TWI453881B - Package structure and method of forming same - Google Patents

Description

Package structure and its manufacturing method

The present invention relates to a package structure and a method of fabricating the same, and more particularly to a package structure having a high density of input/output terminals and a method of fabricating the same.

As the packaging technology of semiconductor wafers has advanced, the size of electronic products has become thinner and lighter, and the demand for high-performance chips has increased. The number of input/output (I/O) terminals of high-efficiency chips has also become more and more popular. The more the spacing between the input/output (I/O) terminals, the smaller the metal bumps have to be, and the more difficult the die bonding is.

Referring to Figures 1A, 1B and 1B', there is shown a cross-sectional view of a conventional wafer bonding process, wherein the 1B' diagram is another example of Figure 1B.

As shown in FIG. 1A, the first wafer 11 and the second wafer 12 are provided with high efficiency, and the surface has a plurality of first electrical contacts 111 and second electrical contacts 121, respectively, and each of the second electrical contacts A metal bump 13 is formed on the dot 121.

As shown in FIGS. 1B and 1B', the wafer bonding process is started, that is, the metal bumps 13 are correspondingly bonded to the second electrical contacts 121, but the first electrical contacts 111 and the second electrical regions are The spacing between the contacts 121 is narrow, so even if there is only a slight deviation in the alignment, it is possible to form a dummy solder joint or the solder joint is broken by the stress concentration, causing a problem of reliability, such as FIG. 1B. As shown; or, the solder joints are misaligned, resulting in erroneous bonding results, as shown in Figure 1B'.

Therefore, how to avoid the various problems in the above-mentioned prior art, to solve the alignment problem at the time of wafer bonding, and to improve the reliability of the package structure has become a problem to be solved at present.

In view of the above-mentioned prior art, the present invention provides a package structure comprising: a first substrate having a plurality of first pads; a second substrate having a plurality of second pads; and a first conductive element Correspondingly connecting each of the second pads and each of the first pads, and a planar projection width of the first conductive element is smaller than a planar projection width of the first pad.

The present invention further provides another package structure, comprising: a first substrate having a plurality of first pads and a plurality of first electrical contacts; and a second substrate having a plurality of second pads and a plurality of second electrical contacts a first conductive element correspondingly connecting each of the second pads and each of the first pads; and a second conductive element correspondingly connecting the first electrical contacts and each of the second electrical contacts Wherein the first conductive element is greater than the second conductive element.

The invention provides a method for manufacturing a package structure, comprising: providing a first substrate having a plurality of first pads and a second substrate having a plurality of second pads, wherein each of the second pads has a first conductive element; The planar projection width of the first conductive component is smaller than the planar projection width of the first bonding pad; and the second bonding pads are electrically connected to the first bonding pads by the first conductive component.

The invention provides a method for fabricating another package structure, comprising: providing a first substrate having a plurality of first pads and a first electrical contact; and a second substrate having a plurality of second pads and a second electrical contact a substrate, and each of the second pads has a first conductive element, each of the first electrical contacts or the second electrical contacts has a second conductive element; connecting the first substrate and the second substrate, only The first conductive element on the second bonding pad contacts the first bonding pad; reflowing the first conductive element to connect the first conductive element to the first bonding pad, and the first conductive element provides a pulling force The first substrate is opposite to the second substrate; and the first electrical contact and the second electrical contact are connected by the second conductive component to electrically connect the first substrate to the second substrate .

It can be seen from the above that, because the invention is skillfully designed on the two substrates to be joined, the solder pads and their corresponding conductive elements are designed to be automatically aligned by the force of the conductive elements and the pads within a reasonable deviation range. By correcting the position, reducing the offset of the joint alignment, and improving the reliability of the package structure, high-precision bonding can be realized by using a low-precision bonding machine to reduce the cost of equipment.

The other embodiments of the present invention will be readily understood by those skilled in the art from this disclosure.

It is to be understood that the structure, the proportions, the size, and the like of the present invention are intended to be used in conjunction with the disclosure of the specification, and are not intended to limit the invention. The conditions are limited, so it is not technically meaningful. Any modification of the structure, change of the proportional relationship or adjustment of the size should remain in this book without affecting the effects and the objectives that can be achieved by the present invention. The technical content disclosed in the invention can be covered. In the meantime, the terms "upper", "flat", "convex", "top", "concave" and "one" as used in this specification are for convenience only and are not intended to be limiting. The scope of the invention can be implemented, and the change or adjustment of the relative relationship is also considered to be within the scope of the invention.

