JP4010541B2 - Electrostatic adsorption device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic adsorption device, and more particularly to an electrostatic adsorption device for fixing a substrate in a substrate processing chamber in a semiconductor manufacturing process.
[0002]
[Prior art]
In recent years, electrostatic adsorption devices are frequently used to fix a substrate in substrate processing such as thin film formation (sputtering, CVD, etc.) or thin film processing (dry etching, etc.) on a substrate in a semiconductor manufacturing process. Substrate fixing by electrostatic attraction does not have a portion in contact with the substrate surface, so that the device extraction rate from the substrate surface is high and the yield of device production can be increased. Furthermore, precise temperature control is possible based on the combination with the temperature adjustment unit.
[0003]
A configuration example of a conventional electrostatic attraction apparatus will be described with reference to FIG. This electrostatic adsorption apparatus is applied to a sputtering apparatus as an example. In this sputtering apparatus, the inside of the metal container 11 is depressurized by an exhaust mechanism (not shown). A disk-shaped target 13 supported by a ring-shaped insulating member 12 is attached to the ceiling portion of the container 11. A magnet 15 fixed to the yoke plate 14 is installed outside the container 11 and on the back surface of the target 13. A substrate support 16 is provided below the inside of the container 11. A substrate 17 is mounted on the upper surface of the substrate support 16. The substrate 17 is disposed in parallel to the target 13 so as to face the target 13. The substrate support 16 is fixed to the bottom of the container 11. The substrate support unit 16 includes an electrostatic adsorption device 18 and a substrate temperature adjustment unit 19. A cylindrical shield 20 is disposed on the inner surface of the peripheral wall of the container 11.
[0004]
The electrostatic attraction device 18 includes a dielectric plate 22 having an embossed portion 21 formed on the surface thereof by embossing, and a metal electrode 23 disposed therein. The metal electrode 23 has a bipolar electrode structure, for example, and includes an inner electrode 23a and an outer electrode 23b. The metal electrode 23 is connected to the external DC power supply circuit 24 and is applied with a constant voltage. The external DC power supply circuit 24 is provided with a battery 24a for applying a positive voltage, a battery 24b for applying a negative voltage, a ground terminal 24c, and switches 24d and 24e. A positive voltage is applied to the inner electrode 23a by the battery 24a, and a negative voltage is applied to the outer electrode 23b by the battery 24b. The substrate 17 is fixed on the substrate support 16 when the substrate 17 is placed on the dielectric plate 22 and a predetermined voltage is applied to the metal electrode 23, the metal electrode 23 and the substrate (silicon substrate) 17 are fixed. It is performed by Coulomb force (electrostatic force) working between them. The Coulomb force is generated based on the charge induced on the surface of the dielectric plate 22. The substrate 17 is attracted to the surface of the dielectric plate 22 by this Coulomb force.
[0005]
The substrate temperature adjusting unit 19 is provided below the electrostatic adsorption device 18. The substrate temperature adjusting unit 19 includes a thermocouple 25, a power source / control mechanism 26, and a heating / cooling unit 27. The heating / cooling unit 27 controlled to a required constant temperature by the thermocouple 25 and the power source / control mechanism 26 holds the dielectric plate 22 provided thereon at a constant temperature. The temperature of the substrate 17 placed on the embossed portion 21 of the dielectric plate 22 is such that gas is introduced into the gap 21a formed by the embossed portion 21 by the gas supply source 28 and the gas introduction path 29, and the inside of the gap 21a is maintained. When held at a constant pressure, it is held at a predetermined temperature by the heat conduction of the gas.
[0006]
When the substrate 17 is fixed by the electrostatic adsorption device 18, the adsorption force needs to be sufficiently larger than the reaction force due to the differential pressure between the pressure of the gap 21 a and the internal pressure of the container 11. A typical sputtering pressure is a few millitorr (mTorr). Therefore, the value of the pressure difference is almost the pressure in the gap 21a. In this case, the pressure difference is about 10 Torr.
