Copper chemical mechanical polishing solution and application thereof

Abstract

The invention provides a chemical mechanical polishing solution for copper and application thereof. The chemical mechanical polishing solution for copper adopts the compound as shown in the formula (I) as a corrosion inhibitor, and in chemical mechanical polishing of copper, the chemical mechanical polishing solution can obtain a relatively high polishing rate during polishing under high pressure and reduce the polishing rate during polishing under low pressure; therefore, the chemical mechanical polishing solution for copper can meet the use requirement that the previous two steps of polishing of copper metal are combined into one step of polishing. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the field of chemical engineering, and relates to a chemical mechanical polishing (CMP) liquid, in particular to a chemical mechanical polishing liquid for copper interconnect wiring in semiconductor manufacturing processes and its applications. Background Art

[0002] At present, the integration density of very large scale integrated circuit (VLSI) chips has reached several billion components, and the feature size has entered the nanometer level. This requires that hundreds of processes in microelectronics technology, especially multi-layer wiring, substrates, dielectrics, etc., must undergo chemical mechanical planarization. The wiring of VLSI is transforming from the traditional aluminum wiring process to the copper wiring process. Compared with Al, Cu wiring has the advantages of low resistivity, high electromigration resistance, and short RC delay time, which enables Cu wiring to replace Al as the interconnect metal in semiconductor manufacturing. However, there is currently no effective technology for plasma etching or wet etching of copper to achieve planarization, and chemical mechanical polishing remains the most effective process for copper wiring planarization.

[0003] Generally, the chemical mechanical polishing process of copper is divided into three steps, which are carried out on three polishing pads respectively: In the first step, a relatively high down pressure is used to quickly and efficiently remove a large amount of copper on the substrate surface and leave a certain thickness of copper; in the second step, a relatively low down pressure is used to remove a small amount of remaining metallic copper at a lower removal rate and stop at the barrier layer; in the third step, a barrier layer polishing liquid is used to remove the barrier layer, part of the dielectric layer, and a small amount of metallic copper, thereby achieving planarization. Currently, in order to effectively remove metallic copper, sufficient polishing time must be ensured in the first and second polishing steps; at the same time, in order to correct the dish-shaped depression caused by copper polishing, sufficient time is also required for the third step of barrier layer polishing, which makes the copper polishing process a bottleneck in production capacity.

[0004] The components in copper polishing solution generally include abrasive particles, corrosion inhibitors, complexing agents, wetting agents, pH regulators, oxidants, etc. To achieve a higher removal rate, a weaker corrosion inhibitor is usually selected, and the polishing rate is controlled by changing the polishing pressure. To improve the polishing rate, attempts are being made to combine the first two polishing steps of copper into one step. However, the polishing pressure in the first step is relatively high (1.5 - 2.0 psi), while that in the second step is relatively low (0.5 - 1.0 psi). Usually, two different components of copper polishing solution are required to cooperate with different polishing pressures for two-step polishing. However, when these two steps are combined into one step (high pressure first and then low pressure) for polishing, the existing polishing solution cannot meet the polishing requirements. The reason is as follows: When the first two polishing steps are carried out separately, under high polishing pressure, the role of the corrosion inhibitor is weak and the polishing rate is very fast; under low polishing pressure, the corrosion inhibitor can be fully adsorbed on the copper surface, which can play a certain role in reducing the polishing rate and the polishing rate is relatively slow; when these two steps are combined into one step (high pressure first and then low pressure) for polishing, after the high pressure is converted to low pressure, the corrosion inhibitor cannot be fully adsorbed on the copper surface, and after polishing at high pressure for a certain period of time, the temperature of the polishing pad is relatively high, which accelerates the corrosion rate of the copper surface, resulting in a relatively high polishing rate under low pressure and affecting the planarization effect.

