Sealing of MEMS Atomic Vapor Cells Using Cu-Cu Thermocompression Bonding

Rigorous theory of thin-vapor-layer linear optical properties: The case of specular reflection of atoms colliding with the walls

“…Taking into account the symmetry relations of the even and odd fields and their derivatives at the boundaries below we write down the exact solution of the set of Eqs. (31) with respect to r and t calculated up to the prescribed n-th order of PT in atomic number density…”

“…Brand new prospects appeared after the theoretical prediction of the possibility to enhance the optical response of a resonant vapor spatially confined between two dielectric media in a layer with a thickness of the order of the incident wavelength [21,22] and practical implementation of miniature vapor cells containing vapors of alkali metals [2]. The works cited subsequently gave a rise to several remarkable studies of the Paschen-Back and related effects on the hyperfine structure of alkali metals [23][24][25][26]; atom-surface interactions at nanoscale [3,27,28]; interactions of the resonant atomic ensemble with the plasmonic structures [29,30] and other applications [4,5,31,32]. Nevertheless, the underlying theoretical model [21] had such drawbacks as the exclusion of light reflection from the rear gas-dielectric interface and the limitation by the first order of the perturbation theory (PT) in vapor density.…”

Wafer-Level Filling of MEMS Vapor Cells Based on Chemical Reaction and Evaporation

“…BaCl 2 and the residual chemical precursors remain in the chamber, which obscures the interrogation laser [13]. In order to solve this issue, double-chamber MEMS vapor cells have been presented [13,[17][18][19][20][21]. The laser passes through a dedicated interrogation chamber.…”

“…The second group is about the sealing technologies of MEMS vapor cells, such as anodic bonding [10,19], Cu-Cu thermocompression bonding [21], and low-temperature indium bonding [23,24]. Anodic bonding, also known as electrostatic bonding or fieldassisted bonding, is almost solely applied to the bonding of silicon to Pyrex glass [25].…”

“…However, the presence of copper adds thermal magnetic noise in the MEMS vapor cell. Additionally, it is more sensitive to dust contamination than anodic bonding [21]. Based on low-temperature indium bonding, MEMS vapor cells can be fabricated under a temperature as low as 140 • C. However, the process is far more complex, and it uses anodic bonding as well [23,24].…”