Cation Effect on Copper Chemical Mechanical Polishing

We examine the effect of cations in solutions containing benzotriazole （BTA） and H202 on copper chemical mechanical polishing （CMP）. On the base of atomic force microscopy （AFM） and material removal rate （MRR） results, it is found that ammonia shows the highest MRR as well as good surface after CMP, while KOH demonstrates the worst performance. These results reveal a mechanism that small molecules with lone-pairs rather than molecules with steric effect and common inorganic cations are better for copper CMP process, which is indirectly confirmed by open circuit potential （OCP）.     

Behaviour of Self-Standing CVD Diamond Film with Different Dominant Crystalline Surfaces in Thermal-Iron Plate Polishing

Self-standing CVD diamond films with different dominant crystalline surfaces are polished by the thermal-iron plate polishing method. The influence of the dominant crystalline surfaces on polishing etfficiency is investigated by measuring the removal rate and final roughness. The smallest rms roughness of 0.14 μm is measured with smallest removal rate in the films with the initial （220） dominant crystalline surface. Activation energy for the polishing is analysed by the Arrhenius relation. It is found that the values are 170kJ/mol, 222kJ/mol and 214kJ/mol for the film with three different dominant crystalline surfaces. Based on these values, the polishing cause is regarded as the graphitization-controlling process. In the experiment, we find that transformation of the dominant crystalline surfaces from （111） to （220） always appears in the polishing process when we polish the （111） dominant surface.     

Reactive Ion Etching as Cleaning Method Post Chemical Mechanical Polishing for Phase Change Memory Device

In order to improve nano-scale phase change memory performance, a super-clean interface should be obtained after chemical mechanical polishing （CMP） of Ge2Sb2Te5 phase change films. We use reactive ion etching （RIE） as the cleaning method. The cleaning effect is analysed by scanning electron microscopy and an energy dispersive spectrometer. The results show that particle residue on the surface has been removed. Meanwhile, Ge2Sb2Te5 material stoichiometric content ratios are unchanged. After the top electrode is deposited, currentvoltage characteristics test demonstrates that the set threshold voltage is reduced from 13 V to 2.7V and the threshold current from 0.1 mA to 0.025 mA. Furthermore, we analyse the RIE cleaning principle and compare it with the ultrasonic method.     

Damascene Array Structure of Phase Change Memory Fabricated with Chemical Mechanical Polishing Method

A damascene structure of phase change memory （PCM） is fabricated successfully with the chemical mechanical polishing （CMP） method, and the CMP of Ge2Sb2Te5 （GST） and Ti films is investigated. The polished surface of wafer is analysed by scanning electron microscopy （SEM） and an energy dispersive spectrometer （EDS）. The measurements show that the damascene device structure of phase change memory is achieved by the CMP process. After the top electrode is deposited, dc sweeping test on PCM reveals that the phase change can be observed. The threshold current of array cells varies between 0.90mA and 1.15mA.     

Ceria concentration effect on chemical mechanical polishing of optical glass

It was found material removal rate (MRR) sharply increased from 250 to 675 nm/min as the concentration decreased from 1 to 0.25 wt% in optical glass chemical mechanical polishing (CMP) using ceria slurries. Scanning electron microscopy was employed to characterize the ceria abrasive used in the slurry. Atomic force microscopy results showed good surface had been got after CMP. Schematic diagrams of the CMP process were shown. Furthermore, the absorption spectra indicated a sudden change from Ce⁴⁺ to Ce³⁺ of the ceria surface when the concentration decreased, which revealed a quantum origin of the phenomenon.     

Effect of surface roughness on the development of protective Al2O3 on Fe-10Al (at.%) alloys containing 0-10 at.% Cr

The effect of alloy surface roughness, achieved by different degrees of surface polishing, on the development of protective alumina layer on Fe-10 at.% Al alloys containing 0, 5, and 10 at.% Cr was investigated during oxidation at 1000 °C in 0.1 MPa oxygen. For alloys that are not strong Al₂O₃ formers (Fe-10Al and Fe-5Cr-10Al), the rougher surfaces increased Fe incorporation into the overall surface layer. On the Fe-10Al, more iron oxides were formed in a uniform layer of mixed aluminum- and iron-oxides since the layer was thicker. On the Fe-5Cr-10Al, more iron-rich nodules developed on an otherwise thin Al₂O₃ surface layer. These nodules nucleated preferentially along surface scratch marks but not on alloy grain boundaries. For the strong Al₂O₃-forming Fe-10Cr-10Al alloy, protective alumina surface layers were observed regardless of the surface roughness. These results indicate that the formation of a protective Al₂O₃ layer on Fe-Cr-Al surfaces is not dictated by Al diffusion to the surface. More cold-worked surfaces caused an enhanced Fe diffusion, hence produced more Fe-rich oxides during the early stage of oxidation.     

