Sol-Gel Gateway Home page

 


 

 

 

  Active TopicsActive Topics  Display List of Forum MembersMemberlist  Search The ForumSearch  HelpHelp
  RegisterRegister  LoginLogin
Characterization Techniques
 Sol-Gel Gateway Forum>Sol-Gel Forum>Characterization Techniques
Message Icon Topic: THICKNESS MEASUREMENTS Post Reply Post New Topic
Author Message
kutty
Newbie
Newbie


Joined: 26 June 2006
Location: India
Online Status: Offline
Posts: 11
Quote kutty Replybullet Topic: THICKNESS MEASUREMENTS
    Posted: 06 July 2006 at 7:09am

   hello guys

                     i am scholor of physics.i am doing in the field of sol-gel spin coating method .my question is ,what are the possible methods are available to measure the thickness of  the film .if u have optical method  to measuring the thickness of the film,please give the all steps.or any simplest method , if you have send the notes.currently i am not having any equipments to measure the thickness of the film..please give the datails.

 

      i am using silicon substrate,not glass.

 guys i am expect your anser.

 thanking you.

s.r.krishnamoorthy
IP IP Logged
Nano
Groupie
Groupie


Joined: 29 May 2006
Location: United States
Online Status: Offline
Posts: 87
Quote Nano Replybullet Posted: 26 July 2006 at 5:30pm
You can use Profilometry. It is for thin film. The instrument will have instructions and easy to operate.

Also you can check the cross-section of your film under SEM.





IP IP Logged
kutty
Newbie
Newbie


Joined: 26 June 2006
Location: India
Online Status: Offline
Posts: 11
Quote kutty Replybullet Posted: 27 July 2006 at 6:50am

  thank u very much.i never forget ur kindful helf sir.

    sir further more i need a one helf from u sir.i want  a ASTM  xrd,ftir pattern for Lead Zirconium Titanate (PZT).I f u have pls send me sir.becouise i am doing rural area sir .pls send me sir.i never forget u sir.

      thanking u sir.

 my email id : krishpdf@yahoo.co.in 

 

s.r.krishnamoorthy
IP IP Logged
Zaara
Newbie
Newbie
Avatar

Joined: 27 July 2006
Location: United Kingdom
Online Status: Offline
Posts: 3
Quote Zaara Replybullet Posted: 27 July 2006 at 7:05am

Hello,

Anyboby have the information of UV glue thickness versus spin speed? For example the glue NOA81?

 

Ara
IP IP Logged
sagebob
Senior Member
Senior Member


Joined: 06 May 2005
Location: United States
Online Status: Offline
Posts: 193
Quote sagebob Replybullet Posted: 19 August 2006 at 11:16am

Howdy Kutty,

 

An optical measurement of thin films is possible and fairly easy.  The optical thickness of the films has to be within the wavelength range or your spectrophotometer.

IP IP Logged
sagebob
Senior Member
Senior Member


Joined: 06 May 2005
Location: United States
Online Status: Offline
Posts: 193
Quote sagebob Replybullet Posted: 19 August 2006 at 11:51am

howdy Kutty,

A continuation of the previous replay.

The theory of reflection of a transparent film on a bulk substate should be available from a physics or optics textbook.  I will approach this from a practical point of view.  What we need to apply here is that at different wavelengths, there is a series of constructive and destructive interference effects within the film.  Constructive interference effects give wavelenghts of maximum reflection and destructuve effects give reflections of minimum reflection.

Let us take a TiO2 film on glass as an example.  A film has a physical thickness (d), quarterwave optical thickness (4nd), and refractive index .  Refractive index is made up of a real (n) and complex component (k).  For a thin, non-absorbing film, we will let the complex component (k) equal zero.  For TiO2 this is about true and let us say the real component (n) equals 2.0 (a dimensionless number).

If the TiO2 film has a physical thickness of 100nm (1000Angstrom) we can calculate that the quaterwave optical thickness (QWOT) is 4nd or (4)(2.0)(100nm) which equals 800nm.  This is just in the near IR.  

