TW201929171A - Bond pad structure and manufacturing method thereof - Google Patents

Abstract

A bond pad structure and a manufacturing method thereof are disclosed. The bond pad structure includes a first metal layer, and at least two second metal layers laminated successively on the first metal layer. Dielectric layers are provided between the first metal layer and the second metal layers, and between every two adjacent second metal layers. The first metal layer and the the second metal layer adjacent to the first metal layer are electrically connected to each other in a region outside the bonding pad structure. Every two adjacent second metal layers are electrically connected to each other. A manufacturing method of the bond pad structure is further disclosed. In this way, it may avoid pits generated by the bonding of copper wires having large sizes.

Description

Bonding pad structure and manufacturing method of bonding pad structure

The invention relates to the technical field of integrated circuits, in particular to a bonding pad structure and a manufacturing method of the bonding pad structure.

Bond pad is an interface between an integrated circuit (IC) contained in a semiconductor chip and a chip package, and is used to transmit power, ground, and input/output signals to chip components. Wire bonding (Wire Bonding, WB) is a kind of use of thin metal wires, through heat, pressure, ultrasound and other energy to make the metal leads and bonding pads tightly welded, to achieve electrical interconnection between the chip and the outside and information exchange between the chip.

With reference to FIG. 1, the conventional bonding pad structure includes a first metal layer 10 and a plurality of second metal layers 21-23, separated by an inter-metal dielectric layer (IMD), each metal layer penetrates Via 40 penetrates through the dielectric layer to achieve electrical connection. At present, copper wires are inexpensive, highly reliable, and have good electrical and thermal conductivity. Compared with other materials, the same wire diameter can withstand larger currents. The advantage becomes the choice of more and more high-power devices, and when large-size copper wires are bonded on the bonding pads, the required bonding force is large. When the force directly acts on the first metal layer 10 of the bonding pad, it is easy to Metal layer 10 and second gold There are pits formed between the through holes 40 of the metal layer 21. When the pits are severe, all the through holes 40 and the metal layer are cracked, which poses a significant threat to the reliability of the chip and even causes the chip to fail.

The technical problem mainly solved by the present invention is to provide a bonding pad structure and a manufacturing method of the bonding pad structure, which can take into account both cost and performance while avoiding the pit problem caused by large-sized copper bonding wires.

In order to solve the above technical problems, a technical solution adopted by the present invention is to provide a bonding pad structure including: a first metal layer; at least two second metal layers stacked in sequence with respect to the first metal layer; the first metal layer A dielectric layer is provided between the second metal layer and the second metal layer; the first metal layer and the second metal layer adjacent to the first metal layer are electrically connected outside the bonding pad structure area ; The second metal layer is electrically connected between two adjacent layers.

To solve the above technical problems, another technical solution adopted by the present invention is to provide a method for manufacturing a bonding pad structure, including: providing a semiconductor wafer; forming a first dielectric layer relative to the semiconductor wafer; and sequentially opposing the first dielectric layer Stacking to form at least two second metal layers, providing a second dielectric layer between the second metal layers; electrically connecting adjacent two layers of the second metal layer; A first metal layer is formed opposite to the second metal layer, and a third dielectric layer is provided between the first metal layer and the second metal layer; the first metal layer and the The second metal layer adjacent to the first metal layer is electrically connected.

The beneficial effects of the present invention are: different from the case of the conventional technology, the present invention electrically connects the first metal layer and the second metal layer adjacent to the first metal layer outside the bonding pad structure area In order to avoid the pit problem caused by large-size copper bonding wires.

