I love a good comeback story of technological innovation, struggle, failure, and redemption. The invention of the scanning capacitance microscope has all of that.
In 1981, RCA filed a patent for the SCM on behalf of company researcher James R. Matey. The microscope was an unintentional by-product of the VideoDisc technology the company had been struggling to bring to market since the mid-1960s. RCA expected the VideoDisc to capture half of the home video market, but instead it lost out in a big way to VHS.
RCA’s James. R. Matey invented the scanning capacitance microscope, which used sensors cannibalized from the company’s VideoDisc players. Hagley Museum and Library
Despite the VideoDisc’s struggles, the underlying technology held a gem: The exquisitely sensitive capacitance sensors used in the VideoDisc players were capable of measuring capacitance differences on the scale of attofarads (1 × 10-18 farad).
But before engineers and scientists could trust Matey’s idea, they wanted an independent evaluation to confirm the accuracy of the new microscope. Researchers at the National Institute of Standards and Technology obliged. Starting in the early 1990s, they too cannibalized capacitance sensors from old VideoDisc players and custom-built a series of SCMs, such as the one pictured at top. After NIST’s validation, microscope manufacturers commercialized the SCM, chipmakers adopted them to study integrated circuits, thus opening the door to the next generation of semiconductors.
Why the RCA VideoDisc Failed
But no story about the scanning capacitance microscope’s triumph would be complete without some discussion of the VideoDisc’s failure. In theory, it should have thrived: It was a thoroughly researched product that anticipated an important consumer market. Its playback fidelity was superior to over-the-air programming and to magnetic tape. And yet it bombed. Why?
The VideoDisc effort had begun in the early 1960s, when RCA asked itself, “What comes after color TV? What will be the next major consumer electronics system?” The company decided that the answer was some type of system to play prerecorded movies and TV shows through your television. RCA was far from alone in pursuing this idea. All of the home video systems under development included a storage medium—film, magnetic tape, nonmagnetic tape, and vinyl discs of various size and composition—and a device to play back the audio and video in high resolution. In addition to magnetic methods, information could be stored using electromechanical, photographic, electron-beam, or optical technologies.
RCA VideoDiscs were easily damaged by dust and fingerprints, so they were loaded into the SelectaVision player inside plastic sleeves.Hagley Museum and Library
By 1964, RCA had settled on VideoDiscs. Like a record album (which the company had pioneered), a VideoDisc was a grooved vinyl platter that uses a stylus for playback. Unlike a record, the VideoDisc carried both audio and video, at a much higher density, and the stylus was electrical instead of mechanical. (The VideoDisc is sometimes confused with the LaserDisc, a home video technology of that era that used an optical laser.)
RCA called its discs Capacitance Electronic Discs. The VideoDisc player spun the 30-centimeter disc at a constant 450 rpm. A metallic stylus traced the depressions and bumps in the disc’s groove by registering differences in capacitance, similar to the way that bringing your finger into contact with a touchscreen causes a detectable change in the screen’s capacitance at that point. Solid-state circuitry unscrambled the frequency-modulated video signal encoded in the capacitance differences. These differences were on the order of femtofarads, and the video signal ran at about 910 megahertz. To get a clear picture, the VideoDisc system required very sensitive capacitance sensors to detect these tiny differences at high frequency.
Unfortunately, commercialization took much longer than expected. In 1972, RCA announced that its VideoDisc would debut the following year, but it didn’t materialize. An article in Popular Science in February 1977 anticipated regional sales by the end of that year. But it wasn’t until March 1981 that the RCA SelectaVision system finally hit the market. Despite heavy promotion, it sold poorly and was pulled from the shelves in 1984. In the end, RCA sank about US $500 million over 20 years to develop the VideoDisc, and it was a total flop.
How Videotape Vanquished the VideoDisc
What went wrong? In a word: videotape. Magnetic tape, which RCA had rejected, turned out to have greater consumer appeal. Introduced in 1976, VHS tapes were cheaper, had more titles available for purchase or rent, and, importantly, allowed owners to record their own programs.
Perhaps if the VideoDisc had launched in 1973, it might have had a chance. But the technology had other problems. Fingerprints, dust, and scratches torpedoed early designs that envisioned users removing the discs from sleeves as casually as record albums; instead, the final version kept the discs encased in a plastic shell that was then inserted into the player.
