KR20110002782A - Gold plating bath for electrode and preparation method of electrode - Google Patents

Abstract

PURPOSE: A gold electroplating bath for the electrode metalization and an electrode formation method using the same are provided to form electrode according to the shape of an opening part of a resist film. CONSTITUTION: A gold electroplating bath for the electrode metalization is made from: sulfurous acid gold alkaline salt or sulfurous acid gold ammonium 1~20 g/L; more than one kinds of component 0.1~100mg/L selected from TI compound, Pb compound and As compound; sodium sulfite 5~150g/L; more than one kinds of compound 1~60g/L selected from inorganic acid salt, carboxylate and hydroxycarboxylic acid salt; more than one kinds of substituted aromatic compound 0.1~200 mmol/L selected from benzoic acid class, aromatic carbonic acid class, aromatic sulphonic acid class, pyridines and the salt thereof. The electrolytic gold plating operates in the electric current density 0.2~2.0 A/d m^2. The electrolytic gold plating operates in the liquid temperature 40~70°C.

Description

Gold plating bath for electrode formation and electrode formation method using same {Gold plating bath for electrode and preparation method of electrode}

The present invention relates to a nonionic electrode gold plating bath that can be optimally used when forming an electrode on a semiconductor wafer and a method of forming an electrode using the same. In particular, among the electrodes, an electrode that can be optimally used when forming a gold bump on a semiconductor wafer suitable for electrode bonding using an anisotropic conductive adhesive and electrode bonding forming a process with a counter metal. It relates to a gold plating bath for forming and an electrode forming method using the same.

In general, as the gold salt, nonionic electrode metal plating is used as a gold salt or gold ammonium sulfite. These gold salts, water-soluble amines acting as stabilizers of the gold deposits derived from the gold salts, trace amounts of T l, Pb, or As compounds as crystallization agents in the plating film, electrolytes, and buffers The gold plating bath is known.

Electroplating using an associated gold plating bath forms electrodes that can be used in electronic circuit boards. Among them, gold bumps formed in integrated circuits on semiconductor wafers have recently been widely used as circuit forming electrodes of semiconductor wafers (see Patent Documents 1 and 2).

3 is a configuration diagram showing an example of a conventional gold bump cross section formed on a wafer.

Formation of gold bumps on a wafer is generally performed as follows. First, an Al electrode 203 having a single minority shape on the wafer 201 is formed by sputtering or the like. For the wafer 201, a silicon wafer or a compound wafer such as GaAs can be used. Next, it is formed on the wafer from the patterned passivation film 20. An opening 205a is formed in the passivation film 205 above the Al electrode 203. Thereafter, an under bump metal (UBM) layer 207 made of a film such as TiW is formed by sputtering. The UBM layer 207 covers the passivation film 205 and the Al electrode 203 exposed at the opening 205a. A gold sputtered film 209 is formed on the UBM layer 207, and a mask is formed on the gold sputtered film 209 by a resist film 211. Openings 211a are formed in the resistor film 211 above the Al electrode 203. Gold bumps 213 are formed on the upper surface of the gold resist film 209 in the opening 211a of the resist film 211 by electrolytic plating. Thereafter, the resist film 211 is removed. Subsequently, the portion of the gold sputtered film 209 and the portion of the same UBM film 207 not covered with the gold bump 213 are removed. Thereby, the passivation film 205 is exposed and the wafer in which the gold bump 213 was formed above the Al electrode 203 is obtained.

The gold bumps formed on the wafer are bonded to the electrodes of the substrate to be bonded to the wafer in the subsequent step (electrode bonding). The electrode bonding includes an electrode bonding using an anisotropic conductive adhesive on a film in which conductive particles are dispersed, and an electrode bonding in which a process is formed with a counter metal.

In recent years, the electron bonding method which thermocompresses both using a film-shaped anisotropic conductive adhesive for electrode bonding of an electrode and an electrode for the purpose of simplifying the manufacturing process of a semiconductor package, and performing electrode bonding reliably is used a lot. . In the anisotropic conductive adhesive, conductive particles such as gold-coated resin particles are uniformly dispersed by epoxy resin after nickel coating.

In FIG. 3, 213a is a gold bump bonding surface to which the gold bump 213 is bonded to the substrate. The gold bump 213 213a has an iron shape in which the center thereof is drawn upward with respect to the wafer surface. In addition, there may be a case where the bump joint surface is a yaw type and a shape in which the peripheral edge is cut off and broken. When bump bonding surface 213a is such a shape, the electroconductive particle in anisotropic conductive adhesive will fall easily into the recessed part and peripheral part of a bump bonding surface. For this reason, the conductive particles are not uniformly dispersed and disposed on the gold bump joint surface 213a, and are ubiquitous in a part of the gold bump joint surface 213a. As a result, at the time of joining, the joining area of the gold bump joining surface and the substrate is reduced and the joining force between the gold bump and the substrate is weakened. For this reason, electrical defects occur due to disconnection and poor bonding in subsequent assembly steps.

Therefore, especially when electrode bonding is performed using an anisotropic conductive adhesive agent, it is necessary to form an electrode with a flat bonding surface especially.

Further, the hardness of the conductive particles and gold bumps in the anisotropic conductive adhesive that can be used for electrode bonding and the counter metal forming the process cannot be specified as one. Therefore, various problems arise.

For example, when the hardness of the electrode is lower than that of the conductive particles in the anisotropic conductive adhesive, the conductive particles are embedded in the electrode during thermocompression bonding. As a result, conductive particles are not thermally compressed between the electrode and the substrate at the time of electrode bonding, and the electrode bonding between the electrode and the substrate is insufficient. On the other hand, when the hardness of an electrode is too high compared with the electroconductive particle in an anisotropic conductive adhesive agent, the electroconductive particle will be crushed and broken at the time of thermocompression bonding, and an electrode and a board | substrate will not join an electrode. In the case of the electrode bonding in which the counter metal and the step are formed, when the hardness of the electrode is too high compared with the counter metal in which the step is formed, the electrode does not get stuck in the counter metal and a sufficient step is not formed. As a result, electrical failure due to disconnection and poor bonding occurs.

