Negative photoresists have a chemical structure that allows the areas that are exposed to light to develop at a slower rate than those areas not exposed to light. Example: In theory, isolated lines or islands are best printed in negative photoresist, whereas spaces and contacts prefer a positive resist. With negative resists, exposure to UV light causes the chemical structure of the photoresist to crosslink/polymerize, which is just the opposite of positive photoresists. Instead of becoming more soluble, negative photoresists become extremely difficult to dissolve. As a result, the UV exposed negative resist remains on the surface while the photoresist developer solution works to remove the areas that are unexposed. This leaves a mask that consists of an inverse pattern of the original, which is applied on the wafer (or other substrate).
APOL-LO 3200 Hi-Res Negative Lift-Off
Film Thickness: 2 – 10+ microns
Applications: Compound Semiconductors, LED
APOL-LO 3200 Series resist is a negative tone advanced photoresist with Lift-Off profile for i-Line, and broadband applications. It has improved resolution and a wider process window compared to the original negative lift-off KL1600. It is designed for use with industry standard developers. Custom formulations are available to adjust lift-off angle and the photospeed.
KL NPR Negative with Vertical Profile
Film Thickness: Up to 20 microns
Applications: TSV, electroplating, metal deposition, RIE etch
KL NPR is a negative tone, novolac photoresist designed for electroplating, metal deposition, TSV, and RIE etch. It has a single coat film thickness of up to 20 µm and features vertical sidewalls and high aspect ratios. KL NPR is thermally stable and can withstand temperatures up to 130⁰C without profile degradation.
KL IR Image Reversal
Tone: Positive / Negative
Film Thickness: 1-2 microns
KL IR15 image reversal series of photoresists are used as either positive and negative photoresist in i-line, g-line and broadband applications.
IR15: Designed for straight profiles when used as negative photoresist
IR15 Lift-Off: Designed for lift-off profiles when used as negative photoresist
HARE SQ™ Negative Tone Epoxy
Film Thickness: 2 to 100+ microns
Applications: MEMS, Microfluidics
HARE SQ™ is a negative tone epoxy photoresist designed for polymeric MEMS, microfluidics, micromachining and other microelectronic applications. This resist has excellent chemical, mechanical and thermal resistance, making it suitable for permanent applications. It is fully compatible with SU-8™ processes. It is sensitive to NUV, i-line and broadband wavelengths. HARE SQ uses superior epoxies specially designed for the electronics industry, making improvements in optical transparency, particles and filter-ability, cured surface energy consistency, and photoresist lot-to-lot consistency versus industry competitors.