KR20060046430A - Etching removing method and etching solution in manufacturing print wiring substrate using semi-additive process - Google Patents

Abstract

The etching removal method which selectively etches chemical copper plating which is a seed layer with respect to the electrical copper plating which is a wiring part in manufacture of a semi additive method printed wiring board, and the etching liquid of copper used by the method are provided.

In the manufacture of the semiadditive method printed wiring board, after forming the seed layer of chemical copper plating on the insulating resin layer and forming the pattern resist, the conductor circuit is formed by the electric copper plating, and then the resist is peeled off and is required by using a selective etching solution. An etching removal method for selectively etching away free chemical copper plating, wherein the selective etching solution contains 0.2 to 15 wt% hydrogen peroxide, 0.5 to 15 wt% sulfuric acid and 0.5 to 5 ppm bromine ions and has a molar ratio of hydrogen peroxide / sulfuric acid of 5 or less It is an etching removal method and a selective etching liquid, and the etching removal method and selective etching liquid which contain 0.001-0.05 weight% of azoles in the said selective etching liquid.

Description

Etching removal method and etching liquid in manufacture of semiadditive method printed wiring board {ETCHING REMOVING METHOD AND ETCHING SOLUTION IN MANUFACTURING PRINT WIRING SUBSTRATE USING SEMI-ADDITIVE PROCESS}

1 is an explanatory diagram showing a result of Example 1. FIG.

2 is an explanatory diagram showing a result of Example 2. FIG.

3 is an explanatory diagram showing a result of Comparative Example 1. FIG.

4 is an explanatory diagram showing a result of Comparative Example 2. FIG.

5 is an explanatory diagram showing a result of Comparative Example 3. FIG.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching method for selectively etching a chemical copper plating as a seed layer with respect to an electrocopper plating as a wiring portion in the manufacture of a semiadditive printed wiring board, and an etching liquid for copper used in the method.

In the manufacturing process of a printed wiring board, electroplating and chemical copper plating are used for copper plating. There is a semiadditive method as a manufacturing method for forming finer wiring. In this wiring forming method, a seed layer of about 0.1 to 2 μm of chemical copper plating is formed on the insulating resin layer, and after the pattern resist is formed, the conductor circuit is formed by electric copper plating. Etching removal of the plating part is performed. As the etching solution, persulfates, hydrogen peroxide-sulfuric acid-alcohols, copper chloride, iron chloride etching solution, and amine etching solution used in the manufacture of a printed wiring board are used (Japanese Patent Laid-Open No. 2003-69218, Japanese Patent Laid-Open No. 2003-60341, See Japanese Patent Application Laid-Open No. 2-60189 and Japanese Patent Laid-Open No. 4-199592).

However, these etching liquids also etch chemical copper plating, and at the same time, electrochemical copper plating is also etched. Therefore, the wiring width and wiring thickness of the conductor circuit formed by the electrocopper plating when etching away the chemical copper plating which is not necessary by the semiadditive method. There is a problem that decreases.

Here, as a method of suppressing the thinness of the wiring width, there is a method of forming a metal film other than copper on the wiring side or surface to etch away the copper of the seed layer (Japanese Patent Laid-Open No. 9-162523 and Japanese Patent Laid-Open No. 2003-78234). See publication number). However, there existed a problem that the number of processes, such as formation of the metal film | membrane other than copper, and the process of peeling simultaneously, etc. increased.

In addition, copper etching solutions using an aqueous solution containing hydrogen peroxide, sulfuric acid, bromine ions and azoles are well known as a roughening etching solution for improving the adhesion between copper and resin (Japanese Patent Laid-Open No. 2000-64067). And Japanese Patent Application Laid-Open No. 2003-3283). These liquids are etching liquids which form irregularities on the copper surface while etching the copper surface, and bromine ions and azoles are added as roughening etching aids. However, since these etching liquids suppress the reduction of the wiring width and wiring thickness of the conductor circuit and maintain the smoothness of the wiring surface, further improvement is desired.

An object of the present invention is an etching liquid having a low etching rate of electric copper plating and a high etching rate of electrocopper plating of chemical copper plating in a printed wiring board manufacturing process using electric copper plating and chemical copper plating in the electronic industry. The chemical copper plating is selectively etched away to suppress the reduction in the wiring width and wiring thickness of the conductor circuit, thereby suppressing disconnection and missing, while maintaining the smoothness of the wiring surface.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined in order to solve the said subject, As a result, in the manufacture of a semiadditive method printed wiring board, the etching removal method of suppressing the etching of the electrical copper plating which is a wiring part, and selectively etching unnecessary chemical copper plating, and The selective etching liquid obtained by containing an azole further in the aqueous solution which consists of hydrogen peroxide, sulfuric acid, and bromine ion used for the said etching method was completed.

