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Environmental Control Units For Semiconductor Producer: Redefining Precision Temperature and Humidity Tolerances for the Semiconductor Industry

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Introduction

A leading provider of engineering solutions used to produce new chips and advanced display equipment, made a strategic decision to overhaul its suite of mask lithography tools. The wholesale upgrade would include replacing all electronics, lasers, and environmental control units (ECU). The company approached Air Innovations for a custom ECU that could meet stringent temperature and humidity requirements needed to preserve expensive instruments and highly sensitive processes for years to come.

 

Lithography Semiconductor

 

The Challenges

There are several challenges inherent in protecting lithography tools in the semiconductor industry and this project presented many of them. First, since the tools were comprised of several different types of metals of various thicknesses, the rate at which they expanded and contracted was different. The ECU would need to maintain extremely tight temperature tolerances to prevent the metals from moving and disrupting the process of transferring circuits onto the masks.

Second, the lithography tools utilized interferometry to track the distance between a laser and a substrate, and this distance was always changing. If the temperature within the tool fluctuated too much, light beams would be unable to accurately calculate the distance to the substrate, disrupting the circuit writing process. Since accuracy between the laser and plate was calculated at the nanometer level, precision was mandatory. Specifically, in order properly calculate, the lithography tool could not experience more than a +/-0.03C temperature variation.

In addition to temperature changes, the light beams were also sensitive to moisture which can negatively impact interferometry. The ECU needed to control relative humidity (RH) so that the lithography tool would not experience more than a +/- 1% RH variation.

Additionally, as this was a retrofit of an existing design, the ECU would need to be mounted within the exact dimensions available inside the electrical cabinet.

Finally, as there are very specific cleanliness and off-gassing requirements in the semiconductor industry, particular attention was needed to be given to the materials of construction to limit any risk of the ECU contaminating the lithography process.

 

The Solution

Air Innovations engineered, manufactured, and tested a custom ECU for the semiconductor company that would maintain a temperature of 20℃ within ±0.03℃ with 40% RH with ±1% RH. The system included an electric reheater and hot-gas bypass refrigeration control to maintain the tight-tolerance temperature control. The semiconductor control equipment included an ultrasonic DI (deionized water) humidifier to maintain precise RH conditions.

Given the sensitive nature of lithography tools, Air Innovations included various alarms and sensors to fully monitor the operating characteristics of the ECU. All the critical points were transmitted to the customer’s control system for remote monitoring. The ECU included various safeties such as the ability to close valves, shut down, and sound an alarm in the presence of a leak.

The final ECU for the lithography tool was customized to fit a precise footprint of 32” x 25”x 75”, constructed of powder-coated aluminum, and suited with Poron® microcellular closed-cell insulation. The unit was designed to meet S2 and S8 SEMI standards and meets or exceed UL standards.

The semiconductor lithography company was then able to deliver upgrade kits with essential components—including electrical boxes, lasers, and ECUs—to its chip manufacturers. These modules can be retrofitted into existing lithography tools being used in facilities around the world.

Semiconductor SystemThe Result:

The environmental control unit included the following:

  • Set point range adjustable 20℃ to 26℃
  • Set point range adjustable 40-50% RH
  • 1650 CFM design airflow
  • 80 CFM make-up air from surrounding class 10 controlled environment
  • 75” external static pressure
  • Incoming power 208V/3P at 50 or 60 Hz
  • Hot gas bypass refrigeration control
  • Electric reheater
  • Water-cooled refrigeration system
  • Auto-tuning PID loop controllers for temperature and humidity
  • Powder coated aluminum and stainless-steel construction
  • Poron® insulation to minimize outgassing
  • Nominal 1 ton R-134a Scroll Compressor

 

If you’re ready for a custom solution from Air Innovations, like these custom environmental control units, contact us by submitting a Project Inquiry or calling 1-800-835-3268 today.

For case studies on other industries, view our general case studies page. We also have whitepapers covering the aerospace industry, semiconductor industry, and MyZone Systems product line. The whitepaper page can be found here.

Custom Clean Room Temperature Control for Lithography Tool

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The Challenge:

Air Innovations partnered with a semiconductor tool firm to design and build an environmental control unit with once-thru steady-state air to maintain conditions within a semiconductor lithography tool. Inlet air was to be taken from the existing class 1000 controlled environment.Custom temperature control - semiconductor ECU

The unit needed to conform to a precise footprint: 26” x 30”. The clean room temperature was to be maintained at 68°F – 74°F ±0.36°F (±0.2°C). Furthermore, the lithography tool could not experience more than 2°F change in any 1-hour period. This semiconductor customer also requested the unit feature a water-cooled condenser with leak detection and solenoid valves for system shutoff in case of a water leak.

