JP2003220562A - Apparatus and method for polishing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and method for polishing, by which stability of polishing speed, excellent flatness and step characteristics are achieved, and also reduction, etc., of defects (scratch) produced on a polished surface of a polishing object, such as a semiconductor wafer, can be satisfactorily achieved for various polishing objects. <P>SOLUTION: The apparatus carries out polishing for the polishing object by pressing the polishing object against a polishing tool. The polishing tool is mainly made of a thermoplastic resin, which has average glass-transition temperature (Tg) higher than or equal to 270°K and lower than or equal to 400°K. <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 apparatus and method for polishing an object to be polished such as a semiconductor wafer into a flat and mirror-like state, and more particularly to a fixed abrasive polishing tool or a polishing pad such as a polishing pad. The present invention relates to a polishing technique using a resin.

[0002]

2. Description of the Related Art In recent years, as the degree of integration of semiconductor devices has increased, the wiring of circuits has become finer and the dimensions of integrated devices have also become finer. Therefore, there is a case where a step of removing the coating film formed on the surface of the semiconductor wafer by polishing to flatten the surface is necessary. As a method of this flattening method, polishing is performed by a chemical mechanical polishing (CMP) device. Is being done. This type of chemical / mechanical polishing (CMP) device has a turntable having a polishing cloth (pad) attached thereto and a top ring, and an object to be polished is interposed between the turntable and the top ring to form a top ring. Rotate while applying a constant pressure to the turntable, and supply the abrasive liquid (slurry) to the polishing cloth to polish the surface of the object to be polished flat and mirror-like.

In such chemical / mechanical polishing (CMP), since polishing is performed while supplying a polishing liquid (slurry) containing a large amount of polishing particles to a relatively soft polishing cloth, there is a problem in pattern dependence. . The pattern dependency means that a gentle unevenness due to the unevenness is formed even after polishing due to the unevenness pattern on the semiconductor wafer existing before polishing, and it is difficult to obtain perfect flatness. That is, the polishing rate is high for the fine pitch irregularities, the polishing rate is low for the large pitch irregularities, and the polishing rate is high for the portions where the ratio (density) of the convex portions is low and low for the high proportions. Become. These are problems in that gentle irregularities are formed between a portion having a high polishing rate and a portion having a low polishing rate.

In recent years, a process using fixed abrasive grains has been announced. The fixed abrasive grain process is a process of polishing the surface of a semiconductor wafer or the like using the fixed abrasive grains in which the abrasive grains are fixed in a resin body which is a binder material. Therefore, the polishing basically does not require the supply of a polishing slurry (slurry), and the polishing is mainly performed by the abrasive grains separated from the binder material. In the fixed-abrasive process, very high flatness is obtained because of its high hardness, which is a basic feature. However, on the other hand, there is a defect that the wafer to be polished is apt to be scratched, that is, scratched.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and provides stability of a polishing rate, good flatness and step characteristics, and polishing of an object to be polished of a semiconductor wafer. An object of the present invention is to provide a polishing apparatus and method capable of satisfactorily exerting reduction of defects (scratches) generated on a surface with respect to various objects to be polished.

[0006]

DISCLOSURE OF THE INVENTION The present invention is a polishing apparatus for polishing by sliding an object to be polished while pressing it against a polishing tool, wherein the polishing tool is mainly composed of a thermoplastic resin, Its average glass transition temperature (Tg) is 270
It is characterized in that it is not less than K and not more than 400K. here,
The average glass transition temperature (Tg) is a calculated value obtained from the weight ratio of the monomers constituting the thermoplastic resin by the Fox equation (see paragraph 0032) described later.

In this polishing tool, the glass transition temperature (Tg) of the thermoplastic resin is 320 K (47 ° C.) or less, and the low glass transition temperature (Tg) phase is 10% by weight or more and 90% by weight or less. High glass transition temperature (Tg) with a temperature (Tg) of 320K (47 ° C) or higher is 90% by weight or less and 1
It is preferable to have a multiphase structure consisting of 0% by weight or more. Here, when the high glass transition temperature phase or the low glass transition temperature phase is composed of plural kinds of monomers, the glass transition temperature (Tg) is an average glass transition temperature thereof.

Desirably, this polishing tool has a low glass transition temperature (Tg) phase having a glass transition temperature (Tg) of 310 K (37 ° C.) or less and 20% by weight or more and 80% by weight or less, and a glass transition temperature (Tg). High glass transition temperature (Tg) phase in which (1) is 330 K (57 ° C.) or higher is 80 wt% or less and 20 wt% or more. More desirably, glass transition temperature (Tg)
Low glass transition temperature (T
g) 20% by weight or more and 80% by weight or less, and 80% by weight or more and 20% by weight or more of a high glass transition temperature (Tg) phase having a glass transition temperature (Tg) of 340K (67 ° C) or more.

Further, in this polishing tool, the thermoplastic resin contains 0% by weight or more and 80% by weight or less of an aromatic vinyl monomer,
(Meth) acrylic acid ester-based monomer 0% by weight or more 10
0% by weight or less, and 0% to 50% by weight of a vinyl-based monomer copolymerizable therewith, and the weight average molecular weight of the polymer substance constituting the polishing tool is 5,000.
It is preferably 0 or more and 5,000,000 or less.
The weight average molecular weight of the polymer substance is preferably 10,
It is 000 or more and 3,000,000 or less. However, as the weight average molecular weight, a polystyrene-equivalent value measured by gel permeation chromatography composed of standard polystyrene is used.

The average glass transition temperature (Tg) of this polishing tool is preferably 300K or higher and 380K or lower, and more preferably 310K or higher and 360K or lower.

Up to now, a thermosetting resin such as PVA, a phenol resin or an epoxy resin has been generally widely used as a polishing tool used for polishing a semiconductor wafer or the like. According to the present invention described above, by using a thermoplastic resin in place of the thermosetting resin, in particular, a multi-phase thermoplastic resin having an average glass transition temperature of 270 K or more and 400 K or less, polishing having performance higher than that of a conventional polishing tool A tool can be realized.

