CN113471090A - Bonding method and bonding mechanism of metal bumps - Google Patents

Bonding method and bonding mechanism of metal bumps Download PDF

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Publication number
CN113471090A
CN113471090A CN202110572516.3A CN202110572516A CN113471090A CN 113471090 A CN113471090 A CN 113471090A CN 202110572516 A CN202110572516 A CN 202110572516A CN 113471090 A CN113471090 A CN 113471090A
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metal bump
layer
metal
seed layer
bonding
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王喆垚
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Tsinghua University
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Tsinghua University
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L24/81—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a bump connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/74—Apparatus for manufacturing arrangements for connecting or disconnecting semiconductor or solid-state bodies
    • H01L24/75—Apparatus for connecting with bump connectors or layer connectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/74—Apparatus for manufacturing arrangements for connecting or disconnecting semiconductor or solid-state bodies and for methods related thereto
    • H01L2224/75—Apparatus for connecting with bump connectors or layer connectors
    • H01L2224/7525—Means for applying energy, e.g. heating means
    • H01L2224/753—Means for applying energy, e.g. heating means by means of pressure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L2224/81—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a bump connector
    • H01L2224/8134—Bonding interfaces of the bump connector
    • H01L2224/81345—Shape, e.g. interlocking features

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  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Wire Bonding (AREA)

Abstract

The invention provides a bonding method and a bonding mechanism of a metal bump, the bonding method of the metal bump forms a closed cavity by matching a first concave part and a convex part, and the closed cavity contains a middle metal layer melted during bonding, so that the flow of liquid middle layer metal under bonding pressure can be effectively prevented, the transverse expansion of the liquid middle layer metal is avoided, and the bonding of the metal bump with small diameter and high density can be realized. In addition, when the first concave part and the convex part are matched, the first metal bump and the second metal bump can be self-adaptively adjusted in alignment position through relative sliding. The bonding method of the metal bump provided by the invention does not need expensive CMP equipment and process, greatly reduces the difficulty and cost of the process, and can adapt to the height difference of the metal bump to a certain extent.

Description

Bonding method and bonding mechanism of metal bumps
Technical Field
The present invention relates to the field of integrated circuits, and in particular, to a method and a mechanism for bonding metal bumps.
Background
Integrated circuits have developed over the past 60 years, following the laws of moore's law, and their feature sizes and integration levels have continued to progress at a rate that is roughly doubled every 18 months, making high-speed, high-performance, low-power integrated circuits the cornerstone of the information industry. However, as the feature size of integrated circuit processes continues to shrink, particularly after the feature size has gone into 10nm, the technological path for further shrinking the feature size has met with unprecedented difficulties both technically and economically.
In recent years, a way of implementing planar or stereoscopic stacked integration of multiple chips by using heterogeneous integration methods such as interposer integration (2.5D integration) and three-dimensional integration (3D integration) has been rapidly developed. The heterogeneous integration method realized by using the bonding technology and the Through Silicon Via (TSV) technology breaks away from the dependence on the continuous reduction of the feature size by integrating a plurality of chips with different functions, different processes and different sizes, has outstanding advantages in the aspects of data transmission bandwidth, integration level, multiple functions, power consumption, size and the like, and becomes one of important development directions in the field of integrated circuits.
Heterogeneous integration techniques present new challenges, one of the most important of which is the issue of electrical interconnect density from chip to chip or from chip to interposer. The electrical interconnection between the two layers of chips is realized by the bonding of the metal bumps between the two layers of chips, the density and the number of the metal bumps determine the electrical interconnection density between the two layers of chips, and a plurality of high-performance chips have extremely high requirements on the interconnection density.
