Prof. Glenn H. Chapman Research Topics

Area of Research and Accomplishments

My main area of research has centered on 8 main areas:
Microelectronics Large Area/Wafer Scale Integration, 
Defect avoidance techniques, 
VLSI design (see also Laser/Optical Applications)
Micromachining Microsensors & transducers
MicroElecto-Optical Mechanical Devices
Laser/Optical/Sensor Applications Laser micromachining, & Laser microsurgery, 
Active Pixel Sensor Sensor Imagers
Hyperspectral Sensor Systems
Biomedical Sensors Laser Micromachined Biomedical Sensors
Space Applications Orbital Microfabrictation, 
Space based Microsensors
Microfabrication Development of  Inorganic Photoresists
Embedded Microprocessor Systems Computer Anti-theft technology
Internet Anti-theft Hardware/Software interaction with the Internet
Much of my research has also been done in cooperation with industry which has resulted in my graduate students obtaining related industrial positions after graduation. I am starting to install PDF versions are available of most papers describing the research work in more detail
This work is the creation of Large Area Restructurable Silicon System (LARSS) which involve arrays of both integrated circuits and transducers. This work aims at the creation of new silicon systems that can readily be expanded to areas and complexities much larger than current integrated circuit fabrication limits. To increase circuit area to the wafer scale level, 10-200 times the current IC area, requires defect avoidance technologies bypass IC fabrication errors and hook together working sections to create large systems. The technique divides the system into redundant circuit blocks surrounded by a grid of metal signal/clock/power bus lines to which the devices can be connected. In all cases the designs use standard IC fabrication services (eg. Canadian Microelectronics Corp.) to manufacture the devices, but applies post fabrication processing to achieve the unique systems. One interconnecting technique which makes permanent signal routing uses a laser linking system developed by the applicant at M.I.T. Lincoln Laboratory and currently applied at Simon Fraser University. It consists of two separated dopant lines in the silicon substrate which are connected to the bus lines (like a gateless transistor). An external laser melts the gap area causing the dopant lines to connect with a resistance of typically 60 ohms. The laser can also cut metal lines, thus segmenting the signal buses.
Wafer Scale Integrated 16 point FFT 
From M.I.T Lincoln Lab
Laser linking by G. Chapman, 
design by M. Rhodes

In terms of work here my students and I have built a major unique piece of experimental equipment. This is a laser interconnection table which will focus a controlled laser beam on integrated circuits with a 0.1 micron position repeatability. This is one of only five such systems in the world, two at M.I.T. Lincoln Lab, plus one each at the University of South Florida and the US National Security Agency. I have played a major part in the creation of all such systems, and feel this is the best designed so far. The value of this equipment is demonstrated by the interest in using the laser table shown in the Industrial Cooperation section.

Due to the expensive nature of building true wafer scale systems my work has concentrated on studying techniques for building large area systems and the design of new classes wafer scale type devices. At the VLSI design level this has resulted in building circuits to compare the area and speed tradeoffs for defect avoidance of laser connections and active devices, which has lead to the design of circuits combining both for optimum operation. My research has proposed and tested a new type of large area product: the Wafer Scale Field Programmable Gate Array which could increase the density of current FPGA systems by 10-100 times. Another new concept was LARSS systems containing both transducers (some micromachined), control circuitry and the laser redundancy network needed to build in large areas. First proposed in one of my papers, the idea here is to build large transducer arrays using separate types of redundancy layouts for both the transducers and the circuitry. One such systems is a large area magnetic field sensor array designed for mapping magnetic field distributions being undertaken by my PhD student Yves Audet. Another array was a design for a wafer scale array of thermal emission elements. In this transducer matrixes the laser redundancy scheme changes the design from something that can be used only in small chip sized structures (say 10x10 arrays) to very large devices possibly of 256 x 256, which makes it of considerable interest to several organizations.
Click here for papers on WSI projects
Currently this wafer scale work has concentrated on the development of large area optical sensors.  (see Lasers/Optical/Sensor Applications)