Therefore, when electrode bonding is performed in the process formed with the anisotropic conductive adhesive and the counter metal, it is necessary to selectively form an electrode having an appropriate hardness.

When forming an electrode using the conventional electrolytic gold plating bath, electrode joining corresponding to both the method using an anisotropic conductive adhesive and the method by process formation becomes difficult. In other words, the electrode having the desired hardness cannot be obtained after the bonding surface is kept flat and subjected to heat treatment. The desired hardness here is 50-120 HV in electrode bonding using an anisotropic conductive adhesive, and 35-60 HV in the case of electrode bonding in the process formed with a counter metal, and this hardness refers to the hardness after heat processing.

As mentioned above, the shape and hardness of an electrode have a big influence on the bonding property of an electrode and a board | substrate. Therefore, the electrode is required to have a predetermined shape and hardness in addition to being excellent in electrical conductivity, oxidation resistance and the like.

[Prior Art Literature]

[Patent Documents]

Patent Document 1: Japanese Patent Application Laid-Open No. 2007-092156

Patent Document 2: Japanese Patent Application Laid-Open No. 2006-322037

An object of the present invention is uniform in appearance of the plated film and has a shape suitable for electrode bonding using an anisotropic conductive adhesive and electrode bonding forming a process with a counter metal, and can be made to a desired hardness by heat treatment. It is providing the gold plating bath for electrode formation for forming an electrode. Another object of the present invention is to provide a plating method for forming an electrode having an uniform appearance and a predetermined shape and hardness by electrolytic plating using this plating bath.

MEANS TO SOLVE THE PROBLEM As a result, when the present inventors examined in order to solve the said subject, by mix | blending predetermined | prescribed substituted aromatic compound in the plating bath at the time of forming an electrode, and mix | blending sodium sulfite as a conducting salt, the appearance of a plating film is uniform and a joining surface is It was found that a flat electrode was obtained. The associated electrode can arbitrarily adjust the hardness after heat treatment in the range of 35-120 HV suitable for electrode bonding of the electrode and the substrate.

This invention which achieves the said objective is described below.

[One]

(a) gold sulfite alkali salts or gold ammonium sulfite as gold concentrations of 1-20 g / L,

(b) one or two or more compounds selected from Tl compounds, Pb compounds, As compounds, and 0.1-100 mg / L as the metal concentration;

(c) 5-150 g / L sodium sulfite as conducting salt,

(d) one or two or more compounds selected from inorganic acid salts, carboxylate salts and hydroxycarboxylic acid salts with a salt concentration of 1-60 g / L,

(e) 0.1-200 mmol / L of benzoic acid, aromatic carboxylic acid, aromatic sulfonic acid, pyridine, and one or two or more substituted aromatic compounds selected from such salts;

Gold plating bath for forming an electrode containing.

In this invention, the invention described below is also included.

[2]

Benzoic acid is 2-hydroxy benzoic acid, 3-hydroxy benzoic acid, 4-hydroxy benzoic acid, 2,3-hydroxy benzoic acid, 2,4-hydroxy benzoic acid, 2,5-dihydroxy benzoic acid, 2,6 -Dihydroxy benzoic acid, 3,4-dihydroxy benzoic acid, 3,5-dihydroxy benzoic acid, 2,3,4-trihydroxy benzoic acid, 3,4,5-trihydroxy benzoic acid, 2-amino benzoic acid , 3-amino benzoic acid, 4-amino benzoic acid, 2-nitro benzoic acid, 3-nitro benzoic acid, 4-nitro benzoic acid, 2,4-dinitro benzoic acid, 2,6-nitro benzoic acid, 3,5-dinitro benzoic acid Gold plating bath for electrode formation as described in [1] which is 1 type, or 2 or more types.

[3]

Aromatic carboxylic acids (except benzoic acid) are DL-4-hydroxymandelic acid, a pyromellitic acid, a metal acid, 2-hydroxy-m-tyl yl, isovanic acid, 1-naphthoic acid 1 type or 2 types selected from 3-hydroxy-2-naphthoic acid, 1,4-dihydroxy-2-naphthoic acid, 3,5-dihydroxy-2-naphthoic acid The gold plating bath for electrode formation of the above-mentioned [1] description.

[4]

Aromatic sulfonic acids are 1-naphtho-yl-8-sulfonic acid, 2-naphtho-yl-7-sulfonic acid, 2-naphtho-yl-6,8-disulfonic acid, 2-amino-5-naph Selected from earth-yl-7-sulfonic acid, 1,5-naphthalenesulfonic acid, 2,7-naphthalenesulfonic acid, gamma acid, naphthalene-1.3.6-trisulfonic acid, metal acid, aminoJ acid, crosane acid Gold plating bath for electrode formation as described in [1] which is 1 type, or 2 or more types.

[5]

Pyridine is 1 type, or 2 or more types chosen from 2-pyridine carboxylic acid, 3-pyridine carboxylic acid, 4-pyridine carboxylic acid, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, [1] ] Gold plating bath for electrode formation of base material.

[6]

The electrode is formed in the opening of the resist film by plating the wafer using the electrode plating gold plating bath according to any one of [1]-[5], and then the wafer is heat-treated at 150 to 400 ° C. for at least 5 minutes. The electrode formation method by which the electrode whose hardness is 35-120 HV and the height difference of a joining surface is less than 2 micrometers is formed in a wafer.

[7]

The electrode formation method as described in [6] which performs electrolytic gold plating whose current density is 0.2-2.0 A / dm <2>, and temperature is 40-70 degreeC.

[8]

The electrode formation method as described in [6] whose electrode is a gold bump.

