[original story reprinted below]
MENLO PARK, Calif. — Mobile photographers could soon have much better cameras on their cellphones, thanks to technology known as quantum dots.
InVisage Technologies, based in Menlo Park, Calif., has spent more than three years trying to build a proprietary film that coats the image sensors used in cellphone cameras and allows them to capture more light. The film stands as a rare commercial use of an exotic semiconductor material called a quantum dot.
Jess Lee, the chief executive of InVisage, said the company’s lab tests had convinced him that within two years cellphone companies would be able to offer cameras that work about four times better than today’s cameras, particularly in low light.
The image sensors in cellphone cameras now use silicon to capture light, which is then processed to create a picture. Companies making these sensors have run into problems as they keep shrinking and tweaking the innards of the devices so that they can absorb more light.
The limitations of cameras based on this technology often appear when people try to take photos in low light, resulting in a blurry image.
“With the current techniques, you might have technology that’s 10 percent better two years from now,” Mr. Lee said. “The big guys have hit a brick wall, and it will only get harder and more expensive for them to fight it.”
Rather than trying to refine the silicon technology, InVisage turned to quantum dots to build what it calls Quantum Film, a layer of semiconductor material that gathers light better than silicon, Mr. Lee said.
Researchers have spent years working on quantum dots with little success. They are essentially semiconductor particles about a nanometer — or a billionth of a meter — in size. Technologists want to control the physical properties of the quantum dots to make them behave a certain way.
Typically, researchers must build the quantum dots with exotic materials and then struggle to control their properties in a repeatable fashion.
Morry Marshall, the vice president for strategic technologies at the chip consulting firm Semico Research, said that if InVisage had figured out how to use quantum dots effectively, it could mean a huge leap in camera performance. “I don’t know of any technology right now that is even close,” Mr. Marshall said.
Mr. Lee declined to reveal what materials InVisage had used to build its dot, calling it the company’s secret recipe. He did, however, show off vials of the quantum dots suspended in a liquid. The liquid is spread across the top of an image sensor. Mr. Lee expects that companies producing image sensor chips could use the film without substantial changes to their existing equipment.
Rather than licensing the film to companies like Sony, Toshiba or Aptina, InVisage plans to make its own sensors and sell them directly to cellphone companies.
“We expect to start production 18 months from now,” Mr. Lee said.
With such technology, the current three-megapixel camera found in the Apple iPhone could be turned into a 12-megapixel camera that works better in varying light conditions, Mr. Lee said.
Ken Salsman, the director of new technologies at Aptina, a major manufacturer of image sensors for cellphones, conceded that silicon-based sensors had proved tough to advance. But he said that Aptina had managed to improve its technology through some novel techniques, and that InVisage might be “in for a very rude surprise.”
Still, Mr. Salsman commended InVisage for trying something new in this field. “I am very excited to see what they’ve got,” he said. “Having a true change in performance never hurt the industry.”
A version of this article appeared in print on March 22, 2010, on page B6 of the New York edition.
Quantum Dot Material Replaces Silicon; Enables Stunning Image Quality on Mobile Handsets
PALM DESERT, Calif., March 22, 2010, DEMO Spring 2010 – Ushering in a new era of high-performance image sensors, InVisage Technologies, Inc. – a venture-backed start-up that is revolutionizing the way light is captured – today announced QuantumFilm. Harnessing the power of custom-designed semiconductor materials, QuantumFilm image sensors are the world’s first commercial quantum dot-based image sensors, replacing silicon. InVisage delivers 4x higher performance, 2x higher dynamic range and professional camera features not yet found in mobile image sensors. The first QuantumFilm-enabled product, due out later this year, solves the crucial challenge of capturing stunning images using mobile handset cameras.
QuantumFilm was developed by InVisage after years of research under the guidance of notable scientist and InVisage CTO Ted Sargent. The technology is based on quantum dots – semiconductors with unique light-capture properties. QuantumFilm works by capturing an imprint of a light image, and then employing the silicon beneath it to read out the image and turn it into versatile digital signals. InVisage spent three years engineering the quantum dot material to produce highly-sensitive image sensors that integrate with standard CMOS manufacturing processes. The first application of QuantumFilm will enable high pixel count and high performance in tiny form factors, breaking silicon’s inherent performance-resolution tradeoff.
