JPH03197575A - Abrasive colloidal silica slurry - Google Patents

Abstract

PURPOSE: To provide a colloidal silica polishing slurry which is useful for polishing of a silicon wafer or a substrate by comprising colloidal silica, a polishing rate accelerator, a bactericidal agent, and an organism-killing agent.

CONSTITUTION: A colloidal silica (A) having a final particle diameter size of 4 to 200 nm, selected from precipitated silica, pyrolytic silica, and silica gel, in an amt. of 1 to 60%, 1 to 5% polishing rate accelerator (B) selected from among a primary amine, a secondary amine, a tertiary amine, and a heterocyclic amine, 0.10 to 1.25% bactericidal agent (C) selected from among tetramethylammonium chloride, tetramethylammonium hydroxide, tetraethylammonium chloride, tetrapropylamonium hydroxide and the like, and 0 to 500 ppm organism-killing agent (D), pref. sodium cholorite, and an optional fungicide (E), pref. sodium Omazine are dispersed in a solvent.

COPYRIGHT: (C)1991,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application The present invention provides a novel colloidal silica slurry that is particularly useful for polishing silicon wafers or substrates. Silicon wafers are the basic building blocks of integrated circuits, semiconductor devices, and transistors. [Prior Art] Roughly cut silicon wafers are processed into (5) ) (6) Normal polishing is required. Silica polishing is a traditional method of delicate surface polishing on silicon wafers.

This method includes placing the wafer on a polishing head;
Subsequently, the method includes positioning the polishing head over the rotating polishing plate. The polishing plate is covered with a polishing pad (ie, a composite pad containing a polymeric material) and held therein with an adhesive. During polishing, dilute colloidal silica is continuously injected between the polishing plate and the silicon wafer to finely polish the wafer.

Although colloidal silica is commonly used in polishing systems, the cost of the silica and the chemicals with which it is mixed has led to increased interest in developing commercially acceptable recirculating systems. Ta. The recirculating system provides rapid polishing rates without using high temperatures and thus distorting the wafer, and substantially reduces chemical costs during the polishing process. Unfortunately, when used for extended periods of time, colloidal silica containing organic promoters increases the growth of microorganisms and fungi. Bacterial contamination causes discoloration and odor, rendering colloidal silica unacceptable as a polishing aid in wafer manufacturing.

The growth of microorganisms and fungi in colloidal silica is well known. Various attempts have been made to reduce or eliminate bacterial growth in colloidal silica. Some examples are U.S. Pat. No. 3,336,236 (Michalski), issued August 15, 1967, 1
No. 3.816,330 issued on June 11, 974 (
Havens), No. 3, published January 14, 1975.
No. 860,431 (Payne), February 11, 1958.
Issue No. 2.823.186 (Nickerso)
n), No. 2,801,2, issued July 30, 1957.
No. 16 (Yoder et al.), July 2, 1962
No. 3,046,234 (Roman e
tal, ), No. 3.37, published April 9, 1968.
7.275 (formerly Chalski et al) and 1
No. 3.148.110 (M
cGahen).

Michalski, US Pat. No. 3,336,236, discloses a method for protecting colloidal silica aqueous sols from bacterial contamination. This patent states that colloidal silica aqueous sols can be protected from bacterial contamination by simply adding sodium chlorite in an amount sufficient to inhibit bacterial growth and reproduction (7) (8).

Havens' patent states that hexachlorophene is approximately 10 to 1
It is suggested that colloidal silica aqueous sol containing 1000 pp can protect against microbial contamination. The addition of hexachlorophene is intended to prevent decolorization, malodor and sludge formation and to increase the shelf life of the colloidal silica sol to more than one year.

The Payne patent and the N1ckerson patent are directed to controlling bacterial growth in silica aqueous sols containing polyhydric alcohols. Payne has shown that by adding biocides, Erobacter and Pseudomonas bacteria, aspergillus
lus niger mold) and the troublesome desulfovibrio and clostridia anaerobic bacteria.

Typical biocides are glutaraldehyde, ethylene diamine, hydrogen peroxide and methyl p-hydroxybenzoate. N1ckerson teaches that addition of sodium pentachlorophenate prevents or inhibits silica aqueous sols containing polyhydric alcohols from turning black, even in instances where the silica aqueous sol contains sodium sulfate. are doing.

