JP5225043B2 - Electrostatic chuck - Google Patents

Description

  The present invention relates to an electrostatic chuck used for a semiconductor manufacturing apparatus or the like and a method for electrostatically attracting an object to be held.

  In a semiconductor device manufacturing process, a fixing method using an electrostatic chuck is employed as a method for fixing a semiconductor wafer when etching or film formation is performed on the semiconductor wafer. As a form of this electrostatic chuck, for example, there is one in which an adsorption electrode is embedded in a plate-like body made of insulating ceramics.

There are two types of wafer chucking force in the electrostatic chuck, one using the Coulomb force and the other using the Johnson-Rahbek force. It is known that the Coulomb force depends on the dielectric constant of the material constituting the dielectric layer, and the Johnson-Rahbek force depends on the volume specific resistance value of the material constituting the dielectric layer. Specifically, the adsorption force when the volume resistivity of the dielectric layer is greater than 10 ¹⁵ Ω · cm is governed by the Coulomb force, and the Johnson-Rahbek force increases as the volume resistivity of the dielectric layer decreases. When expressed and the volume resistivity value of the dielectric layer is less than 10 ¹¹ Ω · cm, the adsorption force is governed by the Johnson-Rahbek force that provides a larger adsorption force than the Coulomb force.

As a ceramic as a dielectric material having a low volume resistivity value that expresses the Johnson Rahbek force, for example, an aluminum nitride ceramic that is an electrically insulating ceramic material, and CeAlO ₃ exhibiting conductivity at its grain boundary. Some have a continuous phase. This aluminum nitride ceramic can conduct through grain boundaries and has a low volume resistivity.

Furthermore, an electrostatic chuck made of an aluminum nitride ceramic that expresses a Johnson-Rahbek force in a manufacturing process of a semiconductor device is used as follows, for example, in a sputtering apparatus. A semiconductor wafer is placed on an electrostatic chuck attached to the sputtering apparatus, an adsorption voltage is applied to the electrostatic chuck, the semiconductor wafer is fixed, and a sputtering process is performed. The initial applied voltage is maintained as it is during the sputtering process. Thereafter, when the sputtering process is completed, the application of the chucking voltage of the electrostatic chuck is released, and the semiconductor wafer is detached from the electrostatic chuck. In the semiconductor device manufacturing process, the adsorption of the semiconductor wafer to the electrostatic chuck and the removal of the semiconductor wafer from the electrostatic chuck are frequently repeated.
JP 11-100271 A

  However, the dielectric layer between the semiconductor wafer and the attracting electrode inside the electrostatic chuck is subject to dielectric breakdown by applying a high voltage for a long time during the sputtering process, and the sputtering process is interrupted. The electrostatic chuck has to be replaced. Further, when the sputtering process is interrupted, there is a problem that the semiconductor wafer becomes defective.

  Accordingly, the present invention has been completed in view of the above-mentioned conventional problems, and its purpose is that dielectric breakdown occurs when a high voltage is applied to the dielectric layer of the electrostatic chuck for a long time. Provided are an electrostatic chuck capable of improving durability, achieving energy saving by suppressing significantly, and further suppressing occurrence of ion migration between terminals, and an electrostatic chucking method of an object to be held. That is.

An electrostatic chuck according to the present invention comprises a static dielectric comprising a ceramic dielectric layer having an adsorption surface for an object to be held and an adsorption electrode to which a voltage for electrostatic adsorption of the object to be held is applied. In the electric chuck, the ceramic dielectric layer is made of an aluminum nitride ceramic, in which aluminum nitride particles lacking nitrogen are scattered and applied to the adsorption electrode. The volume resistivity when the voltage is 500V is 5 × 10
The volume resistivity when the voltage is ^{8 to} 5 × 10 ¹⁰ Ω · cm and the voltage is 10 V is 5 × 10 ^{10 to} 5 × 10 ¹² Ω · cm and the voltage is 500 V. Resistance value of 3
It is characterized by being more than twice.

