A recyclable chemical mechanical polishing liquid for silicon wafers

Abstract

The present invention is a recyclable silicon wafer chemical mechanical polishing liquid, comprising silica sol abrasive, surfactant, deionized water, pH regulator A, and pH regulator B, wherein the components are respectively as follows by mass percentage: silica sol abrasive: 15-25%; pH regulator A: 1%-3%, which is a quaternary ammonium base; pH regulator B: 5%-15%, which is one or more of primary amine base, secondary amine base, and tertiary amine base; surfactant: 0.01%-0.1%, which is a nonionic surfactant; and the balance is deionized water. The removal rate of the polishing liquid is above 0.9 μm / min, and the removal rate after eight cycles is still above 0.8 μm / min, and the attenuation rate is controlled within 8%, which can be recycled multiple times under the premise of high removal rate.

Description

Technical Field

[0001] The invention relates to the technical field of silicon slice rough polishing, and in particular to a recyclable silicon slice chemical mechanical polishing liquid. Background Art

[0002] The chemical mechanical polishing (CMP) of silicon wafers is divided into three steps: rough polishing, medium polishing, and fine polishing. The first step is rough polishing, which is to remove the grinding damage layer. The removal rate in this step is very high. The second step is medium polishing, which is to improve the surface smoothness and obtain a lower roughness. The removal speed is slow, but there are still micro defects on the surface of the silicon wafer. The third step is fine polishing, which is to remove scratches, pits, organic residues, particles and other micro defects, so that the surface has a good nano-morphology and reduce the surface haze value.

[0003] The main indicator of silicon wafer rough polishing is the removal rate. While ensuring a high removal rate, the polishing liquid can be reasonably recycled to extend its service life and effectively reduce the cost of polishing.

[0004] At present, most silicon wafer processing plants only have requirements for removal rate in the rough polishing stage. If the removal rate of the polishing liquid can be guaranteed not to decay after long-term use, or the decay is small, the processing cost can be effectively reduced. At present, most silicon rough polishing liquids on the market can only be used once, or new liquid needs to be added after a short circulation period, which makes it difficult to achieve long-term and effective circulation. Summary of the invention

[0005] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a recyclable chemical mechanical polishing liquid for silicon wafers, which can be recycled for a long time and with high efficiency while ensuring a high removal rate.

[0006] The invention provides a recyclable silicon wafer chemical mechanical polishing liquid, which comprises silica sol abrasive, pH regulator A, pH regulator B, surfactant and deionized water, and is characterized in that the components comprise the following by mass percentage: silica sol abrasive: 15-25%; pH regulator A: 1%-3%, which is a quaternary ammonium base; pH regulator B: 5%-15%, which is one or more of a primary amine base, a secondary amine base and a tertiary amine base; surfactant: 0.01%-0.1%, which is a non-ionic surfactant; and the balance is deionized water.

[0007] The pH adjuster A: the quaternary ammonium base is at least one of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, 1-adamantyltrimethylammonium hydroxide, hexamethylammonium hydroxide or derivatives thereof.

[0008] The pH adjuster B: the primary amine base is monoethanolamine (MEA), monoisopropanolamine or their derivatives; the secondary amine base is diethanolamine (DEA), diisopropanolamine or at least one of their derivatives; the tertiary amine base is triethanolamine (TEA), triisopropanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine or at least one of their derivatives.

[0009] The polishing liquid may further include a chelating agent: one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentaethylenephosphonic acid, and salts thereof, for chelating metal ions.

[0010] Preferably, the abrasive particle size of the silica sol abrasive is 40-80 nm; the mass content of the pH adjuster B is 10%-15%, the mass content of the pH adjuster A is 2%-3%; and the mass content of the surfactant is 0.05%-0.08%.

