A Spark Only I Could See

Fortunately, the tears never came.

Maybe it was the low humidity they held inside the line, but whatever had started to well up dried off before it could fall. Anyway.

"This one's called a clamp error. It happens when the pressure chucking the wafer seated on the pedestal never reaches the spec."

The pedestal. In other words, the chuck wasn't pulling hard enough.

"Any idea what causes it?"

Senior Yeongseok asked. I nodded.

"As I understand it, it comes up when there's foreign material on the pedestal surface, or when the wafer itself seats crooked."

He looked ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠genuinely startled.

"What? How did you know that?"

I studied, Senior. Haha.

I was too embarrassed to actually say it, and while I stood there failing to answer, Yeongseok broke into a grin.

"Not bad. Then do you know how to clear it?"

"Ah — I only know what the error means. I've never actually cleared one."

"All right. I'll walk you through it from here."

And he did, literally one step at a time. He took it slowly, stage by stage, and because of that I had the whole recovery down after hearing it once.

"What matters most is when the error starts firing over and over. That means something's actually wrong."

I nodded. A one-off could be handled with a simple recovery, but if it kept coming back, you had to open the tool and inspect it.

"While I was gone, did this tool throw clamp errors a lot?"

"No, Senior."

"Hm. All right. Then let's start with the simple recovery."

With Yeongseok watching, I finished clearing the error. A clean job — nothing to pick at.

Clap. Clap. Clap.

"You're good at this."

"Haha. Thank you."

Isn't he laying the praise on a little thick? Any ordinary new hire could do this much. Hahaha.

That was when something glinted in the window that looked into the tool. Of the five pedestals inside the chamber, the surface of the third one was shining.

What is that?

Now and then, while metal was depositing, tiny glittering particles would form. When that happened it counted as an anomaly, and the usual answer was an internal clean with plasma. But Senior Yeongseok hadn't run a clean.

Then that means…

I was the only one who could see it.

"Senior."

"Yeah?"

"I think there's something strange on the surface of pedestal three. Would you take a look with me?"

"Yeah? Give me a second."

Even for a word from a junior who barely knew the line, he bent back to the window without a single complaint.

"Hmm… I don't think I can quite… wait."

His eyes lit up. The look of a man who ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠had found something.

"Huh. We're going to have to inspect this."

"Really?"

"Yeah. You were right — something's off. The pin that helps seat the wafer is sticking up."

I looked at the pedestal again, and he was right. At first it had only seemed to glitter, but once he explained it, I could see exactly what the problem was.

"Enter the code on the tool and get the chamber ready to open."

"Yes!"

I went straight to the work he'd given me. At the engineers' computers inside the line, he dropped into the seat beside mine and studied me like I was something curious.

"Uh… is there a reason you're looking at me like that?"

"Because it's strange."

"…Sorry?"

"How did you know that was the problem?"

Uh. Hm.

Because it was sparkling?

I couldn't very well say that. I put together the most plausible answer I could.

"I figured if an error had come up, there had to be a reason."

"Right."

"So I looked a little more carefully, and something unusual stood out. I didn't have the knowledge to know what it was, though."

"Hmm. I see."

Senior Yeongseok nodded slowly. Then he grinned.

"When a new hire comes in, ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠this kind of thing happens."

"Sorry? What kind of thing?"

"You catch what the rest of us have stopped seeing. A new pair of eyes."

"Ah. Ahaha. I suppose so."

It was my ability, but I had no decent way to explain that, so I nodded along. And yet.

"Still, it is strange. Usually when you teach someone an error, they're desperate just to memorize what it means and how to clear it."

"…"

"Well, I'm saying you did well. Thanks to you, we headed off something that was about to become an accident. Impressive."

"…Thank you."

I ducked my head. Leave a tool like that and keep running it, and trouble was only a matter of time. And if the process went on without the error ever firing? Poor chucking pressure meant the heat wouldn't conduct properly into the wafer. The deposited film would come out uneven, and that could turn into a quality problem.

What a relief.

The only shame was that I couldn't tell anyone outside I'd stopped it. I was thinking exactly that when he spoke.

"Once the tool's open, take pictures and share them by mail."

"Sorry?"

"You're telling the department you found the problem. That's how the higher-ups hear about what you've done."

"I see. Yes, understood."

I nodded. So I was supposed to write a mail the way Senior Woohyeon had before.

So that's how you do it.

I'd thought of it as a small thing, but it didn't have to be brushed off that way. Even a tiny fault could grow into a major quality issue. I'd blocked the chance of one, and that was worth sharing with the department.

"Thank you."

"Hm? For what?"

"…For telling me to write the mail. If you hadn't, I probably never would have…"

"Then I would've written it for you. Obviously."

Ah. I really thought this was the second time in my life I was about to cry. He was going to make me tear up for no reason at all.

