy through a substrate positioned within an integrated circuit (IC) processing system;
receiving, by the transducer, reflected acoustic energy from a surface of the substrate and a surface of the IC processing system;
converting, by the transducer, the reflected acoustic energy into electrical signals that indicate multiple echo responses from the surface of the substrate and multiple echo responses from the surface of the IC processing system;
identifying, by a signal processing resource coupled to the transducer, a first order echo response from the multiple echo responses from the surface of the substrate and a first order echo response from the multiple echo responses from the surface of the IC processing system;
evaluating, by the signal processing resource, a width of a gap defined between the surface of the substrate and the surface of the IC processing system based on the first order echo response from the multiple echo responses from the surface of the substrate and the first order echo response from the multiple echo responses from the surface of the IC processing system; and
wherein a location of the gap changes as a location of the surface of the IC processing system changes relative to the surface of the substrate during an IC process and the transducer tracks the surface of the IC processing system as the location of the surface of the IC processing system changes relative to the surface of the substrate during the IC process, such that the method further includes aligning the transducer at more than one location with the gap during the IC process and performing the emitting and the receiving at the more than one location during the IC process.

13. The method of claim 12 , wherein the evaluating the width of the gap includes determining a difference in time between receipt of the identified first order echo response from the surface of the substrate and receipt of the identified first order echo response from the surface of the IC processing system.

14. The method of claim 12 , further comprising, based on the width of the gap at the multiple locations, determining whether the surface of the substrate and the surface of the IC processing system are parallel across the gap.

15. The method of claim 12 , wherein the substrate is a quartz mask and the transducer physically contacts the quartz mask.

16. The method of claim 12 , wherein the IC process includes supplying a liquid to the substrate during a cleaning process.

17. The method of claim 12 , wherein the IC process includes supplying a gas to the substrate during a cleaning process.

18. A method comprising:
aligning a transducer with a gap between a substrate and a nozzle of an integrated circuit (IC) processing system during processing of the substrate, wherein the processing includes cleaning the substrate with a liquid or a gas supplied via the nozzle;
emitting, by the transducer, acoustic energy through the substrate towards the gap;
receiving, by the transducer, reflected acoustic energy from at least one surface of the substrate and at least one surface of the nozzle defining the gap;
generating, by the transducer, electrical signals from the reflected acoustic energy that indicates a width of the gap; and
wherein a location of the gap changes as the nozzle sweeps across the substrate during the processing, the method further comprising re-aligning the transducer at each location with the gap, such that the emitting, the receiving, and the generating is performed at multiple locations.

19. The method of claim 18 , wherein the at least one surface of the substrate is an interface between the substrate and the liquid or the gas and the at least one surface of the nozzle is an interface between the nozzle and the liquid or the gas.

20. The method of claim 18 , further comprising adjusting a processing parameter of the cleaning the substrate based on the width of the gap.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Deng jun-hao
• Lin Kuan-Wen
• Chin Sheng-Chi
• Lee Yu-Ching

Classifications

• H10P74/20

  characterised by the properties tested or measured, e.g. structural or electrical properties · CPC title

• H10P72/0604

  Process monitoring, e.g. flow or thickness monitoring · CPC title

• H10P70/00

  Cleaning of wafers, substrates or parts of devices · CPC title

• H10P14/6342

  Liquid deposition, e.g. spin-coating, sol-gel techniques or spray coating · CPC title

• H10P14/46

  using a liquid · CPC title