JP3045107B2 - Assembly method of solid-state imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for assembling a solid-state imaging device.

[0002]

2. Description of the Related Art With the miniaturization of pixels, solid-state imaging devices have become more sensitive to fine dust. In addition, the formation of on-chip microlenses on the element has been generalized to prevent a decrease in sensitivity, and the chip surface is made of an organic substance, which makes it easier for dust to adhere to the chip surface. It has become easily damaged.

A method of assembling a conventional solid-state imaging device will be described with reference to FIGS.

In the conventional assembling method shown in FIG. 3, in a dicing step, a protective sheet is attached to a surface of a wafer on which a solid-state image pickup device is formed, and the protective sheet is attached to a dicing sheet to perform dicing. Then, the protective sheet is peeled off from the element surface using a peeling sheet, thereby reducing scratches and dust on the element surface due to cutting chips at the time of dicing.

In the conventional method shown in FIG. 4, a protective coating layer is formed on the surface of a wafer on which a solid-state imaging device is formed, dicing is performed, the device is die-mounted in a package, and an organic solvent is used. By dissolving and removing the protective coat layer and then washing the element with water together with the package, the adhesion of dust and scratches is reduced.

In the conventional method shown in FIG. 5, a method is used in which a thermal depolymerization type resin is used as a protective coating layer and the resin on the element surface is removed by heating for fixing the mounting material after die mounting. I have.

[0007]

However, in the method shown in FIG. 3, the surface of the solid-state imaging device is exposed to the atmosphere after dicing and before the cap for sealing is mounted on the package. In the process, garbage,
There was a problem that the attachment of scratches could not be prevented.

Further, in the conventional method shown in FIG. 4, the surface is protected until the die mounting step, and the protective coating layer is removed with an organic solvent. It is extremely difficult to select a solvent that does not have such a property, and it is also difficult to completely remove the protective coating layer on the microfabricated on-chip microlens with an organic solvent, so that dust on the element surface increases. Great potential. Further, there is a problem that dust and scratches may be formed on the element surface in the washing with water after the removal.

Further, in the method shown in FIG. 5, the decomposed debris of the thermally depolymerized resin after heating remains between the miniaturized on-chip microlenses, which rather increases the adhesion of dust on the element surface. There were challenges.

As described above, according to the conventional method, it is possible to prevent cutting chips from adhering to and damage to the surface of the solid-state imaging device in the dicing step, but it is necessary to remove the protective layer on the chip surface after die mounting. It is not easy to select a layer or a solvent for removing the layer, and the protective layer cannot be completely removed. Was poor.

An object of the present invention is to provide a method for assembling a solid-state imaging device which solves the above-mentioned problems.

[0012]

In order to achieve the above object, a method for assembling a solid-state imaging device according to the present invention comprises a sheet attaching step, an element cutting step, a glue curing step, a mounting step, and a mount cure. Process and protective sheet peeling work
And a degree at least, a method of assembling a solid-state imaging device which performs assembling of the solid-state imaging device, the solid-state imaging device, a plurality of formed on a wafer is divided, the printed circuit board
The sheet sticking step is a step of sticking a protective sheet to an element forming surface of a wafer on which the plurality of solid-state imaging elements are formed, and sticking a wafer mounting sheet to the back surface. The device cutting step includes cutting the protection sheet along the dividing line of the wafer with a cutter and cutting the plurality of solid-state image pickup devices individually. A process for curing the glue of the sheet and the wafer mounting sheet is performed, and the mounting step removes the solid-state imaging device from the wafer mounting sheet while mounting the protection sheet and mounts the solid-state imaging device. In the mount curing step, the mounting agent of the solid-state imaging device is cured at a low temperature. Causing process is intended to perform the
In the protective sheet peeling process, the solid-state image sensor is
After mounting, attach a release sheet on the protective sheet
The protective sheet on the solid-state imaging device by the release sheet.
Are performed collectively .

[0013] Further, a transparent protective sheet is used.
You.

[0014]

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 are views showing an embodiment of the present invention in the order of steps.

First, as shown in FIG.
a, a UV curable protective sheet 1 is attached to the element forming surface, and a wafer mounting sheet 3 for fixing the wafer is attached to the opposite surface (sheet attaching step in FIG. 1). Is fixed by a wafer mounting sheet 3 (wafer mounting step in FIG. 1), and a cutter 8 is moved from above the protection sheet 1 along a scribe line 4 serving as a dividing line, and cut into the wafer mounting sheet 3 to remove the wafer 2a. After cutting, the solid-state imaging device 2
(Dicing (element cutting) in FIG. 1)
Process).

Next, as shown in FIG. 2 (b), the elastic wafer mounting sheet 3 is pulled outward to expand it, thereby increasing the space between the divided solid-state image sensors 2 and the solid-state image sensor 2 and the protective sheet. 1. UV is irradiated from both sides of the wafer 2a so that the wafer mounting sheet 3 is separated from each other (double-sided UV irradiation (glue curing step in FIG. 1)). Here, by using a transparent protective sheet 1, it is possible to automatically pick up a good-quality solid-state imaging device 2 from the wafer 2a after dicing.