Since the electrode formed using the plating bath of this invention has a flat joining surface and predetermined hardness, the electrode joining through an anisotropic conductive adhesive through an anisotropic conductive adhesive and the electrode joining forming a process with a counter metal are easy in a semiconductor manufacturing process. It is done surely. In addition, the rate at which disconnection and bonding failure occurs is very low. In particular, the hardness after heat treatment of the electrode can be controlled to an arbitrary value in the range of 35 to 120 HV suitable for electrode bonding with an anisotropic conductive adhesive and electrode bonding forming a process with a counter metal. Therefore, such a plating bath is suitable for formation of a gold bump.

The electrode formed using the plating bath of this invention is uniform in plating film, and is excellent in electrical conductivity, oxidation resistance, etc.

The electrode formed using the plating bath of the present invention does not only cause swelling on the side surface of the electrode in contact with the resist film but also on the bonding surface. Therefore, the electrode can be formed in accordance with the shape of the opening of the resist film. Therefore, it is possible to form the electrodes of the columnar shape and the polygonal shape in which the side surface was planar, and the columnar electrode of uniform particle diameter.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows an example regarding the gold bump cross section formed using the plating bath of this invention.
It is a drawing substitution photograph by the metal microscope which shows the external appearance of the gold bump of Example 1. FIG.
3 is a block diagram showing an example of a cross section of a gold bump formed using a conventional gold plating bath.
It is a drawing substitute photograph by the metal microscope which shows the external appearance of the gold bump of the comparative example 1. FIG.

Hereinafter, each component about the essential component of the gold plating bath for electrode formation of this invention is demonstrated.

(1) Gold sulfite alkali salts, gold ammonium sulfite (gold raw material)

As a gold sulfite alkali salt used for the gold plating bath for electrode formation of this invention, a well-known gold sulfite alkali salt can be used without restrict | limiting. For example, gold (I) sodium sulfite and gold (I) potassium sulfite may be recommended. These may be used individually by 1 type or in combination of 2 or more types.

The compounding quantity of the gold sulfite alkali salt or the gold ammonium sulfite is 1-20 g / L in gold concentration, and 10-16 g / L is preferable. If it is less than 1 g / L, the thickness of a plated film will become nonuniform, and if it exceeds 20 g / L, the characteristic of a plated film, etc. will not be a problem, but manufacturing cost will become high.

(2) Tl compound, Pb compound, As compound (crystal regulator)

As a crystal | crystallization regulator used for the gold plating bath for electrode formation of this invention, Tl compounds, such as thallium formate, thallium malonate, thallium sulfate, and thallium acetate; Pb compounds, such as lead citrate, lead acetate, and alkane sulfonate; As compounds such as arsenic trioxide may be recommended. These may be used individually by 1 type and may be used in combination of 2 or more type.

The compounding quantity of a crystal regulator is 0.1-100 mg / L in a metal concentration, 0.5-50 mg / L is preferable and 10-35 mg / L is especially preferable. If it is less than 0.1 mg / L, the plating adhesion, the stability and durability of the plating bath deteriorate. In addition, the components of the plating bath may decompose. When it exceeds 100 mg / L, deterioration of plating adhesion and appearance unevenness occur in the plating film.

(3) sodium sulfite (conductive salt)

In the gold plating bath for electrode formation of this invention, sodium sulfite is used as a conductive salt. The compounding quantity of sodium sulfite is 5-150 g / L, 10-80 g / L is preferable and 30-60 g / L is especially preferable. If it is less than 5 g / L, the swelling of the electrode shape is not sufficiently controlled, and an electrode having a flat joint surface cannot be obtained. In addition, the plating adhesion circumference becomes uneven and plating bath stability deteriorates. As a result, the constituent components of the plating bath may decompose. If it exceeds 150 g / L, the limit current density decreases and the plating burns.

(4) inorganic salts, carboxylic acids, hydroxycarboxylic acids (buffers)

As a buffer used for the gold plating bath for electrode formation of this invention, a well-known thing can be used. For example, inorganic acid salts such as phosphate salts and borate salts, organic acid salts such as citrate salts, phthalate salts and ethylenediamino tetraacetic acid salts may be recommended.

The compounding quantity of a buffer is 1-60 g / L, 5-40 g / L is preferable and 10-30 g / L is especially preferable. When it is less than 1 g / L, pH is low and plating bath stability deteriorates, and the component of a plating bath may decompose. If it exceeds 60 g / L, the limit current density decreases and the plating burns.

(5) substituted aromatic compounds

As the substituted aromatic compound to be incorporated into the gold plating bath for forming an electrode of the present invention, a compound which dissolves 0.1-200 mmol / L in 20 ° C water is selected.

For example, 2-hydroxy benzoic acid, 3-hydroxy benzoic acid, 4-hydroxy benzoic acid, 2,3-dihydroxy benzoic acid, 2,4-dihydroxy benzoic acid, 2,5-dihydroxy benzoic acid, 2 , 6-dihydroxy benzoic acid, 3,4-dihydroxy benzoic acid, 3,5-dihydroxy benzoic acid, 2,3,4-trihydroxy benzoic acid, 3,4,5-trihydroxy benzoic acid, 2- Amino benzoic acid, 3-amino benzoic acid, 4-amino benzoic acid, 2-nitro benzoic acid, 3-nitro benzoic acid, 4-nitro benzoic acid, 2,4-dinitro benzoic acid, 2,6-dinitro benzoic acid, 3,5-dinitro Benzoic acid and its salts, such as benzoic acid,

DL-4-hydroxybenzoic acid, pyromellitic acid, metal acid, 2-hydroxy-m-truic acid, isovanlinic acid, 1-naphthoic acid, 3-hydroxy-2-naphthoic acid, 1, Aromatic carboxylic acids (except benzoic acids) and salts thereof, such as 4-dihydroxy-2-naphthoic acid and 3,5-dihydroxy-2-naphthoic acid;

1-naphtho-yl-8-sulfonic acid, 2-naphtho-yl-7-sulfonic acid, 2-naphtho-yl-6,8-disulfonic acid, 2-amino-5-naphtho-yl-7 Aromatics such as sulfonic acid, 1,5-naphthalenedisulfonic acid, 2,7-naphthalenedisulfonic acid, gamma acid, naphthalene-1.3.6-trisulfonic acid, metal acid, aminoJ acid, croceic acid Sulfonic acids and salts thereof,

Pyridines and salts thereof, such as 2-pyridinecarboxylic acid, 3-pyridinecarboxylic acid, 4-pyridinecarboxylic acid, chinolic acid, 2-aminopyridine, 3-aminopyridine, and 4-aminopyridi, may be recommended.

