Copper plating electroplating liquid for advanced packaging and application of copper plating electroplating liquid

Abstract

The invention provides a copper plating electroplating solution for advanced packaging, which is characterized by comprising the following components: copper ions, an inhibitor, halide ions, an acidic electrolyte, an accelerant, a leveling agent and water, the inhibitor comprises modified polyethylene glycol. The acidic copper plating electroplating solution with the good leveling property can effectively inhibit barbaric deposition of copper ions, and improves the copper plating smoothness of the electrolytic copper plating solution on micron or submicron small-area opening patterns in a high-current area.

Description

Technical Field

[0001] The present invention belongs to the technical field of electroplating deposition, and relates to a copper plating solution, and in particular to a copper plating solution for advanced packaging and applications thereof. Background Art

[0002] With the development of lightweight and miniaturized electronic equipment such as mobile phones and smart wearables, the interconnection design of IC semiconductor packaging is becoming more and more sophisticated, which puts higher and higher requirements on the deposition of copper pillar electroplating (PILLAR), redistribution layer (RDL) or under bump metallization (UBM), bringing unprecedented challenges to the performance of electroplating copper additives and plating solutions.

[0003] In the copper electroplating process, the organic additive components contained in the copper plating solution play a crucial role. Different types of organic additives can significantly improve the leveling and glossiness of the electrolytically deposited copper surface. They can also effectively control the line shape and copper surface flatness during the electrolytic copper pattern plating process, making the copper electrolytic deposition crystallization more delicate and the copper plating surface smoother, thereby ensuring the quality and performance of semiconductor packaging. Therefore, it can be seen that the composition of additives has a decisive influence on the effect of semiconductor packaging.

[0004] To improve the functionality of the electroplated copper layer, the electroplating copper process typically uses various additives such as accelerators, levelers, and inhibitors. Currently, traditional electroplating copper processes commonly use polymers such as polyethylene glycol, gelatin, and cellulose as inhibitors. For example, CN 102365395B discloses a polymer compound terminated with a hydroxyl group formed by the polymerization reaction of an organic amine with ethylene oxide and propylene oxide, which is used as an inhibitor for filling submicron structures. CN 102597329B discloses a polymer compound terminated with a hydroxyl group formed by the polymerization reaction of a polyol with ethylene oxide and propylene oxide, which is used as an inhibitor for filling submicron structures. CN 103443334A discloses a random block polymer of a fatty alcohol with ethylene oxide and propylene oxide as an electroplating copper additive, which exhibits excellent gloss; the reaction product has an alkyl group at one end and a hydroxyl group at the other. CN 105734621A discloses a method using an alkyl betaine compound surfactant as an electroplating copper additive to obtain a flat copper deposit.

[0005] However, with the development of sophisticated semiconductor packaging technology, these traditional inhibitors have gradually exposed their limitations in terms of inhibition effect, synergy with other additives, and adaptability to complex pattern electroplating. As a result, when the bump or RDL opening size of advanced packaging is less than 100μm, a bread-shaped arc-shaped electroplated copper layer with a high middle and low edges of the copper column is usually formed under high current density conditions.

[0006] Therefore, developing electroplating copper additives with better performance and stronger adaptability has become a key link in promoting the continuous advancement of semiconductor packaging technology. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a copper plating solution for advanced packaging and its application. By optimizing inhibitors, the copper plating solution provided by the present invention achieves the formation of smooth copper pillars and circuit redistribution layers under high current density conditions for small-area openings on the micron or submicron scale. These copper pillars and layers exhibit a squared-off coating morphology in cross-section.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a copper plating solution for advanced packaging, the copper plating solution comprising the following components: copper ions, an inhibitor, a halogen ion, an acidic electrolyte, an accelerator, a leveler, and water;

[0010] The inhibitor comprises modified polyethylene glycol, the molecular formula of which is shown below:

[0011]

[0012] Wherein n>8, for example, it can be 10, 100, 150, 200 or 250, etc., but is not limited to the listed values. Other values not listed in the numerical range are also applicable, and are preferably integers of 10 to 200.

[0013] The inhibitor described in the present invention is a modified polyethylene glycol. The introduction of the thiol (-SH) group can form a coordination bond with the metal ion, making it easier to adsorb on the surface of the electroplating cathode (copper substrate) and inhibit the deposition of copper ions. The introduction of the carboxyl (-COOH) group can make the compound have good water solubility. The modified polyethylene glycol can be used as an inhibitor of the copper plating solution to improve the copper plating smoothness of the electrolytic copper plating solution in the high current area.

