Ultrasonic bonding method and ultrasonic bonding apparatus

Abstract

The problem addressed by the present invention is to provide an ultrasonic bonding device capable of protecting an element from ultrasonic vibrations. In order to solve the above problem, an ultrasonic bonding method in which an element (3) is pressed by a bonding tool (4) and ultrasonically bonded to a substrate (2), a resin sheet (6) is disposed and bonded between the bonding tool (4) and the element (3). An ultrasonic bonding device (1) for ultrasonically bonding an element (3) to a substrate (2) by pressing the element (3) with a bonding tool (4) is provided with a resin sheet (6) disposed between the bonding tool (4) and the element (3).

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic bonding method and an ultrasonic bonding apparatus. Background Art

[0002] Conventionally, when bonding components such as semiconductor chips to a substrate by ultrasonic bonding, wire bonding using a wire such as aluminum and bump bonding in which electrode materials are brought into contact and vibrated to bond are known (for example, refer to Patent Document 1).

[0003] [Prior Art Documents]

[0004] (Patent Document)

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2007-19436 Summary of the Invention

[0006] When an element is to be bonded to a substrate using ultrasonic bonding, since the bonding tool transmits ultrasonic vibrations to the element, it is necessary to protect the element from the influence of the vibrations.

[0007] [Means for Solving the Problems]

[0008] (1) The present invention relates to an ultrasonic bonding method in which a bonding tool (for example, bonding tool 4) presses an element (for example, element 3) and performs ultrasonic bonding with a substrate, and a resin sheet (for example, resin sheet 6) is disposed and bonded between the bonding tool and the element.

[0009] (2) Preferably, the element is formed with corners, the outer shape of the bonding tool is larger than the outer shape of the element, and two or more of the corners of the element are fixedly bonded using the bonding tool.

[0010] (3) The present invention relates to an ultrasonic bonding apparatus (for example, ultrasonic bonding apparatus 1) that presses an element with a bonding tool and performs ultrasonic bonding with a substrate, and includes a resin sheet disposed between the bonding tool and the element.

[0011] (4) Preferably, the element is formed with corners, and the outer shape of the bonding tool is larger than the outer shape of the element.

[0012] [Advantages of the Invention]

[0013] According to the above (1), when pressing the element with the bonding tool, a resin sheet is disposed between the bonding tool and the upper surface of the element, thereby being able to mitigate the influence of the vibration of the bonding tool on the vibration generated on the upper surface of the element. For example, it is possible to suppress the generation of scratches or marks on the upper surface of the element. In addition, sometimes the surface where the bonding tool contacts the element 3 may be offset, but since the resin sheet can capture the element to prevent it from moving, it is possible to easily perform the alignment of the bonding tool with the element and the protective member disposed on the element.

[0014] According to the above (2), the bonding tool 4 itself is used to fix the square element, and ultrasonic bonding of the element can be directly performed using the bonding tool without including bumps or wires, etc. In addition, if it is configured to suppress the corners of the element using the bonding tool, compared with the case of, for example, placing the bonding tool in the frame of the protective member to press the element, the area where the pressing force of the bonding tool is applied to the surface of the element can be expanded. Therefore, the bonding area between the bonding tool and the element can be increased. Further, by fixing two or more corners of the element 3 using the bonding tool 4, the element 3 can be stably held.

[0015] According to the above (3), when pressing the element with the bonding tool, a resin sheet is disposed between the bonding tool and the upper surface of the element, thereby being able to mitigate the influence of the vibration of the bonding tool on the vibration generated on the upper surface of the element. For example, it is possible to suppress the generation of scratches or marks on the upper surface of the element. In addition, sometimes the surface where the bonding tool contacts the element 3 may be offset, but since the resin sheet can capture the element to prevent it from moving, it is possible to easily perform the alignment of the bonding tool with the element and the protective member disposed on the element.

