JP3978714B2 - Manufacturing method of electrostatic chuck - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an electrostatic chuck suitably used in a manufacturing process of a silicon semiconductor, a compound semiconductor, an FPD (flat panel display), a hard disk, a saw filter, an optical memory device, and other electronic devices.
[0002]
[Prior art]
In the manufacturing process of silicon semiconductor, compound semiconductor, FPD, hard disk, saw filter, optical memory device and other electronic devices, dry etching, PVD (physical vapor deposition), CVD (chemical vapor deposition), etc. An electrostatic chuck is widely used for fixing an object (a silicon wafer, a glass substrate, an aluminum substrate, a polymer material, or the like) when performing.
[0003]
For example, as shown in FIG. 1, the electrostatic chuck has conductive electrodes 3 arranged in a predetermined pattern on an insulating substrate formed by covering the periphery of a graphite plate 1 with an insulating layer 2 such as PBN (pyrolytic boron nitride). These have a configuration in which they are covered with an insulating layer 4. Although not shown, both ends of the electrode 3 are connected to a power source through terminals.
[0004]
In the electrostatic chuck 6 having this configuration, when the object 5 such as a silicon wafer is placed on the chuck surface and a voltage is applied between the electrode terminals, a Coulomb force is generated and the object 5 can be chucked. . In this configuration, the electrostatic chuck also serves as a heater, and the attracted object 5 is uniformly heated or cooled to an optimum temperature at which an appropriate chuck suction force is exhibited.
[0005]
FIG. 1 shows an example of the configuration of a bipolar electrostatic chuck. In a monopolar electrostatic chuck, a configuration in which a single conductor electrode is disposed on an insulating substrate is covered with an insulating layer. And chucking the object to be adsorbed by applying a voltage between the electrode and the object to be adsorbed placed on the surface.
[0006]
By the way, when the object to be adsorbed is placed or adsorbed on the heated electrostatic chuck, the thermal chuck causes friction between the object to be adsorbed and the surface of the electrostatic chuck. A problem has been pointed out that a part of the material is scraped off, and the scraped material (hereinafter referred to as particles) adheres to the back surface of the object to be adsorbed and contaminates the chamber during transportation. Further, if the process proceeds to the exposure process with particles still attached to the back surface of the object to be adsorbed, the exposure focus is shifted, and the circuit pattern cannot be printed with high accuracy. In order to avoid such a problem, the goal is to reduce the number of particles having a diameter of 0.2 μm or more to 2000 or less on the back surface of an 8-inch wafer. However, PBN or carbon is doped as an insulating layer. When C-PBN is used, about 40000 particles are generated.
[0007]
As a means for reducing the generation of such particles, an electrostatic chuck using a surface insulating layer made of a material that can be processed with high precision by machining such as alumina, aluminum nitride, silicon nitride, etc. The portion to be adsorbed is configured such that the fine convex portions (also referred to as grain patterns, dimples, mesas, etc.) are scattered at a ratio of several percent with respect to the entire surface, and the object to be adsorbed is supported by these fine convex portions. It has been proposed to minimize the contact area with (JP-A-10-335439, JP-A-2000-106392, JP-A-2000-277594, JP-A-2001-144167, JP-A-2001-517872, etc.).
[0008]
[Problems to be solved by the invention]
However, according to the conventional technology as described above, since the convex portions on the surface of the electrostatic chuck formed by embossing are scattered independently, the convex portions lack due to friction with the object to be adsorbed, On the contrary, there was a case where particle generation was promoted. In particular, electrostatic chucks that use PBN or C-PBN with a layer structure as the insulating layer on the surface tend to cause delamination due to the friction of the object to be adsorbed. It was difficult to do.
[0009]
[Means for Solving the Problems]
Accordingly, the present invention provides a novel configuration capable of minimizing the generation of particles due to rubbing against an object to be adsorbed even in an electrostatic chuck using PBN or C-PBN having a layer structure as a coating layer. Objective.