"…Thank you."

After that I followed Senior Yeongseok all over the line. The WN equipment itself was old, so the little breakdowns never stopped — which meant a lot of errors. And so, without particularly meaning to, I was shoveling in experience at an absurd rate.

"This error is…"

"Yes."

"And this one…"

"Yes. Yes."

"Ah, and this…"

"Yes. Yes. Yes."

A luxury I couldn't have imagined while I was trailing my trainer. Me, growing without a pause between breaths. This was the working life I'd wanted.

"Ah. For this error, you have to go down to the plenum and come back."

"Is that so?"

"Yeah. It starts in the utilities."

The plenum was where a tool's support equipment lived. Easiest to think of it as the basement of the line. Down there were the scrubbers that burned off the chemical gases, the pumps that held the vacuum, and the rest. We went down and started checking the utilities.

A glint.

Something was there to see. Behind the scrubber — the piping that carried PCW, Process Cooling Water. The pipe itself was shining.

"…?"

The line was broken?

I checked the scrubber at once. It was fine. Running normally, nothing wrong with it at all. If the PCW had stopped, overheating should have shut it down.

"What's wrong?"

I'd suddenly started craning my neck at something else, and Senior Yeongseok came over. I flinched and shook ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠my head.

"Ah, it's nothing."

"Nothing?"

He tipped his head.

"If it's something you don't know and I might, why not just tell me?"

"Ah… it's nothing major. This pipe just seemed off."

I pointed at the scrubber's PCW line. Yeongseok leaned in and looked it over. As expected, there was nothing particular to see.

"Doesn't look like anything special."

"…I think so too."

"Well. Let's at least call the vendor and have them take a look."

"Understood."

And with that, the matter was settled for the moment. We came up from the plenum and sat back down at the computers. I called the partner company that handled the scrubbers and asked for an inspection.

The call ended there. A little later, even after the vendor had finished the inspection—

All I got back was word that there was nothing unusual. When I passed that along, Senior Yeongseok nodded.

"All right. For now, we watch it."

"…Yes."

Something about it still sat wrong. I decided I'd go down again tomorrow and look for myself.

That was the note I sent once I'd written up WN-4, the tool we'd taken down for inspection over the earlier error.

"Let's go give the Inform."

"Yes!"

Inform time had come, and I headed for the meeting room with him.

"Good afternoon!"

"Hey~ Woohyeon, Jihan."

I greeted them smartly. Senior Yeongseok just waved.

"Seokhyeon, hey. Yeongseok hyung, you're here?"

"Seokhyeon, hi. Senior, welcome back!"

The moment they saw Yeongseok, smiles broke across both their faces. Of course. A good person is someone everyone recognizes. A brief bit of chatter about the honeymoon followed.

"The Maldives really were something."

"I'd like to go sometime myself."

"What, you planning to get married again?"

"…What kind of thing is that to say."

"Hahaha!"

"Jihan. You think that's funny?"

"…I'm sorry."

I snickered along beside them. Then the chatter ended.

"I'll start the Inform. First, WN-4. We took it down for inspection. The reason…"

Senior Yeongseok ran the Inform with an easy hand. Hard to believe this was a man who'd been away from the work for a month. It felt like he was showing us how an Inform was supposed to go.

Nothing like what my trainer used to do.

The detail wasn't even in the same league. Why the inspection had started, what action had been taken, what the result was, and what the next shift needed to do — everything missing from my trainer's Informs was packed in tight.

I need to do it like that.

I listened with my eyes bright. And then the Inform was done.

"That's the Inform."

"Good work, hyung."

"Thank you for your work!"

"Ah, come on. All I did was teach. Seokhyeon did the actual work."

Huh? Me? What did I do? I was just a talking potato, Senior. Next to what you taught me, I'm nothing.

But Senior Woohyeon's and Senior Jihan's reactions were not the ordinary kind.

"Yeah? Seokhyeon has been doing well."

"He has! Last time he fixed WN-15 by himself, you know."

Both of them nodded, acknowledging me.

"Oh, really? Today he spotted something off on WN-4 right away, too."

"Sharp eyes. He's going to be good at this. He'll be the pillar of our group."

"I think so too. He's got ace written all over him, I'm telling you."

Ahaha.

Seniors, you are going to kill your junior with embarrassment. Saying things like that — it's mortifying.

"Thank you."

Still, when people were recognizing you, refusing it wasn't polite. Right. Right. Senior Woohyeon let out a short laugh and went on.

"Oh, right. You sat in on the meeting for WN-15, the one with the department head, didn't you? The senior manager and the department head were pleased with you. Said you were sharp. Said we'd brought in a good new hire."

Aigoo, what was he saying now. Hahaha.

"Hahaha. That's embarrassing."

But it felt good. Keep going. More.