CA1074575A - Abrasive polishing suspensions and method for making same - Google Patents
Abrasive polishing suspensions and method for making sameInfo
- Publication number
- CA1074575A CA1074575A CA237,424A CA237424A CA1074575A CA 1074575 A CA1074575 A CA 1074575A CA 237424 A CA237424 A CA 237424A CA 1074575 A CA1074575 A CA 1074575A
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- Canada
- Prior art keywords
- dispersion
- weight
- carbopol
- abrasive
- base liquid
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K3/00—Materials not provided for elsewhere
- C09K3/14—Anti-slip materials; Abrasives
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Colloid Chemistry (AREA)
- Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
ABRASIVE POLISHING SUSPENSIONS
AND METHOD FOR MAKING SAME
Abstract of the Disclosure This invention relates to a permanent suspension of abrasive polishing powders. The suspension media consists essentially of a water or glycol base thickened by controlled additions of neutralized carboxy poly-methylene polymer and containing up to 50 weight per cent of abrasive powders.
S P E C I F I C A T I O N
1.
AND METHOD FOR MAKING SAME
Abstract of the Disclosure This invention relates to a permanent suspension of abrasive polishing powders. The suspension media consists essentially of a water or glycol base thickened by controlled additions of neutralized carboxy poly-methylene polymer and containing up to 50 weight per cent of abrasive powders.
S P E C I F I C A T I O N
1.
Description
1(~7 ~5-~
This invention relates to abrasive polishing suspensions and, more particularly, to permanent suspensions of powdered abrasive materials, in amounts up to 50% by weight, in a glycol or water base.
Abrasive polishing materials have been suspended in a glycol or partially aqueous glycol base as disclosed in U.S. Patent 3,817,727 - Yancey. The suspensions disclosed in U.S. Patent 3,817,727 - are highly effective.
However, for some purposes, e.g. a water base suspension is considered advantageous and previous efforts with water base suspensions have resulted in unstable suspensions at high abrasive contents for small particle sizes, resulting in the settling out and caking of the abrasive.
It now has been discovered that permanent water suspensions of abrasive polishing powder at weight levels of up to 50% can be achieved by a novel method of prepa-ration involving a critical sequence of additions in preparing the suspension. The novel method can also be used with glycol bases and partially aqueous glycol bases as disclosed in the above-noted U.S. patent to provide permanent stable suspensions containing up to 50% by weight of abrasive powder.
It is an object of the present invention to provide a method for producing permanent suspensions of abrasive powders in a water or glycol base.
This invention relates to abrasive polishing suspensions and, more particularly, to permanent suspensions of powdered abrasive materials, in amounts up to 50% by weight, in a glycol or water base.
Abrasive polishing materials have been suspended in a glycol or partially aqueous glycol base as disclosed in U.S. Patent 3,817,727 - Yancey. The suspensions disclosed in U.S. Patent 3,817,727 - are highly effective.
However, for some purposes, e.g. a water base suspension is considered advantageous and previous efforts with water base suspensions have resulted in unstable suspensions at high abrasive contents for small particle sizes, resulting in the settling out and caking of the abrasive.
It now has been discovered that permanent water suspensions of abrasive polishing powder at weight levels of up to 50% can be achieved by a novel method of prepa-ration involving a critical sequence of additions in preparing the suspension. The novel method can also be used with glycol bases and partially aqueous glycol bases as disclosed in the above-noted U.S. patent to provide permanent stable suspensions containing up to 50% by weight of abrasive powder.
It is an object of the present invention to provide a method for producing permanent suspensions of abrasive powders in a water or glycol base.
2.
~074575 A method in accordance with the present invention for producing a stable suspension of abrasive powder in a base liquid consisting essentially of at least one material selected from the group consisting of water and glycols comprises the following steps:
(i) providing a first dispersion of carboxy polymethylene polymer in a base liquid at a pH of about 9 to 9.5 and a concentration of at least about 0.02% by weight but below the value at which flocculation of abrasive powder will occur upon addition in accordance with step (ii) said first dispersion containing from 20 to 60%
by weight of the base liquid content of the desired suspension;
(ii) providing a dispersion of abrasive powder in base liquid at a pH of about 8 to 9 and adding an amount of said abrasive powder dispersion to said first dispersion of carboxy polymethylene polymer to provide dispersed therein at least about 0.5% by weight of abrasive powder;
(iii) providing a second dispersion of carboxy polymethylene polymer in base liquid at a pH of about 9 to 9.5 at a concentration of from about 10 to 50 times the concentration of the first dispersion and adding said second dispersion of carboxy polymethylene polymer and a base liquid dispersion of abrasive powder at a pH of about 8 to 9 to said first dispersion in amounts required to provide a base liquid suspension containing from about 10 to 50% by weigh~ abrasive powder dispersed therein and about 0.001 to about 0.2% by weight carboxy polymethylene polymer.
The present invention is based on the discovery that stable permanent water, and also glycol base suspen-sions of abrasive powders, containing up to 50%, e.g. 10 to 50%, and preferably 20 to 50% by weight of such powders, can be prepared by a method involving a critical sequence of steps.
