不同压力下螯合剂浓度在碱性Cu CMP中的影响

We propose the action mechanism of Cu chemical mechanical planarization(CMP) in an alkaline solution.Meanwhile,the effect of abrasive mass fraction on the copper removal rate and within wafer non-uniformity(WIWNU) have been researched.In addition,we have also investigated the synergistic effect between the applied pressure and the FA/O chelating agent on the copper removal rate and WIWNU in the CMP process.Based on the experimental results,we chose several concentrations of the FA/O chelating agent,which added in the slurry can obtain a relatively high removal rate and a low WIWNU after polishing,to investigate the planarization performance of the copper slurry under different applied pressure conditions.The results demonstrate that the copper removal rate can reach 6125 °/min when the abrasive concentration is 3 wt.%.From the planarization experimental results,we can see that the residual step height is 562 ° after excessive copper of the wafer surface is eliminated.It denotes that a good polishing result is acquired when the FA/O chelating agent concentration and applied pressure are fixed at 3 vol% and 1 psi,respectively.All the results set forth here are very valuable for the research and development of alkaline slurry.     

低磨料浓度的碱性铜抛光液平坦化性能的研究

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 copper 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°/min,while WIWNU is 2.8%.Nevertheless,the tantalum removal rate is 0 °/min,which indicates that barrier layer isn’t eliminated 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,after residual copper elimination process,the dishing value increased inconspicuously,in a controllable range,and the wafer surface roughness is only 0.326 nm(sq < 1 nm) after 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.     

基于化学机械动力学的碱性铜抛光液平坦化机理研究

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.     

Alkaline barrier slurry applied in TSV chemical mechanical planarization

We have proposed a TSV （through-silicon-via） alkaline barrier slurry without any inhibitors for barrier CMP （chemical mechanical planarization） and investigated its CMP performance. The characteristics of removal rate and selectivity of Ti/SiO2/Cu were investigated under the same process conditions. The results obtained from 6.2 mm copper, titanium and silica show that copper has a low removal rate during barrier CMP by using this slurry, and Ti and SiO2 have high removal rate selectivity to Cu. Thus it may be helpful to modify the dishing. The TSV wafer results reveal that the alkaline barrier slurry has an obvious effect on surface topography correction, and can be applied in TSV barrier CME     

三种胍盐对低磨料浓度碱性阻挡层抛光液性能的影响

The influence of three kinds of guanidinium salt on the removal rate selectivity of different materials was studied during the barrier chemical mechanical polishing(CMP) process at first.The three kinds of guanidine saltguanidine hydrochloride,guanidine nitrate and guanidine carbonate.Then we compared the effect of the three kinds of guanidine salt on the dishing,erosion and surface roughness value.In the end,the reaction mechanism was studied through electrochemical analysis.All the results indicate that there is a better performance of the slurry with guanidine hydrochloride than the slurries with the other two kinds of guanidine salt.It effectively improved the removal rate selectivity and the surface roughness under the premise of low abrasive concentration and low polishing pressure,which is good for the optimization of the alkaline slurry for the barrier CMP process.     

The stability of a novel weakly alkaline slurry of copper interconnection CMP for GLSI

Chemical mechanical polishing (CMP) is one of the important machining procedures of multilayered copper interconnection for GLSI,meanwhile polishing slurry is a critical factor for realizing the high polishing performance such as high planarization efficiency,low surface roughness.The effect of slurry components such as abrasive (colloidal silica),complexing agent (glycine),inhibitor (BTA) and oxidizing agent (H2O2) on the stability of the novel weakly alkaline slurry of copper interconnection CMP for GLSI was investigated in this paper.First,the synergistic and competitive relationship of them in a peroxide-based weakly alkaline slurry during the copper CMP process was studied and the stability mechanism was put forward.Then 1 wt％ colloidal silica,2.5 wt％ glycine,200 ppm BTA,20 mL/L H2O2 had been selected as the appropriate concentration to prepare copper slurry,and using such slurry the copper blanket wafer was polished.From the variations of copper removal rate,root-mean square roughness (Sq) value with the setting time,it indicates that the working-life of the novel weakly alkaline slurry can reach more than 7 days,which satisfies the requirement of microelectronics further development.     

