JP2936680B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A method of forming a gold bump is described in connection with a method of forming a gold bump in contact with a metal film formed on a semiconductor substrate. The altered layer consisting of a natural oxide film formed on the surface is removed, and then the semiconductor substrate is transferred to a plating apparatus under an inert atmosphere without being exposed to the outside air, and is subjected to gold plating. It is constituted by a method of manufacturing a semiconductor device including a step of forming a gold bump in contact with a film.

[Industrial applications]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for forming a gold bump.

With the progress of high integration of LSIs, the flow of forming gold bumps on a chip and completing mounting by TAB (Tape Automated Bonding) method is increasing.

The TAB lead connects the gold bump to the external terminal.
In the manufacturing process, it is an issue to form gold bumps at low cost and with good yield.

[Conventional technology]

3 (a) to 3 (c) are cross-sectional views in the order of steps showing the formation of a conventional gold bump. Hereinafter, a conventional method of forming a gold bump will be described with reference to these drawings.

Referring to FIG. 3 (a), an Al wiring 2 is formed on a Si substrate 1, and an insulating film 3 for protecting the Al wiring 2 is formed. An opening is formed in the insulating film 3 for connecting the Al wiring 2 to the outside, and Ti (titanium) is formed on the entire surface.
Is sputtered to form a Ti film 4, and then Pd (palladium) is sputtered to form a Pd film 12. Next, a resist is deposited and patterned to form a resist mask 5 having openings for forming gold bumps.

Referring to FIG. 3B, Au (gold) plating is performed on the Pd film 12 from the opening to form a gold plating layer 6.

Referring to FIG. 3C, the resist mask 5 is removed, and the Pd film 12 and the Ti film 4 are etched using the gold plating layer 6 as a mask.
To complete.

Ti has a role as a barrier metal to avoid direct contact between Al and Au, but Ti has a high surface activity, so it is easy for oxide films to grow, and an altered layer is formed on the surface before entering the gold plating process. When a gold bump is formed thereon, the bump is peeled off. To avoid this bump peeling, Pd is continuously grown on Ti.

On the other hand, the presence of Pd and the increase in the number of steps for forming the Pd film cause a disadvantage that the manufacturing cost is increased.

[Problems to be solved by the invention]

An object of the present invention is to provide a method of forming a gold bump having a high density directly on a Ti film, and to reduce the cost as compared with the conventional method of forming a Pd film in the middle.

[Means for solving the problem]

The object is to form a gold bump 6a in contact with the metal film 4 formed on the semiconductor substrate 1 by removing an altered layer made of a natural oxide film formed on the surface of the metal film 4, Manufacturing of a semiconductor device including a step of transporting the substrate 1 to a plating apparatus 8 under an inert atmosphere without being exposed to the outside air, and forming a gold bump 6a in contact with the metal film 4 by performing gold plating. Solved by the method.

[Action]

Usually, at the stage of forming a resist mask for forming the gold bump 6a, it is unavoidable to form an altered layer on the surface of the metal film 4 such as Ti, but in the present invention, this altered layer is removed. Subsequently, the semiconductor substrate is transported to the plating apparatus 8 under an inert atmosphere without being exposed to the outside air. In this way, the altered layer is not formed after the altered layer is removed and before the gold plating is started.

Therefore, the conventional formation of a Pd film becomes unnecessary,
Cost reduction can be achieved.

〔Example〕

1 (a) to 1 (c) are cross-sectional views in the order of steps showing the formation of a gold bump according to the present invention. The mask, 6 indicates a gold plating layer, and 6a indicates a gold bump. FIG. 2 is a schematic diagram for explaining a manufacturing apparatus for forming a gold bump, wherein 7 denotes an etching chamber, 8 denotes a plating chamber, 9 denotes a transport mechanism, and 10a, 10b, 11a, and 11b denote valves.

Hereinafter, embodiments of the present invention will be described with reference to these drawings.

An Al wiring 2 is formed on a Si substrate 1, and an insulating film 3 for protecting the Al wiring 2 is formed. An opening is formed in the insulating film 3 for connecting the Al wiring 2 to the outside, and Ti (titanium) is formed on the entire surface.
Is sputtered to form a Ti film 4 having a thickness of about 0.5 μm.

Next, a resist mask 5 having an opening for depositing a resist and patterning the resist to form a gold bump is formed.
To form At this time, the surface of the Ti film 4 is oxidized to form an extremely thin altered layer (FIG. 1A).

This silicon substrate is placed in the etching chamber 7, and the resist residue and the altered layer remaining on the surface of the Ti film 4 are removed by RF etching.

Thereafter, the valves 10b and 11b are opened, and the silicon substrate is transferred from the etching chamber 7 to the plating chamber 8 by the transfer mechanism 9.
The room in which the transfer mechanism 9 is located and the plating room 8 are set to an inert atmosphere by flowing nitrogen (FIG. 2).

Perform gold plating in a nitrogen atmosphere and apply a thickness of 2
A gold plating layer 6 having a thickness of 0 to 30 μm is formed (FIG. 1B).

The semiconductor substrate is taken out by opening the valve 11a, the resist mask 5 is removed, and then the Ti film 4 is removed by etching using the gold plating layer 6 as a mask to form a gold bump 6a (FIG. 1 (c)). ).

The altered layer on the surface of the Ti film 4 can also be removed by performing reverse sputtering using a sputtering device.

〔The invention's effect〕

As described above, according to the present invention, the Pd film conventionally formed in the middle becomes unnecessary, and the cost can be reduced.

The present invention contributes to LSI cost reduction and yield improvement.

[Brief description of the drawings]

1 (a) to 1 (c) are sectional views in the order of steps showing the formation of a gold bump according to the present invention, FIG. 2 is a schematic view for explaining a manufacturing apparatus for forming a gold bump, and FIG. 3 (a). FIGS. 1C to 1C are cross-sectional views in the order of steps showing the formation of a conventional gold bump. In the figure, 1 is a semiconductor substrate and a Si substrate, 2 is an Al wiring, 3 is an insulating film, 4 is a metal film and a Ti film, 5 is a resist mask, 6 is a gold plating layer, 6a is a gold bump, 7 Denotes an etching chamber, 8 denotes a plating chamber, 9 denotes a transport mechanism, 10a, 10b, 11a, 11b denotes a valve, and 12 denotes a Pd film.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/60

Claims (1)

(57) [Claims] When forming a gold bump (6a) in contact with a metal film (4) formed on a semiconductor substrate (1), an alteration comprising a natural oxide film formed on the surface of the metal film (4). The layer is removed, and then the semiconductor substrate (1) is transferred to a plating apparatus (8) under an inert atmosphere without being exposed to the outside air, and the metal film (4) is plated by gold plating. A method for manufacturing a semiconductor device, comprising a step of forming a gold bump (6a) to be in contact with the semiconductor device.