CN104403574A - Compound abrasive polishing solution for sapphire substrate material and recycling method thereof - Google Patents

Abstract

The invention relates to a composite abrasive polishing liquid for sapphire substrate materials, which is characterized in that: its main components are calculated by weight%, including 10-50% of nano- _SiO2 hydrosol with a weight concentration of 2-50wt% and a particle size of 15-150nm %, mixed abrasive 0.1-3%, active agent 0.1-1%, chelating agent 0.5-2%, pH inorganic alkali regulator 0.1-2%. The recycling steps are as follows: the flow rate of the polishing liquid is 100g/min-300g/min, the polishing pressure is 0-0.2MPa, the polishing speed is 40-60rpm, and the polishing temperature is 30-40°C. When the polishing rate is less than or equal to 1.5 microns/hour, the polishing liquid stops circulating use. Beneficial effects: the polishing liquid of the present invention is in the form of composite abrasives, which can effectively improve the polishing removal rate. The method of recycling the polishing liquid not only saves the cost, but also improves the efficiency.

Description

Composite abrasive polishing fluid for sapphire substrate material and recycling method thereof

technical field

The invention belongs to a CMP polishing fluid, in particular to a composite abrasive polishing fluid for a sapphire substrate material and a recycling method thereof.

Background technique

Sapphire single crystal (Sapphire), also known as white gemstone, has a molecular formula of Al ₂ O ₃ , is transparent, has the same optical and mechanical properties as natural gemstones, and has good thermal properties, excellent electrical properties and dielectric properties. And chemical corrosion resistance, high infrared transmittance, good wear resistance, hardness second only to diamond, Ta Mok's 9, still has good stability at high temperatures, melting point is 2030 ° C, so it is It is widely used in industry, national defense, scientific research and other fields, and is increasingly used as a manufacturing material for parts in high-tech fields such as solid-state lasers, infrared windows, substrates for semiconductor chips, and precision wear-resistant bearings. The application of GaN, the third-generation semiconductor material, in devices is regarded as the most important event in semiconductors after the 1990s, bringing semiconductor light-emitting diodes (LEDs) and lasers to a new level. However, GaN is difficult to prepare as a host material, and thin films must be grown on other substrate materials. There are many kinds of substrate materials for GaN, including sapphire, silicon carbide, silicon, magnesium oxide, zinc oxide, etc., among which sapphire is the most important substrate material (90%), and high-quality epitaxy has been possible on sapphire. GaN materials, and GaN-based blue light-emitting diodes and laser diodes have been developed.

At present, there are many ultra-precision processing methods for the single crystal surface of sapphire substrates in the world, such as mechanical chemical polishing, laser polishing, magnetic liquid polishing, etc., but chemical mechanical polishing is the most effective method, and the effect is better. With the advancement of energy saving and emission reduction tasks worldwide, the United States, Japan, the European Union and other countries have formulated a series of energy reduction and emission reduction measures. One of the most effective methods is to use cold light sources, that is, LED lights. Our country has also formulated corresponding plans to gradually implement the cold light source plan. Therefore, the demand for sapphire substrates is increasing day by day, but the cost is high due to the low processing rate, the waste of polishing fluid once used, etc., and the problems such as chipping and fragility in the processing process lead to low yields and other problems, resulting in low cost performance. Technology development slows down. Low-cost and high-efficiency surface processing of sapphire crystal for LED substrate material is one of the key factors to improve cost performance. With the increasing demand for sapphire substrate materials and the increasing requirements for surface quality, the surface processing of sapphire substrate Technical research is particularly important.

Contents of the invention

The object of the present invention is to overcome the deficiency of above-mentioned technology, provide a kind of composite abrasive polishing liquid of sapphire substrate material and its recycling method, the polishing liquid adopts the form of composite abrasive, can effectively improve polishing removal rate. The method of recycling the polishing liquid not only saves the cost, but also improves the efficiency. The surface quality of the sapphire substrate material is improved, and the problems of low polishing rate, low efficiency and low cost performance of the sapphire substrate material are solved.

In order to achieve the above object, the present invention adopts the following technical scheme: a composite abrasive polishing liquid for sapphire substrate material, characterized in that: its main components are calculated by weight %, including weight concentration 2-50wt% and particle diameter 15-150nm 10-50% of nano- _SiO2 hydrosol, 0.1-3% of mixed abrasive, 0.1-1% of active agent, 0.5-2% of chelating agent, and 0.1-2% of pH inorganic alkali regulator.

