TWI260338B - A method for preparing a silicon wafer polishing slurry - Google Patents

Abstract

The present invention relates to a method for preparing a silicon wafer polishing slurry, which comprises subjecting to a hydrothermal growing reaction of silicate in the presence of an alkanolamine. The present invention also relates to a method for polishing a silicon wafer by using the slurry prepared by the method.

Description

1260338 V. INSTRUCTION DESCRIPTION α) FIELD OF THE INVENTION The present invention relates to a slurry for polishing a crucible wafer substrate comprising an alkanolamine and an aqueous cerium oxide gel as a main component. The invention further relates to a method of polishing a tantalum wafer, the method comprising polishing a tantalum wafer using the slurry of the present invention. BACKGROUND OF THE INVENTION Description of the Related Art: In the semiconductor industry, germanium wafer substrates must be processed into a flat surface before they can be fabricated as integrated circuit components (IC Dev ice). In general, the polishing method for planarizing the surface of a tantalum wafer is to place the wafer on a rotary polishing machine equipped with a spring polishing pad (Pad), and apply a polishing slurry containing submicron particles on the surface of the wafer. To achieve the effect of flattening. Accordingly, there have been many conventional techniques for proposing a wafer. For example, U.S. Patent No. 4,169,336, the disclosure of which is incorporated herein incorporated by incorporated by reference in its entirety in its entirety in No. 33-7 discloses a polishing method in which a polishing slurry is used, which comprises an aqueous solution of cerium oxide and a mixture of a water-soluble ammonia and a water-soluble quaternary ammonium salt; and a polishing method is disclosed in U.S. Patent No. 4,892,61 It is selected from the addition of an alcohol amine to the second oxidation; the aqueous solution of the 5th epoxide is used as a polishing slurry to enhance the polishing performance. U.S. Patent No. 4,057,939 discloses a polishing slurry comprising a combination of an aqueous solution of very finely polished particles and a sodium or potassium salt of sodium carbonate and dichloroisocyanuric acid; U.S. Patent No. 4,588 4 No. 21 reveals a kind of moving liquid liquid which contains a mixture of * oxidized dream glue aqueous solution and _.

1260338 V. INSTRUCTIONS (2) The method of revealing the technique on the compound is to use the material of the light metal gas oxygen polishing slurry: the potassium sulphide antimony sulphate aqueous solution is used for the action, and the eighth is added with ammonia or Polishing aids such as ammonia salts or effects.兮 ^ 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化 氧化It is introduced and remains on the surface of the wafer, which will result in difficulty in cleaning after polishing. In particular, the surface of the wafer contaminated with metal will seriously cause poor quality of the finished circuit components of the back-end process.

SUMMARY OF THE INVENTION The present invention relates to a slurry for polishing a semiconductor material such as a ruthenium wafer substrate. The polishing slurry includes an alkanolamine and is formed by a hydrothermal growth reaction in an alkaline stable state. An aqueous solution of oxidized stone. The polishing slurry of the present invention is characterized by a very low amount (ppm level) of a light alkali metal such as sodium or potassium, and is effective for polishing the surface of the wafer. DETAILED DESCRIPTION OF THE INVENTION: The main feature of the present invention is to provide a polishing slurry for polishing a semiconductor material such as a tantalum wafer substrate, the polishing slurry being an aqueous solution of a dilute gelatin stabilized with an alkanolamine. In general, the method for industrially producing an aqueous solution of montery monoxide is selected from the group consisting of alkali metal silicates, such as sodium citrate or potassium citrate, and is grown in a hydrothermal reaction under an experimentally stable state. It is usually selected from light alkali metal cerium oxides such as sodium hydroxide, potassium cerium oxide aqueous solution or ammonia water or ammonia as raw materials for alkaline stabilization. The preparation method of cerium oxide aqueous solution is

Page 6 1260338 V. Description of invention (3)

