TW201712160A - Acid copper electroplating bath and method for electroplating low internal stress and good ductility copper deposits - Google Patents

Abstract

Acid copper electroplating baths provide improved low internal stress copper deposits with good ductility. The acid copper electroplating baths include one or more polyallylamines and certain sulfur containing accelerators. The acid coper electroplating baths may be used to electroplate thin films on relatively thin substrates to provide thin film copper deposits having low internal stress and high ductility.

Description

Acid copper plating bath and method for electroplating copper deposits with low internal stress and excellent ductility

This invention relates to a copper electroplating bath for electroplating low internal stress copper deposits having excellent ductility. More specifically, the present invention relates to a copper electroplating bath for electroplating low internal stress copper deposits having excellent ductility, wherein the acid copper electroplating bath comprises polyallylamine in combination with certain sulfur-containing accelerators.

The intrinsic or intrinsic stress of an electrodeposited metal is a well-known phenomenon caused by defects in the electroplated crystal structure. After electroplating, such defects attempt to self-correct and thereby induce a force that causes the deposit to shrink (tensile strength) or expand (compressive stress). This stress and its mitigation can be problematic. For example, when electroplating is performed primarily on one side of the substrate, the substrate may be curled, bent, and warped, depending on the substrate flexibility and stress magnitude. Stress can cause poor adhesion of the deposit to the substrate, causing foaming, flaking or cracking. This is especially the case for substrates that are difficult to adhere to, such as semiconductor wafers or their counterparts with relatively smooth surface topography. In general, the amount of stress is proportional to the thickness of the deposit, so it can be problematic when thicker deposits are needed, or It is possible to limit the thickness of the deposit that can be achieved.

Most of the metals including copper deposited by the acid plating method exhibit internal stress. Industrial copper acid plating processes utilize different organic additives that beneficially alter the plating process and deposition characteristics. It is also known that deposits from such electroplating baths can be self-annealed at room temperature. The transformation of grain structure that occurs during such self-annealing simultaneously results in a change in deposition stress, usually an increase in stress. Not only is the internal stress itself problematic, but it is often unpredictable as the deposit undergoes aging changes as it self-anneals over time.

The basic mechanism for mitigating intrinsic stress during copper plating is not fully understood. Parameters such as reduced deposit thickness and reduced current density, ie plating speed, substrate type, seed layer or underboard selection, electroplating bath compositions (eg anionic), additives, impurities and contaminants, are known to affect deposits stress. Although such empirical methods of stress reduction have been employed, they are generally not constant or compromise the efficacy of the plating process.

Another important parameter of copper deposits is their ductility. Ductility can be defined as the ability of a solid material to deform under tensile stress. Copper deposits with high ductility are desirable to prevent or reduce the likelihood of copper cracking over time under tensile stress. Ideally, copper deposits have relatively low internal stress and high ductility; however, there is usually a tradeoff between internal stress and ductility. Therefore, there is still a need for a copper electroplating bath and a method of reducing internal stress in copper deposits and providing excellent or high ductility.

An acid copper electroplating bath comprising one or more sources of copper ions, one or more electrolytes, one or more polyallylamines, one or more (O-ethyldithiocarbonate)-S-(3-sulfopropyl)- Esters, their acids and their salts, and one or more Inhibitor.

The method comprises reacting a substrate with one or more sources of copper ions, one or more electrolytes, one or more polyallylamines, one or more (O-ethyldithiocarbonate)-S-(3-sulfopropyl)- Contacting a copper electroplating bath of an ester, an acid thereof and a salt thereof, and one or more inhibitors; and plating a low internal stress and high ductility copper on the substrate.

The present invention also relates to a copper film having an initial internal stress of from 0 psi to 950 psi and an internal stress after aging of from 300 psi to 900 psi and an elongation of 8% or more under a load of a maximum tensile stress of 50 lbf or more.

