Meinrad Schienle

A fully electronic DNA sensor with 128 positions and in-pixel A/D conversion

A 16 /spl times/ 8 sensor array chip for fully electronic DNA detection is presented. The sensor principle is based on an electrochemical redox cycling process. The chip is fabricated on the basis of an extended 0.5 /spl mu/m CMOS process. Each sensor site of the array chip contains a complete A/D converter with a dynamic range of five decades. The 3/spl sigma/-homogeneity of the electrical response of the sensor array is better than 6% (10/sup -11/ A to 10/sup -7/ A) and better than 20% (10/sup -12/ A to 10/sup -7/ A). Proper operation of the chip is demonstrated with electrochemical and biological experiments.

Sensor arrays for fully-electronic DNA detection on CMOS

A 16×8 DNA sensor array chip with fully electronic readout is based on an extended CMOS process. Requirements concerning the integration of bio-compatible interface-, sensor- and transducer-materials into a standard-CMOS-environment and circuitry design issues are discussed.

Passive DNA Sensor with Gold Electrodes Fabricated in a CMOS Backend Process

A sensor for electrical detection of DNA is fabricated in a CMOS production line. A gold deposition process module is integrated in a CMOS backend process. The sensor principle is based on immobilization of singlestranded DNA probe molecules on an array consisting of interdigitated gold lines and subsequent hybridization with labeled target DNA strands. The electrical signal results from an electrochemical redox cycling process. Successful DNA detection experiments on the basis of such ‘passive’ chips are performed. This passive arrangement represents a test run for the extension of this principle to develop fully electronic DNA sensor arrays on active CMOS chips.

CMOS-Based Biosensor Arrays

CMOS-based sensor array chips provide new and attractive features as compared to todays standard tools for medical, diagnostic, and biotechnical applications. Examples for molecule- and cell-based approaches and related circuit design issues are discussed.

A CMOS Medium Density DNA Microarray with Electronic Readout

A CMOS chip-based approach is reviewed for fully electronic DNA detection. The electrochemical sensor principle used, CMOS integration of the required transducer materials, chip architecture and circuit design issues are discussed, respectively. Electrochemical and biological results obtained on the basis of medium density microarray sensor CMOS chips with 16 × 8 sensor sites prove proper operation.

Fully Electrical Microarrays

Publisher Summary This chapter discusses the principles and several exemplary applications of silicon-based electrical microarrays, showing the power of this emerging technology. The key feature of the fully electrical biochip technology is microarrays made in silicon technology. They carry several array positions with inter-digitated electrodes on its surface. The chips are fabricated using standard silicon manufacturing methods in industrial lines, allowing a high-volume production and minimizing the cost per chip. An example of design and layout of such a transducer interface is presented in the scheme of a low-density chip. The DNA arrays are based on the fixation of oligonucleotides on a solid support and can be made by different techniques. Density is a key element for the function and use of DNA arrays, and depending on the number of different capture sites, microarrays are classified as low-density or high-density arrays. The technical platform that offers optimal features for fully electrical DNA-microarrays, with up to 16 positions, freely designed for the particular application, is described. The ultra-microelectrode gold surface allows a coupling method with alkanethiol modified capture oligonucleotide sequences and leads to a highly specific biointerface for target recognition. The chips considered in this chapter consist of a passivated silicon substrate material and of the sensor elements at their surface. The active chips allow to amplify and process the weak sensor signals on-chip and to operate such chips with a low number of contact pads, independent of the numbers of test sites per chip. The chapter presents such active chips manufactured on the basis of a specifically extended Complementary-Metal-Oxide-Semiconductor (CMOS) process.

Improved SRAM failure diagnosis for process monitoring via current signature analysis

Abstract SRAMs are frequently used as monitor circuits for defect related yield, due to the ease of testing and the good correlation to the yield characteristics of logic circuitry. For the identification of the failure/fault type and the nature of the defect causing the failure, measured failbitmaps are mapped onto a failbitmap catalog obtained from defect-fault simulation. Often this mapping is not unique. A given failbitmap can be caused by several faults or defects. In this contribution, the application of current signature analysis is demonstrated for a stand-alone 16kx1 SRAM monitor circuit. It is found that the resolution of the failbitmap-fault-defect catalog can be improved considerably by additional current signature measurements. The interpretation of current measurements is based on simulation of the possible faults contained in the failbitmap catalog under the operating conditions in the current test. There was good agreement between the simulated and measured current values. With the aid of current measurements, more yield learning information is obtained from the process monitoring vehicle. In some cases, the shorted nodes inside a SRAM cell can be determined exactly. This eases the localization of the failure and is of practical importance for the sample preparation in physical failure analysis.