Silica11, Chapter 3, (1979) R. K. Iler, 11 The Chemistry o is described in detail. The polishing slurry of the present invention uses a sodium citrate salt commonly known as water giass as a reaction starting material, and the molar ratio of cerium oxide (S i 0 2) / sodium oxide (Na 2 〇) is about 2 /1~4/1, usually, sodium citrate salt must be used to carry out hydrothermal growth reaction after removing ionic impurities by cation exchange resin and/or anion exchange resin. An example of the calciner as an intrinsic stabilizer in the polishing slurry of the present invention may be, for example, nioiioethanolaniine, diethanolamine, triethanolamine, preferably ethanolamine; calcinolamine addition. The amount is Q1% by weight to 50% by weight, preferably 0.5% by weight to 2% by weight, based on the weight of the polishing slurry. The solid content of the polishing slurry of the present invention is from 1% by weight to 50% by weight, preferably from 10% by weight to 3% by weight. The polishing slurry of the present invention has a particle size distribution of 5 to 200 nm, preferably 30 to 10 nm. The pH of the polishing slurry of the present invention is 9 · 0 to 1 3 · 0, preferably 1 〇 · 〇 ~ 12· 0 〇 The content of sodium ions or unloading ions in the polishing slurry of the present invention is 1 Qppm or less. The polishing slurry of the present invention is used for polishing a tantalum wafer substrate, and the size thereof is not limited, but is usually, for example, 3", 4", 5", 6", 81, 12" wafer. The invention further relates to a method of polishing a tantalum wafer, the method comprising the step of polishing a tantalum wafer using the Shihwa wafer polishing slurry of the present invention. In the method of Polishing the wafer of the present invention, any polishing machine can be used, and

Page 7 1260338 V. INSTRUCTIONS (4) There are no special restrictions, but for example IPEC-472 can be used; the polishing pad is Rodel IC ~ 1 400, K - GRV. If you use the Ipec-472 to move the machine, the polishing parameters are as follows: Apply pressure (D〇wnforce): 3~8psi Backpressure: 0~2psi Platen Speed: 30~12 Orpm Carrier Speed: 30~120rpm Slurry Flow Rate: 30~300ml/min Platen Temperature: 15~60°C Polishing Time: l~20 min The invention is illustrated by the following examples, which are not intended to limit the invention. EXAMPLES Example 1·Preparation of polishing slurry (a) Industrial grade No. 3 water glass was selected as the reaction starting material, which contained 28.88% by weight of cerium oxide (SiO 2 ) and 9.1% by weight of oxidation. Sodium (Na20), less than 200 ppm of ferric oxide (Fe2〇3), and about 62% by weight of water, wherein the molar ratio of cerium oxide/sodium oxide is 3·27.

First, 5,000 kg of water glass was dissolved in 19.11 kg of deionized water (Deionized Water) to prepare a 24.16 kg aqueous solution of sodium citrate, which contained about 6.0% by weight of two Yttrium oxide. Step (b) Filling a glass tube made of Pyre X glass with 2 000 ml is produced from

1260338 V. INSTRUCTIONS (5) Rhom & Hass, H-type strong acid type cation exchange resin of trade name i 5〇〇11. Next, the aqueous solution of sodium citrate containing about 6% by weight of cerium oxide is flowed downward at a liquid hourly space velocity (LHSV) of about 2,000 hours (Downflow). ) Flowing through the cation exchange resin to collect the ion exchanged gi 1 ici C aci d, measuring the pH value of about 2.93~3·07, and the electrical conductivity is about 353~S/cm, solid The average content is about 5. 22%, and the total collection is about 21 · 85 kg. Step (c) In a reaction flask (react〇r flask) of Pyrex glass, a size of 3 liters, 2·13 kg (about 2 liters) of citric acid obtained by the step (b), 4 gram of gram of gram Ίο% by weight aqueous solution of monoethanolamine at a stirring speed of 2 rpm, and heated to 1000 ° C in an oil bath for 2 hours. Next, 2 · 13 kg (about 2 liters) of the acid was added to the reaction solution at a rate of 16 ml / min while distilling off the water at an equal rate to obtain a solid content of 118% by weight, pH l 〇3, a silica s〇1 seed crystal having a particle diameter d50 of about 12.9 nm has a seed of about 2. 14 kg. Step (d) In a 3 liter size reaction flask, the seed crystal obtained by the step (c) was charged with 192·6 g (about 185 ml) and 1315 ml of deionized water, and the stirring was carried out at 200 rpm to be heated to l〇〇. °C. Next, 5 68 kg (about 5 33 liters) of ginseng acid was added to the reaction solution at a rate of 16 ml/min while distilling off the water at an equal rate to obtain a solid fraction of 16 2% by weight, pH 9 81. An aqueous solution of cerium oxide gel having a particle diameter d5 of about 31.6 nm is about 165 kg. Step (e)

