Semiconductor integrated circuit device

Details Semiconductor integrated circuit device Semiconductor integrated circuit device

2002-04-23

2004-04-13

Flynn, Nathan J. (Department: 2826)

Active solid-state devices (e.g., transistors, solid-state diode

Gate arrays

With particular signal path connections

C257S296000, C257S529000, C257S665000, C257S700000, C257S701000, C257S702000, C257S737000, C257S758000, C257S759000, C257S760000, C257S765000, C257S762000

Reexamination Certificate

active

06720591

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor integrated circuit device and a method of manufacturing the same. More specifically, the present invention relates to a technique effectively applied to a CSP (chip size package) formed by applying a wafer process, i.e., a so-called wafer level CSP (WL-CSP) or a wafer process package, which is a scheme in which a packaging step is completed in a wafer state.
BACKGROUND OF THE INVENTION
A scheme in which a packaging process (post-process) and a wafer process (pre-process) are integrated to each other to complete a packaging step in a wafer state, i.e., a technique so-called a wafer level CSP, has the following advantage. That is, since a packaging process is performed by applying a wafer process, the number of steps can be made considerably smaller than that of a conventional method in which a packaging process (post-process) is performed to each chip cut from a wafer. The wafer level CSP is also called a wafer process package (WPP).
In the wafer level CSP, a wiring layer in the CSP called an interposer for converting the pitch of bonding pads into the pitch of solder bumps can be replaced with rerouting layers formed on a wafer. For this reason, the wafer level CSP is expected to achieve the reduction in number of steps and the reduction in manufacturing cost of a CSP.
The wafer level CSP is described in, e.g., “Electronic Packaging Technology 2000 Special Number” issued by Gijyutsu-chyosa-kai Corporation (issued on May 28, 2000) pp. 81 to 113, International Patent Publication No. WO99/23696, Japanese Patent Laid-Open Publication No. 2000-91339, Japanese Patent Laid-Open Publication No. 2000-138245, Japanese Patent Laid-Open Publication No. 2000-216253, and the like.
SUMMARY OF THE INVENTION
In the conventional method in which the packaging process (post-process) is performed to each chip cut from a wafer, a memory LSI such as DRAM (Dynamic Random Access Memory) has a redundancy function for repairing the defect area created in the wafer manufacturing process, which makes it possible to improve the production yield.
This is a defect repairing function to prevent the defect from spreading over the entire chip even if a defect occurs in a part of a circuit. Such defect repairing is performed in such a manner that rows and columns of spares (redundant circuit) are prepared in advance in a part of a circuit, and when an address signal enters the defective cell (defect bit) in the memory array, the rows and columns of spares are selected.
The replacement of the defect parts with the spare parts is made by cutting a fuse connected to an address switching circuit. In the cutting of the fuse, a current fusion cutting or a laser fusion cutting is generally used. Of the two, the laser fusion cutting is mainly employed because of the high degree of freedom in replacement program and advantages in area efficiency.
The fuse for repairing the defect is constituted of electrode wiring materials such as metal and polycrystalline silicon and is formed simultaneously in a step of forming a semiconductor element or a wiring (wafer process) on a wafer main surface. When the probe test performed in the final step of the wafer process detects the defect cell, the above-mentioned fuse is cut by means of laser to allocate the address corresponding to the defect cell to the redundant cell.
In ordinary cases, on the wafer surface, a surface protection layer termed as a passivation layer is formed on a metal wiring of the uppermost layer, and a resin layer such as polyimide is formed thereon. The passivation layer serves as a protection layer to prevent moisture from penetrating into a circuit from the wafer surface and is constituted of a fine inorganic dielectric layer such as a silicon oxide layer and a silicon nitride layer deposited by, for example, the plasma CVD method. In addition, the resin layer is formed with an aim to prevent the soft error due to the &agr;-ray, to prevent the damages to the chip surface due to the silicon filler in a resin (molding resin) for sealing the chip, and to relax the stress applied to the interface between the passivation layer and the molding resin.
The above-mentioned passivation layer and the resin layer are thickly formed with a thickness of micrometer (&mgr;m) order. Therefore, for the defect repairing by cutting the fuse, the removal of the passivation layer and the resin layer on the fuse is required in advance of the probe test. Also, in the case where the fuse is formed of the relatively lower conductive layer, the interlayer dielectric layer lower than the passivation layer must be etched to reduce the thickness thereof.
For example, the process for removing the dielectric layer on the fuse proceeds as follows. First, a semiconductor element is formed on a main surface of a wafer, and subsequently, multiple layers of metal wirings are formed thereon. In this process, the fuse is formed in any one of a series of steps from forming the semiconductor element to forming the uppermost metal wiring.
Next, for the control of the thickness of the dielectric layer on the fuse to about 1 &mgr;m, an opening is formed in the dielectric layer on the fuse by the dry etching with using a photo-resist layer as a mask, and thereafter, a passivation layer is formed on the uppermost metal wiring and in the bottom of the opening, and then, a polyimide layer is formed on the passivation layer. The passivation layer is formed by depositing a silicon nitride layer and a silicon oxide layer by the plasma CVD method at a temperature of 400° C. to 500° C. The polyimide layer is formed by the spin coating method. Thereafter, the baking process at a temperature of about 350° C. is performed to cure the layer.
Subsequently, a photo-resist layer is formed on the polyimide layer, and the resin layer on the fuse is removed by the wet etching with using the photo-resist layer as a mask, thereby exposing the passivation layer. And simultaneously, a polyimide layer in the area used to form a bonding pad serving as an external connection terminal of a chip is removed to expose the passivation layer.
Next, after removing the photo-resist layer, the passivation layer on the fuse (the area in which the opening is formed in the dielectric layer) is removed by the dry etching with using the polyimide layer as a mask. And simultaneously, the passivation layer in the area used to form the bonding pad is removed to form the bonding pad.
Then, when the probe test performed in the final step of the wafer process detects the defect cell, the defect repairing is performed in such a manner that laser is irradiated to a predetermined fuse through the opening formed in the upper dielectric layer on the fuse in order to cut the fuse.
However, the inventors of the present invention have found out that when the defect repairing process as described above is applied to the conventional manufacturing process of the wafer level CSP, the following problems inevitably occur.
More specifically, in the case of the wafer level CSP, a rerouting layer is formed on the polyimide layer covering the wafer surface and a bump electrode serving as an external connection terminal is connected to one end of the rerouting layer after performing the probe test and the defect repairing. Therefore, the metal layer gets into the opening on the fuse during a step of forming the metal layer for the rerouting layer on the polyimide layer. Accordingly, a step of removing the metal layer in the opening by the use of etching solution is required in order to prevent the short circuit of the fuse cut by the laser via the metal layer. However, the corrosion of the fuse is caused if the etching solution is left in the opening.
Furthermore, in the manufacturing process of the wafer level CSP including the defect repairing process, openings for laser irradiation is left in the polyimide layer on the fuse. Therefore, when forming the rerouting layer on the polyimide layer, the rerouting layer must be arranged so as to avoid the openings. Consequently, the degre

Affiliated with

Also associated with

Rating

Semiconductor integrated circuit device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Semiconductor integrated circuit device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor integrated circuit device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3187471