JP2010177686A - Wafer chucking apparatus and chucking method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chucking apparatus and a chucking method for a wafer, which can prevent occurrence of lifting and displacement of the wafer when conduction is secured from the back of the wafer and reduce a residual electric charge as much as possible when the wafer is removed from a chuck. <P>SOLUTION: The chucking apparatus includes: a first and a second electrodes 4 and 6; an insulator part 8 on which the back of the wafer is placed; an electrostatic chuck part 2 having a through hole passing through from the back to the principal plane of the insulator part; a conduction needle 20 which can be passed through the through hole; a conduction needle drive device 24 for driving the conduction needle so as to move it in the through hole from the back to the principal plane of the insulator part to thrust another end of the conduction needle onto the back of the wafer; and a voltage controller 10 which can provide a voltage different in polarity and the same in polarity to the first and the second electrodes, and also make a value of voltage to be provided to the first and the second electrodes variable. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wafer chucking apparatus and a chucking method.

  In general, a wafer flowing in a processing line during a semiconductor manufacturing process prevents cross contamination by covering the surface with an insulating film (for example, a silicon oxide film or a silicon nitride film). In such an apparatus for processing a wafer covered with an insulating film in a vacuum, a mechanical chuck system or an electrostatic chuck system is used because a vacuum chuck system cannot be used for fixing the wafer.

  However, the mechanical chuck method is not used because of problems such as non-uniform stress applied to the wafer and deterioration of the flatness of the wafer. In addition, two electrodes are brought into contact with the wafer, a high voltage (for example, 1 to 3 kV) is applied between the two electrodes, and the wafer is discharged, whereby the outer peripheral portion (portion where no element is formed) of the wafer is There is also known a method of partially destroying an insulating film to achieve conduction (for example, see Patent Document 1). However, when this method is used, an element being manufactured inside the wafer is damaged, and therefore, it is necessary to perform a process of removing the insulating film in advance only for a portion where conduction is desired.

  The electrostatic chuck system includes a monopolar type and a bipolar type. In the case of the monopolar type, it is necessary to control the voltage between the electrodes in the wafer and the electrostatic chuck, and it is necessary to ensure electrical conduction to the wafer.

  In the case of the bipolar type, it is not always necessary to ensure electrical conduction directly with the wafer. When voltages having different polarities are applied to the two types of electrodes in the electrostatic chuck, charges different from the opposing electrostatic chuck electrodes are collected on the surface of the wafer that is in surface contact via the insulating layer. For this reason, an electric force acts between the wafer and the electrostatic chuck to hold the wafer.

JP 59-135741 A

  However, in an apparatus using an electron beam, for example, an electron beam drawing apparatus, since an arbitrary position of the wafer is irradiated, it is desirable that the wafer has the same potential, and the best state is that the wafer has a uniform zero potential. It is that you are. For this reason, conventionally, the use of bipolar electrostatic chucks has been avoided in electron beam lithography systems.

  Further, as described above, in the monopolar electrostatic chuck, it is necessary to ensure electrical conduction to the wafer. However, an insulating film made of, for example, a silicon oxide film or a silicon nitride film formed on the outer periphery of the wafer is harder than a metal oxide film, and in order to ensure electrical conduction by penetrating the insulating film with a contact needle, A relatively large contact pressure is required.

  If this contact pressure is applied from the lower surface of the wafer before the wafer is held, the wafer is lifted or displaced, and it is difficult to ensure electrical conduction. If the contact needle is made quite thin, the contact pressure can be lowered, but there is a problem that the life of the tip of the contact needle becomes extremely short. For this reason, in general, the contact needle is often pressed from the upper surface of the wafer. However, in this case, for the contact needle and the mechanism for operating the contact needle, it is necessary to provide a region on the upper surface of the wafer where irradiation by the electron beam drawing apparatus is prohibited. There is a problem that the yield of chips is poor.

  Furthermore, a vacuum apparatus in a semiconductor manufacturing apparatus includes a process of automatically holding a wafer in a chuck or removing it from a chuck in a vacuum. In particular, the wafer often has a residual charge when removed from the chuck. For this reason, when the push-up pins or arms that remove the wafer from the chuck plate come into contact, the following problems occur.

  Despite the fact that the chucking force between the chuck plates due to the residual charge in the wafer is acting, a large force is required for the push pin or arm in order to try to peel it off by the push pin or arm. Further, since the wafer jumps up at the moment when the peeling force by the push-up pin or arm wins against the above-mentioned suction force, the wafer falls off and automatic transfer becomes impossible.

  Further, when the wafer is removed from the chuck, a discharge phenomenon occurs between the residual charge in the wafer and the push-up pin or arm, and a high-voltage minute current flows through the wafer, damaging the semiconductor device formed on the wafer. There is a problem.

  The present invention has been made in consideration of the above circumstances, and can prevent the wafer from being lifted and misaligned when securing the conduction of the wafer covered with the insulator film from the back surface of the wafer. An object of the present invention is to provide a wafer chucking apparatus and a chucking method capable of reducing residual charges as much as possible when removing a wafer from a chuck.