The Yoder and Roman et al patent discloses the use of dialdehydes, such as glutaraldehyde, to inhibit bacteria. Michalsk
U.S. Pat. No. 3,377.275 and M.
cGahen discloses the use of formaldehyde to protect colloidal silica sols from bacterial growth. McGahen also uses 3.5 as a fungicide.
-dimethyltetrahydro I, 3, 5, 1-H-
Discloses the use of thiadiazine-2-thiones.

Although each of the aforementioned patents discloses various biocides for inhibiting bacterial growth in colloidal silica (9) (10), none of the aforementioned aqueous sols can be used for polishing silicon wafers. I am not satisfied because of this. That is, the aqueous sol has an unacceptable polishing rate for use in a circulating polishing system.

[Problem to be Solved by the Invention] The inventors have discovered that although there is initially no microbial growth in conventional colloidal silica, increased microbial growth is observed during recirculation and dilution of the slurry. I found it.

Since the reasons for microbial growth in recirculating polishing systems were not clear, the inventors investigated recirculating polishing systems and determined that they not only eliminate bacterial and fungal growth, but also improve the polishing speed of this system. We sought to develop a new type of colloidal silica slurry that maintains and in some cases increases .

Through extensive experiments, the inventors have developed a new type of colloidal silica slurry that inhibits bacterial growth while increasing the polishing rate on silicon wafers.

Other advantages of the invention will become apparent from the following.

The first objective of the present invention is to provide a new colloidal slurry that can inhibit bacterial growth and increase silicon wafer polishing rates.

Another object of the present invention is a method of polishing a silicon wafer comprising recycling a colloidal silica slurry between a polishing plate containing a polishing pad and the silicon wafer, the method comprising colloidal silica, a polishing rate accelerator, and the like. The purpose of the present invention is to improve the method of polishing wafers by using a colloidal silica slurry consisting of a bactericide, a bactericide, and a biocide.

[Means to solve the problem]

The novel colloidal silica slurry of the present invention contains colloidal silica, a polishing rate accelerator, a bactericidal
and, optionally, a fungicide can be added to the slurry to inhibit fungal growth.

(11) (12) The invention also includes a number of additional features described further below.

[Description of preferred embodiments]

In polishing silicon wafers or substrates for use in electronic devices, it is preferable to recirculate the colloidal silica slurry to avoid bacterial and fungal growth while increasing the polishing rate of the system.

Silicon wafers or substrates are the basic building blocks of integrated circuits, semiconductor devices and transistors.

The colloidal silica slurry of the present invention consists of colloidal silica, a polishing rate accelerator, a bactericide, and a biocide.

If fungi are present, it is desirable to add a fungicide to the slurry.

Colloidal silica is about 1-60%, preferably about 50%
Preferably, it is present in an amount of . The polishing speed accelerator is approximately 1
Present in an amount of ~5%. Bactericide is about 0.10-1.2
It is present in an amount of 5%, preferably 0.25-0.75%, more preferably 0.5-0.75%. The biocide is present in an amount of about 0-500 ppm, preferably 65-1100 ppm. The fungicide is about 0 to 2.0%, preferably 0
It is added to the colloidal silica slurry in an amount of ~0.8%, more preferably 0.8%.

The colloidal silica slurry is typically a mixture of colloidal silica and water, preferably deionized water. Colloidal silica may have any average particle size or may be a mixture of silica particles of various sizes. The inventor has determined that the final or ultimate (ul) range is approximately 4-200 nanometers (nm), preferably 50-1100n.
Although some particle sizes have been found to be satisfactory, the preferred particle size will depend on the particular application.

One type of colloidal silica that can be used for this application is 40
% solids, particle size between 35 and 55 nm, pH 8.5 with sodium as stabilizing cation.

Others have 50% solids, particle size between 50 and 70 nm, and sodium as the stabilizing cation,
The pH is 8.4. Still others have a solids content of 30% (13) (14), a particle size between 10 and 16 nm, sodium as stabilizing cation, and a pH of 10.2. Also, 50% solids content, particle size between 16 and 25 nm,
It is also possible to use colloidal silica with sodium as stabilizing cation and pH 9.0.

