What project owners need to know.
Recharge Czochralski (RCz), also called multipulling, is a way of running a Czochralski puller in which fresh polysilicon is melted into the still-hot quartz crucible after each ingot is pulled, so several ingots are grown from one crucible and one heat-up instead of one. It sits between batch Cz, where the crucible is filled once, one ingot is pulled and the furnace is cooled, and continuous Czochralski (CCz), where silicon is fed while the crystal grows. A 2016 paper by PVA Crystal Growing Systems and Fraunhofer CSP put the crucible at roughly a quarter of consumable expenses in standard Cz, and noted that multipulling also removes cool-down time between runs and extends graphite hot-zone life. The trade-offs are a feeding system, tighter melt control and impurities that build up in the melt with each pull, which makes the crucible's endurance more important. This guide is general industry information; process choices should be validated against the specific equipment, feedstock and supplier documentation for a project.
Batch, recharge and continuous
In batch Czochralski the quartz crucible is filled to the top with polysilicon, one ingot is pulled, and the whole puller is cooled down. The crucible does not survive the cool-down, so every ingot costs one crucible and one full heat-up and cool-down cycle.
Recharge Czochralski keeps the hot zone at melting conditions after the ingot is pulled, refills the crucible with polysilicon, and pulls again. Continuous Czochralski goes a step further and feeds silicon while the crystal is growing, which keeps the melt level steady; it is covered in the CCz guide linked below.
How a recharge cycle works
When an ingot is finished it is lifted into the pull chamber above the furnace, which a gate valve separates from the growth chamber. While the ingot cools there, the hot zone stays at temperature and the crucible is topped up with fresh polysilicon, which melts before the next seed is dipped.
The 2016 PVA and Fraunhofer CSP paper describes the main feeding approaches. A slab feeder lowers side slabs cut from squared ingots into the hot crucible. A central feeder lowers a quartz tube filled with silicon chunks. A mobile recharge system can move between pullers and serve several of them, which lowers the investment per machine but needs a production organisation built around it.
What it changes for crucibles, time and the hot zone
The economics argument is qualitative but clear. The same paper notes that in standard Cz the crucible accounts for roughly one quarter of consumable expenses, that multipulling removes the lengthy cool-down between single runs, and that fewer heat-up and cool-down cycles extend the life of graphite hot-zone parts.
We do not publish per-ingot or per-kilogram cost figures. The gain depends on how many pulls a crucible survives, the feedstock, the puller and the plant's operating discipline, and should be modelled for the specific project.
The catch: impurities and crucible endurance
Most metallic impurities prefer to stay in the melt rather than enter the crystal. In a single batch pull they end up concentrated in the last part of the ingot and the residual melt. In a recharge run that residual melt stays in the crucible, so impurities build up from pull to pull, and the paper examines how this segregation affects the quality of multiple ingots grown in one crucible. Feedstock purity therefore matters more, and plants set a limit on how many pulls they run before replacing the crucible.
The crucible also has to stay sound for much longer at temperature. Devitrification of the inner surface into cristobalite, bubble growth in the glass and wall sag all advance with time, and particles shed into the melt can cause dislocations. That is why crucible grade, the bubble-free inner layer and devitrification coatings are specified more tightly for multi-pull operation.
Feedstock for recharging
Recharge needs polysilicon that can be fed into a hot crucible in a controlled way. Dense chunk polysilicon sized for the feeder is common; the PVA system was reported as tested with chips up to 15 mm. Granular polysilicon from fluidised bed reactors flows freely and can be metered, which suits automated recharge and continuous growth.
Chinese price reports often quote a recharge polysilicon grade for n-type production, which reflects how widely multi-pull practice is used for solar mono ingots.
What an Indian ingot plant should ask
For a new ingot plant, recharge capability is decided when the puller and its auxiliaries are specified, not after commissioning. It touches the pull chamber and gate valve, the feeder, recipes, crucible grade, feedstock form and how operators schedule the hall.
- Does the puller support recharge, and with which feeder type?
- How many pulls per crucible has the supplier demonstrated with comparable feedstock?
- Which crucible grade and coating are rated for the planned number of pulls?
- What feedstock form and size does the feeder accept?
- How are residual melt and the impurity limit managed between pulls?
- How will pilot runs qualify ingot quality across the first, middle and last pulls?
How JRST supports this requirement
JRST Technology helps ingot projects in India decide how their Czochralski pullers will be run, batch, recharge or continuous, as part of equipment selection: feeder options, crucible grades and coatings for multi-pull runs, feedstock form, and pilot qualification across successive pulls. Scope and outcomes are confirmed project by project.
Discuss your requirement
Mohammed Saif Zaveri connects JRST's industrial content to execution conversations.
As Co-Founder and designated partner of JRST Technology LLP, Mohammed Saif Zaveri works across industrial growth, strategic partnerships, client conversations, equipment strategy, and project pathways for silicon, solar, semiconductor, and advanced-manufacturing opportunities.
This knowledge page is part of JRST's public industrial knowledge base, designed to help buyers move from search terms and early research toward a structured technical-commercial discussion.
View Mohammed Saif Zaveri's profileConnect on LinkedInFrequently asked questions
What is recharge Czochralski (RCz)?
Recharge Czochralski, also called multipulling, grows several silicon ingots from one quartz crucible by melting fresh polysilicon into the hot crucible after each ingot is pulled, instead of cooling the puller after every run.
Is RCz the same as CCz?
No. In RCz the crucible is refilled between ingots. In continuous Czochralski (CCz) silicon is fed while the crystal is growing, which keeps the melt level steady during the pull.
How many ingots can be grown from one crucible?
It depends on the crucible grade, feedstock purity, puller and recipe, so there is no universal number. Plants set a limit based on supplier data and their own qualification runs.
Does recharge Czochralski reduce cost?
Qualitatively, yes: it spreads one crucible and one heat-up over several ingots and cuts cool-down time. How much depends on the project, so we do not publish universal cost figures.
Which crucible properties matter most for multi-pull runs?
Resistance to devitrification and sag over long cycles, a bubble-free inner layer, low impurity content and a suitable inner-surface coating, all confirmed by qualification runs on the specific puller.
What feedstock is used to recharge a Cz crucible?
Dense chunk polysilicon sized for the feeder, or granular polysilicon from fluidised bed reactors, which can be metered automatically.
Can JRST help specify recharge Czochralski for a new plant?
Yes. JRST Technology helps ingot projects compare pullers, feeders, crucible grades and feedstock routes as part of the equipment and consumables scope. Outcomes depend on the project and supplier validation.
Primary sources and further reading
Last reviewed 2026-11-03. Technical scope, policy eligibility, availability, and commercial terms should be independently confirmed for each project.