Polishing solution for glass bodies and method for polishing glass bodies

Abstract

To provide a glass body polishing method which dispenses with or facilitates management of a polishing liquid, can omit or simplify a separate cleaning step of a glass body after polishing, facilitates recycling or disposal of the polishing liquid after polishing, and can achieve persistence of polishing.SOLUTION: A polishing liquid for a glass body in the present invention is a polishing liquid 11a for a glass body which is interposed between a polished object 1 and a polishing pad 10, and relatively moves the polished object 1 and the polishing pad 10 under a predetermined surface pressure and thereby polishes the polished object 1 by a CMP method. The polished object 1 is composed of glass containing a silicic acid. The polishing pad 10 has a base material which is composed of a resin and where a plurality of air bubble are formed, and polishing particles which are composed of CeO2 and are held in the base material or the air bubbles. The polishing liquid 11a for the glass body does not contain polishing abrasive grains, and contains water and a surface active agent dissolved in the water in such a range as not to generate continuous foams in polishing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polishing solution for glass bodies and a method for polishing glass bodies. [Background technology]

[0002] Patent Document 1 discloses a glass polishing method for polishing a workpiece made of silica-containing glass using the CMP (Chemical Mechanical Polishing) method. In this glass polishing method, in order to polish the glass substrate as a glass body, a slurry containing abrasive particles is interposed as a polishing liquid between the glass substrate (workpiece) and the polishing pad, and the workpiece and the polishing pad are moved relative to each other under a predetermined surface pressure. Foamed urethane is used as the polishing pad, and ceria (cerium oxide, CeO2) is used as the abrasive particles dispersed in the polishing liquid.

[0003] However, in the conventional glass polishing methods described above, the polishing solution contains abrasive particles. Therefore, these glass polishing methods require careful management of the polishing solution, as well as cleaning of the glass after polishing. Furthermore, because the polishing solution is expensive, it is necessary to collect the polishing solution after polishing, readjust it to a predetermined state, and reuse it. In addition, when disposing of the polishing solution and cleaning solution after polishing, complex processing is required to prevent them from harming the environment. As a result, conventional glass polishing methods require complex processes in addition to the polishing process, leading to increased polishing costs.

[0004] In this regard, the applicant proposed a glass polishing method described in Patent Document 2. This glass polishing method employs a polishing pad in which polishing particles made of CeO2 are held within air bubbles in the base material, and since the polishing solution is water only, there is no need to manage the polishing solution. Furthermore, the glass body is already washed with the polishing solution after polishing, so a separate cleaning process can be omitted or simplified. In addition, since the polishing solution is inexpensive, it is not always necessary to collect and reuse the polishing solution after polishing. Moreover, even when disposing of the polishing solution after polishing, not much processing is required. For this reason, this glass polishing method and glass polishing apparatus do not require complex processes other than the polishing process. Therefore, this glass polishing method makes it possible to reduce polishing costs. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 3531906 [Patent Document 2] Patent No. 6976282 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, according to the inventors' test results, the glass polishing method described in Patent Document 2 above is desirable for its polishing durability.

[0007] The present invention has been made in view of the above-mentioned conventional circumstances, and aims to solve the problem of providing a glass polishing method in which the management of the polishing solution is unnecessary or easy, a separate cleaning step for the glass body after polishing can be omitted or simplified, the reuse or disposal of the polishing solution after polishing can be easily done, and the polishing can be made more durable. [Means for solving the problem]

[0008] The present invention provides a polishing solution for glass bodies which is interposed between the workpiece and the polishing pad, and which polishes the workpiece by the CMP method by moving the workpiece and the polishing pad relative to each other under a predetermined surface pressure. The object to be polished is made of glass containing silica, The polishing pad comprises a base material made of resin, in which a plurality of air bubbles are formed, and polishing particles made of CeO2, which are held within the base material or within the air bubbles. It does not contain abrasive particles, but contains water and a water-soluble surfactant in an amount that does not produce continuous bubbles during polishing. fruit, The surfactant is at least one of potassium stearate, sodium stearate, and potassium palmitate. It is characterized by the following:

[0009] Furthermore, the present invention relates to a glass polishing method in which a glass polishing liquid is interposed between the workpiece and the polishing pad, and the workpiece and the polishing pad are moved relative to each other under a predetermined surface pressure, thereby polishing the workpiece by the CMP method. The object to be polished is made of glass containing silica, The polishing pad comprises a base material made of resin, in which a plurality of air bubbles are formed, and polishing particles made of CeO2, which are held within the base material or within the air bubbles. The aforementioned polishing liquid for glass bodies does not contain abrasive particles, and contains water and a water-soluble surfactant in an amount that does not produce continuous bubbles during polishing. fruit, The surfactant is at least one of potassium stearate, sodium stearate, and potassium palmitate. It is characterized by the following:

