A substrate for electroplating and its preparation method and electroplating method

Abstract

The present application discloses a substrate for electroplating, a preparation method thereof and an electroplating method, which belong to the field of semiconductor technology. The substrate for electroplating includes: a substrate to be plated and an organic protective film; the surface of the substrate to be plated has a seed layer; the organic protective film is located on the surface of the seed layer; the organic protective film includes: a nitrogen-containing ligand, the N atoms in the nitrogen-containing ligand are complexed with the metal atoms in the seed layer, and the complex can be released by ionization. The complex between the organic protective film and the seed layer relies on coordination bonds to combine and obtain a stable binding force. When the substrate for electroplating is immersed in the electroplating solution in an inclined manner, the organic protective film will not be destroyed by the electroplating solution based on the binding force, and the seed layer is effectively protected. Since the complex can be released by ionization, by applying an electric current to the substrate for electroplating to ionize, the organic protective film can be peeled off from the seed layer, exposing the seed layer, so that the substrate for electroplating can be subjected to normal electroplating operation.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular to a substrate for electroplating, a preparation method thereof, and an electroplating method. Background Art

[0002] Electrochemical copper plating is a common method for obtaining copper interconnects in the current integrated circuit manufacturing process. Before copper electroplating, a barrier layer needs to be deposited on the surface of a patterned substrate, such as a silicon wafer, to prevent copper from diffusing into the substrate to be plated, and a copper seed layer is deposited on the surface of the barrier layer for conduction to form a substrate to be plated for electroplating. When copper electroplating is performed, the substrate to be plated, which serves as the cathode, is tilted at a certain angle into the plating solution. In the absence of an applied current, the seed layer on the portion of the substrate to be plated that first contacts the plating solution will dissolve in the plating solution, making it impossible to plate copper normally on this portion.

[0003] In the related art, a certain current is applied when the substrate to be plated enters the electroplating solution to play a cathodic protection role, thereby effectively preventing the seed layer that enters the electroplating solution first from being dissolved by the electroplating solution.

[0004] In the process of implementing the present disclosure, the inventors found that the related technology has at least the following problems:

[0005] Although the related technology provides cathodic protection for the seed layer that enters the electroplating solution first, current is also applied to other seed layers that have not entered the electroplating solution at the same time, which can easily cause the substrate to be plated to be burned.

[0006] Public Content

[0007] In view of this, the present disclosure provides a substrate for electroplating, a preparation method thereof, and an electroplating method, which can solve the above technical problems.

[0008] Specifically, the following technical solutions are included:

[0009] On the one hand, the embodiments of the present disclosure provide a substrate for electroplating, the substrate for electroplating comprising: a substrate to be plated and an organic protective film;

[0010] The surface of the substrate to be plated has a seed layer;

[0011] The organic protective film is located on the surface of the seed layer;

[0012] The organic protective film includes: nitrogen-containing ligands, N atoms in the nitrogen-containing ligands are complexed with metal atoms in the seed layer, and the complex can be released by ionization.

[0013] In a possible implementation, the nitrogen-containing ligand is an imidazole ring compound.

[0014] In a possible implementation, the chemical structural formula of the nitrogen-containing ligand is as follows:

[0015]

[0016] Wherein, R is H, substituted or unsubstituted alkyl, or substituted or unsubstituted alkenyl.

[0017] In a possible implementation, the thickness of the organic protective film is 1 nm-10 nm.

[0018] In a possible implementation manner, the seed layer is a copper seed layer, a cobalt seed layer or a ruthenium seed layer.

[0019] On the other hand, the embodiments of the present disclosure provide a method for preparing any of the above-mentioned electroplating substrates, the preparation method comprising: providing a substrate to be plated having a surface seed layer;

[0020] An organic protective film is formed on the surface of the seed layer to obtain the electroplating substrate.

[0021] In a possible implementation, the step of forming the organic protective film on the surface of the seed layer to obtain the electroplating substrate includes:

[0022] A mixed solution including nitrogen-containing ligands and acid solution is coated on the surface of the seed layer of the substrate to be plated, and the organic protective film is formed on the surface of the seed layer to obtain the substrate for electroplating.

[0023] In a possible implementation, the mixed solution is coated on the surface of the seed layer of the substrate to be plated by spin coating, and the spin coating speed is controlled to be 2000 rpm-2800 rpm.

[0024] In another aspect, the present disclosure provides an electroplating method for any of the above-mentioned electroplating substrates, the electroplating method comprising:

[0025] Immersing the electroplating substrate in the electroplating solution at a set tilt angle until the electroplating substrate is completely immersed in the electroplating solution and remains horizontal;

[0026] The electroplating substrate is subjected to ionization treatment to release the complex between the N atoms in the nitrogen-containing ligands and the metal atoms in the seed layer, thereby obtaining a substrate to be plated with the organic protective film removed;

[0027] The substrate to be plated is subjected to electroplating treatment to form an electroplating layer on the seed layer of the substrate to be plated.