  One embodiment of the present invention includes an electrostatic chuck mechanism that includes a plurality of electrodes each configured to be capable of independently supplying electric power and configured to electrostatically attract a substrate to be processed, and at least the substrate to be processed A conduction mechanism configured to be in contact with the back surface and electrically conductive with the substrate to be processed itself, and to an electrode different from the conduction mechanism side electrode after supplying power to the conduction mechanism side electrode of the plurality of electrodes. An electron beam drawing apparatus comprising: a control mechanism that controls to apply electric power; and an electron beam irradiation mechanism that irradiates the substrate to be processed with an electron beam to perform a predetermined process.

  According to another aspect of the present invention, there is provided an electrostatic chuck mechanism including a plurality of electrodes each configured to be capable of independently supplying power, and configured to electrostatically attract a substrate to be processed; A conduction mechanism configured to be in contact with at least the back surface and electrically connectable to the substrate to be processed; an electrode on the conduction mechanism side after supplying power only to the electrode closest to the conduction mechanism side of the plurality of electrodes; An electron beam drawing apparatus comprising: a control mechanism for controlling power to be applied to different electrodes; and an electron beam irradiation mechanism for performing predetermined processing by irradiating the substrate to be processed with an electron beam. is there.

  According to still another aspect of the present invention, there is provided an electrostatic chuck mechanism including a plurality of electrodes each configured to be capable of independently supplying power, and configured to electrostatically attract a substrate to be processed, and the substrate to be processed A conduction mechanism configured to be in contact with at least the back surface of the substrate and electrically connectable to the substrate to be processed, and to supply power to the electrode on the conduction mechanism side of the plurality of electrodes to electrically connect the conduction mechanism and the substrate to be processed. A control mechanism for controlling power to be applied to an electrode different from the electrode on the conduction mechanism side after making it electrically conductive, an electron beam irradiation mechanism for irradiating the substrate to be processed with an electron beam and performing a predetermined process, An electron beam drawing apparatus comprising:

  According to still another aspect of the present invention, there is provided an electrostatic chuck mechanism including a plurality of electrodes each configured to be capable of independently supplying power, and configured to electrostatically attract a substrate to be processed, and the substrate to be processed A conduction mechanism configured to be in contact with at least the back surface of the substrate to be electrically conductive with the substrate to be processed, and to supply electric power of the same polarity to the plurality of electrodes so that the conduction mechanism and the substrate to be processed are electrically conductive. After that, a control mechanism that controls to apply an electric power having a polarity different from the same polarity to an electrode different from the electrode on the conduction mechanism side, and an electron beam irradiation that irradiates the substrate to be processed with an electron beam and performs a predetermined process An electron beam drawing apparatus comprising a mechanism.

  Still another embodiment of the present invention is an electron beam drawing method for performing predetermined processing by irradiating an electron beam onto a substrate to be processed that is electrostatically attracted and held. Different from the step of electrostatically adsorbing the region of the part, the step of bringing a conduction mechanism electrically connected to the substrate to be processed from the back surface of the substrate to be processed, and a partial region of the back surface of the substrate to be processed And a step of electrostatically adsorbing the region.

  Still another embodiment of the present invention is an electron beam drawing method for performing predetermined processing by irradiating an electron beam onto a substrate to be processed that is electrostatically attracted and held. A step of electrostatically adsorbing one region, a step of contacting a conduction mechanism electrically connected to the substrate to be processed from the back surface of the substrate to be processed, and the first region on the back surface of the substrate to be processed. Is an electron beam drawing method comprising: a step of electrostatically attracting different second regions; and a step of detecting the flatness of the substrate to be processed.

  Still another aspect of the present invention is an electron beam drawing method for performing predetermined processing by irradiating an electron beam onto a substrate to be processed that is electrostatically attracted and held. A step of electrostatically adsorbing a first region of the back surface of the substrate to be processed close to the contact position before contacting a conduction mechanism that is electrically connected to the processing substrate; A step of contacting a conductive mechanism that is electrically conductive with the substrate, a step of electrostatically adsorbing a second region different from the first region on the back surface of the substrate to be processed, and a substrate to be processed thereafter And a step of detecting the flatness of the electron beam drawing method.

  Still another embodiment of the present invention is an electron beam drawing method for performing predetermined processing by irradiating an electron beam onto a substrate to be electrostatically held by adsorption, wherein the back surface of the substrate to be processed is the same A step of electrostatically attracting a plurality of places with electric power of polarity, a step of contacting a conduction mechanism electrically connected to the substrate to be processed from the back surface of the substrate to be processed, and a back surface of the substrate to be processed having the same polarity and An electron beam drawing method comprising: a step of electrostatically attracting partly with electric power having a plurality of polarities different from the same polarity.

