JPH11156718A - Grinding device and grinding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent flocculation of abrasive grain by improving dispersibility of abrasive grain in abrasive slurry by providing an abrasive slurry supplying means with an electric field impressing means for abrasive slurry. SOLUTION: An electric field impressing means 18 is provided on an abrasive slurry supply tank 15 (or supply nozzle 16). The electrode constitution is made a constitution in which a capacitive coupling by a that plate electrode or an inductive coupling by a coiled electrode and an antenna are used. As the power source, ac is mainly used from a point of view of dispersion efficiency of abrasive slurry of dc or ac. Electric field of a prescribed frequency is impressed in the abrasive slurry supply tank 15 and abrasive slurry 17 is supplied to a grinding pad 14. Thus, flocculation of abrasive grain is prevented, abrasive slurry having excellent dispersibility is supplied to the grinding pad 14 and generation of a grinding flaw such as a scratch flaw can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus and a polishing method, and more particularly to a polishing apparatus and a polishing method capable of performing stable polishing by preventing polishing flaws such as scratches.

[0002]

2. Description of the Related Art The degree of integration of semiconductor devices such as LSIs has increased.
As the design rules are refined from sub-half micron to quarter micron, the pattern width of the internal wiring is also being reduced. On the other hand, in order to keep the wiring resistance at a low level and prevent signal propagation delay and various migrations, it is necessary to secure a cross-sectional area of the wiring. That is, since the height of the wiring cannot be reduced so much, the aspect ratio of the wiring tends to increase. In general, even on the same semiconductor chip, a region where the wiring density is dense and a region where the wiring density is sparse are mixed.

In order to form a multilayer wiring structure having such fine wiring as a lower layer, a flattening interlayer insulating film is formed so as to fill a step or a recess formed by the lower wiring to secure a flat surface. It is necessary to repeat the process of forming the upper layer wiring thereon. This is because the DOF (Depth of Depth of Exposure) associated with the shortening of the exposure light wavelength and the increase in the NA of the lens in lithography for resist patterning, as well as improving the step coverage of the upper wiring,
Focus) is also important from the viewpoint of compensating for the decrease. As an example, in order to pattern a line and space of 0.25 μm rule with good controllability by KrF excimer laser stepper exposure with a wavelength of 248 nm, the surface step of the exposed surface is required to be 0.2 to 0.3 μm or less.

Conventionally, various methods for forming a planarized interlayer insulating film have been developed. These forming methods are roughly divided into improving the self-flow characteristics by optimizing the film forming conditions,
Alternatively, the surface flatness is improved by reflow heat treatment after film formation. In any of the methods, there is room for improvement with respect to the flat shape of the interlayer insulating film in a stepped recess having a wide wiring interval and the prevention of voids in the interlayer insulating film in a portion having a narrow wiring interval.

Therefore, as a method of flattening an interlayer insulating film or the like having a step by post-processing, a chemical mechanical polishing (CM) using a mirror polishing method of a silicon wafer has recently been applied.
P: Chemical Mechanical Polishing) has been proposed. This chemical mechanical polishing method is regarded as promising as a method that can collectively flatten various steps on a target substrate once formed.

FIG. 4 is a schematic sectional view showing a conventional chemical mechanical polishing apparatus. In the figure, the rotating carrier 12
The substrate 11 to be polished with the polished surface facing downward is set so as to face a platen 13 which is also a rotating polishing platen. On the surface of this platen 13,
The polishing pad 14 is stuck. On the other hand, a polishing slurry 17 is supplied from a polishing slurry supply tank 15, which is a main component of the polishing slurry supply means, to a polishing pad 14 on a platen 13 via a polishing slurry supply nozzle 16. In this state, the substrate 11 to be polished is pressed against the polishing pad 14 with a predetermined pressure to perform polishing. At this time, the carrier 12 and the platen 1
One point is to optimize the adjustment of the number of rotations and the rotation axis, and to select a polishing slurry suitable for the substrate to be polished. As an example, when polishing a silicon oxide-based interlayer insulating film, a chemical reaction and mechanical polishing are used in combination using a dispersion medium such as a KOH aqueous solution in which silica fine particles having a particle diameter of about 10 nm are suspended as polishing particles. Perform CMP.