In polishing a semiconductor wafer or the like, heat is generated during polishing. In a fixed-abrasive polishing tool or a polishing tool such as a polishing pad, by using a thermoplastic resin having an average glass transition temperature (Tg) lower than the temperature during actual polishing, if the resin generates heat during polishing, the average glass Above the transition temperature, the polishing tool will exhibit flexibility.
This makes it possible to polish with a soft polishing surface and suppress the occurrence of scratches (scratches).

Further, in the case of a resin having many steric crosslinks, in order to expose a new surface (non-deteriorated surface) containing unused abrasive grains, the chemical bond is cut. On the other hand, in the case of a linear polymer that does not substantially include a cross-linked structure, it is preferable that the intermolecular force, which has an energy lower than that of a chemical bond, be mainly divided, and a newly-generated surface can be efficiently expressed, and therefore, it is preferable.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The polishing apparatus of the present invention uses a polishing tool that performs precise polishing by pressing and sliding an object to be polished such as a semiconductor wafer. A fixed-abrasive polishing tool containing grains or a non-fixed-abrasive polishing pad.

First, the composition of the resin used in the polishing tool of the present invention will be described. This polishing tool is mainly composed of a thermoplastic resin, and is made of 50% of the resin that constitutes the polishing tool.
% Or more, preferably 80% or more, more preferably 90%
The thermoplastic resin occupies at least%. Since this polishing tool is mainly composed of a thermoplastic resin,
The balance may include a thermosetting resin. Here, the thermoplastic resin preferably comprises a linear polymer. The linear polymer is a bond in which the main chains are only entangled with each other, and in a fixed abrasive that fixes the abrasive in the resin body, the polishing surface is likely to be regenerated during polishing, and is suitable as a resin body that constitutes a polishing tool. Is.

The average glass transition temperature of the thermoplastic resin is 270K or higher and 400K or lower. As a result, when the resin body generates heat due to polishing, the temperature thereof rises, the thermoplastic resin becomes higher than its average glass transition temperature, and the polishing tool has flexibility. Therefore, it becomes possible to polish with a soft polishing surface, and it is possible to suppress the occurrence of scratches (scratches).

It is preferable that the polishing tool contains a phase of the thermoplastic resin having a high glass transition temperature and a phase having a low glass transition temperature, and the average glass transition temperature falls within the above-mentioned range. In particular, a low glass transition temperature (Tg) phase having a glass transition temperature (Tg) of 320 K or less, and a high glass transition temperature (Tg) phase having a glass transition temperature (Tg) of 320 K or more. Is preferably 90% by weight or less and 10% by weight or more. Also, preferably,
20% by weight of low glass transition temperature (Tg) phase below 310K
Above 80 wt%, the high glass transition temperature (Tg) phase of above 330 K is below 80 wt% and above 20 wt%.
More preferably, the low glass transition temperature (Tg) phase of 300K or less is 20% by weight or more and 80% by weight or less, 34
The high glass transition temperature (Tg) phase of 0 K or more is 80 wt% or less and 20 wt% or more. The average glass transition temperature (Tg) of these is 270K (-3 ° C) or more and 400K.
The material ratio is adjusted so that it is (127 ° C.) or less.
The average glass transition temperature (Tg) is more preferably 300K or higher and 380K or lower, and further 310K or higher and 36K or higher.
It is preferably 0K or less. Further, the ratio of the materials is adjusted so that the above linear polymer becomes a resin that does not cause deterioration such as thermal decomposition in the temperature range of 270 K or more and 400 K or less.

As described above, by having both the high glass transition temperature phase and the low glass transition temperature phase, it plays a role as a hard structure in a place far from the polishing surface and close to room temperature, and by friction near the polishing surface. In a place where the temperature rises, at least the glass transition temperature of the low glass transition temperature phase is reached, so that it has an elastic property. Therefore, it has a high impact absorbing effect in the vicinity of the polishing surface, and scratches can be reduced. Further, since there is a high glass transition temperature phase, it can be prevented that the polishing rate is lowered due to excessive softening even in a high temperature portion in the vicinity of the polishing surface, which is a contradictory relationship between effective polishing and prevention of scratches. Both performances can be achieved.

In the polishing tool of the present invention, the linear polymer constituting the polishing tool has a weight average molecular weight of 5,000 or more and 5,000,
000 or less, preferably 10,000 or more and 30,
It is less than or equal to 0,000. When the molecular weight is small, that is, when the main chain is short, the number of intersecting points of the linear polymers is small, and the bond is weak, so that the surface of the resin molded body (molded body of the linear polymer) has a property of easily collapsing. Conceivable.

When the resin molding is used as a polishing tool,
When an external force is applied during polishing, the outermost surface of the polishing surface peels off, and a new surface (non-deteriorated surface) of the lower layer appears. At this time, in the case of a fixed-abrasive polishing tool, the abrasive grains on the resin surface are released, and new abrasive grains contained in the resin appear from the inside to the outermost surface. That is, the number of working abrasive grains that contribute to processing increases, and high processing efficiency can be realized. In addition, when the molecular weight is large, that is, when the main chain is long (for example, the molecular weight is 5,000
(More than 10,000), bonding is strong on the outermost surface of the working surface of the polishing tool, and many deteriorated abrasive grains remain after polishing, resulting in low processing efficiency, which is not desirable. However, when the molecular weight is extremely small, the physical properties and processability of the polymer are lost, so a certain level of molecular weight (5,000 or more) is required. Therefore, the molecular weight of the linear polymer is 5,000 or more and 5,000,000 or less in terms of weight average molecular weight,
It is preferably 10,000 or more and 3,000,000 or less.

