Showing posts with label Thin Film 薄膜. Show all posts
Showing posts with label Thin Film 薄膜. Show all posts

Saturday, May 05, 2007

莱宝APS离子源


一年前在真空论坛许老师曾深入的讨论过此问题,由于论坛上常出现帖子丢失现象,现在将其部分内容以及自己当时的帖子整理一下,以便自用。


“以下是引用许在2005-3-30 8:53:00的发言:

莱宝APS1104光学镀膜机可以说是目前国内镀膜界的王牌。这个镀膜机主要是两台电子蒸发源何一台APS离子源组成。其APS离子源可以说是镀膜机的心脏,其结构十分独特。首先它是Kaufman型离子源,但其阴极不是常用的钨丝,而是昂贵的LaB6材料。另外其磁场不是由永久磁铁产生,而是由电磁线圈产生。从参数来看,其磁场较弱,功率也不大,但其显著特点是在被镀工件上产生的温度低,其各项参数调得使成膜时热力学平衡好,成膜致密。可以说目前国内高档光学镀膜全靠莱宝机,尽管其价格远远高于其他镀膜厂家。

再谈谈莱宝APS离子源。因为这个离子源太独特了,随APS镀膜机,特别是APS1104在国内光学镀膜界的大量采用而为许多用户。APS是Advanced Plasma Source的打头缩写。顾名思义,是先进等离子源。我开始错误的认为它是Kaufman源,后来又觉得它与霍尔源接近,其实它谁都不像,就像它自己。它有些什么特点呢?
1 用很粗大的根BLa6棒作阴极2 很长很深的阳极管包围着阴极3 另外有一个加热BLa6阴极达1500度的加热器4 另有一层法拉第屏蔽5 进气管在离子源出口而不在底部6 功率非常大,光加热器就1.8千瓦,发射功率达15千瓦根据以上特点,做点主观分析:1 BLa6阴极电子发射效率较高,热稳定性相对钨丝要好一些,可提供大电子流,较长运行时间。
2 阳极管长深对离子发射有利(电场长)
3 可将BLa6阴极加热到1500的加热器水平的确高,就像在真空室放了一个炼钢炉,如何保温,冷却。就是电磁线圈的绝缘漆就是一个难题,又要出气率低又要耐一定温度(当然不是1500,因为该离子源采用了水冷却底座)
4 法拉第屏蔽在这里可能就有点讲究,该屏蔽,阴极,阳极应该处在不同电势
5 进气管在顶部容易理解,因为底部有一个“火炉”。但整个离子源好像把气体拉进阳极管离子化后在发射出来
6 功率之大很少有其它离子源能比,但其能级却能控制在250电子伏特以下,对无栅离子源来说真不容易。
7 采用电磁线圈作磁场源看来很笨(体积大,多一套电源),但却增加了可调节参数8 由于电子流大,调节参数多,粒子流在阳极管内基本上完全中和。以上只是一些主观分析。欢迎实际用过APS离子源的同行参加讨论”
------------------------------------------------------

xbimr于2006-4-2 15:08:40编辑过

请教:
(1) “4 另有一层法拉第屏蔽”------法拉第屏蔽的作用是干什么的啊?这个不明白
(2) “ APS是Advanced Plasma Source的打头缩写。顾名思义,是先进等离子源。我开始错误的认为它是Kaufman源,后来又觉得它与霍尔源接近,其实它谁都不像,就像它自己。”------------------个人认为它可能是Kaufman与霍尔源的一个结合体:),采用用很粗大的根BLa6棒作阴极,类似欲Kaufman源那样通过外加电子来降低等离子体工作压强,或者达到增加功率密度的目的;而对于它的等离子体引出系统则是借鉴霍尔源的引出系统的原理,通过不均匀磁场之间的电位差(方向是内部高于出口)来加速在等离子体区域的离子,将它引出,这样可以采用无栅极的,也就没有什么阴极污染/烧蚀问题,此外离子流密度大小也不受所谓空间电荷限制的制约;另外从它的离子流能量分布是介于20——200EV之间,这个范围也是通常霍尔源的能量范围,估计它的能量分布范围也比较宽,这些都是霍尔源引出系统的特点,也是适用于薄膜制备的能量范围,所以用于光学镀膜。
(3) 它采用电磁线圈的原因可能在于,通过改变磁场,随即改变电位梯度,随即改变离子加速的能量,达到控制离子能量的目的?假如采用固定磁场,就少了控制控制离子能量的一个方法(4) APS离子源的离子能量对于有些薄膜,特别是关心电学性能等物理性能的薄膜植被来说,能量还是偏高了,最好应该小于20-30EV,这个范围能量的,一般是需要什么样的离子源可以达到要求,而且同时要保证相对离子流密度不能太小和不均匀??-----个人瞎掰,敬请指教:)
-----------------------------
APS等离子体源工作原理

