WO2017091945A1

WO2017091945A1 - Wafering process for water based slurries

Info

Publication number: WO2017091945A1
Application number: PCT/CN2015/095987
Authority: WO
Inventors: Matthias BRAEM; Zhaoyu FAN
Original assignee: Solvay China Co Ltd; Rhodia Operations SAS
Current assignee: Solvay China Co Ltd; Rhodia Operations SAS
Priority date: 2015-11-30
Filing date: 2015-11-30
Publication date: 2017-06-08
Anticipated expiration: 2018-05-30

Abstract

Processes for improving the cutting performance of a wire saw utilizing semi-aqueous or aqueous slurries comprises (a) contacting a cutting wire with a cutting slurry composition that comprises: (a.i) an abrasive component; (a.ii) a suspending component; (a.iii) at least one defoamer or wetting agent; (a.iv) water; and (a.v) optionally, at least one water miscible solvent; (b) adjusting a slurry flow rate to greater than or equal to 3000 kg/hr. m; and (c) adjusting a wire speed of the cutting wire to greater than or equal to 1 m/sand within a wire speed range having a wire speed lower limit and a wire speed upper limit wherein the wire speed range is determined by formula (I): (-a1) (x) + b1 ≤ y ≤ (a2) (x) + b2; wherein: "(-a1) (x) + b1" is the wire speed lower limit, "(a2) (x) + b2" is the wire speed upper limit, "x" is the slurry flow rate, "y" is the wire speed, and a1, a2, b1 and b2 each individually are positive coefficients; wherein the viscosity of the slurry is maintained at lower than 1000 cPs for a period of time.

Description

WAFERING PROCESS FOR WATER BASED SLURRIES

FIELD OF INVENTION

This invention relates to improvements in wire saw and wafering processes utilizing aqueous or semi-aqueous slurries as cutting liquids and, in particular, process settings using such cutting liquids.

BACKGROUND OF THE INVENTION

Wire saw processes, with its ability to cut very thin wafers from large diameter crystalline ingots of semiconductor materials, has emerged as one method for wafer production across many industries. This process generates thin substrates of semiconductor materials commonly referred to as “wafers. ” Wafers are essential to many industries such as integrated circuit and photo-voltaic industries. Common substrate materials subjected to “wafering” in these industries include, for example, silicon, sapphire, silicon carbide, aluminum nitride, tellurium, silica, gallium arsenide, indium phosphide, cadmium sulfide, germanium, zinc sulfide, gray tin, selenium, boron, silver iodide, and indium antimonide, among other materials.

During a typical wire saw process, a strand of thin wire moves from a feed reel to a take-up reel. The wire, in between, fees through the entrance side of storage system called the “carriage” and into the arrangement of fixed shafts with replaceable wire guides. The wire wraps around the wire guides which have hundreds of grooves. This creates one or multiple nets of parallel wires known webs through which the mass of substrate material, which in its unwafered state is typically called an ingot, is fed together with abrasive slurry to produce a cut.

The wire typically can comprise one or more of steel, iron, metal alloy, composite material, magnetic material, diamond, stainless steel, aluminum, brass, nickel titanium, and copper, to name a few. The cutting increases in efficiency by applying abrasive particles to the interfacing surfaces of the wire and the substrate material. Typically, a standard cutting slurry, such as polyethylene glycol and about 50％by weight silicon carbide abrasive, is pumped over the interfacing surfaces during sawing. Other abrasive particles used in standard cutting slurry compositions may include one or more of silicon carbide, diamond, iron oxide, tin oxide, cerium oxide, silica, aluminum oxide, tungsten carbide, and titanium carbide, among others. A portion of the abrasive in the cutting slurry follows the wire as it is drawn across a surface of the ingot. In so doing, the abrasive particles act to remove a portion of the substrate material from the ingot, thereby widening and deepening the cut and, if the cut is located close and parallel to the surface, resulting in a wafer. In some cases, an aqueous or semi-aqueous slurry is utilized.