The compounding quantity of a substituted aromatic compound is 0.1-200 mmol / L, and 0.2-150 mmol / L is preferable. If it is less than 0.1 mmol / L, an electrode having a flat junction surface cannot be obtained. When it exceeds 200 mmol / L, it does not melt | dissolve in a plating liquid, or a limit current density falls and plating will burn.

By adjusting the compounding quantity of a substituted aromatic compound in the said range, it is possible to adjust the hardness of the electrode after heat processing to the range of 35-120 HV. In addition, the greater the blending amount of the substituted aromatic compound, the greater the hardness of the electrode.

In the gold plating bath for electrode formation of this invention, you may use suitably other components, such as a pH adjuster, in the range which does not impair the objective of this invention. As the pH adjuster, for example, acetic acid, sulfurous acid water, phosphoric acid, etc. may be recommended as the acid, sodium hydroxide, aqueous ammonia, etc. as the alkali.

In order to form an electrode on a semiconductor wafer by plating using the gold plating bath for electrode formation of this invention, plating operation may be performed according to a conventional method. A method of forming gold bumps on a semiconductor wafer using the gold plating bath for electrode formation of the present invention will be described.

1 is a block diagram showing an example of a gold bump cross section that can be formed on a wafer using the gold plating bath for electrode formation of the present invention. In FIG. 1, 11 is a wafer, and a well-known compound wafer, such as a silicon wafer or GaAs, can be used. First, the Al electrode 13 of single-axis columnar phase is formed on the wafer 11 by sputtering or the like. Next, a patterned passivation film 15 is formed. In the passivation film 15, the opening part 15a is formed above the Al electrode 13. Then, UBM layer 17 made of a film such as TiW is formed by sputtering. The UBM layer 17 covers the passivation film 15 and the Al electrode 13 exposed through the opening 15a. A gold sputtering film 19 is formed on the UBM layer 17, and a mask is formed on the gold sputtering film 19 by using a resist film 21. In the resist film 21, an opening portion 21a is formed above the Al electrode 13. The said process can be performed by a well-known method. Using the gold plating bath for electrode formation of this invention, the wafer in which the opening part 21a was formed is plated. As a result, gold bumps 23 are formed in the openings 21a of the resist film 21. Thereafter, the resist film 21 is removed by a known method, and then a portion of the gold sputtered film 19 and a portion of the same UBM film 17 not covered with the gold bump 23 are removed by a known method. Thereby, the passivation film 15 is exposed and the wafer in which the gold bump 23 was formed is obtained.

The gold bump bonding surface 23a formed by the above is flat, and the height difference (after-mentioned) of bump bonding surface is 12 micrometers or more.

As the mask agent, a novolak-based positive photoresist may be used. As a commercial item, LA-900, HA-900 (above, the Tokyo Chemical Industry Co., Ltd.) etc. can be recommended, for example.

Plating temperature is 40-70 degreeC normally, and 50-65 degreeC is preferable. When plating bath temperature is out of the range of 40-70 degreeC, a plating film may be hard to precipitate. In addition, the plating bath may become unstable and the plating bath components may decompose.

The set current density used for the plating may be appropriately determined because the appropriate range varies depending on the composition, the temperature, and the like of the plating solution. For example, gold concentration is 2.0 A / dm <2> or less, Preferably it is 0.2-1.2 A / dm <2> on conditions of the plating bath temperature of 8-15 g / L and 60 degreeC. If the set current density is out of the above range, the workability may deteriorate. In addition, abnormalities may occur in the plating film appearance and the plating film properties. In addition, the plating bath may become unstable remarkably and may cause decomposition of the plating bath constituents.

PH of the plating bath for electrode formation of this invention is 7.0 or more, and 7.2-10.0 are preferable. If it is less than 7.0, the plating bath becomes unstable remarkably and may cause decomposition of the plating bath constituents. When it exceeds 10.0, a mask agent may melt | dissolve in a plating bath, and a desired gold bump may not be formed.

In the gold plating bath for electrode formation of the present invention, by supplementing and managing other components constituting the gold source and the plating bath, 2 (the entire amount of gold in the plating bath is consumed by plating). It is possible to use more than).

The gold plating bath for electrode formation of this invention does not select a to-be-plated object, if a base material is metallized and it is through electricity. It can be used especially suitably when gold bumps are formed on the patterned silicon wafer and the circuit of compound wafers, such as a Ga / As wafer, using a novolak positive type photoresist as a mask material.

Next, heat treatment of the wafer on which the electrode is formed is performed. Heat treatment is performed by heat-processing at 150-400 degreeC for 5 minutes or more. More preferable heat processing is performed by heat processing for 20 to 30 minutes at 200-350 degreeC. The heat treatment is performed using a fine oven or the like capable of maintaining the inside of the chamber at a predetermined temperature for a predetermined time. By this heat treatment, the hardness of the electrode is 35-120 HV.

[Example]

The present invention is specifically described by referring to the following examples, but the present invention is not limited to these examples.

(Examples 1-49, Comparative Example 1-10)

The nonionic electrolytic gold plating bath was adjusted by the formulation shown in Table 1-6. The unit of the compounding concentration of each raw material is (g / L) unless otherwise stated. However, Na ₃ Au (SO ₃ ) ₂ represents the concentration of the gold element.

