Chemical mechanical polishing slurry and method of using the same

Abstract

This invention provides a polishing slurry for carbon-containing materials and a method for using it. The chemical mechanical polishing slurry comprises abrasives, oxidants, and inorganic acids and their salts. While maintaining a high removal rate of carbon-containing materials, this polishing slurry effectively reduces the residue of polishing by-products on the surface of the polishing pad, significantly improves the cleanliness of the polishing pad surface, extends the service life of the polishing pad, and reduces defects on the surface of the polished wafer.

Description

[Technical Field]

[0001] This invention relates to the field of chemical mechanical polishing, and more particularly to a chemical mechanical polishing fluid and its application method. [Previous Technology]

[0002] With the continuous development of semiconductor technology and the increasing number of interconnect layers in large-scale integrated circuits, the planarization technology of conductive and insulating dielectric layers has become particularly crucial. In the 1980s, chemical mechanical polishing (CMP) technology, pioneered by IBM, is considered the most effective method for global planarization. CMP consists of chemical action, mechanical action, and a combination of both. It typically comprises a polishing table with a polishing pad and a polishing head for holding the wafer. The polishing head holds the wafer in place, and then presses the front side of the wafer onto the polishing pad. During CMP, the polishing head moves linearly on the polishing pad or rotates in the same direction as the polishing table. Simultaneously, a slurry containing abrasive is dripped onto the polishing pad and spreads evenly due to centrifugal force. Global planarization of the wafer surface is achieved through the combined mechanical and chemical action.

[0003] Silicon carbide, amorphous carbon, and other carbon-containing materials are new-generation wideband semiconductor materials, possessing characteristics such as wide bandgap, high thermal conductivity, high critical breakdown electric field, high electron saturation migration rate, and high chemical stability. They have enormous application potential in high-temperature, high-frequency, high-power, and high-density integrated electronic devices. However, carbon-containing materials are very stable at room temperature, do not readily undergo chemical reactions, and have excellent resistance to mechanical abrasion. Therefore, commonly used chemical mechanical polishing slurries are difficult to achieve high polishing speeds when polishing carbon-containing materials.

[0004] Carbon-containing materials typically require oxidation with an oxidizing agent for removal. Hydrogen peroxide is a commonly used oxidizing agent, but its oxidizing power is weak, failing to achieve an ideal removal rate. CN102464944A proposes adding strong oxidizing agents such as permanganate, manganate, and their salts to the polishing solution to improve the chemical mechanical polishing rate of carbon-containing materials. However, during the polishing process using permanganate, manganate, and their salts as oxidizing agents, the reduction of these oxidizing agents inevitably generates dark-colored byproducts, which easily deposit on the surface and pores of the polishing pad. This leads to the accumulation of polishing byproducts on the polishing pad, affecting its lifespan and increasing surface defects after polishing. [Summary of the Invention]

[0005] In order to solve the above problems, the present invention provides a polishing slurry and its application method. By adding inorganic acids and their salts to the polishing slurry, the by-products of the polishing process can react directly with the inorganic acids and their salts to form soluble manganese complexes with minimal impact on the removal rate. This avoids the deposition of by-products of the polishing process on the polishing pad, extends the service life of the polishing pad, and reduces defects on the surface of the wafer after polishing.

[0006] The present invention provides a chemical mechanical polishing fluid, specifically comprising abrasive, oxidant, inorganic acid and its salt and water.

[0007] In some embodiments, the inorganic acid is selected from one or more of hydrobromic acid, hydroiodic acid, hydrotelluric acid, boric acid, perboric acid, metaboric acid, bromic acid, iodic acid, chromic acid, manganese acid, arsenic acid, tungstic acid, molybdic acid, selenic acid, telluric acid, lead acid, aluminic acid, metaarsenic acid, phosphoric acid, hypophosphoric acid, and pyrophosphoric acid; and the salt is selected from one or more of potassium salt, sodium salt, or ammonium salt.

[0008] In some embodiments, the oxidant is potassium permanganate.

[0009] In some embodiments, the abrasive is selected from one or more of the following: single-component abrasives of manganese dioxide, aluminum oxide, cerium dioxide, and titanium dioxide, and composite abrasives with a surface coated with silicon dioxide, aluminum oxide, cerium dioxide, and titanium dioxide.

