Elon Musk wants to build a dirty fab that you can smoke and eat cheeseburgers in — bets that Tesla will turn the concept of cleanrooms upside down

Elon Musk this week said that the chipmaking industry builds cleanrooms in the wrong way. The head of Tesla and SpaceX promised that once Tesla builds its own 2nm-capable fab, he would eat a cheeseburger and smoke a cigar in that fab.

"I think they are getting clean rooms wrong in these modern fabs," said Elon Musk in an interview with Moonshots. "I am going to make a bet here, that Tesla will have a 2nm fab, and I can eat a cheeseburger and smoke a cigar in the fab."

When asked whether Musk had sketched Tesla's fab in his mind and whether he found a way to protect silicon wafers from cheeseburger grease, he responded that all wafers should be contained at all times. "They just maintain wafer isolation the entire time," Musk said.

A modern fab is a large, integrated manufacturing facility that encompasses ultra-clean production cleanrooms where wafers are processed; sub-fab levels housing vacuum pumps, gas handling, and exhaust systems, dedicated tool service corridors for maintenance and utilities; centralized chemical delivery and waste management infrastructure; as well as office and control areas used for administrative work, engineering, and monitoring.

Meanwhile, cleanrooms are essentially buildings within fab buildings as they are completely separated from other segments of the fab shell. Cleanliness in cleanrooms is specified by ISO Class standards that define the number of particles per cubic meter of air at different particle sizes. For example, an ISO Class 1 cleanroom allows at most 10 particles ≥0.1 µm per cubic meter and 2 larger particles, whereas an ISO Class 2 cleanroom allows up to 100 particles ≥0.1 µm per cubic meter and 38 larger particles. The most critical operations — such as EUV or DUV lithography exposures or advanced gate formation are performed in ISO Class 1 and 2 environments. By contrast, an ISO Class 3 cleanroom allows up to 1,000 particles ≥0.1 µm per cubic meter, which is still vastly cleaner than typical fab environments and common in advanced fabs for less sensitive operations.

Naturally, smoking or eating a burger in ISO Class 1 – 3 environments is absolutely not allowed, as it renders hundreds of millions or billions of particles. In fact, one human breath produces millions of particles along with moisture, not to mention organic contamination with bacteria or viruses. So, even if wafer and tool isolation is perfect, human breath (not to mention smoke or food particles) can affect the environment, which will affect ultra-sensitive EUV mirrors and perhaps fab chemistry.

Eating and smoking in other areas of the fab is also prohibited due to contamination control and safety requirements. In theory, Musk could eat a burger and smoke his cigar in office areas, which is possible even today. Still, smoking is banned in most office buildings anyway.

This is not the first time that Elon Musk has blasted the foundry industry. While he admired Tesla's partners TSMC and Samsung Foundry, in recent months, he has criticized the foundry industry for slow fab buildout and insufficient capacities, which is slowing down the development of Musk's xAI artificial intelligence initiatives. Musk once mentioned that at some point, Tesla could build its own semiconductor production facility, but given the extreme complexity of such an endeavor, this is something that is unlikely to happen. Furthermore, given the comments made by Musk, it does not look like he had an expert-level understanding of how modern leading-edge semiconductor fabs work.

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