Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
2000-02-29
2002-01-08
Niebling, John F. (Department: 2812)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C250S370080, C250S336200, C250S368000
Reexamination Certificate
active
06337488
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a defect inspection apparatus and a defect inspection method suitable for inspection of scratches, dust, and other defects present in a pattern formed in films in a process of manufacture of a semiconductor device having for example a stacked film structure.
2. Description of the Related Art
Up to the present, inspection of scratches present in a pattern on a semiconductor wafer, dust adhering to the pattern, and other defects in the process of manufacture of a semiconductor device has been carried out by taking the image of the semiconductor wafer creating a contrast waveform from the two dimensional image and detecting the same.
FIG. 5
is a view schematically showing principal parts of an example of the configuration of a defect inspection apparatus for inspection of scratches present in a pattern on a semiconductor wafer, dust adhering to the pattern, and other defects.
The defect inspection apparatus shown in
FIG. 5
is configured so as to emit a beam of visible light from a lamp
101
via a lens
102
, a half mirror
103
, and an object lens
104
onto a semiconductor wafer W and to receive the beam of reflected light via the object lens
104
, the half mirror
103
, and an image-forming lens
105
at a camera
106
.
In the defect inspection apparatus having the above configuration, the beam of light reflected from the semiconductor wafer W passes through the object lens
104
, half mirror
103
, and image-forming lens
105
to be received at the camera
106
, a contrast waveform reflecting the surface shape of the semiconductor wafer W is created based on an intensity of the light received by the camera
106
, and the defect present in a pattern formed on the semiconductor wafer W is detected from this contrast waveform by the naked eye or the like.
FIG. 6A
is a sectional view in the process of manufacture of a semiconductor device having the stacked film structure as an object to be inspected by the defect inspection apparatus, while
FIG. 6B
is an example of the contrast waveform of the surface shape of the semiconductor device shown in
FIG. 6A
by the defect inspection apparatus.
In the structure of the semiconductor device shown in
FIG. 6A
, for example, a silicon oxide pattern SP is formed on the wafer W, and an aluminum interconnection pattern AP is formed on this silicon oxide pattern SP.
As will be understood from
FIGS. 6A and 6B
, the contrast waveform at a step difference between the resist pattern RP and the aluminum interconnection pattern AP has a different shape from the actual shape due to the coverage of the aluminum.
Summarizing the problem to be solved by the invention, the shape of the step difference present between the resist pattern RP and the aluminum interconnection pattern AP cannot be accurately determined from a region PA and a region Pr of the contrast waveform obtained by the defect inspection apparatus.
In the defect inspection apparatus, when there is a relatively deep and inclined step difference in the pattern like the inclined surfaces of the resist pattern RP and the aluminum interconnection pattern AP, there is a disadvantage that even if there is for example a scratch, adhesion of dust, or another defect in these inclined surfaces, it cannot be detected.
In the related art, when there is a relatively deep and inclined step as described above in the pattern stacked on the semiconductor wafer, for example a scanning electron microscope (SEM) has been used to conduct a sampling inspection from among a large number of semiconductor wafers.
In defect inspection using a scanning electron microscope, however, the number of the scanning electron microscopes which can be introduced is limited from the viewpoint of the plant and apparatus investment since scanning electron microscopes are high in cost. Further, the number of the semiconductor wafers inspected is limited since the throughput of the inspection is low.
Semiconductor wafers not inspected for defects are sent to the next step. These uninspected semiconductor wafers have become a cause of reduction of the yield of the product.
In the future, in the process of manufacture of a semiconductor device, along with the miniaturization of the circuit pattern of integrated circuits, employment of a stacked film structure of more layers for the semiconductor device cannot be avoided, so development of a defect inspection apparatus which can correctly inspect minute defects existing in a semiconductor wafer in the process of manufacture of a semiconductor device at a low cost and with a high throughput has become necessary.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a defect inspection apparatus and a defect inspection method capable of more reliably and quickly detecting defects existing in patterns formed in the stacked films formed on a wafer in for example a process of manufacture of a semiconductor device, more particularly capable of reliably and quickly detecting minute defects even if there are step differences and other unevenness at the surface of the wafer.
According to a first aspect of the present invention, there is provide a defect inspection apparatus for inspecting for a defect existing in a inspected surface, comprising a light source for emitting a beam of light of a predetermined frequency band, a light frequency changing means for receiving as its input the is beam of light emitted from the light source and outputting the related beam of light converted to a plurality of beams of inspection light having close frequencies different from each other and a beam of reference light beam, a light focusing means upon which the beams of inspection light output from the light frequency changing means are incident through an identical optical path and focusing the related beams of inspection light to the inspected surface to forming a plurality of different focal points corresponding to the beams of inspection light, a scanning means for scanning the focused beams of inspection light on the inspected surface, a superposing means for superposing the beam of the reflected light of the inspection light from the inspected surface and the beam of reference light to cause interference between the beams of reflected light and the beam of reference light, a light receiving means upon which the superposed light of the beams of reflected light and the beam of reference light is incident and detecting the intensity of the superposed light by confocal detection, and a contrast waveform generating means for generating contrast waveforms in the scanning direction at the focal positions in respect to the light intensity detected by the light receiving means and combining the contrast waveforms.
Preferably, the apparatus further comprises a defect detecting means for detecting defects of the pattern based on the contrast waveforms.
Preferably, the light receiving means has a light receiving element for receiving the superposed light and a pin hole plate provided in an incident light path of the superposed light to the light receiving element and having a small aperture and detecting the intensity of the superposed light by confocal detection.
Preferably, the light source selectively output a beam of visible laser light of a visible band and a beam of far-ultraviolet laser light of a far-ultraviolet band.
Preferably, the superposing means has beam splitters for reflecting the beam of reference light output from the light frequency changing means to the light receiving means, passing the beams of reflected light from the inspected surface striking it after following an identical optical path as that for the beams of inspection light, and exposing the same to the light receiving means.
Preferably, the light frequency shifting means has a plurality of acousto-optic modulating means for changing the frequency of the light emitted from the light source by supersonic waves of different frequencies from each other.
Preferably, the inspected surface comprises uneven surface.
Preferably
LandOfFree
Defect inspection apparatus and defect inspection method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Defect inspection apparatus and defect inspection method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Defect inspection apparatus and defect inspection method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2840632