Abrasive-free alkaline copper fine polishing liquid for copper wiring of integrated circuit and preparation method of abrasive-free alkaline copper fine polishing liquid

Abstract

The invention relates to the technical field of chemical mechanical polishing, and particularly discloses an abrasive-free alkaline copper fine polishing solution for integrated circuit copper wiring and a preparation method of the abrasive-free alkaline copper fine polishing solution. The alkalescent abrasive-free copper fine polishing liquid prepared by utilizing the macromolecular chelating agent has a better dish pit correction effect under the conditions of low pressure, no corrosion inhibitor and no abrasive, and the macromolecular chelating agent can enhance the chemical effect of the polishing liquid and reduce the dosage of the abrasive and the corrosion inhibitor; and the polishing solution does not contain abrasive particles, so that the problems of surface particle pollution, pipeline blockage, surface scratch and the like caused by instability and easiness in agglomeration of the abrasive in the polishing solution are thoroughly solved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical mechanical polishing, in particular to an abrasive-free alkaline copper polishing liquid for integrated circuit copper wiring and a preparation method thereof. Background Art

[0002] The function of copper fine polishing liquid is to remove the copper material on the barrier layer at a fast rate, and at the same time, the polishing end point is required to stop on the barrier layer, which requires the copper fine polishing liquid to have a high copper / barrier layer high polishing rate ratio. In order to ensure the complete removal of the metal copper on the barrier layer, a certain period of over-polishing is required, which leads to copper corrosion in the metal line, thereby generating a dished pit. The traditional method of controlling the extension of the dished pit is: adding corrosion inhibitor benzotriazole (BTA) and its derivatives to the fine polishing liquid to produce an organic passivation film to protect the copper material in the line from chemical corrosion, and the copper material on the barrier layer relies on the strong mechanical action provided by the abrasive to obtain a high polishing rate. However, the abrasive is unstable in the polishing liquid and is prone to agglomeration, so a dispersant needs to be added; after CMP, the abrasive particles can be adsorbed on the surface of the copper line to cause particle pollution; at the same time, it is easy to adhere to the surface of the ground, pipes, barrels and polishing machines, etc., causing problems such as ultra-clean room pollution and pipe blockage; the most important thing is that the abrasive hardness is too high, the particle size distribution is uneven, and it is easy to gel, which is the main cause of scratches on the surface of the copper line, and a filtration and stirring system needs to be introduced to filter out large particles. In addition, BTA and its derivatives are toxic and expensive, which increases the manufacturing cost, and the organic passivation film formed is difficult to clean. The future development direction of copper polishing liquid is: mainly based on chemical action, low pressure, weak alkalinity, no abrasive and no corrosion inhibitor polishing.

[0003] Abrasive-free polishing mainly relies on chemical action to increase the polishing rate. When the chemical action of the polishing liquid is enhanced, the corrosion rate of the copper material inside the line will also increase, resulting in the extension of the dished pit. The traditional planarization method adds BTA and its derivatives to form an organic passivation film, and relies on abrasives to provide strong mechanical force to remove the passivation film, thereby increasing the copper polishing rate on the barrier layer, while the copper surface passivation film inside the line still exists, inhibiting the copper chemical corrosion and controlling the extension of the dished pit. For abrasive-free polishing liquid, the mechanical force is weak, and the organic passivation film on the copper surface of the barrier layer cannot be effectively removed. The presence of the passivation film hinders the progress of the chemical reaction, resulting in the corrosion inhibitor simultaneously inhibiting the chemical reaction of the copper on the barrier layer and the copper inside the line, and planarization cannot be achieved. Therefore, how to solve the problem of increasing the chemical action of abrasive-free alkaline polishing liquid while inhibiting the chemical corrosion of copper inside the line is the main bottleneck restricting its wide application. Therefore, the present invention uses a macromolecular chelating agent to configure an abrasive-free alkaline copper fine polishing liquid, which can control the extension of the dished pit under the condition of no corrosion inhibitor. Summary of the invention

[0004] The purpose of the present invention is to provide an abrasive-free alkaline copper polishing liquid for integrated circuit copper wiring and a preparation method thereof to solve the problems raised by the above-mentioned background technology in view of the defects of the prior art.

[0005] To achieve the above object, the present invention provides the following technical solution: an abrasive-free alkaline copper polishing liquid for integrated circuit copper wiring, the polishing liquid comprising the following components by mass percentage: 0.2-2% of a macromolecular chelating agent, 0.2-1.0% of an activating agent, 0.05-1% of hydrogen peroxide, 0.1-4% of a pH regulator for adjusting the pH to 8-10, and the remainder being deionized water;

[0006] The macromolecular chelating agent has a molecular weight of 1000-10000 g / mol.

[0007] As a preferred technical solution of the present invention, the pH regulator is potassium hydroxide.

[0008] As a preferred technical solution of the present invention, the active agent is fatty alcohol polyoxyethylene ether.

