CN117903887A - Cleaning solution after etching - Google Patents

Abstract

The invention discloses a post-etching cleaning solution which is mainly applied to the post-section cleaning of copper interconnection and can effectively remove dry etching residues or ashed residues. The cleaning solution is prepared from the following raw materials in percentage by mass: 5-15% of fluoride, organic base, chelating agent, corrosion inhibitor, surfactant and water for the balance. The cleaning liquid disclosed by the invention has the advantages of wide residue range, good cleaning effect on structures with narrow line width and high aspect ratio, no corrosiveness (exposed low-k dielectric materials, metal oxides, metals, metal nitrides and alloys thereof) on metals or dielectric materials common to back-end interconnection, and good application prospects.

Description

Cleaning solution after etching

Technical Field

The invention belongs to the field of semiconductor integrated circuit manufacturing, and particularly relates to a cleaning solution for copper interconnection back section dry etching.

Background

At the end of the 90 s of the last century, the latter-stage copper interconnect process was used to replace the aluminum interconnect process in the field of semiconductor integrated circuit fabrication. Copper has many advantages, low resistivity, low electrical mobility, and good conductivity. This allows copper as an interconnect to be made finer and denser while having equal or even greater current carrying capability, thereby reducing the area of the chip. Copper has become the only choice for advanced fabrication processes below 130nm as a metal interconnect material. Cu has the characteristic of being relatively easily oxidized and corroded. The cleaning process takes into account how to efficiently remove reaction byproducts (polymers) while protecting the copper from corrosion. In the copper interconnect cleaning process, fluorine-containing cleaning liquid is mainly used, such as ST250 cleaning agent of Entegris corporation.

With the continuous progress of technology nodes, the chip feature size is continuously reduced, the width of the copper wire is also narrower and narrower, the solution viscosity of the traditional cleaning solvent is larger, smaller and smaller grooves and holes are difficult to infiltrate, and the cleaning effect is also greatly reduced. At the same time, more and more materials are introduced, such as cobalt, tantalum and other metal materials, and SiCOH, BD/BDII and other low-k dielectric materials, so that compatibility of conventional fluorine-containing cleaning solutions with various materials is challenging.

Developing a cleaning solution with good cleaning effect and strong material compatibility becomes a problem to be solved in the field.

Disclosure of Invention

The invention aims to solve the technical problems that the traditional cleaning liquid has poor structure cleaning effect under the conditions of narrow line width and high depth-to-width ratio, and meanwhile, the invention has good compatibility to metal materials and low-k materials and cannot generate excessive corrosion.

Specifically, the present invention is a solution to the above technical problems by the following technical means.

Specifically, the invention provides a fluorine-containing cleaning solution after dry etching, which comprises fluoride, organic alkali, a corrosion inhibitor, a surfactant and water, wherein the water is supplemented to 100% by mass.

Preferably, the fluoride is selected from one or more of hydrofluoric acid, ammonium fluoride, ammonium bifluoride, and ammonium bifluoride.

Preferably, the fluoride content is preferably 5-15% by mass.

Preferably, the organic base is selected from one or more of monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, hydroxylamine and derivatives thereof, triethylenediamine, tetramethylethylenediamine, pentamethyldiethylenetriamine, 4-dimethylaminopyridine, pyridine, methylamine, ethylamine, ethylenediamine, triethylamine, butylamine, isobutylamine, octylamine, aniline;

Preferably, the content of the organic base is preferably 25-40% by mass.

Preferably, the corrosion inhibitor is selected from one or more of benzotriazole, methylbenzotriazole, carboxybenzotriazole, benzotriazole derivatives, mercaptobenzothiazole, benzothiophene, 2-methylimidazole, benzimidazole and 2-mercaptobenzimidazole;

preferably, the content of the corrosion inhibitor is preferably 0.01-10% by mass.

Preferably, the surfactant is selected from one or more of perfluoroethyl acetic acid, perfluoroethyl ammonium acetate, perfluorononylphenol polyoxyethylene ether, perfluorooctylphenol polyoxyethylene ether, perfluoro (diethylene glycol dimethyl ether), perfluorohexyl ethanol, perfluorohexyl ethyl sulfonic acid, perfluorohexyl ethyl phosphate, perfluorooctyl ethylene, perfluorohexyl ethylene.

Preferably, the surfactant content is preferably 0.01-10% by mass.

Compared with the prior art, the invention has the technical advantages that:

(1) The cleaning liquid has strong cleaning capability, can effectively remove the post-copper interconnect dry etching residues or ashed residues, and has good cleaning effect on structures with narrow linewidth and high depth and width.

(2) The invention has good compatibility to metal materials and low-k materials in the cleaning process, and can not generate excessive corrosion. The device is suitable for a high-rotation-speed single-chip rotary cleaning mode.

(3) The cleaning liquid has a large operation window and has good application prospect in the field of the rear-stage cleaning process of semiconductor manufacture.

Detailed Description

The advantages of the present invention are described in detail below in conjunction with tables and specific embodiments.

The reagents and materials used in the present invention are commercially available. The components and their contents as listed in Table 1 were mixed until completely uniform, as shown in Table 1.