  A wafer chucking apparatus according to a reference example of the present invention electrically separates a first electrode and a second electrode arranged so as not to overlap each other, and the first electrode and the second electrode, and the main surface is a back surface of the wafer. And an electrostatic chuck portion having a through-hole penetrating from the back surface of the insulator portion to the main surface, one end of which is connected to a reference potential via a wiring and can pass through the through-hole. A conductive needle and a conductive needle drive that drives the conductive needle so that the other end of the conductive needle protrudes from the back surface of the wafer by moving the conductive needle through the through hole from the back surface of the insulator portion toward the main surface. It is possible to apply voltages having different polarities to the device and the first and second electrodes, and to apply voltages having the same polarity to the first and second electrodes, and to the first and second electrodes. Variable voltage value for Characterized by comprising a voltage controller capable of and.

  The voltage controller includes first and second switches that are turned off when one is turned on, a first power source that applies a voltage to the first electrode, and the first switch through the first switch. A second power source for applying a voltage having a polarity different from that of the first power source to the two electrodes; and a third power source for applying a voltage having the same polarity as the first power source to the second electrode via the second switch. You may comprise as follows.

  The voltage controller applies a voltage to the first electrode and the first electrode that are turned off when one is turned on, and the voltage applied to the second electrode through the first switch. And a second power source for applying a voltage having a polarity different from that of the first power source to the second electrode via the second switch.

  In addition, a wafer chucking method according to another embodiment of the present invention includes a first electrode and a second electrode which are arranged so as not to overlap each other and electrically separated by an insulator, and penetrate from the back surface to the main surface. A step of placing a wafer on the main surface of the electrostatic chuck portion having a through-hole, applying a voltage having the same absolute value and different polarity to the first and second electrodes, and one end connected to a reference potential; The other end of the conductive needle is pushed to the back surface of the wafer through the through hole, and the chucking quality of the wafer is determined based on one of the current flowing through the conductive needle and the contact resistance of the conductive needle. And a step of applying a voltage having the same absolute value and polarity to the first and second electrodes when the chucking of the wafer is determined to be good.

  The wafer chucking method according to still another reference example of the present invention is such that a wafer is placed on the main surface of an electrostatic chuck portion having an electrostatic chuck electrode, and then a conductive needle is applied to the back surface of the wafer. Applying a fritting voltage to establish conduction between the wafer and the conductive needle, and then applying a voltage to the electrostatic chuck electrode of the electrostatic chuck portion to place the wafer on the electrostatic chuck portion. It is characterized by chucking.

  According to the present invention, when electrical continuity is ensured for a wafer covered with an insulator film from the back surface of the wafer, the wafer can be prevented from being lifted and misaligned, and the wafer can be removed from the chuck. The residual charge can be reduced as much as possible.

1 is a configuration diagram showing a configuration of a wafer chucking apparatus according to a first embodiment of the present invention. The flowchart explaining operation | movement of the chucking apparatus by 1st Embodiment. The flowchart explaining the detail of the 1st chuck | zipper process shown in FIG. The flowchart explaining the detail of the conduction | electrical_connection process shown in FIG. The flowchart explaining the detail of the 2nd chuck | zipper process shown in FIG. The figure explaining how to obtain | require contact resistance in the case of determining the quality of chucking using the contact resistance of a conduction needle. The figure which shows the structure of the 1st modification of 1st Embodiment. The top view of the 1st specific example of the electrode used for 1st Embodiment. The top view of the 2nd specific example of the electrode used for 1st Embodiment. The top view of the 3rd specific example of the electrode used for 1st Embodiment. The top view of the 4th specific example of the electrode used for 1st Embodiment. The top view of the 5th example of the electrode used for 1st Embodiment. The figure which shows the structure of the wafer chucking apparatus by 2nd Embodiment of this invention. 9 is a flowchart showing the operation of the wafer chucking apparatus according to the second embodiment. The figure which shows the structure of the 2nd modification of 1st Embodiment.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

(First embodiment)
The configuration of the wafer chucking apparatus according to the first embodiment of the present invention is shown in FIG. The wafer chucking apparatus according to this embodiment includes an electrostatic chuck unit 2, a voltage controller 10, a conduction needle 20, and a conduction needle drive mechanism 24. The electrostatic chuck portion 2 includes a first electrode 4, a second electrode 6, and an insulator portion 8. The insulator portion 8 has a flat main surface on which the wafer 100 is placed, and has a through-hole 9 penetrating from the back surface to the main surface. Note that the main surface of the insulator portion 8 is in contact with the back surface of the wafer 100, that is, the surface opposite to the surface on which the semiconductor elements and the like are formed. The through-hole 9 has a size through which the conductive needle 20 can pass. The first and second electrodes 4 and 6 are embedded in the insulator portion 8 and arranged so as not to overlap each other when viewed from the main surface side.

