Bonding structures and methods of forming the same

Abstract

A bonding structure and a method of forming the same are provided. The bonding structure includes a first line layer, a first bonding metal layer disposed on the first line layer and having a first bonding surface, and a first dielectric material covering a portion of an upper surface of the first bonding metal layer and exposing the first bonding surface, wherein the first dielectric material provides a second bonding surface higher than the first bonding surface to form a step difference with the first bonding surface.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically, to a bonding structure. Background Technology

[0002] When using hybrid bonding for die-to-wafer (DtW) or wafer-to-wafer (WtW) bonding, the metal interface, such as copper-to-copper bonding, is designed with a bump-and-recessed structure to address the problem of deteriorated electrical connectivity caused by bonding shift. The bump-and-recessed structure design mitigates bonding shift because when a small amount of bonding shift occurs, the raised portion slides into the bottom of the recess by contacting its sidewall, thus reducing the probability of bonding shift.

[0003] However, if CMP is used to grind a single-sided metal (e.g., copper) surface to create a dimple, the cost is high (it requires grinding fluid), and the depth of the dimple after grinding is not easy to control. Summary of the Invention

[0004] To address the aforementioned problems in related technologies, this invention proposes a bonding structure that can alleviate the high cost and difficulty in controlling the recess depth caused by conventional CMP polishing of metal surfaces.

[0005] According to an embodiment of the present invention, a bonding structure is provided, comprising: a first circuit layer; a first bonding metal layer disposed on the first circuit layer and having a first bonding surface; and a first dielectric material covering a portion of the upper surface of the first bonding metal layer and exposing the first bonding surface, wherein the first dielectric material provides a second bonding surface, the second bonding surface being higher than the first bonding surface to form a step difference with the first bonding surface.

[0006] In the above-described bonding structure, the first bonding metal layer has a tapered shape.

[0007] In the above bonding structure, the first bonding metal layer has a maximum width and a minimum width that is less than the maximum width, with the maximum width being closer to the first circuit layer and the minimum width being farther away from the first circuit layer.

[0008] In the above-described bonding structure, the first dielectric material has a side surface connected between the first bonding surface and the second bonding surface, and the side surface forms an angle with the upper surface of the first bonding metal layer, the angle being greater than or equal to 20 degrees and less than 90 degrees.

[0009] The above-described bonding structure further includes: a second circuit layer; a second dielectric material covering and exposing a portion of the second circuit layer; and a second bonding metal layer disposed on the exposed second circuit layer and protruding beyond the second dielectric material.

[0010] In the above-described bonding structure, the second bonding metal layer is connected to the first bonding metal layer and is surrounded by the first dielectric material.

[0011] In the above-mentioned bonding structure, the second circuit layer is made of nanotwinned copper material.

[0012] In the above-described bonding structure, the second circuit layer has a horizontal crystal image.

[0013] The above-mentioned bonding structure also includes a third circuit layer disposed on the second circuit layer, the third circuit layer comprising a negative thermal expansion (NTE) material.

[0014] According to an embodiment of the present invention, a bonding structure is also provided, comprising: a second circuit layer; a second bonding metal layer disposed on the second circuit layer, wherein the second bonding metal layer comprises a first material and a second material, the second material being located between the first material and the second circuit layer; and a second dielectric material, the first material being located on the lower surface of the second dielectric material.

[0015] In the above-mentioned bonding structure, the second material is nanotwinned copper material.

[0016] In the above-described bonding structure, the second material has a horizontal crystal image.

[0017] In the above-described bonding structure, the second circuit layer comprises a negative thermal expansion (NTE) material.

[0018] In the above-described bonding structure, the second material connects the second circuit layer to the first material.

[0019] The above-described bonding structure further includes: a first bonding metal layer; and a first dielectric material covering a portion of the upper surface of the first bonding metal layer and surrounding the first material.

[0020] According to an embodiment of the present invention, a method for forming a bonding structure is also provided, comprising: forming a first opening in a first dielectric material; forming a first bonding metal material within the first opening and forming a first circuit layer above a first surface of the first bonding metal material; forming a recess defined by the first dielectric material on a second surface of the first bonding metal material opposite to the first surface; and bonding a second bonding metal material having a protruding first material to the first bonding metal material, wherein the protruding first material is located in the recess.

[0021] The above method further includes: forming a second opening in the second dielectric material and forming a second bonding metal material in the second opening; forming a second circuit layer on a first surface of the second bonding metal material; and forming a first material protruding from the second dielectric material on a second surface of the second bonding metal material opposite to the first surface.

[0022] In the above method, the second material is nanotwinned copper material.