[0010]
In order to achieve this object, the present invention according to claim 1 is directed to manufacturing an electrostatic chuck in which one or a plurality of conductor electrodes are formed on an insulating layer mainly composed of PBN (pyrolytic boron nitride). A mask patterned in a mesh shape according to the position of the continuous convex portion to be formed on the surface of the layer is applied, and the non-mask region on the surface of the insulating layer is dry-etched with an etching gas converted into plasma in a vacuum chamber. In the manufacturing method of the electrostatic chuck in which the mask is removed after forming the mesh-like convex portions on the surface of the layer, the dry etching has a molecular weight equal to or higher than the molecular weight of boron and nitrogen as an etching gas. physically etching the boron and nitrogen atoms of the unmasked area by colliding surface of the insulating layer using an inert gas containing an element Characterized in that it comprises a that step.
[0011]
The present invention according to claim 2 should be formed on the surface of an insulating layer after manufacturing an electrostatic chuck in which one or a plurality of conductor electrodes are formed on an insulating layer mainly composed of PBN (pyrolytic boron nitride). A mask patterned in a mesh shape is applied according to the position of the continuous convex portion, and the non-mask area on the surface of the insulating layer is dry-etched with an etching gas converted into plasma in a vacuum chamber so that the surface of the insulating layer is continuously meshed. In the manufacturing method of the electrostatic chuck in which the mask is removed after forming the convex portions, the dry etching uses oxygen as an etching gas to oxidize boron atoms in the non-mask region of the insulating layer surface to B ₂ O ₃ . chemically etching step to solve interatomic bond of B-N by equal to or該分molecular weight of boron and nitrogen as the etching gas Characterized in that it comprises the step of physically etching the B ₂ O ₃ and the nitrogen atom of the unmasked area by colliding surface of the insulating layer using an inert gas containing an element in an amount more than the molecular weight.
[0016]
According to a third aspect of the present invention, in the method for manufacturing an electrostatic chuck according to the first or second aspect , the inert gas is a gas selected from the group consisting of argon, nitrogen, neon, krypton, and xenon, or It is characterized by being a mixed gas of them.
[0017]
The present invention according to claim 4, after manufacturing an electrostatic chuck in which one or a plurality of conductor electrodes are formed on an insulating layer mainly composed of C-PBN doped with carbon in PBN (pyrolytic boron nitride), A mask patterned in a mesh shape is applied according to the position of the continuous convex portion to be formed on the surface of the insulating layer, and the non-mask region on the surface of the insulating layer is dry-etched by plasma of an etching gas in a vacuum chamber. The mask is removed after forming convex portions that are continuous in a mesh shape on the surface.
[0018]
According to a fifth aspect of the present invention, in the method for manufacturing an electrostatic chuck according to the fourth aspect, the dry etching includes an element having a molecular weight equal to or higher than the molecular weight of boron, nitrogen, and carbon as an etching gas. The method includes a step of physically etching boron atoms and nitrogen atoms in a non-mask region by colliding with the surface of the insulating layer using an inert gas.
[0019]
According to a sixth aspect of the present invention, in the method for manufacturing an electrostatic chuck according to the fourth aspect, in the dry etching, the carbon atoms in the non-mask region on the surface of the insulating layer are changed to CO and / or CO using oxygen as an etching gas. _A chemical etching step that breaks the BN interatomic bond by oxidizing it to ₂ and discharging it out of the system and oxidizing boron atoms to B ₂ O ₃ , and has the same molecular weight as boron, nitrogen and carbon as etching gases Or a step of physically etching the B ₂ O ₃ and nitrogen atoms in the non-mask region by colliding with the surface of the insulating layer using an inert gas containing an element having a molecular weight equal to or higher than the molecular weight. .
[0020]
The present invention according to claim 7 is the method of manufacturing an electrostatic chuck according to claim 5 or 6, wherein the inert gas containing an element having a molecular weight equal to or higher than the molecular weight of boron, nitrogen, and carbon, It is characterized by being one gas selected from the group consisting of argon, nitrogen, neon, krypton and xenon or a mixed gas thereof.
