The InVisage manufacturing process for our products and partners, from quantum dot to full image sensor module
InVisage’s process begins with our proprietary synthesis of quantum dots – semiconductor nanoparticles less than 5 nanometers in diameter. The high photon capture efficiency of each nanoparticle is the basis for QuantumFilm’s high absorption coefficient, allowing QuantumFilm to absorb as much as eight times more light than the silicon used in conventional image sensors.
A single ounce of InVisage’s QuantumFilm solution (shown on the right) contains enough material to produce ten thousand image sensors.
We apply our QuantumFilm solution at QuantumFab3, InVisage’s high-volume manufacturing facility in Hsinchu Science Park, Taiwan. QuantumFab3’s Class 10 cleanroom houses a QuantumFilm deposition tool specially built to our advanced design. This tool has been designed to coat wafers from multiple external foundries, and the film deposition process can also be replicated at other semiconductor fabrication sites. Each InVisage tool receives standard semiconductor wafers, spin-coats QuantumFilm onto them, then deposits an encapsulation layer and our proprietary top electrode stack. The output wafers are then diced and packaged into commercial image sensor modules. The diagram below summarizes this process.
QuantumFilm solution is deposited on top of the backend interconnect layers of a silicon CMOS chip. The entire top surface of the chip is covered with light-absorbing, electron-generating QuantumFilm, giving the QuantumPixel its 100% fill factor. And because QuantumFilm is connected to the silicon circuitry, adding QuantumFilm on top only minimally affects the design and processing of the silicon components. InVisage’s technology couples the superior light absorption of QuantumFilm with the well-established signal processing of CMOS silicon to take advantage of the best parts of each.
QuantumFilm is deposited on a semiconductor wafer using a technique called spin-coating. InVisage’s custom tool at QuantumFab3 (shown below) applies our liquid quantum dot solution to a wafer rotating at a predetermined speed, resulting in a uniform thickness across the entire surface.
Built into InVisage’s top contact is a highly engineered system of encapsulation, which shields the QuantumFilm from oxygen and moisture. We use dense, conformal and pinhole-free layers to protect the QuantumFilm from the elements, ensuring its reliability over extended product lifetimes. All of this makes InVisage’s top contact an ideal partner for QuantumFilm – a light-transmitting, electron-capturing, global-shuttering and moisture-blocking machine. It’s QuantumFilm’s very own bulletproof glass.
One of InVisage’s major advances is QuantumFilm’s global shutter feature. This feature ultimately relies on exquisite control over the operation of QuantumFilm, with dexterity well beyond what silicon can achieve. Our transparent top electrode delivers circuit-powered control over whether the film is on and sensitively detecting light, or off and powerfully obscuring it. InVisage’s top electrode took years to develop – it is a layered, multi-material stack that is highly optimized to be in perfect harmony with QuantumFilm. The top contact effortlessly extracts photoholes as they stream out of the QuantumFilm. At the circuit’s request, the valve can be closed, leaving photoholes inside that remain undetected. The top contact’s capture of photoholes is achieved via careful tuning of its valence band energy. We use advanced characterization techniques, such as x-ray photoelectron spectroscopy, to ensure that the valence band energy of our top contact is well matched for QuantumFilm.