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Browse Prior Art Database

Laser Cleaving as an Analytical Technique

IP.com Disclosure Number: IPCOM000048144D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 3 page(s) / 67K

Publishing Venue

IBM

Related People

Wade, JA: AUTHOR

Abstract

This technique relates to the use of a laser to scribe lines, in a semiconductor wafer surface, that bracket a specific device or area, to facilitate cleaving through a specific device or area of concern.

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Laser Cleaving as an Analytical Technique

This technique relates to the use of a laser to scribe lines, in a semiconductor wafer surface, that bracket a specific device or area, to facilitate cleaving through a specific device or area of concern.

Techniques presently in common usage normally involve tedious 90 degree microsectioning methods or a trial and error mechanical scribing technique that lacks precision in determining the cleave plane. The new technique is precise and takes 1/30th of the time required of the old sectioning method.

The cleave plane in this approach will project through the device or area and yield a 90 degree cross-section of the device or area vertical structure. This cross-section could then be treated, if required, using preferential etching techniques to delineate specific layers within the structure for SEM/EDX (Scanning Electron Microscope/Energy Dispersive X-ray) or SEM topographical analysis.

The use of this technique virtually eliminates the need for reworking samples that have been damaged or contaminated by repeated handling involved when using the old techniques. SEM analytical results were enhanced by the new technique. A comparison of steps required by the new and old methods follows: New Old

1) Laser scribe sample 1) Mount sample on

microsection holder

2) Cleave sample 2) Align sample on holder

3) Etch, if necessary, 3) Wait for holder mounting

to delineate structure material to set

4) Mount sample for SEM 4) Clean excess mounting

material from sample

5) Insert in SEM 5) Check for alignment (re-do,

if necessary)

6) Microsection sample

7) Etch sample

8) Remove sample from holder

9) Clean sample

10) Mount for SEM

11) Check for cleanliness

(re-do, if necessary)

12) Insert in SEM

In Fig. 1, note that the scribe marks need not be placed exactly next to the device to be cleaved, only in close proximity. The 100X photomicrograph shows the scribe tracks along which the cleave will occur.

As shown in Fig. 2, the specimen was fractured or "cleaved", along the plane outlined by the laser scribe, by placing the scribe line axis such that with the scribed side up, it is over an object providing a fulcrum point (glass slide edge, a wire, etc.) for the fracture. Pressure applied with a wooden toothpick or Q-tip

1

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simultaneously to each side of the scribe line would cause a fracture to propagate along the scribe line, as shown in th...