JPH02251145A - Formation of bump electrode - Google Patents

Abstract

PURPOSE:To form bump electrodes of high density which only requires a simple technique and a low manufacturing cost by supplying solder collectively to a wide region including a plurality of terminal electrode parts that are formed at openings of a protective film and are quite densely in existence or to the whole surface of a substrate. CONSTITUTION:A protective film 16 is formed at the whole surface of terminal electrode parts 15 that are input/output terminals of a semiconductor integrated circuit and protective film opening 18 are formed on the protective film 16 by photoetching and then, the terminal electrode parts 15 are exposed. Then bump electrode materials are formed on the protective film 16 including the terminal electrode parts 15 and the bump electrode materials 19 are dissolved by treating with heat and then, bump electrodes 20 are formed at the terminal electrode parts 15. The bump electrodes are thus manufactured efficiently with a simple technique and a process is performed at a low cost. Moreover, as the bump electrodes of high density are formed, elements which are disposed with a number of terminals and the terminal electrode parts of high density are packaged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming a protruding electrode for bonding used when connecting an electronic element and a circuit board.

[Conventional technology]

A conventional method of forming solder bump electrodes is typified by a plating method using photoetching. Fourth
Figures (a), (b), (C), (d), and (e) are /I
FIG. 7 is a cross-sectional view showing the steps and bonding state of a protruding electrode forming method using the '7-ki method.

First, as shown in FIG. 4(a), a terminal electrode portion 42 is formed on a substrate 41 made of silicon, for example, by forming a film by vapor deposition, sputtering, etc., and then patterning by photoetching. This terminal electrode portion 42 is electrically connected to a semiconductor functional portion (not shown) on the substrate 41, and is generally made of an aluminum-based material. Next, as a protective film 46 on the surface of the substrate 410, an insulating material is used to cover the entire surface of the substrate 41, and then a protective film 4 in a shape that exposes the central part of the terminal electrode section 42 is formed by photo-etching.
form 6.

Next, as shown in FIG. 4(b), a common electrode layer 44 for plating is sequentially deposited and laminated on the entire surface of the substrate 41 using metal materials such as chromium, copper, and gold by vapor deposition.

These metal materials have the role of improving the wettability and adhesion between the terminal electrode part 42 and the solder layer formed in a subsequent process, and acting as a diffusion prevention film between the two materials, and generally have a laminated structure of several types of metal materials. It has become. Furthermore, a resist film 45 is formed on the plating common electrode layer 44 by photoetching in a shape that opens the portions where the individual projecting electrodes are to be formed.

Next, as shown in FIG. 4(C), the plating solder 46 is
It is formed on each open terminal electrode portion 42 of the resist film 45 while supplying current to the plating common electrode layer 44 by an electrolytic plating method. After that, flux 47 is applied to the entire surface of the substrate 41.

Next, as shown in FIG. 4(d), the above-mentioned plating solder 46 is melted together with flux 47 by heating as the solder projection electrode 48, and the surface tension of the molten solder is utilized to
A spherical electrode is formed on the terminal electrode portion 42, which is bonded via the common electrode layer 44 for plating. This is the so-called rounding process. Thereafter, excess flux is removed by washing, and the resist film 45 is peeled off. Furthermore, the gold, copper, and chromium of the plating common electrode layer 44 are sequentially removed by etching.
At this time, a part of the plating common electrode layer 44 on the terminal electrode portion 42 remains without being etched away.

The solder protrusion electrode 48 is completed through the above steps.

As shown in FIG. 4(e), the solder protruding electrodes 48 are positioned on the substrate electrode portion 50 of the substrate 49 to be bonded to each other, such as a printed circuit board. The solder protruding electrodes 48 are melted by heating, and the two substrates are bonded together as a joining solder 51.

[Problem to be solved by the invention]

In the conventional plating method using the photoresist described above, the process from forming the metal layer as the plating common electrode layer 44 to etching removal is long (man-hours are required and production costs are high; In order to obtain the height of the electrode 48, it is necessary to increase the thickness of the plating solder 46, which increases the plating time, which is not good in production efficiency.Moreover, in this case, as shown in FIG. 4(C), In the plating method, the plating solder 46 is formed isotropically, so the board 4
The plating progresses in a direction horizontal to 1. Normally, the ratio of the height and diameter of the solder plate 46 is approximately 1=3. Therefore, in order for the spherical solder protrusion electrode 48 formed by the rounding process to have a sufficient height, the ratio between the height and the diameter of the plated solder 46 must be It is necessary to set a sufficient gap between the terminal electrode parts 420 to avoid contact. Therefore, the high-density solder protrusion electrode 48
There are problems such as there is a limit to the formation of semiconductor devices, and it is difficult to respond to multi-terminal and high-density semiconductor devices.

An object of the present invention is to provide a method for forming a multi-terminal, high-density protruding electrode using a simple method and at low cost, paying attention to the above-mentioned problems.

