MEMS工艺中TMAH湿法刻蚀的研究

TMAH具有刻硅速率高、晶向选择性好、低毒性和对CMOS工艺的兼容性好等优点，而成为MEMS工艺中常用的刻蚀剂。但TMAH在刻蚀过程中合形成表面小丘，影响表面光滑性。文章重点研究了MEMS工艺中的TMAH湿法刻蚀获得光滑刻蚀表面的工艺。实验结果表明，要获得理想的刻蚀效果，刻蚀液配方和刻蚀条件的选择是非常重要的因素，实验中也得到了一些与其它报道不同的数据。     

Analysis of structurally modified polyacrylamides by on-line thermochemolysis-GC–MS

Cationically modified polyacrylamides (cPAA) are commonly used flocculants in sewage water treatment processes. Therefore, those compounds are quantitatively important contaminants in sewage sludges, which were deposited on agricultural soils as fertilizers in the past and even today in many countries. In order to monitor environmental pathways and to correlate ecotoxicological effects with quantitative data, there is a necessity for methodologies for quantitative analyzes of technically applied polyacrylamides. The present investigation provides a fundamental proof of the verifiability of cPAA in particulate samples by on-line thermochemolysis-GC–MS in presence of tetramethyl ammonium hydroxide. This methodological approach induces degradation of cPAA to glutarimide related structures. Experiments were carried out on pure cPAA, spiked sediments and sewage sludges. The results revealed a linear correlation between thermochemically degraded quantities of cPAA and abundances of glutarimide related degradation products as well as a theoretical limit of detection of 250 mg/kg, which is sufficient for corresponding analyzes concerning sewage sludges. Thermochemolysis experiments on polyacrylamide and anionically modified derivates revealed the same glutarimide related degradation products as obtained by degradation of cPAA.     

高性能高温压力传感器

研究了决定多晶硅压力传感器性能的两项关键技术：各向异性腐蚀硅杯和温度自补偿。通过研 究四甲基氢氧化铵（ＴＭＡＨ）腐蚀液特性，及在不同腐蚀条件下硅杯表面状况，确定了制作高质量硅杯的工艺 条件。通过优化掺杂浓度，改善了传感器的温度特性，基本上实现自补偿。测试结果表明，多晶硅压力传感器 综合精度达０．ｌ％～０．２％ＦＳ，灵敏度温度系数绝对值小于３ × １０－４／℃，有广阔的应用前景。     

Applications of Inverted Pyramids Corroded by TMAH in PERL Silicon LED

In this paper,a novel and reliable structure of the side passivated emitter and the rear locally-diffused(PERL)silicon light emitting diodes(LEDs)is proposed.The inverted pyramids surface,the important interface in this structure,is given according to the experiment.The results show that the inverted pyramids surface has a low refection about 8%,in the anisotropic etching 70 ℃,5% TMAH concentration,corrosion time of 90 min or 30 min.Low refection means high light emitting rate.Most of the structure and manu...     

四甲基氢氧化铵在MEMS中的应用

通过各向异性腐蚀硅杯实验,研究了四甲基氢氧化铵（TMAH）腐蚀液的特性,包括硅（100）面腐蚀速率与溶液浓度、温度的关系,不同腐蚀条件下硅杯的表面状况,并确定了制作硅杯的最佳工艺条件。通过测试硅杯结构多晶硅压力传感器的输出特性,证明了TMAH确实是一种性能优良的各向异性腐蚀剂。     

硅各向异性浅槽腐蚀实验研究

通过实验分析,对比了异丙醇(IPA)和超声波对Si(100)面在KOH溶液和四甲基氢氧化氨(TMAH)溶液中的浅槽腐蚀速率及其表面形态的影响。实验结果表明,IPA能降低TMAH溶液的腐蚀速率,但IPA在KOH溶液中腐蚀速率降低不明显;IPA加入到较高浓度的KOH溶液中,会在Si表面产生较大小丘,恶化了Si腐蚀表面的质量,但在TMAH溶液中加入一定量的IPA会改善腐蚀表面的质量;超声波能加快腐蚀速率并能改善Si腐蚀表面质量,但对于加入IPA的较高浓度KOH溶液,超声波未能消除Si腐蚀表面的小丘,另外,超声波还能减弱腐蚀过程中微尺寸沟槽的尺寸效应;在腐蚀条件和配比一定情况下,TMAH溶液的腐蚀质量比KOH溶液好。     

