High Phosphorus Doped HDOCVD PSG Film Development And Application

In the manufacture of integrated circuits, PSG film is widely used inPMD (pre metal dielectric) layer. It can effectively capture moving metalions and has a low dielectric constant and other advantages. As the featuresize of ultra large scale integrated circuit continues to shrink, theself-aligned contact hole etching integrated technology is also developingin PMD layer, which can effectively reduce the accuracy requirement oflithography. But the application of this integration process is need the highphosphorus doped PSG film to improve the dry etching selection ratio.Therefore, developing the high phosphorus doped PSG films and making itmeet the requirements of process integration have a very importantsignificance.In this paper, we prepared the9wt%phosphorus doped PSG film byHDPCVD method. Study of the effects of various process parameters onthe properties of the films, the process performance is stable and reliableand meeting the requirements of mass production.For the problem that P concentration distribution of HDPCVD PSG invertical direction is not uniform, we analyze the generating mechanism ofthe problem, optimizing the deposition recipe. At last make the depositiontemperature to match with the PH3flow. The problem is solved.In the integrated process, the wafer center position failure is causedby contact hole that is etched incompletely. The failure is stronglycorrelated with the thickness of the wafer center. Through the tendentiousmanagement of HDPCVD PSG thin film thickness in plane, effectivelyincrease the process window for SAC etching, which solve the failureproblem. For there is a layer of phosphorus doping distribution which is similarto flower shape around the gate, we called Flower Pattern. The study foundthat it is unique to HDPCVD PSG. We also study the formation mechanismof Flower Pattern by various experiments and find the key parametersaffecting the Flower Pattern. Provide a theoretical basis to control theFlower Pattern shape in production.