[0028] In a possible implementation, the ionization treatment of the electroplating substrate to release the complex between the N atoms in the nitrogen-containing ligands and the metal atoms in the seed layer includes:

[0029] Under a first operating condition, applying a first current to the electroplating substrate to perform the ionization treatment;

[0030] The first operating conditions include: the rotation speed of the electroplating substrate is 10 rpm to 60 rpm, the flow rate of the electroplating solution is 10 liters / minute to 30 liters / minute, and the current density of the first current is 0.2 A / dm 2 -1A / dm 2 .

[0031] In a possible implementation, the electroplating treatment is performed on the substrate to be plated to obtain an electroplated layer on the seed layer, including:

[0032] Under a second operating condition, applying a second current to the substrate to be plated to perform the electroplating process;

[0033] The second operating conditions include: the rotation speed of the substrate to be plated is 10 rpm to 60 rpm, the flow rate of the electroplating solution is 5 liters / minute to 20 liters / minute, and the current density of the second current is 5A / dm 2 -15A / dm 2 .

[0034] In a possible implementation, when the electroplating substrate is immersed in the electroplating solution, the time from the formation of the organic protective film is less than or equal to 2 hours.

[0035] The beneficial effects of the technical solution provided by the embodiments of the present disclosure include at least:

[0036] The electroplating substrate provided by the embodiment of the present disclosure forms an organic protective film on the surface of the seed layer, and the organic protective film includes nitrogen-containing ligands. The N atoms in the nitrogen-containing ligands are complexed with the metal atoms in the seed layer. The organic protective film and the seed layer are combined by coordination bonds to obtain a stable binding force. In this way, when the electroplating substrate is immersed in the electroplating solution in an inclined manner, the organic protective film will not be destroyed by the electroplating solution based on the binding force. At the same time, the seed layer is effectively protected to prevent the seed layer that enters the electroplating solution first from being dissolved in advance, thereby ensuring that the electroplating operation proceeds smoothly. Since the complex between the N atoms in the nitrogen-containing ligands and the metal atoms in the seed layer can be released by ionization, the organic protective film can be peeled off from the seed layer by applying an electric current to the electroplating substrate for ionization, exposing the seed layer so that the electroplating substrate can be subjected to normal electroplating operation. DETAILED DESCRIPTION

[0037] In order to make the technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be described in further detail below.

[0038] During the integrated circuit manufacturing process, a conductive network is constructed by copper interconnects formed by electrochemical copper plating. Before copper electroplating, a barrier layer needs to be deposited on the patterned surface of a patterned substrate, such as a silicon wafer, to prevent copper from diffusing into the substrate to be plated, and a copper seed layer is deposited on the surface of the barrier layer for conduction to form a substrate to be plated.

[0039] The seed layer on the substrate to be plated is used to form a conductive surface and promote the formation and growth of copper nuclei. It is expected that the thickness of the seed layer is between 10nm and 40nm and is continuous to meet the requirements of the Damascus process, so that electroplating can be quickly carried out on all surfaces of the seed layer to achieve super filling from bottom to top. Once the seed layer has defects such as discontinuity or obvious agglomeration, it is easy to form defects such as holes in the defective area during electroplating. This is because the nucleation and growth of copper stops at the location of the hole. Therefore, it is very necessary to ensure the continuity of the copper seed layer.

[0040] At present, when electroplating copper, the substrate to be plated, which serves as the cathode, is immersed in the electroplating solution in a rotating manner with the seed layer facing downward. In order to avoid a large number of bubbles when the substrate to be plated enters the electroplating solution, the substrate to be plated is tilted at a certain angle to enter the electroplating solution, which will cause the seed layer on the area where the substrate to be plated first enters the electroplating solution to dissolve in the electroplating solution (in fact, the copper seed layer is corroded by the acid in the electroplating solution). After the substrate to be plated is completely immersed in the electroplating solution, the area where the seed layer is dissolved lacks the seed layer for conduction, so that the electroplating cannot be carried out normally, and defects such as holes will be generated in this area.

[0041] In order to solve the above technical problems, in the related technology, a certain current is applied when the substrate to be plated enters the plating solution to play a cathodic protection role, effectively preventing the seed layer that enters the plating solution first from being dissolved by the plating solution. However, other seed layers that have not entered the plating solution are also applied with current at the same time, which is equivalent to dry burning, which can easily cause the substrate to be plated to be burned.

[0042] Based on the above technical problems, the embodiment of the present disclosure provides a substrate for electroplating, which includes: a substrate to be plated and an organic protective film;

[0043] The surface of the substrate to be plated has a seed layer;

[0044] The organic protective film is located on the surface of the seed layer;

[0045] The organic protective film includes: nitrogen-containing ligands, N atoms in the nitrogen-containing ligands are complexed with metal atoms in the seed layer, and the complex can be released by ionization.

