A polishing liquid for palladium and copper chemical mechanical polishing and its preparation method and use method

Abstract

The present invention provides a polishing liquid for palladium and copper chemical mechanical polishing, and a preparation method and a use method thereof. The polishing liquid for palladium and copper chemical mechanical polishing is composed of the following components by weight percentage: 0.5-10% nanodiamond, 5-10% complexing agent, 0.03-0.05% corrosion inhibitor, 0.02-1% pH regulator, and 83-95% deionized water. The present invention is aimed at palladium and copper coplanar materials with the same thickness. The above-mentioned polishing liquid can achieve the removal of excess material on the surface of the workpiece and global nano-level flattening, avoid the loss of workpiece flatness due to the multi-layer superposition effect of metal cross-linking, and facilitate the subsequent photolithography process.

Description

Technical Field

[0001] The invention belongs to the technical field of polishing liquids, and in particular relates to a polishing liquid for chemical mechanical polishing of palladium and copper, and a preparation method and a use method thereof. Background Art

[0002] Chemical Mechanical Polishing (CMP) is a means of achieving global flatness in integrated circuit manufacturing. At the same time, the grinding fluid is a mixture used in the process of flattening the surface of the workpiece, which includes abrasive materials and chemical additives. At present, the composition of the chemical mechanical polishing grinding fluid used for electroplating palladium materials is similar to that of metallic copper, that is, silica polishing fluid. The silica polishing fluid is mainly composed of components such as abrasive particles, metal corrosion inhibitors, complexing agents and oxidants. In recent years, palladium materials are usually electroplated on the surface of the substrate as functional materials, and copper materials are also electroplated as auxiliary materials. After the above-mentioned substrate is ground, a flat surface with coexistence of palladium and copper is formed on the front of the workpiece. The roughness at this time is measured by a 3D microscope to be 0.08-0.1μm, and after grinding, there is a mirror effect, and the surface roughness at this time is 0.041μm.

[0003] However, the above processing results cannot meet the process requirements. There are several problems: First, the object of chemical mechanical polishing is a palladium-copper coplanar material of the same thickness, and the above chemical mechanical polishing treatment has a large difference in the effect on palladium and copper. This is because palladium itself is chemically inactive, can remain stable in air and humid environments at room temperature, and is resistant to weak acid corrosion. Even the removal of palladium oxides needs to be carried out under high temperature conditions. Therefore, the oxidant in the polishing liquid that has an oxidative corrosion effect on copper cannot corrode palladium, resulting in a large difference in the removal rate between the two. For example, when the copper has a removal amount of 6μm, copper and palladium will form a height difference of 1.45μm, resulting in an uneven surface of the substrate. Secondly, as the removal amount continues to increase, the height difference between palladium and copper also increases. In addition, the height of palladium is higher than that of copper and there is no support from copper. During the chemical mechanical polishing process, it will form an arc due to mechanical action, which cannot meet the requirements of product morphology and performance. In summary, the above factors ultimately lead to the inability to achieve global nanoscale flattening of the workpiece, and subsequent photolithography processes cannot be carried out.

[0004] Therefore, in this field, there is an urgent need to develop a chemical mechanical polishing solution for palladium-copper coplanar materials to solve the above problems and meet the usage requirements. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a polishing liquid for palladium and copper chemical mechanical polishing and a preparation method and a use method thereof. The present invention is aimed at palladium and copper coplanar materials of the same thickness. The use of the above-mentioned polishing liquid can achieve the removal of excess material on the surface of the workpiece and global nano-level flattening, avoid the loss of workpiece flatness due to the multi-layer superposition effect of metal cross-linking, and facilitate the subsequent photolithography process.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a polishing solution for chemical mechanical polishing of palladium and copper, wherein the polishing solution for chemical mechanical polishing of palladium and copper is composed of the following components in weight percentage:

[0008]

[0009] The present invention improves the composition of the polishing liquid and no longer adds an oxidant. The added nano-scale diamond abrasive particles have the advantages of high hardness and low friction coefficient. The surface roughness of palladium and copper polished by the chemical mechanical polishing liquid of the specific composition of the present application is low, and both palladium and copper materials can be taken into account to ensure that the removal amount of the two is consistent, which can achieve a global nano-scale flattening effect.