出处:apsLaB6 2007年07月12日 11:09 阅读 57 次我单位提供质优价廉的德国Leyblod APS镀膜机国产LaB6阴极,目前已经批量生产,性能稳定,销往国内外,成功应用在德国Leyblod APS镀膜机的APS源上,所镀出的产品包括,IR-Cut Filter,紫外红外截止滤光片、红绿蓝(RGB)滤光片、窄带滤光片、二向色镜、介质高反膜、晶体镀膜,各种增透膜等镀膜产品。详细资料请来信联系: apspart@yahoo.com.cn,或留言。我们将提交相关资料供参考:性能参数、激活记录、使用记录(放电电压Vd、偏压、放电电流IC)、及实际镀膜产品的曲线。 APS是Advanced Plasma Source的缩写,原理如下图。等离子体源位于真空室底部,由LaB6阴极、阳极筒和螺旋磁场构成。圆柱形LaB6由石墨加热器直接加热。介于阳极和阴极之间的直流电压建立了一个带有电子的辉光放电等离子体,工作气体是Ar气。由于阳极筒周围螺旋磁场的作用,在磁力线方向等离子体电子迁移率迅速增加,而在阳极筒半径方向迅速减少。随着电子沿磁力线方向运动,等离子体就从阳极筒中射出,并射向基板。反应气体(O2)从阳极筒上方的管道中流出来。在高密度、高能量的等离子体的作用下,反应气体变得有活性并且部分被电离。反应气体的电离降低了反应气体的压强,这对于增加薄膜的化学计量(stoichimetry)是必需的。随着等离子体在真空室的扩张,蒸发物也被部分电离。对金属的电离是特别有效的。除了离子辅助镀的作用产生以外,也产生了电镀效果(电镀:利用电解作用使金属或其它材料制件的表面附着一层金属膜的工艺)。等离子体源与真空室的地面是绝缘的。由于等离子体中电子的高迁移率效果,产生了一个相对于真空室内壁和基板间的正的自偏压(Bias)。离子能量主要由自偏压决定。偏压的量级依赖于放电电压、磁场强度和真空室压力(Ar和O2的流量决定)。在被加速的等离子体离子的冲击及迁移下,基片表面薄膜的迁移率及填充密度就有所增加。与此同时,等离子体中的电子与膜层表面的正离子起到了中和作用,促进了等离子体对基板轰击的一致性。被电离的Ar+离在电场的作用下,对LaB6阴极溅射,这样LaB6阴极就会源源不断的产生大量的电子。等离子体高效的作用使得薄膜的增长速度可以很高,典型值可在0.5—1.5nm/s,具体值由蒸发物决定。虽然APS大部他是可用来提高生产量和性能,但是它也可用来随意的控制薄膜的性质,如密度、化学计量、折射率、甚至是薄膜的应力。


More......

Tuesday, January 30, 2007

Hi, Belgian. Hi, Ghent

I am excited and happy to find that one belgian guy visited my blog this morning. U are the first unknown foreinger visited my new blog after establishing it. Thanks for your visiting and welcome more friends here!

Now i want to introduce the research work of a student, S. Mahieu, from Ghent universit, Belgium. one man i also admired very much, not only because he published an excellent invited review on SZM (stucture zone model, specially for sputtering) as a student but his insight and independent thought.

As for his main opinion, u can glance over the graph below, and the details can be refered to the article: "Biaxial alignment in sputter deposited thin films" by S. Mahieu et. al at http://dx.doi.org/10.1016/j.tsf.2006.06.027 .



More......

Monday, January 29, 2007

Different shape, Same principle


Recent years one "new" sputtering technique has also emerged (see the attached text below), which was proposed by several vacuum companies in the different shapes but same principle. It seems like a diode sputtering except for combinating with an external ion soure.

