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Patent Issued for Substrate Carrying Mechanism, Substrate Carrying Method and Recording Medium Storing Program Including Set of Instructions to Be...

July 30, 2014



Patent Issued for Substrate Carrying Mechanism, Substrate Carrying Method and Recording Medium Storing Program Including Set of Instructions to Be Executed to Accomplish the Substrate Carrying Method

By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Hayashi, Tokutarou (Koshi, JP); Sakaguchi, Kiminari (Koshi, JP), filed on August 19, 2011, was published online on July 15, 2014.

The patent's assignee for patent number 8781787 is Tokyo Electron Limited (Minato-Ku, JP).

News editors obtained the following quote from the background information supplied by the inventors: "The present embodiment relates to a substrate carrying mechanism for carrying a substrate, a substrate carrying method, and a recording medium storing a program including a set of instructions to be executed to accomplish the substrate carrying method.

"A semiconductor device fabricating system for fabricating semiconductor devices or LCD panels (liquid crystal display panels) is provided with processing modules that process substrates (hereinafter, referred to also as 'wafers'). A substrate carrying mechanism carries substrates sequentially to the processing modules to subject the substrates to predetermined processes. The substrate carrying mechanism has, for example, a base, and a substrate holding fork capable of being advanced and being retracted along the base, of turning about a vertical axis and of moving vertically.

"Substrate carrying mechanisms mentioned in, for example, Patent documents 1 and 2 are provided with sensors for determining whether or not a substrate received from the processing module is held at a correct position on the holding fork.

"A semiconductor device fabricating system disclosed in Patent document 1 is provided with a substrate carrying mechanism including a carrying robot having an arm, i.e., holding fork, for holding a substrate. This semiconductor device fabricating system determines a positional error of a substrate in each of a plurality of units of the semiconductor device fabricating system from the position of the substrate on the arm (holding fork). The semiconductor device fabricating system is provided with correcting means for correcting the positional error of the substrate by adjusting a carrying distance for which the substrate is carried between the units. The positional error of the substrate is determined by measuring positions of a plurality of parts of the edge of the substrate.

"The substrate carrying mechanism disclosed in Patent document 2 has a carrying arm unit, a pick-up unit (holding fork), a position measuring unit for measuring the position of a substrate, a center-position calculating unit, a displacement calculating unit, and an arm control unit. The position measuring unit mentioned in Patent document 2 is mounted on the pick-up unit (holding fork) to measure the position of a substrate held by the pick-up unit. The center-position calculating unit calculates the position of the center of the substrate by using data provided by the position measuring unit. The displacement calculating unit calculates a positional error of the center of the substrate with respect to a predetermined reference position. The arm control unit controls the movement of the carrying arm unit such that the positional error of the center of the substrate is corrected while the substrate held by the pick-up unit (holding fork) is being carried to a desired position."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "The following problems lie in those substrate carrying mechanisms and substrate carrying methods mentioned in Patent documents 1 and 2.

"The substrate carrying, mechanism disclosed in Patent document 1 is provided with only two sensors. Therefore, a two-dimensional positional error of a wafer in a horizontal plane cannot be accurately measured. The substrate carrying mechanism disclosed in Patent document 2 is provided with three position measuring units and hence a two-dimensional positional error of a wafer in a horizontal plane can be measured.

"Some semiconductor substrate, namely, wafer, is provided with a notch to be used for positioning the wafer in its edge. The substrate carrying mechanism disclosed in Patent document 2 determines the position of the edge of a wafer by data provided by the three position measuring units. When one of the position measuring units measures the position of a part of the notch, the part of the notch is understood to be a part of the edge not provided with the notch. Therefore, if one of the position measuring unit measures the position of a part of the notch, a positional error of the wafer cannot be accurately determined.

"A known holding fork is provided with a guide structure having a guide wall having a downward tapered inner surface that surrounds a wafer to position a wafer at a correct horizontal position on the holding fork. A wafer placed on the holding fork is guided to a predetermined position on the holding fork by the guide structure. When a wafer coated with a coating film, such as a resist film, drops to the predetermined position on the holding fork, there is the possibility that coating film coating the edge of the wafer is abraded by the guide wall and particles are produced.

"In some cases, a holding fork that positions a wafer at a horizontal position by holding the wafer by using, for example, vacuum attraction instead of using the guide structure. Since the holding fork that holds a wafer by vacuum attraction is not provided with the guide structure, the wafer is liable to be dislocated in a horizontal plane. There is the possibility that a trouble is caused in the holding fork or the wafer by some cause and the position measuring units can operate abnormally under such a condition.