[0009] As a preferred technical solution of the present invention, the oxidant is hydrogen peroxide.

[0010] As a preferred technical solution of the present invention, the macromolecular chelating agent is selected from one or more monomers of tris(2-hydroxyethyl)ammonium ethylenediaminetetraacetate, trisodium salt of hydroxyethylethylenediaminetriacetate, 1,2,3,4,5,6-[hexa-(2-methylamine oxime)ethoxy]hexane, tetrahydroxyethylethylenediaminetetraacetic acid salt, sodium polyacrylate, maleic acid-acrylic acid copolymer, and acrylic acid-acrylate-sulfonate terpolymer.

[0011] A method for preparing an abrasive-free alkaline copper polishing liquid for integrated circuit copper wiring comprises the following specific steps: taking deionized water, adding fatty alcohol polyoxyethylene ether and hydrogen peroxide in succession with stirring, adjusting the pH value to 8-10 with potassium hydroxide, adding a macromolecular chelating agent with stirring, stirring evenly, adding deionized water to make up the required weight, and continuing to stir evenly to obtain a polishing liquid.

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

[0013] (1) Under weak alkaline conditions without abrasives or corrosion inhibitors, copper polishing liquid effectively controls the extension of dishing pits;

[0014] (2) There are no abrasive particles in the polishing liquid, which completely solves the problems of abrasive being unstable in the polishing liquid and easily agglomerated, causing particle contamination on the surface, pipe blockage, surface scratches, etc.

[0015] (3) There is no corrosion inhibitor in the polishing liquid, and chemical action is the main method. Low-pressure polishing solves the problem that the corrosion inhibitor passivation film is not conducive to post-CMP cleaning, requires strong mechanical force to remove, and damages the structure of the ultra-low-k dielectric material;

[0016] (4) The polishing liquid has simple ingredients, low cost, is environmentally friendly and easy to produce and transport. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a control comparison diagram of different fine polishing liquids in Example 1 of the present invention;

[0018] Figure 2 This is a control comparison diagram of different fine polishing liquids in Example 2 of the present invention;

[0019] Figure 3 This is a control comparison diagram of different fine polishing liquids in Example 3 of the present invention; DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0021] Example 1: A method for preparing an abrasive-free alkaline copper polishing solution for integrated circuit copper wiring; the specific steps are as follows:

[0022] Prepare 1000g of fine polishing liquid: take 500ml of deionized water, stir and add 5g of fatty alcohol polyoxyethylene ether and 8ml of hydrogen peroxide successively, adjust the pH to 8.9 with potassium hydroxide, stir and add 10g of macromolecular chelating agent sodium polyacrylate, the molecular weight of sodium polyacrylate is 1000g / mol, stir evenly and make up to 1000g with deionized water, continue to stir evenly to obtain fine polishing liquid A; take 500ml of deionized water, stir and add 5g of fatty alcohol polyoxyethylene ether and 80ml of hydrogen peroxide successively, adjust the pH to 8.9 with potassium hydroxide, stir and add 10g of ethylenediamine, stir evenly and make up to 1000g with deionized water, continue to stir evenly to obtain fine polishing liquid B.

[0023] Test: Use the configured fine polishing liquid A and B in the French Alpsitec-E460E polishing machine; working pressure: 1.0psi; polishing disc speed 85 rpm; polishing head speed 95 rpm; polishing flow 300ml / min. Polishing the 300mm graphic piece for 1min and over-polishing time 15s. Before polishing, the graphic piece is uniformly flattened with commercial rough polishing liquid. After rough polishing, the initial surface copper film thickness is about 200nm, and then fine polishing is performed. After polishing and cleaning, the dish pit value after polishing is tested with a step meter. The results are as follows Figure 1 As shown;

[0024] Example 1 shows that, compared with small molecule ethylenediamine, the abrasive-free and corrosion inhibitor-free alkaline copper polishing liquid configured by the present invention can effectively control the extension of the dishing pit.

[0025] Example 2: A method for preparing an abrasive-free alkaline copper polishing solution for integrated circuit copper wiring; the specific steps are as follows:

[0026] Prepare 1000g of fine polishing liquid: take 500ml of deionized water, stir and add 5g of fatty alcohol polyoxyethylene ether and 8ml of hydrogen peroxide successively, adjust the pH to 8.9 with potassium hydroxide, stir and add 10g of macromolecular chelating agent sodium polyacrylate, the molecular weight of sodium polyacrylate is 5000g / mol, stir evenly, make up to 1000g with deionized water, continue to stir evenly to obtain fine polishing liquid A; take 500ml of deionized water, stir and add 5g of fatty alcohol polyoxyethylene ether and 8ml of hydrogen peroxide successively, adjust the pH to 8.9 with potassium hydroxide, stir and add 8g of glycine, stir evenly, make up to 1000g with deionized water, continue to stir evenly to obtain fine polishing liquid C.