[0005] Related research has reported methods for improving polishing efficiency. US20030008599A1 invented a chemical mechanical polishing method, which controls the polishing rate of copper by introducing oxidants and reductants at different stages during the polishing process; US20100130101A1 disclosed a chemical mechanical polishing method, which introduces components of polishing solution with different compositions onto the polishing pad through two pipelines and mixes the polishing solution online for polishing, and controls the polishing rate by adjusting the flow rates of different components; CN103903979A also reported a method for controlling the polishing rate by using two pipelines, one for supplying the polishing solution and the other for supplying the polishing rate inhibitor. All of the above methods have two problems. The first is the online mixing of chemical components, which has the problem of uneven mixing, bringing great risks to polishing planarization and wafer polishing consistency; the second is the mixing of materials with different components after polishing, which is likely to cause the aggregation of abrasive nanoparticles, shorten the service life of the polishing pad, and easily block the drain pipe of the polishing machine.

[0006] Therefore, how to develop a new chemical mechanical polishing solution that can effectively carry out chemical mechanical polishing of copper, simplify the polishing process, and improve production capacity is a problem that needs to be solved. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention rationally designs a copper chemical mechanical polishing liquid. Through the specific selection and optimization of corrosion inhibitors in its formulation, a new copper chemical mechanical polishing liquid is obtained, enabling the polishing liquid to meet the usage requirements of combining the first two steps into one-step polishing, achieving the effects of simplifying the polishing process flow and increasing production capacity.

[0008] To achieve the above invention objectives, the present invention adopts the following technical solutions: A chemical mechanical polishing liquid, comprising 0.5% - 3% by mass of abrasive particles, 0.01% - 3% of corrosion inhibitor, 1% - 20% of complexing agent, 0.005% - 3% of surfactant, pH regulator, and 0.1% - 1% of oxidant, with the balance being solvent; The corrosion inhibitor is selected from one compound or a mixture of multiple compounds of formula (I);

[0009] In formula (I), X and Y are independently selected from O, S, CR1R2; R1 and R2 are independently selected from hydrogen, C1 - C12 alkyl, C6 - C20 aryl; R3 - R6 are independently selected from hydrogen, C1 - C12 alkyl, C1 - C12 alkoxy, C6 - C20 aryl.

[0010] In one embodiment, the chemical mechanical polishing liquid is a copper chemical mechanical polishing liquid.

[0011] In one embodiment, R1 and R2 are independently selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, phenyl, naphthyl, biphenyl.

[0012] In one embodiment, R3 - R6 are independently selected from hydrogen, methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, methyl, ethyl, propyl, butyl, pentyl, hexyl, phenyl, naphthyl, biphenyl.

[0013] In one embodiment, the compounds of formula (I) are selected from: .

[0014] In one embodiment, in the chemical mechanical polishing liquid, the mass fraction of the corrosion inhibitor is 0.1% - 2%, preferably 0.5% - 1.5%.

[0015] In one embodiment, the solvent comprises a first component, or a mixture of a first component and a second component; wherein the first component is water and the second component is an organic solvent.

[0016] Preferably, the second component is an aliphatic alcohol; more preferably, the second component is selected from methanol, ethanol, propanol, butanol, pentanol, hexanol, ethylene glycol, and glycerol.

[0017] Preferably, in the mixture of the first component and the second component, the mass ratio of the first component to the second component is 10 to 100:1, preferably 30 to 80:1, and more preferably 40 to 50:1.

[0018] In one embodiment, the abrasive particles are silica nanoparticles or alumina nanoparticles.

[0019] Preferably, the particle size of the abrasive particles is 30 to 250 nm, preferably 150 to 200 nm.

[0020] Preferably, in the chemical mechanical polishing liquid, the mass fraction of the abrasive particles is 0.5% to 2%, and more preferably 1% to 2%.

[0021] In one embodiment, the complexing agent is selected from one or more of arginine, lysine, glycine, citric acid, phosphoric acid, aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylenephosphonic acid, and hydroxyethylidene diphosphonic acid, and preferably glycine.

[0022] Preferably, in the chemical mechanical polishing liquid, the mass fraction of the complexing agent is 3% to 10%, and more preferably 5% to 8%.

