CN101972753A - Method for cleaning surface of magnesium aluminum alloy subjected to chemically mechanical polishing - Google Patents

Abstract

The invention discloses a surface cleaning method after magnesium-aluminum alloy chemical mechanical polishing, and aims to provide a method that can reduce the subsequent processing cost of magnesium-aluminum alloy material alkaline chemical mechanical polishing, has a simple and easy application method, and can improve the surface quality of wafers cleaning method. Take ultrapure water with a resistance of 18MΩ or more and add non-ionic surfactant and FA/O chelating agent while stirring; use ultrapure water with a resistance of 18MΩ or more to dilute the corrosion inhibitor; add the diluted corrosion inhibitor while stirring into the above-mentioned liquid, stir evenly to obtain a water-soluble surface cleaning solution, and use the obtained water-soluble surface cleaning solution to quickly polish and clean the magnesium-aluminum alloy material after alkaline chemical mechanical polishing under the condition of large flow and low pressure; The ultrapure water above 18MΩ is flushed under the condition of zero pressure and large flow.

Description

Surface cleaning method of magnesium alloy after chemical mechanical polishing

technical field

The invention relates to a method for cleaning the surface of a magnesium-aluminum alloy after chemical mechanical polishing.

Background technique

Magnesium-aluminum alloys are strategically important metals. Magnesium-aluminum alloys are widely used in aerospace products, such as aircraft landing wheels, gearbox covers, and helicopter horizontal rotor accessories. With the continuous improvement of magnesium-aluminum alloy smelting and manufacturing technology, aluminum-magnesium alloys are also widely used in tank armor parts, missile shells and empennages in the defense industry. Especially in some planar devices, such as flyers, samples and other key or important components, it is necessary to achieve ultra-precise planarization processing with extremely high precision and nearly no defects. These requirements have reached the limit of the current single mechanical cutting or grinding and polishing processing capabilities, and have increasingly become one of the "bottlenecks" restricting the further development of related fields.

Chemical-mechanical polishing (CMP) can truly achieve global planarization of magnesium-aluminum alloys, resulting in better surfaces and higher removal rates. However, both magnesium and aluminum are very active metals. If protective measures are not taken in time after CMP, the surface of magnesium-aluminum alloy is prone to corrosion, which is manifested by a rapid increase in corrosion pits, thereby destroying the surface of the polished magnesium-aluminum alloy. Therefore Research on the chemical-mechanical polishing (CMP) technology and post-polishing treatment technology of magnesium-aluminum alloy has become an important problem to be solved urgently.

As one of the surface treatment technologies, the surface cleaning technology after polishing is particularly important. At present, the surface of magnesium-aluminum alloy is cleaned by washing with water. Due to the high temperature, high energy and high surface tension of the wafer surface, although the polishing has stopped, the reaction on the wafer surface has a lagging process, and it will be easy in the air. Oxidation, simple water washing can not avoid the phenomenon of uneven distribution of polishing liquid, contamination of metal ions, etc., resulting in uneven fog, high roughness, uneven corrosion, etc. on the surface of the wafer after cleaning. On the 8-inch chip, the grain There are more than 1,000 particles with a diameter greater than 0.1 micron, which seriously affects the surface quality of the wafer, resulting in an increase in the cost of subsequent processing and a decrease in the precision of the device.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a cleaning method capable of reducing the subsequent processing cost of alkaline chemical mechanical polishing of magnesium-aluminum alloy materials, simple and easy to use, and capable of improving the surface quality of wafers.

