Stability of TiB2 as a Diffusion Barrier on Silicon

Abstract

The stability of low-pressure chemical vapor-deposited TiB2 films has been investigated for their potenital use as diffusion barriers between A1 or Cu metallurgy and the Si substrate during post-metal annealing at temperatures ranging from 450-640~ for A1, and 500-800~ for Cu. Although no evidence of intermixing was observed via Rutherford backscattering spectroscopy (RBS) for TiB2/Si samples rapid thermal-annealing (RTA) up to 1080~ pyramid-shape pits in the Si, bounded by (111) planes, were observed using transmission electron microscopy for the samples annealed above 950~ Secondary ion mass spectroscopy depth profiles of B in Si originating from the TiB2 solid source suggested enhanced diffusion after RTA. According to RBS spectra coupled with scanning electron microscopy (SEM) examination, A1/TiB2/Si (pre-annealed) stacks appeared to be stable up to 500~ for 30 min in forming gas. For the stacks with as-deposited (amorphous) TiB2 films, plan-view SEM of A1/TiB2/Si showed very limited reaction with A1 up to 600~ in good agreement with sheet resistance measurements. The as-deposited, amorphous TiB2 films were superior diffusion barriers compared to the annealed, polycrystalline TiB2. No interaction took place between sputtered Cu and an underlying, amorphous TiB2 film up to 750~ 30 min in vacuum. Plan-view SEM, RBS, and sheet resistance measurements showed that the structure started to break down at 775~

Preparation of thin copper films from the vapour phase of volatile copper(I) and copper(II) derivatives by the CVD method

“…It was found that at low pressure and with this substrate material, no growth of the copper film on the substrate occurred at temperatures up to 300 8C. Above this temperature, the growth rate was 10 ± 100 nm min 71 . The film thickness depended linearly on the deposition rate, i.e., the deposition rate was practically the same in each experiment.…”

“…121 Simpler methods for the synthesis of Cu(DPM) 2 , e.g., the reaction of H(DPM) with an aqueous solution of CuSO 4 in the presence of sodium acetate, were developed later. 135 The properties of Cu(DPM) 2 have also been studied rather thoroughly: the crystal structure has been determined; 136 thermogravimetric data have been obtained showing that in a nitrogen atmosphere Cu(DPM) 2 sublimes completely at 240 ± 245 8C; 131,132 its sublimation enthalpy (74.8 kJ mol 71 ) and entropy (132.2 J mol 71 K 71 ) have been determined. 135 Analysis of thermogravimetric curves for a wide range of copper(II) b-diketonates with alkyl groups 131,132 showed that Cu(DPM) 2 is actually the most volatile compound in the series where both ligands are identical (the compounds with different ligands are less accessible synthetically).…”

“…The following variant of the CVD process has been suggested: 158 the vapour of the starting Cu(DPM) 2 was carried with a stream of nitrogen containing hydrogen and was then decomposed on a borosilicate glass substrate in the temperature range from 220 to 400 8C. In this case, the deposition of copper films was rather fast for Cu(DPM) 2 (26 nm min 71 ) at a relatively low SER (1.7 ± 2.7 mO cm at thicknesses 5 50 nm).…”

First-principles study of the elastic and thermodynamic properties of HfB2 with AlB2 structure under high pressure

“…Although more and more new hard materials are synthesized, transition metal-diborides as a kind of hard materials still attract great attention due to their unique physical and chemical properties such as high hardness, high melting point and oxidation [1][2][3][4][5][6][7]. Hafnium diborides (HfB 2 ) is one of the transition metal-diborides with hexagonal AlB 2 structure, which can be applied to thin film resistors [8] and explored as diffusion barriers in microelectronics [9,10]. Because of these properties, HfB 2 has been widely investigated in literatures.…”

Observation of nonstandard Fickian diffusion at the interface of isotopically pure amorphousB11onBaker1, Smith2, Brown3 et al. 1997Phys. Rev. B240100View full textAdd to dashboardCite

“…[1][2][3] While these films are chemically and mechanically stable at ambient temperatures, boron diffusion into the device at elevated temperatures is a possible side effect of such passivation. We became involved in a larger study of diboride diffusion into semiconductors by first examining the diffusion properties of elemental boron.…”