10‧‧‧First metal layer

21, 22, 23‧‧‧Second metal layer

31‧‧‧First dielectric layer

32‧‧‧Second dielectric layer

33‧‧‧third dielectric layer

40‧‧‧Second through hole

50‧‧‧passivation layer

60‧‧‧Semiconductor chip

S1 to S6‧‧‧ steps

FIG. 1 is a schematic cross-sectional view of a conventional bonding pad structure provided on a semiconductor wafer; FIG. 2 is a schematic view of a three-dimensional structure of a metal layer of a bonding pad structure according to a first embodiment of the invention; FIG. 3 is a bonding according to a second embodiment of the invention 3D schematic diagram of the metal layer of the pad structure; FIG. 4 is a schematic diagram of the metal layer of the bonding pad structure of the third embodiment of the present invention; FIG. 5 is a metal layer of the bonding pad structure of the third embodiment of the present invention provided on a semiconductor wafer 6 is a schematic diagram of a three-dimensional structure of a metal layer of a bonding pad structure according to a fourth embodiment of the invention; FIG. 7 is a schematic diagram of a sectional structure of a metal layer of a bonding pad structure according to a fifth embodiment of the invention provided on a semiconductor wafer ; FIG. 8 is a schematic flow chart of the manufacturing method of the bonding pad structure of the present invention.

The present invention will be described in detail below with reference to the drawings and embodiments.

Please refer to FIG. 2, which is a schematic view of a three-dimensional structure of a metal layer of a bonding pad structure according to a first embodiment of the present invention (a longitudinal section along dotted line a in FIG. 2 ). The bonding pad structure is located on a semiconductor wafer 60 and includes: a first metal layer 10; at least two second metal layers stacked in sequence with respect to the first metal layer 10 (in this embodiment, including three second metal layers, respectively a second metal layer 21, a second metal layer 22, the first Two metal layers 23, in other embodiments, the number of the second metal layer can be set as needed); between the first metal layer 10 and the second metal layer 21 and between the second metal layers 21-23 A dielectric layer is provided between the two; a first through hole (not shown in the figure) is provided outside the bonding pad structure area, and the first through hole connects the first metal layer 10 and the first metal layer through the wire The second metal layer 21 is connected to achieve electrical connection between the first metal layer 10 and the second metal layer 21 adjacent to the first metal layer.

The adjacent two layers of the second metal layers 21-23 are electrically connected through the second through holes 40.

A passivation layer 50 is provided on the first metal layer 10 of the bonding pad structure, and the passivation layer 50 covers the edge of the first metal layer 10 to expose the middle position of the first metal layer 10 to protect the bonding pad structure .

In this embodiment, the materials of the first metal layer 10 and the second metal layers 21-23 are aluminum (Al); the dielectric layers 31-33 are silicon nitride (SiNx); and the second through holes 40 The conductive material is tungsten (W).

When a large-size (such as 1.8 mil) copper wire (not limited to copper wire in other embodiments) is bonded on the bonding pad structure, between the first metal layer 10 and the second metal layer 21 The first dielectric layer can withstand the stress caused by the bonding in a large area, so that the impact force generated when the copper bonding wire is bonded is evenly distributed to each second metal layer 21-23.

Please refer to FIG. 3, which is a schematic diagram of a three-dimensional structure of a metal layer of a bonding pad structure according to a second embodiment of the present invention (a longitudinal section along dotted line a in FIG. 3). The bonding pad structure is located on a semiconductor wafer 60, which is different from FIG. 2 In this embodiment, the second metal layer 21 is divided into a plurality of strip-shaped metals (in other embodiments, it can be divided into strip-shaped metals by some other second metal layer), and on each second metal layer 21 The total area of the metal strips is less than the total area corresponding to the second metal layer. Specifically, the total area of the metal strips on each second metal layer 21 is less than 60% of the total area corresponding to the second metal layer.

When a large-size (such as 1.8 mil) copper wire (not limited to copper wire in other embodiments) is bonded on the bonding pad structure, between the first metal layer 10 and the second metal layer 21 The first dielectric layer can withstand the stress caused by bonding in a large area, so that the impact force generated when the copper bonding wire is bonded is evenly distributed to the second metal layer 21 and along the metal strips on the second metal layer 21, Since the total area of the metal strips on each second metal layer 21 accounts for less than 60% of the total area of the corresponding second metal layer, the impact force is dispersed on the dielectric layer between two adjacent layers.

