JP2004074336A - Polishing table - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing table wherein the polishing object surface of a workpiece is extremely flatly polished, warp and strain are hardly produced even if enlarging its diameter, so that the table is thinned and reduced in weight. <P>SOLUTION: This polishing table comprising a negative electrode of a polishing device and electropolishing the polishing object surface of the workpiece disposed opposed to its surface via electrolyte is formed of conductive ceramic. <P>COPYRIGHT: (C)2004,JPO

Description

【０１００】
表１に示した結果から明らかなように、実施例１〜４に係る研磨用テーブルを用いて電解研磨を行った被研磨面の平坦度は、いずれも５０〜１００ｎｍであり、電解研磨前の被研磨面に比べて極めて平坦に研磨されていた。
また、いずれの実施例に係る被研磨面にも電解研磨による傷は観察されなかった。
さらに、実施例１〜４に係る研磨用テーブルは、反りや歪が殆ど発生しておらず、軽く、容易に交換等ができ取扱い性に優れていた。
【０１０１】
一方、比較例１に係る研磨用テーブルを用いて電解研磨を行った被研磨面には、電解研磨による傷は、発生していなかったが、その平坦度は、３００ｎｍであり、その平坦度は、実施例に比べて大きくなっていた。
また、比較例１に係る研磨用テーブルは、実施例に係る研磨用テーブルに比べて大きな反りや歪が発生しており、重く、交換作業が困難であり取扱い性に劣るものであった。
【０１０２】
【発明の効果】
本発明の研磨用テーブルは、上述した通りの構成であるので、該研磨用テーブルを用いてなる本発明の研磨装置を用いて被研磨物を電解研磨すると、被研磨物の被研磨面を極めて平坦に電解研磨することができ、その直径を大きくしても反りや歪が殆ど発生することがないため、薄く、軽量化を図ることができる。
【図面の簡単な説明】
【図１】第一の本発明の研磨用テーブルの一例を模式的に示した斜視図である。
【図２】第一の本発明の研磨用テーブルを用いて被研磨物の電解研磨を行う際の研磨用テーブルと被研磨物との関係を示した断面図である。
【図３】第二の本発明の研磨用テーブルの一例を模式的に示した斜視図である。
【図４】第二の本発明の研磨用テーブルを用いて被研磨物の電解研磨を行う際の研磨用テーブルと被研磨物との関係を示した断面図である。
【符号の説明】
１０、２０　研磨用テーブル
１４　電解液
１５　被研磨物
２１　基板
２２　導体層
２３　有底孔[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polishing table constituting a polishing apparatus used when polishing a surface to be polished of an object to be polished by electrolytic polishing.
[0002]
[Prior art]
[Patent Document 1]
JP-A-2002-25956
[0003]
In recent years, with the increase in density and miniaturization of semiconductor devices represented by ICs, LSIs, etc., multi-layer wiring has been promoted along with miniaturization of wiring, and research on semiconductor devices having a multilayer wiring structure has been actively conducted. Is being done.
[0004]
Usually, the semiconductor element having the multilayer wiring structure has a structure in which a plurality of insulating layers in which metal wiring circuits such as copper of a predetermined pattern are embedded are laminated, and metal wiring circuits between upper and lower layers are connected by vias or the like. .
[0005]
When manufacturing a semiconductor element having such a multilayer wiring structure, in order to prevent disconnection of the metal wiring circuit and ensure insulation of the insulating layer, and to form a wiring pattern reliably, the metal wiring circuit is formed on the insulating layer. It is necessary to remove the excess metal layer formed higher than the surface of the insulating layer after the formation, and to planarize the surface. In particular, with the increase in the number of laminated insulating layers in recent years, the above-mentioned planarization step has become an important step.
[0006]
Therefore, in the manufacture of the semiconductor element having the multilayer wiring structure, a groove having a predetermined circuit pattern is formed in the insulating layer by a photolithography process or the like, and a metal such as copper serving as a wiring material is buried in the groove by plating or the like. The so-called damascene method of removing a metal layer by CMP (Chemical Mechanical Polishing) using a chemical polishing action by a chemical and a mechanical polishing action by abrasive grains is mainly used.
[0007]
However, when the extra metal layer is polished by the above-mentioned CMP method, it is necessary to apply the predetermined pressure while applying a predetermined pressure, so that the insulating layer and the like may be greatly damaged and cracks may occur. Further, when the abrasive is mechanically worn with such pressure applied thereto, there is a problem that it is impossible to avoid leaving scratches on the surface of the metal wiring circuit after polishing.
[0008]
Therefore, instead of the above-described CMP method, a method has been proposed in which an excess metal layer formed on the insulating layer is polished and removed by an electrolytic polishing method.
In the above-mentioned electrolytic polishing method, an electrolytic solution is supplied between a metal wiring circuit (anode) and an electrode (cathode) to be polished, and a voltage is applied between the metal wiring circuit and the electrode, so that an extra This is a method of flattening the surface by preferentially oxidizing (anodic oxidizing) and dissolving the metal layer portion (convex portion).
Such an electropolishing method is different from a method of mechanically shaving the surface of a metal wiring circuit with abrasive grains while applying pressure to the surface of a metal wiring circuit as in the above-mentioned CMP method. Scratches on the surface of the circuit can be prevented.
