5-methyl-1H-benzotriazole as potential corrosion inhibitor for electrochemical-mechanical planarization of copper

According to the electrochemical analysis, the corrosion inhibition efficiency of 5-methyl-lH-benzotriazole （m-BTA） is higher than that of benzotrizaole （BTA）. The inhibition capability of the m-BTA passive film formed in hydroxyethylidenediphosphonic acid （HEDP） electrolyte containing both m-BTA and chloride ions is superior to that formed in m-BTA-alone electrolyte, even at a high anodic potential. The results of electrical impedance spectroscopy, nano-scratch experiments and energy dispersive analysis of X-ray （EDAX） indicate that the enhancement of m-BTA inhibition capability may be due to the increasing thickness of passive film. Furthermore, X-ray photoelectron spectrometry （XPS） analysis indicates that the increase in passive film thickness can be attributed to the incorporation of C1 into the m-BTA passive film and the formation of [Cu（I）CI（rn-BTA）], polymer film on Cu surface. Therefore, the introduction of C1- into m-BTA-containing HEDP electrolyte is effective to enhance the passivation capability of m-BTA passive film, thus extending the operating potential window.

TWO STEPS CHEMICAL-MECHANICAL POLISHING OF RIGID DISK SUBSTRATE TO GET ATOM-SCALE PLANARIZATION SURFACE

In order to get atomic smooth rigid disk substrate surface, ultra-fined alumina slurry and nanometer silica slurry are prepared, and two steps chemical-mechanical polishing （CMP） of rigid disk substrate in the two slurries are studied. The results show that, during the first step CMP in the alumina slurry, a high material removal rate is reached, and the average roughness （Ra） and the average waviness （Wa） of the polished surfaces can be decreased from previous 1.4 nm and 1.6 nm to about 0.6 nm and 0.7 nm, respectively. By using the nanometer silica slurry and optimized polishing process parameters in the second step CMP, the Ra and the Wa of the polished surfaces can be further reduced to 0.038 nm and 0.06 am, respectively. Atom force microscopy （AFM） analysis shows that the final polished surfaces are ultra-smooth without micro-defects.

Mechanism of amorphous Ge_2Sb_2Te_5 removal during chemical mechanical planarization in acidic H_2O_2 slurry

In this paper, chemical mechanical planarization （CMP） of amorphous Ge2Sb2Te5 （a-GST） in acidic H2O2 slurry is investigated. It was found that the removal rate of a-GST is strongly dependent on H2O2 concentration and gradually increases with the increase in H2O2 concentration, but the static etch rate first increases and then slowly decreases with the increase in H2O2 concentration. To understand the chemical reaction behavior of H2O2 on the a-GST surface, the potentiodynamic polarization curve, surface morphology and cross-section of a-GST immersed in acidic slurry are measured and the results reveal that a-GST exhibits a from active to passive behavior for from low to high concentration of H2O2. Finally, a possible removal mechanism of a-GST in different concentrations of H2O2 in the acidic slurry is described.

Pseudo Jahn-Teller Effect in Puckering and Planarization of Heterocyclic Compounds

The goal of this brief partly review paper is to summarize the results of the works published over the last few years regarding the origin of the out-of-plane distortions (puckering) of heterocyclic compounds. In all the papers devoted to this problem, it is shown that the instability of planar configurations of heterocyclic molecules leading to symmetry breaking and distortions is induced by the pseudo Jahn-Teller effect (PJTE). Special attention in this work is paid to the mechanism of suppression and enhancement of the PJTE distortions of heterocycles by oxidation, reduction, and chemical substitutions. It is demonstrated that oxidation of 1,4-dithiine containing compounds leads to suppression of the PJTE and to restoration of their planar nuclear configurations. An example of a dibenzo[1,2]dithiine molecule is used to demonstrate the mechanism of enhancement of the PJTE by reduction. It is shown that the reduction of the neutral C12H8S2 molecule up to the dianion (C12H8S2)2- enhances the PJTE, followed by the S-S bond cleavage and significant structural distortions of the system. The change of the PJTE by chemical substitutions, accompanied either by puckering or by planarization of heterocyclic compounds, is discussed using as examples 1,4-ditinine and its S-oxygenated derivatives.