“It is becoming increasingly difficult and expensive to develop next-generation image sensors using silicon; essentially, silicon has hit a wall,” says Jess Lee, InVisage President and C.E.O. “The fundamental problem is that silicon cannot capture light efficiently, but until now it has been the only option. The disruptive nature of QuantumFilm builds on silicon’s success in electronics, and elevates its function using new materials that are engineered from the ground up for light capture.”
Silicon-based image sensors – the technology used today for all digital cameras including handheld, professional, mobile phone, security and automotive cameras – capture on average a mere 25 percent of light. QuantumFilm captures between 90-95 percent, enabling better pictures in even the most challenging lighting conditions. This increase in efficiency will deliver improvements across the entire imaging market, allowing QuantumFilm to be the de-facto next generation camera platform. The first target market for QuantumFilm is mobile handsets, where there is the greatest demand for small, high performance image sensors.
Just nanometers in size, the quantum dot-based material is deposited directly on top of the wafer during manufacturing. And unlike silicon-based image sensor technologies such as BSI (back-side illumination) and FSI (front-side illumination), QuantumFilm covers 100 percent of each pixel. The material is added as a final wafer-level process, which allows for easy integration into standard semiconductor foundries. The process – akin to coating a layer of photoresist onto a standard wafer – adds minimal cost on top of the standard layers of silicon processes.
“It is safe to say that the industry spends an average of $1 billion for each new generation of pixel technology, all to achieve a single-digit percentage improvement in image quality,” says Tetsuo Omori, senior analyst, Techno Systems Research Co. “The future of imaging is in new materials like QuantumFilm, which will change the competitive landscape and possibly re-ignite the pixel race.”
InVisage was founded in 2006 and is led by industry veterans from the image sensor and advanced semiconductor materials industry. It employs 30 people at its Menlo Park headquarters and has received more than $30 million in funding from RockPort Capital, Charles River Ventures, InterWest Partners and OnPoint Technologies. Its technology is protected by 21 patents and patents pending.
QuantumFilm is ideal for a wide range of image-sensing technologies including security cameras, automotive cameras and military applications. The first QuantumFilm image sensors, targeting high-end mobile handsets and smartphones, will sample in Q4 of 2010.
For more information on InVisage Technologies, please visit its newly-launched web site at www.invisage.com. InVisage will be demonstrating its new technology at DEMO Spring 2010 in Palm Desert, Calif., on March 22 and 23. InVisage will also be giving a talk about its technology at Image Sensors Europe 2010 on March 24 in London.
About InVisage Technologies, Inc.
InVisage Technologies, Inc. is a venture-backed fabless semiconductor company based in Menlo Park, Calif. that is developing QuantumFilm, a breakthrough imaging-sensing technology that will replace silicon. Its first product enables the high-fidelity, high resolution images from handheld devices like camera phones and PDAs. Founded in 2006, InVisage Technologies is venture funded by RockPort Capital, Charles River Ventures, InterWest Partners, and OnPoint Technologies. More information is available at www.invisage.com.
Produced by the IDG Enterprise events group, the worldwide DEMO conferences focus on emerging technologies and new products innovations, which are hand selected from across the spectrum of the technology marketplace. The DEMO conferences have earned their reputation for consistently identifying cutting-edge technologies and helping entrepreneurs secure venture funding and establish critical business.
[original story reprinted below]
A new sensor technology promises to make cellphone cameras good enough to use for wedding photos.
InVisage Technologies, a Menlo Park, California, company, has developed an image sensor using quantum dots instead of silicon. The company claims its technology increases sensor performance by more than four times.
“We have all heard ‘Gee, I wish the camera on my iPhone was better,’” says InVisage’s President and CEO Jess Lee. “But the heart of the problem is in the heart of the camera, which is the sensor.”
Most cameras today used either a CCD (charge-coupled device) sensor or a CMOS (complementary metal-oxide-semiconductor)-based sensor. The silicon in current image sensors has a light-absorbing efficiency of only about 50 percent, says Lee.
Reducing efficiency still further are the layers of copper or aluminum circuitry laid on top of the silicon. The metal blocks the light, so only a fraction of a sensor’s silicon is exposed to light.
Replacing silicon with quantum dots could change all that. A quantum dot is a nanocrystal made of a special class of semiconductors. It allows manufacturers to have a very high degree of control over its conductive properties, and is about 90 percent efficient at absorbing light, according to Lee.