[0046] The electroplating substrate provided by the embodiment of the present disclosure forms an organic protective film on the surface of the seed layer, and the organic protective film includes nitrogen-containing ligands. The N atoms in the nitrogen-containing ligands are complexed with the metal atoms in the seed layer. The organic protective film and the seed layer are combined by coordination bonds to obtain a stable binding force. In this way, when the electroplating substrate is immersed in the electroplating solution in an inclined manner, the organic protective film will not be destroyed by the electroplating solution based on the binding force. At the same time, the seed layer is effectively protected to prevent the seed layer that enters the electroplating solution first from being dissolved (that is, corroded) in advance, ensuring that the electroplating operation proceeds smoothly. Since the complex between the N atoms in the nitrogen-containing ligands and the metal atoms in the seed layer can be released by ionization, the organic protective film can be peeled off from the seed layer by applying current to the electroplating substrate for ionization, exposing the seed layer, so that the electroplating substrate can be subjected to normal electroplating operation.

[0047] In addition, as the circuit pattern on the substrate to be plated becomes more and more refined, the diameter of the through hole to be plated of the circuit pattern is also getting smaller and smaller. For example, the diameter of the through hole to be plated has reached about 2um. There is generally air in these through holes to be plated. Before electroplating, it is necessary to spray the wetting liquid into these through holes to drive out the air in the through holes to be plated so that the electroplating liquid can enter the through holes to be plated for electroplating. The process of "spraying the wetting liquid into the through holes to be plated" is called the pre-wetting process of the substrate to be plated, and the inner wall of the through hole to be plated and the surface of the substrate to be plated both have a seed layer.

[0048] At present, the commonly used wetting liquid is water. During pre-wetting, one method is to use liquid water for spraying. However, this method will make it difficult to completely wet the inside of the through-hole to be plated, resulting in poor pre-wetting effect. Another method is to use gas phase water for spraying. However, this method also needs to change the ambient temperature, air pressure and other parameters to convert the gas phase water into liquid phase and condense it to the surface of the through-hole to be plated, which is complicated. In addition, the above two pre-wetting methods cannot protect the copper seed layer immersed in the electroplating solution in the non-charged state. When entering the electroplating solution, these wetting liquids are also easily washed away by the electroplating solution.

[0049] In the disclosed embodiment, an organic protective film is disposed on the surface of the seed layer of the substrate to be plated. The organic protective film can not only protect the seed layer, but also be located on the entire surface of the seed layer, which means that the through holes to be plated in the substrate to be plated can be pre-wetted so that the electroplating solution can enter the through holes to be plated for electroplating. When entering the electroplating solution, the organic protective film has a complexing effect with the seed layer and will not be washed away by the electroplating solution.

[0050] In a possible implementation, the nitrogen-containing ligand is an imidazole ring compound, such as benzimidazole, benzotriazole, etc. The above nitrogen-containing ligands can not only provide N atoms for complexing with metal atoms, but also have the advantages of simple structure and low molecular weight, so as to ensure that the organic protective film is stripped from the seed layer through ionization and enters the electroplating solution without affecting the subsequent electroplating operation, thereby ensuring that the metal coating has good quality.

[0051] In combination with the above implementation, for example, the nitrogen-containing ligand is an imidazole ring compound, and the chemical structure of the nitrogen-containing ligand is as follows:

[0052]

[0053] Here, R is H, substituted or unsubstituted alkyl, or substituted or unsubstituted alkenyl.

[0054] For example, the “unsubstituted alkyl” mentioned above includes but is not limited to: methyl, ethyl, propyl, butyl, pentyl, hexyl, etc.;

[0055] The above-mentioned "substituted alkyl" refers to that a hydrogen atom in the alkyl group is replaced by a substituent, wherein the substituent includes but is not limited to: hydroxyl, carboxyl, aldehyde, benzene ring, halogen and the like.

[0056] The above-mentioned “unsubstituted alkenyl” includes, but is not limited to, ethenyl, propenyl, allyl, butenyl, pentenyl and the like.

[0057] The above-mentioned “substituted alkenyl” refers to a hydrogen atom in an alkenyl group being replaced by a substituent, wherein the substituent includes but is not limited to: hydroxyl, carboxyl, aldehyde, benzene ring, halogen, etc.

[0058] Taking the seed layer as a copper seed layer as an example, the nitrogen atoms in the above imidazole ring compound can be complexed with the copper atoms in the copper seed layer through coordination bonds, and the complexation process can be seen in the following chemical equation:

[0059]

[0060] In the disclosed embodiments, the thickness of the organic protective film is 1nm-10nm, for example, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, etc. The organic protective film of the above thickness can not only ensure effective protection of the seed layer, but also can be easily stripped off through ionization.

[0061] In the disclosed embodiment, the substrate to be plated includes: a substrate body, a barrier layer and a seed layer; wherein the surface of the substrate body has a circuit pattern, the barrier layer is located on the surface of the circuit pattern, and the seed layer is located on the surface of the barrier layer.

