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Autofocus method and apparatus for wafer scribing

A device and focus technology, applied in the field of real-time focus, can solve problems such as system confusion, low measurement accuracy, and intensity changes

Inactive Publication Date: 2013-06-26
ELECTRO SCI IND INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For prior art autofocus systems that rely on reflections from the silicon wafer for measurement, this can create multiple signals that vary in intensity, which can confuse the system and result in lower measurement accuracy or prevent the system from fully operate

Method used

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  • Autofocus method and apparatus for wafer scribing
  • Autofocus method and apparatus for wafer scribing
  • Autofocus method and apparatus for wafer scribing

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Embodiment Construction

[0021] As will be described herein, the present invention solves the problems of the prior art by measuring the working laser beam in real time by using a polarized, grazing angle laser beam of selected wavelength to avoid interference from the working laser beam or plasma plume Displacement between focus and workpiece.

[0022] image 3 One embodiment of the present invention is shown. A collimated beam 42 is emitted by a laser diode 40 and then passes through a small circular aperture or pinhole 44 , an illumination lens 46 and a prism 48 . An exemplary laser diode used for this purpose is 0222-002-01 manufactured by Coherent Corporation of Santa Clara, CA, USA, and operates at a power of about 1.6 milliwatts and a wavelength of 650 nanometers (nm). The distance between aperture 44 and lens 46 , and the distance between lens 46 and silicon wafer top surface 50 is approximately twice the focal length of lens 46 . The aperture is thus imaged to a plane which is close to the...

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Abstract

A method and an apparatus perform real time autofocus for a wafer scribing system. The method and apparatus uses polarized light (42) directed to the surface (50) of the wafer (10) directly under the objective lens (26) for the scribing laser beam at a grazing angle. The light reflected from the wafer is filtered (56) to remove light from the scribing laser beam and then focused on a position sensitive device (58) to measure the distance from the objective lens to the wafer surface.

Description

technical field [0001] This invention relates to methods and apparatus for scribing electronic silicon wafers. In particular, the present invention relates to methods and apparatus for performing real-time focusing of a laser beam used to scribe LED silicon wafers to facilitate singulation. More particularly, the present invention relates to the accurate and efficient detection of the position of the surface of the transparent or translucent LED silicon wafer to maintain the focus of the laser beam and the surface of the silicon wafer in real time when the system is scribing the silicon wafer methods and devices for the correct relationship between Background technique [0002] For ease of manufacture, electronic devices are usually constructed on a substrate or silicon wafer that contains multiple devices. These devices must be separated or singulated prior to packaging and sale. A typical method of singulating electronic devices is to use a laser scribing system to scri...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L21/78H01L21/66
CPCB23K26/367B23K26/046H01L21/67265B23K26/4075B23K26/364B23K26/40B23K2103/50
Inventor 谢秀平朱俊蕾芙·萨尔菲尔德黄崇博
Owner ELECTRO SCI IND INC