The acid copper deposit has low internal stress and a relatively large grain structure. The internal stress and grain structure do not substantially change with the aging of the deposit, thus increasing the predictability of the effectiveness of the copper electroplating bath and the deposits it utilizes for electroplating. The low internal stress copper deposits also have excellent or high ductility such that the copper deposits do not easily crack on the substrate as compared to most conventional copper deposits. Copper plated with the bath of the present invention achieves a good balance between low stress and ductility, which was not observed when copper was electroplated using many conventional copper baths. The copper electroplating bath can be used to deposit a copper film on a relatively thin substrate without the basic concern that the thinner substrate may bend, warp, deform, foam, flake or crack.

Unless the context clearly indicates otherwise, the following abbreviations have the following meanings: °C = degrees Celsius; g = grams; ml = milliliters; L = liters; ppm = parts per million = mg / L; A = amperes (ampcrcs) = Amps; = DC; dm = decimeter; mm = mm; μm = micron; nm = nanometer; Mw = weight average molecular weight; SEM = scanning electron micrograph; ASD = A / dm ² ; 2.54 cm = 1 吋; lbf = Pound-force = 4.44482162 N; N = Newton; psi = pounds per square inch = 0.068805 atmosphere; 1 atmosphere = 1.01325 x ^{10 6} dynes / square centimeter; and RFID = radio frequency identification.

The terms "depositing", "plating" and "electroplating" as used throughout this specification are used interchangeably. The term "portion" means a moiety or functional group of a molecule. section" "--CH ₂ -CH ₂ -. The indefinite article "a" (a and an) includes both singular and plural. The term "ductility" means the ability of a solid material to deform under tensile stress. The term "stretching""stress" means the maximum stress that a material withstands before failure.

All percentages and ratios are by weight unless otherwise indicated. All ranges are inclusive and may be combined in any order unless it is obvious that such numerical ranges are limited to a total of 100%.

Copper metal plating baths provide thin film copper deposits with a combination of low internal stress and high ductility. Copper metal is electroplated using a low stress and high ductility acidic copper bath comprising one or more sources of copper ions, one or more electrolytes, one or more polyallylamines, one or more (O-ethyl disulfide) a base carbonate)-S-(3-sulfopropyl)-ester, an acid thereof or an alkali salt thereof, and one or more inhibitors, so that the copper deposit has low internal stress and high ductility, preferably with copper Precipitation aging has very little change in stress and high ductility. The low internal stress copper deposit may have a relatively large matte appearance of deposited grain size (typically 2 microns or greater). The acidic low stress, high ductility copper bath may also comprise one or more sources of chloride ions and one or more conventional additives typically included in copper plating baths. Preferably, one or more sources of chloride ions are included in the acid copper electroplating bath.

Preferably, the one or more polyallylamines have the formula:

Here, "n" is a number such that Mw is 1000 g/mol or more. Preferably, the polyallylamine of the present invention has a Mw in the range of from 4000 g/mol to 60,000 g/mol, more preferably from 10,000 g/mol to 30,000 g/mol.

The polyallylamine is included in the acid copper plating bath in an amount of from 1 ppm to 10 ppm, preferably from 1 ppm to 5 ppm, more preferably from 1 ppm to 2 ppm.

One or more (O-ethyldithiocarbonate)-S-(3-sulfopropyl)-ester, an acid thereof and an alkali metal salt thereof are included in copper plating in an amount of from 100 ppm to 300 ppm, preferably from 120 ppm to 220 ppm In the bath. The acid form of the ester is 3-[(ethoxythioketomethyl)thio]-1-propanesulfonic acid. The alkali metal salt includes (O-ethyldithiocarbonate)-S-(3-sulfopropyl)-ester potassium salt and (O-ethyldithiocarbonate)-S-(3-sulfopropyl group) )-ester sodium salt. Preferably, the (O-ethyldithiocarbamate)-S-(3-sulfopropyl)-ester potassium salt is included in a copper electroplating bath. Although not bound by theory, it is believed that (O-ethyldithiocarbamate)-S-(3-sulfopropyl)-ester and its alkali metal salt in combination with one or more polyallylamines provide low internal stress and Highly ductile copper metal film deposits can be combined.