It is well known that the diode sputtering suffer from the low ionization efficiency which result in high voltage and low deposition rate. So this technique was almost abandoned after the invention of magnetron sputtering several decades ago. although the magnetron sputtering technique have the advantage of higher local ionization, low cathode voltage, and high deposition rate, etc., it subjects to the low target utiliztion "racetrack" originated from the confined plasma (所谓成也萧何,败也萧何, 呵呵). Various efforts mainly by rotating the magnet or target have been adopted to improve the utiliazition, from the typical <30%>90%) target utilization. Of course, one coin has two sides. u should pay the addtional cost for the plasma soures, and it is suitable only when the benefit u gain can offset the added cost.

Anyway, we can get some beneficial inspiration from this example that 1+1>2, and we should rethink the techniques look like outdated. Something is bad in certain condition but it maybe become good under another condition. BTW, i think the configration of PQL is more reasonable than that of 4Wave. Do u think so? -__- .



"4Wave was founded in August 2000 by senior technical and management staff of the former Commonwealth Scientific Corporation (CSC), a leading manufacturer of ion beam sources and equipment acquired by Veeco Instruments in May 2000. The company's founders are the world's leading experts in ion beam deposition processes, and have developed the first-ever ion beam deposition production system, still in use by IBM for its most advanced product offerings. Our multidisciplinary staff bring an average of 15 years of experience in electrical, mechanical, software, process and system engineering. Sami Antrazi, President, has more than 12 years of engineering management and customer development experience. His professional career combines managerial, business development, and technical expertise in the capital equipment industry. Prior to joining 4Wave, he directed the electrical, mechanical, and software engineering departments at CSC. He also conducted advanced robotics research for space applications for three years with NASA's Goddard Space Flight Center. He holds a Ph.D. (ABD) and an M.S. in electrical engineering from Catholic University in Washington, D.C."

http://www.4waveinc.com/ds.html



"Plasma Quest Ltd (PQL) founded by Professor Mike Thwaites in 1998 is a problem solving research-based company whose core business is thin film deposition sputtering research, and systems development. PQL has developed a high-density plasma method of thin film sputtering that provides process and thin film deposition benefits not currently available from conventional systems - the patented technology, “High Density Plasma forming device” is operationally referred to as High Target Utilisation Sputtering (HiTUS)."
http://www.plasmaquest.co.uk


More......

Sunday, January 28, 2007

Memo for my first paper

My first two papers have been published online this month with some kind friends' help. It is a little shame for me to say it, because it take me over three years to achieve this course, and many my classmates have already published a long list of good papers until now. However, i learned a lot from the course. Now i want to have a conclusion and share some with others.

1> Avoid to publish the paper for the sake of publishing itself as possible. We will not feel any happy but depressed at last if one day we found that our paper had no any indeed contribution to our field. Unfortunately, i also did bad in it before, so it is my lesson.
2> Design and consider the experimental details before beginning it.
3> Put emphasis on the analysis of data, and be sure of their accuracy. As for how to get a beautiful graph, we can refer to one excellent PPT "how to deal with the data".
4> Learn some scientific writing skills. The details may be refered to some excellent articles such as "how to write a paper" by a professor of Cambridge.
5> Put the draft on the desk and revise it several weeks/months later. Alternatively, send it to others for the review if possible before the post.
6> Be concise as possible. One common problem for the freshman like me is that we used to stack all that we know not the new finding.
......

If you have interest in my papers, you can reach it at the following address:

X.B. Zhang, Z. L. Pei, J. Gong, C. Sun, “Investigations on the electrical property and inhomogeneous distribution of ZnO:Al thin films prepared by dc magnetron sputtering at low deposition temperature”, J. Appl. Phys. 101, 014910 (2007). [Link][Full Text].

[ It is a developing trend to deposite thin films and fabricate the device at the lower processing temperature, the same to the preparation of TCO films such as AZO by magnetron sputtering. However, there are still some difficult problems to solve that the properties of TCO films are severe degraded and inhomogeneous under the low temperature processing conditions. Although many researcher have already investigated it, there are not a clear and consistent explaination on the origin of the inhomogeneity in the literature. This paper was aimed to clarify the two existing main opinions and deduce some feasible methods. I ever thought that my opinion was undoubtable. Now i think that i should do more experiment and give more sufficient evidences to support the viewpoint because we used to trust in our own opinion too easy and hardly oppugn it, although i don't think my opinion is wrong until now. ]

X.B. Zhang, J. Q. Xiao, Z. L. Pei, J. Gong, C. Sun, “Influence of external solenoid coil arrangement and excitation mode on plasma characteristics and target utilization in a DC-magnetron sputtering system”, J. Vac. Sci. Technol. A 25, 209 (2007). [Link] [Full Text].

