US20070075236A1

US20070075236A1 - Packaging method of a light-sensing semiconductor device and packaging structure thereof

Info

Publication number: US20070075236A1
Application number: US11/239,028
Authority: US
Inventors: Po-Hung Chen; Mao-Jung Chen
Original assignee: SIGURD MICROELECTRONICS CORP
Current assignee: SIGURD MICROELECTRONICS CORP
Priority date: 2005-09-30
Filing date: 2005-09-30
Publication date: 2007-04-05
Also published as: US7547571B2; US20080188031A1

Abstract

The present invention discloses a packaging method of a light-sensing semiconductor device and a packaging structure thereof, wherein a matrix of spacer walls is formed on a light-sensing wafer, which has multiple light-sensing chips, and the adhesive is directly applied to between two neighboring spacer walls on the non-light-sensing regions. Thus, when the light transparent cover is installed, there is no more adhesive dropping onto the light-sensing regions of the light-sensing chips. Further, when the light transparent cover is pressed to join with the spacer walls, with the trenches formed at the tops of the spacer walls, the adhesive will not overflow from the joint seams into the light-sensing regions.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a packaging method of a semiconductor device and a packaging structure thereof, particularly to a packaging method of a light-sensing semiconductor device and a packaging structure thereof, which can protect a light-sensing chip from the pollution by external particles.
2. Description of the Related Art
In a light-sensing semiconductor, the light-sensing region of the light-sensing chip is used to acquire images; thus, the quality of the light-sensing semiconductor correlates closely with the light-sensing chip. During the packaging process of the light-sensing chip, the chip is often polluted by particles; therefore, packaging is a critical process for the quality of the light-sensing semiconductor.
Refer to FIG. 1A and FIG. 1B section views schematically showing the steps of the conventional packaging method of a light-sensing semiconductor device. A light-sensing wafer 10 has multiple light-sensing chips 12, and each light-sensing chip 12 has a light-sensing region 14. A light transparent cover 16 has a matrix of spacer walls 18; an adhesive 20 is applied to between the spacer walls 18, as shown in FIG. 1A. Then, the light transparent cover 16 is flipped and put onto the light-sensing wafer 10, as shown in FIG. 1B. Thus, the light-sensing region 14, the spacer walls 18 and the light transparent cover 16 enclose an airtight space, which can protect the light-sensing region 14 of the light-sensing chip 12 from the pollution by external particles.
As the adhesive 20 has been applied to the light transparent cover 16 when the light transparent cover 16 is being flipped to put onto the light-sensing wafer 10, the adhesive 20 may drops onto the light-sensing region 14 of the light-sensing chip 12, which pollutes the light-sensing region 14 and influences the quality and yield. Further, as the light transparent cover 16 is flipped and then aligned to join with the light-sensing wafer 10, this conventional packaging method has the problem of alignment accuracy. Furthermore, during the press-joining step, if the adhesive is applied too much, the adhesive will overflow into the light-sensing region 14 and pollute the light-sensing chips 12. If the adhesive is applied too little, the sealing effect is poor.
Accordingly, the present invention proposes a packaging method of a semiconductor device and a packaging structure thereof to protect the light-sensing chip from the pollution by external particles.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a packaging method of a light-sensing semiconductor device and a packaging structure thereof, which can prevent the adhesive from dropping onto the light-sensing region during the fabrication process lest the light-sensing chip be polluted and so that the yield and quality of the light-sensing semiconductor can be promoted.
Another objective of the present invention is to provide a packaging method of a light-sensing semiconductor device and a packaging structure thereof, which provides an easy alignment method for the joining step to simplify the fabrication process and promote the alignment accuracy so that the inferior alignment between the light transparent cover and the wafer occurring in the conventional technology will be solved.
Further objective of the present invention is to provide a CSP (Chip Scale Package) packaging method of a light-sensing semiconductor device and a packaging structure thereof.
To achieve the abovementioned objectives, the packaging method of a light-sensing semiconductor device of the present invention comprises: providing a light-sensing wafer, wherein the wafer has multiple light-sensing chips, and each light-sensing chip has a light-sensing region and a non-light-sensing region; forming a buffer layer on the light-sensing wafer; removing a portion of the buffer layer to respectively form a spacer wall on the non-light-sensing region of each light-sensing chip; applying an adhesive to between the spacer walls; and affixing a light transparent cover to the spacer walls on the light-sensing wafer. Thereby, a airtight space, which is enclosed by the light-sensing region, the spacer walls and the light transparent cover, is formed, and it can protects the light-sensing region from the pollution by external particles.
The present invention also proposes a packaging structure of a light-sensing semiconductor device, which is fabricated according to the abovementioned packaging method and comprises: a light-sensing wafer, having multiple light-sensing chips, wherein each light-sensing chip has a light-sensing region and a non-light-sensing region; multiple spacer walls, respectively formed on the non-light-sensing regions, which encircle the light-sensing chips separately; an adhesive, disposed between two neighboring spacer walls on the non-light-sensing regions; and at least one light transparent cover, affixed to the spacer walls with the adhesive, and covering the light-sensing regions.