In preparing the silica polishing slurry of the present invention, colloidal silica is mixed with precipitated silica, pyrogenic silica (fumed 5
It is also possible to replace it with either Nica) or silica gel.

The polishing rate accelerator may be any amine/nitrogen compound. However, the polishing rate accelerator is preferably at least one compound selected from the group consisting of primary amines, secondary amines, tertiary amines, and heterocyclic amines. Quaternary amines can be used, but are preferred only in combination with one of the other types of amines. The above classification shall include all mixtures of these known to the person skilled in the art.

The primary amines selected are monoethanolamine, isopropylamine, ethylenediamine and propanediamine. The secondary amines selected are jetanolamine, dipropylamine and dibutylamine. The tertiary amine selected is triethanolamine. The quaternary amines selected are tetramethylammonium chloride or hydroxide, tetraethylammonium chloride or hydroxide and tetrapropylammonium chloride or hydroxide.

The heterocyclic amines selected are hexamethylene diamine, bis(aminopropyl)piperazine and piperazine. The polishing rate accelerator can also be a compound selected from the group consisting of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and aminoethylethanolamine.

(15) (16) At least one compound selected from the group consisting of hydroxide, tetraethylammonium chloride, tetrapropylammonium chloride, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide.

Preferred bactericides are those that perform two functions:
It is a polishing rate enhancer in combination with bactericides and amines.

Killing proboscis■ A preferred biocide is sodium chlorite.

The preferred bactericidal agent is sodium omadine.
) (pyrithione).

The present invention also provides a method of polishing a silicon wafer comprising recirculating a colloidal silica slurry between a polishing plate containing a polishing pad and a silicon wafer, the method comprising colloidal silica, a polishing rate accelerator, a bactericidal The present invention includes an improved method characterized in that it uses a colloidal silica slurry consisting of a biocide and a biocide.

〔Example〕

The effectiveness of the novel colloidal silica slurry of the present invention is
This can be best illustrated by the examples below.

[This example uses the biocide tetramethylammonium hydroxide (TMA-OH) in eliminating aerobic bacteria and mold.
) or tetramethylammonium chloride (TMA-
CL). Samples 1 and 17 are conventional colloidal silica used for polishing silicon wafers;
Samples 2-14 on the other hand are selected silica slurries.

The microbiological test methods used to produce the results below are as follows.

(1) Dilute 1 part of the product with 20 parts of water (no pH adjustment); (2) Add the product to (a) Aspergillus nigiel, (
b) Pseudomonas aeruginosa
us (17) (18) aeruginosa) and (c) Erobacter aerogen (aer.

(3) place the inoculated sample on a rotary shaker (continuously rotating at 100 rpm) in a chamber controlled at 37°C; and (4) ) Sampling at 0 h, 1 week, and 2 weeks and growing organisms under the following conditions: (a) Total number = 72 h at 37 °C Manipulated using TGE agar (tryptone-glucose extraction) do, (b)
Aspergillus: operated using potato dextrose for 96 hours at 30°C, and (c) Elobacter: operated using EMB agar (eosin methylene blue) for 24 hours at 37°C.

Tables 1 to 5 below show the results of the microbiological tests. 99
．． A kill of 0% or more is considered an acceptable colloidal silica slurry.

(19) Table 1 TMA-OH microbiological results Table 2 shows that TMA-OH has a two and three times greater effect on bacteria and fungi.
It shows the influence of OH. The piperazine series showed more significant reductions than AREA in bacteria and mold, but mold Cts were insignificant.

(21) 11-Table TMA-OH Microbiological Results AEE8 Aminoethylethanolamine PIF:
Indicates piperazine.

Table 1 shows the effect of TMA-01 Lebel on bacteria and mold with and without sodium chlorite. This result shows that 0.25% active TMA- without sodium chlorite and sodium omazine (pyrithione)
It shows that OH inhibits the product after 2 weeks.

(20) Table 1 TMA-OFI Microbiological Results The addition of sodium omazine (pyrithione) to control mold is specified in Table 3. The results of the two-week test showed that almost all of the piperazine-based drugs were killed. However, mold Cts was still trivial.