[0007]
The force that attracts the substrate 17 is a Coulomb force that acts between the surface of the dielectric plate 22 and the substrate 17. The Coulomb force will be described with reference to FIGS.
[0008]
The substrate 17 is placed on the embossed portion 21 of the dielectric plate 22. As shown in FIG. 8, when a positive voltage is applied to the metal electrode 23 (inner electrode 23a) by the battery 24a, a positive charge is induced on the surface of the dielectric plate 22, but at the same time, a negative charge is also applied to the back surface of the substrate 17. Is induced.
[0009]
When the metal electrode is a unipolar electrode, the substrate 17 is connected to the power supply grounding part via plasma, and a closed circuit is formed. When the metal electrode is a bipolar electrode, electric charges appear on the surface of the dielectric plate 22 corresponding to the internal and external electrode voltages with different signs. By forming a closed circuit through the back surface of the substrate 17, charges are induced on the back surface of the substrate 17.
[0010]
  The force (F) acting between the surface of the dielectric plate 22 and the substrate 17 is F = ε (V²/ L²) A / 2, F = ε (V for bipolar electrodes²/ L²) A / 8 (when the electrode area is the same for the plus electrode and the minus electrode). Here, ε is the dielectric constant of the gap 21a, V is the voltage, L is the distance between the dielectric plate and the substrate back surface (silicon substrate back surface), and A is the electrode area. Adsorption power is the applied voltageSquareIs proportional to the electrode area and the distance between the substrate and the dielectric plate.SquareInversely proportional to In sputtering, since it is necessary to heat the substrate and maintain it at a constant temperature before film formation, a bipolar electrode is usually used.
[0011]
On the other hand, in the convex portion 21b of the embossed portion 21 where the substrate 17 and the dielectric plate 22 are in direct contact with each other, as shown in FIG. A gap 30 (gap distance δ) is generated. Since the distance δ of the gap 30 is very small and about 0.1 μm, the force generated across the gap 30 is very large. This is called the Johnson Rabeck effect (JR effect).
[0012]
Calculate the adsorption force for the case of bipolar electrodes. When a substrate having a diameter of 300 mm is processed, the dielectric plate 22 has a diameter of 300 mm, and the substrate is brought into contact with and supported by the outer peripheral edge 1 mm of the dielectric plate 22 and the embossed protrusions. The surface area of this contact portion is 1% of the horizontal area of the total dielectric plate. The metal electrode 23 is a bipolar electrode divided into a circular shape on the inside and a ring shape on the outside. The metal electrode 23 is a disk having a diameter of 298 mm in calculation. The applied voltage to the metal electrode is + 200V for the plus electrode and -200V for the minus electrode. The emboss gap (the step between the convex portion and the concave portion) corresponding to the distance L between the substrate 17 and the dielectric plate 22 is 7 μm, and the fine gap δ at the contact portion of the embossed convex portion 21b with the substrate is 0.1 μm. Further, the attractive force acts only in the direction perpendicular to the surface of the dielectric plate.
[0013]
The force acting on the concave portion of the embossed portion 21 is 500 to 600 N, the force acting on the convex portion 21 b is 5000 to 10000 N, and the total is 5500 to 10600 N. The force acting on the embossed convex portion 21b is very large and is important for control. The total of these forces is applied to the entire substrate, but the force per unit area, that is, the pressure is 500 to 1000 Torr. Since this pressure is sufficiently larger than the reaction force due to the differential pressure between the pressure in the gap between the substrate 17 and the dielectric plate 22 and the internal pressure of the container 11, the substrate 17 is stably adsorbed on the dielectric plate 22. Fixed.
[0014]
Next, the sputtering process of the substrate 17 in the container 11 of the sputtering apparatus will be described.
