The Mechanism Of An Abnormal Stress Behavior Of HDPCVD Oxides On Metal-Patterned Wafer

Abstract

High-density plasma (HDP) CVD has been of great interests in past several years since it produces higheir density films with good water blocking and gap-filling capability. In HDPCVD, deposition and sputter etching occur simultaneously by applying a substrate bias [I]. In addition, the compressive stress of HDPCVD oxide is expected to compensate the tensile stress of metal film. Our recent work, however, shows that the deposition of HDPCVD oxide on metalpatterned wafer increased the absolute bow value of the wafer. In this paper, an abnormal stress behavior of HDPCVD oxide on metal pattern is presented with the experimental results. Metal patterning on the wafers with AI-O.S%Cu films of 600014 or 1400014, was splited by photomasks with different metal pattern density of 47%, 71% and 88%. The magnitude of wafer bow after the deposition of HDPCVD oxide was measured as a function of oxide thickness. The stress behavior of the HDPCVD oxide on poly-Si pattern was also investigated. HDPCVD oxide was deposited alt AMT CENTURA, and the magnitude of wafer bow was meausred by FIX 2900. It is found that the magnitude of wafer bow, increased by the deposition of AI-O.S%Cu metal film, becomes smaller when the metal film of the wafer is patterned, and the final value of wafer bow after the patterning is proportional to the pattern density. Therefore, the magnitude of wafer bow after patterning is expressed as follow [2].