[0007]

The flattening method by the chemical mechanical polishing method has problems to be solved for practical use. One of them is a polishing flaw such as a scratch flaw which is generated on the surface of the substrate to be polished. For example, if such scratches occur on the surface to be polished such as an interlayer insulating film, when a wiring made of an Al-based metal or the like is formed thereon in a later step, a step breakage or the like occurs at the scratches and electromigration. There is a possibility that a decrease in reliability such as a deterioration in resistance occurs. HDD (Hard Disk)
When scratches occur during polishing of a non-magnetic substrate for Drive, etc., this may cause a loss of reproduced signal such as dropout.

The generation of scratches is considered to be caused by agglomerates due to poor dispersion of abrasive particles. In particular, a polishing slurry that employs alumina as abrasive particles, which is used for CMP of a metal film, has poor dispersibility, and as a countermeasure against this, a CMP device provided with a motor-driven stirring device so that the abrasive particles do not settle has been proposed. . However, even with such mechanical dispersing means, the dispersibility of the abrasive particles is not sufficient, and the scratches have not been completely prevented.

An object of the present invention is to solve the above-mentioned problems. That is, an object of the present invention is to improve the dispersibility of abrasive particles in a polishing slurry, or to maintain good dispersion and prevent agglomeration of abrasive particles, thereby preventing the occurrence of scratches and the like on the surface of a substrate to be polished. Accordingly, an object of the present invention is to provide a polishing apparatus and a polishing method capable of performing stable and high-precision polishing with a high yield.

[0010]

SUMMARY OF THE INVENTION A polishing apparatus according to the present invention is proposed to achieve the above-mentioned object, and comprises a polishing platen to which a polishing pad is attached, a polishing slurry supplied to the polishing pad, Polishing slurry supply means including a polishing slurry supply tank and a polishing slurry supply nozzle, and a polished substrate gripping means for gripping a substrate to be polished and pressing against a surface of a polishing pad, and relatively moving the substrate to be polished and the polishing platen. The polishing slurry supply means further includes an electric field applying means for the polishing slurry.

In the polishing method of the present invention, a polishing slurry is supplied from a polishing slurry supply means including a polishing slurry supply tank and a polishing slurry supply nozzle to a polishing platen to which a polishing pad is attached. And pressing the polishing pad against the surface of the polishing pad, the polishing method comprises a polishing step of polishing the surface of the substrate to be polished by relatively moving the substrate to be polished and the polishing platen, this polishing slurry supply step ,
The method further comprises the step of applying an electric field to the polishing slurry.

The electric field applied to the polishing slurry in the present invention is desirably an AC electric field.

In the present invention, the electric field is preferably applied to the polishing slurry in a polishing slurry supply tank or a polishing slurry supply nozzle.

Next, the operation will be described. The polishing slurry is
Usually, it is a suspension in which abrasive particles are dispersed in a dispersion medium of an acidic or alkaline aqueous solution. Therefore, the surface of the abrasive particles forms an electric double layer in the suspension and floats in a charged state. By applying an electric field from outside in this state, the movement of the abrasive particles is accelerated, and a good dispersion state is maintained or aggregation is prevented. This prevents scratches and the like from occurring due to the aggregates.

[0015]

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

First, an example of a configuration in which the polishing apparatus of the present invention is applied to a chemical mechanical polishing apparatus used in a manufacturing process of a semiconductor device will be described with reference to FIGS.