As the thermoplastic resin, in addition polymerization, polyethylene resin, polypropylene resin, polybutadiene resin, polyvinyl chloride resin, polystyrene resin, polyvinylidene chloride resin, fluorine resin, acrylic resin can be used. Resins such as resins based on vinyl monomers can be exemplified, and in the polycondensation system, polyamide resin, polyester resin, polycarbonate resin, polyphenylene oxide resin, etc. can be exemplified, and in the polyaddition system, thermoplastic polyurethane system. Examples of the resin include polyacetal resins in the ring-opening polymerization system. If the above conditions are satisfied, two or more selected from these may be mixed, or the monomer components of these resins may be copolymerized. Due to the ease of adjusting the glass transition temperature and molecular weight,
Of these, a thermoplastic resin based on a vinyl-based monomer is preferable, and particularly, an aromatic vinyl-based monomer 0% by weight or more and 80% by weight or less, and a (meth) acrylic acid ester-based monomer 0% by weight or more 100%. % By weight or less, and 0% by weight or more and 50% by weight or less of a vinyl-based monomer copolymerizable therewith,
Weight average molecular weight of 5,000 or more and 5,000,000
The following linear polymers are preferred. More preferably,
Aromatic vinyl-based monomer 10% by weight or more and 60% by weight or less,
(Meth) acrylic acid ester-based monomer 40% by weight or more 1
And a vinyl-based monomer copolymerizable therewith, which has a weight average molecular weight of 5,000 or more and 5,000,000 or less, and particularly preferably 10 or less. Over 3,000, 3,000
It is 0 or less.

As the aromatic vinyl-based monomer, for example, styrene, α-methylstyrene, o-methylstyrene, p
-Methylstyrene, t-butylstyrene, vinyltoluene, methyl-α-methylstyrene, divinylbenzene,
1,1-diphenylstyrene, vinyl xylene, N, N
-Diethyl-p-aminoethylstyrene, N, N-diethyl-p-aminomethylstyrene, vinylpyridine, vinyltoluene, vinylnaphthalene and the like can be mentioned. Preferably styrene is used.

Examples of the (meth) acrylic acid ester type monomer include (1) methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, and acrylic. Cyclohexyl acid, alkyl acrylates such as phenyl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, hydroxylethyl acrylate, and (2) methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methacrylic acid. Hexyl, octyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, phenyl methacrylate, benzyl methacrylate, etc. Kill ester, glycidyl methacrylate, methacrylic acid hydroxyethyl, and the like, butyl acrylate, methyl methacrylate, butyl methacrylate are preferably used.

As the vinyl-based monomer copolymerizable with the above monomers, acrylonitrile (AN), methacrylonitrile, butadiene, isoprene, ethylene, propylene, vinyl chloride, vinylidene chloride, acrylic acid, methacrylic acid Etc. can be illustrated. If necessary, a polyfunctional monomer such as allyl methacrylate, 1,3-butanediol, and divinylbenzene can be used, but is not added in order to obtain a linear polymer having a preferable weight average molecular weight. Alternatively, it is preferable to add only a small amount.

The method for obtaining the above-mentioned thermoplastic resin is not particularly limited, and known polymerization methods such as bulk polymerization method, suspension polymerization method, emulsion polymerization method and solution polymerization method can be used.
Moreover, the polymers obtained by these can also be mixed and used. The polymerization initiator, molecular weight modifier, etc. are not particularly limited, and known ones can be used. The dispersant, emulsifier, etc. used when the suspension polymerization method, emulsion polymerization method, etc. are adopted are not particularly limited, and known ones can be used.

It is also possible to employ an emulsifier-free emulsion polymerization method to reduce impurities. The method for obtaining the thermoplastic resin having a plurality of phases is not particularly limited, and examples thereof include a method of mixing a plurality of resins obtained in advance by a known method, a method of controlling so as to have a multiphase structure during polymerization, and the like. The phase structure and its phase unit vary depending on the method adopted. A macro phase structure having a phase unit of several μm or more or several tens of nm
Those having a microphase structure of several μm or less or a unit of several tens nm or less (block copolymers can be exemplified)
Can be exemplified, and those having a phase unit of 1 μm or less are preferable, and it is more preferable that the average particle diameter of the abrasive grains used is about the same or smaller.

Next, the properties of this polishing tool will be described. A polishing tool made of a thermoplastic resin that has a glass transition temperature (Tg) lower than the polishing temperature becomes a rubber state during wafer polishing, and its flexibility and shock absorption become high, so scratches are generated during wafer polishing. Is less likely to occur. However, the glass transition temperature (Tg) is at room temperature (25
The resin of (° C.) or less has a rubber-like property at room temperature and a soft property. Therefore, even if it is possible to suppress the occurrence of scratches, it becomes difficult to exhibit the high flattening performance that is a feature of fixed abrasive grains, and the tool durability is poor. Therefore, by using a resin containing a resin phase with a high glass transition temperature (Tg) and a resin phase with a low glass transition temperature (Tg), the average glass transition temperature (Tg) is around room temperature and the polishing surface is Microscopically, a rubber-like property and a scratch suppressing effect are exhibited due to a temperature rise during polishing. At the same time, low tackiness, which is a characteristic of a resin having a high glass transition temperature (Tg), and the characteristics of a resin having excellent handleability are exhibited, and flat polishing property is exhibited.

In the polishing tool of the present invention, the semiconductor wafer having the device pattern is slid while being pressed,
Perform polishing. Therefore, the polishing tool using the thermoplastic linear polymer as described above can perform polishing with very few scratches, and can achieve good polishing characteristics for polishing semiconductor wafers, and at the same time, manufacture the polishing tool. It's easy. Up to now, thermosetting resins such as PVA, phenolic resins, and epoxy resins have been generally widely used for polishing tools such as semiconductor wafers. In the present invention, a thermoplastic resin is used instead of the thermosetting resin, and particularly, the average glass transition temperature is 270K.
By using the resin adjusted to 400 K or less, a polishing tool having performance higher than that of the conventional polishing tool can be realized. The polishing tool is embodied as a fixed-abrasive polishing tool containing abrasive grains in the polishing tool or a non-fixed-abrasive polishing pad.

