A cleaning liquid composition used in semiconductor wafer cleaning process

Abstract

The invention discloses a cleaning fluid composition for semiconductor wafer cleaning process, according to total mass percentage 100%, including the following raw material components: 0.1 40% compound of hydroxylamine or hydroxylamine salt, 0.1 10% organic acid, 0.1 30% quaternary ammonium base, 0 20% alkanolamine, and the remainder is ultrapure water. The cleaning fluid composition of the present invention, it can play the cerium oxide of partial reduction surface adsorption by the compound of hydroxylamine or hydroxylamine salt so as to weaken the adsorption power of cerium oxide particles and silicon oxide surface, and the addition of organic acid can form a complex bond with the cerium ion on cerium oxide surface so as to break the combination of cerium oxide particles and silicon oxide surface to reach the cerium oxide nanoparticles adsorbed on the removal silicon oxide surface, and the cleaning fluid is in alkaline environment when used, and will not cause damage to silicon oxide and silicon nitride surfaces.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a cleaning liquid composition used in a semiconductor wafer cleaning process, for removing cerium oxide particles and other contaminants on the wafer surface after chemical mechanical polishing in a semiconductor wafer manufacturing process. Background Art

[0002] In the wafer manufacturing process, chemical mechanical polishing (CMP) has become the main technology for flattening semiconductor wafers. Chemical mechanical polishing liquid is generally composed of abrasive particles and chemical additives, which are used to provide mechanical and chemical effects during the wafer polishing process, and work together to achieve precise flattening of the wafer surface. Among them, the abrasive particles mainly include silicon dioxide, aluminum oxide, ceria and other abrasive particles according to their use. During the chemical mechanical planarization grinding process, a large number of fine abrasive particles and chemical additives in the grinding liquid, as well as debris peeled off by wafer wear, may adhere to the wafer surface. Common contaminants on wafers after grinding are metal ions, organic compounds or abrasive particles. If there is no effective cleaning procedure to remove the above contaminants, it will affect the subsequent process and reduce the yield and reliability of the components. The cleaning process during or after the CMP process has become a key technology for the successful application of CMP in semiconductor processes.

[0003] Cerium oxide polishing slurries containing cerium oxide abrasive particles are used for oxide planarization in shallow trench isolation (STI) processes due to cerium oxide's oxidizing properties. In a typical STI process, a shallow trench is formed by first depositing and patterning silicon nitride as a mask, followed by etching the silicon substrate. Silicon oxide is then deposited in the trench to isolate the silicon. The cerium oxide polishing slurry then removes excess silicon oxide and settles on the silicon nitride layer, completing the wafer STI process.

[0004] After polishing with ceria slurries, silicon oxide and silicon nitride surfaces are often strongly adsorbed by nanoscale ceria particles, in addition to common organic residues, metal ions, and silicon-containing polishing byproducts. Due to their strong adsorption to wafer surfaces, removing ceria particles without damaging the surfaces is a pressing challenge for those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a cleaning solution composition for use in a semiconductor wafer cleaning process.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a cleaning liquid composition for use in the semiconductor wafer cleaning process, wherein the cleaning liquid composition comprises the following raw material components based on the total mass percentage of 100%: 0.1-40% of a hydroxylamine or hydroxylamine salt compound, 0.1-10% of an organic acid, 0.1-30% of a quaternary ammonium base, 0-20% of an alkanolamine, and the remainder is ultrapure water.

[0007] As a specific embodiment, the hydroxylamine or hydroxylamine salt compound is selected from one or more combinations of hydroxylamine, hydroxylamine hydrochloride, hydroxylamine sulfate, hydroxylamine nitrate, hydroxylamine phosphate, hydroxylamine acetate, diethylhydroxylamine, N-methylhydroxylamine hydrochloride, and N,N-dimethylhydroxylamine hydrochloride.