[0010] In the polishing liquid for a glass body and the glass body polishing method of the present invention, a polishing pad that holds polishing particles made of CeO2 in a base material or in air bubbles is employed. If the polishing particles are held in air bubbles, until they separate from the polishing pad, the workpiece is polished while being elastically held by the polishing pad. At this time, the abrasive grains in the air bubbles are held by the polishing pad with a force stronger than that of the abrasive grains used in the free type and weaker than that of the abrasive grains used in the conventional fixed type. Even if the polishing particles are held in the base material, until they separate from the polishing pad, the workpiece is polished while being elastically held by the polishing pad. At this time, the abrasive grains held in the base material are held by the polishing pad with a force stronger than that of the abrasive grains used in the free type, stronger than that of the abrasive grains in the pores, and weaker than that of the abrasive grains used in the conventional fixed type. Therefore, the polishing particles are difficult to fall off from the air bubbles or the base material, and it is difficult to generate scratches.

[0011] Also, although the polishing liquid for a glass body is not only water but does not contain abrasive grains, management is unnecessary or easy. Also, the glass body after polishing is already washed with the polishing liquid, and a separate washing process can be omitted or simplified. Also, since the polishing liquid is inexpensive, it is not always necessary to recover and reuse the polishing liquid after polishing. Furthermore, even when the polishing liquid after polishing is discarded, not much treatment is required. Therefore, in this polishing liquid for a glass body and the glass body polishing method, complicated processes other than the polishing process are not required.

[0012] Furthermore, according to the test results of the inventors, the polishing liquid for a glass body contains water and a surfactant dissolved in water within a range that does not generate continuous bubbles during polishing, so the sustainability of polishing can also be realized.

Advantages of the Invention

[0013] In the glass body polishing method, management of the polishing liquid is unnecessary or easy, a separate washing process for the glass body after polishing can be omitted or simplified, reuse or disposal of the polishing liquid after polishing is easy, and the sustainability of polishing can also be realized.

Brief Description of the Drawings

[0014] [Figure 1] Figure 1 is a side view of the main part of the vitreous grinding apparatus used in the test. [Figure 2] Figure 2 is a graph showing the relationship between the polishing time and the polishing rate in the test.

Embodiments for Carrying Out the Invention

[0016] The vitreous polishing liquid preferably has a viscosity of 5 to 100 cP (mPa·s) at 25°C, and more preferably 40 to 80 cP (mPa·s) at 25°C. Further, according to the tests of the inventors, the surfactant is preferably at least one of potassium stearate, sodium stearate, and potassium palmitate. If these are used, they are water-soluble, and it is difficult for the polishing liquid for the vitreous body to generate continuous bubbles, and the sustainability of polishing is excellent. In particular, according to the tests of the inventors, the vitreous polishing liquid is preferably an aqueous solution containing 2% by mass or less of potassium stearate or an aqueous solution containing 2% by mass or less of sodium stearate.

[0017] "Test" First, the following materials were prepared. (Base resin) PES (polyethersulfone) (Polishing particles) Cerium oxide (CeO2) (average particle size: 300 nm) (Solvent) NMP (N-methyl-2-pyrrolidone)

[0018] These were mixed at 20% by volume of the base resin, 20% by volume of the polishing particles, and 55% by volume of the solvent to obtain a paste. Using the obtained paste, it was formed into a sheet-like molded body using a molding device such as a T-die. Then, the molded body was immersed in a replacement liquid and taken out from the replacement liquid after a predetermined time had elapsed. In the molded body, all the solvents were replaced with the replacement liquid and solidified, becoming a solidified body. The solidified body was dried and ground to a predetermined thickness to obtain the polishing pad 10 described in Japanese Patent No. 6976282.

[0019] This polishing pad 10 has a base material made of resin with multiple air bubbles formed on it, and polishing particles made of CeO2 that are held within the base material or within the air bubbles. The base material is made of polyether. The average particle size of the polishing particles is 300 nm. The polishing particles are present in a proportion of 25 volume% of 100 volume% of the polishing pad. According to the inventors' test results, similar effects are produced if the polishing particles are held within the base material or within the air bubbles in a proportion of 5 to 45 volume% of 100 volume% of the polishing pad.

