THE EFFECT OF AN OXYGEN PLASMA EXPOSURE ON THE RELIABILITY OF A TI TIN CONTACT METALLIZATION/

This article demonstrates that the exposure of a TiN barrier to an ex situ oxygen plasma results in a more stable TiN/AlSiCu interface up to temperatures of 600 degrees C as shown by the time-of-flight elastic recoil detection measurements. A quaternary phase diagram of the Al-Ti -O-N system was calculated in the range of temperatures between 450 an d 550 degrees C and suggests that the stabilization of the TiN/AlSiCu interface is possible since oxidized TiN reacts with Al to form AIN, T iAl3 and Al2O3 at the interface. A Ti/TiN/(oxygen plasma exposure)/AlS iCu/TiN contact metallization in 1.2-mu m-diam and 1.4-mu m-deep strai ght wall contacts to 0.2-mu m-deep N+ and P+ diffusions, to gate polys ilicon as well as to capacitor polysilicon shows stable electrical res ults even after a [(450 degrees C, 60 min)+(500 degrees C, 60 min)+(55 0 degrees C, 60 min)] combined thermal stress. (C) 1996 American Insti tute of Physics.