PECVD Si RN as a protection layer for

PECVD Si. RN as a protection layer for Time. Pix chip Violeta Prodanovic, Else Kooi Laboratory • We used Novellus Concept 1 multi station PECVD system for deposition of Si. RN on TP chip (W 12 H 6). • Metal shield is replaced by 1 mm thick carrier wafer with a pocket slightly larger than the chip. Bond pad area is then covered with polyimide tape (Kapton® Polyimide Film, 3 M™ Tape 5413 ). • Loadlock brings wafer cassette from horizontal to vertical position and vice versa Using the tape requires thorough cleaning procedure of the chip after deposition of protective layer: (99% HNO 3 + acetone + IPA + rinsing) 4. 3 um of Si. RN Previously used metal shield protected bond pad area from Si. RN deposition SEM picture of Si. RN on Si substrate

PECVD Si. RN as a protection layer for Time. Pix chip Violeta Prodanovic, Else Kooi Laboratory • • Part of active area remained bare! To avoid this a roof out of cut silicon piece can be introduced. Temperature of deposition is 400 ℃. Parameters are set so the highest refractive index possible is obtained (higher content of Si). Measured stress = -300 MPa Measured resistivity < 1011 Ohm m This process was partly successful for the single chip we wanted to cover, but… PITFALLS: • • • Not ellegant method (stains on bond pad area and non-covered active parts) Processing of 8’’ wafers is not possible in this system! Voids and other defect centers in the layer? Red line represents refractive index of used Si. RN