"The present embodiment has been made in consideration of such problems and it is therefore an object of the present embodiment to provide a substrate carrying mechanism and a substrate carrying method capable of accurately measuring a positional error of a substrate provided with a notch in its edge while the substrate held by a folding fork is being carried, of readily correcting the positional error of the displaced substrate, and of finding and correcting the state of the holding fork and the state of the substrate or position measuring units simultaneously.

"The present embodiment is characterized by the following means for solving the foregoing problems.

"A substrate carrying mechanism in a first aspect of the present embodiment includes: a base; a substrate holding member placed on the base and capable of holding a substrate and of being advanced and retracted relative to the base; four or more detecting units respectively for detecting different parts of the edge of a substrate held by the substrate holding member when the substrate holding member holding the substrate is retracted; and a controller that decides whether or not a notch formed in the edge of the substrate has been detected by one of the detecting units on the basis of measurements measured by the four or more detecting units and corrects an error in a transfer position where the substrate is to be transferred to a succeeding processing unit on the basis of measurements measured by the detecting units excluding the one detecting unit that detected the notch of the substrate.

"A substrate carrying mechanism in a second aspect of the present embodiment includes: a base; a substrate holding member capable of holding a substrate and of being advanced and retracted relative to the base; three detecting units that detect different parts of the edge of a substrate held by the substrate holding member when the substrate holding member holding the substrate is retracted; and a controller that decides whether or not a part of a notch formed in the edge of a substrate received from a processing unit has been detected by one of the detecting units on the basis of measurements measured by the three detecting units, moves the substrate holding member relative to the detecting units when it is decided that one of the detecting units has detected a part of the notch such that no part of the notch will be detected by any one of the detecting units, makes the detecting units detect parts of the edge of the substrate after the substrate holding member has been moved relative to the detecting units, and determines a transfer position where the substrate is to be transferred to a succeeding processing unit on the basis of measurements measured by the detecting units after the substrate holding member has been moved relative to the detecting units.

"A substrate carrying method in a third aspect of the present embodiment, to be carried out by a substrate carrying mechanism including a base, a substrate holding member capable of holding a substrate, placed on the base and capable of being advanced and retracted relative to the base, and four or more detecting units for detecting different parts of the edge of a substrate held by the substrate holding member when the substrate holding member holding a substrate received from a processing unit is retracted, includes the steps of: deciding whether or not a part of a notch formed in the edge of a substrate received from a processing unit has been detected by one of the detecting units on the basis of measurements measured by the detecting units; and determining, if a part of the notch formed in the edge of the substrate received from the processing unit has been detected by one of the detecting units, a transfer position where the substrate is to be transferred to a succeeding processing unit on the basis of the measurements measured by the detecting units excluding the one detecting unit that has detected the part of the notch of the substrate.

"A substrate carrying method in a third aspect of the present embodiment, to be carried out by a substrate carrying mechanism including a base, a substrate holding member capable of holding a substrate and of being advanced and retracted relative to the base, and three detecting units that detect different parts of the edge of a substrate held by the substrate holding member when the substrate holding member holding the substrate is retracted, includes the steps of: deciding whether or not a part of a notch formed in the edge of a substrate received from a processing unit has been detected by one of the detecting units on the basis of measurements measured by the three detecting units, moving the substrate holding member relative to the detecting units such that no part of the notch will be detected by any one of the detecting units when it is decided that a part of the notch has been detected by one of the detecting units; making the detecting units remeasure positions of parts of the edge of the substrate after the substrate holding member has been moved relative to the detecting units; and determining a transfer position where the substrate is to be transferred to a succeeding processing unit on the basis of measurements remeasured by the detecting units after the substrate holding member has been moved relative to the detecting units.

"The substrate carrying mechanism and the substrate carrying method according to the present embodiment can accurately measure a displacement of a substrate having a notch formed in its edge from the reference position when the substrate is held and carried by the substrate holding member, can readily correct a positional error of the substrate, and can find and correct the state of the substrate holding member and the state of the substrate or the detecting units."

For additional information on this patent, see: Hayashi, Tokutarou; Sakaguchi, Kiminari. Substrate Carrying Mechanism, Substrate Carrying Method and Recording Medium Storing Program Including Set of Instructions to Be Executed to Accomplish the Substrate Carrying Method. U.S. Patent Number 8781787, filed August 19, 2011, and published online on July 15, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8781787.PN.&OS=PN/8781787RS=PN/8781787

Keywords for this news article include: Electronics, Semiconductor, Tokyo Electron Limited.

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Source: Electronics Newsweekly


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