The quantum dots are usually suspended in fluid. InVisage takes a vial of these and spins it onto a layer of silicon, then adds the required metal circuitry to create a new type of sensor that it is calling QuantumFilm.
In addition to the increased sensitivity, InVisage’s technology allows the metal circuits to be placed underneath the quantum film, where they don’t block the light.
“This is entirely different from the type of image sensors that we have right now,” says Tom Hausken, director with market research firm Strategies Unlimited. “Usually you see incremental improvements in sensor design, but these guys have made a significant change in the process.”
Quantum dots can be made from silicon, tellurides or sulphides. InVisage won’t reveal exactly which material it is using.
As opposed to silicon’s indirect band gap, quantum dots have a direct band gap. Lee says Invisage can tune the Dots’ band gap much more efficiently than silicon so it is more sensitive to visible light, ultraviolet and even infrared waves.
In the last few years, manufacturers have been touting megapixels as the measure of a camera’s prowess. But the true measure of picture quality is not as much in the megapixels but in the size of the sensor used in the device.
To capture the light, imaging sensors need to have as much area as possible. Powerful DSLR cameras have an imaging sensor that’s about a third of the size of a business card, while camera phones sport sensors that are only about a quarter inch wide (see top photo). Smaller sensors mean less light sensitivity for each pixel on the sensor, and that translates into lower-quality images.
Quantum dot-based sensors won’t be more expensive than traditional CMOS-based sensors, promises Lee. InVisage says it will have samples ready for phone manufacturers by the end of the year and the sensors could be in phones by mid next-year.
Though quantum dots are commercially produced by other manufacturers, they have never been used on image sensors before, says Hausken.
“Mostly people have looked to use it in displays, solar cells and as identification markers,” he says. “So we will have to see how effective and reliable it is as a sensor.”
[original story reprinted below]
R. Colin Johnson
PORTLAND, Ore. — Just as photographic film was mostly replaced by silicon image chips, now quantum film threats to replace the conventional CMOS image sensors in digital cameras. Made from materials similar to conventional film—a polymer with embedded particles—instead of silver grains like photographic film the embedded particles are quantum dots. Quantum films can image scenes with more pixel resolution, according to their inventors, InVisage Inc., offering four-times better sensitivity for ultra-high resolution sensors that are cheaper to manufacture.
“Many innovations are said to be revolutionary, but are really incremental changes. InVisage’s quantum film, on the other hand, really is revolutionary,” said Tom Hausken, director of photonics and compound semiconductors at Strategies Unlimited (Mountain View, Calif.) “Quantum dots have been a solution looking for a problem for several years, and InVisage has found a very significant problem they can solve.”
According to Morry Marshall, vice president of strategic technologies at Semico Research Corp. (Phoenix), InVisage could have the next generation image sensor. “It gathers more light so you can either make a smaller image sensor for a less expensive cell phone camera, or you make a higher resolution sensor for high-end digital cameras,” Marshall said. “It’s a huge step forward and the market is also huge, so they will also need to overcome the problems facing any small company when trying to penetrate a large market.”
The new semiconducting material was invented by Univeristy of Toronto professor Ted Sargent, who is now chief technology officer at InVisage. Sargent perfected a method of suspending lead-sulfide nanoparticles in a polymer matrix to form a new class of semiconducting polymer that Invisage has spent the last three years integrating into a standard CMOS process. Now it can paint quantum film atop a low-cost wafer that has the electrode array for super-dense high-pixel-count images, but without any of the expensive CMOS photodetectors that make up the bulk of conventional digital camera sensors.
“Our quantum film replaces the silicon used for image capture, but what we have really created here is a new semiconductor material,” said Jess Lee, InVisage president and CEO. “Our quantum film even looks like photographic film—an opaque black material that we deposit right on the top layer of our image chip.”
Unlike tradition semiconductors, which have a fixed bandgap, the bandgap of Invisage’s quantum film can be adjusted by changing the size of the embedded quantum dots. The film can also be painted-on at room temperature, obviating the need for expensive high-temperature fabrication techniques required by conventional sensors.
“We can paint our quantum-dot film onto any surface,” said Lee. “Right now we are painting them on silicon wafers for our first product—an ultra low cost image sensor that obsoletes CMOS sensors.”
