HPR 506 photoresist used as a positive tone ion resist

A positive tone photo resist HPR 506 (Olin Microelectronic Materials) has been investigated for its performance under ion exposure. Experiments have been conducted with light ions (H⁺ and He⁺) in the ion projector IPLM 02 (IMS; Vienna) at an energy of 75 keV. The resist resolution proved to be ∼180 nm which is not as good as the projector resolution of below 80 nm as demonstrated with Polymethylmetacrylate. The sensitivity of HPR 506 resist in positive tone amounts to 1.2×10¹³ H⁺ ions/cm² and 6×10¹² He⁺ ions/cm² with contrast numbers of 3.3 and 3.2, respectively. The dose gap between positive and negative mode is sufficiently high (factor of 3) to guarantee a good process stability. The exposure latitude for He⁺ exposure has a value of 15 nm. The sensitivity does not oscillate with resist thickness like in optical lithography. These performance data confirm that HPR 506 resist can be used for mix and match exposure in ion projectors and i‐line steppers.