As the plated material, a silicon wafer having a patterned bump opening, which is a novolak-based positive photoresist (a gold cross-sectional composition / TiW / SiO ₂ ), was used. In 1 L of each plating bath held at 60 ° C., a silicon wafer having the bump openings was deposited, and plating was performed at 0.8 A / dm 2 for 35 minutes to form a plating film having a film thickness of 18 μm. In addition, the current efficiency of nonionic electrolytic plating is 100% under normal plating operation conditions.

Subsequently, the mask agent was removed, and the shape of the formed bumps, roughness, appearance of the plated film, and coating hardness (200 ° C. × 30 minutes, and 300 ° C. × 30 minutes after the heat treatment, if not heat treated) were determined in the following methods and standards. Evaluation was made. The results are shown in Table 1-6.

[Evaluation of Bump Shape (μm)]

As shown in FIG. 1, patterning was carried out using a novolak positive photoresist on a silicon wafer, with one side having a square opening of 100 mu m. After plating was performed using electrolytic gold plating, the novolak-based positive photoresist was dissolved with methyl ethyl ketone. About the obtained gold bump, the difference of the highest point (minimum point of the distance of a bump surface and a bump surface) of a bump bonding surface was measured using the laser microscope VK-9710 made from Keyence Co., Ltd., and was made into the index of smoothness. In addition, the height difference required for bump plating use is 3 micrometers or less normally, and 2 micrometers or less are preferable.

[Stability]

The state of the plating bath after plating in the to-be-plated object was observed, and the following reference | standard evaluated.

X: The precipitation of gold in the plating bath was observed with the visually judged level.

O: Gold precipitation was not observed in the plating bath.

[Plating film appearance]

The surface coating appearance of the gold bump formed on the to-be-plated object was observed and evaluated by the following criteria.

X: Hue is red, dendrite phase precipitation is found, a stain is confirmed, and soot is generated.

O: uniform appearance.

[Film Hardness (Vickers Hardness; HV)]

The film hardness (after heat treatment at 200 ° C. × 30 minutes and 300 ° C. × 30 minutes, if not subjected to heat treatment) of the gold bumps at the specific site formed on the plated material was measured by Mitsudoyo's micro hardness tester HM-221. In addition, the measurement used the forward bump of 100 micrometers on one side, and the measurement conditions were based on the conditions which hold a measurement indenter at 25 gf load for 10 second.

[Comprehensive Evaluation]

From the above evaluation results, the following evaluation criteria were evaluated.

O: The said evaluation result regarding the formed gold plating film (gold bump) and the nonionic electrolytic gold plating bath after plating process was all favorable results.

X: Unfavorable result is contained in the said evaluation result regarding the formed gold plating film (gold bump) and the nonionic electrolytic gold plating bath after plating process.

(Comparative Example 9)

Substituted aromatic compound A of Example 1: 50 (mmol / L) was converted into propionic acid (aliphatic carboxylic acid) 100 (mmol / L), and the plating film was formed based on Example 1. The film hardness of the obtained gold bumps was 55 HV (after 30 minutes heat treatment at 200 ° C.), 51 HV (after 30 minutes heat treatment at 300 ° C.), and the height difference was 3.7 μm, and the plating film had an uneven appearance.

(Comparative Example 10)

Substituted aromatic compound A of Example 1: 50 (mmol / L) was converted into hydroxymethanesulfonic acid (aliphatic sulfonic acid) 100 (mmol / L), and a plating film was formed based on Example 1. The obtained gold film hardness (after 30-minute heat treatment at 200 ° C) was 52 HV, (after 30-minute heat treatment at 300 ° C) was 46 HV, and the elevation was 4.0 µm, and the plated film had an uneven appearance.

The height difference of the joining surface of the gold bumps (Examples 1-49) formed using the gold plating bath for electrode formation of this invention was 2 micrometers or less. On the other hand, the height difference of the joining surface of the gold bumps (Comparative Examples 1, 9, 10) formed without using the electrode plating gold plating bath of the present invention exceeded 2 µm.

The hardness after heat treatment of the gold bumps (Examples 1-49) formed using the electrode plating gold plating bath of the present invention was 35-120 HV. In addition, by changing the concentration of the substituted aromatic compound, the hardness after heat treatment could be arbitrarily selected in the range of 35-120 HV.

The plating film appearance of the gold bumps (Examples 1-49) formed by using the gold plating bath for electrode formation of the present invention was uniform and good in all. On the other hand, the appearance of the plating film of the gold bumps (Comparative Examples 1-8) formed without using the electrode plating gold plating bath of the present invention is red in hue, and the pattern in which dendrite precipitation is found is confirmed or sooting occurs. .

Example One 2 3 4 5 6 7 8 9 10 Compound concentration (g / L)
Na ₃ Au (SO ₃ ) ₂ as Au
Na ₂ SO ₃
Phosphate → Sodium
Tl (mg / L)
Substituted Aromatic Compound A (mmol / L)
Substituted Aromatic Compound B (mmol / L)
Substituted Aromatic Compound C (mmol / L)
Substituted Aromatic Compound D (mmol / L)
Substituted Aromatic Compound E (mmol / L)
Substituted Aromatic Compound F (mmol / L)
Substituted Aromatic Compound G (mmol / L)
pH
15
40
10
30
0.2
―
―
―
―
―
―
8.0
15
40
10
30
One
―
―
―
―
―
―
8.0
15
40
10
30
15
―
―
―
―
―
―
8.0
15
40
10
30
50
―
―
―
―
―
―
8.0
15
40
10
30
100
―
―
―
―
―
―
8.0
15
40
10
30
150
―
―
―
―
―
―
8.0
15
40
10
30
―
0.2
―
―
―
―
―
8.0
15
40
10
30
―
One
―
―
―
―
―
8.0
15
40
10
30
―
15
―
―
―
―
―
8.0
15
40
10
30
―
50
―
―
―
―
―
8.0 Plating condition
Plating temperature (℃)
Current density (A / dm²)
Film thickness (㎛)
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18 Bump condition
Height difference (㎛)
Bath stability
Plating film appearance
Film hardness
Without heat treatment (HV)
After 200 ℃ Heat Treatment (HV)
After 300 ℃ Heat Treatment (HV)
Total evaluation
1.75
O
O

