Pd-Ge-Au Ohmic Contacts to GaAs: Reliability and Failure Analysis

1990 ◽  
Vol 184 ◽  
Author(s):  
T. E. Kazior ◽  
H. Hieslmair ◽  
R. C. Brooks

ABSTRACTWe report on experiments that were performed to evaluate the temperature stability and long term reliability of non-alloyed Pd-Ge-Au ohmic contacts on N-type GaAs. Low resistance contacts (≈1×10−6 Ωcm2) were obtained for samples that were sintered in a conventional furnace or flash sintered in a graphite susceptor. Elevated temperature storage (≈4000 hours at 280°C) showed improved contact stability when compared to Ni-AuGe-Ni-Au control samples. Gateless MESFETs subjected to bias temperature stress measurements (Ids ≈300–350mA/mm, 2000–4000 hours at 200°C) showed no significant change in device current. This result is in contrast to devices with Ni-AuGe-Ni-Au ohmic contacts which exhibited a 6–27% decrease in current under the same test conditions. Failure analysis reveals significant electromigration and Au diffusion in the drain fingers of devices with Ni-AuGe-Ni-Au contacts. In contrast, devices with Pd-Ge-Au contacts show no elect romigration or Au diffusion in the GaAs.

1990 ◽  
Vol 181 ◽  
Author(s):  
T. E. Kazior ◽  
H. Hieslmair ◽  
R. C. Brooks

ABSTRACTWe report on experiments that were performed to evaluate the temperature stability and long term reliability of non-alloyed Pd-Ge-Au ohmic contacts on N-type GaAs. Low resistance contacts (≈1×10−6Ωcm2) were obtained for samples that were sintered in a conventional furnace or flash sintered in a graphite susceptor. Elevated temperature storage (≈4000 hours at 280°C) showed improved contact stability when compared to Ni-AuGe-Ni-Au control samples. Gateless MESFETs subjected to bias temperature stress measurements (Ids ≈300-350mA/mm, 2000–4000 hours at 200°C) showed no significant change in device current. This result is in contrast to devices with Ni-AuGe-Ni-Au ohmic contacts which exhibited a 6–27% decrease in current under the same test conditions. Failure analysis reveals significant electromigration and Au diffusion in the drain fingers of devices with Ni-AuGe-Ni-Au contacts. In contrast, devices with Pd-Ge-Au contacts show no electromigration or Au diffusion in the GaAs.


Author(s):  
Chuan Zhang ◽  
Yinzhe Ma ◽  
Gregory Dabney ◽  
Oh Chong Khiam ◽  
Esther P.Y. Chen

Abstract Soft failures are among the most challenging yield detractors. They typically show test parameter sensitive characteristics, which would pass under certain test conditions but fail under other conditions. Conductive-atomic force microscopy (CAFM) emerged as an ideal solution for soft failure analysis that can balance the time and thoroughness. By inserting CAFM into the soft failure analysis flow, success rate of such type of analysis can be significantly enhanced. In this paper, a logic chain soft failure and a SRAM local bitline soft failure are used as examples to illustrate how this failure analysis methodology provides a powerful and efficient solution for soft failure analysis.


1998 ◽  
Vol 13 (3) ◽  
pp. 138-144 ◽  
Author(s):  
Joachim Raupp

AbstractOn the basis of investigations with samples from a fertilization trial started in 1980, some parameters of food storage ability are evaluated. Microbial infestation of the product during incubation seems to be the most reliable parameter, but the circumstances of infestation and the optimal test conditions are unknown. There are no reliable correlations among the results of degradation tests, storage tests under optimal conditions, and chemical contents of the product. The concept of product vitality (a product-oriented quality referring to a product full of vigor) is based on results of degradation tests. Ultimately, however, food quality standards are based on human priorities (human-oriented). Therefore, not only product characteristics, but also social, psychological, and environmental criteria should be considered.