[0016] According to the above (4), the bonding tool 4 itself is used to fix the square element, and ultrasonic bonding of the element can be directly performed using the bonding tool without including bumps or wires, etc. In addition, if it is configured to suppress the corners of the element using the bonding tool, compared with the case of, for example, placing the bonding tool in the frame of the protective member to press the element, the area where the pressing force of the bonding tool is applied to the surface of the element can be expanded. Therefore, the bonding area between the bonding tool and the element can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic longitudinal sectional view of the ultrasonic bonding apparatus according to the first embodiment.

[0018] Figure 2 is a schematic longitudinal sectional view of the bonding tool according to the first embodiment.

[0019] Figure 3 is along Figure 1 the schematic cross-sectional view taken along line A - A of DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. As Figure 1 shown, the ultrasonic bonding device 1 is a device having an ultrasonic vibrator, an arm-shaped horn, a base (not shown) for placing an object to be bonded, a bonding tool 4, a protection member 5, and a resin sheet 6, and bonding the objects to be bonded by ultrasonic vibration. The ultrasonic bonding device 1 vibrates the ultrasonic vibrator by applying electricity, thereby bonding the contact surfaces of metals to each other. The horn (not shown) transmits while expanding the vibration amplitude of the ultrasonic wave. The bonding tool 4 is connected to the front end of the horn, and ultrasonic vibration is transmitted to the bonding tool 4 via the horn. The object to be bonded by the ultrasonic bonding device 1 is not particularly limited as long as it is a metal component, but in this embodiment, it is the substrate 2 and the element 3 of the semiconductor chip. The bonding tool 4 ultrasonically bonds to the substrate while pressing the element 3.

[0021] The substrate 2 can be, for example, a mounting substrate such as a DCB (Direct Bond Copper), a substrate in which a copper material is directly pasted on a ceramic substrate.

[0022] The element 3 has an element body 30, an upper metal surface 31, and a lower metal surface 32, and is configured in a layered manner. The element body 30 is made of, for example, SiC (silicon carbide). The upper metal surface 31 is an electrode disposed on the upper surface of the element body 30. The lower metal surface 32 is an electrode disposed on the lower surface of the element body 30. The element 3 is pressed by the bonding tool 4, and the lower metal surface 32 is bonded to the substrate 2. The element 3 is formed in a square shape with corners, specifically, has a shape of a relatively thin approximate rectangular parallelepiped.

[0023] As Figure 1 shown, the protection member 5 is a resin member disposed on the upper surface of the upper metal surface 31 of the element 3. The protection member 5 is made of, for example, polyimide, and is disposed to suppress damage or traces on the upper surface of the element 3 due to the vibration of the bonding tool 4. The protection member 5 is disposed on the outer peripheral edge of the upper metal surface 31 of the element 3 and is formed in a frame shape. The thickness of the protection member 5 is thinner than the thickness of the element 3. The length of each side of the frame of the protection member 5 has a length substantially equal to the length of each side of the element 3.

[0024] In this embodiment, the bonding tool 4 has a prismatic shape, and the outer dimension of the bonding tool 4 is larger than the outer dimension of the element 3 in a plan view. That is, the end portion on the lower end side of the bonding tool has a side longer than the length of the side of the element 3 and has an area larger than the area of the upper surface of the element 3. In addition, as Figure 1 and Figure 2 shown, the bonding tool 4 is formed to have a recess 40 that can fix the element 3 and the protection member 5 therein. The recess 40 has a first recess 41 and a second recess 42.

[0025] The first recess 41 is a hole that is recessed upward from the lower end of the bonding tool 4, and is formed to have a size slightly larger than the outer shape of the element 3 so as to be able to cover the element 3. As Figure 3 shown, the first recess 41 is formed in a quadrilateral shape in a plan view from the outer edge of the bonding tool 4 toward the inside.

[0026] The second recess 42 is a box-shaped hollow space that is continuously formed above the first recess 41 and the first recess 41 in the bonding tool 4. The second recess 42 is formed to have a size capable of accommodating the protective member 5 disposed on the upper surface of the element 3 therein. As Figure 2 shown, in a cross-sectional view, it is formed to project upward from the lower end side of the bonding tool 4 along the outer edge of the first recess 41 with a width slightly larger than the width of each side of the protective member 5.