The polishing apparatus shown in FIG. 1 has a polishing slurry supply tank 15 and a polishing slurry supply nozzle 16 which are main components of the polishing slurry supply means, and is provided with an electric field applying means 18 in the polishing slurry supply tank 15. is there. The polishing apparatus shown in FIG. 2 has an electric field applying means 19 provided in the polishing slurry supply nozzle 16 of the polishing slurry supply tank 15 and the polishing slurry supply nozzle 16 which are main components of the polishing slurry supply means. In this case, the electric field applying means 19 may be provided at any part of the pipe from the polishing slurry supply tank 15 to the discharge end of the polishing slurry supply nozzle 16. As an apparatus configuration, an electric field applying unit 18 may be provided in both the polishing slurry supply tank 15 and the polishing slurry supply nozzle 16. In any of the apparatuses, the polishing slurry supply means may circulate the polishing slurry 17 or use it disposably. In any of the apparatuses, the configuration is the same as that of the conventional polishing apparatus described with reference to FIG.

The electrode configuration of the electric field applying means 18 shown is, for example, capacitive coupling by a pair of plate electrodes. However, an electric field effective for polishing slurry, such as an inductive coupling configuration using coiled electrodes or a configuration using an antenna, is used. Any type can be used as long as it can apply. As a power source for the electric field applying means, either a direct current or an alternating current may be used. Here, as an example, a 50 Hz AC power supply of a commercial power supply was used. The applied voltage is a design item that depends on the electrode configuration of the electric field applying unit 18, for example, the distance between the electrodes, and a voltage range in which inter-electrode discharge or the like does not occur, for example, several tens of volts to several thousand volts is selected. The frequency in the case of AC is selected from the range of several Hz to RF (Radio Frequency).

[0019]

EXAMPLES Hereinafter, the polishing method of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1 A polishing slurry prepared by suspending silica fine particles having an average particle diameter of 10 nm in aqueous ammonia and adjusting the pH to 10.0 was used. The amount of silica fine particles in the polishing slurry was 30% by weight. An electric field of 50 Hz is applied to the polishing slurry supply tank 15 using the polishing apparatus shown in FIG.
Is supplied with a polishing slurry 17. When the particle size distribution was determined by observation of the polishing slurry 17 with an electron microscope and image processing, the average particle size of the polishing particles was 50 n without electric field application.
Although an agglomerate was observed at m, the average particle size became 10 nm by application of an electric field, and improvement in dispersibility was confirmed.

FIGS. 3A to 3C are schematic sectional views showing steps of the polishing method of the present invention. That is, as shown in FIG. 3A, a lower interlayer insulating film 2 such as silicon oxide and an Al-based metal or the like are formed on a semiconductor substrate 1 such as silicon on which an element group (not shown) such as a MOS transistor is formed. Wiring 3
Was formed. As further shown in FIG. 3 (b), SiH ₄
The N ₂ O by plasma CVD conventional method for the raw material gas to form an upper interlayer insulating film 4 made of silicon oxide and,
This was used as the substrate 11 to be polished. The surface of the upper interlayer insulating film 4 has an uneven shape reflecting the line and space of the wiring 3.

The substrate 11 to be polished shown in FIG.
1 is held face down on the carrier 12 of the polishing apparatus shown in FIG.
The upper interlayer insulating film 4 was polished while applying an electric field of 50 Hz to. An example of the polishing conditions is shown below. Carrier rotation speed 30 rpm Platen rotation speed 30 rpm Polishing pressure 300 g / cm ² hours 180 sec Note that the polishing pad is an IC1000 / suba400 (manufactured by Rodel) in which a non-woven fabric is laminated below foamed polyurethane.
Was used.

FIG. 3C shows a state after the polishing is completed. The unevenness on the surface of the upper interlayer insulating film 4 was flattened, and no polishing flaws such as scratch flaws were found by observation with a scanning electron microscope. On the other hand, when the upper interlayer insulating film 4 was polished without applying an electric field to the polishing slurry supply tank 15, many scratches were generated. In the case where an electric field was applied to the polishing slurry supply nozzle 16 using the polishing apparatus shown in FIG. 2, no polishing flaws such as scratches were found.

