I started with a ship full of max-level veterans, and I'm just a complete noob.

After the second loading rack was opened, Lao Sun recalibrated the push rod according to the position marks left in the first loading, while Da Liu connected the material compensator to the lookup table network so that the front, middle and tail sections corresponded to a set of reference power.

After the silicon rod enters the high-temperature zone, the molten zone unfolds steadily along the observation window lines. Fang Xudong keeps an eye on the paper tape while reporting the advancement position, and the temperature envelope is always within plus or minus 0.3 degrees.

The low-frequency oscillations that appeared in the middle of the first run did not reappear. Jiang Ming stayed by the control cabinet, aligning the lookup table output, PID correction, and propulsion position item by item until the melting zone reached the tail enrichment area before letting Lao Sun cool it down.

After the second pass, the resistivity of the front section of the silicon rod rose to 18 ohm-cm. Fang Xudong pressed the new curve onto the record from the first pass. The two lines started to separate from the middle section, while the tail ends converged towards the low-value region.

"The position compensation is working, and the front-end reference power can be further subdivided. The third time, we changed the 20mm increment to a 10mm increment."

Jiang Ming circled the area with the greatest slope change in the middle section with a red pencil. Da Liu then disassembled the lookup table panel and added nodes to the original resistor network. Fang Xudong then rewrote the position and power correspondence table.

During the third pass, the molten zone passes through the middle section of the silicon rod, and the PID correction value only moves back and forth within a narrow range, reducing the temperature accuracy from ±0.3 degrees to ±0.25 degrees.

Old Sun stood guard over the propulsion mechanism, his palm resting on the speed control handle. Only when he saw the paper tape lines become smooth did he pick up the cooled enamel mug and take a sip.

"I felt like I'd had enough of the germanium material, having to go through the furnace six times. Now that it's silicon, I'll have to teach you how to operate it all over again."

"I can't remember the stove, but I can remember the record."

Fang Xudong took the location he was given and wrote the last set of current values ​​for the third time into the table. He spoke softly, but when he wrote, he was slower than usual.

He clearly understood the significance of each number before him; the jump from over 900 degrees to over 1400 degrees in 502 was made possible by these correction values ​​written on the edges of the paper tape.

Before the fourth calibration, Da Liu completed the final calibration of the material lookup table. After several high-temperature cycles, the contact resistance of the clamps at both ends of the silicon carbide rod remained within the specified range.

When the melting zone passes through the entire silicon rod again, the furnace temperature stabilizes at ±0.2 degrees Celsius. The reference power switching between the front, middle and rear sections is smooth, and the directional relays in the control cabinet only operate at the specified nodes.

After the fourth resistivity measurement, the first part crossed 60 ohm-cm and the last part dropped to around 2 ohm-cm. The slope formed by impurity migration was more concentrated than in the first three measurements.

The fifth and sixth rounds were then carried out in quick succession. Lao Sun and Da Liu took two shifts to guard the furnace. Fang Xudong retested the probe pressure and sample temperature each time he took a sample, and then added the results to the same long coordinate paper.

At the end of the sixth pass, the resistivity of the front section of the silicon rod reached about 100 ohm-cm, which translates to an impurity concentration of about 10¹³ per cubic centimeter, and the purity jumped from three nines to six nines.

The last twenty millimeters at the tail end drop to below one ohm-centimeter, and the curve on the graph paper folds down along the edge, making the excised area marked with a red pencil more prominent than the first time.

After checking the last two measurement points, Lin Lanying pushed the probe holder back to its original position, her gaze still fixed on the previous set of numbers.

"Using the same batch of materials and the same furnace, achieving this level of quality through six rounds means that process fluctuations have been effectively controlled."

Jiang Ming took out the six-round purification curve of the germanium material, stacked two graph papers under the lamp with normalized lengths, and found that the absolute values ​​of silicon and germanium were significantly different, but the curves contracted along similar directions.