  The electrostatic chuck of the present invention is characterized in that, in the above configuration, the aluminum nitride ceramic is an aluminum nitride ceramic containing a sintering aid.

  The electrostatic chuck of the present invention is characterized in that, in the above configuration, the sintering aid contains cerium oxide or yttria.

According to the electrostatic chuck of the present invention, a ceramic dielectric layer having an adsorption surface for an object to be held is provided on a substrate, and an adsorption electrode to which a voltage for electrostatic adsorption of the object to be held is applied. The ceramic dielectric layer is made of an aluminum nitride ceramic, in which aluminum nitride particles lacking nitrogen are scattered, and when the voltage applied to the adsorption electrode is 500 V When the volume resistivity is 5 × 10 ^{8 to} 5 × 10 ¹⁰ Ω · cm and the voltage is 10 V, the volume resistivity is 5 × 10 ^{10 to} 5 × 10 ¹² Ω · cm and the voltage is Since it is more than 3 times the volume resistivity value at 500V, the voltage applied to the electrode for adsorption is set to 500V at the time of wafer adsorption. Do Doo is possible, as a result, it is possible to significantly shorten the time to apply a high voltage. That is, a high voltage must be applied at the time of wafer adsorption, but even if the voltage is lowered thereafter, the volume resistivity value increases, so that the charge accumulated in the ceramic dielectric layer is difficult to escape, so the polarization of the ceramic dielectric layer It becomes easy to maintain the state, and it is possible to maintain the attractive force to the wafer even if the voltage is lowered. In addition, since aluminum nitride particles lacking nitrogen in aluminum nitride particles are scattered in aluminum nitride ceramics, the conductivity when high voltage is applied is improved. As a result, the volume resistivity of aluminum nitride ceramics The value can be controlled by the oxygen content.

  Therefore, it is possible to reduce the load on the ceramic dielectric layer by applying a high voltage for a long time, and to effectively suppress the dielectric breakdown of the ceramic dielectric layer, and it can be used stably for a long time. A highly durable electrostatic chuck can be obtained.

  Further, energy saving can be achieved because it is not necessary to apply a high voltage for a long time.

  Furthermore, since it is not necessary to apply a high voltage for a long time, the occurrence of ion migration between terminals can be suppressed.

  In the electrostatic chuck of the present invention, in the above configuration, when the aluminum nitride ceramic is an aluminum nitride ceramic containing a sintering aid, the volume resistivity of the ceramic dielectric layer is added by adding the sintering aid. It becomes easy to control.

  In the electrostatic chuck of the present invention, when the sintering aid contains cerium oxide or yttria in the above configuration, the ceramic dielectric layer has high thermal conductivity. The temperature of the electric chuck quickly reaches the set temperature, the controllability by voltage application is enhanced, and voltage control with less waste is possible.

  Below, the example of embodiment of the electrostatic chuck of this invention is demonstrated in detail.

  FIG. 1 shows an example of an embodiment of an electrostatic chuck. 1 is a plate-like body that is a main body of the electrostatic chuck 10, 1a is a ceramic dielectric layer, 1b is a substrate, 2 is an adsorption electrode, 3 Is a suction surface, 4 is a terminal for applying a voltage, 5 is a wafer to be held, 6 is a gas introduction hole for introducing a cooling gas such as helium gas, and 7 is a groove for cooling the wafer.

The electrostatic chuck 10 according to the present embodiment includes a ceramic dielectric layer 1a having an attracting surface 3 for an object to be held on a substrate 1b, and an attracting electrode to which a voltage for electrostatic attraction of the object to be held is applied. The ceramic dielectric layer 1a is made of aluminum nitride ceramics, and has a volume resistivity of 5 × 10 ^{8 to} 5 × 10 ¹⁰ Ω · when the voltage applied to the adsorption electrode 2 is 500V. The volume resistivity value when the voltage is 10 V and the voltage is 10 V is 5 × 10 ^{10 to} 5 × 10 ¹² Ω · cm, and is 3 times or more the volume resistivity value when the voltage is 500 V.

