Developments on laser drilling technology and ablation of dielectric lasers for c-si cells

Transcription

1 Developments on laser drilling technology and ablation of dielectric lasers for c-si cells Richard Hendel / Jason Liu Backcontact workshop Shanghai - May 19

2 ROFIN Group Key Facts Headquartered in Plymouth, Michigan (USA) and Hamburg (Germany) Sales: FY 2013: $560 million Worldwide > 2,100 employees Thereof approx. 140 sales engineers and 400 customer service personnel 22 production facilities in North America, Europe and Asia Customer service support in more than 50 countries Rofin has a installed base of 2500 lasers in PV production

3 Market Situation new rule in China 2013 抑 制 光 伏 产 能 盲 目 扩 张 严 格 控 制 新 上 单 纯 扩 大 产 能 的 多 晶 硅 光 伏 电 池 及 组 件 项 目 光 伏 制 造 企 业 应 拥 有 先 进 技 术 和 较 强 的 自 主 研 发 能 力, 新 上 光 伏 制 造 项 目 应 满 足 单 晶 硅 光 伏 电 池 转 换 效 率 不 低 于 20% 多 晶 硅 光 伏 电 池 转 换 效 率 不 低 于 18% 薄 膜 光 伏 电 池 转 换 效 率 不 低 于 12%, 多 晶 硅 生 产 综 合 电 耗 不 高 于 100 千 瓦 时 / 千 克 Depress low-end capacity expansion. New project of expanding polycrystalline, cell, and module production should be rigorously controlled. PV manufacturer should possess advanced technology as well as strong R&D strength. New project of PV production expansion should fulfill the following criterion, monocell not below 20%, multi-cell not below 18%, thin film not below 12%, polycrystalline energy consumption not above 1000kwh/kg.

4 Market Situation Solution 1 for 18/20% efficiency with moderate investment and retrofitable to standard lines: PERC technology Solution 2 for 18/20% efficiency with moderate investment in cell technology but requirement of new module technology: MWT technology for p-type (also possible with n-type or in combination with PERC)

5 Laser applications on C-Si solar cells Rear side passivation Selective Emitter Edge Isolation Emitter Wrap Through Laser Fired Contacts Cutting Marking Metal Wrap Through

6 Cell Efficiency Enhancement Back Contact Cells Rofin lasers are enabling technology for new cell types Metal Wrap Through (MWT) Diameter: 200 microns Trepanning: 25 holes < 1 second Powerline F 30 LP (IR = 1064nm) Metal Wrap Through (MWT) With Passivated Emitter and Rear Cell (PERC) 6

7 Cell Efficiency Enhancement Back Contact Cells In comparison result with 532nm laser, result: Fiber laser concept with 1064nm, superior in price and performance Metal Wrap Through (MWT) Diameter: 200 microns Trepanning: 25 holes > 2 second Powerline E25 SHG (=532nm) Picture: Courtesy of ECN c-si Solar Cells / RH 7

8 DUAL LINE c-si for MWT Drilling Machine video: (click on picture) This example is showing DUAL LINE c-si with stack handling for drilling of c-si MWT solar cells c-si Solar Cells / RH 8

9 Cell Efficiency Enhancement Passivated Emitter and Rear Cell (PERC) Front Side Texturing Phosphorus Diffusion Option: Selective Emitter (Laser Doping) PSG removal Schematic of Cell Design with SiO2/SiNx or Al2O3/SiNx Option: Back Side Chemical Polishing Dielectric Layer Back Side Stack of SiO2/SiNx or Al2O3/SiNx Front Side PECVD - SiNx Laser Opening Back Side Schematics, Source: Dullweber, et al 26th EU PVSEC, EFFICIENT LARGE AREA REAR- PASSIVATED SCREEN-PRINTED SILICON SOLAR CELLS Front and Back Side Metallization c-si Solar Cells / RH 9

10 Lasers to choose from: PowerLine E 25 SHG highf and L 100 SHG Introduced in mass production are nsec SHG Lasers R&D labs are using ultra short pulse lasers Beam Characteristics E 25 SHG PV L 100 SHG Wavelength [nm] Average power [W] > 100 khz max 100 W Pulse frequency [khz] Pulse width [ns] 100kHz 10kHz Alternative choice Beam Characteristics StarPico StarFemto FX Wavelength [nm] 1064/532/ /532/355 Average power [W] > 10, 20 or 40 W > 4, 10 or 15 W Pulse frequency [khz] Pulse width [psec] 12 0,3-10 c-si Solar Cells / RH 10

11 Dots or Lines? Dots or Lines is one of the most common questions for PERC cell design, considerations: Typical the total area to be laser opened is: 3-5% Typical line spacing requirement is 0,5 2 mm (in case of line opening) Typical dot spacing requirement is 0,2 1 mm (in case of dot opening) Calculation for 3 different scenarios: Spot diameter spot area % of area number of spots required dot spacing/mm length of path / m dot 0,2 0,1 0,0314 mm² 4,5% ,84 29,13 line spacing/mm length of path / m line 0,05 0,025 0, mm² 4,0% ,98 24,80 line 0,03 0,015 0, mm² 3,5% ,67 36,17 Assumptions for this calculations: Dot pattern is arranged in 90 pattern, not hexagonal Lines pattern with zero spot overlap

12 Dots or Lines? video: press button twice

13 Lasers to choose from: PowerLine E 25 SHG highf and L 100 SHG Introduced in mass production are nsec SHG Lasers R&D labs are using ultra short pulse lasers Beam Characteristics E 25 SHG PV L 100 SHG Wavelength [nm] Average power [W] > 100 khz max 100 W Pulse frequency [khz] Pulse width [ns] 100kHz 10kHz Alternative choice Beam Characteristics StarPico StarFemto FX Wavelength [nm] 1064/532/ /532/355 Average power [W] > 10, 20 or 40 W > 4, 10 or 15 W Pulse frequency [khz] Pulse width [psec] 12 0,3-10 c-si Solar Cells / RH 13

14 Comparison between ns- ps- and fs-laser SEM pictures nsec psec fsec

15 Influence of Al paste into contact formation 3rd party R&D results SEM cross section image of a screen-printed, rear-side-passivated PERC solar cell with local line contacts on the rear side. Picture from ISFH: Conclusion: Laser damage of nsec SHG lasers is cured by firing process and building of Si-Al Alloy T. Dullweber et al., Prog. Photovolt. (2011), DOI: /pip.1198

16 DUAL LINE c-si machine platform Features: High Throughput (up to UPH) On the Fly processing option Standardized platform with granit base QC-system with laser power control and multiple wafer sensors Integrated exhaust and filter system Inline, cassette or stack handling for all common standards and degrees of automation Benefits: Compliance with highest safety standards and CE signed Excellent laser expertise High-precision laser processes Layout with compact wafer handling c-si Solar Cells / RH

17 Thank you very much for your kind attention! Dr.-Ing. Roland Mayerhofer, Tel