TWI392714B - A new type of copper cmp slurry - Google Patents

Description

Copper chemical mechanical polishing fluid

The present invention relates to a chemical mechanical polishing slurry, and in particular, to a chemical mechanical polishing liquid for copper.

With the development of microelectronics technology, the integration of large integrated circuit chips has reached several billion components, and the feature size has entered the nanometer level. Therefore, nearly 100 processes in microelectronics processes, especially multilayer wiring, substrates, media, etc., must be fully chemically and mechanically flattened, and chemical mechanical polishing (CMP) has proven to be the best leveling. Method. In addition, large-scale integrated wiring is being converted from conventional aluminum (Al) to copper (Cu). Compared with aluminum, copper wiring has low resistivity; high resistance to electromigration; short delay time of resistor-capacitor (RC); 50% reduction in fabric layer; 30% reduction in process cost and 40% reduction in processing time. Therefore, the advantages of copper wiring have attracted widespread attention around the world.

However, it has not been possible to perform effective plasma etching or wet etching of copper materials so that copper interconnections are sufficiently formed in integrated circuits. Therefore, the chemical mechanical polishing method of copper is considered to be the most effective alternative. Referring to Figure 1, one of the workflows of the conventional chemical mechanical polishing method for copper is to remove a large amount of copper on the surface of the substrate with a fast and efficient removal rate; and to reduce the removal rate to polish when it is approaching the barrier layer. The remaining metal copper; finally remove surface contaminants to complete the entire workflow. A conventional chemical mechanical polishing liquid suitable for polishing copper, such as a composition and method for metal chemical mechanical polishing disclosed in U.S. Patent No. 6,616,717; a metal disclosed in U.S. Patent No. 5,527,423 a chemical mechanical polishing solution for a layer; a chemical mechanical polishing method for copper using a polymer complexing agent disclosed in U.S. Patent No. 6,821,897; a polishing of a chemical mechanical polishing process for copper disclosed in Chinese Patent No. 02114147.9 liquid; A polishing liquid for chemical mechanical polishing of copper disclosed in Chinese Patent No. 01818940.7; a chemical mechanical polishing liquid for copper and a manufacturing method for an integrated circuit disclosed in Chinese Patent No. 98120987.4.

However, the above-mentioned polishing solution for copper is prone to defects, scratches, stains, and/or other residues on the surface of the substrate after use, or insufficient rapid removal of copper, that is, insufficient polishing selectivity, or during polishing. There are problems such as local or overall corrosion. Therefore, it is necessary to develop a new chemical mechanical polishing liquid for copper.

Accordingly, it is a primary object of the present invention to provide a chemical mechanical polishing fluid for copper to solve the above problems. The chemical mechanical polishing liquid of copper according to the present invention can quickly remove a large amount of metallic copper.

A chemical mechanical polishing solution for copper according to a preferred embodiment of the present invention comprises an abrasive particle, an organic phosphonic acid, a polyacrylic acid and/or a salt thereof and/or a polyacrylic acid copolymer, an oxidizing agent, and A carrier. The chemical mechanical polishing slurry containing the organic phosphonic acid, polyacrylic acid and/or its salt and/or polyacrylic copolymer of the invention has high selectivity to copper during polishing, and the surface thereof is very good. The roughness and lower residue, while at lower abrasive particle levels, also ensure a higher copper removal rate.

In a preferred embodiment of the present invention, the concentration of the abrasive particles is 0.5 to 5%, preferably 1 to 2%, and the concentration of the organic phosphonic acid is 0.01 to 1%. The polyacrylic acid and/or The concentration of the salt and/or polyacrylic copolymer is 0.01-0.5%, the concentration of the oxidant is 0.001-5%, and the concentration of the carrier is the remaining percentage. The above % refers to the chemical machinery of the whole copper. The total weight percentage of the polishing liquid.

Further, the organic phosphonic acid is a variety of organic phosphonic acids, preferably hydroxyethylidene diphosphonic acid (HEDP), aminotrimethylene phosphonic acid (ATMP) and/or 2-hydroxyphosphoninoacetic acid. (HPAA).

