感应耦合等离子体选择性刻蚀GaN／A1GaN

采用Cl2/Ar作为刻蚀气体．研究了在感应耦合等离子体干法刻蚀GaN、Al0.27，Ga0.73N材料中工艺参数对刻蚀速率及选择比的影响．GaN与Al0.27Ga0.72N之间的刻蚀选择比随自偏压的增大而减小．随感应耦合等离子体功率的增大变化不大．在Cl2／Ar为3：l的刻蚀气体中加入10％的O2对GaN刻蚀速率影响不大．却使Al0.27Ga0.73N刻蚀速率明显下降．从而提高了GaN与Al0.27Ga0.73N之间的刻蚀选择比．对比了采用不同自偏压刻蚀的Al0.27Ga0.73N材料肖特基的特性．发现反向漏电流随自偏压的增大而增大．     

工艺参数对电感耦合等离子体刻蚀ZnS速率及表面粗糙度的影响

为了得到电感耦合等离子体反应刻蚀ZnS的工艺参数,采用CH4∶H2∶Ar(1∶7∶5)作为刻蚀气体,在ZnS刻蚀机理的基础上,分析各工艺因素对ZnS刻蚀速率和刻蚀后表面粗糙度的影响.实验结果表明:当气体总流量39sccm、偏压功率80W、射频功率300W时,ZnS刻蚀速率为18.5nm/min,表面粗糙度Ra小于6.3nm,刻蚀后表面沉积物相对较少;Ar含量变化对刻蚀速率和表面粗糙度影响较大.给出了刻蚀速率和表面粗糙度随气体总流量、Ar含量、偏压功率和射频功率的变化趋势.     

PZY铁电薄膜材料的ECR等离子体刻蚀研究

以SF6和SF6＋Ar为刻蚀气体。采用电子回旋共振等离子体刻蚀工艺成功地对溶胶．凝胶工艺制备的锆钛酸铅铁电薄膜进行了有效的刻蚀去除．研究了不同气体总漉量、混合比、微波功率等因素对刻蚀速率的影响。指出当气体混合比约为20％时。刻蚀速率达到最大值．锆钛酸铅铁电薄膜表面组份XPS能谱分析曲线表明，在SF6和SF6＋Ar气体中。被刻蚀后样品的Pb含量大大减少。TiO2的刻蚀是限制铬钛酸铅铁电薄膜刻蚀速率的主要因素．     

电感耦合等离子体刻蚀反应烧结碳化硅工艺研究

为获得超光滑的反应烧结碳化硅(RB-Si C)材料表面,以提高其表面反射率,利用电感耦合等离子体(ICP)刻蚀技术对RB-Si C进行刻蚀.通过正交实验研究了射频功率、偏压功率和刻蚀气体(CF_4/O_2)流量比三个因素对刻蚀速率和表面粗糙度的影响程度.分析了偏压功率这一单因素对刻蚀速率和表面粗糙度的影响规律.结果表明:偏压功率对刻蚀速率和表面粗糙度的影响程度最大,其次为射频功率,刻蚀气体(CF_4/O_2)流量比对刻蚀速率和表面粗糙度的影响最小;刻蚀最优射频功率为150 W,最优偏压功率为50 W,最优CF_4/O_2流量比为25∶5,最优工作压强为1 Pa.     

硅深刻蚀中掩蔽层材料的研究

掩蔽层材料选择比低是硅高深宽比微结构实现的限制之一.为了获得高质量的掩蔽层材料,利用感应耦合等离子体(Inductively Coupled Plasma,ICP)刻蚀方法,选择SiO2,MgO,Al作为掩蔽层材料,通过研究刻蚀过程中射频功率及气体流量对SiO2,MgO,Al及Si刻蚀速率变化的影响,获得了SF6等离子体对Si与SiO2,Si与MgO,Si与Al的选择比.结果表明:MgO薄膜作为掩蔽层、射频功率为800 W,气体流量为50 sccm或80 sccm是深刻蚀中适宜的工艺参数.     