[0023] In one embodiment, the surfactant is a polymeric anionic surfactant. Preferably, the surfactant is selected from one or more of a carboxylate-sulfonate copolymer, a carboxylate-sulfonate-nonionic copolymer, and a carboxylate-sulfonate-acrylate copolymer with a hydrophilic-lipophilic balance value (HLB value) of 15 to 30. Also preferably, the salt is a potassium salt and / or a sodium salt. Most preferably, the surfactant is a carboxylic acid-sulfonate copolymer kr-5000.

[0024] Preferably, in the chemical mechanical polishing liquid, the mass fraction of the surfactant is 0.1% to 2%, and more preferably 0.5% to 1.5%.

[0025] In one embodiment, the pH regulator is selected from one or more of H3PO4, HNO3, potassium hydroxide, and ammonium hydroxide. Preferably, the pH range of the chemical mechanical polishing liquid after adjustment is 5 to 8, and preferably, the pH range is 6 to 7.

[0026] In one embodiment, the oxidizing agent is hydrogen peroxide.

[0027] Preferably, in the chemical mechanical polishing liquid, the mass fraction of the oxidant is 0.2% to 0.8%, more preferably 0.3% to 0.5%.

[0028] The present invention also provides a preparation method of a chemical mechanical polishing liquid, and the method includes: (1) Mixing a solvent, abrasive particles, a corrosion inhibitor, a complexing agent, and a surfactant uniformly; (2) Adjusting the pH value to 5 to 8 with a pH regulator; (3) Adding an oxidant to obtain the chemical mechanical polishing liquid.

[0029] The present invention also provides a compound of formula (I):

[0030] In formula (I), X and Y independently selected from O, S, CR1R2; R1 and R2 are independently selected from hydrogen, C1-C12 alkyl, C6-C20 aryl; R3-R6 are independently selected from hydrogen, C1-C12 alkyl, C1-C12 alkoxy, C6-C20 aryl; The compound is not .

[0031] In one embodiment, R1 and R2 are independently selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, phenyl, naphthyl, biphenyl.

[0032] In one embodiment, R3-R6 are independently selected from hydrogen, methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, methyl, ethyl, propyl, butyl, pentyl, hexyl, phenyl, naphthyl, biphenyl.

[0033] In one embodiment, the compound of formula (I) is selected from:

[0034]

[0035] .

[0036] The present invention also provides a synthesis method of the compound of formula (I), including the following steps:

[0037] The compound of formula (II) reacts with ammonia or aqueous ammonia to obtain the compound of formula (III), and the compound of formula (III) reacts with nitrite to obtain the compound of formula (I).

[0038] The present invention also provides the use of the compound of formula (I) in the field of chemical mechanical polishing, especially in the field of chemical mechanical polishing of copper.

[0039] The present invention also provides the use of the chemical mechanical polishing liquid in the field of chemical mechanical polishing, especially in the field of chemical mechanical polishing of copper.

[0040] The present invention also provides a method for polishing copper, comprising the following steps: (1) Using the chemical mechanical polishing liquid of the present invention, removing copper on the surface of the substrate under high pressure and low pressure conditions in sequence and stopping at the barrier layer; (2) Removing the barrier layer, a part of the dielectric layer and a small amount of metallic copper with the barrier layer polishing liquid.

[0041] In one embodiment, the high pressure condition is 1.5 - 2.0 psi, and the low pressure condition is 0.5 - 1.0 psi.

