Cleaning solution for polished aluminum gate and preparation method and application of cleaning solution

Abstract

The invention relates to a cleaning solution for a polished aluminum gate, which comprises the following components in parts by weight: 1-10 parts of functional agent; 1-10 parts of a chelating agent; 0.1 to 0.5 part of an oxidizing agent; and 80-90 parts of ultrapure water. The invention further discloses a preparation method and application of the cleaning fluid. The molecular structure of the functional agent has amphipathy, one end is a polar hydrophilic group, and the other end is a non-polar hydrocarbon chain hydrophobic group; the oxidizing agent is subjected to oxidation reaction on the surface of the aluminum gate to generate a passivation layer of the oxide, and the functional agent forms physical adsorption on the surface of the aluminum gate to play a synergistic protection role and reduce the corrosion rate of the aluminum gate. The carboxyl in the chelating agent can also form a p-pi conjugated structure with benzene rings in the oxidizing agent and the functional agent, and a compact adsorption film is generated on the surface of the aluminum gate so as to inhibit corrosion.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor manufacturing processes, and particularly relates to a cleaning solution for aluminum gate polishing, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous development of integrated circuit process technology, in order to improve the integration of integrated circuits, the size of CMOS devices has been continuously reduced. When the size of CMOS devices is reduced to less than 45 nm, according to the proportional reduction requirements of Moore's law, the CMOS gate dielectric will become thinner. However, traditional polysilicon gates have problems such as short channel effect (SCE), drain induced barrier lowering (DIBL), hot carrier injection (HCI), and gate oxide leakage. To overcome these problems, the semiconductor industry uses metal gates to replace polysilicon gates to form a metal gate / high-K dielectric gate structure for CMOS devices.

[0003] After using a metal gate to replace a polysilicon gate, the remote Coulomb scattering effect can be eliminated, and the problem of the decrease in the channel carrier mobility caused by surface soft phonon scattering in the high-K gate dielectric can be effectively suppressed. Metallic aluminum is a gate material that has been studied earlier. Because aluminum has a very low resistance, does not react with oxides, and can effectively transfer the control voltage to the gate oxide layer to control the current in the channel, it has become a new star in gate materials.

[0004] Chemical mechanical polishing (CMP) is the main technology for wafer planarization. Metal chemical mechanical polishing solutions usually contain abrasive particles, complexing agents, metal corrosion inhibitors, oxidants, etc. Among them, the abrasive particles are mainly silica, aluminum oxide, cerium dioxide, polymer abrasive particles, etc. After the metal CMP process, the wafer surface will be contaminated by metal ions and the abrasive particles in the polishing solution itself. These contaminations are likely to cause electronic device noise, deteriorate the electrical property consistency, and seriously affect the device performance. Moreover, the residues of metal ions and abrasive particles will both affect the flatness of the wafer surface, which may reduce the device performance and affect subsequent processes or the operation of the device. Therefore, it is very necessary to remove the metal ions, metal corrosion inhibitors, and abrasive particles remaining on the wafer surface after the metal CMP process, improve the hydrophilicity of the wafer surface, and reduce surface defects.

[0005] The abrasive particles for aluminum gate CMP are mainly silica sol particles, which have both colloidal and nano properties and have a strong adhesion to the aluminum gate. The main component SiO2 forms new Si-O-Al covalent bonds with the broken chemical bonds on the aluminum gate surface, causing the silica sol to adsorb on the aluminum gate surface and becoming one of the main objects to be cleaned after aluminum gate CMP. Summary of the Invention

[0006] Technical problem solved by the present invention: After the metal CMP process, remove the metal ions, metal corrosion inhibitors and abrasive particles remaining on the wafer surface, especially silica sol particles, which have strong adhesion to aluminum gates.

[0007] In view of the technical problems existing in the prior art, the present invention provides a cleaning solution for aluminum gates after polishing that is safe, environmentally friendly, efficient and has almost no corrosion to semiconductor chips. It can maintain extremely excellent cleaning efficiency only under the pure immersion process conditions without the need for ultrasonic process cooperation. It should be noted that in the present invention, unless otherwise specified, the specific meaning of "including" related to component definition and description includes both the open "including", "containing" and their similar meanings, and also the closed "consisting of" and their similar meanings.

