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Reliability Issues. Mohammad Sharifkhani. Reading. Textbook I Chapter 18 Textbook I Chapter 20 The paper on SER. Motivation. There is a long distance from a chip working in a lab to a chip working in the field Reliability Robustness Fatigue
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Reliability Issues Mohammad Sharifkhani
Reading • Textbook I Chapter 18 • Textbook I Chapter 20 • The paper on SER
Motivation • There is a long distance from a chip working in a lab to a chip working in the field • Reliability • Robustness • Fatigue • Many of the culprits are in rise as technology scales
Introduction • Packaging • Electromigration • ESD Protection • SER Protection
Chip Packaging • Bond wires (~25m) are used to connect the package to the chip • Pads are arranged in a frame around the chip • Pads are relatively large (~100m in 0.25m technology),with large pitch (100m) • Many chips areas are ‘pad limited’
Pad Frame Layout Die Photo
Chip Packaging • An alternative is ‘flip-chip’: • Pads are distributed around the chip • The soldering balls are placed on pads • The chip is ‘flipped’ onto the package • Can have many more pads
V DD V DD En Out En En Out In In En Increased output drive Out = In.En + Z.En Tristate Buffers
Electromigration • Current density (current per unit area) • A reliability issue creates problem over time • Due to transport of metal ions • AC signals will be fine • Breaking or shorting to adjacent wire • Keeping current below 0.5 to 1mA/um relaxes the problem • For DC wires (power/GND) • IR Drop transient problem (peak current) • Electromigration DC problem (ave. current) • Using copper helps
Electro-Static Discharge (ESD) Which one fails?
Electro-Static Discharge (ESD) Second breakdown of the path at a higher voltage level than the second break- down of the ESD path Second breakdown of the path at a lower voltage than the second break- down of the ESD path
Electro-Static Discharge (ESD) There are challenges as technology scales!
Electro-Static Discharge (ESD) Design of ESD protection circuits: A glimpse!
Electro-Static Discharge (ESD) • ESD protection is extremely important when dealing with high speed input output signals • I/O Capacitance