摘要
微／纳米科学技术作为二十一世纪的关键高新技术之一，将导致人类认识和改造世界能力的重大突破。而具有强烈交叉学科色彩的微系统(或微机电系统，MEMS)可能迅速崛起和蓬勃发展，成为微／纳米科技中的核心之一。为充分发挥微系统的功能和用途，需要制备较为复杂和高性能的微结构，因此必须发展和建立新型的加工技术。适宜于微系统的新型的加工技术应能满足如下三方面的要求：(1)能够加工复制出真正的超微复杂三维微加工图形或器件；(2)可批量生产；(3)达到微／纳米尺寸。
早在1992年，田昭武院士等就提出了约束刻蚀剂层技术(Confined EtchantLayer Technique，简称CELT)，是一种具有距离敏感性及控制保留量等特点，可用于三维超微(纳米)图形复制加工的新型技术，原则上它能同时满足上述三方面的要求，即可实现分辨率在微米、纳米级的复杂三维微细图形的复制加工。近十年来，我们实验小组不仅对CELT的相关理论问题进行了进一步探讨，并根据此原理对一些简单以及较为复杂的三维结构进行了加工刻蚀实验，表明CELT用于三维微结构加工刻蚀是可行的。但是该微结构是任意的，用规整模板复制加工更能体现CELT技术的优势。本论文基于此开展了下面的一些研究工作：一、 化学模板电极的制备
设计出微齿轮状、金字塔状等规整微图形，通过合作单位利用体硅工艺制成硅材料的模板。
通过射频溅射技术在Si基底模板上镀大约几百个纳米导电层(在镀Pt或
摘 要
An之前，先镀几个纳米厚的Cr或Ti以增加镀层的牢固性）。实验发现，在以
Br。作刻蚀剂的电化学刻蚀体系中，An镀层易被腐蚀破坏，而且会沉积到工件表
面；所以在实验中，我们均采用Pt镀层。
通过射频溅射镀Pt膜的方法，让Pt膜作为连线，使棒与模板表面导通。
在溅射镀膜时，模板的放置试用了两种方式：一种是模板表面与靶材表面平行，
另一种是模板表面与靶材表面垂直。实验表明，后一种方式效果最好，既能使
连接棒与模板表面导通，又不使模板表面的导电层沉积过厚。
采用恒电流方法，以模板作为工作电极，测试在不同电流密度下模板的使
用寿命。结果发现，在电流密度小于1．OX10－‘A／Cof时，模板可以进行20次以
上刻蚀实验；电流密度远大于 1．0 X 10W Cmz时，模板表面的镀层 Pt，12次实
验后就脱落。
通过逐渐优化制作过程，摸索出一条较为成熟电化学模板的制作工艺。
二．用规则模板对半导体GaAs的加工刻蚀
1．齿状模板对GaAS的加工刻蚀
用同一模板在GatS表面刻蚀出的两个图形，被刻蚀出的是模板的负像。
其上的十字状结构及中间的齿状微结构都非常相似。说明CELT技术可以进行批
量复制。样品GaAS表面的九条凹槽与模板图形互补，实现了模板立体微结构图
形的复制。
2．金字塔状阵列模板对GaAS的加工刻蚀
GaAs样品表面被刻蚀出一规整微孔组成的阵列。微孔深度在 1．ffel．8 11m之
间。两相邻微孔最低点间的距离为14．9 P m，与模板上两相邻“金字塔”状锥体
最高点间的距离 15．4 11m基本吻合。通过比较计算得到实验加工精度大约在 1
卜m左右。同时分析了样品表面图形的形状与原模板的负像相比发生了变化伯
由方锥孔变为圆锥孔）的原因。
n
摘 要
三．CELT技术用于抛光刻蚀
以抛光微圆盘电极作模板对粗糙的GaAS表面进行平整，获得了表面粗糙度更
小的平整表面，显示了CELT技术作为一种平面抛光手段的潜力。
Micro- and Nanometer science and technology, which will lead to a great
breakthrough in understanding and transforming the world is considered to be a key
Hi-tech in 21st century. The micro system or microelectromechanical systems
(MEMS), as an interdisciplinary field, will be a core of micro- and nanometer
science and technology. In order to exert the potential of MIEMS, a new
micromachining method that is capable of generating complex and high performance
microstructures must be further developed. The method that is suitable for
microfabrication should meet the following three requirements: (1) capable of
replication of real complex ultramicro-patters and units; (2) capable of mass product;
(3) producing units in the micro/nano-meter scale.