In the case of a fixed-abrasive polishing tool, this polishing tool contains abrasive grains, and cerium oxide (Ce oxide) is used as the abrasive grain raw material.
0 ₂ ), alumina (Al ₂ O ₃ ), silicon carbide (Si
C), silicon oxide _(Si0 2), zirconium (Zr
0 ₂ ), iron oxide (Fe 0, Fe ₃ 0 ₄ ), manganese oxide (Mn 0 ₂ , Mn ₂ 0 ₃ ), magnesium oxide (Mg
O), calcium oxide (CaO), barium oxide (Ba)
0), zinc oxide (ZnO), barium carbonate (BaC)
O ₃ ), calcium carbonate (CaCO ₃ ), diamond (C), or a composite material thereof is used. Also,
The abrasive grain raw material may be either a powder raw material or a slurry raw material, but in order to produce a uniform fixed abrasive grain, it is desirable to use slurry-like abrasive grains which are stably present as fine abrasive grains. More desirably, it is desirable to use abrasive grains having a grain size of 10 nm or more and 10 μm or less. Further, in order to use it as a polishing tool for semiconductor processing, it is desirable to minimize the amount of metal contained in the abrasive grain raw material.

The fixed-abrasive polishing tool is composed of abrasive grains, a binder and holes. As the binder, the thermoplastic resin of the present invention is mainly used. Fixed abrasive composition ratio (abrasive ratio
(Vg) to binder ratio (Vb) to porosity (Vp) ratio: vol%)
Is, as an example, abrasive grain ratio (Vg): binder ratio (Vb): porosity (Vp) = 35: 5
It is 5:10 (vol%). Fixed abrasive composition ratio (abrasive ratio (Vg) and binder ratio)
(Vb) to porosity (Vp) ratio: vol%) is generally 10% <abrasive grain ratio (Vg) <50%, 30% <binder ratio (Vb) <80%, 0% <porosity Ratio (Vp) <40%, 20% <abrasive grain ratio (Vg) <45%, 40% <binder ratio (Vb) <70%, 0% <porosity (Vp) <20%, 30% <abrasive grain ratio (Vg) <40%, 50% <binder ratio (Vb) <60%, 5% <porosity (Vp) <15% are more desirable.

Next, examples of the polishing tool of the present invention will be described. Styrene (S
t), methyl methacrylate (MMA), butyl acrylate (B
A) and butyl methacrylate (BMA) are used. The monomer mixing ratio at this time is as follows. St: MMA: BA: BMA = 34: 33: 29: 4 (parts by weight) The glass transition temperature (Tg) of the homopolymer obtained from each monomer is as shown in Table 1.

[Table 1]

The above monomer mixture was emulsion polymerized according to a known method, and the obtained polymer was separated. The average glass transition temperature (Tg-ave) is obtained by the Fox equation, Tg [K] = 100 / Σ (i) {W (i) / Tg (i)} [K]. Substituting this equation for calculation, Tg [K] = 100 / Σ (i) {W (i) / Tg (i)} [K] = 100 / (34/373 + 29/219 + 33/378 + 4/293) [K ] = 100 / (0.32452637) [K] = 308 [K] = 35 [℃] where W (i) is the weight% of polymer (i) and Tg (i) is polymer
It is the glass transition temperature Tg [K] of (i).

The average glass transition temperature (Tg-ave) in the case of the above material ratio is 308K (35 ° C), so that 270K (-3 ° C) <Tg-ave <400K (127 ° C), which is described above. Satisfies the conditions.

As a second embodiment, styrene (St) is used as the aromatic vinyl monomer, and methyl methacrylate (MM) is used as the (meth) acrylic acid ester monomer.
A), butyl acrylate (BA), butyl methacrylate (B
MA) is used and the weight part is changed as follows.
That is, an appropriate amount of n-octyl mercaptan was added as a molecular weight modifier to a monomer mixture of St: MMA: BA: BMA = 18: 3: 29: 0 (parts by weight), and then seed particles were polymerized to obtain seeds. St: MMA: BA: BMA = 16: 30: 0: 4 (parts by weight) in the presence of particles, a suitable amount of n-octyl mercaptan was added as a molecular weight modifier to the monomer mixture for dropwise addition, and polymerization was performed. did. 50% by weight of the seed particles have a low glass transition temperature phase (T
g = 265K), a polymer of 50% by weight of the dropping monomer mixture constitutes a high glass transition temperature phase (Tg = 368K), and an average glass transition temperature of the entire polymer is 308K. Got This multiphase polymer was a linear polymer having substantially no crosslinked structure, and its weight average molecular weight was 100,000.

Next, the polishing performance when a fixed-abrasive polishing tool manufactured using the obtained polymer is used will be described. As an example, a polishing rate of about 2000 Å / min was obtained, the flatness was extremely excellent, and the uniformity was good. When scratches occur, 2 per wafer
The result of 15 pieces was obtained, and compared with the performance of the chemical mechanical polishing (CMP) performed by the combination of the conventional standard polishing pad (SS-25) and the standard polishing liquid (IC1000 / SUBA400), The same or better performance was obtained.

Next, an outline of the method for manufacturing this polishing tool will be described. The thermoplastic resin (polymer) is produced by polymerizing a monomer (monomer). At that time, various agents such as polymerization catalysts represented by organometallic compounds and inorganic metal compounds, polymerization inhibitors, dispersants, activators, solvents, catalyst deactivators, stabilizers, emulsifiers, antioxidants, and water. Is used to form a polymer compound through complicated steps. In order to reduce the mixing of metal elements in the polymeric material used for this polishing tool, it is desirable to reduce the chemicals and metal compounds of water used in the various polymerization steps described above. It is desirable to use water, ultrapure water, or high-purity solvent.

Further, the form of the polymer material may be either powder raw material or liquid raw material, but the composition ratio of the granulated powder as an intermediate product is made uniform, and in the case of a fixed abrasive polishing tool, In order to improve the dispersion homogeneity of the particles, it is desirable to use a latex suspension in which the abrasive particles are homogeneously dispersed in the liquid. Furthermore, for semiconductor processing applications, that is, in order to achieve wafer polishing with less metal contamination, it is desirable to minimize the amount of metal contained in the polymer material.

