Semiconductor equipment

Abstract

To provide a semiconductor device with high reliability.SOLUTION: A semiconductor device has a metal film provided on a semiconductor chip, an insulating film with an aperture over the metal film, and a connector having a bonding material provided over the metal film in the aperture and bonded to the metal film, a bonding surface, and an annular groove provided on the bonding surface, along the outer circumference of the bonding surface and with an inner diameter not less than 60% and not more than 90% of the outer diameter, the bonding surface being bonded to the bonding material.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD

[0001] Embodiments of the present invention relate to a semiconductor device. BACKGROUND ART

[0002] A semiconductor device having a semiconductor chip such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is used for applications such as power conversion. For example, when the above-mentioned semiconductor device is a vertical MOSFET, a source electrode provided on an upper surface of the semiconductor chip is connected to, for example, a connector provided on the MOSFET. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0003] Patent Document 1 International Publication No. 2019 / 167218 SUMMARY OF INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0004] A problem to be solved by the present invention is to provide a highly reliable semiconductor device. MEANS FOR SOLVING THE PROBLEM

[0005] The semiconductor device of an embodiment comprises: a metal film provided on a semiconductor chip; an insulating film provided on the metal film and having an opening; a bonding material provided on the metal film in the opening and bonded to the metal film; and a connector having a bonding surface and an annular groove provided in the bonding surface, extending along an outer circumference of the bonding surface, and having an inner diameter that is not less than 60% and not more than 90% of an outer diameter of the annular groove, the bonding surface being bonded to the bonding material An annular groove is positioned between the bonding surface and the metal film. . BRIEF DESCRIPTION OF DRAWINGS

[0006] [Figure 1] FIG. 1 is a schematic top view of the semiconductor device of the embodiment. [Figure 2] This is a schematic diagram of the main parts of the semiconductor device according to the embodiment. [Figure 3] This is another example of a schematic diagram of the bonding surface of a semiconductor device according to an embodiment. [Figure 4] This is a schematic diagram of the main components of a comparative semiconductor device. [Modes for carrying out the invention]

[0007] Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same reference numerals will be used for identical components, and the description of components that have already been described will be omitted as appropriate.

[0008] In this specification, the upper direction in a drawing is referred to as "up" and the lower direction in a drawing as "down" to indicate the positional relationship of parts, etc. In this specification, the concepts of "up" and "down" do not necessarily refer to a relationship with the direction of gravity.

[0009] (Embodiment) The semiconductor device of the embodiment comprises a metal film provided on a semiconductor chip, an insulating film provided on the metal film and having an opening, a bonding material provided on the metal film within the opening and bonded to the metal film, a bonding surface, and an annular groove provided on the bonding surface and along the outer circumference of the bonding surface, with an inner diameter of 60% to 90% of the outer diameter, wherein the bonding surface is bonded to the bonding material.

[0010] Figure 1 is a schematic top view of the semiconductor device 100 of this embodiment. Figure 2 is a schematic cross-sectional view of the main part of the semiconductor device 100 of this embodiment. Figure 2(a) is a schematic view of the A-A' section in Figure 1. Figure 2(b) is a schematic view of the bonding surface 55 of the embodiment. Figure 2(c) is another example of a schematic view of the bonding surface 55 of the embodiment. Figure 2(d) is another example of a schematic view of the bonding surface 55 of the embodiment.

[0011] The semiconductor device 100 of this embodiment will be described with reference to Figures 1 and 2.

[0012] The die pad 2 is a component containing a conductive material such as Cu (copper) on which the semiconductor chip 10 is placed. The die pad 2 has a first bed portion 3 and a first outer lead 6. The first bed portion 3 has an upper surface 4. The semiconductor chip 10 is placed on the upper surface 4. The first outer lead 6 is connected to the first bed portion 3. The first outer lead 6 is used to connect the semiconductor chip 10 to an external circuit (not shown).

[0013] Here, we define the X direction, the Y direction which intersects perpendicularly with the X direction, and the Z direction which intersects perpendicularly with both the X and Y directions. The top surface 4 is arranged parallel to the XY plane. The Y direction is an example of a first direction. The X direction is an example of a second direction.

[0014] The semiconductor chip 10 is provided on the upper surface 4 of the die pad 2. The semiconductor chip 10 is provided with a vertical MOSFET, IGBT (Insulated Gate Bipolar Transistor), or diode on a semiconductor substrate such as Si (silicon), SiC (silicon carbide), GaAs (gallium arsenide), or GaN (gallium nitride), or on a semiconductor layer such as GaN (gallium nitride) provided on a Si substrate.

[0015] The first bonding material 70 is provided between the upper surface 4 and the semiconductor chip 10. The first bonding material 70 bonds the upper surface 4 and the semiconductor chip 10. For example, if a MOSFET is provided on the semiconductor chip 10, the first bonding material 70 bonds the drain electrode of the semiconductor chip 10 (not shown) to the upper surface 4.