85
42
39
O
1.59
O
O

96
70
53
O
1.33
O
O

96
70
53
O
1.18
O
O

95
90
73
O
1.21
O
O

115
103
82
O
1.15
O
O

122
119
85
O
1.85
O
O

80
40
37
O
1.62
O
O

89
65
49
O
1.29
O
O

98
79
63
O
1.20
O
O

110
91
75
O

Substituted aromatic compound A: 2,5-dihydroxy benzoic acid

Substituted aromatic compound B: 3,5-dihydroxy benzoic acid

Substituted aromatic compound C: 3-hydroxy-2-naphthoic acid

Substituted aromatic compound D: 3,5-dihydroxy-2-naphthoic acid

Substituted aromatic compound E: 2-naphtho-yl-7-sulfonic acid

Substituted Aromatic Compounds F: 2-Amino-5-naphtho-yl-7-sulfonic acid

Substituted aromatic compound G: 2-pyridine carboxylic acid

Example 11 12 13 14 15 16 17 18 19 20 Compound concentration (g / L)
Na ₃ Au (SO ₃ ) ₂ as Au
Na ₂ SO ₃
Phosphate → Sodium
Tl (mg / L)
Substituted Aromatic Compound A (mmol / L)
Substituted Aromatic Compound B (mmol / L)
Substituted Aromatic Compound C (mmol / L)
Substituted Aromatic Compound D (mmol / L)
Substituted Aromatic Compound E (mmol / L)
Substituted Aromatic Compound F (mmol / L)
Substituted Aromatic Compound G (mmol / L)
pH
15
40
10
30
―
100
―
―
―
―
―
8.0
15
40
10
30
―
150
―
―
―
―
―
8.0
15
40
10
30
―
―
0.2
―
―
―
―
8.0
15
40
10
30
―
―
One
―
―
―
―
8.0
15
40
10
30
―
―
15
―
―
―
―
8.0
15
40
10
30
―
―
50
―
―
―
―
8.0
15
40
10
30
―
―
100
―
―
―
―
8.0
15
40
10
30
―
―
150
―
―
―
―
8.0
15
40
10
30
―
―
―
0.2
―
―
―
8.0
15
40
10
30
―
―
―
One
―
―
―
8.0 Plating condition
Plating temperature (℃)
Current density (A / dm²)
Film thickness (㎛)
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18 Bump condition
Height difference (㎛)
Bath stability
Plating film appearance
Film hardness
Without heat treatment (HV)
After 200 ℃ Heat Treatment (HV)
After 300 ℃ Heat Treatment (HV)
Total evaluation
1.21
O
O

118
99
86
O
1.15
O
O

125
118
93
O
1.76
O
O

95
40
39
O
1.44
O
O

108
63
50
O
1.28
O
O

115
86
62
O
1.19
O
O

122
103
75
O
1.19
O
O

126
115
90
O
1.14
O
O

123
119
92
O
1.78
O
O

82
42
37
O
1.62
O
O

92
62
53
O

Substituted aromatic compound A: 2,5-dihydroxy benzoic acid

Substituted aromatic compound B: 3,5-dihydroxy benzoic acid

Substituted aromatic compound C: 3-hydroxy-2-naphthoic acid

Substituted aromatic compound D: 3,5-dihydroxy-2-naphthoic acid

Substituted aromatic compound E: 2-naphtho-yl-7-sulfonic acid

Substituted Aromatic Compounds F: 2-Amino-5-naphtho-yl-7-sulfonic acid

Substituted aromatic compound G: 2-pyridine carboxylic acid

Example 21 22 23 24 25 26 27 28 29 30 Compound concentration (g / L)
Na ₃ Au (SO ₃ ) ₂ as Au
Na ₂ SO ₃
Phosphate → Sodium
Tl (mg / L)
Substituted Aromatic Compound A (mmol / L)
Substituted Aromatic Compound B (mmol / L)
Substituted Aromatic Compound C (mmol / L)
Substituted Aromatic Compound D (mmol / L)
Substituted Aromatic Compound E (mmol / L)
Substituted Aromatic Compound F (mmol / L)
Substituted Aromatic Compound G (mmol / L)
pH
15
40
10
30
―
―
―
15
―
―
―
8.0
15
40
10
30
―
―
―
50
―
―
―
8.0
15
40
10
30
―
―
―
100
―
―
―
8.0
15
40
10
30
―
―
―
150
―
―
―
8.0
15
40
10
30
―
―
―
―
0.2
―
―
8.0
15
40
10
30
―
―
―
―
One
―
―
8.0
15
40
10
30
―
―
―
―
15
―
―
8.0
15
40
10
30
―
―
―
―
50
―
―
8.0
15
40
10
30
―
―
―
―
100
―
―
8.0
15
40
10
30
―
―
―
―
150
―
―
8.0 Plating condition
Plating temperature (℃)
Current density (A / dm²)
Film thickness (㎛)
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18 Bump condition
Height difference (㎛)
Bath stability
Plating film appearance
Film hardness
Without heat treatment (HV)
After 200 ℃ Heat Treatment (HV)
After 300 ℃ Heat Treatment (HV)
Total evaluation
1.48
O
O