The Solution:

To ensure clean room temperature control accuracy, Air Innovations designed the water-cooled semiconductor HVAC system to include a temperature sensor with an accuracy of ±0.1°F. The final unit also features hot-gas bypass refrigeration control.

Download our semiconductor whitepaper: Pursuing Perfection

This custom environmental control system included a 5kW electric reheater to maintain very limited temperature change in any given hour and in case expected ambient conditions dipped below normal.

The final stainless steel environmental control system for the lithography tool included Poron® microcellular closed-cell insulation, urethane sealants, and closed-cell gaskets. As with all AdvancAir® systems, this unit was also designed to meet SEMI standards, and included non-shedding, non-off-gassing componentry, and a DIP inverter to protect against power drops.

The Result:

  1. All design specifications were met within the 11-12 week lead time (future units would be delivered in 8 weeks).
  2. The environmental control system included cooling, heating, dehumidification, pre-filtration, and HEPA filtration
  3. Design output conditions of 68°F -74°F ±0.36°F (±0.2°C) were met.
  4. 2500 – 4000 CFM variable operational range
  5. 5” external static pressure
  6. Separate auto-tuning PID loop controllers for temperature
  7. Water-cooled condenser with leak detection and hot-gas bypass refrigeration control
  8. The temperature control system can take 3 different voltage inputs: 380-415V/3/50, 200-220V/3/50, or 208-230V/3/60 ±10%
  9. Meets all SEMI and UL certification requirements

If you’re ready for a custom solution from Air Innovations, like this Advancair custom lithography tool cooling system, contact us by submitting a Project Inquiry or by calling 1-800-835-3268 today.

If you would like to see case studies for other industries, view our general case studies page. If you are interested in seeing more case studies for the semiconductor industry, look at the items below. We also have whitepapers available covering the aerospace industry, the semiconductor industry, and our Micro Environments product line. The whitepaper page can be found here.

Semiconductor: Custom ECU for Semiconductor Process Equipment

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The Challenge:

Custom ecu for semiconductor application

Custom ECU for Semiconductor Application

One of the biggest challenges in using lithography in high-volume semiconductor fabrication is photomask defectivity. A global supplier to the semiconductor and photomask making industries asked Air Innovations to create an environmental control unit (ECU) that could service — on demand — any of its nanomachining mask repair tool systems. Extremely tight tolerance was required for both temperature and humidity.

Download our semiconductor whitepaper: Pursuing Perfection

The Solution:

We configured vertical, stainless steel environmental control systems to match the client’s various types of mask-repair tools. The units would be configured to provide recirculated, steady-state air to the mask-repair tool with very specific temperature and humidity controls for optimal tool calibration. The semiconductor process equipment needed to accept a range of incoming power at 208V/3Phase and either 50 or 60 Hz without degradation of overall performance.
Key Specifications:

  • Air temperature controlled to ±0.03°C (set point range is adjustable from 19°C to 23°C)
  • RH controlled to ±1% RH (set point range is adjustable 45-55%)
  • No more than 1°C/5 minutes with a maximum deviation of 3°C (Tool vs Fab)
  • No more than 1% RH/3 minutes with a maximum deviation of 5% (Tool vs Fab)
  • Airflow designed for 600 – 1350 CFM
    • Max. external static pressure of 1.65” at 1350CFM
    • Max. external static pressure of 1.15” at 600 CFM
  • Hot-gas bypass refrigeration control
  • 7.5kW electric reheater

The Result:

Two newly configured systems allowing the customer to communicate with nanomachining mask repair tools anywhere in the world and to gain direct access to the ECU’s controls and diagnostics by simply logging onto the internet through a Windows-based program. In addition, the environmental control unit for the mask-repair test equipment also included the following attributes:

  • Meets UL standards
  • Water-cooled condenser
  • 6 leveling legs
  • 4 seismic tie-downs at the corner leveling legs for safety in seismic hazard zones

If you would like to read case studies for other industries, view our general case studies page. If you are interested in viewing more case studies for the semiconductor industry, look at the case studies attached below. We also have whitepapers available covering the aerospace industry, the semiconductor industry, and our Micro Environments product line. The whitepaper page can be found here.