Various emulsion polymerization methods can be used for the production of the above polymer. For example, a seed polymerization method is known.
First, a monomer or a mixture of monomers is divided into an initial addition monomer and a dropping monomer. Next, a pH buffering agent such as boric acid or sodium carbonate is added to the aqueous medium, the aqueous medium is heated to 70 ° C. or higher and 85 ° C. or lower, and persulfate such as potassium persulfate is stirred under an inert atmosphere. After the salt polymerization initiator is added, the above-mentioned initial addition monomer is added all at once and kept for a certain period of time to form seed particles. Subsequently, the persulfate polymerization initiator is added again to this polymerization system, and then the above-mentioned monomer for dropping is immediately added dropwise over a certain period of time and kept for a certain period of time. At this time, it is also possible to obtain a multiphase polymer having different glass transition points by changing the compositions of the initial addition monomer and the dropping monomer.

After producing a mixed solution in which various materials are polymerized in a required ratio, this is dried to obtain a mixed powder. The drying treatment may be natural drying, heat drying or freeze drying, but it is preferable to use a spray dryer. The obtained mixed powder is compression molded by a mold under an appropriate temperature condition to manufacture a polishing tool having a predetermined shape. In addition to the above-mentioned drying method, a method of preparing a mixed powder by utilizing the aggregation and / or precipitation action may be adopted. The production of the powder (mixed powder) may be performed by a drying step after mixing, a mixing step after drying, or these steps as appropriate, if necessary. Further, depending on the materials to be mixed, a step of directly mixing dry powders of a plurality of materials may be taken. In addition, a step of washing with water or an organic solvent can be adopted in the above steps for the purpose of reducing the amount of metal and other impurities mixed in.

In manufacturing the fixed-abrasive polishing tool, the abrasive raw material may be uniformly dispersed when the resin is polymerized. In order to improve the dispersion homogeneity of the abrasive grains, it is desirable to use a suspension in which the abrasive grains are homogeneously dispersed in the liquid. Thereafter, the mixed powder is dried to form a mixed powder, and the mixed powder is compression-molded to manufacture a fixed-abrasive polishing tool.

An example of the structure of the polishing apparatus according to the present invention will be described below. FIG. 1 is a plan view showing the overall configuration of a polishing apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the polishing apparatus according to this embodiment includes four load / unload stages 2 on which a wafer cassette 1 for stocking a large number of semiconductor wafers is placed. The load / unload stage 2 may have a mechanism capable of moving up and down. A transfer robot 4 is arranged on the traveling mechanism 3 so that each wafer cassette 1 on the load / unload stage 2 can be reached.

The transfer robot 4 is provided with two hands, an upper hand and a lower hand. The lower hand of the two hands of the transfer robot 4 is a suction type hand for vacuum-sucking the wafer, and is used only when receiving the semiconductor wafer from the wafer cassette 1. This suction type hand can accurately convey the wafer regardless of the deviation of the wafer in the cassette. On the other hand, the upper hand of the transfer robot 4 is a drop-type hand that holds the peripheral edge of the wafer, and is used only when the semiconductor wafer is returned to the wafer cassette 1. Since this drop-in hand does not collect dust unlike the suction-type hand, the wafer can be transported while maintaining the cleanness of the back surface of the wafer. The clean wafer thus cleaned is arranged on the upper side to prevent the wafer from being soiled further.

Two washing machines 5 and 6 for washing the semiconductor wafer are arranged on the side opposite to the wafer cassette 1 with the traveling mechanism 3 of the transfer robot 4 as the axis of symmetry. The washing machines 5 and 6 are arranged at positions where the hand of the transfer robot 4 can reach. Further, these washing machines 5 and 6 have a spin dry function of rotating the wafer at a high speed to dry the wafer, so that it is possible to deal with the wafer without changing the module in the two-stage cleaning and the three-stage cleaning of the wafer. You can

Between the two washing machines 5 and 6, a semiconductor wafer mounting table 7 is provided at a position where the transfer robot 4 can reach.
A wafer station 12 including four 8, 9, 10 is arranged. Washing machine 5 and three mounting tables 7, 9, 10
A transfer robot 14 having two hands is arranged at a position where can be reached. Further, a transfer robot 15 having two hands is arranged at a position where the cleaning machine 6 and the three mounting tables 8, 9, 10 can be reached.

The mounting table 7 is used to transfer semiconductor wafers between the transfer robot 4 and the transfer robot 14, and the mounting table 8 is transferred to the transfer robot 4 and the transfer robot 1.
It is used to transfer semiconductor wafers to and from 5. These mounting tables 7 and 8 are respectively provided with detection sensors 16 and 17 for detecting the presence or absence of a semiconductor wafer.

The mounting table 9 is used to transfer the semiconductor wafer from the transfer robot 15 to the transfer robot 14, and the mounting table 10 is used to transfer the semiconductor wafer from the transfer robot 14 to the transfer robot 15. These mounting tables 9 and 10 are provided with detection sensors 18 and 19 for detecting the presence or absence of a semiconductor wafer, and rinse nozzles 20 and 21 for preventing the semiconductor wafer from drying or cleaning the wafer. .

These mounting tables 9 and 10 are arranged in a common waterproof cover, and a shutter 22 is provided at an opening portion for carrying provided in this cover. The mounting table 9 is located above the mounting table 10. The wafer after cleaning is mounted on the mounting table 9, and the wafer before cleaning is mounted on the mounting table 10. With such a structure, the contamination of the wafer due to the fall of the rinse water is prevented. Note that, in FIG. 1, the sensors 16, 17, 18, and 19, the rinse nozzles 20 and 21, and the shutter 22 are schematically illustrated, and their positions and shapes are not accurately illustrated.

A washing machine 24 is arranged adjacent to the washing machine 5 at a position reachable by the hand of the transfer robot 14. A washing machine 25 is arranged adjacent to the washing machine 6 at a position where the hand of the transfer robot 15 can reach. These washing machines 24 and 25 are washing machines capable of washing both sides of the wafer.

