Semiconductor package and fabrication method thereof

Abstract

A semiconductor package and a fabrication method thereof are disclosed. The fabrication method includes the steps of providing a semiconductor chip having an active surface and a non-active surface opposing to the active surface, roughening a peripheral portion of the non-active surface so as to divide the non-active surface into the peripheral portion formed with a roughened structure and a non-roughened central portion, mounting the semiconductor chip on a chip carrier via a plurality of solder bumps formed on the active surface, forming an encapsulant on the chip carrier to encapsulate the semiconductor chip. The roughened structure formed on the peripheral portion of the non-active surface of the semiconductor chip can reinforce the bonding between the semiconductor chip and the encapsulant, and the non-roughened central portion of the non-active surface of the semiconductor chip can maintain the structural strength of the semiconductor chip.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reading the following detailed description of the preferred embodiments, with reference made to the accompanying drawings, wherein:

FIG. 1 (PRIOR ART) is a cross-sectional view of a conventional flip-chip semiconductor package;

FIGS. 2A to 2C are schematic diagrams showing a semiconductor package and a fabrication method thereof in accordance with the present invention; and

FIGS. 3 to 5 are top views of a semiconductor chip in accordance with other embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of a semiconductor packages and a fabrication method thereof as proposed in the present invention are described as follows with reference to FIGS. 2 to 5. It should be understood that the drawings are simplified schematic diagrams only showing the elements relevant to the present invention, and the layout of elements could be more complicated in practical implementation.

FIGS. 2A to 2C show a semiconductor package and a fabrication method thereof in accordance with the present invention.

As shown in FIGS. 2A and 2B, wherein FIG. 2B is a cross-sectional view of FIG. 2A taken along line 2B-2B, a semiconductor package of the present invention comprises a semiconductor chip 20. The semiconductor chip 20 has an active surface 201 and a non-active surface 202 opposing to the active surface 201. A roughened structure 200 is formed on a peripheral portion of the non-active surface 202 of the semiconductor chip 20, such that the non-active surface 202 is divided into a non-roughened central portion, and the peripheral portion formed with the roughened structure 200.

The roughened structure 200 formed on the peripheral portion of the non-active surface 202 of the semiconductor chip 20 is primarily located at the corners of the semiconductor chip 20. The roughened structure 200 extends for at least one third of a distance from the corner of the non-active surface 202 of the semiconductor chip 20 to a center of the non-active surface 202 of the semiconductor chip 20 (where there is no deformation at the center of the semiconductor chip 20), that is, one third of a distance to neutral point (DNP). The roughened structure 200 formed on the non-active surface 202 of the semiconductor chip 20 reinforces the bonding between the semiconductor chip 20 and an encapsulant to be subsequently formed thereon. The non-roughened central portion of the non-active surface 202 of the semiconductor chip 20 maintains the structural strength of the semiconductor chip 20. The roughened structure 200 is generally formed by a roughening process using laser with a wavelength less than 0.5 μm, plasma, or chemical etching. The depth of the roughened structure 200 is preferably in the range of 0.5 to 5 μm, and more preferably 2 μm.

In this embodiment, the roughened structure 200 comprises discrete portions formed at the four corners of the non-active surface 202 of the semiconductor chip 20 respectively. The roughened structure 200 extends for one third of a distance from the corner to the center of the non-active surface 202 of the semiconductor chip 20, and the central portion, which is not roughened, extends outwardly from the center of the non-active surface 202 of the semiconductor chip 20 for two thirds of the distance to neutral point (DNP).

Prior to formation of the roughened structure 200, the semiconductor chip 20 can be polished to reinforce surface strength thereof, and then the corners of the non-active surface 202 of the semiconductor chip 20 can be roughened to form the roughened structure 200.

Referring to FIG. 2C, the semiconductor chip 20 is mounted on a chip carrier 22 via a plurality of solder bumps 21 formed on the active surface 201 of the semiconductor chip 20, and an encapsulant 23 is formed on the chip carrier 22 to encapsulate the semiconductor chip 20. Thereby, a semiconductor package is obtained.

The chip carrier 22 is, for example, a ball grid array (BGA) substrate. A plurality of solder balls 24 are implanted on a surface of the substrate other than the surface for mounting the semiconductor chip 20, and are used to electrically connect the semiconductor chip 20 to an external device. Alternatively, the chip carrier 22 can be a lead frame.

