Dieter Pierreux

Influence of the Oxidant on the Chemical and Field-Effect Passivation of Si by ALD Al2O3

Differences in Si surface passivation by aluminum oxide (Al2O3) films synthesized using H2O and O-3-based thermal atomic layer deposition (ALD) and plasma ALD have been revealed. A low interface defect density of D-it = similar to 1011 eV(-1) cm(-2) was obtained after annealing, independent of the oxidant. This low D-it was found to be vital for the passivation performance. Field-effect passivation was less prominent for H2O-based ALD Al2O3 before and after annealing, whereas for as-deposited ALD films with an O-2 plasma or O-3 as the oxidants, the field-effect passivation was impaired by a very high Dit

Atomic Layer Deposition of Strontium Titanate Films Using Sr ( #2#1Cp ) 2 and Ti ( OMe ) 4

Strontium titanate (STO) is a promising candidate as a high-k dielectric for dynamic random access memory application. STO thin films are deposited by atomic layer deposition using Sr( t Bu 3 Cp) 2 , Ti(OMe) 4 , and H 2 O as precursors. Growth and saturation behavior of STO and binary oxides are evaluated by ellipsometry thickness measurements. The precursor pulse ratio controls the amount of Sr and Ti incorporated in STO films. Stoichiometric SrTiO 3 is characterized by the lowest crystallization temperature and largest refractive index, density, and dielectric constant. An excess of Ti or Sr results in an increase in the crystallization onset temperature and contraction or expansion of the cubic cell constant of perovskite SrTiO 3 . Incorporation of more Sr in STO reduces the leakage current density but also increases the capacitance-equivalent thickness.

Composition influence on the physical and electrical properties of SrxTi1−xOy-based metal-insulator-metal capacitors prepared by atomic layer deposition using TiN bottom electrodes

In this work, the physical and electrical properties of SrxTi1−xOy (STO)-based metal-insulator-metal capacitors (MIMcaps) with various compositions are studied in detail. While most recent studies on STO were done on noblelike metal electrodes (Ru, Pt), this work focuses on a low temperature (250 °C) atomic layer deposition (ALD) process, using an alternative precursor set and carefully optimized processing conditions, enabling the use of low-cost, manufacturable-friendly TiN electrodes. Physical analyses show that the film crystallization temperature, its texture and morphology strongly depends on the Sr/Ti ratio. Such physical variations have a direct impact on the electric properties of SrxTi1−xOy based capacitors. It is found that Sr-enrichment result in a monotonous decrease in the dielectric constant and leakage current as predicted by ab initio calculations. The intercept of the EOT vs physical thickness plot further indicates that increasing the Sr-content at the film interface with the bottom TiN...

Influence of in situ applied stress during thermal oxidation of (111)Si on Pb interface defects

The results of a series of experiments are reported in which constant, controlled levels of in-plane stress were applied in situ to oxidizing (111) silicon substrates. Electron spin resonance measurements show that the properties of inherently incorporated electrically active Pb defects at the (111)Si/SiO2 interface are affected; among others, tensile stresses decrease the number of Pbs, while compressive stresses have the opposite effect. The results are in agreement with the generally accepted relationship between Pb-defect generation and interfacial mismatch (stress).

Characterization of S centers generated by thermal degradation in SiO2 on (100)Si

The structural degradation of thermal SiO2 on (100)Si under isochronal vacuum annealing in the range Tan=950 °C–1250 °C was monitored by electron spin resonance (ESR) in terms of point defect creation, including Eγ′, Eδ′, EX and the elusive predominant degradation-center S. Depth profiling after heating at 1200 °C shows that the S centers predominantly reside near the oxide borders, generally in anticorrelation with the Eγ′ distribution. The resulting anisotropic demagnetization effect has enabled inference of the S center susceptibility. As to the nature of the S center, an observed weak hyperfine structure may comply with the S center being of the type SinO3−n≡Si⋅ either the single n=1 or a mix of both the n=1,2 variants.

Novel Batch Titanium Nitride CVD Process for Advanced Metal Electrodes

This article describes a novel CVD process for TiN films developed in a 300 mm Vertical Furnace. We have solved Chlorine incorporation at low temperature inside the TiN layer while at the same time the batch process yields a 3 times higher throughput per dual reactor system compared to a single wafer system with 3 chambers.We show process results for load sizes ranging from 5 to as much as 100 wafers that prove filler wafers are only required to a minimum. Applications of the developed TiN process in Metal-Insulator-Metal memory devices such as Deep Trench DRAM, Stack DRAM, as well as Control Electrodes in Charge trapping Flash memory.

Pb-type interface defects in (100)Si/SiO2 structures grown in ozonated water solution

Si dangling bond interface defects (Pb0,Pb1) were probed by electron spin resonance in entities of (100)Si with ultrathin SiO2 grown in ozonated de-ionized water solution at room temperature. After photodesorption of passivating hydrogen, Pb0 appears with densities up to ∼5×1012 cm−2, a value five times larger than the one standardly attained with high temperature thermal growth. Thus standard quality thermal Si/SiO2 interface properties, as exposed by the Pb0-type defects criterion (interface traps), are not obtained by oxidation in ozonated water solutions at room temperature. The interface quality may be upgraded by providing additional thermal budget. Yet standard qualitity is still not attained after vacuum annealing at 600 °C.

Atomic layer deposition of GdHfOx thin films

GdHfOx thin films were deposited by atomic-layer deposition (ALD) using Tris(isopropyl-cyclopentadienyl)Gadolinium [Gd(iPrCp)3] and HfCl4 in combination with H2O as oxidizer. Growth curves show nearly ideal ALD behavior. The growth per cycle is found to be 0.55 A, independent of Gd/(Gd+Hf) composition in the studied range. This indicates that the amount of HfO2 deposited during an HfCl4/H2O cycle is identical to the amount of Gd2O3 deposited during a Gd(i-PrCp)3/H2O cycle. The film composition can therefore be deduced from the HfCl4/Gd(i-PrCp)3 cycle ratio. The crystallization of GdHfOx with Gd/(Gd+Hf) contents between 9% and 30% was studied. All films crystallize into a cubic/tetragonal HfO2-like phase during spike annealing at 1050°C. Cubic/tetragonal phases are also observed after laser annealing for 1.5 ms up to 1300°C, demonstrating that the cubic/tetragonal phase is thermally stable in this temperature range.

Annealing Induced Degradation of Thermal SiO2 On (100)Si: Point Defect Generation

The structural degradation of thermal SiO2 on (100)Si under isochronal post oxidation vacuum annealing (POVA) has been probed by electron spin resonance (ESR). The degradation process, studied in the range Tan = 950–1250 °C, is established as intense point defect generation including E′γ, E′δ, EX and the elusive predominant degradation center S. Thermally activated generation is revealed over broad Tan ranges for the two most populous defects, S and E′γ, with a common activation energy ∼1.6eV. Depth profiling after heating at 1200°C shows that the S centers predominantly reside near the oxide borders, generally in anticorrelation with the E′γ distribution. The S center susceptibility has been inferred from conventional ESR signal intensity monitoring as well as from revealed anisotropic demagnetisation effects. It is found Curie-Weiss type with critical temperature of ∼ 1.3 K. Newly observed weak hyperfine structure may comply with the S center being an E′-like defect.