In the practice of the present invention, a suspension is ultimately produced having the about following proportions:
Ingredient Parts by weight Carboxy polymethylene polymer 0.001 to 2 Abrasive Powder 100 to 500 Base Liquid 897 to 488 Neutralizing Agent 2.5 to 10 Total = 1000 In obtaining a permanent suspension having the composition described above, a carboxy polymethylene ~ 07~ S 7 ~ 9576 poLymer of high molecular weight, as disclosed in U.S.
patent 3,817,727 - Yancey such as the type sold by B.F. Goodrich Chemical Company under the trademark Carbopol 941* is blended into a base liquid to provide a first, or receptor dispersion of Carbopol 941* and the receptor dispersion is neutralized to a pH of about 9 to 9.5. The base liquid can be water, or a nonaqueous or partially aqueous glycol, as described in the above-noted U.S. patent 3,817,727-yancey. The amount of ~-arbopol 941*in the first dispersion constitutes only a portion of the Carbopol 941*content of the final desired suspension, and at least about .02% by weight of the dispersio~ but does not exceed the concentration at which added abrasives would flocculate. The upper limit of the Carbopo~ 941*concentration in the first, or receptor dispersion, whereby flocculation of abrasives is avoided, is dependent on the sizing of the abrasive powders to be suspended, with lower concentrat~ons being used with smaller particle sizing. For example, wi~h powder sizes of 5 microns to 75 microns, the concentration of Carbopol 941*can be up to about 0.4%; for particle sizes from 1 micron to 5 microns the upper limit is about 0.35%;
for particle sizes from 0.3 to 1 micron the upper limit is about 0.25%; and for particles from 0.05 microns to 0.3 microns to upper limit i~ about 0.15%. An upper *Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
5. ;
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limit for ~he concentration of Carbopol 941*1n the first or receptor dispersion has been found to be necessary in order to avoid flocculation of subsequently added abrasive powder, the tendency to flocculate increasing with decreasing particle sizing of the powder.
The first, or receptor dispersion of Carbopol 941*is neutralized to a pH of about 9 to 9.5 using neutralizing agants such as those disclosed in the above-noted U.S. patent. A dispersion of abrasive powder in base liqu~d is prepared at a pH of about 8.0 to 9 and an amount of this abrasive dispersion is added to the first, or receptor dispersion of Carbopol 941* the amount of abrasive powder being added in this step being such as to provide at least about 0.5% by weight of abrasive powder in the receptor dispersion. In employing relatively high concentrations of Carbopol 941*in the first, or receptor dispersion, it is recommended that a very slight test addition abrasive powder, e.g. 0.01%
by weight be made to the receptor dispersion. If no flocculation occurs, then the remaining abrasive can be added. If there is an i~dication of flocculation, then ~ the concentration of Carbopol 941* in the receptor dispersion is lowered until flocculation do~s not occur with test additions. The addition of suck an amount of abrasive powder, 0.5~/O has the ef~ect of conditioning the receptor dispersion whereby additional Carbopol 941*can be added *Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin G ~36 ~Revised) of the B.F.
Goodrich Chemical Company, is a commercially availab~e water-soluble carboxy vinyl polymer resin.
~(~74S75 to the receptor dispersion as described below, together with abra~ive powder in amounts up to 50% by weight of the final suspension.
A ~econd dispersion of Carbopol 94Ikin base liquid is prepared and neutralized to a pH of 9 to 9.5 and this dispersion, which has a Carbopo~ concentration of about 50 to 10 times that of the receptor disper~ion, and a dispersion of abrasive powder in base liquid, are added to the first dispersion to provide a permanent suspension. The amount of abrasive powder containing up to 50% by weigh~ of abrasive powder. The amount of Carbopol 94~ in the second dispersion is that which will provide a Carbopol 941*content of about 0.001 to 0.2% by weight in the final permanent suspension which resul~s from the addition o~ the second Carbopol 94~ dispersion and abrasive dispersion to the first, or receptor dispersion. The abrasive dispersion can provide up to 50% by weight of abrasive in the suspension, e.g. ~rom 10 to 50% and preferably 20 to 50%. In a preferred practice of the preqent invention, the first, or receptor dispersion of Carbopol 941*contains about 20 to 60% by weight of the base liquid and the second dispersion of Carbopol 941*contai~s about 2 to 10% of the base liquid. The required balance of the base liquid is added with the abrasive disperslon. The aforedescribed method, through the use of separate neutralized Carbopo~ dispersions, of different and controlled concentration, and an *Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin IGC-36 (Revised) of the B.F
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer7resin.
1(~74575i 9576 l intermediate abrasive powder dispersion, enables the fo~nation of stable permanent water or glycol base suspensions containing up to 50% by weight abrasive.
This is accomplished by adding abrasive powder dispersion, e.g. A1203, to the neutralized, relatively dilute Carbopol*
receptor dispersion, which has been found to have the effect of conditioning the dilute receptor dispersion, possibly on account of surface reactions between the abrasive and Carbopo~, whereby a concentrated, neutralized second dispersion of Carbopol*can be added to bring the Carbopol*concentration to a level which maintains a stable suspension at abrasive contents up to 50% by weight. The intermediate conditioning addition of abrasive dispersion can constitute the entire addition of abrasive; however, it has been found to be convenient to employ an intermediate addition to about 10 to 60% by weight of the desired abrasive content which is followed by an addition of 30 to 60% of the second Carbopol*
dispersion. Thereafter the remaining abrasive dispersion is added and followed by the remaining portion of the second Carbopol*dispersion.
*Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
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The following examples are provided to illustrate the various forms the invention may take anld the methods for achieving the permanent suspensions of the invention:
Example I
.~ suspension of A1203 powder (sized 0.05 micron) was prepared containing 57.0 Iiters of water, 75 grams (0.1% by weight) of carboxy polymethylene polymer (Carbopol 941**), and 12,000grams of A12O3 (17.3% by weight) by the following procedure: 25 grams of Carbopol 94~* resin was blended into 1000 ml of water to form a dlspersion. 17.0 liters of water were added to the dispersion to provide a concentration of Carbopol 941**of.16% by weight. The diluted dispersion was neutralized to a pH of 9 to 9.5 with 150 ml of 50%
DIPA* to form a receptor gel mLx. The A12O3 powder, 12,000 grams, was separately dispersed in 37.0 liters of water to give 40 liters of dispersion. 10 l~ters of the A12O3 dispersion were mixed with the receptor gel mix. 50 grams of Carbopol 941* * was separately blended with 2000 ml of water and this second Carbopol**
dispersion was neutralized to a pH of 9 to 9.5 by adding 250 ml of 50% DIPA* 1125 ml of this dispersion were blended wqth the receptor gel mix after which the *Diisopropanolamine.
**Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
B 9.
~074575 remaining A1203 dispersion 30 liters was blended with the receptor gel mix followed by addition and blending of the remaining second Carbopol*dispersion. The resulting material was a penmanent stable suspension containing 17.3% by weight A12O3 powder 82.1% by weight Water 0.1% by weight Carbopol 941*
0.5% by w~ight DIPA**(diisopropanolamine).
Example 2 A suspension of A1203 powder (sized 0.3 ~icron) was prepared containing 57 liters of water, 75 grams (.1% by weight) of carboxy polymethylene polymer (Carbopol 941~, and 1200 grams of A1203 (17.3% by weight) by the folLowing procedure: 38 grams of Carbopol 941*resin was blended into 1500 ml of water to form a dispersion. 17.0 liters of water were added to the dispersion to provide a concentration of Carbopol 941*of 0.2% by weight. The diluted dispersion was neutralized to a pH of 9 to 9.5 with 190 ml of 50%
DIP~to form a receptor gel mix. The A12O3 powder, 12,000 grams, was separately dispersed in 37 liters of water to give 40 liters of dispersion. 10 liters of the A1203 dispexsion were mixed with the receptor gel mix. 37 grams of Carbopol 941*was separate~y ~lended with 1500 ml -*Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin GC-36 ~Revised) of the B.F.
Goodrich Chemical Company, is a commerclally available water-soluble carboxy vinyl polymer resin.
**Diisopropanolamine.
' ~ , 10.
.
~(~74S~5 of water and this second Carbopol dispersion was neutralized to a pH of 9 to 9.5 by adding 185 ml of 50% DIPA** 1000 ml of this dispersion were blended with the receptor gel mix after which the re~aining A12Q3 dispersion 30 liters was blended with the receptor gel mix followed by addition and blending of the remaining second Carbopol*dispersion. The resulting matérial was a permanent stable suspension containing 17.3% by weight A1203 powder 82.1% by weight Water 0.1% by weight Carbopol 941*
0.5% by weight DIPA**
Example 3 A suspension of A1203 powder (sized 1.0 micron) was prepared containing 57 liters of water, 75 grams (0.1~ by weight) of carboxy polymethylene polymer (Carbopol 941~., and 1200 grams of A1203 (17.3% by weight) by the following procedure: 60 grams of Carbopol 941*resin was blended into 2200 ml of water t~o form a dispersion.
17 liters of water were added to the dispersion to provide a concentration of Carbopol 941*was separately blended with 800 ml of water and this second Carbopol*dispersion was neutralized to a pH of ~ to 9.5 by adding 75 ml of 50%
DIPA~* 875 ml o this dispersion were blended with the *Trademark of B.F. Goodrich Chemical Company - ~arbopol 941, as described in Service Bulletin GC-36 (Revlsed) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
**Diisopropanolamine.
B 11.
~074575 receptor gel mix after which the rem~ining A1203 dispersion 30 liters was blended with the receptor gel mix. The res~lting material was a permanent stable suspension containing 17.3% by weight A1203 powder 82.1% by weight Water 0.1% by weight Carbopol 941*
0.5% by weight DIPA**
Example 4 A suspension of A1203 powder (sized 5 microns) was prepared containing 51.2 liters of water, 180 grams (0.2% by weight) of carboxy polymethylene polymer (Carbopol 941~, and 38,160 grams of A1203 (42.2% by weight) by the following procedure: 60 grams of Carbopol 941*resin was blended into 2400 ml of water to form a dispersion. 17.0 liters of water were added to the dispersion to provide a concentration of Carbopol 941*of 0.3% by weight. The diluted dispersion was neutralized to a pH of 9 to 9.5 with 180 ml of 50% DIPA**
to fonm a receptor gel m~x. The A1203 powder, 38,160 grams, was separately dispersed in 27.0 liters of water, to give 36.54 liters of dispersion. 12.18 liters of the ; A1203 dispersion were mixed with the receptor gel mix.
