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  Dose transfer standard detector for a lithography toolUSPTO Application #: 20070296948Title: Dose transfer standard detector for a lithography tool Abstract: A dose transfer standard detector measures radiation intensity and dose in a lithography tool. The lithography tool may be an Extreme Ultraviolet lithography (EUVL) tool. The dose transfer standard detector may transmit intensity and dose data to a computer, which analyzes the data. Based on the analyzed data, the lithography tool may be calibrated. (end of abstract) Agent: Fish & Richardson, PC - Minneapolis, MN, US Inventor: Michael Goldstein USPTO Applicaton #: 20070296948 - Class: 355069000 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20070296948. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation application of and claims priority under 35 U.S.C. .sctn.120 to U.S. application Ser. No. 10/661,971, filed on Sep. 11, 2003. BACKGROUND [0002] A microchip manufacturing process may deposit various material layers on a wafer and form a photosensitive film or photoresist on one or more deposited-layers. A lithography tool may transmit light through transmissive optics or reflect light from reflective optics to a reticle or patterned mask. Light from the reticle transfers a patterned image onto the photoresist. Portions of the photoresist which are exposed to light may be removed. Portions of the wafer which are not protected by the remaining photoresist may be etched to form transistor features. [0003] The semiconductor industry may continue to reduce the size of transistor features to increase transistor density and improve transistor performance. This reduction in transistor feature size has driven a reduction in the wavelength of light used in lithography tools to define smaller transistor features on a photoresist. DESCRIPTION OF DRAWINGS [0004] FIG. 1 illustrates an example of a lithography tool, such as an Extreme Ultraviolet lithography (EUVL) tool. [0005] FIG. 2 illustrates a dose transfer standard detector structure which may be used in the lithography tool of FIG. 1. [0006] FIG. 3 illustrates the dose transfer standard detector structure of FIG. 2, two lithography tools and a computer. [0007] FIG. 4 shows a flow chart of using the dose transfer standard detector of FIG. 2. [0008] FIG. 5 illustrates an alternative embodiment of the dose transfer standard detector structure of FIG. 2. DETAILED DESCRIPTION [0009] Extreme Ultraviolet lithography (EUVL) may use a radiation wavelength of approximately 11-15 nanometers (nm). An EUV lithography tool may print a pattern on a photoresist with dimensions which are smaller than dimensions achieved by other lithography tools. An EUV lithography tool may also be called a "lithographic exposure system," an "EUV scanner" or an "EUV stepper." [0010] FIG. 1 illustrates an example of a lithography tool 100, such as an Extreme Ultraviolet lithography (EUVL) tool. The lithography tool 100 may include a laser 102, an electric discharge or laser produced plasma source 104, condenser optics 106, a reflective reticle 107 with a pattern, and reflective reduction optics 108. The reticle 107 may be used to form a patterned image on an object 110, such as a silicon wafer with a photoresist layer. [0011] "Intensity" (milliWatts/cm.sup.2) refers to an amount of radiation incident upon the object 110 in the lithography tool 100. "Dose" (milliJoules/cm.sup.2) refers to an amount of energy absorbed by the object 110 in the lithography tool 100. A user may set radiation intensity and dose for a lithography tool according to a standard reference. The standard reference may be based on values provided by the National Institute of Standards & Technology (NIST). The intensity and dose may vary slightly from lithography tool to lithography tool even though the lithography tools have the same settings. Intensity and dose may also change ("drift") after a lithography tool is shipped or after repeated used. [0012] It may be desirable to measure and calibrate the intensity and dose of a lithography tool. It may be desirable to compare and match the intensity and dose of two or more lithography tools. [0013] It may be difficult to access a wafer stage of a conventional lithography tool to install hardware to measure radiation intensity and dose. A lithography tool may have a vacuum or non-vacuum wafer stage. For a lithography tool with a non-vacuum wafer stage, a person may enter the lithography tool and manually connect radiation detection hardware to the wafer stage. [0014] For a lithography tool with a wafer stage in a vacuum, such as an EUV lithography tool, a person may have to break the vacuum to install radiation detection hardware to the wafer stage. Alternatively, a robot may be inserted in an interlock chamber connected to the vacuum to insert radiation detection hardware to the wafer stage. [0015] The present application relates to a dose transfer (or dose transport) standard detector and techniques of using the same. The detector may address the challenges of moving a dose detector between two or more lithography tools. The detector may be easily loaded and unloaded on a wafer stage of a lithography tool, such as an extreme ultraviolet lithography (EUVL) tool. The detector may accurately measure the intensity and/or dose of one or more-vacuum or non-vacuum lithography tools. The size, shape and components of the detector may automate loading of the detector, alignment of the detector, and collection of intensity and dose data. A computer may compare data from the detector with a reference value. [0016] FIG. 2 illustrates a dose transfer standard detector structure 200, which may be used in the lithography tool 100 of FIG. 1. Lithography tools may handle the dose transfer standard detector structure 200 as any other wafer. The detector structure 200 may include a wafer 201 fabricated with an array of detectors 206, one or more amplifiers 202, a processor 203, a wireless transmitter 204, a power source 207 and alignment marks 205. [0017] The processor 203 in FIG. 2 may be a digital signal processor available from Intel Corporation. The power source 207 in FIG. 2 may be capacitive, electrolytic, photovoltaic or some other type of power source. The alignment marks 205 allow the wafer 201 to be aligned on a wafer stage of the lithography tool 100. [0018] The detectors 206 in FIG. 2 may be adapted to detect radiation intensity (milliWatts/cm.sup.2) incident upon the wafer 201 and/or dose (milliJoules/cm.sup.2) when the wafer 201 is in the lithography tool 100. The detectors 206 may include photodiodes. For example, the detectors 206 may include a silicon photodiode. The detectors 206 may detect extreme ultraviolet (EUV) radiation and other types of radiation. An array of detectors 206 may be used since intensity and/or dose may vary (e.g., 0.5%) over multiple detectors. An average intensity and/or dose over multiple detectors may be calculated in an embodiment. [0019] The temperature of the wafer stage inside the lithography tool 100 may be carefully controlled such that the detectors 206, amplifiers 202, processor 203, wireless transmitter 204, and power source 207 on the wafer 201 do not experience a substantial temperature change. The array of detectors 206 may be the only components on the wafer 201 exposed to radiation in the lithography tool 100 in an embodiment. [0020] FIG. 3 illustrates the dose transfer standard detector structure 200 of FIG. 2 being used with first and second lithography tools 302A, 302B and a computer 304. The lithography tools 302A, 302B may be similar to the lithography tool 100 of FIG. 1. Continue reading... Full patent description for Dose transfer standard detector for a lithography tool Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Dose transfer standard detector for a lithography tool patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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