AES AND HRTEM STUDY OF AN A-SINX-H W/WSIX/A-SINX-H MULTILAYER STRUCTURE REALIZED BY PEVCD/

A multilayer insulator-metal-insulator capacitive structure was realiz ed by plasma-enhanced chemical vapour deposition for a discharge frequ ency of 35 kHz. The chosen materials were amorphous hydrogenated silic on nitride as the insulator and tungsten as the metal. An interlayer o f tungsten silicide used as an adhesion layer is deposited between W a nd a-SiN(x):H. An AES depth profiling study coupled with high-resoluti on transmission electron microscopy observation showed the presence of interphases: the interfacial zone between a-SiN(x):H and W is constit uted by a WN(x) interphase approximately 10 nm deep. Small crystallite s are observed in tungsten-based materials. The presence of a mixed ph ase containing tungsten, silicon, nitrogen and a small amount of oxyge n is obvious and noticed on the AES spectra at the WSi(x)/a-SiN(x):H i nterface: its thickness appears to be approximately 7 nm.