用SF6/O2气体ICP刻蚀硅深槽基片温度对刻蚀速率的影响

以SF6/O2为刻蚀气体用RIE刻蚀机刻蚀Si,当功率为500W,偏压为250V,气体流量45mL/min,压力分别为2.7Pa6、.7 Pa、11Pa时,基片温度的改变对其刻蚀速率的影响。实验结果表明:进行室温刻蚀(≥0℃)和低温刻蚀(≤0℃)时,其刻蚀机理不尽相同,当基片温度为0℃~80℃时,对刻蚀速率起关键作用的是各向同性的化学反应刻蚀。当基片温度为-120℃~0℃时,对刻蚀速率起关键作用的是各向异性的物理刻蚀,可以获得理想的尺寸和形貌。     

利用发射光谱研究ECR等离子体对钨的刻蚀

研究不同刻蚀条件下等离子体对钨表面的刻蚀变化,并对其原因进行分析有助于进一步了解其对钨的刻蚀机理,从而为如何提高钨材料的使用寿命提供一定的理论支撑.采用光纤光谱仪(Avaspec—ULS2048一USB2)检测在不同放电条件下电子回旋共振(electron cyclotron resonance,ECR)等离子体中受激发的钨原子、钨离子谱线的相对强度,从而根据其谱线的相对强度可以直接地反映出不同刻蚀条件下的等离子体对钨表面刻蚀的强弱规律.结果表明:偏压越大对钨表面的刻蚀越严重,气压则呈现先增大后减小的趋势;在N_2-Ar混合气体中随着N,体积分数的增加对钨的刻蚀逐渐增强;而对比He、N,和Ar三种气体,He等离子体对钨的刻蚀最为严重;在700 W、0.1 Pa条件下,0~175 V偏压范围的He等离子体对轧制态钨的刻蚀比再结晶态钨严重,而在175 V之后结果却相反.     

多晶硅的ECR等离子体刻蚀

报道了用CF4作工作气体的ECR刻蚀poly-Si技术,研究了微波功率、气体流量、气压和射频偏置功率对刻蚀速率的影响,并对实验结果进行了讨论.实验中微波等离子体功率范围在100～500 W,CF4气体流量在10～50 cm3/min(标准状态下)范围,气压在0.25～2.5 Pa范围,射频偏置功率在0～300 W范围,对应的刻蚀速率为10.4～46.2 nm/min.     

聚合物薄膜的大气压微等离子体射流无掩膜刻蚀工艺

为优化束斑直径在微米级的大气压微等离子体射流刻蚀工艺,自制搭建一种结构简单、操作方便的大气压微等离子体射流装置,以典型聚合物parylene-C薄膜为对象,研究大气压微等离子体射流处理parylene-C薄膜的刻蚀工艺,分析O₂流量、工作电压、工作间距和刻蚀时间等工艺参数对刻蚀线宽和刻蚀深度的影响。结果表明:增大O₂流量、工作电压、工作间距及刻蚀时间均能增大刻蚀线宽和刻蚀深度;持续增大上述工艺参数,刻蚀线宽和刻蚀深度增加不明显,甚至减小;工作电压和工作间距对parylene-C薄膜刻蚀效果的影响较大,在刻蚀过程中起关键作用,通过调整这两个参数可实现聚合物刻蚀过程的可控调节。     

不同工艺参数对金刚石薄膜齿轮制备的影响

金刚石薄膜是最具潜力的微机械结构功能材料之一,但其极高的硬度和化学稳定性使其难以被加工成型。本文采用反应离子刻蚀方法对金刚石薄膜进行了微齿轮结构的制作研究,制作出了厚度为5gin,模数为0．003的金刚石薄膜齿轮。实验结果表明,镍钛合金薄膜和光刻胶层作为金刚石薄膜刻蚀掩模,可以获得表面平滑、轮廓清晰、侧壁陡直的金刚石薄膜图形;O2及与Ar的混合气体对佥刚石薄膜图形化的刻蚀主要工艺参数如射频功率、工作气压、气体流量及反应气体成分等均对刻蚀速率和刻蚀界面形貌产生不同程度的影响。刻蚀中,当工作气压12Pa及气体流量50sccm稳定时,射频功率与刻蚀速率呈线性变化,但射频功率过高（大于135W）则掩模刻蚀生成物沉积在金刚石薄膜表面而发黑;对于给定的工艺条件下,金刚石薄膜的刻蚀速率并不强烈依赖于混合气体中氧气的含量。     

Nonselective etching of GaN/AlGaN heterostructures by Cl2/Ar/BCl3 inductively coupled plasmas

