CN220106511U - Joint structure - Google Patents

Abstract

The utility model discloses a joint structure, which comprises: a bonding pad; a bonding layer over the bonding pad; and the buffer layer is positioned between the bonding pad and the bonding layer, wherein the bonding layer extends to the outer side wall of the buffer layer so as to electrically connect the bonding pad. According to the technical scheme, the buffer layer is arranged between the bonding layer and the bonding pad, so that at least the bonding force applied during bonding can be buffered, and the bonding success rate is increased.

Description

Joint structure

Technical Field

The present utility model relates to the field of semiconductor technology, and more particularly, to a bonding structure.

Background

Referring to fig. 1, in the HBI (Hybrid bond interconnection, hybrid bond interconnect) process, the SiOx (silicon oxide) 12 of the upper package 10 is bonded to the SiOx 22 of the lower package 20, and then heated to the bonding temperature to perform diffusion (diffusion) between the Cu (copper) pad 14 of the upper package 10 and the Cu pad 24 of the lower package 20, and the bonding surfaces of the SiOx 12 and the SiOx 22 are planarized by CMP (Chemical Mechanical Polishing ) to bond with Li Fande watts before the SiOx 12 and the SiOx 22 are bonded. CMP is costly and has the following bottlenecks: (1) After CMP, the requirements of meeting the requirements of the Ra (roughness) of the butt joint surfaces of SiOx 12 and SiOx 22 are less than 0.5nm, and the severe conditions lead to high manufacturing cost; (2) And the bonding force 60 applied during bonding may not be too great to avoid cracking 70 of SiOx 12 or SiOx 22.

In another prior art, referring to fig. 2A, the SiOx 22 of the lower package 20 is replaced with PI (polyimide) 25; or referring to fig. 2B, both SiOx 12 of upper package 10 and SiOx 22 of lower package 20 are replaced with PI 25. PI 25 softens and adheres directly with a temperature above the Tg (glass transition temperature) point and particles 30 between PI 25 (see fig. 2B) are covered by the softened PI 25, so that HBI bonding can be accomplished without CMP processing, as long as the bonding temperature is above the Tg point of PI 25. However, in the above-mentioned technique, referring to fig. 2B, since the Cu pad 14 is solid to Cu in the bonding portion of the Cu pad 24, if the particle 30 exists between the Cu pad 14 and the Cu pad 24, a large bonding force 60 is required to cover the particle 30 by the Cu pad 14 and the Cu pad 24 at the time of bonding, however, if the bonding force 60 is too large, the PI 25 may not support and cause the die 51, 52 to crack 80, and if the bonding force 60 is not increased, the bonding area of the Cu pad 14 and the Cu pad 24 may be affected by the separation of the particle 30 from the Cu pad 14 and the Cu pad 24, which is disadvantageous to the electrical property.

Disclosure of Invention

In view of the above, the present utility model provides a joining structure that can at least buffer a joining force applied at the time of joining, thereby increasing a joining success rate.

The technical scheme of the utility model is realized as follows:

according to an aspect of the present utility model, there is provided a joint structure comprising: a bonding pad; a bonding layer over the bonding pad; and the buffer layer is positioned between the bonding pad and the bonding layer, wherein the bonding layer extends to the outer side wall of the buffer layer so as to electrically connect the bonding pad.

In some embodiments, the buffer layer exposes a periphery of the pad.

In some embodiments, portions of the bonding layer have protrusions, and the buffer layer accommodates the protrusions of the bonding layer.

In some embodiments, the engagement structure further comprises particles that overlap the protrusions in a vertical direction.

In some embodiments, the bonding structure further includes a dielectric layer disposed laterally side-by-side with the bonding layer, the dielectric layer being of the same material as the buffer layer.

In some embodiments, the dielectric layer extends upward and beyond the bonding layer.

In some embodiments, the dielectric layer is separated from the buffer layer by a bonding layer.