The bonding method of the metal bump can be broadly divided into two types, solid metal bonding and liquid metal bonding. The solid metal bonding comprises metal hot-pressing bonding and room temperature bonding, and the metal salient points on the surfaces of the upper chip and the lower chip are bonded in a solid state under certain bonding pressure and bonding temperature, such as copper-copper bonding, gold-gold bonding, aluminum-aluminum bonding and the like. The method has the advantages that the metal is solid in the bonding process, no position slippage exists between the metal salient points after bonding, and no transverse expansion of the liquid metal is generated under the bonding pressure, so that the bonding with small diameter, high density and high alignment precision can be realized. However, since the metal is in a solid state and does not have a liquid state in the bonding process, the metal deformation is very small, and the metal bump height difference and the chip thickness non-uniformity cannot be adapted to, the metal and the dielectric layer must be planarized by Chemical Mechanical Polishing (CMP) before bonding, the process is complex, and the manufacturing cost is very high.
The liquid metal bonding is mainly solid-liquid interdiffusion bonding, the bonding method uses low-melting-point metal as middle layer metal to connect metal salient points formed by high-melting-point metals at two sides for bonding, the middle layer metal is melted during bonding and carries out chemical reaction with the metal salient points at two sides to generate intermetallic compounds for realizing bonding. Because the intermediate layer metal is melted into liquid state and has deformability, the method can adapt to the non-uniformity of the height of the metal bump and the thickness of the chip to a certain extent, CMP is not needed, the manufacturing process is simple, and the cost is low. However, after the intermediate layer metal is melted in the bonding process, the liquid metal has an expansion problem under the action of bonding pressure, so that the metal bump bonding with small center distance is difficult to realize, and high-density interconnection cannot be realized. In addition, the liquid metal can also cause bump slippage during bonding, further limiting bump diameter reduction.
Disclosure of Invention
The invention provides a bonding method and a bonding mechanism of metal bumps, which are used for solving the problem that liquid metal expands in the liquid metal bonding technology in the prior art.
The invention provides a bonding method of a metal bump, which comprises the following steps:
a10, arranging a first seed layer on one side of a lower substrate and a second seed layer on one side of an upper substrate;
a20, arranging a first mould layer with a through hole on one side of the first seed layer, which is far away from the lower substrate, and arranging a second mould layer with a through hole on one side of the second seed layer, which is far away from the upper substrate;
a30, forming a first metal bump in the through hole of the first mould layer by using an electroplating method, and forming a first concave part on the side of the first metal bump, which is far away from the first seed layer, by controlling the concentration of an additive in an electroplating solution; forming a second metal bump in the through hole of the second mold layer, and forming a convex part on one side of the second metal bump, which is far away from the second seed layer;
a40, forming an intermediate metal layer in the first concave part by using an electroplating method, wherein a second concave part is formed on one side of the intermediate metal layer, which is far away from the first metal bump;
a step a50 of removing the first mold layer and the second mold layer;
a step 60, removing the first seed layer and the second seed layer;
a70, reflowing the lower substrate at high temperature, and controlling the heating speed of reflow to make the center thickness of the middle metal layer larger than the edge thickness;
step a80, aligning and contacting the convex part of the second metal bump with the second concave part of the first metal bump, and applying bonding pressure and temperature to bond the first metal bump with the second metal bump.
According to the bonding method of the metal bump provided by the invention, the width of the second metal bump is larger than that of the first metal bump.
According to the bonding method of the metal bump provided by the invention, the height of the center of the second concave part is lower than the height of the edge of the first concave part.
According to the bonding method of the metal bump provided by the invention, the height difference between the edge of the convex part and the center of the convex part is smaller than the height difference between the edge of the first concave part and the center of the first concave part.
According to the bonding method of the metal bumps, the middle metal layer is made of metal tin, the first metal bumps and the second metal bumps are made of metal copper, and the first mold layer and the second mold layer are made of high polymer materials.
