Thermally stable photoresist polymer

Abstract

A new photoresist stable to 500°C has been developed. The addition of potassium dichromate to a polyamic acid, believed to be the condensation product of pyromellitic dianhydride and 4,4′‐diaminodiphenylether, results in a photosensitive polymer which can be cast or spun. The resultant film after exposure, development and post‐bake is a crosslinked aromatic polyimide. An efficient developing solution consisting of a 5:1 mixture of hexamethylphosphoramide and dimethylsulfoxide has been discovered. The system has been fully characterized in terms of composition, film formation, exposure, development, hardening and removal. This material has already proven useful as an area‐controlled, thermally stable dielectric and as a sputter‐etch resist. It has been demonstrated that under the conditions of sputter‐etching (bombardment of substrate with Ar, Ar+ species with energies from 1–300 eV) commercial photoresists, of the polyisoprene variety, char to the extent of being ineffective as a masking material. Under these same conditions, the thermally stable resist retains its film integrity and uniform sputter‐etch rate. An exemplary processing sequence is included as an appendix.

Structure And Properties Of BPDA-PDA Polyimide From Its Poly(Amic Acid) Precursor Complexed With An Aminoalkyl Methacrylate

“…Here, the residual stress (or) was calculated from the radii of wafer curvatures before and after polyimide film deposition, using a simple equation [12] valid under tF << t,; Or = {EstS(tU(1-vs))(IIRF -1/R_) (1) Here, the subscripts F and S denote polymer film and substrate, respectively. The symbols E, v, a, and t are Young's modulus, Poisson's ratio, stress, and thickness of each layer material.…”

“…Since Kerwin and Goldrick [1] reported a photosensitive polyimide (PSPI) in 1971, several PSPIs, including both negative [2][3][4][5] and positive acting types [6][7][8][9] , have been developed. PSPIs have recently gained great attention in the microelectronics industry due to the simple fabrication process based on their direct patternability.…”

“…PSPIs have recently gained great attention in the microelectronics industry due to the simple fabrication process based on their direct patternability. In general, PSPI is a polyimide precursor type [1][2][3][4][6][7][8] or a prelmidized soluble polyimide type [5,6,8,9]. The former type of PSPI is possible from any polyimide precursor, whereas the latter type is very much limited to a few soluble polyimides.…”

Synthesis and Characterizations of Positive-Working Photosensitive Polyimides Having 4,5-Dimethoxy-o-Nitrobenzyl Side Group

“…Recently, photosensitive polyimides (PSPIs) have attracted a great attention because they can reduce processing steps significantly. [8][9][10] Initially, the most widely investigated are the negative-working PSPIs, in which the UV-exposed part becomes insoluble via photocrosslinking or photo-polymerization reaction, while the unexposed part remains soluble in developing solution. More recently, these negative-working PSPIs have been replaced by the positive-working PSPIs because of several reasons.…”

Synthesis and evaluation of photolytically and thermally crosslinkable polyimide copolymers with diacetylene functionality

“…This was realized as early as 1971 by Kenvin and Goldrick of Bell Laboratories. 2 Requirements for making photoimagable polyimide systems practical for real semiconductor production are extremely high. The basic criteria for evaluating such system have been photospeed, processability, resolution, purity, thermostability, and water uptake.…”