JP2006302690A - Ion doping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion doping device preventing a short-circuit between components by flaking away of a metal film generated by sputtering of a Faraday cup. <P>SOLUTION: The ion doping device is equipped with a Faraday cup 11 measuring beam current, a suppression electrode 12 to suppress secondary electrons generated from the Faraday cup 11, an ion suppression electrode 13 to suppress ions from plasma excited by the ion beam, and a grounding chassis 14 covering the above. Irregularities made of faces with shorter diameters than each interval between adojoining components (distances A to G) of the Faraday cup 11, the suppression electrode 12, the ion suppression electrode 13 and the grounding chassis 14 are provided on a surface at least with metal films 17a to 17c formed out of surfaces of the suppression electrode 12, the ion suppression electrode 13 and the grounding chassis 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ion doping apparatus used for manufacturing a low-temperature polysilicon liquid crystal panel or the like, and more particularly to an ion doping apparatus that prevents a measurement error of a beam current.

  When a TFT is formed on a large substrate such as a low-temperature polysilicon liquid crystal, an ion doping apparatus is used for the implantation of impurities for the purpose of forming the source, drain, and LDD regions of the TFT and controlling the threshold value of the TFT.

  The ion doping apparatus includes a Faraday apparatus that takes in an ion beam and measures a beam current. This Faraday apparatus is mainly used for beam current adjustment of an ion beam. The Faraday device includes a Faraday cup for measuring beam current, a suppression electrode for suppressing secondary electrons generated from the Faraday cup, an ion suppression electrode for suppressing ions from plasma excited by the ion beam, And a grounding casing covering these.

The ion doping apparatus is also provided with an ion source that converts the element into plasma and extracts ions in the plasma as an ion beam. Patent Document 1 discloses an ion source that electrically insulates a plasma chamber body and a plasma slit and removes deposits deposited on the plasma slit by plasma sputtering by applying a sputtering voltage therebetween. It is disclosed.
JP-A-9-17366

  Patent Document 1 discloses removing the deposits deposited in the ion source, but does not describe the removal of deposits deposited in the Faraday device.

  Since the Faraday device having the above-described configuration generally uses a metal such as stainless steel that is easy to process, the Faraday cup is sputtered by the ion beam, and the suppression electrode, the ion suppression electrode, and the Faraday cup side of the ground casing are arranged. A metal film is deposited on the surface. When this metal film grows to a certain thickness, it peels off in a size of several mm to several cm due to temperature change. The metal film that has peeled off falls between the Faraday cup, the suppression electrode, the ion suppression electrode, and the ground casing that need to be electrically insulated from each other, and short-circuits these members. As a result, there is no original potential difference between the members, and an error occurs in the measurement of the beam current. Conventionally, the surface of each member has been blasted in order to suppress peeling of the metal film that causes this.

  However, when the blasting process is performed, the time until the generated metal film is peeled off becomes long, but in some cases, the metal film is peeled off and the members are short-circuited.

  An object of this invention is to provide the ion doping apparatus which prevented the short circuit between each member by the metal film produced | generated by the sputtering of the Faraday cup peeling off.

  In order to achieve the above object, an ion doping apparatus of the present invention includes a Faraday cup, a suppression electrode, an ion suppression electrode, at least a surface of a suppression electrode, an ion suppression electrode, and a housing on which a metal film is formed. And the convex part which consists of a surface of a shorter diameter than each member space | interval which a housing | casing adjoins is provided.

  The surface of the Faraday cup is sputtered by the ion beam, and the scattered metal is deposited as a sputtered film (metal film) on the surface of the suppression electrode, the ion suppression electrode, and the Faraday cup side of the ground casing. When this metal film grows to a certain thickness, it peels off due to temperature changes. In that case, according to said structure, the metal film which peels off peels in the shape of the surface which comprises a convex part.

  For example, the convex portion can be formed by making a plurality of intersecting groove portions into recesses or making a plurality of adjacent holes into recesses.

  According to the present invention, the size of the metal film that is peeled off is shorter than the interval between the suppression electrode, the ion suppression electrode, and the grounding case, and therefore, these members are deposited without short-circuiting. As a result, the original potential difference can be maintained between the members, and the beam current can be measured normally.

  The ion doping apparatus includes an ion source that converts elements into plasma and extracts ions in the plasma as an ion beam, and a Faraday apparatus that takes in the ion beam and measures a beam current.

  FIG. 1 is a schematic cross-sectional view of a Faraday device mounted on an ion doping apparatus. The Faraday device 10 includes a Faraday cup 11 for measuring a beam current, a suppression electrode 12 for suppressing secondary electrons generated from the Faraday cup 11, and ions for suppressing ions from plasma excited by an ion beam. A suppression electrode 13 and a ground casing 14 covering these electrodes are provided.