The present invention is not limited to the above-described embodiments, and various embodiments can be taken within the scope of the invention described in each of the claims. Speaking of the etching gas, the etching gas in the first embodiment physically hits boron atoms, nitrogen atoms, and carbon atoms in the non-mask region by colliding with the insulating layer surface. An inert gas containing an element having an equivalent or higher molecular weight can be used. In addition to the above-mentioned argon, nitrogen, neon (Ne), krypton (Kr), xenon (Xe), etc. are used alone or in any mixture. be able to. The etching gas used in the second step in the second and third embodiments is also used to physically etch boron atoms, nitrogen atoms, and carbon atoms in the non-mask region by colliding with the surface of the insulating layer. In addition to argon (second embodiment) and nitrogen (third embodiment), neon (Ne), krypton (Kr), xenon (Xe) and the like can be used alone or in any mixture.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
A 300 μm PBN insulating layer 2 is formed on the surface of a graphite plate 1 having a thickness of 10 mm by the CVD method. Further, a 50 μm PG layer is formed on both surfaces by the CVD method, and the conductor electrode 3 of the PG layer The conductor electrode 3 having a predetermined pattern was formed on both surfaces of the PBN insulating layer 2 by removing the other part while leaving the part having the predetermined pattern. Next, 3 mol of ammonia and 2.4 mol of methane gas are reacted at 0.5 Torr and a temperature of 1850 ° C. with respect to 1 mol of boron trichloride by CVD, and a carbon-added PBN (C-PBN) insulating layer having a thickness of 100 μm is formed on the entire surface. 4 was obtained to obtain a bipolar electrostatic chuck 6 having the configuration shown in FIG. The electrical resistivity of the C-PBN coating layer 4 in the electrostatic chuck 6 was measured and found to be 2.8 × 10 12 Ω · cm.
[0022]
In order to form convex portions 7 in a lattice form as shown in FIG. 3 on the surface of the C-PBN insulating layer 4 of the obtained electrostatic chuck 6, plasma drying is performed using an apparatus configured as shown in FIG. 2. Etching treatment was performed. That is, a mask patterned in a lattice shape is applied to the surface of the insulating layer 4 of the electrostatic chuck 6 in accordance with the formation position of the convex portion 7 and placed on the electrode 11 in the plasma chamber 10. Thus, the inside of the chamber 10 is adjusted and maintained at a predetermined degree of vacuum, an etching gas is introduced from the gas introduction unit 17, and a high frequency is applied from the high frequency RF power supply 13 to the electrostatic chuck 6 through the mixing unit 16. As a result, a plasma region 14 is formed around the electrostatic chuck 6 and the introduced etching gas is ionized. Next, etching is performed by applying a predetermined pulse voltage from the pulse power supply 15 to the electrostatic chuck 6 via the mixing unit 16 after a predetermined after glow time (time from application of the high frequency voltage for plasma formation to the application of the pulse voltage) has elapsed. The gas ions are moved at high speed to collide with the non-mask region on the surface of the insulating layer 4.
[0023]
In the first embodiment, argon is used as an etching gas, and argon ionized in the plasma region 14 of the vacuum chamber 10 is made to collide with the surface of the insulating layer 4 of the electrostatic chuck 6, whereby B (boron atoms in the non-mask region). ), N (nitrogen atoms) and C (carbon atoms) are physically removed by sputtering. The etching in the first embodiment is a physical etching performed by a mechanism as shown in FIG.
[0024]
In the second embodiment, a two-stage dry etching process is performed. In the first step, oxygen is used as an etching gas, and oxygen plasma formed in the plasma region 14 of the vacuum chamber 10 is made to collide with the surface of the insulating layer 4 of the electrostatic chuck 6, whereby carbon atoms in the non-masked region of the insulating layer surface. Is oxidized to CO or CO2 and discharged out of the system, and boron atoms are oxidized to B2O3 to break the BN interatomic bond. In the second step, argon is used as an etching gas, and argon ionized in the plasma region 14 of the vacuum chamber 10 is made to collide with the surface of the insulating layer 4, and B2O3 and nitrogen atoms present in the non-masked region in the first step are caused to flow. Physically sputter to remove. Etching in the second embodiment is performed by a mechanism as shown in FIG. 5, and the first step according to (A) to (B) (actually performed almost simultaneously, not in time series) is chemical or reaction. The second step according to (D) is a physical etching similar to the reaction mechanism (FIG. 4) according to the first embodiment described above.
