Control Circuitry for Self-Repairable MEMS Accelerometers

A BISR (Built-in Self-Repairable) MEMS comb accelerometer with modularized design has been previously reported. In this paper, the differential capacitance sensing circuitry for MEMS comb accelerometer is discussed. The BISR control circuitry based on CMOS transmission gates (TGs) is proposed. Each BISR module is connected to the capacitance sensing circuitry through a transmission gate. By turning on or off a transmission gate, the corresponding module can be either connected to or isolated from the capacitance sensing circuitry. In this way, the faulty module can be easily replaced with a good redundant module for self-repair. The parasitic model for the BISR control circuitry is also analyzed. The analysis results show that the parasitic capacitance will not affect the proper operation of the BISR control circuitry. Furthermore, the signal strength will not be degraded due to the insertion of analog multiplexers. The control circuitry can effectively isolate the faulty module of the BISR MEMS comb accelerometer. Both BISR and non-BISR MEMS accelerometer designs are suggested and their performances are also extracted for comparison

Reliability Analysis of Self-Repairable MEMS Accelerometer

© 2008 IEEE. Reprinted, with permission, from [Xiong, Xingguo; Wu, Yu-Liang; Jone, Wen-Ben, Reliability Analysis of Self-Repairable MEMS Accelerometer, IEEE International Joint Conferences on Computer, Information, and Systems Sciences, and Engineering, 12-2008. The final published version can be found at the link below.MEMS (Microelectromechanical System) yield and reliability have been a very critical issue. In our previous paper, we have proposed a self-repairable MEMS comb accelerometer device, and the yield analysis has demonstrated effective yield increase due to the BISR (built-in self-repair) design. In this paper, we developed a MEMS reliability model for quantitative assessment of the MEMS reliability analysis. Based on this model, we analyze the reliability of both non-BISR and BISR MEMS comb accelerometers under Z-axis shocking environment. Simulation results demonstrate very effective reliability enhancement due to the BISR design. The reliability model can also be applied to other MEMS devices under various failure mechanisms in a similar way.http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4030934&tag=

A Self-repairable MEMS Comb Accelerometer

The final publication is available at www.springerlink.comIn this paper, a built-in self-repair technique for the MEMS comb accelerometer device is proposed. The main device of the comb accelerometer consists of n identical modules, and m modules are introduced as the redundancy. If any of the working module in the main device is found faulty during a built-in self-test (BIST), the control circuit will replace it with a good redundant module. In this way, the faulty device can be self-repaired through redundancy. The implementation of dualmode BIST on the BISR module is discussed. The sensitivity loss due to device modularization can be well compensated by different design alternatives. The yield model for MEMS redundancy repair is developed. The simulation results show that the BISR (built-in self-repair) design leads to effective yield increase compared to non-BISR design, especially for a moderate non-BISR yield. The yield as well as the reliability of the accelerometer can be improved due to the redundancy repair.http://link.springer.com/chapter/10.1007%2F1-4020-5261-8_1

Reliability Model for MEMS Accelerometers

The final publication is available at www.springerlink.comMEMS (Microelectromechanical System) reliability is a very critical issue for its commercial applications. In order to measure the reliability of MEMS, a systematic reliability model is required. In this paper, we developed a MEMS reliability model for quantitative assessment of the MEMS reliability analysis. Based on this model, we analyze the reliability of both BISR (built-in-self-repairable) and non-BISR MEMS comb accelerometers under Z-axis shocking environment. Simulation results demonstrate very effective reliability enhancement due to the BISR design. The reliability model can also be applied to other MEMS devices under various failure mechanisms in a similar way.http://link.springer.com/chapter/10.1007%2F978-1-4020-8737-0_4

MEMS Yield Simulation with Monte Carlo Method

The final publication is available at www.springerlink.comIn this paper, Monte Carlo method is used for the simulation of point-stiction defects in MEMS accelerometer devices. The yield of MEMS devices is estimated based on the simulation results. Comparison between simulated yields of BISR/non-BISR MEMS accelerometers demonstrates effective yield increase due to self-repairable design. The simulation results of yield increase versus different initial yields for BISR MEMS accelerometers are in good agreement with theoretical prediction based on previous MEMS yield model. This verifies the correctness of the MEMS yield model.http://link.springer.com/chapter/10.1007%2F978-1-4020-6266-7_9

Material Fatigue And Reliability Of Mems Accelerometers

MEMS (Microelectromechanical System) reliability has been a very important issue, especially for safety critical applications. Due to the diversity and multiple energy domains involved, MEMS devices are vulnerable to various failure mechanisms. MEMS reliability under different failure mechanisms should be analyzed separately. Since most of MEMS devices contain movable parts, material fatigue and aging under long-term repeated cycling load may lead to potential device failure, which in turn degrades the device reliability. In this paper, the reliability of poly-silicon MEMS comb accelerometers under material fatigue failure mechanism is analyzed. Based on ANSYS stress simulation, the mean-time-to-failure (MTTF) lifetimes and failure rates for both BISR (built-in self-repairable) and non-BISR poly-silicon MEMS comb accelerometers are derived. Simulation results show that the fatigue lifetime of MEMS accelerometers made by poly-silicon material can be good enough for general purpose applications. However, for some 'weak' devices with certain structure defects, the material fatigue and aging may become potential threats. Compared to non-BISR design, BISR MEMS accelerometer demonstrates effective reliability improvement due to redundancy repair. MEMS reliability under material fatigue for other MEMS materials will be further studied in the future.http://ieeexplore.ieee.org.libproxy.bridgeport.edu/stamp/stamp.jsp?tp=&arnumber=4641187&tag=

Yield Analysis for Self-Repairable MEMS Devices

In this paper, the yield analysis for a selfrepairable MEMS (SRMEMS) accelerometer design is proposed. The accelerometer consists of(n+m) identical modules: n of them serve as the main device, while the remaining m modules act as the redundancy. The yield model for MEMS redundancy repair is developed by statistical analysis. Based upon the yield model, the yield increase after redundancy repair for the SRMEMS accelerometer is derived. The yield increase versus initial yield for different m numbers is simulated. The simulation results show that the SRMEMS leads to effective yield increase compared to non-BISRS design, especially for a moderate initial yield.http://ieeexplore.ieee.org.libproxy.bridgeport.edu:9000/stamp/stamp.jsp?tp=&arnumber=159411

Design And Analysis Of Self-Repairable MEMS Accelerometer

In this paper, a self-repairable MEMS (SRMEMS) accelerometer design is proposed. The accelerometer consists of (n+m) identical modules: n of them serve as the main device, while the remaining m modules act as the redundancy. If any of the working module in the main device is found faulty, the control circuit will replace it with a good redundant module. In this way, the faulty device can be self-repaired through redundancy. The sensitivity loss due to device modularization can be well compensated by different design alternatives. The yield model for MEMS redundancy repair is developed. The simulation results show that the BISR (built-in self-repair) design leads to effective yield increase compared to non-BISR design, especially for a moderate non-BISR yield. By implementing the fault tolerance feature into MEMS devices, the yield as well as the reliability of a MEMS device implemented in a SoC can be improved.http://ieeexplore.ieee.org.libproxy.bridgeport.edu/stamp/stamp.jsp?tp=&arnumber=1544500&tag=