[0015]
The substrate 17 is carried into the container 11 and placed on the dielectric plate 22 of the substrate support 16. The substrate 17 is transferred by a transfer robot and lift pins (not shown). Next, it operates from the external DC power supply circuit 24, and a predetermined voltage is applied to the electrode 23. In this example, + 200V is applied to the inner electrode 23a and -200V is applied to the outer electrode 23b. The same voltage as an absolute value is applied to the inner electrode 23a and the outer electrode 23b. When a voltage is applied to the electrode 23, the substrate 17 is attracted and fixed to the dielectric plate 22 by electrostatic force as described above. When the substrate 17 is fixed, gas is introduced from the gas supply source 28 through the gas introduction path 29 into the gap 21 a formed between the substrate 17 and the dielectric plate 22. The pressure in the gap 21a is controlled to a certain constant pressure in the range of 1 to 10 Torr. With this gas, heat is transferred from the dielectric plate 22 held at a constant temperature by the substrate temperature adjusting unit 19 to the substrate 17. As a result, the substrate 17 is also heated and held at a constant temperature. When the substrate temperature becomes constant, Ar gas is introduced into the container 11 and the pressure in the container 11 is maintained at a constant pressure. Next, a high voltage is applied from the sputtering power supply 31 to the target 13 facing the substrate 17, and a discharge is generated inside the container 11, and a desired thin film is formed on the substrate 17 by the sputtering action on the target 13. After film formation, gas introduction into the container 11 and gas supply to the gap 21a are stopped. After the pressure is sufficiently reduced, the voltage application to the electrode 23 is stopped. Next, the substrate 17 is separated from the embossed portion 21 of the dielectric plate 22 by lift pins (not shown), and the substrate 17 is carried out of the container 11 by a transfer robot (not shown).
[0016]
[Problems to be solved by the invention]
In the conventional electrostatic attraction apparatus described above, since the attraction force of the embossed portion 21 of the dielectric plate 22 is set strongly, the back surface of the substrate 17 and the dielectric plate 22 rub against each other when the attraction starts, etc. A problem arises in that a large amount of particles are scraped off and become a source of dust generation, causing a decrease in yield. In order to solve this problem, the area of the substrate contact portion of the embossed protrusion 21b may be reduced. However, since it has a role as a support for supporting a curved substrate, there is a limit to area reduction.
[0017]
Furthermore, since the charge induced on the surface of the dielectric plate 22 remains even after the substrate 17 is processed and the voltage applied to the metal electrode 23 is lost, the attractive force does not disappear immediately. Therefore, when the substrate 17 is to be separated from the dielectric plate 22 with a lift pin for the purpose of transporting the substrate 17 out of the container 11, the substrate causes a position shift due to vibration or the like. As a result, problems such as deterioration in distribution and inability to transport are caused in subsequent substrate processing, resulting in a decrease in yield or a reduction in apparatus operation rate.
[0018]
As a conventional technique related to the above problem, there is an electrostatic chuck disclosed in Japanese Patent Laid-Open No. 11-251416. In this electrostatic chuck, good detachability of the attracted member is realized.
[0019]
In view of the above problems, an object of the present invention is to provide an electrostatic adsorption device that reduces the generation of particles, easily and stably removes and conveys a substrate, and realizes a high yield and device operation rate.
[0020]
[Means and Actions for Solving the Problems]
In order to achieve the above object, an electrostatic chuck according to the present invention is configured as follows.
[0021]
  The first electrostatic adsorption device (corresponding to claim 1) is an electrostatic adsorption device including a dielectric plate whose surface is embossed, and an electrode layer formed in an embossed recess and a voltage applied to the electrode layer An external power supply to be in a grounded state or a grounded state, and a conductor layer formed on the substrate support surface of the embossed protrusionThe electrode layer has a bipolar electrode structure, and is composed of an inner disk-shaped electrode and an outer donut-shaped electrode, and each electrode has a plurality of through holes for penetrating the embossed protrusions. Installed on the entire embossed recess except for the gap between the inner disk-shaped electrode and the outer donut-shaped electrode.Configured as follows.