In some embodiments, the bonding layer defines a space on an outer sidewall side of the buffer layer.

In some embodiments, the bonding layer is a first bonding layer, and the bonding structure further includes a second bonding layer over and bonded to the first bonding layer, wherein an edge of the second bonding layer is not aligned with an edge of the first bonding layer.

In some embodiments, the bonding layer also extends to the sidewalls of the dielectric layer.

In the above bonding structure, the buffer layer is arranged between the bonding layer and the bonding pad, so that the bonding force applied during bonding can be buffered, the bonding success rate is increased, and the problem that the bonding force channel cannot be supported by a part of the structure because a large bonding force is required during bonding of the solid bonding pad can be solved. In addition, the bonding layer can be flattened, so that CMP is not required, and the bonding process cost is effectively reduced.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present utility model, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Figure 1 is a schematic cross-sectional view of a prior art HBI structure.

FIGS. 2A and 2B are schematic cross-sectional views of two other HBI structures of the prior art

Fig. 3 is a schematic cross-sectional view of a joint structure according to one embodiment of the utility model.

Fig. 4 is a schematic cross-sectional view of a joint structure according to another embodiment of the present utility model.

Fig. 5 is a schematic cross-sectional view of a joint structure according to another embodiment of the utility model.

Fig. 6A to 6E are schematic cross-sectional views at various steps of forming a bonding structure according to an embodiment of the present utility model.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which are derived by a person skilled in the art based on the embodiments of the utility model, fall within the scope of protection of the utility model.

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of elements and arrangements will be described below to simplify the present disclosure. These are, of course, merely examples and are not intended to limit the utility model. For example, in the following description, forming a first component over or on a second component may include embodiments in which the first component and the second component are in direct contact, and may also include embodiments in which additional components are formed between the first component and the second component such that the first component and the second component may not be in direct contact. Moreover, the present utility model may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

In addition, the embodiments of the present utility model and the features in the embodiments may be combined with each other without collision. The utility model will be described in detail below with reference to the drawings in connection with embodiments.

Fig. 3 is a schematic cross-sectional view of a joint structure 100 according to one embodiment of the utility model. Referring to fig. 3, the bonding structure 100 includes a first pad (may also be referred to as a pad) 102, a first bonding layer (may also be referred to as a bonding layer) 104 located over the first pad 102, and a first buffer layer (may also be referred to as a buffer layer) 108 located between the first pad 102 and the first bonding layer 104. The first bonding layer 104 extends from the outer sidewall of the first buffer layer 108 to be electrically connected to the first pad 102, that is, the first bonding layer 104 may surround the outer sidewall 108s of the first buffer layer 108. The first bonding layer 104 may also extend over the upper surface of the first buffer layer 108. The material of the first bonding layer 104 may be a conductive material to electrically connect the first pad 102 with other structures through the first bonding layer 104.

In the above-described bonding structure 100, by providing the first buffer layer 108 between the first bonding layer 104 and the first pad 102, the bonding force applied at the time of bonding can be buffered, the bonding success rate can be increased, and the problem that the bonding force cannot be supported by the structure accommodating the solid pad due to the need for a larger bonding force at the time of bonding the solid pad can be solved, as described with reference to fig. 2B, when the SiOx 22, 24 is replaced with PI 25, the bonding force cannot be supported by PI 25 due to the need for a larger bonding force at the time of bonding the solid Cu pads 14, 24, and the problem that the die 51, 52 is broken can be solved. In addition, by providing the first bonding layer 104 to extend on the upper surface of the first buffer layer 108, the first bonding layer 104 can be made flat, and thus such first bonding layer 104 can be directly used for bonding with other structures without performing CMP, which can effectively reduce the bonding process cost.