  The voltage controller 10 includes power supplies 12, 14a, 14b and switches 16a, 16b. The power supply 12 has one end connected to the reference potential GND and the other end connected to the first electrode. The power supply 14a has one end connected to the reference potential GND and the other end connected to the second electrode 6 via the switch 16a. The power supply 14b has a polarity different from that of the power supply 14a, and has one end connected to the reference potential GND and the other end connected to the second electrode 6 via the switch 16b. When a voltage is applied to the electrode 6, one of the switches 16a and 16b is turned on and the other is turned off.

  The conduction needle 20 is driven by the conduction needle drive mechanism 24 so as to be movable in the through hole 9 of the insulator portion 8 from the back surface side to the main surface side and from the main surface side to the back surface side. The leading end of the conductive needle 20 is configured to be pressed against the back surface of the wafer 100 placed on the main surface of the insulator unit 8 by the drive mechanism 24. The conduction needle 20 is connected to the reference potential GND via the wiring 26 and the ammeter 28.

  Next, the operation of the wafer chucking apparatus according to the first embodiment will be described with reference to FIGS. FIG. 2 is a flowchart showing an outline of a method of chucking the wafer 100 by the chucking apparatus according to the present embodiment. First, the wafer 100 is mounted on the main surface of the electrostatic chuck unit 2 (see step F0), and then the first chuck process is executed (see step F1).

  Details of the first chucking step will be described with reference to FIG. First, voltages Ea1 and Ea2 having the same absolute value but different polarities are applied to the two electrodes 4 and 6 of the electrostatic chuck unit 2 on which the wafer 100 is placed, thereby temporarily chucking in a bipolar manner (see step F10). . Subsequently, the surface height, that is, the flatness of the wafer 100 is measured using, for example, a light lever type height sensor (not shown in FIG. 1) (see step F11). Thereafter, it is determined whether or not the measured flatness is within an allowable value (see step F12). When the measured flatness is within the allowable value, the first chucking process is completed (see step F13). As the number of layers of films formed on the wafer 100 increases, “undulation” occurs in the wafer 100 and the flatness of the wafer 100 deteriorates. For this reason, the flatness of the wafer 100 is improved by chucking before drawing with an electron beam.

  In step F12 of FIG. 3, if the measured flatness is outside the allowable value, it is determined that the wafer is defective (see step F14), the wafer 100 is removed from the electrostatic chuck portion 2, and step F0 shown in FIG. Returning to (see step F15 in FIG. 3), a wafer to be newly chucked is placed on the electrostatic chuck unit 2. In step F12 of FIG. 3, if the measured flatness is outside the allowable value, the wafer is not replaced and the process returns to step F10 to perform temporary chucking again and measure the flatness again. Also good. In this case, when the flatness measurement result is out of the allowable value, the process proceeds to step F14.

  Next, when the first chucking process described above is completed, the process proceeds to step F2 in FIG. Details of the conduction process with the back surface of the wafer 100 will be described with reference to FIG. First, the conduction needle 20 is raised by the conduction needle drive mechanism 24 (see step F20), and the conduction needle 20 is projected on the back surface of the wafer 100 placed on the electrostatic chuck unit 2. And the electric current which flows into the wafer 100 and earth | ground GND via the conduction needle | hook 20 is measured with the ammeter 28 (refer step F21).

  Thereafter, the voltage Es1 applied to one of the electrodes 4 and 6, for example, the electrode 4 is changed (see step F22). As a result, the balance between the voltage Es1 applied to the electrode 4 and the voltage Es2 applied to the electrode 6 is lost, and the potential of the neutral wafer 100 is changed to a potential having one of the polarities. A leak current IΔEs flows between the wafer 100 and the reference potential GND via the needle 20. This leak current IΔEs is measured by an ammeter 28. In this way, by flowing a leakage current, it is possible to release the charge charged on the wafer 100 to the reference potential GND, and the residual charge on the wafer 100 can be reduced as much as possible.

  In this manner, it is determined in step F23 whether or not the leakage current IΔEs obtained in step F22 of FIG. 4 is a value within a specified value. If the leakage current IΔEs is within the specified value, the conduction process with the back surface of the wafer 100 is completed. If the leakage current IΔEs is outside the specified value, the process proceeds to Step F24, the conduction needle 20 is lowered and separated from the wafer 100, and then the process returns to Step F20 to conduct the conduction process with the back surface of the wafer 100 again. If the leakage current IΔEs is outside the specified value even after conducting the conduction process again, the wafer 100 is removed from the electrostatic chuck unit 2, and the process proceeds to Step F 0 in FIG. 2 to place a new wafer 100 on the electrostatic chuck unit 2. To do.

