JPS62177946A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To perform the etching of a metal layer except a pad electrode only by one step by forming a metal layer under a metal bump in a self-aligning manner by an electrolessly plating method. CONSTITUTION:An aluminum pad electrode 3 and an insulating film 4 are formed on an insulating film 2 on a semiconductor substrate 1, and the film on the electrode 3 is removed. The entire surface is coated with a metal layer 5 of Cr or the like, and an aluminum layer 6 is formed on the layer 5. A photosensitive resin film 7 remains on a region to be formed with a metal bump, and the aluminum layer except this region is oxidized to alter it to an aluminum oxide film 8. The film 7 and the film 6 under the film 7 are removed, and a metal layer 9 of Cu or the like is formed by an electrolessly plating method on the layer 5. Then, with the layer 9 as a plating electrode a metal bump 10 is formed of Au, Cu or the like. Thereafter, with the bump 10 as a mask the layer 8 and the layer 5 are removed by etching. Then, after the bump is formed, the etching of the metal layer is performed only by one step to prevent the pad electrode from being damaged due to the etching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of manufacturing a semiconductor device having metal bumps.

[Conventional technology]

Conventionally, in the manufacturing method of this type of semiconductor device, for example, the metal bumps used for gigantic bonding are
It is manufactured by the manufacturing process shown in Figures (al to (dl). That is, an aluminum film for forming a pad electrode is coated on a first insulating film 22 such as a silicon oxide film formed on a semiconductor substrate 21, for example. The metal is deposited to a thickness of about 1,0.1, and the metal is removed leaving the powder electrode portion 23. After that, a second insulating film 24 such as a silicon oxide film formed by chemical vapor deposition (CVD) is deposited. The entire surface is covered, and holes 2 for producing 9 electrodes are formed on the aluminum pad electrodes 23.
5. Completely form (Fig. 2(a)).

Next, a plurality of metal layers 26 and 27' are sequentially laminated over the entire surface by sputtering or the like. As the material of this metal layer, multiple layers such as Cr-Cu, N1-Cu, Cr-Cu-Au, etc. are used. It is desirable to sputter this metal layer continuously in a vacuum, and it is better to perform a pretreatment for sputtering α11 to remove the natural aluminum oxide film on the surface of the aluminum film (FIG. 2(b)).

Further, a photosensitive resin film 28 for use as a plating mask is applied over the entire surface of the metal layer 26, 27, and an opening 29 for a metal bump forming portion is formed in a portion on the aluminum pad electrode. Next, 1
j1'' metal film 26.27 Au as common electrode of gold force
Alternatively, the metal pan 130 is formed by electro-depositing Cu, copper, etc. This metal bump 30 is usually formed to have a thickness of 10 to 20 μm (FIG. 1(C)). After that, the photosensitive resin film 2
8 and the metal film 26 and 27, the final metal bump structure is obtained (see Fig. 1(d)).
)).

[Problem that the invention seeks to solve]

In the conventional semiconductor device manufacturing method described above, after forming metal bumps, it is necessary to remove multiple layers of metal (1m26, 277f) by etching.For example, in the case of Cr, potassium ferricyanide and caustic soda are If the mixed solution is Cu, it is necessary to use a strong acid) There are problems such as the metal in the important parts of the PJT such as Shiba and Sodo Densai being etched away due to seepage along the etching. Furthermore, Cu is present on the metal bumps and Cu' is also present on the multiple metal layers below.
(In the structure using Z, the metal bumps themselves are also etched away, so there are drawbacks such as large variations in the thickness of the gold h5. Making money with technology and making money under the bump JF
The purpose of the present invention is to provide a manufacturing method that only requires an elastomeric layer of the metal layer, by using an electroless plating method, since etching was difficult due to the thickness of 1 m or 2 layers.

[Means to solve all problems]

The method for manufacturing a semiconductor device of the present invention includes the steps of: forming a metal layer in a predetermined shape entirely on a first insulating film formed on one surface of a semiconductor substrate; forming a film and forming a hole in a predetermined region thereof leading to the upper surface of the metal electrode; and sequentially laminating a first metal layer and an aluminum layer on the second insulating film including the hole. a step of converting all of the aluminum layer other than the area on the metal electrode into an aluminum oxide layer using an anodic acetate method; removing the predetermined aluminum layer by etching; a step of fully exposing a first metal layer; a step of fully forming a second metal layer on the exposed first metal layer by electroless plating; and a step of fully forming a second metal layer on the exposed first metal layer; Said second layer by plating method.
The method is characterized by comprising the steps of: forming a third metal layer in contact with the metal layer; and removing the aluminum oxide layer and the first metal layer by etching, using the entire third metal layer as a mask.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 [a+ to ge] is a vertical cross-sectional view of an embodiment of the present invention in the order of steps.

