Glasse phosphosilicate

BSG = borosilicate glass PSG = phosphosilicate glass MOS = metal oxide semiconductor. 

Although the majority of NAA applications have been in the area of bulk analysis, some specialized uses need to be mentioned. One such unique application is the measurement of phosphorus in thin films (about 5000 A) of phosphosilicate (PSG) or borophosphosilicate (BPSG) glasses used in VLSI device fabrication. In this case,... 

A widely used glass is phosphosilicate (PSG), which is used extensively in semiconductor devices as a passivation and planarization coating for silicon wafers. It is deposited by CVD by the reaction of tetraethyl orthosilicate (TEOS) (C2H50)4Si, and trimethylphosphate PO(OCH3)3, in a molecular ratio corresponding to a concentration of 5 to 7% P. Deposition temperature is usually 700°C and pressure is 1 atm. 

For instance, doped phosphosilicate glasses used in planarization cannot be heated above their flow temperature of 725°C. Likewise, after a layer of aluminum is deposited, subsequent temperatures cannot exceed 380°C because spiking and the formation of hillocks would occur rapidly (see diffusion barrier in the following chapter). The factor of time at a given temperature is just as important, as it will influence phenomena, such as diffusion and dissolution. In the planning of a CVD process, the sequence of events and the thermal budget are essential considerations. 

NHE OCP ONO OPS PCD PDS PL PLE PMMA PP PP PS PSG PSL PTFE PVC PVDF normal hydrogen electrode (= SHE) open circuit potential oxide-nitride-oxide dielectric oxidized porous silicon photoconductive decay photothermal displacement spectroscopy photoluminescence photoluminescence excitation spectroscopy polymethyl methacrylate passivation potential polypropylene porous silicon phosphosilicate glass porous silicon layer polytetrafluoroethylene polyvinyl chloride polyvinylidene fluoride... 

Abbreviations used. TEOS, tetraethylorthosilicate PSG, phosphosilicate glass BHF, buffered HR 2.3% HF + 2.1%HN03. 

E. H. Snow and B. E. Deal, Polarization phenomena and other properties of phosphosilicate glass films on silicon, /. Electrochem. Soc. 113, 263, 1966. 

Figure 4.21. Si spectra of alkaline-earth phosphosilicate glasses of composition 0.3MO-0.05Si02-0.65P205, showing evidence for Si in 6-fold and possibly 5-fold coordination. From Yamashita et al. (2000), by permission of Elsevier Science.

Phosphosilicate glasses. The formation of phosphosilicate glasses by thermal treatment of gel precursors has been studied by P MAS NMR (Clayden et al. 2001). The dried gels were found to consist of siloxane frameworks containing trapped... 

Figure 12.18. Si MAS NMR spectra of lead phosphosilicate glasses (After Prabakar etal., 1991).

Phosphosilicate glass films have been obtained with low-temperature oxidation of hydrides ... 

SiC>2. The same also holds for other glass films prepared in a similar way, such as phosphosilicate and arsenosilicate [106,115,128,129,141,142]. 

The details on the fabrication procedure can be found in Liu et al. [2]. In the first step, phosphosilicate glass sacrificial thin film is deposited on top of the silicon substrate. This thin film is patterned to form mesas on which... 

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