In some embodiments, the first pads 102 are pads that are housed in the electronic device 180, i.e., the first pads 102 are pads of the electronic device 180. The electronic device 180 may be a die or any other suitable type of electronic device. In some embodiments, the material of the first buffer layer 108 is a less stiff material, e.g., the material of the first buffer layer 108 has a stiffness less than the stiffness of the first pad 102. In one embodiment, the material of the first buffer layer 108 is PI. Because PI is softer and has high pore-filling properties, it can be used as the first buffer layer 108 during bonding, providing a buffer during bonding. In some embodiments, the Tg point of the material of the first buffer layer 108 is below the bonding temperature during bonding of the first bonding layer 104, such that at the bonding temperature, the first buffer layer 108 softens to provide good buffering at the time of bonding. In other embodiments, other dielectric materials may be used for the first buffer layer 108.

With continued reference to fig. 3, the first buffer layer 108 is located over a central region of the first pad 102. The first buffer layer 108 exposes a periphery of the first pad 102. In addition, the bonding structure 100 may further include a first dielectric layer 122, where the first dielectric layer 122 is laterally disposed side by side with the first bonding layer 104. The sidewalls 122s of the first dielectric layer 122 may be misaligned with the edges 102e of the first pad 102 such that a portion of the surface of the electronic device 180 is also exposed between the first dielectric layer 122 and the first buffer layer 108.

In some embodiments, the material of the first dielectric layer 122 may be the same as the material of the first buffer layer 108. In embodiments where the first dielectric layer 122 is the same material as the first buffer layer 108, the first dielectric layer 122 may have the same characteristics as the first buffer layer 108 described above. For example, the material of the first dielectric layer 122 and the material of the first buffer layer 108 may both be PI. In some embodiments, the first dielectric layer 122 may be flush with the upper surface of the first bonding layer 104. In some embodiments, a portion of the upper surface of the first dielectric layer 122 may extend beyond the first bonding layer 104.

In some embodiments, the first bonding layer 104 and the first pad 102 may be different conductive materials. For example, the material of the first pad 102 is Al (aluminum), and the material of the first bonding layer 104 is Cu. In other embodiments, the materials of the first bonding layer 104 and the first pad 102 may also be the same conductive material.

The first bonding layer 104 may extend beyond the edge of the first pad 102 in the lateral direction. Specifically, the first bonding layer 104 extends from the upper surface and the outer sidewall 108s of the first buffer layer 108 to the exposed periphery of the first pad 102 and then to the sidewall 122s of the first dielectric layer 122. The first bonding layer 104 may further extend onto the upper surface of the first dielectric layer 122, and an edge of the first bonding layer 104 may be located on the upper surface of the first dielectric layer 122. Thus, the first bonding layer 104 may define a space 130, and the space 130 is located on the outer sidewall 108s side of the first buffer layer 108. The space 130 may surround the first buffer layer 108. The first dielectric layer 122 and the first buffer layer 108 may be separated by the first bonding layer 104 and the space 130.

The bonding structure 100 may include a plurality of first bonding pads 102, and a corresponding first buffer layer 108 and a first bonding layer 104 are disposed over each of the first bonding pads 102. The first bonding layer 104 on adjacent first pads 102 may be spaced apart at the upper surface of the first dielectric layer 122 to avoid shorting.

In some embodiments, the pitch (pitch) between adjacent first pads 102 may be less than 45 μm, where the pitch may refer to the distance between the centers of adjacent two first pads 102. As product development has not advanced to higher performance requirements, the number of I/os under the same area needs to be increased, and increasing the number of I/os may reduce the pitch of the bumps (e.g., C4 bumps) used for bonding, which affects the subsequent bump connection and is easy to generate bridging, resulting in short circuit. By employing the bonding structure 100 provided by the present utility model on the electronic device 180, the pitch between the first pads 102 can be reduced to less than 45 μm as compared to using the conventional bump, so that the I/O number of the electronic device 180 can be increased.