1260338 V. INSTRUCTIONS (6) ---- In a 3 liter reaction flask, install A 丄 愉 / 」 」 」 」 」 」 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 , 1〇>|"古11丄乳1(:") and 1 2 4 53⁄4 liters of deionized water, 1 mix speed 20 rpm, heat to 10 (TC. technology -^, 〇r7X ^ ^, Next, 5 · 2 7 kg (about 4 9 5 liters) of citric acid was added to the reaction solution at a rate of 16 ml / min, while at the same rate will be reduced, slowly dripping 1 〇 4 4 % monoethanolamine aqueous solution to adjust the pH of the reaction solution about 9.5-10.0' end of the reaction to obtain a solid content of 18 2% by weight, PH9.99' particle size d50 about 47.4nm of cerium oxide gel aqueous solution about 1 shoulder kilogram. Step (f The reaction flask of the size of 3 liters was charged with 380. 7 g (about 343 liters) of the aqueous cerium oxide gel solution prepared in the step (e) and 1 liters of deionized water at a rate of 20 rpm. 100 ° C. Next, 4 85 kg (about 4 55 liters) of linalic acid was added to the reaction solution at a rate of 16 ml / min while distilling off the water at an equal rate. Slowly drip 10% by weight aqueous solution of monoethanolamine, adjust the reaction solution pΗ about 10·0-11.0' reaction end point to obtain the solid part IQ 1% by weight, ρ Η1 0 · 8 3 'granule control d 5 〇 about *7 0 · 0 The nanometer aqueous solution of sulphur dioxide is about 167 kg' and the sodium and potassium ion contents in the solution are determined to be 85 ριηη and 5 ppm ° respectively. Example 2. Polishing method

The polishing machine selected in this embodiment is IPEC-472; the polishing pad is 1^〇(1611(:-1400,1[-61^.1?£(:-47 2 polishing table setting parameters are as follows) : Applying pressure (Downforce): 4psi Backpressure: Opsi

1260338 V. Invention description (7) Platen Speed: 90 rpm Carrier Speed: 45 rpm Slurry Flow Rate: 100 ml/min Platen Temperature: 4 2 ° C Polishing time: 10 min Polishing number: 3 pieces In this example, the cerium oxide gel aqueous solution prepared in the above Example 1 was selected as the polishing slurry, and the dilution ratio was: slurry: deionized water = 1:6 The diluted slurry has a solid content of 2.73% by weight and ρΗ10·3. Before and after polishing, the difference in weight of the Shixi wafer was measured to convert the polishing removal rate, and the surface roughness (Roughness) was measured by an atomic force microscope (AFM). As a result, the polishing removal rate of the three ruthenium wafers was measured to be 〇·42 0 / ζ m / min, and the surface roughness was averaged 0.5 5 nm. Comparative Example 1 The preparation of the polishing slurry was carried out in the same manner as in Example 1. Grade 3 water glass is the reaction starting material, 1 small test rig with a capacity of 1 ton/batch is hydrothermally synthesized, and the reaction enthalpy is a medium with a 45% aqueous solution of potassium hydroxide (K〇H) as an alkaline stabilizer. Plough solid form = 1% by weight ' ρ Η 10 · 54 ' particle size d5 (^ 78 〇 nm of cerium oxide glue and the sodium ion and potassium ion content of the solution were determined to be 11. 5 叩晌 Comparative Example 2 · polishing method only The same polishing machine of Example 2 was used, and the polishing and glazing parameters were compared. The aqueous solution of the montmorillonite gel prepared in Example 1 was a polishing poly ratio, and the slurry: deionized water = 1:10, the diluted slurry.

1260338 V. The invention has a solid content of 2.74% by weight, ρΗΙΟ. As a result, the polishing removal rate of the three ruthenium wafers was 〇·281/ζ m/min, and the surface roughness was 0.73 nm on average. The results of Example 2 and Comparative Example 2 show that the polishing of the tantalum wafer by the polishing slurry of the present invention can achieve better polishing removal rate than the polishing of the tantalum wafer without the slurry of the alkanolamine. The preferred surface roughness is.

Page 12 1260338 Schematic description

Page 13

Claims (1)

1260338 VI. Patent Application Scope 1. A method for preparing a Shiyue wafer polishing slurry, comprising: performing hydrothermal treatment of cerium oxide under the condition of heating and refluxing and slow stirring in the presence of an alkanolamine as a stabilizer Grinding slurry is prepared by growing reaction; wherein the barley alkali content in the calendering slurry is 〇·1% by weight to 5.0% by weight, the solid content is If%% to 50% by weight, and the particle size distribution is 5 to 200 nm. , ρ Η is 9. 〇 to 13·0, sodium ion and potassium ion content are respectively l〇ppm or less. 2. The preparation method of claim 1, wherein the alkanolamine is selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, and/or a composition thereof. . 3. The preparation method of claim 2, wherein the alkanolamine is monoethanolamine. 4. The preparation method of claim 1, wherein the slurry has a solid content of 10% by weight to 30% by weight. 5. The preparation method of claim 1, wherein the slurry has a particle size distribution of 30 to 1 〇 〇 nm. 6 · The preparation method of the scope of the patent application, wherein the slurry pIL^i〇. 0~1 2 · 0 〇 mm第14页