[0016] The first metal film 16 is provided on the semiconductor chip 10. For example, if a MOSFET is provided on the semiconductor chip 10, the first metal film 16 corresponds to the source electrode of such MOSFET. The first metal film 16 contains, for example, Al (aluminum).

[0017] The first insulating film 12 is provided on the first metal film 16. For example, the first insulating film 12 is provided on an end portion of the semiconductor chip 10 and on an end portion of the first metal film 16. The first insulating film 12 has a first opening 13. The first opening 13 penetrates through the first insulating film 12. The first insulating film 12 contains, for example, an insulating material such as silicon oxide formed from TEOS (Tetraethyl ortho-silicate) by plasma CVD (Chemical Vapor Deposition), or polyimide.

[0018] The first insulating film 12 is an example of an insulating film. The first opening 13 is an example of an opening.

[0019] The first post portion 54 includes a second bed portion 58 and a second outer lead 56. The first post portion 54 contains a conductive material such as Cu. The second outer lead 56 is used for connection between the semiconductor chip 10 and an external circuit not shown in the drawings.

[0020] The second post portion 64 includes a third bed portion 68 and a third outer lead 66. The second post portion 64 contains a conductive material such as Cu. The third outer lead 66 is used for connection between the semiconductor chip 10 and an external circuit not shown in the drawings.

[0021] The first connector (an example of a connector) 50 has a first end 50a and a second end 50b. The first end 50a has a bonding surface 55. The first connector 50 contains, for example, a conductive material such as Cu. Note that the surface of the first connector 50 may be plated with a material containing, for example, Sn. The first end 50a is provided on the first metal film 16 within the first opening 13. The second end 50b is provided on the second bed portion 58. The first connector 50 is provided extending, for example, in the Y direction across between the first post portion 54 to which the second end 50b is connected and the die pad 2.

[0022] The second metal film 18 is provided between the first end 50a of the first connector 50 and the first metal film 16 in the first opening 13. The second metal film 18 contains, for example, Ni and Au. The second metal film 18 is provided, for example, to increase the bonding strength between the second bonding material 20 and the first metal film 16.

[0023] The first metal film 16 or the second metal film 18 is an example of a metal film.

[0024] The second bonding material 20 is provided on the second metal film 18. The second bonding material 20 is provided between the second metal film 18 and the bonding surface 55 of the first end 50a. The second bonding material 20 bonds the bonding surface 55 of the first end 50a and the second metal film 18. The second bonding material 20 is an example of a bonding material.

[0025] The bonding surface 55 has an annular groove 51 along an outer periphery 57 of the bonding surface 55.

[0026] The bonding surface 55 is, for example, a flat surface. However, the bonding surface 55 does not have to be a flat surface. For example, the bonding surface 55 may be subjected to polishing treatment or the like for improving the bite property of the second bonding material 20.

[0027] FIG. 2(b) shows two annular grooves 51a and 51b. The annular groove 51b is provided outside the annular groove 51a. The annular groove 51b and the annular groove 51a are provided concentrically with each other. FIG. 2(c) shows one annular groove 51a. As described above, the bonding surface 55 may have a plurality of annular grooves 51 provided concentrically with each other. In addition, the number of the annular grooves 51 is not particularly limited.

[0028] The outer diameter of the annular groove 51 in a predetermined direction parallel to the bonding surface 55 is not less than 60% and not more than 90% of the inner diameter of the annular groove 51 in the predetermined direction parallel to the bonding surface 55.

[0029] First, let's explain using Figure 2(c), which has one annular groove 51a, as an example. The inner diameter L2 of the annular groove 51a in the X direction is 60% to 90% of the outer diameter L1 of the annular groove in the X direction. Also, the inner diameter L4 of the annular groove 51a in the Y direction is 60% to 90% of the outer diameter L3 of the annular groove 51b in the Y direction. Here, the joint surface 55 is assumed to be provided parallel to the XY plane. The X direction or Y direction is an example of a predetermined direction parallel to the joint surface 55.

[0030] Next, we will explain using Figure 2(b), which has two annular grooves 51a and annular groove 51b, as an example. In the X direction, the inner diameter L6 of the inner annular groove 51a is 60% to 90% of the outer diameter L5 of the outer annular groove 51b in the X direction. In the Y direction, the inner diameter L8 of the inner annular groove 51a is 60% to 90% of the outer diameter L7 of the outer annular groove 51b in the Y direction. Here again, the joint surface 55 is assumed to be provided parallel to the XY plane. The X direction or Y direction is an example of a predetermined direction parallel to the joint surface 55.

[0031] Similarly, if multiple annular grooves 51 are provided, the inner diameter of the innermost annular groove 51 in a predetermined direction parallel to the joint surface 55 is 60% or more and 90% or less of the outer diameter of the outermost annular groove 51 in a predetermined direction parallel to the joint surface 55.