FIGS. 3 to 5 are top views of a semiconductor chip 20 in accordance with different embodiments of the present invention. As shown in FIGS. 3 to 5, the non-roughened central portion of the non-active surface of the semiconductor chip 20 is shaped as a circle (FIG. 3), a rectangle (FIG. 4), or a polygon (FIG. 5). The roughened structure 200 formed on the peripheral portion of the non-active surface of the semiconductor chip 20 extends for at least one third of a distance from the corner to the center of the non-active surface of the semiconductor chip 20, and extends on all edges of the non-active surface of the semiconductor chip 20. With the non-active surface of the semiconductor chip 20 comprising both the peripheral portion with the roughened structure 200 and the non-roughened central portion, the bonding between the semiconductor chip 20 and the encapsulant that encapsulates the semiconductor chip 20 can be enhanced by the roughened structure 200, and also the structural strength of the semiconductor chip 20 can be maintained by the non-roughened central portion. Accordingly, the present invention is suitable for packaging a large semiconductor chip, without having delamination on the corners of the semiconductor chip and without having cracks of the semiconductor chip caused by roughening the entire chip surface in the prior art.

The aforesaid embodiments merely serve as the preferred embodiments of the present invention. They should not be construed as to limit the scope of the present invention in any way. Hence, any other changes can actually be made in the present invention. It will be apparent to those skilled in the art that all equivalent modifications or changes made, without departing from the spirit and the technical concepts disclosed by the present invention, should fall within the scope of the appended claims.

Claims

1. A semiconductor package, comprising: a chip carrier;a semiconductor chip having an active surface and a non-active surface opposing to the active surface, wherein the semiconductor chip is mounted on the chip carrier via a plurality of solder bumps formed on the active surface of the semiconductor chip, and wherein the non-active surface of the semiconductor chip comprises a peripheral portion formed with a roughened structure, and a non-roughened central portion; andan encapsulant formed on the chip carrier to encapsulate the semiconductor chip.

2. The semiconductor package of claim 1, wherein the roughened structure is formed on at least one corner of the non-active surface of the semiconductor chip.

3. The semiconductor package of claim 2, wherein the roughened structure extends for at least one third of a distance from the corner to a center of the non-active surface of the semiconductor chip.

4. The semiconductor package of claim 2, wherein the roughened structure is formed by one selected from a group consisting of laser with a wavelength less than 0.5 μm, plasma, and chemical etching, and the roughened structure has a depth of 0.5 to 5 μm.

5. The semiconductor package of claim 2, wherein the roughened structure is formed at four corners of the non-active surface of the semiconductor chip.

6. The semiconductor package of claim 2, wherein the roughened structure comprises discrete portions formed at four corners of the non-active surface of the semiconductor chip respectively.

7. The semiconductor package of claim 2, wherein the semiconductor chip is polished to reinforce surface strength thereof, and the roughed structure is formed at the corner of the non-active surface of the polished semiconductor chip.

8. The semiconductor package of claim 2, wherein the chip carrier is one of a ball grid array (BGA) substrate and a lead frame.

9. The semiconductor package of claim 2, wherein the non-roughened central portion of the non-active surface of the semiconductor chip has a shape selected from a group consisting of a circle, a rectangle, and a polygon.

10. The semiconductor package of claim 2, wherein the roughened structure extends for at least one third of a distance from the corner to a center of the non-active surface of the semiconductor chip, and extends on all edges of the non-active surface of the semiconductor chip.

11. A fabrication method of a semiconductor package, comprising the steps of: providing a semiconductor chip having an active surface and a non-active surface opposing to the active surface;roughening a peripheral portion of the non-active surface of the semiconductor chip, so as to divide the non-active surface into the peripheral portion formed with a roughened structure, and a non-roughened central portion;mounting the semiconductor chip on a chip carrier via a plurality of solder bumps formed on the active surface of the semiconductor chip; andforming an encapsulant on the chip carrier to encapsulate the semiconductor chip.

12. The fabrication method of claim 11, wherein the roughened structure is formed on at least one corner of the non-active surface of the semiconductor chip.

13. The fabrication method of claim 12, wherein the roughened structure extends for at least one third of a distance from the corner to a center of the non-active surface of the semiconductor chip.

14. The fabrication method of claim 11, wherein the roughened structure is formed by one selected from a group consisting of laser with a wavelength less than 0.5 μm, plasma, and chemical etching, and the roughened structure has a depth of 0.5 to 5 μm.

15. The fabrication method of claim 11, wherein the roughened structure is formed at four corners of the non-active surface of the semiconductor chip.

16. The fabrication method of claim 11, wherein the roughened structure comprises discrete portions formed at four corners of the non-active surface of the semiconductor chip respectively.

17. The fabrication method of claim 11, wherein the semiconductor chip is polished to reinforce surface strength thereof, and then the corner of the non-active surface of the polished semiconductor chip is roughened to form the roughened structure.

18. The fabrication method of claim 11, wherein the chip carrier is one of a ball grid array (BGA) substrate and a lead frame.

19. The fabrication method of claim 11, wherein the non-roughened central portion of the non-active surface of the semiconductor chip has a shape selected from a group consisting of a circle, a rectangle, and a polygon.

20. The fabrication method of claim 11, wherein the roughened structure extends for at least one third of a distance from the corner to a center of the non-active surface of the semiconductor chip, and extends on all edges of the non-active surface of the semiconductor chip.