WO1998045089A1

WO1998045089A1 - Manufacturing method, polishing method and polishing device for semiconductor devices

Info

Publication number: WO1998045089A1
Application number: PCT/JP1998/001621
Authority: WO
Inventors: Tetsuo Ookawa; Hiroyuki Kojima; Hidemi Sato; Takashi Nishiguchi
Original assignee: Hitachi, Ltd.
Priority date: 1997-04-09
Filing date: 1998-04-08
Publication date: 1998-10-15

Abstract

A method of manufacturing semiconductor devices involving the polishing step, which realizes a stable finishing removal rate and achieves a reduction of consumption of the polishing pad. In this method, a mixture of grains for scraping out deposition with slurry is fed to the polishing pad and the polishing pad and the workpiece are moved relative to each other. Therefore even if the polishing waste tends to be deposited on the polishing pad, the waste is raked out by the action of the raking grains.

Description

TECHNICAL FIELD Manufacturing method of semiconductor device, polishing method and polishing apparatus

The present invention relates to a method for manufacturing a semiconductor device, a polishing method, and a polishing apparatus. Background art

Today, in the field of semiconductor device manufacturing, the miniaturization of elements and the increase in the number of integrated elements have progressed, and it has become common sense to use multi-layer wiring. In the case of multi-layered wiring, simply overlapping the wiring via the interlayer insulating film causes irregularities on the surface of the interlayer insulating film, which affects the exposure processing and the like. Therefore, how to improve the flatness of the interlayer insulating film (eg, Sio ₂ film) is a major issue in multilayer wiring technology.

As a method of improving the flatness of the interlayer insulating film, for example, a CMP (Chemical Mechanical Polishing) technology in which the surface of the interlayer insulating film is polished using a polishing liquid having a high solid phase reactivity with the interlayer insulating film. Power is known.

In the polishing step using a polishing pad, the working surface of the polishing pad generally deteriorates as the processing time increases. When the work surface of the polishing pad deteriorates, the actual polishing amount becomes smaller than the set polishing amount. Therefore, in the past, con- crete dressing and the like were implemented to prevent the work surface of the polishing pad from deteriorating. In concurrent dressing, a workpiece to be polished and a grindstone for dressing the polishing pad are placed on a rotating polishing pad to polish the workpiece and remove the polishing pad. Dressing will proceed at the same time. Such concurrent dressing can be done by CMP It is also commonly used in equipment.

However, while the above-mentioned concurrent dressing is suitable for stabilizing the polishing efficiency, the polishing pad is greatly consumed by the dressing, and the polishing pad must be replaced in an early cycle. In this case, the cost of the polishing pad is increased, and the burden on the operator is increased. The reason for the high consumption of the polishing pad is that, in concurrent dressing, the surface of the polishing pad is removed together with the deposits using a diamond whetstone.

In addition, the wear of the grinding wheel is severe, and the grinding wheel must be replaced in a fast cycle. In this case, the cost of the grinding wheel is increased, and the burden on the operator is increased. The cause of the high wear of the grinding wheel is that the diamond abrasive grains fixed on the surface of the grinding wheel are worn.

In the dressing method using a grindstone, such as concurrent dressing, abrasive grains fall off the grindstone, and the abrasive grains scratch the surface to be processed. This is a serious problem related to the quality of a semiconductor device when a substrate (wafer) is polished as a semiconductor device manufacturing method.

In addition, in order to perform concurrent dressing, it is necessary to provide a place on the polishing pad where a grindstone is installed so as not to interfere with the wafer. Therefore, it is difficult to reduce the size of the polishing pad. Therefore, it is difficult to reduce the size of the polishing apparatus. This is an important issue related to the effective use of the installation area of a polishing apparatus in a semiconductor device manufacturing line.

On the other hand, if interval dressing is used, it is not necessary to install a wafer and a grindstone on the polishing pad at the same time, so the polishing pad can be downsized.However, deposits on the polishing pad surface during polishing are possible. As the polishing time elapses, the polishing efficiency decreases with the passage of polishing time, and the distribution of the polishing amount in the wafer surface fluctuates. You. This is an important issue related to the quality of semiconductor devices.

When the wafer surface is cut using a force or a byte that grinds the wafer surface using a grindstone, or when the wafer surface is wrapped using a polishing platen, the wafer surface is scratched using a polishing pad. When removing the wafer, the wafer needs to be polished.

If scratches occur on the wafer surface after polishing, the wafer is primarily polished using a polishing pad with a high elastic modulus to remove this scratch, and then a polishing pad with a lower elastic modulus is used. It is necessary to perform secondary polishing using

In order to solve such a problem, an object of the present invention is to provide a method of manufacturing a semiconductor device, a polishing method, and a polishing apparatus, which can obtain a stable polishing efficiency and reduce the consumption of a polishing pad. It is in. Disclosure of the invention

According to one embodiment of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: supplying a slurry to a polishing pad to polish a substrate; The particles for scraping off the deposits on the surface and the slurry are supplied to the polishing pad surface separately or as a mixture, and the surface to be processed of the substrate and the polishing pad surface are relatively positioned. There is provided a method for manufacturing a semiconductor device, which comprises polishing a substrate to be moved.

According to one aspect of the present invention, there is provided a method of manufacturing a semiconductor device having a step of polishing a substrate, wherein a grinding fluid or a slurry is supplied to the surface of the grindstone. The first polishing is performed on the substrate by relatively moving the grindstone and the substrate, and the particles and the slurry for removing the deposits for removing the deposits on the surface of the polishing pad are formed. Are supplied to the surface of the polishing pad separately or as a mixture to relatively move the surface of the polishing pad and the surface to be processed of the substrate, thereby performing the second polishing on the substrate. A method for manufacturing a semiconductor device is provided.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device having a step of polishing a substrate, wherein the slurry is formed on a surface of a polishing plate made of metal or resin. The first polishing is performed on the substrate by moving the polishing platen and the substrate relatively to each other, and the particles and slurry for removing the deposits for scraping the deposits on the surface of the polishing pad are supplied. The second polishing is performed on the substrate by supplying the polishing pad surface separately or as a mixture to the polishing pad surface and relatively moving the polishing pad surface and the processed surface of the substrate. (4) A method for manufacturing a conductive device is provided.