  With such a configuration, the voltage applied to the adsorption electrode 2 is set to, for example, 500 V when the wafer 5 is adsorbed, and once adsorbed and fixed, the adsorbed and fixed wafer 5 can be maintained even if the voltage is lowered. As a result, the time for applying the high voltage can be remarkably shortened. That is, a high voltage must be applied when the wafer 5 is attracted, but even if the voltage is lowered thereafter, the volume specific resistance value increases, so that the charges accumulated in the ceramic dielectric layer 1a are difficult to escape. It becomes easy to maintain the polarization state of 1a, and it is possible to maintain the attracting force with respect to the wafer 5 even if the voltage is lowered.

  As will be described later, the volume resistivity of the ceramic dielectric layer 1a made of an aluminum nitride ceramic is controlled by 1) including a sintering aid in the aluminum nitride ceramic, and 2) firing a small amount of oxygen in the firing process. It can be performed by such means as introduction into the furnace.

  The electrostatic chuck 10 of this example can be changed in shape and size in accordance with the size of the wafer 5 and the apparatus using the electrostatic chuck 10, and the main body of the plate-like body 1 provided with the attracting electrode 2. The surface is the suction surface 3 of the wafer 5.

  The plate-like body 1 has a disk shape or the like, and includes a ceramic dielectric layer 1a on the adsorption surface 3 side, and a base 1b formed integrally with the ceramic dielectric layer 1a. A planar adsorption electrode 2 is embedded between the ceramic dielectric layer 1a and the substrate 1b inside the plate-like body 1. Furthermore, a terminal 4 for applying a voltage by being electrically connected to the adsorption electrode 2 is connected to the adsorption electrode 2 and led out to the substrate 1b. Then, the wafer 5 is electrostatically adsorbed to the adsorption surface 3 of the plate-like body 1 by applying a voltage from the terminal 4 to the adsorption electrode 2.

  The adsorption electrode 2 is an electrode made of a high melting point metal such as Mo or W, for example, a bulk metal such as a mesh or a single plate, or a thick film metal formed by printing and baking a metal paste. It will be. When the adsorption electrode 2 is made of a bulk metal embedded in the plate-like body 1, the adsorption electrode 2 can be used as a high-frequency electrode used in a high-frequency sputtering method, a plasma CVD method, or a plasma etching method.

  The plate-like body 1 is provided with a gas introduction hole 6 for introducing a cooling gas such as He gas and a groove 7 for cooling the wafer by circulating the cooling gas. By flowing a cooling gas from the gas introduction hole 6 to the groove 7, the wafer 5 whose temperature has been increased by etching or the like can be cooled.

The ceramic dielectric layer 1a is made of an aluminum nitride ceramic, and has a volume resistivity value of 5 × 10 ^{8 to} 5 × 10 ¹⁰ Ω · cm when the voltage applied to the adsorption electrode 2 is 500 V, and the voltage The volume resistivity value when the voltage is 10 V is 5 × 10 ^{10 to} 5 × 10 ¹² Ω · cm and is more than three times the volume resistivity value when the voltage is 500 V, but the volume resistivity value is 5 By setting it to 10 ⁸ Ω · cm or more, the leakage current can be reduced, and adverse effects on the object to be held can be suppressed. In addition, by setting the volume resistivity to 5 × 10 ¹² Ω · cm or less, it is possible to reduce the influence of the Coulomb force and suppress the decrease in the adsorption force.

  Further, by setting the volume resistivity value at 10V to 3 times or more of the volume resistivity value at a voltage of 500V, the charge accumulated in the ceramic dielectric layer 1a is more difficult to escape, so that the ceramic dielectric The polarization state of the layer 1a is easily maintained, and it becomes easier to maintain the attracting force with respect to the wafer 5 even when the voltage is lowered.