[0010] In some embodiments, the mass percentage content of the abrasive is 0.1-10 wt%.

[0011] In some embodiments, the particle size of the abrasive is in the range of 50-500 nm.

[0012] In some embodiments, the oxidant has a mass percentage content of 0.01-1 wt%.

[0013] In some embodiments, the inorganic acid and its salts have a mass percentage content of 0.01-2 wt%.

[0014] In some embodiments, the inorganic acid and its salts have a mass percentage content of 0.1-0.5 wt%.

[0015] In some embodiments, the pH value of the chemical mechanical polishing fluid is 2-6.

[0016] The polishing solution of the present invention can be prepared by concentrating the components other than the oxidant. Before use, it can be diluted with deionized water and the oxidant can be added to the concentration range of the present invention.

[0017] On the other hand, the present invention provides a method of using the chemical mechanical polishing slurry of the present invention, comprising: using the chemical mechanical polishing slurry of the present invention for chemical mechanical polishing of carbon-containing materials.

[0018] Compared with the prior art, the advantages of the present invention are: the addition of inorganic acids and their salts to the chemical mechanical polishing slurry reduces the residue of polishing byproducts on the surface of the polishing pad, and at the same time reduces the defects on the surface of the wafer after polishing.

Implementation Method

[0019] The advantages of the present invention will be further illustrated below with reference to specific embodiments.

[0020] According to the formula given in Table 1, the polishing solutions of Comparative Examples 1-4 and Examples 1-50 of this application were prepared. Then, a certain concentration of oxidant solution, inorganic acid and its salts were mixed evenly with the abrasive. Water was used to make up the mass percentage to 100%. KOH or HNO3 was used to adjust the polishing solution to the required pH value.

