Meet Nye - Robert Hoffman
As a Regional Engineering Manager Bob Hoffman helps customers in the Western United States find lubrication solutions for their specific applications. In addition to serving these areas, Bob specializes in lubricants for customers in the aerospace, semiconductor, and medical markets. Prior to working at Nye, Bob worked in engineering and business development for several prominent equipment manufacturers, supplying electronics packaging systems such as pick-and-place, dispensing, and inspection. In that role, he has worked with many of Nye’s existing aerospace and electronics customers, and he acts as one of Nye’s resident experts in dispensing technology. Bob holds a Bachelor of Science degree in Electrical Engineering from the University of California, Los Angeles.
What should semiconductor manufacturing systems and handling equipment OEMs and fabs consider when selecting lubricants for their equipment?
The semiconductor manufacturing market is divided between front-end device manufacturers and back-end assembly and test functions. On the front end, where multi-million-dollar systems are installed to apply chip circuitry to wafers using lithography and vapor deposition, lubricants are selected for high-vacuum compatibility and the ability to withstand high temperatures and sometimes harsh chemicals. There is an extreme sensitivity to making sure the lubricant doesn’t outgas or migrate in any way that would contaminate the wafers being processed. These systems present very costly down-times if they are not running and fully functional, so they need to be extremely reliable and designed for the longest time possible between maintenance intervals. Usually, the Equipment OEMs specify the lubricant performance needed and many of the high-end device designers have expertise in this arena. Companies who are responsible for FAB will typically follow the guidance of the OEM manufacturers.
During back-end assembly and testing, high speed robots are used to pick-and place the individual chips from the wafers into packages such as lead-frames, ball grid arrays and multi-chip modules. High speed wire bonding, encapsulation, curing, and electrical testing are subsequent processes that use sophisticated robots as well. In these processes, vacuum is rarely a consideration, although the processes are still done in cleanrooms. However, the cleanrooms are not as extreme as the front-end side, the chips are less sensitive to contamination once fabricated, and throughput and cost allow for a lower cost lubrication solution. In the design of these robotic systems, it is very common to integrate off-the-shelf components, such as linear drives, slides, motors, and bearings. The system designer is often reliant on the component supplier to select the appropriate lubricants for their components. The need for higher lubricant performance is often only a discussion after they encounter a problem brought to them by their back-end systems customers. It is important to view the lubricants as a critical design component early in the process to avoid system downtimes.
What is outgassing and how does it affect the performance of semiconductor lubricants?
All materials outgas to some degree, and outgassing is akin to evaporation; it is the release of smaller fractional molecules from the bulk liquid or solid material. Outgassing is the cause of “that new car smell” as the plastic and elastomeric materials on the interior of a new car give off vapors from the freshly fabricated materials such as the door panels, seats, carpet, and seals. Evaporation and outgassing increase as the temperature rises, and generally the smaller, fractional molecules are the first to outgas. The rate decreases as the larger molecules take more energy to release. Therefore, it is possible to “vacuum-strip” a material in a thermal chamber to remove the lighter, unwanted outgas constituents before application in the system, to some degree.
Outgassing also increases with lower molecular weight materials, which is why the evaporation of lower viscosity base oils is higher than in more viscous base oils, and still higher than in crosslinked plastics, at a given temperature. In a situation where an outgassed molecule becomes airborne, it can condense on a surface and care must be taken that the condensate does not adversely affect the optical or surface properties of the material onto which it condenses. For example, light molecular weight silicone materials, which are notoriously migratory, are not allowed in certain factories, where painting, bonding and adhesion processes might be adversely affected, were the silicone molecules to deposit on the surface being processed.
How do lubricants for wafer fabrication manufacturing and flat panel display manufacturing differ?
Both systems require extreme levels of cleanliness, vacuum compatibility, and high reliability. Many of the fabrication processes differ, in that flat-panel displays are arrays of fairly-large-feature-size devices that act as switches or gates that allow pixels to be on or off in LCD, LED, OLED, and plasma displays, among a very diverse field of display technologies. These substrates often start as heavy 3-meter square pieces of glass onto which devices are deposited, and they can be eventually cut into TV-size or mobile-phone-size displays. It is much easier to move a very thin 300mm silicon wafer around, in comparison to a 3-meter square piece of glass or solar panel. Moving large materials requires larger robots that are lubricated with greases with better anti-wear properties that can support higher loads
The pixel sizes in flat panel displays are small, though much bigger than the sub-10-nanometer features that are applied to 200-300 mm wafers in the manufacture of semiconductor devices such as microprocessors, memories, and control logic. When manufacturing these wafers, even the smallest contaminants from lubricants can result in product defects and yield loss. Robotics involved in wafer fabrication, therefore, require cleaner lubricants with lower outgassing properties.
Why is it important to validate the performance of lubricants in vacuum?
Vacuum lubricants that are widely used in space and semiconductor applications both face very high consequences from lubricant contamination or lubricant failure if not properly managed. We say it is possible to send an astronaut up into space to repair a satellite— you just can’t get them back. In cases like these, it’s better to ensure an application’s reliability before launch. Especially in today’s semiconductor shortage environment, it is vital that the appropriate semiconductor vacuum lubricant get selected and applied in the best way, to assure up-time and productivity of the device manufacturing system.
What is your favorite part about working at Nye?
I like the diversity of our customer base, and our heritage that spans from “whale ships to spaceships.”. Some days, I could get a call from someone who wants to repair the treadmill in their garage, and then later the same day it could be a customer looking for help on a mission to Jupiter or Mars. In the 10+ years I have been with Nye, many innovators out here in the western US have come to Nye for help with cell phones, medical devices, satellites, electric vehicles, food and drink processing, alternative energy systems, and a very wide diversity of components such as bearings, connectors, and seals of all sizes and shapes. It has been fun to see many of these new products, improved with Nye’s lubricants, come into our world and in some way change the playing field. I learn something new every day and being part of FUCHS opens another whole world of interesting projects.