According to another aspect of the present invention, there is provided a semiconductor device manufacturing method for supplying a slurry to a polishing pad and polishing a substrate. The particles for scraping out the deposits on the polishing pad surface and the slurry are supplied separately or as a mixture to the polishing pad surface, and the work surface of the substrate and the polishing pad surface are compared with each other. The first polishing is applied to the substrate, and the polishing pad used in the first polishing step is also subjected to the second polishing using the second polishing pad having a small surface rigidity. A method of manufacturing a semiconductor device, characterized by performing the following.

Further, according to one aspect of the polishing method of the present invention for attaining the above object, in a polishing method using a polishing pad, the particles for removing deposits for removing deposits on the surface of the polishing pad and the slurry are used. Are supplied separately or as a mixture onto the polishing pad surface, and the workpiece and the polishing pad surface are relatively moved while pressing the workpiece surface of the workpiece against the polishing pad surface. Thus, there is provided a polishing method characterized by polishing a workpiece.

Further, according to one embodiment of the polishing apparatus of the present invention for achieving the above object, a mixture of the particles for removing the deposits and the slurry for scraping off the deposits on the surface of the polishing pad is provided on the surface of the polishing pad. A supply device for supplying the workpiece, a holding member that holds the workpiece and presses the workpiece against the surface of the polishing pad, and a device that relatively moves the workpiece and the polishing pad. A polishing apparatus characterized by having at least:

Further, according to one embodiment of the polishing apparatus of the present invention for achieving the above object, a base, a rotatable polishing plate, and a rotation center of the polishing plate provided on the polishing plate and provided on the surface thereof A polishing pad having a plurality of drain passages formed concentrically around a center, wherein the arm is fixed to the base, and the arm is aligned with an arrangement pitch of the plurality of drain passages. A polishing apparatus, comprising: a plurality of scraping pieces attached to a polishing table; wherein each of the plurality of scraping pieces scrapes deposits from each drainage channel when the polishing platen rotates. Is provided.

Further, according to one embodiment of the chemical mechanical polishing apparatus of the present invention for achieving the above object, a chemical mechanical polishing apparatus for chemically and mechanically removing and flattening irregularities on the surface of a workpiece is provided. A supply device for supplying a mixture of the particles for scraping the deposits and the slurry for scraping the deposits on the surface of the polishing pad onto the surface of the polishing pad, holding the workpiece and holding the workpiece. A chemical mechanical polishing apparatus is provided, comprising at least a holding member for pressing against a surface of a polishing pad, and a device for relatively moving the workpiece and the polishing pad. .

Further, according to one embodiment of the polishing method of the present invention for achieving the above object, in a polishing method using a grindstone and a polishing pad, a grinding fluid or a slurry is used. Particles for deposit removal for supplying first to the surface of the grindstone and relatively moving the grindstone and the workpiece to perform the first polishing on the workpiece and scraping the deposit on the polishing pad surface And the slurry are supplied separately or as a mixture to the surface of the polishing pad to move the surface of the polishing pad and the surface of the workpiece relative to each other. There is provided a polishing method characterized by performing polishing.

Further, according to one aspect of the polishing method of the present invention for achieving the above object, in a polishing method using a metal or resin polishing platen and a polishing pad, the slurry is made of metal or resin. The first polishing is performed on the workpiece by supplying the workpiece to the surface of the polishing table and moving the polishing table and the workpiece relative to each other, and a deposit for scraping off the deposit on the polishing pad surface. The polishing particles and the slurry are supplied separately or as a mixture to the surface of the polishing pad to relatively move the surface of the polishing pad and the workpiece. There is provided a polishing method characterized by performing the polishing.

Further, according to one embodiment of the polishing method of the present invention for achieving the above object, in the polishing method for supplying a slurry to the polishing pad and polishing the workpiece, The particles for scraping out the deposits and the slurry are supplied to the surface of the polishing pad separately or as a mixture to move the surface of the workpiece and the surface of the polishing pad relatively. In this way, the workpiece is subjected to the first polishing, and the polishing pad used in the first polishing step is also subjected to the second polishing using the second polishing pad having a small surface rigidity. The polishing method characterized by performing the polishing of the above is provided. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram showing a polishing apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram schematically showing the polishing apparatus of FIG. 1 as viewed from above, and FIG. , FIG. 3 is an explanatory view showing the appearance of the surface of the polishing pad of the polishing apparatus. FIG. 3 (a) is an explanatory view showing the appearance of the polishing pad of the polishing apparatus of FIG. 1 according to the present invention. FIG. 3 (b) is an explanatory view showing a state on a polishing pad of a conventional polishing apparatus. FIG. 4 is a diagram (part 1) showing the results of a comparison experiment between the polishing apparatus of the present invention shown in FIG. 1 and a conventional polishing apparatus, and FIG. 5 shows the polishing apparatus of the present invention shown in FIG. Fig. 6 shows the results of a comparative experiment between the polishing apparatus of the present invention and the conventional polishing apparatus shown in Fig. 1, and Fig. 6 shows the results of a comparative experiment between the polishing apparatus of the present invention and the conventional polishing apparatus. FIG. 7 is a diagram (part 4) showing the results of a comparison experiment between the polishing apparatus of the present invention shown in FIG. 1 and a conventional polishing apparatus, and FIG. FIG. 5 is a diagram (part 5) showing the results of a comparative experiment between the polishing apparatus of the present invention of FIG. 1 and a conventional polishing apparatus, and FIG. 9 shows a polishing apparatus of another embodiment of the present invention. FIG. 10 is a schematic configuration diagram showing a processing process of performing roughing and finishing using a polishing apparatus according to still another embodiment of the present invention. FIG. 11 is a schematic configuration diagram showing a machining process for performing rough machining and finish machining using a polishing apparatus according to still another embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 shows a main part of the polishing apparatus of the present embodiment. This polishing apparatus is a so-called chemical mechanical polishing apparatus (CMP apparatus). In the figure, a chuck 3 for holding a workpiece 1 via an elastic body 2 and a polishing pad 4 are detachable. A polishing platen 5 attached to the base, a base 6 surrounding the lower surface and side surfaces of the polishing platen 5 so as not to hinder the rotation of the polishing platen 5, and a polishing pad surface (work surface). A working fluid supply device 10 for supplying a working fluid 7; An electric field generating device 20 for generating an electric field in a specific region including a part of the polishing pad 4 is shown.

