Patent WO-2022035467-A1 (WO)
Title: Integrated circuit bond pad with multi-material toothed structure
Inventor: SATO JUSTIN
IPC: H01L21/60
Filed: 2021-02-16
Abstract: An integrated circuit device may include a multi-material toothed bond pad (306, 406, 770, 940, 1102, 1202) including (a) an array of vertically-extending teeth (320, 420, 720, 904, 1110, 1204) formed from a first material and (b) a second material (fill material) (322, 422, 760, 930, 1112, 1206) at least partially filling voids (724, 906, 1206) between the array of teeth (320, 420, 720, 904, 1110, 1204). The teeth (320, 420, 720, 904, 1110, 1204) may be formed by depositing and etching the first material and the fill material (322, 422, 760, 930, 1112, 1206) may be deposited over the array of teeth (320, 420, 720, 904, 1110, 1204) and extending down into the voids (724, 906, 1206) between the teeth (320, 420, 720, 904, 1110, 1204), and etched to expose top surfaces of the teeth (320, 420, 720, 904, 1110, 1204). The array of teeth (320, 420, 720, 904, 1110, 1204) may collectively define an abrasive structure. The multi-material toothed bond pad (306, 406, 770, 940, 1102, 1202) may be bonded to another bond pad (304, 404, 1142, 1222), e.g., using an ultrasonic or thermosonic bonding process, during which the abrasive teeth (320, 420, 720) may abrade, break, or remove unwanted native oxide layers formed on the respective bond pad (304, 306, 404, 406, 770) surfaces, to thereby create a direct and/or eutectic bonding between the bond pads (304, 306, 404, 406, 770). The teeth (320, 420, 720) may comprise oxidized teeth (324, 424, 754) including an oxide layer (312, 412, 764) formed on each tooth (320, 420, 720), wherein the oxide layer (312, 412, 764) formed on each tooth (320, 420, 720) may define the abrasive structure. The teeth (720) may include silicon nodules at an exposed surface of the tooth (720). A roughening process may be performed to increase a surface roughness of the teeth (320, 324, 420, 424, 720, 754). The integrated circuit device may comprise an interposer (203, 402, 700, 900, 1100, 1200) and/or an integrated circuit die (300, 400a, 400b, 1140a, 1140b, 1220). The first material may comprise aluminum and the second material (322, 422, 760, 930, 1112, 1206) may comprise silver. Alternatively, the first material may comprise silicon. A bond pad (1142) configured to bond with a toothed bond pad (1102) may have a three-dimensional shape designed to further improve bonding with the toothed bond pad (1102), e.g., a three-dimensional shape including recesses or other geometries configured to receive the teeth (1110) of the toothed bond pad (1102); in particular, each bond pad (1142) may include a plurality of protrusions (1144) that define openings or voids (1146) configured to receive the teeth (1110), wherein the protrusions (1144) may be tapered, rounded, or otherwise configured to facilitate a self-alignment of each bond pad (1142) with a corresponding bond pad (1102). Metal bumps (e.g., gold stud bumps (1230)) may be applied to the bond pads (1222) that engage with the multi-material toothed bond pads (1202), wherein the multi-material toothed bond pads (1202) may be fully covered by an underfill region (1210), e.g., comprising epoxy.