CN1164724C - Aqueous cleaning liquid composition for post-chemical mechanical planarization - Google Patents

Abstract

The invention relates to an aqueous cleaning solution composition for chemical mechanical planarization, which has a pH value of 2-6, and comprises 1-10 wt% of organic acid, 0.01-0.5 wt% of corrosion inhibitor, 0.01-2 wt% of alcohol amine, 0.01-2 wt% of polyol compound and water. The aqueous cleaning solution composition of the present invention can effectively remove the pollutants such as abrasive particles, metal complexes or organic molecules remained on the surface of the copper process silicon wafer after chemical mechanical planarization, and can not cause the metal wire to generate corrosion.

Description

Aqueous cleaning fluid composition for use after chemical mechanical planarization

The present invention relates to the use of a cleaning liquid composition with a specific chemical composition in the follow-up process of semiconductors to effectively remove the pollutants on the surface of the copper process silicon wafer after chemical mechanical planarization, so as to facilitate subsequent processes such as film deposition and lithography. conduct.

Regarding semiconductor components, they are now developing towards smaller line widths and higher integration densities. When the minimum line width of integrated circuits is reduced to below 0.25 microns, the time delay caused by the resistance of the metal wire itself and the parasitic capacitance of the dielectric layer (RC delay) has become the main key affecting the operation speed of components. Therefore, in order to improve the operation speed of components, copper metal wires with low dielectric coefficient (low k dielectric) have been used in this field to replace traditional aluminum-copper alloys. wire.

Applying chemical mechanical planarization (CMP) technology to the copper metal wire process can not only overcome the problem of difficult pattern definition due to the difficulty of copper metal etching, but also provide a global planarity plane after grinding , easy to carry out multi-layer wiring process. The principle of chemical mechanical planarization is to use the abrasive particles in the polishing liquid to cooperate with chemical additives to cause mechanical abrasion on the surface of the wafer, thereby achieving a high removal rate due to high pressure on the uneven surface , the lower part of the surface unevenness has a slower removal rate due to less pressure, and then achieves the purpose of global planarization.

During the chemical mechanical polishing (CMP) grinding process, a large number of fine grinding particles and chemical additives in the grinding liquid, as well as debris peeled off during the grinding process, may adhere to the wafer surface. Generally, the common pollutants after wafer grinding are metal ions, organic compounds or abrasive particles. If there is no effective cleaning procedure to remove the above pollutants, it will affect the subsequent process and reduce the excellent rate and reliability of the components. Therefore, CMP After grinding, the cleaning process has become a key technology for the successful application of CMP to semiconductor processes.

The main principle of the cleaning technology after chemical mechanical planarization is to use a polyvinyl alcohol (PVA) brush to remove fine dust on the wafer surface, etch the wafer surface to remove metal contamination on the surface layer, and dissolve specific pollutants by acid solution.

The RCA cleaning method is often used after chemical mechanical planarization, which uses a cleaning solution composition called SC-1, including 28% ammonium hydroxide, 30% hydrogen peroxide, and deionized water (1:1:5 ratio) , to remove organic and metal ion contaminants on the wafer surface, and to remove oxide layer etch residues, etc. After SC-1 cleaning, continue to use SC-2 cleaning solution composition, including 30% hydrogen peroxide, 37% hydrochloric acid and deionized water (ratio 1:1:5), for further treatment to remove the remaining metal contaminants.

The function of the hydrogen peroxide in the above method is to produce a protective oxide layer on the wafer surface, so as to prevent the wafer from being corroded by strong acid or strong alkali in the solution. However, it is often necessary to use hydrofluoric acid solution or steam to remove the oxide layer after cleaning. In addition, hydrogen peroxide is easy to decompose itself in the solution, resulting in a decrease in effective concentration. This is the shortcoming of the RCA cleaning method.

The current improved method in the market is to replace the hydrogen peroxide with a non-ionic surfactant in the cleaning liquid composition, and adjust the pH value between 8 and 10 (as disclosed in US Patent No. 5,466,389). Or add a water-based, metal-ion-free substrate and an amphoteric surfactant to the cleaning solution to replace hydrogen peroxide (as disclosed in Chinese Taiwan Patent No. 88698). Although the cleaning composition disclosed in the above-mentioned patent can allow the wafer to obtain a smooth surface after cleaning, this type of cleaning composition will produce the problem that the surfactant is adsorbed or remains on the wafer surface after cleaning, although currently available Ozone ultrapure water is used to remove organic residues, but special equipment and steps are required, which increases the complexity of the process in vain.

In order to effectively remove the pollutants on the surface of the copper process silicon wafer after chemical mechanical planarization in the semiconductor follow-up process, so as to facilitate the follow-up process, the inventors of the present application, after extensive research, found that there are some special compositions Aqueous cleaning fluid compositions achieve the objects of the present invention and the results obtained are set forth in the present invention.

The main object of the present invention is to provide an aqueous cleaning liquid composition for chemical mechanical planarization.

Another object of the present invention is to provide an aqueous cleaning solution composition that can effectively remove residues after chemical mechanical polishing without corroding the wafer surface.

The cleaning liquid composition of the present invention has a pH value between 2 and 6, and includes organic acid, corrosion inhibitor, alcohol amine, polyalcohol compound and water.

Fig. 1 is a surface scanning electron microscope (FE-SEM) photograph of the wafer after contamination.

Fig. 2 is a scanning electron microscope (FE-SEM) photograph of the surface of a wafer after being cleaned by the cleaning composition of the present invention.

