Automated particle removal system

Patent metadata

Field	Value
Publication number	US-11017996-B2
Application number	US-201916375913-A
Country	US
Kind code	B2
Filing date	Apr 5, 2019
Priority date	Apr 5, 2019
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

A foreign particle removal system for removing a particle from a surface of a fragile object has a tool gripper which grips a particle removal tool. A force sensing device determines a cleaning position of the particle removal tool relative to the surface whereat a threshold force is exerted on the surface, the threshold force being a force that is exerted by the particle removal tool on the surface that would pick up the foreign particle but would not damage the object. The particle removal tool is conveyed over a location of the foreign particle and is moved towards the surface to the cleaning position whereat the threshold force is exerted on the surface. The particle removal tool is then lifted away from the surface together with the foreign particle.

First claim

The invention claimed is:

1. Method for removing a foreign particle from a surface of a fragile object, the method comprising the steps of:
gripping a particle removal tool with a tool gripper;
determining with a force sensing device a cleaning position of the particle removal tool relative to the surface whereat a threshold force is exerted on the surface at the cleaning position, the threshold force being a force that is exerted by the particle removal tool on the surface that would pick up the foreign particle but would not damage the fragile object;
determining a position of a tip of the particle removal tool with an optical device prior to conveying the particle removal tool over a location of the foreign particle;
conveying the particle removal tool with the tool gripper over the location of the foreign particle and moving the particle removal tool towards the surface to the cleaning position whereat the threshold force is exerted on the surface with the tip of the particle removal tool; and
lifting the foreign particle away from the surface with the particle removal tool.

2. Method as claimed in claim 1 , further comprising the step of ascertaining the location of the foreign particle on the surface by inspecting the surface using an automated optical inspection device.

3. Method as claimed in claim 1 , wherein the particle removal tool is gripped and taken by the tool gripper from a cleaning tool station containing a supply of multiple particle removal tools.

4. Method as claimed in claim 1 , wherein the force sensing device is a force/pressure transducer which is located at a force calibration station, the tip of the particle removal tool being conveyed to the force calibration station to contact the force/pressure transducer prior to conveying the particle removal tool over the location of the foreign particle.

5. Method as claimed in claim 4 , wherein the force/pressure transducer is separate from the tool gripper and the particle removal tool, and the force/pressure transducer comprises a force sensor or a strain gauge.

6. Method for removing a foreign particle from a surface of a fragile object, the method comprising the steps of:
gripping a particle removal tool with a tool gripper;
determining with a force sensing device a cleaning position of the particle removal tool relative to the surface whereat a threshold force is exerted on the surface at the cleaning position, the threshold force being a force that is exerted by the particle removal tool on the surface that would pick up the foreign particle but would not damage the fragile object;
conveying the particle removal tool with the tool gripper over a location of the foreign particle and moving the particle removal tool towards the surface to the cleaning position whereat the threshold force is exerted on the surface; and
lifting the foreign particle away from the surface with the particle removal tool, wherein the force sensing device is a force/pressure transducer which is located at a force calibration station positioned next to an optical device, the optical device being for determining a position of a tip of the particle removal tool prior to conveying the particle removal tool over the location of the foreign particle.

7. Method as claimed in claim 4 , further comprising the step of gradually decreasing a distance between the tool gripper and the force/pressure transducer, and determining the cleaning position whereat a force corresponding to the threshold force is detected by the force/pressure transducer.

8. Method as claimed in claim 1 , wherein the force sensing device is a force/pressure transducer coupled to the tool gripper, the force/pressure transducer monitoring a force being exerted by the particle removal tool on the surface at each position of the particle removal tool relative to the surface.

9. Method as claimed in claim 8 , further comprising the step of monitoring a position of the particle removal tool relative to the surface when the particle removal tool is being moved by the tool gripper.

10. Method as claimed in claim 8 , wherein the tool gripper pushes the particle removal tool against the surface until the threshold force is reached, whereupon the particle removal tool is lifted away from the surface together with the foreign particle.

11. Method as claimed in claim 8 , wherein the force/pressure transducer comprises a force sensor or a strain gauge.

12. Method as claimed in claim 1 , wherein the particle removal tool comprises a gel stick which has a gel-like substance attached to one end of the gel stick for attracting foreign particles.

13. Method as claimed in claim 1 , wherein the fragile object is a CMOS sensor that is arranged and conveyed on a carrier.

Assignees

• Asm Tech Singapore Pte Ltd

Inventors

• Shu Gang
• Ong Chin Tiong
• Song Keng Yew
• Tan Qing Le

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P70/60 Primary

  Cleaning only by mechanical processes · CPC title

• H10F39/011

  Manufacture or treatment of image sensors covered by group H10F39/12 · CPC title

• G01L1/26

  Auxiliary measures taken, or devices used, in connection with the measurement of force, e.g. for preventing influence of transverse components of force, for preventing overload · CPC title

• G01B11/005

  coordinate measuring machines · CPC title