Preparation method of cobaltous sulfate electroplating solution

Abstract

The invention discloses a preparation method of cobaltous sulfate electroplating liquid. The preparation method of the cobaltous sulfate electroplating solution comprises the following steps: mixing raw materials with the following concentrations to obtain the cobaltous sulfate electroplating solution, the raw materials comprise cobalt sulfate with the concentration of 4-9 g / L, boric acid with the concentration of 20-40 g / L, an additive B with the concentration of 1-5 g / L and water. Wherein g / L represents the ratio of the mass of each component to the total volume of the cobaltous sulfate electroplating solution; the additive B is one or two of compounds as shown in a formula I and a formula II. When the cobalt sulfate electroplating solution prepared by the preparation method is used for micropore cobalt electroplating filling, a relatively high filling deposition rate can be obtained, and the effects that micropores are free of gaps and are uniformly filled are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of a cobalt sulfate electroplating solution. BACKGROUND

[0002] Electrodeposition technology is a key technology to realize metal interconnection, however, in the electrodeposition process, due to the limitation of tip effect and mass transfer in micro-nano holes, the metal deposition at the opening of the trench is too fast, which is easy to form shrinkage defects, and reduces the quality and stability of the interconnection line. In the traditional copper damascene process, by introducing a combination of additives (accelerators, inhibitors and leveling agents), under the synergistic action of the additives, the deposition rate of copper at the opening is lower than that at the bottom, forming a bottom-up growth. Nowadays, with the development of IC integrated circuit industry technology, the integration level of high-end chips is getting higher and higher, and the metal wiring inside the electronic product chip is getting denser and denser, up to tens of kilometers, and the number of layers is as high as 15, the improvement of energy consumption / performance requires the size of transistors and metal interconnection lines to be continuously reduced, and the size effect brought by this is becoming more and more significant, and the interconnection line resistivity will increase sharply, which not only causes serious RC delay, but also generates a lot of Joule heat, which damages the performance of the chip. In summary, copper interconnection has been unable to meet the development needs of the size reduction of advanced integrated circuits in the post-Moore era, and it is urgent to find a new alternative interconnection material.

[0003] Under this circumstance, researchers proposed to use metals with short electron mean free path, such as nickel, cobalt (Co), molybdenum and ruthenium, etc. transition metals to replace copper, in order to avoid the resistance size effect brought by traditional metals when continuously reducing the size of the device. Among them, Co is proposed as a new generation of interconnection material due to its very short electron mean free path, relatively low price and good compatibility with semiconductor manufacturing. However, the electrodeposition process of cobalt interconnection still faces many challenges, such as insufficient filling ability in micro-holes and micro-trenches, uneven plating layer quality, etc. The key to solving these problems lies in the optimization of the formula and performance of the electroplating solution. Therefore, the development of high-performance cobalt electroplating solution has become the core of improving cobalt interconnection technology. SUMMARY

[0004] In view of the problems of poor filling effect and uneven plating layer quality in the existing cobalt metal interconnection, a preparation method of a cobalt sulfate electroplating solution is provided. The cobalt sulfate electroplating solution prepared by the preparation method has a faster filling deposition rate when used for micro-hole cobalt electroplating filling, and can achieve the effect of no gap and uniform filling.

[0005] The present application provides a cobalt sulfate electroplating solution, which comprises the following components in the following concentrations: 4-9 g / L of cobalt sulfate, 20-40 g / L of boric acid, 1-5 g / L of additive B and water; wherein g / L represents the mass of each component to the total volume of the cobalt sulfate electroplating solution;

[0006] The additive B is one or both of the compounds of Formula I and Formula II;

[0007]

[0008] R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 each independently is H, -OH, or C 1-6 alkyl; and R 1 , R 2 , R 3 , and R 4 at least one of R 5 and R 6 is -OH;

[0009] n 1 , n 2 , n 3 , n 4 , n 5 , and n 6 each independently is 0, 1, 2, 3, or 4;

[0010] X 1 , X 2 , and X 3 each independently is absent or -O-.