As described above, the polishing of the surface of the metal wiring circuit by the electrolytic polishing method can solve the above-mentioned problems of the CMP method.
[0009]
In recent years, in order to obtain more semiconductor chips from one silicon wafer, the diameter of the silicon wafer has been increased. With the increase in the diameter of such a silicon wafer, the diameter of a polishing table used for performing the electrolytic polishing of the surface of the silicon wafer also needs to be increased.
[0010]
However, the polishing table used in the conventional electrolytic polishing method is made of a metal such as copper (see, for example, paragraph [0016] of Patent Document 1). Therefore, if the diameter is increased, warping or distortion occurs due to its own weight. Unless the thickness is increased, the surface to be polished of a large-diameter silicon wafer cannot be uniformly electropolished. However, when the thickness of the polishing table is increased in this manner, there is a problem that the weight becomes heavy and the polishing table becomes bulky.
[0011]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and can polish a polished surface of an object to be polished extremely flatly, and hardly causes warpage or distortion even if its diameter is increased. Therefore, an object of the present invention is to provide a polishing table that can be thin and light in weight.
[0012]
[Means for Solving the Problems]
The polishing table according to the first aspect of the present invention constitutes a cathode of a polishing apparatus, and a polishing table for performing electropolishing of a surface to be polished of an object to be polished which is disposed via an electrolytic solution so as to face the surface thereof. Wherein the polishing table is made of a conductive ceramic.
[0013]
Further, the polishing table of the second aspect of the present invention constitutes a polishing apparatus, and a polishing table for performing electropolishing of a surface to be polished of an object to be polished which is disposed via an electrolyte so as to face the surface thereof. The polishing table includes a ceramic substrate and a conductor layer formed on a surface of the substrate and functioning as a cathode of a polishing apparatus.
In the following, when there is no need to distinguish between the polishing table of the first present invention and the polishing table of the second present invention, it is simply referred to as the polishing table of the present invention.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
First, the polishing table of the first invention will be described.
The polishing table according to the first aspect of the present invention constitutes a polishing apparatus, and is a polishing table for performing electropolishing of a surface to be polished of an object to be polished which is disposed via an electrolytic solution so as to face the surface thereof. The polishing table is made of a conductive ceramic.
[0015]
FIG. 1 is a perspective view schematically showing one example of the polishing table of the first invention, and FIG. 2 is a schematic view showing the relationship between the polishing table and the object to be polished when performing the electrolytic polishing. FIG.
[0016]
As shown in FIG. 1, the first polishing table 10 of the present invention has a disk shape.
This polishing table 10 constitutes a cathode of a polishing apparatus for performing electropolishing, and as shown in FIG. 2, in the polishing apparatus, an electrolytic solution 14 is interposed so as to face the uppermost surface of the polishing table. The object to be polished 15 is provided, and a voltage is applied between the polishing table 10 and the object to be polished 15, so that the surface of the object to be polished 15 facing the polishing table 10 is electropolished. The specific method of the electropolishing will be described later.
[0017]
In the above-mentioned electrolytic polishing apparatus, the polishing table and the object to be polished are used as electrodes, and a voltage is applied between them. Therefore, the polishing table needs to be a conductor.
The material constituting the polishing table according to the first aspect of the present invention is a conductive ceramic. Since the polishing table of the first invention made of the conductive ceramic has high mechanical strength, even if the substrate is made thin, it is unlikely to cause warpage or distortion.
[0018]
The conductive ceramic is not particularly limited. For example, SiC, WC, MoC, ZrB ₂ , TiB ₂ , ZrN, TiN, ZrC, NbC, TiC, TaC and the like, and a non-oxide ceramic having corrosion resistance. Among them, SiC is preferable. This is because it is chemically stable, has excellent chemical resistance to hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, hydrofluoric acid, sodium hydroxide, and the like, and is unlikely to be dissolved or corroded by an electrolytic solution.
In the polishing table according to the first aspect of the present invention, the substrate made of the conductive ceramic may be made of dense ceramic, or may be made of porous ceramic.
[0019]
When the polishing table of the first invention is made of dense ceramic, the polishing table of the first invention has very excellent rigidity. Therefore, for example, when polishing an object to be polished having a very large surface to be polished, it is not necessary to make the thickness of the polishing table of the first invention too large. Therefore, it is relatively lightweight, can be easily manufactured, and has excellent handleability.
[0020]
The dense ceramic can be produced by making the particle diameter of the powder as a raw material uniform, by producing a high-density compact using granules or the like. Hereinafter, a dense silicon carbide sintered body will be described as an example.
[0021]
The average particle diameter of the silicon carbide particles constituting the dense silicon carbide sintered body is desirably 1 to 100 μm. This is because the above-described substrate can be a dense silicon carbide sintered body having excellent bending strength.
The porosity of the dense silicon carbide sintered body is preferably 5% or less, and more preferably 1% or less. The Young's modulus is desirably 100 to 600 GPa.
[0022]
It is desirable that the dense silicon carbide sintered body contains a conductive substance such as carbon. By containing impurities, the silicon carbide crystal can be made conductive to some extent, but by containing a conductive material such as carbon at the grain boundaries, it is possible to make the material more conductive. is there.
The lower limit of the resistivity of the dense silicon carbide sintered body is 10 ^-3 Ω · cm is desirable, and the upper limit is 10 ⁷ Ω · cm is desirable. A more desirable lower limit of the resistivity of the dense silicon carbide sintered body is 10%. ^-2 Ω · cm, and a more desirable upper limit is 10 ³ Ω · cm.