The Confined Etchant Layer Technique (CELT) as a new approach of
electrochemical three-dimensional micromachining was proposed by Prof Zhao-Wu
Tian in 1992.This method is distance sensitive and controls the quantity of survival
(in comparison with the current micromachining techniques, which control the
quantity of removal), which makes the replication of ultramicro three dimensional
patterns possible. In the recent ten years, the further analysis on the CELT theory was
done and microfabrication experiments were performed with simple micro-disk
electrode and spherical platinum electrode, the results show the method is feasible in
fabricating three-dimensional micro-pattern. However, in previous study, the
selection of the micro-pattern was arbitrary. Three-dimensional microfabrication
using regular pattern mold will outstand the advantage of CELT. The results of
present work are described as followed
1. Preparation of electrochemical molds
Molds with regular microstructures were fabricated by bulk silicon etching
technique on silicon wafers. As the electrochemical mold must have excellent
conductance, a Cr or Ti film with thickness of several nanometers was sputtered as
adhesion layer before a Pt film with thickness of several hundreds nanometer was
deposited on the mold surface .The conductive connector between the mold surface
and the lead was also a sputtered Pt film along the side of the silicon after the mold
was fixed at the tip of a metal stick.
In order to test the lifetime of the electrochemical mold, the etching process was
performed using it as the working electrode at different constant currents. It was
found that the electrochemical mold could be used for more than 20 times when the
current density i is lower than 1.0 X 102k1 cm2 ; However, when the current density
was much higher than 1.0 X 10 A/ cm , the sputtered Pt film would be fallen off
only after 1-2 experiments
2. Fabrication of GaAs with regular patterns molds
Two etched patterns resembled each other were obtained with the same gear-like
mold. The etched pattern has nine slots and eight protruding lines, compared with the
mold, it is almost the negative copy of the mold.
The etched microhole arrays were obtained on a GaAs surface. The depth of the
holes varies from 1.61?m to 1.81?m. The distance between the bottom point of the
two nearest holes is 14.9 t~?m which is in agreement with that of 15.4 ii m between
the highest point of two adjacent pyramids. The precision of the etching in this
experiment was ca. I ii in. The reason for the transformation of the shape from
pyramid for mold to cone for the workpiece was discussed.
3 .Polisbing surface of semiconductors with CELT
引文
[1] 丁衡高，仪器仪表学报，1995，16(1)：1
[2] 张立刚．MEMS发展的重要性．国家重点基础研究发展规划培植项目《集成微光机电系统研究》研讨会论文集．1999年3月6-7日，上海
[3] Motamedi M E, Wu M C, Pister K S J. Micro-electro-mechanical devices and on -chip optical processing [J]
[4] Wu M C, Proceeding of IEEE, 1997, 85:1 883
[5] Manz A, Becker H, Eds. Microsystem technology in chemistry and life Science [M] Berlin: Springer, 1998,51.