  The volume resistivity at the time of voltage application in the ceramic dielectric layer 1a made of an aluminum nitride ceramic can be measured by a known three-terminal method or the like.

In the electrostatic chuck 10 of the present embodiment, the aluminum nitride ceramic is preferably an aluminum nitride ceramic containing a sintering aid. In this case, the volume resistivity of the ceramic dielectric layer 1a can be easily controlled by adding a sintering aid. For example, it becomes easy to produce such that the volume resistivity value when 500 V is applied is in the range of 5 × 10 ^{8 to} 5 × 10 ¹⁰ Ω · cm.

  The content of the sintering aid contained in the aluminum nitride ceramic is preferably about 10 to 13% by mass. By setting it within this range, it becomes easy to control the volume specific resistance value of the ceramic dielectric layer 1a, and it is possible to effectively suppress a decrease in the volume specific resistance.

  In the electrostatic chuck 10 of the present embodiment, it is preferable that the sintering aid includes cerium oxide or yttria. In this case, since the thermal conductivity of the ceramic dielectric layer 1a is increased, the temperature of the electrostatic chuck 10 quickly reaches the set temperature under use conditions with temperature changes, and the controllability due to voltage application is improved, which is wasted. Less voltage control is possible. Furthermore, the sintering aid containing cerium oxide or yttria can further easily control the volume resistivity.

  The adsorption electrode 2 preferably has a thickness of 0.1 to 50 μm. By making the thickness within this range, when the plate-like body 1 composed of the ceramic dielectric layer 1a and the substrate 1b is produced by sintering, the sinterability is maintained even if oxygen is introduced into the firing furnace and sintered. It does not deteriorate and the conductivity of the adsorption electrode 2 can be kept high.

  The adsorption electrode 2 is preferably made of tungsten, titanium nitride or molybdenum. In this case, when the plate-like body 1 is produced by sintering, the sinterability does not deteriorate even if oxygen is put into the firing furnace and the sinterability is not deteriorated, and the conductivity of the adsorption electrode 2 is kept high. be able to.

  Furthermore, the area of the adsorption electrode 2 is preferably 85% to 90% of the area of the adsorption surface 3. By setting it within this range, there is an electrodeless portion with a suitable width in which the adsorption electrode 2 does not exist in a plan view. Since the electrodeless portion is less likely to escape charges than the electrode portion, Adsorption power can be maintained.

  The thickness of the ceramic dielectric layer 1a is preferably 0.3 to 1.5 mm. By setting the thickness within this range, it is difficult for dielectric breakdown to occur due to the ceramic dielectric layer 1a being too thin, and a decrease in adsorption force due to the ceramic dielectric layer 1a being too thick can be suppressed. Even if the voltage is further lowered, it becomes easy to maintain the adsorption force.

  Next, a method for manufacturing the electrostatic chuck according to the present embodiment will be described.

  First, a predetermined amount of an organic resin binder for improving moldability is added to AlN powder as a primary raw material, and cerium (Ce) is added to adjust the volume resistivity value. A ceramic tape molded body is produced by the method. An organic resin binder for enhancing adhesion is applied to each ceramic tape molded body, and then the ceramic tape molded bodies are sequentially laminated one by one and pressed to obtain a laminated molded body.

  The adsorption electrode 2 of the electrostatic chuck 10 is formed by adding an organic resin binder and a dispersant to W powder and using a conductive paste (conductive ink). The conductive paste is formed by printing a conductive paste layer to be the adsorption electrode 2 on a single ceramic tape molded body using a mesh-like printing plate making. The laminated molded body is printed with the thickness of the ceramic tape molded body, the number of laminated layers, and the conductive paste layer so that the suction electrode 2 is finally present at a depth of 0.3 mm to 1.5 mm from the suction surface 3. It is produced in consideration of the laminated position of the ceramic tape molded body.

  Next, in order to remove the organic resin binder in the laminated molded body, it is degreased by heating in a reducing gas atmosphere.