Specific examples of the silicon carbide sintered body include, for example, SC850, SCR-302, SCR-02, and SCH-07 manufactured by IBIDEN Corporation. Moreover, CVD-SiC manufactured by the CVD method is also included.
[0023]
On the other hand, when the polishing table of the first invention is made of a porous ceramic having an opening, when polishing the surface to be polished of the object to be polished using the polishing table of the first invention, An electrolytic solution to be supplied between the polishing table of the present invention and the surface to be polished can be supplied through an opening, and is uniformly applied to the entire surface to be polished of the object to be polished at a constant speed. Can be supplied.
[0024]
The porous ceramic is to use a powder obtained by mixing two kinds of powders having different particle diameters, to perform sintering using a material having a not so large effect as a sintering aid, without applying pressure during sintering, It can be produced by firing under mild conditions. Hereinafter, a porous silicon carbide sintered body will be described as an example.
[0025]
The porosity of the polishing table according to the first aspect of the present invention comprising the porous silicon carbide sintered body is desirably 10 to 60%. When the porosity is less than 10%, it is difficult to allow the electrolyte to pass smoothly through the inside of the polishing table of the first aspect of the present invention. On the other hand, when the porosity exceeds 60%, the mechanical strength is reduced. May decrease. Further, the strength of the polishing table according to the first aspect of the present invention is reduced, so that the polishing table may be easily broken by thermal shock, vibration, or the like.
[0026]
The polishing table of the first invention made of the porous silicon carbide sintered body desirably has a Young's modulus of 20 to 350 GPa. If it is less than 20 GPa, the mechanical strength is too low, and there is a possibility that breakage or the like may occur during use as an electropolishing table. On the other hand, it is difficult to ensure a strength exceeding 350 GPa while securing a predetermined porosity. .
[0027]
The pore diameter of the substrate made of the porous silicon carbide sintered body is desirably 0.1 to 50 μm. When the pore diameter is less than 0.1 μm, it is difficult to smoothly pass the electrolytic solution into the inside of the polishing table of the first present invention. It is difficult to maintain the mechanical properties such as the Young's modulus of the table at the above values.
[0028]
The lower limit of the resistivity of the porous silicon carbide sintered body is 10 ^-3 Ω · cm is desirable, and the upper limit is 10 ⁷ Ω · cm is desirable. A more desirable lower limit of the resistivity of the porous silicon carbide sintered body is 10 Ω · cm, and a more desirable upper limit is 10 Ω · cm. ⁶ Ω · cm.
Specific examples of the porous silicon carbide sintered body include, for example, SCP-5, SCP-02, SCP-7, SC550, SCP-302, and SCF-030 manufactured by Ibiden Co., Ltd.
[0029]
The shape of the polishing table according to the first aspect of the present invention is a disk shape, and the diameter is preferably 400 mm or more, more preferably 500 mm or more. When the substrate to be polished is a semiconductor wafer, the substrate having such a large diameter can be subjected to electrolytic polishing of a plurality of semiconductor wafers, and can sufficiently cope with the recent increase in diameter of semiconductor wafers. Because you can.
[0030]
Further, when the polishing table of the first invention is made of dense ceramic, a desirable upper limit of the thickness is 50 mm, and a lower limit thereof is 10 mm. On the other hand, when the first polishing table of the present invention is made of a porous ceramic, a desirable upper limit of the thickness is 100 mm, and a lower limit thereof is 10 mm.
[0031]
It is desirable that a shielding plate is formed on or above the polishing table of the first invention. When the polishing table according to the first aspect of the present invention is mounted on an electrolytic polishing apparatus and the surface to be polished of an object to be polished such as a semiconductor wafer is subjected to electrolytic polishing, a uniform voltage (electric field) is applied to the entire surface to be polished. Is difficult, and the voltage (electric field) near the center tends to be higher than the voltage near the outer edge. Therefore, the vicinity of the center of the polished surface may be preferentially polished, and it may be difficult to uniformly polish the polished surface. Therefore, by providing a shielding plate on the polishing table of the first invention, a voltage (electric field) or a flow of electrolyte applied between the surface to be polished and the polishing table of the first invention is provided. Is intentionally disturbed, a uniform voltage is applied to the entire surface to be polished, and the entire surface to be polished can be uniformly polished.
[0032]
The material constituting the shielding plate is not particularly limited, and examples thereof include inorganic materials such as ceramics and resins.
[0033]
The ceramic is not particularly limited, and examples thereof include a nitride ceramic, a carbide ceramic, and an oxide ceramic.
[0034]
The nitride ceramic is not particularly limited, and examples thereof include aluminum nitride, silicon nitride, boron nitride, and titanium nitride. These may be used alone or in combination of two or more.
[0035]
The carbide ceramic is not particularly limited, and examples thereof include silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, and tungsten carbide. These may be used alone or in combination of two or more.
[0036]
Further, the oxide ceramic is not particularly limited, and examples thereof include alumina, silica, zirconia, cordierite, and mullite. These may be used alone or in combination of two or more.
[0037]
The above resin is not particularly limited. For example, polyimide resin, fluorine resin, silicone resin, bismaleimide resin, polyphenylene resin, phenoxy resin, polyphenylene sulfone (PPS), polyphenylene sulfide (PPES), polyphenylene ether (PPE), polyether Thermoplastic resins such as imide (PI) and thermosetting resins are exemplified.