[0010] In addition, the present application adjusts the content of various components so that the removal amounts of palladium and copper are basically balanced. If the content is too low, no removal amount will occur. Otherwise, the surface of the chip will be convex and steps will be produced.

[0011] In the present invention, the weight percentage of the nano-diamond is 0.5-10%, for example, it can be 0.5%, 1%, 2%, 5%, 8%, 10%, etc.

[0012] In the present invention, the weight percentage of the complexing agent is 5-10%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0013] In the present invention, the weight percentage of the corrosion inhibitor is 0.03-0.05%, for example, it can be 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, etc.

[0014] In the present invention, the weight percentage of the pH adjuster is 0.02-1%, for example, it can be 0.02%, 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1% and the like.

[0015] In the present invention, the weight percentage of the deionized water is 83-95%, for example, it can be 83%, 85%, 88%, 90%, 92%, 95%, etc.

[0016] Preferably, the polishing liquid for chemical mechanical polishing of palladium and copper consists of the following components in weight percentage:

[0017]

[0018] Preferably, the particle size distribution of the nanodiamond is 10 to 100 nm, preferably 20 to 80 nm, for example, it can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc.

[0019] Preferably, the average particle size of the nanodiamond is 60 nm, preferably 50 nm.

[0020] Preferably, the complexing agent includes any one of ethylenediaminetetraacetic acid, ethylenediamine, malonic acid or oxalic acid, or a combination of at least two thereof.

[0021] Preferably, the corrosion inhibitor comprises any one of benzotriazole, 5-phenyltetrazolyl or mercaptophenyltetrazolyl, or a combination of at least two thereof.

[0022] Preferably, the pH adjuster includes any one of sodium chloride solution, ammonium acetate or potassium nitrate, or a combination of at least two thereof.

[0023] Preferably, the mass ratio of the nanodiamond to the complexing agent is (0.5-1):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, etc.

[0024] In the present invention, the mass ratio of nano-diamond and complexing agent is adjusted to balance the removal amount of palladium and copper. If the mass ratio is too low, no removal amount will occur, whereas if the mass ratio is too high, a height difference will occur between palladium and copper, resulting in steps.

[0025] In a second aspect, the present invention provides a method for preparing a polishing solution for chemical mechanical polishing of palladium and copper according to the first aspect, the method comprising the following steps:

[0026] The complexing agent, corrosion inhibitor and deionized water are mixed once to obtain a primary mixed solution, and then the primary mixed solution and nano-diamond are mixed for a second time to obtain a secondary mixed solution, and a pH regulator is added to adjust the pH value of the system to obtain the polishing liquid for palladium and copper chemical mechanical polishing.

[0027] Preferably, the pH value of the adjustment system is 6.95.

[0028] In a third aspect, the present invention provides a method for using the polishing liquid for chemical mechanical polishing of palladium and copper according to the first aspect, the method comprising: performing chemical mechanical polishing on the polishing liquid for chemical mechanical polishing of palladium and copper.

[0029] Preferably, the chemical mechanical polishing has a pressure of 2 psi, a time of 30 min, and a rotation speed of 70 rpm.

[0030] Preferably, the amount of the polishing liquid used for chemical mechanical polishing of palladium and copper is 3 mL / min.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention provides a polishing liquid for chemical mechanical polishing of palladium and copper. The present invention improves the composition of the polishing liquid and no longer adds an oxidant. The added nano-scale diamond abrasive particles have the advantages of high hardness and low friction coefficient. The surface roughness of palladium and copper polished by the chemical mechanical polishing liquid of the specific composition of the present application is low, and both palladium and copper materials can be taken into consideration to ensure that the removal amounts of the two materials are consistent, thereby achieving a global nano-scale flattening effect.