2019 ◽  
Vol 3 (1) ◽  
pp. 70-83
Author(s):  
Wei Wei Liu ◽  
Berdy Weng ◽  
Scott Chen

Purpose The Kirkendall void had been a well-known issue for long-term reliability of semiconductor interconnects; while even the KVs exist at the interfaces of Cu and Sn, it may still be able to pass the condition of unbias long-term reliability testing, especially for 2,000 cycles of temperature cycling test and 2,000 h of high temperature storage. A large number of KVs were observed after 200 cycles of temperature cycling test at the intermetallic Cu3Sn layer which locate between the intermetallic Cu6Sn5 and Cu layers. These kinds of voids will grow proportional with the aging time at the initial stage. This paper aims to compare various IMC thickness as a function of stress test, the Cu3Sn and Cu6Sn5 do affected seriously by heat, but Ni3Sn4 is not affected by heat or moisture. Design/methodology/approach The package is the design in the flip chip-chip scale package with bumping process and assembly. The package was put in reliability stress test that followed AEC-Q100 automotive criteria and recorded the IMC growing morphology. Findings The Cu6Sn5 intermetallic compound is the most sensitive to continuous heat which grows from 3 to 10 µm at high temperature storage 2,000 h testing, and the second is Cu3Sn IMC. Cu6Sn5 IMC will convert to Cu3Sn IMC at initial stage, and then Kirkendall void will be found at the interface of Cu and Cu3Sn IMC, which has quality concerning issue if the void’s density grows up. The first phase to form and grow into observable thickness for Ni and lead-free interface is Ni3Sn4 IMC, and the thickness has little relationship to the environmental stress, as no IMC thickness variation between TCT, uHAST and HTSL stress test. The more the Sn exists, the thicker Ni3Sn4 IMC will be derived from this experimental finding compare the Cu/Ni/SnAg cell and Ni/SnAg cell. Research limitations/implications The research found that FCCSP can pass automotive criteria that follow AEC-Q100, which give the confidence for upgrading the package type with higher efficiency and complexities of the pin design. Practical implications This result will impact to the future automotive package, how to choose the best package methodology and what is the way to do the package. The authors can understand the tolerance for the kind of flip chip package, and the bump structure is then applied for high-end technology. Originality/value The overall three kinds of bump structures, Cu/Ni/SnAg, Cu/SnAg and Ni/SnAg, were taken into consideration, and the IMC growing morphology had been recorded. Also, the IMC had changed during the environmental stress, and KV formation was reserved.


Author(s):  
R.I. Korsnes ◽  
U. Zimmermann ◽  
M.V. Madland ◽  
S.A.R. Bertolino ◽  
T. Hildebrand-Habel ◽  
...  
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2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Sun Min ◽  
Yufeng Bi ◽  
Mulian Zheng ◽  
Sai Chen ◽  
Jingjing Li

The energy consumption and greenhouse gas emission of asphalt pavement have become a very serious global problem. The high-temperature stability and durability of polyurethane (PU) are very good. It is studied as an alternative binder for asphalt recently. However, the strength-forming mechanism and the mixture structure of the PU mixture are different from the asphalt mixture. This work explored the design and performance evaluation of the PU mixture. The PU content of mixtures was determined by the creep slope (K), tensile strength ratios (TSR), immersion Cantabro loss (ICL), and the volume of air voids (VV) to ensure better water stability. The high- and low-temperature stability, water stability, dynamic mechanical property, and sustainability of the PU mixture were evaluated and compared with those of the stone matrix asphalt mixture (SMA). The test results showed that the dynamic stability and bending strain of the PU mixture were about 7.5 and 2.3 times of SMA. The adhesion level of PU and the basalt aggregate was one level greater than the limestone, and basalt aggregates were proposed to use in the PU mixture to improve water stability. Although the initial TSR and ICL of PU mixture were lower, the long-term values were higher; the PUM had better long-term water damage resistance. The dynamic modulus and phase angles (φ) of the PU mixture were much higher. The energy consumption and CO2 emission of the PU mixture were lower than those of SMA. Therefore, the cold-mixed PU mixture is a sustainable material with excellent performance and can be used as a substitute for asphalt mixture.


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