(22) Table A - TMA-O11 Microbiological Results Table 51 The effect of higher AEEA levels on polishing rate is shown in Table 4. Higher levels of AREA did not actually increase the polishing rate of the colloidal silica slurry. Higher AREA with or without chlorine appears to help control both bacteria and mold.

Table 5 shows the effect that tetramethylammonium chloride (H-CL) instead of TMA-OH has on colloidal silica slurry. This result shows that TMA
-CL TM to control bacteria and mold after 2 weeks
It has been shown to be approximately as effective as A-Oll. Tests using systems with TMA-CL, sodium omazine, and sodium chlorite gave excellent control of both bacteria and mold.

Various samples were prepared and evaluated as polishing slurries against conventional colloidal silica. Sample 1 is aminoethylethanolamine (23) (24) conventional colloidal silica and Sample 17 is conventional colloidal silica containing 5% aminoethylethanolamine.

The field tests shown in Tables 6, 7 and 8 above were conducted with the following operating parameters. The polishing machine has 4 pieces of 7 pieces each.
Silte has a 36-inch diameter platen with four 18-inch heads that can hold inch wafers.
c 3800. The wafer is Tygh Sil
P-100 type, boron doped, obtained from icon.
4 inch diameter x 2.2±0.2 mil; KOH etch, resistivity between 30.0 and 60.0.

The template assembly is P with a 12mil pocket.
It was SA■ and was replaced after each operation 8 times. The polishing pad was a 36 inch diameter Suba 500 and was replaced between each run.

The polishing conditions for the field test were a polishing pressure of 150 gauge (5.551b/in2) and a polishing speed of 65 to 66P.
PM, polishing temperature 32-35° and 42-45°, pH 1
1.0-11.1, KOH alkaline, flow rate 210mL
/min, warm-up operation 10 minutes and polishing time 2
It was 0 minutes.

Field test results were obtained using the polishing test method described below.

(1) place a new polishing pad on the machine, (2) finish the pad by first cleaning it with deionized water and then scraping the pad with a safety razor blade, (3) attaching the wafer set to the machine. (4) remove the line and begin flowing the slurry to soak the pad; (5) perform a 5 minute warm-up at the desired pressure and flow rate (check and adjust temperature accordingly); (6) perform the operation. After cleaning the wafer, remove the wafer from the carrier and replace it with a good wafer, (7) perform the operation for 20 minutes, (8) clean the wafer, remove the wafer from the support, clean again and heat it. Place in water (≧1706F) for 5-10 minutes, and (9) air dry the wafer.

(25) (26) No. 1-Table 1-Table 2%AEEA 5%AEEA 1%AEEA 1%ARE^ 1% PIP 0,50 0.75 0.50 O,08 0,08 0, 08 29±10 27±10 33± 4 28± 8 31± 4 0.68 0.68 0.58 0.68 0.62 0.03 0゜05 0.06 0.03 0.04 In Table 6 , comparing the polishing rates of various colloidal silica slurries of the present invention against conventional colloidal silica (Samples 1 and 17) using the same polishing conditions. ^
The EE^ system is influenced by the level of TM^-OH.

i.e. 0.75% active rMa-o with 1% AEEA
H is required to obtain polishing rates comparable to conventional colloidal silica (Sample 1).

A is 40% solids, particle size between 35 and 55r++n, pH 8 with sodium as stabilizing cation.
, 5 represents the pace silica sol.

B has 50% solids content, particle size between 50 and 70 nm, pH 8.4 with sodium as stabilizing cation.
represents the pace silica sol.

(27) (28) Table A has a pH of 8.5 with 40% solids content, particle size between 35 and 55 nm, and sodium as stabilizing cation.
represents the base silica sol.

B has 50% solids content, particle size between 50 and 70 nm, pH 8.4 with sodium as stabilizing cation.
represents the base silica sol.

In Tables 7 and 8, TMA-OR and/or TMA
Field test polishing results using high amine level products with and without -CL are shown.

The second result shows that amine type and temperature are important variables for improved polishing rate. Additionally, TMA-OH and ^-CL resistance appear to be responsible for the improvement in polishing rate.

While the inventor has shown and described several embodiments in accordance with the invention, it is to be clearly understood that the same is susceptible to numerous variations and modifications that will be apparent to those skilled in the art. Therefore, the inventors do not intend to limit the invention to the detailed description shown and described, but wish to include within the scope of the invention all variations and modifications that fall within the scope of the appended claims. Not even.

