Infrared thermographic method and apparatus for etch process monitoring and control
First Claim
1. A method for detecting the presence and location of suspended plasma particulates in a plasma etch reactor, comprising the steps of:
- positioning a substrate in said plasma etch reactor;
creating a plasma in said plasma etch reactor for etching said substrate;
monitoring infrared emissions emanating from said gaseous plasma during etching of said substrate; and
detecting localized regions within said gaseous plasma which have infrared emission properties which differ from said gaseous plasma.
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Accused Products
Abstract
An infrared television camera (20) monitors the etching of a substrate (26) in-situ in an etch chamber (24). Temporal and spatial resolution of IR emissions is obtained by monitoring the top surface of the substrate (26) in two-dimensions throughout the course of the etching process. Anomalies in temperature detected on the top surface of the substrate (26) can indicate defects in the substrate (26) itself or in the operation of the etching apparatus. Process feedback control is achieved by adjusting various parameters of the etching apparatus (i.e., gas-pressure, flow pattern, magnetic field, coolant flow to electrode, or the like) to compensate for etching anomalies. Etch uniformity and etch endpoint monitoring is achieved by monitoring the IR emissions resulting from exothermic reaction of the film being etched. IR emissions decline at the end of an exothermic etch reaction. Particulate matter which might otherwise harm the substrate (26) can be identified in the gas-phase with a second IR television camera (34) which images the region above the substrate (26). Particulate matter appears as localized "hot spots" within the gas plasma, and the identification of particulate matter allows corrective measures to be taken.
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Citations
32 Claims
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1. A method for detecting the presence and location of suspended plasma particulates in a plasma etch reactor, comprising the steps of:
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positioning a substrate in said plasma etch reactor; creating a plasma in said plasma etch reactor for etching said substrate; monitoring infrared emissions emanating from said gaseous plasma during etching of said substrate; and detecting localized regions within said gaseous plasma which have infrared emission properties which differ from said gaseous plasma. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for detecting the presence and location of suspended plasma particulates in a plasma etch reactor, comprising:
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an infrared sensitive device positioned to image an area in said plasma etch reactor where gaseous plasma is generated for etching a substrate; means for determining an intensity of infrared radiation in said area imaged by said infrared sensitive device; means for allocating an intensity level for regions within at least two dimensions of said area imaged by said infrared sensitive device based on output from said means for determining; means for identifying a background level of intensity of said infrared radiation representative of said gaseous plasma in said area imaged by said infrared sensitive device; and means for identifying localized regions within said area imaged by said infrared sensitive device which have a higher level of intensity than said background level of intensity of said infrared radiation. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method for controlling plasma etching in a plasma etch reactor, comprising the steps of:
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providing a substrate in said plasma etch reactor having at least two layers of film where an etch reaction exothermicity of a first layer of film is detectably greater than for a second layer of film on said substrate; creating a plasma in said plasma etch reactor; monitoring infrared emissions emanating from said substrate during plasma etching of said substrate; detecting heating of said substrate caused by said etch reaction exothermicity of said first layer of film from said infrared emissions during plasma etching; adjusting conditions in said plasma etch reactor in response to detected heating of said substrate caused by said etch reaction exothermicity of said first layer of film. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. An apparatus for controlling plasma etching of a substrate in a plasma etch reactor wherein said substrate in said plasma etch reactor has at least two layers of film where an etch reaction exothermicity of a first layer of film is detectably greater than for a second layer of film, comprising:
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means for creating a plasma in said plasma etch reactor for etching said substrate; means for monitoring infrared emissions emanating from said substrate during plasma etching; means for detecting heating of said substrate caused by said etch reaction exothermicity of said first layer of film of said substrate from said infrared emissions occuring during plasma etching; and means for adjusting conditions in said plasma etch reactor in response to detected heating of said substrate caused by said etch reaction exothermicity of said first layer of film of said substrate. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 32)
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31. An apparatus as recited in claim 31 further comprising a means for determining when regions of said surface of said substrate have divergent exothermic heating.
Specification