[0038]
The shape of the shielding plate is not particularly limited, and is appropriately determined according to the size of the polishing table and the object to be polished of the first invention, the intensity of the applied voltage, and the like.
Further, the shielding plate may be formed directly on the polishing table of the first invention, and between the surface of the polishing table of the first invention and the surface to be polished of the object to be polished. You may interpose. When interposed between the surface of the polishing table and the surface to be polished of the object to be polished, it may be arranged near the object to be polished, may be arranged near the polishing table, and further, You may arrange | position in the middle of both.
[0039]
When the shielding plate is formed directly on the polishing table, the shielding plate is formed when the polishing table is manufactured. In this case, it is only necessary to form a shielding plate having an outer shape composed of various patterns substantially similar to those of the polishing table. Examples of the pattern of the shielding plate include a mesh shape, a pattern in which a large number of holes having various shapes are formed, and the like. These shielding plates may have irregularities. When the shielding plate is made of ceramic, when manufacturing a polishing table, green sheets of a predetermined pattern may be laminated and fired. It can be formed by applying a liquid containing a resin, heating and the like. Screen printing or the like may be performed to form a predetermined pattern.
[0040]
Next, a method of manufacturing the polishing table according to the first embodiment of the present invention will be described.
In the following, a method of manufacturing a polishing table made of dense silicon carbide or porous silicon carbide will be mainly described.
[0041]
When manufacturing the first polishing table of the present invention made of a conductive ceramic, a slurry is prepared by mixing a ceramic powder such as a carbide ceramic with a binder, a solvent and the like, and the slurry is spray-dried. Thus, a granular powder is produced. Then, by using the above granular powder, rubber press molding, injection molding, extrusion molding, casting molding or the like is performed to form a disk-shaped or polygonal-shaped molded product (formed product).
When molding the above-mentioned molded product, a cold isostatic pressure (CIP) method may be used, and the molding pressure at this time is desirably a lower limit of 96 MPa, an upper limit of 144 MPa, a lower limit of 106 MPa, and an upper limit of 106 MPa. More preferably, it is 134 MPa. This is because the bending strength and density of the molded body to be molded are increased.
[0042]
When producing dense silicon carbide, first, a boron compound is added to silicon carbide powder, a binder is added to produce granules, and then molding is performed to produce a formed body. When producing porous silicon carbide, first, a binder is added to silicon carbide powder to produce granules, and then molding is performed to produce a formed body.
[0043]
Next, after the formed body is degreased, it is baked at 1700 to 2400 ° C. in a non-oxidizing atmosphere such as nitrogen or argon to produce a plate made of dense silicon carbide or porous silicon carbide. .
Normally, the obtained plate-shaped body is processed to produce a first polishing table of the present invention having a predetermined diameter and a predetermined thickness. At this time, the surface on the side facing the object to be polished may be polished or the like to make the surface uniform or have a predetermined surface roughness.
[0044]
The polishing table according to the first aspect of the present invention is made of a conductive ceramic and has high mechanical strength. Therefore, even if the substrate is made thin, it is unlikely to cause warpage or distortion.
Further, when the polishing table of the first present invention is made of dense ceramic, its rigidity becomes very excellent, and when polishing a workpiece having a very large surface to be polished, Even if the thickness is not so large, no warping or distortion occurs. In addition, it is relatively lightweight, can be easily manufactured, and has excellent handleability.
[0045]
Further, when the polishing table of the first invention is made of a porous ceramic having openings, the polishing table of the object to be polished is polished using the polishing table of the first invention. The electrolytic solution to be supplied between the polishing table of the present invention and the surface to be polished can be supplied through the opening, and uniformly over the entire surface to be polished of the object to be polished, It can be supplied at a constant rate.
When the object to be polished such as a semiconductor wafer is electrolytically polished by using the polishing apparatus using the polishing table of the first invention, the surface to be polished of the object to be polished can be polished extremely flat.
[0046]
Next, a method of electrolytic polishing using the polishing table 10 of the present invention will be described. As shown in FIG. 2, in the polishing apparatus including the polishing table 10 of the present invention, the polishing apparatus is covered with an electrolytic solution 14 made of concentrated phosphoric acid, concentrated sulfuric acid, or the like so as to face the polishing table 10. An abrasive 15 is provided.
[0047]
In the above polishing apparatus, when the polishing table 10 is made of a porous ceramic having an opening, the electrolytic solution 14 flows out of the upper surface of the polishing table 10 through the opening from below the polishing table 10 to be polished. It is supplied between the table for use 10 and the object 15 to be polished. On the other hand, when the polishing table 10 is made of a dense ceramic, since the electrolytic solution cannot pass through the inside of the substrate, a supply pipe capable of supplying the electrolytic solution between the polishing table and the workpiece is attached. An electrolytic solution is supplied from the supply pipe.
