Chemical studies on 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) were conducted to elucidate its thermal behaviors with water and under various reaction conditions. TMCTS was heated in the presence of 316L stainless steel and in the presence of water. The heated TMCTS then was evaluated using 1H NMR (proton nuclear magnetic resonance) spectroscopy, GC-MS (gas chromatography-mass spectrometry) as a function of time, temperature and residual water concentration. The thermal degradation kinetics of gas-phase TMCTS were investigated using FTIR (Fourier transform infrared) spectroscopy at elevated temperatures. These initial results indicated that TMCTS degradation rates increased with both temperature and water concentration. This work spawned the development of a “dry” TMCTS that is expected to exhibit enhanced thermal stability relative towards uncontrolled decomposition.

This study investigates and compares the deposition of Hf1-xSixO2 films from two suites of metalorganic CVD precursors. The first precursor suite has oxygen coordinated to the Si or Hf center and includes β-diketonate, alcoxide and acetoxy ligands. The second precursor suite has alkylamido ligands, which have nitrogen coordinated to the Hf or Si center. The process space for deposition of silicates was evaluated for controlling the composition of the silicate films while optimizing deposition rates for a manufacturable single-wafer process. The composition of the film, x, is controlled over the entire range by changing the composition of the precursor solution, Si:Si+Hf. The composition of the films, including hafnium, silicon, oxygen, carbon, and nitrogen content were measured by XPS. Both suites of precursors provide routes by which composition can be controlled in fully oxidized films with low carbon and nitrogen content. Film deposition rates are consistent with manufacturing requirements. The interfacial layers that were observed by HRTEM between the film and the substrate were thin (< 10Å) and possibly graded in composition.

Introduction As semiconductor device architectures continue to shrink, small feature/high aspect ratio trench and via structures, including cylindrical capacitors and stacked gate electrodes have become common. These structures are formed in close proximity to each other and can become physically bonded together during aqueous cleaning due to the high surface tension of water during the wetting and subsequent drying of the structures. This phenomenon, called stiction, is a common problem in the manufacturing of micro electro mechanical systems (MEMS) devices. Therefore, removal of contamination on these structures without pattern collapse or stiction is difficult. In addition, conventional aqueous chemistries tend to alter the sensitive low-k interlayer dielectric properties during post-etch or post-ash photoresist residue removal because these materials are organic or porous polymer materials. Supercritical carbon dioxide (SCCO2) provides an alternative method for cleaning fragile fine structures or high aspect-ratio structures. SCCO2 diffuses rapidly, has low viscosity, near zero surface tension like a gas, and thus, can penetrate easily into deep trenches and vias. It also enables more effective cleaning without pattern collapse or stictional degradation, in addition to being more cost-effective and having a lower environmental impact compared to wet cleaning techniques. Recently, SCCO2 compositions containing co-solvents have been used to remove post-etch or postash photoresist residues, both organic and inorganic in nature. We have previously reported the successful removal of particles, removal of post-etch residues, and removal of high-dose ionimplant photoresists by the careful choice of chemical additives in SCCO2 formulations [1]. In this paper, we demonstrate the effects of various chemical additives as well as process temperature and pressure in SCCO2/co-solvent solutions on particle removal efficiency (PRE). Correlation of the particle removal efficiency and substrate layer etch rate will be discussed.

Increasing the elastic modulus and hardness of low K films is one of the key challenges towards integration of these materials into future integrated circuits. Several approaches are explored for increasing the hardness of carbon doped oxide (CDO) dielectrics. Several low K precursors and their mixtures specifically chosen to enhance the hardness (H) and modulus (E) of CDO films through chemically induced cross-linking. Composition and FTIR measurements suggest the presence of C-C and C-Si cross-linking with concurrent observation of improved film hardness and modulus at relatively low deposition temperatures. Films deposited at 373°C using diethoxy-methyl-oxiranyl have a hardness and modulus of 2.5 GPa and 18.1 GPa respectively. Films deposited at 180°C using tetramethylcyclotetrasiloxane (TMCTS) and 25% hardener have hardness and modulus of 1.5 GPa and 9.4 GPa, respectively. These film properties are significantly higher than those observed for TMCTS alone under similar deposition conditions. Based on these results a low temperature process with 25% hardener and 75% TMCTS combined with a porogen was used to produce a porous film with a k<2.5 and a hardness of 0.72GPa.