To enable the objectives, technical contents, characteristics, and accomplishments of the present invention to be more easily understood, the embodiments of the present invention is to be described below in detail in cooperation with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B are section views schematically showing the steps of the conventional packaging method of a light-sensing semiconductor device.
FIG. 2 is a section view schematically showing the packaging structure of a light-sensing semiconductor device according to the present invention.
FIG. 3A to FIG. 3D are section views schematically showing the steps of the packaging method according to one embodiment of the present invention.
FIG. 4A to FIG. 4E are section views schematically showing the steps of the packaging method according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a packaging method of a light-sensing semiconductor device and a packaging structure thereof, which provides a mechanism by which light can access the light-sensing chip inside the light-sensing semiconductor device and protects the light-sensing chip from the pollution by external particles.
Refer to FIG. 2 a diagram schematically showing the packaging structure of a light-sensing semiconductor device according to the present invention. This wafer-scale packaging structure of a light-sensing semiconductor device according to the present invention comprises: a light-sensing wafer 30, having multiple light-sensing chips 32, with each light-sensing chip 32 having a light-sensing region 34 and a non-light-sensing region 36; spacer walls 38, separately encircling the non-light-sensing regions 36 of the light-sensing chips 32; and a light transparent cover 40, affixed to the spacer walls 38 with an adhesive 42, such as a thermosetting glue or a UV glue, and covering the light-sensing regions 34, wherein the light transparent cover 40, the spacer walls 38 and the light-sensing regions 34 together form multiple airtight spaces. In the present invention, one identical light transparent cover 40 may cover either multiple light-sensing chips 32, as shown in FIG. 2, or only one light-sensing chip 32.
The abovementioned light transparent cover 40 may also be designed to filter out a light of a specific wavelength, such as a far-infrared ray.
Refer to from FIG. 3A to FIG. 3D for the packaging method of the present invention, which realizes the abovementioned packaging structure. Firstly, as shown in FIG. 3A, a light-sensing wafer 30 is provided, and the light-sensing wafer 30 has multiple light-sensing chips 32, and each light-sensing chip 32 has a light-sensing region 34 and a non-light-sensing region 36. A buffer layer 44 is formed on the light-sensing wafer 30, and the buffer layer may be made of a photoresist material.
Next, as shown in FIG. 3B, a portion of the buffer layer 44 is removed via an etching method, and the remaining buffer layer 44 forms a matrix of spacer walls 38, i.e. every non-light-sensing region 36, which is along the perimeter of each light-sensing chip 32, has a spacer wall 38.
Next, as shown in FIG. 3C, an adhesive 42 is applied to between two neighboring spacer walls 38 that are respectively on two neighboring non-light-sensing regions 36. Next, as shown in FIG. 3D, a light transparent cover 40 is affixed to those spacer walls 38 on the light-sensing wafer 30, and thus, the light-sensing regions 32, the spacer walls 38 and the light transparent cover 40 can form multiple airtight spaces to protect the light-sensing regions 34 of the light-sensing chips 32 from the pollution by external particles. Then, the packaging process is completed.
The light transparent cover 40 may also be affixed to the spacer walls 38 in a vacuum chamber, and airtight and evacuated spaces without residual gas are thus formed lest the thermal expansion of the residual gas influence the reliability of the sealed semiconductor devices during the succeeding high-temperature process.
The abovementioned light-sensing wafer 30 may also be cut by the light-sensing chip 32 in order to form multiple light-sensing semiconductor devices, wherein each light-sensing semiconductor device comprises: a light-sensing chip 32, a spacer wall 38, a light transparent cover 40 and an adhesive 42, which seals the aforementioned parts.
In the present invention, as the adhesive is directly applied to between two neighboring spacer walls on the non-light-sensing region, neither the problem of alignment accuracy nor the problem of the adhesive's dropping onto the light-sensing region will occur. Further, when the light transparent cover is pressed to join with the spacer walls, the adhesive is unlikely to overflow into the light-sensing regions.
To obtain a better cohering effect of the adhesive, the present invention further proposes another embodiment, which is shown in from FIG. 4A to FIG. 4E. As shown in FIG. 4B, trenches 46 are formed on the buffer layer 44, which has been formed on the light-sensing wafer 30 and is shown in FIG. 4A. Next, as shown in FIG. 4C, a portion of the buffer layer 44 is removed in order to form the spacer walls 38, wherein the tops of every two neighboring spacer walls 38 has one trench 46. Then, as shown in FIG. 4D, those trenches 46 function as the glue-leading channels where the applied adhesive 42 will gather, and the adhesive 42 is unlikely to flow out the matrix formed by those non-light-sensing regions 36. Therefore, as shown in FIG. 4E, when the light transparent cover 40 is pressed to join with to the spacer walls 38, the trenches 46 can prevent the adhesive 42 from overflowing onto the light-sensing region 34.
In summary, the present invention not only can obviously simplify the fabrication process but also can prevent the adhesive from dropping onto the light-sensing regions and polluting the light-sensing chips; thus, the quality and yield of the light-sensing semiconductor devices can be promoted. Further, the present invention also provides a CSP (Chip Scale Package) packaging method of a light-sensing semiconductor device and a packaging structure thereof.
Those embodiments disclosed above are only to clarify the present invention to enable the persons skilled in the art to understand, make and use the present invention; however, those are not intended to limit the scope of the present invention. Any equivalent modification and variation according to the spirit of the present invention disclosed herein is to be included within the scope of the present invention.

