JPH0582524A - Manufacture of electrode and its connecting method - Google Patents

Abstract

PURPOSE:To obtain an electrode manufacturing method in which the short-circuit between electrodes can be suppressed by a method wherein, when the protruding type electrodes to be used in fine mounting of semiconductor elements, manufactured by an electroless plating method, the region other than the part where an electrode will be formed is covered by photosensitive resin, and a dry plating pretreatment is conducted. CONSTITUTION:After a semiconductor substrate 1, on which a circuit is formed, has been coated with a photosensitive resin layer, a laminated on the electrode of an aluminum layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a projection-shaped electrode used for fine mounting of semiconductor elements and a method of connecting the electrodes.

[0002]

2. Description of the Related Art As a method for connecting an element using a semiconductor or an insulator to an external circuit, there is a thin film mounting method typified by TAB (tape automated bonding) and a wire bonding method widely used in packages. Among them, TAB is expanding its field of application because it can be mounted in a small size and light weight.

The protruding electrodes (bumps) required for the TAB on the semiconductor element side have been conventionally manufactured by using dry plating methods such as vapor deposition and sputtering, wet plating methods and photolithography methods. Therefore, the manufacturing process becomes long, and there are problems in cost and manufacturing yield. Therefore, in order to solve these problems, a method of manufacturing a protruding electrode using an electroless plating method has been devised, and is disclosed in Japanese Patent Laid-Open No. 63-30553
A method of laminating a nickel alloy plating film using palladium as an activated metal as in 2 has been devised. Further, this bump had a mushroom shape because the plating grew isotropically.

[0004]

However, the conventional technique has the following problems.

First, as the number of IC terminals increases, the area of the electrodes and the distance between the electrodes decrease. As a result, in the conventional mushroom-shaped protruding electrode, the height is about 1/2 of the electrode interval.
If it becomes higher than this, a short circuit will occur and the connection function cannot be obtained. Furthermore, there is a problem that the connection strength is low because the area that can contact aluminum is small.

The present invention solves these problems, and an object thereof is to apply a photosensitive resin to a height close to a projected height,
It is intended to provide a method for manufacturing an electrode, in which selectivity of plating is enhanced, electrodes are not short-circuited even if the pitch is narrowed, and connection strength is not lowered.

[0007]

SUMMARY OF THE INVENTION A method of manufacturing an electrode according to the present invention is a projecting electrode in which a conductive layer of aluminum is laminated on a semiconductor substrate and a connection metal layer for electrically connecting is laminated on the conductive layer. In the manufacturing method of the connection metal layer,
A step of coating a photosensitive resin on a semiconductor substrate containing aluminum, b, a step of removing the photosensitive resin at a predetermined electrode portion, a step of irradiating light having a wavelength of 200 nm or less, or a step of irradiating an oxidizing gas plasma And d, a step of irradiating non-oxidizing gas plasma and e, a step of adsorbing palladium on aluminum and a step of f, a step of precipitating a metal by immersing in electroless plating and a step of removing a photosensitive resin, and laminating. It is characterized by doing.

The electroless plating solution is a plating solution of nickel, nickel-phosphorus, nickel-boron, gold, palladium-phosphorus or nickel-phosphorus or nickel-boron, and tungsten, molybdenum, manganese, copper, palladium, silver, A plating solution containing at least one metal ion selected from the group consisting of cobalt, chromium, iron, rhenium, tin, lead, indium, zinc, thallium, and bismuth.

The electrode connecting method of the present invention is characterized in that the electrode manufactured by the above electrode manufacturing method is used to connect to a circuit board.

The photosensitive resin of the present invention may be either a positive type or a negative type, and its coating method may be a spin coating method, a coater method, a laminating method or a constant speed pulling method. Further, it is desirable that the photosensitive resin has one layer, and two or more layers of the photosensitive resin may be applied through an adhesion improver to increase the thickness to the projected electrode height.

Irradiation with ultraviolet rays is carried out for the purpose of removing the photosensitive resin which cannot be completely removed after exposure and development. The wavelength is preferably 200 nm or less. Light having a wavelength of 200 nm or less makes oxygen in the air ozone. Since ozone is an oxidizing agent, the resin can be removed. The removal of the photosensitive resin can also be realized by irradiating an oxidizing gas such as oxygen plasma.

Also, non-oxidizing gases such as argon, nitrogen,
The plasma irradiation of argon or nitrogen containing hydrogen or hydrogen is performed for the purpose of cleaning the aluminum surface oxidized by the action of ozone.

The electroless plating is carried out for the purpose of forming the shape of the protruding electrodes. It is desirable to use a plating solution containing one or more metal ions of manganese, copper, palladium, silver, cobalt, chromium, iron, rhenium, tin, lead, indium, zinc, thallium, and bismuth. Further, the pH of the plating solution is preferably from weak alkaline to acidic side because the plating is performed while leaving the photosensitive resin.

