Ellipsometer

Details Ellipsometer Ellipsometer

1992-10-23

1994-08-30

Rosenberger, Richard A.

Optics: measuring and testing

By polarized light examination

Of surface reflection

356382, G01B 1100

Patent

active

053432932

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION

The present invention refers to an ellipsometer used for in-situ measuring of the film thickness of films applied to or deposited on an object within an oven, comprising an analyzer unit, a beam deflection device, a paddle having the object arranged thereon, and a polarizer unit.
The present invention deals, in particular, with an ellipsometer, which is adapted to be used in the field of silicon semiconductor technology for controlling within conventional oxidation ovens, CVD (chemical vapour deposition) ovens or CVD reactors the grown oxidation film thickness or CVD film thickness on silicon wafers in situ.
Ellipsometers used for film thickness measurement have been known for decades with respect to their measurement principle as well as with respect to their structure, this being proved by the following technical publications:
Y. J. van der Meulen, N. C. Hien, "Design and operation of an automated, high temperature ellipsometer" J. Opt. Soc. Am. 64, 1974.
R. H. Muller, "Principles of Ellipsometry" Advances in Electrochemistry and Electrochemical Engineering, vol. 9, Wiley, N.Y. 1973.
It is also known to use ellipsometers for measuring the grown oxide film thickness on silicon wafers in oxidation ovens, as will be evident from the first-mentioned technical publication. In these cases, the geometry of the oxidation oven is normally adapted to the structure of the ellipsometer. In so doing, the heating cartridge of the oxidation oven is provided with beam passages, and this may cause disturbances within the temperature profile in the oxidation oven. Furthermore, a pipe connection to the quartz tube of the oxidation oven with beam passage windows is required, and this will cause tensions in the quartz tube. This pipe connection cannot be produced such that it is gastight so that an ingress of external air from the heating cartridge into the process tube may occur. Moreover, in the case of the known ellipsometer, it is necessary that the adjustment of said ellipsometer to the silicon wafer film thickness to be measured is carried out at a high temperature, without the opeator being able to observe the ray path. Taking into account the overall structure of the ellipsometer and of the oxidation oven, it will be evident that, by means of the known ellipsometer, a film thickness measurement can only be carried out at one single location on the semiconductor wafer. Furthermore, in practical operation, it turns out to be unacceptable that, in the case of the known ellipsometer, the polarizer unit and the analyzer unit are located on opposite sides of the heating cartridge of the oxidation oven in the socalled grey room.
An ellipsometer according to the generic clause, used for in-situ measurement of the film thickness of films applied to or deposited on semiconductor wafers within an oven, is known from EP-B1-102470. In the case of this known ellipsometer system, the analyzer unit and the polarizer unit are arranged such that the light beam emitted by the polarizer unit is parallel to the light beam received by the analyzer unit, said light beams extending parallel to the axis of symmetry of the quartz tube of the oxidation oven. The light beam emitted by the polarizer unit is deflected on the surface of a first silicon wafer, which is arranged approximately at an angle of 45.degree. to the longitudinal axis of the quartz tube, and falls on a second silicon wafer, which is arranged symmetrically to the first silicon wafer and by means of which the light beam is reflected towards the analyzer unit. It follows that this ellipsometer system can only be used for simultaneously measuring oxidation films deposited on two silicon wafers. Furthermore, it turned out that the measuring signal produced in the case of such an ellipsometer system is a temporally strongly fluctuating measuring signal so that, for reasons of measurement precision, this arrangement has not spread widely. In addition, this ellipsometer arrangement requires an adjustment of the polarizer unit and of the analyzer unit, when the oxidation

REFERENCES:
patent: 3060793 (1962-10-01), Wells
patent: 3737237 (1973-06-01), Zurasky

Affiliated with

Also associated with

Rating

Ellipsometer does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Ellipsometer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ellipsometer will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-33350