[Means to solve the problem]

In order to achieve the above object, the protruding electrode according to the present invention is manufactured by the steps described below.

The process of forming a protective film over the entire surface of the terminal electrode part, which is the input/output terminal of a semiconductor integrated circuit, and forming a protective film opening in the protective film by photoetching to expose the terminal electrode part, and the process of protecting the terminal electrode part. The method includes a step of forming a protruding electrode material on the film, and a step of melting the protruding electrode material by performing heat treatment to form a protruding electrode on the terminal electrode portion.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1(a), (b), (C), (d), and (e) are cross-sectional views showing a final process for explaining an embodiment of the present invention. Further, FIGS. 2(a), 2(b), and 2(C) are perspective views shown for easy understanding (explanation) of the same process.

First, as shown in FIG. 1(a), a conductive layer 12 and a base layer 16 are sequentially formed on a substrate 11 made of silicon, for example. Specifically, first, the conductive layer 12 has a low resistivity (
Aluminum or its alloy, which has good adhesion to the substrate 11, is formed into a film with a thickness of about 1 μm over the entire surface of the substrate 11 by a method such as vapor deposition or sputtering. Here, aluminum-based materials lack wettability with solder (so
As the base layer 16, a conductive material having good wettability with solder, such as copper or nickel, is formed on the entire surface of the conductive layer 12 to a thickness of about 200 nm by vapor deposition, sputtering, or the like. Thereafter, a resist film 14 is formed on the base layer 16, and the base layer 16 and the conductive layer 12 are sequentially patterned by etching to form the terminal electrode portion 15 and the electrode base portion 17, as shown in FIG. 1(b). Form. Terminal electrode part 15
is electrically connected to a semiconductor functional section on the substrate 11, which is not shown in the figure. Next, the substrate 1 is used as a protective film 16.
A film of insulating material such as phosphosilicate glass or polyimide is formed on the entire surface of the substrate 1 to a thickness of about 3 μm using CVD, sputtering, or spin-coding. Furthermore, the terminal electrode part 1
In step 5, the protective film 16 is patterned by photo-etching to expose the portion of the electrode base 17 on the electrode base 17 where the solder protrusion electrode is to be formed, and the protective film opening 18 is formed.
A protective film 16 is formed. FIG. 2(a) shows the steps up to this point, for example, as a perspective view of one electronic element pellet on the wafer-shaped substrate 11.
The electrode base portion 17 is exposed in the protective film opening 18 .

Thereafter, as shown in FIG. 1(c) K, a solder paste is applied to the protective film 16 including the protective film openings 18 by a printing method, a transfer method, a dispensing method, etc. as a solder layer 19.
feed on top. This supply form is easy to understand (a perspective view is shown in FIG. 2(b), where a plurality of protective film openings 18 are present at high density, that is, an area where terminal electrode portions 15 are continuously formed. , a plurality of protective film openings 18
Solder is supplied over a wide area to the region including the solder, and one electronic element pellet has one or more solder supply regions. The figure shows an example in which two solder layer 19 regions exist.

Next, as shown in FIG. 1(d), the solder layer 19 described above is heated and melted at a temperature of 200°C to 300°C to form the protruding electrode 20, and the surface tension of the molten solder is used to form the protective film opening. In step 18, a spherical solder is formed which is bonded to the terminal electrode part 15 via the electrode base part 17, and a rounding process is performed in which it is left to cool and harden while remaining in the spherical shape. FIG. 2(C) is a perspective view showing the completed state of the protruding electrode 20.

At this time, the solder paste that was widely supplied to the plurality of terminal electrode parts 15 is melted into the protective film 1.
6 does not get wet and aggregates only on the electrode base portion 17 on the exposed terminal electrode portion 15 by capillary phenomenon, so that the protruding electrode 2
It is possible to form a zero.

In addition, in this case, the composition of the solder and the viscosity, adhesion, and dripping properties of the solder are influenced by the flux contained in the solder paste.
One containing t% to 15wt% of flux is suitable. Furthermore, the height of the protruding electrode 20 made of solder is generally 50 μm at a terminal electrode pinch of 200 μm to 300 μm.
μm to 100 μm is suitable, but according to the present invention,
In accordance with the pitch of the protruding electrodes, the height of the protruding electrodes can be adjusted by adjusting the solder supply thickness and supply area.

It is conceivable that a short circuit between adjacent protruding electrodes 20 and 5 may occur due to a short circuit phenomenon of molten solder during the rounding process.
Generally, the causes of this are: (1) design problems with the terminal electrode position, (2) manufacturing conditions, and (3) contaminated solder. By taking these factors into consideration, it is possible to prevent short circuits.

As a means of preventing short-circuiting by controlling the height of the solder layer 19, a method of forming a thick protective film 16 or a method of applying a solder resist between the terminal electrode portions 15 may be considered.

As shown in FIG. 1 (el), the substrate 11 on which the solder protruding electrodes 20 are formed is placed on a substrate electrode portion 22 formed on a substrate 21 that is bonded opposite to the substrate 11, such as a printed circuit board 5, for example. After alignment, the two difference plates are bonded using a joining solder 26 formed by melting the protruding electrodes 20 by heating.