One problem with aqueous or semi-aqueous slurries, however, is the problem of wafer thickness variation. Wafer thickness control is very difficult with water based slurries: many wafers are either way too thin or way too thick. In its most extreme form this problem is called “Thick-Thin” . Several practices (ingot tilting, increased SiC loading, ceramic strips) are available in literature for polyethylene glycol (PEG) based slurries, but those do not solve the problem for aqueous or semi-aqueous based slurries.

SUMMARY OF THE INVENTION

In one aspect, described herein are processes and methods that improve upon wafer thickness variation with water based slurries during wire saw cutting. Wafer thickness control is very difficult with water based slurries: many wafers are either way too thin or way too thick. In its most extreme form this problem is called “Thick-Thin” . The novelty is that we discovered the root cause of the thickness problem: unstable and uneven wire spacing in the wire web, even prior to the ingot touching the web.

This is caused by a wrongly chosen combination of wire speed and slurry flow rate for a water based slurry with a certain rheological behaviour and wetting behaviour (static and dynamic wetting to both wire guiding rollers and sawing wire)

The discovery can be applied to any wafering process with sawing wire and water based slurries. It is not limited to silicon wafering. It has been surprising discovered that a correlation between wire speed, slurry flow rate and slurry properties can prevent the occurrence of thin-thick issues in wafer processing, among others.

In one aspect, described herein are methods for cutting a substrate with a wire saw, comprising the steps of:

(a) contacting a cutting wire with a cutting slurry composition that comprises:

(a. i) an abrasive component；

(a. ii) a suspending component；

(a. iii) at least one defoamer or wetting agent；

(a. iv) water； and

(a. v) optionally, at least one water miscible solvent；

(b) adjusting a slurry flow rate to greater than or equal to 3000 kg/hr. m； and

(c) adjusting a wire speed of the cutting wire to greater than or equal to 1 m/sand within a wire speed range having a wire speed lower limit and a wire speed upper limit；

wherein the wire speed range is determined by formula (I) :

(-a1) (x) + b1 ≤ y ≤ (a2) (x) + b2

(I) ；

wherein:

“ (-a1) (x) + b1” is the wire speed lower limit,

“ (a2) (x) + b2” is the wire speed upper limit,

“x” is the slurry flow rate,

“y” is the wire speed, and

a1, a2, b1 and b2 each individually are positive coefficients；

wherein the viscosity of the slurry is maintained at lower than 1000 cPs for a period of time.

In another aspect, described herein are method for cutting a substrate with a wire saw, comprising the steps of:

(a) contacting a cutting wire with a cutting slurry composition that comprises, by weight of slurry composition:

(a. i) from about 0.1 to 50 wt％of an abrasive component；

(a. ii) from about 0.1 to 10 wt％of a suspending component；

(a. iii) at least one defoamer；

(a. iv) at least one wetting agent；

(a. v) water； and

(a. vi) optionally, at least one water miscible solvent.

(b) adjusting a slurry flow rate to greater than or equal to 4000 kg/hr. m； and

(c) adjusting a wire speed of the cutting wire to greater than or equal to 3 m/sand within a wire speed range having a wire speed lower limit and a wire speed upper limit；

wherein the wire speed range is determined by formula (I) :

(-a1) (x) + b1 ≤ y ≤ (a2) (x) + b2

(I) ；

wherein:

“ (-a1) (x) + b1” is the wire speed lower limit,

“ (a2) (x) + b2” is the wire speed upper limit,

“x” is the slurry flow rate,

“y” is the wire speed, and

a1, a2, b1 and b2 each individually are positive coefficients；

wherein the viscosity of the slurry is maintained at lower than 600 cPs for a period of time.

In some embodiments, the wire speed of the cutting wire is adjusted to to greater than or equal to 4 m/s. In some embodiments, the viscosity of the slurry is maintained at lower than 800 cPs for a period of time.

