An alkaline chemical mechanical polishing solution for a tantalum barrier layer of a through-silicon via

Abstract

The present invention relates to an alkaline chemical mechanical polishing solution for a tantalum barrier layer of a through-silicon via. The composition of the polishing solution includes nano-silica, a complexing agent for tantalum, histidine, lauryldihydroxyethylamine oxide, hydrogen peroxide, and deionized water; the pH value of the polishing solution is 8-10; among them, the mass percentage ratios of each component in the polishing solution are: 3-6% of nano-silica, 0.01-1% of a complex of histidine and lauryldihydroxyethylamine oxide, 0.5-1% of hydrogen peroxide, 1-3% of a complexing agent for tantalum; the mass ratio is histidine: lauryldihydroxyethylamine oxide = 5:1 to 10:1. The present invention can effectively reduce the surface tension of the wafer, eliminate the organic contamination of the wafer, and is environmentally friendly and green, and simplifies the preparation process of the polishing solution.

Description

Technical Field:

[0001] The present invention relates to an alkaline chemical mechanical polishing solution for a tantalum barrier layer of a through-silicon via. Background Art:

[0002] Generally, copper is filled in the through-silicon via in the Z direction of the chip as an interconnection layer to enhance the integration degree of the chip. To prevent the diffusion of copper into the silicon substrate, before filling the through-silicon via with copper, it is also necessary to deposit metallic tantalum as a diffusion barrier layer. In this way, after the copper chemical mechanical polishing process of the wafer, after removing the deposited copper film on the wafer surface, the tantalum diffusion barrier layer and the copper in the via will be exposed. After copper polishing, it is also necessary to polish the barrier layer material to complete the global planarization of the entire plane. However, both copper and tantalum materials exist on the wafer surface during the barrier layer polishing process, and their polishing rates are often inconsistent. It is necessary to control the composition of the polishing solution to improve the polishing rate selectivity ratio of copper and tantalum in the barrier layer, and finally achieve the ideal effect that the same surface is removed simultaneously. In production, usually a copper corrosion inhibitor is added to reduce the copper removal rate to achieve the effect of adjusting the removal rate ratio of copper and tantalum.

[0003] Currently, azoles are mainly used as copper corrosion inhibitors in industrial production. An azole is a five-membered heterocyclic organic compound, and at least two heteroatoms are contained in the five-membered ring, one of which is a nitrogen atom. The azole molecule contains electronegative atoms such as N, S, and O, which can adsorb on the copper atoms on the wafer surface and form a smooth elastic molecular film to play a role in inhibiting copper corrosion. Azoles can be used alone or in combination. Azoles can be further divided into several subcategories (such as diazoles, triazoles, thiazoles). The most commonly used azole corrosion inhibitors in the wafer process are benzotriazole (BTA), methylbenzotriazole (TTA), and 1,2,4-triazole. Azoles themselves can stimulate the eyes, may be dangerous to the fetus, and may also cause burns; inhaling benzotriazole dust can cause rhinitis, bronchitis, fever, wheezing, and symptoms such as vagus nerve tension caused by tracheal inflammation. Although adding azoles to the polishing solution can effectively inhibit copper corrosion, the disadvantages are also obvious: first, most azoles have biological toxicity, so the wastewater discharged from polishing is not conducive to environmental protection; second, after the adsorption product of azoles adsorbs on the copper surface of the wafer, it is difficult to be removed by subsequent cleaning processes, which is likely to cause organic contamination of the wafer; third, azoles are generally insoluble in water, and the dissolution and preparation process takes a long time, which is not conducive to the rapid production of the polishing solution concentrate.

