JP2003209079A - Porous plastic grain polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad in which a slurry holding function is high- accurately controlled, the variation of polishing performance is reduced and a service life is prolonged in the field of polishing, in particular, in a CMP process. <P>SOLUTION: In the porous plastic grain polishing pad composed of air bubbles containing plastic grains, preferably, an average air bubble diameter is ≥0.1 μm and <100 μm, an average plastic grain diameter is <300 μm, and plastic is a thermoplastic urethane resin. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing pad used for polishing semiconductors, substrates for various memory hard disks and the like, and in particular, surface flattening of a semiconductor device wafer such as an interlayer insulating film and metal wiring. The present invention relates to a polishing pad that is preferably used in.

[0002]

2. Description of the Related Art FIG. 1 shows an example of a chemical mechanical polishing method (CMP) which is a typical process used for surface flattening of a semiconductor device wafer. For example, while dropping a polishing slurry, a semiconductor wafer is rotated and pressed against the surface of a polishing pad to flatten the surface of an object to be polished with high accuracy. In addition to the polishing conditions, the characteristics of each constituent member affect the polishing rate, the flatness after polishing, the uniformity in the plane of the semiconductor wafer, and the like. Among them, the polishing pad is one of the components that have a great influence on these polishing performances.

Due to the recent remarkable development of the electronics industry, it has evolved into transistors, ICs, LSIs, and VLSIs. As the degree of integration of circuits in these semiconductor elements has rapidly increased, the design rules of semiconductor devices are becoming finer year by year. As the device becomes more and more popular, the depth of focus in the device manufacturing process has become shallower, and the flatness of the pattern formation surface has become more and more strict. Along with this, the level of polishing performance required for polishing pads is also increasing.

Conventionally, in the CMP process, for example, an independent foaming type polishing pad (trade name: IC, using a thermosetting polyurethane manufactured by Rodel Co. as a matrix resin).
1000) etc. have been used as standard. According to the dressing before polishing and the abrasion of the surface of the polishing pad with the progress of polishing, air bubbles are opened and the ability to retain the polishing slurry is developed. Density variations that occur in the conventional polishing pad, for example, in the process of dispersing bubbles and / or hollow spheres in the matrix resin, or in the process of curing the matrix resin, include flatness variation in the polishing surface, non-uniformity, etc. It was a factor. Further, since this density variation occurs not only in the plane but also in the thickness direction of the polishing pad, the conventional polishing pad is
There is a possibility that the polishing performance may change due to the abrasion of the polishing pad itself as the polishing progresses.

Furthermore, in the conventional polishing pad in which the matrix resin constituting the polishing pad is, for example, thermosetting polyurethane, it takes a long time for the dressing process before use, which lowers the throughput in the polishing process. It was a cause. Further, the conventional polishing pad is apt to be clogged with polishing debris or the like generated as the polishing progresses, and the polishing performance such as the polishing rate is likely to change or decrease as the number of polishing is increased. Polishing pad
Despite the dressing process, it must be replaced when the desired polishing performance is no longer obtained, but pad replacement is a task that requires a considerable amount of time even for an expert.
This has been one of the causes of lowering the throughput in the polishing process. Therefore, the advent of a polishing pad that is less likely to be clogged, has less variation in polishing performance, and has a long life has been greatly desired.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the problem that the polishing performance of the conventional polishing pad tends to fluctuate due to, for example, variations in density or clogging caused by the progress of polishing. It is an object of the present invention to provide a porous plastic particle polishing pad in which the slurry holding function is controlled with high precision, variation in polishing performance is small, and the life is long.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made extensive studies in view of the problems of the prior art, and as a result, have accomplished the present invention by the following means. That is, the present invention is
(1) Porous plastic particle polishing pad characterized by being composed of plastic particles containing air bubbles,
(2) The porous plastic particle polishing pad according to item (1), wherein the average diameter of the bubbles is 0.1 μm or more and less than 100 μm, and (3) the average particle diameter of the plastic particles is 30.
The porous plastic particle polishing pad according to item (1) or (2), which is less than 0 μm, and (4) the plastic is a thermoplastic urethane resin. (1)
~ The porous plastic particle polishing pad according to any one of items (3) to (3).

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the polishing pad for porous plastic particles of the present invention, the voids between the porous plastic particles have a role of holding the slurry so that the slurry is spread over the entire surface of the polishing pad, and the plastic particles are included therein. The bubbles open as the dressing and polishing progress, and play the role of holding the slurry on the polishing surface.

The average diameter of the bubbles contained in the plastic particles of the present invention is not particularly limited. For example, the type of polishing target,
The thickness is preferably 0.1 μm or more and less than 100 μm, although it varies depending on the slurry configuration, polishing conditions, and the like. 0.
If it is less than 1 μm, the bubble size is too small, so that clogging due to, for example, polishing debris or the like is likely to occur, and not only the slurry holding performance on the polishing surface varies but also
It is not preferable because the life of the polishing pad itself becomes short.
On the contrary, if the average diameter of the bubbles is 100 μm or more, the slurry cannot be sufficiently held in the polishing surface, and the polishing performance such as polishing rate and flatness is deteriorated, which is not preferable.

