The present invention provides new stable crystalline N-iodoamides-1-iodo-3,5,5-trimethylhydantoin (1-ITMH) and 3-iodo-4,4-dimethyl-2-oxazolidinone (IDMO). The present invention further provides a process for the preparation of organic iodides using N-iodoamides of this invention and recovery of the amide co-products from waste water.

The present invention provides new stable crystalline N-iodoamides-1-iodo-3,5,5-trimethylhydantoin (1-ITMH) and 3-iodo-4,4-dimethyl-2-oxazolidinone (IDMO). The present invention further provides a process for the preparation of organic iodides using N-iodoamides of this invention and recovery of the amide co-products from waste water.

An onium salt containing a sulfonic acid anion having a substituted fused ring structure and an aromatic sulfonic acid structure is provided. A chemically amplified resist composition comprising the onium salt has satisfactory solvent solubility, high sensitivity, and high contrast, and forms a resist film with improved lithography properties such as EL and LWR.