Analytical Elastic–Plastic Cutting Model for Predicting Grain Depth-of-Cut in Ultrafine Grinding of Silicon Wafer

Abstract

Grain depth-of-cut, which is the predominant factor determining the surface morphology, grinding force, and subsurface damage, has a significant impact on the surface quality of the finished part made of hard and brittle materials. When the existing analytical models are used to predict the gain depth-of-cut in ultra-precision grinding process of silicon wafer, the results obtained become unreasonable due to an extremely shallow grain depth-of-cut, which is inconsistent with the theory of the contact mechanics. In this study, an improved model for analyzing the grain depth-of-cut in ultra-fine rotational grinding is proposed, in which the minimum grain depth-of-cut for chip formation, the equivalent grain cutting tip radius, elastic recovery deformation in cutting process, and the actual number of effective grains are considered in the prediction of the ultrafine rotational grinding of brittle materials. The improved model is validated experimentally and shows higher accuracy than the existing model. Furthermore, the sensitivity of the grain depth-of-cut to three introduced factors is analyzed, presenting the necessity of the consideration of these factors during the prediction of grain depth-of-cut in ultrafine grinding.

Grinding Marks in Back Grinding of Wafer with Outer Rim

“…After that, wafer rotational speed was 121 r/min and the grinding wheel rotational speed were 2389 and 2409 r/min, respectively. In all experiments, the wheel infeed rate was 20 μm/min and the spark out time was 5 s. According to equation (22) and the research of Lin et al., 17 the value of δ is about 2 μm. It can be seen that the results of the experiments are consistent with the simulation, as shown in Figure 8.…”

“…According to researches of Lin et al. 17 and Young et al., 18 the maximum cutting depth of single abrasive grain is where d g is the cutting depth of single abrasive grain.…”

Elastic recovery of monocrystalline silicon during ultra-fine rotational grinding

“…1, most of the research on grinding considers grit tip radius to be equivalent to an imaginary spheroidal shape radius of the grit and assumes rigid-plastic material while revealing the effect of the grinding process and wheel parameters on average attainable depth-of-cut [8][9]. Earlier, Zhou et al [7] proposed a novel model of ultra-fine rotational grinding incorporating elastic-plastic response of the material and grit tip radius by adding two coefficients relating to material's elastic recovery and grit tip radius respectively. Their results show that the simplified assumption of assuming the grit tip radius as equal to the average grit radius becomes unreasonable in ultra-fine grinding.…”

“…In the past, the concept of machining brittle materials in the ductile-mode such that the material removal occurs by virtue of plastic deformation as opposed to fracture has been well demonstrated in materials ranging from germanium, silicon and silicon carbide [4][5]. For this reason, various theoretical models are proposed aimed at optimisation of the rotational grinding process [6][7]. These models have shown that the quality of the finish depends on grinding parameters, grinding wheel topography, and stability of the tool-workpiece contact (chatter, vibrations etc.).…”

Modeling of Vibration Condition in Flat Surface Grinding Process

“…e methodology validated and provided a detailed information on grinding forces which was not addressed by the previous models. Lin et al [26] proposed a model of surface roughness by analyzing the grit depth of cut model in ultrafine rotational grinding. e results showed that the chip formation, the cutting tip radius, and the effective number of grains have to be considered for grit depth of cut prediction.…”