[0011] The surfactant may be any one of JFCE, AEO-3, AEO-7, and AEO-9.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] In the present invention, the quaternary ammonium base is used as an organic strong base, which is completely ionized in water to ensure a high removal rate. At the same time, the primary amine base, the secondary amine base, and the tertiary amine base are used as organic weak bases, which can ionize OH in water. - , to fill the OH consumed during polishing - , ensuring the circulation capacity. The combination of organic strong base and organic weak base not only ensures a high removal rate, but also prolongs the service life of the polishing liquid, allowing the polishing liquid to be recycled, effectively saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a comparison chart of the polishing test results of Examples 1-11. DETAILED DESCRIPTION

[0015] The present invention is further explained below in conjunction with the embodiments and drawings, but this is not intended to limit the scope of protection of the present application.

[0016] The polishing liquid of the present invention simultaneously adds an organic strong base and an organic weak base. The quaternary ammonium base, as an organic strong base, is completely ionized in water and exists in the polishing liquid in the form of ions, providing the OH required in the polishing process. -. Thus, under the mechanical action, the chemical reaction is fully carried out, and the mechanical action and chemical reaction work together to achieve a high removal rate. Primary amine bases, secondary amine bases, and tertiary amine bases are organic weak bases that can exist in the polishing liquid in molecular form and can ionize OH in water. - , maintaining the dynamic balance between molecules and ions. During the polishing process, some OH - , breaking the dynamic balance between molecules and ions. In order to maintain the balance, this kind of organic weak base will continuously ionize OH - , to maintain the OH in the polishing liquid - The concentration is high, the polishing rate is guaranteed, and the polishing liquid can be reasonably recycled. The polishing liquid of the present application can still ensure a high removal rate after five hours of use.

[0017] Example 1

[0018] Polishing liquid ratio:

[0019] Silica sol abrasive with a particle size of 60 nm: 20%; TMAH: 2%; JFCE: 0.05%; the balance is deionized water.

[0020] Polishing conditions:

[0021] Machine: Universal-150B; polishing head / disc speed: 87 / 93rpm; pressure: 3psi; flow rate 150ml / min; polishing time: 30min; the polishing liquid is diluted with deionized water during use, and the dilution ratio of the polishing liquid to deionized water is 1:20.

[0022] Example 2

[0023] Polishing liquid ratio:

[0024] Silica sol abrasive with a particle size of 60 nm: 20%; MEA: 10%; JFCE: 0.05%; the balance is deionized water.

[0025] Polishing conditions: Same as Example 1

[0026] Example 3

[0027] Polishing liquid ratio:

[0028] Silica sol abrasive with a particle size of 60 nm: 20%; DEA: 10%; JFCE: 0.05%; the balance is deionized water.

[0029] Polishing conditions: Same as Example 1

[0030] Example 4

[0031] Polishing liquid ratio:

[0032] Silica sol abrasive with a particle size of 60 nm: 20%; TEA: 10%; JFCE: 0.05%; the balance is deionized water.

[0033] Polishing conditions: Same as Example 1

[0034] Example 5

[0035] Polishing liquid ratio:

[0036] Silica sol abrasive with a particle size of 60 nm: 20%; TMAH: 1%; MEA: 10%; JFCE: 0.05%; the balance is deionized water.

[0037] Polishing conditions: Same as Example 1

[0038] Example 6

[0039] Polishing liquid ratio:

[0040] Silica sol abrasive with a particle size of 60 nm: 20%; TMAH: 2%; MEA: 10%; JFCE: 0.05%; the balance is deionized water.

[0041] Polishing conditions: Same as Example 1

[0042] Example 7

[0043] Polishing liquid ratio:

[0044] Silica sol abrasive with a particle size of 60 nm: 20%; TMAH: 3%; MEA: 10%; JFCE: 0.05%; the balance is deionized water.

[0045] Polishing conditions: Same as Example 1

[0046] Example 8

[0047] Polishing liquid ratio:

[0048] Silica sol abrasive with a particle size of 60 nm: 20%; TMAH: 2%; MEA: 5%; JFCE: 0.05%; the balance is deionized water.

