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Integrated metrology chamber for transparent substratesRelated Patent Categories: Semiconductor Device Manufacturing: Process, With Measuring Or Testing, Electrical Characteristic SensedIntegrated metrology chamber for transparent substrates description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060154388, Integrated metrology chamber for transparent substrates. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to the fabrication of photomasks useful in the manufacture of integrated circuits. [0003] 2. Background of the Related Art [0004] Photolithography techniques use light patterns and photoresist materials deposited on a substrate surface to develop precise patterns on the substrate surface prior to the etching process. In conventional photolithographic processes, a photoresist is applied on the layer to be etched, and the features to be etched in the layer, such as contacts, vias, or interconnects, are defined by exposing the photoresist to a pattern of light through a photolithographic photomask which corresponds to the desired configuration of features. A light source emitting ultraviolet (UV) light, for example, may be used to expose the photoresist to alter the composition of the photoresist. Generally, the exposed photoresist material is removed by a chemical process to expose the underlying substrate material. The exposed underlying substrate material is then etched to form the features in the substrate surface while the retained photoresist material remains as a protective coating for the unexposed underlying substrate material. Since photomasks are used repeatedly to create device patterns, quality control of photomask manufacturing is very important. [0005] Photolithographic photomasks, or reticles, include binary (or conventional) photomasks and phase shift masks (PSM), which could be used in sub 0.13 .mu.m technology. Binary (or conventional) masks typically include a substrate made of an optically transparent silicon based material, such as quartz (i.e., silicon dioxide, SiO.sub.2), having an opaque light-shielding layer of metal, such as chromium, on the surface of the substrate. Phase shift masks improve the resolution of the aerial image by phase shifting. The principle of phase shift mask is described in P. 230-234 of Plummer, Deal and Griffin, "Silicon VLSI Technology Fundamentals, Practice and Modeling", 2000 by Prentice Hall, Inc. Phase shift masks could be either attenuated phase shift or alternate phase shift mask. An attenuated phase shift mask typically includes a substrate made of an optically transparent silicon based material, such as quartz, having a translucent layer of material, such as molybdenum silicide (MoSi) or molybdenum silicon oxynitride (MoSiON), on top. When the photolithographic light, e.g. at 248 nm wavelength, shines through the patterned mask surface covered by the translucent layer, the transmission (e.g. 6% at 248 nm wavelength) and the thickness of the translucent layer create a phase shift, e.g., 180.degree., compared to the photolithographic light that shines through the patterned mask surface not covered by the translucent layer. An alternate phase shift mask typically includes a substrate made of an optically transparent silicon based material, such as quartz, which is etched to a certain depth to create a phase shift with the un-etched transparent substrate when the photolithographic light shines through the patterned mask. It also has a chrome layer with the same pattern as the quartz. There is another type of phase shift mask, the Chromeless Phase Lithography (CPL) Mask, which has the chrome layer removed. [0006] Photomasks allow light to pass therethrough in a precise pattern onto the substrate surface. The metal layer on the photomask substrate is patterned to correspond to the features to be transferred to the substrate. The patterns on the photomask could be 1.times., 2.times. or 4.times. the size of patterns that will be patterned on the wafer substrate. Typically, a photolithographic stepper reduces the image of the photomask by 4.times. and prints the pattern on the photoresist covering the wafer surface. Conventional photomasks are fabricated by first depositing one to two thin layers of metal, which could either be opaque or translucent depending on the types of masks being formed, on a substrate comprising an optically transparent silicon based material, such as quartz, and depositing a photoresist layer on substrate. The photomask is then patterned using conventional laser or electron beam patterning equipment to define the critical dimensions in the photoresist. The top metal layer, typically opaque, is then etched to remove the metal material not protected by the patterned photoresist, thereby exposing the underlying silicon based material. For a binary mask, the photomask is formed after the metal etching step. While for attenuate and alternate phase shift masks, additional photoresist patterning and etching of transparent substrate or translucent metal layer are needed to form the photomask. [0007] Since photomasks are used repeatedly to create device patterns, the accuracy and tight distribution of the critical dimensions, and the phase shift angle and its uniformity across the substrate are key requirements for binary and phase shift photomasks. For alternate phase shift mask, the phase angle is affected by the depth of the transparent material, such as quartz. Since precise control of the phase shift is very important, the etching of the transparent material, such as quartz, is often accomplished after multiple etching processes and multiple etch depth measurements to ensure phase shift of the mask is within control