US20130048208A1

US20130048208A1 - Method for fabricating camera module

Info

Publication number: US20130048208A1
Application number: US13/219,948
Authority: US
Inventors: Tzy-Ying Lin; Chieh-Yuan Cheng; Hung-Yeh Lin
Original assignee: VisEra Technologies Co Ltd; Omnivision Technologies Inc
Current assignee: VisEra Technologies Co Ltd; Omnivision Technologies Inc
Priority date: 2011-08-29
Filing date: 2011-08-29
Publication date: 2013-02-28
Anticipated expiration: 2031-08-29
Also published as: TW201310106A; US8388793B1; CN102969321B; CN102969321A; TWI460485B

Abstract

The invention provides a method for fabricating a camera module. An exemplary embodiment of the method for fabricating a camera module comprises providing plurality of lens sets. A dry film layer is formed on the plurality of lens sets. The dry film layer is patterned to form a plurality of dry film patterns respectively attaching to a plurality of lens sets. The plurality of lens sets are separated. A lens set separated from the plurality of lens sets is bonded to an image sensor device chip. The dry film pattern on the lens set is removed.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to applying the dry film material by a wafer level lithography process to fabricate a camera module.
2. Description of the Related Art
The conventional camera module is fabricated by laminating lenses on a substrate having optical devices thereon, and then the substrate laminated with the lenses is diced and divided into several individual camera module units. During the formation of the conventional camera module, a product yield thereof is lowered because the removal step of a protection film for the plurality of optical lenses of the plurality of lens cubes may destroy an aperture of the optical lens.
A novel method for fabricating a camera module without destroying the apertures of the plurality of optical lenses is desired.

BRIEF SUMMARY OF INVENTION

Methods for fabricating a camera module are provided. An exemplary embodiment of the method for fabricating a camera module comprises providing plurality of lens sets. A dry film layer is formed on the plurality of lens sets. The dry film layer is patterned to form a plurality of dry film patterns respectively attaching to a plurality of lens sets. The plurality of lens sets are separated. A lens set separated from the plurality of lens sets is bonded to an image sensor device chip. The dry film pattern on the lens set is removed.
Another exemplary embodiment of the method for fabricating a camera module comprises a first wafer having a plurality of first lens elements thereon. A first spacer element on the first wafer for isolating the first lens elements each other is formed. A dry film layer is formed on the first spacer element. The dry film layer is patterned to form a plurality of dry film patterns respectively attaching to a plurality of lens sets. The plurality of lens sets are separated. A lens set separated from the plurality of lens sets is bonded to an image sensor device chip. The dry film pattern on the lens set is removed.
Yet another exemplary embodiment of the method for fabricating a camera module comprises a first wafer having a plurality of first lens elements thereon. A first spacer element on the first wafer for isolating the first lens elements each other is formed. A second wafer having a plurality of second lens elements thereon is bonded to the first spacer element, wherein the plurality of second lens elements aligns to the plurality of first lens elements. A second spacer element is formed on the second wafer for isolating the second lens elements each other. A dry film layer is formed on the second spacer element. The dry film layer is patterned to form a plurality of dry film patterns respectively attaching to a plurality of lens sets. The plurality of lens sets are separated. A lens set separated from the plurality of lens sets is bonded to an image sensor device chip. The dry film pattern on the lens set is removed
A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIGS. 1 a-1 c, 2 a-2 b, 3 a-3 b and 4-9 are cross section views or top views showing exemplary embodiments of a method for fabricating a camera module of the invention.