[0021] Table 1: Composition, content and pH of polishing solutions for Comparative Examples 1-4 and Examples 1-50 Polishing liquid abrasive Oxidizing agent Inorganic acids and their salts pH kernel Coating material Content wt% Particle size (nm) Specific substances Content wt% Specific substances Content wt% Comparative Example 1 Silicon dioxide / 10.0 80 potassium permanganate 0.08 2.5 Comparative Example 2 Titanium dioxide / 8.0 250 potassium permanganate 0.30 2.8 Comparative Example 3 Titanium dioxide / 2.5 230 potassium permanganate 0.01 6.0 Comparative Example 4 Cerium dioxide Titanium dioxide 0.1 130 potassium permanganate 0.30 3.5 Example 1 Aluminum oxide / 3.0 150 potassium permanganate 0.20 Phosphoric acid 1.0 3.0 Example 2 Titanium dioxide / 1.0 260 potassium permanganate 0.50 Potassium dihydrogen phosphate 0.1 2.2 Example 3 Titanium dioxide Cerium dioxide 0.5 500 potassium permanganate 0.30 Chromic acid 1.2 2.5 Example 4 Manganese dioxide Titanium dioxide 1.5 280 potassium permanganate 0.50 hydroiodic acid 0.4 3.2 Example 5 Titanium dioxide Aluminum oxide 2.0 320 potassium permanganate 0.20 Ammonium borate 0.6 2.5 Example 6 Cerium dioxide Aluminum oxide 1.0 100 potassium permanganate 1.00 Sodium phosphate 0.3 3.8 Example 7 Titanium dioxide Aluminum oxide 3.0 300 potassium permanganate 0.20 Pyrophosphate 0.5 2.2 Example 8 Titanium dioxide Manganese dioxide 10.0 320 potassium permanganate 0.50 Arsenic 2.0 2.6 Example 9 Cerium dioxide Aluminum oxide 1.5 150 potassium permanganate 0.50 manganic acid 0.5 3.2 Example 10 Titanium dioxide Aluminum oxide 1.5 300 potassium permanganate 0.50 hydroiodic acid 0.3 3.5 Example 11 Titanium dioxide Aluminum oxide and manganese dioxide 2.0 350 potassium permanganate 0.01 Phosphoric acid + dipotassium hydrogen phosphate 0.3 + 0.4 2.8 Example 12 Manganese dioxide Aluminum oxide 1.5 50 potassium permanganate 0.30 Sodium bromate 1.2 3.2 Example 13 Titanium dioxide Aluminum oxide 3.0 320 potassium permanganate 0.40 metaboric acid 0.3 6.0 Example 14 Titanium dioxide Silicon dioxide 3.0 80 potassium permanganate 0.10 Sodium aluminate 0.0 2.6 Example 15 Manganese dioxide Aluminum oxide 1.0 150 potassium permanganate 0.20 hydroiodic acid 0.7 6.0 Example 16 Titanium dioxide Aluminum oxide 0.5 280 potassium permanganate 0.40 hypophosphite 1.0 4.0 Example 17 Titanium dioxide Aluminum oxide 2.0 320 potassium permanganate 0.20 molybdic acid 0.1 2.5 Example 18 Cerium dioxide Aluminum oxide 2.0 150 potassium permanganate 0.20 telluric acid 0.5 2.0 Example 19 Titanium dioxide Silicon dioxide 5.0 300 potassium permanganate 0.50 Selenic acid 1.8 5.2 Example 20 Cerium dioxide Aluminum oxide 2.5 200 potassium permanganate 0.01 lead acid 0.8 2.8 Example 21 Titanium dioxide Aluminum oxide and silicon dioxide 1.5 350 potassium permanganate 0.03 hydrotelluric acid 1.0 3.6 Example 22 Titanium dioxide Aluminum oxide and manganese dioxide 4.0 350 potassium permanganate 0.50 Vanadic acid 1.2 4.2 Example 23 Cerium dioxide Aluminum oxide 3.0 150 potassium permanganate 0.20 Arsenic trioxide 2.0 5.4 Example 24 Titanium dioxide Silicon dioxide 1.0 260 potassium permanganate 0.50 tungstic acid 1.5 2.8 Example 25 Titanium dioxide Aluminum oxide 0.5 500 potassium permanganate 0.30 telluric acid 0.1 3.6 Example 26 Titanium dioxide Aluminum oxide 1.5 280 potassium permanganate 0.50 Vanadic acid 0.3 4.0 Example 27 Titanium dioxide Aluminum oxide and silicon dioxide 2.0 320 potassium permanganate 0.20 Potassium bromate + Sodium bromate 0.2 + 0.5 2.0 Example 28 Cerium dioxide / 1.0 100 potassium permanganate 1.00 Potassium borate 1.0 5.0 Example 29 Manganese dioxide / 3.0 300 potassium permanganate 0.20 Sodium arsenate 1.8 2.5 Example 30 Titanium dioxide Aluminum oxide and manganese dioxide 10.0 320 potassium permanganate 0.50 hypophosphite 2.0 4.0 Example 31 Titanium dioxide Aluminum oxide 1.5 150 potassium permanganate 0.50 lead acid 0.01 5.2 Example 32 Aluminum oxide / 1.5 300 potassium permanganate 0.50 Potassium arsenite 0.4 2.2 Example 33 Titanium dioxide Aluminum oxide and silicon dioxide 2.0 350 potassium permanganate 0.01 Metaphosphate 0.9 3.6 Example 34 Cerium dioxide Aluminum oxide 1.5 50 potassium permanganate 0.30 manganic acid 1.3 4.5 Example 35 Titanium dioxide Aluminum oxide 3.0 320 potassium permanganate 0.20 Chromic acid 1.5 2.6 Example 36 Titanium dioxide Aluminum oxide and silicon dioxide 2.5 150 potassium permanganate 0.50 Phosphoric acid 0.5 3.2 Example 37 Titanium dioxide Aluminum oxide 4.0 150 potassium permanganate 0.50 telluric acid 0.3 4.0 Example 38 Titanium dioxide Aluminum oxide and silicon dioxide 5.0 150 potassium permanganate 0.50 Vanadic acid 0.2 5.2 Example 39 Titanium dioxide Cerium dioxide 0.1 300 potassium permanganate 0.50 perboric acid 0.5 2.4 Example 40 Titanium dioxide Aluminum oxide 1.5 120 potassium permanganate 0.02 Arsenic 0.9 3.0 Example 41 Aluminum oxide / 0.8 100 potassium permanganate 0.80 lead acid 0.3 4.2 Example 42 Titanium dioxide / 8.0 250 potassium permanganate 0.30 Phosphoric acid 0.1 2.8 Example 43 Titanium dioxide / 2.5 230 potassium permanganate 0.01 hydroiodic acid 0.01 6.0 Example 44 Cerium dioxide Aluminum oxide 5.0 80 potassium permanganate 1.00 boric acid 0.2 3.0 Example 45 Cerium dioxide Titanium dioxide 0.1 100 potassium permanganate 0.30 Phosphoric acid 0.3 3.5 Example 46 Titanium dioxide Manganese dioxide and aluminum oxide 2.5 350 potassium permanganate 1.00 boric acid 0.5 4.0 Example 47 Titanium dioxide Aluminum oxide 4.0 250 potassium permanganate 0.15 Phosphoric acid 0.1 2.0 Example 48 Titanium dioxide Manganese dioxide 4.5 300 potassium permanganate 0.30 metaboric acid 0.2 3.0 Example 49 Manganese dioxide Titanium dioxide 1.5 150 potassium permanganate 0.10 Pyrophosphate 0.3 3.8 Example 50 Cerium dioxide Titanium dioxide 2.5 50 potassium permanganate 0.35 Bromic acid 0.2 2.0