Improvement of High Dynamic Range Capacitive Displacement Sensor by a Globalm Planarization

This study presents an improvement of high dynamic range contact-type capacitive displacement sensor by applying planarization. The sensor is called the contact-type linear encoder-like capacitive displacement sensor (CLECDiS), is a nano-meter-resolution sensor with a wide dynamic range. However, height differences due to patterned electrodes may cause a variety of problems or performance degradation. In devices of two glass wafer surfaces with patterned structures assembled face-to-face and in sliding contact, the heights of the patterns crucially affect their performance and practicality, so it should be planarized for reducing the problem. A number of techniques for planarizing glass wafer surfaces with patterned chrome electrodes were evaluated and the following three were selected as adequate: lift-off, etch-back, and chemical mechanical polishing (CMP). The fabricated samples showed that CMP provided the best planarization. CMP was successfully employed to produce CLECDiS with improved signal reliability due to reduced collisions between electrodes.

Evaluation of planarization capability of copper slurry in the CMP process

The evaluation methods of planarization capability of copper slurry are investigated.Planarization capability and material removal rate are the most essential properties of slurry.The goal of chemical mechanical polishing(CMP) is to achieve a flat and smooth surface.Planarization capability is the elimination capability of the step height on the copper pattern wafer surface,and reflects the passivation capability of the slurry to a certain extent.Through analyzing the planarization mechanism of the CMP process and experimental results,the planarization capability of the slurry can be evaluated by the following five aspects:pressure sensitivity,temperature sensitivity,static etch rate,planarization efficiency and saturation properties.

Scratch formation and its mechanism in chemical mechanical planarization (CMP)

Chemical mechanical planarization(CMP)has become one of the most critical processes in semiconductor device fabrication to achieve global planarization.To achieve an efficient global planarization for device node dimensions of less than 32 nm,a comprehensive understanding of the physical,chemical,and tribo-mechanical/chemical action at the interface between the pad and wafer in the presence of a slurry medium is essential.During the CMP process,some issues such as film delamination,scratching,dishing,erosion,and corrosion can generate defects which can adversely affect the yield and reliability.In this article,an overview of material removal mechanism of CMP process,investigation of the scratch formation behavior based on polishing process conditions and consumables,scratch formation mechanism and the scratch inspection tools were extensively reviewed.The advantages of adopting the filtration unit and the jet spraying of water to reduce the scratch formation have been reviewed.The current research trends in the scratch formation,based on modeling perspective were also discussed.

Planarization properties of an alkaline slurry without an inhibitor on copper patterned wafer CMP

The chemical mechanical polishing/planarization（CMP） performance of an inhibitor-free alkaline copper slurry is investigated.The results of the Cu dissolution rate（DR） and the polish rate（PR） show that the alkaline slurry without inhibitors has a relatively high copper removal rate and considerable dissolution rate.Although the slurry with inhibitors has a somewhat low DR,the copper removal rate was significantly reduced due to the addition of inhibitors（Benzotriazole,BTA）.The results obtained from pattern wafers show that the alkaline slurry without inhibitors has a better planarization efficacy;it can planarize the uneven patterned surface during the excess copper removal.These results indicate that the proposed inhibitor-free copper slurry has a considerable planarization capability for CMP of Cu pattern wafers,it can be applied in the first step of Cu CMP for copper bulk removal.

Chemical mechanical planarization of amorphous Ge_2Sb_2Te_5 with a soft pad

Chemical mechanical planarization（CMP） of amorphous Ge_2Sb_2Te_5（a-GST） is investigated using two typical soft pads（politex REG and AT） in acidic slurry.After CMP,it is found that the removal rate（RR） of a-GST increases with an increase of runs number for both pads.However,it achieves the higher RR and better surface quality of a-GST for an AT pad.The in-situ sheet resistance（R_s） measure shows the higher R_s of a-GST polishing can be gained after CMP using both pads and the high R_s is beneficial to lower the reset current for the PCM cells. In order to find the root cause of the different RR of a-GST polishing with different pads,the surface morphology and characteristics of both new and used pads are analyzed,it shows that the AT pad has smaller porosity size and more pore counts than that of the REG pad,and thus the AT pad can transport more fresh slurry to the reaction interface between the pad and a-GST,which results in the high RR of a-GST due to enhanced chemical reaction.

Planarization mechanism of alkaline copper CMP slurry based on chemical mechanical kinetics

The planarization mechanism of alkaline copper slurry is studied in the chemical mechanical polishing （CMP） process from the perspective of chemical mechanical kinetics.Different from the international dominant acidic copper slurry,the copper slurry used in this research adopted the way of alkaline technology based on complexation. According to the passivation property of copper in alkaline conditions,the protection of copper film at the concave position on a copper pattern wafer surface can be achieved without the corrosion inhibitors such as benzotriazole（BTA）,by which the problems caused by BTA can be avoided.Through the experiments and theories research,the chemical mechanical kinetics theory of copper removal in alkaline CMP conditions was proposed. Based on the chemical mechanical kinetics theory,the planarization mechanism of alkaline copper slurry was established. In alkaline CMP conditions,the complexation reaction between chelating agent and copper ions needs to break through the reaction barrier.The kinetic energy at the concave position should be lower than the complexation reaction barrier,which is the key to achieve planarization.

