KR20060107349A - Process for producing substrate with copper wiring or bump formed thereon - Google Patents

Abstract

Semi-additive method using a substrate having a metal thin film layer formed by sputtering by using an etching solution containing 0.1 to 10% by weight of hydrogen peroxide and 0.5 to 50% by weight of phosphoric acid as the etching solution and a weight ratio of hydrogen peroxide / phosphate to 0.02 to 0.3 In forming thin wire copper wiring and bump (BUMP) in, the metal of the seed layer, in particular sputter copper or sputter nickel, is etched away quickly and the reduction in wiring width of the copper wiring is suppressed, eliminating shortcomings such as disconnection and short circuit, Provided is a method of manufacturing a highly reliable substrate without eroding the bump constituent metal.

Description

A manufacturing method of a board | substrate with copper wiring or bumps {PROCESS FOR PRODUCING SUBSTRATE WITH COPPER WIRING OR BUMP FORMED THEREON}

This invention relates to the manufacturing method of the board | substrate with which copper wiring or bump was formed by the semiadditive process.

BACKGROUND ART In recent years, in the field of wiring boards for electronic devices, thinning of copper wiring has rapidly progressed with high-density mounting, and the wiring width and wiring spacing are significantly narrowed. Further, in the field of wafer-level chip size packages, the formation of thin copper wiring by the semi-additive method and the formation of bumps [BUMP: small hump-shaped conductor protrusions provided for connecting the substrate and the package] are formed. This is mainstream.

In the semiadditive process, a metal thin film layer (hereinafter referred to as a "seed layer") is formed on a substrate by a physical method such as electroless plating or sputtering, and a resist pattern for wiring formation or bump formation by photolithography thereon. To form. Further, in the case of copper wiring formation, the copper wiring is formed by performing electrocopper plating and finally removing the resist and etching away the unnecessary seed layer. In the case of bump formation, bump metal is formed, for example, solder plating is performed, and after removing the resist at last, the unnecessary seed layer is etched away to form bumps.

The present inventors have proposed a system in which azoles are added to hydrogen peroxide-sulfuric acid as a copper etching solution of a seed layer in this semiadditive process (see Japanese Patent Laid-Open No. 2005-5341). When the seed layer is electroless copper plating, the etching solution can be etched well, but when the seed layer is copper (sputtered copper) formed by the sputtering method, etching cannot be completely removed. Since sputtered copper is physically formed densely in a particulate state on the insulating layer, it is more difficult to etch away than electroless copper plating. For this reason, overetching to completely etch away reduces the copper wiring width. Moreover, although the method of etching metal of a seed layer by forming a metal film other than copper on the copper wiring side or surface is also proposed, when a seed layer is sputter copper like the above-mentioned chemical | medical solution, etching removal cannot be performed completely ( See Japanese Patent Application Laid-open No. Hei 9-162523 and No. 2003-78234).

Although the peroxide-nitrate-sulfuric acid system has been proposed for the nickel etching solution of the seed layer in the semi-additive process, the etching removal cannot be completed when the seed layer is nickel (sputter nickel) formed by the sputtering method. -140084 publication). Therefore, in forming thin wire copper wiring in the semi-additive method, it is required to put practical use of the method of suppressing the reduction in the wiring width of the copper wiring and etching away the sputtered copper or sputter nickel of the seed layer.

The present invention is to quickly etch away and remove metal of the seed layer, in particular sputter copper or sputter nickel, in the thin-wire copper wiring formation and bump formation in the semiadditive process using a substrate having a metal thin film layer formed by sputtering. It is possible to provide a method of manufacturing a highly reliable substrate by suppressing a reduction in wiring width, eliminating shortcomings such as disconnection and short circuit, and not corroding the bump constituent metal.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to solve the said subject, as a result, the etching solution of the metal thin film layer in the semiadditive process using the board | substrate which has the metal thin film layer formed by the sputtering method contains hydrogen peroxide and phosphoric acid in a specific concentration and ratio. By using the etchant to make it possible to solve the above problems, the present invention has been completed.