The upper hands of the transfer robot 14 and the transfer robot 15 are used to transfer the once cleaned semiconductor wafer to the mounting table of the cleaning machine or the wafer station 12. On the other hand, the lower hand is used to convey a semiconductor wafer that has never been cleaned and a semiconductor wafer that has not been polished. By using the lower hand to move the wafer in and out of the reversing machine, which will be described later, the upper hand is not contaminated by the rinsing water droplets from the upper wall of the reversing machine.

Shutters 5a, 6a, 24a, and 5a, 6a, 24a, are provided at the wafer carry-in ports of the washing machines 5, 6, 24, 25, respectively.
25a is attached and can be opened only when the wafer is loaded.

The polishing apparatus is provided with a housing 26 so as to surround each device, and the inside of the housing 26 is a partition wall 2.
It is divided into a plurality of regions (including the region A and the region B) by 8, the partition wall 30, the partition wall 32, the partition wall 34, and the partition wall 36.

The area A in which the wafer cassette 1 and the transfer robot 4 are arranged, the washing machines 5, 6 and the mounting tables 7, 8,
A partition wall 28 is arranged between the area B in which 9 and 10 are arranged in order to separate the cleanliness of the area A and the area B. The partition 28 is provided with an opening for transporting the semiconductor wafer between the area A and the area B, and a shutter 38 is provided in this opening.
The cleaning machines 5, 6, 24, 25, the mounting tables 7, 8, 9, 10 of the wafer station 12, and the transfer robot 1
All of 4, 15 are arranged in the area B, and the pressure in the area B is adjusted to be lower than the atmospheric pressure in the area A.

A reversing machine 40 for reversing the semiconductor wafer to a position where the hand of the transfer robot 14 can reach within the area C separated from the area B by the partition wall 34.
The semiconductor wafer is transferred to the reversing machine 40 by the transfer robot 14. Further, inside the area C, a reversing machine 41 for reversing the semiconductor wafer is arranged at a position where the hand of the transfer robot 15 can reach, and the semiconductor wafer is transferred to the reversing machine 41 by the transfer robot 15. Reversing machine 40 and reversing machine 41
Is provided with a chuck mechanism for chucking the semiconductor wafer, a reversing mechanism for reversing the front surface and the back surface of the semiconductor wafer, and a detection sensor for confirming whether the semiconductor wafer is chucked by the chuck mechanism.

A partition chamber 34 defines a polishing chamber which is partitioned from the region B, and the partition chamber 36 further partitions the polishing chamber into two regions C and D. The partition wall 3 that divides the region B from the regions C and D
An opening for transporting a semiconductor wafer is provided at 4, and shutters 42 and 43 for the reversing machine 40 and 41 are provided at this opening.

In each of the two regions C and D, two polishing tables and one top ring for holding one semiconductor wafer and polishing while pressing the semiconductor wafer against the polishing table are arranged. There is. That is, in the area C, the top ring 44 and the polishing table 4
6, 48, a polishing liquid supply nozzle 50 for supplying the polishing liquid to the polishing table 46, and an atomizer 52 having a plurality of injection nozzles (not shown) connected to the nitrogen gas supply source and the liquid supply source. A dresser 54 for dressing the polishing table 46 and a dresser 56 for dressing the polishing table 48 are arranged. Similarly, in the region D, the top ring 45, the polishing tables 47 and 49, the polishing liquid supply nozzle 51 for supplying the polishing liquid to the polishing table 47, the nitrogen gas supply source, and the liquid supply source are connected. An atomizer 53 having a plurality of jet nozzles (not shown), a dresser 55 for dressing the polishing table 47, and a dresser 57 for dressing the polishing table 49 are arranged.

The polishing liquid supply nozzles 50 and 51 supply the polishing liquid used for polishing and the dressing liquid (for example, water) used for dressing onto the polishing tables 46 and 47, respectively. Further, a liquid obtained by mixing nitrogen gas and pure water or a chemical liquid is jetted from the atomizers 52 and 53 onto the polishing tables 46 and 47. The nitrogen gas from the nitrogen gas supply source and the pure water or the chemical liquid from the liquid supply source are adjusted to a predetermined pressure by a regulator (not shown) or an air operator valve, and the atomizer 5 is mixed with the two.
It is supplied to 2,53 injection nozzles. In this case, it is preferable that the spray nozzles of the atomizers 52 and 53 spray liquid toward the outer peripheral sides of the polishing tables 46 and 47. Note that other inert gas may be used instead of nitrogen gas. Further, only the liquid such as pure water or chemical liquid may be ejected from the atomizers 52 and 53. An atomizer may also be provided on the polishing tables 48 and 49. By providing atomizers on the polishing tables 48, 49, the surfaces of the polishing tables 48, 49 can be kept cleaner.

The mixed nitrogen gas and pure water or chemical solution are
In the state of liquid atomization, solidification of liquid solidification, and vaporization of liquid (these are referred to as atomization or atomization), the spray nozzles of atomizers 52 and 53 direct the polishing tables 46 and 47. Is jetted. The mixed liquid becomes liquid fine particles, fine particle solidification,
Which state of gasification is injected is determined by the pressure, temperature, nozzle shape, etc. of nitrogen gas and / or pure water or a chemical solution. Therefore, the state of the ejected liquid can be changed by appropriately changing the pressure, temperature, nozzle shape, etc. of the nitrogen gas and / or the pure water or the chemical liquid by the regulator or the like.

A wet type wafer film thickness measuring machine may be installed instead of the polishing tables 48 and 49. In that case, the film thickness of the wafer immediately after polishing can be measured, and it is possible to control the polishing process for the next wafer by further cutting the wafer and utilizing the measured value.

Below the reversing machines 40 and 41 and the top rings 44 and 45, a rotary transporter 60 for transferring a wafer between the cleaning chamber (region B) and the polishing chambers (regions C and D) is arranged. The rotary transporter 60 is provided with four stages on which wafers are placed at equal positions so that a plurality of wafers can be loaded at the same time.