Evaluation of planarization performance for a novel alkaline copper slurry under a low abrasive concentration

A novel alkaline copper slurry that possesses a relatively high planarization performance is investigated under a low abrasive concentration. Based on the action mechanism of CMP, the feasibility of using one type of slurry in copper bulk elimination process and residual copper elimination process, with different process parameters, was analyzed. In addition, we investigated the regular change of abrasive concentration effect on cop- per and tantalum removal rate and within wafer non-uniformity （WIWNU） in CMP process. When the abrasive concentration is 3 wt%, in bulk elimination process, the copper removal rate achieves 6125 ~/min, while WIWNU is 3.5%, simultaneously. In residual copper elimination process, the copper removal rate is approximately 2700 A/min, while WIWNU is 2.8%. Nevertheless, the tantalum removal rate is 0 A./min, which indicates that barrier layer isn＇t elinainated in residual copper elimination process. The planarization experimental results show that an excellent planarization performance is obtained with a relatively high copper removal rate in bulk elimination process. Meanwhile, atier residual copper elimination process, the dishing value increased inconspicuously, in a control- lable range, and the wafer surface roughness is only 0.326 nm （sq 〈 1 nm） alter polishing. By comparison, the planarization performance and surface quality of alkaline slurry show almost no major differences with two kinds of commercial acid slurries after polishing. All experimental results are conducive to research and improvement of alkaline slurry in the future.

A new weakly alkaline slurry for copper planarization at a reduced down pressure

This study reports a new weakly alkaline slurry for copper chemical mechanical planarization （CMP）, it can achieve a high planarization efficiency at a reduced down pressure of 1.0 psi. The slurry is studied through the polish rate, planarization, copper surface roughness and stability. The copper polishing experiment result shows that the polish rate can reach 10032 A/rain. From the multi-layers copper CMP test, a good result is obtained, that is a big step height （10870 A） that can be eliminated in just 35 s, and the copper root mean square surface roughness （sq） is very low （〈 1 rim）. Apart from this, compared with the alkaline slurry researched before, it has a good progress on stability of copper polishing rate, stable for 12 h at least. All the results presented here are relevant for further developments in the area of copper CMP.

Y_(2)O_(3) nanosheets as slurry abrasives for chemical-mechanical planarization of copper

Continued reduction in feature dimension in integrated circuits demands high degree of flatness after chemical mechanical polishing.Here we report using new yttrium oxide(Y_(2)O_(3))nanosheets as slurry abrasives for chemical-mechanical planarization(CMP)of copper.Results showed that the global planarization was improved by 30%using a slurry containing Y_(2)O_(3) nanosheets in comparison with a standard industrial slurry.During CMP,the two-dimensional square shaped Y_(2)O_(3) nanosheet is believed to induce the low friction,the better rheological performance,and the laminar flow leading to the decrease in the within-wafer-non-uniformity,surface roughness,as well as dishing.The application of the two-dimensional nanosheets as abrasive in CMP would increase the manufacturing yield of integrated circuits.

Effect of polishing parameters on abrasive free chemical mechanical planarization of semi-polar(1122) aluminum nitride surface

An abrasive free chemical mechanical planarization（AFCMP） of semi-polar（1122） Al N surface has been demonstrated. The effect of slurry p H, polishing pressure, and platen velocity on the material removal rate（MRR） and surface quality（RMS roughness） have been studied. The effect of polishing pressure on the AFCMP of the（1122） Al N surface has been compared with that of the（1122） Al Ga N surface. The maximum MRR has been found to be 562 nm/h for the semi-polar（1122） Al N surface, under the experimental conditions of 38 k Pa pressure,90 rpm platen velocity, 30 rpm carrier velocity, slurry p H 3 and 0.4 M oxidizer concentration. The best root mean square（RMS） surface roughness of 1.2 nm and 0.7 nm, over a large scanning area of 0.70×0.96 mm^2, has been achieved on AFCMP processed semi-polar（1122） AlN and（AlGaN） surfaces using optimized slurry chemistry and processing parameters.

Compact magneto-optical traps using planar optics

Magneto-optical traps (MOTs) composed of magnetic fields and light fields have been widely utilized to cool andconfine microscopic particles. Practical technology applications require miniaturized MOTs. The advancement of planaroptics has promoted the development of compact MOTs. In this article, we review the development of compact MOTs basedon planar optics. First, we introduce the standardMOTs. We then introduce the gratingMOTs with micron structures, whichhave been used to build cold atomic clocks, cold atomic interferometers, and ultra-cold sources. Further, we introducethe integrated MOTs based on nano-scale metasurfaces. These new compact MOTs greatly reduce volume and powerconsumption, and provide new opportunities for fundamental research and practical applications.