[0022]
The electrostatic adsorption apparatus is applied to a substrate processing apparatus such as a sputtering apparatus. The substrate fixed by the electrostatic adsorption device is a silicon substrate or the like. An embossed portion is formed on the surface of the dielectric plate by embossing. The embossed portion is formed with a convex portion, a concave portion, and an outer peripheral protrusion. When a voltage is applied to the electrode layer formed in the embossed recess, charge is induced on the back surface of the substrate. Since the portion in contact with the substrate is a conductor plate layer formed on the surface of the embossed convex portion, the contact portion has the same potential as the substrate and no electrostatic force is generated. Therefore, the generation of particles due to rubbing can be suppressed. A conductor layer is similarly formed on the surface of the outer peripheral protrusion. Said embossing convex part shall contain an outer periphery protrusion part notionally. In addition, when the electrode layer is grounded after the substrate processing, the induced charges can be rapidly released.
[0023]
In the first electrostatic adsorption device (corresponding to claim 2), the step formed between the electrode layer and the conductor layer is preferably included in the range of 5 to 30 μm in the first configuration. It is characterized by. The step is preferably a distance in the range of several μm to several tens of μm, but more preferably in the range of 5 to 30 μm.
[0025]
  First3Electrostatic adsorption device (claim)3In the first configuration described above, the range in which the conductor layer is formed is preferably inside the surface range of the embossed convex portion. With this configuration, the edge of the conductor layer and the edge of the electrode layer are prevented from being arranged on a straight line in the height direction.
[0026]
  First4Electrostatic adsorption device (claim)4In the first configuration described above, preferably, the area where the conductor layer is formed is inside the surface area of the embossed convex part, and the electrode layer is not formed around the embossed convex part. It is characterized by that. This configuration also prevents the edge of the conductor layer and the edge of the electrode layer from being arranged on a straight line in the height direction.
[0027]
  First5Electrostatic adsorption device (claim)5In the respective configurations described above, the material of the electrode layer and the conductor layer is preferably any one of tungsten, molybdenum, tantalum, and a carbon-based conductor.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
[0029]
The configurations, shapes, sizes, and arrangement relationships described in the embodiments are merely schematically shown to the extent that the present invention can be understood and implemented, and the numerical values and the composition (materials) of each component are illustrated. Only. Therefore, the present invention is not limited to the embodiments described below, and can be modified in various forms without departing from the scope of the technical idea shown in the claims.
[0030]
In this embodiment, an example of an electrostatic attraction apparatus applied to a sputtering apparatus as a substrate film forming apparatus will be described.
[0031]
The configuration of the sputtering apparatus will be outlined according to FIGS. The basic part of the configuration of the sputtering apparatus is the same as that of the conventional apparatus described with reference to FIG. The same elements as those described in FIG. 7 are denoted by the same reference numerals.
[0032]
The sputtering apparatus includes a container 11 whose inside is decompressed by an external exhaust mechanism (not shown), a target 13 provided on the ceiling of the container 11 via a ring-shaped insulating member 12, and a back surface side of the target 13. A magnet 15 provided and fixed to the yoke plate 14, a substrate support 16 installed at a position facing the target 13 and fixed to the bottom of the container 11, and an electrostatic chuck provided on the substrate support 16 18 and a substrate temperature adjusting unit 19. A voltage is applied to the target 13 from the sputtering power supply 31. A cylindrical shield member 20 is disposed along the inner surface of the peripheral wall of the container 11. In FIG. 1, illustration of a substrate transfer robot, a carry-in / carry-out gate, a lift pin for placing or removing the substrate 17 on the substrate support unit 16, a mechanism related to discharge generation, a discharge Ar gas introduction mechanism, and the like are omitted. Yes.
[0033]
The electrostatic attraction device 18 provided on the upper side of the substrate support 16 includes a dielectric plate 22 whose surface is embossed, an electrode layer 41 made of metal or the like provided on the surface of the dielectric plate 22, and an electrode layer 41. The external DC power supply circuit 24 applies a constant voltage to the external DC power supply circuit 24.