[0048]
Actually, when performing the electrolytic polishing of the surface to be polished of the object to be polished 15, the polishing table 10 and the object to be polished 15 are arranged as described above, and then the polishing table 10 and the object to be polished 15 are The gap is filled with the polishing liquid 14, and a voltage is applied between the polishing object 15 such as a silicon wafer and the polishing table 10. The distance between the polishing table 10 and the polishing object 15 is set to be extremely small, and the potential difference between the polishing object 15 and the polishing table 10 causes the surface of the polishing object 15 to be polished to be polished. The oxidation reaction proceeds, and the surface to be polished is electrolytically polished to become an extremely flat surface. At this time, the object to be polished 15 and / or the polishing table 10 may be rotated so that the electrolytic polishing process proceeds uniformly over the entire surface.
[0049]
Further, a shielding plate may be interposed between the object to be polished and the polishing table. The shielding plate may be provided with a support member on a polishing apparatus or a polishing table constituting the polishing apparatus, and may be supported by the support member.
Since the surface is flattened by the above-mentioned electrolytic polishing, scratches and the like do not remain on the surface to be polished. Further, by providing the shielding plate, it is possible to uniformly perform the electrolytic polishing as a whole.
[0050]
Next, a polishing table according to a second embodiment of the present invention will be described.
The polishing table according to the second aspect of the present invention is a polishing table that constitutes a polishing apparatus and performs electrolytic polishing of a surface to be polished of an object to be polished, which is disposed via an electrolytic solution so as to face the surface thereof. The polishing table includes a substrate made of ceramic and a conductor layer formed on a surface of the substrate and functioning as a cathode of a polishing apparatus.
[0051]
FIG. 3 is a perspective view schematically showing an example of the polishing table of the second invention, and FIG. 4 is a schematic view showing a relationship between the polishing table and the object to be polished when performing the electrolytic polishing. FIG.
[0052]
As shown in FIG. 3, the polishing table 20 according to the second embodiment of the present invention includes a disc-shaped substrate 21 on one surface of which a conductor layer 22 of substantially the same size is formed by lamination. Are formed with a large number of bottomed holes 23 penetrating the conductor layer 22 and exposing the surface of the substrate 21 on the bottom surface thereof.
[0053]
The material of the conductor layer is not particularly limited as long as it exhibits good conductivity, and examples thereof include metals.
The metal is not particularly limited, and examples thereof include copper, silver, gold, platinum, tantalum, and titanium. Further, it is preferable that these metals are more noble than copper. This is because dissolution, corrosion, and the like by the electrolytic solution are unlikely to occur.
[0054]
A desirable upper limit of the thickness of the conductor layer is 500 μm, and a lower limit thereof is 0.1 μm. A more desirable upper limit of the thickness of the conductor layer is 50 μm, and a more desirable lower limit is 0.2 μm.
[0055]
The lower limit of the resistivity of the conductor layer is 10 ^-8 Ω · cm is desirable, and the upper limit is 10 ^-4 Ω · cm is desirable. A more desirable lower limit of the resistivity of the conductor layer is 10 ^-7 Ω · cm, and a more desirable upper limit is 10 ^-5 Ω · cm.
[0056]
The upper limit of the diameter of the bottomed hole 23 is preferably 2 mm, and the lower limit is preferably 1 μm. Further, a more desirable upper limit of the diameter of the bottomed hole 23 is 200 μm, and a more desirable lower limit is 10 μm.
Also, this bottomed hole 23 is 100 mm ² The upper limit of the number that is desirably present therein is 50,000, and the lower limit is two. Also, 100mm ² The upper limit of the number more preferably present in the metal is 1000, and the lower limit of the number is more preferably 5.
Further, the bottomed hole 23 is formed substantially uniformly in a portion excluding the outer edge of the polishing table 10, but may be formed unevenly on the surface of the polishing table 10, for example.
[0057]
It is desirable that the corner of the conductor layer on the side of the object to be polished is chamfered.
The corner of the conductor layer on the side of the object to be polished, in other words, refers to the uppermost edge of the bottomed hole provided in the polishing table.
The corners are parts that are easily consumed or chipped during the electropolishing, and if the shapes of the corners are different during the electropolishing, the flow of ions and the like in the electrolytic solution may occur. Is different, and the electropolishing conditions are changed. However, if the corners are chamfered, the electropolishing conditions are hardly changed, so that the electropolishing can be performed under stable conditions.
[0058]
When the substrate is made of a dense body, bubbles tend to remain inside the bottomed hole due to the small diameter of the bottomed hole being 1 μm to 2 mm. If air bubbles remain inside the bottomed hole, the resistance value will be different between the portion where the air bubbles are present and the other portions, and the electropolishing conditions will change, but the corners are chamfered. In this case, air bubbles are easily removed, and air bubbles and the like hardly remain in the bottomed hole.
[0059]
When the substrate is made of a porous ceramic having openings, the polishing table and the surface to be polished are polished using the polishing table of the second aspect of the present invention. Can be supplied through the opening of the substrate and the bottomed hole formed in the conductor layer, and the electrolytic solution is uniformly and uniformly supplied to the entire surface of the object to be polished at a constant rate. Liquid can be supplied.
[0060]
On the other hand, when the substrate is made of dense ceramic, it is not necessary to form a bottomed hole in the conductor layer. It may be. Further, by forming a bottomed hole or the like in the conductor layer, the conductor layer may function as a shielding plate.
[0061]
When the substrate is made of dense ceramic, the polishing table of the present invention has very excellent rigidity. Therefore, for example, when polishing an object to be polished having a very large surface to be polished, it is not necessary to make the thickness of the polishing table of the present invention too large. Therefore, it is relatively lightweight, can be easily manufactured, and has excellent handleability.