The invention also provides a bonding method of the metal bump, which comprises the following steps:
b10, arranging a first seed layer on one side of the lower substrate and a second seed layer on one side of the upper substrate;
step b20, arranging a first mould layer with a through hole on one side of the first seed layer, which is far away from the lower substrate, and arranging a second mould layer with a through hole on one side of the second seed layer, which is far away from the upper substrate;
b30, forming a first metal bump in the through hole of the first mould layer by using an electroplating method, and forming a first concave part on the side of the first metal bump, which is far away from the first seed layer, by controlling the concentration of an additive in an electroplating solution; forming a second metal bump in the through hole of the second mold layer;
step b40, forming an intermediate metal layer on one side of the second metal bump, which is far away from the second seed layer, by using an electroplating method;
step b50, removing the first mold layer and the second mold layer;
step b60, removing the first seed layer and the second seed layer;
step b70, reflowing the upper substrate at high temperature to form a convex part matching the first concave part on the intermediate metal layer;
step b80, aligning and contacting the convex part with the first concave part, and applying bonding pressure and temperature to bond the first metal bump and the second metal bump.
The invention also provides a bonding mechanism of the metal bump, which comprises:
the device comprises a lower substrate, wherein a first seed layer is arranged on one side of the lower substrate, a first metal bump is arranged on one side, away from the lower substrate, of the first seed layer, a first concave part is formed on one side, away from the first seed layer, of the first metal bump, and an interlayer metal is arranged in the first concave part;
the metal bump structure comprises an upper substrate, wherein a second seed layer is arranged on one side of the upper substrate, a second metal bump is arranged on one side, away from the upper substrate, of the second seed layer, the edge of one side, away from the second seed layer, of the second metal bump is in contact with the edge of a concave portion of the first metal bump to form a closed cavity, and the first metal bump and the second metal bump are bonded through a middle metal layer in the first concave portion.
According to the bonding mechanism of the metal bumps provided by the invention, the width of the second metal bump is larger than that of the first metal bump.
According to the bonding mechanism of the metal bump provided by the invention, the melting point of the intermediate metal layer is lower than the melting points of the first metal bump and the second metal bump.
According to the bonding method of the metal bump, the first concave part and the convex part are matched to form the closed cavity, the closed cavity is used for accommodating the molten intermediate metal layer during bonding, the liquid intermediate layer metal can be effectively prevented from flowing under the bonding pressure, the transverse expansion of the liquid intermediate layer metal is avoided, and therefore the bonding of the metal bump with small diameter and high density can be realized. In addition, when the first concave part and the convex part are matched, the first metal bump and the second metal bump can be self-adaptively adjusted in alignment position through relative sliding. The bonding method of the metal bump provided by the invention does not need expensive CMP equipment and process, greatly reduces the difficulty and cost of the process, and can adapt to the height difference of the metal bump to a certain extent.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a lower substrate provided with no first metal bump;
FIG. 2 is a schematic structural diagram of a lower substrate provided with a first metal bump according to the present invention;
FIG. 3 is a schematic structural diagram of a lower substrate provided by the present invention after an intermediate metal layer is disposed thereon;
FIG. 4 is a schematic structural diagram of the underlying substrate provided by the present invention after the first mold layer and a portion of the first seed layer are removed;
FIG. 5 is a schematic view of the structure of the present invention after reflow of the lower substrate;
FIG. 6 is a schematic structural diagram of the upper substrate provided by the present invention after removing the second mold layer and a portion of the second seed layer;
FIG. 7 is a schematic structural diagram of a first metal bump and a second metal bump after bonding;
FIG. 8 is a schematic structural diagram of the upper substrate after the second mold layer and a portion of the second seed layer are removed;
fig. 9 is a schematic structural diagram of a first metal bump and a second metal bump after bonding according to another embodiment of the present invention.
Reference numerals:
100. a lower substrate; 101. a first seed layer; 102. a first metal bump; 103. an intermediate metal layer; 104. a first recess; 105. a second recess; 110. a first mold layer; 200. an upper substrate; 201. a second seed layer; 202. a second metal bump; 204. a convex portion.
Detailed Description
The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "connected" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. Specific meanings of the above terms in the embodiments of the present invention can be understood in specific cases by those of ordinary skill in the art.