Claims (1)

[Claims] 1. A colloidal silica slurry comprising colloidal silica, a polishing rate accelerator, a bactericide, and a biocide. 2. The colloidal silica is present in an amount ranging from about 1 to 60%, the polishing rate accelerator is present in an amount ranging from about 1 to 5%, and the bactericide is present in an amount ranging from about 0.10 to 1%. 25% and the biocide is present in an amount ranging from about 0 to 500 ppm. 3. The colloidal silica slurry of claim 2, wherein said bactericide is present in an amount ranging from about 0.25 to 0.75%. The colloidal silica slurry 5 of claim 3, wherein the biocide is present in an amount ranging from about 65 to 100 ppm.
The colloidal silica slurry 6 of claim 1, wherein the colloidal silica slurry further comprises a fungicide, and the colloidal silica slurry 7 of claim 1, wherein the fungicide is present in an amount ranging from about 0 to 2.0%. Colloidal silica slurry according to 6. 8. The colloidal silica slurry of claim 7, wherein said fungicide is present in an amount ranging from about 0 to 0.8%. 9. A colloidal silica slurry according to claim 8, wherein said fungicide is present in an amount ranging from about 0.1 to 0.5%, said colloidal silica having a final particle size ranging from about 4 to 200 nanometers. The colloidal silica slurry according to claim 1, comprising: 11. The colloidal silica slurry of claim 1, wherein said colloidal silica has a final particle size in the range of about 50-100 nanometers. 12. The colloidal silica slurry of claim 1, wherein the colloidal silica has a solids range of about 1 to 60%, a particle size of about 4 to 200 nanometers, and a pH of about 8 to 12.5. . 13. The colloidal silica slurry of claim 1, wherein said colloidal silica is replaced with at least one material selected from the group consisting of: 13. precipitated silica, pyrogenic silica, and silica gel. 14. The colloidal silica slurry according to claim 1, wherein the polishing rate accelerator is at least one compound selected from the group consisting of primary amines, secondary amines, tertiary amines, and heterocyclic amines. 15. The colloidal silica slurry of claim 14, wherein the polishing rate accelerator comprises at least one quaternary amine. 16. The colloidal silica slurry of claim 14, wherein said primary amine is selected from the group consisting of monoethanolamine, isopropylamine, ethylenediamine, and propanediamine. 17. The colloidal silica slurry of claim 14, wherein the secondary amine is selected from the group consisting of diethanolamine, dipropylamine, and dibutylamine. 18. The colloidal silica slurry according to claim 14, wherein the tertiary amine is triethanolamine. 19. The quaternary amine of claim 15, wherein the quaternary amine is selected from the group consisting of tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide. 15. Colloidal silica slurry 20, wherein the heterocyclic amine is selected from the group consisting of hexamethylene diamine, bis(aminopropyl)piperazine, and piperazine. 21. The colloidal silica slurry of claim 1, wherein the polishing rate accelerator is selected from the group consisting of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and aminoethylethanolamine. 22. The bactericide is at least one compound selected from the group consisting of tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide. A colloidal silica slurry according to claim 1. 23. Claim 1, wherein the biocide is sodium chlorite.
Colloidal silica slurry as described. 24. Claim 6, wherein the fungicide is sodium omazine.
Colloidal silica slurry as described. 25. A method of polishing a silicon wafer comprising recycling a colloidal silica slurry between a polishing plate containing a polishing pad and the silicon wafer, comprising colloidal silica, a polishing rate accelerator, a bactericide and a biocide. A method characterized by using a colloidal silica slurry consisting of: 26, the colloidal silica is present in an amount ranging from about 1 to 60%, the polishing rate accelerator is present in an amount ranging from about 1 to 5%, and the bactericide is present in an amount ranging from about 0.10 to 1%. 26. The colloidal silica slurry of claim 25, wherein the biocide is present in an amount ranging from about 0 to 500 ppm. 27. The method of claim 25, wherein the colloidal silica slurry also includes a fungicide. 28. The colloidal silica slurry of claim 27, wherein said fungicide is present in an amount ranging from about 0 to 0.8%.