Fig. 4 is a schematic cross-sectional view of a joint structure 200 according to another embodiment of the utility model. Referring to fig. 4, the bonding structure 200 includes, in addition to the first pad 102, the first bonding layer 104, the first buffer layer 108, the first dielectric layer 122, and the like described above with reference to fig. 3, the bonding structure 200 further includes a second pad 202, a second bonding layer 204 located below the second pad 202, a second buffer layer 208 located between the second pad 202 and the second bonding layer 204, and a second dielectric layer 222 disposed laterally side by side with the second bonding layer 204 and above the first dielectric layer 122. The second pad 202 is housed in the electronic device 280. The relative structural configuration of the second pad 202, the second bonding layer 204, the second buffer layer 208, the second dielectric layer 222, and the electronic device 280 may be similar to the first pad 102, the first bonding layer 104, the first buffer layer 108, the first dielectric layer 122, and the electronic device 180 described above with reference to fig. 3, and thus similar detailed descriptions are omitted in the description with reference to fig. 4.

The materials of the first bonding layer 104 and the second bonding layer 204 may be the same and bonded to each other, and thus the interface between the first bonding layer 104 and the second bonding layer 204 is not shown in fig. 4. The materials of the first dielectric layer 122 and the second dielectric layer 222 may be the same and bonded to each other, and thus the interface between the first dielectric layer 122 and the second dielectric layer 222 is also not shown in fig. 4. And in the bonding structure 200, the first dielectric layer 122 and the second dielectric layer 222 may be formed as a single dielectric layer.

The second bonding layer 204 is over the first bonding layer 104 and bonded to the first bonding layer 104, and the second buffer layer 208 at least partially overlaps the first buffer layer 108 in a vertical direction. The first bonding pad 102 and the second bonding pad 202 may be electrically connected by the first bonding layer 104 and the second bonding layer 204. As shown at dashed line B1 in fig. 4, at least one side edge of the first bonding layer 104 and a corresponding edge of the second bonding layer 204 may be misaligned. The bonded first bonding layer 104 and second bonding layer 204 may together define a space 130'. The space 130' may surround the first buffer layer 108 and the second buffer layer 208. In some embodiments, the inner sidewall of the first bonding layer 104 defining the space 130 'and the inner sidewall of the second bonding layer 204 defining the space 130' may be coplanar, as shown in fig. 4. In other embodiments, the inner sidewall of the first bonding layer 104 defining the space 130 'and the inner sidewall of the second bonding layer 204 defining the space 130' may not be coplanar.

In some embodiments, the first dielectric layer 122 may extend upward and beyond the first bonding layer 104, for example, may exceed an interface where the first bonding layer 104 contacts an upper surface of the first dielectric layer 122, or may exceed an upper surface of the first bonding layer 104. The upwardly extending first dielectric layer 122 may completely fill or partially fill the space 150 between adjacent first and second bonding layers 104, 204. The second dielectric layer 222 may also extend downward and beyond the second bonding layer 204. In some embodiments, the first dielectric layer 122 extending upward and the second dielectric layer 222 extending downward together completely fill or partially fill the space 150.

The portion of the first bonding layer 104 may have a protrusion 104p facing the first pad 102, and the first buffer layer 108 may accommodate the protrusion 104p of the first bonding layer 104. Similarly, portions of the second bonding layer 204 may have protrusions 204p facing the second pads 202, and the second buffer layer 208 may accommodate the protrusions 204p of the second bonding layer 204.

The bonding structure 200 also includes at least one particle 230 between the first bonding layer 104 and the second bonding layer 204. The protrusions 104p of the first bonding layer 104 and the protrusions 204p of the second bonding layer 204 may be caused by the particles 230, so that the particles 230 overlap with the corresponding protrusions 104p, 204p in the vertical direction.