The polishing apparatus also includes a first rotation mechanism for rotating the polishing table 5, a second rotation mechanism for rotating the chuck 3, and a feeding mechanism for moving the chuck 3 in the X direction. In addition, a pressing mechanism for pressing the workpiece 1 against the polishing pad surface is provided. These mechanisms are not shown in the drawings because they are also used in conventional CMP devices and their structures are well known. For example, the first rotating mechanism includes a servomotor and a speed reducer, and transmits the output of the servomotor to the rotating shaft of the polishing table 5 via the speed reducer to rotate the polishing table 5. The feed mechanism also includes a servo motor and a speed reducer.The output of the servo motor is transmitted to the spline formed on the ball screw for chuck feed via the speed reducer, and the chuck 3 is moved in the X direction. Move to The pressing mechanism moves the chuck 3 in the z direction using an air cylinder, and presses the workpiece 1 against the polishing pad surface.

The workpiece 1 is, for example, a silicon wafer in a stage where wirings are being multi-layered, and a SiO ₂ interlayer insulating film is formed on the surface thereof. Under the interlayer insulating film, a wiring group having a fine pattern is formed. For this reason, a level difference occurs in the interlayer insulating film between a portion where the wiring exists and a portion where the wiring does not exist. The present polishing apparatus is used to flatten the unevenness of the surface of the interlayer insulating film or to polish a metal film constituting a wiring group.

In the present invention, a mixture of the slurry 7 and particles for scraping out deposits for scraping out deposits on the surface of the polishing pad is used in the slurry. The function and effect of the sediment scraping particles will be described later in detail. A slurry having a solid phase reactivity with a member having a surface to be processed is used. For example, when polishing an SiO ₂ insulating film, an alkaline solution containing about 20% by weight of SiO ₂ abrasive grains (silica abrasive grains) having a particle size of about 30 nm may be used. , Grain About 2 0 wt diameter l OO nm of C E_〇 ₂ abrasive grains (oxide parsley um abrasive). Use the one mixed with / ₀ . On the other hand, when polishing the metal film on the SiO ₂ film, for example, a material obtained by mixing alumina abrasive grains in an acidic solution is used. The polishing pad 4 is formed of a material having excellent wear resistance and chemical resistance. In the present embodiment, a polishing pad made of a rigid foamed polyurethane-based synthetic resin is used. The surface of the polishing pad has a predetermined surface roughness, and a plurality of minute concave portions corresponding to the surface roughness are formed on the surface.

The machining fluid supply device 10 includes a tank 11 for temporarily storing a machining fluid 7 (ie, a mixture of slurry and sediment scraping particles) sent from outside, and a sediment scraping particle in the tank 11 內.撹拌 Agitator 12 for agitating these so that the abrasive grains do not settle, pump 14 for pumping the machining fluid in tank 11 from supply pipe 13, and supply of machining fluid per unit time Adjusting the volume is configured with a valve 15 '. The slurry and sediment scraping particles may be supplied separately, taking care to mix well on the polishing pad surface.

The electric field generator 20 includes a disk-shaped electrode plate 21 disposed directly below the polishing pad 4, a rail 22 attached to the base 6, and a motor drive not shown. It is fixed to the table 23 and the table 23 that moves directly along the rail 22 and moves in the radial direction (X direction) of the polishing pad 4 while maintaining a certain distance from the surface of the polishing pad. It comprises an electrode plate 24, a power supply 25 built in the base 6, and a switch 26. The power supply 25 and the electrode plate 21 are electrically connected via a slip ring 8 attached to the rotating shaft of the polishing platen 5, and this electrical connection is made by the polishing platen. It is maintained while 5 is rotating. As shown in FIG. 2, the moving area 24a of the electrode plate 24 and the moving area 3a of the chuck 3 are set so as not to overlap with each other. Then, when the switch 26 is turned on, an electric field is formed between the electrode plates 21 and 24. The strength of the electric field is adjusted by increasing or decreasing the voltage of the power supply 25. In addition, when the position of the electrode plate 24 is moved in the X direction, an electric field is generated, and the region moves accordingly.

The configuration of the electric field generator 20 is not limited to that described above. Instead of moving the electrode plates 24 along the rails 22, a plurality of electrode plates 24 are previously set on the rails 22 at regular intervals. Then, any one of these electrode plates may be selected and an electric field may be generated there. In the electric field generator 20 of the present embodiment, the table 23 slides on the rail 22. However, if this sliding portion can be omitted, the durability of the device is improved structurally.

The components of the polishing apparatus have been described above according to their functions. In this polishing apparatus, a processing liquid 7 is supplied onto the surface of the polishing pad using these components, and a wafer is provided on the surface of the polishing pad. For example, the process of pressing the surface to be processed 1 and the process of relatively moving the surface of the polishing pad and the surface of the wafer 1 to be processed are simultaneously performed, for example, by the mechanical and chemical polishing action of the processing liquid 7. Then, fine irregularities on the surface to be processed are removed, and finally, the surface to be processed is mirror-finished. In this case, in this polishing apparatus, the deposits generated by the polishing are scraped off from the surface of the polishing pad by the deposit scraping particles.

Figure 3 (a) shows how the deposits on the polishing pad surface are scraped out. In FIG. 3 (a), a working fluid 7 is supplied between the surface of the polishing pad 4 and the surface to be processed of the wafer 1. In this state, the polishing pad 4 and the wafer 1 are connected to each other. Are relatively sliding. The working liquid 7 is composed of a liquid 71 serving as a solvent, abrasive grains 72 for polishing, and particles 73 for scraping out deposits. The sediment scraping particles 73 are made of a polymer (for example, having a longitudinal elastic modulus of about 2 to 3 Gp). It is a spherical member made of acrylic resin or ethylene resin. If the particles 73 for excavating the deposit are formed into a spherical shape, the processing becomes easy. Polishing of the surface to be processed of the wafer 1 is mainly realized by the abrasive grains 72 present at a contact portion between the surface to be processed and the surface of the polishing pad 4. This is the same for conventional CMP equipment.