[0034]
  The embossed portion 21 on the surface of the dielectric plate 22 is composed of a plurality of convex portions 21b, concave portions 21c, and outer peripheral protrusion portions 21d. The convex portion 21b has a cylindrical shape. The outer peripheral protrusion 21d has a ring shape. The outer peripheral protrusion 21d is also conceptually included in the protrusion. A gap 21 a is formed on the back side of the substrate 17 by the embossed portion 21 of the dielectric plate 22. In the embossed portion 21 of the dielectric plate 22, a conductor layer 42 is provided on all tip surfaces (substrate support surfaces) of the plurality of convex portions 21 b. The material of the dielectric plate 22 is A with good thermal conductivity.lN (aluminum nitride) is used.
[0035]
The electrode layer 41 is disposed on the bottom surface of the recess 21 c of the embossed portion 21. The electrode layer 41 has a bipolar electrode structure, and is composed of a disk-shaped inner electrode layer 41a and a ring-shaped outer electrode layer 41b. The electrode layer 41 is made of a metal such as tungsten, molybdenum, or tantalum having a thermal expansion coefficient similar to that of the dielectric plate 22 or a carbon-based conductor.
[0036]
FIG. 3 is a plan view of the dielectric plate 22 and shows a formation pattern of the embossed protrusions 21 b and an arrangement pattern of the electrode layer 41. In FIG. 3, the diameter of the embossed convex portion 21b is drawn larger than the actual one so as to be easily understood. In FIG. 3, the region of the electrode layer 41 is indicated by hatching. The electrode layer 41 is composed of two parts, an inner disk electrode layer 41a and an outer donut electrode layer 41b. The electrode layer 41 is provided at the embossed recess 21 c on the surface of the dielectric plate 22. In addition, since the conductor layer 42 is formed on the embossing convex part 21b, the circular conductor layer 42 is shown in the place of the embossing convex part 21b in FIG. Furthermore, a ring-shaped outer peripheral protrusion 21d is formed on the outer edge portion of the dielectric plate 22, and a ring-shaped conductor layer 43 is also formed thereon.
[0037]
The electrode layer 41 is formed by ion plating or the like and has a thickness of about several μm to several tens of μm. The electrode layer 41 has good adhesion to the dielectric plate 22 and does not peel off when the temperature is raised or lowered. A direct current power source is connected to each of the electrode layers 41a and 41b through an external circuit. That is, the electrode layer 41 is connected to the external DC power supply circuit 24 and is applied with a constant voltage. The external DC power supply circuit 24 is provided with a battery 24a for applying a positive voltage, a battery 24b for applying a negative voltage, a ground terminal 24c, and switches 24d and 24e. A positive voltage is applied to the inner electrode layer 41a by the battery 24a, the switch 24d, and the conducting wire 43, and a minus voltage is applied to the outer electrode layer 41b by the battery 24b, the switch 24e, and the conducting wire 44. The electrode layers 41 a and 41 b are grounded by the ground terminal 24 c of the external DC power supply circuit 24.
[0038]
When a positive voltage from the battery 24a and a negative voltage from the battery 24b are applied to each of the inner electrode layer 41a and the outer electrode layer 41b, the surface of the embossing convex portion 21b of the dielectric plate 22 has a code corresponding to each electrode voltage. Charge appears.
[0039]
Since the electrode layer 41 is formed on the dielectric plate 22 by film formation, it is electrically insulated from the substrate temperature adjusting unit 19. Conductive wires 43 and 44 that form an electrical connection relationship with the external DC power supply circuit 24 are also electrically insulated from the temperature / temperature adjusting unit 19 and the container 11.