The wafer transported to the reversing machines 40 and 41 has the center of the stage of the rotary transporter 60,
When the center of the wafer chucked by the reversing machine 40 or 41 is in phase, the lifter 62 or 63 installed below the rotary transporter 60 moves up and down,
It is conveyed onto the rotary transporter 60. The wafer placed on the stage of the rotary transporter 60 is transferred below the top ring 44 or 45 by changing the position of the rotary transporter 60 by 90 °. The top ring 44 or 45 is swung in advance to the position of the rotary transporter 60. Top ring 44
Alternatively, when the center of the wafer 45 is in phase with the center of the wafer mounted on the rotary transporter 60, the pushers 64 or 65 disposed below them move up and down to move the wafer from the rotary transporter 60 to the top. Transferred to ring 44 or 45.

Next, the polishing chamber will be described in more detail. Although only the area C will be described below,
The region D can be considered similarly to the region C.
FIG. 2 shows the top ring 44 and the polishing table 4 in the area C.
It is a figure which shows the relationship with 6,48.

As shown in FIG. 2, the top ring 44 is suspended from a top ring head 72 by a rotatable top ring drive shaft 70. Top ring head 7
2 is supported by a swingable shaft 74 which can be positioned, and the top ring 44 can access both the polishing tables 46 and 48.

The dresser 54 is suspended from a dresser head 78 by a rotatable dresser drive shaft 76. The dresser head 78 is a swingable shaft 80 that can be positioned.
The dresser 54 can be moved between a standby position and a dresser position on the polishing table 46. Similarly, the dresser 56 is suspended from a dresser head 84 by a rotatable dresser drive shaft 82. The dresser head 84 is supported by a positionable swing shaft 86, which allows the dresser 56 to move between a standby position and a dresser position on the polishing table 48.

The upper surface of the polishing table 46 has abrasive grains, pores and
Is a fixed abrasive in which a porosity agent and a binder (resin) are combined
This fixed abrasive grain 46a is composed of grains 46a.
Wafer held by the top ring 44 by the
A polishing surface is formed for polishing. This fixed abrasive is as described above
It is mainly composed of a thermoplastic resin. Well
Further, instead of the fixed abrasive grains, a thermoplastic resin is mainly used.
The polishing pad formed may be used. This
The fixed abrasive grain 46a is, for example, a slurry-like abrasive (liquid
(With abrasive grains dispersed in the body) and emulsion resin
Mix and disperse the mixed liquid by spray-drying and mold this mixed powder
It is obtained by filling a jig and pressurizing and heating. As an abrasive
Preferably, the average particle size is 0.5 μm or less.
A (CeO _Two) Or silica (SiO_Two) Is used.

The upper surface of the polishing table 48 is made of a soft non-woven fabric, and this non-woven fabric constitutes a cleaning surface for cleaning the abrasive grains attached to the surface of the semiconductor wafer after polishing. In the polishing, a polishing liquid containing no abrasive grains (pure water or pure water + additive) is used as the fixed abrasive grains 46.
Polish while feeding onto a.

The semiconductor wafer polished by the fixed abrasive grains 46a as described above is moved to the polishing table 48 having a small diameter, where buff cleaning is performed. That is, the semiconductor wafer after polishing held by the top ring 44 is pressed against the soft nonwoven fabric on the polishing table 48 while rotating the top ring 44 and the polishing table 48 independently of each other. At this time, a liquid containing no abrasive grains, for example, pure water or an alkaline liquid, preferably an alkaline liquid having a pH of 9 or more or an alkaline liquid containing TMAH, is supplied to the nonwoven fabric from a cleaning liquid supply nozzle (not shown). This makes it possible to effectively remove the abrasive grains attached to the surface of the semiconductor wafer after polishing.

Next, an example of use of the polishing tool of the present invention will be described. FIG. 3 shows a main part of the polishing apparatus. This polishing apparatus has a fixed-abrasive polishing tool 101 on the surface.
And a liquid supply nozzle 103 for supplying water or a chemical liquid W containing no abrasive grains during polishing. Here, the fixed-abrasive polishing tool 101 is mainly composed of a thermoplastic resin in which phases having different glass transition temperatures are mixed and the average glass transition temperature is adjusted to 270 K or more and 400 K or less. A polishing object 5 such as a wafer so as to face the fixed-abrasive polishing tool 101.
Is provided with a top ring 106 for holding. The semiconductor wafer that is the object to be polished 105 is the top ring 106.
Is pressed against the fixed-abrasive polishing tool via the elastic mat and is rotationally driven by the drive shaft 107. On the other hand,
The turntable 102 to which the fixed-abrasive polishing tool is fixed is also independently driven to rotate by its drive shaft 104. Here, the surface to be polished of the semiconductor wafer comes into contact with the surface of the fixed-abrasive polishing tool and slides to perform polishing. proceed.

FIG. 4 shows a main part of a polishing apparatus using a polishing abrasive liquid (slurry). This apparatus includes a polishing pad 111 using a thermoplastic resin adjusted so that the average glass transition temperature of the present invention is 270 K or more and 400 K or less. The polishing pad 111 is used for the polishing table 11
2, a top ring 116 for holding a semiconductor wafer, which is an object 115 to be polished, is arranged so as to face the polishing pad 111. A slurry Q containing a large amount of polishing abrasive grains is supplied onto the polishing pad 111 from a slurry supply nozzle 113. The surface to be polished of the semiconductor wafer slides while being pressed against the polishing pad 111 to which the slurry containing a large amount of polishing abrasive grains is supplied in this way, whereby the polishing of the surface to be polished proceeds.

For these fixed-abrasive polishing tools or polishing pads, a thermoplastic resin adjusted to have an average glass transition temperature of 270K or more and 400K or less is used. For this reason, the surface of the polishing tool exhibits a soft property due to the temperature rise during polishing, which allows soft polishing without causing scratches and the like. At the same time, since the average glass transition temperature is near the temperature at the time of polishing, it also has a hard property as a resin and can perform polishing excellent in flatness and homogeneity.

