Tunnel Oxide Passivated Contact (TOPCon) Processing

Incorporating some laser operations to the TOPCon process can further improve photovoltaic performance.

First, the LDSE process, which stands for "laser-doped selective emitters," creates a shallow, highly doped n++ emitter region by adding an n-type dopant to the wafer and then using a laser to both ablate the anti-reflective coating layer and drive the dopant into the underlying silicon. This would be performed before growing the tunneling silicon oxide layer. The benefits of LDSE include improved overall cell efficiency compared to standard methods such as furnace-based doping.

Next, creating laser contact openings, or LCOs, through laser patterning to ablate the silicon nitride and aluminum oxide layers before metallization through screen printing can result in lower contact resistance after metallization.

These improvements to TOPCon panel performance could help the technology become more widespread.

• 50+ years and thousands of laser micromachining systems for industrial applications
• Long-term partner to photovoltaic processing companies
• Full range of products: lasers, motion, optics, opto-mechanics, beam analysis
  • Custom capabilities
  • Product availability
• Ability to scale with you
• Global corporation and presence

Lasers	Light Analysis	Motion Control	Optics & Opto-Mechanics
Ultrafast UV lasers DPSS Q-switched lasers	High power laser thermal sensors High power beam profilers Laser power/energy meters	Full range of motorized stages Motion controllers Manual Positioners	Mirror mounts Lens positioners High-energy optics UV and visible optics

When choosing a laser, there are three main categories of criteria to consider. First is the application or function of the laser, such as patterning cells to create LCOs or ablation as part of the LDSE process. The next category addresses the requirements of that application, such as the type and thickness of the material to be processed. Then, the specifications of lasers, such as wavelength and power, must be evaluated. Listed here are the criteria that MKS believes are most important when selecting lasers for TOPCon processing.

• Application Requirements
  • Function
  • Type of Material
  • Thickness of Material
  • Speed
  • Resulting Size of Heat Affected Zone (HAZ)
• Laser Specifications
  • Wavelength
  • Power
  • Pulse Width and Repetition Rate
  • Stability

• IceFyre^® Picosecond Lasers are recommended for patterning cells to create LCOs and offer exceptional performance and unprecedented versatility at industry-leading cost-performance.

	IceFyre®
Wavelengths	UV
Power	Up to >50 W
Pulse Width	<12 ps
Repetition Rates	Single Shot to 10 MHz
Max Pulse Energy	Up to >60 µJ
Other Features	24/7 industrial reliability TimeShift™ technology for pulse control Laser/controller in single, compact package

• Talon^® Diode-Pumped Solid State Q-Switched Lasers are recommended for ablation as part of the LDSE process and offer a superior combination of performance, reliability and cost.

	Talon
Wavelengths	Green
Power	Up to >70 W
Pulse Width	<25 or <43 ns
Repetition Rates	0 to 500 or 700 kHz
Max Pulse Energy	Up to 1000 µJ
Pulse-to-Pulse Energy Stability	<5% rms or better
Other Features	Laser/controller in single, compact package 24/7 industrial reliability E-Pulse™ technology for superb stability

• Stages that MKS ships meet or exceed the guaranteed specifications
• Metrology reports included with each stage (ASME B5.57 and ISO 230-2 standards)
• Typically, the product will perform ~2x better than the guarantee

The HybrYX^® G5 combines the precision of air bearings with the cost-effectiveness of mechanical bearings for large payloads.

Highest load capacity and speed of all linear motor stages for demanding production environments

High load capacity, long travel, fast movement capable of high-duty cycles in industrial applications

High load capacity, mid-travel, fast movement capable of high-duty cycles in light industrial applications

Even with the advantages that lasers provide over traditional tools, lasers systems can degrade over time, leading to reduced output power or a change in focus. This, in turn, could result in lower quality laser operations. Therefore, it is very important to monitor your laser beam frequently, and the critical parameters of the laser should be checked before and after each important step of the laser manufacturing process.

MKS offers a comprehensive portfolio of power sensors. Shown here are examples of sensors designed to measure optical output power of short-pulsed lasers, such as IceFyre and Talon that operate in ps and ns pulse widths.

• Laser Thermal Power Thermal Sensors: very high damage thresholds for hundreds of watts power measurement.

	F150(200)A-CM-16	30(150)A-SV-17	F80(120)A-CM-17
Spectral Range	0.248-9.4 µm	0.19-11 µm	0.248-9.4 µm
Power Range	300 mW - 200 W	100 mW - 150 W	100 mW - 120 W
Energy Range	50 mJ – 200 J	50 mJ – 300 J	50 mJ – 200 J
Max Avg Power Density	35 kW/cm2	60 kW/cm2	35 kW/cm2
Max Energy Density (2 msec)	45 J/cm2	50 J/cm2	45 J/cm2
Aperture	Ø16 mm	Ø17 mm	Ø17.5 mm
Response Time	3 sec	1.7 sec	2 sec
Other Features	Not water-cooled

The recommended products above are the most popular models for TOPCon Processing. We have a lot more than these and you can use our online tools to find the ones that best fit your requirements.

• Sensor Finder and Laser Fluence Calculator

Power Meters		Virtual Power Meters
Centauri	StarBright Handheld	Juno+	EA-1
Extensive graphic displays on 7-in full color touchscreen display Advanced measurement processing Single- or dual-channel versions USB and RS-232 interfaces, with user-friendly software application Analog and TTL output External trigger input	Portable use For transmission checks "in the field" Variety of measurement modes and displays USB & RS-232 interfaces	USB connection to use PC as monitor User-friendly software Extensive graphic displays of data Advanced measurement processing Data logging	Ethernet adapter enables remote control and monitoring of sensor Telnet, HTTP and UDP protocols supported Interact with sensor through custom software or MKS user-friendly software Data logging

• SP932U Beam Profiling Camera: high resolution, real-time viewing and measuring of laser structure with highest accuracy in the industry.