[0062]
The substrate is made of a ceramic, but may be a conductive ceramic or an insulating ceramic.
The case where the substrate is made of a conductive ceramic has been described in the first aspect of the present invention, and the description is omitted here.
[0063]
The insulating ceramic is not particularly limited, and examples thereof include a nitride ceramic, a carbide ceramic, and an oxide ceramic.
In addition, among the above-mentioned ceramic materials, there is also a material that is known to have conductivity under predetermined conditions or the like, but is used as a material constituting the insulating layer in the polishing table of the present invention. Each of the ceramic materials indicates an insulating material under the condition of performing the electropolishing, or has a very high resistance value and almost functions as an insulating material.
[0064]
The nitride ceramic is not particularly limited, and examples thereof include aluminum nitride, silicon nitride, boron nitride, and titanium nitride. These may be used alone or in combination of two or more.
[0065]
The carbide ceramic is not particularly limited, and examples thereof include silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, and tungsten carbide. These may be used alone or in combination of two or more.
[0066]
Further, the oxide ceramic is not particularly limited, and examples thereof include alumina, silica, zirconia, cordierite, and mullite. These may be used alone or in combination of two or more.
[0067]
When the substrate is made of dense ceramic, a desirable upper limit of the thickness is 50 mm, and a lower limit thereof is 10 mm. On the other hand, when the substrate is made of porous ceramic, a desirable upper limit of the thickness is 100 mm, and a lower limit thereof is 10 mm.
[0068]
The dense ceramic can be manufactured by making the particle size of the powder as a raw material uniform, producing a high-density molded body using granules or the like, and firing while applying pressure during firing. . Hereinafter, a dense silicon carbide sintered body will be described as an example.
[0069]
The average particle diameter of the silicon carbide particles constituting the dense silicon carbide sintered body is desirably 1 to 100 μm. This is because the above-described substrate can be a dense silicon carbide sintered body having excellent bending strength.
The porosity of the dense silicon carbide sintered body is preferably 5% or less, and more preferably 1% or less. The Young's modulus is desirably 100 to 600 GPa.
[0070]
The porous ceramic is to use a powder obtained by mixing two kinds of powders having different particle diameters, to perform sintering using a material having a not so large effect as a sintering aid, without applying pressure during sintering, It can be produced by firing under mild conditions. Hereinafter, a porous silicon carbide sintered body will be described as an example.
[0071]
The porosity of the substrate made of the porous silicon carbide sintered body is desirably 10 to 60%. When the porosity is less than 10%, it is difficult to allow the electrolyte to pass through the inside of the substrate smoothly. On the other hand, when the porosity exceeds 60%, the mechanical strength may be reduced. . Further, when the strength of the substrate is reduced, the substrate may be easily broken by thermal shock or vibration.
[0072]
The substrate made of the porous silicon carbide sintered body desirably has a Young's modulus of 20 to 350 GPa. If it is less than 20 GPa, the mechanical strength is too low, and there is a possibility that breakage or the like may occur during use as an electropolishing table. On the other hand, it is difficult to ensure a strength exceeding 350 GPa while securing a predetermined porosity. .
[0073]
The pore diameter of the substrate made of the porous silicon carbide sintered body is desirably 0.1 to 50 μm. If the pore diameter is less than 0.1 μm, it becomes difficult to allow the electrolyte to pass smoothly through the inside of the substrate, while if it exceeds 50 μm, the mechanical properties such as the Young's modulus of the substrate are kept at the above values. Becomes difficult.
[0074]
It is desirable that a shielding plate is formed on or above the polishing table of the second invention, as in the first invention. Since the material and the like of the shielding plate have been described in the first present invention, the description is omitted here. The method of arranging the shielding plate is almost the same as that of the first embodiment of the present invention. However, when the shielding layer is formed on the conductor layer when the bottomed hole is formed in the conductor layer, the arrangement method is effective. It must be formed to avoid the bottom hole.
[0075]
The polishing table of the second aspect of the present invention comprises a substrate made of ceramic and a conductor layer formed on the surface of the substrate and functioning as the cathode, and has a high mechanical strength. However, warping and distortion are unlikely to occur.
Further, when the substrate of the polishing table of the second invention is made of a dense ceramic, its rigidity becomes very excellent, and when polishing an object to be polished having a very large surface to be polished, In addition, even if the thickness is not so large, no warping or distortion occurs. In addition, it is relatively lightweight, can be easily manufactured, and has excellent handleability.
[0076]
Further, when the substrate of the polishing table of the second invention is made of a porous ceramic having openings, polishing of the surface to be polished of the object to be polished is performed using the polishing table of the second invention. When performing, the electrolytic solution to be supplied between the polishing table of the second present invention and the surface to be polished, can be supplied through the bottomed hole formed in the opening and the conductor layer, It can be uniformly supplied at a constant speed over the entire surface to be polished of the object to be polished. Therefore, when the object to be polished such as a semiconductor wafer is subjected to electrolytic polishing by using the polishing apparatus using the polishing table of the second invention, the surface to be polished of the object to be polished can be polished extremely flat. .
[0077]
Next, a method of manufacturing the polishing table according to the second embodiment of the present invention will be described.
