JP5171860B2 - Ion implanter - Google Patents

Description

  The present invention relates to an ion implantation apparatus, and more particularly, to a SIMOX (Separation by Implanted Oxygen) ion implantation apparatus suitable for implanting oxygen ions into a silicon wafer using a silicon wafer as an object of implantation.

  Conventionally, as an ion implantation apparatus for implanting ions into a silicon wafer, an apparatus that irradiates an ion beam from an ion source into a processing chamber and implants oxygen ions or the like into the silicon wafer disposed in the processing chamber is known. In this type of ion implantation apparatus, for example, as described in Patent Document 1, a configuration is adopted in which a silicon wafer is disposed on a disk-shaped wafer holder and the side surface of the silicon wafer is held by holder pins.

JP 61-116746 A

  In the prior art, the configuration in which the side surface of the silicon wafer is held by the holder pins is adopted, but thermal vibration occurs during heating or ion implantation of the silicon wafer, such as generation of particles when the silicon wafer is mounted on the wafer holder. However, it is not sufficiently considered that particles are generated due to mechanical vibration.

  In particular, in the ion implantation apparatus for SIMOX, when particles are deposited on a silicon wafer, an implantation defect is created in the ion implantation process, which becomes a pinhole in the insulating layer, and the insulation characteristics of the silicon wafer deteriorate and insulation failure occurs. , Leading to degradation of wafer quality. These particles have various generation processes such as when a silicon wafer is mounted on a wafer holder, during a heating process, and during ion implantation.

  First, when the wafer is mounted, the structure is such that when the silicon wafer is set in the wafer holder, the silicon wafer is held stationary at a specific position by the wafer holding mechanism. Friction or rubbing occurs between the wafer and the holding mechanism, and particles are generated by this friction or rubbing.

  On the other hand, in the heating / implantation process, the silicon wafer is first heated by the heater, and then further heated with the irradiation of the ion beam. When the silicon wafer is heated in the process controlled to maintain a constant high temperature by adjusting the output of the heater simultaneously with the latter heating, the silicon wafer and the holding mechanism are simultaneously heated when the silicon wafer is heated. Friction or rubbing occurs between the two and particles are generated by this rubbing or rubbing.

  As described above, when the silicon wafer is held, if the silicon wafer is simply held, particles may be generated due to friction or rubbing between the silicon wafer and the holding mechanism.

  As described in Japanese Patent Laid-Open No. 5-326676, when holding a silicon wafer, the side surface of the silicon wafer is held by a pair of clampers, and the clamper is held in a swingable manner so that a constant clamp is always provided. It is conceivable to adopt a configuration in which the silicon wafer is clamped by force and the clamper is bent. However, if the clamper simply bends when the clamper contacts the silicon wafer, the contact between each clamper and the silicon wafer can be reduced. Depending on the manner or timing of contact, friction or rubbing may occur between each clamper and the silicon wafer, and particles may be generated.

  The subject of this invention is providing the ion implantation apparatus which can suppress that particle | grains generate | occur | produce with holding an implantation target.

  In order to solve the above problems, a processing chamber for forming a processing space for an implantation target in a vacuum atmosphere, an ion beam incident means for injecting an ion beam emitted from an ion source into the processing chamber, and a processing chamber. A holding unit arranged to hold the implantation target, and a transport unit that moves the holding unit as a passing region of the implantation target in an ion beam propagation region in the processing chamber, and the implantation unit includes the implantation unit. The contact portion with the object constitutes an ion implantation apparatus configured to be rotatable about an axis parallel to the axis of the holder base.

  In configuring the ion implantation apparatus, an ion source that generates and emits an ion beam is provided, or a specific ion species is extracted from the ion beam emitted from the ion source as an ion beam incident unit. A device having a function of injecting an ion beam into the processing chamber, or a transporting device having a function of moving the holding unit as a passing region of the implantation target within the ion beam propagation region of the specific ion species in the processing chamber Can also be used.

Furthermore, the holding means includes a disk-shaped holder base for supporting the injection target, fixed to the outer peripheral side of the holder base, a fixing member, a part in contact with the outer circumference of the injection target, said injection subject Two holder pins having a rotation axis in a direction perpendicular to the surface of the holder base opposite to the surface of the holder base, a spring force is applied to the two holder pins, and the injection target is determined by the resultant force of the two spring forces. There are two springs that move toward the fixing member, and the two springs are caused by friction between the two holder pins and the injection target when the injection target is pressed toward the fixing member. The two holder pins are biased in such a direction that the two holder pins rotate.

  In configuring each of the ion implantation apparatuses, the following elements can be added.

  (1) The conveying means includes a rotating disk that is rotationally driven by a driving source, and a plurality of holder arms that are coupled to the rotating disk and are radially disposed on the outer peripheral side of the rotating disk. The holder base is fixed to the tip side of the holder arm.