[0027] Test: Use the configured fine polishing liquid A and C in the French Alpsitec-E460E polishing machine; working pressure: 1.0psi; polishing disc speed 85 rpm; polishing head speed 95 rpm; polishing flow 300ml / min. Polishing the 300mm graphic piece for 1min and over-polishing time 15s. Before polishing, the graphic piece is uniformly flattened with commercial rough polishing liquid. After rough polishing, the initial surface copper film thickness is about 200nm, and then fine polishing is performed. After polishing and cleaning, the dish pit value after polishing is tested with a step meter; the results are as follows Figure 2 shown.

[0028] Example 2 shows that, compared with small molecule glycine, the abrasive-free and corrosion inhibitor-free alkaline copper polishing liquid configured by the present invention can effectively control the extension of the dishing pit.

[0029] Example 3: A method for preparing an abrasive-free alkaline copper polishing solution for integrated circuit copper wiring; the specific steps are as follows:

[0030] Prepare 1000g of fine polishing liquid: take 500ml of deionized water, stir and add 5g of fatty alcohol polyoxyethylene ether and 8ml of hydrogen peroxide successively, adjust the pH to 8.9 with potassium hydroxide, stir and add 10g of macromolecular chelating agent sodium polyacrylate, the molecular weight of sodium polyacrylate is 10000g / mol, stir evenly and make up to 1000g with deionized water, continue to stir evenly to obtain fine polishing liquid A; take 500ml of deionized water, stir and add 5g of fatty alcohol polyoxyethylene ether and 8ml of hydrogen peroxide successively, adjust the pH to 8.9 with potassium hydroxide, stir and add 20g of ethylenediaminetetraacetic acid, stir evenly and make up to 1000g with deionized water, continue to stir evenly to obtain fine polishing liquid D.

[0031] Test: Use the configured fine polishing liquid A and D in the French Alpsitec-E460E polishing machine; working pressure: 1.0psi; polishing disc speed 85 rpm; polishing head speed 95 rpm; polishing flow 300ml / min. Polishing the 300mm graphic piece for 1min and over-polishing time 15s. Before polishing, the graphic piece is uniformly flattened with commercial rough polishing liquid. After rough polishing, the initial surface copper film thickness is about 200nm, and then fine polishing is performed. After polishing and cleaning, the dish pit value after polishing is tested with a step meter; the results are as follows Figure 3 shown.

[0032] Example 3 shows that, compared with the small molecule ethylenediaminetetraacetic acid, the alkaline copper polishing liquid without abrasive and corrosion inhibitor configured by the present invention can effectively control the extension of the dishing pit.

[0033] Examples 1-3 illustrate that the present invention provides an abrasive-free alkaline copper polishing liquid for integrated circuit copper wiring, which is mainly based on chemical action. The polishing liquid is mainly based on chemical action and can effectively control the extension of dishing pits without corrosion inhibitors and abrasives.

[0034] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims

1. An abrasive-free alkaline copper polishing liquid for integrated circuit copper wiring, characterized in that: The polishing liquid is composed of the following components by mass percentage: 0.2-2% of macromolecular chelating agent, 0.2-1.0% of active agent, 0.05-1% of hydrogen peroxide, 0.1-4% of pH regulator for adjusting pH to 8-10, and the balance is deionized water; The macromolecular chelating agent has a molecular weight of 1000-10000 g / mol.

2. The abrasive-free alkaline copper polishing liquid for integrated circuit copper wiring according to claim 1, characterized in that: The pH regulator is potassium hydroxide.

3. The abrasive-free alkaline copper polishing liquid for integrated circuit copper wiring according to claim 2, characterized in that: The active agent is fatty alcohol polyoxyethylene ether.

4. The abrasive-free alkaline copper polishing liquid for integrated circuit copper wiring according to claim 3, characterized in that: The oxidant is hydrogen peroxide.

5. The abrasive-free alkaline copper polishing liquid for integrated circuit copper wiring according to claim 4, characterized in that: The macromolecular chelating agent is selected from one or more monomers of tris(2-hydroxyethyl)ammonium ethylenediaminetetraacetate, trisodium hydroxyethylethylenediaminetriacetate, 1,2,3,4,5,6-[hexa-(2-methylamine oxime)ethoxy]hexane, tetrahydroxyethylethylenediaminetetraacetate, sodium polyacrylate, maleic acid-acrylic acid copolymer, and acrylic acid-acrylate-sulfonate terpolymer.

6. A method for preparing an abrasive-free alkaline copper polishing solution for integrated circuit copper wiring according to any one of claims 1 to 5, characterized in that: The specific steps are as follows: take deionized water, add fatty alcohol polyoxyethylene ether and hydrogen peroxide in succession, and adjust the pH to 8-10 with potassium hydroxide, add macromolecular chelating agent with stirring, stir evenly and then add deionized water to make up the required weight, continue to stir evenly to obtain fine polishing liquid.

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