  Next, baking is performed in a nitrogen gas atmosphere. In this firing process, oxygen is introduced into the firing furnace. Here, it is preferable that a small amount (0.05 to 0.5% by volume) of oxygen gas can be introduced into the firing furnace by an oxygen introduction valve via a flow meter. In this case, particles lacking nitrogen (N) are scattered in the aluminum nitride (AlN) ceramics, and conductivity when a high voltage is applied is improved. As a result, the volume resistivity value of the aluminum nitride ceramic can be controlled by the oxygen content. The oxygen concentration in the firing furnace can be adjusted by opening and closing the oxygen introduction valve.

  By setting the amount of oxygen gas introduced into the firing furnace to 0.05 to 0.5% by volume, it is possible to effectively suppress a decrease in volume resistivity due to oxidation of cerium (Ce).

  Next, with respect to the plate-like body 1 made of an aluminum nitride ceramic, the adsorption surface 3 is polished so that the adsorption electrode 2 is positioned at a depth of 0.3 mm from the adsorption surface 3. Further, a through hole penetrating between the upper and lower main surfaces through which a lift pin for lifting the wafer 5 is inserted and a hole for providing a terminal 4 for supplying voltage to the adsorption electrode 2 are formed in the plate-like body 1 by cutting. To do. A terminal made of Cu was inserted into the hole, and the terminal was adhered to the adsorption electrode 2 with a conductive adhesive so as to be electrically connected to the adsorption electrode 2. In this way, the electrostatic chuck 10 is manufactured.

  The electrostatic chucking method of the object to be held according to the present embodiment uses the electrostatic chuck 10 having the configuration of the present embodiment as described above, and the chucking electrode 2 is used to electrostatically attract the object to be held such as a semiconductor wafer. The voltage to be applied is 200 to 2000 V at the start of adsorption, and then 10 to 500 V (however, the voltage at the start of adsorption is 1.2 times or more).

  With such a configuration, even if the voltage is lowered after the wafer 5 is applied with a high voltage, the volume specific resistance value is increased, so that charges accumulated in the ceramic dielectric layer 1a are difficult to escape. By using a highly durable electrostatic chuck 10 that can maintain the fixed state of the wafer 5 while maintaining the polarization state 1a, a desired process such as sputtering can be performed without interrupting the electrostatic adsorption of the object to be held. Can be processed. In addition, since it is not necessary to apply a high voltage for a long time, the object to be held can be processed with energy saving.

  A desired large adsorption force can be obtained by setting the voltage applied to the adsorption electrode 2 to 200 to 2000 V at the start of adsorption. For example, even a semiconductor wafer deformed through a series of semiconductor manufacturing processes such as film formation and etching can be adsorbed while maintaining flatness.

  By setting the voltage applied to the suction electrode 2 to 10 to 500 V after the start of suction, it is possible to continue the suction while maintaining the flatness of the semiconductor wafer.

  The time (period) for setting the voltage applied to the adsorption electrode 2 to 200 to 2000 V at the start of adsorption is preferably about 0.1 to 5 seconds. By making it within this time range, for example, a deformed semiconductor wafer can be sufficiently adsorbed while maintaining flatness, and the ratio of time to the time of one film formation or etching process is reduced. The load applied to the ceramic dielectric layer 1a can be reduced. And after this time passes, the voltage applied to the electrode 2 for adsorption | suction shall be 10-500V.

  By setting the voltage at the start of adsorption to at least 1.2 times the voltage after the adsorption starts, the load applied to the ceramic dielectric layer 1a can be reduced.

  Examples of the electrostatic chuck according to the present invention will be described below.

  A bipolar electrostatic chuck was produced as follows. First, an organic resin binder was added to the primary raw material AlN powder in order to improve the moldability, and 10% by volume of cerium (Ce) was added to adjust the volume resistivity, thereby preparing a ceramic paste.

