Effect of saw-damage etching conditions on flexural strength in si wafers for silicon solar cells

Byung Jun Kang, Sungeun Park, Seung Hun Lee, Hyunho Kim, Bong Gul Shin, Soonwoo Kwon, Jai Won Byeon, Sewang Yoon, Donghwan Kim

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

We have studied methods to save Si source during the fabrication process of crystalline Si solar cells. One way is to use a thin silicon wafer substrate. As the thickness of the wafers is reduced, mechanical fractures of the substrate increase with the mechanical handling of the thin wafers. It is expected that the mechanical fractures lead to a dropping of yield in the solar cell process. In this study, the mechanical properties of 220-micrometer-solar grade Cz p-type monocrystalline Si wafers were investigated by varying saw-damage etching conditions in order to improve the flexural strength of ultra-thin monocrystalline Si solar cells. Potassium hydroxide (KOH) solution and tetramethyl ammonium hydroxide (TMAH) solution were used as etching solutions. Etching processes were operated with a varying of the ratio of KOH and TMAH solutions in different temperature conditions. After saw-damage etching, wafers were cleaned with a modified RCA cleaning method for ten minutes. Each sample was divided into 42 pieces using an automatic dicing saw machine. The surface morphologies were investigated by scanning electron microscopy and 3D optical microscopy. The thickness distribution was measured by micrometer. The strength distribution was measured with a 4-point-bending tester. As a result, TMAH solution at 90°C showed the best performance for flexural strength.

Original languageEnglish
Pages (from-to)617-622
Number of pages6
JournalKorean Journal of Materials Research
Volume20
Issue number11
DOIs
Publication statusPublished - 2010

Keywords

  • Flexural strength
  • Saw damage etching
  • Solar cell
  • Ultra-thin silicon wafer

ASJC Scopus subject areas

  • Materials Science(all)

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