化学机械抛光制程中铜抛光液平坦化能力的评估

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.     

Characterization and optimization of copper chemical mechanical planarization

The feature scale planarization of the copper chemical mechanical planarization (CMP) process has been characterized for two copper processes using Hitachi 430-TU/Hitachi T605 and Cabot 5001/Arch Cu10K consumables. The first process is an example of an abrasive-free polish with a high-selectivity barrier slurry, while the second is an example of a conventional abrasive slurry with a low-selectivity barrier slurry. Copper fill planarization has been characterized for structures with conformal deposition as well as with bumps resulting from bottom-up fill. Dishing and erosion were characterized for several structures after clearing. The abrasive-free polish resulted in low sensitivity to overpolish and low saturation levels for dishing and erosion. Consequently, this demonstrated superior performance when compared to the International Technology Roadmap for Semiconductors (ITRS) 2000 roadmap targets for planarization. While the conventional slurry could achieve the 0.13-μm technology node requirements, the abrasive-free polish met the planarization requirements beyond the 0.10-μm technology node.     

碱性阻挡层CMP后铜布线粗糙度的影响机理分析

The surface roughness seriously affects the performance of devices after barrier CMP. Due to the high surface roughness of copper line, the local resistance of a device will be high when working, then the copper line will overheat prompting the generation of electro-migration and the circuit will lose efficacy. Reducing the surface roughness of the copper line in barrier CMP is still an important research topic. The main factors influencing the surface roughness of copper line in alkaline barrier slurry are analyzed in the paper. Aimed at influencing the law on the surface roughness of copper line, using a new type of alkaline barrier slurry with a different p H of the chelating agent and changing the content of non-ionic surfactant, we then analyze the influencing law both on the surface roughness of copper line, and the influence mechanism. The experimental results show that with a chelating agent with a low p H value in the barrier slurry, the surface roughness of the copper line is 1.03 nm and it is the lowest in all of the barrier slurries, and with the increase of non-ionic surfactant concentration, the surface roughness of copper line is reduced to 0.43 nm, meeting the demand of further development of integrated circuits.     

碱性铜抛光液在300mm平坦化系统中CMP工艺优化的研究

CMP process optimization for bulk copper removal based on alkaline copper slurry was performed on a 300 mm Applied Materials Reflexion LK system. Under the DOE condition, we conclude that as the pressure increases, the removal rate increases and non-uniformity is improved. As the slurry flow rate increases, there is no significant improvement in the material removal rate, but it does slightly reduce the WIWNU and thus improve uniformity. The optimal variables are obtained at a reduced pressure of 1.5 psi and a slurry flow rate of 300 ml/min. Platen/carrier rotary speed is set at a constant value of 97/103 rpm. We obtain optimized CMP characteristics including a removal rate over 6452 A/min and non-uniformity below 4% on blanket wafer and the step height is reduced by nearly 8000 A/min in the center of the wafer on eight layers of copper patterned wafer, the surface roughness is reduced to 0.225 nm.     

Software Radio——Software Radio： A Review of Design Considerations and Digital Hardware Choices

This paper reviews the requirements for Software Defined Radio （SDR） systems for high-speed wireless applications and compares how well the different technology choices available- from ASICs, FPGAs to digital signal processors （DSPs） and general purpose processors （GPPs） - meet them.     

