Encapsulation of a gate stack comprising a high-k dielectric material may be accomplished on the basis of a silicon nitride material that is deposited in a sequence of two deposition processes, in which the first process may be performed on the basis of a moderately low process temperature, thereby passivating sensitive surfaces without unduly contaminating the same, while, in a second deposition process, a moderately high process temperature may be used to provide enhanced material characteristics and a reduced overall cycle time compared to conventional ALD or multi-layer deposition techniques.