[0023] In the above method, the second material has a horizontal crystal image.

[0024] In the above method, the second circuit layer includes a negative thermal expansion (NTE) material. Attached Figure Description

[0025] The various aspects of the invention can be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, in accordance with standard industrial practice, the various components are not drawn to scale and are for illustrative purposes only. In fact, for clarity of discussion, the dimensions of the various components may be arbitrarily increased or decreased.

[0026] Figure 1 This is a schematic diagram of the joining structure before joining according to an embodiment of the present invention.

[0027] Figure 2A This is a schematic diagram of the joining structure after joining according to an embodiment of the present invention.

[0028] Figure 2B yes Figure 2A A partially enlarged schematic diagram of the joint structure.

[0029] Figures 3A to 3P This is a schematic diagram of various stages of a method for forming a joint structure according to an embodiment of the present invention. Detailed Implementation

[0030] The following disclosure provides numerous different embodiments or instances for implementing various features of the provided subject matter. Specific examples of elements and arrangements will be described below to simplify the invention. These are merely examples and are not intended to limit the invention. For example, in the following description, forming a first component above or on a second component can include embodiments where the first and second components are in direct contact, or embodiments where an additional component is formed between the first and second components such that the first and second components are not in direct contact. Furthermore, reference numerals and / or letters may be repeated throughout the various instances. Such repetition is for brevity and clarity only and does not in itself indicate a relationship between the various embodiments and / or configurations discussed.

[0031] According to an embodiment of the present invention, a bonding structure is provided, comprising: a first circuit layer; a first bonding metal layer disposed on the first circuit layer and having a first bonding surface; and a first dielectric material covering a portion of the upper surface of the first bonding metal layer and exposing the first bonding surface, wherein the first dielectric material provides a second bonding surface, the second bonding surface being higher than the first bonding surface to form a step difference with the first bonding surface.

[0032] Figure 1This is a schematic diagram of the joining structure according to an embodiment of the present invention before joining. Figure 1 As shown, a first bonding metal layer 112 is disposed on a first circuit layer 114. The first bonding metal layer 112 has a first bonding surface 115. In some embodiments, the material of the first bonding metal layer 112 is, for example, copper. The first circuit layer 114 is located in a first dielectric material 120. The first dielectric material 120 covers a portion of the upper surface of the first bonding metal layer 112 and exposes the first bonding surface 115. The first bonding surface 115 is for bonding with another metal layer (such as a second bonding metal layer 142). The first dielectric material 120 provides a second bonding surface 116. The second bonding surface 116 is for bonding with another dielectric material (such as a second dielectric material). The second bonding surface 116 is higher than the first bonding surface 115 to form a step difference with the first bonding surface 115. Thus, a recess 119 is defined on the upper surface of the first bonding metal layer 112 by the first dielectric material 120. This avoids the need to use CMP to grind the metal surface to create a recess defined by the metal in order to solve the bonding displacement, thus reducing costs compared to conventional processes, and the depth of the recess 119 defined by the first dielectric material 120 is easier to control.

[0033] Continue to refer to Figure 1 As shown, the first dielectric material 120 has a side surface 117 connecting the first bonding surface 115 and the second bonding surface 116. The side surface 117 forms an angle α with the upper surface of the first bonding metal layer 112, such that the width of the recess 119 gradually increases in the direction from the upper surface of the first bonding metal layer 112 to the upper surface of the first dielectric material 120. The angle α ranges from greater than or equal to 20 degrees to less than 90 degrees. In other embodiments, the angle α can be any other suitable angle value.

[0034] The first bonding metal layer 112 may have a tapered shape. Specifically, the first bonding metal layer 112 has a maximum width and a minimum width smaller than the maximum width, with the maximum width close to the first circuit layer 114. The first bonding metal layer 112 may contact the first circuit layer 114 at its maximum width. The minimum width of the first bonding metal layer 112 is away from the first circuit layer 114. The first bonding metal layer 112 may have a minimum width at its upper surface.

[0035] In addition, such as Figure 1As shown, a second bonding metal layer 142 is disposed on the surface of the second circuit layer 144. The second circuit layer 144 is located within the second dielectric material 140. The second dielectric material 140 may be the same as the first dielectric material 120, or it may be different from the first dielectric material 120. The second bonding metal layer 142 is disposed on the surface of the second circuit layer 144. The second bonding metal layer 142 protrudes from the second dielectric material 140 in a direction toward the first bonding metal layer 112 to bond with the first bonding metal layer 112 via a recess 119.

