Interferometric method and apparatus for measuring etch rate and fabricating devices
First Claim
1. A method for fabricating a device, comprising the steps of:
- etching a pattern into a substrate; and
monitoring said etching of said substrate by illuminating a region of said substrate with light and sensing a portion of the light reflected from said region, characterized in thatsaid region of said substrate is a region into which a portion of said pattern is being etched,said sensing step includes the step of detecting the intensity of a diffraction order of the light reflected from said region, andsaid method further comprises the step of terminating said etching based on the detected number of cycles of said intensity.
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Abstract
A method and apparatus for measuring etch depth during the etching of a device pattern into a nontransparent substrate, is disclosed. The method makes use of the finding that the device patterns etched into substrates produce diffraction patterns when illuminated. Thus, according to the method, a beam of light is directed onto a region of a substrate, into which region a portion of a device pattern is being etched. The light reflected from this region forms a diffraction pattern and, according to the inventive method, the intensity of a diffraction order is detected and recorded as a function of time during the etching procedure. The intensity of the diffraction order varies with time. The etch rate of the substrate is inversely proportional to the period of the oscillations in the recorded intensity-time curve.
82 Citations
14 Claims
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1. A method for fabricating a device, comprising the steps of:
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etching a pattern into a substrate; and monitoring said etching of said substrate by illuminating a region of said substrate with light and sensing a portion of the light reflected from said region, characterized in that said region of said substrate is a region into which a portion of said pattern is being etched, said sensing step includes the step of detecting the intensity of a diffraction order of the light reflected from said region, and said method further comprises the step of terminating said etching based on the detected number of cycles of said intensity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for measuring the etch depth of a substrate during a process in which a device pattern is etched into said substrate, comprising the steps of:
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illuminating a region of said substrate with light; and sensing a portion of the light reflected from said region, characterized in that said region of said substrate is a region into which a portion of said pattern is being etched, said sensing step includes the step of detecting the intensity of a diffraction order of the light reflected from said region, and said method further comprises the step of terminating said etching based on the detected number of cycles of said intensity. - View Dependent Claims (12, 13)
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14. Apparatus for measuring the etch rate of a substrate, during a process in which a device pattern is etched into said substrate, comprising:
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first means for illuminating a region of said substrate with light; and second means for sensing a portion of the light reflected from said region, characterized in that said first means is adapted for directing light onto a region of said substrate into which a portion of said pattern is being etched, said second means includes means for detecting the intensity of a diffraction order of the light reflected from said region, and said etch rate is inversely proportional to a period of the variation with time of said intensity.
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Specification