Stress and bowing engineering in passive silicon interposer

Three modifications of the structure of a 4 BEOL layers with 10×100μm TSV Si interposer are proposed to mitigate the tensile stress and release the interposer warpage. By using a thicker compressive PMD layer, reducing Metal1 thickness and using a higher compressive oxide to build the BEOL, the bowing contributions of the TSV, Metal1 and Via2 to Metal4 were reduced by 75%, 37% and 120% respectively. In total, the bowing at wafer level was reduced by 75% after full interposer front side processing.