120 grams of Carbopol 941*was separately blended with *Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
**Diisopropanolamine. 12.
~074575 48~0 ml of water and this second Carbopo~ dispersion was neutralized to a pH of 9 to 9.5 by adding 600 ml of 50% DIPA~ 2700 ml of this dispersion were blended with the receptor gel mix after whi.ch the remaining A1203 disp~rsion 24.36 liters wa~ blended with the receptor gel mix followed by addition and blending of the remaining second Carbopol*dispersion. The resulting material was a permanent stable suspension containing 42.2% by weight Alz03 powder 56.6~ by weight Water 0.2% by weight Carbopol 941*
1.0% by weight DIPA.**
Example 5 A suspension of A1203 powder (sized 0.3 micron) was prepared containing 40 liters of water,and 17.0 liters of ethylene glycol~ 75 grams (0.1% by weight) of carboxy polymethylene polymer (Carbopol 941~ and 12000 gram3 of Alz03 tl7.3~ by weight~ by the following procedure: 38 grams of Carbopol 94E~re~in was blended into 1500 ml of water to form a tispersion. 17.0 liters of ethylene glycol were added to the dlspersion to provide a concentration of Carbopol 94~ of 0.2% by weight. The diluted dispersion was neutralized to a pH of 9 to 9.5 with 190 ml of 5Q% DIPA** to form a receptor gel mix. The A1203 *Trademark of B.F. Goodrich Chemical Co. - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the s.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
**Diisopropanolamine.
13.
F~
9s76 iO74S75 powder, 1200 grams, was separately dispersed in 37.0 liters of water to give 40 liters of dispersion. 10 liters of the A12O3 dispersion were mixed with the recep~or gel mix. 37 grams of Carbopol 941*was separately blended with 1500 ml of water and this second Carbopol*disp¢rsion was neutralized to a pH of 9 to 9.5 by adding 185 ml of 50% DIPA** 1000 ml of this dispersion were blended with the receptor gel mix after which the remaining A1203 dispersion. 30 liters was blended with the receptor gel mix followed by addition and blending of the remaining second Carbopo~ dispersion. The resulting material was a permanent stable suspension containing 17.3% by weight A1203 powder 57.6% by weight Water 24.5% by weight Ethylene Glycol .1% by weight Carbopol 941*
; .5% by weight DIPA?~*
*Trademark of B.F. Goodrich Chemical Co. - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
`- Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
**Diisopropanolamine.
14.
~ .
1(~'74$~f 5 Any~polishing agent can be suspended by the method of this invention. Typical powders are aluminum oxide powders having an unagglomerated average of particle size in the range of from about .05 to 1.0 microns, sold by Union Carbide Corporation under the trademark Linde*
Type A, B or C. Other powders could be, for example, silicon carbide, beach sand and other powders ad disclosed in U.S. Patent 3,817,727.
In the practice of the present invenCion-j dispersions are prepared by blending a carboxy polymethylene polymer of high molecular weight, such as the type sold by B.F. Goodrich Chemical Co. under the tradem~rk Carbopol 941'~* into ethylene glycol. The Carbopol 941** is supplied as dry, fluffy powders in acid form requiring neutralization to develop optimum properties. Therefore, after Carbopol 941** is blended into base liquid and aqueous solution of a neutralizing agent is added to the Carbopol*~/ ;
base liquid mixture to neutralize the ~arbopol** and form a dispersion. The neutralizing agents for Carbopol** re~in for use in accordance with the present inver.tion are as disclosed in U.S. patent 3,~17,727 and are bases, either organic such as diisopropanolamine or inorganic such as NaOH. Other bases which will neutralize Carbopo]** resins in a water or ethylene glycol/water system are ammonium hydroxide, triethanolamine, monoethanolamine, eriethylamine, *Trademark of Union Carbide Corporation.
**Trademark of B.F. Goodrich Chemical Co. - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
15.
:~3745~i~5 a~ld Ethomeen C-25**. ~iisopropanolamine has been found to be the most efficient neutralizing agent in the present systems and is the preferred agent. An advantage of the suspensions made using this preferred organic base is that there are no inorganic ions, such as Na, present to any exten~. Ions such as sodium are very deleter~ous to polished semiconductor substrates. ~brasive powder to be suspended is dispersed in a base liquid for addition to Carbopol*
dispersions in accordance with the present invention.
Glycols for use in the practice of the present i~vention as disclosed in U.S. patent 3,817,727 and include ethylene glycols and propylene glycols.
The Carbopol 941*is preferred in the practice of the present invention over the other Carbopol*resins due to its ability to form relatively low vixcosities in ionic systems. The other Carbopol*resins are used to provide much thicker emulsions and suspensions.
Applications for these suspensions produced in accordance with the present invention as widespread as the powders from which they are formed. They can be used in essentially all polishing operations which now use the alumina powders, with the new advantage of being easier to handle than the powder counterpart.
Since~ they are chemically neutral, they will not corrode laps as will some of the other formulations on the market.
*Trademark of B.F. Goodrich Chemical Co.
**Trademark of Armour and Co. A cationic surface-active agent produced by reacting aliphatic amines with ethylene oxide.
16.
,. ~ , .
~074575 A method in accordance with the present invention for producing a stable suspension of abrasive powder in a base liquid consisting essentially of at least one material selected from the group consisting of water and glycols comprises the following steps:
(i) providing a first dispersion of carboxy polymethylene polymer in a base liquid at a pH of about 9 to 9.5 and a concentration of at least about 0.02% by weight but below the value at which flocculation of abrasive powder will occur upon addition in accordance with step (ii) said first dispersion containing from 20 to 60%
by weight of the base liquid content of the desired suspension;
(ii) providing a dispersion of abrasive powder in base liquid at a pH of about 8 to 9 and adding an amount of said abrasive powder dispersion to said first dispersion of carboxy polymethylene polymer to provide dispersed therein at least about 0.5% by weight of abrasive powder;
(iii) providing a second dispersion of carboxy polymethylene polymer in base liquid at a pH of about 9 to 9.5 at a concentration of from about 10 to 50 times the concentration of the first dispersion and adding said second dispersion of carboxy polymethylene polymer and a base liquid dispersion of abrasive powder at a pH of about 8 to 9 to said first dispersion in amounts required to provide a base liquid suspension containing from about 10 to 50% by weigh~ abrasive powder dispersed therein and about 0.001 to about 0.2% by weight carboxy polymethylene polymer.