[6] Ma L, Modern Scientific instruments, 1999,3:3
[7] 马立人．生物芯片．现代科学仪器，1999，3：3
[8] 晓石．制造世界上最快的CPU．中国计算机，1997，4：9
[9] Romankiw L T, Electrochimica acta, 1997,42:2985
[10] 周兆英，叶雄英等，微米／纳米科学与技术，1996，12(1)：1
[11] H Y Liu, F R Fan, C W Lin and A J Bard, J Am Chem Soc, 108, 3838(1986)
[12] A J Bard, F R Fan, J Kwak and O lev, Anal Chem, 61,132(1989)
[13] J Kwak and A J Bard, Anal Chem, 61, 1221 (1989)
[14] J Kwak and A J Bard, Anal Chem, 61, 1794(1989)
[15] C Lee and A J Bard idid, 62, 1906(1992)
[16] A J Bard, F R Fan, D T Pierce etc, Science, 254(1991)
[17] F R Fan and A J Bard, Science, 270, 1851 (1995)
[18] E R Scott, H S White and J B Phipps, Anal Chem. 65. 1537 (1993)
[19] D T Pierce and A J Bard, Anal Chem 65, 3598(1993)
[20] B R Horrocks, D Schmidtke, A Heller and A J Bard, Anal Chem 65, 3605 (1993)
[21] A J Bard, G Denuault, C Lee, D Mandler and D O Wipf, Acc Chem Res 23, 357 (1990)
[22] D Mandler and A J Bard, Langmuir, 6, 1489 (1990)
[23] D Mandler and A J Bard, J Electrochem Soc 136, 3143(1990)
[24] D Mandler and A J Bard, ibid, 137, 2468(1990)
[25] D Mandler and A J Bard, ibid, 137, 1079(1990)
[26] D Meltzer and D Mandler, J Chem Soc Faraday Tran, 91, 1019(1995)
[27] D H Craston, C W Lin and A J Bard, J Electrochem Soc, 135(1988)
[28] H Shiku, T Takeda, H Yamada, T Matuse and I Uchida, Anal Chem, 67, 321 (1995)
[29] K Borgwarth C Ricken, D G Ebling and J Heinze, Bunsenges Phys Chem, 99, 1421(1995)
[30] Cohen A et al, Santa Clara, CA, September 22,1999
[31] Cohen A et al, 1999,Technical Digest, IEEE.
[32] Cohen A et at, The University of Texas at Austin
[33] Schuster R, Kircher V, Allongue P, Ert G. Science. 2000, 289: 98. Microscopy. Faraday Discussion, 1992, 94:37
[34] 蒋新荣编著．微细加工技术．北京：电子工业出版社，1990．
[35] 余承业编著．特种加工新技术．北京：国防工业出版，1995．
[36] 叶玉堂编著．激光微细加工．成都：电子科技大学出版社，1995．
[37] Romankiw LT. A path from eletroplating through lithograhic masks in electronics to LIGA in MEMS. Electrochimica Acta, 1997, 42:2985
[38] 田昭武，林华水，孙建军，周勇亮等，微系统科技的发展及电化学的新应用，2001，7(1)：1
[39] Tian Z W, Feng Z D, Tian Z Q, et al. Confined Etchant Layer Techniques for Two-dimensional Lithograpy at High Resolution using Electrchemical Scanning Tunneling
[40] 苏连永，厦门大学理学博士论文，1995．
[41] 谢雷，厦门大学理学博士论文，1996．
[42] 祖延兵，约束刻蚀剂层技术研究，厦门大学博士后研究工作报告，1998．
[43] 田昭武，田中群，林仲华，谢兆雄，罗瑾，毛秉伟，谢雷，苏连永．复杂三维超 微图形的复制加工技术的困难及对策．仪器仪表学报，1996，17：14．
[44] 罗瑾，苏连永，吴金添，林仲华，田昭武，电化学，1995，1：270．
[45] Zu Y B, Xie L, Mao B W, Tian Z W. Studies on Silicon Etching Using the Confined Etchant Layer Technique. Electochimica Acta, 1998, 43: 1683.
[46] 黄海苟，孙建军，叶雄英，将利民 罗瑾，卢泽生，董申，田中群，周兆英，田昭武．用规整模板对砷化稼的三维微结构图形加工刻蚀．电化学，2000，6：253．
[47] Sun J J, Huang H G, Chen Y A, Yan J W, Xia S H, Liang L M, Tian Z Q, Tian.Z.W. Fabrication of Microhole Arrays with Confined Etchant Layer Technique. Chemical Journel of Chinese University, 2000, 21,425 (Suppl.)
[48] Sun J J, Huang H G, Tian Z Q, Xie L, Luo J, Ye X Y, Zhou Z Y, Xia S H, Tian Z W. Three Dimensional Micromachining for Microsystems by Confined Etchant Layer Technique. Electrochimica Acta, 2001 (Accepted)