2A to 2D are cross-sectional views showing a package structure and a method of manufacturing the same according to the present invention, wherein the 2A' to 2D' drawings are partial top views of the 2A to 2D drawings, respectively, and the 2A" figure is the 2Ath drawing. A top view of a substrate, 2A-1, 2A-2, 2A-3, and 2A-4 are different embodiments of FIG. 2A.

First, as shown in FIGS. 2A and 2A', a first substrate 21 and a second substrate 22 are provided. The first substrate 21 has a plurality of first pads 211, a plurality of first electrical contacts 212, and is formed in the first substrate a second conductive member 24 on the second substrate 22, the second substrate 22 has a plurality of second pads 221, a plurality of second electrical contacts 222, and a first conductive layer formed on the second pad 221 The planar projection width D of the portion of the first conductive member 23 connected to the second pad 221 is smaller than the planar projection width L of the first pad 211, and the planar projection width of the first conductive member 23 is greater than The planar projection width of the second conductive component 24; wherein the first conductive component 23 and the second conductive component 24 can be solder balls, and the first substrate 21 and the second substrate 22 can be semiconductor wafers and semiconductor wafers, respectively. The width of the first conductive element 23 is preferably greater than the width of the second conductive element 24, and the melting point of the first conductive element 23 is preferably greater than or equal to the second conductive element. The melting point of 24.

In this embodiment, the first conductive element 23 and the second conductive element 24 are lead-free solder; in other embodiments, the first conductive element 23 may be lead-free solder, and the second conductive element 24 may have a layer of lead-free solder. a solder bump and a metal bump of a layer of copper conductive pillars thereon, and a melting point of the lead-free solder layer of the second conductive component 24 is preferably greater than or equal to a melting point of the first conductive component 23; and then, a preliminary alignment step is performed The first conductive element 23 contacts the first pad 211 of the first substrate 21. In this case, the first conductive element 23 does not undergo a reflow process, when the precision of the machine is low. The second conductive element 24 in the middle cannot be accurately aligned with the second electrical contact 222. At this time, the first substrate 21 and the second substrate 22 are not completely aligned.

2A' is a plan view of the second pad 211 in the region of the first pad 211, and the first pad 211 further has a positioning mark 2110. In the embodiment, the first pad 211 is made of a metal material, and may be a single layer or a plurality of metal alloy structures such as nickel, nickel/gold, copper, aluminum, tin/silver, tin/lead, tin/silver/copper. The first pad 211 may be formed by electroplating, electroless plating, sputtering, printing, or the like. The positioning mark 2110 is a cross-shaped notch disposed in the first pad 211, and the positioning mark 2110 is also It may be a dielectric layer material or a metal layer different from the first pad 211 for use as a positioning when the first substrate 21 and the second substrate 22 are joined. In addition, as shown in FIG. 2A, the first substrate 21 is a top view of the first substrate 21, and the first pad 211 is distributed at a corner of the first substrate 21. In this embodiment, the first pad 211 is respectively disposed at four corners of the first substrate 21, so that when the first substrate 21 and the second substrate 22 are offset by an XY axis or an angular rotation offset, the subsequent automatic alignment can be performed to provide the first The substrate 21 and the second substrate 22 are offset from each other, and the second conductive elements 24 are matrix-arranged at the center of the first substrate 21. In other embodiments (not shown), the first A substrate 21 and a second substrate 22 are wafers, and a plurality of wafer units are disposed in the wafer setting area, and the pads are disposed in the non-wafer setting area of the wafer.

Next, as shown in FIGS. 2B to 2D and 2B' to 2D', the first conductive member 23 is melted by reflow or heat treatment, and the first conductive member 23 is gradually melted into a liquid, and is connected to the first When the pad 211 is soldered, the first conductive element 23 gradually covers the entire first pad 211 due to the wetting of the first conductive element 23 and the first pad 211, as shown in FIG. 2C. Then, as shown in FIG. 2D, the first conductive element 23 entirely covers the first pad 211. Due to the cohesive force of the first conductive element 23, a pulling force is provided, and the first substrate 21 and the second substrate are driven. The substrates 22 are horizontally moved relative to each other until they are aligned with each other, thereby pulling back the position where the XY axis offset or the angular rotation of the first substrate 21 and the second substrate 22 are originally pulled back to the second conductive element 24 to reach a predetermined joint. The position of the first conductive element 23 is lowered by melting, so that the second conductive element 24 is aligned and correspondingly connected to the second electrical contact 222, thereby completing the self-alignment of the two substrates. With the joint, it becomes a package structure.