Please refer to FIG. 4 and FIG. 5, FIG. 4 is a three-dimensional schematic diagram of the metal layer of the bonding pad structure of the third embodiment of the present invention. Combined with FIG. 5, FIG. 5 is a metal of the bonding pad structure of the third embodiment of the present invention Schematic diagram of the cross-sectional structure of the layer disposed on the semiconductor wafer (longitudinal line along the dotted line a in FIG. 4), the bonding pad structure is located on the semiconductor wafer 60, and the difference from FIG. 3 is that in this embodiment, the second metal layer 21-23 are divided into multiple strips of metal.

The projections of the metal strips on the second metal layers 21 and 22 in the same plane intersect, and the second metal layers 21 and 22 are electrically connected through the second through hole 40 at the intersection, and the second metal layer 22 and 22 The projections of the metal strips on 23 in the same plane intersect, and the second metal layer 22 and 23 are electrically connected through the second through hole 40 at the intersection.

Specifically, the projections of the metal strips on adjacent two of the second metal layers 21-23 in the same plane intersect vertically, that is, the projections in the same plane, the metal strips on the second metal layer 21 are perpendicular to the second The metal strips on the metal layer 22, the metal strips on the second metal layer 22 are perpendicular to the metal strips on the second metal layer 23, and the projected intersections of the metal strips on every two adjacent second metal layers 21-23 pass through the second pass The hole 40 electrically connects two adjacent metal layers in the second metal layers 21-23 (in this embodiment, a second through hole is provided at all the intersections of the metal strips on each adjacent two second metal layers. In other embodiments, a second through hole may be provided at the projected intersection of the metal strips on each adjacent two second metal layers, or a second through hole may be provided at other positions of each adjacent two second metal layers to connect the adjacent two The second metal layer is electrically connected).

Specifically, the projections of the second metal layers disposed at two intervals, such as the metal strips on the second metal layers 21 and 23, coincide on the same plane (in other embodiments (The projections of the metal strips on the second metal layer spaced apart in the middle on the same plane may not overlap).

In this embodiment, the total area of the metal strips on each second metal layer 21-23 is smaller than the total area of the corresponding second metal layer. Specifically, the metal strips on each second metal layer 21-23 The total area is less than 60% of the total area corresponding to the second metal layer.

When a large-size (such as 1.8 mil) copper wire (not limited to copper wire in other embodiments) is bonded on the bonding pad structure, between the first metal layer 10 and the second metal layer 21 The first dielectric layer 31 can withstand the stress caused by bonding in a large area, so that the impact force generated when the copper bonding wire is bonded is evenly distributed on each second metal layer 21-23, and then along the second metal layer The vertical intersecting X, Y axis of the metal strips on 21-23 is dispersed. Since the total area of the metal strips on each second metal layer 21-23 accounts for less than 60% of the total area of the corresponding second metal layer, the impact force Dispersed on the dielectric layers 31-33 between two adjacent layers.

Please refer to FIG. 6, which is a schematic view of a three-dimensional structure of a metal layer of a bonding pad structure according to a fourth embodiment of the present invention. The difference from FIG. 5 is that a second through hole 40 is electrically connected between two adjacent second metal layers. The second through holes 40 between the layers are arranged correspondingly at intervals, such as two adjacent second through holes 41 and 42 provided between the second metal layers 21 and 22, and the second between the second metal layers 22 and 23 The projection of the through hole 43 and the second through holes 41 and 42 in the same plane is between the second through holes 41 and 42.

Please refer to FIG. 7, which is a schematic view of the cross-sectional structure of the metal layer of the bonding pad structure provided on the semiconductor wafer according to the fifth embodiment of the present invention Vertical line a), the bonding pad structure is located on the semiconductor wafer 60, the difference from FIG. 5 is that two spaced apart second metal layers such as the metal strips on the second metal layers 21 and 23 are on the same plane The projections do not coincide. For example, the two metal strips 211 and 212 on the second metal layer 21 are parallel. On the same projection plane, the metal strip 231 on the second metal layer 23 is between the metal strip 211 and the metal strip 212.

Please refer to FIG. 8, which is a schematic flowchart of the method for manufacturing the bonding pad structure of the present invention, including:

Step S1: A semiconductor wafer 60 is provided.

The semiconductor wafer is silicon (Si).