The preparation method of the composite abrasive polishing liquid comprises adding deionized water to dilute 0.1-2% inorganic alkali until it is completely dissolved to make a pH inorganic alkali regulator; stirring 0.1-3% of the mixed abrasive Add nanometer 10-50% _SiO2 hydrosol, then add 42-89.8% deionized water while stirring, then add 0.1-1% active agent, 0.5-2% chelating agent and pH inorganic Alkaline conditioner.

The composite abrasive is one or a mixture of Al ₂ O ₃ and CeO ₂ , and the particle size of the abrasive is the same as that of the SiO ₂ hydrosol.

The active agent is FA/O type I surfactant, O _II -7((C _1O H ₂₁ -C ₆ H ₄ -O-CH ₂ CH ₂ O) ₇ -H), O _II -10((C _1O H ₂₁ -C ₆ H ₄ -O-CH ₂ CH ₂ O) ₁₀ -H), O-20(C _12-18 H _25-37 -C ₆ H ₄ -O-CH ₂ CH ₂ O) ₇₀ -H ), or one or more mixtures of JFC.

The pH regulator is an inorganic base, and the inorganic base is KOH, NaOH or a mixture of the two, and the pH value of the pH regulator is 9-13.

Described chelating agent is FA/O II type chelating agent.

The recycling method of the above sapphire substrate material composite abrasive polishing liquid is based on the law that the removal rate gradually decreases with the increase in the number of polishing times, and the polishing time is set according to the thickness removed according to the process requirements. When the removal rate does not reach the value required by the process, polishing Stop the recycling of the liquid; the specific implementation steps for the recycling of the polishing liquid are as follows: take the prepared polishing liquid 10Kg, the flow rate of the polishing liquid is 100g/min-300g/min, the polishing pressure is 0-0.2MPa, the polishing speed is 40-60rpm, and the polishing temperature is 30 -40°C, when the polishing rate is less than or equal to 1.5 microns/hour, the polishing fluid will stop circulating.

The effect of the technology adopted in the present invention is: the alkaline polishing of the sapphire substrate material has problems such as low polishing rate, low efficiency, waste of polishing liquid for one-time use, and low cost performance. The polishing fluid is in the form of composite abrasives, which can effectively improve the polishing removal rate. The use of surfactants can make the polishing products in a state of physical attachment that is easy to remove, which is beneficial to the removal of surface contaminants and reduces damage. The use of chelating agents can effectively remove the metal ions contaminated in the polishing system, and at the same time play a role in buffering and corrosion inhibition. On the premise of using composite abrasives to increase the removal rate, the method of recycling the polishing liquid is used, which saves costs and improves efficiency.

Beneficial effects: compared with the prior art, the present invention lays a foundation for realizing the low-cost and high-efficiency surface processing of the sapphire crystal of the LED substrate material. especially,

1. The polishing liquid uses composite abrasives, alkaline pH regulators, surfactants, and chelating agents as the main components, and adopts a recycling method, which can improve polishing efficiency, improve surface roughness, have no corrosion to equipment, and can greatly reduce cost.

2. The selection of composite abrasives can effectively improve the polishing removal rate.

3. The selection of surfactant can make the adsorbate on the polishing surface easy to clean in a physical adsorption state, which is beneficial to the removal of surface contaminants, while reducing the damaged layer and improving the uniformity of the wafer surface quality;

3. The selected chelating agent can react with the metal ions remaining on the surface of the chip to form a soluble macromolecular chelate, which can be detached from the surface of the chip with a small amount of action, and can play the role of buffer and corrosion inhibition at the same time.

4. Choose the method of recycling the polishing liquid, which can greatly reduce the cost while ensuring the polishing quality.

Detailed ways

The specific implementation of the present invention will be described in detail below in conjunction with preferred embodiments.

Example 1

Prepare 10kg composite abrasive polishing fluid for sapphire substrate material and use it for circular polishing

Take 5000g particle size 150nm SiO ₂ water sol, add 300g same particle size Al ₂ O ₃ abrasive while stirring, then add in 4150g deionized water while stirring, then add 50g of FA/O I type surfactant respectively while stirring , 100g of FA/O type II chelating agent, 200g of KOH diluted with deionized water and 200g of pH regulator. After stirring evenly, carry out circular polishing, each cycle time is 1 hour, and examine the change of removal rate in each cycle. Pressure: 0.12Mpa; Speed: 60rpm; Flow: 300ml/min. The results are: the removal rate of the first cycle is 7.85 μm/h, the removal rate of the second cycle is 5.72 μm/h, and the removal rate of the third cycle is 3.065 μm/h.