[0008] In order to solve the above-mentioned existing technical problems, the present invention adopts the following solutions:

[0009] A cleaning solution for aluminum gates after polishing, characterized in that, calculated by weight, it includes the following components:

[0010] Functional agent 1 - 10 parts;

[0011] Chelating agent 1 - 10 parts;

[0012] Oxidizing agent 0.1 - 0.5 parts;

[0013] Ultra-pure water 80 - 90 parts;

[0014] The functional agent is a compound containing a non-polar hydrocarbon chain hydrophobic group.

[0015] Further, the functional agent is one or more of Alpha-(dinonylphenyl)-ω-hydroxy poly(oxy-1,2-ethylene), 5-tetradecyldihydro-2(3H)-furanone, (S)-N-(4-dodecylbenzenesulfonyl)pyrrolidine-2-carboxamide.

[0016] Further, the chelating agent is a polyhydroxy compound.

[0017] Further, the chelating agent is one or more of Galβ(1-3)[Neu5Acα(2-6)]GalNAc-α-propylamine, 2-amino-9-((2R,3R,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-3,9-dihydro-6H-purin-6-thione hydrate, 2-amino-9-((2R,3R,4R,5R)-4-hydroxy-5-(hydroxymethyl)-3-methoxytetrahydrofuran-2-yl)-8-methyl-3,9-dihydro-6H-purin-6-one, 4-amino-1-((2S,4S,5R)-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)pyrimidin-2(1H)-one, (2R,3R,4S,5R)-5-(6-amino-9H-purin-9-yl)-4-fluoro-2-(hydroxymethyl)tetrahydrofuran-3-ol.

[0018] Further, the oxidizing agent is an organic peroxide.

[0019] Further, the oxidizing agent is one or more of 2-isopropylnaphthalene hydroperoxide, (E)-5-phenyl-4-pentene hydroperoxide, diisopropylbenzene hydroperoxide.

[0020] Further, the ultrapure water is deionized water with a resistivity ≥ 18 MΩ.

[0021] The present invention also discloses a preparation method of a cleaning solution for post-aluminum gate polishing, which is characterized by comprising the following steps:

[0022] Step 1: Weigh each component in their respective amounts.

[0023] Step 2: Stir all components except ultrapure water at room temperature until all materials are completely dissolved, and finally add ultrapure water and mix evenly at 30-60 °C to obtain the cleaning solution for post-aluminum gate polishing.

[0024] The present invention also discloses the use of a cleaning solution for post-aluminum gate polishing in the cleaning after aluminum gate polishing.

[0025] The present invention also discloses a using method of a cleaning solution for post-aluminum gate polishing, which is characterized by comprising the following steps:

[0026] Step 1: Dilute the cleaning solution for post-aluminum gate polishing 30-70 times with ultrapure water, then soak the chip at room temperature for 60-90 seconds to obtain a soaked chip.

[0027] Step 2: Rinse the soaked chip with ultrapure water to complete the cleaning of the chip.

[0028] In the cleaning liquid system of the present invention, in order to further optimize the effect, each component can be optimized: 3-7 parts of functional agent; 3-7 parts of chelating agent; 0.2-0.4 parts of oxidant; 82-88 parts of ultrapure water.

[0029] In the present invention, the functional agent is Alpha-(dinonylphenyl)-ω-hydroxypoly(oxy-1,2-ethylene).

[0030] In the present invention, the chelating agent is Galβ(1-3)[Neu5Acα(2-6)]GalNAc-α-propylamine.

[0031] In the present invention, the oxidant is 2-isopropylnaphthalene hydroperoxide.