[0014] The electroplating solution provided by the present invention is acidic and improves the morphology of the coating in a small area through the synergistic effect of an inhibitor, an acidic electrolyte, copper ions and halogen ions.

[0015] As a preferred technical solution of the present invention, the molecular weight of the modified polyethylene glycol is 500 to 10,000, for example, 500, 1,000, 2,000, 4,000, 6,000, 8,000 or 10,000, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0016] As a preferred technical solution of the present invention, the copper plating solution includes: 10-80 g / L of copper ions, 1-2000 mg / L of inhibitor, 5-150 mg / L of halogen ions, 5-200 g / L of acidic electrolyte, 1-1000 mg / L of accelerator, 1-100 mg / L of leveler and water.

[0017] Exemplarily, in the copper plating solution, the concentration of the copper ions is 10 to 80 g / L, for example, 10 g / L, 20 g / L, 40 g / L, 60 g / L or 80 g / L, but is not limited to the listed values, and other values not listed within the numerical range are also applicable;

[0018] The concentration of the inhibitor is 1 to 2000 mg / L, for example, 1 mg / L, 50 mg / L, 100 mg / L, 500 mg / L, 800 mg / L, 1100 mg / L, 1400 mg / L, 1700 mg / L or 2000 mg / L, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable;

[0019] The concentration of the halogen ion is 5 to 150 mg / L, for example, 5 mg / L, 10 mg / L, 50 mg / L, 100 mg / L or 150 mg / L, but is not limited to the listed values, and other values not listed within the numerical range are also applicable;

[0020] The concentration of the acidic electrolyte is 5 to 200 g / L, for example, 5 g / L, 10 g / L, 20 g / L, 50 g / L, 100 g / L, 150 g / L or 200 g / L, but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0021] The concentration of the promoter is 1 to 1000 mg / L, for example, 1 mg / L, 10 mg / L, 50 mg / L, 100 mg / L, 400 mg / L, 800 mg / L or 1000 mg / L, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0022] The concentration of the leveling agent is 1 to 100 mg / L, for example, 1 mg / L, 10 mg / L, 30 mg / L, 50 mg / L, 70 mg / L or 100 mg / L, but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0023] As a preferred technical solution of the present invention, the copper plating solution includes: 30-60 g / L of copper ions, 5-1000 mg / L of inhibitor, 10-45 mg / L of halogen ions, 20-100 g / L of acidic electrolyte, 1-200 mg / L of accelerator, 10-50 mg / L of leveler and water.

[0024] As a preferred technical solution of the present invention, the copper ions are provided by a copper ion source, and the copper ion source includes any one or a combination of two of copper sulfate, copper carbonate, copper pyrophosphate, copper alkanesulfonate or copper alkanolsulfonate. Typical but non-limiting combinations include: a combination of copper sulfate, copper carbonate and copper pyrophosphate, a combination of copper alkanesulfonate and copper alkanolsulfonate, or a combination of copper sulfate, copper carbonate, copper pyrophosphate, copper alkanesulfonate and copper alkanolsulfonate.

[0025] Preferably, the copper alkanesulfonate comprises copper methanesulfonate and / or copper propanesulfonate.

[0026] Preferably, the copper alkanol sulfonate comprises copper hydroxyethyl sulfonate and / or copper hydroxypropyl sulfonate.

[0027] As a preferred technical solution of the present invention, the halogen ion includes any one of chloride ion, iodide ion or bromide ion, or a combination of at least two of them. Typical but non-limiting combinations include: a combination of chloride ion and iodide ion, a combination of chloride ion and bromide ion, a combination of iodide ion and bromide ion, or a combination of chloride ion, iodide ion and bromide ion.

[0028] As a preferred technical solution of the present invention, the acidic electrolyte includes an organic acid electrolyte and / or an inorganic acid electrolyte.

[0029] Preferably, the inorganic acid electrolyte comprises sulfuric acid.

[0030] Preferably, the organic acid electrolyte includes any one of alkanesulfonic acids, alkanolsulfonic acids, citric acid, tartaric acid or formic acid, or a combination of at least two thereof. Typical but non-limiting combinations include: a combination of alkanesulfonic acids and alkanolsulfonic acids, or a combination of citric acid, tartaric acid and formic acid.

[0031] Preferably, the alkanesulfonic acids include methanesulfonic acid and / or propanesulfonic acid.

[0032] Preferably, the alkanol sulfonic acids include isethionic acid and / or hydroxypropyl sulfonic acid.

[0033] As a preferred technical solution of the present invention, the accelerator includes a sulfur-containing compound.