[0027] As Figure 1 shown, the depth of the recess 40 formed by combining the first recess 41 and the second recess 42, that is, the depth dimension D1 of the side wall 44 of the recess 40 from the lower end surface of the bonding tool 4 to the surface on the base end side of the bonding tool 4 in the second recess 42, is configured to be a size capable of accommodating the resin sheet 6, the protective member 5, the upper metal surface 31, and the upper part of the element body 30, which will be described later, inside. When specifying the depth dimension D1 of the recess 40, it is obtained on the basis of setting the distance D2 between the bonding tool 4 and the substrate 2 to give an appropriate pressing force to the bonding of the substrate 2 and the element 3.

[0028] The resin sheet 6 is a soft sheet made of resin. As Figure 1 shown, the resin sheet 6 is disposed between the element 3 and the bonding tool 4 so as to cover both the upper metal surface 31 of the element 3 and the upper surface of the protective member 5. In addition, in Figure 3 , since the resin sheet 6 overlaps the element 3 and the protective member 5, it is omitted. The resin sheet 6 has a cross-sectional shape with irregularities formed along the protective member 5 and the upper metal surface 31. Specifically, the resin sheet 6 is formed in a quadrilateral shape in a plan view, and has an outer edge portion 61, a stepped portion 62, and a central recess 63. The outer edge portion 61 is a portion that extends inward from the outer edge side of the resin sheet 6 by an amount equal to the width of each side of the box-shaped protective member 5, and is formed in a frame shape in a plan view. The stepped portion 62 is a portion that bends downward from the inner end of the outer edge portion 61. The central recess 63 is an inner quadrilateral portion surrounded by the outer edge portion 61, and is located below the portion closer to the stepped portion 62 than the outer edge portion 61. The resin sheet 6 is made of, for example, a polyimide film.

[0029] As Figure 1As shown, an element 3 is disposed on a substrate 2, and a protective member 5 is disposed on the upper metal surface 31 of the element 3, and a resin sheet 6 is overlapped so as to cover the protective member 5 and the upper metal surface 31. Then, a joining tool 4 is brought close in such a manner that these laminates are inserted into a recess 40. As Figure 3 shown, by inserting into a first recess 41 and a second recess 42, the resin sheet 6, the protective member 5, and the element 3, four corners of the element 3, the protective member 5, and the resin sheet 6 are fixed by using a corner of the second recess 42 formed on the joining tool 4 and side walls 44 of the second recess 42 and the first recess 41 hanging down from the corner. In this state, an ultrasonic joining device 1 is applied, and ultrasonic vibration is transmitted to the substrate 2 and the element 3. After that, with the resin sheet 6 disposed between the joining tool 4 and the element 3, a joining surface 7 between the substrate 2 and the element 3 is joined.

[0030] According to the present embodiment, the following effects are achieved.

[0031] (1) The ultrasonic joining method is configured to press the element 3 with the joining tool 4 and perform ultrasonic joining with the substrate 2, and is configured to dispose and join the resin sheet 6 between the joining tool 4 and the element 3. When pressing the element 3 with the joining tool 4, the resin sheet 6 is disposed between the upper surfaces of the joining tool 4 and the element 3, so that the influence of the vibration of the joining tool 4 on the upper surface of the element 3 can be alleviated. For example, it is possible to suppress the generation of scratches or marks on the upper surface of the element 3. In addition, sometimes the surface where the joining tool 4 contacts the element 3 may be offset, but since the element 3 can be captured by the resin sheet 6 to prevent it from moving, the alignment of the joining tool 4 with the element 3 and the protective member 5 disposed on the element 3 can be easily performed.