He re-substituted the viscosity of silicon, the impurity diffusion coefficient, and the effective segregation coefficient into the BPS model, extending the calculation line from the beginning to the end, and the measured inflection point always fell within the error band.

After the rotating disk boundary layer theory was transferred from germanium melt to silicon melt, all the physical properties were changed, but the underlying relationship controlling impurity transport still holds true.

This verification reassured Jiang Ming, but the increase in accuracy from the fourth to the sixth test made him move the pencil back to the front, as the gap between 60 ohms, 84 ohms and 100 ohms was narrowing.

If we extrapolate based solely on the segregation model, the initial stage of the sixth pass should be even higher. However, the existing curve shows a premature slowdown, indicating that a new source of impurities is being introduced into the furnace.

He grouped the cumulative energizing time of the silicon carbide rod, the power in the highest temperature zone, and the impurity concentration in the front section of the silicon rod together, and then looked up the records of graphite crucibles from the germanium era. The curves at the ends of the two stages showed similar confined shapes.

"At temperatures above 1400 degrees Celsius, silicon carbide rods release trace amounts of carbon and silicon vapor. After entering the molten zone, the carbon remains in the interstices of the crystal lattice. The front end has just been purified, and then something else is being added to the furnace."

Huang Kun took the two records and checked them line by line along the slope after the fourth reading, his expression growing increasingly serious.

"The cleanliness of the heating element and the melting vessel has become the upper limit for this furnace."

"To achieve the 7.99% efficiency, we need to switch to a cleaner heating method. Radio frequency induction heating with a floating zone melting is one way, and we can also make room for improvement by continuing to modify the sealed and isolated heating element."

After the experimental results, Jiang Ming wrote down two directions. At present, the high-frequency power supply, coil materials and furnace conditions are difficult to support a complete transformation, so he only included them in the subsequent technical reserves.

Wang Shouwu arrived at the Institute of Physics that evening, sat down at the recording table, flipped through the data from the first batch of furnace loading to the sixth batch of resistivity curves, and then laid out the six rolls of temperature control paper tape in chronological order.

His own laboratory has also done silicon zone purification. When manually adjusting the pressure, the furnace temperature moves according to the experience of the on-duty personnel. It is best to stop at five nines for a batch. Repeated tests will also show obvious dispersion.

The closed-loop control system in front of us binds temperature, propulsion position and material load into the same set of records. The results of six iterations can be cross-checked, and the difference has been reduced to the process control itself.

Wang Shouwu rummaged through the documents for a long time before taking off his glasses, wiping the lenses clean, and then putting the six records and temperature control curves into his gray-blue briefcase.

He wrote "502 Silicon Region Purification Technology Handover Materials" on the cover, then turned to Jiang Ming.

"I brought this set of data back to the group. We will put the diffusion furnace and single crystal growth together in the next step of the plan, and prepare materials, equipment and personnel as a joint project."

At this very moment, at the Third Electronics Factory headquarters, Wu Hanzhang also received the approval for the second batch of pre-research funding from Factory Director Zhang. The special fund for silicon materials in the approval form has been listed separately.

The comment section contains only one line: "K-band pre-research is urgent, and resources must be prioritized."

When Wu Hanzhang returned to 502, Fang Xudong was updating the overall progress chart. He pressed the approval document next to the column for silicon single crystal growth, and the factory's red stamp on the paper covered the previously empty resource number.

The silicon region purification has entered the verification completion stage. The next item is to recalculate the crucible material, protective atmosphere, rotation speed, and BPS parameters.

Jiang Ming opened the old hardcover memo and wrote down the Germanium process verification, silicon regional purification, silicon single crystal growth, Laue orientation and double diffusion retest in turn as the stage conclusions.

The five nines purity combined with crystal orientation control left by Lei Zhenbang have been extended from germanium devices to silicon, and the old method is continuing to move forward along the new material system.

After reading the record, Wu Hanzhang pushed forward the approval of the second batch of funds.

"The funds have arrived, and Wang Shouwu is also preparing to make a move. When he comes next time, he will probably bring more than just records."