[0011] In certain embodiments of the application, certain components and concentrations in the cobalt sulfate electroplating solution are defined as follows, and components and concentrations not mentioned are as described in any of the embodiments of the application (referred to herein as "in a certain embodiment").

[0012] In a certain embodiment, R 1 is H or C 1-6 alkyl.

[0013] In a certain embodiment, R 2 is -OH.

[0014] In a certain embodiment, R 3 is -OH.

[0015] In a certain embodiment, R 4 is H or C 1-6 alkyl.

[0016] In a certain embodiment, X 1 is -O-.

[0017] In a certain embodiment, X 2 and X 3each independently is absent or -O-.

[0018] In a certain embodiment, n 1 and n 2 each independently is 1.

[0019] In a certain embodiment, n 3 , n 4 , n 5 and n 6 each independently is 0 or 1.

[0020] In a certain embodiment, R 5 is -OH.

[0021] In a certain embodiment, R 6 is C 1-6 alkyl.

[0022] In a certain embodiment, R 1 is H or -CH3.

[0023] In a certain embodiment, R 4 is H or -CH3.

[0024] In a certain embodiment, R 6 is -CH3.

[0025] In a certain embodiment, the additive B is one or more of 3-butyn-2-ol, propoxylated propargyl alcohol, 3-hexyn-2,5-diol, butynediol propoxylate and butynediol ethoxylate.

[0026] In a certain embodiment, the water is purified water.

[0027] In a certain embodiment, in the cobalt sulfate electroplating solution, the concentration of the cobalt sulfate is 6.8-8.8 g / L; preferably 7-7.5 g / L; for example 7.2 g / L.

[0028] In a certain embodiment, in the cobalt sulfate electroplating solution, the concentration of the boric acid is 28 -35 g / L, preferably 30-32 g / L; for example 31.24 g / L.

[0029] In a certain embodiment, in the cobalt sulfate electroplating solution, the concentration of the additive B is 1-4 g / L, also 1-3 g / L, for example 1 g / L, 3 g / L or 4 g / L.

[0030] In a certain embodiment, the cobalt sulfate electroplating solution consists of the following concentrations of components: 6.8-8.8 g / L of cobalt sulfate, 28-35 g / L of boric acid, 1-4 g / L of additive B and the balance of water; the kind of the additive B is as described in any of the preceding embodiments.

[0031] In one aspect, the cobalt sulfate electroplating solution is prepared from the following raw materials: cobalt sulfate, boric acid, additive B, and water; the additive B is one or more of 3-butyn-2-ol, propoxylated propargyl alcohol, 3-hexyn-2,5-diol, butynediol propoxylate, and butynediol ethoxylate.

[0032] In one aspect, the cobalt sulfate electroplating solution comprises components in the following concentrations of any one of Groups 1 to 4:

[0033] Group 1: 7.2 g / L of cobalt sulfate, 31.24 g / L of boric acid, 1 g / L of 3-butyn-2-ol, and the rest water.

[0034] Group 2: 7.2 g / L of cobalt sulfate, 31.24 g / L of boric acid, 1 g / L of propoxylated propargyl alcohol, and the rest water.

[0035] Group 3: 7.2 g / L of cobalt sulfate, 31.24 g / L of boric acid, 3 g / L of 3-hexyn-2,5-diol, and the rest water.

[0036] Group 4: 7.2 g / L of cobalt sulfate, 31.24 g / L of boric acid, 2 g / L of butynediol propoxylate, 2 g / L of butynediol ethoxylate, and the rest water.

[0037] The present application also provides a preparation method of the above-mentioned cobalt sulfate electroplating solution, comprising the following steps: mixing raw materials in the following concentrations to obtain the cobalt sulfate electroplating solution; the raw materials comprise the following components in the following concentrations: 4-9 g / L of cobalt sulfate, 20-40 g / L of boric acid, 1-5 g / L of additive B, and water; the type of the additive B is as described in any one of the previous aspects; wherein g / L represents the ratio of the mass of each component to the total volume of the cobalt sulfate electroplating solution.

