What's the difference between a fab technician and an engineer?

The biggest difference between a technician and an engineer is what each one looks after. Technicians look after the floor: they run the tools by the SOP, do rounds, and handle routine problems. Engineers look after the why: they decide what conditions a tool runs under and whether to change a parameter, and they find the cause when something goes wrong. One works closest to the tools, the other closest to the data and the causes, and a fab can't run without both. Names vary from place to place: technicians are also called operators, or "OP" for short, and in some fabs the people who maintain and repair the tools are called technicians too.

What does a technician do at the tool?

A fab's tools run 24 hours a day, looked after by crews in turn. A technician's shift usually includes:

• Loading lots from the work order: the system issues a work order saying which step this lot needs and which recipe to use. The technician checks that the lot and the tool match, loads it and starts the run.
• Rounds: walking from tool to tool, checking the tower light, the numbers on the screen and whether supplies are running low, and writing down the readings that need recording.
• Handling routine problems: when a tool throws an alarm or a measurement falls outside the control limits, they follow the OCAP step by step: what to stop first, which lots to put on hold, whom to tell.
• Keeping records: what they did and what they saw goes into the system or a log sheet, so the next person can find it.

All of this follows the SOP, the standard operating procedure. It spells out how to do every step, like a cookbook everyone works from: whichever shift or person does the job, the result should be the same. New people usually learn alongside someone experienced and get trained, and only once they've shown they can do it do they run a type of tool on their own.

Because technicians spend the whole shift next to the tools, they are often the first to notice something off: a sound that isn't right, the same yellow light coming on for the third time today. For why the yellow light is the easiest one to ignore, read What do the red, yellow and green lights on a tool mean?.

What is the engineer thinking about?

Engineers mostly work from an office with the data and go into the cleanroom when they need to. They own the why:

• Setting conditions: the gases, temperatures and times in a recipe, where the spec limits sit, and why those numbers.
• Changing parameters: when a number slowly drifts one way, whether to change something, by how much, and whether that affects later steps.
• Finding causes: why a tool stopped or why a lot drifted. That means comparing data, running experiments, and finally writing down the cause and the countermeasure.

There are several kinds of engineer. Process engineers own whether the output is right; equipment engineers own whether the tool runs. For how they split the work, read What's the difference between a process engineer and an equipment engineer?.

Following the SOP vs asking why: what's the difference?

Take one example: a tool throws an alarm.

The technician follows the OCAP: stops the tool, puts the lot on hold and tells the engineer. At this point the problem is contained, and no more wafers get spoiled.

The next questions belong to the engineer. Why did the alarm go off? Is a part wearing out, does the recipe need adjusting, or were the wafers already a little off when they came from the previous step? Can the wafers stuck in the tool still be used? These take data and judgment, and someone has to answer for the decision.

So following the SOP doesn't mean not thinking. For what the SOP covers, following it is the fastest and steadiest way. When something comes up that it doesn't cover, that's the time to pick up the phone.

When a tool fails at night, who calls whom?

Technicians usually work round-the-clock shifts; engineers mostly work days and take turns being on-call at night, and every fab arranges it differently (for why, see Why do chip fabs run 24 hours a day?). A problem at night often goes like this:

1. The night technician sees the tool stop first and does what the OCAP allows.
2. They call the on-call engineer (Equipment for the tool, Process for the wafers) and say clearly what they see: which tool, which alarm, what time, which lot stopped at which wafer, and what they've already done.
3. On the other end of the line, the engineer decides: stop or continue the remaining wafers, whether to get someone else to look, whether to come in at dawn.
4. The technician carries out the decision and records it.

The engineer isn't there and has only what's said on the phone to go on. The more precisely the technician reports, the faster the engineer can decide; the more clearly the engineer states the decision, the more confidently the technician can carry it out.

Why does the handover matter so much?

Technicians hand over at every shift change, and engineers pass things on between the day and the on-call too. One problem can run from midnight to morning and pass through several people, and every change of hands is a handover: what isn't finished, what was decided, and why, all have to reach the next person.

Public workplace-safety guidance recommends doing handovers face to face and both ways, spoken and written: what's written down stays, and talking in person lets the person taking over ask questions on the spot. If a lot was put on hold during a call at night and nobody wrote it down, the morning crew only sees it sitting there, with no idea why.

Which job matters more?

Both, and they can't be separated. The conditions an engineer sets only turn into wafers made right, one after another, because technicians follow them shift after shift. The problems a technician spots on the floor need someone to find the cause and fix the process, or they happen again. Technicians suggest improvements too: some problems can only be seen by people who stand next to the tools every day. Which lot goes first on the line is for Manufacturing to arrange; read What does the manufacturing department do in a chip fab, and how are lots scheduled?.

In fab24hr

Technicians aren't a role you can play, but they're the people you talk to most all day. Tap "Clock in", choose "A day in the fab", then on the "Your role today" card tap "Production fab", swipe to the process engineer and tap "Implant" under the name: you're the implant process engineer. On the late-night shift, De, the night-shift technician in the front-end bay, wakes you with a call: IMP-01 stopped by itself halfway through a lot. He has already called the equipment on-call, and, as the rules say, he ran a monitor wafer: the average is within spec, but the map is all in stripes. Hold the remaining wafers or finish them? "Your call," he says. On the evening shift, you and Hsiu-Lan, the day technician, check the recipe the tool loaded against the work order, line by line; after she goes home, De comes in for the night shift and asks what you want written on the whiteboard. As Manufacturing, on the afternoon shift the only certified technician is at lunch, and Zhe, three months in and due to take his certification test next month, says "I can do it." Whether he runs it is up to you. The companies, people, tools and lot numbers in the game are fictional; how technicians and engineers split the work follows public, general sources, and real job titles and divisions of work differ from company to company.