FIG. 3 (b) shows the state of the surface state of the polishing pad 4 in the conventional CMP apparatus. Conventionally, as shown in FIG. 3 (b), chips and the like generated during polishing are deposited on the concave and convex portions of the surface of the polishing pad 4 as deposits 74, and polishing is conventionally performed. Pad 4 was clogged. Although not clearly shown in FIG. 3 (b), debris is generated around the convex portion on the surface of the polishing pad 4, so that deposits also accumulate on this convex portion.

Such clogging of the polishing pad surface significantly reduces the polishing efficiency. Conventionally, for example, a dedicated grindstone (grindstone 30 in FIG. 2) is placed on the polishing pad. This was prevented by performing dressing continuously during polishing, so-called in-process dressing. This in-process dressing is a process in which diamond abrasive grains are fixed to the surface of a grindstone, and while the diamond abrasive grains are pressed against the polishing pad, the grindstone and the polishing pad slide. This is the operation to remove the waste together with the sediment.

On the other hand, in the polishing apparatus according to one embodiment of the present invention, as shown in FIG. 3 (a), the deposit is moved in the concave portion on the surface of the polishing pad 4 or so as to move from the concave portion to the concave portion. Since the scraping particles 73 roll, the sediment 74 is scraped off. Therefore, clogging of the polishing pad 4 due to the deposits 74 hardly occurs in this portion, and a decrease in polishing efficiency can be prevented. In addition, sediment scraping particles 7 Since the roller 3 rolls on the surface of the polishing pad 4, the surface of the polishing pad 4 is not shaved, and the consumption of the polishing pad 4 is significantly suppressed.

Further, in the polishing apparatus of the present embodiment, since the deposit scraping particles 73 are attracted in the electric field generated between the electrode 21 and the electrode 24, the deposit is deposited on the surface of the polishing pad 4. The scraping particles 73 stay to some extent. As the density of the particles 73 for excavating the sediment in the machining liquid 7 increases, the frequency of contact between the surface of the polishing pad 4 and the particles 73 for exposing the sediment increases, and the particles for exposing the sediment increase. 7 The effect of eliminating blind spots by 3 is improved. Next, the difference between the present polishing apparatus and the conventional polishing apparatus (CMP apparatus) will be specifically verified. Here, a comparative experiment was performed by actually operating the present polishing apparatus and the conventional polishing apparatus.

First, various conditions set in the experimental test are described together, and then the specific contents of the experiment are described.

対象 Polishing target: 6 inch Si wafer with interlayer insulating film formed on the surface 〇Polishing condition:

Rotation speed of polishing platen: 20 r / min

Number of rotations of chuck: 20 r / min

Chuck feeding speed: 5 mm / sec

Polishing time: 1 O min (However, the polishing efficiency is measured every 2 minutes)

100 min (however, the polishing efficiency is measured every 10 minutes)

Polishing load: 60 kg f

Slurry: Al solution containing abrasive grains

Abrasive grain size: 30 nm

Depth of multiple minute parts existing on the surface of the polishing pad: 30 to 40 μm

方法 Calculation method of polishing amount: Before starting polishing, use a light interference type film thickness meter.

4 Measure the thickness of the interlayer insulation film at 9 locations (T1, ··· Τ49), and after polishing, measure the film thickness at the same position (Τ1 '· · · Τ49'). , using (equation 1) to calculate the amount of polishing V _k. Still, using the (equation 2) to calculate the variation AV amount of polishing V _k.

V, = T _k —T _k '(Equation 1)

△ V = ± 10 00 (Vmax— Vmin) / (2 Vave) (Equation 2) where k is a natural number of 49 or less, Vmax is the maximum polishing amount, Vmin is the minimum polishing amount, and Vave is the average polishing amount. It is.

Items related to conventional polishing equipment only>

〇 Dressing conditions for polishing pad:

Dressing member: Diamond whetstone placed on polishing pad Dressing timing: Only during or before polishing Dressing time: Same time as polishing time

If dressing before polishing, 30 sec

条件 Polishing conditions for polishing pad deposits:

Sediment scraping member: Spherical sediment scraping element made of polymer

Sediment removal timing: polishing

Sediment scraping time: Same time as polishing time

Particle size of sediment scraping particles: 8, 60 m

Concentration of sediment scraping particles: 1, 5, 10 weight. / ₀

印加 Applied voltage of electric field generator: 100 V First, we examined how the polishing efficiency changes with the polishing time. Figure 4 shows the experimental results. Here, polishing was performed for 10 minutes, and the polishing efficiency (polishing amount V / polishing time T) was calculated every 2 minutes.

Each mark (a) in the figure shows a change in the polishing efficiency of a conventional polishing apparatus when dressing is continuously performed during polishing. Each mark in (g) shows the change in the polishing efficiency of a conventional polishing apparatus when dressing is performed only before polishing. Each mark in (c) shows the transition of the polishing efficiency when the particle diameter of the particles for scraping out deposits is 8 m and the concentration is 5% by weight in the polishing apparatus of the present embodiment. Each mark in (d) shows the transition of the polishing efficiency when the particle size of the sediment scraping particles is 8 μm and the concentration is 10% by weight. Each mark in (e) shows the change in the polishing efficiency when the particle size of the sediment extraction particles is 8 μm and the concentration is 1% by weight. Each mark in (f) indicates that the particle size for sediment scraping is 60 μm and the concentration is 10 weight. It shows the progress of the polishing efficiency when / ₀ is set. Each mark in (b) shows the transition of the polishing efficiency when the particle size of the sediment scraping particles is 8 μm and the concentration is 5% by weight and an electric field is generated by an electric field generator.

According to this experiment, in (a), the polishing efficiency was stable, and the average value was as high as about 0.2 / mZmin. On the other hand, in (g), the final polishing efficiency was reduced by about 40% of the initial value as compared with the initial value.

In addition, in (c), the average value of the polishing efficiency is about ◦ 18 μm / min, which is 10% lower than the average value of (a) in comparison with (a). did. In (d), the average value of the polishing efficiency was about 0.16 μm / min, which was about 20% lower than the average value of (a) in comparison with (a). However, in (c) and (d), the stability of polishing efficiency is good. It was equivalent to (a). This clearly shows that the particles for scraping off sediment had an effect of eliminating clogging.