[0008] In actual operation, the hydroxylamine or hydroxylamine salt compound is selected from one or more of hydroxylamine, hydroxylamine hydrochloride, hydroxylamine sulfate, hydroxylamine nitrate and hydroxylamine phosphate. The dosage of the hydroxylamine or hydroxylamine salt compound is selected from any one of the ranges of 0.1-40%, 0.1-30%, 0.1-20%, 0.1-10%, 0.1-5%, 0.5-10%, 0.5-5%, 1-10% and 1-5%, preferably between 0.1-10%, more preferably between 1-5%.

[0009] As a specific embodiment, the quaternary ammonium base is selected from tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tributylmethylammonium hydroxide, benzyltrimethylammonium hydroxide, choline hydroxide, ethyltrimethylammonium hydroxide, tris (2-hydroxyethyl) methylammonium hydroxide, diethyldimethylammonium hydroxide, or one or more combinations thereof.

[0010] In actual operation, the quaternary ammonium base is preferably one of tetramethylammonium hydroxide and choline hydroxide or a mixture of the two. The dosage of the quaternary ammonium base is selected from any one of the ranges of 0.1-30%, 0.1-20%, 0.1-10%, 0.1-5%, 1-30%, 1-20%, 1-10%, 1-5%, 5-30%, 5-20%, and 5-10%; the dosage is preferably 1-20%, more preferably 5-10%.

[0011] As a specific embodiment, the organic acid includes but is not limited to one or more of acetic acid, propionic acid, butyric acid, malonic acid, succinic acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, tartaric acid, oxalic acid, malic acid, citric acid, aconitic acid, propane-1,2,3-tricarboxylic acid, trimesic acid, ascorbic acid, benzoic acid, salicylic acid, caffeic acid, 3,4,5-trihydroxybenzoic acid, gluconic acid, lactic acid, glycolic acid, mandelic acid, maltobionic acid, ethylenediaminetetraacetic acid, cyclohexanediaminetetraacetic acid, pyromellitic acid, mellitic acid, glycine, alanine, valine, leucine, isoleucine, phenylalanine, tryptophan, tyrosine, aspartic acid, histidine, asparagine, glutamic acid, lysine, glutamine, arginine, serine, threonine, cysteine, proline, and catechol. The organic acid is preferably selected from one or more of citric acid, ethylenediaminetetraacetic acid, gluconic acid and catechol; more preferably selected from one or a combination of citric acid and gluconic acid; more preferably selected from gluconic acid.

[0012] Here, the dosage of the organic acid is selected from any one range of 0.1-20%, 0.1-10%, 0.1-5%, 0.1-3%, 0.5%-3%, 0.5-5%, 0.5-10%, 1-5%, 1-3%, 1-10%, 3-5%, 3-10%; preferably 0.1-5%, more preferably 0.5-5%.

[0013] As a specific embodiment, the alkanolamine is selected from one or more of ethanolamine, diethanolamine, methylethanolamine, triethanolamine, isopropanolamine, isobutanolamine, diglycolamine, methyldiethanolamine, dimethylethanolamine, and hydroxyethylethylenediamine. The addition amount of the alkanolamine is selected from any one of the following ranges: 0-20%, 0.1-10%, 0.1-5%, 1-10%, 1-20%, 1-5%, 0.5%-20%, 0.5-10%, 0.5-5%, 3-15%, 3-10%, and 3-5%, preferably 1-10%, and more preferably 0.5-5%.

[0014] As a specific embodiment, the pH value of the cleaning liquid composition is greater than 9, preferably the pH value is greater than 11, and more preferably the pH value is greater than 13.

[0015] A surfactant may also be added to the cleaning liquid composition. Optional surfactants include cationic surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants. Nonionic surfactants are preferred, specifically selected from one or more of long-chain fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid polyoxyethylene esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, and polyethers. The amount of the surfactant added is selected from any one of 0.001-1%, 0.001-0.5%, 0.001-0.1%, 0.001-0.05%, 0.01-1%, 0.01-0.5%, 0.01-0.1%, 0.05-0.5%, and 0.05-0.2%, preferably 0.01-0.5%, and more preferably 0.01-0.1%.

