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January 27, 2024

MOSIS: The 1980s DARPA ‘Silicon Broker’

This piece is a part of a FreakTakes series. The goal is to put together a series of administrative histories on specific DARPA projects just as I have done for many industrial R&D labs and other research orgs on FreakTakes. The goal — once I have covered ~20-30 projects — is to put together a larger ‘ARPA Playbook’ which helps individuals such as PMs in ARPA-like orgs navigate the growing catalog of pieces in a way that helps them find what they need to make the best decisions possible. In service of that, I am including in each post a bulleted list of ‘pattern language tags’ that encompass some categories of DARPA project strategies that describe the approaches contained in the piece — which will later be used to organize the ARPA Playbook document. These tags and the piece itself should all be considered in draft form until around the Spring of 2024. In the meantime, please feel free to reach out to me on Twitter or email (egillia3 | at | alumni | dot | stanford | dot | edu) to recommend additions/changes to the tags or the pieces. Also, if you have any ideas for projects from ARPA history — good, bad, or complicated — that would be interesting for me to dive into, please feel free to share them!

Pattern Language Tags:

  • Encouraging modularity and open interfaces
  • Democratizing an area of research via cost reduction
  • Promoting a coordination/service mechanism to reduce material costs and increase research feedback cycles
  • Facilitating tool/hardware improvements in a key technology area far from its suspected theoretical frontier

Introduction

In the early 1980s, a large amount of money and energy from DARPA and the DoD was shifting towards computing infrastructure and applications. While many involved with those organizations already had one (hopeful) eye on long-term applications such as AI, it was clear that almost all aspects of DARPA’s AI plans, in some way, leaned on ease of access to computer chips for the research community.

So, as a suite of DARPA and DARPA-adjacent projects sprung up — all in the hopes of systematically building up the greater universe of chip capacity and computing applications — DARPA’s MOSIS project was established to ensure that researchers working on computing problems could have faster and cheaper access to computer chips. In this early era of computing research — when the technical capabilities of chips were orders of magnitude more limited than they are today — it was the norm for many researchers and engineers to design bespoke chips for the particular task at hand. MOSIS would provide the middleman service to all researchers who needed their designs fabricated into chips more cheaply, quickly, and discretely than would otherwise be available.

Context

In the late-1970s, printing chips was extremely expensive. For independent researchers paying a separate facility to print their design, the price of a single wafer could have a price tag in the tens of thousands. Since hardware was often specially developed for individual applications or experiments, single research projects often required printing individually designed chips. The cost was a big problem and the process itself was a major annoyance to researchers. Manufacturers who printed chips often had specialized syntax in which they encoded the digital designs into their machines. Going back and forth with a manufacturer was a major tax on researchers’ time and timelines. Also, researchers handing all of their designs to manufacturers was a point of concern. If their project was a success and they attempted to commercialize it, one of the researcher’s now-competitors would have their digital designs in hand. The system of fabricating chips, at the time, was just not set up for convenient access by the community of individual researchers. That is why MOSIS was created.

MOSIS could make things cheaper and easier for these researchers. While individual silicon wafers and runs with manufacturers were expensive, the average chip that needed to be fabricated for a standard research project was quite small — about 1/20th the size of a wafer of silicon. Since the field was new and there was not exactly a mass market of hobbyists who would pay for many chips to be run in parallel, a market/middleman service had not been made for this particular service. Without a solution, new research might be far more expensive, time-consuming, and sparse than it otherwise could be.

In the backdrop of all of this was the belief – encompassed by a 1976 RAND report by Carver Mead, Ivan Sutherland, and Thomas Everhart – that the integrated circuit revolution had only half run its course. Another four orders of magnitude improvement in chip manufacture seemed theoretically possible. Despite this potential, the authors believed that many industry players largely seemed to persist in incremental development. They believed DARPA should take steps to get involved and help speed up ambitious development and research work in the field.

Beginnings

The demand and usefulness of the eventual MOSIS service were first proven through Carver Mead’s chip design course at Caltech — leveraging a more computational, less manual pipeline for designing chips he had developed — and subsequently through courses modeled after Mead’s course at MIT and elsewhere.