It is to be noted that the implementation of the present invention may also change the position of the first conductive element 23 and the second conductive element 24, as shown in FIG. 2A-1, in addition to the aspect of FIG. 2A; or, the second The substrate 22 may have a plurality of micro-electromechanical (MEMS) devices 25 as shown in FIG. 2A-2. Alternatively, the first substrate 21 may be formed with a plurality of through vias 210 and a plurality of protrusions 213 for each of the first pads. The pad 211 is located on the top surface of each of the protrusions 213, and the first substrate 21 is provided with a semiconductor wafer 26 that covers the through hole 210 and is electrically connected to the first substrate 21, and the second substrate 22 is The transparent material is formed as shown in FIG. 2A-3; or the first substrate 21 may be formed with a plurality of recesses 214, so that the first pads 211 are disposed on the recesses 214, and thus the first After the substrate 21 and the second substrate 22 are aligned, the height of the first conductive element 23 is lowered by melting, and the height between the first substrate 21 and the second substrate 22 after reflowing is not the height of the original reflow soldering. In contrast, the sinking is about 8% to 75%, so that the second conductive element 24 is aligned and correspondingly connected to the second electrical contact 222, and finally two Self-alignment plate (self-align) engages with the recessed portion to increase the accuracy of the self-aligned structure and reduce the overall volume of the package, as shown on FIG. 2A-4.

In addition, FIG. 2A is a top view of the first pad 211 and the first conductive element 23, where the first pad 211 is further included with a positioning mark 2110, and the positioning mark 2110 can be presented. a cross-shaped notch, but the positioning mark 2110 may also have an L-shaped, circular, rectangular or pentagonal notch, as shown in FIGS. 3A to 3D; and the second bonding pad 221 may be rectangular, octagonal, or circular. The shape of the shape or the length of the capsule is as shown in Figures 4A to 4D. Of course, the second pad 221 may also have an elliptical shape (not shown).

In summary, the present invention is based on the two substrates to be joined, and the solder pads and their corresponding conductive elements are skillfully designed to be within a reasonable range of deviation, by the conductive elements and soldering. The force of the pad automatically aligns and corrects the position (translating or rotating), reduces the offset of the joint alignment, and improves the reliability of the package structure, thereby enabling high-precision bonding using a low-precision bonding machine. Reduce equipment costs.

The above embodiments are intended to illustrate the principles of the invention and its effects, and are not intended to limit the invention. Any of the above-described embodiments may be modified by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be as set forth in the appended claims.

11. . . First wafer

111. . . First electrical contact

12. . . Second chip

121. . . Second electrical contact

13. . . Metal bump

twenty one. . . First substrate

210. . . Through hole

211‧‧‧First pad

2110‧‧‧ Positioning Mark

213‧‧‧ convex

214‧‧‧ recess

212‧‧‧First electrical contact

22‧‧‧second substrate

221‧‧‧Second pad

222‧‧‧Second electrical contacts

23‧‧‧First conductive element

24‧‧‧Second conductive element

25‧‧‧Microelectromechanical components

26‧‧‧Semiconductor wafer

D, L‧‧‧ Planar projection width

1A, 1B, and 1B' are cross-sectional views showing a conventional wafer bonding method, wherein the 1B' diagram is another example of FIG. 1B;

2A to 2D are cross-sectional views showing a package structure and a method of manufacturing the same according to the present invention, wherein the 2A' to 2D' drawings are partial top views of the 2A to 2D drawings, respectively, and the 2A" figure is the first substrate of the 2Ath drawing. In the top view, the 2A-1, 2A-2, 2A-3, and 2A-4 diagrams are different embodiments of FIG. 2A;

3A to 3D are different embodiments of the first pad of the package structure of the present invention;

4A through 4D are different embodiments of the second pad of the package structure of the present invention.

twenty one. . . First substrate

211. . . First pad

2110. . . Positioning mark

212. . . First electrical contact

twenty two. . . Second substrate

221. . . Second pad

222. . . Second electrical contact

twenty three. . . First conductive element

twenty four. . . Second conductive element

Claims (25)

