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Thinning of Prescribed Regions of LPE Samples for Electron Microscopy

IP.com Disclosure Number: IPCOM000082376D
Original Publication Date: 1974-Nov-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Blum, JM: AUTHOR [+3]

Abstract

A method has been devised for preparing predetermined regions of liquid phase epitaxially (LPE) grown material, so that the material can be thin enough to be viewed in an electron microscope without damage.

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Thinning of Prescribed Regions of LPE Samples for Electron Microscopy

A method has been devised for preparing predetermined regions of liquid phase epitaxially (LPE) grown material, so that the material can be thin enough to be viewed in an electron microscope without damage.

In the study of LPE layers under an electron mricroscope, the layer being examined must be less than one micron. Such thin samples are difficult to manipulate without breakage. To obtain thinness, yet allow for strength, a chip is prepared (See Fig. 1) by growing a layer 2 of GaAlAs by LPE growth onto a substrate 4 of GaAs. The GaAs substrate 4, after it has been prepared and chemically polished to be about 4 mils thick, is mounted so that the LPE grown side is attached to a quartz disk 6, using glycol phthalate or other suitable binding agent that is transparent and removable.

Using a photoresist mask 8 to delineate the region of GaAs to be etched, a solution of H(2)O(2), pH adjusted 7.05-7.40 with NH(4)OH, is used to electively etch away the GaAs over the GaAlAs layer 2. Other faster etches may be used, prior to reaching the GaAlAs LPE layer 2, with the final etching step being a chemical etch.

When the photoresist mask 8 is removed and the GaAlAs layer 2 is stripped from the quartz mounting block 6, a self-supporting, thin film of GaAlAs is available (See Fig. 2) for examination under an electron microscope.

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