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Laser texturing of ceramic-containing articles

Pending Publication Date: 2020-07-16
M CUBED TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent is about a device for handling semiconductor wafers. A way to reduce friction between the wafer and the support surface is to remove a portion of the support surface through machining, such as a groove or channel, or a plurality of holes. This texture or controlled roughness on the support surface helps prevent the wafer from sticking during processing. The machining can be done using a laser, which can be a thermal or cold ablation laser, or a modified laser to reduce oxidation of non-oxide materials. Overall, this invention helps improve the efficiency and quality of semiconductor wafer processing.

Problems solved by technology

When stickiness is present between a wafer and a wafer support surface, it is difficult to quickly chuck and de-chuck a wafer, and it is difficult to hold a wafer in a precision fashion.
Currently available methods to machine these pin patterns, such as Electric Discharge Machining (EDM), struggle to meet the demand for smaller and more precisely controlled pins.
EDM preferentially machines the metallic component of these composites, leading to sub-surface damage (i.e. cracks and voids) and particle formation.
Moreover, EDM leaves a surface oxide layer (also known as “re-cast”) that can lead to particle contamination in wafer handling operations.
Still further, EDM suffers from poor dimensional control.
However, conventional laser machining can locally heat the material, which can cause surface modifications and oxide formation.
Such surface modifications and oxide formation are highly undesirable due to an increased propensity for particle contamination.
Cold-ablation does not completely avoid local heating, however, and some oxide formation can occur.

Method used

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  • Laser texturing of ceramic-containing articles
  • Laser texturing of ceramic-containing articles
  • Laser texturing of ceramic-containing articles

Examples

Experimental program
Comparison scheme
Effect test

example 1

hining Pins in a Si / SiC Wafer Chuck

[0086]Refer now to FIGS. 1A and 1B, which are SEM photographs at different magnifications of pins in a Si / SiC wafer chuck that were laser machined according to the instant invention. The laser machining was performed by means of a cold ablation laser apparatus modified or supplemented with a means (e.g., a nozzle) to direct an inert gas (here, argon gas) onto the surface of the Si / SiC material to be machined in the vicinity, zone or region of the laser beam.

[0087]In addition to little-to-no surface modification of the machined surface of the Si / SiC material, the Ar-assisted cold-ablation laser machining provides;[0088]For more precise control of machined features[0089]Much less sub-surface damage[0090]Smoother surface finishes[0091]Much less roughness on feature edges[0092]No evidence of crack or void formation[0093]Avoidance of oxidation and reduced propensity for particle formation.

[0094]By “avoidance of oxidation”, the Applicant means that no ox...

example 2

n of Laser Drilled Holes in Si / SiC

[0095]This example shows the effect of adding an inert gas “assist” to a cold ablation laser machining process.

[0096]Here, the process is in drilling a hole in a Si / SiC composite material formed by a reaction-forming process. FIG. 3 shows the process being conducted in air. The left side of the figure is a SEM photo of the hole. The right side of the figure shows the elemental analysis of the edge of the hole according to energy dispersive analysis by x-ray (EDAX).

[0097]Similarly, FIG. 4 shows the process being conducted in flowing argon cover gas. The left side of the figure is a SEM photo of the hole. The right side of the figure shows the elemental analysis of the edge of the hole according to energy dispersive analysis by x-ray (EDAX). Comparing the ratio or relative sizes of the oxygen peak to the silicon peak in FIG. 3 versus FIG. 4, one can see that the oxygen peak is greatly reduced where the argon cover gas was used, indicating much less ox...

example 3

n of Pocket Cuts in Si / SiC

[0099]This example compares the quality of a “pocket cut” among the modified cold ablation laser machining technique of the instant invention, a prior art cold ablation laser machining process, and a prior art electrical discharge machining process. In each instance, the pocket cut was prepared on a sample of Si / SiC composite material produced by reaction bonding. A pocket cut may be prepared by providing an orthogonal prism of material such as a cube, and proceeding to shave off material on one side to a desired depth but leaving a region near the top surface intact, and then doing the same on an adjacent side surface, again leaving a region near the top surface undisturbed.

[0100]FIGS. 5A, 5B and 5C are SEM photographs at the same magnification of pocket cuts made into the Si / SiC samples by EDM, the prior art cold ablation laser in air, and the instant cold ablation laser machining under protective argon gas flow. The samples are oriented each the same way...

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Abstract

A laser texturing process modifies the surface of a semiconductor wafer-handling device so that flatness is maintained, but controlled roughness is imparted to prevent unwanted wafer sticking. The laser texturing may be from a thermal laser, a cold ablation laser, or either laser modified with an inert cover gas. The laser etches or burns away a portion or fraction of a flat surface, thereby reducing the area of contact to the semiconductor wafer and thereby reducing friction and sticking. The etched or burned-away portion is thus at a reduced, relieved or lower elevation than the unaffected portion. The laser texturing may take the form of a plurality of channels cut into the surface, or a plurality of holes. Laser machining can yield a semiconductor wafer handling device having finer detail than can be produced by other shaping techniques, with feature sizes on the order of 50 microns being achievable.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)[0001]This patent document claims the benefit of U.S. Provisional Application Ser. Nos. 62 / 500,482 and 62 / 500,491, each filed on May 2, 2017. Where permitted by law, the entire contents of each of these commonly owned patent applications are expressly incorporated by reference herein.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH[0002]None.TECHNICAL FIELD[0003]In one aspect, the present invention relates to machining techniques for use on ceramic-containing materials, including composites and glasses. The present invention particularly relates to laser machining techniques.[0004]In another aspect, the present invention relates to machining methods for imparting a controlled roughness to an otherwise flat, smooth surface, particularly in articles or components for handling semiconductor wafers (e.g., silicon) wafers for processing, which could be, but is not limited to, lithography.BACKGROUND ART[0005]As Moore's Law pushes semiconductor feat...

Claims

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Application Information

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IPC IPC(8): B23K26/352B23K26/03B23K26/364
CPCB23K26/032B23K26/364B23K26/355B23K2103/52B23K26/123B23K26/14B23K26/36B23K26/40B23K26/0624B23K2103/02B23K2103/08B23K2103/50B23K26/0876B23K26/10B23K26/1464B23K26/362B23K26/402C04B41/0036C04B41/5346C04B41/91H01L21/68735H01L21/687
Inventor GRATRIX, EDWARD J.AGHAJANIAN, MICHAEL K.MASTROBATTISTO, DANIELMCDANNALD, AUSTIN SCOTT
Owner M CUBED TECH
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