The present invention is based on the discovery that stable permanent water, and also glycol base suspen-sions of abrasive powders, containing up to 50%, e.g. 10 to 50%, and preferably 20 to 50% by weight of such powders, can be prepared by a method involving a critical sequence of steps.
In the practice of the present invention, a suspension is ultimately produced having the about following proportions:
Ingredient Parts by weight Carboxy polymethylene polymer 0.001 to 2 Abrasive Powder 100 to 500 Base Liquid 897 to 488 Neutralizing Agent 2.5 to 10 Total = 1000 In obtaining a permanent suspension having the composition described above, a carboxy polymethylene ~ 07~ S 7 ~ 9576 poLymer of high molecular weight, as disclosed in U.S.
patent 3,817,727 - Yancey such as the type sold by B.F. Goodrich Chemical Company under the trademark Carbopol 941* is blended into a base liquid to provide a first, or receptor dispersion of Carbopol 941* and the receptor dispersion is neutralized to a pH of about 9 to 9.5. The base liquid can be water, or a nonaqueous or partially aqueous glycol, as described in the above-noted U.S. patent 3,817,727-yancey. The amount of ~-arbopol 941*in the first dispersion constitutes only a portion of the Carbopol 941*content of the final desired suspension, and at least about .02% by weight of the dispersio~ but does not exceed the concentration at which added abrasives would flocculate. The upper limit of the Carbopo~ 941*concentration in the first, or receptor dispersion, whereby flocculation of abrasives is avoided, is dependent on the sizing of the abrasive powders to be suspended, with lower concentrat~ons being used with smaller particle sizing. For example, wi~h powder sizes of 5 microns to 75 microns, the concentration of Carbopol 941*can be up to about 0.4%; for particle sizes from 1 micron to 5 microns the upper limit is about 0.35%;
for particle sizes from 0.3 to 1 micron the upper limit is about 0.25%; and for particles from 0.05 microns to 0.3 microns to upper limit i~ about 0.15%. An upper *Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
5. ;
:~V7457~
limit for ~he concentration of Carbopol 941*1n the first or receptor dispersion has been found to be necessary in order to avoid flocculation of subsequently added abrasive powder, the tendency to flocculate increasing with decreasing particle sizing of the powder.
The first, or receptor dispersion of Carbopol 941*is neutralized to a pH of about 9 to 9.5 using neutralizing agants such as those disclosed in the above-noted U.S. patent. A dispersion of abrasive powder in base liqu~d is prepared at a pH of about 8.0 to 9 and an amount of this abrasive dispersion is added to the first, or receptor dispersion of Carbopol 941* the amount of abrasive powder being added in this step being such as to provide at least about 0.5% by weight of abrasive powder in the receptor dispersion. In employing relatively high concentrations of Carbopol 941*in the first, or receptor dispersion, it is recommended that a very slight test addition abrasive powder, e.g. 0.01%
by weight be made to the receptor dispersion. If no flocculation occurs, then the remaining abrasive can be added. If there is an i~dication of flocculation, then ~ the concentration of Carbopol 941* in the receptor dispersion is lowered until flocculation do~s not occur with test additions. The addition of suck an amount of abrasive powder, 0.5~/O has the ef~ect of conditioning the receptor dispersion whereby additional Carbopol 941*can be added *Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin G ~36 ~Revised) of the B.F.
Goodrich Chemical Company, is a commercially availab~e water-soluble carboxy vinyl polymer resin.
~(~74S75 to the receptor dispersion as described below, together with abra~ive powder in amounts up to 50% by weight of the final suspension.
A ~econd dispersion of Carbopol 94Ikin base liquid is prepared and neutralized to a pH of 9 to 9.5 and this dispersion, which has a Carbopo~ concentration of about 50 to 10 times that of the receptor disper~ion, and a dispersion of abrasive powder in base liquid, are added to the first dispersion to provide a permanent suspension. The amount of abrasive powder containing up to 50% by weigh~ of abrasive powder. The amount of Carbopol 94~ in the second dispersion is that which will provide a Carbopol 941*content of about 0.001 to 0.2% by weight in the final permanent suspension which resul~s from the addition o~ the second Carbopol 94~ dispersion and abrasive dispersion to the first, or receptor dispersion. The abrasive dispersion can provide up to 50% by weight of abrasive in the suspension, e.g. ~rom 10 to 50% and preferably 20 to 50%. In a preferred practice of the preqent invention, the first, or receptor dispersion of Carbopol 941*contains about 20 to 60% by weight of the base liquid and the second dispersion of Carbopol 941*contai~s about 2 to 10% of the base liquid. The required balance of the base liquid is added with the abrasive disperslon. The aforedescribed method, through the use of separate neutralized Carbopo~ dispersions, of different and controlled concentration, and an *Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin IGC-36 (Revised) of the B.F
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer7resin.
1(~74575i 9576 l intermediate abrasive powder dispersion, enables the fo~nation of stable permanent water or glycol base suspensions containing up to 50% by weight abrasive.