limit. If the etch depth measurement is performed in a system not integrated with the etching system, process cycle time could be very long and the approach could increase the total defect counts. [0008] Therefore, there remains a need in the art for an integrated metrology tool to measure etch depth (or phase shift angle) of photomask in a semiconductor photomask processing system. SUMMARY OF THE INVENTION [0009] The embodiments of the invention relates to a method and apparatus for measuring the etch depth between etching for an alternate phase shift photomask in a semiconductor photomask processing system. In one embodiment, an apparatus for measuring the etch depth of a substrate in an etch processing system comprises a measurement cell coupled to a mainframe of the etch processing system, and an etch depth measurement tool coupled to the bottom of the measurement cell, wherein an opening at the bottom of the measurement cell allows light beams to pass between the etch depth measurement tool and the substrate. [0010] In another embodiment, an apparatus for measuring the etch depth of a substrate in an etch processing system comprises a measurement cell coupled to a mainframe of the etch processing system, an etch depth measurement tool coupled to the bottom of the measurement cell, wherein an opening at the bottom of the measurement cell allows light beams to pass between the etch depth measurement tool and the substrate, and a substrate transfer robot placed in the mainframe to transfer substrate to the measurement cell, wherein the substrate transfer robot having a robot blade to hold a substrate and the robot blade having an opening to allow light beam to be shined on the substrate backside. [0011] In another embodiment, a method of preparing an alternate phase shift mask comprises a) placing a substrate in an etch processing chamber, wherein the substrate is made of an optically transparent material and has a first patterned opaque layer and a second patterned photoresist layer on the optically transparent material, b) etching the quartz to a first etch depth, c) transferring the substrate to a measurement cell coupled to a substrate transfer chamber, d) measuring the etch depth from the substrate backside by a etch depth measurement tool coupled to the bottom of the measurement cell to determine the etch time of next etch, e) placing the substrate back to the etch processing chamber, f) etching for the etch time determined by the etch depth measurement, g) transferring the substrate to the measurement cell, h) measuring the etch depth from the substrate backside by a etch depth measurement tool coupled to the bottom of the measurement cell to determine the etch time of next etch, and i) repeating "e" to "h" until a targeted etch depth has been reached. [0012] In another embodiment, an apparatus for measuring the etch depth of a substrate in an etch processing system comprises a measurement cell coupled to a mainframe of the etch processing system, n etch depth measurement tool coupled to the bottom of the measurement cell, wherein an opening at the bottom of the measurement cell that allows light beams to pass between the etch depth measurement tool and the substrate, a CD measurement tool coupled to the top of the measurement cell, wherein an opening at the top of the measurement cell allows light beams to pass between the CD measurement tool and the substrate, and a substrate transfer robot placed in the mainframe to transfer the substrate to the measurement cell, wherein the substrate transfer robot having a robot blade to hold the substrate and the robot blade having an opening to allow light beam to be shined on the substrate. BRIEF DESCRIPTION OF THE DRAWINGS [0013] So that the manner in which the above recited aspects of the invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. [0014] It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. [0015] FIGS. 1A-1F are cross-sectional views showing an etching sequence for processing an alternate phase shift photomask. [0016] FIG. 2 is a block diagram of key components of an integrated etch system. [0017] FIG. 3 is a diagram of one embodiment of an integrated etch system. [0018] FIG. 4 is a schematic diagram showing a substrate, a measurement tool, and the impeding and reflected light beams between the substrate and the measurement tool. [0019] FIG. 5A shows a schematic drawing of the end of the robot arm with a robot blade. [0020] FIG. 5B shows a schematic drawing of a measurement cell and an etch depth metrology tool. [0021] FIG. 5C shows a schematic drawing of a measurement cell with an etch depth measurement tool and a CD measurement tool. Continue reading about Integrated metrology chamber for transparent substrates... Full patent description for Integrated metrology chamber for transparent substrates Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Integrated metrology chamber for transparent substrates 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. Start now! - Receive info on patent apps like Integrated metrology chamber for transparent substrates or other areas of interest. ### Previous Patent Application: Method for calibration of a photodiode, semiconductor chip and operating method Next Patent Application: Light emitting diode with conducting metal substrate Industry Class: Semiconductor device manufacturing: process ### FreshPatents.com Support Thank you for viewing the Integrated metrology chamber for transparent substrates patent info. IP-related news and info Results in 0.20579 seconds Other interesting Feshpatents.com categories: Qualcomm , Schering-Plough , Schlumberger , Seagate , Siemens , Texas Instruments , 174 |
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