Issues on short circuits in large on-chip power MOS-transistors using a modified checkerboard test structure

Hess, Christopher P.; Weiland, L.H.; Bornefeld, Ralf

doi:10.1109/icmts.1997.589365

Cited by 3 publications

(1 citation statement)

References 5 publications

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“…[2]- [4]. Furthermore, sensors for defects of the on-chip metallization were presented in [5]- [7]. But none of these approaches was shown to be suitable for on-chip metallization failure caused by cyclic thermo-mechanical stress.…”

Section: Introductionmentioning

confidence: 98%

On-Chip Sensors to Detect Impending Metallization Failure of LDMOS Transistors Under Repetitive Thermo-Mechanical Stress

Ritter

Pham

Pfost

2016

IEEE Trans. Semicond. Manufact.

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In many automotive applications, repetitive selfheating is the most critical operation condition for LDMOS transistors in smart power ICs. This is attributed to thermomechanical stress in the on-chip metallization, which results from the different thermal expansion coefficients of the metal and the intermetal dielectric. After many cycles, the accumulated strain in the metallization can lead to short circuits, thus limiting the lifetime.Increasing the LDMOS size can help to lower peak temperatures and therefore to reduce the stress. The downside of this is a higher cost. Hence, it has been suggested to use resilient systems that monitor the LDMOS metallization and lower the stress once a certain level of degradation is reached. Then, lifetime requirements can be fulfilled without oversizing LDMOS transistors, even though a certain performance loss has to be accepted.For such systems, suitable sensors for metal degradation are required. This work proposes a floating metal line embedded in the LDMOS metallization. The suitability of this approach has been investigated experimentally by test structures and shown to be a promising candidate. The obtained results will be explained by means of numerical thermo-mechanical simulations.Index Terms-LDMOS transistor, thermo-mechanical stress, metallization failure, metal meander, leakage path forming, meander resistance change, early warning sensor.

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