DETAILED DESCRIPTION

In one embodiment, the described herein is a wire cutting process that incorporates a slurry composition comprising an abrasive component and an suspending component dispersed in an aqueous or semi-aqueous medium. The slurry composition also includes one or more defoamers and/or one or more wetting agents.

One of the traditional problems related to aqueous slurries or semi-aqueous slurries is their stability. The slurries having stability is understood to mean that the particles of which they are composed have to remain in suspension in the liquid phase without separation by settling occurring over a sufficient period of time for optimum use. In addition, dispersions are desired which are stable over a significant pH range which makes it possible to effectively use them in applications and under conditions which are as varied as possible. Another problem associated with related to aqueous slurries or semi-aqueous slurries is the unacceptable variance of wafer diameters, called “Thin-Thick” .

The suspending component can comprises one or more suspending particles selected from inorganic oxides, in one embodiment, inorganic hydroxides in another embodiment, an inorganic oxyhydroxide in another embodiment or any combination thereof in yet another embodiment. Suitable suspending particles include oxides, hydroxides and/or oxyhydroxides of single elements including but not limited to cerium, titanium, zirconium, silicon, aluminum, manganese, tin, iron, silica, and mixtures thereof, as well as of mixtures of such elements. Typically, the particles are comprised of an oxide, a hydroxide or an oxyhydroxide of aluminum, zinc or manganese. In yet amother emboidment, the suspending particles are selected from aluminum hydroxide, aluminum oxy hydroxide, manganese hydroxide, magnesium hydroxide or zinc hydroxide.

The abrasive component, in one embodiment, comprises one or more abrasive particles selected from silicon carbide, diamond, iron oxide, zirconium oxide, tin oxide, tungsten carbide, boron carbide, boron nitride, and titanium carbide, silicon, silica, cerium oxide, aluminum oxide, silicon nitride. In one embodiment, the abrasive component is silicon carbide (SiC) .

Substrate: The substrate that is subjected to the cutting process as described herein can be any material, which in one embodiment is silicon, sapphire, silicon carbide, aluminum nitride, tellurium, silica, gallium arsenide, indium phosphide, cadmium sulfide, germanium, zinc sulfide, gray tin, selenium, boron, silver iodide, and indium antimonide, among other materials. Typically, the substrate is silicon or sapphire. In one particular embodiment, the substrate is silicon.

The abrasive component: In one embodiment, the abrasive component and/or suspending component particles are initially present in the form of a slurry of such particles dispersed in an aqueous medium or semi-aqueous medium. Typically, the aqueous medium comprises at least 40 wt％, more typically at least 50 wt％water and even more typically at least 60 wt％water. In one embodiment, the aqueous medium comprises at least 95 wt％water. In one embodiment, the aqueous medium consists essentially of water. In other embodiments, the aqueous medium comprises at least 20 wt％water, or at least 30 wt％water.

The aqueous medium may optionally further comprise one or more water miscible organic liquids or solvents, such as for example, tetrahydrofuran, alkyl lactone, alkylene carbonates, N, N-dimethylformamide, acetonitrile, N-methylpyrrolidone, acetone, dimethyl acetamide, (C1-C8) alkanols such as methanol, ethanol, 2-propanol and diols such as ethylene glycol, dialkylene glycol, propylene glycol, alkylene glycol, polyalkylene glycol, ethylene glycol monoacetate, glycol ethers, polyols or ketones.

As used herein the terminology "primary particle" means a single discrete particles and the terminology "secondary particle" means an agglomerate of two or more primary particles. A reference to "particles" that does not specify "primary" or "secondary" means primary particles, or secondary particle, or primary particles and secondary particles.