[0004] In patents CN200710172362.9, CN201110073508.0, CN201210012743.1, CN201310027550.8, CN201711439525.5, CN201711439533.X, CN201711439628.1, CN201811627080.8, and CN202010686009.8, azole corrosion inhibitors are widely used. However, the environmental protection and wafer contamination problems caused by azoles have not been effectively solved. Adding insoluble azoles increases the dissolution difficulty in the preparation process and affects the production cycle of the polishing liquid. Summary of the Invention:

[0005] In view of the existing technical problems, the present invention provides an alkaline chemical mechanical polishing liquid for a through-silicon via tantalum barrier layer. The polishing agent is a compound of histidine and lauryldihydroxyethylamine oxide, and the two play a synergistic role as a corrosion inhibitor for copper. Histidine can effectively inhibit the corrosion of copper, while lauryldihydroxyethylamine oxide has a polar group at one end and a non-polar group at the other end. The non-polar group can quickly emulsify organic substances, enabling histidine and other organic substances adsorbed on the copper surface to quickly detach. The polar group makes lauryldihydroxyethylamine oxide easily soluble in the deionized water of the polishing liquid. Lauryldihydroxyethylamine oxide effectively reduces the surface tension of the wafer and eliminates organic contamination of the wafer. The present invention can effectively reduce the surface tension of the wafer, eliminate organic contamination of the wafer, is green and environmentally friendly, and simplifies the preparation process of the polishing liquid.

[0006] To achieve the object of the present invention, the technical solution adopted is as follows:

[0007] An alkaline chemical mechanical polishing liquid for a through-silicon via tantalum barrier layer, the composition of the polishing liquid includes nano-silica, a complexing agent for tantalum, histidine, lauryldihydroxyethylamine oxide, hydrogen peroxide, and deionized water; the pH value of the polishing liquid is 8 - 10;

[0008] Among them, the mass percentage of each component in the polishing liquid is: 3 - 6% of nano-silica, 0.01 - 1% of the complex of histidine and lauryldihydroxyethylamine oxide, 0.5 - 1% of hydrogen peroxide, 1 - 3% of the complexing agent for tantalum;

[0009] The mass ratio is: histidine: lauryldihydroxyethylamine oxide = 5:1 - 10:1;

[0010] The complexing agent for tantalum is one or more of guanidine, guanidine salts, amidine, amidine salts, alkylhydroxamic acids, and organic phosphonic acids; the polishing liquid also contains one or two of a dispersant and a bactericide; the mass percentage is 0.01 - 0.5% of the dispersant and 0.01 - 0.5% of the bactericide.

[0011] The dispersant described is xanthan gum or carboxymethyl cellulose (CMC); the bactericide described is methylisothiazolinone (MIT) or 1,2-benzisothiazolin-3-one (BIT).

[0012] The particle size of the nano-silica described is 60 - 100 nm; preferably 80 nm.

[0013] The specific guanidines described are guanidine and aminoguanidine; the specific guanidine salts are guanidine carbonate, guanidine nitrate, guanidine phosphate, and guanidine sulfate; the specific amidines are formamidine; the specific amidine salts are formamidine acetate and formamidine sulfinate; the specific alkyl hydroxamic acids are butyl alkyl hydroxamic acid, pentyl alkyl hydroxamic acid, hexyl alkyl hydroxamic acid, heptyl alkyl hydroxamic acid, and octyl alkyl hydroxamic acid; the specific organic phosphonic acids are hydroxyethane diphosphonic acid (HEDP), diethylenetriamine pentamethylene phosphonic acid (DTPMP), aminotrimethylene phosphonic acid (ATMP), ethylenediamine tetramethylene phosphonic acid (EDTMP), and their derivatives.

[0014] The preparation method of the alkaline chemical mechanical polishing liquid for the through-silicon via tantalum barrier layer includes the following steps:

[0015] (1) Dissolve and stir nano-silica, histidine, lauryldihydroxyethylamine oxide, and the complexing agent of tantalum separately with deionized water to make their respective solutions;

[0016] (2) Add the solutions of histidine, lauryldihydroxyethylamine oxide, and the complexing agent of tantalum, as well as the hydrogen peroxide solution, to the nano-silica solution in sequence under stirring;

[0017] (3) Then add deionized water to make the solution reach 70 - 98% of the target mass of the polishing liquid, and then adjust the pH to 8 - 10 with a pH regulator, and make up the balance with deionized water;

[0018] One or both of a dispersant and a bactericide are added before adjusting the pH value in step (3).

[0019] The pH regulator described is a potassium hydroxide solution or lactic acid; the hydrogen peroxide solution is 30% hydrogen peroxide by mass ratio;

[0020] The application of the chemical mechanical polishing liquid for the through-silicon via tantalum barrier layer is used for polishing and cleaning of the through-silicon via tantalum barrier layer copper interconnect wafer.