[0032] In the present invention, the functional agent has a special effect:

[0033] The functional agent is beneficial to the dispersion of silica sol particles after polishing, making them evenly distributed, preventing aggregation, gelation, reducing the generation of scratches and enhancing stability. On the one hand, the functional agent can be preferentially adsorbed on the surface of the aluminum gate, wrapping impurities such as residual silica sol particles, preventing the introduction of new contamination. After adding the functional agent, the convex part of the aluminum gate surface corrodes faster, and the concave part corrodes slower. There is a corrosion rate difference between the convex and concave parts of the aluminum gate surface, and the non-uniform corrosion also improves the surface roughness. On the other hand, the functional agent molecules can penetrate between the silica sol particles and the aluminum gate surface, increasing the distance between the silica sol particles and the aluminum gate surface, and suspending the silica sol particles in the cleaning liquid.

[0034] In the present invention, the chelating agent has a unique effect:

[0035] The chelating agent can be ionized in aqueous solution, and the ionized OH - can not only maintain the pH value of the cleaning liquid, but also react with Al to form Al(OH)3. Al(OH)3 is unstable and easily decomposes into Al 3+ Al 3+It can form soluble chelates with silica sol particles, breaking the Si-O-Al balance. That is, the hydroxyl groups on the surface of silica sol particles react with the chelating agent to form silicate anions. The silicate anions react with silicon, reducing the energy on the surface of SiO2, causing SiO2 to detach from the aluminum gate surface, thereby achieving the purpose of removing silica sol particles. At the same time, the electrostatic repulsion between the silica sol particles and the aluminum gate surface increases, enhancing the ease of cleaning of the silica sol particles and reducing the probability of re-adsorption. On the other hand, the hydroxyl groups in the chelating agent can form hydrogen bonds with the functional agent to form a large hydrogen bond network, and can also form Si-O-H type hydrogen bonds with the silica sol particles, forming a monolayer adsorption on the surface of the silica sol particles, thereby encapsulating the silica sol particles to prevent secondary deposition. At the same time, the carboxyl groups in the chelating agent can also form a p-π conjugate structure with the oxidant and the benzene ring in the functional agent, generating a dense adsorption film on the aluminum gate surface to inhibit corrosion.

[0036] In the present invention, the oxidant has a unique role:

[0037] After adding this oxidant, the surface of the aluminum gate is first oxidized, forming a dense Al2O3·3H2O passivation film on its surface, and a large number of porous oxide layers will be formed on the Al2O3·3H2O passivation film. The OH ionized by the chelating agent - converts the Al2O3·3H2O passivation film into Al(OH)3, and then into Al(OH) 4- , and further reacts to form a soluble chelate {Al[R-(NH2)2]3}3, which is washed by the cleaning solution to achieve the purpose of removing aluminum ions. The chelating agent can also dissolve part of the Al2O3·3H2O passivation film and the loose and porous oxide layer on the passivation film structure, achieving the effect of removing the oxide film.

[0038] In the present invention, in the preparation method of the cleaning solution, ultrapure water is added in step 2 and mixed evenly at 50 °C.

[0039] In the present invention, in the usage method of the cleaning solution, the number of rinsing times described in step 2 is two or more.

[0040] The present invention provides a cleaning solution for aluminum gate polishing, its preparation method and application, which have the following beneficial effects:

[0041] 1. The functional agent in the present invention has amphiphilicity, with a polar hydrophilic group at one end and a non-polar hydrocarbon chain hydrophobic group at the other end. A large number of functional agent molecules can self-aggregate inside the cleaning solution. The hydrophobic groups gather together to form the core of the molecule, and the hydrophilic groups face outwards to contact water to form the molecular shell, and then form many micelles. These micelles form physical adsorption on the aluminum gate surface, playing a protective role on the aluminum gate surface.

[0042] 2. In the present invention, the oxidant undergoes an oxidation reaction on the surface of the aluminum gate to form a passivation layer of oxide, which plays a synergistic protective role with the physical adsorption formed by the functional agent on the surface of the aluminum gate, reducing the corrosion rate of the aluminum gate.

[0043] Therefore, the cleaning solution of the present invention has very good application prospects and the potential for large-scale industrial promotion in the field of semiconductor chip cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 : An optical microscope picture of the surface of the chip cleaned with the cleaning solution prepared in Comparative Example 1, magnified 50 times.