In one embodiment, the abrasive particle and/or suspending particles have a mean particle diameter ( "D₅₀" ) of from about 0.1 to about 100 micrometer ( "μm" ) . In one embodiment, the particles have a D₅₀ of from about 0.5 to about 80 μm, even more typically from about 0.8 to about 50 μm, and still more typically from about 1 to about 10 μm.In one embodiment, the particles have a D₅₀ of from about 1 to about 40 μm, even more typically from about 2 to about 30 μm, and still more typically from about 5 to about 20 μm. In one embodiment, the particles have a D₅₀ of from about 7 to about 14 μm.In one embodiment, the particles have a D₅₀ of from about 8 to about 12 μm. Particle size may be determined using dynamic light scattering. The sizes given here are measured by the technique of quazielastic light scattering (QELS) or by the laser diffraction technique.

These particles are in stable suspension in a liquid phase. This is understood to mean that, with regard to these dispersions, a cake formed by separation by settling is not observed to form before several minutes to hours depending on process requirements. Furthermore, the cake formed by separating by settling, if it is formed, can be re-suspended by simple agitation.

In another embodiment, the suspending particles are based on an inorganic oxide which can be chosen from CeO₂, TiO₂, ZrO₂, Al₂O₃ or Fe₂O₃. The particles can also be based on a hydroxide and/or on an oxyhydroxide of the same above metal elements. The term “oxide” , in the singular or in the plural, should be understood as applying not only to the oxide form but also to the “hydroxide” and “oxyhydroxide” forms. The particles can also be based on a mixture of the oxides mentioned above. The invention applies not only to the case described above, where the particles are composed of a mixture of oxides, but also to the case where the dispersion comprises particles of a first type of oxide as a mixture with particles of another type of oxide. In one embodiment, the abrasive particles are different than the suspending particles.

In another embodiment of the present invention, a cutting slurry composition including at least one abrasive particle, at least one suspending particle, a carrier fluid, and a thickening agent is employed. The carrier fluid can be aqueous or non-aqueous； preferably, the carrier fluid is aqueous. Suitable aqueous carrier fluids include water and alkylene glycols. Preferred alkylene glycols used in the context of the present invention include ethylene glycol (EG) , polyethylene glycol (PEG) , and polypropylene glycol (PPG) . More preferred carrier fluids are water, EG, DEG and PPG； yet more preferred is water.

In one embodiment, the slurry composition contains up to 80％by total weight of the abrasive inorganic. In another embodiment, the slurry composition contains up to 70％by total weight of the abrasive inorganic. In one embodiment, the slurry composition contains up to 50％by total weight of the abrasive inorganic. In one embodiment, the slurry composition contains up to 30％by total weight of the abrasive inorganic. In one embodiment, the slurry composition contains up to 20％by total weight of the abrasive inorganic. In one embodiment, the slurry composition contains up to 15％by total weight of the abrasive inorganic. In one embodiment, the slurry composition contains up to 10％by total weight of the abrasive inorganic.

In one embodiment, the slurry composition contains up to 20％by total weight of suspending particles. In one embodiment, the slurry composition contains up to 15％by total weight of suspending particles. In one embodiment, the slurry composition contains up to 10％by total weight of suspending particles. In one embodiment, the slurry composition contains up to 8％by total weight of suspending particles. In one embodiment, the slurry composition contains up to 5％by total weight of suspending particles. In one embodiment, the slurry composition contains up to 3％by total weight of suspending particles

Because the invention relates to aqueous and semi-aqueous media, extended contact of the formulations of this invention with metals such as carbon steel, iron, steel, etc., that are typical components of wire saws, metal finishing lappers, etc., can result in corrosion/rusting of such metals. In one embodiment, a corrosion inhibitor may be added to the slurry formulations to suppress or eliminate metal corrosion. Appropriate inhibitors should not cause foaming, interfere with the formulations ability to provide long-term stable abrasive or solids suspensions, compromise the viscosity, rheology, pH, or uniformity of the carrier formulations and their associated abrasive or solids suspensions.

In one aspect, the defoamer can be a mineral oil based defoamer or a polysiloxane defoamer or a combination of both. In one embodiment, the defoamer is a pollysiloxane defaomer.