[0021] The substantial features of the present invention are:

[0022] In the current technology, in the chemical mechanical polishing liquid for the through-silicon via tantalum barrier layer, azole compounds are often added as corrosion inhibitors for copper. Azoles with biological toxicity are not conducive to environmental protection. Azoles adsorbed on the wafer surface are likely to cause organic contamination problems of the wafer. Azole compounds have low solubility, which brings inconvenience to the preparation process of the polishing liquid.

[0023] In the chemical mechanical polishing liquid for the tantalum barrier layer of the through - silicon via, histidine and lauryldihydroxyethylamine oxide are compounded in a ratio of 5:1 to 10:1 instead of azole corrosion inhibitors. Its components are green and environmentally friendly, without biological toxicity. Histidine can effectively inhibit the corrosion of copper, while the non - polar group of lauryldihydroxyethylamine oxide can quickly emulsify organic substances. The two play a synergistic role, enabling histidine and other organic substances adsorbed on the copper surface to quickly detach. The polar group makes lauryldihydroxyethylamine oxide easily soluble in the deionized water of the polishing liquid, effectively reducing the surface tension of the wafer and eliminating the organic contamination of the wafer. Histidine is extremely soluble in pure water, and it is easy to prepare an aqueous solution of histidine, simplifying the preparation process of the polishing liquid.

[0024] The beneficial effects of the present invention are as follows:

[0025] The polishing liquid formula for the tantalum barrier layer of the through - silicon via proposed by the present invention uses histidine and lauryldihydroxyethylamine oxide compounded in a ratio of 5:1 to 10:1 instead of azoles as a corrosion inhibitor for copper. The two play a synergistic role, using the green corrosion inhibitor histidine that is completely harmless to the human body and the environment, and solving the environmental protection problem of azole corrosion inhibitors; compounding histidine and the non - ionic surfactant lauryldihydroxyethylamine oxide (OAE - 12) in a ratio of 5:1 to 10:1 solves the problem of organic contamination on the surface of the wafer after polishing; at the same time, using easily soluble histidine instead of azoles improves the convenience of polishing liquid production. Histidine itself has no biological toxicity, its chemical properties are relatively stable, and it has no pollution to the environment, belonging to an environmentally friendly material. The N atom, carboxyl group, and amino group of histidine can all interact with the outer - layer empty orbitals of the matrix metal atoms, undergo chemical adsorption, adsorb on the metal surface, and form a self - assembled film, thus playing a role in protecting the metal. Lauryldihydroxyethylamine oxide (OAE - 12) is easily soluble in water and polar organic solvents, is non - ionic under alkaline conditions, and has good thickening, antistatic, softening, foam - increasing, foam - stabilizing, and detergency properties; it has low irritation to the human body and also has characteristics such as sterilization, calcium soap dispersion, and easy biodegradation. Histidine and lauryldihydroxyethylamine oxide are compounded in a ratio of 5:1 to 10:1. Histidine can effectively inhibit the corrosion of copper, while lauryldihydroxyethylamine oxide has a polar group at one end and a non - polar group at the other end. The polar group can quickly emulsify organic substances, enabling histidine and other organic substances adsorbed on the copper surface to quickly detach. The polar group makes lauryldihydroxyethylamine oxide easily soluble in the deionized water of the polishing liquid, effectively reducing the surface tension of the wafer and eliminating the organic contamination of the wafer. Histidine is extremely soluble in pure water, and it is easy to prepare an aqueous solution of histidine, simplifying the preparation process of the polishing liquid. Specifically, it is reflected in:

[0026] Using benzotriazole as a corrosion inhibitor, there will be organic contamination on the wafer after polishing, and the roughness of the tantalum wafer is above 2 nm; using histidine and lauryldihydroxyethylamine oxide in a compounding ratio of 5:1 to 10:1, the two play a synergistic role and have little effect on the removal rates of copper and tantalum, which is similar to that of the through-silicon-via tantalum-based barrier layer polishing liquid using benzotriazole; while the roughness Sq of tantalum decreases by 50% from above 2 nm; the organic contamination situation on the wafer surface changes from having a small amount of contamination to being clean. And this formula can adjust and control the removal rates of copper and tantalum materials by changing the content of the tantalum complexing agent and the content of nano-silica, and the adjustment range is that the tantalum removal rate is from about to or so; the copper removal rate is from about to or so). BRIEF DESCRIPTION OF THE DRAWINGS:

[0027] Figure 1 SEM image of the abrasive being nano-silica with a particle size of 60 - 80 nm; DETAILED DESCRIPTION OF THE INVENTION:

[0028] In the present invention, histidine and lauryldihydroxyethylamine oxide (OAE-12) are both well-known substances, and the schematic diagrams of their chemical formula structures are shown as follows; both histidine and lauryldihydroxyethylamine oxide are environmentally friendly components that are friendly to humans and the environment. When compounded in a ratio of 5:1 to 10:1 and added to the polishing liquid, it will not cause environmental protection problems; the two play a synergistic role. Histidine is easily adsorbed on the copper material surface of the wafer and can effectively inhibit the corrosion of copper, while the non-polar group of lauryldihydroxyethylamine oxide can quickly emulsify organic substances, enabling histidine and other organic substances adsorbed on the copper surface to quickly detach. The polar group makes lauryldihydroxyethylamine oxide easily soluble in the deionized water of the polishing liquid, reducing the surface tension of the wafer and effectively eliminating the organic contamination on the wafer. Histidine is extremely soluble in pure water, and it is easy to prepare an aqueous solution of histidine, simplifying the preparation process of the polishing liquid.

[0029]

[0030] Schematic diagram of the chemical formula structure of histidine Schematic diagram of the chemical formula structure of lauryldihydroxyethylamine oxide

[0031] The through-silicon-via tantalum barrier layer chemical mechanical polishing liquid of the present invention contains: nano-silica, a tantalum complexing agent, histidine, lauryldihydroxyethylamine oxide, hydrogen peroxide, and deionized water.

[0032] Taking the preparation of 1000 g of polishing liquid as an example:

[0033] Example 1:

[0034] 1. Weigh 150 g of silica sol with a particle size of 80 nm and a concentration of 40% (the main component is nano-silica), 5 g of benzotriazole, 0.5 g of lauryldihydroxyethylamine oxide, 30 g of guanidine carbonate, and 16.67 ml of hydrogen peroxide with a concentration of 30% (i.e., 5 g of hydrogen peroxide). Add benzotriazole to 250 ml of deionized water, and add the remaining components to twice their respective volumes of deionized water and stir simultaneously to prepare their respective diluted solutions;

[0035] 2. Add the diluted guanidine carbonate, benzotriazole, lauryldihydroxyethylamine oxide, and hydrogen peroxide to the aqueous solution of silica sol in sequence, and stir evenly while adding;

[0036] 3. Then add deionized water to make the total weight close to 950 g. While stirring, add 0.1 g of carboxymethyl cellulose (CMC), 0.1 g of methylisothiazolinone (MIT), and adjust the pH to 9 with 0.5 mol / L potassium hydroxide solution. Make up the balance to 1000 g with deionized water and stir evenly. (The composition content of the obtained polishing liquid is: the mass percentage of 80 nm silica is 6%, the mass percentage of benzotriazole is 0.5%, the mass percentage of lauryldihydroxyethylamine oxide is 0.05%, the mass percentage of guanidine carbonate is 3%, the mass percentage of hydrogen peroxide is 0.5%, the mass percentage of carboxymethyl cellulose (CMC) is 0.01%, the mass percentage of methylisothiazolinone (MIT) is 0.01%, and the balance is deionized water)

[0037] The polishing machine used is a fully automated CMP equipment developed and produced by Huahaiqingke, with the model of U300B. The polishing wafer is a 12-inch through-silicon-via tantalum-based copper interconnect wafer; the polishing pad is an IC1010 type polishing pad produced by Dow Chemical Company; the polishing parameters are: the down pressure is 1.5 psi; the polishing head speed is 87 rpm; the polishing platen speed is 93 rpm; the polishing liquid flow rate is 300 ml / min. The copper removal rate, tantalum removal rate, roughness of the tantalum film, and surface contamination situation of the wafer after polishing are listed in Table 1.