Since the first buffer layer 108 and the second buffer layer 208 are disposed between the first bonding layer 104 and the second bonding layer 204 and the corresponding first bonding pad 102 and second bonding pad 202, the particles 230 can make the corresponding portions of the first bonding layer 104 and/or the second bonding layer 204 conform to the particles 230 during bonding, so as to form the protrusions 104p and 204p, and the first buffer layer 108 and the second buffer layer 208 with softer materials can conform to the protrusions 104p and 204p and accommodate the protrusions 104p and 204p. Thus, the first buffer layer 108, the second buffer layer 208, and the first and second bonding layers 104, 204 may collectively conformally encapsulate each particle 230. Since the first and second bonding layers 104 and 204 conformally encapsulate the particles 230 therebetween, the first and second bonding layers 104 and 204 around the particles 230 can be completely contacted without a gap separating the first and second bonding layers 104 and 204, thereby increasing a contact area between the first and second bonding layers 104 and 204 and improving electrical properties. In addition, by providing the first buffer layer 108 and/or the second buffer layer 208, when the particles 230 are present, the first bonding layer 104 and the second bonding layer 204 can be bonded without requiring a large bonding force, so that the problem that the first dielectric layer 122 and the second dielectric layer 222 cannot support the bonding force due to the large bonding force can be avoided, and the electronic devices 180 and 280 are broken.

Further, similarly, for a particle 230 located between the first dielectric layer 122 and the second dielectric layer 222 that overlaps the first bonding layer 104 and the second bonding layer 204, the first bonding layer 104 and the second bonding layer 204 may conformally encapsulate the particle 230, the first bonding layer 104 and the second bonding layer 204 have protrusions 104p, 204p that overlap the particle 230, and the first dielectric layer 122 and the second dielectric layer 222 may house the protrusions 104p, 204p. For particles 230 that are located between the first dielectric layer 122 and the second dielectric layer 222 that do not overlap the first bonding layer 104 and the second bonding layer 204, such as particles 230 located in the space 150 in fig. 4, the particles 230 may be conformally coated with the first dielectric layer 122 and the second dielectric layer 222 together.

Fig. 5 is a schematic cross-sectional view of a joint structure 300 according to another embodiment of the utility model. The junction structure 300 shown in fig. 5 is different from the junction structure 200 shown in fig. 4 in that a cavity 152 is provided between the first dielectric layer 122 and the second dielectric layer 222. Adjacent first and second bonding layers 104, 204 are separated by a cavity 152. In this embodiment, the first dielectric layer 122 does not extend upward, and the second dielectric layer 222 does not extend downward. In some embodiments, the cavity 152 may have at least one particle 230 therein. In some embodiments, the particles 230 may also be absent from the cavity 152.

Fig. 6A-6E are schematic cross-sectional views at various steps in forming a joining structure 400 according to one embodiment of the utility model. Referring to fig. 6A, at least one first pad 102 housed in the electronic device 180 is provided. The first pad 102 is exposed by the electronic device 180. The pitch between the plurality of first pads 102 may be less than 45 μm.

Referring to fig. 6B, a cover dielectric layer is formed on the electronic device 180, and trenches 610 exposing the peripheral edges of the respective first pads 102 are formed in the cover dielectric layer. In some embodiments, the trench 610 may be formed using a mask and through a photolithography process. A blanket dielectric layer over the first pad 102 surrounded by the trench 610 is formed as the first buffer layer 108. A blanket dielectric layer outside of the trench 610 is formed as the first dielectric layer 122.

Referring to fig. 6C, first bonding layer 104 is conformally deposited over first buffer layer 108 and first dielectric layer 122, and within trench 610. Portions of the first bonding layer 104 may then be removed such that adjacent first bonding layers 104 are spaced apart over the first dielectric layer 122. In some embodiments, a portion of the first dielectric layer 122 may be masked (not shown) on the first dielectric layer 122 between the first pads 102, then the first bonding layer 104 may be formed by electroplating, and then the mask may be removed after electroplating, thereby forming the first bonding layer 104 shown in fig. 6C. The first bonding layer 104 extends continuously on the upper surface and outer sidewall of the first buffer layer 108, the bottom of the trench 610, and the sidewall and part of the upper surface of the first dielectric layer 122, and the first bonding layer 104 is connected to the periphery of the corresponding first pad 102.