  Next, when the above-described conduction process is completed, the process proceeds to step F3 in FIG. Details of the second chucking step will be described with reference to FIG. First, the voltage applied to one of the electrodes 4, 6 of the electrostatic chuck portion 2, for example, the electrode 6, is dropped to the reference potential GND (see step F30). At this time, the voltage of the other electrode 4 is not changed. Thereby, the electric charge charged in the wafer 100 escapes to the reference potential GND, and the residual electric charge of the wafer 100 can be reduced as much as possible. At this time, the leak current IΔEs flowing through the conductive needle 20 to the wafer 100 and the reference potential GND is measured by the ammeter 28 (see step F31). Then, in step F32, it is determined whether or not the measured leakage current IΔEs is within a specified value. If the leakage current IΔEs is outside the specified value, the process returns to step F30 and the above steps are repeated. If the leakage current IΔEs is within the specified value, the process proceeds to step F33, and the voltage Es2 applied to the electrode 6 is set to the same value as the voltage Es1 applied to the electrode 4 from the reference potential GND level. That is, the wafer 100 is chucked by a single pole type electrostatic chuck method.

  Subsequently, the leak current IΔEs flowing between the wafer 100 and the reference potential GND through the conductive needle 20 is measured by the ammeter 28 (see step F34). Then, in step F35, it is determined whether or not the measured leakage current IΔEs is within a specified value. If the leakage current IΔEs is outside the specified value, the process returns to step F33 and the above steps are repeated. If the leakage current IΔEs is within the specified value, the process proceeds to step F36, and the flatness of the wafer 100 is measured by a height sensor (not shown). In step F37, it is determined whether or not the measured flatness is within the allowable value. If the measured flatness is within the allowable value, the second chuck process is completed. If it is outside the allowable value, it is determined that the wafer 100 is defective (see Step F38), and the process returns to Step F0 in FIG. 2 to place a new wafer 100 on the electrostatic chuck unit 2.

  In the conduction step and the second chuck step, the quality of conduction between the wafer 100 and the conduction needle 20 is determined based on the current value. However, the contact resistance value of the conduction needle 20 is a measured value of leakage current. Then, the contact resistance of the conduction needle 20 may be calculated from the voltage values Es1 and Es2, and may be determined based on the calculated contact resistance of the conduction needle 20.

A method of calculating the contact resistance will be described with reference to FIG. FIG. 6A is a block diagram of the chucking device when the voltage applied to one of the electrodes 4 and 6 is changed, and FIG. 6B is a circuit diagram at this time. It is. ΔEs shown in FIG. 6A is a difference in voltage applied to the electrode 4 and the electrode 6. As shown in FIG. 6B, the resistance value of the insulator part 8 between the electrode 4 and the wafer 100 is Res1, the resistance value of the insulator part 8 between the electrode 6 and the wafer 100 is Res2, and the conduction needle. The contact resistance 20 is Rs, the internal resistance of the ammeter 28 is Rc, the current flowing through the system composed of the electrode 4 and the conductive needle 20 is Is1, and the current flowing through the system composed of the electrode 6 and the conductive needle 20 is Is2. Then, the current IΔEs actually flowing through the conductive needle 20 is
IΔEs = Is1 + Is2 (1)
It becomes. And Is1 and Is2 are
Is1 = Es1 / (Res1 + Res2 + Rc) (2)
Is2 = Es2 / (Res1 + Res2 + Rc) (3) From these equations (1), (2), and (3), the contact resistance Rs of the conductive needle 20 is obtained. If the resistance Res1 and the resistance Res2 are the same value Res, that is, assuming that Res1 = Res2 = Res, the contact resistance Rs of the conductive needle 20 is:
Rs = ΔEs / IΔEs− (Res + Rc)
It becomes.

  As described above, in the present embodiment, since the residual charge on the wafer 100 is released to the reference potential via the conduction needle 20, the residual charge can be reduced as much as possible. Thereby, when removing the wafer 100 from the chucking device, even if the peeling force by the push-up pins or the arms acts on the wafer 100, the wafer 100 can be prevented from being lifted and also prevented from being displaced. Can do.

  Further, when the wafer 100 is removed from the chucking apparatus, in the prior art, a discharge phenomenon has occurred between the wafer and the push-up pin or arm, but in this embodiment, the residual charge of the wafer 100 is transferred to the conductive needle 20. Therefore, it is possible to prevent a discharge phenomenon from occurring between the wafer and the push-up pin or arm. This can prevent the semiconductor device from being broken.

  In the first embodiment, the voltage controller 10 includes the three power supplies 12, 14a, and 14b. However, the voltage controller 10 may be configured to include the two power supplies 12 and 14 as shown in FIG. good. In this case, the power supply 12 is connected to the first electrode 4 and also to the second electrode 6 via the switch 17a. The power source is connected to the second electrode 6 through the switch 17b.

  Specific examples of the first electrode 4 and the second electrode 6 used in this embodiment will be described with reference to FIGS.

  FIG. 8 shows a configuration of a first specific example of the electrodes 4 and 6 used in the present embodiment. FIG. 8 is a plan view of the electrodes 4 and 6 of the first specific example. In FIG. 8, the electrodes 4 and 6 have a shape that is nested in each other. The space between the electrodes 4 and 6 is covered with an insulator 8. These electrodes 4 and 6 are fixed to the insulator portion 8 with screws 70.