That is, the present invention forms a seed layer of chemical copper plating on the insulating resin layer and forms a pattern resist in the manufacture of a semiadditive process printed wiring board, and then forms a conductor circuit with electric copper plating, then peels off the resist and selects An etching removal method for selectively etching away unnecessary chemical copper plating using an etching solution, wherein the selective etching solution contains 0.2 to 15% by weight of hydrogen peroxide, 0.5 to 15% by weight of sulfuric acid, and 0.5 to 5 ppm of bromine ions. It relates to an etching removal method having a molar ratio of 5 or less, a selective etching solution, an etching removal method further comprising 0.001 to 0.01 wt% of azoles in the selective etching solution.

Hereinafter, the present invention will be described in detail.

In the etching removal method of the present invention, in the manufacture of a semiadditive method printed wiring board, after forming a seed layer of chemical copper plating on an insulating resin layer and forming a pattern resist, the conductor circuit is formed of electric copper plating, and then the resist is formed. It peels and selectively etches away unnecessary chemical copper plating using a selective etching solution. The selective etching solution used in the etching removal method is an aqueous solution containing hydrogen peroxide, sulfuric acid, and bromine ions, and further containing azoles in the aqueous solution. Aqueous solution.

The concentration of hydrogen peroxide in the selective etching solution can be treated at 0.2 to 15% by weight, but 0.5 to 10% by weight is particularly suitable, and more preferably 0.5 to 3% by weight. If it is 0.2 weight% or more, management to a hydrogen peroxide concentration will become easy and polishing rate will become enough, while if the hydrogen peroxide concentration is 15 weight% or less, an etching rate will become suitable, and control of polishing amount will become easy. Moreover, you may add well-known hydrogen peroxide stabilizers, such as organic carboxylic acid and organic amine compounds, as needed.

The concentration of sulfuric acid in the selective etching solution is very suitably 0.5 to 15% by weight. If the sulfuric acid concentration is 0.5% by weight or more, the liquid management at the time of treatment is easy, and if the sulfuric acid concentration is 15% by weight or less, the solubility of copper sulfate does not decrease in the process of dissolving copper, and copper sulfate crystals do not precipitate. The molar ratio of hydrogen peroxide / sulfuric acid is preferably 5 or less, particularly preferably 2 or less.

The bromine ion concentration in the selective etching solution is preferably 0.5 to 5 ppm, particularly preferably 1 to 3 ppm. If it is 0.5 ppm or more, the etching rate of an electrocopper plating will be 0.5 micrometer / min or less, and also the surface will become difficult to harmonize. If it is 5 ppm or less, the etching selectivity with respect to the electrocopper plating of chemical copper plating will become enough, without reducing the etching rate of chemical copper plating. As bromine ions, potassium bromide, sodium bromide, bromic acid, salts thereof and the like can be used.

The addition effect of bromine ions decreases the etching rate with the addition amount with respect to the electrocopper plating, which is the wiring portion, but the etching rate does not decrease with any constant addition amount with respect to chemical copper plating. Therefore, selective etching of chemical copper plating becomes possible and the etching rate of chemical copper plating can be obtained stably.

On the other hand, the addition of chlorine ions increases the addition amount of both the electro copper plating and the chemical copper plating, and the etching rate decreases, so that the etching selectivity of the chemical copper decreases (see Comparative Example 1 described later). In the addition of fluorine ions, the etching rate hardly fluctuates even if the amount of addition is increased in both electroplating and chemical copper plating (see Comparative Example 2 described later).

The azoles are added as adjuvants that increase the etching inhibiting effect of the electroplating. By addition, since the etching itself is suppressed, the surface is not harmonized. Examples of the azoles include tetraazoles and triazoles. Tetrasols include 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole and 5-amino-1H-tetrazole, especially 5-amino-1H-tetrazole. May be suitably used. Triazoles include 1H-1,2,4-triazole and 3-amino-1,2,4-triazole.

The concentration of azoles in the selective etching solution is 0.001 to 0.05% by weight, more preferably 0.001 to 0.01% by weight. If it is 0.001 wt% or more, the effect of the additive is sufficiently obtained, and if it is 0.05 wt% or less, the etching time of copper is shortened in both chemical copper plating and electric copper plating, and the reduction in wiring width is suppressed without increasing the inhibitor effect too much. can do.