Three new neutral cis-hexacoordinate bis(beta-diketonato) silicon(IV) complexes, (thd)2SiX2, where X = Me (1), tBuO (2), and tAmO (3), and thd = 2,2,6,6-tetramethyl-3,5-heptanedionato, were synthesized in high yield. Single crystal X-ray crystallographic analysis revealed that 1 was monomeric with cis-hexacoordinate octahedral geometry on the silicon and oxygen atoms. Crystal data: empirical formula C24H46O4Si, crystal system monoclinic; space group P2(1)/n; unit cell dimensions a = 10.4195(5) A, b = 19.7297(10) A, c = 13.6496(7) A; beta = 102.6590(10) degrees; Z = 4. Variable temperature NMR confirmed (thd)2SiX2 maintained cis-geometry in solution by observing two distinct methyl proton resonances (of thd) at room temperature or low temperatures. These compounds show potential for use as low temperature silicon oxide CVD precursors for transition metal silicate high kappa gate dielectrics.

In this paper, we report on the removal of photoresist, post-etch process residues and particles for various patterned semiconductor wafers using supercritical carbon dioxide (SCCO2)/chemical modifier formulations. Optimization of the chemical formulations was determined using data obtained from statistical analysis and designed experiments. Characterization of the processed samples via scanning electron microscopy (SEM), optical microscopy and fourier transform infrared spectroscopy (FTIR) revealed that process conditions and chemical derivatization are important to cleaning patterned wafers. The results of our investigations illustrate the potential of SCCO2 as a viable cleaning technology for nextgeneration integrated circuits.

Hafnium silicate (Hf1−xSixO2) films were deposited by metalorganic chemical-vapor deposition with composition x ranging from 0 to 1 using amide precursors in an organic solvent. The liquid precursors, tetrakis(diethylamido)hafnium, Hf[N(C2H5)2]4, and tetrakis(dimethylamido)silicon, Si[N(CH3)2]4, are compatible when mixed in solution, have high elemental purity, and exhibit a low halogen content. Thin oxide films were deposited with these precursors over a range of wafer temperatures from 400 to 600 °C with very low carbon and nitrogen incorporation. Control of the film composition is attained by changing the ratio of silicon concentration to hafnium concentration in the precursor solution for specific deposition conditions. Composition and growth rate are reported as a function of process condition. Interfacial layers of less than 10 Å were observed by high-resolution transmission electron microscopy.

Chemical studies on 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) were conducted to elucidate its thermal behaviors with water and under various reaction conditions. TMCTS was heated in the presence of 316L stainless steel and in the presence of water. The heated TMCTS then was evaluated using H-1 NMR (proton nuclear magnetic resonance) spectroscopy, GC-MS (gas chromatography-mass spectrometry) as a function of time, temperature and residual water concentration. The thermal degradation kinetics of gas-phase TMCTS were investigated using FTIR (Fourier transform infrared) spectroscopy at elevated temperatures. These initial results indicated that TMCTS degradation rates increased with both temperature and water concentration. This work spawned the development of a "dry" TMCTS that is expected to exhibit enhanced thermal stability relative towards uncontrolled decomposition.

High purity silicon amido precursors provide a route to low temperature CVD of silicate gate dielectrics. We have developed a straightforward synthetic method for the production of high purity Si[N(CH 3 ) 2 ] 4 , Si(NMeEt) 4 , HSi(NEtMe) 3 and HSi(NEt 2 ) 3 in high yield. These compounds were fully characterized by NMR, GC/MS, ICP-MS, ICchlorine, and elemental analysis. Their solution compatibility with an Hf amide source was also examined by chemical techniques. Low temperature CVD of metal silicate films is also demonstrated.

Three antimony and indium compounds, CH3SbBr2,, (SbCl3)(.)[(SbCl3S)-S-.(CH3)(2)] and (hfac)In(CH3)(2) were synthesized and characterized by spectroscopic methods. These compounds are highly volatile with excellent thermal stability. CH3SbBr2 contains only one carbon that may minimize carbon incorporation. (SbCl3)(.)[(SbCl3S)-S-.(CH3)(2)] is a new volatile dimeric compound (hfac)In(CH3)(2) is an air and moisture stable compound and is readily sublimed at room temperature. These compounds show promise for use as ion implant dopants.

Metalorganic chemical vapor deposition (MOCVD) process characteristics of several zirconium source reagents were investigated. These source reagents included metal β-diketonates [e.g., Zr(thd)4 where thd=(2,2,6,6-tetramethyl-3,5-heptanedionate)] and metal alkoxide/β-diketonates [e.g., Zr(OiPr)2(thd)2 and Zr(OtBu)2(thd)2]. Thermal properties and transport behaviors of these precursors were examined by thermogravimetric analysis. Zirconium oxide films were deposited on silicon substrates at reduced pressure. Under the process conditions examined, the deposition behavior was mass-transport controlled, and Zr(OiPr)2(thd)2 and Zr(OtBu)2(thd)2 behaved similarly. The films exhibited low carbon content. Pb(Zr, Ti)O3 (PZT) films were deposited on iridium-coated silicon substrates under reduced pressure. Zirconium incorporation efficiency was significantly improved for Zr(OiPr)2(thd)2 when compared to Zr(thd)4. Use of M(OtBu)2(thd)2 (where M=Zr or Ti) as source reagents for MOCVD of PZT was examined and compared to M(OiPr)2(thd)2 analogues. In this case, higher process pressures were needed to improve the incorporation efficiencies of M(OtBu)2(thd)2 precursors.