The invention relates to an aqueous cleaning solution composition for chemical mechanical planarization, the pH value of which is between 2 and 6, including 1-10% by weight of organic acid and 0.01-0.5% by weight of corrosion inhibitor , 0.01-2% by weight of alcohol amine, 0.01-2% by weight of polyalcohol compounds and water.

The pH value of the aqueous cleaning liquid composition of the present invention is adjusted by nitric acid or ammonia water, and the pH value is between 2-6, preferably 2-3.5.

The organic acid used in the present invention is preferably selected from oxalic acid or citric acid. Its content is 0.5 to 10% by weight, preferably 4 to 8% by weight.

The corrosion inhibitor of the present invention is preferably a triazole compound, more preferably selected from benzotriazole (BTA) or its derivatives, and its content is 0.01-0.5% by weight.

Alcoholamines used in the present invention may be selected from ethanolamine, diethanolamine, triethanolamine and propanolamine. The amount used is 0.01-2% by weight, preferably 0.1-1% by weight.

The polyol compound used in the present invention may be selected from ethylene glycol, 1,3-propanediol and diethylene glycol, and the amount thereof is 0.01-2 wt%, preferably 0.1-1 wt%.

The present invention adds a small amount of alcohol amine and polyol compound to the solution containing organic acid, not only can remove the metal ions deposited on the wafer through the chelation of organic acid, but also remove the residual abrasive particles and organic compounds at the same time and other pollutants. In addition, the cleaning solution of the present invention has a good cleaning effect, and only needs to properly rinse the surface of the wafer at normal temperature. In addition, since the composition of the present invention uses only a very small amount of organic solvent, pollution to the environment can be minimized.

The following examples will further illustrate the present invention and are by no means intended to limit the scope of the present invention. Modifications and changes that can be easily achieved by any person skilled in the art fall within the scope of the present invention.

Example

Experimental procedure

(1) Mix ETERPOL-U6, a commercially available copper process grinding fluid, with hydrogen peroxide at a ratio of 9:1, and add 72ppm of copper nitrate to prepare a contaminated solution.

(2) After immersing the copper chip in the contamination solution for 12 minutes, immerse it in deionized water for 2-3 seconds, then take it out and dry it with nitrogen gas.

(3) Dip the contaminated sheet into the prepared cleaning solution for 30 seconds, then take it out and dry it with nitrogen.

(4) Place the cleaned wafer under a surface scanning electron microscope (FE-SEM) to observe the number of particles.

Example 1

Prepare different solutions (as shown in Table 1), and adjust the pH value of the solution to 2 with nitric acid or ammonia water.

Use the prepared solution to clean the polluted wafer, observe the effect of its clean wafer surface, the results are shown in Table 1:

Table 1 use solution Removal amount of film residual particles on wafer surface Deionized water 0% 0.5% by weight oxalic acid in water 0% 0.5% by weight citric acid in water 0% 0.5% by weight diethylenetriamine aqueous solution 3% 0.5% by weight ethylenediamine aqueous solution 0% 0.5% by weight ethylene glycol in water 80% 0.5% by weight 1,3-propanediol in water 70% 0.5% diethylene glycol aqueous solution 80%

From the above results, it can be seen that the addition of a small amount of polyalcohol compounds has a cleaning effect on the wafer.

Embodiment 2-4

Prepare the solutions shown in Table 2, and adjust the pH with ammonia water. Use the prepared solution to clean the polluted wafer, observe the effect of its clean wafer surface, the results are shown in Table 2:

Table 2 Prepare the solution Removal amount of film residual particles on wafer surface Example 2 6% by weight of citric acid, 0.05% by weight of BTA, 0.7% by weight of ethylene glycol, 0.3% by weight of diethanolamine, pH=3.5. 85% Example 3 4 wt% citric acid, 0.05 wt% BTA, 0.5 wt% diethanolamine, pH=3.5. 50% Example 4 5 wt% oxalic acid, 0.05 wt% BTA, pH=4.5. 20%

From the above results, it can be seen that the ability to clean wafers can be greatly improved by adding trace amounts of alcohol amines and polyols. Wafer surfaces cannot be effectively cleaned using only trace amounts of alcohol amines or only organic acid solutions.

The patent scope of the following application is used to define the reasonable protection scope of the present invention. However, various obvious improvements that can be achieved by those skilled in the art based on the disclosure of the present invention should also belong to the reasonable protection scope of the present invention.

Claims (7)

1, a kind of aqueous cleaning fluid composition that is used for behind the chemical-mechanical planarization, its pH comprises between 2～6: (a) 1-10 weight % is selected from the organic acid of oxalic acid or citric acid; (b) corrosion inhibitor of 0.01-0.5 weight %; (c) 0.01-2 weight % is selected from the hydramine of thanomin, diethanolamine, trolamine and Propanolamine; (d) 0.01-2 weight % is selected from ethylene glycol, 1, many alcohol compounds of ammediol and glycol ether; Reach (e) water.

2, composition as claimed in claim 1, wherein said pH value is between 2～3.5.

3, composition as claimed in claim 1, wherein said organic acid consumption are 4～8 weight %.

4, composition as claimed in claim 1, wherein said corrosion inhibitor is a triazole compounds.

5, composition as claimed in claim 4, wherein triazole compounds is to be selected from the benzotriazole or derivatives thereof.

6, composition as claimed in claim 1, wherein the consumption of said hydramine is 0.1～1 weight %.

7, composition as claimed in claim 1, wherein the content of said many alcohol compounds is 0.1～1 weight %.

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