Optionally, one or more other promoters may be included in the low stress and high ductility acid copper electroplating bath. The promoter is preferably a compound that, in combination with one or more inhibitors, increases the plating rate at a given plating potential. Such promoters as the case may be 3-mercapto-1-propanesulfonic acid, ethyldithiodipropanesulfonic acid, bis-(ω-sulfobutyl)-disulfide, methyl-(ω- Sulfopropyl)-disulfide, N,N-dimethyldithiocarbamic acid (3-sulfopropyl) ester, 3-[(amine -iminomethyl)-thiol]-1-propanesulfonic acid, 3-(2-benzylthiothiazolylthio)-1-propanesulfonic acid, bis(sulfopropyl)-disulfide and Its alkali metal salt. Preferably, such promoters are excluded from the copper electroplating bath.

When included as an accelerator present, it is included in an amount of 1 ppm and higher. Typically such promoters can be included in the acid copper electroplating bath in an amount from 2 ppm to 500 ppm, more typically from 2 ppm to 250 ppm.

Inhibitors included in low stress, high ductility acid copper electroplating baths include, but are not limited to, polyoxyalkylene glycols, carboxymethyl cellulose, nonylphenol polyglycol ethers, octanediol bis (polyalkylene) Alcohol ether), octanol polyalkylene glycol ether, oleic acid polyglycol ester, polyethyl propylene glycol, polyethylene glycol, polyethylene glycol dimethyl ether, polyoxypropylene glycol, polypropylene glycol, polyvinyl alcohol, hard Polyethylene glycol ester of fatty acid and stearyl glycol polyglycol ether. Such inhibitors are included in an amount of from 0.1 g/L to 10 g/L, preferably from 0.1 g/L to 5 g/L, more preferably from 0.1 g/L to 2 g/L, and most preferably from 0.1 g/L to 1g/L.

Suitable copper ion sources are copper salts and include, but are not limited to: copper sulfate; copper halides such as copper chloride; copper acetate; copper nitrate; copper tetrafluoroborate; copper alkyl sulfonate; copper aryl sulfonate; Copper sulfonate; copper perchlorate and copper gluconate. Exemplary copper alkanesulfonates include copper (C ₁ -C ₆ ) alkanesulfonate, and more preferably copper (C ₁ -C ₃ ) alkanesulfonate. Preferred copper alkane sulfonates are copper methane sulfonate, copper ethane sulfonate and copper propane sulfonate. Exemplary copper aryl sulfonates include, but are not limited to, copper benzene sulfonate and copper p-toluene sulfonate. A copper ion source mixture can be used. One or more metal ion salts other than copper ions may be added to the acid copper electroplating bath. Typically, the copper salt is present in an amount sufficient to provide an amount of copper ions in the plating solution from 10 g/L to 400 g/L. The plating bath does not include any alloy metal. The electroplating bath is for thin film copper deposits, not for copper alloy deposits or any other metal or metal alloy.

Suitable electrolytes include, but are not limited to, sulfuric acid, acetic acid, fluoroboric acid, alkanesulfonic acids (such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, and trifluoromethanesulfonic acid), arylsulfonic acids (such as benzenesulfonic acid, P-toluenesulfonic acid), aminosulfonic acid, hydrochloric acid, hydrobromic acid, perchloric acid, nitric acid, chromic acid, and phosphoric acid. A mixture of acids can be used in the metal plating bath of the present invention. Preferred acids include sulfuric acid, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, hydrochloric acid, and mixtures thereof. The acid may be present in the range of from 1 g/L to 400 g/L. Electrolytes are generally available from a variety of sources and can be used without further purification.

One or more optional additives may also be included in the electroplating composition. Such additives include, but are not limited to, leveling agents, surfactants, buffers, pH adjusters, halide ion sources, organic acids, chelating agents, and complexing agents. Such additives are well known in the art and can be used in conventional amounts.