Traditional CMOS sensors require that light filter down past several microns of metallization to reach the photodetectors on a silicon wafer, but InVisage’s quantum film is on the top layer for 100 percent exposure to incident light.
“Traditional CMOS sensors require light to travel down through four or five microns of metal before reaching the photodetector, whereas our quantum film captures all the incident light in a layer just 500 nanometers thick,” said Michael Hepp, director of marketing at InVisage (Santa Clara, Calif.).
This process that was improved upon by OmniVision (where Lee was formerly the vice president of the mainstream business unit) with back-side illumination (BSI). According to Lee, BSI only converts about 80 percent of incident light because trenches are required between pixels to prevent cross talk in conventional sensors. Quantum film, on the other hand, exposes the entire top layer of the chip to light, allowing 100 percent pixel coverage and without the need for BSI.
“Just by virtue of having our detector on the top surface, we get a 2X increase in sensitivity—the holy grail of the industry,” said Lee. “Beyond that we have changed the materials too—our quantum film is twice as efficient at absorbing incident light for another 2X improvement, for a 4X improvement overall.”
Physically, what happens is photons hit the quantum dots, but because of their small size quantum confinement converts the energy into an exciton—a bound electron-hole pair. The metal electrode then conducts the electron away thereby sensing the incident light.
“We draw down those electrons and store them on a capacitor in a very standard-looking CMOS pixel—except we don’t have to build a photodetector too so we can use much larger and less expensive geometries, since the quantum film has already done all the light capturing steps on the first layer,” said Lee.
As a consequence, InVisage claims to be able to create image sensors that are four-times as sensitive (or four times smaller for the same sensitivity) using a low-cost 8-inch, 1.1-micron CMOS line at TSMC, compared to the CMOS image vendors today who have to use an expensive 12-inch, 65 nanometer process to achieve inferior results.
For the future, the company also plans to target other specialized applications, such as pitch-black night vision goggles, cheaper solar cells and even spray-on displays.
“Because we have better quantum efficiency, we can also apply our quantum film technology to more efficiently collect light for solar cells, or for paintable displays on textiles, clothing and other novel uses such as glowing street signs and other night-time illumination needs,” said Hepp.
InVisage has had two rounds of funding since its founding in 2006, including about $30 million so far from RockPort Capital, Charles River Ventures, InterWest Partners and OnPoint Technologies.
[original story reprinted below]
A layer of light-absorbing particles boosts digital image quality.
Cell phone cameras are famous for taking grainy, low-resolution pictures. Part of the problem is the lens, which is usually cheaply made and has limited resolution and ability to collect light. But another problem is the light sensor: a silicon chip containing photodetectors. When shrunk to fit in a phone, these chips are limited in the amount of light they can capture.
Now, InVisage, a Menlo Park, CA-based startup, is demonstrating a way to improve the quality of pictures, at least on the sensor side, without adding size, significant complexity, or cost. At the DEMO conference in Palm Springs, CA, today, the company’s executives announced a new technology called QuantumFilm that lets small camera sensors, like those in cell phones, capture more light than ever before. QuantumFilm is simply a layer of quantum dots–tiny crystals that efficiently absorb light and emit either photons or electrons–in a top layer of the sensor. The electrons emitted by QuantumFilm are collected and sorted the chip’s circuitry.
The result is a sensor that collects twice the light of the standard chip, converts it to electricity twice as efficiently, and is just as cheap to make, says Ted Sargent, chief technology officer of InVisage and professor of electrical and computer engineering and the University of Toronto, where the early research for QuantumFilm began. “Silicon image sensors have a really severe problem in that they just throw away photons left right and center,” says Sargent. Quantum dots, he says, provide a “fundamental solution to the problem.”
In today’s digital cameras, a silicon sensor does double duty. It serves as a photodetector that absorbs incoming light and converts it to an electrical signal. But it also acts as the foundation for the electronics that store the signal from the photodetector and route it away from the chip, where it is processed by separate electronics. The problem is that the photodetector part of the silicon often sits below layers of transistors, metal wires, and a color filter. Because of these obstructions, only about half the original light reaches the photodetector.
There are some commercial technologies that try to tackle the problem of the obstructed photodetector. For instance, manufacturers have added microlenses that focus the light into a tiny space. But even with a bigger photodetector area, silicon still isn’t the best light collector: it registers less than half of the photons that hit it.