[0062] The surface of the substrate body has a circuit pattern, that is, the circuit pattern is etched on the surface of the substrate body in advance, and then the metal interconnection line is obtained by electroplating on the circuit pattern. For example, the substrate body includes but is not limited to: a silicon chip (also known as a silicon wafer), a resin substrate for a printed circuit board, a semiconductor ceramic substrate, etc.

[0063] Before electroplating on the circuit pattern, a barrier layer needs to be formed on the surface of the circuit pattern to prevent the metal to be plated from diffusing into the substrate. At present, physical vapor deposition is usually used to deposit Ta or TaN on the surface of the circuit pattern of the substrate to form a barrier layer.

[0064] A seed layer is covered on the surface of the barrier layer, for example, the seed layer is deposited on the surface of the barrier layer by physical vapor deposition. The seed layer is used to form a conductive surface and promote the formation and growth of metal nuclei to be plated. For example, the seed layer involved in the embodiments of the present disclosure includes but is not limited to: a copper seed layer, a cobalt seed layer, a ruthenium seed layer, etc.

[0065] During electroplating, the metal to be plated, such as a copper block, is used as the anode, and the substrate to be plated is used as the cathode. Both the anode and the cathode are immersed in the electroplating solution. A power source is connected between the anode and the cathode. The metal to be plated at the anode undergoes an electrochemical reaction and is converted into metal ions and electrons. The electrons released by the anode are transferred to the cathode through the electroplating solution, so that the metal ions on the surface of the seed layer of the cathode combine with the electrons released by the anode, thereby forming a plating layer on the surface of the seed layer.

[0066] In a possible implementation, in the electroplating substrate provided by the embodiment of the present disclosure, the substrate body is a silicon wafer, and the seed layer is a copper seed layer, that is, copper is electroplated on the silicon wafer.

[0067] On the other hand, the embodiments of the present disclosure further provide a method for preparing any of the above-mentioned electroplating substrates, the preparation method comprising: providing a substrate to be plated with a surface seed layer; and

[0068] An organic protective film is formed on the surface of the seed layer to obtain a substrate for electroplating.

[0069] The organic protective film includes nitrogen-containing ligands, N atoms in the nitrogen-containing ligands are complexed with metal atoms in the seed layer, and the complex can be released by ionization.

[0070] In a possible implementation, the organic protective film is formed on the surface of the seed layer to obtain a substrate for electroplating, including:

[0071] A mixed solution including nitrogen-containing ligands and acid solution is coated on the surface of the seed layer of the substrate to be plated, and an organic protective film is formed on the surface of the seed layer to obtain a substrate for electroplating.

[0072] The above-mentioned coating process can be carried out at room temperature, for example, between 20°C and 26°C. The embodiment of the present disclosure coats a mixed solution including nitrogen-containing ligands and acid solution on the surface of the seed layer of the substrate to be plated. In this way, the metal atoms on the seed layer form coordination bonds with the nitrogen atoms in the nitrogen-containing ligands. The two cooperate to form a stable complex, and continue to extend as a unit, so that all the metal atoms on the seed layer are complexed with the nitrogen atoms in the nitrogen-containing ligands, thereby forming an organic protective film on the surface of the seed layer to protect it.

[0073] Among them, in order to facilitate the occurrence of the above complexation reaction, the nitrogen-containing ligand and the acid solution are mixed to serve as a coating mixture. The purpose of using the acid solution is to provide a reaction solvent for the complexation reaction so that the nitrogen-containing ligand can be evenly dissolved therein. At the same time, after the organic protective film is formed, the acid solution can enter the electroplating solution as the base liquid of the electroplating solution to avoid introducing other unnecessary impurities into the electroplating solution.

[0074] In addition, based on the above, when the nitrogen-containing ligand and the acid solution are mixed as a mixed solution for coating, it is very beneficial for the pre-wetting process of the substrate to be plated, and is conducive to obtaining an excellent pre-wetting effect.

[0075] The acid solution is a weak acid such as acetic acid or carbonic acid to avoid corrosion of the seed layer. The amount of the acid solution is controlled to completely dissolve the nitrogen-containing ligand.

[0076] In a possible implementation, the nitrogen-containing ligand is an imidazole compound. The above nitrogen-containing ligand can not only provide N atoms for complexing with metal atoms, but also has the advantages of simple structure and low molecular weight, so that after the organic protective film is stripped from the seed layer by ionization and enters the electroplating solution, it avoids the introduction of undesirable impurities into the electroplating solution, thereby ensuring the plating performance of the electroplating solution.

[0077] In combination with the above implementation, for example, the nitrogen-containing ligand is an imidazole ring compound, and its chemical structure is as follows:

[0078]

[0079] Here, R is H, substituted or unsubstituted alkyl, or substituted or unsubstituted alkenyl.