Laser/Optical/Sensor Applications

Optical sensors arrays (eg. Digital camera) are becoming more common and are now being considered for many Systems on a Chip devices integrating sensors and processing elements. With the size of the CMOS Active Pixel Sensor (APS) array implemented in such chips increasing to 2048x1024 and beyond, the possibility of degradation in the reliability of the chip over time must be a factor in the chip design, espcially in harsh environments. In digital circuits, a commonly used technique for reliability or yield enhancement is the incorporation of redundancy (e.g., adding redundant rows and columns in large memory ICs). Very limited attempts have been directed towards fault-tolerance in analog circuits, mainly due to the very high level of irregularity in their design. Since active pixel arrays have a regular structure, they are amenable to reliability enhancement through a limited amount of added redundancy. The purpose of this research is to investigate the advantages of incorporating some fault-tolerance methods, including redundancy, into the design of an active pixel sensor array. An Active Pixel Sensors self-correcting for most common faults has created which will significantly incease sensor array yields.  When combined with newly developed software correction techiques this creates imaging systems that are highly resistant to defects created either at fabrication time or during operations under harsh conditions. A new area is the creation of Active Pixel Sensors which are enhanced for specifical optical detection requirements and the building of Hyperspectral sensors which combine selected wavelength range APS' and other sensors to create many wavelength range detection systems.
Click here for papers on the Active Pixel Sensor project

Laser micromachining is used to create unique devices not possible with current etching technology. The most import work here is a vision/proximity sensor called "Vision Skin" developed by myself and my grad students for the Canadian Space Agency. Vision Skin gives both gives a low resolution image of the an approaching object and measures the distance to it with precision 100 micron precision. This patented device has been licensed by the Canadian Space Agency and Kinetic Sciences Inc. Click here for papers on the Vision Skin  project   This is part of the Angular Domain Imaging work (see the Biomedical Sensor section)

In addtion to the laser links a Laser Microsurgery on Integrated Circuits service for Canadian Microelectronic Corp. members has been offered using my laser table during the past four years. Removing defects occurring in chip designs has been done for researchers directed to this laboratory by CMC. Specifications for this service is maintained by CMC on their web site. The most important and successful project consisted of a nearly 8 months project with McGill's Electronic department. A very large IC, consisting of about 40% of the area of a CMC 1.2 micron fabrication run, contained several design defects which made them totally inoperable. The size of the chip meant that it would be very expensive to refabricate. In a series of experiments involving the exchange of 5 sets of chips the problems were identified by successive cut and test cycles. The final work produced fully operable devices, enabling the student to obtain his thesis. Several local companies have used this laser microsurgery to analyze problems with their chips and reduce the design cycle.


The area of true micromachining we are working on the development of sevearl new sensors. As noted above micromachining and transducers is playing a significant role in the many of the large area systems that are currently the research of myself and my graduate students. In addition to classic etching micromachining I have in particular been looking at Laser Micromachining which uses laser beams to create structures in the 50 micron and below size. My micromachining developments has concentrated on two areas. First was the development a new micromachined vacuum sensor that has been the subject of a MSc and BSc thesis by students, and is expandable into creating very sensitive flow sensors. The second involves developing advanced X-ray detectors with micromachined sensor electrodes. Included in this is several new characterization techniques we have developed.
 Click here for papers on the micromaching  project

Laser Micromachined Biomedical Sensors

Light can penetrate quite deeply into tissue but much of it becomes heavily scattered. To illustrate this effect place a flash light behind your hands in the dark and see the resulting red glow which penetrates, but the very poor definition of the bones within the hand. The key to successful optical imaging is the separation of the slightly scattered light, which carries information about the structure of the tissue through which it passes, from the scattered component that is Billions of times greater. We have build micromachined optical devices (Silicon Micromachined Collimator Array) that are already seeing though the equilivant of 10 mm of tissue. It uses a new method called Angular Domain Imaging. Where would this be used? Since light does not damage tissue like X-rays do it can be used to replace X-ray screening in such areas as mammograms, brain scans etc. Indeed light has the advantage that cancerous tissue can be directly identified optically, if we can make the system sensitive enough. Click here for papers on the Angular Domain Imaging projects

A unique UV laser micromachining facility has been funded by Canadian Foundation for Innovation grant and is currently being built up in our lab. This will be used to build biomedical devices cooperative research with two companies. These consist of precisely shapped plastics holding patterns of electrodes which make contact to the nerves. We build these by an ultraviolet (UV) laser on a computer controlled micropositioning table to create 3D structures with photoablation: where the UV photon's energy literally tears apart the molecules of plastics and allows the automated shaping of materials. The computer controlled UV laser table system will allow cuff design and electrode positions to be altered from one test sample to another, for rapid design evolution.


Currently microfabrication photolithography is dominated by the use of organic based photoresists.  However, as the movement to shorter wavelength (<157 nm) exposures continues organic resists have presented problems connected with the extreme short absorption depth of the light.  Furthermore organic photoresists have always involved organic contamination of the wafers and many wet processes (application, development, and cleans) at a time when most other microfabrication processes are driven towards dry processes.