This is accomplished by adding abrasive powder dispersion, e.g. A1203, to the neutralized, relatively dilute Carbopol*
receptor dispersion, which has been found to have the effect of conditioning the dilute receptor dispersion, possibly on account of surface reactions between the abrasive and Carbopo~, whereby a concentrated, neutralized second dispersion of Carbopol*can be added to bring the Carbopol*concentration to a level which maintains a stable suspension at abrasive contents up to 50% by weight. The intermediate conditioning addition of abrasive dispersion can constitute the entire addition of abrasive; however, it has been found to be convenient to employ an intermediate addition to about 10 to 60% by weight of the desired abrasive content which is followed by an addition of 30 to 60% of the second Carbopol*
dispersion. Thereafter the remaining abrasive dispersion is added and followed by the remaining portion of the second Carbopol*dispersion.
*Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
8.
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The following examples are provided to illustrate the various forms the invention may take anld the methods for achieving the permanent suspensions of the invention:
Example I
.~ suspension of A1203 powder (sized 0.05 micron) was prepared containing 57.0 Iiters of water, 75 grams (0.1% by weight) of carboxy polymethylene polymer (Carbopol 941**), and 12,000grams of A12O3 (17.3% by weight) by the following procedure: 25 grams of Carbopol 94~* resin was blended into 1000 ml of water to form a dlspersion. 17.0 liters of water were added to the dispersion to provide a concentration of Carbopol 941**of.16% by weight. The diluted dispersion was neutralized to a pH of 9 to 9.5 with 150 ml of 50%
DIPA* to form a receptor gel mLx. The A12O3 powder, 12,000 grams, was separately dispersed in 37.0 liters of water to give 40 liters of dispersion. 10 l~ters of the A12O3 dispersion were mixed with the receptor gel mix. 50 grams of Carbopol 941* * was separately blended with 2000 ml of water and this second Carbopol**
dispersion was neutralized to a pH of 9 to 9.5 by adding 250 ml of 50% DIPA* 1125 ml of this dispersion were blended wqth the receptor gel mix after which the *Diisopropanolamine.
**Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
B 9.
~074575 remaining A1203 dispersion 30 liters was blended with the receptor gel mix followed by addition and blending of the remaining second Carbopol*dispersion. The resulting material was a penmanent stable suspension containing 17.3% by weight A12O3 powder 82.1% by weight Water 0.1% by weight Carbopol 941*
0.5% by w~ight DIPA**(diisopropanolamine).
Example 2 A suspension of A1203 powder (sized 0.3 ~icron) was prepared containing 57 liters of water, 75 grams (.1% by weight) of carboxy polymethylene polymer (Carbopol 941~, and 1200 grams of A1203 (17.3% by weight) by the folLowing procedure: 38 grams of Carbopol 941*resin was blended into 1500 ml of water to form a dispersion. 17.0 liters of water were added to the dispersion to provide a concentration of Carbopol 941*of 0.2% by weight. The diluted dispersion was neutralized to a pH of 9 to 9.5 with 190 ml of 50%
DIP~to form a receptor gel mix. The A12O3 powder, 12,000 grams, was separately dispersed in 37 liters of water to give 40 liters of dispersion. 10 liters of the A1203 dispexsion were mixed with the receptor gel mix. 37 grams of Carbopol 941*was separate~y ~lended with 1500 ml -*Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin GC-36 ~Revised) of the B.F.
Goodrich Chemical Company, is a commerclally available water-soluble carboxy vinyl polymer resin.
**Diisopropanolamine.
' ~ , 10.
.
~(~74S~5 of water and this second Carbopol dispersion was neutralized to a pH of 9 to 9.5 by adding 185 ml of 50% DIPA** 1000 ml of this dispersion were blended with the receptor gel mix after which the re~aining A12Q3 dispersion 30 liters was blended with the receptor gel mix followed by addition and blending of the remaining second Carbopol*dispersion. The resulting matérial was a permanent stable suspension containing 17.3% by weight A1203 powder 82.1% by weight Water 0.1% by weight Carbopol 941*
0.5% by weight DIPA**
Example 3 A suspension of A1203 powder (sized 1.0 micron) was prepared containing 57 liters of water, 75 grams (0.1~ by weight) of carboxy polymethylene polymer (Carbopol 941~., and 1200 grams of A1203 (17.3% by weight) by the following procedure: 60 grams of Carbopol 941*resin was blended into 2200 ml of water t~o form a dispersion.
17 liters of water were added to the dispersion to provide a concentration of Carbopol 941*was separately blended with 800 ml of water and this second Carbopol*dispersion was neutralized to a pH of ~ to 9.5 by adding 75 ml of 50%
DIPA~* 875 ml o this dispersion were blended with the *Trademark of B.F. Goodrich Chemical Company - ~arbopol 941, as described in Service Bulletin GC-36 (Revlsed) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
**Diisopropanolamine.
B 11.
~074575 receptor gel mix after which the rem~ining A1203 dispersion 30 liters was blended with the receptor gel mix. The res~lting material was a permanent stable suspension containing 17.3% by weight A1203 powder 82.1% by weight Water 0.1% by weight Carbopol 941*
0.5% by weight DIPA**
Example 4 A suspension of A1203 powder (sized 5 microns) was prepared containing 51.2 liters of water, 180 grams (0.2% by weight) of carboxy polymethylene polymer (Carbopol 941~, and 38,160 grams of A1203 (42.2% by weight) by the following procedure: 60 grams of Carbopol 941*resin was blended into 2400 ml of water to form a dispersion. 17.0 liters of water were added to the dispersion to provide a concentration of Carbopol 941*of 0.3% by weight. The diluted dispersion was neutralized to a pH of 9 to 9.5 with 180 ml of 50% DIPA**
to fonm a receptor gel m~x. The A1203 powder, 38,160 grams, was separately dispersed in 27.0 liters of water, to give 36.54 liters of dispersion. 12.18 liters of the ; A1203 dispersion were mixed with the receptor gel mix.
