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Submicron E-Beam Imaging Process

IP.com Disclosure Number: IPCOM000038815D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Gillespie, SJ: AUTHOR

Abstract

By taking advantage of the high resolution and precise overlay capabilities of electron (E)-beam lithography, a process is shown for extending the metal liftoff process to submicron dimensions and thus allowing for tighter packing of metal lines without yield and reliability problems brought about by conventional processes. When the metal liftoff process is utilized in a conventional single or multilayer resist process, the metal level images are subject to problems known as "skirting" and "fencing" which detract from the quality of the final metal image. Skirting is caused by a scattering of evaporated metal under an undercut resist profile and being deposited as a thin metal layer on the substrate adjacent to the metal image being formed. The resulting metal skirt on the image metal is difficult to remove.

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Submicron E-Beam Imaging Process

By taking advantage of the high resolution and precise overlay capabilities of electron (E)-beam lithography, a process is shown for extending the metal liftoff process to submicron dimensions and thus allowing for tighter packing of metal lines without yield and reliability problems brought about by conventional processes. When the metal liftoff process is utilized in a conventional single or multilayer resist process, the metal level images are subject to problems known as "skirting" and "fencing" which detract from the quality of the final metal image. Skirting is caused by a scattering of evaporated metal under an undercut resist profile and being deposited as a thin metal layer on the substrate adjacent to the metal image being formed. The resulting metal skirt on the image metal is difficult to remove. Fencing is caused by a build-up and spiking of metal at the foot of an undercut resist profile. If unwanted metal (skirt and/or spike) is left in place, potential yield and reliability problems can result. The process shown in Fig. 1 through Fig. 6 will eliminate skirting and fencing and extend metal liftoff to submicron dimensions and thus allow for tighter packing of metal lines. Fig. 1 shows a defined resist image using registered direct-write electron-beam exposure techniques. The resist thickness is such that a near vertical resist profile is formed. Next, a conformal coat of either silicon nitride or silicon dioxide is c...