[0042] In one embodiment, polishing is carried out for 1 - 3 min under high pressure conditions, preferably 0.5 - 1.5 min; then polishing is carried out for 1 - 3 min under low pressure conditions, preferably 0.5 - 1.5 min. Advantageous Effects

[0043] For the copper chemical mechanical polishing liquid of the present invention, a specific corrosion inhibitor is used. This corrosion inhibitor contains two benzotriazole groups, and the two benzotriazole groups are bridged by O, S or C, and the solvent is increased, so that when polishing under high pressure, not all benzotriazole groups are adsorbed on the surface of copper, thus obtaining a relatively fast polishing rate. When polishing under low pressure, more benzotriazole groups are adsorbed on the surface of copper, thus reducing the polishing rate, so that the copper chemical mechanical polishing liquid of the present invention can meet the use requirements of combining the first two steps of copper metal polishing into one step of polishing (first high pressure and then low pressure). Detailed Embodiments

[0044] The present invention is described in more detail below to facilitate the understanding of the present invention.

[0045] The experimental methods in the following examples are all conventional methods unless otherwise specified. For those not indicating specific techniques or conditions in the examples, they are carried out according to the techniques or conditions described in the literature in this field or according to the product specifications.

[0046] Synthesis Example: Step 1: Synthesis of 9,9,10,10 - tetramethyl - 9,10 - dihydroanthracene - 2,3,6,7 - tetramine

[0047] Add 240 mL of absolute ethanol to an autoclave, cool down to 10 °C, slowly introduce ammonia gas until saturation, then add 10.94 g of 2,3,6,7-tetrabromo-9,9,10,10-tetramethyl-9,10-dihydroanthracene. Then seal the autoclave, gradually heat up to room temperature and keep for 4 hours, then heat up to 60 °C and keep for 4 hours, then heat up to 100 °C and keep for 4 hours. Cool down, pour the reaction solution into water, filter, and after drying the obtained solid under reduced pressure, crystallize it with ethanol to obtain 3.4 g of a dark brown product. MS-ESI: 297.20 [M+H] + 。

[0048] Step 2: Synthesis of 5,5,11,11-tetramethyl-1,5,7,11-tetrahydroanthra[2,3-d:6,7-d']bis([1,2,3]triazole) In a three-necked flask, replace the air with nitrogen, add 100 mL of glacial acetic acid and 50 mL of water, then add 3.0 g of 9,9,10,10-tetramethyl-9,10-dihydroanthracene-2,3,6,7-tetraamine, heat up to reflux for 30 minutes, then cool down to 20 °C, and slowly add dropwise a solution prepared from 1.3 g of sodium nitrite and 10 mL of water. After addition, heat up to 60 °C for 2 hours. Cool down, adjust the pH value to 9 - 10 with 5% sodium hydroxide solution, filter, and after drying the obtained solid under reduced pressure, crystallize it with ethanol three times to obtain 0.9 g of the product. MS-ESI: 319.16 [M+H] + 。

[0049] Examples: The composition of the copper chemical mechanical polishing liquid is as shown in Table 1 below. Each part is by mass. Stir and mix all components evenly, and adjust the pH value to 6 with 10% potassium hydroxide aqueous solution. Add an oxidant before use and mix evenly. The oxidant used is hydrogen peroxide, and the amount of hydrogen peroxide (the amount of pure hydrogen peroxide) accounts for 0.4% of the total weight of the copper chemical mechanical polishing liquid. Among them, the surfactant kr-5000 is purchased from Shandong Kerry Chemical Co., Ltd.

[0050] Table 1: Composition of copper chemical mechanical polishing liquid for comparative examples and examples

[0051] The specific polishing conditions are as follows: The polishing machine is a 12” Reflexion LK, and the polishing pad is IC1010; the high polishing pressure is 2.0 psi, and the low polishing pressure is 1.0 psi; the rotation speeds of the polishing head and the polishing plate are 93 / 87 rpm, the flow rate of the polishing liquid is 300 mL / min, and the polishing time is 2 min. One-step polishing of copper metal is carried out (high-pressure polishing for 1 min first and then low-pressure polishing for 1 min). According to the real-time thickness change of the copper wafer during the polishing process and combined with a metal film thickness gauge, the polishing rate of the copper wafer under different pressure conditions can be calculated, as shown in Table 2 below: Table 2: Copper polishing rates of the copper chemical mechanical polishing liquids of the comparative examples and the examples