In one aspect, the wetting agent can be an alkoxylated adduct of a tertiary acetylenic diol, for example, an ethylene oxide adduct of a tertiary acetylenic diol or an ethylene oxide/propylene oxide adduct of a tertiary acetylenic diol. Ethylene oxide adducts of tertiary acetylenic diols are described in U.S. Pat. No. 5,650,543. In another embodiment, the wetting agent is an alkylethoxylate phosphate.

The wires can be made of any suitable material and suitable shape, In one embodiment, the wires comprise straight wires, structure wires, diamond wires or wires made with metal (e.g., brass) or plastics. The slurry as described herein can also contain a dispersion stabilizer, which in one embodiment is an inorganic gel or organic dispersant, including silica gel, alumina gel, PEG polymers, PAA polymer, polyamine polymers.

It has been observed that problems with aqueous or semi-aqueous slurries include “thick-thin” issues. In particular, use of a semi-aqueous or aqueous slurry during wire sawing caused unstable wire pairing, which for example makes the wires move laterally over the ingot surface. Where they pair the largest pressure is created and most slurry is dragged with them (due to smallest gap between them) , resulting in higher. At this position a thin wafer is generated and the adjacent position will result in a thick wafer, hence the the systematic 'thick-thin' . Thick-Thin (TT) wafers are a product of uneven space between wires. This phenomenon appears before the ingot touches the wire web and remains present after the wire cuts into the ingot.

It is also believed that the drag attributable to the aqueous or semi-aqueous slurry results in pressure build up at the cut in position that it can lift the wires out of their kerf slot and into the adjacent kerf slot. That explains why there are wafers with a thickness in excess of double the target thickness. This phenomenon is sometimes called wire lift.

Additional problems attributable to aqueous or semi-aqueous slurries include the following: (ii) Wire jumps: Alumina particles were found on mesh and guiding rollers. Some of them were rigid but most of them were crushable by fingers. An excessive amount of such particles can lead to wire jumps on the wire guiding rollers. This generates thick-thin and also increases the wire fracture rate.

Accordingly, described herein are methods for cutting a substrate with a wire saw, comprising the steps of:

(a) contacting a cutting wire with a cutting slurry composition that comprises:

(a. i) an abrasive component；

(a. ii) a suspending component；

(a. iii) at least one defoamer or wetting agent

(a. iv) water； and

(a. v) optionally, at least one water miscible solvent.

(b) adjusting the wire speed of the cutting wire to greater than or equal to 1 m/s； and

(c) adjusting the flow rate of the cutting slurry to greater than or equal to 3000kg/hr. m；

In certain embodiment, the wire speed of the cutting wire is proportional or relative to the cutting slurry flow rate (otherwise called “slurry flow rate” ) within a wire speed range having a wire speed lower limit and a wire speed upper limit determined by formula (I) :

(-a1) (x) + b1 ≤ y ≤ (a2) (x) + b2

(I) ；

wherein:

“ (-a1) (x) + b1” is the wire speed lower limit,

“ (a2) (x) + b2” is the wire speed upper limit,

“x” is the slurry flow rate,

“y” is the wire speed, and

a1, a2, b1 and b2 each individually are positive coefficients；

In other embodiments, relating the viscosity to wire speed and/or slurry flow rate allows for improved process parameters. In other embodiments, reducing the contact angle on iron and reducing the dynamic surface tension of the slurry make it possible to widen the process window under formula (I) . This allows for the industrial process settings required to wafer ingots with acceptable speed and wafer quality.

In one embodiment, the wire speed of the cutting wire is greater or equal to 3 meters/second (m/s) . In another embodiment, the wire speed of the cutting wire is greater or equal to 4 m/s. In another embodiment, the wire speed of the cutting wire is greater or equal to 5 m/s. In another embodiment, the wire speed of the cutting wire is greater or equal to 6 m/s. In yet another embodiment, the wire speed of the cutting wire is greater or equal to 7 m/s. In an alternative embodiment, the wire speed of the cutting wire is greater or equal to 8 m/s. In a further another embodiment, the wire speed of the cutting wire is greater or equal to 9 m/s. In yet another embodiment, the wire speed of the cutting wire is greater or equal to 10 m/s.