First, a substrate constituting a polishing table is manufactured. The method of manufacturing a substrate made of dense silicon carbide or porous silicon carbide is substantially the same as that of the first invention, and therefore the description thereof will be omitted here, but the manufacturing method of the second invention will be omitted. The dense silicon carbide or the porous silicon carbide may be an insulator.
When manufacturing a substrate made of an insulator, a dense silicon carbide or a porous silicon carbide is manufactured in substantially the same manner as the method of manufacturing a conductive ceramic except that additives for imparting conductivity are not added. Can be manufactured.
[0078]
After manufacturing the substrate, a conductor layer is formed on the substrate.
The method for forming the conductor layer is not particularly limited, and examples thereof include a PVD method such as vacuum deposition, sputtering, and ion plating. Further, the conductor layer may be a single layer, or a plurality of different types of conductor layers may be formed.
[0079]
After forming the conductor layer on the entire surface of the substrate in this way, if necessary, bottomed holes having a specific diameter are formed at a plurality of specific locations. The shape of the bottomed hole to be formed in plan view is not particularly limited, and includes, for example, any shape such as a circle, an ellipse, and a polygon. Further, the wall surface of the bottomed hole is formed on the upper surface of the conductor layer. May be perpendicular to or may have a slope.
The method for forming the bottomed hole is not particularly limited.For example, the bottomed hole may be formed using a cutting device or the like, and the bottomed hole is formed by disassembling an unnecessary portion using a laser. You may. Further, the bottomed hole may be formed by blasting such as sand blasting.
[0080]
Also, in some cases, using a screen printing or the like, an insulating layer of a predetermined pattern including a circular non-coated portion is formed on a substrate, and a conductive layer of the same pattern is formed thereon using a mask or the like. Good.
[0081]
The electrolytic polishing method using the above-mentioned polishing table is the same as in the first embodiment of the present invention, and the description thereof will be omitted.
Since the surface is flattened by the above-mentioned electrolytic polishing, scratches and the like do not remain on the surface to be polished. Further, by providing the shielding plate, it is possible to uniformly perform the electrolytic polishing as a whole.
[0082]
The polishing table of the present invention constitutes a polishing apparatus and is used when performing the electrolytic polishing of the polished surface of the object to be polished using the polishing apparatus. However, the object to be polished is not particularly limited. Instead, for example, a metal wiring circuit such as copper formed on a semiconductor element, a silicon wafer before forming a semiconductor element, and the like, which have been conventionally subjected to electrolytic polishing, may be used.
[0083]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
[0084]
Example 1
6 parts by weight of a phenol resin, 5 parts by weight of an acrylic resin (Licabond manufactured by Chuo Rika Kogyo Co., Ltd.), 124 parts by weight of methanol, B based on 100 parts by weight of silicon carbide powder having an average particle size of 50 μm ₄ After mixing 0.7 parts by weight of C, the mixture was mixed in a ball mill for 5 hours to obtain a uniform mixed composition. After drying the mixed composition for a predetermined time to remove water to some extent, an appropriate amount of the dried mixed composition was collected and granulated by a spray drying method. At this time, the water content of the granules was adjusted to be about 0.8% by weight.
[0085]
When granulating the mixed composition by the spray drying method, it was confirmed that granules produced in the past did not remain on the tower wall to be granulated by blowing hot air, and that impurities were contained in the produced granules. The above-mentioned mixed composition was granulated with particular care so as not to mix.
[0086]
Next, the granules were heat-treated using a dryer at a heating temperature of 80 ° C. and a heating time of 5 hours.
Then, after the granules of the mixed composition are put into a mold, a disc-shaped silicon carbide molded body is held at a pressure of 96 MPa for 5 minutes using a molding machine utilizing cold isostatic pressure (CIP). Was formed.
[0087]
Next, the silicon carbide molded body is fired by heating to 2200 ° C. to produce a dense silicon carbide sintered body, and a substrate having a diameter of 600 mm and a thickness of 40 mm is cut out and polished to obtain a conductive ceramic. Was manufactured.
[0088]
Example 2
First, a substrate made of a porous silicon carbide sintered body was manufactured by processing SCP-02 (porosity 25%, pore diameter 8 μm, Young's modulus 80 GPa) manufactured by Ibiden Co., Ltd. to a diameter of 600 mm and a thickness of 40 mm.
[0089]
Next, a solution in which an epoxy resin was dissolved was spin-coated on the substrate, and after closing the opening, the epoxy resin layer on the surface was removed to prepare a substrate in which only the opening portion was filled with the epoxy resin.
[0090]
Next, Ti was sputtered to form a conductor layer having a thickness of 0.5 μm.
Next, using a YAG laser, a large number of bottomed holes (diameter 60 μm) are formed at a rate of 200 to 300 pieces / sec so that the distance connecting the centers thereof is 120 μm, and a polishing table is manufactured. finished. The epoxy resin filled in the opening was decomposed and removed by heating the substrate.
[0091]
Example 3
A polishing table was manufactured in the same manner as in Example 1 except that SCR-302 (Young's modulus: 340 GPa) manufactured by Ibiden was used as the conductive dense silicon carbide sintered body.
[0092]
Example 4
Porous silicon carbide was used in the same manner as in Example 1 except that SCP-5 (porosity: 40%, Young's modulus: 340 GPa, pore diameter: 2 μm) manufactured by IBIDEN was used as the conductive porous porous sintered body. Was manufactured.