[0034] Preferably, the molecular weight of the promoter is ≤1000, for example, it can be 1000, 800, 600, 4000 or 2000, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0035] Preferably, the sulfur-containing compound comprises bis(3-sulfopropyl) disulfide disodium salt (SPS) and / or 3-mercapto-1-propanesulfonic acid sodium salt (MPS).

[0036] As a preferred technical solution of the present invention, the leveling agent includes nitrogen-containing organic matter.

[0037] Preferably, the nitrogen-containing organic matter includes any one of quaternized polyvinyl imidazole, mercaptobenzimidazole, the reaction product of amine and epoxy compound, the reaction product of amine and thiourea, polyamino acid, 1,3-bis(3-pyridylmethyl)-2-thiourea or polyamide polyamine, or a combination of at least two thereof. Typical but non-limiting combinations include: a combination of quaternized polyvinyl imidazole and mercaptobenzimidazole, a combination of polyamino acid, 1,3-bis(3-pyridylmethyl)-2-thiourea and polyamide polyamine, or a combination of a reaction product of amine and epoxy compound and a reaction product of amine and thiourea.

[0038] It is worth noting that each component in the copper plating solution of the present invention can be purchased commercially.

[0039] In a second aspect, the present invention provides a use of a copper plating solution for advanced packaging as provided in the first aspect, wherein the copper plating solution is used for plating copper pillars or redistribution layers in semiconductor packages.

[0040] Preferably, the line width of the metal wiring or the copper pillar graphic opening in the semiconductor package is ≤100μm, for example, it can be 100μm, 80μm, 60μm, 40μm or 20μm, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0041] It is worth noting that the copper plating solution of the present invention can be carried out under conventional electroplating conditions without any specific limitations.

[0042] More specifically, the anode electrode in the electroplating process includes any one of an insoluble iridium oxide anode, an insoluble titanium-platinum anode, or a soluble phosphorus copper anode;

[0043] The temperature during the electroplating process is 10 to 50° C., for example, 10° C., 20° C., 30° C., 40° C., or 50° C., but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0044] The current density during the electroplating process is 0.1~20A / dm 2, for example, it can be 0.1A / dm 2 , 0.5A / dm 2 , 1A / dm 2 , 5A / dm 2 、10A / dm 2 、15A / dm 2 or 20A / dm 2 The above values are not limited to the listed values, and other values not listed in the numerical range are also applicable.

[0045] The numerical range described in the present invention includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0046] The system refers to an equipment system, a device system or a production device.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The present invention uses modified polyethylene glycol as an inhibitor, and the terminal thiol and carboxyl groups replace the hydroxyl groups of the original polyethylene glycol, which can inhibit the deposition of copper ions, reduce the copper plating rate, and improve the coating morphology of small areas;

[0049] (2) The copper plating solution provided by the present invention has excellent leveling properties; even at high current density, it can still achieve electroplating and depositing a flat copper layer on a small-area opening pattern in an advanced packaging BUMP or RDL. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0051] Example 1

[0052] This embodiment provides a copper plating solution for advanced packaging, wherein the copper plating solution for advanced packaging comprises the following components: copper ions, an inhibitor, a halogen ion, an acidic electrolyte, an accelerator, a leveler, and water;

[0053] The copper ions are provided by a copper ion source, and the copper ion source is copper sulfate;

[0054] The inhibitor is modified polyethylene glycol The molecular weight is 5000;

[0055] The halogen ion is a chloride ion; the acidic electrolyte is sulfuric acid; the accelerator is disodium bis(3-sulfopropyl) disulfide; and the leveler is a reaction product of amine and thiourea.

[0056] Example 2

[0057] This embodiment provides a copper plating solution for advanced packaging, wherein the copper plating solution for advanced packaging comprises the following components: copper ions, an inhibitor, a halogen ion, an acidic electrolyte, an accelerator, a leveler, and water;

[0058] The copper ions are provided by a copper ion source, and the copper ion source is copper sulfate;

[0059] The inhibitor is modified polyethylene glycol The molecular weight is 2000;

[0060] The halogen ion is iodide ion; the acidic electrolyte is tartaric acid; the accelerator is sodium 3-mercapto-1-propanesulfonate; and the leveling agent is amine and quaternized polyvinyl imidazole.

[0061] Example 3

[0062] This embodiment provides a copper plating solution for advanced packaging, wherein the copper plating solution for advanced packaging comprises the following components: copper ions, an inhibitor, a halogen ion, an acidic electrolyte, an accelerator, a leveler, and water;

[0063] The copper ions are provided by a copper ion source, and the copper ion source is copper pyrophosphate;

[0064] The inhibitor is modified polyethylene glycol The molecular weight is 1000;

[0065] The halogen ion is a chloride ion; the acidic electrolyte is an alkanol sulfonic acid; the accelerator is disodium bis(3-sulfopropyl) disulfide; and the leveler is mercaptobenzimidazole.