Table 1 comparative examples and the components and contents according to the preferred examples of the invention

Placing the rear copper interconnection after dry etching in a SINGLE WAFER tool matched with a cleaning machine, and adding the cleaning liquid obtained in any one of the embodiments 1-14 for cleaning, wherein the cleaning time is 1.5min; the dipping temperature is 50 ℃, and the cleaning effect is as follows:

TABLE 2 film corrosion Rate (A/min) and Structure sheet cleaning results

From the etching rate of each film layer in Table 2, the cleaning solution of the invention can not erode metals (such as Ti, W and Cu) and non-metals (TEOS and SiON) used in the manufacture of semiconductors basically, has small etching rate to various film layers, meets the etching rate requirement of the back-end cleaning of the semiconductor industry, and shows that the material of the invention has good compatibility and high safety to products in the use process.

From Table 2, the results of cleaning the structural sheets of comparative examples 1-8 show that the residual of via holes can be cleaned, because the organic base of the present invention not only provides an alkaline environment for the cleaning liquid, but also has surface activity, which can effectively reduce the surface tension of the system. Through the additional perfluoro surfactant, the two chemical substances with surface activity cooperate with each other, the surface tension of the system is further reduced, so that the liquid medicine can easily drill into the high-depth-type specific via hole in the cleaning process, and a good cleaning effect can be realized. Better effect than the cleaning solution with single surfactant. In addition, the perfluoro surfactant has the characteristic of high chemical stability, and the stability of the liquid medicine is further improved.

As can be seen from Table 2, in comparative examples 7 and 8, the short-chain nonionic surfactant is added in examples 7 and 8 of the present invention under the condition that other components and contents are substantially the same, the cleaning effect on Via holes is good, the bottom side wall is free from residual residues, and the bottom side wall of the pore channel is free from corrosion.

In addition, in comparative example 10 and example 11, the benzotriazole, which is a metal corrosion inhibitor for use in semiconductor industry, was used in example 11, and 2-methylimidazole was used in example 10 instead of benzotriazole, so that the protection effect on Cu was better, and the same effect on residual removal was achieved.

In summary, it can be seen that the fluorine-containing cleaning solution of the nitrogen-containing heterocyclic compound and the polymer thereof can effectively replace the traditional azole corrosion inhibitor, realize the control of metal and nonmetal corrosion rates, and simultaneously can effectively remove plasma etching residues in the semiconductor Damascus process, thereby having good application prospects in the fields of semiconductor wafer cleaning and the like.

It should be understood that the wt% of the present invention refers to the mass percent.

It should be noted that the embodiments of the present invention are preferred and not limited in any way, and any person skilled in the art may make use of the above-disclosed technical content to change or modify the same into equivalent effective embodiments without departing from the technical scope of the present invention, and any modification or equivalent change and modification of the above-described embodiments according to the technical substance of the present invention still falls within the scope of the technical scope of the present invention.

Claims (7)

1. The post-etching cleaning solution is characterized by comprising the following raw materials in parts by mass: 5-15% of fluoride, 25-40% of organic base, 0.01-10% of corrosion inhibitor, 0.01-10% of surfactant and water, wherein the balance is water, and the sum of the mass fractions of the components is 100%.

2. The post-etch cleaning solution of claim 1, wherein the fluoride is selected from one or more of hydrofluoric acid, ammonium fluoride, ammonium bifluoride, and ammonium bifluoride.

3. The post-etch cleaning solution of claim 1, wherein the organic base is selected from one or more of monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, hydroxylamine, triethylenediamine, tetramethylethylenediamine, pentamethyldiethylenetriamine, 4-dimethylaminopyridine, pyridine, methylamine, ethylamine, ethylenediamine, triethylamine, butylamine, isobutylamine, octylamine, aniline.

4. The post-etch cleaning solution of claim 1, wherein the corrosion inhibitor is selected from one or more of benzotriazole, methylbenzotriazole, carboxybenzotriazole, benzotriazole derivatives, mercaptobenzothiazole, benzothiophene, 2-methylimidazole, benzimidazole, 2-mercaptobenzimidazole.

5. The post-etch cleaning solution of claim 1, wherein the surfactant is selected from one or more of perfluoroethyl acetic acid, perfluoroethyl ammonium acetate, perfluorononylphenol polyoxyethylene ether, perfluorooctylphenol polyoxyethylene ether, perfluoro (diethylene glycol dimethyl ether), perfluorohexyl ethanol, perfluorohexyl ethyl sulfonic acid, perfluorohexyl ethyl phosphate, perfluorooctyl ethylene, perfluorohexyl ethylene.

6. The cleaning process after the back-end copper interconnection is subjected to dry etching by adopting the cleaning solution according to any one of claims 1-5, wherein the back-end copper interconnection is placed in etching solution in the cleaning process, and is immersed for 1-3min at the temperature of 30-60 ℃ to finish the cleaning.

7. The cleaning process according to claim 6, wherein the cleaning is performed by immersing the substrate in an etching solution at 50 ℃ for 1 min.