Example 2

Prepare 10kg composite abrasive polishing fluid for sapphire substrate material and use it for circular polishing

Get 2500g particle diameter 80nm SiO ₂ water sol, add 150g _same particle diameter CeO while stirring Abrasive, then add in the deionized water 6850g while stirring, add FA/OI type surfactant 100g, FA respectively while stirring afterwards /O Type II chelating agent 200g, KOH100g pH regulator diluted with 200g deionized water. After stirring evenly, carry out circular polishing, each cycle time is 1 hour, and examine the change of removal rate in each cycle. Pressure: 0.10Mpa; Speed: 60rpm; Flow: 200ml/min. The results are: the removal rate of the first cycle is 7.615 μm/h, the removal rate of the second cycle is 4.885 μm/h, and the removal rate of the third cycle is 2.935 μm/h.

Example 3

Prepare 10kg composite abrasive polishing fluid for sapphire substrate material and use it for circular polishing

Take 1000g of SiO ₂ water sol with a particle size of 15-20nm, add 10g of Al ₂ O ₃ abrasive with the same particle size while stirring, then add it into 8720g of deionized water while stirring, and then add FA/O Type I surface active Agent 10g, FA/O I type I chelating agent 50g, 200g deionized water diluted KOH 10g pH adjuster. After stirring evenly, carry out circular polishing, each cycle time is 1 hour, and examine the change of removal rate in each cycle. Pressure: 0.08Mpa; Speed: 60rpm; Flow: 300ml/min. The results are: the removal rate of the first cycle is 6.615 μm/h, the removal rate of the second cycle is 4.53 μm/h, and the removal rate of the third cycle is 2.335 μm/h.

Described chelating agent FA/O type II chelating agent, active agent FA/O type I surfactant are commercially available products of Tianjin Jingling Microelectronics Material Co., Ltd.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the structure of the present invention in any form. All simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solutions of the present invention.

Claims (7)

1. a kind of composite abrasive polishing liquid of sapphire substrate material is characterized in that: its main component is by weight %, comprises the nano _- SiO of weight concentration 2-50wt% and particle diameter 15-150nm Hydrosol 10-50% , mixed abrasive 0.1-3%, active agent 0.1-1%, chelating agent 0.5-2%, pH inorganic alkali regulator 0.1-2%. 2. the composite abrasive polishing liquid of sapphire substrate material according to claim 1 is characterized in that: the preparation method of described composite abrasive polishing liquid, by weight %, adds deionized water in 0.1-2% inorganic alkali Dilute until fully dissolved to make a pH inorganic alkali regulator; add 0.1-3% of the mixed abrasive into the nanometer 10-50% _SiO2 hydrosol while stirring, then add 42-89.8% of deionized water while stirring, and then While stirring, 0.1-1% active agent, 0.5-2% chelating agent and pH inorganic alkali regulator are sequentially added. 3. the composite abrasive polishing liquid of sapphire substrate material according to claim 1, is characterized in that: described composite abrasive is Al ₂ O ₃ , _CeO One or two kinds of mixing, abrasive particle diameter and SiO ₂ The particle size of the hydrosol is the same. 4. the composite abrasive polishing liquid of sapphire substrate material according to claim 1, is characterized in that: described active agent is FA/O I type surfactant, O _II -7 ((C ₁₀ H ₂₁ -C ₆ H ₄ -O-CH ₂ CH ₂ O) ₇ -H), O _II -10((C ₁₀ H ₂₁ -C ₆ H ₄ -O-CH ₂ CH ₂ O) ₁₀ -H), O-20(C _{12 -18} H _25-37 -C ₆ H ₄ -O-CH ₂ CH ₂ O) ₇₀ -H), or one or more mixtures of JFC. 5. the composite abrasive polishing liquid of sapphire substrate material according to claim 1, is characterized in that: described pH adjusting agent is inorganic alkali, and inorganic alkali is the mixing of one or both of KOH, NaOH, and described pH adjustment The pH of the agent is 9-13. 6. the composite abrasive polishing liquid of sapphire substrate material according to claim 1, is characterized in that: described chelating agent is FA/O II type chelating agent. 7. A method for recycling the sapphire substrate material composite abrasive polishing fluid according to claim 1, characterized in that: according to the law that the removal rate gradually decreases with the increase of the number of times of polishing, the polishing time is set according to the thickness removed by the process requirements , when the removal rate does not reach the required value of the process, the recycling of the polishing solution is stopped; the specific implementation steps of the recycling of the polishing solution are as follows: take the prepared polishing solution 10Kg, the flow rate of the polishing solution is 100g/min-300g/min, and the polishing pressure is 0 -0.2MPa, the polishing speed is 40-60rpm, the polishing temperature is 30-40°C, when the polishing rate is less than or equal to 1.5 microns/hour, the polishing liquid will stop circulating.