  Next, using this ceramic paste, a ceramic tape molded body was produced by a doctor blade method. At this time, the size of the ceramic tape molded body is 300 mm square and 0.3 mm thick so that a disk-shaped plate body having a diameter (φ) of 200 mm can be manufactured as a dimension after firing and processing. The body was made.

  Next, 20 ceramic tape compacts are prepared, and an organic resin binder is applied to each ceramic tape compact to improve adhesion, and then 20 ceramic tape compacts are sequentially laminated one by one. Then, a laminated molded body was obtained by pressurizing at a pressure of about 20 MPa.

  Here, the adsorption electrode of the electrostatic chuck was formed by adding an organic resin binder and a dispersant to W powder having an average particle diameter of 1 μm and using a conductive paste (conductive ink). This conductive paste was printed on one ceramic tape molded body using a mesh-like printing plate making so that the thickness of the adsorption electrode was 15 μm. The laminated position of the ceramic tape molded body on which the conductive paste was printed was adjusted so that the adsorption electrode was positioned at a depth of 0.3 mm from the adsorption surface in the laminated molded body.

  Next, in order to remove the organic resin binder in the laminated molded body, degreasing was performed at about 500 ° C. in a reducing gas atmosphere.

  Next, the laminated molded body was fired at about 2000 ° C. in a nitrogen gas atmosphere. In this baking process, 0.2% by volume of oxygen gas was introduced into the baking furnace. Here, a small amount of oxygen gas can be introduced into the firing furnace by an oxygen introduction valve via a flow meter. The oxygen gas concentration in the firing furnace can be adjusted within the range of 0.1 to 0.5% by volume by opening and closing the oxygen introduction valve. Thereby, it was possible to disperse particles lacking N of the AlN particles in the aluminum nitride ceramics.

  Next, polishing was performed on the adsorption surface of the plate-like body made of aluminum nitride ceramic so that the adsorption electrode was positioned at a depth of 0.3 mm from the adsorption surface. Further, a through hole penetrating between the upper and lower main surfaces through which a lift pin for lifting the wafer is inserted and a hole provided with a terminal for supplying a voltage to the adsorption electrode were formed in the plate-like body by cutting. A terminal made of Cu was inserted into the hole, and the terminal was adhered to the adsorption electrode with an Ag-containing conductive adhesive so as to be electrically connected to the adsorption electrode. In this way, an electrostatic chuck was produced.

  Further, the electrostatic chuck was bonded to an Al base member with a silicone resin adhesive, and attached to an evaluation apparatus for evaluating the adsorptivity of the wafer. Here, since the silicone resin adhesive has low hardness, it was selected as one that can absorb the thermal expansion difference between the plate-like body made of aluminum nitride ceramics and the Al base member.

The electrostatic chuck was placed in a vacuum chamber, a silicon wafer was placed on the suction surface of the electrostatic chuck, and evacuation was performed to set the pressure in the vacuum chamber to 1 × 10 ⁻³ Pa. A voltage of 500 V was applied to the adsorption electrode embedded in the plate to adsorb the silicon wafer.

The volume resistivity value of the ceramic dielectric layer made of the aluminum nitride ceramic when a voltage of 500 V was applied was 1 × 10 ¹⁰ Ω · cm as measured in advance by the three-terminal method.

Then, 2 seconds after the voltage application, He gas was flowed from the gas introduction hole 6 at a pressure of 666 Pa. When the amount of He gas leaked at this time was measured, it was 3.38 × 10 ⁻⁴ Pa · m ³ / s. Furthermore, the voltage was lowered from 500 V to 250 V 2 seconds after flowing He gas.

The volume resistivity value of the ceramic dielectric layer made of the aluminum nitride ceramic when a voltage of 250 V was applied was 8 × 10 ¹⁰ Ω · cm as measured in advance by the three-terminal method.

At this time, the leakage amount of He gas remained at 3.38 × 10 ⁻⁴ Pa · m ³ / s, and it was confirmed that the adsorption of the silicon wafer remained stable even when the voltage was lowered.