The leveling agent can be included in an acid copper plating bath. Such leveling agents include, but are not limited to, organosulfosulfonates such as 1-(2-hydroxyethyl)-2-imidazolinthione (HIT), 4-mercaptopyridine, 2-mercaptothiazoline, Ethyl thiourea, thiourea, is disclosed in U.S. Patent No. 6,610,192 to Step et al., U.S. Patent No. 7,128,822 to Wang et al., U.S. Patent No. 7,374,652 to Hayashi et al., and to Hagiwara et al. Those of the patents 6,800,188. Such leveling agents can be included in known amounts. When included, it is included in an amount of from 1 ppb to 1 g/L. It is preferred to exclude the leveling agent from the bath.

Conventional nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants can be included in the acid copper plating bath. Such surfactants are well known in the art and are mostly commercially available. Typically the surfactant is a nonionic surfactant. Generally speaking, Surfactants are included in conventional amounts. Generally, it may be included in the plating bath in an amount of from 0.05 g/l to 15 g/L.

Halogen ions include chloride ions, fluoride ions, and bromide ions. Such halides are typically added to the bath in the form of a water soluble salt or acid. Preferably, the copper electroplating bath comprises chloride ions. The chloride ion is preferably introduced into the bath in the form of hydrochloric acid or in the form of sodium chloride or potassium chloride. Preferably, chloride ions are added to the bath in the form of hydrochloric acid. The halogen content included in the bath may be from 20 ppm to 500 ppm, preferably from 20 ppm to 100 ppm.

The low stress, high ductility acid copper electroplating bath has a pH in the range of less than 1 to less than 7, preferably less than 1 to 5, more preferably less than 1 to 2, and the pH is preferably less than 1 to 1.

The plating can be DC plating, pulse plating, pulse commutation plating, photo induction plating (LIP) or photo-assisted plating. Preferably, the low stress, high ductility copper film is electroplated by DC, LIP or photo-assisted plating. Generally, current densities range from 0.5 to 50 ASD, depending on the application. Typically, current densities range from 1 ASD to 20 ASD or such as 4 ASD to 20 ASD or 15 ASD to 20 ASD. The electroplating is carried out at a temperature ranging from 15 ° C to 80 ° C or such as from room temperature to 60 ° C or such as from 20 ° C to 40 ° C or such as from 20 ° C to 25 ° C.

The internal stress and ductility of the copper film can be measured using a conventional method. Typically, low internal stresses are measured using a sediment stress analyzer, such as the Specialty Testing and Development Co., available from Jacobs, PA. The low internal stress can be determined using the equation S=U/3TxK, where S is the stress in psi, U is the incremental number of deflections on the calibration scale, T is the thickness of the deposit in 吋, and K is the test strip With calibration constants. The constant can be changed and by Provided by the accumulation stress analyzer. After electroplating and then several days after aging, the low internal stress is measured immediately, preferably two days after the copper film is deposited on the substrate, such as a conventional copper/niobium alloy test strip. The internal stress measurement was carried out immediately after electroplating and after aging at room temperature. When the room temperature is changed, in order to measure the internal stress, the room temperature is usually in the range of 18 ° C to 25 ° C, preferably 20 ° C to 25 ° C. Preferably, a copper film of 1 μm to 10 μm, more preferably 1 μm to 5 μm, is plated on the test strip. The initial internal stress measured immediately after plating the copper on the substrate may range from 0 psi to 950 psi at room temperature, preferably from 0 psi to 900 psi, more preferably from 0 psi to 850 psi. After aging (e.g., two days), the internal stress can range from 300 psi to 900 psi at room temperature, preferably from 300 psi to 850 psi, more preferably from 300 psi to 840 psi. When the internal stress slightly changes during the two-day aging period, the measurement of the internal stress of the copper film of the present invention at room temperature after the two-day aging period usually does not significantly change.