Mead wanted to teach his students how to design VLSI (Very Large-Scale Integration) chips. Since there was no single industry standard to teach to because each manufacturer had its own protocols, Mead developed a general set of protocols out of the disparate standards that would allow students to learn the principles in a specific way — but in such a way that the students would still be useful to any arbitrary company they may go work for after graduation. Above all, Mead wanted students to learn to design chips by actually designing their own chips.

To make this goal feasible, printing the chips would have to be cheaper. So Mead figured out a way to put many chip designs onto the same wafer to reduce printing costs. Mead turned to Lynn Conway — Head of LSI System Design at Xerox PARC — and Xerox PARC fulfilled the role of silicon broker in this first iteration of the course. And it was a success. Mead and Conway succeeded in the course’s goal of trying to ‘totally isolate the designer from all the trivia that fabrication requires’ to enable students to learn chip design faster.

These learnings and design standards were eventually codified into what became the bible of VLSI design, a book co-authored by Mead and Conway titled Introduction to VLSI Systems. This book and the course’s approach were how the course’s teachings began to reach more schools and researchers. The approach demystified chip design and enabled researchers to learn chip design in a course setting — rather than having to consult for a chip manufacturer to learn all the little tips and tricks of the trade as was common at the time. You didn’t need to know everything about chip manufacturing to design workable chips anymore. In 1978, Conway went to MIT to teach MIT’s iteration of the course for the first time. By 1980, things were progressing. In the spring alone, “250 designers from 15 universities and R&D organizations submitted 171 projects for implementation.” These specific chips were fabricated by HP.

With the potential of the service proven at several schools and across multiple manufacturers, Mead, Conway, and others began pushing more strongly for a DARPA project to take over and scale this work. At the time, most DARPA PMs made efforts to be in close contact with as many potential PIs as possible in relevant research areas. In this particular case, Conway — while at Xerox PARC — began pushing Kahn — then head of IPTO — to push this work forward. Although, it is very likely that if Conway had not made this push, Mead could also have reached out to one of the IPTO PMs who frequently worked with CalTech.

The Information Sciences Institute (ISI) — which had an affiliation with USC but was independent of the university in many ways — was granted the role of DARPA “silicon broker.” In the 1980s, they became one of IPTO’s go-to performers to carry out a variety of services like this which required research familiarity as well as the organizational skills of a company — such as orchestrating the Machine Acquisition Program in the adjoining piece. ISI was started by a group of researchers who felt their former employer, RAND, was too geared towards paper studies and did little in the way of directing research and work on technology itself. ISI was an unfunded research arm of USC — paying its own way through (mostly DARPA) grants and contracts. Their regular work included performing services for DARPA, conducting applied research, creating technology transfer programs, and more. ISI had often conducted work somewhere in between applied research and DARPA program administration before, and, thus, was very well-suited to this new role.

Operations

Once the program was established, the user experience was quite straightforward. Those who had access to MOSIS — largely NSF researchers, DARPA grantees, and other individuals whose funds were largely from the government — communicated with the MOSIS central office via the ARPANET. MOSIS put together a user manual explaining how electronic mail via the ARPANET worked — those were the early days of the internet — and how to email designs and queries to the mail system in a structured way so a program could sort them.

Researchers sent their designs — in CIF files — to MOSIS. MOSIS, initially using a system designed by Ron Ayres of ISI, took it from there. The system:

  • Checked the CIF file to ensure it conformed to the basic design standards outlined by MOSIS in the user manual.
  • Packed sets of projects onto a smaller set of dies.
  • Translated each die into MEBES format.
  • Made bonding diagrams for manufacturers.
  • Most importantly, produced tapes that the foundries used to make masks.

Danny Cohen and George Lewecki of ISI, in a 1981 talk on the early MOSIS system, described how the process continued from there, saying, “The next step in the process is mask fabrication. Mask houses expect two types of things from us: tapes with MEBES files and job decks. MEBES files contained the information that the mask houses used to make bitmaps (which are made into masks). A job deck…contains the specifications for each MEBES file — parity, record size, etc.”

