The removal of silicon nitride during chemical mechanical planarization (CMP) of shallow trench isolation structures occurs through tribological wear-induced conversion of the nitride to an oxide. Hence, silicon nitride removal rate can be drastically reduced if appropriate chemicals that can inhibit this conversion at the surface are added to the CMP slurry. This paper presents data on the effects of numerous amino acids and other chemical additives with ceria abrasives on the removal rate of silicon nitride during CMP. A mechanism is presented that explains the suppression of nitride removal during CMP, observed only with some of the amino acids and proline in particular. (C) 2004 The Electrochemical Society.