That is, in the present invention, a resist pattern is formed on the metal thin film layer by using a substrate having a metal thin film layer formed by sputtering, followed by electrolytic copper plating or plating of bump metal, followed by removal of the resist. And 0.1 to 10% by weight of hydrogen peroxide and 0.5 to 50% by weight of phosphoric acid as an etching solution in the method for producing a substrate having copper wiring or bumps by a semiadditive process for removing the metal thin film layer by etching. The manufacturing method of the board | substrate with a copper wiring or bump formed using the etching liquid whose weight ratio of hydrogen peroxide / phosphoric acid is 0.02-0.3.

Best Mode for Carrying Out the Invention

The hydrogen peroxide concentration used for the etching liquid of the manufacturing method of the board | substrate of this invention is 0.1-10 weight%, Preferably it is 0.5-5 weight%. If the hydrogen peroxide concentration is less than 0.1% by weight, a sufficient etching rate cannot be obtained, and if it exceeds 10% by weight, the reduction in the wiring width of the copper wiring becomes significant.

The phosphoric acid concentration used for the etching liquid of the manufacturing method of the board | substrate of this invention is 0.5-50 weight%, Preferably it is 2.5-25 weight%. If the phosphoric acid concentration is less than 0.5% by weight, a sufficient etching rate cannot be obtained, and even if it exceeds 50% by weight, no further effect can be obtained.

Moreover, the weight ratio (hydrogen peroxide / phosphate) of hydrogen peroxide and phosphoric acid in etching liquid is 0.02-0.3. If the weight ratio of hydrogen peroxide and phosphoric acid is less than 0.02 and more than 0.3, the etching removal property of the seed layer is not sufficient, and if it exceeds 0.3, the wiring width of the copper wiring becomes particularly remarkable when forming the copper wiring, which is not preferable.

As the substrate, Ti, Si, Sn, Cr, and alloys thereof are made of metals such as Ti, TiN, TiW, Si, SiO ₂ , SiN, Sn, SnPb, SnAg, Cr, CrNi, and mainly wafer-level chip size packages. The flexible board | substrate etc. which are based on the board | substrate and polyimide used for this etc. are mentioned.

In the present invention, the metal for forming the seed layer to be etched is a metal such as copper or nickel formed by the sputtering method.

In this invention, the contact method of an etching liquid and an object does not have a restriction | limiting in particular, It can carry out by an immersion process, a spray process, etc. As for etching process temperature, 20-60 degreeC is preferable. If the treatment temperature exceeds 60 ° C., decomposition of hydrogen peroxide is promoted, which is not preferable. As for the etching treatment time, an optimum time is selected in accordance with the surface state and shape of the object, but practically, 30 seconds to 120 seconds are preferable. If the etching solution is left attached to the object after the etching treatment, the copper surface is oxidized and discolored and stained. Therefore, it is preferable to perform the water washing promptly after the etching treatment.

In the management of the etching solution used in the present invention, the concentration of each component decreases with dissolution of the metal, so that each component concentration is calculated by analysis to compensate for the shortage. In addition, since the etching rate decreases as the amount of dissolved metal increases, it is preferable to update the liquid at a stage where the amount of dissolved metal exceeds 15 g / L.

Example

Although an Example and a comparative example demonstrate this invention concretely below, this invention is not limited to a following example.

Example 1

The etching liquid containing 1 weight% hydrogen peroxide and 10 weight% phosphoric acid (hydrogen peroxide / phosphate weight ratio = 0.10) was combined. Next, a 0.5 micrometer-thick sputtered copper film is formed on a silicon wafer substrate, a resist pattern is formed by photolithography, electro-copper plating of 6 micrometers thick, and finally, a resist is peeled off and copper wiring The test board | substrate whose width / wiring space is 15 micrometers / 10 micrometers was created.