[0016] Furthermore, in some embodiments, the cleaning solution does not contain oxidants such as hydrogen peroxide; does not contain abrasive particles, silicon-containing compounds; does not contain inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid; does not contain inorganic bases such as potassium hydroxide, sodium hydroxide, nor does it contain ammonia water, alcohol amines, organic amines, and may not add surfactants, fluorides, chlorides, bromides, sulfur-containing compounds, various organic solvents and metal-containing compounds.

[0017] Furthermore, in some embodiments, the cleaning solution does not contain a surfactant.

[0018] The cleaning liquid composition is first diluted with water when used, with a dilution ratio between 1:1 and 1:200, preferably between 1:10 and 1:100, and more preferably between 1:20 and 1:60.

[0019] During use of the cleaning liquid composition, the cleaning temperature is controlled at 20-60°C, preferably 20-30°C.

[0020] The cleaning liquid of the present invention can be used to clean wafers in a cleaning machine or on a polishing plate after polishing. It can also be used to clean the flattened wafer surface on a chemical mechanical planarization machine or on an independent cleaning machine.

[0021] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: the cleaning liquid composition of the present invention can partially reduce the cerium oxide adsorbed on the surface through the hydroxylamine or hydroxylamine salt compound, thereby weakening the adsorption force between the cerium oxide particles and the silicon oxide surface, and the addition of the organic acid can form a complex bond with the cerium ions on the cerium oxide surface, thereby breaking the bond between the cerium oxide particles and the silicon oxide surface to achieve the effect of removing the cerium oxide nanoparticles adsorbed on the silicon oxide surface. In addition, the cleaning liquid is in an alkaline environment during use and will not cause damage to the silicon oxide and silicon nitride surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attachment Figure 1 The surface conditions of the silicon oxide wafers of samples 15 to 21 before cleaning were observed under the atomic force microscope Nanoview1000AFM;

[0023] Attachment Figure 2 This is the surface condition of the cleaned silicon oxide wafer of sample 15 observed under the atomic force microscope Nanoview1000AFM;

[0024] Attachment Figure 3 This is the surface condition of the cleaned silicon oxide wafer of sample 16 observed under the atomic force microscope Nanoview1000AFM;

[0025] Attachment Figure 4 This is the surface condition of the cleaned silicon oxide wafer of sample 17 observed under the atomic force microscope Nanoview1000AFM;

[0026] Attachment Figure 5 This is the surface condition of the cleaned silicon oxide wafer of sample 18 observed under the atomic force microscope Nanoview1000AFM;

[0027] Attachment Figure 6 This is the surface condition of the cleaned silicon oxide wafer of sample 19 observed under the atomic force microscope Nanoview1000AFM;

[0028] Attachment Figure 7 This is the surface condition of the cleaned silicon oxide wafer of sample 20 observed under the atomic force microscope Nanoview1000AFM;

[0029] Attachment Figure 8 This is the surface condition of the cleaned silicon oxide wafer of sample 21 observed under the atomic force microscope Nanoview1000AFM;

[0030] Attachment Figure 9 Surface conditions of the comparative silicon oxide wafers of samples 22 to 26 before cleaning observed under the atomic force microscope Nanoview1000AFM;

[0031] Attachment Figure 10 This is the surface condition of the cleaned silicon oxide wafer of sample 22 observed under the atomic force microscope Nanoview1000AFM;

[0032] Attachment Figure 11 This is the surface condition of the cleaned silicon oxide wafer of sample 23 observed under the atomic force microscope Nanoview1000AFM;

[0033] Attachment Figure 12 The surface condition of the cleaned silicon oxide wafer of sample 24 observed under the atomic force microscope Nanoview1000AFM;

[0034] Attachment Figure 13 The surface condition of the cleaned silicon oxide wafer of sample 25 observed under the atomic force microscope Nanoview1000AFM;

[0035] Attachment Figure 14 The silicon oxide surface was observed using the atomic force microscope Nanoview1000AFM after sample 26 was cleaned.