[0020] The surface of the obtained polishing pad 10 was used as the polishing surface, and wafers 1 were polished using a wafer polishing apparatus (LAPOLISH 15 manufactured by LAPMaster). Each wafer 1 is made of synthetic quartz with a diameter of 4 inches.

[0021] As shown in Figure 1, the wafer polishing apparatus comprises multiple carriers 5, a base plate 7, a drive unit 9, and a polishing fluid supply device 11. Although only a single carrier 5 is shown in Figure 1, the wafer polishing apparatus has multiple carriers 5. Each carrier 5 is horizontal and disc-shaped. A second fixing surface 5a is recessed on the lower surface of each carrier 5, and a wafer 1 is fixed to the second fixing surface 5a. A carrier rotation shaft 5b is vertically projected from the upper surface of each carrier 5.

[0022] The surface plate 7 is a horizontal disc shape that encloses all the carriers 5. A surface plate rotation shaft 7a is provided protruding vertically from the bottom surface of the surface plate 7. The top surface of the surface plate 7 is the first fixed surface 7b. Disc-shaped polishing pads 10 are fixed to the first fixed surface 7b with adhesive so as to face each wafer 1.

[0023] The drive unit 9 comprises a main drive unit 9a, a sub-drive unit 9b, and a pressurizing device 9c. The main drive unit 9a rotates the platen rotation shaft 7a around the first axis O1 at a predetermined speed. The sub-drive unit 9b rotates each carrier rotation shaft 5b around the second axis O2 at a predetermined speed. The pressurizing device 9c applies a predetermined load to each carrier rotation shaft 5b and the sub-drive unit 9b toward the platen 7.

[0024] The polishing liquid supply device 11 is provided above the surface plate 7. The polishing liquid supply device 11 interposes a polishing liquid 11a for glass bodies between each wafer 1 and the polishing pad 10.

[0025] As the polishing liquid 11a for glass bodies, the aqueous solutions shown in Table 1 were used. Each aqueous solution was obtained by dissolving the following surfactants in water at the concentrations (mass %) shown in Table 1. Potassium laurate (C 12 H 23 KO2) Potassium myristate (C 14 H 27 KO2) Potassium palmitate (C 16 H 31 KO2) Potassium stearate (C 18 H 35 KO2) Potassium oleate (C 18 H 33 KO2) Potassium linoleate (C 18 H 31 KO2) Potassium linolenate (C 18 H 29 KO2) ]>Sodium stearate (C 18 H 35 NaO2) Calcium stearate ((C 18 H 35 O2)2Ca)

[0026] In this wafer polishing apparatus, each wafer 1 was polished under the following conditions. Rotation speeds of the first and second surface plates: 60 (rpm) Sizes of the first and second polishing pads: diameter 300 (mm) Rotation speed of the carrier: 60 (rpm) Processing surface pressure: 60 (kPa) Supply timing of the polishing liquid for glass bodies: 10 mL / min

[0027] The presence or absence of foam generation, water solubility, and polishing durability of the glass polishing solution 11a were evaluated. The results are shown in Table 1. The viscosity (cP (mPa·sec)) of each glass polishing solution 11a is also shown in Table 1.

[0028] The presence or absence of bubbles was determined by visually observing whether bubbles formed in the glass polishing solution 11a during the polishing test. If no bubbles were present, it was marked with ◎; if a single bubble of 3 mm or less was present, it was marked with ○; and if continuous bubbles were present, it was marked with ×.

[0029] Water solubility was judged visually; a "○" was given if the solute was completely dissolved, and a "×" was given if any solute remained.

[0030] The durability of the polishing was judged by the polishing method using the apparatus shown in Figure 1. A score of ○ was given if the polishing rate was better than that of water alone, and a score of × was given if it was the same or worse.

[0031] [Table 1]

[0032] Furthermore, the relationship between polishing time (minutes) and polishing rate (nm / min) for each polishing solution 11a was evaluated in comparison to the case where only water was used as the polishing solution 11a for glass bodies. The results are shown in Figure 2.