[0025]
In the third embodiment, a two-stage dry etching process is performed as in the second embodiment, and is the same as the second embodiment except that nitrogen is used as an etching gas in the second process. Etching in the third embodiment is performed by a mechanism as shown in FIG.
[0026]
By performing the etching process as described above, the non-mask region on the surface of the insulating layer 4 in the electrostatic chuck 6 is etched, and a convex portion 7 (FIG. 3) continuous in a mesh shape is formed on the surface of the insulating layer. Therefore, after that, the mask is removed, and the electrostatic chuck of the present invention is manufactured. As for masking and mask removal, it is possible to adopt a method of performing masking by partially exposing and removing the photoresist thin film and removing the mask made of this photoresist by asher after etching, or any other method. it can.
[0027]
The etching process in the first to third embodiments described above is performed under the conditions as shown in FIG. 7, and the mesh-like continuous convex portions 7 (total of the convex portions) having a width of 0.1 mm at intervals of 3 mm are formed on the surface of the insulating layer 4. An electrostatic chuck having a surface area of about 6% of the total surface area of the insulating layer 4 is manufactured, and an 8-inch wafer is placed on the mesh-like continuous convex portion 7 and heat-adsorbed. The number of particles having a diameter of 0.2 μm or more is about 2400, and the number of particles generated when a conventional electrostatic chuck having a smooth surface of the insulating layer 4 made of PBN or C-PBN is used (about 40000). ) To about 6%.
[0028]
The present invention is not limited to the above-described embodiments, and various embodiments can be taken within the scope of the invention described in each of the claims. Speaking of the etching gas, the etching gas in the first embodiment physically hits boron atoms, nitrogen atoms, and carbon atoms in the non-mask region by colliding with the insulating layer surface. An inert gas containing an element having an equivalent or higher molecular weight can be used. In addition to the above-mentioned argon, nitrogen, neon (Ne), krypton (Kr), xenon (Xe), etc. are used alone or in any mixture. be able to. The etching gas used in the second step in the second and third embodiments is also used to physically etch boron atoms, nitrogen atoms, and carbon atoms in the non-mask region by colliding with the surface of the insulating layer. In addition to argon (second embodiment) and nitrogen (third embodiment), neon (Ne), krypton (Kr), xenon (Xe) and the like can be used alone or in any mixture.
[0029]
【The invention's effect】
According to the present invention, the surface of the PBN or C-PBN insulating layer has a convex portion that is continuous in a mesh shape, and the surface of the convex portion is configured to support an object to be adsorbed such as a silicon wafer . Since the electrostatic chuck can be manufactured , the contact area with the object to be adsorbed is minimized, and generation of particles due to rubbing with the object to be adsorbed can be suppressed.
[0030]
The convex portions on the surface of the insulating layer are not scattered independently as in the conventional embossed convex portions, and the convex portions are continuous in a mesh shape. Since the entire portion exhibits strength against peeling, peeling due to rubbing with an adsorbed object hardly occurs even in an insulating layer mainly composed of PBN or C-PBN having a layer structure.
[0031]
In addition, by employing a dry etching process using a specific etching gas, an electrostatic chuck having mesh-like continuous convex portions on the surface of the insulating layer can be efficiently manufactured.
[Brief description of the drawings]
FIG. 1 is a structural diagram of a bipolar electrostatic chuck.
FIG. 2 is a schematic view showing an apparatus configuration example for an etching process performed for forming a mesh-like continuous convex portion on the surface of an insulating layer in the method for manufacturing an electrostatic chuck according to the present invention.
FIG. 3 is a schematic perspective view showing mesh-like continuous convex portions on the insulating layer surface of the electrostatic chuck of the present invention.
FIG. 4 is an explanatory view showing an embodiment of an etching process performed for forming a mesh-like continuous convex portion on the surface of an insulating layer in the method for manufacturing an electrostatic chuck according to the present invention.
FIG. 5 is an explanatory view showing another embodiment of an etching process performed to form a mesh-like continuous convex portion on the surface of an insulating layer in the method for manufacturing an electrostatic chuck according to the present invention.
FIG. 6 is an explanatory view showing still another embodiment of an etching process performed for forming a mesh-like continuous convex portion on the surface of an insulating layer in the method for manufacturing an electrostatic chuck according to the present invention.