[0036] The second bonding metal layer 142 may include a first material 1411 and a second material 1412. The second material 1412 is located between the first material 1411 and the second circuit layer 144. The first material 1411 is located below the surface of the second dielectric material 140 facing the first dielectric material 120, that is, the first material 1411 of the second bonding metal layer 142 protrudes from the second dielectric material 140. In some embodiments, the first material 1411 may be copper. In some embodiments, the second material 1412 may be a nanotwinned copper material. The nanotwinned copper material may have a horizontal crystal image.

[0037] Furthermore, the second circuit layer 144 may include a negative thermal expansion (NTE) material 1441. The NTE material 1441 may also be referred to as the third circuit layer. The second material 1412 connects the second circuit layer 144 and the first material 1411.

[0038] Figure 2A This is a schematic diagram of the joining structure after joining according to an embodiment of the present invention. Figure 2B yes Figure 2A A partially enlarged schematic diagram of the joint structure. (See attached diagram.) Figure 2A As shown, after the first bonding metal layer 112 and the second bonding metal layer 142 are bonded, the second bonding metal layer 142 is connected to the first bonding metal layer 112, and the portion of the second bonding metal layer 142 protruding from the second dielectric material 140 is surrounded by the first dielectric material 120. In some embodiments, after the first bonding metal layer 112 and the second bonding metal layer 142 are bonded, the second bonding metal layer 142 may fill the recess defined by the first dielectric material 120. In some embodiments, such as Figure 2B As shown, when heated, NTE material 1441 contracts, while the copper in the first material 1411 and the second material 1412 expands. The directions of contraction and expansion are as follows. Figure 2B As shown by the arrow in the image, we can obtain the following: Figure 2B The structure shown.

[0039] According to an embodiment of the present invention, a method for forming a joint structure is also provided. Figures 3A to 3PThis is a schematic diagram of various stages of a method for forming a joint structure according to an embodiment of the present invention.

[0040] like Figure 3A As shown, a first carrier 101 is provided, and a metal layer 131 is coated on the surface of the first carrier 101. In some embodiments, the material of the metal layer 131 may be, for example, copper. Then, as... Figure 3B As shown, a first dielectric material 120 is formed on the metal layer 131, and a first opening 134 is formed in the first dielectric material 120. The first opening 134 exposes a portion of the surface of the underlying metal layer 131.

[0041] like Figure 3C As shown, the material forming the first bonding metal layer 112 in the first opening 134, the first bonding metal layer 112 may be, for example, copper. Figure 3D As shown, a first circuit layer 114 is formed over the first dielectric material 120 and the first bonding metal layer 112, and is bonded to the first bonding metal layer 112. The first circuit layer 114 may be covered by a dielectric material that is the same as or different from the first dielectric material 120. Then the first carrier is removed, and the resulting structure is inverted to obtain the structure shown. Figure 3E The structure is shown. After the first carrier is removed, the surface of the first bonding metal is exposed by the first dielectric material 120.

[0042] like Figure 3F As shown, an additional first dielectric material 120 is formed on the surfaces of the first dielectric material 120 and the first bonding metal layer 112, such that the surface of the first dielectric material 120 is raised above and covers the surface of the first bonding metal layer 112. Then, the portion of the first dielectric material 120 covering the first bonding metal is removed. Thus, a recess 119 is formed in the first dielectric material 120 that exposes the surface of the first bonding metal.

[0043] On the other hand, such as Figure 3G As shown, a second carrier 102 is provided, and a metal layer 151 is coated on the surface of the second carrier 102. The material of the metal layer 151 can be, for example, copper. Then, as... Figure 3H As shown, a second dielectric material 140 is formed on the metal layer 151, and a second opening 154 is formed in the second dielectric material 140. The second opening 154 exposes a portion of the surface of the underlying metal layer 151.

[0044] like Figure 3I As shown, a metallic material 1412 (i.e., the aforementioned second material 1412) is formed in the second opening 154. This metallic material 1412 can be, for example, a nanotwinned copper material. Then, as... Figure 3JAs shown, a patterned photoresist layer 150 is formed over the second dielectric material 140. The patterned photoresist layer 150 has a third opening 155 that exposes the metal material 1412 in the second dielectric material 140.

[0045] like Figure 3K As shown, a material 1441, such as NTE, is conformally covered on the patterned photoresist layer 150 and within the third opening 155. Figure 3L As shown, the NTE material 1441 covering the patterned photoresist layer 150 and its sidewalls is removed, while the NTE material 1441 is retained on at least a portion of the surface of the metal material 1412.

[0046] like Figure 3M As shown, a second circuit layer 144 is formed over the second dielectric material 140. The second circuit layer 144 may be covered by a dielectric material that is the same as or different from the second dielectric material 140. Then the second carrier 102 is removed, and the resulting structure is inverted to obtain the structure shown. Figure 3N The structure shown.