[0038] Example 2:

[0039] 1. Weigh 5 g of histidine and 0.5 g of lauryldihydroxyethylamine oxide, add 60 ml of deionized water and stir simultaneously for a 10:1 compounding;

[0040] 2. Weigh 150 g of silica sol with a particle size of 80 nm and a concentration of 40% (the main component is nano-silica), 30 g of guanidine carbonate, and 16.67 ml of hydrogen peroxide with a concentration of 30% (i.e., 5 g of hydrogen peroxide), and add twice their respective volumes of deionized water and stir simultaneously to prepare their respective diluted solutions;

[0041] 3. Add the diluted guanidine carbonate, histidine, the compound solution of lauryldihydroxyethylamine oxide, and hydrogen peroxide to the aqueous solution of silica sol in sequence, while adding and stirring evenly.

[0042] 4. Then add deionized water to make the total weight close to 950 g. While stirring, add 0.1 g of carboxymethyl cellulose (CMC), 0.1 g of methylisothiazolinone (MIT), adjust the pH to 9 with 0.5 mol / L potassium hydroxide solution, and make up the balance to 1000 g with deionized water, and stir evenly. (The composition content of the obtained polishing liquid is: the mass percentage of 80 nm silica is 6%, the mass percentage of histidine is 0.5%, the mass percentage of lauryldihydroxyethylamine oxide is 0.05%, the mass percentage of guanidine carbonate is 3%, the mass percentage of hydrogen peroxide is 0.5%, the mass percentage of carboxymethyl cellulose (CMC) is 0.01%, the mass percentage of methylisothiazolinone (MIT) is 0.01%, and the balance is deionized water)

[0043] The polishing machine used is the fully automated CMP equipment developed and produced by Huahaiqingke, with the model of U300B. The polished wafer is a 12-inch through-silicon-via tantalum-based copper interconnect wafer; the polishing pad is the IC1010 polishing pad of Dow Chemical Company; the polishing parameters are: the down pressure is 1.5 psi; the polishing head rotation speed is 87 rpm; the polishing platen rotation speed is 93 rpm; the polishing liquid flow rate is 300 ml / min. The copper removal rate, tantalum removal rate, roughness of the tantalum film, and surface contamination situation of the wafer after polishing are listed in Table 1.

[0044] Example 3:

[0045] 1. Weigh 5 g of histidine and 0.5 g of lauryldihydroxyethylamine oxide, add 60 ml of deionized water and stir simultaneously for a 10:1 compounding.

[0046] 2. Weigh 75 g of silica sol with a particle size of 80 nm and a concentration of 40% (the main component is nano-silica), 30 g of guanidine carbonate, and 16.67 ml of hydrogen peroxide with a concentration of 30% (i.e., 5 g of hydrogen peroxide), add a small amount of deionized water to each and stir simultaneously to make their respective diluted solutions.

[0047] 3. Add the diluted guanidine carbonate, the compounded solution of histidine and lauryldihydroxyethylamine oxide, and hydrogen peroxide to the aqueous solution of silica sol in sequence, while adding and stirring evenly.

[0048] 4. Add deionized water to make the total weight close to 950 g. While stirring, add 0.1 g of carboxymethyl cellulose (CMC), 0.1 g of methylisothiazolinone (MIT), and adjust the pH to 9 with 0.5 mol / L potassium hydroxide solution. Make up the balance to 1000 g with deionized water and stir evenly. (The composition content of the obtained polishing liquid is as follows: the mass percentage of 80 nm silica is 3%, the mass percentage of histidine is 0.5%, the mass percentage of lauryldihydroxyethylamine oxide is 0.05%, the mass percentage of guanidine carbonate is 3%, the mass percentage of hydrogen peroxide is 0.5%, the mass percentage of carboxymethyl cellulose (CMC) is 0.01%, the mass percentage of methylisothiazolinone (MIT) is 0.01%, and the balance is deionized water)

[0049] The polishing machine is a fully automated CMP equipment developed and produced by Huahaiqingke, with the model of U300B. The polishing wafer is a 12-inch through-silicon-via tantalum-based copper interconnect wafer; the polishing pad is a Dow Chemical Company IC1010 type polishing pad; the polishing parameters are: the down pressure is 1.5 psi; the polishing head speed is 87 rpm; the polishing platen speed is 93 rpm; the polishing liquid flow rate is 300 ml / min. The copper removal rate, tantalum removal rate, roughness of the tantalum film, and surface contamination of the wafer after polishing are listed in Table 1.

