| Summary: | 碩士 === 國立清華大學 === 材料科學與工程學系 === 86 === A cold/hot Al sputtering was processing to fill contact, 0.4 μm open, aspect ratio up to 4 and collimated Ti/TiN was initial deposited following RTP treatment to be barrier layer. Stacks, IMP Ti 80nm/cold Al 200nm/Hot Al 800nm, were deposited without vacuum break in an Endura PVD system. A base vacuum (2*10-8 Torr) was required to prevent oxygen contamination and maintain a clean surface for sputtering. The Hot Al film was deposited and at wafer temperature varies 430℃ and 480℃ in two comparative cases. During hot depositing, a Al-Ti-(Si) compound was form to be a wetting layer for Al to flow into contact. Al plug can fill the contact completely during 430℃reflow, but cannot fill with voids left in contact during 480℃ reflow. With a experiment of sequential display in depositing layer by layer, evolution of the surface topography during cold/hot Al process can be described. It could be find that the wetting layer was presented as a conformal and continuous film. cover the contact sidewall at 430℃, thus hot Al film filled the contact by reflowing through surface diffusion. But it presents a discontinuous wetting layer in at 480℃, called de-wet effect. De-wet effect was caused by inordinate grain growth at higher temperature thus to form a discontinuous film in sidewall. The barrier collimated Ti/TiN was qualified for Al plug in the paper, but Al spiking occurred. In a modified process in this paper, A CVD-TiN was introduced to enhance the barrier layer and replace IMP Ti to be a glue layer. Depositing of stacks, CVD-TiN 10nm/ Cold Al 200nm/ Hot Al 800nm, was confirmed as a successful process for filling contact at wafer temperature 430℃. All analysis was characterized using XSEM and XTEM.
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