FIGS. 3(b) and 3(c) are perspective views showing the formation of protruding electrodes using one electronic device pellet according to another embodiment of the present invention.

Here, the same parts as in the embodiment described above are given the same reference numerals, and detailed explanation thereof will be omitted.

The feature of this embodiment is as shown in FIG.
) The formation of the base layer 16 that is wettable with solder is performed by immediately forming the protective film 16 with an opening in the region where the protruding electrode is to be formed after forming the terminal electrode portion 15, and then as shown in FIG. 3(a). 5. In addition to the electrode base portion 17 on the terminal electrode portion 15, the base layer 61 on the protective film is left as a pattern on the protective film 16.

Thereafter, solder paste is supplied to the entire surface of the substrate 11 by a printing method, a transfer method, a dispensing method, etc. to form a solder layer 62 on the entire surface, and the solder is rounded by heating and melting. At this time, solder bumps that are also formed on the protective film 16 and are not electrically connected to the element functional parts are referred to as extra bumps 66. This extra bump 6
6 can be used as a bump that has the role of promoting mechanical stability during device pellet mounting. Furthermore, when the element pellet is a semiconductor memory, there are effective ways of using it, such as using it as a barrier metal that has the effect of shielding alpha rays that can cause malfunctions.

The shape of the extra bump 66 can be formed into any shape depending on the pattern shape of the base layer 61 on the protective film formed on the protective film 16.
5 layout, the shape of the substrate electrode portion 22 on the side to which the element platen is bonded as shown in FIG. We apologize for the inconvenience that the shape should be designed taking into account the stress generated by the sealing material that fills the gap between the two differential plates.

Although the configurations of the embodiments according to the present invention have been described above, the present invention is not limited to these configurations.
For example, the terminal electrode portion 15 is made of a material that has wettability with solder;
For example, if it is made of a conductive material such as copper or nickel, it is not necessarily necessary to form the base layer 16, and the process can be simplified.

In addition, in FIG. 3, the base layer 6 on the protective film 16 is
Of course, it is also possible to have a configuration in which no extra bump 66 is formed at all. In this case, the difference from the series of steps shown in FIG. 1 is whether the base layer 16 is formed before or after the formation of the protective film 16. At this time, as shown in Figure 1(a),
Since it is possible to pattern the base layer 16 and the conductive layer 12 using the same resist in the photoetching process, the former requires fewer steps than the latter (and is advantageous in terms of production cost).

Furthermore, the composition of the base layer 16 or the base layer 61 on the protective film is aluminum/chromium/copper, titanium/copper/ It may be multiple conductive materials such as nickel, chromium/copper/nickel, or chromium/copper/gold.

Further, the material of the protruding electrode 20 is not limited to solder paste.
For example, metal solder may be used by vapor deposition or the like, and after supplying flux, it is also possible to apply flux to the entire surface of the substrate using a spin cord and then perform rounding.

Further, the protruding electrode 20 is not formed on the terminal electrode section 15, but on the substrate electrode 22 on the side of the substrate 21 to be bonded facing the terminal electrode section 15 in FIG. It does not matter if it is formed on both terminal electrode parts.

〔Effect of the invention〕

As described in detail above, in the method of forming solder protruding electrodes according to the present invention, solder is supplied to a wide area including a plurality of terminal electrode parts present at a high density, or to the entire surface of the board, thereby forming protruding solder electrodes. Electrodes can be manufactured efficiently using a simple method, and the cost of the process can be reduced.
Moreover, since it becomes possible to form extremely high-density protruding electrodes, it becomes possible to provide element mounting with multiple terminals and a high-density terminal electrode arrangement.

[Brief explanation of drawings]

FIGS. 1(a), (b), (C), (d) and (e) are all sectional views showing the steps of the first embodiment of the present invention, and FIGS. 2(a), (b) and (C) are both perspective views for explaining the first embodiment of the present invention, and FIG.
) and (b) are also sectional views showing the steps of the conventional example. 11...Substrate, 2...Conductive layer, 6...Underlayer, 4...Resist film, 5...Terminal electrode part, 6... Protective film, 7... Electrode base portion, 8... Protective film opening, 9... Solder layer, 0... Protruding electrodes, 1... Substrates to be joined to each other, 2...
Substrate electrode portion, 6... Bonding solder, 1... Base layer on protective film, 2... Whole surface solder layer, 6... Extra pants.

Claims (1)

[Claims] forming a protective film over the entire surface of the terminal electrode portion, which is an input/output terminal of a semiconductor integrated circuit; and forming a protective film opening in the protective film by photoetching to expose the terminal electrode portion; and a step of exposing the terminal electrode portion. forming a protruding electrode material on the protective film containing the protruding electrode; and melting the protruding electrode material by performing heat treatment to form a protruding electrode on the terminal electrode portion. Method.