[0036] Attachment Figure 15 This is the surface condition of the silicon oxide wafer after being cleaned with clean water, as observed under the atomic force microscope Nanoview1000AFM;

[0037] Attachment Figure 16 This is the surface condition of the silicon oxide wafer after being cleaned with the sample 22 stock solution observed under the atomic force microscope Nanoview1000AFM;

[0038] Attachment Figure 17 The surface condition of the cleaned silicon oxide wafer observed under the atomic force microscope Nanoview1000AFM after using sample 22 diluted 1:10;

[0039] Attachment Figure 18 The surface condition of the cleaned silicon oxide wafer observed under the atomic force microscope Nanoview1000AFM after using sample 22 diluted 1:20;

[0040] Attachment Figure 19 The surface condition of the cleaned silicon oxide wafer observed under the atomic force microscope Nanoview1000AFM after using sample 22 diluted 1:30;

[0041] Attachment Figure 20 This is the surface condition of the cleaned silicon oxide wafer observed under the atomic force microscope Nanoview1000AFM after using sample 22 diluted 1:50. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0043] A cleaning liquid composition for use in a semiconductor wafer cleaning process comprises the following raw material components, calculated based on 100% total mass percentage: 0.1-40% of a hydroxylamine or hydroxylamine salt compound, 0.1-10% of an organic acid, 0.1-30% of a quaternary ammonium base, 0-20% of an alkanolamine, and the remainder being ultrapure water.

[0044] The cleaning liquid composition can be prepared by simply mixing the raw materials at room temperature. After mixing, the process further includes shaking and filtering. The total mass fraction of the raw materials in the cleaning liquid is 100%, and the amount of water used is calculated to make up the total mass fraction of the raw materials. Some raw materials are present in the form of aqueous solutions, such as a 25% aqueous methylammonium hydroxide solution and a 50% aqueous choline hydroxide solution. In the following examples, the weight ratios of the raw materials are based on the net weight of the raw materials.

[0045] 1. Dissolution of cerium oxide particles in different cleaning solutions

[0046] The following provides a cleaning liquid composition for use in a semiconductor wafer cleaning process. The components and contents of the cleaning liquid composition are shown in Table 1, and the contents of each component are expressed in percentage by mass.

[0047] Table 1

[0048]

[0049]

[0050] We measured the amount of cerium oxide dissolved in each cleaning liquid composition obtained in Table 1. The measurement method is as follows:

[0051] At 50°C, 0.01 g of cerium oxide particles with an average particle size of 100 nm were added to 50 mL of each cleaning solution. The mixture was stirred thoroughly and then ultrasonically shaken for 2 hours to dissolve the cerium oxide particles. The supernatant was then centrifuged at 3500 rpm for 10 minutes. The amount of cerium oxide dissolved by the cleaning solution was estimated from the cerium ion concentration in the supernatant. The cerium ion concentration was measured using an Agilent 7900 ICP-MS.

[0052] From the results in Table 1, we can see that the solubility of cerium oxide using quaternary ammonium base or hydroxylamine alone is very low, as shown in Samples 1 and 2. Even adding hydroxylamine or an organic acid to choline hydroxide does not significantly improve the solubility of cerium oxide, as shown in Samples 3 and 8. However, the addition of an organic acid to choline hydroxide and hydroxylamine simultaneously significantly increases the solubility of cerium oxide, as shown in Samples 4 to 7. These results indicate that in alkaline solutions, hydroxylamine is capable of partially reducing cerium oxide but cannot significantly dissolve it. The addition of an organic acid significantly increases its complexing ability with cerium oxide, thereby increasing the solubility of cerium oxide.