Further, the polyacrylic acid is various polyacrylic acids, preferably polyacrylic acid and/or polymaleic acid. The salts are potassium, ammonium, sodium, calcium and/or other alkali or alkaline earth metal salts, preferably potassium, ammonium and/or sodium. The polyacrylic copolymer is preferably a polyacrylic acid-polyacrylate copolymer and/or a polyacrylic acid-polymaleic acid copolymer.

Further, the polyacrylic acid preferably has a molecular weight of 1,000 to 20,000, more preferably 2,000 to 5,000; and the polyacrylic copolymer preferably has a molecular weight of 1,000 to 20,000, more preferably 2,000 to 5,000.

Further, the abrasive particles are various abrasive particles, preferably ceria, alumina, yttria and/or polymer particles; the size of the abrasive particles is preferably from 20 to 200 nm, more preferably from 50 to 100 nm. . The oxidizing agent is preferably a oxidizing agent, preferably hydrogen peroxide, urea hydrogen peroxide, peracetic acid, benzammonium peroxide, potassium persulfate, ammonium persulfate and/or ammonium nitrate, more preferably hydrogen peroxide.

In a preferred embodiment of the present invention, the chemical mechanical polishing liquid has a pH of 2.0 to 4.0, and the pH adjusting agent may be potassium hydroxide, nitric acid, ethanolamine, and/or triethanolamine. Furthermore, the carrier is preferably water.

Further, the chemical mechanical polishing liquid according to the present invention further contains other additives such as a surfactant, a complexing agent, and/or an inhibitor.

The chemical mechanical polishing liquid according to the present invention can reduce the amount of abrasive particles to cause a significant drop in defects, scratches, stains and other residues; and, it has a high polishing selectivity to copper; moreover, it can prevent the metal polishing process Local and overall corrosion generated in the substrate reduces contaminants on the substrate surface to improve product yield.

The advantages and spirit of the present invention will be further understood from the following detailed description of the invention.

In order to achieve the above-mentioned technical means and other functions, the preferred embodiments are described as follows:

Referring to Table 1, a series of embodiments in accordance with the present invention are presented.

In each of the above embodiments, the materials are sequentially added to the reactor in the following order: abrasive particles, half of the amount of deionized water, organic phosphonic acid, H ₂ O ₂ , polyacrylic acid, and/or copolymer thereof. Stir well and the rest is filled with deionized water. Finally, adjust to the desired pH with a pH adjuster (20% KOH or dilute HNO ₃ according to the pH value), and continue to stir to make it a uniform fluid. After standing for 10 minutes, you can get the chemical machinery. Polishing solution. Please note that the starting materials in the examples described herein are all commercially available materials.

Specific embodiment 1

The wafers of blank tantalum (Ta), copper (Cu), cerium oxide (SiO ₂ ) and the like were polished by the chemical mechanical polishing slurry of the above Examples 1 to 6, respectively, and the polishing conditions were the same, and the polishing parameters were as follows: manufactured by Logitech. Polishing pad; downward pressure 2 psi; turntable speed / polishing head speed 60/80 rpm; polishing time 120 s; chemical mechanical polishing liquid flow rate 100 mL / min. See Table 2 for polishing results.

Obviously, the chemical mechanical polishing liquid of the present invention has a high polishing selectivity to copper as compared with cerium and cerium oxide; and the chemical mechanical polishing liquid of the present invention can reduce the amount of abrasive particles, as in Example 4. The chemical mechanical polishing liquid reduces the content of the abrasive particles to 0.5% by weight, and can still maintain a high removal rate of copper; in addition, the surface of the blank wafer polished by the chemical mechanical polishing liquid of Example 1 has no contaminants or less contaminants ( As shown in Figure 3, compared with before polishing (as shown in Figure 2), the surface of the polished blank copper wafer is significantly reduced in pitting and corrosion, and the quality is improved.

Specific embodiment 2

The chopper-impregnated/electroplated copper dioxide wafers were polished with the chemical mechanical polishing solutions of Examples 2 and 4, respectively, and polished to the barrier layer. The polishing conditions were the same for both sets of experiments. The polishing parameters were as follows: Polishing pad of Logitech.; downward pressure 2 psi; turntable speed / polishing head speed 60/80 rpm; polishing time 120 s; and chemical mechanical polishing liquid flow rate 100 mL / min. See Table 3 for polishing results.