In embodiments of the invention, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of an embodiment of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
The bonding method and bonding mechanism of the metal bump according to the present invention will be described with reference to fig. 1 to 9.
According to an embodiment of the present invention, as shown in fig. 1 to 7, a method for bonding a metal bump includes the steps of:
a step 10, arranging a first seed layer 101 on one side of a lower substrate 100 and a second seed layer 201 on one side of an upper substrate 200;
as shown in fig. 1, the first seed layer 101 and the second seed layer 201 are made of copper or other conductive metal, and may be deposited on the surface of the corresponding substrate by sputtering or evaporation.
It should be noted that the lower substrate 100 may be a circuit and/or a microsensor chip manufactured by a standard integrated circuit process and/or a micromachining technology, or may be a chip with other structures, and of course, the lower substrate 100 may also be a wafer, and the specific type of the lower substrate 100 is not specifically limited herein.
A step a20, arranging a first mould layer 110 with through holes on the side of the first seed layer 101 facing away from the lower substrate 100, and arranging a second mould layer with through holes on the side of the second seed layer 201 facing away from the upper substrate 200;
as shown in fig. 1 and 6, the first mold layer 110 is provided with a through hole for providing a place for forming the first metal bump 102, and the second mold layer is provided with a through hole for providing a place for forming the second metal bump 202. The number of the through holes can be one or more. The through holes may be formed in various manners, and the through holes may be formed on the first mold layer 110 and the second mold layer by using photolithography or reactive ion etching, so that the first seed layer 101 and the second seed layer 201 are exposed, thereby providing conditions for forming the first metal bump 102 and the second metal bump 202. The first mold layer 110 and the second mold layer are made of a polymer material, such as a liquid polymer precursor, e.g., photoresist, benzocyclobutene, or polyimide, or a solid dry film polymer material. If the liquid polymer precursor is the liquid polymer precursor, coating the liquid polymer precursor on one side of the substrate in a suspension coating mode, and then heating and curing; if the polymer is a dry film polymer, the polymer is bonded to one side of the substrate by film pressing or the like.
A30, forming a first metal bump 102 in the through hole of the first mold layer 110 by electroplating method, and forming a first concave part 104 on the side of the first metal bump 102 away from the first seed layer 101 by controlling the concentration of the additive in the electroplating solution; forming a second metal bump 202 in the through hole of the second mold layer, and forming a convex part 204 on one side of the second metal bump 202, which is far away from the second seed layer 201;
as shown in fig. 2 and 6, the first metal bump 102 and the second metal bump 202 are formed by a conventional electroplating method, and the formation processes of the first metal bump 102 and the second metal bump 202 are described below.
In the process of forming the first metal bump 102, the first seed layer 101 is used as an electrode, and the conventional electroplating method is adopted to deposit the first metal bump 102 on the surface of the first seed layer 101 exposed in the through hole of the first mold layer 110, wherein the transverse shape of the first metal bump 102 is limited by the through hole of the first mold layer 110. By controlling the composition and concentration in the plating solution, a pulse current is used as a plating waveform, so that the side of the first metal bump 102 facing away from the first seed layer 101 forms a first concave portion 104.
In the process of forming the second metal bump 202, the second seed layer 201 is used as an electrode, and the conventional electroplating method is also adopted, so that the second metal bump 202 is deposited on the surface of the second seed layer 201 exposed in the through hole of the second mold layer, and the transverse shape of the second metal bump 202 is limited by the through hole of the second mold layer. By controlling the composition and concentration of the plating solution, a pulse current is used as a plating waveform, so that the convex portion 204 is formed on the side of the second metal bump 202 away from the second seed layer 201.