[0045] Figure 2 : An optical microscope picture of the surface of the chip cleaned with the cleaning solution prepared in Example 1, magnified 50 times. DETAILED DESCRIPTION OF THE INVENTION

[0046] The present invention will be further described below in conjunction with specific examples and the accompanying drawings:

[0047] Table 1 Examples 1-9

[0048]

[0049]

[0050] Table 2 Comparative Examples 1-4

[0051]

[0052] Table 3 Test Data

[0053]

[0054]

[0055] Regarding the preparation method of the cleaning solution for aluminum gate after polishing of the present invention, it comprises the following steps:

[0056] Step 1: Weigh each component in their respective amounts;

[0057] Step 2: Add all components except ultrapure water to a container and stir at room temperature of 25 °C until all materials are completely dissolved, and finally add ultrapure water and mix evenly to obtain the cleaning solution for post-polishing of the aluminum gate.

[0058] Regarding the usage method of the cleaning solution for aluminum gate after polishing of the present invention, it comprises the following steps:

[0059] Step 1: Dilute the cleaning solution for post-CMP of the aluminum gate 60 times with ultrapure water, then soak the chip at room temperature of 25 °C for 70 seconds to obtain the soaked chip;

[0060] Step 2: Rinse the soaked chip twice with ultrapure water, and the cleaning of the chip is completed.

[0061] Regarding performance testing and description:

[0062] The test methods for cleaning effect and metal corrosion are as follows:

[0063] The test method for cleaning effect of Performance 1 is as follows:

[0064] Step 1: Dilute the cleaning agent after the chip aluminum gate CMP with ultrapure water by 30 times, then soak the semiconductor chip with this aqueous solution at room temperature for 60 seconds to obtain the soaked semiconductor chip;

[0065] Step 2: Rinse the soaked chip at least twice with ultrapure water, and then dry the surface of the semiconductor chip with nitrogen, and the cleaning process of the semiconductor chip is completed.

[0066] The ultrapure water used in Step 1 and Step 2 is deionized water with a resistance of at least 18 MΩ.

[0067] The test method for metal corrosion of Performance 2 is as follows:

[0068] The ICP-MS method (Inductively Coupled Plasma Mass Spectrometry) is used to test the corrosion performance of different cleaning liquids on metals. The specific test method is as follows: Immerse a 2×2 cm 2 aluminum sheet in the cleaning liquid at room temperature for 2 hours, then measure the aluminum ion concentration in the cleaning liquid by ICP-MS method and calculate the aluminum corrosion rate, with the unit of

[0069] Analysis and explanation of the test results:

[0070] Based on Table 3, it can be seen that the cleaning liquid of the embodiment of the present invention has a lower corrosion rate on the aluminum gate and almost no residue, while the corrosion rate of the comparative example is larger. Specifically:

[0071] Compared with Example 1, the chelating agent single-6-O-(p-toluenesulfonyl)-α-cyclodextrin used in Comparative Example 1 has a polyhydroxy structure. Since the chelating agent does not contain a carboxyl group, the p-π conjugation between the chelating agent and the functional agent in the component is reduced, and the inhibitory effect of the adsorption film is weakened, resulting in a larger corrosion rate;

[0072] Comparative Example 2 uses conventional hydrogen peroxide as an oxidant. Since the structure does not contain a benzene ring, the ability to form an adsorption film while removing aluminum ions is weakened, resulting in a larger corrosion rate;

[0073] Comparative Example 3 uses a functional agent with a carbon chain of 5. The hydrophobic interaction of the long-chain substance relies on van der Waals forces. Since the carbon chain is short, the van der Waals forces are weak, resulting in poor wettability;

[0074] In Comparative Example 4, since no functional agent was added and only the chelating agent Galβ(1-3)[Neu5Acα(2-6)]GalNAc-α-propylamine was added, the synergistic effect between the functional agent and the chelating agent in the components was reduced, resulting in a worse effect of removing particles and inhibiting corrosion.

