Facility & Processes Research On The Fabrication Of Atomic Clock Alkali Vapor Cell

Atomic clock is an accurate timekeeping device based on the hyperfine energy transitions of atoms. These transitions could generate very-steady frequency, and then are used in the circuit as oscillators. Atomic clock would be developed much smaller based on the CPT (Coherent Population Trapping) theory. Therefore, the core-chip (alkali vapor cell) of atomic clock would be the key to the development of small atomic clock.To fabricate the alkali vapor cell, the hermetic packaging method, in particular the anodic bonding technology, for MEMS (Micro-Electro-Mechanical System) technology was introduced. Anodic bonding is the method used here for cell's fabrication, and the whole technical processes about the cell were established. On the basis of processes and requirements of anodic bonding, an anodic bonding facility on the vacuum-obtained equipment was designed and manufactured. This can be specially used for the cell-making and bonding experiment under different pressure levels which can be from high vacuum to two or three atm. The new type floating chuck and work plantform could satisfy the needs for the bonding. Rb is used in the experiments; the Rb vapor cell's processes have been researched. Silicon-hole was made by wet etching or ultrasonic hole making technologies. The Rb's effect on the anodic bonding was presented. The temperature, voltage, air pressure were also analyzed about the cell's manufacturing. The Rb vapor cell based on the third dimension bonding was made. The cell's effect and absorbtion were tested, and these indicated the Rb does exist in the cell. The third dimension bonding was studied and the Na or sodium compounds from the Pyrex glass to the glass/silicon interface were discovered. The Rb cell's has proven the facility and the processes of cell's fabrication. These tools and methods can be used to fabricate the Cs cell, and these could satisfy the needs of atomic clock alkali vapor cell. At last future works on the alkali vapor cell's fabrication were projected.