Process study on large-size silicon wafer grinding by using a small-diameter wheel

Abstract

Silicon (Si) is a fundamental material in the semiconductor industry. The advancement of semiconductor devices have offered convenience and comfort to our life. In order to raise productivity and economic efficiency, the semiconductor industry keeps looking for use of larger size Si wafers. The next generation wafer is expected to be sized as large as 450 mm in diameter. Many wafering processes including lapping, grinding and polishing have been studied and grinding technology stands out as the most promising process for large-size Si wafer manufacturing. In the current in-feed grinding scheme adopted for Si wafers, the wheel diameter used is generally equal to or larger than the wafer diameter. In turn, larger diameter wheels require larger size machine tools and production lines, which lead to increase in manufacturing costs. In this paper, both experiment and kinematical analysis have been carried out to investigate the feasibility of using small diameter grinding wheels to grind large size Si wafers, mainly focusing on the effects of wheel diameter on wafer geometry and surface roughness. The results show that both wheels generated a central convex profile on the wafer and the small wheel achieved a slightly better flatness than the large wheel. The surface roughness were similar one to another for most area of the wafer except the fringe around its edge. All these experimental results were predicable by the kinematic model established in this paper. Particularly, the kinematic analysis found that the cutting path made by small wheel with diameter equaling to the wafer radius was parallel each other at the fringe around wafer edge, which directly worsened the surface roughness.

Deformation and removal of semiconductor and laser single crystals at extremely small scales

“…The characteristics and performance in the grinding of single crystal Si were intensively investigated, including the effects of grinding wheels [46,140,143,152], grinding induced surface/subsurface damages [46,[153][154][155], and optimization of grinding parameters for better surface quality [44,144,148,153,[156][157][158][159][160][161][162][163][164]. As the material removal involved in silicon grinding is often controlled at nanometric scales to ensure the ductile-like removal [153,155,[160][161][162][163], such a grinding process was also termed as nanogrinding.…”

“…For face grinding of a Si substrate or wafer, the wheel diameter is generally sufficiently large to cover the entire workpiece in one grinding revolution [46,157]. Certainly, a smaller diamond wheel would help reduce the processing cost [152]. By carefully planning the cutting paths of the smaller wheel, it is possible to achieve a surface roughness similar to or slightly worse than that obtained using the conventional large wheel [152].…”

“…Certainly, a smaller diamond wheel would help reduce the processing cost [152]. By carefully planning the cutting paths of the smaller wheel, it is possible to achieve a surface roughness similar to or slightly worse than that obtained using the conventional large wheel [152]. In this case, a mathematical model was developed to plan the cutting path, which helped to optimize the grinding conditions too.…”

An Investigation on the Total Thickness Variation Control and Optimization in the Wafer Backside Grinding Process

“…However, more details about the wafer TTV control method and relevant technology requirements were not revealed in their study. Zhou et al [22][23][24] developed a backside grinding machine with a horizontal mode. They also established a simulation model to obtain the wafer TTV profile transition laws at different tilt angle combinations.…”