(2) The holder pin includes a cylindrical small-diameter portion that is a contact portion with the injection target, and large-diameter portions that are larger in diameter than the small-diameter portion and formed on both sides of the small-diameter portion. A tapered surface is formed between the small diameter portion and each large diameter portion so that the diameter gradually increases from the small diameter portion toward each large diameter portion.

  (3) A sphere that rotates by contact with the injection target is rotatably fixed to the holder base.

  (4) A bearing is attached to a contact portion of the support member with the holding member.

  (5) The bearing is made of ceramic.

  (6) The implantation target is a disk-shaped silicon wafer.

  According to the above-described means, the contact portion of the holding means with the injection target is configured to be rotatable about an axis parallel to the axis of the holder, so that the injection target is held by the holding means. Sometimes, when friction or rubbing occurs between the injection target and the holding means, the contact portion of the holding means with the injection target rotates, and friction or rubbing is avoided, and generation of particles can be suppressed. it can.

  Specifically, when a silicon wafer as an implantation target is mounted on the holder base or in the process of holding the side surface of the silicon wafer placed on the holder base with the fixing member and the holding member, it is accompanied by thermal vibration and mechanical vibration. If friction or rubbing occurs between the holding member and the silicon wafer, the holding member rotates and friction or rubbing between the holding member and the silicon wafer is avoided, and generation of particles can be suppressed. This can contribute to the improvement of wafer quality.

  ADVANTAGE OF THE INVENTION According to this invention, the ion implantation apparatus which can suppress that a particle generate | occur | produces with hold | maintaining an injection target can be provided.

1 is an overall configuration diagram of an ion implantation apparatus showing an embodiment of the present invention. (A) is a side view showing the relationship between the wafer holder and the holder arm when the wafer is mounted, and (b) is a side view showing the relationship between the wafer holder and the holder arm when the beam is incident. It is a figure for demonstrating the scanning and rotation method of a wafer. It is a front view for demonstrating the relationship between a wafer fixing | fixed part and a holder pin. It is a figure for demonstrating the relationship between a wafer fixing | fixed part and a holder pin, Comprising: It is sectional drawing in alignment with AA of FIG. It is a front view for demonstrating the moving direction of a holder pin. It is a principal part enlarged front view for demonstrating the moving direction of a holder pin. It is principal part sectional drawing for demonstrating other embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of an ion implantation apparatus showing an embodiment of the present invention. 1, the ion implantation apparatus includes an ion source 10, a mass separator 12, a processing chamber (end station) 14, a rotating disk 16, a holder arm 18, a wafer holder 20, and the like.

  The ion source 10 is connected to the mass separator 12 via a evacuated pipe (not shown), generates an ion beam 22 by oxygen ions using a 2.45 GHz microwave, and the generated ion beam. 22 is emitted to the mass separator 12 side. The mass separator 12 is connected to the processing chamber 14 via a evacuated pipe (not shown), and applies an electromagnetic force to the ion beam 22 from the ion source 10 to cause the ion beam 22 to be about 90 degrees. An ion beam that is deflected and separates and extracts only ion species having a required mass, for example, oxygen ions, from the ion beam 22 and enters the processing chamber 14 with the ion beam 22 of oxygen ions that are specific ion species. It is configured as an incident means. The processing chamber 14 is evacuated to a vacuum by an evacuation apparatus (not shown), and forms a processing space for a wafer (silicon wafer) 24 to be implanted in a vacuum atmosphere. The processing chamber 14 accommodates a rotating disk 16, a holder arm 18, a wafer holder 20, a motor box 26, and the like.

  The rotating disk 16 is a motor in a motor box 26 via a rotating shaft 28 as an element of transport means for moving the wafer holder 20 as a passing area of the wafer 24 in the propagation area of the ion beam 22 by specific ion species. It is connected to a drive source such as 30 and is driven to rotate. A plurality of, for example, 18 holder arms 18 are arranged on the outer peripheral side of the rotary disk 16, and the base end portion of each holder arm 18 is connected to the rotary disk 16 so as to be rotatable about its axis. Has been. At the front end side of each holder arm 18, the wafer holder 20 is fixed in a state inclined at about 3 degrees with respect to the vertical axis, and the wafer 24 is disposed on the wafer holder 20. That is, as shown in FIG. 2A, each wafer holder 20 is substantially parallel to the horizontal plane (inclined by about 3 degrees) when the wafer is loaded (when the wafer loading position is reached as the holder arm 18 rotates). Thus, when the ion beam 22 is incident on the wafer 24, the holder arm 18 is rotated from the position (a) about the axis about the axis of rotation, and is disposed at a position substantially orthogonal to the ion beam 22. It has become so. The ion beam 22 is sequentially incident on the wafer 24 on each wafer holder 20 as the holder arm 18 and the wafer holder 20 rotate as the rotary disk 16 rotates.