The ductility is measured using conventional elongation tests and devices. Preferably, the elongation test is performed using an industry standard IPC-TM-650 method using a device such as the Instron pull tester 33R4464. The copper is plated on a substrate such as a stainless steel panel. Usually, copper is electroplated on the substrate in a film form to a thickness of 50 μm to 100 μm, preferably 60 μm to 80 μm. The copper is stripped from the substrate and annealed for 1 to 5 hours, preferably 2 to 5 hours. Annealing is carried out at a temperature of from 100 ° C to 150 ° C, preferably from 110 ° C to 130 ° C. The elongation or load of the maximum tensile stress is usually not a preset parameter. The greater the load of the maximum tensile stress that the material can withstand before failure or cracking, the higher or better ductility. Typically, the elongation is carried out under a load of 50 lbf or maximum tensile stress. Preferably, the elongation is carried out under a load of a tensile stress of 60 lbf or more. More preferably, the maximum stretch at 70 lbf to 90 lbf Perform under stress loading. The elongation ranges from greater than or equal to 8%, preferably from 9% to 15%.

The low stress, high ductility acid copper electroplating bath and method are used on a relatively thin substrate (eg, a semiconductor wafer of 100 μm to 220 μm or such as 100 μm to 150 μm) or on a substrate side having problems of bending, curling, or warpage Electroplated copper. The low stress, high ductility acid copper electroplating bath can also be used to electroplate copper on substrates that are common for foaming, flaking or cracking of deposits that are difficult to adhere. For example, the method can be used to manufacture printed circuits and wiring boards, such as flexible circuit boards for photovoltaic devices and solar cells, flexible circuit antennas, RFID tags, electrolytic foils, semiconductor wafers, the sun The battery includes an interdigitated trailing edge contact solar cell, a heterojunction (HIT) cell with an intrinsic thin layer, and a fully plated front contact cell. The acid copper plating bath is used to electroplate copper preferably in a thickness range of 1 μm to 5 mm of electroplated copper, more preferably 5 μm to 1 mm. When copper is used as the main conductor for forming the contacts of the solar cell, the copper is preferably plated to a thickness in the range of 1 μm to 60 μm, more preferably 5 μm to 50 μm.

The copper deposit has a low internal stress and a relatively large grain structure. In addition, the internal stress and grain structure do not substantially change with the aging of the deposit, thereby increasing the predictability of the performance of the copper electroplating bath and the deposits using the electroplating thereof. The low internal stress copper deposit also has excellent ductility such that it does not easily crack on the substrate as compared to many conventional copper deposits. The copper plated with the bath of the present invention has a good balance between low stress and ductility, which was not found when copper was electroplated using many conventional copper baths. The copper electroplating bath can be used to deposit copper on relatively thin substrates without substantial problems that the substrate may bend, warp, deform, foam, flake or crack.

The following examples are provided to illustrate the invention, but not to limit its scope.

Example 1

The following aqueous acid copper plating bath was prepared.

The components of the copper electroplating bath are made using conventional laboratory procedures in which organics are added to the water followed by the addition of inorganic components. Stirring or agitation is carried out with heating at a temperature below 30 ° C to ensure that all components are dissolved in the water. The bath was allowed to reach room temperature prior to copper plating. The pH of the acid copper electroplating bath ranges from less than 1 to 1 at room temperature and during copper plating.

Example 2

The dielectric is coated on one side of the two flexible copper alloy foil test strips so that one side plating can be performed on the uncoated side. The test strip was adhered to the support substrate with a plating tape and placed in a Haring cell containing an acid copper plating bath having the formulation of the bath 1 of the watch in Example 1. The bath was kept at room temperature. A copper metal strip is used as the anode. The test foil strip and anode are connected to a rectifier. The test foil strip is 2 ASD The average current density was copper plated to deposit a 5 [mu]m copper thickness on the uncoated side of each strip. After the plating is complete, the test strip is removed from the Harlem tank, rinsed with water, dried and the electroplated tape removed from the test strip. The internal stress of the copper deposit on the strip was determined to be 838 psi. The internal stress can be determined using the equation S = U / 3TxK, where S is the stress in psi and U is the incremental number of deflections on the calibration scale. T is the sediment thickness in 吋, and K is the test strip calibration constant. After the test strips were aged for 2 days, the stress of each strip was determined to be 837 psi. The internal stress of the copper deposit after aging remains substantially the same.