Referring to fig. 6D, the second bonding layer 204 connected to the second pad 202 of the electronic device 280, the second buffer layer 208 located between the second bonding layer 204 and the second pad 202, and the second dielectric layer 222 disposed laterally side by side with the second bonding layer 204 may be formed through the steps shown in fig. 6A to 6C. Then, the second bonding layer 204 is opposed to the first bonding layer 104.

Referring to fig. 6E, the second bonding layer 204 is butt-bonded to the first bonding layer 104 to obtain a bonding structure 400. By providing the first bonding layer 104 and the second bonding layer 204 to extend over the surfaces of the first buffer layer 108 and the second buffer layer 208, the first bonding layer 104 and the second bonding layer 204 may be planarized, and thus CMP may not be required prior to interfacing the second bonding layer 204 with the first bonding layer 104, effectively reducing bonding process costs.

During bonding, a bonding temperature and bonding force may be applied to diffuse and bond the second bonding layer 204 with the first bonding layer 104. By providing the first buffer layer 108 and the second buffer layer 208, the bonding force applied at the time of bonding can be buffered, and the bonding success rate can be increased.

In the embodiment shown in fig. 6E, a cavity 152 is formed between the first dielectric layer 122 and the second dielectric layer 222. In some other embodiments, at the bonding temperature, the first dielectric layer 122 and the second dielectric layer 222 may soften and extend upward and downward, respectively. The extended first dielectric layer 122 and second dielectric layer 222 may be completely filled or partially filled in the space 150 between adjacent first bonding layer 104 and second bonding layer 204 (shown with reference to fig. 4).

In some embodiments, particles 230 may be present between the first bonding layer 104 and the second bonding layer 204 (see fig. 4) before the first bonding layer 104 and the second bonding layer 204 shown in fig. 6E are butted. In such an embodiment, after bonding the second bonding layer 204 with the first bonding layer 104, a bonding structure 200 as shown in fig. 4 may be obtained. The joining structure 400 formed by the method described above with reference to fig. 6A-6E may have some of the benefits described above with reference to fig. 3-5.

The foregoing description of the preferred embodiments of the utility model is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the utility model.

Claims (10)

1. A joining structure, characterized by comprising:

a bonding pad;

a bonding layer over the bonding pad;

and the buffer layer is positioned between the bonding pad and the bonding layer, wherein the bonding layer extends to the outer side wall of the buffer layer so as to be electrically connected with the bonding pad.

2. The joining structure according to claim 1, wherein,

the buffer layer exposes a periphery of the pad.

3. The joining structure according to claim 1, wherein,

the part of the bonding layer is provided with a bulge, and the buffer layer is used for accommodating the bulge of the bonding layer.

4. The joining structure according to claim 3, further comprising:

particles overlapping the protrusions in a vertical direction.

5. The joining structure according to claim 1, further comprising:

and the dielectric layer is transversely arranged side by side with the bonding layer, and the material of the dielectric layer is the same as that of the buffer layer.

6. The joining structure according to claim 5, wherein,

the dielectric layer extends upward and beyond the bonding layer.

7. The joining structure according to claim 5, wherein,

the dielectric layer is separated from the buffer layer by the bonding layer.

8. The joining structure according to claim 1, wherein,

the bonding layer defines a space located on the outer sidewall side of the buffer layer.

9. The bonding structure of claim 1, wherein the bonding layer is a first bonding layer, the bonding structure further comprising:

and a second bonding layer over and bonded to the first bonding layer, wherein an edge of the second bonding layer is not aligned with an edge of the first bonding layer.

10. The joining structure according to claim 5, wherein,

the bonding layer also extends to the side wall of the dielectric layer.