120 grams of Carbopol 941*was separately blended with *Trademark of B.F. Goodrich Chemical Company - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
**Diisopropanolamine. 12.
~074575 48~0 ml of water and this second Carbopo~ dispersion was neutralized to a pH of 9 to 9.5 by adding 600 ml of 50% DIPA~ 2700 ml of this dispersion were blended with the receptor gel mix after whi.ch the remaining A1203 disp~rsion 24.36 liters wa~ blended with the receptor gel mix followed by addition and blending of the remaining second Carbopol*dispersion. The resulting material was a permanent stable suspension containing 42.2% by weight Alz03 powder 56.6~ by weight Water 0.2% by weight Carbopol 941*
1.0% by weight DIPA.**
Example 5 A suspension of A1203 powder (sized 0.3 micron) was prepared containing 40 liters of water,and 17.0 liters of ethylene glycol~ 75 grams (0.1% by weight) of carboxy polymethylene polymer (Carbopol 941~ and 12000 gram3 of Alz03 tl7.3~ by weight~ by the following procedure: 38 grams of Carbopol 94E~re~in was blended into 1500 ml of water to form a tispersion. 17.0 liters of ethylene glycol were added to the dlspersion to provide a concentration of Carbopol 94~ of 0.2% by weight. The diluted dispersion was neutralized to a pH of 9 to 9.5 with 190 ml of 5Q% DIPA** to form a receptor gel mix. The A1203 *Trademark of B.F. Goodrich Chemical Co. - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the s.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
**Diisopropanolamine.
13.
F~
9s76 iO74S75 powder, 1200 grams, was separately dispersed in 37.0 liters of water to give 40 liters of dispersion. 10 liters of the A12O3 dispersion were mixed with the recep~or gel mix. 37 grams of Carbopol 941*was separately blended with 1500 ml of water and this second Carbopol*disp¢rsion was neutralized to a pH of 9 to 9.5 by adding 185 ml of 50% DIPA** 1000 ml of this dispersion were blended with the receptor gel mix after which the remaining A1203 dispersion. 30 liters was blended with the receptor gel mix followed by addition and blending of the remaining second Carbopo~ dispersion. The resulting material was a permanent stable suspension containing 17.3% by weight A1203 powder 57.6% by weight Water 24.5% by weight Ethylene Glycol .1% by weight Carbopol 941*
; .5% by weight DIPA?~*
*Trademark of B.F. Goodrich Chemical Co. - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
`- Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
**Diisopropanolamine.
14.
~ .
1(~'74$~f 5 Any~polishing agent can be suspended by the method of this invention. Typical powders are aluminum oxide powders having an unagglomerated average of particle size in the range of from about .05 to 1.0 microns, sold by Union Carbide Corporation under the trademark Linde*
Type A, B or C. Other powders could be, for example, silicon carbide, beach sand and other powders ad disclosed in U.S. Patent 3,817,727.
In the practice of the present invenCion-j dispersions are prepared by blending a carboxy polymethylene polymer of high molecular weight, such as the type sold by B.F. Goodrich Chemical Co. under the tradem~rk Carbopol 941'~* into ethylene glycol. The Carbopol 941** is supplied as dry, fluffy powders in acid form requiring neutralization to develop optimum properties. Therefore, after Carbopol 941** is blended into base liquid and aqueous solution of a neutralizing agent is added to the Carbopol*~/ ;
base liquid mixture to neutralize the ~arbopol** and form a dispersion. The neutralizing agents for Carbopol** re~in for use in accordance with the present inver.tion are as disclosed in U.S. patent 3,~17,727 and are bases, either organic such as diisopropanolamine or inorganic such as NaOH. Other bases which will neutralize Carbopo]** resins in a water or ethylene glycol/water system are ammonium hydroxide, triethanolamine, monoethanolamine, eriethylamine, *Trademark of Union Carbide Corporation.
**Trademark of B.F. Goodrich Chemical Co. - Carbopol 941, as described in Service Bulletin GC-36 (Revised) of the B.F.
Goodrich Chemical Company, is a commercially available water-soluble carboxy vinyl polymer resin.
15.
:~3745~i~5 a~ld Ethomeen C-25**. ~iisopropanolamine has been found to be the most efficient neutralizing agent in the present systems and is the preferred agent. An advantage of the suspensions made using this preferred organic base is that there are no inorganic ions, such as Na, present to any exten~. Ions such as sodium are very deleter~ous to polished semiconductor substrates. ~brasive powder to be suspended is dispersed in a base liquid for addition to Carbopol*
dispersions in accordance with the present invention.
Glycols for use in the practice of the present i~vention as disclosed in U.S. patent 3,817,727 and include ethylene glycols and propylene glycols.
The Carbopol 941*is preferred in the practice of the present invention over the other Carbopol*resins due to its ability to form relatively low vixcosities in ionic systems. The other Carbopol*resins are used to provide much thicker emulsions and suspensions.