Bimetallic thermal alloying resists consist of two thin metal films. In and Bi, in this case, are RF or DC sputtered to the thickness of 15-150 nm on a thin film layer that is going to be patterned. When exposed to light under a photomask, as shown in, the material in the exposed area will absorb the light energy and be heated up to above the Bi/In eutectic temperature. Since the alloy has a lower melting point than either individual film, melting will begin at the interface between the two layers and move outward as the melt pool grows.  At the end of the laser pulse, the resist layers will cool and solidify as the eutectic alloy. The material in the unexposed area, where the light is blocked by the photomask, will remain the same as two-layer structure. Tests show that the alloy have different chemical properties from Bi or In.  For the resist development after exposures, two etch solutions have been found which will attack the areas of unexposed resist more aggressively than the exposed areas. After the resist development, the alloyed area remains while the unexposed area is removed. The pattern is then transferred to the underneath layer to be patterned by plasma etching or wet etching. After the resist stripping, the whole lithography process is completed.This project is supported by a grant from CREO Products, the BC Advanced Systems Institute and BC Science Council.
Click here for papers on the Inorganic Resist project

Space Applications

The free vacuum in orbit makes it an ideal place for many microfabrication processes.  Much current research has concentrated on orbital fabrication of single high vacuum processes, such as Wakeshield's silicon epitaxial growth.  Yet, even the simplest semiconductor devices require the combination of many microfabrication steps, such as thin film deposition, patterning (photolithography), and etching.  Fortunately, with the right choice of processes, the advantage of the native vacuum greatly reduces the number of microfabrication process steps, and equipment complexity, mass and power requirements. The key to this synergy is the modification of the processes that use abundant earth based resources (water, power), to those better suited to the vacuum and microgravity space environment. We have investigated a wide range of microfabrication processes for orbital environmental compatibility.  Many types of deposition (plasma sputtering, CVD, ion implant) and etching processes (Plasma, RIE) require base vacuum levels >10-7 torr, above that of LEO. Computer models have been developed which compare the standard Earth-based process consumables, power and fabrication time with space-oriented processes and also assess alternative space transportation architectures, resulting in a process flow that is optimized for orbital facilities.  Compared to earth operations, removal of the vacuum systems from orbital equipment leads to reductions estimated for each process in equipment mass (48-72%), volume (37-59%), process consumable supplies, and equipment life cycle maintenance.. To create true structures, an important simplifying step is the introduction of a vacuum based process inorganic resist for photolithographic patterning of films. Since the orbital vacuum also removes earth based contamination from the wafer environment, the elimination of organic resists almost eliminates local contamination thus reducing interprocess cleaning steps, which consume large quanities of water, acids and organic solvents.  It also increases throughput and improves film/etching quality.  The adding vacuum based plasma/ion cleaning processes further eliminates liquid consumables.  In addition the flexible supply requirements of space microfabrication offer a whole new type of space manufacturing where the supply requirements are not closely connected to the delivery of the finished projeduct; an asynchronous supply requirement. The result is a synergistic orbital based methodology for deposition, patterning, and etching that is capable of building microfabricated structures.  This is leading to studies of an orbital microfabrication satellite, a FabSat.

The potential advantage of Microfabrication in space has been under study by my research team at Simon Fraser University.  The project was first conceived in 1990 during my period on the research staff of Massachusetts Institute of Technology’s Lincoln Laboratory microelectronic group where I was principal researcher on the Restructurable Wafer Scale Integration project.  The project proceeded at a modest level, with a first publication in 1991 while the questions were considered.  Starting in 1998 Boeing Aircraft funded a more intense research phase was entered which culminated in a Masters project by Nick Pfeiffer.  This carefully investigated the main technical problems, issues, costs and benefits of space.  Studies showed that successful space microfabrication needed to change the existing wet organic photoresist process for a vacuum based dry resist process.  Several such process to do this have been proposed in the literature.
Click here for papers on space microfabrication
Howver, one of the considerable synergies of our work is the development under a separate program of a Inorganic Dry thermal resist for CREO Products, a world leader in applications of organic thermal resists.  (see Microfabrication section)

Another space related project is the Vision Skin proximity and imaging sensor work is continuing in a cooperative program with the Canadian Space Agency. See the Laser/Optical Sensors area.

Computer/Internet Anti-theft technology

Several projects connected to embedded microprocessor systems are currently being started with local industry. These include computer antithief devices, advanced development software and devices to interact with the internet to detect the theft of inforamtion from systems.

Links To Other Descriptions of My Research

  • Wafer Scale Integration Article: SFU Centre for Systems Science Update
  •  Institute for Micromachining and Microfabrication Research

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    Last updated May 7, 2003