[0032] (2) According to the present embodiment, the element 3 is formed to have corners, and the outer shape of the joining tool 4 is made larger than the outer shape of the element 3. Two or more corners of the element 3 are fixed by the joining tool 4 for joining. By directly using the joining tool 4 to perform ultrasonic joining on the element 3 without including bumps or wires, etc., the element 3 can be fixed by the joining tool 4 itself. In addition, if it is configured to suppress the corners of the element 3 with the joining tool 4, compared with the case where, for example, the joining tool 4 is placed in a frame of the protective member 5 to press the element 3, the area where the pressing force of the joining tool 4 is applied to the surface of the element 3 can be expanded. Therefore, the joining area between the joining tool 4 and the element 3 can be increased. Further, by fixing two or more corners of the element 3 with the joining tool 4, the element 3 can be stably held.

[0033] (3) According to the present embodiment, the ultrasonic bonding device 1 is configured to press the element 3 with the bonding tool 4 and perform ultrasonic bonding with the substrate 2. It is configured to include a resin sheet 6 disposed between the bonding tool 4 and the element 3. When pressing the element with the bonding tool, by disposing the resin sheet between the bonding tool and the upper surface of the element, the influence of the vibration of the bonding tool on the upper surface of the element can be mitigated. For example, it is possible to suppress the generation of scratches or marks on the upper surface of the element. In addition, sometimes the surface of the bonding tool that contacts the element 3 may shift, but since the resin sheet can capture the element and prevent it from moving, it is possible to easily align the bonding tool with the element and the protective component disposed on the element.

[0034] (4) According to the present embodiment, the element 3 is formed with corners, and the outer shape of the bonding tool 4 is made larger than the outer shape of the aforementioned element. By using the bonding tool 4 itself to fix the square element, ultrasonic bonding of the element can be directly performed with the bonding tool without including bumps or wires, etc. In addition, if it is configured to suppress the corners of the element with the bonding tool, compared with the case of, for example, placing the bonding tool in the frame of the protective component to press the element, the area where the pressing force of the bonding tool is applied to the surface of the element can be enlarged. Therefore, the bonding area between the bonding tool and the element can be increased.

[0035] In addition, the present invention is not limited to the above-described embodiment, and deformations, improvements, etc. within the scope where the object of the present invention can be achieved are included in the present invention. In the above-described embodiment, the four corners of the element 3, the protective component 5, and the resin sheet 6 are fixed by the concave portion 40 of the bonding tool 4. However, the shapes of the concave portion and the element are not limited to the shapes described above. In the above-described embodiment, the element 3 is formed in a quadrilateral shape, but as long as it has a shape with corners, it is not limited to a quadrilateral shape. It can also be a polygon such as a triangle, pentagon, hexagon, etc.

[0036] In addition, in the above-described embodiment, a concave portion 40 is formed on the lower end surface of the bonding tool 4 and a laminate covering the element 3 and the protective component 5 with the resin sheet 6 is held, but it is not limited to this configuration. For example, it can also be configured to form a protrusion from the lower end surface of the bonding tool 4 and suppress the corners of the laminate of the element, the protective component, and the resin sheet with the protrusion. At this time, it is not limited to four corners, and as long as two or more corners are suppressed.

[0037] Reference numerals

[0038] 1... Ultrasonic bonding device

[0039] 2... Substrate

[0040] 3... Element

[0041] 4... Bonding tool

[0042] 6... Resin sheet

Claims

1. An ultrasonic bonding method, which uses a bonding tool to press an element and perform ultrasonic bonding with a substrate, A resin sheet is disposed and bonded between the bonding tool and the element.

2. The ultrasonic bonding method according to claim 1, wherein The element is formed with corners, The outer shape of the bonding tool is larger than the outer shape of the element, Two or more of the corners of the element are fixedly bonded using the bonding tool.

3. An ultrasonic bonding apparatus, which uses a bonding tool to press an element and perform ultrasonic bonding with a substrate, and includes a resin sheet disposed between the bonding tool and the element.

4. The ultrasonic bonding apparatus according to claim 3, wherein The element is formed with corners, The outer shape of the bonding tool is larger than the outer shape of the element.

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