U.S. patent application number 09/775865 was filed with the patent office on 2002-02-28 for biocides for polishing slurries.
Invention is credited to Goldberg, Wendy B., Luo, Qiuliang, Ye, Qianqiu (Christine).
Application Number | 20020025762 09/775865 |
Document ID | / |
Family ID | 22670800 |
Filed Date | 2002-02-28 |
United States Patent
Application |
20020025762 |
Kind Code |
A1 |
Luo, Qiuliang ; et
al. |
February 28, 2002 |
Biocides for polishing slurries
Abstract
Compounds containing both a sulfur and a nitrogen in a
five-membered ring structure are used as biocides in polishing
solutions and slurries.
Inventors: |
Luo, Qiuliang; (Newport
Beach, CA) ; Goldberg, Wendy B.; (Wilmington, DE)
; Ye, Qianqiu (Christine); (Washington, DC) |
Correspondence
Address: |
Rodel Holdings, Inc.
Suite 1300
1105 North Market Street
Wilmington
DE
19899
US
|
Family ID: |
22670800 |
Appl. No.: |
09/775865 |
Filed: |
February 2, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60182960 |
Feb 16, 2000 |
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Current U.S.
Class: |
451/41 |
Current CPC
Class: |
C09G 1/02 20130101; C09K
3/1463 20130101 |
Class at
Publication: |
451/41 |
International
Class: |
B24B 001/00 |
Claims
What is claimed is:
1. An aqueous solution, for use in CMP of semiconductor wafers
wherein a fixed abrasive polishing pad is used, which contains
essentially no abrasive particles and which is protected from
bacterial and fungal activity by means of a biocide comprising an
organic compound with a five membered ring containing both a sulfur
and a nitrogen group in said ring.
2. An aqueous slurry, for use in CMP of semiconductor wafers, which
contains abrasive particles and which is protected from bacterial
and fungal activity by means of a biocide comprising an organic
compound with a five membered ring containing both a sulfur and a
nitrogen group in said ring.
3. The solution of claim 1 wherein said biocide is from the group
comprising 2-methyl-4-isothiazolin-3-one and
5-chloro-2-methyl-4-isothiaz- olin-3-one.
4. The slurry of claim 2 wherein said biocide is from the group
comprising 2-methyl-4-isothiazolin-3-one and
5-chloro-2-methyl-4-isothiazolin-3-one.
5. The solution of claim 1 wherein said biocide is present in the
range of 0.01% to 1% by weight of said solution.
6. The slurry of claim 2 wherein said biocide is present in the
range of 0.01% to 1% by weight of said slurry.
7. A method of polishing a semiconductor wafer comprising: applying
a solution at a polishing interface between a fixed abrasive
polishing pad and said wafer, said solution comprising essentially
no abrasive particles and which is protected from bacterial and
fungal activity by means of a biocide comprising an organic
compound with a five membered ring containing both a sulfur and a
nitrogen group in said ring.
8. A method of polishing a semiconductor wafer comprising: applying
a slurry at a polishing interface between a polishing pad and said
wafer, said solution comprising abrasive particles and which is
protected from bacterial and fungal activity by means of a biocide
comprising an organic compound with a five membered ring containing
both a sulfur and a nitrogen group in said ring.
9. A method according to claim 5 wherein said biocide is from the
group comprising 2-methyl-4-isothiazolin-3-one and
5-chloro-2-methyl-4-isothiaz- olin-3-one.
10. A method according to claim 6 wherein said biocide is from the
group comprising 2-methyl-4-isothiazolin-3-one and
5-chloro-2-methyl-4-isothiaz- olin-3-one.
11. A method according to claim 5 wherein said biocide is present
in the range of 0.01% to 1% by weight of said solution.
12. A method according to claim 6 wherein said biocide is present
in the range of 0.01% to 1% by weight of said slurry.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/182,960 filed Feb. 16, 2000.
FIELD OF THE INVENTION
[0002] This invention relates to the protection of polishing
slurries and silica dispersions from the proliferation of bacteria
and/or fungi by means of biocides.
DESCRIPTION OF RELATED ART
[0003] The problem of bacterial and fungal growth in silica
polishing slurries is addressed in U.S. Pat. No. 5,230,833
(Romberger et al.). It includes a thorough summary of the early
related art. Bactericides disclosed in '833 are tetramethylammonium
chloride, tetraethylammonium chloride, tetrapropylammonium
chloride, alkylbenzyldimethylammonium chloride, and
alkylbenzyldimethylammonium hydroxide, wherein the alkyl chaim
ranges from 1 to about 20 carbon atoms. Also, the preferred biocide
is sodium chlorite or sodium hypochlorite. The preferred fungicide
is sodium OMADINE.RTM. (pyrithone).
[0004] U.S. Pat. No. 3,377,275 discloses a synergistic blend of
3,5-di-methyl tetrahydro 1,3,5,2H-thiadiazine-2-thione in
combination with formaldehyde as a microbiocide for aqueous
colloidal silica sols.