A40, forming an intermediate metal layer 103 in the first concave part 104 by using an electroplating method, and forming a second concave part 105 on the side of the intermediate metal layer 103, which is far away from the first metal bump 102;
as shown in fig. 3 and 6, in the process of forming the intermediate metal layer 103 and the second recess 105, the intermediate metal layer 103 is formed by electroplating on the inner surface of the first recess 104 by a conventional electroplating method using the first seed layer 101 and the first metal bump 102 as electrodes. The melting point of the intermediate metal layer 103 is lower than the melting points of the first metal bump 102 and the second metal bump 202, in this embodiment, the material of the intermediate metal layer 103 is tin, and the materials of the first metal bump 102 and the second metal bump 202 are copper. Of course, the material of the intermediate metal layer 103 and the materials of the first metal bump 102 and the second metal bump are not limited thereto, and may be other metal materials, and are not particularly limited thereto. The thickness of the intermediate metal layer 103 is determined according to the height of the first metal bump 102, and should satisfy the requirement of solid-liquid interdiffusion to copper-tin mass ratio. Meanwhile, the thickness of the intermediate metal layer 103 is also required to be sufficient that the height of the center of the second concave portion 105 is lower than the height of the edge of the first concave portion 104 after the thermal reflow, so as to achieve the purpose of optimizing the surface tension and curvature after the tin is melted.
Step a50, removing the first mold layer 110 and the second mold layer;
as shown in fig. 4 and 6, the removal of the first mold layer 110 and the second mold layer is determined according to the material, and may be performed by wet etching or dry etching, and after the first mold layer 110 and the second mold layer are removed, a portion of the first seed layer 101 and the second seed layer 201 are exposed.
A step 60, removing the first seed layer 101 and the second seed layer 201;
as shown in fig. 4 and 6, after exposing a portion of the first seed layer 101 and the second seed layer 201, wet etching is used to remove the exposed portions of the first mold layer 110 and the second mold layer.
A70, reflowing the lower substrate 100 at high temperature, and controlling the heating speed of the reflow to make the center thickness of the middle metal layer 103 greater than the edge thickness;
as shown in fig. 5 and 6, the lower substrate 100 is reflowed at a high temperature, the reflow temperature is well above the melting point of the intermediate metal layer 103 to melt the intermediate metal layer 103, and the heating rate of the reflow is controlled so that the center thickness of the intermediate metal layer 103 is greater than the edge thickness, thereby ensuring that the second concave portion 105 fits the convex portion 204.
In step a80, the convex portion 204 of the second metal bump 202 is aligned with and contacted with the second concave portion 105 of the first metal bump 102, and a bonding pressure and temperature are applied to bond the first metal bump 102 and the second metal bump 202.
As shown in fig. 7, when the first metal bump 102 is bonded to the second metal bump 202, the upper substrate 200 needs to be rotated by 180 ° so that the convex portion 204 of the second metal bump 202 faces downward, the convex portion 204 is abutted to the second concave portion 105, and bonding pressure and temperature are applied to bond the first metal bump 102 to the second metal bump 202. The selection of the bonding pressure and temperature is specifically determined according to the material of the intermediate metal layer 103, in this embodiment, the bonding pressure is 10Mpa, and the temperature is 260 °.
According to the bonding method of the metal bump, the first concave part 104 and the convex part 204 are matched to form the closed cavity, the closed cavity is used for accommodating the molten intermediate metal layer 103 during bonding, the flowing of liquid intermediate layer metal under bonding pressure can be effectively prevented, the transverse expansion of the liquid intermediate layer metal is avoided, and therefore the bonding of the metal bump with small diameter and high density can be realized. In addition, when the first concave part 104 and the convex part 204 are adopted to cooperate, the first metal bump 102 and the second metal bump 202 can be adjusted in alignment position by relative sliding. The bonding method of the metal bump provided by the invention does not need expensive CMP equipment and process, greatly reduces the difficulty and cost of the process, and can adapt to the height difference of the metal bump to a certain extent.
According to an embodiment of the present invention, the surface of the protrusion 204 is a curved surface, which allows the protrusion 204 to have a larger contact surface. The difference in height between the edge of the convex portion 204 and the center of the convex portion 204 is smaller than the difference in height between the edge of the first concave portion 104 and the center of the first concave portion 104.