[0040]
As shown in FIG. 2 in an enlarged manner, a conductor layer 42 is formed on the tip surface of the embossed protrusion 21b. The conductor layer 42 is a metal having a thermal expansion coefficient similar to that of the dielectric plate 22, and may be tungsten, molybdenum, tantalum, or a carbon-based material other than the metal. The conductor layer 42 is electrically insulated from the electrode layer 41. The conductor layer 42 is similarly formed by ion plating or the like and has a thickness of about several μm to several tens of μm. It has good adhesion to the dielectric plate 22 and does not peel off even when the temperature rises or falls. The front end surface of the embossed convex portion 21 b is a portion that is in direct contact with the substrate 17. In addition to the embossed protrusion 21b, the conductor layer 42 is also formed on the surface of the ring-shaped outer peripheral protrusion 21d of the dielectric plate 22 that contacts the substrate 17.
[0041]
In order to insulate between the electrode layer 41 (41a, 41b) and the conductor layer 42, as shown in FIG. 4 and FIG. 5, the range in which the conductor layer 42 is formed is the tip surface area of the embossed protrusion 21b. It is desirable that the electrode layer is not formed near the periphery of the embossed step so that the region where the conductor layer 42 is formed is located inside the tip end surface range of the embossed convex portion 21b. That is, it is preferable that the edge portion of the electrode layer and the edge portion of the conductor layer are not arranged on a straight line in the height direction at a portion where a step is formed.
[0042]
The substrate temperature adjusting unit 19 includes a thermocouple 25, a power source / control mechanism 26, and a heating / cooling unit 27.
[0043]
A gas is introduced from a gas supply source 28 through a gas introduction path 29 into a gap 21 a formed between the dielectric plate 22 and the substrate 17. The pressure in the gap 51 is maintained at a constant pressure by the introduced gas. The substrate 17 is kept at a predetermined temperature by the heat conduction of the gas.
[0044]
The substrate processing by the sputtering apparatus according to the present embodiment is basically the same as the contents described in the conventional apparatus. In this embodiment, preferably, a voltage in the range of +200 to +1000 V is applied to the inner electrode layer 41a of the electrode layer 41, and a voltage in the range of −200 to −1000 V is applied to the outer electrode layer 41b. The same voltage as an absolute value is applied to the inner and outer electrode layers of the electrode layer 41 which is a bipolar electrode. When a voltage is applied to the electrode layers 41a and 41b, as shown in FIG. 6, a charge having a sign different from the sign of the electrode potential is induced on the back surface of the opposing substrate 17, and the substrate 17 is adsorbed by an electrostatic force, It is fixed on the dielectric plate 22.
[0045]
Next, the substrate adsorption action by the electrostatic adsorption device 18 will be described in detail with reference to FIG.
[0046]
When a substrate (for example, a silicon substrate) 17 is placed on the dielectric plate 22 and a predetermined voltage is applied to the inner and outer electrode layers 41a and 41b, the back surface of the substrate 17 has a potential corresponding to the potential of the corresponding electrode. As a result, the substrate 17 is fixed to the dielectric plate 22 by electrostatic force. Since the substrate 17 has a relatively low resistance, when a predetermined voltage is applied to the inner and outer electrode layers 41a and 41b, the current easily moves near the back surface of the substrate 17, and the back surface portion of the substrate facing the plus electrode layer Thus, a negative charge is generated, and a positive charge is generated on the back side of the substrate facing the negative electrode layer. The potential of the substrate is almost the same as the potential of the electrode layer 41. When charge transfer occurs on the back surface of the substrate 17, a closed circuit is formed between the power supply circuit 24 and the substrate 17, and charge flow occurs in this closed circuit.
[0047]
On the other hand, the tip surface of the embossed convex portion 21b is in contact with the back surface of the substrate 17, but the conductor layer 42 of the convex portion 21b has the same potential as the back surface portion of the substrate 17 that is in contact. Accordingly, no electrostatic force is generated between the surface of the embossed convex portion 21b and the substrate 17, and the electrostatic force does not work. For this reason, the Johnson-Rahbek effect on the embossed surface, which is the contact portion between the substrate 17 and the embossed portion 21 of the dielectric plate 22, does not occur and a strong force does not work, so that the generation of particles due to rubbing is very small.