The said board | substrate was immersed in 30 degreeC etching liquid, and time until the sputter | spatter copper of the seed layer which is a wiring space part was completely etched away was measured. In addition, the copper wiring width before and after the etching process was measured using the optical microscope, and the wiring width reduction amount was calculated. The results are shown in Table 1.

Example 2

Except having used the etching liquid containing 0.5 weight% hydrogen peroxide and 8 weight% phosphoric acid (hydrogen peroxide / phosphate weight ratio = 0.06) as an etching liquid in Example 1, it carried out similarly to Example 1, and removed and calculated the amount of removal time and wiring width reduction. The results are shown in Table 1.

Comparative Example 1

In Example 1, it carried out similarly to Example 1 except using the etching liquid containing 1 weight% of hydrogen peroxide, 4 weight% of sulfuric acid, and 0.01 weight% of 1H- tetrazole, and the removal time and the wiring width reduction amount were measured and calculated. The results are shown in Table 1.

Comparative Example 2

Except having used the etching liquid containing 3 weight% of hydrogen peroxide and 3 weight% of phosphoric acid (hydrogen peroxide / phosphate weight ratio = 1.00) as an etching liquid in Example 1, it carried out similarly to Example 1, and measured the removal time and the wiring width reduction amount. The results are shown in Table 1.

Example 3

The etching liquid containing 1.5 weight% hydrogen peroxide and 15 weight% phosphoric acid (hydrogen peroxide / phosphate weight ratio = 0.10) was combined. Next, a 0.3 micrometer-thick sputtered nickel film was formed on a polyimide substrate, a pattern resist was formed by photolithography, electroplating copper plating of 6 micrometers thick, and finally, the resist was peeled off and copper doubled. A test substrate having a line width / wiring space of 15 μm / 10 μm was created.

The said board | substrate was spray-processed by 30 degreeC etching liquid (spray pressure 0.03 Mpa), and time until the sputter nickel of the seed layer which is a wiring space part was completely etched away was measured. In addition, the copper wiring width before and behind an etching process was measured using the optical microscope, and the wiring width reduction amount was computed. The results are shown in Table 1.

Comparative Example 3

Except for using the etching solution containing 0.3% by weight of hydrogen peroxide, 30% by weight of nitric acid, 6% by weight of sulfuric acid, 0.01% by weight of sodium chloride, 1% by weight of 2-chloro-pyridine as an etching solution in Example 3, removal was performed. The amount of time and wiring width reduction were measured and calculated. The results are shown in Table 1.

Comparative Example 4

In Example 1, it carried out similarly to Example 3 except having used the etching liquid containing 1.5 weight% of hydrogen peroxide, 15 weight% of phosphoric acid, and 2 ppm of chlorine ion as an etching liquid, and the removal time and the wiring width reduction amount were measured and calculated. The results are shown in Table 1.

Removal time (seconds) Reduced wiring width (㎛) Example 1 40 <1 Example 2 50 <1 Example 3 45 <1 Comparative Example 1 300 5 Comparative Example 2 180 8 Comparative Example 3 600 8 Comparative Example 4 600 8

As shown in Table 1, in the thin-wire copper wiring formation by the semiadditive process by the etching method of this invention, reduction of the wiring width of a copper wiring can be suppressed and the sputter | spatter copper or sputter nickel of a seed layer can be etched away.

Example 4

The etching liquid containing 1 weight% hydrogen peroxide and 12 weight% phosphoric acid (hydrogen peroxide / phosphate weight ratio = 0.08) was combined.

Each board | substrate was processed for 60 second by the shaking process at 30 degreeC using the board | substrate to which sputtered copper was applied, and the board | substrate which electroplated with copper, and the etching rate in each copper was computed. As for the calculation of the etching rate, sputter | spatter copper measured the film thickness before and behind a process using the fluorescent X-ray, and electrocopper plating measured the weight difference before and behind a process, and computed the etching amount of each copper.