7 is a table illustrating conditions for etching processing according to the embodiments shown in FIGS. 4 to 6; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Graphite plate 2 Insulating layer 3 Conductor electrode 4 Insulating layer 5 Adsorbed object 6 such as silicon wafer Electrostatic chuck 7 Mesh-like continuous convex portion 10 Plasma chamber 11 Electrode 12 Vacuum pump 13 RF power source 14 Plasma region 15 Pulse power source 16 Mixing unit 17 Gas introduction part

Claims (7)

After manufacturing an electrostatic chuck in which one or more conductor electrodes are formed on an insulating layer mainly composed of PBN (pyrolytic boron nitride), a mesh shape is formed according to the position of the continuous convex portion to be formed on the surface of the insulating layer. Then, a patterned mask is formed on the surface of the insulating layer by dry etching the non-mask region on the surface of the insulating layer with an etching gas converted into plasma in a vacuum chamber. In the manufacturing method of the electrostatic chuck that removes the dry etching, the dry etching is performed by causing an inert gas containing an element having a molecular weight equal to or higher than the molecular weight of boron and nitrogen as an etching gas to collide with the surface of the insulating layer. A method of manufacturing an electrostatic chuck comprising a step of physically etching boron atoms and nitrogen atoms in a non-mask region . After manufacturing an electrostatic chuck in which one or more conductor electrodes are formed on an insulating layer mainly composed of PBN (pyrolytic boron nitride), a mesh shape is formed according to the position of the continuous convex portion to be formed on the surface of the insulating layer. Then, a patterned mask is formed on the surface of the insulating layer by dry etching the non-mask region on the surface of the insulating layer with an etching gas converted into plasma in a vacuum chamber. In the method of manufacturing an electrostatic chuck that removes oxygen, the dry etching is performed by oxidizing the boron atoms in the non-mask region on the surface of the insulating layer to B ₂ O ₃ by using oxygen as an etching gas to bond BN atoms. including a chemical etching step of solving, the elements equal to the molecular weight of boron and nitrogen as the etching gas or the molecular weight or molecular weight Method of manufacturing an electrostatic chuck which comprises a step of physically etching the B ₂ O ₃ and the nitrogen atom of the unmasked area by colliding with the insulating layer surface with an inert gas. The method for manufacturing an electrostatic chuck according to claim 1, wherein the inert gas is one gas selected from the group consisting of argon, nitrogen, neon, krypton, and xenon, or a mixed gas thereof. . After manufacturing an electrostatic chuck in which one or a plurality of conductor electrodes are formed on an insulating layer mainly composed of C-PBN doped with carbon in PBN (pyrolytic boron nitride), a continuous layer to be formed on the surface of the insulating layer A mesh-patterned mask is formed on the surface of the insulating layer by applying a mask patterned in a mesh shape according to the position of the protrusion, and dry etching the non-mask area on the surface of the insulating layer with an etching gas plasma in a vacuum chamber. After forming the mask, the mask is removed. The dry etching is performed using an inert gas containing an element having a molecular weight equal to or higher than the molecular weight of boron, nitrogen, and carbon as an etching gas, and is caused to collide with the surface of the insulating layer to form boron atoms and nitrogen atoms in the non-mask region. The method of manufacturing an electrostatic chuck according to claim 4, further comprising a step of physically etching the substrate. In the dry etching, oxygen is used as an etching gas to oxidize carbon atoms in the non-mask region on the surface of the insulating layer to CO and / or CO ₂ to be discharged out of the system and to oxidize boron atoms to B ₂ O _3. And a chemical etching process for breaking the BN interatomic bond, and collision with the insulating layer surface using an inert gas containing an element having a molecular weight equal to or higher than that of boron, nitrogen and carbon as an etching gas. The method for manufacturing an electrostatic chuck according to claim 4, further comprising: physically etching B ₂ O ₃ and nitrogen atoms in the non-mask region. The inert gas containing an element having a molecular weight equal to or higher than the molecular weight of boron, nitrogen, and carbon is one gas selected from the group consisting of argon, nitrogen, neon, krypton, and xenon, or a mixed gas thereof. The method for manufacturing an electrostatic chuck according to claim 5, wherein the method is provided.

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