DETAILED DESCRIPTION OF INVENTION

The following description is of a mode for carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. Wherever possible, the same reference numbers are used in the drawings and the descriptions to refer the same or like parts.
The present invention will be described with respect to particular embodiments and with reference to certain drawings, but the invention is not limited thereto and is only limited by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual dimensions to practice the invention.
FIGS. 1 a-1 c, 2 a-2 b, 3 a-3 b and 4-9 are cross section views or top views showing exemplary embodiments of a method for fabricating a camera module of the invention. The method for fabricating the camera module utilizes a dry film to prevent an optical lens set from being covered by coating materials, such as an electromagnetic interference (EMI) shielding material or a light shielding material applied during subsequent processes.
FIG. 1 a is a cross section view showing the exemplary embodiment of lens sets constituted by lens elements on a single wafer.
Referring to FIG. 1 a, a plurality of lens sets in wafer level are provided. A first wafer 200 b having first lens elements 202 b thereon is provided. A first spacer element 203 b is then formed on the first wafer 200 b for isolating the first lens elements 200 b each other. The lens sets are constituted by first lens elements 202 b on two sides of a first wafer 200 b and first spacer elements 203 b. The first wafer 200 b may comprise a transparent material. The first spacer elements 203 b may be arranged as an array on two sides of the first wafer 200 b. Alternatively, the first lens elements 202 b and the first spacer elements 203 b may be respectively arranged on one side of the first wafer 200 b.
Alternatively, FIG. 1 b is a cross section view showing another exemplary embodiment of lens sets, in which the lens sets are constituted by lens elements on two wafers. As shown in FIG. 1 b, a second wafer 200 a having second lens elements 202 a thereon is bonded to the first spacer elements 203 b on the first wafer 200 b so that the first wafer 200 b and the second wafer 200 a are stacked together. A spacer element 203 a is then formed on the second wafer 200 a for isolating second lens elements 202 a each other. The second wafer 200 a may comprise a transparent material. The second spacer elements 203 a may be arranged as an array on the upper surface of the second wafer 200 a. The second lens elements 202 a align to the first lens elements 202 b. FIG. 1 c is a top view showing the exemplary embodiment of lens sets constituted by two wafers and lens elements thereon. Alternatively, one more wafer with lens elements thereon may bond to the second wafer 200 a or first wafer 200 b. The following description will take one embodiment as shown in 1 b and lc, but is not limited to the disclosed embodiments.
Next, referring to FIGS. 2 a and 2 b, a dry film layer 204 is laminated on the second spacer element 203 a by a pressing process. In one embodiment, the dry film layer 204 covers an entire region of the wafer-level lens sets constituted by the first wafer 200 b and the second wafer 200 a.
FIGS. 3 a and 3 b show a process step to form dry film patterns 204 a respectively attaching to the lens sets. The dry film layer 204 may be formed of a photosensitive material, therefore the dry film layer 204 may serve as a photoresist layer. As shown in FIGS. 3 a and 3 b, a lithography process is performed to remove a portion of the dry film layer 204 thereby patterning the dry film layer 204 into dry film patterns 204 a. In one embodiment, the lithography process may include alignment, exposing, and developing the dry film layer 204. Next, a curing process may be performed to fully cure the dry film patterns 204 a below 75° C. In one embodiment, the dry film patterns 204 a respectively cover each of the lens sets. The dry film patterns 204 a have a protection function for the underlying lens elements 202 a. In one embodiment, the dry film layer 204 is processed below 75° C. for the steps of lamination, exposure, development, and so forth. The dry film layer 204 is not flowable below 75° C., therefore the individual lens set can be covered with a solidified dry film pattern 204 a without being contaminated by a fluid dry film materials or other particles and impurities.
Next, the wafer-level lens sets covered with dry film patterns 204 a are separated by a sawing process along first spacer element 203 b and second spacer element 203 a. For example, wafer-level lens sets are divided along the scribe line, dotted line as shown in FIG. 3 b. In one embodiment, the first wafer 200 b with lens elements 202 b thereon and the second wafer 200 a with lens elements 202 b thereon are divided into individual lens sets. FIG. 4 illustrates one of the individual lens sets. The lens set as shown in FIG. 4 has first lens elements 202 b on two sides of the first wafer 200 b and second lens elements 202 a on two sides of the second wafer 200 a. Also, the dry film pattern 204 a faces and overlies the second lens elements 202 a of the lens set.
Next, referring to FIG. 5, a mounting process may be performed, by placing and pressing an image sensor device chip 210, having a plurality of solder balls 216 on a bottom surface of the image sensor device chip 210 on a carrier 213. In one embodiment, the carrier 213 may be a thermal tape comprising a flexible film 212 and a glue 214 thereon to fix the image sensor device chip 210. In one embodiment, the image sensor device chip 210 may comprise complementary metal-oxide-semiconductor (CMOS) devices or charge-coupled devices (CCDs).
Next, referring to FIG. 6, a dispensing process is performed to apply an adhesive 220 to a top surface 218 of the image sensor device chip 210 for bonding of the lens set as shown in FIG. 4. In one embodiment, the adhesive 220 may comprise resin, epoxy adhesive polymer.
Next, referring to FIG. 7, the lens set may be bonded onto the top surface 218 of the image sensor device chip 210, by placing and pressing the lens set on the image sensor device chip 210, centrally.
Next, referring to FIG. 8, a protective film 230 is formed covering the lens set. The formation of the protective film 230 may comprise performing a coating process, such as a spray coating process, to coat a metal material entirely over the lens set and the dry film pattern 204 a to form a metal layer 222. In one embodiment, the metal layer 222 may comprise Al, Cu or the like (Ag, Iron coating). The metal layer 222 may serve as an electromagnetic interference (EMI) shield to provide an electromagnetic interference (EMI) shielding function for the image sensor device chip 210. Next, another coating process such as a spray coating process is performed to coat a first light shielding material covering the metal layer 222 to form a light shielding layer 224. In one embodiment, the light shielding layer 224 may comprise a black paint to prevent internal reflections. In one embodiment, the protective film 230, comprising the metal layer 222 and the light shielding layer 224, has a protection function for the lens set.
Next, referring to FIG. 9, a laser cutting process is performed to cut a portion of the metal layer 222, the light shielding layer 224 and the dry film pattern 204 a. The remainder the dry film pattern 204 a over the lens set is dipped in a solution containing an organic solvent such as acetone. Next, the dry film pattern 204 a may be removed and stripped by oscillating in the solution containing the organic solvent. In this step, the metal layer 222, the light shielding layer 224 over the dry film pattern 204 a may simultaneously be taken out. Moreover, Oscillation of the solution facilitates removal efficiency of the dry film pattern 204 a, a portion of the metal layer 222 and the light shielding layer 224 over the lens element 202 a. After dry film pattern 204 a is removed by the solution containing the organic solvent, no residue will be left inside of lens set.
Alternatively, a cleaning process may be performed to remove residue of the dry film pattern 204 a, the metal layer 222 and the light shielding layer 224 over the lens set.
As shown in FIG. 9, the metal layer 222 and the light shielding layer 224 shield the camera module, except for the solder balls 216 and the aperture of the lens set. Next, the carrier 213 as shown in FIG. 8 is torn off from the image sensor device chip 210. Therefore, the description of fabrication of one exemplary embodiment of a camera module of the invention is completed.
One exemplary embodiment of a method for fabricating a camera module is provided. The method for fabricating the camera module utilizes a dry film as a protection film to prevent an aperture of a lens set from being covered by coating materials such as an electromagnetic interference (EMI) shielding material or a light shielding material applied during subsequent processes. The dry film layer is formed on the lens set in by a wafer-level lithography process before dividing the wafer level lens sets into individual lens sets. Therefore, the process using the dry film layer in wafer level has high throughput. Because dry film layer is formed by the wafer level lithography process, dry film patterns can be located exactly on lens sets by an alignment step of the wafer level lithography process. Also, the dry film layer has good dimension control ability. Moreover, during the step of forming lens set, the dry film patterns for the lens sets may be easily removed without additional process steps.
While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

