Modeling of silicon oxynitride etch microtrenching using genetic algorithm and neural network

A prediction model of etch microtrenching was constructed by using a neural network. The etching of silicon oxynitride films was conducted in C₂F₆ inductively coupled plasma. The process parameters that were varied in a statistical experimental design include radio frequency source power, bias power, pressure, and C₂F₆ flow rate. The etch microtrenching was quantified from scanning electron microscope images. The prediction accuracy of optimized neural network model with genetic algorithm had a root mean-squared error of 0.03 nm/min. Compared to conventional model, this demonstrates an improvement of about 32%. The constructed model was used to infer etch mechanisms particularly as a function of pressure. Roles of profile sidewall variations were investigated by relating them to the microtrenchings. The pressure effect was conspicuous at lower source power, lower bias power, or higher C₂F₆ flow rate. Microtrenching variations could be reasonably explained by the expected ion reflection from the profile sidewall. The pressure effect seemed to be strongly affected by the relative dominance of fluorine-driven etching over polymer deposition initially maintained in the chamber.     

Bulk micromachining of silicon in TMAH-based etchants for aluminum passivation and smooth surface

The fabrication of silicon based micromechanical sensors often requires bulk silicon etching after aluminum metallization. All wet silicon etchants including ordinary undoped tetramethyl ammonium hydroxide (TMAH)-water solution attack the overlaying aluminum metal interconnect during the anisotropic etching of (100) silicon. This paper presents a TMAH-water based etching recipe to achieve high silicon etch rate, a smooth etched surface and almost total protection of the exposed aluminum metallization. The etch rate measurements of (100) silicon, silicon dioxide and aluminum along with the morphology studies of etched surfaces are performed on both n-type and p-type silicon wafers at different concentrations (2, 5, 10 and 15%) for undoped TMAH treated at various temperatures as well as for TMAH solution doped separately and simultaneously with silicic acid and ammonium peroxodisulphate (AP). It is established through a detailed study that 5% TMAH-water solution dual doped with 38 gm/l silicic acid and 7 gm/l AP yields a reasonably high (100) silicon etch rate of 70 μm/h at 80 °C, very small etch rates of SiO₂ and pure aluminum (around 80 Å/h and 50 Å/h, respectively), and a smooth surface (±7 nm) at a bath temperature of 80 °C. The etchant has been successfully used for fabricating several MEMS structures like piezoresistive accelerometer, vaporizing liquid micro-thruster and flow sensor. In all cases, the bulk micromachining is carried out after the formation of aluminum interconnects which is found to remain unaffected during the prolonged etching process at 80 °C. The TMAH based etchant may be attractive in industry due to its compatibility with standard CMOS process.     

铝基刚挠结合板制作工艺探讨

金属铝基由于其良好的散热性能,广泛应用于LED方面;但随着PCB技术进一步向短、小、轻、薄的方向发展,其平面安装技术在安装空间方面受到了极大的限制,因此,如何实现金属基板三维折叠安装成为业界新的研究课题。对铝基＋软硬结合板的制作工艺进行了可行性探讨,通过铝基表面复合处理工艺＋纯胶预贴局部撕胶十二氧化碳激光切割技术有效实现了金属铝基与挠性电路的有机结合,满足了客户对金属基板实现三维安装的特种需求。     

复杂铝合金零件镀银工艺改进

介绍了复杂铝合金零件镀银工艺,分析了影响铝合金电镀层质量的因素,通过试验改进了铝合金电镀工艺,在常规二次浸锌工艺中增加了电镀锌,采用浸锌电镀锌联合处理法提高了复杂铝合金零件镀银的结合力。给出了工艺流程及各工序溶液配方和相关参数,并提出了相应的操作要点。介绍了生产过程中易出现的问题及解决办法。利用划格法和热震法检验了镀层的结合强度。测试结果表明:采用新工艺加工的零件达到了结合力的要求。     

Kinetics of hillock growth in Al and Al-alloys

Hillock growth kinetics and size distribution were investigated in Al, Al:Si 1% and Al:Si1%:Cu 0.5% layers. Metallization surface was examined by optical, SEM and TEM microscopy, stylus profiling and an automatic method of hillock recognition from a microscope image. The method allowed for counting hillocks in a desired range of their diameter d. Surface density of hillocks was measured as a function of time of furnace annealing at 400°C and as a function of temperature of RTP annealing. A maximum hillock size was found to increase linearly with metallization layer thickness and with logarithm of annealing time. A total area occupied by hillocks was evaluated. Hillock density decreased versus 1/T with an activation energy of 0.28 eV for Al and 0.31 eV for Al:Si. It was found, that a normalized hillock density N may be expressed by a formula N=N₀ exp(−cd). Values for N₀ and c are given together with a short discussion.     

Effect of annealing on characteristics of a HfOxNy-HfO2-HfOxNy sandwich stack compared with HfO2 film

induced leakage current (SILC) investigations.     

Photoelectrochemical properties of porous silicon based novel photoelectrodes

Porous silicon interfaces have been modified with nitrided TiO₂ (TiON) nanoparticles to develop highly efficient photoelectrodes. Photoelectrodes were prepared by impregnating the electrochemically prepared porous silicon microchannels with titanium oxynitride. Photocatalytic measurements were carried out on titanium oxynitride particles in water‐methanol mixture and the results showed a dependence on the nitrogen concentration. Among the photoelectrodes used for photocurrent measurements, porous silicon impregnated with TiO₂ nitrided at 600 °C showed maximum photocurrent increase after exposure to sunlight‐type radiation. The enhancement in photocurrent was one order more for the porous silicon/titanium oxynitride hetero‐structure than that of polished silicon/titanium oxynitride hetero‐structure. Photoelectrodes thus prepared were found to have stable performance for a period of six months. This observation promises the possibility of using porous silicon/titanium oxynitride hetero‐structures as efficient electrodes for photovoltaic cells. Copyright © 2010 John Wiley & Sons, Ltd.     

LED TV铝基板外形加工冲压板面裂纹问题的分析和改善

对LED TV铝基板外形加工冲压板面裂纹问题进行了分析,主要讲述了问题形成的要素和原因,并提出了相对应的改善措施。     

氮氧化硅薄膜红外吸收特性的研究

利用等离子体增强化学气相沉积法沉积氮氧化硅(SiOxNy)薄膜,通过X射线光电子能谱仪、傅里叶变换红外光谱仪、椭偏仪等表征技术,研究不同N2O与NH3流量比R条件下薄膜的组分、光学常数及红外吸收特性.研究结果表明:随着流量比R的增加,SiOxNy薄膜中O的相对百分含量提高,N含量降低,而Si含量基本不变;薄膜由于Si-...     

铝合金5A06激光拼焊板的接头性能及组织研究

利用拉伸试验机、金相显微镜、扫描电镜分别研究了铝合金5A06不等厚激光拼焊板的接头力学性能及组织特点。结果表明,拼焊板的纵向拉伸性能较差,延伸率δ降低幅度较大,拼焊板横向拉伸性能与试样上薄板所占比例关系很大,当薄板占较大比例时,拼焊板具有较大的延伸率,拼焊板的拉伸变形能力随着薄板所占比例的减小而逐渐变差；拼焊板的焊缝组织极为细小,在熔合线附近开始向焊缝中心生长的是树枝状晶,在焊缝中心是等轴晶。