Magnet assisted alignment method for wafer bonding and wafer level chip scale packaging

摘要

A high-precision alignment method with high throughput is proposed, which can be used for wafer-to-wafer, chip-to-wafer or chip-to-chip bonding. The scheme implements pairing patterned magnets predetermined designed and made using wafer level process on two components (wafer or chip). The magnetization in patterned magnet can be set at predetermined configuration before bonding starts. When, the two components are bought to close proximity after a coarse alignment, the magnetic force will bring the magnet pairs together and aligned the patterned magnet on one component with its mirrored or complimentary patterned magnets on the other component to minimize the overall the magnetic energy of the pairing magnet. A few patterned magnet structures and materials, with their unique merits are proposed as examples for magnet pair for the self-alignment purpose. This method enables solid contact at the bonding interface via patterned magnets under the magnetic force, which avoid the wafer drafting due to the formation of the liquid phases.

主权项

1. A method for aligning two components and maintaining alignment during bonding, comprising the steps of:
a. fabricating single or plural arrays of patterned magnets forming a predetermined arrangement as well as electrical connections using wafer level processes at or near a bonding interface on a first component; b. fabricating single or plural arrays of mirrored patterned magnets forming a complementary arrangement matching said arrangement on said first component along with complementary electrical connections using wafer level processes at or near a bonding interface on a second component; c. doing a coarse alignment by matching said arrangement of said patterned magnets on said first component to said complementary arrangement of said patterned magnets on said second component after positioning said bonding interface on said first component facing to said bonding interface on said second component; d. applying a direction-predetermined external magnetic field with preset variation of the field strength to align magnetizations of said magnets on both said first component and said second component to ensure the complimentary north-pole facing south-pole for said magnets on said first component matching said mirrored magnets on said second component; e. keeping the said external magnetic field present while approaching said first component towards said second component, while the attractive or expulsive magnetic force between said magnet on said first component and said its said mirrored magnet on said second component forces the pair aligned together to facilitate wafer-to-component alignment between said first component and said second component; f. bonding said first component and said second component after aligning said components in close contact.