Aerospace Sensor Component and Subsystem Investigation and Innovation-2 Component Exploration and Development (ASCSII-2 CED) Delivery Order 0003: Hermetically Sealed Cavities in 3-D GaAs-Silicon and Silicon-Silicon Packages for Microelectromechanical System (MEMS) Devices Using Selective and Large-Scale Bonding
Abstract
Chip-scale bonding of GaAs-to-silicon and silicon-to-silicon to produce cavities for 3-D assembly of MEMS devices has been demonstrated using SnAgCu and eutectic SnPb solders. Laser and furnace reflow were used for region-selective and fast bonding of the chips, respectively, for 3-D assembly. For example, for GaAs-to-silicon bonding, lines of solder paste, 150 mm in width, were screen-printed onto silicon wafers to form square-shaped sealing rings as small as 2 by 2 mm. The solder line width was optimized to provide the smallest width, yet sufficient to ensure a hermetic seal. The solder was reflowed, and the wafer was diced into individual chips of various die sizes. The chips were then flipped onto gold-coated GaAs chips and again placed in the reflow oven at a temperature of up to 250 deg C for a total reflow time of 7 minutes. The bonded chips were then tested for hermeticity using MIL-STD-883E and by examining the sealed area after the separation of the chips using a pull test. For the case of selectively laser-bonded silicon-to-silicon chips, the structures exhibited excellent hermetic it and adhesion stren th with a uniform microcavity and uniform reflow of the solder.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2003
- Accession Number
- ADA420804
Entities
People
- Ajay P. Malshe