idonus proposes an innovative UV illumination system based on the use of high-power LEDs and high-grade microlens arrays. This product finds application in photoresist exposure and is suitable for a wide variety of substrates. Our complete line of UV illumination products addresses photolithography needs for masks and wafers up to 300 mm wide. Customized solutions can be designed to suit your specific requirements (e.g., retrofit on mask aligners, OEM for your future products).

LED BENEFITS

Until recently, mercury arc lamps were the only sources capable of providing high intensity light suitable for UV photolithography exposure. Thanks to the advances in LED technology, UV-LEDs have become a very attractive alternative to the energy-consuming mercury lamps.

Along with the ecological and security aspects, the technical advantages of UV-LEDs as compared with traditional mercury lamps are numerous and significant for photolithography. A foremost advantage of UV-LEDs is that they opeate with consistent emission for very long lifetimes. As a result, daily calibration and maintenance are not required. Furthermore, by being more energy efficient, LEDs have reduced heating, which greatly simplifies system cooling.

Benefits of UV-LED technology

• long lifespan of LEDs, meaning no more consumable required
• no daily calibration required, instantly stable illumination
• instant-on, light is ON only during exposure, no mechanical shutter needed
• low power consumption
• limited heating, implying very low air cooling costs
• no maintenance costs

UV-LED EXPOSURE SYSTEM

idonus has introduced a complete line of UV-LED exposure products. Our systems integrate the most effective UV-LEDs available on the market together with high-grade microlens arrays. They are fully assembled and controlled in-house. Our design features a fully telecentric optics that provides reproducible and uniform illumination conditions over the whole exposure area - i.e., highly homogeneous and stable intensity with very small divergence angles. This cutting edge optics ensures perfectly uniform exposure of the entire substrate, producing cured photoresists with straight sidewalls and enabling precise microstructuring of patterns with micrometer critical dimensions.

PERFORMANCES
Our UV-LED exposure system is available in several standard configurations that can be customized with a multitude of variations (e.g., single or  mixed wavelengths). As a manufacturer of special machines, idonus can also develop fully customized equipments according to client’s specifications (e.g., different exposure area, adapted equipment housing). The main characteristics of our products are given in Table 1. A typical measurement performed during the calibration process is shown in Fig. 3: In the usable exposure area, irradiance inhomogeneity is lower than ±3%. The maximum collimation angle  which is illustrated in Fig. 2 is another important parameter that we systematically characterize. Data shown in Fig. 4 are typical results extracted from measurements performed on our model UV-EXP150S-75. To evaluate , irradiance is measured as a function of the collimation angle: corresponds to the FWHM (full width at half maximum). This threshold is commonly used to consider light energy effectively contributing to photoresist irradiation. Given the performance of our exposure system, about 95% of the energy is enclosed within the collimation angle.

Fig. 3: Irradiance inhomogeneity  Measurements show inhomogeneity lower than ±3%. Typical values extracted from our model UV-EXP100S-75 (square illumination area of 100×100 mm2).