[0033] In addition, the present application adjusts the content of various components so that the removal amounts of palladium and copper are basically balanced. If the content is too low, no removal amount will occur, whereas if the content is too high, relief will occur on the wafer surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a photo of the substrate after being polished by the polishing solution provided in Application Example 1;

[0035] Figure 2 This is a diagram showing the effect of a substrate polished with the polishing liquid provided in Comparative Application Example 1. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below by combining the accompanying drawings and specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0037] Example 1

[0038] This embodiment provides a polishing solution for palladium and copper chemical mechanical polishing, and the polishing solution for palladium and copper chemical mechanical polishing is composed of the following components in weight percentage:

[0039]

[0040] The particle size distribution of the nano-diamond is 10-100 nm, the average particle size is 60 nm, and the mass ratio of the nano-diamond to the ethylenediaminetetraacetic acid complexing agent is 0.5:1.

[0041] This embodiment also provides a method for preparing the above-mentioned polishing liquid, which comprises the following steps:

[0042] Ethylenediaminetetraacetic acid complexing agent, benzotriazole corrosion inhibitor and deionized water with a resistivity of 6 MΩ·cm were configured into a primary mixed solution with a volume of 500 mL, and then the primary mixed solution and nanodiamond were mixed for a second time to obtain a secondary mixed solution. After adding sodium chloride solution, the pH value of the system was adjusted to 6.95 to obtain a polishing solution for palladium and copper chemical mechanical polishing.

[0043] Example 2

[0044] This embodiment provides a polishing solution for palladium and copper chemical mechanical polishing, and the polishing solution for palladium and copper chemical mechanical polishing is composed of the following components in weight percentage:

[0045]

[0046] The particle size distribution of the nano-diamond is 10-100 nm, the average particle size is 60 nm, and the mass ratio of the nano-diamond to the ethylenediaminetetraacetic acid complexing agent is 0.5:1.

[0047] This embodiment also provides a method for preparing the above-mentioned polishing liquid, which comprises the following steps:

[0048] Ethylenediaminetetraacetic acid complexing agent, benzotriazole corrosion inhibitor and deionized water with a resistivity of 6 MΩ·cm were configured into a primary mixed solution with a volume of 500 mL, and then the primary mixed solution and nanodiamond were mixed for a second time to obtain a secondary mixed solution. After adding sodium chloride solution, the pH value of the system was adjusted to 6.95 to obtain a polishing solution for palladium and copper chemical mechanical polishing.

[0049] Example 3

[0050] This embodiment provides a polishing solution for palladium and copper chemical mechanical polishing, and the polishing solution for palladium and copper chemical mechanical polishing is composed of the following components in weight percentage:

[0051]

[0052] The particle size distribution of the nano-diamond is 10-100 nm, the average particle size is 60 nm, and the mass ratio of the nano-diamond to the ethylenediaminetetraacetic acid complexing agent is 0.5:1.

[0053] This embodiment also provides a method for preparing the above-mentioned polishing liquid, which comprises the following steps:

[0054] Ethylenediaminetetraacetic acid complexing agent, benzotriazole corrosion inhibitor and deionized water with a resistivity of 6 MΩ·cm were configured into a primary mixed solution with a volume of 500 mL, and then the primary mixed solution and nanodiamond were mixed for a second time to obtain a secondary mixed solution. After adding sodium chloride solution, the pH value of the system was adjusted to 6.95 to obtain a polishing solution for palladium and copper chemical mechanical polishing.