[0048]
Here, the conductor layer 42 on the tip surface of the embossed convex portion 21b has substantially the same potential as the substrate 17 (negative potential in FIG. 6), but the interface with the dielectric plate 22 below (the embossed convex portion of the embossed convex portion). Due to the presence of charges of the opposite sign (plus charge in FIG. 6) induced on the dielectric plate side of the interface with the tip surface, the electric field moves and disappears at the interface, and the Johnson-Rahbek effect at the interface. There is power. However, the phenomenon occurring at this interface is not related to the adsorption of the substrate.
[0049]
The force for adsorbing the substrate 17 in this embodiment is calculated. As described above, the working force is F = ε (V²/ L₀ ²) A₀/ 8 (when the area of the electrode layer is the same for the plus electrode layer and the minus electrode layer). Where ε is the dielectric constant, V is the voltage, and L₀Is the distance between the front surface of the electrode layer and the back surface of the substrate, A₀Is approximately the area of the electrode layer 41. The attractive force is proportional to the square of the applied voltage and the electrode area, and inversely proportional to the square of the distance between the substrate and the dielectric plate surface.
[0050]
When a substrate having a diameter of 300 mm is processed, the dielectric plate 22 serving as a substrate support has a diameter of 300 mm, the electrode layer 41 has an area of 298 mm in diameter, an outer peripheral protrusion having a width of 1 mm, and an embossed protrusion having a diameter of 1 mm. Is assumed to be 1% of the total area as it contacts the substrate.
[0051]
The force acting when the applied voltage is 200 to 500 V is 500 to 3200 N, and the pressure is 60 to 370 Torr. The reaction force due to the pressure difference between the pressure generated by introducing the gas into the gap 21 a and the internal pressure of the container 11 is obtained. Adequately enough, stable adsorption can be achieved.
[0052]
However, the surface of the substrate is SiO₂In the case where it is covered with, the movement of electric charge is Si0 at the substrate contact portion.₂It is rate-controlled by the charge transfer of the layer and is not as easy as with the Si substrate alone. In addition, since the substrate and the dielectric plate are unlikely to have the same potential at the embossed portion, this calculation is not necessarily accurate. However, since the charge transfer does not occur unlike the case of contact between dielectrics, the attractive force at the embossed portion is reduced as compared with the conventional case.
[0053]
After the processing of the substrate 17 is finished, the voltage application to the electrode layer 41 is stopped, and the electrode layer 41 is connected to the ground portion 24c by the changeover switches 24d and 24e of the external circuit. When the electrode 41 reaches the ground potential, the charge separation caused by electrostatic induction is eliminated in the opposing substrate 17, and the charge induced on the back surface of the substrate disappears. As a result, the electrostatic force working between the electrode layer 41 and the substrate 17 rapidly decreases, and the adsorption force disappears.
[0054]
However, since the charges induced in the dielectric plate portion on the surface of the convex portion 21b of the embossed portion 21 remain, charges with different signs remain on the back surface portion of the substrate near the convex portion 21b. However, since the conductor layer 42 formed on the surface of the embossed protrusion 21b is almost at the same potential as that of the substrate 17, no electrostatic force acts between the substrate and the dielectric plate, and no attracting force is generated. Adsorption force does not occur between the substrate and the dielectric plate due to the residual charge of the portion.
[0055]
As described above, the substrate adsorption force instantaneously declines after the voltage application to the inner and outer electrode layers 41a and 41b is stopped, and the adsorption force due to the residual charge does not continue for a long time. Therefore, even if the unloading of the substrate is started immediately after the voltage application to the metal electrode 42 is stopped, the substrate will not vibrate and will not be displaced.
[0056]
According to the electrostatic attraction apparatus according to the present invention, when experimentally inspected, conventionally, about 50,000 particles were generated on the back surface when processing a substrate having a diameter of 300 mm, but about 5,000 or less. Declined. This greatly improved the production yield.