On the other hand, in (e), the final polishing efficiency was reduced by about 20% of the initial value as compared with the initial value. This indicates that the polishing pad 4 was clogged due to the low concentration of the particles for scraping out the sediment.

In (f), the polishing efficiency was stable, but the average value of the polishing efficiency was about 0, 12 m / min. Compared to (a), the average value of the polishing efficiency in (a) was It has been reduced by about 40%. This is due to the fact that the particle size of the particles for scraping out deposits is larger than the depth of the minute recesses on the surface of the polishing pad, so that the polishing pad surface is less likely to contact the surface to be processed and the polishing efficiency is reduced. Seem. Therefore, in order to improve the polishing efficiency, the size of the particles for scraping out the deposits must be at least as small as the average depth of the plurality of recesses present on the surface of the polishing pad. is there.

In (b), the stability and average value of the polishing efficiency were equivalent to (a). This means that if the particle size and concentration of sediment scraping particles are set to optimal values and a predetermined electric field is generated, the polishing efficiency can be changed in exactly the same way as in the conventional polishing method. Is shown.

■ Next, Fig. 5 shows the measurement results of the surface profile of the polishing pad. Here, the surface profile of the polishing pad was measured using a stylus-type surface roughness meter, and the effect of the particles for scraping out deposits was examined.

Figs. 5 (a) and (b) show the surface profile of the polishing pad when dressing is performed before polishing and not during polishing ((g) in Fig. 4). The measurement results are shown. The surface profile file in Fig. 5 (a) is the one immediately after dressing, and the surface profile in Fig. 5 (b) is the one after 10 minutes from the start of polishing. In this way, if no dressing work is performed during the polishing operation, the polishing The eye moves rapidly on the head.

On the other hand, Fig. 5 (c) shows the surface profile when the particles for excavating the sediment and the electric field generator were used (in the case of (b) in Fig. 4). 10 minutes after the start of polishing, but almost no clogging and almost the same state as the profile immediately after dressing (Fig. 5 (a)) .

Next, FIG. 6 shows a diagram regarding the polishing efficiency when the polishing operation is performed for a long time. Here, polishing was performed for 100 minutes, and the polishing efficiency was calculated every 100 minutes.

The sixth diagram (a), as with the 4 (a), the during polishing continuously in polishing efficiency in case of performing Doretsushingu transition is the indicated _c the 6 (b) is As in (b) of Fig. 4, the change in polishing efficiency when using 8 μπι particles for scraping out deposits and an electric field generator is shown. _{C As} is clear from the figure, (b) The polishing efficiency of (a) is stable at about the same level as (a), and even if polishing is performed for a long period of time, the effect of the particles for scraping off the deposits is sufficiently exhibited.

Next, the evaluation results of the amount of consumption of the polishing pad in (a) and (b) of FIG. 6 are described. The effect of the present embodiment is remarkably reflected in the consumption of the polishing pad.

The initial thickness of the polishing pad before polishing was about 1.3 mm in both cases (a) and (b) of FIG. When the polishing time exceeded 100 minutes, the polishing pad was cut, and the thickness of the polishing pad in the radial direction at the portion where the wafer passed was measured using a micrometer. . After that, the difference from the initial thickness was determined for each measurement result, and the consumption of the polishing pad was calculated based on the average value.

As a result, the consumed amount under the condition (a) was about 150 μm. on the other hand, The amount of consumption under the condition (b) was about 10 μm.

This is because the polishing pad is significantly consumed by continuous dressing with a grindstone, but the polishing pad is significantly consumed when particles for scraping out are used. 5). Since the polishing pad is compressed and deformed during polishing, the actual consumption in FIG. 6 (b) is actually smaller than the above-mentioned value.

Next, the distribution of the polishing efficiency within the wafer surface is shown in FIG.

When dressing is performed continuously during polishing (in the case of (a) in Fig. 4), the variation in polishing efficiency in the wafer surface is about ± 3% as shown in (a) in Fig. 7. there were. On the other hand, when dressing is performed only before polishing (case (g) in FIG. 4), the variation in polishing efficiency within the wafer surface is about ± 7% as shown in (g) in FIG. Was. In (g) of FIG. 7, the polishing efficiency was significantly reduced at the center of the wafer. For this reason, in (b) of FIG. 7, the electrode 24 is arranged substantially at the center of the rail 22 so that the electrode 24 and the center of the wafer are positioned substantially concentrically. An electric field is generated at an applied voltage of 100 V, and as in Fig. 4 (b), polishing is performed using a machining fluid with a particle size of 8 μm and a concentration of 5% by weight for scraping out sediments. Was conducted.

As a result, the polishing efficiency in the wafer surface was equivalent to that obtained when continuous dressing was performed ((a) in FIG. 7).

As described above, according to the polishing apparatus of the present embodiment, the distribution of the polishing efficiency in the wafer surface can be arbitrarily changed by moving the position of the electrode 24.

Next, FIG. 8 shows a change in the thickness of the polishing pad when a large number of wafers are polished, where the most remarkable effect is exhibited in the present embodiment. The measurement was performed by cutting the polishing pad and measuring with a micrometer as described above. <Fig. 8 (a) shows the case of (a) in Fig. 4 (that is, the dressing was continuously performed during polishing). The transition of the thickness of the polishing pad is shown.

The FIG. 8 (c), in the fourth diagram of (c) (i.e., the particle size of the deposited writers out and for particles with 8 m, when the concentration of 5 wt. / ₀₎ The transition of the thickness of the polishing pad is shown.

Thus, under the condition (c) of FIG. 4, the polishing apparatus of the present embodiment shows that the polishing pad thickness hardly changes even when 100 wafers are polished. The consumption of the polishing pad is completely suppressed. On the other hand, in the conventional polishing apparatus under the condition (a) in FIG. 4, the polishing pad becomes thinner as the number of sheets increases. This means that the maintenance time in the semiconductor manufacturing process is much shorter in the present embodiment than in the conventional example.

As described above, the comparative experiment between the polishing apparatus of the present embodiment and the conventional polishing apparatus has been described. Separately, the experiment was performed by applying the polishing apparatus of the present embodiment to a multilayer wiring process of a semiconductor device. .