[0055] Example 4

[0056] This embodiment provides a polishing solution for palladium and copper chemical mechanical polishing, and the polishing solution for palladium and copper chemical mechanical polishing is composed of the following components in weight percentage:

[0057]

[0058] The particle size distribution of the nano-diamond is 10-100 nm, the average particle size is 60 nm, and the mass ratio of the nano-diamond to the ethylenediaminetetraacetic acid complexing agent is 0.5:1.

[0059] This embodiment also provides a method for preparing the above-mentioned polishing liquid, which comprises the following steps:

[0060] Ethylenediaminetetraacetic acid complexing agent, benzotriazole corrosion inhibitor and deionized water with a resistivity of 6 MΩ·cm were configured into a primary mixed solution with a volume of 500 mL, and then the primary mixed solution and nanodiamond were mixed for a second time to obtain a secondary mixed solution. After adding sodium chloride solution, the pH value of the system was adjusted to 6.95 to obtain a polishing solution for palladium and copper chemical mechanical polishing.

[0061] Example 5

[0062] This embodiment provides a polishing solution for palladium and copper chemical mechanical polishing, and the polishing solution for palladium and copper chemical mechanical polishing is composed of the following components in weight percentage:

[0063]

[0064] The particle size distribution of the nano-diamond is 10-100 nm, the average particle size is 60 nm, and the mass ratio of the nano-diamond to the ethylenediaminetetraacetic acid complexing agent is 1:1.

[0065] This embodiment also provides a method for preparing the above-mentioned polishing liquid, which comprises the following steps:

[0066] Ethylenediaminetetraacetic acid complexing agent, benzotriazole corrosion inhibitor and deionized water with a resistivity of 6 MΩ·cm were configured into a primary mixed solution with a volume of 500 mL, and then the primary mixed solution and nanodiamond were mixed for a second time to obtain a secondary mixed solution. After adding sodium chloride solution, the pH value of the system was adjusted to 6.95 to obtain a polishing solution for palladium and copper chemical mechanical polishing.

[0067] Example 6

[0068] The difference between this embodiment and embodiment 1 is that the mass ratio of nano-diamond to complexing agent is 0.05:1, and the rest is the same as embodiment 1.

[0069] Example 7

[0070] The difference between this embodiment and embodiment 1 is that the mass ratio of nano-diamond to complexing agent is 1:0.5, and the rest is the same as embodiment 1.

[0071] Comparative Example 1

[0072] The difference between this comparative example and Example 1 is that the nanodiamond is replaced with an equal content of aluminum oxide, and the rest is the same as Example 1.

[0073] Comparative Example 2

[0074] The difference between this comparative example and Example 1 is that the weight percentage of nanodiamond in the polishing liquid is 0.1%, the content of deionized water is adaptively adjusted so that the total weight percentage of the total system is 100%, and the rest is the same as Example 1.

[0075] Comparative Example 3

[0076] The difference between this comparative example and Example 1 is that the weight percentage of nanodiamond in the polishing liquid is 15%, the content of deionized water is adaptively adjusted so that the sum of the weight percentage of the total system is 100%, and the rest is the same as Example 1.

[0077] Comparative Example 4

[0078] This comparative example provides a silicon dioxide polishing liquid, which comprises the following components:

[0079]

[0080] Application Examples 1 to 7 and Comparative Application Examples 1 to 4

[0081] The polishing liquids provided in Examples 1 to 7 and Comparative Examples 1 to 4 were used to polish the palladium-copper wafer, and the specific method was as follows:

[0082] The prepared polishing liquid was used to polish a 4-inch palladium-copper wafer at a polishing pressure of 2 psi, a polishing disc speed of 70 rpm, a polishing liquid flow rate of 3 mL / min, and a polishing time of 30 min.

[0083] Test conditions

[0084] The palladium-copper wafers provided in Application Examples 1 to 7 and Comparative Application Examples 1 to 4 were tested, and the testing method was as follows:

[0085] (1) Surface roughness: measured using a 3D microscope;

[0086] (2) Thickness: measured using a step profiler;

[0087] (3) Polishing rate: the thickness difference before and after polishing divided by the polishing time.