  On the other hand, as comparative examples, 1) a plate-like body made of an aluminum nitride ceramic containing 10% by volume of cerium (Ce) as a sintering aid is used. 2) oxygen gas is not introduced into the firing furnace during the firing process. An electrostatic chuck was manufactured using a plate-like body having the above manufacturing conditions.

In the electrostatic chuck of this comparative example, the volume resistivity of the ceramic dielectric layer made of aluminum nitride ceramics when a voltage of 500 V was applied was 8 × 10 ⁹ Ω · cm when measured in advance by the three-terminal method. It was.

Further, the volume resistivity value of the ceramic dielectric layer made of aluminum nitride ceramics when a voltage of 250 V was applied was 9 × 10 ⁹ Ω · cm as measured in advance by the three-terminal method.

For the electrostatic chuck of the comparative example, the same measurement as in the example was performed. As a result, when the voltage was lowered to 250 V, the amount of He gas leaked was 6.76 × 10 ⁻³ Pa · m ³ / s, and the wafer could not be stably adsorbed.

  In addition, a life comparison test was performed on the electrostatic chuck (electrostatic chuck A) of the above example and the electrostatic chuck (electrostatic chuck B) of the comparative example.

  For the electrostatic chuck A of the example, 1) 500 V applied, 2) 250 V applied after 4 seconds, 3) 0 V after 1 minute 56 seconds, 4) 500 V applied after 0.5 seconds, 5) 250 V applied after 4 seconds, 6) 1 Voltage application was repeated in a cycle of 1) to 6) that the voltage was 0 V after 56 minutes. That is, the operation includes a step of reducing the voltage to 0 V in two stages in one cycle.

  For the electrostatic chuck B of Comparative Example, voltage application was repeated in the cycle 1) to 4), 1) 500 V applied, 2) 0 V after 2 minutes, 3) 500 V applied after 0.5 seconds, 4) 0 V after 2 minutes. . That is, the operation includes a step of reducing the voltage to 0 V in one step in one cycle.

  In addition, dielectric breakdown occurred in the ceramic dielectric layer in the electrostatic chuck B in 14 days, whereas dielectric breakdown did not occur in the ceramic dielectric layer in the electrostatic chuck A even after 60 days. The comparative test was discontinued.

  From this result, it was confirmed that the electrostatic chuck of the present invention can be used stably for a long period of time because the load on the ceramic dielectric layer due to voltage application is reduced.

  The present invention is not limited to the above-described embodiment and examples, and various modifications may be made without departing from the scope of the present invention.

It is a longitudinal section showing an example of an embodiment about an electrostatic chuck of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Plate-shaped body 1a ... Ceramic dielectric layer 1b ... Base | substrate 2 ... Electrode 3 for adsorption | suction ... Adsorption surface 4 ... Terminal 5 ... Wafer 6 ... Gas introduction hole 7 ... Groove
10 ... Electrostatic chuck

Claims (3)

In the electrostatic chuck comprising a ceramic dielectric layer having an adsorption surface of an object to be held and an electrode for adsorption to which a voltage for electrostatic adsorption of the object to be held is applied on the substrate, the ceramic dielectric The layer is made of an aluminum nitride ceramic, in which aluminum nitride particles lacking nitrogen are interspersed, and the volume applied when the voltage applied to the adsorption electrode is 500V. The volume resistivity value when the resistance value is 5 × 10 ^{8 to} 5 × 10 ¹⁰ Ω · cm and the voltage is 10 V is 5 × 10 ^{10 to} 5 × 10 ¹² Ω · cm, and the voltage is An electrostatic chuck characterized by being 3 times or more the volume resistivity value at 500V.   The electrostatic chuck according to claim 1, wherein the aluminum nitride ceramic is an aluminum nitride ceramic containing a sintering aid.   The electrostatic chuck according to claim 2, wherein the sintering aid contains cerium oxide or yttria.