[0093]
Comparative Example 1
A polishing table made of copper having a diameter of 600 mm and a thickness of 40 mm was manufactured.
[0094]
An insulating layer (oxide film) was formed on the surface of the silicon wafer, a groove of a wiring pattern was formed in the insulating layer by a photolithography process, and copper was plated in the groove to form a copper wiring.
[0095]
The silicon wafer on which the copper wiring was formed was used as an object to be polished, and the object to be polished and the polishing tables manufactured in Examples 1 to 4 and Comparative Example 1 were arranged as shown in FIG. Electropolishing of the surface of the copper wiring was performed by the method described in the embodiment. That is, the surface to be polished of the object to be polished is composed of an insulating layer and copper wiring, and the portion to be polished on the surface to be polished is a copper wiring portion.
[0096]
The voltage applied between the silicon wafer and the polishing table was 100 V, and a sulfuric acid aqueous solution was used as the electrolytic solution. When electrolytic polishing was performed using the polishing table according to Example 3, the electropolishing was performed by disposing a shielding plate made of a SUS metal net between the polishing table and the silicon wafer. .
Then, the flatness of the polished surface made of the insulating layer and the copper wiring after the electrolytic polishing and the presence or absence of scratches were examined by the following methods.
[0097]
Measuring flatness
The flatness of the polished surface after the electrolytic polishing was measured using fluorescent X-rays.
The flatness refers to the difference between the most protruding part and the most depressed part on the surface to be polished after the electrolytic polishing.
In addition, the flatness of the surface to be polished of the object to be polished before the electrolytic polishing was measured using fluorescent X-rays.
[0098]
Observation of scratches
The polished surface after the electrolytic polishing was observed using an electron microscope (SEM).
The results are shown in Table 1 below.
[0099]
[Table 1]

[0100]
As is clear from the results shown in Table 1, the flatness of the polished surface on which the electrolytic polishing was performed using the polishing tables according to Examples 1 to 4 was 50 to 100 nm, and the flatness before the electrolytic polishing. Polishing was extremely flat compared to the surface to be polished.
Also, no scratches due to electrolytic polishing were observed on the polished surface according to any of the examples.
Furthermore, the polishing tables according to Examples 1 to 4 were hardly warped or distorted, were light, could be easily replaced, and were excellent in handleability.
[0101]
On the other hand, the surface to be polished on which the electrolytic polishing was performed using the polishing table according to Comparative Example 1 had no scratches due to the electrolytic polishing, but the flatness was 300 nm, and the flatness was 300 nm. , Compared to the example.
Further, the polishing table according to Comparative Example 1 had larger warpage and distortion than the polishing table according to the example, was heavy, was difficult to replace, and was inferior in handleability.
[0102]
【The invention's effect】
Since the polishing table of the present invention is configured as described above, when the object to be polished is electrolytically polished using the polishing apparatus of the present invention using the polishing table, the surface to be polished of the object to be polished is extremely reduced. Electropolishing can be performed flat, and even if the diameter is increased, warping or distortion hardly occurs. Therefore, thinning and weight reduction can be achieved.
[Brief description of the drawings]
FIG. 1 is a perspective view schematically showing one example of a polishing table of the first invention.
FIG. 2 is a cross-sectional view showing the relationship between the polishing table and the object to be polished when the object to be polished is electropolished using the polishing table of the first invention.
FIG. 3 is a perspective view schematically showing one example of a polishing table of the second invention.
FIG. 4 is a cross-sectional view showing a relationship between a polishing table and an object to be polished when electrolytic polishing of the object to be polished using the polishing table of the second invention.
[Explanation of symbols]
10, 20 Polishing table
14 Electrolyte
15 Object to be polished
21 Substrate
22 conductor layer
23 bottomed hole

Claims (13)

A polishing table that constitutes a cathode of a polishing apparatus and performs electrolytic polishing of a surface to be polished of an object to be polished, which is disposed via an electrolytic solution so as to face the surface thereof, wherein the polishing table is a conductive table. A polishing table characterized by being made of conductive ceramic. The polishing table according to claim 1, wherein the polishing table is made of dense ceramic. The polishing table according to claim 1, wherein the polishing table is made of a porous ceramic. The polishing table according to claim 1, wherein the resistivity is 10 ⁻³ to 10 ⁷ Ω · cm. The polishing table according to claim 3, wherein the pore diameter is 0.1 to 50 μm. The polishing table according to any one of claims 3 to 5, wherein the porosity is 10 to 60%. The polishing table according to any one of claims 1 to 6, wherein the conductive ceramic is made of SiC having conductivity and corrosion resistance. A polishing table that constitutes a polishing apparatus and performs electrolytic polishing of a surface to be polished of an object to be polished disposed via an electrolytic solution so as to face the surface thereof,
The polishing table includes a substrate made of ceramic and a conductor layer formed on a surface of the substrate and functioning as a cathode of a polishing apparatus. 9. The polishing table according to claim 8, wherein the substrate is made of dense ceramic. 9. The polishing table according to claim 8, wherein the substrate is made of a porous ceramic. The polishing table according to claim 8, wherein the substrate has a resistivity of 10 ⁻³ to 10 ⁷ Ω · cm. The polishing table according to claim 10, wherein a pore diameter of the substrate is 0.1 to 50 μm. The polishing table according to any one of claims 10 to 12, wherein the porosity of the substrate is 10 to 60%.

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