The average particle size of the porous plastic particles is not particularly limited. For example, it depends on the type of the object to be polished, the slurry composition, the polishing conditions, etc., but preferably 30
It is less than 0 μm. When it is 300 μm or more, the voids between the porous plastic particles become large, so that the slurry easily flows out, that is, it becomes difficult to properly hold the slurry, and the polishing performance deteriorates, which is not preferable.

The type of plastic particles constituting the polishing pad of the present invention is not particularly limited, but thermoplastic elastomers such as thermoplastic urethane resin, polystyrene, polyester, polypropylene, nylon, polyvinyl chloride, polyvinylidene chloride, Polybutene, polyacetal, polyphenylene oxide, polyvinyl alcohol, polymethylmethacrylate, polycarbonate, polyarylate, aromatic polysulfone resin, polyamide resin, polyimide resin, fluororesin, ethylene-propylene resin, ethylene-ethylacrylate resin, acrylic resin, norbornene-based Resin, styrene copolymer (for example, vinyl polyisoprene-styrene copolymer, butadiene-styrene copolymer, acrylonitrile-styrene copolymer, acrylonitrile Tolyl - butadiene - styrene copolymer, etc.), or natural rubber, synthetic rubber and the like are preferable. These may be used alone, or may be mixed or copolymerized, but a thermoplastic urethane resin is preferable from the viewpoint of polishing performance, processability, cost and the like.

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the contents of the examples. <Evaluation of Polishing Performance> As an object to be polished, a 6-inch silicon wafer on which 10000 Å of Cu was formed by electrolytic plating was prepared. A one-side polishing machine having a platen diameter of 600 mm was used for polishing. Attach the polishing pad to the surface plate of the polishing machine with double-sided tape, and first drop ion-exchanged water,
After dressing the surface of the polishing pad with a diamond disk, a polishing slurry manufactured by Cabot (trade name:
The Cu film was polished for 1 minute while flowing iCue 5003).

As the polishing conditions, the load applied to the wafer is 350 g / cm ² , the rotation number of the surface plate is 70 rpm, the rotation number of the wafer is 70 rpm, and the flow rate of the polishing slurry is 200 ml.
/ Min. After cleaning and drying the wafer after polishing, the Cu film thickness was measured at 49 points on the wafer surface using a 4-probe sheet resistance measuring device, and the polishing rate was calculated as an index of polishing performance, and the flatness and The variations in the in-plane uniformity of the wafer were compared with the conventional pad. The state of clogging of the polishing pad surface after polishing was observed using an electron microscope.

Example 1 A disc-shaped polishing pad having a diameter of 600 mm was prepared by using thermoplastic urethane resin particles having an average particle diameter of 50 μm and containing bubbles having an average diameter of 20 μm. (Example 2) A disc-shaped polishing pad having a diameter of 600 mm was produced by using resin particles having an average particle diameter of 40 µm, which were obtained by alloying thermoplastic urethane resin and polystyrene, and which contained air bubbles having an average diameter of 15 µm. (Comparative Example) IC1000 (manufactured by Rodel) was used as a polishing pad. Reference Example A non-foamed thermoplastic urethane resin particle having an average particle diameter of 50 μm was used to manufacture a disk-shaped polishing pad having a diameter of 600 mmφ.

<Evaluation Results> The flatness was good in both (Example 1) and (Example 2). (Comparative Example) and (Reference Example) were also at a level that could be practically used,
Compared with (Example 1) and (Example 2), the result was slightly lower. Regarding the in-plane uniformity of the wafer, the Cu film-formed wafer was partially clogged on the polished surface at the stage of polishing about 100 sheets in (Comparative Example) and at the stage of polishing about 120 sheet in (Reference Example). Was observed, and the polishing rate and the in-plane uniformity were remarkably lowered, but in (Example 1) and (Example 2), 120
No clogging was observed even after polishing about one sheet,
Neither polishing rate nor in-plane uniformity was observed. In addition,
The time required for dressing of (Example 1), (Example 2) and (Reference Example) was 1/2 or less of that of (Comparative Example).

[0016]

EFFECTS OF THE INVENTION The porous plastic particle polishing pad of the present invention has improved polishing performance such as polishing rate and flatness due to improvement of clogging, etc., as compared with the conventional polishing pad, and the in-plane wafer The variation in polishing performance was reduced and the polishing accuracy was improved. Further, the throughput was improved by shortening the dressing time.

[Brief description of drawings]

FIG. 1 is an example of a standard process of chemical mechanical polishing (CMP).

FIG. 2 is an example of a cross section (a part) of a polishing pad of porous plastic particles of the present invention.

FIG. 3 is an example of a cross section of porous plastic particles constituting the polishing pad of the present invention.

[Explanation of symbols]

1 Semiconductor wafer 2 surface plate 3 dressing discs 4 Polishing slurry 5 Sample holder 6 polishing pad 7 rotation axis 8 Wafer fixing jig 9 Dressing disc holder 10 Slurry supply pipe 11 Porous plastic particles 12 bubbles

Claims (4)

[Claims] 1. A polishing pad for porous plastic particles, which is composed of plastic particles containing air bubbles. 2. The average diameter of bubbles is 0.1 μm or more and 100.
The porous plastic particle polishing pad according to claim 1, which is less than μm. 3. The average particle diameter of the plastic particles is 300.
The porous plastic particle polishing pad according to claim 1 or 2, which has a diameter of less than μm. 4. The porous plastic particle polishing pad according to claim 1, wherein the plastic is a thermoplastic urethane resin.