Although the turntable type has been described in the above-mentioned use example, the present invention is not limited to the turntable type, and may be applied to a scroll type or cup type polishing apparatus in which the polishing tool and the object to be polished make a translational circular motion. The application of the polishing tool of is also possible. As described above, the above embodiment merely describes one preferable mode of the present invention, and it goes without saying that various embodiments can be adopted without departing from the gist of the present invention.

[0072]

As described above, according to the present invention, there is provided a polishing apparatus capable of high-quality polishing. As a result, it is possible to perform a precise polishing process with less scratches.

[Brief description of drawings]

FIG. 1 is a plan view showing an overall configuration of a polishing apparatus according to an embodiment of the present invention.

FIG. 2 is a front view of the polishing chamber in FIG.

FIG. 3 is a diagram showing a main part of a polishing apparatus using a fixed-abrasive polishing tool according to an embodiment of the present invention.

FIG. 4 is a diagram showing a main part of a polishing apparatus using a polishing pad according to an embodiment of the present invention.

[Explanation of symbols]

1 Wafer cassette 2 Load / unload stage 3 Travel mechanism 4, 14, 15 Transfer robot 5, 6, 24, 25 Washer 5a, 6a, 22, 24a, 25a, 38, 42, 43
Shutter 7,8,9,10 Mounting table 12 Wafer station 16,17,18,19 Detection sensor 20,21 Rinse nozzle 26 Housing 28,30,32,34,36 Partition wall 40,41 Inverter 44,45 Top ring 46 , 47, 48, 49 Polishing table 46a Fixed abrasive grains 50, 51 Polishing liquid supply nozzle 52, 53 Atomizer 54, 55, 56, 57 Dresser 60 Rotary transporter 62, 63 Lifter 64, 65 Pusher 70 Top ring drive shaft 72 Top Ring heads 74, 80, 86 Swing shafts 76, 82 Dresser drive shafts 78, 84 Dresser heads 101 Fixed abrasive polishing tools 102, 112 Turntables 103, 113 Nozzles 104, 114 Drive shafts 105, 115 Polishing objects 106, 116 Top ring 107,117 Drive shaft 111 polishing pad

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09K 3/14 550 C09K 3/14 550C H01L 21/304 622 H01L 21/304 622F // C08L 33:04 C08L 33:04 F-term (reference) 3C058 AA07 AA09 CA01 CB02 DA12 3C063 AA10 BB01 BB02 BB03 BB07 BC03 BC10 EE10 FF23 4F071 AA12X AA15X AA20X AA22X AA24X AA25X AA32X AA33 AA33X AA34X AA81 AA86 AF53 AH19 DA17 4J100 AA02R AA03R AB00Q AB02Q AB03Q AB04Q AB07Q AB13Q AB16Q AC02R AC03R AJ02R AL03P AL04P AL05P AL08P AL09P AL10P AL11P AM02R AQ12Q AS02R AS03R BA31Q BC04P CA01 CA04 CA05 DA01 DA25 DA47 JA28 JA43

Claims (9)

[Claims] 1. A polishing apparatus for polishing by sliding an object to be polished while pressing it against a polishing tool, wherein the polishing tool is mainly composed of a thermoplastic resin and has an average glass transition temperature (Tg). Is 270K or more and 400K or less. 2. A polishing apparatus for polishing by sliding an object to be polished while pressing it against a polishing tool, wherein the polishing tool is mainly composed of a thermoplastic resin, and the glass transition temperature of the thermoplastic resin ( The low glass transition temperature (Tg) phase having a Tg of 320K or lower is 10% by weight or more and 90% by weight or less, and the high glass transition temperature (Tg) phase having a glass transition temperature (Tg) of 320K or higher is 90% by weight. The polishing apparatus is characterized by comprising 10% by weight or more below. 3. A polishing apparatus for polishing by sliding an object to be polished while pressing it against a polishing tool, wherein the polishing tool is mainly composed of a thermoplastic resin, and the thermoplastic resin is an aromatic vinyl. 0% to 80% by weight
And (meth) acrylic acid ester-based monomer 0% by weight or more and 100% by weight or less, and a vinyl-based monomer copolymerizable with them of 0% by weight or more and 50% by weight or less. A polishing apparatus characterized by being 5,000 or more and 5,000,000 or less. 4. The polishing apparatus according to claim 1, wherein the thermoplastic resin is a linear polymer. 5. The polishing tool is a fixed-abrasive polishing tool containing abrasive grains in the polishing tool.
4. The polishing apparatus according to any one of 3 to 3. 6. The polishing apparatus according to claim 1, wherein the polishing tool is a polishing pad made of non-fixed abrasive grains. 7. In a polishing method for polishing by sliding an object to be polished while pressing it against a polishing tool, a thermoplastic resin having a glass transition temperature of 270 K or more and 400 K or less is used for the polishing tool. And polishing method. 8. A low glass transition temperature (Tg) having a glass transition temperature (Tg) of 320 K or less as the polishing tool, in the polishing method of polishing by sliding an object to be polished while pressing it against the polishing tool. ) A thermoplastic resin comprising a phase of 10% by weight or more and 90% by weight or less and a glass transition temperature (Tg) of 320K or more and a high glass transition temperature (Tg) phase of 90% by weight or less and 10% by weight or more. A polishing method characterized by being used. 9. A polishing method for polishing by sliding an object to be polished while pressing it against a polishing tool, wherein as the polishing tool, an aromatic vinyl monomer is 0% by weight or more and 80% by weight or less, The (meth) acrylic acid ester-based monomer is 0% by weight or more and 100% by weight or less, and the vinyl-based monomer copolymerizable with these is 0% by weight or more and 50% by weight or less, and has a weight average molecular weight of 5, 000 or more 5,000,00
A polishing method comprising using a thermoplastic resin having a high glass transition temperature (Tg) phase of 0 or less and 90% by weight or more and 10% by weight or more.