[The improvement of target utilization and the independent control of plasma growth parameters are still two critical issues and worth concerning further. However, the research objective of this paper is a gradually outdated and abandoned technique (this method appeared in the beginning of 1990s). Therefore, it is more wise to do research on the promising technique; but i had no wide enough eyeshot and deep understanding on this field in the beginning. Of course, hope that there are still few useful elements existed in it. ]

More......

Friday, January 26, 2007

TCO niuniu in my eyes (1) ---- K. Ellmer


Results found:60 Sum of the Times Cited :819 Average Citations per Item : 13.65 h-index :17




















In my eyes, Dr. Klauss Ellmer is one of admiring scientists in the area of TCO (transparent conducting oxide) films, especially Al-doped ZnO films (AZO) by magnetron sputtering. Now he work in the solar energy division of Hahn-Meitner-Institut Berlin as a senior researcher. According to the statistic of ISI web index (up to 2006), he authored only 17 papers about AZO films in the last decade. However, the total of cited number is over 340 times, approximately 20 times per paper. Maybe somebody think that the number is just so so, but it is considerable if we take into account that the research on AZO films by magnetron sputtering has been intensively carried out by numerous groups, and not achieved a great breach in the last two decades.
His main contribution to this field is correlating the plasma parameters with the microstructure, electrical, and optical properties and having a systemtic investigation on AZO films using this method. We often found that the results of diffirent authors in the literature conflicted each other even though they used the same preparation method, same external parameters. This make us lost! and it is difficult to make a clear and reliable correlation between the process conditions and film properties. Therefore, his approach, probably inspired from the classic work on TiN coatings by Petrov group (another pioneer i admired will be introduced in later articles ), is more insightful and necessary for a better understanding of TCO materials.

In the last years such an approach was reported only on few papers, in order to achieve further progress in understanding and reproducibly produce TCO films, the interplay between the microparameters (plasma parameters, not only external parameters) and film quality has to be investigated much more in detail.
P. S. : Partial representative papers:
1. Cebulla R, Wendt R, Ellmer K Al-doped zinc oxide films deposited by simultaneous rf and dc excitation of a magnetron plasma: Relationships between plasma parameters and structural and electrical film properties JOURNAL OF APPLIED PHYSICS 83 (2): 1087-1095 JAN 15 1998 Times Cited: 67
2. Ellmer K Resistivity of polycrystalline zinc oxide films: current status and physical limit JOURNAL OF PHYSICS D-APPLIED PHYSICS 34 (21): 3097-3108 NOV 7 2001 Times Cited: 51
3. Ellmer KMagnetron sputtering of transparent conductive zinc oxide: relation between the sputtering parameters and the electronic properties JOURNAL OF PHYSICS D-APPLIED PHYSICS 33 (4): R17-R32 FEB 21 2000 Times Cited: 51
4. ELLMER K, KUDELLA F, MIENTUS R, et al.INFLUENCE OF DISCHARGE PARAMETERS ON THE LAYER PROPERTIES OF REACTIVE MAGNETRON-SPUTTERED ZNO-AL FILMS THIN SOLID FILMS 247 (1): 15-23 JUL 1 1994 Times Cited: 44
5. Hinze J, Ellmer KIn situ measurement of mechanical stress in polycrystalline zinc-oxide thin films prepared by magnetron sputtering JOURNAL OF APPLIED PHYSICS 88 (5): 2443-2450 SEP 1 2000 Times Cited: 25

More......

Wednesday, January 24, 2007

Manual for FTG (Film Thickness Module)

I found a free software (FTG, Film Thickness Module) which can be used to determine the thickness of thick films ( usually suitable for the transparent films exceeding 200-300 nm thickness ). Hehe, how about the precision? i don't know :), the details can be refered to the linked paper. Personal viewpoint, the error depending on the value of n, k could be toleranced for the most cased. Fortunately, now the personal manual for FTG has been completed by zmliu which can be reach it at the fellowing address:
http://xbzhangcn.googlepages.com/%E5%AD%98%E6%A1%A3

The Film Thickness Module includes both fringe counting and the FFT technique. It may be downloaded freely and without restrictions from web site
http://www.ftgsoftware.com/
More......