[0005] It has been found in recent years that the above chemicals
are not always compatible with abrasive slurries used for
chemical-mechanical polishing (CMP) of semiconductor wafers and
with abrasive free slurries used with fixed abrasive polishing pads
for semiconductor wafer polishing. It is the object of this
invention to provide biocides which are not detrimental to the
polishing of semiconductor wafers. Embodiments of the invention
will now be described by way of example, with reference to the
following detailed description.
SUMMARY OF THE INVENTION
[0006] It has been found that a five membered organic ring compound
containing both a sulfur and a nitrogen in the ring provide biocide
protection of CMP slurries without affecting polishing performance.
Examples of such compounds are
5-chloro-2-methyl-4-isothiazolin-3-one and
2-methyl-4-isothiazolin-3-one.
DETAILED DESCRIPTION
[0007] A class of biocides has been found which do not
significantly affect the polishing performance of both
particle-free solutions for use with fixed abrasive pads and
slurries comprising metal oxide abrasives such as alumina, ceria,
zirconia, and silica. These biocides comprise a five-membered
organic ring compound containing both a sulfur and a nitrogen in
the ring.
EXAMPLE 1
[0008] A chemical polishing solution for use with a fixed abrasive
pad was made up with the following components: ammonium hydrogen
phosphate, iminodiacetic acid, 5-methyl-1H-benzotriazole,
surfactant, and hydrogen peroxide. Removal rates were determined
using a Strasbaugh 6DS-SP Planarizer and a 3M fixed abrasive matrix
MRW64 pad. The process was fixed at 4 psi downforce, 60 rpm platen
speed, and 40 rpm carrier speed. Biocide 1 (Kathon CGICP II
available from Rohn and Haas Company, Philadelphia, Pa.) and
Biocide 2 (Neolone M50 available from Rohm and Haas Company,
Philadelphia, Pa.) were added at a concentration of 0.15% by weight
to solution batches. The active ingredients in these biocides are
2-methyl-4-isothiazolin-3-one and
5-chloro-2-methyl-4-isothiazolin-3-- one. Results of polishing
patterned wafers are shown in Table 1.
1TABLE 1 Polishing Results 10 um 25 um 100 um 90% BP 0.5 0.5 Sample
lines lines lines 4.5/.5 120 um Bpe 2.5/2.5 1.5/1.5 Control #1 461
652 1126 908 515 23 159 167 Biocide #1 503 751 922 692 472 40 212
221 Biocide #2 510 658 1085 855 570 93 301 242 Control #2 652 830
1052 1003 649 47 348 279
[0009] These results show little or no effect from adding the
biocide to the particle-free solutions. Similar solutions were
prepared and evaluated using a challenge test with the intentional
additions of bacteria and fungi.
2TABLE 2 Challenge Test Results Sample Days Testing Results*
Control 14 4F Biocide #1 14 0 Biocide #2 14 0 *4 = >100,000
cfu/ml, 0 = <10 cfu/ml, F = fungi
EXAMPLE 2
[0010] A polishing slurry comprising as major components iodic
acid, lactic acid, potassium hydrogen phthalate, and metal oxide
abrasive (a mixture of alumina and titania) was made up as slurry
A. To a portion of this slurry was added 0.10% by weight of
Kathon.RTM. CGICP biocide (active ingredients
2-methyl-4-isothiazolin-3-one and
5-chloro-2-methyl-4-isothiazolin-3-one). This slurry was designated
slurry B.
[0011] Wafers comprising tungsten (W), titanium (Ti), and silicon
dioxide (Ox) were polished on a standard CMP polishing machine
using slurry A and slurry B. Results of the polishing are shown in
Table 3.
3 TABLE 3 Avg. W RR Avg. Ti RR Avg. Ox RR Slurry Angstroms/min
Angstroms/min Angstroms/min A 3392 545 65 B 3533 564 64 B 3565 889
105 A 3291 891 62
EXAMPLE 3
[0012] A CMP slurry was made up with the following major
components: Klebosol 1498-50 (silica sol), citric acid (complexing
agent), benzotriazol (corrosion inhibitor), and a surfactant.
Addition of a small amount (about 0.1%) of Neolone.RTM. (available
from Rohm and Haas Company) gave adequate biocide protection to the
CMP slurry while the slurry provided slightly improved surface
quality when the slurry was used as a second step slurry for
polishing semiconductor wafers comprising copper.
[0013] It is obvious from the above results that the addition of a
biocide comprised of 2-methyl-4-isothiazolin-3-one and/or
5-chloro-2-methyl-4-iso- thiazolin-3-one in an amount sufficient to
provide antibacterial and antifungal protection to the slurry does
not adversely affect the polishing performance of a slurry. It
performs particularly well on slurries which comprise Klebosol.RTM.
silica sol as an ingredient. A sufficient amount of biocide is in
the range of 0.01% to 1% by weight of the CMP solution or
slurry.
* * * * *