In situ nanoscale refinement by highly controllable etching of the(111) silicon crystal plane and its influence on the enhanced electrical property of a silicon nanowire

Nanoscale refinement on a(100) oriented silicon-on-insulator(SOI) wafer was introduced by using tetra-methyl-ammonium hydroxide(TMAH,25 wt%) anisotropic silicon etchant,with temperature kept at 50℃to achieve precise etching of the(111) crystal plane.Specifically for a silicon nanowire(SiNW) with oxide sidewall protection,the in situ TMAH process enabled effective size reduction in both lateral(2.3 nm/min) and vertical (1.7 nm/min) dimensions.A sub-50 nm SiNW with a length of microns with uniform triangular cross-section was achieved accordingly,yielding enhanced field effect transistor(FET) characteristics in comparison with its 100 nm-wide pre-refining counterpart,which demonstrated the feasibility of this highly controllable refinement process. Detailed examination revealed that the high surface quality ofthe(111) plane,as well as the bulk depletion property should be the causes of this electrical enhancement,which implies the great potential of the as-made cost-effective SiNW FET device in many fields.     

Towards identification of traditional European and indigenous Australian paint binders using pyrolysis gas chromatography mass spectrometry

We report a pyrolysis GC–MS method capable of analysing Indigenous Australian and European binders typically used in the manufacture of culturally important painted works. Eleven different traditional European binders and ten different Indigenous Australian binders were examined. The method allows discrimination between highly complex and impure lipid, resin, polysaccharide, wax, and protein-based binders. Each was found to have characteristic pyrolysis products that were unique to the binder material, demonstrating the potential for differentiation of these binders on Australian Aboriginal artworks towards identification and conservation of cultural heritage.     

Determination of benzoic acid in soft drinks by gas chromatography with on-line pyrolytic methylation technique

A new application of pyrolytic methylation was developed to determine benzoic acid in soft drinks by gas chromatography (GC) without using any pretreatment procedures and special pyrolyzer. With the on-line pyrolytic methylation by tetramethylammonium hydroxide (TMAH), benzoic acid was converted into its corresponding methyl ester in the injector at 280 °C. Thus, samples containing benzoic acid could be well determined by direct-injection in GC on the medium polar stationary phase column. To obtain optimum methylation conditions, important factors were investigated and then applied to the following experiments. The results were obtained as following: 280 °C as reaction temperature, 2:1 as the proportion of TMAH to benzoic acid. The storage time of mixed solution had no obvious effect on the area of benzoic acid methyl ester peak. With the p-xylene as an inter-standard, GC behaviors were investigated under these optimum conditions. The linear range achieved for benzoic acid was 1-10,000 mg/l with the correlation coefficient of 0.9985. The precision was quite high with the R.S.D. of 2.8% and the limit of detection reached 0.1 mg/l. The potential of the proposed method was assessed by applying it to the determination of benzoic acid in soft drinks. The results obtained coincided with the statement on the labels and all of the detected data were below the maximum permitted concentration of the European Union Legislation. This on-line pyrolytic methylation technique was proved to be simple to implement, sensitive and selective.     

微薄膜结构的湿法腐蚀技术研究

通过对流量传感器制造工艺中微薄膜结构的研究,分别介绍了采用氢氧化钾和四甲基氢氧化铵(TMAH)交替腐蚀实现感应薄膜释放的基本原理、工艺方法、工艺参数,及在制作流量芯片中的具体应用实例,实现了微米级厚度薄膜释放,为流量传感器和其它需要超薄薄膜微结构的制作奠定了基础。