Assessing the Oxidative Degradation of N-Methylpyrrolidone (NMP) in Microelectronic Fabrication Processes by Using a Multiplatform Analytical Approach

Figure 6

Proposed degradation chemistry mechanisms. (a) The reaction may proceed via three different pathways. Pathway I: The attack of OH radicals proceeds via a hydrogen abstraction on the CH₂ group adjacent to the amine group of NMP being NMS the main degradant. Pathway II: The attack of OH radicals proceeds via a hydrogen abstraction on the methyl group of NMP leading to the formation of FP. Pathway III: This pathway is more speculative than pathways I and II, and it may proceed via a ring opening mechanism, leading to the formation of NM4ABA. (b) Degradation pathways for minor impurities have also been proposed and it was like the proposed pathway II. N-Methyl-4-aminobutanoic (NM4ABA), N-methylsuccinimide (NMS), 5-hydroxy-N-methylpyrrolidone (5-HNMP), 1-formyl-2-pyrrolidone (FP), 1-acetyl-2-pyrrolidone (2-NEP), and 1-(2-Hydroxyethyl)-2-pyrrolidone (2-AP).

(a)

(b)