  Further, in order to make the ion beam 22 incident on the entire surface of the wafer 24, in this embodiment, the motor box 26 is connected to the swing mechanism 34 via the arm 32, and the motor box 26 is driven by the swing mechanism 34. Has become a pendulum exercise. When the motor box 26 moves in a pendulum manner, the ion beam 22 is sequentially scanned over the entire surface of the wafer 24 on each wafer holder 20 as the rotary disk 16 rotates as shown in FIG. An ion beam 22 is incident on the entire surface.

  Each holder arm 18 is made of aluminum, and each holder arm 18 has a tip end direction orthogonal to the rotation surface of each holder arm 18, that is, a direction orthogonal to the irradiation direction of the ion beam 24. The wafer holder base 36 is fixed to the tip of the bent portion.

  Each wafer holder base 36 is formed in a disk shape using an aluminum material, and as shown in FIGS. 4 and 5, a wafer fixing portion 38 as a fixing member is fixed to the outer peripheral side of each wafer holder base 36. In addition, holder pins 40 and 42 as holding members are arranged so as to be movable along the radial direction of the wafer holder base 36.

  A portion of the wafer fixing portion 38 protrudes along the radial direction of the wafer holder base 36 on the outer peripheral side of the wafer holder base 36, and a surface that contacts the outer peripheral side of the silicon wafer 24 disposed on the wafer holder base 36. The disc-shaped wafer 24 is formed in an arc shape having a curvature that matches the outer shape of the wafer 24.

  The holder pins 40 and 42 are formed in a columnar shape, and the bottom side thereof is integrally connected to the rotary shafts 40a and 42a. The rotary shafts 40a and 42a are rotatably supported by a ceramic bearing 44. Yes. The bearing 44 constitutes a support member together with a housing 46 and a coil spring 48 as an elastic body. These support members are disposed so as to be movable along the radial direction of the wafer holder base 36, and the holder pins 40 are rotated about the axis (Z axis) parallel to the axis of the wafer holder base 36, that is, the rotation axis. The holder pin 40 is rotatably supported around 40a and 42a as the rotation center. The housing 46 is swingably connected to the wafer holder base 36 via pins (not shown), and is connected to the wafer holder base 36 via a coil spring 48. Further, the end of the housing 46 is connected to a pusher (not shown). When the wafer 24 is set on the wafer holder base 36, the housing 46 is driven by the spring force (elastic force) of the coil spring 48 by driving the pusher. The wafer holder 24 is set on the wafer holder base 36 away from the wafer holder base 36 against the above. When the drive by the pusher is stopped after the wafer 24 is set on the wafer holder base 36, the housing 46 swings around the pin by the spring force of the coil spring 48 and moves to the wafer holder base 36 side. It is supposed to be.

  That is, in the present embodiment, the wafer holder 20 as a holding means for holding the wafer 24 movably includes a wafer holder base 36, a wafer fixing portion 38, holder pins 40 and 42, a bearing 44, a housing 46, and a coil spring 48. The wafer fixing portion 38 and the two holder pins 40 and 42 hold the outer peripheral side of the wafer 24 at three points.

  Further, in the present embodiment, the holder pins 40 and 42 that are contact portions with the wafer 24 are configured to be rotatable, and in the process of holding the side surface side of the wafer 24 with the two holder pins 40 and 42, When friction or rubbing occurs between the wafer pins 40 and 42, the rotation of the holder pins 40 and 42 avoids friction or rubbing between the wafer 24 and the holder pins 40 and 42, thereby suppressing generation of particles. Yes.

  Specifically, when chucking the wafer 24, the wafer 24 is moved in the horizontal direction until the end of the wafer 24 contacts the wafer fixing portion 38 while the holder pins 40 and 42 are in contact with the side surface of the wafer 24. Chucking. At this time, the moving direction of the wafer 24 is an arrow B, but the moving direction of the holder pins 40 and 42 is a direction determined by how the coil spring 48 is attached, and is an arrow C1 and C2. At this time, forces F1 and F2 are applied from the coil spring 48 to the holder pins 40 and 42, respectively. When the forces F1 and F2 are divided into the X direction and the Y direction including the moving direction of the wafer 24, they can be divided into FX1, FX2, and FY2. At this time, since FX1 and FX2 are balanced in the X direction, the wafer 24 does not move in the X direction, but the wafer 24 moves in the Y direction because of the same force in the Y direction. Accordingly, in FIG. 6, the wafer 24 moves in the B direction.

  Next, when the wafer 24 moves in the Y direction while being in contact with the holder pins 40, 42, as shown in FIG. 7, the contact point between the wafer 24 and the holder pins 40 moves from D to D '. Since it moves in the direction C by the elastic force of the coil spring 48, the contact point of the holder pin 40 moves from D to E. For this reason, the contact portion between the side surface of the wafer 24 and the holder pin 40 is rubbed at a distance of D ′ to E.

