Radiant energy – Inspection of solids or liquids by charged particles
Reexamination Certificate
1999-05-13
2001-10-16
Berman, Jack (Department: 2881)
Radiant energy
Inspection of solids or liquids by charged particles
Reexamination Certificate
active
06303930
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an observation position and forming position determining method in an observation/forming apparatus using a charged particle apparatus such as a focused ion beam apparatus FIB (Focused Ion Beam) scanning electron microscope (SEM), and to an apparatus therefor.
The conventional FIB/SEM observation position alignment utilizing an optical microscope image includes two methods. The first is a method of comparing two images to align them on a coordinate and performing marking with an FIB to enable location of a mark position by use of an optical microscope, thereby confirming the position. The second is a method for aligning positions of an optical microscope image and an FIB and SEM image from a coordinate relationship. For example, such a method is disclosed in JP-A-9-097585.
There is a problem in that the above described technology in damage is caused to a sample due to FIB/SEM and labor and time is required in forming position specifying time and also in detailed position specifying accuracy to conduct section observation.
For example, in a semiconductor manufacturing process, highly integrated semiconductor manufacture has recently been obtained in multi-layer structures using planar layers as interconnect line width has been reduced. On the semiconductor surface a transparent passivation film is formed. Due to this, because the passivation film does not transmit electrons or ions, it has become impossible to observe a target position inside the planarized film after planarization. Accordingly, optical observation images are required to supplement positioning observation/forming position location for FIB/SEM use. However, the section forming of an interconnect of 1 micron or smaller requires observation/forming position alignment of 1 micron or less. However, there is a problem in that using only stage coordinate movement positioning an accuracy of 1 micron or smaller is difficult to easily achieve.
Also, there is a problem of occurrence of reference (contamination) on a sample encountered in long time or strong electron/ion beam observation.
It is an object of the present invention to provide an apparatus which is capable of improving observation/forming position positional accuracy using FIB/SEM and reducing sample damage by an electron/ion beam due to observation time shortening.
SUMMARY OF THE INVENTION
A coordinating optical type observing apparatus of the present invention sets a sample on a stage and moves it to a target position while observing at an external coordinate or continuous optical image.
A laser marking method of the present invention performs marking of a diameter of 10 microns or smaller by selecting a proper laser oscillation wavelength based on a sample nature by a laser optical system coaxially arranged with respect to an optical observing system on both sides of a target position to be observed and formed with an FIB or SEM.
Further, the coordinating optical type observing apparatus of the present invention can accumulate on a recording medium, together with a positional coordinate, an optical image at a position at which marking was made.
Also, the accumulated data is read from an external FIB/SEM, which can be used to search a target position.
Because the present invention searches for a target position by use of an optical image, there is no damage caused by irradiating a laser beam such as in FIB or SEM onto the sample. Further, because the material of a planarized film used in a semiconductor manufacturing process can transmit in the optical type observing apparatus, where a target position for observing/forming of FIB/SEM is under the planarized film, the position can be specified. Also, an optical type observing image can be distinguished in target position due to color, different from an image of an FIB/SEM.
Next, by performing marking of 10 microns or smaller on both sides of the target position, the target position of forming and observing for FIB/SEM can be specified with an accuracy of 1 micron or less.
Also, the present invention can accumulate in a recording medium laser-marked position information and an optical image and positional coordinate including the laser mark. This accumulated information can be supplied as observation/forming information for other observation/forming and semiconductor manufacturing apparatus performed by an FIB/SEM.
REFERENCES:
patent: 5028939 (1991-07-01), Hornbeck et al.
patent: 5715052 (1998-02-01), Fujino et al.
patent: 6081614 (2000-06-01), Yamada et al.
patent: 57-55947 (1955-09-01), None
patent: 9283073 (1997-10-01), None
Adams & Wilks
Berman Jack
Seiko Instruments Inc.
Smith II Johnnie L
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