ASML Temperature Sensor Assembly with PT1000 Probe 4022.481.27732

Assembly Overview

The ASML Temperature Sensor Assembly, part number 4022.481.27732 (also known as 37437), is a high‑precision resistive temperature detector (RTD) assembly designed for monitoring critical thermal points within photolithography equipment. It combines a PT1000 sensing element with a stainless‑steel sheath, a flexible cable, and a miniature connector, providing reliable and accurate temperature feedback for process control and thermal compensation.

Sensor Element and Performance

The sensing element is a platinum thin‑film RTD with a nominal resistance of 1000 Ω at 0 °C, conforming to IEC 60751 Class A standards. The assembly offers excellent stability, with a temperature coefficient of 0.385 Ω/°C. The probe is encapsulated in a 316L stainless steel tube (outer diameter 3 mm, length 50 mm) with a hermetically sealed tip. The response time (time constant) is 2.5 seconds in stirred water, and 8 seconds in still air, making it suitable for both liquid and gas temperature measurements.

Electrical and Mechanical Specifications

• Sensor Type: PT1000, 4‑wire configuration (for lead compensation)

• Resistance at 0 °C: 1000 Ω ±0.06 %

• Temperature Range: –50 °C to +300 °C (continuous)

• Accuracy: ±(0.15 + 0.002·|T|) °C (IEC 60751 Class A)

• Insulation Resistance: > 100 MΩ at 100 V DC (between element and sheath)

• Cable: Teflon‑insulated, 4‑conductor, 2 m length, shielded

• Connector: LEMO 4‑pin (keyed, push‑pull locking)

• Protection Rating: IP68 (when mated)

Application in Lithography Systems

This sensor is typically installed on the wafer stage, reticle stage, or immersion fluid supply lines to monitor thermal drift. The PT1000 provides the high resolution needed to detect sub‑0.01 °C changes, which is crucial for compensating focus and overlay errors caused by thermal expansion of optical components. The 4‑wire connection eliminates lead resistance errors, ensuring that the measured resistance corresponds exactly to the temperature at the probe tip. The sensor’s output is fed into a precision bridge circuit or a 24‑bit ADC on the system’s environmental control board.

Installation and Mounting

Mount the probe by inserting it into a thermowell or using a compression fitting. The sensor is not threaded; it can be clamped using a standard M3 set screw. Route the cable away from high‑voltage lines and moving parts. Connect the four wires to the corresponding terminals of the measurement board: red and white for excitation current, blue and green for sense. The shield wire should be grounded at the controller end only. Ensure that the cable has sufficient slack to allow stage motion without tension.

Calibration and Verification

Each assembly is factory‑calibrated at three points (0 °C, 100 °C, and 200 °C) with a certificate provided. In the field, periodic verification can be done using an ice‑water bath (0 °C) and a boiling water bath (100 °C), taking into account local atmospheric pressure. The measured resistance should match the standard table within the specified tolerance. If drift is observed, the system’s offset and gain coefficients can be adjusted via the calibration menu. Do not attempt to disassemble the probe; it is sealed and not repairable.

Maintenance and Troubleshooting

Inspect the cable for cuts or abrasions regularly. Clean the connector with contact cleaner if oxidation is suspected. Common fault indications: “Sensor Open” – check the continuity of each wire (should be < 10 Ω); “Short Circuit” – verify that no wire is touching the sheath. If the measured temperature jumps erratically, look for electromagnetic interference; ensure the cable shield is properly grounded. The sensor is passive, so no firmware updates are required. For replacement, order the exact part number 4022.481.27732 to maintain compatibility with the mounting geometry and cable length.