The talk continued, “Fabrication itself is very simple because somebody else does it. Once the masks are made, all we have to do is drive three, four, maybe ten miles in Silicon Valley with the masks to a wafer fabricator. (It is wise to drive slowly to make sure the masks don’t break.) After that, if we’re lucky — and typically we are — we end up with a couple of wafers.” MOSIS completed its job by dicing, bonding, packaging, and shipping chips.

The MOSIS staff also took measures to ensure that they were as ‘lucky’ as possible. And when they weren’t lucky, they made arrangements that ensured as few defective chips as possible were handed to users. They accomplished this in several ways. MOSIS carried out basic probing tests on transistors, inverters, etc. ISI kept track of defect rates for any given type of job from all of their fabricators to 1) ensure that they continued to work with the best fabricators possible and 2) that they ordered enough duplicates of any given part for a researcher to ensure a 90% probability that a given print would yield a working chip for the researchers — helping keep research projects on schedule.

ISI also carried out different forms of applied research to ensure progress in a variety of operationally important areas. Some of these areas included exploring the feasibility of expanding the service into new chip types, working to incorporate new coding language into ISI’s workflow, using new varieties of machines in their work; etc. In general, it was ISI’s job to do any research work required to make the service work as efficiently as possible and take advantage of the rapid technological improvements happening in the field of computing. While the ISI team did not set out to do fundamental research in its own right, the ISI team’s skills as researchers may still have been important to the project’s success. In the hunt to make chips smaller, new technical problems constantly arose in fabrication processes. Courses of research were often required to work through these problems.

One ISI research project involved finding a way to translate the different design languages used by researchers into those used by manufacturers. Another case — discussed in the Cohen and Lewecki talk at CalTech — outlined how the ISI team worked around a difficulty in testing new softwares to see which software was best:

The problem arises in comparing two masks, one produced by the old [software] and the other produced by the new system. Are the patterns really the same? A microscope is supposed to help, but it can’t do a good job. We tried many ways and finally worked out a very strange technique. Suppose you want to compare mask A and mask B. What we did was to overprint A and B bar [the reverse of B], and A bar and B. In this way we discovered all the changes. We did all the printing on one plate so we wouldn’t have to use a special microscope.

One final — often forgotten — aspect of MOSIS’ success was that it provided a layer of security and confidentiality to researchers and manufacturers. Researchers came to trust ISI agents and their system for communicating design instructions to manufacturers. As Roland and Shiman — who wrote an in-depth history on DARPA’s 1980s computing efforts — noted, “Only ISI had the electronic version of their designs; versions on masks or even on the chip itself were prohibitively difficult to decode.” Manufacturers also maintained open lines of communication with ISI as they became convinced that ISI respected their proprietary information. Many recognize that ISI’s service in this project was ill-suited to a traditional university department. However, as this remark from Roland and Shiman also indicates, this particular piece of ISI’s service may have been hard to replicate for certain companies in DARPA’s performer pool as well. 

1991 VLSI chip photo. Photo courtesy of Wikimedia Commons.

Results

The MOSIS program is widely considered a success.

The number of wafers MOSIS printed rose steadily throughout the 1980s as demand increased and the field developed. The number of wafers printed grew from 258 in 1981 to 1,790 by 1985. The cost of the average chip for a researcher often came in around 5%-10% of what it would have cost if a researcher had to pay for the entire wafer. In 1988, George Lewecki noted that a single 2µ chip in a MOSIS run could cost as little as $258 (~$650 today). For the most part, DoD and DARPA contractors got the service for free, NSF grantees paid for the service out of their research grants (and eventually received the service free), and any commercial actors had to pay full price.

Throughout the 1980s, the average turnaround for chip times from MOSIS gradually decreased from around 10 weeks to about 8 weeks. The ability to print smaller and smaller features for a given cost and time frame continuously improved by large margins as the field evolved. MOSIS’ somewhat stagnant turnaround time was a conscious decision because allowing more projects to fill the queue helped ISI take further steps to reduce costs.