[0057]
The electrostatic attraction apparatus according to the present embodiment described above can be applied to CVD (chemical vapor deposition) for forming a thin film on a substrate and dry etching for processing a thin film in addition to sputtering. Further, although the bipolar electrode has been described in the present embodiment, the present invention can be similarly applied to a monopolar electrode.
[0058]
【The invention's effect】
As is apparent from the above description, according to the present invention, an electrode layer is formed on the surface of an embossed recess in an electrostatic chucking device that holds and fixes a substrate with a Coulomb force between the embossed surface of the dielectric plate and the backside of the substrate. In addition, since the conductor layer is formed on the tip surfaces of the plurality of embossed convex portions, the contact portion with the substrate is kept at the same potential, and a strong force does not act on the contact portion between the substrate and the dielectric plate, thus rubbing. Particle generation due to can be suppressed. After the substrate processing is completed, the adsorption force can be instantly reduced after the voltage application is stopped, and the substrate can be taken out and transported stably. This makes it possible to perform substrate processing with a high yield and a high operating rate.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a sputtering apparatus to which an electrostatic attraction apparatus according to the present invention is applied.
FIG. 2 is an enlarged vertical sectional view showing a contact state between an embossed portion of a dielectric plate and a substrate.
FIG. 3 is a plan view showing an arrangement pattern of embossed portions and electrode layers of a dielectric plate.
FIG. 4 is an enlarged longitudinal sectional view showing another example of a contact state between an embossed portion of a dielectric plate and a substrate.
FIG. 5 is an enlarged longitudinal sectional view showing a state where the substrate is separated in another example of the contact state between the embossed portion of the dielectric plate and the substrate.
FIG. 6 is an enlarged longitudinal sectional view showing an applied voltage and an induced charge in a contact state between an embossed surface of a dielectric plate and a substrate.
FIG. 7 is a longitudinal sectional view showing a sputtering apparatus equipped with a conventional electrostatic attraction apparatus.
FIG. 8 is a partially enlarged longitudinal sectional view for explaining a contact relationship between an embossed portion with a dielectric plate and a substrate.
FIG. 9 is a partially enlarged longitudinal sectional view for explaining a contact relationship between an embossed convex portion and a substrate.
[Explanation of symbols]
11 containers
13 Target
15 Magnet
16 Substrate support
17 Substrate
18 Electrostatic adsorption device
19 Substrate temperature adjustment unit
21 Embossing
21b Convex part
21c recess
21d Outer peripheral edge protrusion
22 Dielectric plate
41 Electrode layer
42 Conductor layer

Claims (5)

In an electrostatic attraction apparatus including a dielectric plate whose surface is embossed, an electrode layer formed in an embossed recess, an external power source that makes the electrode layer in a voltage application state or a ground state, and a substrate support surface of the embossed protrusion The electrode layer has a bipolar electrode structure, and is composed of an inner disk-shaped electrode and an outer donut-shaped electrode, and each electrode has the embossed convex portion. Electrostatic adsorption characterized by having a plurality of through-holes for penetrating and being installed over the entire embossed recess except for the gap between the inner disk-shaped electrode and the outer donut-shaped electrode apparatus.   The electrostatic attraction apparatus according to claim 1, wherein a step formed between the electrode layer and the conductor layer is included in a range of 5 to 30 μm.   The electrostatic attraction apparatus according to claim 1, wherein a range in which the conductor layer is formed is inside a surface range of the embossed convex portion.   2. The electrostatic adsorption according to claim 1, wherein a range in which the conductor layer is formed is inside a surface range of the embossed convex portion, and the electrode layer is not formed around the embossed convex portion. apparatus. The material of the said electrode layer and the said conductor layer is any one of tungsten, molybdenum, a tantalum, and a carbon-type conductor, The electrostatic attraction apparatus of any one of Claims 1-4 characterized by the above-mentioned.

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