[0088] The test results are shown in Table 1:

[0089] Table 1

[0090]

[0091] From Table 1 and Figure 1 , Figure 2 It can be seen that the surface roughness of palladium and copper after polishing using the chemical mechanical polishing liquid of the specific composition of the present application is low, and both palladium and copper materials can be taken into account to ensure that the removal amount of the two is consistent, and the effect of global nanoscale flattening can be achieved.

[0092] Compared with Application Example 1, Application Examples 6-7 are cases where the mass ratio of nanodiamond to complexing agent exceeds the specified range. If the mass ratio is too low, no removal amount will occur. Otherwise, a height difference will occur between palladium and copper, resulting in steps, and the surface roughness will be relatively high.

[0093] Comparative Application Example 1 is a case of replacing nanodiamonds, and its polishing rate is slow and the roughness is high; Comparative Application Examples 2-3 are cases where the weight percentage of nanodiamonds exceeds the specified range; Comparative Application Example 4 provides a silica polishing liquid containing an oxidant, none of which can achieve the technical effect of the present invention.

[0094] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A polishing liquid for palladium and copper chemical mechanical polishing, characterized in that: The polishing liquid for palladium and copper chemical mechanical polishing consists of the following components in weight percentage: Nano diamond 0.5-10% Complexing agent 5-10% Corrosion inhibitor 0.03-0.05% pH adjuster 0.02-1% Deionized water 83-89.43%; The particle size distribution of the nano-diamond is 10 to 100 nm; The complexing agent includes any one of ethylenediaminetetraacetic acid, ethylenediamine, malonic acid or oxalic acid, or a combination of at least two thereof; The corrosion inhibitor includes any one of benzotriazole, 5-phenyltetrazolyl or mercaptophenyltetrazolyl, or a combination of at least two of them.

2. The polishing liquid for chemical mechanical polishing of palladium and copper according to claim 1, characterized in that: The polishing liquid for palladium and copper chemical mechanical polishing consists of the following components in weight percentage: Nano diamond 0.5-10% Complexing agent 5-10% Corrosion inhibitor 0.03-0.05% pH adjuster 0.02-0.1% Deionized water 83-89.43%.

3. The polishing liquid for chemical mechanical polishing of palladium and copper according to claim 1 or 2, characterized in that: The average particle size of the nano-diamond is 60 nm.

4. The polishing liquid for chemical mechanical polishing of palladium and copper according to claim 1, characterized in that: The pH adjuster includes any one of sodium chloride solution, ammonium acetate or potassium nitrate, or a combination of at least two of them.

5. The polishing liquid for chemical mechanical polishing of palladium and copper according to claim 1, characterized in that: The mass ratio of the nano-diamond to the complexing agent is (0.5-1):

1.

6. A method for preparing a polishing liquid for palladium and copper chemical mechanical polishing according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: The complexing agent, corrosion inhibitor and deionized water are mixed once to obtain a primary mixed solution, and then the primary mixed solution and nano-diamond are mixed for a second time to obtain a secondary mixed solution, and a pH regulator is added to adjust the pH value of the system to obtain the polishing liquid for palladium and copper chemical mechanical polishing.

7. The method according to claim 6, characterized in that The pH value of the adjustment system is 6.

95.

8. A method for using the polishing liquid for chemical mechanical polishing of palladium and copper according to any one of claims 1 to 5, characterized in that: The use method comprises: performing chemical mechanical polishing on the polishing liquid used for chemical mechanical polishing of palladium and copper.

9. The method of use according to claim 8, characterized in that: The chemical mechanical polishing was performed at a pressure of 2 psi, a time of 30 min, and a rotation speed of 70 rpm.

10. The method of use according to claim 8, characterized in that: The dosage of the polishing liquid for chemical mechanical polishing of palladium and copper is 3 mL / min.

Images