EEFA： Energy Efficiency Frame Aggregation Scheduling Algorithm for IEEE 802.11n Wireless Network

Packet size is restricted due to the error-prone wireless channel which drops the network energy utilization. Furthermore, the frequent packet retransmissions also lead to energy waste. In order to improve the energy efficiency of wireless networks and save the energy of wireless devices, EEFA （Energy Efficiency Frame Aggregation）, a frame aggregation based energy-efficient scheduling algorithm for IEEE 802.11n wireless network, is proposed. EEFA changes the size of aggregated frame dynamically according to the frame error rate, so as to ensure the data transmission and retransmissions completed during the TXOP and reduce energy consumption of channel contention. NS2 simulation results show that EEFA algorithm achieves better performance than the original frame-aggregation algorithm.     

SDN-Based Data Offioading for 5G Mobile Networks

The rapid growth of 3G/4G enabled devices such as smartphones and tablets in large numbers has created increased demand formobile data services.Wi-Fi offloading helps satisfy the requirements of data-rich applications and terminals with improved multi-media.Wi-Fi is an essential approach to alleviating mobile data traffic load on a cellular network because it provides extra capaci-ty and improves overall performance.In this paper,we propose an integrated LTE/Wi-Fi architecture with software-defined net-working(SDN)abstraction in mobile backhaul and enhanced components that facilitate the move towards next-generation 5G mo-bile networks.Our proposed architecture enables programmable offloading policies that take into account real-time network condi-tions as well as the status of devices and applications.This mechanism improves overall network performance by deriving real-time policies and steering traffic between cellular and Wi-Fi networks more efficiently.     

Large-signal characterizations of DDR IMPATT devices based on group Ⅲ-Ⅴ semiconductors at millimeter-wave and terahertz frequencies

Large-signal （L-S） characterizations of double-drift region （DDR） impact avalanche transit time （IM- PATT） devices based on group III-V semiconductors such as wurtzite （Wz） GaN, GaAs and InP have been carried out at both millimeter-wave （mm-wave） and terahertz （THz） frequency bands. A L-S simulation technique based on a non-sinusoidal voltage excitation （NSVE） model developed by the authors has been used to obtain the high frequency properties of the above mentioned devices. The effect of band-to-band tunneling on the L-S properties of the device at different mm-wave and THz frequencies are also investigated. Similar studies are also carried out for DDR IMPATTs based on the most popular semiconductor material, i.e. Si, for the sake of comparison. A compara- tive study of the devices based on conventional semiconductor materials （i.e. GaAs, InP and Si） with those based on Wz-GaN shows significantly better performance capabilities of the latter at both mm-wave and THz frequencies.     

应力和电阻率可控的适用于高品质因子MEMS器件的原位掺硼LPCVD多晶硅薄膜

The simultaneous control of residual stress and resistivity of polysilicon thin films by adjusting the deposition parameters and annealing conditions is studied. In situ boron doped polysilicon thin films deposited at 520 ℃ by low pressure chemical vapor deposition （LPCVD） are amorphous with relatively large compressive residual stress and high resistivity. Annealing the amorphous films in a temperature range of 600-800 ℃ gives polysilicon films nearly zero-stress and relatively low resistivity. The low residual stress and low resistivity make the polysilicon films attractive for potential applications in micro-electro-mechanical-systems （MEMS） devices, especially in high resonance frequency （high-f） and high quality factor （high-Q） MEMS resonators. In addition, polysilicon thin films deposited at 570 ℃ and those without the post annealing process have low resistivities of 2-5 mΩ·cm. These reported approaches avoid the high temperature annealing process （〉 1000 ℃）, and the promising properties of these films make them suitable for high-Q and high-f MEMS devices.     

Survivable Virtual Network Mapping Using Optimal Backup Topology in Virtualized SDN

Software-Defined Network architecture offers network virtualization through a hypervisor plane to share the same physical substrate among multiple virtual networks. However, for this hypervisor plane, how to map a virtual network to the physical substrate while guaranteeing the survivability in the event of failures, is extremely important. In this paper, we present an efficient virtual network mapping approach using optimal backup topology to survive a single link failure with less resource consumption. Firstly, according to whether the path splitting is supported by virtual networks, we propose the OBT-I and OBT-II algorithms respectively to generate an optimal backup topology which minimizes the total amount of bandwidth constraints. Secondly, we propose a Virtual Network Mapping algorithm with coordinated Primary and Backup Topology （VNM-PBT） to make the best of the substrate network resource. The simulation experiments show that our proposed approach can reduce the average resource consumption and execution time cost, while improving the request acceptance ratio of VNs.     