As a result, it was confirmed that the variation in the polishing amount of the interlayer insulating film was suppressed to ± 2.7% or less. The surface roughness of the interlayer insulating film was measured to be 0.3 nm or less as a result of measuring the surface roughness of the interlayer insulating film by using a contact surface roughness meter and an atomic force microscope. Was confirmed. In addition, the surface roughness of the interlayer insulating film at the step was measured using a contact surface roughness meter and an atomic force microscope. It was confirmed that the surface was flattened to 0 5 μm or less. The above measured values are values that can satisfy the conditions required for an interlayer film of an ultrafine line having a line width of 0.15 m. The application of the present polishing apparatus to the multilayer wiring process is only an example shown for evaluating the apparatus performance. Therefore, needless to say, even if the present polishing apparatus is introduced into a polishing process of another component (for example, an optical element or the like) requiring high shape accuracy, the same beneficial effect can be achieved.

Next, another embodiment of the polishing apparatus according to the present invention is shown in FIG.

In the same figure, a polishing pad 104 formed with a plurality of concentric drainage channels (drainage grooves) 104a is attached to the upper surface of the polishing platen 105. . This groove is formed, for example, with a groove width of about 100 m and a groove depth of about 300 to 400 μm.

Although the polishing pad 104 having such a form has existed in the past, when the polishing process was performed using the polishing pad, as the polishing time elapses, the above-described processing was performed in the groove 104a. Debris accumulates and clogs the grooves, lowering polishing efficiency.

Therefore, in this polishing apparatus, an arm 102 provided with a plurality of scraping pieces (for example, thin resin pieces having sharp pointed ends) 101 is provided. The arm 102 is fixed to a translation table 103 movable in the z direction. The mounting pitch of the scraping pieces 101 matches the pitch of the concentric grooves of the polishing pad. During the rotation of the polishing table 1◦5, the linear motion table 103 moves in the z direction and pushes each piece 101 into the groove 104a of the polishing pad 104. . As a result, the tip of the scraping piece 101 slides at the bottom of the groove 104a, and the sediment in the groove is scraped out. The arm 102 with a scraping piece may be attached to, for example, the polishing apparatus shown in FIG. In this case, the arm 102 with a scraping piece is installed at a position indicated by a dotted line in FIG. 2, for example.

Here, the results of a comparative experiment of a conventional polishing apparatus without the arm 102 with a scraping piece and the polishing apparatus of the present embodiment will be described. Conventional polishing equipment: When polishing was actually performed using a polishing pad with concentric grooves with a width of about 100 μm, despite continuous dressing using a grindstone, After 100 minutes of polishing time, the inside of the groove was noticeable.

Polishing apparatus of the present embodiment: Even if polishing was continued without dressing with a grindstone, the inside of the groove was not clogged. In this case, the effect of eliminating the clogging inside the groove was the same between the case where the scraping piece was continuously slid and the case where it was slid for 30 seconds every 10 minutes. .

Next, still another embodiment of the polishing apparatus according to the present invention is shown in FIG. FIG. 10 (a) shows a first polishing mechanism of the polishing apparatus of the present embodiment. This grinding device is a so-called grinding machine when using a grindstone, and a lapping machine when using a lap surface plate. In the figure, the workpiece 1 is made of an elastic body 2 b A chuck 3b, which is held through a hole, and a polishing platen 5b to which a grindstone 4b (or a lap platen 4c) is removably attached as main components, are provided. The machining fluid 7b is supplied on the surface (work surface) of the grinding wheel 4b (or the lap surface plate 4c).

Although not shown in FIG. 10 (a), the following configuration is also included. For example, a base that surrounds the lower surface and side surfaces of the polishing table 5b so as not to hinder the rotation of the polishing table 5b. A first rotating mechanism for rotating the platen 5b, a second rotating mechanism for rotating the chuck 3b, a feeding mechanism for moving the chuck 3b in the X direction, and a workpiece 1 It has a pressure mechanism for pressing against the polishing pad surface. Although these mechanisms are not shown in the drawings, they are also used in conventional grinding machines and lapping machines, and their structures are well known. For example, the first rotation mechanism includes a servomotor and a speed reducer, and outputs the output of the servomotor via the speed reducer. Then, it is transmitted to the rotating shaft of the polishing table 5b, and the polishing table 5b is rotated. The feed mechanism also includes a servo motor and a speed reducer. The output of the servo motor is transmitted to the spline formed on the ball screw for chuck feed via the speed reducer, and the chuck 3 b is moved to X Move in the direction. The pressurizing mechanism moves the chuck 3b in the z-direction with the aid of a cylinder, and presses the workpiece 1 against the grindstone surface or the lap surface.

The workpiece 1 is, for example, a silicon wafer in a stage in which wiring is multi-layered, and an SiO ₂ interlayer insulating film is formed on the surface thereof. Under the interlayer insulating film, a group of wires having a fine pattern is formed. For this reason, a level difference occurs in the interlayer insulating film between a portion where the wiring exists and a portion where the wiring does not exist. The first polishing mechanism is used to flatten the unevenness of the surface of the interlayer insulating film or to polish a metal film constituting a wiring group. A slurry is used as the working fluid 7b. A slurry with a solid surface reactivity with a member having a surface to be processed is used. For example, in the case of polishing an insulating film S io ₂ is an alkaline solution, a particle size of about 3 0 nm of S i 0 ₂ abrasive grains obtained by mixing (silica abrasive grains) from about 2 0% by weight and a particle size about 1 0 0 nm of C E_〇 ₂ abrasive use those mixed with (oxidation parsley um abrasive grains) from about 2 0% by weight. On the other hand, when polishing a metal film on the SiO ₂ film, for example, a material obtained by mixing alumina abrasive grains in an acid solution is used.

The grindstone 4b is formed of a material having a low elastic modulus so that scratches do not occur on the wafer surface during processing. In this embodiment, a grindstone formed of cerium oxide abrasive grains is used. The whetstone surface has a predetermined surface roughness and flatness.

When the lapping plate 4c is used for polishing the grinding wheel 4b, a lapping plate formed of a material having a low elastic modulus such as metal, plastic or rubber, or a composite material of metal and plastic / rubber is used. Use a board. The machining fluid supply device includes a tank for storing the machining fluid 7b sent from outside, a stirrer for stirring the abrasive fluid so as not to settle in the tank, and a machining fluid in the tank. It has a pump for sending 7b from the supply pipe 13b and a valve for adjusting the supply amount of machining fluid per unit time.