Planar Hall Effect in the Charge-Density-Wave Bi_(2)Rh_(3)Se_(2)

We systematically investigate in-plane transport properties of ternary chalcogenideBi_(2)Rh_(3)Se_(2).Upon rotating the magnetic field within the plane of the sample, one can distinctly detect the presence of both planar Hall resistance and anisotropic longitudinal resistance, and the phenomena appeared are precisely described by the theoretical formulation of the planar Hall effect (PHE). In addition, anisotropic orbital magnetoresistance rather than topologically nontrivial chiral anomalies dominates the PHE in Bi_(2)Rh_(3)Se_(2). The finding not only provides another platform for understanding the mechanism of PHE, but could also be beneficial for future planar Hall sensors based on two-dimensional materials.

High-performance GaSb planar PN junction detector

This paper examines GaSb short-wavelength infrared detectors employing planar PN junctions. The fabrication was based on the Zn diffusion process and the diffusion temperature was optimized. Characterization revealed a 50% cut-off wavelength of 1.73 μm, a maximum detectivity of 8.73 × 10^(10) cm·Hz^(1/2)/W, and a minimum dark current density of 1.02 × 10^(-5) A/cm^(2).Additionally, a maximum quantum efficiency of 60.3% was achieved. Subsequent optimization of fabrication enabled the realization of a 320 × 256 focal plane array that exhibited satisfactory imaging results. Remarkably, the GaSb planar detectors demonstrated potential in low-cost short wavelength infrared imaging, without requiring material epitaxy or deposition.

Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite

The damage of rock joints or fractures upon shear includes the surface damage occurring at the contact asperities and the damage beneath the shear surface within the host rock.The latter is commonly known as off-fault damage and has been much less investigated than the surface damage.The main contribution of this study is to compare the results of direct shear tests conducted on saw-cut planar joints and tension-induced rough granite joints under normal stresses ranging from 1 MPa to 50 MPa.The shear-induced off-fault damages are quantified and compared with the optical microscope observation.Our results clearly show that the planar joints slip stably under all the normal stresses except under 50 MPa,where some local fractures and regular stick-slip occur towards the end of the test.Both post-peak stress drop and stick-slip occur for all the rough joints.The residual shear strength envelopes for the rough joints and the peak shear strength envelope for the planar joints almost overlap.The root mean square(RMS)of asperity height for the rough joints decreases while it increases for the planar joint after shear,and a larger normal stress usually leads to a more significant decrease or increase in RMS.Besides,the extent of off-fault damage(or damage zone)increases with normal stress for both planar and rough joints,and it is restricted to a very thin layer with limited micro-cracks beneath the planar joint surface.In comparison,the thickness of the damage zone for the rough joints is about an order of magnitude larger than that of the planar joints,and the coalesced micro-cracks are generally inclined to the shear direction with acute angles.The findings obtained in this study contribute to a better understanding on the frictional behavior and damage characteristics of rock joints or fractures with different roughness.

Regulating intramolecular hydrogen bonds of p-phenylenediimidazole-based small-molecule compounds towards the enhanced lithium storage capacity

The use of redox-active organic electrode materials in energy storage is restricted due to their inferior solvent resistance,abysmal conductivity,and the resultant low practical capacity.To address these issues,a class of bipolar p-phenylenediimidazole-based small-molecule compounds are designed and fabricated.Theπ-conjugated backbone of these small molecules allows for electron delocalization on a big conjugation plane,endowing them with good conductivity and reaction reversibility.Furthermore,when the para-positions of phenylene are occupied by hydroxyl groups,as-formed intramolecular hydrogen bonds(N-H...O)between phenolic hydroxyl groups and the–NH groups of imidazole rings further enhance the structural planarity,resulting in higherπ-conjugation degree and better conductivity,and thus higher utilization of active sites and electrode capacity,proved by both experimental results and theoretical calculations.The optimized composite electrode DBNQ@rGO-45 shows a high specific capacity(∼308 mA h g^(−1)at 100 mA g^(−1))and a long cycling stability(112.9 mA h g^(−1)after 6000 cycles at 2000 mA g^(−1)).The significantly better electrochemical properties for hydroxyl group-containing compounds than those without hydroxyl groups attributed to intramolecular hydrogen bond-induced conjugation enhancement will inspire the structure design of organic electrodes for better energy storage.