RCA spent two decades developing its home video system, but in the end the SelectaVision lost out to VHS and VCRs. Hagley Museum and Library
Another problem was running time. In 1977, VideoDiscs could hold only about 30 minutes of material per side. That rose to an hour per side by the time of product launch, but that still meant that any movie over 120 minutes would have to be spread over multiple discs. The first VHS tapes could hold 120 minutes of video (double that of its main tape competitor, Betamax). And VHS kept extending that lead: By the 1980s, VHS had long play (four hours) and extended play (six hours) versions, albeit with noticeable drops in resolution quality.
RCA forecasters also badly misread the economics of VideoDisc players. Their 1977 price estimate for a VideoDisc player was $500 (about $2,800 in today’s dollars). The first VHS players were much more expensive, ranging from $1,000 to $1,400, but by the mid-1980s, their price had dropped to $200 to $400. VHS tapes of major Hollywood films cost about $80—much more than VideoDiscs’ $10 to $18 price tag—but only diehard fans actually paid the modern equivalent of about $440 to buy a movie on videotape. For everyone else, the Hollywood studios licensed titles to third-party rental companies. Seemingly overnight, independent video shops, supermarkets, and national chains like Blockbuster were renting movies for a small fee. For a brief period, RCA VideoDiscs shared the shelves with videotapes, but usually only at independent shops and never with as many titles available.
Meanwhile, RCA struggled to sell its VideoDisc players. The company had forecast eventual annual sales of five to six million players; its first-year goal was a more modest 200,000, and yet it sold only half that number. By 1984, RCA realized the VideoDisc would never come close to 50 percent market penetration, let alone profitability, and pulled the plug.
Birth of the Scanning Capacitance Microscope
Normally that would be the end of the story, another failed venture in consumer electronics. But back when RCA scientists first began researching the VideoDisc, there were no microscopes capable of identifying the tiny variations in the disc that encoded the audio/video signal. The bumps and depressions were less than a tenth the size of the groove itself; even the most advanced microscopes of the day couldn’t detect features that small.
A factory worker inspects an RCA VideoDisc, which encoded the audio and video signals in the disc’s groove. Hagley Museum and Library
And so RCA’s James Matey developed and patented the scanning capacitance microscope (which he abbreviated SCaM, but others wisely shortened to SCM) as a quality-control tool for manufacturing the VideoDiscs. Four years after the first patent, RCA filed a reissue patent with some corrections and improvements. In a very readable paper in the March 1985 issue of the Journal of Applied Physics, Matey and fellow RCA researcher Joseph Blanc explained the new technology. The SCM could detect variations in surface topography on the order of 0.3 nanometers over areas on the order of 0.5 square micrometers. RCA delayed publication of this paper until it had shuttered the VideoDisc operation, and so Matey and Blanc concluded their paper, “We are currently in the process of adapting [the SCM] for similar uses on other samples.” The new use turned out to be in the manufacturing of the next generation of semiconductors.
Semiconductor performance depends on the distribution of intentionally introduced impurities, called dopants, which change the ability of the material to conduct electricity. In the early days of semiconductor production, manufacturers used ion mass spectroscopy and a technique called spreading resistance to measure the dopant distribution in one dimension.
By the late 1980s, integrated circuits had become so small that the industry needed a way to measure the dopants in two dimensions. The SCM, used in conjunction with an atomic force microscope, fit the bill. When the conductive tip of the atomic force microscope made contact with a semiconductor surface, it created a small capacitance, on the order of attofarads to femtofarads, depending on the dopant concentration. The SCM measured the changes of the local capacitance and mapped the dopant distributions. But the technology was still novel and not yet commercially available, so researchers at NIST took up the task of testing it.
In the early 1990s, Joseph Kopanski, Jay Marchiando, and David Berning began building a series of custom SCMs at the NIST Semiconductor Electronics Division. They did more than just reproduce Matey and Blanc’s results. They also provided the industry with models and software for extracting two-dimensional dopant distribution from the capacitance measurements.
NIST’s validation of the SCM led to the commercial production of the instruments, which in turn led to the development of more-advanced semiconductors—an industry that is orders of magnitude more important to the global economy than a consumer product like the VideoDisc would ever have been. It’s a classic tale of redemption in the history of technology: At the start of any new tech project, no one really knows what the outcome will be. Sometimes, you just have to keep going, even through abject failure, and trust that something good will emerge on the other side.
Part of a continuing series looking at historical artifacts that embrace the boundless potential of technology.
An abridged version of this article appears in the October 2025 print issue as “RCA’s VideoDisc Gamble Paid Off in Chips.”
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