Example 2 A polishing slurry in which alumina fine particles having an average particle diameter of 10 nm were suspended in an aqueous potassium hydroxide solution was used.
The amount of alumina fine particles in the polishing slurry was 35% by weight. Using the polishing apparatus shown in FIG.
A polishing slurry 17 is supplied to the polishing pad 14 by applying an electric field of 50 Hz to the tip. When the particle size distribution was obtained by observing the polishing slurry 17 with an electron microscope and by image processing, the average particle size of the abrasive particles was 50 nm without application of an electric field, and agglomerates were observed.
nm, and the dispersibility was improved.

The substrate 11 to be polished in this embodiment is the same as that in the first embodiment. However, as the upper interlayer insulating film 4 shown in FIG. SiOF) was used. An example of the plasma CVD film forming conditions of SiOF using an ECR plasma CVD apparatus will be described. SiF ₄ 80 sccm SiH ₄ 40 sccm O ₂ 100 sccm Ar 50 sccm Pressure 1.0 Pa Microwave power 2000 W (2.45 GHz) RF power 2000 W (13.56 MHz) Substrate temperature 200 ° C. Upper interlayer insulating film 4 made of SiOF Also has an uneven shape reflecting the line and space of the wiring 3.

The substrate 11 to be polished shown in FIG.
Then, the upper interlayer insulating film 4 was polished while applying a 50 Hz electric field to the polishing slurry supply nozzle 16 while gripping the carrier 12 of the polishing apparatus shown in FIG. An example of the polishing conditions is shown below. Carrier rotation speed 30 rpm Platen rotation speed 30 rpm Polishing pressure 250 g / cm ² hours 150 sec The polishing pad used was IC1000 / suba400 (manufactured by Rodel) in which a nonwoven fabric was also laminated on the lower part of foamed polyurethane.

FIG. 3C shows a state after the polishing is completed. Irregularities on the surface of the upper interlayer insulating film 4 were flattened, and no polishing flaws such as scratches were found by observation with a scanning electron microscope. On the other hand, when the upper interlayer insulating film 4 was polished without applying an electric field to the polishing slurry supply nozzle 16, many scratches were generated. In the case where an electric field is applied to the polishing slurry supply tank 15 using the polishing apparatus shown in FIG.
Similarly, no polishing flaws such as scratch flaws were found.

Although the present invention has been described with reference to the two embodiments, the present invention is not limited to these embodiments.

For example, although a chemical mechanical polishing apparatus is taken as an example of the polishing apparatus, the present invention can be applied to a simple mechanical polishing apparatus that does not involve a chemical reaction. Although an inorganic alkaline dispersion medium such as aqueous ammonia or potassium hydroxide is used as a dispersion medium for the polishing slurry, an organic alkaline dispersion medium such as an organic amine or a derivative thereof may be used. Similar effects can be obtained with an acidic dispersion medium such as an inorganic acid or an organic acid. In addition, a stabilizer, a pH buffer, an oxidizing agent, or the like may be added to the polishing slurry depending on the substrate to be polished. For example, an H ₂ O ₂ / KOH aqueous solution-based dispersion medium is suitable for flattening the W layer, and an H ₃ PO ₄ / H ₂ O ₂ aqueous solution-based dispersion medium is used for flattening the Al-based metal layer. It may be used.

As the abrasive particles, silica and alumina are typical, and oxides such as cerium oxide, manganese dioxide, zirconium oxide, titanium oxide, chromium oxide and iron oxide, or sulfates and carbonates of various metals ( Water-insoluble) may be used. It also contributes to improving the dispersibility of a polishing slurry using ultrafine diamond as polishing particles.