  FIG. 9 shows a configuration of a second specific example of the electrodes 4 and 6 used in this embodiment. FIG. 9 is a plan view of the electrodes 4 and 6 of the second specific example. In FIG. 9, the electrodes 4 and 6 have a shape in which they are nested together. The electrodes 4 and 6 are covered with an insulator 8.

  FIG. 10 shows a configuration of a third specific example of the electrodes 4 and 6 used in this embodiment. FIG. 10 is a plan view of the electrodes 4 and 6 of the third specific example. In FIG. 10, electrodes 4 and 6 have a half-moon shape and are surrounded by an insulator 8.

  FIG. 11 shows the configuration of a fourth specific example of the electrodes 4 and 6 used in this embodiment. FIG. 11 is a plan view of the electrodes 4 and 6 of the fourth specific example. In FIG. 11, the electrodes 4 and 6 have a quadrant shape and are surrounded by the insulator portion 8.

  FIG. 12 shows the configuration of a fifth specific example of the electrodes 4 and 6 used in this embodiment. FIG. 12 is a plan view of the electrodes 4 and 6 of the fifth specific example. In FIG. 12, the electrodes 4 and 6 are each annular, and the electrode 6 surrounds the electrode 4 and is electrically separated by the insulator portion 8.

  The conductive needle 20 used in the present embodiment is made of any one of conductive diamond, tungsten carbide, alumina titanium carbide ceramic (Al2O3 + TiC), cermet (TiC + TiN) tungsten, palladium, iridium, and beryllium-copper alloy. ing. Further, particularly important properties as a material used for the conductive needle 20 are (1) conductivity, (2) hardness, and (3) non-magnetic.

(Second Embodiment)
Next, a wafer chucking apparatus according to a second embodiment of the present embodiment will be described with reference to FIGS. The wafer chucking apparatus according to this embodiment uses the fritting phenomenon to break the insulating film of the wafer and bring the wafer and the conductive needle into electrical conductive contact. The fritting phenomenon is a phenomenon in which the contact resistance increases when the film due to oxidation or the like is 5 nm or more on the wafer surface, but suddenly decreases when a certain voltage is applied. When the coating is a metal oxide film, it is known that a fritting phenomenon occurs when the potential gradient reaches 105 to 106 V / cm. The wafer chucking device according to this embodiment includes an electrostatic chuck portion 2A, an electrostatic chuck power supply 10B, conduction needles 20A and 20B, a conduction needle drive mechanism 40, and a fritting voltage application device 60. Yes.

  The electrostatic chuck portion 2 </ b> A includes an electrostatic chuck electrode 5 and an insulator portion 8. The electrostatic chuck electrode 5 is embedded in the insulator portion 8. The insulator portion 8 has a flat main surface on which the wafer 100 is placed, and has through holes 9A and 9B penetrating from the back surface to the main surface. Note that the main surface of the insulator portion 8 is in contact with the back surface of the wafer 100, that is, the surface opposite to the surface on which the semiconductor elements and the like are formed. Further, the through holes 9A and 9B have a size through which the conductive needles 20A and 20B can pass.

  The electrostatic chuck power supply 10B includes a power supply 12 and a switch 13. By switching the switch 13, the potential applied to the electrostatic chuck electrode 5 is set to the power supply potential Es or the reference potential GND. ing.

  The conduction needle drive mechanism 40 includes a guide 42, a motor 44, a screw 46 that is coupled to the shaft of the motor 44 and rotates with the rotation of the shaft of the motor 44, a moving member 48 that can move up and down along the guide 42, A horizontal member 49 that is fixed to the moving member 48 and extends in the horizontal direction, a fixing member 50 that is fixed to the horizontal member 49 and is internally threaded and screwed into the screw 46, and a conductive needle that is fixed to the horizontal member 49. A force detector 52 that detects a force applied to 20A and 20B, and insulators 54A and 54B provided on the horizontal member 49 and embedded with one end of the conductive needles 20A and 20B are provided. When the motor 44 rotates, the screw 52 rotates, and thereby the fixing member 50 moves up and down. With the movement of the fixing member 50, the horizontal member 49, that is, the moving member 48 moves along the guide 42. If the horizontal member 49 moves upward, the conductive needles 20A and 20B will stick to the back surface of the wafer 100 placed on the main surface of the insulator portion 8.

  The fritting voltage application device 60 includes a programmable voltage source 61, a buffer amplifier 62, a current detection resistor 64, a current limiting amplifier 66, and a switch 68, and applies a fritting potential to the conductive needle 20A. The conductive needle 20B is always supplied with the reference potential GND.

  Next, the operation of the wafer chucking apparatus according to the present embodiment will be described with reference to FIG.