[0022] Effective Example 1 The polishing slurries of Comparative Examples 1-4 and Examples 42-50 were used to polish empty wafers of amorphous carbon under the following conditions. Specific polishing conditions: Reflexion LK polishing machine, IC1010 polishing pad, 300mm wafer, polishing pressure 2.5psi, polishing disc speed 93 rpm, polishing head speed 87 rpm, polishing slurry flow rate 300 ml / min, polishing time 1 min. The polishing effect data of Comparative Examples 1-4 and Examples 42-50 are recorded in Table 2.

[0023] Table 2 Polishing effect data of Comparative Examples 1-4 and Examples 42-50 Polishing liquid Amorphous carbon removal rate (Å / min) Polishing pad surface cleanliness Comparative Example 1 30 +++ Comparative Example 2 180 ++++ Comparative Example 3 55 +++ Comparative Example 4 175 ++++ Example 42 178 ++ Example 43 58 + Example 44 172 + Example 45 179 + Example 46 180 + Example 47 241 + Example 48 229 ++ Example 49 185 ++ Example 50 203 +

[0024] The cleanliness of the polishing pad surface is described as follows: ++++ The polishing pad surface is severely contaminated; +++ The polishing pad surface is obviously contaminated; ++ The polishing pad surface is slightly contaminated; + The polishing pad surface is not obviously contaminated.

[0025] As can be seen from Table 2, compared with the comparative examples, the polishing slurry of the present invention has a higher amorphous carbon removal rate. The polishing slurries of comparative examples 1-3 contain single-component abrasives, and the polishing slurry of comparative example 4 uses composite abrasives and potassium permanganate as oxidants, which has a certain amorphous carbon removal rate, but the surface cleanliness of the polishing pad is poor after polishing. Compared with the polishing slurries of comparative examples 2, 3 and 4, the polishing slurries of examples 42, 44 and 45 add inorganic acids and their salts, and their amorphous carbon removal rate is slightly reduced, but they can effectively reduce the polishing by-product residue on the surface of the polishing pad and significantly improve the surface cleanliness of the polishing pad.

[0026] As can be seen, the polishing fluid of Examples 42-50 of the present invention, by selecting abrasives, oxidants and inorganic acids and their salts with appropriate particle sizes and adjusting the pH value, can reduce the residue of polishing by-products on the surface of the polishing pad while ensuring a high amorphous carbon removal rate, and significantly improve the surface cleanliness of the polishing pad.

[0027] Effective Example 2: Using the polishing slurries of Comparative Examples 1-4 and Examples 47-50 of the present invention, the amorphous carbon blank wafer was polished under the following conditions, and the number of surface defects was detected. Specific polishing conditions: Reflexion LK polishing machine, IC1010 polishing pad, 300mm wafer, polishing pressure 2.5psi, polishing disk speed 93 rpm, polishing head speed 87 rpm, polishing slurry flow rate 300ml / min, polishing time 1min. The number of surface defects on the blank wafer after polishing was detected using a surface defect scanner SP2, and the results of the surface defect count are listed in Table 3.

