JPH0548059A - Production of solid-state image sensor - Google Patents

Abstract

PURPOSE:To improve the yield and suppress the wear of dicing blade by preventing the dust from adhering to the surface of solid-state image sensor. CONSTITUTION:In the dicing processes for separating respective chips from a solid-state image sensor in wafer state, a sheet 3 is attached on the chip of wafer 1 in a manner that it covers entirely the photoelectric conversion section on respective chips of the wafer 1 and simultaneously does not cover the bonding pads and scribe lines (b). After performing dicing to divide the wafer 1 into chips 1a (c), a rear sheet is stretched to separate each chip. All chips are mounted onto the package while the sheet 3 is attached on them, and wire bonding is applied. The sheet 3 is peeled off just before packing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid-state image pickup device, and more particularly to a method for manufacturing a solid-state image pickup device including a step of separating a wafer into individual chips.

[0002]

2. Description of the Related Art In a semiconductor device dicing process, a wafer is deeply cut along a scribe line on a wafer by a dicing blade to be divided into individual chips. Thus, in the case of a solid-state image sensor, defects such as black scratches will occur if silicon cutting debris adheres to the surface of the photoelectric conversion unit. To avoid this, protect the device surface with a sheet prior to the dicing process. Is being done.

4A to 4C are process cross-sectional views for explaining a conventional manufacturing method. First, as shown in FIG.
The wafer 1 is attached to the back sheet 2, and then the top sheet 8 is attached to the front surface (element surface) of the wafer 1 as shown in FIG. Next, as shown in FIG. 4 (c), a cut is made in the wafer by a rotary blade, and as shown in FIG. 4 (d), the back sheet 2 is enlarged to separate the wafer 1 into individual chips 1a. Split into.

According to this manufacturing method, dust such as cutting scraps adheres to the surface sheet 8 and is removed at the same time when the sheet 8 is removed thereafter, so that the generation of black scratches is suppressed.

[0005]

In the conventional manufacturing method described above, it is necessary to peel off the sheet after mounting the chip on the package and before performing the wire bonding. Therefore, it is difficult to improve the yield because dusts generated during wire bonding tend to adhere.

Further, in the conventional method of sticking a sheet on the entire surface, it is necessary to cut extra by the thickness of the surface sheet, and since the sheet is generally made of an organic material, the blade is easily damaged. There was a problem. Further, when the film thickness of the sheet is increased, the light transmittance is reduced, which makes it difficult to recognize the scribe line.

[0007]

A method of manufacturing a solid-state image pickup device according to the present invention includes a photoelectric conversion section including photoelectric conversion elements arranged one-dimensionally or two-dimensionally, and an output detector around the photoelectric conversion section. And selectively forming a sheet that covers the photoelectric conversion unit and exposes the bonding pad and the scribe line on a wafer in which a plurality of solid-state imaging devices including a bonding pad and the like are formed. And a step of separating the wafer into individual chips.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. 1A to 1D are process cross-sectional views showing a first embodiment of the present invention. First, as shown in FIG. 1A, a wafer 1 having a plurality of solid-state image pickup device chips formed therein is attached onto a back sheet 2, and then a photoresist 3a is applied to the surface of the wafer 1.

Next, the photoresist 3a is exposed and developed to form a sheet 3 which completely covers the photoelectric conversion portion of each solid-state image pickup device and exposes the bonding pads existing in the peripheral portion of the device [( b)].

Next, cutting is performed with a blade along the scribe line to divide the wafer 1 into chips 1a [(c) of FIG. 1]. Subsequently, the back sheet 2 is enlarged to separate the chips 1a [(d) of FIG. 1].

FIG. 2 shows the state of the chip after being divided as shown in FIG. 1 (d). As shown in the figure, the photoelectric conversion unit 4 is formed in the central portion of the solid-state imaging device chip 1a, and in the peripheral portion 5 thereof, in addition to the peripheral circuit, a plurality of bonding pads 6 are provided along the outer edge. Has been formed.
The sheet 3 is formed so as to completely cover the photoelectric conversion section 4 and avoid the bonding pad 6 and the scribe line.

After the state shown in FIG. 2, the chip is mounted in the package in this state and wire bonding is performed. After that, the sheet 3 is peeled off, a cap is attached, and the manufacture of the solid-state imaging device is completed.

According to this embodiment, since the cutting portion is not covered with the organic sheet, abrasion of the blade during cutting is suppressed. In addition, since the scribe line is exposed, it is easy to recognize the scribe line, and the alignment can be accurately performed. Furthermore, after the chip is mounted in the package, the bonding can be performed as it is, and the sheet can be peeled immediately before the sealing, so that the chance of dust adhesion can be greatly reduced.

FIG. 3 is a perspective view of a wafer for explaining the second embodiment of the present invention. Not limited to solid-state image sensor,
Generally, in a semiconductor element, each element is inspected in a wafer state to mark its quality. In this embodiment, the sheet 3 is used for this marking. That is,
In this embodiment, the quality of the chip is judged in the wafer state,
The sheet 3 is attached only on the non-defective chip, which is used as a marking. In this case, it is possible to facilitate recognition of non-defective products by appropriately selecting the thickness and color of the sheet 3.

As the means for forming the sheet 3, in addition to application of a liquid photoresist, sticking of a film, and the like, sticking of a dry film photoresist or printing method can be used. Further, the solid-state image sensor to which the present invention is applied includes not only a two-dimensional type but also a one-dimensional type.

[0016]

As described above, according to the present invention, the bonding pad and the scribe line are exposed on each chip and the photoelectric conversion section is exposed on each chip prior to the dicing process for separating the solid-state image pickup device from the wafer state into each chip. According to the present invention, it is possible to prevent the dust from directly adhering to the photoelectric conversion portion, and to minimize the decrease in yield due to the generation of black scratches. Further, according to the present invention, since the dicing blade does not cut the organic sheet,
Wear of the blade is suppressed. Further, since the scribe line is exposed, positioning can be performed easily, and workability in the dicing process is improved.

[Brief description of drawings]

FIG. 1 is a process sectional view showing a first embodiment of the present invention.

FIG. 2 is a plan view of a solid-state imaging device chip for explaining the first embodiment of the present invention.

FIG. 3 is a perspective view of a wafer for explaining a second embodiment of the present invention.

FIG. 4 is a process sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Wafer 1a ... Solid-state image sensor chip 2 ... Back surface sheet 3 ... Sheet 3a ... Photoresist 4 ... Photoelectric conversion part 5 ... Peripheral part 6 ... Bonding pad 7 ... Scribing line 8 ... Surface sheet

Claims (1)

[Claims] 1. A wafer on which a plurality of solid-state imaging device chips each having a photoelectric conversion portion in the center and a bonding pad formed in the peripheral portion are formed and which covers the photoelectric conversion portion and has the bonding pad and A method for manufacturing a solid-state imaging device, comprising: a step of selectively forming a sheet exposing a scribe line; and a step of separating the wafer into individual chips.