Transformation of hydrogen trapped onto microbubbles into H platelet layer in SI

Abstract

Features of a process of delamination of a crystalline silicon layer from a silicon wafer along a hydrogen platelet layer formed by r.f. plasma hydrogenation are described. The process involves first making a buried layer of nuclei for hydrogen platelets. Ion implantation of inert or low-soluble gases is used to form the layer. The nuclei are microbubbles that appear along the R_p plane of implanted ions. Results for argon are presented. Wafers implanted with a dose of 10¹⁵ cm⁻² are then hydrogenated with an r.f. plasma. During hydrogenation, atomic hydrogen diffuses into the silicon wafer and collects onto internal surfaces of the microbubbles. Then the hydrogen increases the internal surface of the microbubbles by growing platelet-type extensions to the microbubbles. The extensions grow preferentially along the buried-layer plane. A silicon layer above the layer of grown platelets was delaminated through a pre-bonding/cut/post-bonding sequence as in a standard layer-transfer process. The plasma hydrogenation of the trap layer may be used as a step in a process of fabricating of SOI wafers with a very thin top crystalline silicon layer. Also, implant doses needed to form the microbubble trap layer are much lower than doses of direct implantation of hydrogen in the layer-transfer process.