Elongation tests were also performed using the industry standard LPC-TM-650 method. 75 μm copper was electroplated on a stainless steel panel at 3.8 ASD. The copper film was peeled off after electroplating and annealed at 125 ° C for 4 hours. The tensile test was performed on an Instron pull tester 33R4464. The elongation of bath 1 was 14% and the load at maximum tensile stress was 76 lbf. The results show that the internal stress is low and ductile for copper deposits electroplated with a bath containing polyallylamine and (O-ethyldithiocarbamate)-S-(3-sulfopropyl)-ester potassium salt. high.

Example 3 (comparative)

The dielectric is coated on one side of the two flexible copper/bismuth alloy foil test strips so that one side plating can be performed on the uncoated side. > The test strip was adhered to the support substrate with a plating tape and placed in a Harlem tank containing an acid copper plating bath 2. The bath was at room temperature. A copper metal strip is used as the anode. The test foil strip and anode are connected to a rectifier. The test foil strips were copper plated at an average current density of 2 ASD to deposit a 5 [mu]m copper thickness on the uncoated side of each strip. After the plating is completed, the test strip is removed from the Harlem tank, rinsed with a wafer, dried and self-tested by plating tape Remove the strip from the strip. One end of the test strip was inserted into a screw clamp of a sediment stress analyzer. The internal stress of the copper deposit on the strip was determined to be 211 psi. The internal stress can be determined using the equation S=U/3TxK, where S is the stress in psi, U is the incremental number of deflections on the calibration scale, T is the thickness of the deposit in 吋, and K is the test strip Calibration constant. After the test strips were aged for 2 days, the internal stress of each strip was determined to be 299 psi.

Elongation tests were also performed using the industry standard IPC-TM-650 method. 75 μm copper was electroplated on a stainless steel panel at 3.8 ASD. The copper film was peeled off after electroplating and annealed at 125 ° C for 4 hours. The tensile test was performed on an Instron pull tester 33R4464. The copper plated with bath 2 had an elongation of 7% and a load at maximum tensile stress of only 50 lbf. Although the internal stress is low, the ductility of copper is not as high as in bath 1 including polyallylamine. Bath 2 is an example of a conventional acid copper electroplating bath which typically etches a copper film that has low internal stress but is not as ductile as desired.

Example 4 (comparative)

The dielectric is coated on one side of the two flexible copper/bismuth alloy foil test strips so that one side plating can be performed on the uncoated side. The test strip was adhered to the support substrate with a plating tape, and placed in a Harlem tank containing the acid copper plating bath 3 in the table of Example 1. The bath was at room temperature. A copper metal strip is used as the anode. The test foil strip and anode are connected to a rectifier. The test foil strips were copper plated at an average current density of 2 ASD to deposit a 5 [mu]m copper thickness on the uncoated side of each strip. After the plating is complete, the test strip is removed from the Harlem tank, rinsed with the wafer, dried and the electroplated tape removed from the test strip. The test strip was inserted into the screw holder of the sediment stress analyzer at one end. Copper deposits on the strip The internal stress was determined to be 1156 psi. The internal stress can be determined using the equation S=U/3TxK, where S is the stress in psi, U is the incremental number of deflections on the calibration scale, T is the thickness of the deposit in 吋, and K is the test strip Calibration constant. After the test strips were aged for 2 days, the stress of each strip was determined to be 1734 psi.