In order to realize the TAB connection, gold plating or solder plating is required on the outermost surface of the protruding electrode. The gold plating can be formed by an electroless plating method using a substitution type solution and a reduction thickening type solution. The solder plating includes an electroless plating method and a method of removing the photosensitive resin and then immersing it in a molten solder bath.

[0015]

According to the method of the present invention for plating the surface of the photosensitive resin while leaving the photosensitive resin, isotropic plating growth can be prevented, so that the electrodes are not short-circuited even if the electrode interval is narrow. Further, since it is not necessary to reduce the electrode area in consideration of isotropic plating growth, the strength does not decrease even when the electrode interval is narrowed, as compared with the method using no photosensitive resin.

[0016]

EXAMPLES The effects of the present invention will be described below based on examples.

(Embodiment 1) FIGS. 1A to 1C are cross-sectional views for each manufacturing process of the electrode of this embodiment.

As shown in FIG. 1A, an aluminum layer 3 having a thickness of about 1 micron is formed on a silicon substrate 1 having an oxide film 2 formed thereon by a sputtering method or a vapor deposition method. Then, an insulating layer 4 of silicon oxide, polyimide or silicon nitride containing phosphorus or boron of about 1 micron is formed by spin coating or CVD method, and a plurality of 80 micron intervals,
A 60-micron-square electrode planned part is processed by the photo fistography method and the etching method.

Next, as shown in FIG. 1 (b), a negative type photosensitive resin 5 is applied to the aluminum layer 3 and the insulating layer 4 with a thickness of about 30 μm, and the solvent is dried to remove the photosensitive resin in the electrode planned portion. Exposure and development.

Subsequently, as shown in FIG. 1 (c), the photosensitive resin remaining on the aluminum layer at the electrode planned portion is removed by ultraviolet irradiation of a wavelength of 185 nm or oxygen plasma irradiation of 0.2 Torr, 100 W, and further argon or nitrogen. Or 0.2 Torr with other non-oxidizing gas,
Plasma irradiation of 100 W is continuously performed, and aluminum is activated by electroless plating by immersing it in an aqueous solution containing 20 ppm of palladium chloride as a main component. -The phosphorus layer 6 is formed.

<Plating Composition> Nickel Sulfate Hexahydrate 30 g / l Sodium Hypophosphite Dihydrate 10 g / l Trisodium Citrate Dihydrate 10 g / l Ammonium Sulfate 66 g / l Thiodiglycolic Acid 10 ppm <Plating conditions> pH 5.5 Temperature 70 degrees (Celsius) Finally, the gold layer 7 was plated with a commercially available displacement plating solution for TAB connection, and the photosensitive resin was removed with a stripping solution to produce an electrode.

(Embodiment 2) FIGS. 2A to 2D are cross-sectional views of the electrodes of this embodiment in different manufacturing steps.

A silicon substrate 21 having an oxide film 22 formed thereon as shown in FIG.
An aluminum layer 23 having a micron thickness is formed. And about 1 micron phosphorus- or boron-containing silicon oxide,
An insulating layer 24 of polyimide or silicon nitride is formed by spin coating or a CVD method, and a plurality of electrode planned portions having a pitch of 80 μm and a size of 60 μm are processed by a photophysography method and an etching method.

Next, as shown in FIG. 2B, a negative type photosensitive resin 25 is applied to the aluminum layer 2 having an active surface of about 30 microns.
3 and the insulating layer 24 are applied, dried by a solvent, and exposed and developed so that the photosensitive resin in the electrode planned portion can be removed.

Then, as shown in FIG. 2 (c), the photosensitive resin remaining on the aluminum layer at the electrode planned portion is removed by ultraviolet irradiation of 185 nm wavelength or 0.2 Torr, 100 W, oxygen plasma irradiation, and 20 ppm of palladium chloride. Aluminum is activated by electroless plating by immersing it in an aqueous solution containing
The nickel plating layer 26 having a height of about 20 μm is formed by using a phosphorus plating solution.

<Plating Composition> Nickel Sulfate Hexahydrate 30 g / l Sodium Hypophosphite Dihydrate 10 g / l Trisodium Citrate Dihydrate 10 g / l Ammonium Sulfate 66 g / l Thiodiglycolic Acid 10 ppm <Plating conditions> pH 5.5 Temperature 70 degrees (Celsius) Next, as shown in FIG. 3D, the gold layer 27 was plated with a commercially available displacement plating solution, and after removing the photosensitive resin with a stripping solution,
Electrodes were produced by plating the gold layer 28 with an electroless thick gold plating solution for about 1 to 10 microns.

Comparative Example 1 An electrode was manufactured in the same manner as in Example 1 except that the coating and exposure of the photosensitive resin of Example 1 were omitted. FIG. 3 is a cross-sectional view of the electrode of this comparative example.

Comparative Example 2 An electrode was manufactured in the same manner as in Example 1 except that the 185 nm ultraviolet irradiation or oxygen RF plasma irradiation process of Example 1 was omitted.