[0080] For example, the “unsubstituted alkyl” mentioned above includes but is not limited to: methyl, ethyl, propyl, butyl, pentyl, hexyl, etc.;

[0081] The above-mentioned "substituted alkyl" refers to that a hydrogen atom in the alkyl group is replaced by a substituent, wherein the substituent includes but is not limited to: hydroxyl, carboxyl, aldehyde, benzene ring, halogen and the like.

[0082] The above-mentioned “unsubstituted alkenyl” includes, but is not limited to, ethenyl, propenyl, allyl, butenyl, pentenyl and the like.

[0083] The above-mentioned “substituted alkenyl” refers to a hydrogen atom in an alkenyl group being replaced by a substituent, wherein the substituent includes but is not limited to: hydroxyl, carboxyl, aldehyde, benzene ring, halogen, etc.

[0084] Taking the seed layer as a copper seed layer as an example, the nitrogen atoms in the above imidazole ring compound can be complexed with the copper atoms in the copper seed layer through coordination bonds, and the complexation process can be seen in the following chemical equation:

[0085]

[0086] In order to make the coating process of the mixed liquid more uniform, the embodiment of the present disclosure adopts a spin coating method to coat the mixed liquid on the surface of the seed layer of the substrate to be plated. At the same time, the spin coating speed is controlled to 2000rpm-2800rpm, for example, 2050rpm, 2100rpm, 2200rpm, 2300rpm, 2400rpm, 2500rpm, 2600rpm, 2700rpm, 2800rpm, etc.

[0087] On the other hand, the present disclosure also provides an electroplating method for any of the above-mentioned electroplating substrates, the electroplating method comprising:

[0088] Step 1: Immerse the electroplating substrate in the electroplating solution at a set tilt angle until the electroplating substrate is completely immersed in the electroplating solution and remains horizontal.

[0089] Step 2: ionize the electroplating substrate to release the complex between the N atoms in the nitrogen-containing ligands and the metal atoms in the seed layer, thereby obtaining a substrate to be plated with the organic protective film removed.

[0090] Step 3: electroplating the substrate to be plated to form an electroplating layer on the seed layer of the substrate to be plated.

[0091] When electroplating the electroplating substrate prepared in the embodiment of the present disclosure, the organic protective film is firstly peeled off from the seed layer by ionization in the electroplating solution to obtain the substrate to be plated with the seed layer exposed. Then, the substrate to be plated can be electroplated.

[0092] When immersing the electroplating substrate in the electroplating solution, that is, when performing step 1, the time from performing step 1 to the formation time of the organic protective film is less than or equal to 2 hours. In this way, the continuity and integrity of the organic protective film can be ensured, and the protection effect on the seed layer can be improved.

[0093] The following is an explanation of each of the above steps:

[0094] For step 1, the electroplating substrate is immersed in the electroplating solution in a rotating manner with the seed layer facing downward, and when immersed in the electroplating solution, the electroplating substrate is tilted at a set angle to avoid a large number of bubbles when the electroplating substrate enters the electroplating solution. The tilted angle is measured as the angle between the electroplating substrate and the horizontal plane, which is less than or equal to 7°, for example, 4°, 5°, 6°, etc. After the electroplating substrate is completely immersed in the electroplating solution and kept horizontal, step 2 can be performed.

[0095] For step 2, the electroplating substrate is subjected to ionization treatment to release the complex between the N atoms in the nitrogen-containing ligands and the metal atoms in the seed layer, thereby obtaining a substrate to be plated with the organic protective film removed.

[0096] For example, when the seed layer is a copper seed layer and the nitrogen-containing ligand is an imidazole ring compound, the ionization between the nitrogen atoms in the imidazole ring compound and the copper atoms in the copper seed layer is released by ionization, and the ionization process can be seen in the following chemical equation:

[0097]

[0098] It can be seen that after ionization, the organic protective film is peeled off from the copper seed layer, the copper seed layer is exposed, and the copper atoms on the copper seed layer act as seed crystals to help the copper plating layer grow thereon.

[0099] In order to allow the above ionization to proceed smoothly, that is, only the organic protective film can be stripped without electroplating, the embodiment of the present disclosure illustrates that under a first operating condition, a first current is applied to the electroplating substrate for ionization treatment.

[0100] The first operating conditions include: the rotation speed of the electroplating substrate is 10 rpm to 60 rpm, the flow rate of the electroplating solution is 10 liters / minute to 30 liters / minute, and the current density of the first current is 0.2 A / dm 2 -1A / dm 2 .