[0049] Polishing conditions: Same as Example 1

[0050] Example 9

[0051] Polishing liquid ratio:

[0052] Silica sol abrasive with a particle size of 60 nm: 20%; TMAH: 2%; MEA: 15%; JFCE: 0.05%; the balance is deionized water.

[0053] Polishing conditions: Same as Example 1

[0054] Example 10

[0055] Polishing liquid ratio:

[0056] Silica sol abrasive with a particle size of 60 nm: 20%; TMAH: 2%; DEA: 10%; JFCE: 0.05%; the balance is deionized water.

[0057] Polishing conditions: Same as Example 1

[0058] Embodiment 11

[0059] Polishing liquid ratio:

[0060] Silica sol abrasive with a particle size of 60 nm: 20%; TMAH: 2%; TEA: 10%; JFCE: 0.05%; the balance is deionized water.

[0061] Polishing conditions: Same as Example 1

[0062] Table 1 is the relevant formula of Examples 1-11 in this application; Table 2 gives the test results of multiple polishing of different embodiments.

[0063] Table 1:

[0064]

[0065] Table 2: Polishing test results

[0066]

[0067] Example 12

[0068] In this embodiment, based on the embodiment 6, the type of pH adjuster A is changed, and tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, and 1-adamantyltrimethylammonium hydroxide are used instead of TMAH.

[0069] Embodiment 13

[0070] In this embodiment, based on the embodiment 6, the type of pH adjuster B is changed, and monoisopropanolamine, diisopropanolamine, N-methyldiethanolamine, N-ethyldiethanolamine or a mixture of monoethanolamine and triethanolamine (mixed in a mass ratio of 1:1) is used to replace MEA.

[0071] Embodiment 14

[0072] In this embodiment, on the basis of embodiment 6, a chelating agent is added: one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentaethylenephosphonic acid, and salts thereof, with a mass ratio of 0.2%.

[0073] Embodiment 15

[0074] In this embodiment, based on the embodiment 6, the type of surfactant is changed, and AEO-3, AEO-7, and AEO-9 are used to replace JFCE.

[0075] After testing, the removal rate of the polishing liquid in Example 12, Example 13, Example 14 and Example 15 of the present invention is above 0.9μm / min. The removal rate after eight cycles of use is still above 0.8μm / min, and the attenuation rate is controlled within 8%, which can achieve multiple cycles of use at a high removal rate.

[0076] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A recyclable silicon wafer chemical mechanical polishing liquid, comprising a silica sol abrasive, a surfactant, and deionized water, characterized in that: the polishing liquid also comprises a pH adjuster A and a pH adjuster B, and the components are respectively as follows by mass percentage: silica sol abrasive: 15-25%; the mass content of the pH adjuster B is: 10%-15%; the mass content of the pH adjuster A is: 1%-3%; the mass content of the surfactant is: 0.05%-0.08%; the balance is deionized water; The surfactant is any one of JFCE, AEO-3, AEO-7, and AEO-9; The pH adjuster A is at least one of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, and 1-adamantyltrimethylammonium hydroxide; The pH adjuster B is at least one of monoethanolamine (MEA), monoisopropanolamine, diethanolamine (DEA), diisopropanolamine, triethanolamine (TEA), N-methyldiethanolamine, and N-ethyldiethanolamine; The abrasive particle size of the silica sol abrasive is 60nm; The removal rate of the polishing liquid is above 0.9μm / min, and the removal rate after eight cycles of use is still above 0.8μm / min; the attenuation rate is 4.3%-5.4%, and the qualified rate is 100%; the polishing conditions used are: machine: Universal-150B; polishing head / polishing disc speed: 87 / 93rpm; pressure: 3psi; flow rate 150ml / min; polishing time: 30min; the polishing liquid is diluted with deionized water during use, and the dilution ratio of the polishing liquid to deionized water is 1:

20.

2. The recyclable silicon wafer chemical mechanical polishing solution according to claim 1, characterized in that: A chelating agent is also added to the polishing liquid, and the chelating agent is one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentaethylenephosphonic acid and their salts.

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