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SUB-MICRON GaAs LINES

IP.com Disclosure Number: IPCOM000043818D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Knoedler, CM: AUTHOR [+2]

Abstract

Sub-micron GaAs lines can be produced in epitaxial GaAs/AlGaAs material using conventional optical lithography techniques and reactive ion etching. Epitaxial layers of GaAs, AlGaAs, and GaAs on a GaAs substrate are shown in Fig. 1. A 2000 ˜ blanket of molybdenum or other selected transition element is deposited on top of the epitaxial layers. The molybdenum and epitaxial layers are patterned with photoresist, e.g., AZ1450J, and exposed using a light field mask. The layers then look as shown in Fig. 2. The width of the stencil lines can easily be achieved with conventional mask aligners and lithographic practices. With the structure of Fig. 2, the following steps are employed. Step 1 The molybdenum, or other transition metal, is etched with a CF4 and O2 mixture. The CF4 + O2 mixture will not etch the GaAs layer underneath.

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SUB-MICRON GaAs LINES

Sub-micron GaAs lines can be produced in epitaxial GaAs/AlGaAs material using conventional optical lithography techniques and reactive ion etching. Epitaxial layers of GaAs, AlGaAs, and GaAs on a GaAs substrate are shown in Fig. 1. A 2000 ~ blanket of molybdenum or other selected transition element is deposited on top of the epitaxial layers. The molybdenum and epitaxial layers are patterned with photoresist, e.g., AZ1450J, and exposed using a light field mask. The layers then look as shown in Fig. 2. The width of the stencil lines can easily be achieved with conventional mask aligners and lithographic practices. With the structure of Fig. 2, the following steps are employed. Step 1 The molybdenum, or other transition metal, is etched with a CF4 and O2 mixture. The CF4 + O2 mixture will not etch the GaAs layer underneath. The structure is shown in Fig.
3. Step 2 Removal of the photoresist layer leaves an exact duplicate of the stencil in the molybdenum. Now, the molybdenum becomes the stencil. The oxide layer on the GaAs is then removed from the GaAs either by chemical means (HCl and H2O) or by RIE (reactive ion etching). Step 3 The GaAs layer is etched using CCl2F2 + He mixture. When the etching reaches the AlGaAs layer, the vertical etching will stop, but there will still be a horizontal or chemical component which will etch the GaAs laterally. Thus, the GaAs will etch gradually inwards, and it can be stopped at the required thickness. The...