Comparative Example 3 An electrode was manufactured in the same manner as in Example 1, except that the plasma irradiation using argon or nitrogen or other non-oxidizing gas in Example 1 was omitted.

The metallized state of the electrodes of Examples 1 to 2 and Comparative Examples 1 to 3 was examined with a microscope, and the electrode height was examined with a step gauge. As a result, as shown in Table 1, in Examples 1 to 2, plating could be selectively formed on aluminum, but in Comparative Example 1, the electrodes were short-circuited because the electrode shape was mushroom. Furthermore, Comparative Examples 2 and 3 had an electrode portion where plating was not formed.

[0031]

[Table 1]

In Comparative Example 1, the silicon exposed on the surface was also plated. As a result, useless metal consumption increases,
The life of the plating solution has become shorter.

Next, the electrodes of Examples 1 to 2 and Comparative Examples 2 to 3 were TAB-connected to the tin-plated tape by a conventional method. As a result of comparison, the minimum connection strength was less than 20 g / electrode as poor and 20 g / electrode or more as good. As a result, as shown in Table 2, the electrodes of Examples showed a better connection state than the Comparative Examples.

[0034]

[Table 2]

Also, a good connection state was obtained by a wire bonding method or a method of flip-chip connecting semiconductor elements, and long-term reliability was also good.

The effects of the present invention were not changed except for the processing conditions, bump heights, electrode compositions and semiconductor substrate materials shown in this embodiment.

In the electroless plating solution, if the pH is more acidic than that of weak alkali, nickel-phosphorus, nickel-boron, nickel-phosphorus, palladium-phosphorus or nickel-boron plating solutions may be added to tungsten or molybdenum. , Manganese, copper, palladium, silver, cobalt, chromium, iron,
The plating solution containing one or more metal ions of rhenium, tin, lead, indium, zinc, thallium, and bismuth did not change the effect.

The effect of the nickel plating solution was not changed even when a known electroless plating solution composition or other commercially available plating solution was used in addition to the present invention.

Even if the ultraviolet wavelength was 200 nm or less and the pressure of the plasma treatment was changed, the effect was not changed.

The effect of the photosensitive resin was the same as that of the positive type.

Further onto the nickel alloy or gold plating,
Even if the solder was laminated by the electroless plating method or the immersion method in the molten solder bath, the effect was not changed.

[0042]

As described above, according to the present invention, as a method of manufacturing electrodes, by coating a portion other than the planned electrode portion with a photosensitive resin before plating, the selective plating property on aluminum is improved and the electrode spacing is improved. Even a narrowed TAB, flip chip, or wire bonding method has an effect of stable connection. Further, since surface stains on aluminum are removed by irradiation with ultraviolet rays and plasma, there is an effect that variations in height of plated bumps can be suppressed. Since the surface of the semiconductor element is not immersed in the plating solution, there is an effect of preventing the quality deterioration.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an electrode according to a first embodiment of the present invention for each manufacturing process.

2A to 2C are cross-sectional views of the electrode according to the second embodiment of the present invention for each manufacturing process.

FIG. 3 is a sectional view of an electrode of Comparative Example 1 of the present invention.

[Explanation of symbols]

 1 Silicon Substrate 2 Oxide Film 3 Aluminum Layer 4 Insulating Film 5 Photosensitive Resin Layer 6 Nickel Phosphorus Layer 7 Gold Layer 21 Silicon Substrate 22 Oxide Film 23 Aluminum Layer 24 Insulating Film 25 Photosensitive Resin Layer 26 Nickel Phosphorus Layer 27 Gold Layer 28 Gold Layer 41 Silicon Substrate 42 Oxide Film 43 Aluminum Layer 44 Insulating Film 45 Nickel Phosphorus Layer 46 Gold Layer

Claims (3)

[Claims] 1. A method for manufacturing a bump electrode, comprising: a conductive layer of aluminum laminated on a semiconductor substrate; and a connection metal layer capable of electrical connection on the conductive layer. A step of coating a photosensitive resin on a semiconductor substrate including b, a step of removing the photosensitive resin in a portion to be an electrode, and a step of irradiating light having a wavelength of 200 nm or less or a step of irradiating an oxidizing gas plasma. d, a step of irradiating non-oxidizing gas plasma and e, a step of adsorbing palladium on aluminum, f, a step of precipitating a metal by immersing in an electroless plating solution and a step of removing g of a photosensitive resin, and laminating A method for manufacturing an electrode, comprising: 2. The electroless plating solution according to claim 1, wherein the plating solution of nickel, nickel-phosphorus, nickel-boron, gold, palladium-phosphorus or nickel-phosphorus or nickel-boron is added to tungsten, molybdenum, manganese,
A method for producing an electrode, which is a plating solution containing any one or more metal ions of copper, palladium, silver, cobalt, chromium, iron, rhenium, tin, lead, indium, zinc, thallium, and bismuth. .. 3. A method for connecting electrodes, which comprises connecting the electrodes manufactured by the method according to claim 1 to a circuit board.