Step S2: Form a first dielectric layer 31 relative to the semiconductor wafer 60.

A dielectric material is deposited on the semiconductor wafer 60 by spin coating to form a first dielectric layer 31. In this embodiment, the dielectric material is silicon nitride (SiNx).

Step S3: Relative to the first dielectric layer 31 is sequentially stacked to form at least two second metal layers (in this embodiment, it includes three second metal layers, namely a second metal layer 21, a second metal layer 22, a second The second metal layer 23, in other embodiments, the number of the second metal layer can be set as needed), and a second dielectric layer 32 is provided between the second metal layers 21-23.

Specifically, the second metal layers 21-23 are all divided into a plurality of strip-shaped metals. The projections of the metal strips on the second metal layers 21 and 22 in the same plane intersect, and the projections of the metal strips on the second metal layers 22 and 23 in the same plane intersect.

Specifically, the projections of the metal strips on adjacent two of the second metal layers 21-23 in the same plane intersect vertically, that is, the projections in the same plane, the metal strips on the second metal layer 21 are perpendicular to the second The metal strip on the metal layer 22 and the metal strip on the second metal layer 22 are perpendicular to the metal strip on the second metal layer 23.

Specifically, the second metal layers disposed at two intervals, such as the projections of the metal strips on the second metal layers 21 and 23 on the same plane, overlap (in other embodiments, the metal strips on the second metal layers disposed at the two intervals are the same (The plane projections may not coincide.)

The second metal layer 23 is deposited on the first dielectric layer 31 by spin coating, the second metal layer 23 is distributed in parallel strips by etching, and then the dielectric material is deposited on the second metal layer 23 The second dielectric layer 32 is formed, and then the second metal layer 22 is deposited on the second dielectric layer 32, the second metal layer 22 is etched to be distributed in parallel stripes, and then the dielectric material is deposited on the first A second dielectric layer 32 is formed on the two metal layers 22, and then the second metal layer 21 is deposited on the second dielectric layer 32, and the second metal layer 21 is etched to be distributed in parallel stripes, wherein the second metal The projections of the metal strips on the layers 21-23 in the same plane intersect vertically, that is, the projections in the same plane, the metal strips on the second metal layer 21 are perpendicular to the metal strips on the second metal layer 22, the second metal layer 22 The upper metal strip is perpendicular to the metal strip on the second metal layer 23. When a large-sized copper wire is bonded on the first metal layer 10 of the bonding pad structure, the impact force of each second metal layer 21-23 can be along the adjacent two of the second metal layers 21-23 The metal strips on the metal layer intersect the X and Y axes that intersect vertically.

In this embodiment, the materials of the first metal layer 10 and the second metal layers 21-23 are aluminum (Al).

Step S4: electrically connect two adjacent layers of the second metal layer 21-23.

Specifically, a second through hole 40 is provided at the intersection of the projections of the metal strips on each adjacent two layers of the second metal layer 21-23 in the same plane to electrically connect the two adjacent second metal layers 21-23 Connection (in this embodiment, a second through hole is provided at all projected intersections of the metal strips on every two adjacent second metal layers, in other embodiments, the metal strips on each adjacent two second metal layers can be projected to intersect Through holes are provided at each location, and second through holes can also be provided at other positions of each adjacent two second metal layers to electrically connect the two adjacent second metal layers).

Specifically, the second through hole 40 may be formed through a tungsten plug process.

In other embodiments, the electrical connection between the second metal layers can be established by connecting a plurality of wires at the same connection point to electrically connect two adjacent metal layers. In addition to the conductive properties, the wires can also To achieve the support between two adjacent metal layers.

Step S5: A first metal layer 10 is formed relative to the second metal layers 21-23, and a third dielectric layer 33 is provided between the first metal layer 10 and the second metal layers 21-23.

A dielectric material is deposited on the second metal layer 21 by spin coating to form a third dielectric layer 33, and then the first metal layer 10 is deposited on the third dielectric layer 33, the first metal layer 10 The third dielectric layer 33 between the second metal layer 21 and the second metal layer 21 can withstand the impact force caused by the bonding in a large area.