109
80
64
O
1.33
O
O

125
104
76
O
1.29
O
O

122
111
86
O
1.20
O
O

121
115
90
O
1.59
O
O

90
42
40
O
1.32
O
O

102
66
55
O
1.26
O
O

117
84
62
O
1.22
O
O

118
98
72
O
1.09
O
O

129
112
84
O
1.10
O
O

133
114
85
O

Substituted aromatic compound A: 2,5-dihydroxy benzoic acid

Substituted aromatic compound B: 3,5-dihydroxy benzoic acid

Substituted aromatic compound C: 3-hydroxy-2-naphthoic acid

Substituted aromatic compound D: 3,5-dihydroxy-2-naphthoic acid

Substituted aromatic compound E: 2-naphtho-yl-7-sulfonic acid

Substituted Aromatic Compounds F: 2-Amino-5-naphtho-yl-7-sulfonic acid

Substituted aromatic compound G: 2-pyridine carboxylic acid

Example 31 32 33 34 35 36 37 38 39 40 Compound concentration (g / L)
Na ₃ Au (SO ₃ ) ₂ as Au
Na ₂ SO ₃
Phosphate → Sodium
Tl (mg / L)
Substituted Aromatic Compound A (mmol / L)
Substituted Aromatic Compound B (mmol / L)
Substituted Aromatic Compound C (mmol / L)
Substituted Aromatic Compound D (mmol / L)
Substituted Aromatic Compound E (mmol / L)
Substituted Aromatic Compound F (mmol / L)
Substituted Aromatic Compound G (mmol / L)
pH
15
40
10
30
―
―
―
―
―
0.2
―
8.0
15
40
10
30
―
―
―
―
―
One
―
8.0
15
40
10
30
―
―
―
―
―
15
―
8.0
15
40
10
30
―
―
―
―
―
50
―
8.0
15
40
10
30
―
―
―
―
―
100
―
8.0
15
40
10
30
―
―
―
―
―
150
―
8.0
15
40
10
30
―
―
―
―
―
―
0.2
8.0
15
40
10
30
―
―
―
―
―
―
One
8.0
15
40
10
30
―
―
―
―
―
―
15
8.0
15
40
10
30
―
―
―
―
―
―
50
8.0 Plating condition
Plating temperature (℃)
Current density (A / dm²)
Film thickness (㎛)
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18 Bump condition
Height difference (㎛)
Bath stability
Plating film appearance
Film hardness
Without heat treatment (HV)
After 200 ℃ Heat Treatment (HV)
After 300 ℃ Heat Treatment (HV)
Total evaluation
1.77
O
O

78
40
36
O
1.33
O
O

96
59
50
O
1.29
O
O

105
71
63
O
1.20
O
O

118
88
71
O
1.22
O
O

123
103
85
O
1.15
O
O

119
115
91
O
1.83
O
O

82
41
39
O
1.75
O
O

86
56
49
O
1.62
O
O

95
65
54
O
1.59
O
O

101
81
70
O

Substituted aromatic compound A: 2,5-dihydroxy benzoic acid

Substituted aromatic compound B: 3,5-dihydroxy benzoic acid

Substituted aromatic compound C: 3-hydroxy-2-naphthoic acid

Substituted aromatic compound D: 3,5-dihydroxy-2-naphthoic acid

Substituted aromatic compound E: 2-naphtho-yl-7-sulfonic acid

Substituted Aromatic Compounds F: 2-Amino-5-naphtho-yl-7-sulfonic acid

Substituted aromatic compound G: 2-pyridine carboxylic acid

Example 41 42 43 44 45 46 47 48 49 Compound concentration (g / L)
Na ₃ Au (SO ₃ ) ₂ as Au
Na ₂ SO ₃
Phosphate → Sodium
Tl (mg / L)
Substituted Aromatic Compound A (mmol / L)
Substituted Aromatic Compound B (mmol / L)
Substituted Aromatic Compound C (mmol / L)
Substituted Aromatic Compound D (mmol / L)
Substituted Aromatic Compound E (mmol / L)
Substituted Aromatic Compound F (mmol / L)
Substituted Aromatic Compound G (mmol / L)
pH
15
40
10
30
―
―
―
―
―
―
100
8.0
15
40
10
30
―
―
―
―
―
―
150
8.0
15
40
10
30
50
―
50
―
―
―
―
8.0
15
40
10
30
50
―
―
―
50
―
―
8.0
15
40
10
30
50
―
―
―
―
―
50
8.0
15
40
10
30
―
―
50
―
50
―
―
8.0
15
40
10
30
―
―
50
―
―
―
50
8.0
15
40
10
30
―
―
―
―
50
―
50
8.0
15
40
10
30
10
―
10
―
10
―
10
8.0 Plating condition
Plating temperature (℃)
Current density (A / dm²)
Film thickness (㎛)
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18 Bump condition
Height difference (㎛)
Bath stability
Plating film appearance
Film hardness
Without heat treatment (HV)
After 200 ℃ Heat Treatment (HV)
After 300 ℃ Heat Treatment (HV)
Total evaluation
1.35
O
O