The selective etching solution of the present invention is an etching solution whose etching rate of the electroplating is 0.5 µm / minute or less. If it is 0.5 micrometer / min or less, wiring width and wiring thickness will become difficult to reduce. Moreover, the etching liquid of this invention is etching liquid whose etching rate of chemical copper plating is 5 times or more with respect to the etching rate of electric copper plating. If it is 5 times or more, the etching removal time of chemical copper plating can be shortened, and as a result, the etching time of electric copper plating is also shortened and the etching amount of electric copper plating is reduced, so that the reduction of wiring width and wiring thickness can be suppressed. have.

Although the selective etching liquid of this invention may be added, so that each composition may become content determined at the time of use, it can also mix | blend previously. Therefore, after preparing a thick liquid, it is suitable to dilute with water so that it may become content defined by this invention. Although there is no restriction | limiting in particular in the temperature of an etching process, Temperature can be arbitrarily set according to a desired etching rate from the range of 20-50 degreeC.

As for the management of the etching liquid, the copper concentration in the liquid increases and the component decreases depending on the throughput of the copper, and at this time, the amount of each component may be calculated by analysis to supplement the deficiency. In this replenishment method, a stable treatment surface is continuous even by replenishing each component individually or by a so-called replenishment solution in which the amount of copper dissolved in advance and the insufficient component amount required by component analysis of the treatment liquid are mixed at that ratio. It is obtained by. At this time, part of the treatment liquid is discarded, so that precipitation of the copper sulfate crystal accompanying the increase in the copper concentration contained in the treatment liquid is suppressed.

The selective etching solution of the present invention can be used without particular limitation in equipment used in known etching methods. For example, the spray etching machine used for the spray method is mentioned.

As described above, the selective etching solution of the present invention is an aqueous solution capable of selectively etching away chemical copper plating which is not necessary, and suppressing roughening of transient to maintain smoothness of the wiring surface. Therefore, it is preferable that the selective etching liquid of this invention does not contain the component which shows the effect of excessive roughening, for example, silver from a viewpoint of suppressing the roughening of the wiring surface by the excessive etching aimed at roughening. .

In this way, the etching removal method of the present invention can selectively remove chemical copper plating by using the above-described selective etching solution, thereby suppressing disconnection and disconnection by suppressing reduction in wiring width and wiring thickness of the conductor circuit. The smoothness of the wiring surface can be maintained.

Example

Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited in any form by these Examples.

Example 1

The liquid which added 0-5 ppm of bromine ion concentration to the etching liquid which consists of 0.8 weight% of hydrogen peroxide, 4 weight% of sulfuric acids, 20 g / L of copper concentrations, and remaining water was adjusted. The spray etching process was performed at the spray pressure of 0.1 Mpa and liquid temperature of 30 degreeC using the chemical copper plating board | substrate (plating thickness 1 micrometer) and the electrocopper plating board (plating thickness 20 micrometers). The etching amount was calculated by the weight difference of the board | substrate before and behind a process, and the etching rate per unit time was computed. Moreover, the ratio of the etching rate of chemical copper plating with respect to the etching rate of electric copper plating was computed. The results are shown in FIG.

Example 2

It carried out similarly to Example 1 except having added 0.005 weight% of 5-amino-1H-tetrazole. The results are shown in FIG.

Comparative Example 1

The liquid which added 0-5 ppm of chlorine ion concentration to the etching liquid which consists of 0.8 weight% of hydrogen peroxide, 4 weight% of sulfuric acids, 20 g / L of copper concentrations, and remaining water was adjusted. The spray etching process was performed at the spray pressure of 0.1 Mpa and liquid temperature of 30 degreeC using the chemical copper plating board | substrate (plating thickness 1 micrometer) and the electrocopper plating board (plating thickness 20 micrometers). The etching amount was calculated by the weight difference of the board | substrate before and behind a process, and the etching rate per unit time was computed. Moreover, the ratio of the etching rate of chemical copper plating with respect to the etching rate of electric copper plating was computed. The results are shown in FIG.

Comparative Example 2

It carried out similarly to the comparative example 1 except having changed the chlorine ion into fluorine ion. The results are shown in FIG.

Comparative Example 3

It carried out similarly to the comparative example 1 except having added 0.005 weight% of 5-amino-1H- tetrazole. The results are shown in FIG.