In one embodiment, the flow rate of the cutting slurry is greater than or equal to 4000 kg per hour (kg/hr. m) . In another embodiment, the flow rate of the cutting slurry is greater than or equal to 6000 kg/hr. m. In another embodiment, the flow rate of the cutting slurry is greater than or equal to 8000 kg/hr. m. In yet another embodiment, the flow rate of the cutting slurry is greater than or equal to 10, 000 kg/hr. m. In a further embodiment, the flow rate of the cutting slurry is greater than or equal to 12,000 kg/hr. m.

In one embodiment, viscosity of the slurry is maintained at lower than 600 cPs for a period of time. In another embodiment, the viscosity of the slurry is maintained at lower than 500 cPs for a period of time. In yet another embodiment, the viscosity of the slurry is maintained at lower than 400 cPs for a period of time. In a further embodiment, the viscosity of the slurry is maintained at lower than 300 cPs for a period of time. In another embodiment, the viscosity of the slurry is maintained at lower than 200 cPs for a period of time. In one embodiment, the viscosity of the slurry is maintained at lower than 100 cPs for a period of time. . In one embodiment, the viscosity of the slurry is maintained at lower than 50 cPs for a period of time. In one embodiment, the viscosity of the slurry is maintained at lower than 30 cPs for a period of time. . . In one embodiment, the viscosity of the slurry is maintained at 20 cPs or lower for a period of time.

It has also been discovered that following formula (I) should be followed, in certain embodiments, to avoid the problem of thick-thin:

(-a1) (x) + b1 ≤ y ≤ (a2) (x) + b2

(I)

Where:

X ＝ slurry flow rate

Y ＝ wire speed

a1, a2, b1 and b2 are positive coefficients.

Experiments have also shown that lowering the viscosity, reducing the contact angle and reducing the dynamic surface tension of the slurry make it possible to widen the process window described by the later equation to allow for the industrial process settings required to wafer ingots with acceptable speed and wafer quality.

In another aspect, described herein are methods for cutting a substrate with a wire saw, comprising the steps of:

(a. i) from about 0.1 to 50 wt％of an abrasive component；

(a. ii) from about 0.1 to 10 wt％of a suspending component；

(a. iii) at least one defoamer；

(a. iv) at least one wetting agent；

(a. v) water； and

(a. vi) optionally, at least one water miscible solvent.

(b) adjusting the wire speed of the cutting wire to greater than or equal to 4 m/s； and

(c) adjusting the flow rate of the cutting slurry to greater than or equal to 4000kg/hr. m；

Experiments

Description of test set up. A full factorial experimental design was used with different water based slurry formulations to cover the following range in selected properties

Table 1

For each of the formulations, a full factorial experimental design was used to cover the following range in selected process settings

Table II

Process setting	Minimum	Maximum
Wire speed	1m/sec	10m/sec
Slurry flow rate	2000 kg/hr. m	14000 kg/hr. m

Note: the slurry flow rate is expressed per meter of slurry delivery manifold width. Other process settings were kept within the typical industrial range

Table III

	min	Max
Wire tension in	12N	16N
Wire tension out	22N	27N
Slurry temperature	20 Degrees C	32 degrees C

The study was done for 120 micron straight sawing wire and 115 microns structured wire. For each of the formulation –process setting combinations a study by photography and video was conducted to observe the wire spacing. Once the appropriate operational windows were defined, the set up was validated by cutting multi-silicon ingots of 156x156mm into 190 micron thick wafers and checking the wafers with standard PV metrology. It was surprising discovered that there is process window to avoid the problem of Thick-Thin for a slurry of a certain viscosity, with a certain contact angle on Fe and dynamic surface tension

Description of test results and interpretation.