用于ZigBee的2.4GHz低功耗双增益低噪声放大器

This paper presents a fully differential dual gain low noise amplifier（DGLNA） for low power 2.45-GHz ZigBee/IEEE 802.15.4 applications.The effect of input parasitics on the inductively degenerated cascode LNA is analyzed.Circuit design details within the guidelines of the analysis are presented.The chip was implemented in SMIC 0.18-μm 1P6M RF/mixed signal CMOS process.The DGLNA achieves a maximum gain of 8 dB and a minimum gain of 1 dB with good input return loss.In high gain mode, the measured noise figure（NF） is 2.3-3 dB in the whole 2.45-GHz ISM band.The measured 1-dB compression point, IIP3 and IIP2 is-9, 1 and 33 dBm, respectively.The DGLNA consumes 2 mA of current from a 1.8 V power supply.     

应用于低中频和零中频DVB调谐器中8阶信道滤波器设计

An eighth order active-RC filter for low-IF and zero-IF DVB tuner applications is presented, which is implemented in Butterworth biquad structure. An automatic frequency tuning circuit is introduced to compensate the cut-off frequency variation using a 6-bit switched-capacitor array. Switched-resistor arrays are adopted to cover different cut-off frequencies in low-IF and zero-IF modes. Measurement results show that precise cut-off frequencies at 2.5, 3, 3.5 and 4 MHz in zero-IF mode, 5, 6, 7 and 8 MHz in low-IF mode can be achieved, 60 dB frequency attenuation can be obtained at 20 MHz, and the in-band group delay agrees well with the simulation. Two-tone testing shows the in-band IM3 achieves -52 dB and the out-band IM3 achieves -55 dB with -11 dBm input power. This proposed filter circuit, fabricated in a SMIC 0.18μm CMOS process, consumes 4 mA current with 1.8 V power supply.     

A 3.1-4.8 GHz CMOS receiver for MB-OFDM UWB

An integrated fully differential ultra-wideband CMOS receiver for 3.1-4.8 GHz MB-OFDM systems is presented. A gain controllable low noise amplifier and a merged quadrature mixer are integrated as the RF front-end. Five order Gm-C type low pass filters and VGAs are also integrated for both I and Q IF paths in the receiver. The ESD protected chip is fabricated in a Jazz 0.18μm RF CMOS process and achieves a maximum total voltage gain of 65 dB, an AGC range of 45 dB with about 6 dB/step, an averaged total noise figure of 6.4 to 8.8 dB over 3 bands and an in-band IIP3 of-5.1 dBm. The receiver occupies 2.3 mm2 and consumes 110 mA from a 1.8 V supply including test buffers and a digital module.     

一种适用于“模一”多带OFDM超宽带系统中跳频产生的3.96GHz锁相环

A fully integrated phase-locked loop（PLL） is presented for a single quadrature output frequency of 3.96 GHz.The proposed PLL can be applied to mode-1 MB-OFDM UWB hopping carrier generation.An adaptive frequency calibration loop is incorporated into the PLL.The capacitance area in the loop filter is largely reduced through a capacitor multiplier.Implemented in a CMOS process, this PLL draws 13.0 mA current from a single 1.2 V supply while occupying 0.55 mm2 die area.Measurement results show that the PLL achieves a phase noise of-70 dBc/Hz at 10 kHz offset and-113 dBc/Hz at 1 MHz offset.The integrated RMS jitter from 1 kHz to 10 MHz is 2.2 ps.The reference spur level is less than-68 dBc.