A systematic study of the nonselective and smooth etching of GaN/AlGaN heterostructures was performed using Cl2/Ar/BCl3 inductively coupled plasmas (ICP).Nonselective etching can be realized by adjusting the BCl3 ratio in the Cl2/Ar/BCl3 mixture (20%-60%), increasing the ICP power and dc bias, and decreasing the chamber pressure. Surface morphology of the etched heterostructures strongly depends on the gas chemistry and the chamber pressure. Specifically, with the addition of 20% BCl3 to Cl2/Ar (4:1) gas mixture, nonselective etching of GaN/Al0.28Ga0.72N heterostructures at high etch rate is maintained and the surface root-mean-square (rms) roughness is reduced from 10.622 to 0.495 nm, which is smoother than the as-grown sample. Auger electron spectroscopy (AES) analysis shows that the effective removal of residual oxygen from the surface of AlGaN during the etching process is crucial to the nonselective and smooth etching of GaN/AlGaN herterostructures at high etch rate.     

Nonselective etching of GaN/AlGaN heterostructures by Cl<Subscript>2</Subscript>/Ar/BCl<Subscript>3</Subscript> inductively coupled plasmas

A systematic study of the nonselective and smooth etching of GaN/AlGaN heterostructures was performed using Cl₂/Ar/BCl₃ inductively coupled plasmas (ICP). Nonselective etching can be realized by adjusting the BCl₃ ratio in the Cl₂/Ar/BCl₃ mixture (20%–60%), increasing the ICP power and dc bias, and decreasing the chamber pressure. Surface morphology of the etched heterostructures strongly depends on the gas chemistry and the chamber pressure. Specifically, with the addition of 20% BCl₃ to Cl₂/Ar (4∶1) gas mixture, nonselective etching of GaN/Al_0.28Ga_0.72N heterostructures at high etch rate is maintained and the surface root-mean-square (rms) roughness is reduced from 10.622 to 0.495 nm, which is smoother than the as-grown sample. Auger electron spectroscopy (AES) analysis shows that the effective removal of residual oxygen from the surface of AlGaN during the etching process is crucial to the nonselective and smooth etching of GaN/AlGaN herterostructures at high etch rate.     

预氧化对滦河天津段高藻期藻类的控制效果

目的 为了提高天津高藻期滦河水藻类的去除效果，保证水厂出水的安全性．方法通过小试静态实验模拟常规混凝沉淀工艺的处理效果和高锰酸盐复合药剂（PPC）、氯（Cl2）、氯氨（NH2Cl）和臭氧（O3）预氧化除藻和除有机物效果进行了研究．结果结果表明，PPC在预氧化除藻、除有机物以及助凝中均表现了良好的性能，30mg／L的Al2（SO4）3混凝条件下2mg／LPPC即可有效提高藻类和有机物去除效果，O3次之．PPC和O3预氧化可以明显提高混凝除藻效果，投量为2mg／L和4mg／L时比单纯混凝时藻类最高去除率分别提高了55％和35％，而Cl2和NH2Cl预氧化除藻效果较差，而且基本没有助凝效果．结论单纯的混凝除藻在经济上并不理想，而在FeCl扑聚合铝、Al2（SO4）3三种混凝剂和高锰酸盐复合药剂（PPC）、氯（Cl2）、氯氨（NH2Cl）和臭氧（O3）中，Al2（SO4）3作为混凝剂与预氧化剂PPC联用能够实现对滦河水天津段的藻类具有良好的控制效果和对有机物的有效控制．     

Effects of MgO content and CaO/Al_2O_3 ratio on surface tension of calcium aluminate refining slag

Surface tension of calcium aluminate refining slag was measured by the Slide method at 1823 K.Based on different levels of the MgO content and the mass ratio of CaO to Al_2O_3,the effects of MgO content and the mass ratio of CaO to Al_2O_3 on surface tension were investigated.The results indicate that surface tension decreased with increasing MgO content(from 0 to 4.86%),followed by an increase with further increasing MgO content up to 11.33%.The trend that surface tension changed with the mass ratio of CaO to Al_2O_3 was the same as the trend that surface tension changed with the MgO content.The surface tension was varied from 0.617 N/m to 0.710 N/m,for the mass ratio of CaO to Al_2O_3 varying between 0.60 and 1.28.An attempt was made to estimate surface tension of CaO-Al_2O_3-MgO slag and its sub-system,and the application showed that the model worked well.     

