05-09-2012, 11:33 AM
Digital Micromirror Device
Digital Micromirror.ppt (Size: 605.5 KB / Downloads: 87)
Applications
Mainly projection systems (Digital Light Processing)
Other emerging applications such as 3D metrology, confocal microscopy,digital TV
Hinge fatigue
Fatigue: slow growth of a crack driven by repeated plastic deformation
Mirror in normal operating mode switches every 200 microseconds
5 years use with 1000 operating hours a year mirrors switch 90x109 times
First approach: anaylsis using bulk properties of the hinge material showed that fatigue would be a big problem
However… accelerated tests proved that wrong, samples easily exceeding 100x109 switches showing no fatigue.
Explanation: hinge so thin governed by thin film properties!
Hinge memory
Most significant mode of failure
Occurs when a mirror operates in the same direction for a long period of time
Main factors are the duty cycle and the operating temperature
Duty cycle: percentage of time a mirror is addressed to one side.(95/5)
Temperature is the dominant factor for hinge memory lifetime
Stiction
Induced by an excessive adhesive force between the landing tip and its landing site
Adhesive forces can be induced by:
Surface contamination
Capillary condensation
CMOS defects
Van der Walls forces
Reliability testing can be done to measure the distribution of surface adhesion across the device to determine the number of operating devices under different switching voltages
Environment robustness
Based on standard semiconductor tests requirement
Capillarity force
Humidity everywhere
UV light exposure
Thermal testing
Surface contamination
During production process
Size vs Robustness
Small size enable robustness to mechanical shocks
Lowest resonant frequency in KHz
Test :1500G and 20G in vibration with no mirror breaking
Weaknesses on the package identified and annihilated
Summary of DMD reliability
Hinge memory lifetime
>100’000 hours at normal operating conditions
Random defects
>650’000 hours MTBF (<1500 FIT)
Hinge fatigue lifetime
>3.67 trillion cycle or >250’000 hours
Environmentally robust
Conclusion
Misleading apparence
Experience plan must be done to find critical failure modes
Concern to reliability
The reliability of the DMD has been exemplary and should be considered as a reference for development of other MEMS
Digital Micromirror.ppt (Size: 605.5 KB / Downloads: 87)
Applications
Mainly projection systems (Digital Light Processing)
Other emerging applications such as 3D metrology, confocal microscopy,digital TV
Hinge fatigue
Fatigue: slow growth of a crack driven by repeated plastic deformation
Mirror in normal operating mode switches every 200 microseconds
5 years use with 1000 operating hours a year mirrors switch 90x109 times
First approach: anaylsis using bulk properties of the hinge material showed that fatigue would be a big problem
However… accelerated tests proved that wrong, samples easily exceeding 100x109 switches showing no fatigue.
Explanation: hinge so thin governed by thin film properties!
Hinge memory
Most significant mode of failure
Occurs when a mirror operates in the same direction for a long period of time
Main factors are the duty cycle and the operating temperature
Duty cycle: percentage of time a mirror is addressed to one side.(95/5)
Temperature is the dominant factor for hinge memory lifetime
Stiction
Induced by an excessive adhesive force between the landing tip and its landing site
Adhesive forces can be induced by:
Surface contamination
Capillary condensation
CMOS defects
Van der Walls forces
Reliability testing can be done to measure the distribution of surface adhesion across the device to determine the number of operating devices under different switching voltages
Environment robustness
Based on standard semiconductor tests requirement
Capillarity force
Humidity everywhere
UV light exposure
Thermal testing
Surface contamination
During production process
Size vs Robustness
Small size enable robustness to mechanical shocks
Lowest resonant frequency in KHz
Test :1500G and 20G in vibration with no mirror breaking
Weaknesses on the package identified and annihilated
Summary of DMD reliability
Hinge memory lifetime
>100’000 hours at normal operating conditions
Random defects
>650’000 hours MTBF (<1500 FIT)
Hinge fatigue lifetime
>3.67 trillion cycle or >250’000 hours
Environmentally robust
Conclusion
Misleading apparence
Experience plan must be done to find critical failure modes
Concern to reliability
The reliability of the DMD has been exemplary and should be considered as a reference for development of other MEMS