According to the embodiment of the present invention, the first seed layer 101 is deposited on one side of the lower substrate 100 by a sputtering or evaporation method; the second seed layer 201 is deposited on one side of the upper substrate 200 by a sputtering or evaporation method.
The invention also provides a bonding method of the metal bump, as shown in fig. 8 and 9, the bonding method of the metal bump comprises the following steps:
step b10, arranging a first seed layer 101 on one side of the lower substrate 100 and a second seed layer 201 on one side of the upper substrate 200;
a step b20 of providing a first mold layer 110 with through holes on the side of the first seed layer 101 facing away from the lower substrate 100 and providing a second mold layer with through holes on the side of the second seed layer 201 facing away from the upper substrate 200;
step b30, forming a first metal bump 102 in the through hole of the first mold layer 110 by electroplating method, and forming a first concave part 104 on the side of the first metal bump 102 away from the first seed layer 101 by controlling the concentration of the additive in the electroplating solution; forming a second metal bump 202 in the through hole of the second mold layer;
step b40, forming an intermediate metal layer 103 on the side of the second metal bump 202 away from the second seed layer 201 by using an electroplating method;
the steps b10 to b40 are the same as the steps a10 to a40, and reference is made to the above steps for specific implementation, which is different from the above steps in that the side of the second metal bump 202 away from the second seed layer 201 is a plane in this embodiment, so as to facilitate the formation of the intermediate metal layer 103 on the plane by an electroplating method. The intermediate metal layer 103 is also formed by controlling the composition and concentration of the plating solution, and using a current matched thereto as a plating waveform.
Step b50, removing the first mold layer 110 and the second mold layer;
step b60, removing the first seed layer 101 and the second seed layer 201;
step b70, reflowing the upper substrate 200 at high temperature to form the convex portion 204 matching the first concave portion 104 on the intermediate metal layer 103;
step b80, aligning and contacting the convex portion 204 with the first concave portion 104, and bonding the first metal bump 102 with the second metal bump 202 using bonding pressure and high temperature.
The steps b50 to b80 are the same as the steps a50 to a80, and will not be described in detail, and the steps a50 to a80 can be referred to for specific implementation.
The invention further provides a bonding mechanism of a metal bump, as shown in fig. 7 and fig. 9, the bonding mechanism of a metal bump includes a lower substrate 100 and an upper substrate 200, a first seed layer 101 is disposed on one side of the lower substrate 100, a first metal bump 102 is disposed on one side of the first seed layer 101 away from the lower substrate 100, a first concave portion 104 is formed on one side of the first metal bump 102 away from the first seed layer 101, and an intermediate metal layer 103 is disposed on the first concave portion 104.
It should be noted here that the number of the first metal bumps 102 may be one or multiple, and the multiple first metal bumps 102 are arranged in an array to form a first metal bump array.
A second seed layer 201 is arranged on one side of the upper substrate 200, a second metal bump 202 is arranged on one side of the second seed layer 201, which is away from the upper substrate 200, the edge of one side of the second metal bump 202, which is away from the second seed layer 201, is in contact with the edge of the first concave part 104 to form a closed cavity, and the intermediate metal layer 103 in the first concave part 104 bonds the first metal bump 102 with the second metal bump 202.
It should be noted here that the number of the second metal bumps 202 may be one or multiple, and the multiple second metal bumps 202 are arranged in an array and correspond to the positions of the first metal bumps 102 one by one.