  First, as shown in Step F50 of FIG. 13, the wafer 100 is placed on the electrostatic chuck portion 2A. Subsequently, the conductive needles 20A and 20B are moved to the back surface of the wafer 100 by the conductive needle drive mechanism 40 (see step F51). Further, the conduction needles 20A and 20B are pressed against the back surface of the wafer 100 by the conduction needle drive mechanism 40, and the pressing force at this time is detected by the force detection unit 46 (see step F52). In step F53, it is determined whether or not the detected pressing force is within the specified value range. If the detected pressing force is outside the specified value range, the process returns to step F51, the position of the conductive needle is adjusted, and the above is repeated. If the pressing force detected in step F53 is within the specified value range, the process proceeds to step F54.

  In step 54, the fritting voltage is applied to the conductive needle 20 </ b> A by the fritting voltage applying device 60. When the insulating film of the wafer 100 is broken by the fritting voltage, the electric circuit including the buffer amplifier 62, the current detection resistor, the switch 68, the conductive needle 20A, the insulating film of the wafer 100, the base of the wafer 100, and the conductive needle 20B is formed. Current flows. At this time, the reference potential GND is applied to the electrostatic chuck electrode 5 from the power supply 10B for the electrostatic chuck.

  Subsequently, the current flowing through the electric circuit is detected by the current detection resistor 64 (see step F55). In step F56, it is determined whether or not the detected current value is within a specified value. If the detected current value is outside the specified value range, the voltage applied to the conduction needle 20A is increased by the fritting voltage applying device 60 (see step F57), the process returns to step F54, and the above is repeated. As the voltage is raised, current suddenly flows at a certain point. This rapid current rise is detected, and it is used as a substitute for the fact that conduction between the conductive needle 20A and the wafer 100 can be secured. If the detected current value is within the specified value range, the process proceeds to step F58.

  In step F58, the reference potential GND is applied to the conduction needle 20A by the switch 68 of the fritting voltage applying device 60, and the electrical circuit is separated. Thereafter, the electrostatic chuck voltage Es is applied to the electrostatic chuck electrode 5 by switching the switch 13 of the electrostatic chuck power source 10B (see step F59). At this time, an electric current is supplied to the electric circuit of the electrostatic chuck power source 10B, the electrostatic chuck electrode 5, the insulator 8 of the electrostatic chuck unit 2, the insulating film of the wafer 100, the base of the wafer 100, the conductive needle 20B, and the reference potential GND. Flows. In step F60, the current flowing through the conductive needle 20B is detected by a current detector (not shown). If the detected current value is within the specified value range, it is determined that the chucking of the wafer 100 is complete, and the next operation, for example, drawing using an electron beam is performed. If the detected current value is outside the specified value range, the process returns to step F60 and the above is repeated. When the number of repetitions exceeds a predetermined value, the wafer 100 is peeled off from the electrostatic chuck portion 2A, and the process returns to Step F50 to repeat the above.

  Note that the fritting voltage is about 1 to 20 V and at most 100 V or less. For this reason, this is different from the discharge phenomenon that occurs when a voltage of several kV is applied as in the case of breaking the insulating film described in the prior art. The pressing force of the conductive needles 20A and 20B is about 1 g. For this reason, the lifetime of the conductive needles 20A and 20B can be extended as compared with the conventional case.

  The conductive needles 20A and 20B used in the present embodiment are made of any one of conductive diamond, tungsten carbide, tungsten, palladium, iridium, and beryllium-copper alloy.

  Accordingly, when the wafer is removed from the chuck, the potential applied to the electrostatic chuck electrode 5 by the electrostatic chuck power supply 10B is set to the reference potential GND, thereby preventing the wafer from being lifted and misaligned. And the residual charge can be reduced as much as possible.

  As described above, according to the present embodiment, good chucking can be performed without damaging the semiconductor device formed on the wafer 100.

  In the first embodiment, one end of the power supplies 12, 14a, 14b is connected to the reference potential GND and one end of the conduction needle 20 is connected to the reference potential GND via the ammeter 28. As shown in FIG. 15, the power supply 29 may be grounded.

  The chucking apparatus according to the first and second embodiments can be used as a chucking apparatus for a vacuum apparatus or an electron beam drawing apparatus used in a semiconductor manufacturing apparatus. In particular, when used in an electron beam drawing apparatus, the chucking apparatus according to the above embodiment can reduce the residual charge of the wafer, and thus it is possible to prevent positional deviation during electron beam irradiation. Accurate electron beam irradiation can be performed.

  As described above, according to the present invention, it is possible to prevent the wafer from being lifted and misaligned when ensuring electrical continuity from the back surface of the wafer. In addition, the residual charge can be reduced as much as possible when the wafer is removed from the chuck.

