150 mm or 200 mm: choosing a wafer size for a pilot line

Wafer size is the decision that shapes every other purchase on a pilot line. Once you commit to 150 mm (6 in) or 200 mm (8 in), each tool, cassette, carrier and metrology recipe follows.

Both sizes have a large base of used and refurbished equipment, and both are still in active use across MEMS, power devices, photonics and sensors. The choice comes down to your substrates, the process steps you need, the tools you can actually buy, and where you want the line to be in five years. This guide sets out the trade-offs for teams building or extending a pilot line on used tools.

Start from the substrate

The material you work on often decides the question.

• Silicon is readily available in both sizes. For MEMS and sensor work, 150 mm remains common, while 200 mm is standard for many CMOS-adjacent and higher-volume lines.
• Silicon carbide for power devices has been mainly a 150 mm material, with a shift to 200 mm under way at larger manufacturers. Check current substrate availability and price at each size before you commit.
• GaN on silicon is produced on both 150 mm and 200 mm silicon.
• Compound semiconductors such as GaAs and InP are typically smaller, often 100 or 150 mm, which can make 150 mm the natural upper limit.
• Glass, quartz and sapphire substrates come in various sizes and thicknesses; confirm that your handling and chucks suit them.

If your customers or partners will hand you wafers at a particular size, that size usually wins.

The physical differences that matter

The jump from 150 to 200 mm is more than diameter. A 200 mm wafer has about 1.8 times the area of a 150 mm wafer, so more die per wafer, but the change also affects handling.

These differences mean a tool set up for one size cannot simply accept the other. Robots, cassette stations, chucks, edge rings, aligners and flat or notch finders all change. Some platforms were designed to cover a range of sizes with a kit swap, others are fixed.

Tool availability on the used market

Many fabs that moved from 150 to 200 mm decades ago, and later from 200 to 300 mm, released large numbers of tools. The result is a mature used market at both sizes, but the mix differs.

At 150 mm, you find many single-wafer research and pilot tools, mask aligners, compact etchers and deposition systems, as well as older batch furnaces. Lithography at 150 mm is well served by contact aligners and older steppers.

At 200 mm, the used market is dominated by production platforms: multi-chamber etch and CVD systems such as the Applied Materials Precision 5000, cluster PVD tools, vertical furnaces and automated metrology. These tools give production-grade repeatability, but they are larger, need more facilities, and carry more complex software. Demand for 200 mm tools is also strong because many specialty fabs still run at that size, which affects availability and lead time.

A practical check: list every process step you need, then look for at least two available tool options for each step at each size. Gaps show up quickly, especially in lithography and metrology.

Lithography deserves particular attention. A 150 mm line can often run on contact or proximity aligners for most layers, adding a stepper only where resolution or overlay demands it. At 200 mm, used aligners are fewer and steppers and tracks become the norm, which raises the cost and complexity of the patterning module. Metrology follows the same pattern: many tabletop film thickness and resistivity tools accept both sizes, while automated 200 mm metrology is built for cassette handling.

Automation, facilities and footprint

Pilot lines run fewer wafers than production fabs, but they need repeatability and traceability, which is where automation helps.

At 200 mm, cassette-to-cassette handling and recipe management are standard on most production tools. That brings consistent results and data logging but also robot calibration, wafer mapping and host communication to maintain. At 150 mm, more tools are manual or semi-automatic. Operators load wafers by hand, which is flexible for small lots and mixed substrates but adds variation and handling risk.

Consider who will run the line. A small team of engineers may prefer simpler 150 mm tools. A line preparing for transfer to a high-volume partner may value 200 mm automation because the recipes will look closer to the eventual production process.

200 mm production tools tend to be larger and heavier, with more demanding facilities: three-phase power at higher current, process cooling water, more exhaust, sometimes house vacuum and specialty gases with abatement. Cluster tools also need service access around several sides.

150 mm research and pilot tools are usually smaller and more forgiving. If your building has limited floor loading, low ceilings or tight door openings, check the dimensions of the 200 mm tools on your list early. Our pilot lines and small fabs page covers how we plan installations in existing buildings.

Converting between sizes

Many tools can be converted between wafer sizes during refurbishment. Typical changes include chucks, clamp rings, edge rings, robot end effectors, cassette stations, wafer sensors and software parameters. Whether a conversion is practical depends on the platform: some were designed with size kits, others need custom parts.

Conversions are most common when a pilot line wants to bring a few 200 mm tools down to 150 mm to match the rest of the line, or when a research lab wants a larger tool to run smaller wafers. Our wafer-size conversion service describes what we assess before quoting. Bridge tools that handle both sizes, or a few tools kept at a second size for specific steps, are also common.

A decision framework

Answer these questions in order:

1. What size are your substrates now, and what size will they be in five years?
2. Can you source a tool for every process step at that size?
3. Does your building support the facilities and footprint?
4. Who runs the line, and how much automation can they maintain?
5. Will the process transfer to a partner fab, and at what size?

If the answers point to different sizes, pick the size that serves your substrates and plan conversions for the rest.

What we can do

We supply and refurbish 150 mm and 200 mm tools for pilot lines and can convert many platforms between sizes. Send us your process flow and substrate plan, and we will map available tools to each step and flag where a conversion or a second size makes sense. Furnaces can be a long-lead step at either size, so our thermal processing range is a good place to start, and our rigging and transport service can check your building access before you commit to larger 200 mm platforms.