Effect of gas residence time on the morphology of silicon surface etched in SF6 plasmas

This paper describes the effect of the SF₆ gas residence time on the morphology of silicon (1 0 0) samples etched in a reactive ion etching system. Profilometry and atomic force microscopy techniques were used to characterize the etching process focusing attention on the evolution of the surface morphology. Under the condition of variable pressure and gas flow rate, the decrease of the residence time leads to an increase of the silicon etch rate concomitantly with an increase of the surface roughness. Contrary fact is observed when the gas flow is fixed and the pressure is varied. Here, the increasing of residence time leads to a constant increase of silicon etch rate with small variations in final surface roughness. To better understanding this resident time effect, mass spectrometry analyses were realized during the discharge for both gas flow conditions.     

The effect of hydrogen peroxide on polishing removal rate in CMP with various abrasives

The effect of hydrogen peroxide in chemical mechanical planarization slurries for shallow trench isolation was investigated. The various abrasives used in this study were ceria, silica, alumina, zirconia, titania, silicon carbide, and silicon nitride. Hydrogen peroxide suppresses the polishing of silicon dioxide and silicon nitride surfaces by ceria abrasives. The polishing performances of other abrasives were either unaffected or enhanced slightly with the addition of hydrogen peroxide. The ceria abrasives were treated with hydrogen peroxide, and the polishing of the work surfaces with the treated abrasive shows that the inhibiting action of hydrogen peroxide is reversible. It was found that the effect of hydrogen peroxide as an additive is a strong function of the nature of the abrasive particle.     

Submicron particle removal in post-oxide chemical–mechanical planarization (CMP) cleaning

Particle removal models for soft-pad buffing (the second-step polishing with DI water) and mechanical brush-cleaning processes are proposed and the removal forces are evaluated and compared with the average particle adhesion force to the oxide wafer surface resulting from the primary polishing (the first-step polishing with slurry). The hydrodynamic force due to the fluid flow is too small to remove slurry particles by itself and particles are most likely removed from the surfaces by the pad or brush asperity contact forces and the hydrodynamic drag force together. This conclusion is consistent with the experimental observations. Received: 25 January 1999 / Accepted: 18 May 1999 / Published online: 8 September 1999     

Effect of Pretreatment of TaN Substrates on Atomic Layer Deposition Growth of Ru Thin Films

The polycrystalline ruthenium films are grown on TaN substrates by atomic layer deposition （ALD） using bis（cyclopentadienyl） ruthenium [RuCp2] and oxygen as ruthenium precursor and reactant respectively at a deposition temperature of 330℃. The low-energy Ar ion bombardment and Ru pre-deposition are performed to the underlying TaN substrates before ALD process in order to improve the Ru nucleation. X-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy are carried out to characterize the properties of ALD Ru films. The results show that the nucleation density of Ru films with Ar^＋ bombardment to the underlying TaN substrates is much higher than that of the ones without any pretreatment. The possible reasons are discussed.     

Superhydrophobic surfaces prepared from water glass and non-fluorinated alkylsilane on cotton substrates

Superhydrophobic surfaces have been successfully prepared by sol-gel method using water glass as starting material. Such surfaces were obtained first by dip-coating the silica hydrosols prepared via hydrolysis and condensation of water glass onto cotton substrates, then the surface of the silica coating was modified with a non-fluoro compound, hexadecyltrimethoxysilane (HDTMS), to gain a thin film through self-assembly, superhydrophobicity with a water contact angle higher than 151° can be achieved. The morphology and surface roughness were characterized by SEM and AFM.     

石英玻璃片的化学抛光工艺研究

石英玻璃是紫外光刻、激光核技术等精密光学系统的关键光学元件。石英玻璃在加工过程中易出现表面及亚表面损伤和蚀坑等缺陷问题,化学抛光能有效消除石英玻璃的亚表面损伤。介绍了石英玻璃片的化学抛光工艺原理和过程,利用正交实验法优化了石英玻璃化学抛光工艺参数,分析了化学抛光过程中抛光液成分、抛光液温度和抛光时间对石英玻璃片表面粗糙度的影响。实验结果表明,采用氟化氢铵、水和丙三醇配置的化学抛光液,在最优化的工艺参数时,石英玻璃片经过化学抛光,表面粗糙度可降到100 nm左右,可见光透过率最高可达到89%。为石英玻璃光学零件的化学抛光工艺提供了理论依据和技术支持。     

Laser-induced periodic surface structures on different poly-carbonate films

Laser-induced periodic surface structures (LIPSS) were generated on oriented and amorphous thick, as well as on spin-coated thin, poly-carbonate films by polarized ArF excimer laser light. The influence of the film structure and thickness on the LIPSS formation was demonstrated. Below a critical thickness of the spin-coated films the line-shaped structures transformed into droplets. This droplet formation was explained by the laser-induced melting across the whole film thickness and subsequent de-wetting on the substrate. The thickness of the layer melted by laser illumination was computed by a heat-conduction model. Very good agreement with the critical thickness for spin-coated films was found. The original polymer film structure influences the index of refraction of the thin upper layer modified by the laser treatment, as was proven by the dependence of the structure’s period on the angle of incidence both for ‘s’- and ‘p’-polarized beams. The effect of the original surface roughness – grains in thick films or holes in thin films – was studied using atomic force microscopy. It was shown that the oblique incidence of ‘s’-polarized beams results in an intensity confinement in the direction of the forward scattering and in asymmetrical interference pattern formation around these irregularities. A new, two-dimensional grating-like structure was generated on spin-coated films. These gratings might be used as a special kind of mask. Received: 10 July 2001 / Accepted: 23 July 2001 / Published online: 30 August 2001     