Step S6: electrically connecting the first metal layer 10 and the second metal layer 21 adjacent to the first metal layer outside the bonding pad structure area.

Specifically, a first through hole (not shown in the figure) is provided outside the bonding pad structure area, the first through hole connects the first metal layer 10 and the second metal adjacent to the first metal layer through a wire The layer 21 is connected to achieve electrical connection between the first metal layer 10 and the second metal layer 21 adjacent to the first metal layer.

A passivation layer 50 is provided on the first metal layer 10 of the bonding pad structure, and the passivation layer 50 covers the edge of the first metal layer 10 and exposes the middle position of the first metal layer to protect the bonding pad structure .

In this embodiment, the ratio of the total area of the metal strips on each second metal layer 21-23 to the total area of the corresponding second metal layer is less than 60% (such as the total area of the metal strips on the second metal layer 21 The proportion of the total area of the second metal layer 21 is less than 60%), so that the impact force is dispersed on the dielectric layers 31-33 of the two adjacent second metal layers.

According to the present invention, at least two second metal layers are stacked and each second metal layer is divided into a plurality of parallel metal strips, and the projections of the metal strips on the adjacent two second metal layers in the same plane intersect vertically and intersect vertically The two adjacent second metal layers are electrically connected, and the total area of the metal strips on the second metal layer accounts for less than 60% of the total area of the corresponding second metal layer. In the first metal layer and the first metal layer Electrical connection outside the bonding pad structure area between the two metal layers, so that the impact force on the bonding pad structure when the large-size copper wire is bonded to the first metal layer is dispersed, achieving both cost and performance Avoid the pit problem caused by large-size copper bonding wires.

The above are only the embodiments of the present invention, and therefore do not limit the patent scope of the present invention. Anything made by the description and drawings of the present invention Effective structure or equivalent process transformation, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present invention.

Claims (10)

A bonding pad structure includes: a first metal layer; at least two second metal layers stacked in sequence with respect to the first metal layer; between the first metal layer and the second metal layer and between the second metal layer A dielectric layer is provided; the first metal layer and the second metal layer adjacent to the first metal layer are electrically connected outside the bonding pad structure area; the two adjacent metal layers are electrically connected between two adjacent layers . The bonding pad structure according to item 1 of the patent application scope, wherein at least one layer of the second metal layer is divided into a plurality of strip-shaped metals. The bonding pad structure according to item 2 of the patent application scope, wherein the second metal layer adjacent to the first metal layer is divided into a plurality of strip-shaped metals. The bonding pad structure according to item 2 of the patent application scope, wherein all the second metal layers are divided into a plurality of strip-shaped metals. The bonding pad structure according to item 4 of the patent application scope, wherein the projections of the metal strips on adjacent two layers of the second metal layer in the same plane intersect. The bonding pad structure according to item 5 of the patent application scope, wherein the projections of the metal strips on adjacent two layers of the second metal layer in the same plane intersect perpendicularly. The bonding pad structure according to item 6 of the patent application scope, wherein the metal strips on adjacent two layers of the second metal layer electrically connect the adjacent two second metal layers at the intersection of projections in the same plane . The bonding pad structure according to item 2 of the patent application scope, wherein the total area of the metal strips on each second metal layer accounts for a certain proportion of the total area of the corresponding second metal layer. The bonding pad structure according to item 1 of the patent application scope, wherein a passivation layer is provided on the first metal layer of the bonding pad structure, and the passivation layer covers the edge of the first metal layer to connect the first metal The middle of the layer is exposed to protect the bond pad structure. A method for manufacturing a bonding pad structure includes: providing a semiconductor wafer; forming a first dielectric layer relative to the semiconductor wafer; sequentially stacking at least two second metal layers relative to the first dielectric layer, between the second metal layers Providing a second dielectric layer; electrically connecting two adjacent layers of the second metal layer; forming a first metal layer opposite to the second metal layer, and between the first metal layer and the second metal layer A third dielectric layer is provided between them; the first metal layer and the second metal layer adjacent to the first metal layer are electrically connected outside the bonding pad structure area.