[0053] 2. Effect of cleaning solution component concentration on the dissolution amount of cerium oxide particles

[0054] The following provides a cleaning liquid composition for use in a semiconductor wafer cleaning process. The components and contents of the cleaning liquid composition are shown in Table 2, and the contents of each component are expressed in percentage by mass.

[0055] Table 2

[0056]

[0057] We measured the amount of cerium oxide dissolved in each cleaning liquid composition obtained in Table 2. The measurement method is as follows:

[0058] 0.01 g of cerium oxide particles with an average particle size of 50 nm were added to 50 mL of each cleaning solution at room temperature and stirred at 500 rpm for 30 minutes to dissolve the cerium oxide. The amount of cerium oxide dissolved by the cleaning solution was estimated from the cerium ion concentration in the supernatant. The cerium ion concentration was measured using an Agilent 7900 ICP-MS.

[0059] From Table 2, we can see from the dissolution amounts detected for samples 9, 10, 11, and 14 that an increase in the concentration of hydroxylamine sulfate can increase the dissolution amount of cerium oxide in the cleaning solution composition; from the dissolution amounts detected for samples 12 and 13, we can see that an increase in the concentration of gluconic acid does not significantly increase the dissolution amount of cerium oxide.

[0060] 3. Effect of cleaning solution concentration on solution pH and removal ability of cleaning solutions with different pH values ​​on cerium oxide particles adsorbed on silicon oxide surface

[0061] The following provides a cleaning liquid composition for use in a semiconductor wafer cleaning process. The components and contents of the cleaning liquid composition are shown in Table 3, and the contents of each component are expressed in percentage by mass.

[0062] Table 3

[0063]

[0064] The ability of each example in Table 3 to remove cerium oxide particles adsorbed on the silicon oxide surface was tested using the following test method:

[0065] A silicon oxide wafer was immersed in a cerium oxide polishing solution at 500 rpm for 5 minutes, then rinsed with deionized water for 1 minute to obtain a silicon oxide wafer with cerium oxide nanoparticles adsorbed on its surface. The wafer was then rinsed in the aforementioned cleaning solutions at 500 rpm for 5 minutes, rinsed with deionized water for 1 minute, and then dried with nitrogen. The ability to remove cerium oxide nanoparticles from the silicon oxide surface was observed using an atomic force microscope (AFM) called Nanoview 1000.

[0066] The surface condition of silicon oxide before cleaning is shown in Figure 1 The surface conditions of silicon oxide after cleaning of samples 15 to 21 are shown in Figure 2. Figures 2 to 8 From this we can see that the cleaning solution sample 15 with a lower pH has only a partial ability to remove cerium oxide particles, and only removes the larger cerium oxide particles. Figure 2 For example, the cleaning solution without gluconic acid, sample 20 and sample 21, did not completely remove the cerium oxide particles, as shown in FIG. Figure 7 and 8 The cleaning solutions containing choline hydroxide, hydroxylamine and gluconic acid, such as samples 16 to 19, all have the ability to completely remove the cerium oxide particles adsorbed on the silicon oxide surface. Figures 3 to 6 shown.

[0067] 4. Removal of Cerium Oxide Particles Adsorbed on Silica Surface by Cleaning Solutions Containing Different Quaternary Ammonium Bases

[0068] The following provides a cleaning liquid composition for use in a semiconductor wafer cleaning process. The components and contents of the cleaning liquid composition are shown in Table 4, and the contents of each component are expressed in percentage by mass.

[0069] Table 4

[0070]

[0071] The ability of each example in Table 4 to remove abrasive particles of cerium oxide particles adsorbed on the surface of silicon oxide was tested using the same testing method as above.