  The Faraday cup 11 has a cup shape for receiving an ion beam, and is disposed at the center lower portion in the ground casing 14 and is insulated from other members. The distance from the outer bottom surface of the Faraday cup 11 to the inner bottom surface of the ground casing 14 is a distance A.

  The suppression electrode 12 is disposed so as to cover the Faraday cup 11 and is insulated from other members. The lower end portion of the suppression electrode 12 is fixed to the inner bottom surface of the ground casing 14 via an insulator 15a. Further, the distance from the inner portion of the upper surface of the suppression electrode 12 to the upper end of the Faraday cup 11 is separated by a distance B, and the distance from the inner portion of the side surface of the suppression electrode 12 to the outer surface of the Faraday cup 11 is separated by a distance C. The distance D is separated from the most protruded portion of the side surface to the inner side surface of the ground casing 14.

  The ion suppression electrode 13 is disposed above the suppression electrode 12 and is insulated from other members. The distance from the bottom surface of the ion suppression electrode 13 to the top surface of the suppression electrode 12 is a distance E, the distance from the top surface of the ion suppression electrode 13 to the inner portion of the top surface of the ground housing 14 is a distance F, and the side end of the ion suppression electrode 13 To the inner surface of the ground casing 14 by a distance G.

  Openings 12 a, 13 a, and 14 a are formed in the suppression electrode 12, the ion suppression electrode 13, and the ground casing 14 above the Faraday cup 11, respectively. An ion beam extracted from an ion source (not shown) is received by the Faraday cup 11 through the openings 12a, 13a, and 14a.

  The Faraday cup 11, the suppression electrode 12, the ion suppression electrode 13, and the ground casing 14 are generally made of metal because they require electrical conductivity. For example, stainless steel that can be easily processed can be used.

  The Faraday cup 11, the suppression electrode 12, and the ion suppression electrode 13 are connected to an ammeter, a power source, and ground, respectively. A conducting wire 16 connecting them is provided through the ground casing 14. Insulators 15b to 15d are provided in the penetrating portion of the ground casing 14 in order to prevent the conductor 16 from being short-circuited with the ground casing 14.

  Concavities and convexities are formed on the inside portions of the upper surfaces of the suppression electrode 12, the ion suppression electrode 13, and the ground casing 14. 2 is a schematic plan view of an inner portion of the upper surface of the suppression electrode 12, and FIG. 3 is a cross-sectional view taken along line XX of FIG. The inner portions of the upper surfaces of the ion suppression electrode 13 and the ground casing 14 have the same structure.

  As shown in FIG. 2, a plurality of intersecting grooves 12 b are formed in the inner portion of the upper surface of the suppression electrode 12. These groove portions 12b are arranged in a grid at predetermined intervals. Thereby, the groove part 12b becomes a concave / convex concave part, and a part protruding in a square other than the groove part becomes a concave / convex convex part 12c. As shown in FIG. 3, the convex portion 12 c has a diagonal line with a length H. Further, the width of the groove portion 12b is shorter than one side of the convex portion 12c.

  And length H is shorter than each member space | interval (distance AG) where the Faraday cup 11, the suppression electrode 12, the ion suppression electrode 13, and the grounding housing | casing 14 adjoin.

  4 is a schematic plan view of an inner portion of the upper surface of another suppression electrode 12, and FIG. 5 is a cross-sectional view taken along line YY of FIG. The inner portions of the upper surfaces of the ion suppression electrode 13 and the ground casing 14 can also have the same structure.

  As shown in FIG. 4, a plurality of holes 12 d are formed in the inner portion of the upper surface of the suppression electrode 12 so as to slightly overlap. Thereby, the hole 12d becomes an uneven concave portion, and the protruding portion other than the hole becomes an uneven convex portion 12e. The convex portion 12e has a diagonal line with a length J as shown in FIG.

  And length J is shorter than each member space | interval (distance AG) to which the Faraday cup 11, the suppression electrode 12, the ion suppression electrode 13, and the grounding housing | casing 14 adjoin.

  As shown in FIG. 2 to FIG. 5, the unevenness formed on the surfaces of the suppression electrode 12, the ion suppression electrode 13, and the grounding housing 14 has a diameter of the surface that becomes the convex portion as a member interval (distance A to G The shape of the unevenness is not particularly limited.

  When the Faraday device 10 having such a configuration is used, the metal films 17a to 17c (see FIG. 1) grow on the surfaces of the suppression electrode 12, the ion suppression electrode 13, and the ground casing 14 within a few weeks. This is because the surface of the Faraday cup 11 is sputtered by the ion beam, and the scattered metal is deposited on the surface of the suppression electrode 12, the ion suppression electrode 13, and the ground housing 14 on the Faraday cup 11 side as a sputtered film. is there.