According to the embodiment of the invention, the width of the second metal bump 202 is greater than the width of the first metal bump 102, so that when the second metal bump 202 abuts against the edge of the first concave portion 104, the closed cavity can be completely closed.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (9)

1. A bonding method of a metal bump is characterized by comprising the following steps:
a10, arranging a first seed layer on one side of a lower substrate and a second seed layer on one side of an upper substrate;
a20, arranging a first mould layer with a through hole on one side of the first seed layer, which is far away from the lower substrate, and arranging a second mould layer with a through hole on one side of the second seed layer, which is far away from the upper substrate;
a30, forming a first metal bump in the through hole of the first mould layer by using an electroplating method, and forming a first concave part on the side of the first metal bump, which is far away from the first seed layer, by controlling the concentration of an additive in an electroplating solution; forming a second metal bump in the through hole of the second mold layer, and forming a convex part on one side of the second metal bump, which is far away from the second seed layer;
a40, forming an intermediate metal layer in the first concave part by using an electroplating method, wherein a second concave part is formed on one side of the intermediate metal layer, which is far away from the first metal bump;
a step a50 of removing the first mold layer and the second mold layer;
a step 60, removing the first seed layer and the second seed layer;
a70, reflowing the lower substrate at high temperature, and controlling the heating speed of reflow to make the center thickness of the middle metal layer larger than the edge thickness;
step a80, aligning and contacting the convex part of the second metal bump with the second concave part of the first metal bump, and applying bonding pressure and temperature to bond the first metal bump with the second metal bump.
2. The method for bonding a metal bump according to claim 1, wherein the width of the second metal bump is greater than the width of the first metal bump.
3. The method for bonding a metal bump according to claim 1, wherein the height of the center of the second recess is lower than the height of the edge of the first recess.
4. The method for bonding a metal bump according to claim 1, wherein a difference in height between an edge of the convex portion and a center of the convex portion is smaller than a difference in height between an edge of the first concave portion and a center of the first concave portion.
5. The method as claimed in claim 1, wherein the intermediate metal layer is made of tin, the first metal bump and the second metal bump are made of copper, and the first mold layer and the second mold layer are made of polymer materials.
6. A bonding method of a metal bump is characterized by comprising the following steps:
b10, arranging a first seed layer on one side of the lower substrate and a second seed layer on one side of the upper substrate;
step b20, arranging a first mould layer with a through hole on one side of the first seed layer, which is far away from the lower substrate, and arranging a second mould layer with a through hole on one side of the second seed layer, which is far away from the upper substrate;
b30, forming a first metal bump in the through hole of the first mould layer by using an electroplating method, and forming a first concave part on the side of the first metal bump, which is far away from the first seed layer, by controlling the concentration of an additive in an electroplating solution; forming a second metal bump in the through hole of the second mold layer;
step b40, forming an intermediate metal layer on one side of the second metal bump, which is far away from the second seed layer, by using an electroplating method;
step b50, removing the first mold layer and the second mold layer;
step b60, removing the first seed layer and the second seed layer;
step b70, reflowing the upper substrate at high temperature to form a convex part matching the first concave part on the intermediate metal layer;
step b80, aligning and contacting the convex part with the first concave part, and applying bonding pressure and temperature to bond the first metal bump and the second metal bump.
7. A bonding mechanism of a metal bump is characterized by comprising:
the device comprises a lower substrate, wherein a first seed layer is arranged on one side of the lower substrate, a first metal bump is arranged on one side, away from the lower substrate, of the first seed layer, a first concave part is formed on one side, away from the first seed layer, of the first metal bump, and an interlayer metal is arranged in the first concave part;
the metal bump structure comprises an upper substrate, wherein a second seed layer is arranged on one side of the upper substrate, a second metal bump is arranged on one side, away from the upper substrate, of the second seed layer, the edge of one side, away from the second seed layer, of the second metal bump is in contact with the edge of a concave portion of the first metal bump to form a closed cavity, and the first metal bump and the second metal bump are bonded through a middle metal layer in the first concave portion.
8. The metal bump bonding mechanism of claim 7 wherein the width of the second metal bump is greater than the width of the first metal bump.
9. The bonding mechanism of metal bumps as claimed in claim 7 or 8, wherein the melting point of the intermediate metal layer is lower than the melting points of the first metal bump and the second metal bump.
CN202110572516.3A 2021-05-25 2021-05-25 Bonding method and bonding mechanism of metal bumps Pending CN113471090A (en)

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