A package structure includes: a first substrate having a plurality of first pads; a second substrate having a plurality of second pads and microelectromechanical components; and a first conductive component correspondingly connecting the second pads And each of the first pads, and a planar projection width of the first conductive element is smaller than a planar projection width of the first pad. A package structure includes: a first substrate having a plurality of first pads and a plurality of first electrical contacts; and a second substrate having a plurality of second pads and a plurality of second electrical contacts; the first conductive And the second conductive pad is connected to each of the first electrical contact and each of the second electrical contacts, wherein the first A conductive element is greater than the second conductive element, and the second conductive element has a melting point greater than a melting point of the first conductive element. The package structure of claim 1, wherein the first substrate has a plurality of first electrical contacts and a second conductive component formed on the first electrical contact, the second substrate And having a plurality of second electrical contacts, wherein each of the first electrical contacts is electrically connected to each of the second electrical contacts by the second conductive component. The package structure of claim 1, wherein the first substrate is formed with a plurality of first electrical contacts, and the second substrate is formed with a plurality of second electrical contacts and formed on the second substrate The second conductive component on the two electrical contacts is such that each of the second electrical contacts is electrically connected to each of the first electrical contacts by the second conductive component. The package structure of claim 2, wherein the planar projection width of the first conductive element is smaller than a planar projection width of the first pad. The package structure of claim 1 or 2, wherein the first conductive element is a solder bump. The package structure of claim 2, 3 or 4, wherein the second conductive element is a solder bump. The package structure according to claim 1 or 2, wherein the first substrate is a semiconductor wafer, a semiconductor wafer, a glass substrate or a package substrate, and the second substrate is a semiconductor wafer or a package substrate. The package structure of claim 1 or 2, wherein the second pad is rectangular, octagonal, circular, elongated, or elliptical. The package structure of claim 1 or 2, wherein the first pad further comprises a positioning mark. The package structure of claim 10, wherein the positioning mark is an L-shaped, circular, polygonal or cross-shaped notch. The package structure as described in claim 1 or 2, wherein The first substrate is formed with a plurality of through holes and a plurality of protrusions, wherein each of the first pads is located on a top surface of each of the protrusions, and the first substrate is provided with a cover and electrically connected A semiconductor wafer connected to the first substrate. The package structure of claim 1 or 2, wherein the first substrate is formed with a plurality of recesses so that each of the first pads is disposed on each of the recesses. A method for fabricating a package structure includes: providing a first substrate having a plurality of first pads and a second substrate having a plurality of second pads and microelectromechanical elements, wherein each of the second pads has a first conductive element; The planar projection width of the first conductive component is smaller than the planar projection width of the first bonding pad; and the second bonding pads are electrically connected to the first bonding pads by the first conductive component. The method of fabricating a package structure according to claim 14, wherein the first conductive element is a solder ball. The method of manufacturing the package structure of claim 14, wherein the first substrate has a plurality of first electrical contacts and a second conductive component formed on the first electrical contact, the first The second substrate has a plurality of second electrical contacts, and the first electrical contacts are electrically connected to the second electrical contacts by the second conductive elements. The method of manufacturing a package structure according to claim 14, wherein the first substrate is formed with a plurality of first electrical contacts, and the second substrate is formed with a plurality of second electrical contacts and formed on the second substrate The second electricity The second conductive component on the contact is electrically connected to each of the first electrical contacts by the second conductive component. The method of fabricating a package structure according to claim 16 or 17, wherein the second conductive element is a solder ball. The method of manufacturing a package structure according to claim 14, wherein the second pad is rectangular, octagonal, circular, elongated, or elliptical. The method of manufacturing a package structure according to claim 14, wherein the first pad further comprises an alignment mark. The method of manufacturing a package structure according to claim 20, wherein the positioning mark is an L-shaped, circular, polygonal or cross-shaped notch. A method for fabricating a package structure includes: providing a first substrate having a plurality of first pads and first electrical contacts; and a second substrate having a plurality of second pads and second electrical contacts, and The second conductive pad has a first conductive element, and each of the first electrical contact or the second electrical contact has a second conductive component, and a melting point of the second conductive component is greater than a melting point of the first conductive component; Connecting the first substrate and the second substrate, only the first conductive element on the second bonding pad contacts the first bonding pad; reflowing the first conductive element to connect the first conductive element to the first bonding pad, Providing a pulling force to move the first substrate and the second substrate relative to each other; and connecting the first electrical contact and the second by the second conductive element Electrical contacts are electrically connected to the second substrate. The method of fabricating a package structure according to claim 22, wherein a planar projection width of the first conductive element is smaller than a planar projection width of the first pad. The method of fabricating a package structure according to claim 14 or claim 22, wherein the first substrate is formed with a plurality of recesses so that each of the first pads is disposed on each of the recesses. The method of fabricating a package structure according to claim 22, wherein a plane projection width of the first conductive element is greater than a plane projection width of the second conductive element.