In Situ Thermal Aging Calibration Corrections for High Temperature MEMS Transducer Arrays
Dynamic matrix corrections combine in situ reference tracking and Arrhenius modeling to eliminate unbudgeted high temperature MEMS recalibration cycles.
Titanium Tungsten Barrier
Metallurgical Layer
A thin-film metallic layer is deposited between the silicon substrate and the metal interconnects to prevent interdiffusion and electromigration. The titanium tungsten barrier consists of an alloy that combines the high adhesion of titanium with the diffusion resistance of tungsten. This layer is crucial in sensor fabrication to protect active areas from aluminum or copper contamination.
It ensures the electrical and mechanical stability of the contact points.
Functional Application
Deposition of this protective film is typically achieved through physical vapor deposition or sputtering in a vacuum chamber. During subsequent high-temperature annealing steps, the titanium tungsten barrier prevents the formation of metal silicides that would otherwise degrade the electrical contacts. The specific alloy ratio, usually ten percent titanium and ninety percent tungsten, is optimized to balance adhesion and barrier performance.
This layer also acts as an etching stop during the patterning of subsequent metal layers. This dual function simplifies the manufacturing process of the sensor chip. If this barrier layer is too thin, localized diffusion can occur, leading to high contact resistance and early failure of the sensor circuit.
Adhesion Property
The titanium component provides high bonding strength to both silicon dioxide and silicon nitride surfaces. This mechanical integrity prevents delamination of the titanium tungsten barrier during thermal cycling.
Thickness Measurement
X-ray fluorescence or spectroscopic ellipsometry verifies the thickness of the deposited alloy during wafer manufacturing. This quality control step ensures the titanium tungsten barrier will perform reliably.