Applications for these suspensions produced in accordance with the present invention as widespread as the powders from which they are formed. They can be used in essentially all polishing operations which now use the alumina powders, with the new advantage of being easier to handle than the powder counterpart.
Since~ they are chemically neutral, they will not corrode laps as will some of the other formulations on the market.
*Trademark of B.F. Goodrich Chemical Co.
**Trademark of Armour and Co. A cationic surface-active agent produced by reacting aliphatic amines with ethylene oxide.
16.
,. ~ , .
Claims (7)
1. A method for producing a stable permanent suspension of abrasive powder in a base liquid consisting essentially of at least one material selected from the group consisting of water and glycols, said method comprising (i) providing a first dispersion of carboxy polymethylene polymer in a base liquid at a pH of about 9 to 9.5 and a concentration of at least about 0.02% by weight but below the value at which flocculation of abrasive powder will occur upon addition in accordance with step (ii) said first dispersion containing from 20 to 60%
by weight of the base liquid content of the desired suspension;
(ii) providing a dispersion of abrasive powder in base liquid at a pH of about 8 to 9 and adding an amount of said abrasive powder dispersion to said first dispersion of carboxy polymethylene polymer to provide therein at least about 0.5% by weight of abrasive powder;
(iii) providing a second dispersion of carboxy polymethylene polymer in base liquid at a pH of about 9 to 9.5 at a concentration of from about 10 to 50 times the concentration of the first dispersion and adding said second dispersion of carboxy polymethylene polymer and a base liquid dispersion of abrasive powder at a pH of about 8 to 9 to said first dispersion in the amounts required to provide a stable, permanent base liquid suspension free of flocculation and containing from about 10 to 50% by weight abrasive powder and about 0.001 to about 0.2% by weight carboxy polymethylene polymer.
by weight of the base liquid content of the desired suspension;
(ii) providing a dispersion of abrasive powder in base liquid at a pH of about 8 to 9 and adding an amount of said abrasive powder dispersion to said first dispersion of carboxy polymethylene polymer to provide therein at least about 0.5% by weight of abrasive powder;
(iii) providing a second dispersion of carboxy polymethylene polymer in base liquid at a pH of about 9 to 9.5 at a concentration of from about 10 to 50 times the concentration of the first dispersion and adding said second dispersion of carboxy polymethylene polymer and a base liquid dispersion of abrasive powder at a pH of about 8 to 9 to said first dispersion in the amounts required to provide a stable, permanent base liquid suspension free of flocculation and containing from about 10 to 50% by weight abrasive powder and about 0.001 to about 0.2% by weight carboxy polymethylene polymer.
2. A method in accordance with claim 1 wherein the concentration of carboxy polymethylene polymer in the first dispersion of step (i) has a maximum value of about 0.4% for when the abrasive powders added in step (ii) has an average particle size of from 5 to 75 microns; about 0.35% when the abrasive powder added in step (ii) has an average particle size of from 1 to 5 microns; about 0.25%
when the abrasive powder added in step (ii) has an average particle size of from 0.3 to 1 micron;
about 0.15% when the abrasive powder added in step (ii) has an average particle size of less than 0.3 micron.
when the abrasive powder added in step (ii) has an average particle size of from 0.3 to 1 micron;
about 0.15% when the abrasive powder added in step (ii) has an average particle size of less than 0.3 micron.
3. A method in accordance with claim 1 and 2 wherein the abrasive powder is Al2O3.
.
.
4. A method in accordance with claim 1 wherein the concentration of carboxy polymethylene polymer in the dispersion of step (iii) is about 10 to 50 times the concentration of the dispersion of step (i).
5. A method in accordance with claim 1 wherein said base liquid is more than 50% by weight water.
6. A method in accordance with claim 1 wherein the base liquid is water.
7. A method in accordance with claim 2 wherein the stable, permanent, flocculation-free base liquid suspension provided contains from about 17.3 to 42% by weight abrasive powder.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US52222474A | 1974-11-08 | 1974-11-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1074575A true CA1074575A (en) | 1980-04-01 |
Family
ID=24079997
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA237,424A Expired CA1074575A (en) | 1974-11-08 | 1975-10-10 | Abrasive polishing suspensions and method for making same |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5170589A (en) |
| CA (1) | CA1074575A (en) |
| CH (1) | CH608827A5 (en) |
| FR (1) | FR2290462A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4242842A (en) * | 1979-08-08 | 1981-01-06 | La Pierre Synthetique Baikowski, S.A. | Precision polishing suspension and method for making same |
| JPS5820128U (en) * | 1981-07-30 | 1983-02-07 | 三菱電機株式会社 | Air conditioner drain tray |
| JPS5924958A (en) * | 1982-07-27 | 1984-02-08 | Sumitomo Special Metals Co Ltd | Accurate polishing method of insulating thin film |
-
1975
- 1975-10-10 CA CA237,424A patent/CA1074575A/en not_active Expired
- 1975-11-07 FR FR7534146A patent/FR2290462A1/en active Granted
- 1975-11-07 JP JP50133138A patent/JPS5170589A/en active Granted
- 1975-11-07 CH CH7514436A patent/CH608827A5/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5170589A (en) | 1976-06-18 |
| FR2290462B1 (en) | 1981-01-09 |
| CH608827A5 (en) | 1979-01-31 |
| DE2548966B2 (en) | 1977-04-21 |
| FR2290462A1 (en) | 1976-06-04 |
| JPS5337154B2 (en) | 1978-10-06 |
| DE2548966A1 (en) | 1976-05-13 |
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