[0075] A further comparison and illustration are made through the accompanying drawings of the specification:

[0076] Figure 1 An optical microscope picture of the surface of the chip magnified 50 times after being cleaned with the cleaning solution prepared in Comparative Example 1; Figure 2 An optical microscope picture of the surface of the chip magnified 50 times after being cleaned with the cleaning solution prepared in Example 1.

[0077] From Figure 1 and Figure 2 comparison, it can be seen that the surface of the chip after being cleaned with the cleaning solution prepared in Example 1 of the present invention is smooth and clean, without residue and has a good cleaning effect. The surface of the chip after being cleaned with the cleaning solution prepared in Comparative Example 1 of the present invention has obvious particle residues and corrosion appears.

[0078] The present invention has been described exemplarily above in combination with the embodiments and the drawings. Obviously, the implementation of the present invention is not limited by the above-mentioned methods. As long as various improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. An aluminum gate post - polishing cleaning solution, characterized in that, Calculated by weight parts, it comprises the following components: Functional agent: 1 - 10 parts; Chelating agent: 1 - 10 parts; Oxidizing agent: 0.1 - 0.5 part; Ultra-pure water: 80 - 90 parts; The functional agent is a compound containing a non-polar hydrocarbon chain hydrophobic group.

2. The post - aluminum - gate polishing cleaning solution according to claim 1, characterized in that: The functional agent is one or more of Alpha-(dinonylphenyl)-ω-hydroxy poly(oxy-1,2-ethylene), 5-tetradecyldihydro-2(3H)-furanone, (S)-N-(4-dodecylbenzenesulfonyl)pyrrolidine-2-carboxamide.

3. The post - aluminum - gate polishing cleaning solution according to claim 1, wherein: The chelating agent is a polyhydroxy compound.

4. The cleaning liquid for aluminum gate after polishing according to claim 3, wherein: The chelating agent is one or more of Galβ(1-3)[Neu5Acα(2-6)]GalNAc-α-propylamine, 2-amino-9-((2R,3R,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-3,9-dihydro-6H-purin-6-thione hydrate, 2-amino-9-((2R,3R,4R,5R)-4-hydroxy-5-(hydroxymethyl)-3-methoxytetrahydrofuran-2-yl)-8-methyl-3,9-dihydro-6H-purin-6-one, 4-amino-1-((2S,4S,5R)-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)pyrimidin-2(1H)-one, (2R,3R,4S,5R)-5-(6-amino-9H-purin-9-yl)-4-fluoro-2-(hydroxymethyl)tetrahydrofuran-3-ol.

5. The post - aluminum - gate polishing cleaning solution according to claim 1, wherein: The oxidizing agent is an organic peroxide.

6. The post - aluminum - gate polishing cleaning solution according to claim 5, wherein: The oxidizing agent is one or more of 2-isopropylnaphthalene hydroperoxide, (E)-5-phenyl-4-pentene hydroperoxide, diisopropylbenzene hydroperoxide.

7. The post - aluminum - gate polishing cleaning solution according to claim 1, characterized in that: The ultra-pure water is deionized water with a resistance ≥ 18 MΩ.

8. A method for preparing the aluminum gate post-polishing cleaning solution according to any one of claims 1-7, characterized in that, It comprises the following steps: Step 1: Weigh each component in their respective dosages; Step 2: Stir all components except ultra-pure water at room temperature until all materials are completely dissolved, and finally add ultra-pure water and mix evenly to obtain the cleaning solution for aluminum gate polishing.

9. Use of the cleaning solution for aluminum gate polishing according to any one of claims 1 - 7 in the cleaning after aluminum gate polishing.

10. A method for using the cleaning solution for aluminum gate after polishing according to claim 9, characterized in that, It comprises the following steps: Step 1: Dilute the cleaning solution for aluminum gate polishing 30 - 70 times with ultra-pure water, then soak the chip at room temperature for 60 - 90 seconds to obtain the soaked chip; Step 2: Rinse the soaked chip with ultra-pure water to complete the cleaning of the chip.

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