Abstract:This paper presents a new carrierless approach to handling and processing ultra-thin Silicon which is predominantly used in processing Through Silicon Via (TSV) wafers. Currently, the state of the art consists of bonding the wafers having the vias onto a carrier wafer, after which the thinning steps of the wafer and the backside processing, e.g. Redistribution (RDL) or Bumping, are performed. By means of temporarily bonding the wafer to a carrier, the wafer has structural integrity and can be handled and proce… Show more
“…7 The warpage of the ultrathin wafer can be lowered and the breakage risk during handling can be controlled by using the BGWOR method. 8–10 Figure 1.Schematic of Back Grinding of Wafer with Outer Rim by cup diamond grinding wheel.…”
Back Grinding of Wafer with Outer Rim (BGWOR) is a new method for carrier-less thinning of silicon wafers. In this paper, the simulation model of grinding marks of wafer in BGWOR was developed. With the model, the relationship between process parameters, including wheel rotational speed, wafer rotational speed, wheel infeed rate, spark out time and the protruding height of the abrasive grains in the grinding wheel, and grinding marks was discussed. Reasonable grinding parameters to control the grinding marks were also proposed. The model was verified by the experiments of BGWOR. The results showed that: (1) The pattern of the grinding marks of the wafers in BGWOR was depended on the grinding wheel rotational speed, the wafer rotational speed, the wheel infeed rate, the spark out time and the protruding height of the abrasive grains on the grinding wheel; (2) The angle between two adjacent grinding marks changes as the variation of the wheel rotational speed and wafer rotational speed; (3) The grinding marks density can be controlled by selecting the proper ratio of wheel speed to wafer speed. The depth of grinding marks can be reduced by increasing the spark out time and reducing the protruding height of the abrasive grains.
“…7 The warpage of the ultrathin wafer can be lowered and the breakage risk during handling can be controlled by using the BGWOR method. 8–10 Figure 1.Schematic of Back Grinding of Wafer with Outer Rim by cup diamond grinding wheel.…”
Back Grinding of Wafer with Outer Rim (BGWOR) is a new method for carrier-less thinning of silicon wafers. In this paper, the simulation model of grinding marks of wafer in BGWOR was developed. With the model, the relationship between process parameters, including wheel rotational speed, wafer rotational speed, wheel infeed rate, spark out time and the protruding height of the abrasive grains in the grinding wheel, and grinding marks was discussed. Reasonable grinding parameters to control the grinding marks were also proposed. The model was verified by the experiments of BGWOR. The results showed that: (1) The pattern of the grinding marks of the wafers in BGWOR was depended on the grinding wheel rotational speed, the wafer rotational speed, the wheel infeed rate, the spark out time and the protruding height of the abrasive grains on the grinding wheel; (2) The angle between two adjacent grinding marks changes as the variation of the wheel rotational speed and wafer rotational speed; (3) The grinding marks density can be controlled by selecting the proper ratio of wheel speed to wafer speed. The depth of grinding marks can be reduced by increasing the spark out time and reducing the protruding height of the abrasive grains.
Double‐sided metal‐oxide‐semiconductor field‐effect‐transistor processing is demonstrated for the first time on an ultrathin crystalline silicon substrate of 6‐20 μm in a 100 mm diameter wafer format without a carrier wafer, the thinnest free‐standing silicon wafers ever fabricated. The compatibility of the flexible material with conventional semiconductor processing tools is enabled by supporting an interior ultrathin silicon with a surrounding thicker ring of silicon. Current‐voltage characteristics of transistors on ultrathin silicon show performance as expected from bulk silicon, with electron mobility ~1500 cm2 V−1 second−1. Mechanical measurements quantify the handleability.image
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