As a substrate to be polished, in addition to the silicon oxide-based interlayer insulating film described in the embodiment, an organic SOG (Spin On Glass)
Or BSG (Boro Silicate Glass), PSG (Phos
phoSilicate Glass), BPSG (Boro Phosho Silicat)
e Glass), various glasses such as AsSG (Arseno Silicate Glass), inorganic insulating films such as silicon oxynitride or silicon nitride, organic polymers such as polyimide, organic low dielectric constant polymers such as polyparaxylylene fluoride, etc. It may be. In addition to the interlayer insulating film, it is also suitable for polishing a silicon substrate, polycrystalline silicon, amorphous silicon, or various kinds of refractory metals such as Al-based metals, Cu and W, and silicides thereof. In addition to the semiconductor device manufacturing process, a favorable effect can be obtained for flattening and polishing of Al-based metal substrates for HDDs, polycarbonate substrates for optical disks and magneto-optical disks, ultra-high molecular weight polyolefin substrates, and the like. In addition, it goes without saying that the present invention can be applied to various electronic devices and optical devices that require a flat surface. Others
The configuration and the like of the polishing apparatus may be appropriately changed.

[0032]

As is apparent from the above description, according to the polishing apparatus of the present invention, the provision of the electric field applying means for the polishing slurry supply means prevents the agglomeration of the abrasive particles and improves the dispersibility. The polishing slurry can be supplied to the polishing pad.

Further, according to the polishing method of the present invention, by applying an electric field to the polishing slurry during the polishing slurry supply step, aggregation of the polishing particles is prevented, and the polishing slurry having good dispersibility is supplied to the polishing pad. Thus, the occurrence of polishing flaws such as scratch flaws can be prevented.

According to the above effects, it is possible to perform a process for flattening the surface of a semiconductor device having a high step due to the adoption of a multilayer wiring structure, a process for manufacturing an information recording medium having a high recording density, and the like with high reliability.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one configuration example of a polishing apparatus of the present invention.

FIG. 2 is a schematic sectional view showing another configuration example of the polishing apparatus of the present invention.

FIG. 3 is a schematic cross-sectional view showing the steps of the polishing method of the present invention.

FIG. 4 is a schematic sectional view showing a conventional polishing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Lower interlayer insulating film, 3 ... Wiring, 4 ...
Upper interlayer insulating film 11: substrate to be polished, 12: carrier (grinding means for substrate to be polished), 13: platen (polishing platen), 14: polishing pad, 15: polishing slurry supply tank, 16: polishing slurry supply nozzle, 17 ... polishing slurry, 18, 19 ... electric field applying means

Claims (8)

[Claims] A polishing plate having a polishing pad attached thereto; a polishing slurry supply means including a polishing slurry supply tank and a polishing slurry supply nozzle for supplying a polishing slurry to the polishing pad; A polishing apparatus comprising: a substrate to be polished gripping means for pressing the surface of a polishing pad and relatively moving the substrate to be polished and the polishing platen, wherein the polishing slurry supply means is an electric field applying means for the polishing slurry. A polishing apparatus, further comprising: 2. The polishing apparatus according to claim 1, wherein said electric field applying means is an AC electric field applying means. 3. The polishing apparatus according to claim 1, wherein said electric field applying means is provided in said polishing slurry supply tank. 4. The polishing apparatus according to claim 1, wherein said electric field applying means is provided in said polishing slurry supply nozzle. 5. A step of supplying a polishing slurry from a polishing slurry supply means including a polishing slurry supply tank and a polishing slurry supply nozzle to a polishing platen to which a polishing pad is attached, wherein said polishing is performed by gripping a substrate to be polished. A polishing method comprising: a polishing step of pressing the surface of a pad and relatively moving the substrate to be polished and the polishing platen to polish the surface of the substrate to be polished. A polishing method, further comprising a step of applying an electric field to the slurry. 6. The polishing method according to claim 5, wherein said electric field applying step is an AC electric field applying step. 7. The method according to claim 5, wherein the step of applying the electric field is a step of applying the electric field in the polishing slurry supply tank.
The polishing method as described above. 8. The polishing method according to claim 5, wherein the electric field applying step is a step of applying the electric field in the polishing slurry supply nozzle.