[0050] Example 4:

[0051] 1. Weigh 5 g of histidine and 0.5 g of lauryldihydroxyethylamine oxide, add a small amount of deionized water and stir simultaneously for 10:1 compounding;

[0052] 2. Weigh 75 g of silica sol with a particle size of 80 nm and a concentration of 40% (the main component is nano-silica), 60 g of guanidine carbonate, and 16.67 ml of hydrogen peroxide with a concentration of 30% (i.e., 5 g of hydrogen peroxide), add a small amount of deionized water to each and stir simultaneously to make their respective dilution solutions;

[0053] 3. Add the diluted guanidine carbonate, the compounded solution of histidine and lauryldihydroxyethylamine oxide, and hydrogen peroxide to the aqueous solution of silica sol in sequence, and stir evenly while adding;

[0054] 4. Add deionized water to make the total weight close to 950 g. While stirring, add 0.1 g of carboxymethyl cellulose (CMC), 0.1 g of methylisothiazolinone (MIT), and adjust the pH to 9 with 0.5 mol / L potassium hydroxide solution. Make up the balance to 1000 g with deionized water and stir evenly. (The composition content of the obtained polishing solution is as follows: the mass percentage of 80-nm silica is 3%, the mass percentage of histidine is 0.5%, the mass percentage of lauryldihydroxyethylamine oxide is 0.05%, the mass percentage of guanidine carbonate is 6%, the mass percentage of hydrogen peroxide is 0.5%, the mass percentage of carboxymethyl cellulose (CMC) is 0.01%, the mass percentage of methylisothiazolinone (MIT) is 0.01%, and the balance is deionized water)

[0055] The polishing machine is a fully automated CMP equipment developed and produced by Huahaiqingke, with the model of U300B. The polishing wafer is a 12-inch through-silicon-via tantalum-based copper interconnect wafer; the polishing pad is a Dow Chemical IC1010 polishing pad; the polishing parameters are as follows: the down pressure is 1.5 psi; the polishing head speed is 87 rpm; the polishing platen speed is 93 rpm; the polishing solution flow rate is 300 ml / min. The copper removal rate, tantalum removal rate, roughness of the tantalum film, and surface contamination of the wafer after polishing are listed in Table 1.

[0056] Example 5:

[0057] 1. Weigh 5 g of histidine and 0.5 g of lauryldihydroxyethylamine oxide, add a small amount of deionized water and stir simultaneously for 10:1 compounding;

[0058] 2. Weigh 75 g of silica sol with a particle size of 80 nm and a concentration of 40% (the main component is nano-silica), 10 g of guanidine carbonate, and 16.67 ml of hydrogen peroxide with a concentration of 30% (i.e., 5 g of hydrogen peroxide), add a small amount of deionized water to each and stir simultaneously to make their respective dilution solutions;

[0059] 3. Add the diluted guanidine carbonate, the compounded solution of histidine and lauryldihydroxyethylamine oxide, and hydrogen peroxide to the aqueous solution of silica sol in sequence, and stir evenly while adding;

[0060] 4. Add deionized water to make the total weight close to 950 g. While stirring, add 0.1 g of carboxymethyl cellulose (CMC), 0.1 g of methylisothiazolinone (MIT), and adjust the pH to 9 with 0.5 mol / L potassium hydroxide solution. Make up the balance to 1000 g with deionized water and stir evenly. (The composition content of the obtained polishing liquid is as follows: the mass percentage of 80 nm silica is 3%, the mass percentage of histidine is 0.5%, the mass percentage of lauryldihydroxyethylamine oxide is 0.05%, the mass percentage of guanidine carbonate is 1%, the mass percentage of hydrogen peroxide is 0.5%, the mass percentage of carboxymethyl cellulose (CMC) is 0.01%, the mass percentage of methylisothiazolinone (MIT) is 0.01%, and the balance is deionized water)