[0047] Then, as Figure 3O As shown, a patterned photoresist layer pattern 162 is formed. The patterned photoresist pattern 162 is located above the metal layer 151 above the metal material 1412. Figure 3P As shown, the portion of the metal layer 151 not covered by the photoresist pattern 162 can be removed by an etching process. Then, the patterned photoresist pattern 162 is removed, and a metal layer 151 (i.e., the aforementioned first material 1411) protruding above the metal material 1412 is formed. The metal layer 151 protruding above the second dielectric material 140 and the metal material 1412 can be collectively referred to as the second bonding metal layer 142.

[0048] Subsequently, the second bonding metal layer 142 can be connected to... Figure 3F The first bonding metal layer 112 is bonded. When a slight bonding displacement occurs, the metal layer 11 protruding from the second dielectric material 140 can slide into the bottom of the recess 119 by contacting the sidewall of the recess 119, thus reducing the probability of bonding displacement. Furthermore, since the formation process of the recess 119 does not use CMP, the cost can be reduced compared to conventional processes, and the depth of the recess 119 defined by the first dielectric material 120 is easier to control.

[0049] The foregoing summary outlines features of several embodiments that enable those skilled in the art to better understand various aspects of this disclosure. Those skilled in the art should understand that other processes and structures can be readily designed or modified based on this invention to achieve the same objectives and / or benefits as the embodiments described herein. Those skilled in the art should also recognize that these equivalent structures do not depart from the spirit and scope of the invention, and that various changes, substitutions, and modifications can be made without departing from the spirit and scope of the invention.

Claims

1. A joining structure, characterized in that, include: First line layer; A first bonding metal layer is disposed on the first circuit layer and has a first bonding surface; A first dielectric material covers a portion of the upper surface of the first bonding metal layer and exposes the first bonding surface, wherein the first dielectric material provides a second bonding surface that is higher than the first bonding surface to form a step difference with the first bonding surface, and the first bonding surface is provided with a recess defined by the first dielectric material. The second dielectric material is located above the first dielectric material; The second bonding metal layer includes a second material located in the second dielectric material and a first material connected to the second material and protruding from the second dielectric material, wherein the protruding first material is located in the recess and bonded to the first bonding surface; A third circuit layer, including a negative thermal expansion material, is disposed on the second material. The upper and lower surfaces of the second material protrude vertically outward, and the lower surface of the third circuit layer contacts the second material and is concave.

2. The joining structure according to claim 1, characterized in that, The first bonding metal layer has a tapered shape.

3. The joining structure according to claim 2, characterized in that, The first bonding metal layer has a maximum width and a minimum width smaller than the maximum width, the maximum width being closer to the first circuit layer and the minimum width being farther away from the first circuit layer.

4. The joining structure according to claim 1, characterized in that, The first dielectric material has a side surface connected between the first bonding surface and the second bonding surface, the side surface forming an angle with the upper surface of the first bonding metal layer, the angle ranging from greater than or equal to 20 degrees to less than 90 degrees.

5. The joining structure according to claim 1, characterized in that, Also includes: The second circuit layer is located in and connected to the second dielectric material.

6. The joining structure according to claim 5, characterized in that, The second bonding metal layer is connected to the first bonding metal layer and is surrounded by the first dielectric material.

7. The joining structure according to claim 5, characterized in that, The second material is nanotwinned copper material.

8. The joining structure according to claim 5, characterized in that, The second material has a horizontal crystal structure.

9. A method for forming a joint structure, characterized in that, include: A first opening is formed in the first dielectric material; A first bonding metal material is formed in the first opening and a first circuit layer is formed above the first surface of the first bonding metal material. A recess defined by the first dielectric material is formed on a second surface of the first bonding metal material opposite to the first surface; A second opening is formed in a second dielectric material, a second bonding metal material is formed in the second opening, and a third circuit layer including a negative thermal expansion material is formed on the second bonding metal material. The second bonding metal material includes a second material located in the second opening and a first material connected to the second material and protruding from the second dielectric material. The third circuit layer is located on the side of the second material opposite to the first material. The protruding first material is joined to the first bonding metal material, wherein the protruding first material is located in the recess, and after joining, the upper and lower surfaces of the second material protrude vertically outward, and the lower surface of the third circuit layer contacts the second material and is recessed.

10. The method according to claim 9, characterized in that, Also includes: A second circuit layer is formed on the first surface of the second material of the second bonding metal material; The first material protrudes from the second dielectric material on the second surface opposite to the first surface of the second material.

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