An insulating film 2 is formed on one main surface of the semiconductor substrate l by thermal oxidation or the like. Aluminum interconnects (not shown) and aluminum bud electrodes 3 are formed thereon to connect the semiconductor elements. Furthermore, CVD is applied as a protective film on aluminum wiring and aluminum pad electrodes.
An insulating film 4 is formed by a method. Then, an opening for an external electrode is formed in a part of the insulation 4 on the aluminum pad electrode 3 by photoetching (FIG. 1(a)).

Next, a metal layer 5. is formed by sputtering or the like. For example, Cr
Or look at '4M on the Ti mirror surface. This metal layer 5 is
The gold remains under the metal bump as an adhesive layer for the bump.

The thickness used is 10007V to 5000A. Then, an aluminum layer 6 is formed to a thickness of, for example, 5000 Å using a sputtering method or the like, and the entire photosensitive resin film 7 is selectively left on the metal bump formation limb regions on the aluminum layer 6 (FIG. 1(b)). ).

Next, the aluminum layer other than the area where metal bumps are to be formed is changed into an aluminum oxide film 8 by anodizing. Here, the anodization method is a method in which aluminum is converted into aluminum laminate aluminum oxide by applying a full voltage to the aluminum as an anode in an electrolytic solution and passing a current. After step 7, the photosensitive resin film 7 is removed (FIG. 1(C)).

Next, using an etching solution such as phosphoric acid that is capable of selectively etching the aluminum film 6 and the aluminum oxide film 8 and does not remove the underlying metal film 5,
Etch away the aluminum. Thereafter, a second metal layer of 9%, for example, Cu or Au, is deposited on the surface of the gold bird film 5 from which the aluminum film has been removed by electroless plating.
It is formed to a thickness of about 1.0 μm. For example, even if the underlying metal layer is difficult to adhere to by electrolytic plating, such as 'I'i, C, there are conditions under which a metal film can be grown by a combination of pretreatment and electroless plating. Thereafter, a metal pant with a thickness of 10 to 20 μm is formed using A11 or Cu1 solder by electrolytic plating using the second metal layer 9 as a plating electrode (FIG. 1(e)). Finally, using the metal bang 10 as a mask, the aluminum oxide layer 8 and the metal layer 5 are removed using their respective etching solutions. In the present invention, one metal layer is entirely formed under the metal bang in a self-aligned manner with respect to the aluminum oxide layer using an electroless plating method. Therefore, since it relies on a strong acid or strong base using the metal bump as a mask, the conventional problem of the wiring aluminum etc. being etched due to seepage of the etching solution is greatly reduced. Furthermore, even if the same material as the metal bump is used for the metal layer formed in a self-aligned manner with respect to the aluminum oxide layer, there is no need to remove this metal layer by etching, so the metal bump can be removed by etching. Fear will disappear.

In the above embodiment, the metal bumps are entirely formed on the pad electrode, but it goes without saying that this manufacturing method can be applied even if the metal bumps are not necessarily formed on the pad electrode.

〔Effect of the invention〕

As explained above, the present invention uses a metal no.
The same aluminum oxide film that forms and lies down? Using this as a mask, multi-metal bumps are formed using the electroplating method. After forming a metal bump, the aluminum oxide film, which is easy to etch, and the underlying metal layer are all removed by etching.In contrast, conventional multi-layered metal layers are sequentially etched away and the wiring aluminum is removed by seepage of the etching solution. This has the advantage of preventing changes in the shape of the metal bang when the same metal as the metal bang must be etched.

In addition, electroless plating requires plating at high temperatures, so selective electroless plating is possible even at temperatures that photosensitive resin films cannot withstand by using anodized aluminum oxide film as a plating mask. becomes.

[Brief explanation of drawings]

1.21 FIG. ... Semiconductor substrate, 2, 22... First insulating film, 3, 23... Aluminum pad electrode,
4.24... Second insulating film, 5, 9, 26, 2
7...Metal layer, 6...Aluminum layer, 7.28...Photosensitive resin film, 8...
Aluminum oxide layer, 10.30... Metal bump, 25... Hole for exposing the number of electrodes. 29...Opening of metal bump forming part. th/time

Claims (1)

[Claims] forming a metal electrode in a predetermined shape on a first insulating film formed on one main surface of a semiconductor substrate; forming a second insulating film on the entire surface in contact with the metal electrode; and forming a second insulating film on the entire surface in contact with the metal electrode; a step of forming an opening communicating with the upper surface of the electrode; a step of sequentially laminating a first metal layer and an aluminum layer on the second insulating film including the opening; a step of converting all areas other than a predetermined region into an aluminum oxide layer using an anodizing method; a step of etching away the aluminum layer in the predetermined region to expose the first metal layer; and a step of exposing the first metal layer. a step of forming a second metal layer thereon by electroless plating, and a step of forming a third metal layer in contact with the second metal layer by electroplating using the second metal layer as a plating electrode. and a step of etching away the aluminum oxide layer and the first metal layer using the third metal layer as a mask.