[0101] For example, the rotation speed of the electroplating substrate includes but is not limited to: 10 rpm, 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, etc.;

[0102] During ionization treatment, the flow rate of the plating solution includes but is not limited to: 10 liters / minute, 15 liters / minute, 20 liters / minute, 25 liters / minute, 30 liters / minute, etc.;

[0103] The density of the first current applied to the electroplating substrate includes but is not limited to: 0.2A / dm 2 , 0.3A / dm 2 , 0.4A / dm 2 , 0.5A / dm2 , 0.6A / dm 2 , 0.7A / dm 2 , 0.8A / dm 2 , 0.9A / dm 2 wait;

[0104] The time of ionization treatment is 3 seconds to 30 seconds, for example, including but not limited to: 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, etc. The ionization time is determined by the thickness of the organic protective film. The thicker the thickness of the organic protective film, the longer the ionization time. Based on the thickness of the organic protective film being 1nm to 10nm, the embodiment of the present disclosure controls the ionization time to be 3 seconds to 30 seconds.

[0105] Under the above first operating condition, ionization can be smoothly and fully carried out, so that the organic protective film is fully stripped and the entire seed layer is exposed. Under the first current with the above current density, electroplating will not occur after the seed layer is exposed. By continuing to increase the current density and changing other operating conditions to electroplate the substrate, see step 3.

[0106] In step 3, the substrate to be plated is subjected to electroplating treatment to form an electroplating layer on the seed layer of the substrate to be plated.

[0107] In order to make the electroplating process proceed smoothly, the embodiment of the present disclosure illustrates that under the second operating condition, a second current is applied to the substrate to be plated on which the seed layer is exposed to perform the electroplating process.

[0108] The second operating conditions include: the rotation speed of the substrate to be plated is 10 rpm-60 rpm, the flow rate of the electroplating solution is 5 liters / minute-20 liters / minute, and the current density of the second current is 5A / dm 2 -15A / dm 2 .

[0109] For example, the rotation speed of the substrate to be plated includes but is not limited to: 10 rpm, 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, etc.;

[0110] During electroplating, the flow rate of the electroplating solution includes but is not limited to: 5 liters / minute, 10 liters / minute, 15 liters / minute, 20 liters / minute, etc.;

[0111] The density of the second current applied to the substrate to be plated includes but is not limited to: 5A / dm 2 , 8A / dm 2 、10A / dm 2 、12A / dm 2 、13A / dm 2 、14A / dm 2、15A / dm 2 wait;

[0112] The electroplating treatment time is 10 seconds to 500 seconds, including but not limited to: 10 seconds, 50 seconds, 100 seconds, 200 seconds, 250 seconds / 300 seconds, 350 seconds, 400 seconds, 450 seconds, etc. The electroplating treatment time is determined by the thickness of the metal coating. The thicker the metal coating, the longer the electroplating treatment time. Based on the current requirements for the thickness of the metal coating, the embodiment of the present disclosure controls the electroplating treatment time to be 10 seconds to 500 seconds. Taking the copper coating as an example, if a 1 micron thick copper coating needs to be electroplated, the electroplating treatment time is about 120 seconds.

[0113] Under the above-mentioned second operating condition, electroplating can be carried out quickly and fully on all surfaces of the seed layer, achieving super filling from bottom to top, and avoiding defects such as discontinuity in the seed layer. Compared with the current density used in the ionization operation, the current density used in the electroplating operation is significantly increased. It can be seen that when the electroplating substrate is electroplated in the embodiment of the present disclosure, a small current is first passed for ionization, and then a large current is passed for electroplating. Each operation process is carried out independently and smoothly and continuously (that is, the ionization operation is compatible with the electroplating operation), the operation is simple, and the preparation cost is low.

[0114] In a possible implementation, in the electroplating substrate provided in the embodiment of the present disclosure, the substrate body used is a silicon wafer, and the metal to be plated is copper, that is, a method for electroplating copper on a silicon wafer is provided.

[0115] The electroplating method involved in the embodiments of the present disclosure can be applied in scenarios including, but not limited to, electroplating in the chip field, electroplating in the packaging field, electroplating in the printed circuit board field, etc.

[0116] The present disclosure will be further described below through specific examples.

[0117] Example 1

[0118] This embodiment provides a substrate for electroplating, which includes: a substrate to be plated and an organic protective film, wherein the substrate to be plated is a silicon wafer with a copper seed layer on the surface, and the organic protective film includes a nitrogen-containing ligand, and the N atoms in the nitrogen-containing ligand are complexed with the copper atoms in the seed layer. The chemical structure of the nitrogen-containing ligand is as follows:

[0119]

[0120] The electroplating substrate is prepared by the following method:

[0121] Under the temperature condition of 25°C, the nitrogen-containing ligand is fully dissolved in acetic acid, and stirred to form a uniform mixed solution. The mixed solution is applied on the copper seed layer of the silicon wafer by spin coating, and the flow rate of the mixed solution during spin coating is controlled to be 1.8 sccm (i.e., 1.8 ml / min), and the spin coating speed is controlled to be 2500 rpm, forming a 2 nm thick organic protective film on the copper seed layer, thereby obtaining the desired electroplating substrate of this embodiment.

[0122] The electroplating substrate is electroplated by the following method:

[0123] The electroplating substrate is immersed in the electroplating solution at an angle of 5° with the horizontal direction until the electroplating substrate is completely immersed in the electroplating solution and remains horizontal.

