Modernizing Environmental Control Units For Microchip Manufacturing: Advancing Temperature, Humidity, and Cleanliness Tolerances

Modernizing Environmental Control Units For Microchip Manufacturing: Advancing Temperature, Humidity, and Cleanliness Tolerances

Introduction

A leading provider of engineering solutions to manufacture microchips needed to address equipment components that were about to reach the end of their life. Rather than replacing the fleet of chip manufacturing machines, the company pursued a more cost-effective solution of upgrading the outdated critical machine components. One of the critical components that needed upgrading was the environmental control unit (ECUs) used to preserve the integrity of each piece of equipment.

Since technology had advanced significantly, leaders at the company were in the market for a modernized drop-in replacement unit and turned to Air Innovations for help. Air Innovations had the depth of experience creating customized, high-performance ECUs they sought.

Challenges

In the time since the original environmental control system was designed, microprocessing power had increased significantly. This made the chips even more sensitive to heat, cold, moisture, and debris. Exposure to an imperfect environment compromises the quality of the manufactured microchips, which impacts how well they function within their devices. The first challenge was to design an ECU that was sophisticated enough to meet even stricter requirements.

The second challenge was designing an ECU that could be retrofitted into a relatively small, pre-existing space. Utility connection points were fixed, the supply of conditioned air had to line up with the original unit, and despite having to ensure more precise environmental control, the unit could not be any larger.

Next, since microchip manufacturing occurred in cleanrooms versus open-air factories, routine equipment maintenance would need to be as easy to execute as possible.

Finally, when a process occurs in a cleanroom environment, equipment breakdowns could stall chip manufacturing production for weeks. The Air Innovations solution needed to be robust.

The Solution

Air Innovations designed a one-ton ECU that met all requirements.

First, the unit could maintain a temperature within +/- 0.05 ℉ (+/- 0.03 ℃) with a temperature setpoint range of 68-79 ℉ (20-26 ℃) and humidity setpoint range of 40-50% +/-1% relative humidity. Since these ranges exceed the client’s expectations, the ECU could provide precise climate control even when microchips get smaller and continue to advance.

The heat exchangers used in the original unit were no longer available, so Air Innovations created a custom one with identical utility connection points. The unit recirculated a constant volume of conditioned, precision-temperature air through external carbon and ULPA filters to control the printhead chamber environment.

The ECU incorporated existing system air inlet and air outlet sizes, shapes, and locations and maintained the existing flow rate and direction of airflow.

It was also designed for zero leakage from all pressurized plenum seams, access covers, and fasteners. To prevent moisture from disrupting the chip manufacturing process, the area around the heat exchanger had a drip tray connected to a drain port designed to function using gravity while the ECU operated. Optical surfaces were placed downstream from the ECU to minimize exposure to out-gassing materials to the unit air stream.

Serviceable components like the motor and belt drive were located out of the main air path with removable shields for easy cleaning. Finally, spherical casters were included on the bottom of the ECU for ease of installation and removal.

Phase Two: Designing and Building From Scratch

The semiconductor equipment manufacturer came back to Air Innovations for a second project. This time, the company was looking for Air Innovations to engineer and build new equipment. While the first drop-in replacement ECU controlled the climate using air, the second project would need to utilize air to maintain the environment and a water component to cool the chip manufacturing equipment.

The solution would need two separate streams that provided precise chilled water to cool and protect the manufacturing process. The lasers that cut materials to make microchips generated a lot of heat and could be air-cooled like the first set of ECUs. The back of the laser, however, needed to be water-cooled.

Second Solution

This time, the Air Innovations team engineered a unit with a closed water loop that circulated from the ECU to the back of the laser. The circulating cold water absorbed the heat generated by the laser motor.

The second stream of water came from the building’s water supply to the heat exchanger to remove the heat from the closed water loop and put it into the air.

The Drop-In Replacement Result:

The environmental control unit included the following:

• Set point range adjustable 68-79 ℉ (20-26 ℃)
• Set point range adjustable 40-50% RH +/-1%
• 1000 SCFM design airflow
• 120 CFM make-up air from the top edge of the ECU return air duct
• 75” +/- 0.10” W.G. external static pressure
• Incoming power at 60 Hz
• Re-circulated conditioned air through external Carbon and ULPA filters
• Noise Level Control less than 65 dba within the assembled chamber

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.

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

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.

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.

The 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 1.5 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

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.

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

The Challenge:

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.