[0028] Table 3 Number of surface defects on amorphous carbon after polishing in Comparative Examples 1-4 and Examples 47-50 Polishing liquid Number of surface defects (>80nm) of amorphous carbon (particles) Comparative Example 1 396 Comparative Example 2 419 Comparative Example 3 387 Comparative Example 4 425 Example 47 63 Example 48 46 Example 49 37 Example 50 59

[0029] As can be seen from Table 3, in Comparative Examples 1-4, which did not use inorganic acids and their salts, the number of defects on the surface of the amorphous carbon wafers after polishing was in the range of 350-450. However, the polishing solution of Examples 47-50 of the present invention, which used inorganic acids and their salts, significantly improved the surface defects of the amorphous carbon after polishing, reducing the number of surface defects to the range of 30-70. The number of surface defects of amorphous carbon was greatly reduced.

[0030] Effective Example 3 The polishing slurries of Comparative Examples 1-4 and Examples 47-50 were used to polish empty silicon carbide wafers under the following conditions. Specific polishing conditions: Reflexion LK polishing machine, IC1010 polishing pad, 300mm wafer, polishing pressure 2.5psi, polishing disc speed 93 rpm, polishing head speed 87 rpm, polishing slurry flow rate 300 ml / min, polishing time 1 min. The polishing effect data of Comparative Examples 1-4 and Examples 47-50 are recorded in Table 4.

[0031] Table 4 shows the silicon carbide polishing effect data of Comparative Examples 1-4 and Examples 47-50. Polishing liquid Silicon carbide removal rate (Å / min) Polishing pad surface cleanliness Comparative Example 1 220 +++ Comparative Example 2 674 +++ Comparative Example 3 281 ++++ Comparative Example 4 659 +++ Example 47 802 ++ Example 48 748 + Example 49 683 + Example 50 705 +

[0032] As can be seen from Table 4, compared with Comparative Examples 1-4 which did not add inorganic acids and their salts, the polishing liquid of Examples 47-50 of the present invention which uses inorganic acids and their salts still has a higher silicon carbide removal rate, while reducing the polishing pad by-product residue on the surface of the polishing pad and improving the surface cleanliness of the polishing pad.

[0033] In summary, by adding inorganic acids and their salts, the present invention ensures that the polishing slurry has a high removal rate for carbon-containing materials under acidic conditions, reduces the residual polishing by-products on the surface of the polishing pad after polishing, and reduces defects on the surface of the wafer after polishing.

[0034] The specific embodiments of the present invention have been described in detail above, but they are merely examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.

Claims

1. A chemical mechanical polishing slurry for chemical mechanical polishing of carbon-containing materials, characterized in that it comprises abrasive, oxidant, inorganic acid and its salts, and water; wherein the oxidant is potassium permanganate; the abrasive is selected from one or more of single-component abrasives of manganese dioxide, aluminum oxide, cerium dioxide, and titanium dioxide, and composite abrasives with surface coatings of silicon dioxide, aluminum oxide, cerium dioxide, and titanium dioxide; the inorganic acid and its salts have a mass percentage content of 0.01-2 wt%; the inorganic acid is selected from one or more of hydrobromic acid, hydroiodic acid, hydrotelluric acid, boric acid, perboric acid, metaboric acid, bromic acid, iodic acid, chromic acid, manganese acid, arsenic acid, tungstic acid, molybdic acid, selenic acid, telluric acid, lead acid, aluminic acid, metaarsenic acid, phosphoric acid, hypophosphoric acid, and pyrophosphoric acid; and the salts are selected from one or more of potassium salts, sodium salts, or ammonium salts; the pH value of the chemical mechanical polishing slurry is 2-6, wherein... The particle size range of the abrasive is 50-500 nm.

2. The chemical mechanical polishing slurry as described in claim 1, wherein, The abrasive content is 0.1-10 wt%.

3. The chemical mechanical polishing slurry as described in claim 1, wherein, The oxidant has a mass percentage content of 0.01-1 wt%.

4. The chemical mechanical polishing slurry as claimed in claim 1, wherein, The inorganic acid and its salts contain 0.1-0.5 wt% of each.