[0061] The polishing machine is a fully automated CMP equipment developed and produced by Huahaiqingke, with the model of U300B. The polishing wafer is a 12-inch through-silicon-via tantalum-based copper interconnect wafer; the polishing pad is an IC1010 type polishing pad from Dow Chemical Company; the polishing parameters are: the down pressure is 1.5 psi; the polishing head rotation speed is 87 rpm; the polishing disc rotation speed is 93 rpm; the polishing liquid flow rate is 300 ml / min. The copper removal rate, tantalum removal rate, roughness of the tantalum film, and surface contamination of the wafer after polishing are listed in Table 1.

[0062] Figure 1 It can be seen that the abrasive used in the present invention is silica with a particle size of 60 - 100 nm.

[0063] As can be seen from Table 1, compared with Example 1 using benzotriazole, in the through-silicon-via tantalum-based barrier layer polishing liquid of Example 2, histidine and lauryldihydroxyethylamine oxide are compounded in a ratio of 5:1 to 10:1, and the two play a synergistic role, with little effect on the removal rates of copper and tantalum, and there is little difference compared with the through-silicon-via tantalum-based barrier layer polishing liquid of Example 1 using benzotriazole; while the roughness Sq of tantalum drops from 2.76 nm to 1.37 nm; the organic contamination on the wafer surface changes from the presence of a small amount of contamination to a clean degree. By comparing Examples 2 - 5, it can be known that by relatively adjusting the content of silica sol (i.e., nano-silica) or relatively adjusting the content of the tantalum complexing agent (i.e., guanidine carbonate), the removal rates of copper and tantalum in the barrier layer process can be effectively adjusted to achieve the effect of controlling the removal rate ratio of copper and tantalum. In Examples 2 - 5, the roughness Sq of tantalum has been improved, and the organic contamination on the wafer surface has reached a clean degree. Using the combination of histidine and lauryldihydroxyethylamine oxide instead of azoles as the copper corrosion inhibitor, the green corrosion inhibitor histidine that is completely harmless to humans and the environment is used, solving the environmental protection problem of azole corrosion inhibitors; solving the problem of organic contamination on the wafer surface after polishing; at the same time, replacing azoles with easily soluble histidine improves the convenience of polishing liquid production. Histidine can easily prepare an aqueous solution of histidine, which can significantly simplify the preparation process of the polishing liquid.

[0064] Table 1

[0065]

[0066] As can be seen from the above embodiments, for the through-silicon-via tantalum barrier layer polishing solution formulation proposed by the present invention, histidine is compounded with lauryldihydroxyethylamine oxide to replace azoles as a corrosion inhibitor for copper. The green corrosion inhibitor histidine, which is completely harmless to humans and the environment, is used to solve the environmental protection problem of azole corrosion inhibitors; histidine is compounded with the non-ionic surfactant lauryldihydroxyethylamine oxide (OAE-12), and the two play a synergistic role to solve the problem of organic contamination on the surface of the wafer after polishing; at the same time, easily soluble histidine is used to replace azoles, improving the convenience of polishing solution production. Histidine itself has no biological toxicity, relatively stable chemical properties, and no pollution to the environment, belonging to an environmentally friendly material. The N atom, carboxyl group, and amino group of histidine can all interact with the outer empty orbit of the matrix copper metal atoms, undergo chemical adsorption, and adsorb on the surface of metallic copper to form a monomolecular film, thus playing a role in protecting metallic copper. Lauryldihydroxyethylamine oxide (OAE-12) is an amphoteric surfactant, soluble in water and polar organic solvents. Its aqueous solution is cationic under acidic conditions and non-ionic under alkaline conditions, and has good thickening, antistatic, softening, foam-increasing, foam-stabilizing, and detergency properties; it has low irritation, can effectively reduce the irritation of the polishing solution, and also has characteristics such as sterilization, calcium soap dispersion, and easy biodegradation. When histidine is compounded with lauryldihydroxyethylamine oxide, histidine can effectively inhibit the corrosion of copper, while lauryldihydroxyethylamine oxide has a polar group at one end and a non-polar group at the other end. The non-polar group can quickly emulsify organic substances, enabling the histidine and other organic substances adsorbed on the copper surface to quickly detach. The polar group makes lauryldihydroxyethylamine oxide easily soluble in the deionized water of the polishing solution, and lauryldihydroxyethylamine oxide effectively reduces the surface tension of the wafer surface and eliminates the organic contamination of the wafer. Histidine is extremely soluble in pure water, with a solubility of 41.6 g / l at 25°C, and it is easy to prepare an aqueous solution of histidine, thus simplifying the preparation process of the polishing solution.

