APPLICATION OF RAPID THERMAL PROCESSING FOR SIMULTANEOUS BPSG AND CONTACT REFLOW, AND POLY EMITTER ANNEAL
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2002-Jan-02
A wide variety of publications are available which While these application& have been well documented, demonstrate the application of rapid thermal process- there is little available thatidemonstrates the successful ing (RTP) to implant anneal/activation, diffusion of application of RTP to simul&xously achieve two or more dopants from polysilicon into silicon, BPSG fusion for of these functions. The first heneration Motorola BiCMOS improved planarity, and reflow of etched contacts to process employes RTP to inneal source/drain implants, improve metal step coverage. The major interest in form shallow poly emitter NpN transistors, and fuse BPSG RTP over conventional furnace annealing is that high to provide a fairly planar s&face. However, as geometries temperatures (> 1OOO'C) for short times (~60 set) can shrink to the one micrometer and less level, further con- be achieved. This provides the advantage of high dopant straints are placed on the brocess. A significant issue is activation, break-up of interfacial oxide (in poly emitters), metal step coverage into neow (O.S& and significant flow of doped dielectric glass, but for contacts. An additional RTP after contact etch can be in- such short times that there is no significant dopant corporated into the process to reflow the BPSG to provide movement. Thus, the shallow junctions and critical a more tapered profile. A&natively, a single RTP could dimensions so critical to high performance circuits can reflow the contacts as welllas satisfy the other functions be maintained. above. A comparison of the 4pproaches is shown in Table 1.