Claims

1. A method for fabricating a camera module, comprising:

providing a plurality of lens sets;

forming a dry film layer on the plurality of lens sets;

patterning the dry film layer to form a plurality of dry film patterns respectively attaching to a plurality of lens sets;

separating the plurality of lens sets;

bonding a lens set separated from the plurality of lens sets to an image sensor device chip; and

removing the dry film pattern on the lens set.

2. The method for fabricating a camera module as claimed in claim 1, further comprising:

forming a protective film on the lens set.

3. The method for fabricating a camera module as claimed in claim 2, wherein forming the protective film comprises:

forming a metal layer on the dry film pattern; and

forming a light shielding layer on the metal layer.

4. The method for fabricating a camera module as claimed in claim 1, wherein removing the dry film pattern further comprises:

cutting the dry film pattern by a laser process;

dipping the dry film pattern by an organic solvent; and

oscillating the dry film pattern.

5. The method for fabricating a camera module as claimed in claim 4, wherein the organic solvent comprises acetone.

6. The method for fabricating a camera module as claimed in claim 1, further comprising cleaning the lens set after removing the dry film pattern.

7. The method for fabricating a camera module as claimed in claim 1, wherein providing the plurality of lens sets further comprises:

providing a first wafer having a plurality of first lens elements thereon; and

forming a first spacer element on the first wafer for isolating the first lens elements each other.

8. The method for fabricating a camera module as claimed in claim 7, wherein separating the plurality of lens sets further comprising dividing the first wafer along the first spacer element by a sawing process.

9. The method for fabricating a camera module as claimed in claim 7, wherein forming the dry film layer comprising laminating a photosensitive material layer on the first spacer element.

10. The method for fabricating a camera module as claimed in claim 7, further comprising:

bonding a second wafer to the first wafer, wherein the second wafer has a plurality of second lens elements aligning to the plurality of first lens elements and a second spacer element for isolating the second lens elements each other.

11. The method for fabricating a camera module as claimed in claim 9, wherein separating the plurality of lens sets further comprising dividing the first wafer and the second wafer along the first spacer element and the second spacer element by a sawing process.

12. The method for fabricating a camera module as claimed in claim 10, wherein forming the dry film layer comprising laminating a photosensitive material layer on the first spacer element.

13. The method for fabricating a camera module as claimed in claim 1, wherein patterning the dry film layer further comprises:

exposing the dry film layer;

developing the dry film layer to form the dry film patterns; and

baking the dry film patterns under a temperature below 75° C.

14. The method for fabricating a camera module as claimed in claim 1 further comprising:

applying an adhesive on the image sensor device chip to bond the lens set.

15. A method for fabricating a camera module, comprising:

providing a first wafer having a plurality of first lens elements thereon;

forming a first spacer element on the first wafer for isolating the first lens elements each other;

forming a dry film layer on the first spacer element;

separating the plurality of lens sets;

removing the dry film pattern on the lens set.

16. A method for fabricating a camera module, comprising:

providing a first wafer having a plurality of first lens elements thereon;

bonding a second wafer having a plurality of second lens elements to the first spacer element, wherein the plurality of second lens elements aligns to the plurality of first lens elements;

forming a second spacer element on the second wafer for isolating the second lens elements each other;

forming a dry film layer on the second spacer element;

separating the plurality of lens sets;

removing the dry film pattern on the lens set.