  When this sputtered film (metal films 17a to 17c) grows to a certain thickness, it peels off due to temperature change. The metal films 17a to 17c that are peeled off at this time have the concavo-convex shape shown in FIGS. For example, in FIG. 2, it peels off with the shape of the convex part 12c (diagonal length H), and in FIG. 3, it peels off with the shape of the convex part 12e (diagonal length J). In addition, since the sputtered film is difficult to be attached to the concave portion including the groove portion 12b and the hole 12d, it is difficult to peel off. The metal films 17a to 17c that have been peeled off fall between the Faraday cup 11, the suppression electrode 12, the ion suppression electrode 13, and the ground casing 14 that need to be electrically insulated from each other.

  Specifically, the metal film 17 a passes through the inside of the Faraday cup 11 or the upper end portion, or between the side surface of the suppression electrode 12 and the side surface of the Faraday cup 11, and falls to the inner bottom surface of the ground casing 14. Further, the metal film 17 b passes between the upper surface of the suppression electrode 12, the inside of the Faraday cup 11, or the most protruded portion of the side surface of the suppression electrode 12, and the inner surface of the ground housing 14 and falls to the inner bottom surface of the ground housing 14. Further, the metal film 17 c passes through the upper surface of the ion suppression electrode 13, the inside of the Faraday cup 11, or between the side end of the ion suppression electrode 13 and the inner side surface of the ground housing 14 and falls to the inner bottom surface of the ground housing 14.

  Here, as described above, the size of the metal films 17a to 17c to be peeled has a length of H or J and is shorter than the distance between the members (distances A to G). Therefore, these members (suppression electrode 12, ion suppression electrode 13, and ground casing 14) are deposited without short-circuiting. As a result, the original potential difference can be maintained between the members, and the beam current can be measured normally. In addition, what is necessary is just to remove regularly the metal films 17a-17c which peeled off.

  Since the location and size of the metal film are different depending on the shape of the Faraday device, at least the surface of the suppression electrode 12, the ion suppression electrode 13, and the ground housing 14 on the surface on which the metal film is formed. What is necessary is just to provide an unevenness | corrugation.

  Below, the Example of the Faraday apparatus 10 is described. In FIG. 1, distance A = 5 mm, B = 6 mm, C = 5 mm, D = 6, E = 8, F = 8, G = 6, and in FIG. 2, length H = 2 mm. In this case, the metal films 17a to 17c that are peeled off are square with a diagonal of 2 mm. The metal films 17a to 17c that have been peeled off fall between the Faraday cup 11, the suppression electrode 12, the ion suppression electrode 13, and the ground casing 14, but the lengths (2 mm) of the metal films 17a to 17c are the distance between the members. It is sufficiently shorter than (distances A to G).

  Therefore, the metal films 17a to 17c are deposited without short-circuiting these members. As a result, the original potential difference can be maintained between the members, and the beam current can be measured normally. In addition, the short circuit by the metal films 17a-17c which peeled off has not arisen in the maintenance for every 6 months. Conventionally, a short circuit has occurred unless the metal film is removed every two weeks to every two months.

  The ion doping apparatus of the present invention can be used for manufacturing a low-temperature polysilicon liquid crystal panel or the like.

It is a schematic sectional drawing of the Faraday apparatus mounted in the ion doping apparatus. It is a schematic plan view of the inner part of the upper surface of the suppression electrode. FIG. 3 is a sectional view taken along line XX in FIG. 2. It is a schematic plan view of the inner part of the upper surface of another suppression electrode. It is the YY sectional view taken on the line of FIG.

Explanation of symbols

10 Faraday device 11 Faraday cup 12 Suppression electrode 12b Groove (recess)
12c Convex part 12d Hole (concave part)
12e Convex part 13 Ion suppression electrode 14 Grounding casing 17a-17c Metal film

Claims (3)

Faraday cup for measuring beam current, suppression electrode for suppressing secondary electrons generated from the Faraday cup, ion suppression electrode for suppressing ions from plasma excited by ion beam, and covering these In an ion doping apparatus comprising a housing,
Each of the Faraday cup, the suppression electrode, the ion suppression electrode, and the casing is adjacent to at least the surface on which the metal film is formed among the suppression electrode, the ion suppression electrode, and the surface of the casing. An ion doping apparatus comprising a convex portion having a surface with a shorter diameter than a member interval.   The ion doping apparatus according to claim 1, wherein the convex portion is formed by forming a plurality of intersecting groove portions as concave portions.   The ion doping apparatus according to claim 1, wherein the convex portion is formed by forming a plurality of adjacent holes as concave portions.

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