There are a few industrial boundary conditions to be taken into account:

For slurries of a viscosity higher than 100 cps a very slow wire speed of 1 m/sec was found to avoid Thick –Thin, but this speed is not useable for industrial processes as it is considered too slow to provide an acceptable cut-in table speed. Cut-in speeds of 2 to 3 m/swill require a lower table speed and will hence prolong the total cutting time.

A slurry flow of minimum 3000 kg/hr. m is required to have a continuous slurry curtain along the width of the slurry delivery system. Below this level, interruptions may appear that lead to insufficient slurry delivery to some points along the ingot. This can lead to saw marks and bad TTV.

Below is an example of the process window for a formulation with a viscosity of 50 cPs, a static contact angle on Fe of 40 degrees and a dynamic surface tension of 70 –75 dynes.

The process window , respecting the minimum acceptable industrial wire speed of 3m/sand minimum flow rate of 3000kg/hr. m) , is define by:

-x/800 + 17.5 ≤ y ≤ x/1000 + 4

With x ＝ slurry flow rate in kg/hr. m and y ＝ wire speed in m/s.

Once the flow reaches 10000 kg/hr. m any wire speed above 3m/swill avoid thick-thin.

An improvement can be seen when the slurry viscosity is lowered. Below is the operational window for a slurry with a viscosity of 20 cPs, a static contact angle on Fe of 40 degrees and a dynamic surface tension of 70 –75 dynes. As can be seen from the table, there is now only a minimum limit to respect for the wire speed –slurry flow rate combination:

-3x/2000 + 16 ≤ y

With x ＝ slurry flow rate in kg/hr. m and y ＝ wire speed in m/s.

Once the flow reaches 8000 kg/hr. m any wire speed above 3m/swill avoid thick-thin.

A further improvement can be seen when lowering the dynamic surface tension and contact angle on Fe. The operational window expands to allow for all flow rate–wire speed combinations, leaving just the industrial boundary conditions described earlier to be respected. This formulation had a contact angle on Fe < 10 degrees and a dynamic surface tension < 30 dynes.

The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While the invention has been depicted and described and is defined by reference to particular preferred embodiments of the invention, such references do not imply a limitation on the invention, and no such limitation is to be inferred. The invention is capable of considerable modification, alteration and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts. The depicted and described preferred embodiments of the invention are exemplary only and are not exhaustive of the scope of the invention. Consequently, the invention is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects.

Claims

A method for cutting a substrate with a wire saw, comprising the steps of:

(a) contacting a cutting wire with a slurry composition that comprises:

(a. i) an abrasive component；

(a. ii) a suspending component；

(a. iii) at least one defoamer or wetting agent；

(a. iv) water； and

(a. v) optionally, at least one water miscible solvent；

(b) adjusting a slurry flow rate to greater than or equal to 3000 kg/hr. m； and

(c) adjusting a wire speed of the cutting wire to greater than or equal to 1 m/sand within a wire speed range having a wire speed lower limit and a wire speed upper limit；

wherein the wire speed range is determined by formula (I) :

(-a1) (x) + b1 ≤ y ≤ (a2) (x) + b2

(I) ；

wherein:

“ (-a1) (x) + b1” is the wire speed lower limit,

“ (a2) (x) + b2” is the wire speed upper limit,

“x” is the slurry flow rate,

“y” is the wire speed, and

a1, a2, b1 and b2 each individually are positive coefficients；

wherein the viscosity of the slurry is maintained at lower than 1000 cPs for a period of time.
The method of claim 1 wherein the wire speed of the cutting wire is greater or equal to 3 m/s
The method of claim 1 wherein the wire speed of the cutting wire is greater or equal to 4 m/s.
The method of claim 1 wherein the slurry flow rate is greater than or equal to 4000 kg/hr. m.
The method of claim 1 wherein the slurry flow rate is greater than or equal to 6000 kg/hr. m.
The method of claim 1 wherein the viscosity of the slurry is maintained at lower than 600 cPs for a period of time.
The method of claim 1 wherein the viscosity of the slurry is maintained at lower than 300 cPs for a period of time.
The method of claim 1 wherein the dispersion has a pH of between about 3 and about 12.
The method of claim 1 wherein the suspending component comprises at least one particle selected from oxides, hydroxides or oxyhydroxides of any of cerium, titanium, zirconium, silicon, aluminum, manganese, tin, iron or silica.
The method of claim 1 wherein the suspending component comprises at least one particle selected from aluminum hydroxide, aluminum oxy hydroxide, manganese hydroxide, magnesium hydroxide or zinc hydroxide.
The method of claim 1 wherein the abrasive component comprises at least one particle selected from silicon carbide, diamond, iron oxide, zirconium oxide, tin oxide, tungsten carbide, boron carbide, boron nitride, and titanium carbide, silicon, silica, cerium oxide, aluminum oxide or silicon nitride.
The method of claim 1 wherein the abrasive component comprises silicon carbide.
The method of claim 1 wherein the abrasive particles exhibit a mean particle size of between about 1 nm and about 200 nm.
The method of claim 1 wherein the abrasive particles exhibit a mean particle size of between about 20 nm and about 70 nm, and exhibit a standard deviation value of at most 30％ of the mean particle size.
The method of claim 1 wherein the solvent comprises at least one of the following: tetrahydrofuran, alkyl lactone, alkylene carbonates, N, N-dimethylformamide, acetonitrile, N-methylpyrrolidone, acetone, dimethyl acetamide, methanol, ethanol, 2-propanol, ethylene glycol, dialkylene glycol, propylene glycol, alkylene glycol, polyalkylene glycol, ethylene glycol monoacetate, glycol ethers or ketones.
The method of claim 1 wherein the solvent comprises at least one of the following: (poly) ethylene glycol, dialkylene glycol, propylene glycol, alkylene glycol, polyalkylene glycol, ethylene glycol monoacetate or glycol ethers.
The method of claim 1 wherein the defoamer is present and selected from a mineral oil based defoamer, a polysiloxane defoamer or a combination of both.
The method of claim 1 wherein the wetting agent is present and selected from an alkoxylated adduct of a tertiary acetylenic diol, an alkylethoxylate phosphate or a combination of both.
The method of claim 1 wherein defoamer present and is selected from mineral oil based defoamer, a polysiloxane defoamer or a combination of both； and wherein the wetting agent is present and selected from an alkoxylated adduct of a tertiary acetylenic diol, an alkylethoxylate phosphate or a combination of both.
A method for cutting a substrate with a wire saw, comprising the steps of:

(a) contacting a cutting wire with a slurry composition that comprises, by weight of slurry composition:

(a. i) from about 0.1 to 50 wt％ of an abrasive component；

(a. ii) from about 0.1 to 10 wt％ of a suspending component；

(a. iii) at least one defoamer；

(a. iv) at least one wetting agent；

(a. v) water； and

(a. vi) optionally, at least one water miscible solvent；

(b) adjusting a slurry flow rate to greater than or equal to 4000 kg/hr. m； and

(c) adjusting a wire speed of the cutting wire to greater than or equal to 4 m/s and

within a wire speed range having a wire speed lower limit and a wire speed upper limit；

wherein the wire speed range is determined by formula (I) :

(-a1) (x) + b1 ≤ y ≤ (a2) (x) + b2

(I) ；

wherein:

“ (-a1) (x) + b1” is the wire speed lower limit,

“ (a2) (x) + b2” is the wire speed upper limit,

“x” is the slurry flow rate,

“y” is the wire speed, and

a1, a2, b1 and b2 each individually are positive coefficients；

wherein the viscosity of the slurry is maintained at lower than 600 cPs for a period of time.