[0124] Under the first operating condition, a first current is applied to the electroplating substrate for ionization treatment to obtain a substrate to be plated, that is, a silicon wafer with a copper seed layer on the surface. The first operating condition includes: the rotation speed of the electroplating substrate is 30 rpm, the flow rate of the electroplating solution is 15 liters / minute, and the current density of the first current is 0.5 A / dm 2 , the ionization treatment time is 10 seconds.

[0125] Under the second operating condition, a second current is applied to the silicon wafer having a copper seed layer on the surface for electroplating to obtain a copper coating on the silicon wafer. The second operating condition includes: the rotation speed of the substrate to be plated is 25 rpm, the flow rate of the electroplating solution is 10 liters / minute, and the current density of the second current is 10 A / dm 2 , the electroplating treatment time is 150 seconds.

[0126] The test results show that electroplating can be carried out quickly and fully on all surfaces of the seed layer, achieving super filling from bottom to top, and the obtained coating has uniform texture and no defects such as holes and cracks.

[0127] Example 2

[0128] This embodiment provides a substrate for electroplating, which includes: a substrate to be plated and an organic protective film, wherein the substrate to be plated is a silicon wafer with a copper seed layer on the surface, and the organic protective film includes a nitrogen-containing ligand, and the N atoms in the nitrogen-containing ligand are complexed with the copper atoms in the seed layer. The chemical structure of the nitrogen-containing ligand is as follows:

[0129]

[0130] The electroplating substrate is prepared by the following method:

[0131] Under the temperature condition of 25°C, the nitrogen-containing ligand is fully dissolved in acetic acid, and stirred to form a uniform mixed solution. The mixed solution is applied on the copper seed layer of the silicon wafer by spin coating, and the flow rate of the mixed solution during spin coating is controlled to be 2sccm, and the spin coating speed is controlled to be 2000rpm, forming a 5nm thick organic protective film on the copper seed layer, thereby obtaining the desired electroplating substrate of this embodiment.

[0132] The electroplating substrate is electroplated by the following method:

[0133] The electroplating substrate is immersed in the electroplating solution at an angle of 6° with the horizontal direction until the electroplating substrate is completely immersed in the electroplating solution and remains horizontal.

[0134] Under the first operating condition, a first current is applied to the electroplating substrate for ionization treatment to obtain a substrate to be plated, that is, a silicon wafer with a copper seed layer on the surface. The first operating condition includes: the rotation speed of the electroplating substrate is 40 revolutions per minute, the flow rate of the electroplating solution is 20 liters per minute, and the current density of the first current is 0.8 A / dm 2 , the ionization treatment time is 20 seconds.

[0135] Under the second operating condition, a second current is applied to the silicon wafer having a copper seed layer on the surface for electroplating to obtain a copper coating on the silicon wafer. The second operating condition includes: the rotation speed of the substrate to be plated is 40 rpm, the flow rate of the electroplating solution is 5 liters / minute, and the current density of the second current is 12 A / dm 2 , the electroplating treatment time is 300 seconds.

[0136] The test results show that electroplating can be carried out quickly and fully on all surfaces of the seed layer, achieving super filling from bottom to top, and the obtained coating has uniform texture and no defects such as holes and cracks.

[0137] Example 3

[0138] This embodiment provides a substrate for electroplating, which includes: a substrate to be plated and an organic protective film, wherein the substrate to be plated is a silicon wafer with a copper seed layer on the surface, and the organic protective film includes a nitrogen-containing ligand, and the N atoms in the nitrogen-containing ligand are complexed with the copper atoms in the seed layer. The chemical structure of the nitrogen-containing ligand is as follows:

[0139]

[0140] The electroplating substrate is prepared by the following method:

[0141] Under the temperature condition of 25°C, the nitrogen-containing ligand is fully dissolved in carbonic acid, and stirred to form a uniform mixed solution. The mixed solution is applied on the copper seed layer of the silicon wafer by spin coating, and the flow rate of the mixed solution during spin coating is controlled to be 2sccm, and the spin coating speed is controlled to be 2800rpm, forming a 10nm thick organic protective film on the copper seed layer, thereby obtaining the desired electroplating substrate of this embodiment.

[0142] The electroplating substrate is electroplated by the following method:

[0143] The electroplating substrate is immersed in the electroplating solution at an angle of 4° with respect to the horizontal direction until the electroplating substrate is completely immersed in the electroplating solution and remains horizontal.

[0144] Under the first operating condition, a first current is applied to the electroplating substrate for ionization treatment to obtain a substrate to be plated, that is, a silicon wafer with a copper seed layer on the surface. The first operating condition includes: the rotation speed of the electroplating substrate is 60 rpm, the flow rate of the electroplating solution is 30 liters / minute, and the current density of the first current is 1A / dm 2 , the ionization treatment time is 30 seconds.