Elongation tests were also performed using the industry standard IPC-TM-650 method. 75 μm copper was electroplated on a stainless steel panel at 3.8 ASD. The copper film was peeled off after electroplating and annealed at 125 ° C for 4 hours. The tensile test was performed on an Instron pull tester 33R4464. The elongation for copper deposits from bath 3 was 16% and the load at maximum tensile stress was 62 lbf. Although the copper film electroplated with the bath 3 is excellent in ductility, the internal stress exceeds 1000 psi, which is poor. Bath 3 is another example of a conventional acid copper plating in which the internal stress is high and the ductility is good.

Example 5 (comparative)

The dielectric is coated on one side of the two flexible copper/bismuth alloy foil test strips so that one side plating can be performed on the uncoated side. The test strip was adhered to the support substrate with a plating tape and placed in a Harlem tank containing an acid copper electroplating bath similar to bath 1, with the exception that the branching polyethylenimine was replaced by 0.75 ppm with Mw= 2000 g/mol and linear polyethylenimine of the formula:

Wherein y is a number such that the linear polyethylenimine has a weight average molecular weight of about 2000 g/mole.

A copper metal strip is used as the anode. Test foil strip and anode are connected To the rectifier. The test foil strips were copper plated at an average current density of 2 ASD to deposit a 5 [mu]m copper thickness on the uncoated side of each strip. After the plating is complete, the test strip is removed from the Harlem tank, rinsed with the wafer, dried and the electroplated tape removed from the test strip. One end of the test strip was inserted into a screw clamp of a sediment stress analyzer. The internal stress of the copper deposit on the strip was determined to be 631 psi. The internal stress can be determined using the equation S=U/3TxK, where S is the stress in psi, U is the incremental number of deflections on the calibration scale, T is the thickness of the deposit in 吋, and K is the test strip Calibration constant. After the test strips were aged for 2 days, the internal stress of each strip was determined to be 1578 psi.

Elongation tests were also performed using the industry standard IPC-TM-650 method. A 75 μm thick copper film was plated on a stainless steel panel at 3.8 ASD. The copper film was peeled off after electroplating and annealed at 125 ° C for 4 hours. The tensile test was performed on an Instron pull tester 33R4464. The elongation of copper from the bath was 11.8% and the load at maximum tensile stress was 78 lbf. Although the ductility is at a high level, the internal stress exceeds 1000 psi after aging, indicating poor bath performance. The result of bath 4 with linear polyethylenimine and copper not including the combination of polyallylamine and (O-ethyldithiocarbamate)-S-(3-sulfopropyl)-ester potassium salt The bath is generally the same.

Claims (8)

An acid copper electroplating bath comprising one or more sources of copper ions, one or more electrolytes, one or more polyallylamines, one or more (O-ethyldithiocarbonate)-S-(3-sulfopropyl groups An ester, an acid thereof or an alkali metal salt thereof, and one or more inhibitors. The acid copper electroplating bath according to claim 1, wherein the one or more polyallylamines have a weight average molecular weight of 1000 g/mol or more. The acid copper electroplating bath of claim 1, wherein the one or more polyallylamines are present in an amount of from 1 ppm to 10 ppm. The acid copper electroplating bath according to claim 1, wherein the one or more (O-ethyldithiocarbonate)-S-(3-sulfopropyl)-ester, an acid thereof or an alkali metal thereof The salt content is from 100 ppm to 300 ppm. A method comprising: a) contacting a substrate with one or more sources of copper ions, one or more electrolytes, one or more branched polyallylamines, one or more (O-ethyldithiocarbonate)-S-(3- Contacting a copper electroplating bath of a sulfopropyl)-ester, an acid thereof or an alkali metal salt thereof, and one or more inhibitors; and b) plating a low internal stress, high ductility copper on the substrate using the copper plating bath. The method of claim 5, wherein the low internal stress and high ductility copper has a thickness of from 1 μm to 5 mm. The method of claim 5, wherein the substrate is a flexible circuit board, a flexible circuit antenna, a REID tag, an electrolytic foil, or a semiconductor. A copper film having an initial internal stress of 0 psi to 950 psi and an internal stress after aging of 300 psi to 900 psi and a maximum pull of 50 lbf or more Elongation at 8% or greater under load of tensile stress.