As you made a wavelength scan from say 1000nm to 200nm on a spectrophotometer, you would see a maximum in reflection at 800nm. This is the QWOT where constructive interference takes place.  As you follow the curve down from 800nm, you would see a minimum in reflection at 400nm (800/2).  This is destructive interference.  As you continue down, you will see another maximum reflection point at 267nm (800/3).  Basically all the odd quarter waves (i.e. QWOT, 3QWOT, 5QWOT) are maximum reflection points and all the even quarterwaves (2QWOT, 4QWOT) are minimum reflections.

If the layer is very thin, no maximum in reflection is seen.  Beyond the first QWOT, the film reflection slowly decreases to zero as the wavelength increases.  If the layer is very thick, the first QWOT may be in the infared (IR) and not easily measureable due to lack of instrument range or absorption in the coating.

You can calculate the film thickness in this case by determining the ratio between the maximums and minimums and determining which QWOT's you are seeing.

For example, say the TiO2 film is 400nm thick.  The first QWOt will be at 4nd= (4)(2.0)(400nm) = 3200nm.  You can calculate that the 2QWOT is at 1600nm, the 3QWOT is at 1067nm, the 4QWOT is at 800nm, the 5QWOT is at 640nm, the 6QWOT is at 533nm, etc.  Other effects will prevent this from being as simple as I show here.  The largest effect is from dispersion.  This is the property where a material's refractive index changes with wavelength.  TiO2 has a high dispersion and SiO2 has almost none.  As the refractive index changes, you can see that it changes the result of the calculation.  however, the calculation works well for most materials in the visible and near IR range.  Many materials have very high dispersion in the UV.  They also often become very absorbing in the UV.  This is where the complex refractive index (k) increases rapidly from being close to zero in the visible or IR.

Most chemistry labs or water analysis labs have a spectrophotometer that can be adapted to measuring reflectance.  A beam bending mirror attachment may need to be made.  For non-absorbing films, it is often easier to put them on a transparent substrate and then directly measure transmission.  i.e. Glass for visible, silicon for IR.

 

hope this helps a little - have fun - bob

IP IP Logged
pravin
Newbie
Newbie
Avatar

Joined: 12 November 2006
Location: India
Online Status: Offline
Posts: 3
Quote pravin Replybullet Posted: 12 November 2006 at 3:19am
Hello!
    I am a new user.
I need some information about calculating the optical constants of thin film using transmission and absorption spectra.
Any help will be appreciated.
    Pravin.
Have a nice time!!
IP IP Logged
K. K. Saini
Newbie
Newbie


Joined: 19 July 2005
Location: India
Online Status: Offline
Posts: 6
Quote K. K. Saini Replybullet Posted: 21 December 2006 at 4:31am
Following three research articles may help you the desired optical constants:
1. J. C. Manifacier, J. Gasiot and J. P. Fillard; J. Phys E 1976, Vol-9, pp1002.
2. D. Davazoglou; Appl. Phys. Lett., Vol 70 No. 2, Jan 1977.
3. R. Swanepoel; J. Phys. E. Sci. Instrum. Vol 16, 1983.
IP IP Logged
DEFRANOUX
Newbie
Newbie
Avatar

Joined: 02 October 2006
Location: France
Online Status: Offline
Posts: 6
Quote DEFRANOUX Replybullet Posted: 21 December 2006 at 5:41am

I would suggest Spectroscopic Ellipsometry to measure the opticals constants of a film. It does not need any Krames Kronig assumption. It also determine the thickness at the same time.
In a previous post, I also mention that Ellipsometry can also determine the porosity and the pore size distribution of a porous thin film.
Christophe.defranoux@sopra-sa.com
IP IP Logged
Tamizi
Newbie
Newbie
Avatar

Joined: 11 April 2006
Location: Malaysia
Online Status: Offline
Posts: 8
Quote Tamizi Replybullet Posted: 28 August 2007 at 4:10am
I just read sagebob's explaination on d & n measurement. Thanks. Which somehow explain why thicker films are hardly measured.
IP IP Logged
Post Reply Post New Topic
Printable version Printable version

Forum Jump
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum




This page was generated in 0.109 seconds.
Privacy statement Copyright 2000-2017, Solgel.com.