  However, in the present embodiment, since the holder pins 40 and 42 themselves rotate freely in a state of being rotatably supported by the bearing 44, the holder pin 40 rotates in the G direction by a distance from D ′ to E, and The wafer 24 is moved while being pushed in the direction D ′. Therefore, friction and rubbing between the side surface of the wafer 24 and the holder pins 40 can be prevented, and the wafer 24 can be moved to a stationary position.

  With respect to the holder pins 42, the wafer 24 can be moved to a stationary position without causing friction or rubbing between the holder pins 42 and the side surfaces of the wafer 24.

  Further, not only when the wafer 24 is mounted on the wafer holder 20 but also when the wafer 24 undergoes thermal elongation and a force from the wafer 24 acts on the holder pins 40 and 42 in the heating / injection process, the holder pin 40 is caused by this force. , 42 rotates, so that the wafer 24 is free from thermal expansion without causing friction or rubbing between the wafer 24 and the holder pins 40, 42. Thereby, it is possible to prevent the generation of particles from the contact portion between the wafer 24 and the holder pins 40 and 42, which can contribute to the improvement of quality.

  Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, the housing 50 is fixed on the wafer holder base 36, a spherical concave portion is formed on the upper surface side of the housing 50, and the sphere 52 is rotatably mounted in the concave portion. The bottom side of the wafer 24 is rotatably held, and other configurations are the same as in the above embodiment.

  In the present embodiment, the wafer 24 moves while rubbing the surface of the sphere 52 in the process of moving the wafer 24 until the wafer 24 comes into contact with the wafer fixing portion 38 and stops. Since the sphere 52 freely rotates in accordance with the above, the wafer 24 is brought into contact with the wafer fixing portion 38 without causing friction or rubbing between the wafer 24 and the sphere 52 while changing the contact point between the wafer 24 and the sphere 52. It is possible to move to a position where Thereby, it can prevent that a particle | grain generate | occur | produces from the contact part of the spherical body 52 and the wafer 24, and can contribute to the improvement of quality.

  In each of the above embodiments, the holder pins 40 and 42 are formed in a cylindrical shape. However, as the holder pins 40 and 42, a part of the holder pins 40 and 42, i.e., a portion that is a contact portion with the wafer 24. A columnar small diameter part is formed, and both sides of the small diameter part are made large diameter parts, and a tapered surface is formed between the small diameter part and each large diameter part so that the diameter gradually increases from the small diameter part toward each large diameter part. It is also possible to adopt a configuration that does this.

  According to the present invention, the contact portion of the holding means with the injection target is configured to be rotatable about an axis parallel to the axis of the holder as a center of rotation. Even if rubbing occurs, the contact portion of the holding means with the injection target rotates, friction or rubbing can be avoided, generation of particles can be suppressed, and it can contribute to quality improvement. .

DESCRIPTION OF SYMBOLS 10 Ion source 12 Mass separator 14 Processing chamber 16 Rotating disk 18 Holder arm 20 Wafer holder 22 Ion beam 24 Wafer 26 Motor box 28 Rotating shaft 30 Motor 32 Arm 34 Swing mechanism 36 Wafer holder base 38 Wafer fixing part 40, 42 Holder pin 44 Bearing 46 Housing 48 Coil spring

Claims (2)

A processing chamber for forming a processing space for an implantation target in a vacuum atmosphere, an ion beam incident means for injecting an ion beam emitted from an ion source into the processing chamber, and the implantation target disposed in the processing chamber for holding the implantation target Holding means, and a transfer means for moving the holding means as a passing area of the implantation target in the propagation region of the ion beam in the processing chamber,
The holding means is a disk-shaped holder base for supporting the injection target, a fixing member fixed to the outer peripheral side of the holder base, a part of which is in contact with the outer periphery of the injection target, and facing the injection target Two holder pins having a rotation axis in a direction perpendicular to the surface of the holder base, and a spring force is applied to the two holder pins, and the injection target is fixed by the resultant force of the two spring forces. Having two springs that move towards the member,
The two springs, said when the injection subject presses toward the fixing member, wherein the friction between the two holder pin the injection target, together with the two holder pin is rotated, the holder pin is the injection An ion implantation apparatus characterized in that the two holder pins are urged along a periphery of an object in a direction so as to move toward an end opposite to the end of the implantation target in contact with the fixing member . In claim 1,
The two springs are directions in which the spring force of the two springs is canceled in the x direction when the movement direction of the injection target by the two holder pins is the y direction and the direction perpendicular to the movement direction is the x direction. Further, the ion implantation apparatus is characterized in that the two holder pins are biased.

Images