Example 3

10 L of the surface treatment agent which consists of 1 weight% of hydrogen peroxide, 5 weight% of sulfuric acid, 1 ppm of bromine ions, 20 g / L of copper concentrations, and the remainder of water was used, and the process was performed at spray pressure 0.1 Mpa, and processing temperature of 30 degreeC using the spray etching machine.

The evaluation board | substrate used the board | substrate which formed 1 micrometer of chemical copper plating in the seed layer of the resin surface, or the board | substrate which formed the wiring of line / space = 30 micrometer / 30 micrometers by electric copper plating. Etching time was made into the time when the chemical copper plating on space was etched away. The wiring width before and after the process was measured using an optical microscope, and the wiring width reduction amount was calculated. Moreover, the surface of the wiring which is electro copper plating was observed by SEM, and the wiring surface shape was confirmed. The results are shown in Table 1.

Example 4

It carried out similarly to Example 3 except having added 3 ppm bromine ion and 0.005 weight% of 5-amino-1H- tetrazole. The results are shown in Table 1.

Comparative Example 4

10 L of the surface treatment agent consisting of 1% by weight of hydrogen peroxide, 5% by weight of sulfuric acid, copper concentration of 20 g / L, and the remaining water was used at a spray pressure of 0.1 Mpa and a treatment temperature of 30 ° C.

The evaluation board | substrate used the board | substrate which formed 1 micrometer of chemical copper plating in the seed layer of the resin surface, or the board | substrate which formed the wiring of line / space = 30 micrometer / 30 micrometers by electric copper plating. Etching time was made into the time when the chemical copper plating on space was etched away. The wiring width before and after the process was measured using an optical microscope, and the wiring width reduction amount was calculated. Moreover, the surface of the wiring which is electro copper plating was observed by SEM, and the wiring surface shape was confirmed. The results are shown in Table 1.

Comparative Example 5

It carried out similarly to the comparative example 4 except having added 0.005 weight% of 5-amino-1H- tetrazole. The results are shown in Table 1.

Comparative Example 6

It carried out similarly to the comparative example 4 except having added 1 ppm of chlorine ion concentrations. The results are shown in Table 1.

Etching Time (sec) Reduced wiring (μm) Wiring surface condition  Example 3 50 0.9 ○  Example 4 30 0.4 ◎  Comparative Example 4 45 2.7 ○  Comparative Example 5 30 2.0 △  Comparative Example 6 180 2.2 ○

In the etching removal method of the present invention, by using a selective etching solution, in the manufacture of a semiadditive method printed wiring board, the etching of the electrical copper plating, which is the wiring portion, is suppressed, and the chemical copper plating which is not necessary is selectively etched away, and the wiring width of the conductor circuit, By suppressing the reduction in the thickness of the wiring, disconnection and disconnection can be suppressed while the smoothness of the wiring surface can be maintained.

According to the present invention, in the manufacture of a semiadditive printed wiring board, by suppressing the etching of the electro-copper plating, which is the wiring part, and selectively etching away the unnecessary chemical copper plating, the reduction of the wiring width and the wiring thickness of the conductor circuit is suppressed. In addition, it is possible to keep the wiring surface smooth while suppressing the missing.

Claims (6)

In the manufacture of the semiadditive method printed wiring board, after forming the seed layer of chemical copper plating on the insulating resin layer and forming the pattern resist, the conductor circuit is formed by the electric copper plating, and then the resist is peeled off and is required by using a selective etching solution. An etching removal method for selectively etching away free chemical copper plating, wherein the selective etching solution contains 0.2 to 15 wt% hydrogen peroxide, 0.5 to 15 wt% sulfuric acid and 0.5 to 5 ppm bromine ions and has a molar ratio of hydrogen peroxide / sulfuric acid of 5 or less Etch Removal Method. The method of claim 1, Said selective etching liquid contains 0.001-0.05 weight% of azoles further, The etching removal method characterized by the above-mentioned. The method of claim 1, Said selective etching liquid contains 0.001-0.01 weight% of azoles further, The etching removal method characterized by the above-mentioned. The method according to any one of claims 1 to 3, And the etching rate ratio of the chemical copper plating to the electrocopper plating in the selective etching solution is 5 or more. The method according to any one of claims 1 to 3, The etching rate of the electro-copper plating in the selective etching solution is 0.5 ㎛ / min or less. The selective etching liquid used by the etching removal method in any one of Claims 1-5.

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