[0072] The surface condition of silicon oxide before cleaning is shown in Figure 9 The surface conditions of silicon oxide after cleaning of samples 22 to 26 are shown in Figure 2. Figures 10 to 14 From this, we can see that using tetramethylammonium hydroxide / tetramethylammonium hydroxide and ethanolamine as the alkaline substance, its compound with hydroxylamine sulfate as the hydroxylamine, and gluconic acid as the organic acid, such as samples 22, 23, and 24, all have similar cerium oxide particle removal capabilities; using choline hydroxide / choline hydroxide and ethanolamine as the alkaline substance, its compound with hydroxylamine sulfate as the hydroxylamine, and gluconic acid as the organic acid, such as samples 25 and 26, also have similar cerium oxide particle removal capabilities.

[0073] In addition, the cleaning solution of sample 22 was diluted at different ratios to observe its effect on the removal of cerium oxide particles adsorbed on the silicon oxide surface. The dilution ratios are shown in Table 5.

[0074] Table 5

[0075]

[0076] See also Figures 15 to 20 , we can see that sample 22 always maintains the ability to remove cerium oxide particles under different dilution ratios.

[0077] In addition, the corrosion rate of the cleaning solution of sample 22 on silicon oxide and silicon nitride was tested, and the testing method was as follows:

[0078] In the silicon oxide and silicon nitride etching rate measurements, the silicon oxide and silicon nitride used were provided by Silicon Valley Microelectronics Corporation of the United States. Their thickness is 5 cm x 5 cm wafers were etched in 500 mL of cleaning solution at room temperature with magnetic stirring at 500 rpm for 1-8 hours. The wafers were then removed from the cleaning solution, rinsed with high-purity water for 5-10 minutes, and blown dry with nitrogen. The weights of the silicon oxide and silicon nitride wafers before and after etching were measured using an analytical balance. The silicon oxide and silicon nitride etching rates were estimated based on the weight change of the wafers and the conversion of their silicon nitride and SiO2 densities to the wafer surface area.

[0079] The results obtained by the above method are shown in Table 6.

[0080] Table 6

[0081]

[0082] From the results in Table 6, we can see that the corrosion rate of sample 22 on silicon nitride and silicon oxide is less than This indicates that the cleaning solution sample 22 will not damage the exposed silicon nitride and silicon oxide surfaces during the process of removing cerium oxide particles adsorbed on the silicon oxide surface.

[0083] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A cleaning liquid composition for removing cerium oxide particles from the surface of a semiconductor wafer after chemical mechanical polishing in a semiconductor wafer manufacturing process, characterized in that: The raw materials of the cleaning liquid composition include hydroxylamine or hydroxylamine salt compound, organic acid, quaternary ammonium base, and alkanolamine, wherein the hydroxylamine or hydroxylamine salt compound is hydroxylamine or hydroxylamine sulfate, the quaternary ammonium base is tetramethylammonium hydroxide or choline hydroxide, and the alkanolamine is ethanolamine. When tetramethylammonium hydroxide is used as the quaternary ammonium base, the cleaning liquid composition comprises the following raw material components based on 100% by total mass percentage: 10% or 22% tetramethylammonium hydroxide, 5% hydroxylamine sulfate, 1% gluconic acid, 0% or 5% ethanolamine, and the remainder is ultrapure water, with a pH of 13.12≤pH≤14.89; When the quaternary ammonium base is choline hydroxide, hydroxylamine or hydroxylamine salt, the cleaning liquid composition comprises the following raw material components based on 100% by weight: Choline hydroxide is 7.5-10.7%, hydroxylamine is 1.7-2.0%, and an organic acid is 3.3-5.0%, with the remainder being ultrapure water, 11.29≤pH≤11.47, wherein the organic acid is selected from any one of citric acid, ethylenediaminetetraacetic acid, gluconic acid, and catechol; When the quaternary ammonium base is choline hydroxide, or the hydroxylamine or hydroxylamine salt compound is hydroxylamine sulfate, the cleaning liquid composition comprises the following raw material components based on 100% by weight: Choline hydroxide is 9.0-13.0%, hydroxylamine sulfate is 1.0-7.5%, ethanolamine is 0 or 5%, gluconic acid is 1.0%, and the rest is ultrapure water, 13.03≤pH≤13.48.

Images