	SP932U
Spectral Range	190-1100 nm
Damage Threshold	50 W/cm2, 1 J/cm2, <100 ns pulse width
Beam Sizes	34.5 µm to 5.3 mm
Pixels	2048 x 1536 Effective Pixels, 3.45 µm Pixel Size
PC Interface	USB 2.0
Other Features	BeamGage® software included UltraCal™ correction algorithm Measures cross-sectional intensity 72 dB true dynamic resolution 24 Hz frame rate in 12-bit mode

• Wavelength
• Laser Damage Threshold
  • Substrate Material
  • Coating
• Reflectivity/Transmission
• Size and Shape

High-energy laser mirrors optimized for 355 nm offer very high reflectivity and damage thresholds, and standard broadband metallic mirrors offer a more economic option for good performance and value over very broad spectral ranges.

High-energy lenses optimized for 355 nm offer very high transmission and damage thresholds, and standard fused silica lenses offer good performance and value over very broad spectral ranges.

Highest laser damage resistance and lowest reflection loss

Optimized for 355 nm, these cubes offer high damage thresholds, efficient polarization, and high extinction ratio.

Very high damage threshold, low sensitivity to temperature and wavelength variation.

• Resolution/Sensitivity
• Long Term Stability
• Lockable
• Size and Shape

Optical component mounts are needed to hold and adjust optics. Long term stability and low drift is crucial. Minimizing drift caused by vibrations or thermal drift over time will ensure laser alignment to the desired spot and also reduce any potential downtime due to misalignment and errors. Having a locking mechanism on these mounts can also prevent misalignment of the beam, especially during shipping and also if anything else happens during usage.

HVM industrial mounts are recommended for robust long term usage in compact space. The Suprema^® mirror mount is excellent for its stainless steel construction that gives better thermal performance than an aluminum mirror mount. Ultra-fine 254-TPI adjusters provide alignment sensitivity as low as 1.5 arc sec. For applications that are really concerned about the thermal changes that can be potentially caused by prolonged high powered laser usage, the ZeroDrift™ version will compensate for some thermal changes as well. For those mirror mounts that need to be set-and-forget for a long period of time, we recommend the MFM flexure mirror Mount. These are excellent for their small footprint so that machine size can be reduced.

• Suprema® Stainless Steel Mirror Mounts: the industry's best thermal performance for long-term stability.
• M-Series Aluminum Mirror Mounts: the new standard for affordable mounts.

	Suprema	M-Series
Optic Diameters	0.5, 1 and 2 in.	0.5, 1 and 2 in.
Resolution	50, 100, 127 and 254 TPI	100 TPI
Angular Range	±7°	±4°
Material	Stainless Steel	Aluminum
Drive Types	Knob Hex Key Exchangeable Actuators	Knob Hex Key
Lockable Versions	Yes	No
Other Versions	Clear-Edge Front- and Rear-Loading Right- and Left-Handed Low Wavefront Distortion ZeroDrift™	Clear-Edge Front- and Rear-Loading Right- and Left-Handed

• HVM Top-Adjust Mirror Mounts: for use in compact spaces so your hands do not have to cross the beam path for adjustment.
• MFM Flexure Mirror Mounts: designed for "set and forget" applications.

	HVM-Series	MFM-Series
Optic Diameters	0.5, 1 and 2 in.	0.5, 0.75 and 1 in.
Resolution	80 and 100 TPI	80 and 100 TPI
Angular Range	±2.5°, ±3° and ±3.5°	±2.5°
Material	Anodized Aluminum, Stainless Steel	Stainless Steel
Drive Types	Hex Key	Hex Key
Lockable Versions	Yes	No
Other Features	Front- and Rear-Loading Versions	Shock Resistant Front- and Rear-Loading Versions Adhesive wells for permanent mounting

• A-Line™ Fixed Position Lens Mounts: fast, easy and economic mounting, aligning and focusing of optics.
• Compact Lens Positioners: ideal solution for applications with limited table space.
• LP Precision Multi-Axis Lens Positioners: highest performing lens positioners.

	A-Line	Compact	LP-Series
Optic Diameters	0.5 to 3 in.	0.5, 1 and 2 in.	0.5, 1 and 2 in.
Resolution	-	100 TPI	100 TPI
Adjustments	Fixed	XY, XYZ, XYZθxθy	XY, XYZ, XYZθxθy
Material	Aluminum	Aluminum	Aluminum
Other Features	Self-aligning design Large clear aperture Compatible with A-Line alignment system	Adapters for other optics Lockable positions	Zero-freeplay XY mechanism True Gimbal adjustments Independent non-influencing locks Adapters for other optics

• Ultima® Gimbaled Cube/Prism Mount: precision alignment of beamsplitter cubes and prisms.
• RSP High Performance Optic Rotation Mounts: smooth, continuous 360° rotation of optics.

	UGP-1	RSP-Series
Optic Size	0.5 and 1 in. cube	1 and 2 in.
Resolution	100 TPI	4 arc min
Angular Range	±5°	360°
Material	Aluminum	Aluminum
Drive Types	Knob w/ Hex Hole	Coarse: knurled edge Fine: knob
Lockable	Yes	Yes
Other Features	True gimbal motion Adapters for other optics	Full ball bearing races Adapters for other optics

• PX Forkless Optical Pedestals: Long-term stability of a pedestal at 1/3 the space.

	PX Post	PX Pedestal
Diameter	1 in.	1 in. with 1.25 in. flange
Heights	1, 2, 3 and 4 in.
Material	Stainless Steel
Other Features	Accessories for varying heights and mounting configurations