[0066] Example 4

[0067] This embodiment provides a copper plating solution for advanced packaging, wherein the copper plating solution for advanced packaging comprises the following components: copper ions, an inhibitor, a halogen ion, an acidic electrolyte, an accelerator, a leveler, and water;

[0068] The copper ions are provided by a copper ion source, and the copper ion source is copper sulfate;

[0069] The inhibitor is modified polyethylene glycol The molecular weight is 10000;

[0070] The halogen ion is a combination of bromide ion and chloride ion; the acidic electrolyte is copper alkanesulfonate; the accelerator is sodium 3-mercapto-1-propanesulfonate; and the leveler is 1,3-bis(3-pyridylmethyl)-2-thiourea.

[0071] Example 5

[0072] This embodiment provides a copper plating solution for advanced packaging, wherein the copper plating solution for advanced packaging comprises the following components: copper ions, an inhibitor, a halogen ion, an acidic electrolyte, an accelerator, a leveler, and water;

[0073] The copper ions are provided by a copper ion source, and the copper ion source is copper methanesulfonate;

[0074] The inhibitor is modified polyethylene glycol The molecular weight is 500;

[0075] The halogen ion is a bromide ion; the acidic electrolyte is methanesulfonic acid; the accelerator is disodium bis(3-sulfopropyl) disulfide; and the leveler is polyamide polyamine.

[0076] Example 6

[0077] This embodiment provides a copper plating solution for advanced packaging, wherein the copper plating solution for advanced packaging comprises the following components: copper ions, an inhibitor, a halogen ion, an acidic electrolyte, an accelerator, a leveler, and water;

[0078] The copper ions are provided by a copper ion source, and the copper ion source is copper sulfate;

[0079] The inhibitor is modified polyethylene glycol The molecular weight is 1000;

[0080] The halogen ion is a chloride ion; the acidic electrolyte is tartaric acid; the accelerator is disodium bis(3-sulfopropyl) disulfide; and the leveler is a reaction product of an amine and an epoxy compound.

[0081] The component contents of the copper plating solutions for advanced packaging provided in Examples 1-6 are shown in Table 1.

[0082] Table 1

[0083]

[0084]

[0085] Example 7

[0086] This embodiment provides a copper plating solution for advanced packaging. The copper plating solution for advanced packaging differs from that of Example 1 only in that:

[0087] In this example, the molecular weight of the modified polyethylene glycol is adjusted to 300.

[0088] Example 8

[0089] This embodiment provides a copper plating solution for advanced packaging. The copper plating solution for advanced packaging differs from that of Example 1 only in that:

[0090] In this example, the molecular weight of the modified polyethylene glycol was adjusted to 15,000.

[0091] Comparative Example 1

[0092] This comparative example provides a copper plating solution for advanced packaging. The copper plating solution for advanced packaging differs from that of Example 1 only in that:

[0093] In this comparative example, the modified polyethylene glycol was adjusted to a traditional polyethylene glycol PEG with a molecular weight of 6000.

[0094] Comparative Example 2

[0095] This comparative example provides a copper plating solution for advanced packaging. The copper plating solution for advanced packaging differs from that of Example 1 only in that:

[0096] In this comparative example, modified polyethylene glycol was omitted from the electroplating solution.

[0097] Application Examples

[0098] The copper plating solutions provided in the above embodiments and comparative examples were used to electroplate the electroplating materials, and the plated layers were evaluated. The evaluation results are shown in Table 2.

[0099] The electroplating material is an 8-inch wafer, which is coated with photoresist and patterned to obtain an electroplating pattern with an opening size of 50 μm in diameter;

[0100] The electroplating temperature is 25°C, the current density is 15ASD, and the time is 15min.

[0101] The evaluation includes:

[0102] (1) Visually observe the appearance of the copper plating, and there must be no copper particles or pitting;

[0103] (2) Calculation of copper pillar morphology flatness: After the wafer is plated, a copper pillar with a diameter of 50 μm is vertically cut to make a metallographic section. The morphology of the copper pillar is observed under a microscope, and the copper thickness A at the center of the copper pillar and the copper plating thickness B at the edge are measured respectively.

[0104] Copper layer topography flatness = (AB) / A×100%;

[0105] The smaller the copper layer morphology flatness value is, the flatter the copper column morphology is.

