Tunnel Oxide Passivated Contact (TOPCon) Processing

One technology which shows promise of meeting the growing demands of solar panel quantity, performance and cost-effectiveness is TOPCon, or tunnel oxide passivated contact, technology. TOPCon has been gaining in popularity recently, and in fact, some analysts suggest that TOPCon may be the leading PV panel technology by late 2024.

Improving TOPCon Performance with Lasers

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.

MKS Solutions for TOPCon Processing

Challenges in TOPCon Processing MKS Solutions
Selective removal of targeted materials UV and green lasers to ablate required materials
High power/high fluence optics to manage the lasers
Precise, repeatable control of manufacturing process Lasers with versatile and consistent pulse control
Power meters and beam profilers to ensure optimal laser output
High precision and repeatable motorized positioners
Robust, stable optical mounts
Preventing collateral damage, contamination or particle generation Ultrafast lasers for highest quality micromachining
High yields and throughput to reduce costs High-power, precise lasers
Power meters and beam profilers to ensure optimal laser output

Your Partner for TOPCon Processing

  • 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

Lasers

Criteria for Selecting Lasers

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

Picosecond Lasers

  • 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 IceFyre_1064-50
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

Nanosecond Lasers

Talon
Wavelengths Green Talon
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

Motion Control

Guaranteed Motion Control Performance

  • 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

HybrYX® G5 Air & Mechanical Bearings Positioning System

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

X-Axis Y-Axis
Travel Range 450 mm 1400 mm
Speed 300 mm/s 600 mm/s
Peak Acceleration 0.15 G 0.25 G
Load Capacity 40 kg
Accuracy ±3 µm
Y-axis Straightness 1 µm
XY Flatness

0.6 µm (300 mm circle)
Speed Stability 0.1%
Other Features

Z-Tip-Tilt-θ option

IDL-LM Series Industrial Linear Motor Stages

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

IDL-LM Series
Travel Range 100 to 1200 mm
Speed 2000 mm/s
Load Capacity 450 to 2,000 N
Accuracy ±2 to ±5 µm
Repeatability ±0.25 to ±0.5 µm
Pitch ±15 to ±65 µrad
Yaw ±15 to ±40 µrad
Other Features Ironless Linear Motor
Recirculating ball bearings
Industrial grade hard covers

IMS Series Long-Travel Aluminum Linear Positioners

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

Stepper Motor DC Motor
Travel Range 300 to 600 mm
Speed 100 m/sec 200 mm/sec

Repeatability

±0.75 µm

±0.2 or ±0.75 µm
Load Capacity 600 N
Pitch ±37 to ±50 µrad
Yaw ±15 to ±30 µrad
Accuracy ±2.5 to ±4 µm
Other Features Double-row recirculating ball bearings
Linear motor version available

ILS Series Mid-Travel Aluminum Linear Positioners

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

Stepper Motor DC Motor
Travel Range 50 to 250 mm
Speed 50 m/sec 100 mm/sec
Repeatability ±0.4 to ±0.6 µm ±0.4 to ±0.6 µm or
±0.1 to ±0.15 µm
Load Capacity 250 N
Pitch ±15 to ±42 µrad
Yaw ±12 to ±25 µrad
Accuracy ±0.6 to ±1.7 µm
Other Features Double-row recirculating ball bearings
Linear motor version available

Motion Controllers

XPS-D
XPS-D		 XPS-RLD
XPS-RLD
  • High performance, complex motion trajectories
  • Up to 8 axes
  • Extensive analog and digital I/O
  • Can synchronize galvos and positioners
  • Best for the most demanding applications
  • High performance, complex motion trajectories
  • Up to 4 axes
  • Analog and digital I/O
  • Can synchronize galvos and positioners
  • Good for demanding R&D and low volume production

Laser Beam Analysis

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.

Laser Power Sensors

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.

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 laser-power-energy-meters
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.

Power Meters

Ophir laser power and energy meters work on the smart plug principle. This means that almost any power meter can work – plug and play – with almost any of the wide range of Ophir optical sensors.

Power Meters Virtual Power Meters
centauri
Centauri		 StarBright
StarBright Handheld		 Juno+
Juno+		 EA-1
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

Beam Profilers

SP932U
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

Optics

Criteria for Selecting Optics

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

High-Energy Laser Mirrors

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 Laser Mirrors
Wavelength 355 nm
CW Damage Threshold 3 kW/cm2
Pulsed Damage Threshold 3.5 J/cm2 @ 10 ns, 20 Hz
Reflectivity Rs > 99.7%
Rp > 99%
Diameter 1 and 2 inch
Substrate Material UV Grade Fused Silica
Angle of Incidence 45°

High-Energy Plano-Convex Lenses

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.

High-Energy Spherical Lenses
Wavelength 355 nm
Pulsed Damage Threshold 15 J/cm2 @ 20 ns, 10 Hz
Average Reflectivity per Surface < 0.25%
Diameter 1 inch
Substrate Material High Purity Fused Silica

Nanotexture Surface Lenses

Highest laser damage resistance and lowest reflection loss

Nanostructure Surface Fused Silica Plano-Convex Lenses
Wavelength 250 to 550 nm
CW Damage Threshold 15 MW/cm2
Pulsed Damage Threshold 35 J/cm2 @ 10 ns, 1064 nm
Reflection Loss 0.1%
Diameter 0.5 in.
Shapes Plano-Convex or Plano-Concave
Substrate Material High Purity Fused Silica
Other Features Sub-λ AR nanotextures etched directly into surface (no thin film coatings)

High-Energy Polarizing Cube Beamsplitters

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

High-Energy UV Polarizing Cube Beamsplitters
Wavelength 355 nm
Pulsed Damage Threshold 5 J/cm2
Reflectivity Rs > 99%
Transmission Tp > 90%
Extinction Ratio Tp/Ts >200:1
Size 1 in.
Substrate Material UV Grade Fused Silica

Other Features

Optically contacted, no cement

Zero-Order Waveplates (λ/4 and λ/2)

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

Zero-Order Waveplates
Wavelength 355 nm
CW Damage Threshold 2 MW/cm2
Reflectivity per Surface < 0.25%
Diameter 0.5 and 1 in.
Substrate Material Quartz
Temperature Coefficient 0.0001 λ/°C
Other Features ±λ/300 retardation accuracy

Opto-Mechanics

Criteria for Selecting Optical Mounts

  • 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
Suprema		 M-Series
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-Series
HVM-Series		 MFM-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
A-Line		 Compact
Compact		 LP-Series
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
UGP-1
UGP-1		 RSP-Series
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 Post PX Pedestal
Diameter 1 in. 1 in. with 1.25 in. flange forkless-optical-pedestals
Heights 1, 2, 3 and 4 in.
Material Stainless Steel
Other Features Accessories for varying heights and mounting configurations