Next, as shown in FIGS. 2C and 2D, at least one surface has a plurality of conductive paths.
The solid-state imaging device 2 mounted on the protection sheet 1 is mounted on a predetermined area of the printed circuit board 5 on which the bonding pattern is formed, that is, die mounting is performed (FIG. 1).
Sheet enlargement / mounting process). FIG. 2D is a plan view of FIG. 2C.

At this time, conventionally, the chip is die-mounted on the package. However, by die-mounting the chip on the substrate 5, the protection sheets 1 on a large number of chips can be peeled off once. Although the number of the solid-state imaging devices 2 mounted on the substrate 5 can be any number, in order to surely peel off the protective sheet 1, the substrate size is set to 15 cm □ or less, and according to the size of the solid-state imaging device 2, Die mount the number that can be loaded.

A silver paste is usually used for the mounting material 6 used for performing the die mounting of the solid-state imaging device 2. The silver paste is classified into a two-pack type (base agent and hardener) type and a one-pack type (kneading hardener) type. By optimizing the mixing ratio, temperature, time, etc. The paste is cured, and the chip is fixed. However, it is necessary to perform mount cure at a temperature as low as possible, for example, 40 ° C. or lower, in order to prevent the viscosity of the paste cured by UV irradiation of the protective sheet 1 (see FIG. 1). Process). The characteristics of the solid-state imaging device 2 are easily affected by heat. However, by lowering the mount cure temperature as in the embodiment of the present invention, the effect on the chip is reduced.

Next, as shown in FIG. 2 (e), a peeling sheet 7 is placed on the surface of the substrate 5 on which the solid-state imaging device 2 is die-mounted, and rubbed with a roller or the like to remove the end face of the protective sheet 1 for peeling. The peeling sheet 7 is peeled off from the substrate 5 together with the protective sheet 1 by adhering to the glue surface of the sheet 7 (sheet peeling step in FIG. 1). At this time, the protective sheet 1 is irradiated with UV, and the adhesive surface is cured to lose its viscosity. Therefore, a part of the protective sheet 1 is adhered to the peeling sheet 7 and is pulled. Easy to peel off. After the protective sheet 1 is peeled off by the peeling sheet 7, the process proceeds to the next step, a bonding step.

In this embodiment, since the protection sheet 1 is placed on the imaging surface of the solid-state imaging device 2 before bonding,
Dust and scratches do not adhere to the element surface. Also, by using a UV-curable sheet as the protective sheet 1, the wafer mounting sheet is usually a UV-curable sheet, and UV is radiated when the chip is removed therefrom. By making the protective sheet transparent, the step of removing chips from the wafer mounting sheet can be automatically performed.

Further, by using a substrate without using a package at the time of mounting, it is possible to easily and collectively peel off protective sheets on a large number of chips, and subsequent processing is also facilitated. In addition, by using a release sheet, even in the event that a chip that cannot be separated from the protective sheet is generated, the chip can be subjected to the separation step again by performing the same steps.

[0025]

As described above, according to the present invention, in the process of assembling a solid-state imaging device, a protective sheet is attached to the surface of a wafer prior to dicing, thereby preventing the attachment of cutting chips and scratches during dicing. Can be
Moreover, it is possible to prevent dust and the like from adhering to the atmosphere before the bonding step for driving the solid-state imaging device.

Further, in the present invention, by using a printed circuit board without using a package, it is possible to obtain a solid-state imaging device which can be easily applied after bonding.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention in the order of steps.

2A and 2B are a sectional view and a plan view showing an embodiment of the present invention in the order of steps.

FIG. 3 is a flowchart showing a conventional example in the order of steps.

FIG. 4 is a flowchart showing a conventional example in the order of steps.

FIG. 5 is a flowchart showing a conventional example in the order of steps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Protective sheet 2a Wafer 2 Solid-state image sensor 3 Wafer mounting sheet 4 Scribe line 5 Substrate 6 Mounting material 7 Peeling sheet

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 27/14-27/148 H01L 21/78 H01L 21/52

Claims (2)

(57) [Claims] 1. A solid-state imaging device having at least a sheet sticking step, an element cutting step, a glue curing step, a mounting step, a mount curing step, and a protection sheet peeling step, and assembling a solid-state imaging element. The solid-state imaging device is divided into a plurality of solid-state imaging devices, formed on a wafer , and mounted on a printed circuit board, and the sheet attaching step is performed on a wafer on which the plurality of solid-state imaging devices are formed. A process of attaching a protective sheet to the element forming surface and attaching a wafer mounting sheet to the back surface of the protective sheet. The element cutting step cuts the protective sheet along the dividing line of the wafer with a cutter. And a step of individually cutting out a plurality of solid-state imaging devices. The mounting step performs a process of removing the solid-state imaging device from the wafer mounting sheet and mounting the solid-state imaging device with the protection sheet adhered. Wherein the mount curing step performs a process of curing the mounting agent of the solid-state imaging device at a low temperature, and the protection sheet peeling step includes removing the solid-state imaging device from a printed circuit board.
After mounting on the board, paste the release sheet on the protective sheet
The protective sheet on the solid-state image sensor is attached by the release sheet.
A method for assembling a solid-state imaging device, wherein a process for peeling off a batch is performed . 2. The method for assembling a solid-state imaging device according to claim 1 , wherein a transparent protective sheet is used.