Electroplating solution for Damascus copper interconnection and electroplating process thereof

Abstract

The invention provides an electroplating solution for Damascus copper interconnection and an electroplating process of the electroplating solution. The plating solution comprises copper sulfate, sulfuric acid, chloride ions and an organic additive. The organic additives comprise an accelerator, an inhibitor and a leveling agent. By adopting the electrocoppering solution disclosed by the invention, the effects of no cavity, compact structure, small surface roughness and smoothness can be realized at advanced nodes, and the electrocoppering solution has a good application prospect in semiconductor wafer manufacturing.

Description

Technical Field

[0001] The present invention relates to the technical field of electroless copper plating, and particularly to an electroplating solution for damascene copper interconnect and an electroplating process thereof. Background Art

[0002] For the on-chip metallization of vias and trenches in the fabrication of advanced-node ICs, it relies on an additive-controlled copper deposition process (damascene electroplating). The classical direct current (DC) method of damascene electroplating is based on the use of a three-component additive, usually consisting of an inhibitor, its specific anti-inhibitor, and a leveling agent. And bottom-up filling is a prerequisite for achieving void-free and defect-free damascene copper plating. The preferred inhibitor of the present invention has excellent ability to inhibit the growth on the sidewalls of trenches, and can achieve a bottom-up filling effect in combination with an accelerator. With the preferred leveling agent, it can achieve a copper filling effect with no voids, no defects, good throwing power, dense structure, and small roughness on advanced nodes. It has good application prospects in the semiconductor wafer manufacturing process. Summary of the Invention

[0003] The present invention discloses an electroplating solution for damascene copper interconnect, which is characterized by comprising: copper sulfate, sulfuric acid, chloride ions, an accelerator, an inhibitor, and a leveling agent.

[0004] Further, the accelerator includes: one or a combination of more of sodium dimethyldithiocarbamoyl propane sulfonate, 3-mercapto-propane sulfonic acid-(3-sulfopropyl) ester, sodium 3-mercapto-propane sulfonate, sodium polydithiopropane sulfonate, polydithiopropane sulfonate other than sodium salts, 1,3-propane sultone, sodium 3-(benzothiazolyl-s-thio) propanesulfonate, 3-isothiourea propane sulfonic acid inner salt.

[0005] Further, the inhibitor includes: one or a combination of more of polyethylene glycol copolymer, polyethylene glycol monooleate, polypropylene glycol copolymer, polyvinyl alcohol copolymer, polyethylene glycol / polypropylene glycol block copolymer.

[0006] Further, the weight-average molecular weight of the inhibitor is 500 - 20000, preferably 1000 - 10000.

[0007] Further, the leveling agent is selected from nitrogen-containing compounds of the following formula:

[0008]

[0009] Wherein, R1, R2, R3, R4 are selected from C1-C8 alkyl groups; R5 is selected from a hydrogen bond, a C1-C6 straight-chain alkyl alcohol or a cyclic alkyl alcohol; x and y are respectively integers arbitrarily selected from 1 - 5, and n is an integer arbitrarily selected from 1 - 20.

[0010] Further, the concentration of copper sulfate is 1 g / L - 100 g / L, preferably 5 to 50 g / L; the concentration of sulfuric acid is 1 to 50 g / L, preferably 1 to 20 g / L; the concentration of chloride ions is 20 to 100 mg / L, preferably 30 to 60 mg / L.

[0011] Further, the concentration of the accelerator is 10 to 60 mg / L, preferably 20 to 50 mg / L.

[0012] Further, the concentration of the inhibitor is 50 to 250 mg / L, preferably 75 to 150 mg / L.

[0013] Further, the concentration of the leveling agent is 2 to 200 mg / L, preferably 20 to 100 mg / L.

[0014] The present invention also discloses an electroplating process for a damascene copper interconnect electroplating solution, which uses the electroplating solution as described above. Among them, the current density of electroplating is 1 - 20 mA / cm2, preferably 3 - 15 mA / cm2.

[0015] Further, the electroplating temperature is 15 - 30 °C, preferably 20 - 25 °C.

[0016] Using the electroplating solution of the present invention, a copper filling effect without voids, defects, good throwing power, dense structure, small roughness, and flatness can be achieved for damascene at advanced nodes. Detailed Embodiments

[0017] The advantages of the present invention are further elaborated below in conjunction with specific embodiments.

[0018] Prepare the metal electroplating compositions of Examples 1 - 26 and Comparative Examples 1 - 6 according to the various components and contents described in Table 1. Just mix the various components evenly. The volume of the electroplating composition after uniform mixing is 1 L (made up to 1 L with water), and water is the balance, which is not shown in the table. The pH value of the overall plating solution is 1 - 2. Before electroplating, a small current (~0.05 mA / cm2) needs to be applied to the plating solution for 10 minutes for activation to make the ionic components in the solution evenly distributed. The electroplating equipment is a small horizontal plating equipment.