The present invention realizes through following technical scheme:

A method for cleaning the surface of a magnesium-aluminum alloy after chemical mechanical polishing, is characterized in that it comprises the following steps:

(1) get resistance and add nonionic surfactant and FA/O chelating agent while stirring the ultrapure water more than 18MΩ;

(2) Dilute the corrosion inhibitor with ultrapure water with a resistance of 18MΩ or more;

(3) join the diluted corrosion inhibitor in the liquid that step (1) obtains while stirring, obtain water-soluble surface cleaning liquid after stirring evenly, in the water-soluble surface cleaning liquid that obtains, the weight of nonionic surfactant The percentage is 1-5%, the weight percentage of FA/O chelating agent is 0.1-5%, the corrosion inhibitor is 0.01-5%, and the remaining resistance is ultrapure water above 18MΩ;

(4) Use the water-soluble surface cleaning solution obtained in step (3) to quickly perform alkaline chemical mechanical polishing on the magnesium-aluminum alloy material using a large flow rate of 1000-5000ml/min under a low pressure condition of 0-0.01 atmosphere. Polishing and cleaning, the time of polishing and cleaning is 30s-3min;

(5) Rinse the magnesium-aluminum alloy material cleaned in step (4) for 30s-3min with ultra-pure water with a resistance of 18MΩ or more under the condition of zero pressure and high flow rate of 1000-4000ml/min.

Among them, zero pressure means that the pressure on the pressure gauge is zero, only the self-weight pressure of the polishing disc. The 0.01 atmospheric pressure in the low pressure of 0-0.01 atmospheric pressure means that the value on the pressure gauge is 0.01 atmospheric pressure, excluding the self-weight pressure. It is equivalent to the pressure of 2000Pa-12000Pa.

The nonionic surfactant is FA/O type I surfactant, O _π -7((C ₁₀ H ₂₁ -C ₆ H ₄ -O—CH ₂ CH ₂ O) ₇ -H), O _π -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), any of JFC. Among them, the FA/OI surfactant is a commercially available product from Tianjin Jingling Microelectronics Materials Co., Ltd.

The FA/O chelating agent is a commercially available product of Tianjin Jingling Microelectronics Materials Co., Ltd., and its name is ethylenediaminetetraacetic acid tetrakis(tetrahydroxyethylethylenediamine), which can be abbreviated as NH ₂ RNH ₂ , and its structural formula is as follows,

The corrosion inhibitor is benzotriazole or hexamethylenetetramine (urotropine).

The present invention has following technical effect:

(1) The cleaning method of the present invention immediately uses a water-soluble surface cleaning solution containing non-ionic surfactants, chelating agents, corrosion inhibitors, etc. to carry out high-flow polishing and cleaning after the alkaline polishing has just been completed, and can quickly remove the residues on the wafer surface. Clean and perfect polishing surface can be obtained. Moreover, the heat brought out by the large flow of cleaning makes the temperature distribution of each part of the wafer consistent, and the temperature consistency is good, preventing uneven corrosion and improving uniformity, thereby reducing the subsequent The cost of processing is low, the yield of devices is improved, and the use is convenient and simple. Moreover, the cost of the water-soluble surface cleaning solution is low, and does not pollute the environment and corrode equipment.

2. in the cleaning method of the present invention, clean with water-soluble surface cleaning solution, wherein, the selected nonionic surfactant can reduce the high surface tension of the wafer surface after polishing rapidly, reduce the damage layer, and improve the uniformity of the wafer surface quality The chelating agent can react with the metal ions remaining on the wafer surface to generate a soluble macromolecular chelate, which is detached from the wafer surface under the action of a large flow of aqueous solution; the corrosion inhibitor can form a monomolecular passivation film on the wafer surface after polishing, Prevent the uneven distribution of the polishing liquid on the wafer surface from reacting with the substrate to form uneven corrosion, and improve the perfection of the polished wafer surface. Using the method of the invention can improve the surface quality of the wafer, reduce the cost of subsequent processing, and increase the device yield.

3. The method of the present invention is carried out under low pressure, which can make the water-soluble surface cleaning liquid fully contact with the cleaning surface, and effectively take away the pollutants cleaned from the surface under the action of the large-flow water-soluble surface cleaning liquid at the same time, thereby improving surface cleaning. Quality; if the pressure is too large, it will cause friction on the surface, which will affect the quality of the polished surface.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments.