[0067] Matters not covered by the present invention are well-known technologies.

Claims

1. An alkaline chemical mechanical polishing solution for tantalum barrier layer of through-silicon via, characterized in that the composition of the polishing solution includes nano-silica, complexing agent for tantalum, histidine, lauryldihydroxyethylamine oxide, hydrogen peroxide, deionized water; the pH value of the polishing solution is 8 - 10; Among them, The mass percentages of each component in the polishing solution are: 3 - 6% of nano-silica, 0.01 - 1% of the complex of histidine and lauryldihydroxyethylamine oxide, 0.5 - 1% of hydrogen peroxide, 1 - 3% of the complexing agent for tantalum; The mass ratio of the complex of histidine and lauryldihydroxyethylamine oxide is that histidine: lauryldihydroxyethylamine oxide = 5:1 - 10:1; The complexing agent for tantalum is one or more of guanidine, guanidine salts, amidine, amidine salts, alkylhydroxamic acids, and organic phosphonic acids; The polishing solution also contains one or two of a dispersant and a bactericide; the mass percentages are 0.01 - 0.5% of the dispersant and 0.01 - 0.5% of the bactericide; The dispersant is xanthan gum or carboxymethyl cellulose; the bactericide is methylisothiazolinone or 1,2 - benzisothiazolin - 3 - one.

2. The alkaline chemical mechanical polishing solution for tantalum barrier layer of through-silicon via according to claim 1, characterized in that the particle size of the nano-silica is 60 - 100 nm.

3. The alkaline chemical mechanical polishing solution for tantalum barrier layer of through-silicon via according to claim 1, characterized in that the specific guanidine is guanidine, aminoguanidine; the specific guanidine salts are guanidine carbonate, guanidine nitrate, guanidine phosphate, guanidine sulfate; the specific amidine is formamidine; the specific amidine salts are formamidine acetate, formamidine sulfite; the specific alkylhydroxamic acids are butylhydroxamic acid, pentylhydroxamic acid, hexylhydroxamic acid, heptylhydroxamic acid, octylhydroxamic acid; the specific organic phosphonic acids are hydroxyethylidene diphosphonic acid, diethylenetriamine pentamethylenephosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid and their derivatives.

4. The preparation method of the alkaline chemical mechanical polishing liquid for the tantalum barrier layer of the through-silicon via according to claim 1, characterized in that It includes the following steps: (1) Dissolve and stir nano-silica, the complex of histidine and lauryldihydroxyethylamine oxide, and the complexing agent for tantalum separately with deionized water to make their respective solutions; (2) Add the solutions of the complex of histidine and lauryldihydroxyethylamine oxide, the complexing agent for tantalum, and the hydrogen peroxide solution to the nano-silica solution in sequence under stirring; (3) Then add deionized water to make the solution reach 70 - 98% of the target mass of the polishing solution, and then adjust the pH to 8 - 10 with a pH regulator, and make up the balance with deionized water.

5. The preparation method of the alkaline chemical mechanical polishing solution for tantalum barrier layer of through-silicon via according to claim 4, characterized in that the pH regulator is potassium hydroxide solution or lactic acid; the hydrogen peroxide solution is 30% hydrogen peroxide by mass ratio.

6. The preparation method of the alkaline chemical mechanical polishing solution for the tantalum barrier layer of the through-silicon via according to claim 4, characterized in that One or two of a dispersant and a bactericide are also added in step (3).

7. The application of the chemical mechanical polishing solution for tantalum barrier layer of through-silicon via according to claim 1, characterized in that it is used for polishing and cleaning of copper interconnect wafers with tantalum barrier layer of through-silicon via.

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