[0052] Generally, under high pressure, the polishing rate of copper is required to be greater than 6000 Å / min, and under low pressure, the polishing rate of copper is required to be in the range of 1500 - 2200 Å / min. The copper chemical mechanical polishing liquids of Examples 1 - 4 of the present invention using the compound shown in Formula (I) of the present invention as a corrosion inhibitor can control the copper polishing rates under high and low pressures within the required ranges. The copper chemical mechanical polishing liquid of Comparative Example 1 uses benzotriazole as a corrosion inhibitor and has an excessively high copper polishing rate under low pressure; the copper chemical mechanical polishing liquid of Comparative Example 2 uses biphenyltriazole as a corrosion inhibitor and has an excessively low polishing rate under high pressure and an excessively high polishing rate under low pressure. At the same time, when there is a small amount of fatty alcohol in the solvent, the low-pressure polishing rate increases.

[0053] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the method of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present invention.

Claims

1. A chemical mechanical polishing liquid, comprising abrasive grains in a mass percentage of 0.5% - 3%, a corrosion inhibitor in a mass percentage of 0.01% - 3%, a complexing agent in a mass percentage of 1% - 20%, a surfactant in a mass percentage of 0.005% - 3%, a pH regulator, and an oxidizing agent in a mass percentage of 0.1% - 1%, with the balance being a solvent; The corrosion inhibitor is selected from one compound or a mixture of multiple compounds of the formula (I) compounds; ； In formula (I), X and Y independently are selected from O, S, CR1R2; R1 and R2 independently are selected from hydrogen, C1 - C12 alkyl groups, and C6 - C20 aryl groups; R3 - R6 independently are selected from hydrogen, C1 - C12 alkyl groups, C1 - C12 alkoxy groups, and C6 - C20 aryl groups.

2. The chemical mechanical polishing liquid according to claim 1, wherein R1 and R2 independently are selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, phenyl, naphthyl, and biphenyl; R3 - R6 independently are selected from hydrogen, methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, methyl, ethyl, propyl, butyl, pentyl, hexyl, phenyl, naphthyl, and biphenyl.

3. The chemical mechanical polishing liquid according to claim 1, wherein, The formula (I) compounds are selected from: ； ； 。 4. The chemical mechanical polishing liquid according to claim 1, wherein The solvent includes a first component, or a mixture of a first component and a second component; wherein the first component is water and the second component is an organic solvent.

5. A formula (I) compound: ； In formula (I), X and Y independently are selected from O, S, CR1R2; R1 and R2 independently are selected from hydrogen, C1 - C12 alkyl groups, and C6 - C20 aryl groups; R3 - R6 independently are selected from hydrogen, C1 - C12 alkyl groups, C1 - C12 alkoxy groups, and C6 - C20 aryl groups; The compound is not .

6. The compound of formula (I) according to claim 5, characterized in that, The compound is selected from: 。 7. Use of the compound of formula (I) in the field of chemical mechanical polishing, characterized in that, The formula (I) compound is: ； In formula (I), X and Y independently are selected from O, S, CR1R2; R1 and R2 independently are selected from hydrogen, C1 - C12 alkyl groups, and C6 - C20 aryl groups; R3 - R6 independently are selected from hydrogen, C1 - C12 alkyl groups, C1 - C12 alkoxy groups, and C6 - C20 aryl groups.

8. Use of the chemical mechanical polishing liquid according to any one of claims 1 - 4 in the field of chemical mechanical polishing.

9. A copper polishing method, comprising the following steps: (1) Using the chemical mechanical polishing liquid according to any one of claims 1 - 4, sequentially removing copper on the substrate surface under high pressure and low pressure conditions and stopping on the barrier layer; (2) Removing the barrier layer, a part of the dielectric layer, and a small amount of metallic copper with a barrier layer polishing liquid.

10. The polishing method according to claim 9, wherein The high pressure condition is 1.5 - 2.0 psi, and the low pressure condition is 0.5 - 1.0 psi.

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