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Blistering on Silicon Surface Caused by Gettering of Hydrogen on Post-Implantation Defects A.Y. Usenko1, and W.N. Carr2 1 Silicon Wafer Technologies Inc., 240 King Blvd., Newark, NJ, 07102 USA 2 New Jersey Institute of Technology, 323 King Blvd., Newark, NJ, 07102 USA ABSTRACT A well-known process for thinning of silicon by slicing submicron-thick crystalline films from substrates uses direct implantation of protons. In this paper we describe a different way of delivering hydrogen to a cleavage plane. In our process a defect-rich buried layer is first formed with ion implantation. Defects in the as-implanted silicon work as traps for hydrogen. Next monatomic hydrogen is delivered to the trap layer by electrolytic charging. To check sliceability, the samples were annealed and blistering was observed. Evidence of blistering is a sign of potential cleavage. The electrolytic charging was performed using a simple two-electrode cell. The front side of the as-implanted silicon wafer was exposed to an electrolyte. The backside of the wafer was contacted with an aluminum layer and connected to a current source. The acidic electrolyte was buffered with ethylene glycol. Buffering was used to suppress bubbling on the wafer surface and to improve the uniformity of charging. To increase charging current the wafer was illuminated with visible light. A graphite rod was used as the positive electrode in the cell. A few Coulombs per square centimeter of the wafer were passed through the cell during the hydrogenation process. The depth of blisters is about 1/2 of projection range of the implanted ions. It means that the hydrogen platelets are formed in the region of maximum of vacancyenriched post-implantation defects. This process of electrolytic hydrogen charging may be used in future to manufacture silicon-on-insulator wafers with very thin top silicon layer. Thin SOI offers important advantages in the production of substrates for mainstream CMOS integrated circuit manufacturing. INTRODUCTION Wafer bonding combined with delamination of crystalline films from single crystal substrates is used in a well-known silicon-on-insulator technology [1] called Smart-Cut™. In the Smart-Cut process, to delaminate the silicon film, hydrogen ions are implanted with a high dose (more than 4x1016 cm-2 for H+, and 2 1016 cm-2 for H2+) into the silicon wafer [2]. In this process a dense hydrogen-rich layer is formed followed by heating to promote defect transformation. The implanted hydrogen precipitates into platelets or microbubbles with heating. Depending on how deep the hydrogen layer is located, the precipitation results in either (a) cleavage of silicon along the hydrogen layer or (b) blistering of silicon surface. If the hydrogen layer is deeper than few microns, or if the surface is stiffened with an additional bonded or deposited layer, then cleavage proceeds. If hydrogen precipitates closer than about a micron from a surface, the film blisters before the continuous layer formation. Cleavage and blistering phenomena are caused by the same hy