Claims

1. A packaging method of a light-sensing semiconductor device, comprising the following steps:

providing a light-sensing wafer, wherein said wafer has multiple light-sensing chips, and each said light-sensing chip has a light-sensing region;

forming a buffer layer on said light-sensing wafer;

removing a portion of said buffer layer, with the remaining said buffer layer respectively forming a spacer wall on a non-light-sensing region, which is disposed along the perimeter of each said light-sensing chip;

applying an adhesive to between neighboring said spacer walls on said non-light-sensing regions and; and

affixing a light transparent cover to said spacer walls via said adhesive, with said light-sensing regions, said spacer walls and said light transparent cover forming at least one airtight spaces.

2. The packaging method of a light-sensing semiconductor device according to claim 1, wherein said step of “removing a portion of said buffer layer” is implemented with an etching method.

3. The packaging method of a light-sensing semiconductor device according to claim 1, wherein before said step of forming said spacer walls, multiple trenches are formed on said buffer layer in order to respectively provide one common said trench for the tops of every two neighboring said spacer walls.

4. The packaging method of a light-sensing semiconductor device according to claim 1, wherein forming said trenches is implemented with an etching method.

5. The packaging method of a light-sensing semiconductor device according to claim 1, wherein said step of “affixing a light transparent cover to said spacer walls” is undertaken in a vacuum chamber, and said light-sensing regions, said spacer walls and said light transparent cover form at least one evacuated and airtight spaces.

6. The packaging method of a light-sensing semiconductor device according to claim 1, further comprising a cutting step, wherein said light-sensing wafer is divided by said light-sensing chip in order to form multiple light-sensing semiconductor devices.

7. A packaging structure of a light-sensing semiconductor device, comprising:

a light-sensing wafer, having multiple light-sensing chips, wherein each said light-sensing chip has a light-sensing region and a non-light-sensing region;

multiple spacer walls, separately encircling each said non-light-sensing region, which is around the perimeter of corresponding said light-sensing chip;

at least one adhesive, disposed between every two neighboring said spacer walls on said non-light-sensing regions; and

at least one light transparent cover, affixed to said spacer walls with said adhesive, and covering said light-sensing regions, with said light-sensing regions, said spacer walls and said light transparent cover forming at least one airtight spaces.

8. The packaging structure of a light-sensing semiconductor device according to claim 7, wherein one identical said light transparent cover may cover either multiple said light-sensing chips or only one said light-sensing chip.

9. The packaging structure of a light-sensing semiconductor device according to claim 7, wherein said adhesive is a thermosetting glue or a UV glue.

10. The packaging structure of a light-sensing semiconductor device according to claim 7, wherein multiple trenches are separately formed on the tops of every two neighboring said spacer walls, and said adhesive is filled into said trenches.

11. The packaging structure of a light-sensing semiconductor device according to claim 7, wherein said light transparent cover can filter out a light of a specific wavelength.

12. The packaging structure of a light-sensing semiconductor device according to claim 11, wherein said light transparent cover can filter out a far-infrared ray.

13. The packaging structure of a light-sensing semiconductor device according to claim 7, wherein said spacer wall is made of a photoresist material.

14. The packaging structure of a light-sensing semiconductor device according to claim 7, wherein said light-sensing wafer is further cut by said light-sensing chip in order to form multiple light-sensing semiconductor devices, wherein each said light-sensing semiconductor device comprises: one said light-sensing chip, one said spacer wall, one said light transparent cover and one said adhesive for sealing those said parts.