Example 5

It carried out similarly to Example 4 except having used the etching liquid containing 1 weight% of hydrogen peroxide and 4 weight% of phosphoric acid (hydrogen peroxide / phosphate weight ratio 0.25), and the etching amount was computed.

Comparative Example 5

The etching liquid containing 1 weight% hydrogen peroxide and 2 weight% phosphoric acid (hydrogen peroxide / phosphate weight ratio = 0.5) was combined. Each board | substrate was processed for 60 second by the shaking process at 30 degreeC using the board | substrate to which sputtered copper was applied, and the board | substrate which electroplated with copper, and the etching rate in each copper was computed. As for the calculation of the etching rate, sputter | spatter copper measured the film thickness before and behind a process using the fluorescent X-ray, and electrocopper plating measured the weight difference before and behind a process, and computed the etching amount of each copper.

Comparative Example 6

The etching amount was calculated in the same manner as in Comparative Example 5 except that an etching solution containing 5% by weight of hydrogen peroxide and 1% by weight of phosphoric acid (hydrogen peroxide / phosphate weight ratio 5.0) was used.

Comparative Example 7

The etching amount was computed similarly to the comparative example 5 except having used the etching liquid which adjusted the etching liquid CPE-700 by Mitsubishi Gas Chemical Co., Ltd. which mainly contains hydrogen peroxide and sulfuric acid to 1 weight% of hydrogen peroxide.

The results are shown in Table 2.

Etch Rate Sputtered Copper (μm / min) Etching Rate Electroplated Copper (μm / min) Etching Rate Ratio Sputter Copper / Electroplating Copper Example 4 0.70 0.60 1.17 Example 5 0.60 0.58 1.03 Comparative Example 5 0.54 0.71 0.76 Comparative Example 6 0.33 0.70 0.47 Comparative Example 7 0.50 1.40 0.36

Example 6

The etching liquid containing 0.9 weight% hydrogen peroxide and 10 weight% phosphoric acid (hydrogen peroxide / phosphate weight ratio = 0.09) was combined. The test piece which performed SnAg solder plating was immersed at 30 degreeC, and the process was performed for 10 minutes. The weight before and after the treatment was measured, and the etching rate was calculated. Moreover, the surface state was observed.

Comparative Example 8

The etching liquid containing 1 weight% hydrogen peroxide and 5 weight% sulfuric acid was combined.

The test piece which performed SnAg solder plating was immersed at 30 degreeC, and the process was performed for 10 minutes. The weight before and after the treatment was measured, and the etching rate was calculated. Moreover, the surface state was observed.

The results are shown in Table 3.

Metal type Etch Rate Å / min Surface observation Example 6 SnAg <10 No change Comparative Example 8 SnAg 560 Blurring

According to the etching method of the present invention, the metal of the seed layer, particularly sputter copper or sputter nickel, can be quickly suppressed in the semi-additive process by suppressing the reduction in the wiring width of the copper wiring when forming the thin copper wiring and eroding the bump constituent metal. It becomes possible to remove an etching and is useful for manufacture of electronic components, such as a semiconductor product and a printed wiring board.

Claims (3)

After forming a resist pattern on the metal thin film layer using a substrate having a metal thin film layer formed by sputtering, electrolytic copper plating or metal plating for bumps is performed, and then the metal is removed by etching and etching. In the method of manufacturing a substrate having a copper wiring or bump formed by the semi-additive method of removing the thin film layer, the etching solution contains 0.1 to 10% by weight of hydrogen peroxide and 0.5 to 50% by weight of phosphoric acid while the weight ratio of hydrogen peroxide / phosphoric acid The manufacturing method of the board | substrate with a copper wiring or bump which uses the etching liquid whose is 0.02-0.3. The method of claim 1, The metal thin film layer formed by the sputtering method is copper, The manufacturing method of the board | substrate characterized by the above-mentioned. The method of claim 1, The metal thin film layer formed by sputtering method is nickel, The manufacturing method of the board | substrate characterized by the above-mentioned.