[0145] Under the second operating condition, a second current is applied to the silicon wafer having a copper seed layer on the surface for electroplating to obtain a copper coating on the silicon wafer. The second operating condition includes: the rotation speed of the substrate to be plated is 60 rpm, the flow rate of the electroplating solution is 20 liters / minute, and the current density of the second current is 15 A / dm 2 , the electroplating treatment time is 400 seconds.

[0146] The test results show that electroplating can be carried out quickly and fully on all surfaces of the seed layer, achieving super filling from bottom to top, and the obtained coating has uniform texture and no defects such as holes and cracks.

[0147] The above description is only for the purpose of facilitating those skilled in the art to understand the technical solution of the present disclosure and is not intended to limit the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A substrate for electroplating, characterized in that: The electroplating substrate comprises: a substrate to be plated and an organic protective film; The surface of the substrate to be plated has a seed layer; The organic protective film is located on the surface of the seed layer; The organic protective film includes: nitrogen-containing ligands, N atoms in the nitrogen-containing ligands are complexed with metal atoms in the seed layer, and the complex can be released by ionization; The nitrogen-containing ligand is an imidazole ring compound, and the seed layer is a copper seed layer, a cobalt seed layer or a ruthenium seed layer; The chemical structural formula of the imidazole ring compound is as follows: ； Wherein, R is H, substituted or unsubstituted alkyl, or substituted or unsubstituted alkenyl.

2. The electroplating substrate according to claim 1, characterized in that: The thickness of the organic protective film is 1 nm-10 nm.

3. The method for preparing a substrate for electroplating according to any one of claims 1 to 2, characterized in that: The preparation method comprises: providing a substrate to be plated having a seed layer on the surface; Forming an organic protective film on the surface of the seed layer to obtain the electroplating substrate; Wherein, the nitrogen-containing ligand in the organic protective film is an imidazole ring compound, and the seed layer is a copper seed layer, a cobalt seed layer or a ruthenium seed layer; The chemical structural formula of the imidazole ring compound is as follows: ； Wherein, R is H, substituted or unsubstituted alkyl, or substituted or unsubstituted alkenyl.

4. The preparation method according to claim 3, characterized in that: The step of forming the organic protective film on the surface of the seed layer to obtain the electroplating substrate comprises: A mixed solution including nitrogen-containing ligands and acid solution is coated on the surface of the seed layer of the substrate to be plated, and the organic protective film is formed on the surface of the seed layer to obtain the substrate for electroplating.

5. The preparation method according to claim 4, characterized in that: The mixed solution is coated on the surface of the seed layer of the substrate to be plated by spin coating, and the spin coating speed is controlled to be 2000 rpm-2800 rpm.

6. The electroplating method for a substrate for electroplating according to any one of claims 1 to 2, characterized in that: The electroplating method comprises: Immersing the electroplating substrate in the electroplating solution at a set tilt angle until the electroplating substrate is completely immersed in the electroplating solution and remains horizontal; The electroplating substrate is subjected to ionization treatment to release the complex between the N atoms in the nitrogen-containing ligands and the metal atoms in the seed layer, thereby obtaining a substrate to be plated with the organic protective film removed; Performing electroplating treatment on the substrate to be plated to form an electroplating layer on the seed layer of the substrate to be plated; Wherein, the nitrogen-containing ligand is an imidazole ring compound, and the seed layer is a copper seed layer, a cobalt seed layer or a ruthenium seed layer; The chemical structural formula of the imidazole ring compound is as follows: ； Wherein, R is H, substituted or unsubstituted alkyl, or substituted or unsubstituted alkenyl.

7. The electroplating method of a substrate for electroplating according to claim 6, characterized in that: The electroplating substrate is subjected to ionization treatment to release the complex between the N atoms in the nitrogen-containing ligands and the metal atoms in the seed layer, comprising: Under a first operating condition, applying a first current to the electroplating substrate to perform the ionization treatment; The first operating conditions include: the rotation speed of the electroplating substrate is 10 rpm to 60 rpm, the flow rate of the electroplating solution is 10 liters / minute to 30 liters / minute, and the current density of the first current is 0.2 A / dm 2 -1A / dm 2 .

8. The electroplating method of a substrate for electroplating according to claim 6, characterized in that: The electroplating treatment is performed on the substrate to be plated to obtain an electroplated layer on the seed layer, comprising: Under a second operating condition, applying a second current to the substrate to be plated to perform the electroplating process; The second operating conditions include: the rotation speed of the substrate to be plated is 10 rpm to 60 rpm, the flow rate of the electroplating solution is 5 liters / minute to 20 liters / minute, and the current density of the second current is 5 A / dm 2 -15A / dm 2 .

9. The electroplating method of a substrate for electroplating according to claim 6, characterized in that: When the electroplating substrate is immersed in the electroplating solution, the time from the formation of the organic protective film is less than or equal to 2 hours.

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