Atomically controlled surfaces with step and terrace of β-Ga2O3 single crystal substrates for thin film growth

The surface of β-Ga₂O₃ (1 0 0) single crystal grown with floating zone method was treated by chemical-mechanical-polishing (CMP) for 30-120 min followed by annealing in oxygen atmosphere at temperature 600-1100 °C for 3-6 h. The evolution of the step arrangement was investigated with reflection high energy electron diffraction and atomic force microscopy. Atomically smooth surfaces with atomic step and terrace structure of β-Ga₂O₃ substrates were successfully obtained after just CMP treatment as well as CMP treatment and post annealing at 1100 °C for 3 h. The uniform step height was 0.57 nm, and smooth terrace width was 100 nm, where the misorientation angle was about 0.36°. The obtained atomically smooth surface provides a potential application for the high-quality epitaxial film growth.     

Laser treatment of white China surface

The surface of gloss fired porcelain with and without raw glaze coating was radiated by a CO₂ laser working at 10.6 μm, a choice resulted from spectroscopic studies of suspensions made of China. The shine of the untreated sample was defined as the distribution of micro-droplets on the surface. The surface alterations due to laser heating were classified by the diameter of the completely melted surface, the ring of the surface at the threshold of melting, and the size of microscopic cracks. The diameter of the laser treated area was in the range of 3 mm, while the incident laser power and the duration of laser heating were varied between 1 and 10 W and 1-8 min, respectively. The different stages of surface modifications were attributed primarily to the irradiating laser power and proved to be rather insensitive to the duration of the treatment. We have found a range of parameters under which the white China surface coated with raw glaze and followed by laser induced melting exhibited very similar characteristics to the untreated porcelain. This technique seems prosperous for laser assisted reparation of small surface defects of unique China samples after the firing process.     

AFM Study on the Formation Mechanism and Microstructure of Ni Atomic Aggregates on Liquid Substrates

We study the formation mechanism and microstructure of nickel （Ni） atomic aggregates on the silicone oil surfaces by atomic force microscopy （AFM）. Initially, the deposited atoms nucleate and form the compact clusters on the liquid surfaces. Then they perform Brownian motion and adhere upon impact. Finally the branched aggregates are formed. The Ni aggregates exhibit granular structure. The mean size of the granularities in the aggregates is of the order of 10 nm and it decreases with the nominal film thickness. The experiment shows that the Ni aggregates perform a directional diffusion towards the sample edge. The interpretation for this phenomenon is presented.     

Wet sulfur passivation of GaSb(1 0 0) surface for optoelectronic applications

A comparative analysis of the properties of the non-passivated and S-passivated GaSb(1 0 0) surfaces has been performed through PL, AFM and RHEED characterization. The samples treated with a 1 M Na₂S aqueous solution demonstrate an increase in the 5 K PL intensity. According to AFM data, the annealing of the S-passivated GaSb(1 0 0) leads to the formation of the clean flat (1 0 0) surface. Moreover, after annealing the PL intensity of the S-passivated GaSb(1 0 0) surfaces decreases by 20%, whereas for the non-passivated samples it drops by more than a factor of 4. The method of wet sulfur passivation has shown great effectiveness in pre-epitaxial processing for LPE and MBE growth of the GaSb-related materials for optoelectronics.     

高准确度玻璃光学元件的CMP技术研究

依据化学机械抛光（Chemical Mechanical Polishing,CMP）加工玻璃光学元件的原理,通过对抛光运动机理的理论分析,提出了抛光垫的磨削均匀性对光学元件面形的影响,并设计了新的工艺流程.通过工艺试验,完成了高准确度玻璃光学元件的CMP加工,获得了表面质量N<0.2,Rq<0.3 nm的玻璃光学元件.     

Nano- and micro-scale patterning of Si (1 0 0) under keV ion irradiation

Evolution of Si (1 0 0) surface under 100 keV Ar⁺ ion irradiation at oblique incidence has been studied. The dynamics of surface erosion by ion beam is investigated using detailed analysis of atomic force microscopy (AFM) measurements. During an early stage of sputtering, formation of almost uniformly distributed nano-dots occurs on Si surface. However, the late stage morphology is characterized by self-organization of surface into a regular ripple pattern. Existing theories of ripple formation have been invoked to provide an insight into surface rippling.     

Stability of hydrogen-terminated vicinal Si(1 1 1) surface under ambient atmosphere

In this paper a comparative study of different wet-chemical etching procedures of vicinal Si(1 1 1) surface passivation is presented. The stability against oxidation under ambient atmosphere was studied by X-ray photoelectron spectroscopy and atomic force microscopy. The best results were achieved by the buffered HF etching and the final smoothing of the surface by hot (72 °C) NH₄F. The procedures consisting of a large number of etching steps were unsatisfactory, since the probability of contamination during each step was increasing. The passivated surface was stable against oxidation for at least 3 h under ambient atmosphere.