[0033] As shown in Table 1 and Figure 2, if the surfactant is potassium stearate, sodium stearate, or potassium palmitate, it is water-soluble, the glass polishing solution 11a is less likely to generate continuous bubbles, and the polishing duration is excellent. In particular, if an aqueous solution of 1% by mass of potassium stearate is used as the glass polishing solution 11a, the polishing duration is extended by about three times compared to when water alone is used as the glass polishing solution 11a. If an aqueous solution of 2% by mass of potassium stearate is used as the glass polishing solution 11a, the polishing duration is extended by about twice as much. If an aqueous solution of 2% by mass or less of sodium stearate is used as the glass polishing solution 11a, the polishing duration is extended by about twice as much.

[0034] In this case, it is presumed that the outermost surface of the CeO2 particles exerts a chemical effect on the glass wafer 1. That is, the Ce of the CeO2 particles 3+ It is presumed that this weakens the Si-O bond in H2O, causing chemical polishing.

[0035] Furthermore, it is found that the glass polishing solution 11a preferably has a viscosity of 5 to 100 cP (mPa·sec) at 25°C, and more preferably 40 to 80 cP (mPa·sec) at 25°C. If the viscosity is within this range, Ce can be polished for a long time. 3+ It is presumed that this material comes into contact with Si-O, making it prone to chemical polishing.

[0036] Furthermore, this glass polishing method employs a polishing pad 10 in which polishing particles made of CeO2 are held within the base material or air bubbles. As a result, the polishing particles are less likely to fall off from the air bubbles or base material, and scratches are less likely to occur.

[0037] Furthermore, the glass polishing solution 11a used in the test, although not just water, does not contain abrasive particles, making management unnecessary or easy. Also, since the wafer 1 after polishing is already cleaned with the glass polishing solution 11a, a separate cleaning process can be simplified. In addition, because the glass polishing solution 11a is inexpensive, it is not always necessary to collect and reuse the glass polishing solution 11a after polishing. Moreover, even when disposing of the glass polishing solution 11a after polishing, no special processing is required.

[0038] Although the present invention has been described above in relation to the tests, it goes without saying that the present invention is not limited to what was used in the tests, and can be applied with appropriate modifications without departing from its spirit.

[0039] For example, the material to be polished is not limited to a wafer 1 made of synthetic quartz, but may also be borosilicate glass, lead silicate glass, etc., as long as it contains silica. [Industrial applicability]

[0040] This invention can be used in manufacturing methods and manufacturing equipment for camera glass lenses, hard disks, flat panel displays, and the like. [Explanation of symbols]

[0041] 1…Material to be polished (wafer) 10… Polishing pad 11a…Polishing solution for glass bodies

Claims

1. A polishing liquid for glass bodies, which is interposed between the workpiece and the polishing pad, and polishes the workpiece by the CMP method by moving the workpiece and the polishing pad relative to each other under a predetermined surface pressure, The object to be polished is made of glass containing silica, The polishing pad is made of resin and consists of a base material in which multiple air bubbles are formed and CeO 2 It consists of abrasive particles held within the base material or within the bubbles, It does not contain abrasive particles, and contains water and a water-soluble surfactant in an amount that does not produce continuous bubbles during polishing. The aforementioned surfactant is characterized by being at least one of potassium stearate, sodium stearate, and potassium palmitate.

2. The polishing solution for glass bodies according to claim 1, wherein the potassium stearate is an aqueous solution containing 2% by mass or less.

3. The polishing solution for glass bodies according to claim 1, wherein the sodium stearate is an aqueous solution containing 2% by mass or less.

4. A polishing solution for glass bodies according to any one of claims 1 to 3, wherein the viscosity is 5 to 100 cP at 25°C.

5. The polishing solution for glass bodies according to claim 4, wherein the viscosity is 40 to 80 cP at 25°C.

6. In a polishing method in which a workpiece is polished by the CMP method, a glass polishing solution is interposed between the workpiece and the polishing pad, and the workpiece and the polishing pad are moved relative to each other under a predetermined surface pressure, The object to be polished is made of glass containing silica, The polishing pad is made of resin and consists of a base material in which multiple air bubbles are formed and CeO 2 It consists of abrasive particles held within the base material or within the bubbles, The aforementioned polishing liquid for glass bodies does not contain abrasive particles, and contains water and a water-soluble surfactant in an amount that does not produce continuous bubbles during polishing. A method for polishing glass bodies, characterized in that the surfactant is at least one of potassium stearate, sodium stearate, and potassium palmitate.

7. The glass polishing method according to claim 6, wherein the polishing pad is made of a polyether base material, and the polishing particles have an average particle size of 300 nm and are held in the base material or in the bubbles at a ratio of 5 to 45 volume percent of 100 volume percent of the polishing pad.

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