Costa Mesa-based Ceradyne announced this morning that it is in a definitive agreement to acquire SemEquip, Inc., a North Billerica, Mass.-based developer of products for the manufacture of logic and memory chips. Ceradyne said it would pay $25M in cash, plus up to $100M in contingent payments based on revenues from SemEquip, over the next 15 years. SemEquip develops cluster ion implantation sub-systems, and advanced ion source materials which are used in the manufacture of logic and memory chips. Ion implantation is a process used in semiconductor manufacturing to dope silicon wafers with various materials, and early step in the manufacturing of semiconductors.