2 Electrostatic chuck part 2A Electrostatic chuck part 4 First electrode 5 Electrostatic chuck electrode 6 Second electrode 8 Insulator part 9 Through hole 9A Through hole 9B Through hole 10 Voltage controller 10B Power supply for electrostatic chuck 12 Power supply 13 Switch 14a Power supply 14b Power supply 16a Switch 16b Switch 20 Conductive needle 20A Conductive needle 20B Conductive needle 24 Conductive needle drive mechanism 26 Wiring 28 Ammeter 40 Conductive needle drive mechanism 60 Fritting voltage application device

Claims (10)

An electrostatic chuck mechanism comprising a plurality of electrodes each configured to be capable of independently supplying power, and configured to electrostatically attract a substrate to be processed;
A conduction mechanism configured to be in electrical communication with at least the back surface of the substrate to be processed and electrically connected to the substrate to be processed;
A control mechanism for controlling power to be applied to an electrode different from the electrode on the conduction mechanism side after supplying power to the electrode on the conduction mechanism side of the plurality of electrodes;
An electron beam drawing apparatus comprising: an electron beam irradiation mechanism that irradiates the substrate to be processed with an electron beam to perform a predetermined process. An electrostatic chuck mechanism comprising a plurality of electrodes each configured to be capable of independently supplying power, and configured to electrostatically attract a substrate to be processed;
A conduction mechanism configured to be in electrical communication with at least the back surface of the substrate to be processed and electrically connected to the substrate to be processed;
A control mechanism for controlling power to be applied to an electrode different from the electrode on the conduction mechanism side after supplying power only to the electrode closest to the conduction mechanism side of the plurality of electrodes;
An electron beam drawing apparatus comprising: an electron beam irradiation mechanism that irradiates the substrate to be processed with an electron beam to perform a predetermined process. An electrostatic chuck mechanism comprising a plurality of electrodes each configured to be capable of independently supplying power, and configured to electrostatically attract a substrate to be processed;
A conduction mechanism configured to be in electrical communication with at least the back surface of the substrate to be processed and electrically connected to the substrate to be processed;
Control is performed so that power is supplied to an electrode different from the electrode on the conduction mechanism side after power is supplied to the electrode on the conduction mechanism side of the plurality of electrodes to electrically connect the conduction mechanism and the substrate to be processed. A control mechanism;
An electron beam drawing apparatus comprising: an electron beam irradiation mechanism that irradiates the substrate to be processed with an electron beam to perform a predetermined process. An electrostatic chuck mechanism comprising a plurality of electrodes each configured to be capable of independently supplying power, and configured to electrostatically attract a substrate to be processed;
A conduction mechanism configured to be in electrical communication with at least the back surface of the substrate to be processed and electrically connected to the substrate to be processed;
After supplying electric power of the same polarity to the plurality of electrodes to electrically connect the conduction mechanism and the substrate to be processed, electric power having a polarity different from the same polarity is applied to an electrode different from the electrode on the conduction mechanism side. A control mechanism for controlling
An electron beam drawing apparatus comprising: an electron beam irradiation mechanism that irradiates the substrate to be processed with an electron beam to perform a predetermined process.   5. The electron beam according to claim 1, further comprising a detection mechanism that detects the flatness of the substrate to be processed that is electrostatically attracted and held by the electrostatic chuck mechanism. Drawing device. An electron beam drawing method for performing a predetermined process by irradiating an electron beam to a substrate to be electrostatically held by holding,
Electrostatically adsorbing a partial area of the back surface of the substrate to be processed;
Contacting a conduction mechanism that is electrically conductive with the substrate to be processed from the back surface of the substrate to be processed;
A step of electrostatically adsorbing a region different from a partial region of the back surface of the substrate to be processed;
An electron beam drawing method comprising: An electron beam drawing method for performing a predetermined process by irradiating an electron beam to a substrate to be electrostatically held by holding,
Electrostatically adsorbing the first region of the back surface of the substrate to be processed;
Contacting a conduction mechanism that is electrically conductive with the substrate to be processed from the back surface of the substrate to be processed;
Electrostatically adsorbing a second region different from the first region on the back surface of the substrate to be processed;
Thereafter, a step of detecting the flatness of the substrate to be processed;
An electron beam drawing method comprising: An electron beam drawing method for performing a predetermined process by irradiating an electron beam to a substrate to be electrostatically held by holding,
Electrostatically adsorbing a first region of the back surface of the substrate to be processed close to the contact position before contacting a conduction mechanism that is electrically connected to the substrate to be processed from the back surface of the substrate to be processed;
Contacting a conduction mechanism that is electrically conductive with the substrate to be processed from the back surface of the substrate to be processed;
Electrostatically adsorbing a second region different from the first region on the back surface of the substrate to be processed;
Thereafter, a step of detecting the flatness of the substrate to be processed;
An electron beam drawing method comprising: An electron beam drawing method for performing a predetermined process by irradiating an electron beam to a substrate to be electrostatically held by holding,
A step of electrostatically adsorbing the back surface of the substrate to be processed at a plurality of locations with electric power of the same polarity;
Contacting a conduction mechanism that is electrically conductive with the substrate to be processed from the back surface of the substrate to be processed;
A step of electrostatically attracting the back surface of the substrate to be processed partially with electric power having the same polarity and a plurality of polarities different from the same polarity;
An electron beam drawing method comprising:   The electron beam drawing method according to claim 6, further comprising a step of detecting the flatness of the substrate to be processed after the substrate to be processed is adsorbed.

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