FIG. 10 (b) shows a second polishing mechanism of the polishing apparatus of the present embodiment. The second polishing mechanism is a so-called chemical mechanical polishing apparatus (CMP apparatus), and has the same configuration as the polishing apparatus shown in FIG.

In this embodiment, roughing is performed by the polishing apparatus shown in FIG. 10 (a), and finishing is performed by the polishing apparatus shown in FIG. 10 (b).

Hereinafter, this will be described in detail. The first polishing mechanism (FIG. 10 (a)) uses the above components to supply a machining fluid 7b onto the surface of the grindstone 4b (or the lap surface plate 4c). A process of pressing the work surface of the wafer 1 against the surface of the grinding wheel 4 b (or the lap surface plate 4 c), and a process of pressing the surface of the grinding wheel 4 b (or the lap surface plate 4 c) with the surface of the wafer 1. At the same time, the processing to remove the fine irregularities on the surface to be processed is performed by the mechanical and chemical polishing action of the processing liquid 7b. This is rough processing of the work surface of the work 1 by the first polishing mechanism.

Further, in the second polishing mechanism section (FIG. 10 (b)), a process of supplying a working fluid 7 onto the surface of the polishing pad 4 using the above-described constituent elements, The process of pressing the surface to be processed of the wafer 1 against the surface of the polishing pad 4 and the process of moving the surface of the polishing pad 4 and the surface to be processed of the wafer 1 relative to each other are simultaneously executed. Mechanical and chemical polishing with the processing liquid 7 By the action, fine irregularities on the surface to be processed are removed, and finally, the surface to be processed is mirror-finished. This book second polishing In the mechanical part, in particular, the surface to be processed is finished.

Thus, the present invention can also be applied to the second polishing step in a two-stage polishing operation. FIG. 11 shows another embodiment of the polishing apparatus according to the present invention. In this embodiment, as the first polishing step, the deposit shown in FIG. 1 is scraped and polished, and as the second polishing step, the polishing pad shown in FIG. In this method, the surface to be processed is finished using a polishing pad with low surface rigidity.

FIG. 11 (a) shows a first polishing mechanism of the polishing apparatus of the present embodiment. This polishing apparatus is a so-called chemical mechanical polishing apparatus (CMP apparatus), and polishes the surface of a wafer by the same method as the polishing apparatus shown in FIG.

FIG. 11 (b) shows a second polishing mechanism of the polishing apparatus of the present embodiment. The second polishing mechanism is a so-called chemical mechanical polishing device (CMP device). In the figure, a chuck 3 c for holding the workpiece 1 through the elastic body 2 c and a soft A polishing platen 5c to which the polishing pad 4d is detachably attached, and a supply pipe 13c for supplying the machining fluid 7c onto the surface (work surface) of the soft polishing pad 4d. It is shown.

Although not shown in Fig. 11 (b), it includes the following components. A base surrounding the lower surface and side surfaces of the polishing platen 5c so as not to hinder the rotation of the polishing platen 5c, and a first rotating mechanism for rotating the polishing platen 5c, and the chuck 3c are rotated. A second rotating mechanism for moving the chuck 3c in the X direction, a pressing mechanism for pressing the workpiece 1 against the surface of the soft polishing pad, and the like. These mechanisms are not shown in the drawings because they are used in a conventional CMP apparatus and have a well-known structure. For example, the first rotating mechanism is composed of a servomotor and a speed reducer. The output of the servomotor is transmitted to the rotating shaft of the polishing table 5c via a speed reducer, and the polishing table 5c is rotated. The feed mechanism also includes a servo motor and a speed reducer, and transmits the output of the servo motor to the spline formed on the ball screw for chuck feed through the speed reducer _. Move to The pressurizing mechanism moves the chuck 3c in the z direction with an air cylinder, and presses the workpiece 1 against the soft polishing pad.

In FIG. 11 (a), the workpiece 1 is subjected to a first polishing step by the same processing as in FIG.

The soft polishing pad 4d used in the second polishing step shown in FIG. 11 (b) is formed of a material having excellent wear resistance and chemical resistance. In the present embodiment, a polishing pad made of a soft foamed polyurethane-based synthetic resin is used. The surface of the polishing pad has a predetermined surface roughness, and a plurality of minute concave portions corresponding to the surface roughness are formed on the surface.

This second polishing mechanism is also a so-called chemical mechanical polishing device (CMP device), and is different from the polishing pad of the polishing device shown in FIG. 1 (FIG. 11 (a)). A soft polishing pad with a low elastic modulus is provided, and the surface of a wafer rough-processed by the polishing device shown in Fig. 11 (a) is polished.

That is, in the second polishing mechanism, processing for supplying the working liquid 7c onto the surface of the soft polishing pad 4d and processing for pressing the surface to be processed of the wafer 1 against the surface of the soft polishing pad 4d are performed. At the same time, the process of relatively moving the surface of the soft polishing pad 4d and the surface to be processed of the wafer 1 is performed, and fine irregularities on the surface to be processed are mechanically and chemically polished by the processing liquid 7c. After removal, the surface to be processed is finally mirror-finished (finished). Industrial applicability As described above in detail, according to the present invention, clogging of the polishing pad is suppressed by the action of the particles for scraping out deposits during polishing, the polishing efficiency is stabilized, and the polishing pad is stabilized. This significantly reduces the amount of power consumption, and significantly reduces maintenance time in the manufacturing process for semiconductors and other products.

Also, unlike conventional dressing, the abrasive grains do not fall off from the grindstone, so the scratches due to the dropped abrasive grains do not enter the work surface and improve the reliability of the workpiece, including semiconductor devices. Will be able to Thus, the present invention is suitable for use in a semiconductor manufacturing process having a polishing step.

Claims

In a method for manufacturing a semiconductor device in which a slurry is supplied to a polishing pad and a substrate is polished, the particles for scraping out deposits for scraping out deposits on the surface of the polishing pad and the above-mentioned range. Manufacturing a semiconductor device, wherein the slurry is supplied to the polishing pad surface separately or as a mixture, and the substrate is polished by relatively moving the surface to be processed of the substrate and the polishing pad surface. Method.