[0019] Among them, it has been reported in relevant literature that quaternary ammonium salts have a good leveling effect in through-hole copper plating solutions and can increase cathodic polarization. Therefore, it is selected as a comparative example for comparison [https: / / doi.org / 10.5796 / electrochemistry.84.414]; the following chemical formulas are selected as leveling agents for the examples:

[0020]

[0021]

[0022] Table 1 Formulations of Examples 1-26 and Comparative Examples 1-6

[0023]

[0024]

[0025]

[0026] In order to further test the effects of the above metal electroplating solution, electroplating was carried out on a 55 nm trench wafer with a TaN / Ta barrier layer and a copper seed layer as the electroplating substrate under the electroplating conditions listed in Table 2. The electroplating time was about 1 minute. After electroplating, the wafer slices were observed for the filling rate, hole conditions, and structural compactness of the slices by FIB-SEM, and the surface roughness of the plating layer was observed by AFM. Examples 1-26 and Comparative Examples 1-6 were selected for electroplating tests, and the results are shown in Table 2.

[0027] Table 2 Comparison of Filling Effects between Examples 1-26 and Comparative Examples 1-6

[0028]

[0029]

[0030] It can be seen from Table 2 that by selecting specific electroplating additives, the electroplating solution of the present invention can achieve a copper interconnect effect without voids, defects, with a dense plating layer and a smooth and flat surface on wafers at the 55 nm node and even at more advanced nodes under low current density.

[0031] It should be noted that the embodiments of the present invention have better implementability and do not impose any form of limitation on the present invention. Any person skilled in the art may use the technical content disclosed above to modify or transform it into equivalent effective embodiments. However, as long as it does not depart from the technical solution of the present invention, any modification, equivalent change, or modification made to the above embodiments based on the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. An electroplating solution for damascene copper interconnects, characterized in that, Including: Copper sulfate, sulfuric acid, chloride ions, accelerator, inhibitor, and leveling agent.

2. The electroplating solution according to claim 1, characterized in that, The accelerator includes one or more combinations selected from: sodium dimethylthiocarbamoyl propane sulfonate, 3-mercapto-propyl sulfonic acid-(3-sulfopropyl) ester, 3-mercapto-sodium propyl sulfonate, sodium poly(dithiodipropane sulfonate), poly(dithiodipropane sulfonate) other than sodium salt, 1,3-propane sultone, sodium 3-(benzothiazolyl-s-thio) propyl sulfonate, 3-isothiourea propane sulfonic acid inner salt.

3. The electroplating solution according to claim 1, wherein, The inhibitor includes one or more combinations selected from: polyethylene glycol copolymer, polyethylene glycol monooleate, polypropylene glycol copolymer, polyvinyl alcohol copolymer, polyethylene glycol / polypropylene glycol block copolymer.

4. The electroplating solution according to claim 3, wherein The weight-average molecular weight of the inhibitor is 500 - 20000.

5. The electroplating solution according to claim 4, characterized in that, The weight-average molecular weight of the inhibitor is 1000 - 10000.

6. The electroplating solution according to claim 1, characterized in that, The leveling agent is selected from nitrogen-containing compounds of the following formula: (I) (II) Wherein, R1, R2, R3, and R4 are selected from C1-C8 alkyl groups; R5 is selected from a hydrogen bond, a C1-C6 linear alkyl alcohol, or a cyclic alkyl alcohol; x and y are each independently an integer selected from 1 to 5, and n is an integer selected from 1 to 20.

7. The electroplating solution according to claim 1, characterized in that, The concentration of the copper sulfate is 1 g / L - 100 g / L; the concentration of the sulfuric acid is 1 to 50 g / L; the concentration of the chloride ions is 20 to 100 mg / L.

8. The electroplating solution according to claim 7, characterized in that, The concentration of the copper sulfate is 5 to 50 g / L; the concentration of the sulfuric acid is 1 to 20 g / L; the concentration of the chloride ions is 30 to 60 mg / L.

9. The electroplating solution according to claim 1, wherein, The concentration of the accelerator is 10 to 60 mg / L.

10. The electroplating solution according to claim 9, characterized in that, The concentration of the accelerator is 20 to 50 mg / L.

11. The electroplating solution according to claim 1, characterized in that, The concentration of the inhibitor is 50 to 250 mg / L.

12. The electroplating solution according to claim 11, wherein, The concentration of the inhibitor is 75 to 150 mg / L.

13. The electroplating solution according to claim 1, characterized in that, The concentration of the leveling agent is 2 to 200 mg / L.

14. The electroplating solution according to claim 13, characterized in that, The concentration of the leveling agent is 20 to 100 mg / L.

15. An electroplating process of the damascene copper interconnect electroplating solution according to any one of claims 1 - 14, characterized in that The current density of electroplating is 1 - 20 mA / cm2, and the electroplating temperature is 15 - 30 °C.

16. An electroplating process of the damascene copper interconnect electroplating solution according to any one of claims 1 - 14, characterized in that The current density of electroplating is 3 - 15 mA / cm2, and the electroplating temperature is 20 - 25 °C.

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