Key takeaways:
LAPLACE promoted poly-fingered TOPCon as the next step beyond conventional TOPCon, requiring only 2 additional process steps
The company introduced new tools for edge passivation, laser ablation, and TBC optimization, with throughputs up to 10,000 wafers per hour
It also presented a solution that increases the lifetime of the quartz tube and the longevity of the quartz parts
A pioneer in TOPCon mass production equipment supply, LAPLACE presented its latest solutions for upgraded TOPCon and back-contact (BC) technologies at the TaiyangNews Cell & Module Production Equipment and Processing Materials Conference 2025.
As part of the next shift in cell technology, LAPLACE promotes its upgraded TOPCon, branded ‘TOPCon+’, as an alternative to BC. TOPCon+ features a rear-side oxide + polysilicon stack in a fingered structure, as opposed to the full-area oxide + polysilicon rear-passivation of conventional TOPCon.
Poly-Fingered TOPCon or Back Contact?
TOPCon+, which can also be termed as poly-fingered TOPCon, is achieved by selectively etching the full-area rear passivation stack. This, according to LAPLACE, is achieved using in-house developed laser tools. LAPLACE argues that the shift from TOPCon to TOPCon+ is simpler than shifting to BC, in terms of the complexity in the process steps of a BC line.
Taking conventional TOPCon as the benchmark, LAPLACE presented a comparative analysis between TOPCon+ and BC based on 3 parameters: manpower requirements, process complexity, and cell bifaciality, as shown in the table below.
Firstly, by shifting to TOPCon+, there is only a 3% increase in manpower as compared to a 20% increase with a shift to BC. Secondly, since BC has all the contacts on the rear side of the cell, additional process steps are required to mask one polarity of a layer before selectively depositing another layer, which is then followed by isolation of the 2 polarities from each other. These steps also follow a different sequence compared to a conventional TOPCon line, adding to the complexity. In contrast, TOPCon+ adds just 2 extra steps to the standard TOPCon flow:
Laser ablation to selectively etch the rear passivation, and
An edge passivation step post-metallization to passivate the half-cut cells as a final step before testing and sorting.
So, for the new TOPCon players, if the weighted level of complexity is a moderate level 6, then TOPCon+ would still be moderate with 7, whereas BC would be ranked as hard with 10. Thirdly, the bifaciality of poly-fingered TOPCon would be higher, at about 85%, compared to about 70% bifaciality of BC, or slightly higher in some cases.
With current advancements, the absolute efficiency difference between the 2 technologies is around 0.4%, which the company notes is not significant, given that there is still scope for further efficiency improvements for TOPCon+. With all the above advantages, LAPLACE is promoting TOPCon+ as an alternative to BC.
To learn more about various process routes and latest developments in cell and module technologies, read TaiyangNews Cell & Module Technology Trends 2025.
Latest Tools:
Even as it promotes poly-fingers, LAPLACE has also developed a toolset that can process TOPCon-BC (TBC) cells. This way, the company can still cater to BC cell manufacturers in addition to the poly-fingered TOPCon players.
At the conference, LAPLACE showcased 3 new tools that are optimized for both poly-fingered TOPCon and TBC processes:
A system to support cutting and passivating the edges of the final cell, with a throughput of 10,000 pcs/h for an M10-sized wafer.
A tool to reduce the poly layer thickness using laser ablation, which helps lower parasitic absorption and improve efficiency, with a throughput of 9,000 pcs/h for M10.
Equipment to form a structured doped layer for TBC, with a throughput of 3,600 pcs/h for M10.
Cost Reduction Solutions:
In addition to its earlier cost-reduction approaches, LAPLACE says it has developed in-house heating elements that improve thermal uniformity while reducing processing time, thereby extending the longevity of quartz parts. LAPLACE also introduced nano-crystalline coating for quartz tubes, which extends their lifetime to 6-9 months. Its latest LPCVD tool, incorporating these features, is said to lower the cost of operation (CoO) by 39% compared with PECVD. The company also emphasizes that its ex-situ doping approach for polysilicon allows its customers to sell their products to the USA and Europe without IP issues.
The company is additionally working towards silicon-perovskite tandem technology, though the related equipment is still under development.
.png?w=50&fm=png){kind=logo}