Example 1:

(1) Take 3645g of ultrapure water with a resistance of more than 18MΩ, and put in 100g of FA/O Type I surfactant and 50g of FA/O chelating agent while stirring.

(2) Weighing 5g of phenylacryltriazole is diluted with 200g of ultrapure water with a resistance of 18MΩ or more and poured into the liquid of step (1) while stirring, to obtain a magnesium-aluminum alloy water-soluble surface cleaning solution after stirring evenly.

(3) Use the water-soluble surface cleaning solution obtained in step (2) to immediately polish and clean the magnesium-aluminum alloy material after alkaline chemical mechanical polishing for 2 minutes under the condition of zero pressure (self-weight pressure) at a flow rate of 1000ml/min.

(4) Rinse the magnesium-aluminum alloy material cleaned in step (3) for 30 seconds with ultrapure water with a resistance of more than 18MΩ under zero pressure (self-weight pressure) and a flow rate of 1000ml/min, and obtain the magnesium-aluminum alloy wafer surface Smooth and non-etching pattern, the surface roughness can reach 3nm level, on the 8-inch chip, there are less than 10 particles with a particle size larger than 0.1 micron.

Example 2:

(1) Take 3400g of ultrapure water with a resistance of 18MΩ or more, and put in 100g of JFC and 50g of FA/O chelating agent while stirring.

(2) 250g of hexamethylenetetramine is diluted with 200g of ultrapure water with a resistance of 18MΩ or more and poured into the liquid of step (1) while stirring, and the magnesium-aluminum alloy water-soluble surface cleaning solution is obtained after stirring.

(3) Using the water-soluble surface cleaning solution obtained in step (2), use the flow rate of 4000ml/min to immediately polish and clean the magnesium-aluminum alloy material after alkaline chemical mechanical polishing for 30s under the condition of 0.01 atmospheric pressure (excluding self-weight pressure) .

(4) Rinse the magnesium-aluminum alloy material cleaned in step (3) for 30 seconds with ultra-pure water with a resistance of more than 18MΩ under the condition of zero pressure (self-weight pressure) and a flow rate of 4000ml/min, and obtain the surface of the magnesium-aluminum alloy wafer Smooth and non-etching pattern, the surface roughness reaches 3.2nm level. On an 8-inch chip, there are fewer than 10 particles larger than 0.1 micron in size.

Claims (3)

1. a magnadure chemically mechanical polishing rear surface cleaning method is characterized in that, comprises the steps:

(1) the power taking resistance adds non-ionic surface active agent and FA/O chelating agent while stirring for the above ultra-pure water of 18M Ω;

(2) adopting resistance is the above ultra-pure water dilution corrosion inhibitor of 18M Ω;

(3) corrosion inhibitor after will diluting joins in the liquid that step (1) obtains while stirring, obtain water-soluble surface cleaning liquid after stirring, in the water-soluble surface cleaning liquid that obtains by weight percentage: non-ionic surface active agent is 1-5%, the FA/O chelating agent is 0.1-5%, corrosion inhibitor is 0.01-5%, and surplus is that resistance is the above ultra-pure water of 18M Ω;

(4) use the water-soluble surface cleaning liquid that obtains in the step (3) to adopt the big flow of 1000-5000ml/min under 0-0.01 atmospheric low pressure conditions, to carry out polished and cleaned, the time 30s-3min of polished and cleaned to the magnesium-aluminium alloy material behind the alkaline chemical mechanical polishing rapidly;

(5) be that the above ultra-pure water of 18M Ω is the magnesium-aluminium alloy material flushing 30s-3min after under the big flow condition of 1000-4000ml/min step (4) being cleaned at zero pressure, flow with resistance.

2. magnadure chemically mechanical polishing according to claim 1 rear surface cleaning method is characterized in that described non-ionic surface active agent is FA/OI type surfactant, O _π-7, O _π-10, any among O-20, the JFC.

3. magnadure chemically mechanical polishing according to claim 1 rear surface cleaning method is characterized in that described corrosion inhibitor is phenylpropyl alcohol triazole or hexa.