CHEMICAL-VAPOR-DEPOSITION (CVD) OF BOROPHOSPHOSILICATE GLASS-FILMS

Chemical vapour deposition (CVD) has become the standard method for th e fabrication of microelectronic devices for use in the semiconductor industry. In this investigation, it has been used to grow films of sil icon dioxide (SiO2) and borophosphosilicate glass (BPSG) at both atmos pheric and low pressures under various conditions. The growth behaviou r of SiO2 and BPSG films has been investigated as a function of the O- 2/SiH4 ratio. Both processes give a similar trend, with the growth rat es of BPSG being somewhat higher than SiO2. The variation in the growt h rate with O-2/SiH4 ratio has been explained in terms of relative tra nsport and kinetic reaction rates. The effects of temperature on the d eposition rate have also been studied and the activation energy calcul ated showed two distinct regions corresponding to mass transport contr ol and kinetic control regimes. Both BPSG and SiO2 have been annealed under various furnacing conditions. It has been shown that the additio n of boron and phosphorous results in much lower reflow temperatures a nd times. This has a significant bearing on the performance characteri stics of devices. Initial results from rapid thermal annealing (RTA) w ork are also presented, and RTA is shown to be a viable annealing proc ess.