We have investigated a thermal MOCVD process using pentakis(ethylmethylamido)Ta and ammonia to deposit TaN as a conductive barrier (liner) for copper interconnects. We found that smooth, low resistivity films with low carbon and oxygen content could be formed at substrate temperatures from 300-450degreesC. The lowest resistivity observed for as-deposited films was 850muOmega-cm at a substrate temperature of 410degreesC. Since the deposition rate for this process was found to be surface reaction rate limited below 300degreesC we believe that highly conformal TaN can be deposited by this approach.

Tetrahydrofuran, unlike related monodentate ligands, displays an unusual ability to stabilize the mononuclear structure of bis(β-diketonate) complexes of barium and strontium as found for Ba(thd)2(THF)4 and Sr(thd)2(THF)4.

The compound (hfac)In(CH3)2 was synthesized and characterized by solution NMR, thermal analysis, and single-crystal X-ray diffraction. The compound is oxygen- and moisture-stable, very volatile, and easily transported with mild heating or vacuum sublimation. Chemical vapor deposition (CVD) using this molecule as a precursor produced In−Cu alloys on Cu/Pt-coated silicon substrates, and thus, the molecule exhibits utility as a safe indium CVD precursor.

MOCVD processes for (Ba,Sr)TiO3 (BST) and Pb(Zr,Ti)O3 (PZT) are described based on different metal – organic precursors. In the case of BST, processes using polyamine and tetraglyme adducts of group II metals were compared. Similar incorporation efficiencies were obtained at 640 °C for both adducts, and electrical properties were comparable. Delivery methodologies were compared using the tetraglyme adducts for BST. Composition control was equivalent using liquid mass flow controllers versus a positive displacement pump. For PZT, Zr(thd)4 and Zr(OiPr)2(thd)2 were compared as source materials in combination with Ti(OiPr)2(thd)2 and Pb(thd)2(pmdeta). The mixed ligand Zr source increased Zr incorporation efficiency by a factor of nearly eight for otherwise equivalent processes centred at 590 °C, and run to run repeatability was 0.1 at% for Pb and 0.6 at% for Zr (1 σ) over a series of more than 300 films. The electrical properties of thin film PZT deposited with Zr(OiPr)2(thd)2 compared favourably with those obtained previously with Zr(thd)4. Copyright © 2000 John Wiley & Sons, Ltd.

Thin films of Sr1−xBi2+xTa2O9 (SBT) have been deposited by metalorganic chemical vapor deposition (MOCVD) on 150mm Si wafers with Pt/Ti electrodes. The choice of Bi precursor significantly affects the process; film homogeneity is significantly improved when using a β-diketonate Bi precursor in combination with compatible Sr and Ta precursors. A highly repeatable process has been developed, with good run-to-run composition and thickness control. Effects of Bi volatility have been investigated in annealing experiments that show the onset of Bi loss at ∼570°C at reduced pressure (1–10 Torr). Film properties relevant to integrated ferroelectric random access (Fe RAMS) memories have also been characterized. Remenant polarizations (2Pr) up to 24μCcm−2 have been obtained at 5V, with 90% saturation of 2Pr at 1·5V and a coercive voltage of 0·52V for a 140mn film. Electrical leakage current density values were <2×10−8A cm−2 at 1·5V. Fatigue endurance has been measured to 1011 cycles with <10% degradation in switched charge.

Ni,Zn-ferrite (NZF) thin films are of interest for high frequency applications because of their high saturation magnetization compared to garnet films and their low eddy current losses compared to metal alloy films. Therefore there is an increasing need for methods to deposit single crystal ferrite thin films for incorporation into next generation microwave devices. Epitaxial thin films of NZF have been deposited by liquid delivery metal-organic chemical vapor deposition onto (100) oriented MgO substrates. The morphology, orientation and magnetic properties of the as-deposited films were investigated as a function of deposition temperature and pressure. X-ray diffraction (XRD) reveals highly oriented films with a film strain of 1.01% compared to bulk lattice parameters. Films with well saturated magnetic hysteresis were obtained under a number of conditions with values of saturation magnetization up to 270 emu/cc (3400 gauss) with relatively low coercive fields ~100 Oe. The influence of metal cation ratio on magnetic properties is discussed.