Photoresist Action Spectrum Measurement
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Photoresist is a chemical substance that becomes insoluble by exposure to ultraviolet light. (Please SCROLL DOWN to review our selection of light meter systems for use in photoresist applications.) Photoresist is used to form patterns for industrial processingPhotoresist is a light-sensitive chemical substance that is used to form a coating on a surface or substrate. This coating can then be exposed to a specific band of light, referred to as the photoresist’s action spectrum, to affect a desired change in the photoresist. This change causes the photoresist to either become soluble or insoluble to another chemical called the developer which will be washed over the photoresist. Once developed, the photoresist that has been exposed to light in the action spectrum either remains or is washed away leaving a pattern that can then be used for further processing such as chemical etching, engraving, or lithography. |
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Photoresist sees widespread use in numerous technologies including micromachiningPhotoresist is extensively used in the printed circuit board industry where the patterns created by its use layout the circuit connections or traces of printed circuit boards through the use of etching chemicals. Another heavy user of photoresist is the semiconductor industry, where it is a crucial step in the photolithographic production of micro-patterns that are used to form the tiny circuits of individual semiconductor devices. Photoresists have also found use in Biomedical engineering, holography, and micromachining. The last application, micromachining, is a rapidly advancing arena in industrial technology. Also referred to as MEMS, short for MicroElectroMechanical Systems technology, micromachining has driven the use of photoresist to remarkable new heights. Special photoresists and substrates are carefully processed and developed repeatedly in micro-sized layers, forming fully functional micro-sized circuits, structures, and even entire machines such as gear sets, valves, mirrors, sensors, and gyroscopes. Some MEMS devices can be as small as a single micrometer. DLP or digital light processing is a technique used in modern projection television sets that utilizes a microchip with thousands of microscopic mirrors on its surface, manufactured through MEMS technology, along with a light source to create smooth, high-contrast, jitter-free images. |
Controlling the exposure of photoresists is critical to maintaining production
Many photoresist types exist to suit a large variety of applications, and the action spectra can vary from one to the next. It is critical to control the action spectra exposure settings, both the intensity of the light and the time of exposure, to avoid wasteful under or overexposure of the photoresist during processing and production.
To maintain these settings, a light meter with a spectral response as close to the photoresist’s action spectrum as possible is required to get an accurate idea of how well the photoresist is being exposed. Further complicating matters is the processing equipment where photoresists are exposed are frequently very compact and have minimal room for taking these measurements.
International Light Technologies is committed to providing a variety of unique, photoresist-specific instruments to assist our customers in making these often difficult measurements.
| Application | Common Sources | Spectral Range | ILT System Options Click Links Below |
Measurement Range | Units |
|---|---|---|---|---|---|
| PHOTORESIST | PC board-exposure systems, UVA Sources, UV-Vis Sources |
320-475 nm | IL1700, SED033/A/W | 4.00e-9 to 4.00e+0 | W/cm² |
| 320-475 nm | IL1400, SEL033/A/W | 2.00e-7 to 7.00e-1 | W/cm² | ||
| 320-475 nm | IL1700, XRD140A | 4.44e-10 to 4.44e-1 | W/cm² | ||
| 320-475 nm | IL1400, XRL140A | 2.22e-8 to 7.78e-2 | W/cm² | ||
| 320-475 nm | IL1700, XRD340A | 5.00e-9 to 5.00e+0 | W/cm² | ||
| 320-475 nm | IL1400, XRL340A | 2.50e-7 to 8.75e-1 | W/cm² | ||
| 326-401 nm | IL1700, SED033/B/W | 5.00e-10 to 5.00e-1 | W/cm² | ||
| 326-401 nm | IL1400, SEL033/B/W | 2.50e-8 to 8.75e-2 | W/cm² | ||
| 326-401 nm | IL1700, XRD140B | 1.05e-9 to 1.05e+0 | W/cm² | ||
| 326-401 nm | IL1400, XRL140B | 5.26e-8 to 1.84e-1 | W/cm² | ||
| 326-401 nm | IL1700, XRD340B | 1.05e-8 to 1.05e+1 | W/cm² | ||
| 326-401 nm | IL1400, XRL340B | 5.26e-7 to 1.84e-0 | W/cm² | ||
| 260-400 nm | IL1700, SSD001A | 2.22e-7 to 9.00e-1 | W/cm² | ||
| 260-400 nm | IL1400, SSL001A | 1.11e-5 to 9.00e-1 | W/cm² |
Image courtesy of Sandia National Laboratories, SUMMiTTM Technologies, www.mems.sandia.gov