[0038] In one aspect, in the preparation method, the cobalt sulfate is used in the form of cobalt sulfate heptahydrate.

[0039] In one aspect, the temperature of the preparation method is 10-30°C, preferably 20°C.

[0040] In one aspect, the preparation method is preferably as follows: mixing cobalt sulfate heptahydrate and boric acid at a temperature of 20°C to obtain a mixed solution, adding the additive B and water to the mixed solution to obtain the cobalt sulfate electroplating solution.

[0041] The present application also provides a use of the above-mentioned cobalt sulfate electroplating solution in cobalt electroplating filling.

[0042] In one aspect, in the cobalt electroplating filling, the electroplating time is 0.5-2 min; preferably 1 min.

[0043] In one aspect, the current density in the cobalt electroplating filling is 0.1 A / dm2~0.8 A / dm2. 2 ; preferably 0.4 A / dm2. 2 .

[0044] In one aspect, the plating temperature in the cobalt electroplating filling is 10~30℃, preferably 18℃.

[0045] On the basis of common knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily, thus obtaining various preferred examples of the present application.

[0046] The reagents and raw materials used in the present application are commercially available.

[0047] The positive progress effect of the present application is that the cobalt sulfate electroplating solution provided by the present application can obtain a faster filling deposition rate when used for micropore cobalt electroplating filling, realize the effect of no gap and uniform filling in the micropore, and thus obtain an excellent electroplated material. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 Filling effect diagram for Example 1;

[0049] Figure 2 Filling effect diagram for Example 2;

[0050] Figure 3 Filling effect diagram for Example 3;

[0051] Figure 4 Filling effect diagram for Example 4;

[0052] Figure 5 Filling effect diagram for Comparative Example 1;

[0053] Figure 6 Filling effect diagram for Comparative Example 2; wherein the gap in the red frame line indicates the presence of a gap in the micropore. DETAILED DESCRIPTION

[0054] The present application will be further described by way of examples, but the present application is not limited to the examples. In the following examples, the experimental methods not specified in the examples are selected according to conventional methods and conditions, or according to the instructions of the goods.

[0055] Examples 1-4 and Comparative Examples 1-2

[0056] Table 1 Structure of additive B

[0057]

[0058] Table 2 Preparation of electroplating solution

[0059]

[0060] The cobalt sulfate heptahydrate and boric acid were mixed to obtain a basic electroplating solution, then the additives were added into the basic electroplating solution according to the types and mass of the additive B in Table 2 above, and finally water was added to make up to 1 L, and then mixed uniformly at a temperature of 20℃, to obtain the cobalt sulfate electroplating solutions of Examples 1-4 and Comparative Examples 1-2.

[0061] Application Examples

[0062] The cobalt sulfate electroplating solutions obtained in Examples 1-4 and Comparative Examples 1-2 were used for cobalt electroplating filling, and the specific electroplating process conditions were as follows:

[0063] The electroplating parameters were taken as an example of 70x180nm hole type:

[0064] The current density was 0.4 A / dm 2 , the electroplating time was 1 min, and the electroplating temperature was 18℃.

[0065] The filling effects of the cobalt sulfate electroplating solutions of Examples 1-4 and Comparative Examples 1-2 were as follows:

[0066] Table 3 Filling effects of examples and comparative examples

[0067]

[0068] As can be seen from the results in Table 3 and the accompanying Figures 1-4 diagram, the cobalt sulfate electroplating solution of the present application is used for micro-pore cobalt electroplating filling, and a faster filling deposition rate can be obtained, the micro-pores are filled without gaps and defects, and thus an excellent electroplated material can be obtained.

[0069] When the micro-pore cobalt electroplating filling is carried out without adding the additive B (Comparative Example 1, Figure 5 ), the filling deposition rate is slow, and the micro-pores cannot be filled without gaps and uniformly; when the concentration of the additive B is greater than 5g / L (Comparative Example 2, Figure 6 ), the deposition rate is low due to the too high concentration, and the micro-pores cannot be filled without gaps and uniformly, resulting in a short service life of the electroplated material.