[0106] Table 2

[0107]

[0108]

[0109] According to Table 2, we can know the following points:

[0110] (1) Comprehensive analysis of Examples 1-6 shows that the copper plating solution provided by the present invention can effectively inhibit the barbaric deposition of copper ions and improve the copper plating smoothness of the electrolytic copper plating solution in the high current area; and the copper plating has a good appearance and is free of copper particles and pitting;

[0111] More specifically, when the content of the inhibitor and other components is low (such as in Example 5), the inhibitory effect on copper ion deposition is low, resulting in a high morphological flatness of the copper layer;

[0112] (2) Comprehensive analysis of Example 1 and Examples 7-8 shows that the molecular weight of the modified polyethylene glycol affects the inhibitory effect of the inhibitor. If the molecular weight is too low, the copper plating will have a poor appearance; on the contrary, if the molecular weight is too high, the copper plating will have a foggy appearance.

[0113] (3) Comprehensive analysis of Example 1 and Comparative Example 1 shows that compared with traditional polyethylene glycol PEG, the addition of the modified polyethylene glycol provided by the present invention can make the coating have better flatness;

[0114] (4) Comprehensive analysis of Example 1 and Comparative Example 2 shows that the presence of the inhibitor can effectively inhibit the brutal deposition of copper ions, so that the coating has good flatness and there are no copper particles and pits on the surface of the coating.

[0115] In summary, the acidic copper plating solution with good leveling properties provided by the present invention can effectively inhibit the brutal deposition of copper ions and improve the copper plating flatness of the electrolytic copper plating solution for small-area opening patterns of micron or submicron size in high current areas.

[0116] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A copper plating solution for advanced packaging, characterized in that: The copper plating solution comprises the following components: copper ions, inhibitors, halogen ions, acidic electrolytes, accelerators, levelers and water; The inhibitor comprises modified polyethylene glycol, the molecular formula of which is shown below: Where n>

8.

2. The copper plating solution for advanced packaging according to claim 1, characterized in that The molecular weight of the modified polyethylene glycol is 500 to 10,000.

3. The copper plating solution for advanced packaging according to claim 2, characterized in that The copper plating solution comprises: 10-80 g / L of copper ions, 1-2000 mg / L of inhibitor, 5-150 mg / L of halogen ions, 5-200 g / L of acidic electrolyte, 1-1000 mg / L of accelerator, 1-100 mg / L of leveler and water.

4. The copper plating solution for advanced packaging according to claim 3, characterized in that The copper plating solution comprises: 30-60 g / L of copper ions, 5-1000 mg / L of inhibitor, 10-45 mg / L of halogen ions, 20-100 g / L of acidic electrolyte, 1-200 mg / L of accelerator, 10-50 mg / L of leveler and water.

5. The copper plating solution for advanced packaging according to any one of claims 1 to 4, characterized in that The copper ions are provided by a copper ion source, and the copper ion source includes any one of copper sulfate, copper chloride, copper carbonate, copper pyrophosphate, copper alkane sulfonate or copper alkanol sulfonate, or a combination of at least two thereof.

6. The copper plating solution for advanced packaging according to any one of claims 1 to 5, characterized in that The halogen ion includes any one of chloride ion, iodide ion or bromide ion, or a combination of at least two of them.

7. The copper plating solution for advanced packaging according to any one of claims 1 to 6, characterized in that The acidic electrolyte includes an organic acid electrolyte and / or an inorganic acid electrolyte; Preferably, the organic acid electrolyte includes any one of alkanesulfonic acids, alkanolsulfonic acids, citric acid, tartaric acid or formic acid, or a combination of at least two thereof.

8. The copper plating solution for advanced packaging according to any one of claims 1 to 7, characterized in that The accelerator includes a sulfur-containing compound; Preferably, the molecular weight of the accelerator is ≤1000; Preferably, the sulfur-containing compound comprises disodium bis(3-sulfopropyl) disulfide and / or sodium 3-mercapto-1-propanesulfonate.

9. The copper plating solution for advanced packaging according to any one of claims 1 to 8, characterized in that The leveling agent includes nitrogen-containing organic matter; Preferably, the nitrogen-containing organic matter includes any one or a combination of at least two of quaternized polyvinyl imidazole, mercaptobenzimidazole, a reaction product of an amine and an epoxy compound, a reaction product of an amine and thiourea, polyamino acid, 1,3-bis(3-pyridylmethyl)-2-thiourea or polyamide polyamine.

10. A use of the copper plating solution for advanced packaging according to any one of claims 1 to 9, characterized in that: The copper plating solution is used for plating copper pillars or redistribution layers in semiconductor packages; Preferably, the line width of the metal wiring or the copper pillar pattern opening in the semiconductor package is ≤100 μm.

Images