In a method for manufacturing a semiconductor device having a step of polishing a substrate, a first polishing is performed on the substrate by supplying a grinding liquid or a slurry to the surface of the grinding wheel to move the grinding stone and the substrate relative to each other. The particles for scraping off the deposits on the surface of the polishing pad and the slurry are supplied separately or as a mixture to the surface of the polishing pad to move the polishing pad surface and the surface to be processed of the substrate relatively. A method of manufacturing a semiconductor device, wherein a second polishing is performed on the substrate.

A method for manufacturing a semiconductor device having a step of polishing a substrate, comprising: supplying a slurry to a surface of a polishing plate made of metal or resin to move the polishing plate and the substrate relative to each other; The polishing pad surface is polished, and the particles for removing the deposits and the slurry for scraping off the deposits on the surface of the polishing pad are supplied to the surface of the polishing pad separately or as a mixture. A second polishing of the substrate by relatively moving the substrate _c . A method of manufacturing a semiconductor device wherein the substrate is polished by supplying a slurry to a polishing pad. A method of processing a substrate by separately or as a mixture supplying the particles for scraping the deposit for scraping the deposit on the surface of the polishing pad and the slurry to the surface of the polishing pad. And said polishing pad surface The first polishing is performed on the substrate by relatively moving the substrate, and the polishing pad used in the first polishing step is also subjected to the second polishing using the second polishing pad having a small surface rigidity. A method for manufacturing a semiconductor device, comprising: polishing a semiconductor device.

5. In a polishing method using a polishing pad, the particles for scraping off the deposits on the surface of the polishing pad and the slurry are supplied separately or as a mixture onto the surface of the polishing pad, and the workpiece is processed. A polishing method characterized in that a workpiece is polished by relatively moving the workpiece and the polishing pad surface while pressing a processing surface against the polishing pad surface.

6. The polishing method according to claim 5, wherein the surface of the polishing pad has a predetermined surface roughness, and the deposit scraping particles are present on the surface of the polishing pad. A polishing method characterized by having a particle size smaller than the average depth of the plurality of recesses to be formed.

7. The polishing method according to claim 5 or 6, wherein the slurry includes a liquid serving as a solvent and abrasive grains, and the particles for scraping off the deposits are more than the abrasive grains. A polishing method characterized by having a large particle size.

8. The polishing method according to claim 5, wherein the sediment scraping particles are formed of a polymer.

9. The polishing method according to claim 8, wherein the polymer has a longitudinal elastic modulus of 2 to 4 GPa.

10. The polishing method according to claim 5, wherein the sediment scraping particles are spherical.

11. The polishing method according to claim 5, wherein an electric field is supplied to a periphery of the polishing pad, and the particles for scraping off the deposit are formed on the surface of the polishing pad. A polishing method characterized in that the polishing is carried out on a polishing surface.

2. In a polishing method that uses a polishing pad to chemically and mechanically remove the unevenness of the surface of the workpiece and flatten it, it is used to remove deposits on the surface of the polishing pad. The particles and the slurry are supplied separately or as a mixture onto the surface of the polishing pad, and the surface of the workpiece and the surface of the polishing pad are relatively moved while pressing the surface of the workpiece against the surface of the polishing pad. A chemical-mechanical polishing method characterized by treating an object to be reworked by moving the workpiece mechanically.

3. A supply device for supplying a mixture of the particles for removing the deposits and the slurry for scraping the deposits on the surface of the polishing pad onto the surface of the polishing pad, and holding the workpiece and polishing the workpiece. A polishing apparatus, comprising: at least a holding member for pressing against a pad surface; and a device for relatively moving the workpiece and the polishing pad.

4. The polishing apparatus according to claim 13, further comprising: an electric field generator for generating an electric field for retaining the particles for scraping out the deposits on the surface of the polishing pad. Polishing equipment.

5. A base, a rotatable polishing plate, and a polishing plate provided on the polishing plate and having a plurality of drainage channels formed concentrically on the surface thereof around the rotation center of the polishing platen. In a polishing apparatus provided with a pad,

An arm fixed to the base, and a plurality of scraping pieces attached to the arm in accordance with an arrangement pitch of the plurality of drainage channels, wherein the plurality of scraping pieces are used when the polishing platen is rotated. The polishing apparatus according to any one of claims 1 to 3, wherein the sediment in the drainage channel is scraped out.

6. Chemical-mechanical polishing equipment that removes irregularities on the surface of the workpiece chemically and mechanically and planarizes it.

Particles for scraping off deposits on the polishing pad surface A supply device for pouring the mixture with the slurry onto the polishing pad surface, a holding member for holding the workpiece and pressing the workpiece against the polishing pad surface, the workpiece and the polishing pad A chemical mechanical polishing apparatus, characterized by at least a device for relatively moving the polishing machine.

17. In a polishing method using a grindstone and a polishing pad, a grinding liquid or a slurry is supplied to the grindstone surface to relatively move the grindstone and the workpiece, thereby forming a first work piece on the work piece. The polishing pad is polished, and the particles for removing the deposits and the slurry for scraping off the deposits on the surface of the polishing pad are supplied separately or as a mixture to the surface of the polishing pad, and the surface of the polishing pad and the workpiece are processed. A polishing method, wherein a second polishing is performed on a workpiece by relatively moving the processing surface.

18. In a polishing method using a metal or resin polishing plate and a polishing pad, the slurry is supplied to the surface of the metal or resin polishing plate and the polishing plate and the workpiece are separated. The workpiece is firstly polished by relatively moving the workpiece, and particles for scraping the deposit and the slurry for scraping the deposit on the surface of the polishing pad are separately or as a mixture. A polishing method, wherein a second polishing is performed on the workpiece by supplying the polishing pad surface to the workpiece and moving the polishing pad surface and the workpiece relatively.

19. A polishing method in which a slurry is supplied to a polishing pad to polish a workpiece, wherein the particles for depositing for scraping off deposits on the surface of the polishing pad and the slurry are separately or mixed. The first polishing is performed on the workpiece by supplying the polishing pad surface and moving the workpiece surface of the workpiece relative to the polishing pad surface. A polishing method, characterized in that a workpiece is subjected to a second polishing using a second polishing pad having a lower surface rigidity than a polishing pad used in a polishing step.