Obviously, the use of the chemical mechanical polishing liquid of the present invention can significantly reduce the size of the depressions on the surface of the test wafer and reduce the residue. The surface of the copper wire polished by using the chemical mechanical polishing liquid of Example 4 has no obvious contaminant (see Fig. 4), which can prevent local and overall corrosion during polishing, and the surface roughness of the copper sheet is less than 0.3 nm (please See Figure 5).

In summary, the chemical mechanical polishing liquid (1) according to the present invention can reduce the amount of abrasive particles, causing a significant decrease in defects, scratches, stains and other residues; (2) high polishing selectivity to copper; (3) It can prevent local and overall corrosion generated during metal polishing, reduce surface contamination of the substrate, and improve product yield.

The features and spirit of the present invention will be more apparent from the detailed description of the preferred embodiments. On the contrary, the intention is to cover various modifications and equivalents within the scope of the invention as claimed. Therefore, the scope of the patent scope of the invention should be based on the above description. Make the broadest interpretation so that it covers all possible changes and arrangements of equality.

S11 to S20‧‧‧ workflow

FIG. 1 is a schematic diagram showing the working flow of a copper polishing liquid in the prior art.

Figure 2 is a surface microscopy image of a blank copper wafer before polishing.

Figure 3 is a surface microscopic image of a blank copper wafer after polishing.

Figure 4 is a scanning electron microscope image of the polished copper wire surface.

Figure 5 shows an atomic force microscope image of the copper surface of the test wafer (5 x 5 micron area).

Claims (10)

A chemical mechanical polishing slurry comprising: an abrasive particle; an organic phosphonic acid; a polyacrylic acid and/or a salt thereof (Salt) And/or a polyacrylic acid copolymer (Copolymer); an oxidizing agent (Oxidant); and a carrier liquid, wherein the concentration of the abrasive particles is 0.5 to 5 wt%, and the concentration of the organic phosphonic acid is 0.01 to 1 wt%. The concentration of the polyacrylic acid and/or a salt thereof and/or the polyacrylic acid copolymer is 0.01 to 0.5% by weight, the concentration of the oxidizing agent is 0.001 to 5% by weight, and the concentration of the carrier is the remaining percentage, wherein The chemical mechanical polishing liquid has a pH of 2.0 to 5.0. The chemical mechanical polishing liquid according to the first aspect of the invention, wherein the organic phosphonic acid is 1-hydroxyethylidene 1, 1diphosphonic acid (HEDP) or Amino trimethylene phosphonic acid (ATMP). And/or 2-hydroxyphosphinic acid acetic acid. The chemical mechanical polishing liquid according to claim 1, wherein the polyacrylic acid is polyacrylic acid and/or polymaleic acid, and the salt is a potassium salt (Potassic salt) and an ammonium salt (Ammonium). The salt and/or sodium salt is a polyacrylic acid-polyacrylate copolymer and/or a polyacrylic acid-polymaleic acid copolymer. The chemical mechanical polishing liquid according to any one of claims 1 to 3, wherein the polyacrylic acid has a molecular weight of 1,000 to 20,000; and the polyacrylic copolymer has a molecular weight of 1,000 to 20,000. The chemical mechanical polishing liquid according to claim 4, wherein the polyacrylic acid has a molecular weight of 2,000 to 5,000; and the molecular weight of the polyacrylic copolymer is 2,000~5,000. The chemical mechanical polishing liquid according to any one of claims 1 to 3, wherein the abrasive particles are cerium oxide, aluminum oxide, cerium oxide and/or polymer particles, and the concentration of the abrasive particles is 1~2wt%. The chemical mechanical polishing liquid according to any one of claims 1 to 3, wherein the abrasive particles have a size of 20 to 200 nm. The chemical mechanical polishing liquid according to claim 6, wherein the abrasive particles have a size of 50 to 100 nm. The chemical mechanical polishing liquid according to any one of claims 1 to 3, wherein the oxidizing agent is hydrogen peroxide, urea hydrogen peroxide, peracetic acid, benzammonium peroxide, potassium persulfate, Ammonium persulfate and / or ammonium nitrate. The chemical mechanical polishing liquid according to any one of claims 1 to 3, wherein the chemical mechanical polishing liquid further comprises an inhibitor.