W-band 3.4 W/mm GaN power amplifier MMIC

A high power density monolithic microwave integrated circuit (MMIC) power amplifier is presented for W band application. The chip is fabricated using the 100 nm GaN high electron mobility transistor (HEMT) technology on a 50 μm SiC substrate. The amplifier is designed for a high gain and high output power with three stage topology and low-loss impedance matching networks designed with high and low characteristic impedance micro-strips and metal-insulator-metal (MIM) capacitors. And quarter-wave micro-strips are employed for the DC bias networks, while the power amplifier is also fully integrated with bias networks on the wafer.Measurement results show that, at the drain bias of 15 V, the amplifier MMIC achieves a typical small signal gain of 20 dB within the frequency range of 88~98 GHz. Moreover, the saturated output power is more than 250 mW at the continuous-wave mode. At 98 GHz, a peak output power of 405 mW has been achieved with an associated power gain of 13 dB and a power-added-efficiency of 14.4%. Thus, this GaN MMIC delivers a corresponding peak power density of 3.4 W/mm at the W band.     

玻璃电极在酸性室温融盐AlCl3—TMPAC中的电化学研究

通过循环伏安法和电流分析法对玻璃电极在酸性室温融盐三氯三甲基苯氨铝中的电化学特性进行了初步研究．铝离子的还原、沉积过程是可逆的,沉积过程包括晶核的形成和增长过程．电流分析法表明,以半球扩散增长方式瞬间形成的晶核导致了铝在玻璃电极上的沉积．     

干氧SiO2的氢氟酸缓冲腐蚀研究

根据对掺三氯乙烯(TCE)干氧氧化的SiO2在不同配比氢氟酸缓冲腐蚀液(BHF)中的腐蚀特性的研究结果表明, 在HF wt%保持不变的条件下,腐蚀速率先随着NH4F wt%的增大而上升;NH4F大于15wt%～20wt%以后,腐蚀速率反而随之降低.值得注意的是,干氧SiO2同湿氧SiO2相比,在1wt% HF条件下,前者的腐蚀速率要比后者高,直到HF酸浓度大于3wt%时,前者的腐蚀速率才低于后者,这一现象可用NH 4 阻挡模型结合TCE在SiO2中引入浅电子陷阱的方式得到解释.     

Impact of strain relaxation of AlGaN barrier layer on the performance of high Al-content AlGaN/GaN HEMT

Owing to large direct bandgap energy, high saturation drift velocity, large conduction band discontinuities, high thermal stability and strong piezoelectric and spontaneous po- larization[1-4], AlGaN/GaN HEMTs have advantages over electronic devices based on Si, GaAs and their alloys in high-frequency, -temperature and -power applications. Many researches show[5,6] that the characteristics of AlGaN/GaN HEMTs depend on two-dimensional gas (2DEG) in heterostructures which has intimate r…     

直流偏磁对不同铁心结构和联结组别变压器感应电动势的影响

特高压直流输电系统单极运行会导致临近变压器出现直流偏磁现象,而变压器感应电动势会对电网电压产生重要影响。为了研究直流偏磁对不同铁心结构和联结组别变压器感应电动势的影响,本文将三相三柱式和五柱式变压器时步有限元模型与YNy和YNd连接的外部电路相结合,建立了能够反映不同联结组别和铁心结构的变压器场-路耦合模型。研究了变压器感应电动势和励磁电流的基波及谐波含量随直流偏磁程度的变化规律,揭示了感应电动势波形畸变率与铁心结构及联结组别之间的关系;最后通过实验验证了结果的正确性。结果表明,直流偏磁对三相五柱式变压器感应电动势的影响较大,采用YNd联结会减小感应电动势波形的畸变率;而直流偏磁对三相三柱式变压器感应电动势基本没有影响。     

Adhesion of NiCu Films DC Biased Plasma-Sputter-Deposited on MgO (001)

NiCu films about 60nm thick were deposited on MgO (001) substrates at 230℃ by DC plasma-sputtering at 2.7kV and 8mA in pure Ar gas using a Ni90Cu10 target. A DC bias voltage of 0, 60, 110 or 140V was applied to the substrate during deposition. The adhesion of the film to the substrate was studied using a scratch test as a function of . The application of is very effective in increasing the adhesion of the film to the substrate. In conclusion, the adhesion increases with cleaning the substrate surface by sputtering off impurity admolecules during the film initial formation due to the energetic Ar ion particle bombardment.