122
99
85
O
1.33
O
O

122
108
89
O
1.26
O
O

110
92
79
O
1.41
O
O

114
102
84
O
1.39
O
O

109
96
75
O
1.26
O
O

131
106
86
O
1.24
O
O

123
116
86
O
1.15
O
O

116
105
79
O
1.71
O
O

108
81
69
O

Substituted aromatic compound A: 2,5-dihydroxy benzoic acid

Substituted aromatic compound B: 3,5-dihydroxy benzoic acid

Substituted aromatic compound C: 3-hydroxy-2-naphthoic acid

Substituted aromatic compound D: 3,5-dihydroxy-2-naphthoic acid

Substituted aromatic compound E: 2-naphtho-yl-7-sulfonic acid

Substituted Aromatic Compounds F: 2-Amino-5-naphtho-yl-7-sulfonic acid

Substituted aromatic compound G: 2-pyridine carboxylic acid

Comparative example One 2 3 4 5 6 7 8 Compound concentration (g / L)
Na ₃ Au (SO ₃ ) ₂ as Au
Na ₂ SO ₃
Phosphate → Sodium
Tl (mg / L)
Substituted Aromatic Compound A (mmol / L)
Substituted Aromatic Compound B (mmol / L)
Substituted Aromatic Compound C (mmol / L)
Substituted Aromatic Compound D (mmol / L)
Substituted Aromatic Compound E (mmol / L)
Substituted Aromatic Compound F (mmol / L)
Substituted Aromatic Compound G (mmol / L)
pH
15
40
10
30
―
―
―
―
―
―
―
8.0
15
40
10
30
250
―
―
―
―
―
―
8.0
15
40
10
30
―
250
―
―
―
―
―
8.0
15
40
10
30
―
―
250
―
―
―
―
8.0
15
40
10
30
―
―
―
250
―
―
―
8.0
15
40
10
30
―
―
―
―
250
―
―
8.0
15
40
10
30
―
―
―
―
―
250
―
8.0
15
40
10
30
―
―
―
―
―
―
250
8.0 Plating condition
Plating temperature (℃)
Current density (A / dm²)
Film thickness (㎛)
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18
60
0.8
18 Bump condition
Height difference (㎛)
Bath stability
Plating film appearance
Film hardness
Without heat treatment (HV)
After 200 ℃ Heat Treatment (HV)
After 300 ℃ Heat Treatment (HV)
Total evaluation
4.02
O
X

82
49
45
X
1.76
O
X

126
119
92
X
1.62
O
X

122
109
93
X
1.40
O
X

126
118
95
X
1.42
O
X

121
116
88
X
1.38
O
X

131
129
92
X
1.29
O
X

135
128
89
X
1.83
O
X

110
96
82
X

Substituted aromatic compound A: 2,5-dihydroxy benzoic acid

Substituted aromatic compound B: 3,5-dihydroxy benzoic acid

Substituted aromatic compound C: 3-hydroxy-2-naphthoic acid

Substituted aromatic compound D: 3,5-dihydroxy-2-naphthoic acid

Substituted aromatic compound E: 2-naphtho-yl-7-sulfonic acid

Substituted Aromatic Compounds F: 2-Amino-5-naphtho-yl-7-sulfonic acid

Substituted aromatic compound G: 2-pyridine carboxylic acid

11 wafer, 13 Al electrode
15: passivation film 15a: opening of passivation film
17: UBM layer 19: gold sputter film
21 resist film 21a openings in resist film
23: gold bump 23a: opening of the gold bump
201: wafer 203: Al electrode
205: passivation film 205a: opening of passivation film
207: UBM layer 209: gold sputter film
211: resist film 211a: opening of resist film
213: gold bump 213a: joint surface of the gold bump

Claims (8)

(a) gold sulfite alkali salts or gold ammonium sulfite with a gold concentration of 1-20 g / L,
(b) one or two or more compounds selected from Tl compound, Pb compound, and As compound are 0.1-100 mg / L as the gold concentration;
(c) 5-150 g / L sodium sulfite as the conductive salt,
(d) one or two or more compounds selected from inorganic acid salts, carboxylate salts and hydroxycarboxylic acid salts with a salt concentration of 1-60 g / L,
(e) A gold plating bath for electrode formation, wherein one or two or more substituted aromatic compounds selected from benzoic acids, aromatic carboxylic acids, aromatic sulfonic acids, pyridines, and salts thereof contain 0.1-200 mmol / L.
The method of claim 1,
Benzoic acid is 2-hydroxy benzoic acid, 3-hydroxy benzoic acid, 4-hydroxy benzoic acid, 2,3-dihydroxy benzoic acid, 2,4-dihydroxy benzoic acid, 2,5-dihydroxy benzoic acid, 2 , 6-dihydroxy benzoic acid, 3,4-dihydroxy benzoic acid, 3,5-dihydroxy benzoic acid, 2,3,4-trihydroxy benzoic acid, 3,4,5-trihydroxy benzoic acid, 2- Amino benzoic acid, 3, -amino benzoic acid, 4-amino benzoic acid, 2-nitro benzoic acid, 3-nitro benzoic acid, 4-nitro benzoic acid, 2,4-dinitro benzoic acid, 2,6-dinitro benzoic acid, 3,5-di Gold plating bath for electrode formation which is 1 type (s) or 2 or more types chosen from nitrobenzoic acid.
The method of claim 1,
Aromatic carboxylic acids (except benzoic acid) are DL-4-hydroxymandelic, pyromellitic acid, metal acid, 2-hydroxy-m-triyl acid, isovanlinic acid, 1-naphthoic acid, Formation of one or two or more kinds of electrodes selected from 3-hydro-2-naphthoic acid, 1,4-dihydroxy-2-naphthoic acid, 3.5-dihydroxy-2-naphthoic acid Dragon gold plating bath.
The method of claim 1,
Aromatic sulfonic acids, 1-naphtho-yl-8-sulfonic acid, 2-naphtho-yl-7-sulfonic acid, 2-naphtho-yl-6,8-disulfonic acid, 2-amino-5-naph Sat-yl-7-sulfonic acid, 1,5-naphthalenedisulfonic acid, 2,7-naphthalenedisulfonic acid, gamma acid, naphthalene-1,3,6-trisulfonic acid, metal acid, amino J acid, crosane acid Gold plating bath for electrode formation which is 1 type (s) or 2 or more types chosen from.
The method of claim 1,
Gold plating bath for electrode formation whose pyridines are 1 type or 2 or more types chosen from 2-pyridine carboxylic acid, 3-pyridine carboxylic acid, 4-pyridine carboxylic acid, 2-aminopyridine, 3-aminopyridine, and 4-aminopyridine. .
After forming an electrode in the opening part of a resist film by plating a wafer using the plating bath for electrode formation of any one of Claims 1-5, the said wafer is heat-processed at 150-400 degreeC for 5 minutes or more. The electrode formation method in which the electrode of hardness is 35-120 HV and the height difference of a joining surface is less than 2 micrometers is formed in a wafer.
The method of claim 6,
Electrode gold-plating method with current density of 0.2-2.0 A / dm <2> and liquid temperature of 40-70 degreeC.
The method of claim 6,
A method of forming an electrode, wherein the electrode is a gold bump.

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