Chemical Mechanical Polishing Equipment And Its Key Technology For 300mm Wafer

Chemical mechanical polishing (CMP) is the important technology, to satisfy the local and golobal planarization, in the process of the intergrated circuit (IC) manufacturing. With the development of the IC processing technology, wafer size is increasing, the device feature size is scaling down for the need of the high chip yield and the low manufacturing cost, and the requirement for the CMP technology and equipment becomes higher and higher. The drive system of the large-scale wafer polisher requires high performance because the drive power rises to the second power of the proportion of the wafer scale. The nonunifomity of the pressure distribution on the wafer surface, especially on the edge, make higher demands on the pressure system and the control technology. On the basis of the deep research on the material removal rate (MRR) and the pressure distribution of wafer, the key technology of the CMP equipment is studied, the main contents and conclusions are as follows:The model of the MRR of a point on the wafer is established by velocity vector integral. The effects of the process parameters, such as the rotation speed, reciprocation range and the reciprocation speed, on MRR and the nonuniformity of the material removal (NUMR) are analyzed. The results of the theoretical analysis show that the speed of the polishing plate is the major factor to affect the MRR, but the speed of the carrier has little effect on it. The reciprocation range has some influence on MRR and NUMR, but the reciprocation speed seldom impacts MRR and NUMR.Based on the model, the effects of the three kinematic forms on MRR and NUMR are analyzed. The results of the theoretical analysis and the experiment show that the reciprocation polisher and the oscillation polisher have little difference on MRR NUMR, but the both have higher MRR and less NUMR than the eccentric polisher.Comparing the structure design of three types of polisher, the scheme of the reciprocating polisher is determinated taking into account the structure and the theory results.The effects of the retaining ring on the pressure distribution on 300mm wafer surface are analyzed by finite element model. The results show that the retaining ring has great influence on the pressure distribution on the wafer edge, and there exists the matching relationship between the pressure on the ring and that on the wafer. Reasonable adjustment of the ring pressure will improve the pressure distribution on the wafer edge.Aiming at the requirement of the pressure distribution uniformity on the wafer surface for the polishing-head press system, the press system is designed in manner of the separate pressure regulation on the retaining ring and the wafer. The downforce on the wafer is applied by the air chamber and regulated by the high-accuracy proportional dump valve. A manner to apply the downforce by compound springs is brought forward to press and regulate the pressure on the retaining ring, and the accuracy of the device is analyzed in theory and by experiment.The structure design of the reciprocating polisher is completed, and the static and dynamic analysis of the important parts is carried out in order to perfect the design. And then scheme of the multi-station, flexibility and automatic polishing system has been put forward, also the control system of the equipment is completed on Personal Computer (PC).