Claims

1. A method for preparing a cobalt sulfate electroplating solution, characterized in that: The method comprises the following steps: mixing raw materials of the following concentrations to obtain the cobalt sulfate electroplating solution; the raw materials include components of the following concentrations: 4-9 g / L of cobalt sulfate, 20-40 g / L of boric acid, 1-5 g / L of additive B, and water; wherein g / L represents the ratio of the mass of each component to the total volume of the cobalt sulfate electroplating solution; The additive B is one or two of the compounds represented by formula I and formula II; ； R 1 、R 2 、R 3 、R 4 、R 5 and R 6 Each independently is H, -OH or C 1-6 alkyl; and R 1 、R 2 、R 3 and R 4 At least one of them is -OH; R 5 and R 6 At least one of them is -OH; n 1 、n 2 、n 3 、n 4 、n 5 and n 6 Each independently is 0, 1, 2, 3 or 4; X 1 、X 2 and X 3 Each is independently absent or -O-.

2. The preparation method according to claim 1, wherein It meets one or more of the following conditions: (1) R 1 H or C 1-6 alkyl; (2) R 2 is -OH; (3) R 3 is -OH; (4) R 4 H or C 1-6 alkyl; (5) X 1 is -O-; (6) X 2 and X 3 Each is independently absent or -O-; (7)n 1 and n 2 Each independently equals 1; (8)n 3 、n 4 、n 5 and n 6 Each independently 0 or 1; (9) R 5 is -OH; (10) R 6 C 1-6 alkyl.

3. The preparation method according to claim 1, wherein It meets one or more of the following conditions: (1) R 1 is H or -CH3; (2) R 4 is H or -CH3; (3) R 6 is -CH3.

4. The preparation method according to claim 1, wherein It meets one or more of the following conditions: (1) The additive B is one or more of 3-butyn-2-ol, propoxylated propynyl alcohol, 3-hexyn-2,5-diol, butynediol propoxylate and butynediol ethoxylate; (2) The water is purified water; (3) The concentration of the cobalt sulfate is 6.8-8.8 g / L; (4) The concentration of the boric acid is 28-35 g / L; (5) The concentration of the additive B is 1-4 g / L.

5. The preparation method according to claim 4, wherein It meets one or more of the following conditions: (1) The concentration of cobalt sulfate is 7-7.5 g / L; (2) The concentration of the boric acid is 30-32 g / L; (3) The concentration of the additive B is 1-3 g / L.

6. The preparation method according to claim 1, wherein The raw material includes components in the concentrations of any one of the following groups 1 to 4: Group 1: 7.2 g / L cobalt sulfate, 31.24 g / L boric acid, 1 g / L 3-butyn-2-ol, and the balance water; Group 2: 7.2 g / L of cobalt sulfate, 31.24 g / L of boric acid, 1 g / L of propoxylated propynyl alcohol, and the balance of water; Group 3: 7.2 g / L of cobalt sulfate, 31.24 g / L of boric acid, 3 g / L of 3-hexyne-2,5-diol, and the balance of water; Group 4: 7.2 g / L of cobalt sulfate, 31.24 g / L of boric acid, 2 g / L of butynediol propoxylate, 2 g / L of butynediol ethoxylate, and the balance of water.

7. The preparation method according to any one of claims 1 to 5, characterized in that The cobalt sulfate electroplating solution consists of the following components at the following concentrations: 6.8-8.8 g / L of cobalt sulfate, 28-35 g / L of boric acid, 1-4 g / L of additive B, and the balance of water.

8. The preparation method according to claim 1, wherein It meets one or both of the following conditions: (1) The cobalt sulfate is used in the form of cobalt sulfate heptahydrate; (2) The temperature of the preparation method is 10~30℃.

9. The preparation method according to claim 8, wherein The temperature of the preparation method is 20°C.

10. The preparation method according to claim 9, characterized in that The preparation method comprises the following steps: mixing cobalt sulfate heptahydrate and boric acid at a temperature of 20° C. to obtain a mixed solution; and adding the additive B and water to the mixed solution to obtain the cobalt sulfate electroplating solution.

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