MOSIS was considered a quite efficient operation. A 12-month period from 1987-1988 saw $9 million flow to the MOSIS program. George Lewecki noted that 74.3% of MOSIS expenses went to fabrication costs, 13.1% to salaries, and 11.4% to ISI overhead.

Lessons Learned (and Caveats)

Some in industry were annoyed that MOSIS might support future competitors of theirs. Private researchers could get free access to resources that TI, Intel, and IBM had to pay for. These researchers were not just looking to expand the knowledge frontier, but spin out companies from their university research if things worked out. Conversely, some within the government were annoyed that the MOSIS service — which was primarily targeted at university researchers — could be used by commercial actors at cost. Essentially, they felt the years of infrastructure and know-how MOSIS built up were not being priced in, and the service was essentially providing an industry subsidy.

To this writer, those criticisms are not to be taken too seriously. But a third area of criticism is worth examining. Some didn’t like that MOSIS seemed to be a never-ending program. MOSIS was providing a service that required some research and also helped the research community, but once it settled into its patterns it was not considered high-risk — even if it was seen to be high-payoff. DARPA tended to focus on higher-risk R&D projects. However, MOSIS also did not seem like a sure-fire commercial bet to spin off into its own firm. While the service was successful, it was not considered a good bet for venture capital by many familiar with the program. It was more of a service and contemporary VCs preferred products. Additionally, 98% of the service’s customers — in this young and research-focused area — were from DARPA, NSF, or DoD funding sources. Competing firms had little need for MOSIS’ main service of subdividing wafers. 

If left on its own in the private sector, one could not be sure MOSIS would survive. For example, it could end up in some sort of ruinous cost-cutting competition with a competing manufacturer and end up out of business. But, still, the service was too good to terminate because it offered a cost-effective way to support a vital area of research and teaching. So, instead, MOSIS was moved under the umbrella of more traditional defense funding to continue operation indefinitely. Funding for the program by the DoD and NSF ended in 1998. However, the program does still exist today under the ISI umbrella at USC. Its continued existence — in an era of very different technological conditions than those that created the original need for the program — may be considered, by some, a data point in favor of “sunset clauses” for certain projects. But I will not address that point further as it is somewhat out of scope of this series.

All in all, the program is considered a success. The MOSIS program succeeded in lowering the barriers to doing ambitious research in a broad research area whose progress was all-important to DARPA and the DoD’s computing goals; microelectronics research could be done by individual researchers for a fraction of the cost it would have previously cost. Additionally, as Kuan and West write, MOSIS “modularized [decomposing a problem into separate modules] the semiconductor ecosystem” by enabling semiconductor design to be done productively on its own. With MOSIS, DARPA was able to help alter the structure of a field in a way that industry incumbents may not have done on their own — but was likely better for the progress of the field.

Previously, design was generally done by those with the skills, experience, and machines to manufacture semiconductors — large industry players. The MOSIS service was able to help unbundle these two separate tasks and pave the way for the semiconductor industry to subdivide into design-only  “fabless” firms and production-only foundries. With so much of this fabless design research being done by the academic community — rather than existing private sector incumbents — the field itself was able to be built out in the open, with researchers making rapid progress by leveraging one another’s discoveries.

Some might believe that rising tides lift all boats and, thus, any infrastructure program in an area that turns out to be explosively productive — like mid-1980s computing hardware — will look good in retrospect. However, one should keep in mind that not all of DARPA’s Strategic Computing infrastructure projects with similar goals from this same era are considered a success in a similar vein. For more on that point, see the accompanying piece on DARPA’s Strategic Computing Machine Acquisition Program. Some feel there could have been a world where the MOSIS investment’s heavy reliance on Mead-Conway standards artificially incentivized researchers to develop λ proportions at the expense of others. The accompanying piece describes a program that made a somewhat analogous error. However, I believe that MOSIS’ placement as more of a broker than a capital purchaser provided it a greater level of flexibility to work around this category of issue that ailed the Machine Acquisition Program.

Check out the adjoining piece here

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