成果報告書詳細
管理番号20120000000568
タイトル*平成23年度中間年報 太陽エネルギー技術研究開発 太陽光発電システム次世代高性能技術の開発 マルチワイヤーソーによるシリコンウエハ切断技術の研究開発
公開日2012/12/4
報告書年度2011-2011
委託先名株式会社コベルコ科研
プロジェクト番号P07015
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:
[記載項目]
23年度は前年度に導入した高線速マルチワイヤーソーを用いて切断実験を行い、中間目標のいくつかを達成するに至った。
英文要約Title:High performance PV generation system for the future. Development of slicing technology of Si wafer by multi wire saw system. (FY2010-FY2012) FY 2011 Annual Report
The target of this development is to get high quality Si wafers with minimum kerf loss. Combination of resin coated steel saw wire (R-wire) and diamond loose abrasive is employed in this development. In fiscal year 2010, a high speed type multi wire saw was introduced and it has worked from the beginning of fiscal 2011. Using R-wire of 0.12mm diameter steel core wire and 60x20x50mm Si block, the optimization of slicing parameters was established. Size of the Si block was changed bigger and finally 125mm square wafers were obtained. Using these wafers, study of advantage of R-wire slicing has been started by solar cell trial production. To minimize the kerf loss, thinner R-wire of 0.1mm diameter steel core wire was prepared and the minimum kerf loss of 115μm was established with 135μm wafer thickness using 60x20x50mm Si block. In some cases, slicing loss, which is difference of kerf loss and R-wire diameter including resin thichness, became nearly zero. This shows a possibility of ultimate small kerf loss using thinner R-wire. It became clear that the biggest advantage of R-wire slicing is small damage layer of less than 5μm at the surface of Si wafer. At the surface of Si sliced by R-wire, dislocation etch pit is not observed by optical microscope and slicing groove depth determines the damage layer depth. By TEM observation, dislocation exist around 0.5μm deep at the surface of Si sliced by R-wire. This suggests that etching process to eliminate the damage layer before texturing process is not necessary when the wafers sliced by R-wire are employed in a solar cell manufacturing line. Some numerical simulations were carried out and new suggestions to improve slicing ability of R-wire were obtained about viscosity of coolant and gap control between R-wire and Si during slicing. These suggestions will be investigated in nest fiscal year. A new candidate of resin for R-wire was selected by investigation of wide variety of resin materials. The resin will be tested in nexst fiscal year. By activities in fiscal 2011, prospect for achieving the target of this development (damage layer depth, surface roughness, kerf loss, and wafer thickness) becomes good except for slicing speed (Si ingot feed speed). To improve the slicing speed is one on the most important subject in next fiscal year.
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