Characterizing stress in ultrathin silicon wafers

The aim of this letter is to calculate the mechanical grinding induced bow and stress in ultrathin silicon wafers. The reverse leakage current of a p-n junction diode fabricated on a 4 in. silicon wafer was measured for wafers thinned to various thicknesses. A correlation with the residual stress was obtained through band gap narrowing effect. The analytical results were compared with experimental bow measurements using a laser profiler. The bow in 50 mu m thick wafer was found to be less than 2 mm using the current grinding process. (c) 2006 American Institute of Physics. (DOI:10.1063/1.2336212

Integrated motor drives: state of the art and future trends

With increased need for high power density, high efficiency and high temperature capabilities in Aerospace and Automotive applications, Integrated Motor Drives (IMD) offers a potential solution. However, close physical integration of the converter and the machine may also lead to an increase in components temperature. This requires careful mechanical, structural and thermal analysis; and design of the IMD system. This paper reviews existing IMD technologies and their thermal effects on the IMD system. The effects of the power electronics (PE) position on the IMD system and its respective thermal management concepts are also investigated. The challenges faced in designing and manufacturing of an IMD along with the mechanical and structural impacts of close physical integration is also discussed and potential solutions are provided. Potential converter topologies for an IMD like the Matrix converter, 2-level Bridge, 3-level NPC and Multiphase full bridge converters are also reviewed. Wide band gap devices like SiC and GaN and their packaging in power modules for IMDs are also discussed. Power modules components and packaging technologies are also presented

Electrochemical sensor with dry reagents implemented in lab-on-chip for single nucleotide polymorphism detection

We developed an electrochemical (EC) sensor having dry reagents to detect pyrophosphoric acid (PPi) produced as a by-product of a polymerasechain- reaction (PCR) amplicon for single nucleotide polymorphism (SNP) detection. The EC sensor is implementable in a lab-on-chip (LoC) system, and a sensor chip having side-wall electrical connections that enable electrical contacts from the top of the LoC has been developed. We also developed separated on-chip placement of dry reagents divided into three groups in a sensor cavity to suppress background current when there is no PPi. Using this chip, we successfully demonstrated SNP detection in the ABO gene from human blood samples, in combination with the allele-specific PCR amplification method using our developed LoC systemstatus: publishe

Full-wafer in-situ fabrication and packaging of microfluidic flow cytometer with photo-patternable adhesive polymers

Integration of microelectronics with microfluidics enables sophisticated lab-on-a-chip devices for sensing and actuation. In this paper, we investigate a novel method for in-situ microfluidics fabrication and packaging on wafer level. Two novel photo-patternable adhesive polymers were tested and compared, PA-S500H and DXL-009. The microfluidics fabrication method employs photo lithographical patterning of spin coated polymer films of PA or DXL and direct bonding of formed microfluidics to a top glass cover using die-to-wafer level bonding. These new adhesive materials remove the need for additional gluing layers. With this approach, we fabricated disposable microfluidic flow cytometers and evaluated the performance of those materials in the context of this application. DXL-009 exhibits lower autofluorescence compared to PA-S500H which improves detection sensitivity of fluorescently stained cells. Results obtained from the cytotoxicity test reveals that both materials are biocompatible. The functionality of these materials was demonstrated by detection of immunostained monocytes in microfluidic flow cytometers. The flexible, fully CMOS compatible fabrication process of these photo-patternable adhesive materials will simplify prototyping and mass manufacturing of sophisticated microfluidic devices with integrated microelectronics.status: publishe