[0032] Furthermore, it is preferable that the outer diameter of the annular groove 51 in a predetermined direction parallel to the joint surface 55 is 90% or more and less than 100% of the length of the joint surface 55 in a predetermined direction parallel to the joint surface 55.

[0033] First, let's explain using Figure 2(c), which has one annular groove 51a, as an example. Preferably, the outer diameter L1 of the annular groove 51a in the X direction is 90% or more and less than 100% of the length L10 of the joint surface 55 in the X direction. Also, preferably, the outer diameter L3 of the annular groove 51a in the Y direction is 90% or more and less than 100% of the outer diameter L11 of the annular groove 51a in the Y direction.

[0034] Next, we will explain using Figure 2(b), which has two annular grooves 51a and annular groove 51b, as an example. In the X direction, it is preferable that the outer diameter L5 of the annular groove 51b provided on the outside is 90% or more and less than 100% of the length L10 of the joint surface 55 in the X direction. In the Y direction, it is preferable that the outer diameter L7 of the annular groove 51b provided on the outside is 90% or more and less than 100% of the length L11 of the joint surface 55 in the Y direction.

[0035] Similarly, if multiple annular grooves 51 are provided, it is preferable that the outermost annular groove 51, which is parallel to the joint surface 55, has an outer diameter of 90% or more and 100% or less of the length of the joint surface 55 in a predetermined direction parallel to the joint surface 55.

[0036] The annular groove 51 is formed in a rectangular shape along the outer circumference 57 of the joint surface 55, as shown in Figure 2, for example. However, the shape of the annular groove 51 is not limited to this.

[0037] Furthermore, as shown in Figure 2(d), the corners 53 of the rectangular annular groove 51a may be chamfered.

[0038] The third joining member 59 is provided between the second bed portion 58 and the second end portion 50b. The third joining member 59 joins the second bed portion 58 and the second end portion 50b.

[0039] The second connector 60 has a third end 61a and a fourth end 61b. The second connector 60 includes, for example, a conductive material such as Cu. The surface of the second connector 60 may be plated with, for example, a material containing Sn. The third end 61a is electrically connected to the semiconductor chip 10 via a fourth bonding material 80 provided on the semiconductor chip 10. Below the fourth bonding material 80, for example, a gate electrode pad of the semiconductor chip 10 (not shown) is provided. The gate electrode pad is connected to the gate electrode of the semiconductor chip 10.

[0040] The fifth joining member 69 is provided between the third bed portion 68 and the fourth end portion 61b. The fifth joining member 69 connects the third bed portion 68 and the fourth end portion 61b.

[0041] As the first bonding material 70, the second bonding material 20, the third bonding material 59, the fourth bonding material 80, and the fifth bonding material 69, for example, solder containing Pb (lead) and Sn (tin), solder containing Pb, Ag (silver) and Sn (tin), solder containing Sn and Sb (antimony), solder containing Au (gold) and Sn, solder containing Au and Si, or solder containing Au and Ge (germanium) can be preferably used.

[0042] The thickness of the first metal film 16 is not particularly limited, but is, for example, about 4 μm. The thickness of the second metal film 18 is not particularly limited, but is, for example, about 3 μm. The thickness of the first insulating film 12 is not particularly limited, but is, for example, about 5 μm. The depth of the annular groove 51 is not particularly limited, but is, for example, several μm.

[0043] Figure 3 is another example of a schematic cross-sectional view of the semiconductor device 110 of the embodiment. Preferably, the depth d2 of the annular groove 51b provided on the outside is deeper than the depth d1 of the annular groove 51a provided on the inside.

[0044] Next, the operation and effects of the semiconductor device of this embodiment will be explained.

[0045] During the manufacturing of the semiconductor device 100, the second bonding material 20 sometimes spread to the edges of the semiconductor chip 10 and remained on top of the first insulating film 12. This remaining bonding material could cause defects in the characteristics and reliability of the semiconductor device.

[0046] Figure 4 is a schematic cross-sectional view of a semiconductor device 1000 representing a comparative embodiment. An annular groove 51 is formed across the entire surface of the bonding surface 55. In the X direction, the inner diameter L6 of the innermost annular groove 51a is less than 60% of the outer diameter L5 of the outermost annular groove 51d. In the Y direction, the inner diameter L8 of the innermost annular groove 51a is less than 60% of the outer diameter L7 of the outermost annular groove 51d.

[0047] By providing annular grooves 51 across the entire surface of the bonding surface 55 and increasing the contact area of ​​the second bonding material 20, it is possible to prevent the second bonding material 20 from remaining on top of the first insulating film 12. However, if multiple annular grooves 51 are provided on the inside, the annular grooves 51 provided on the inside are more likely to be left unfilled by the second bonding material 20, resulting in the formation of cavities. This could potentially increase the contact resistance between the bonding surface 55 and the first metal film 16. As a result, there was a risk of increasing the on-resistance of the semiconductor device.

[0048] Therefore, in the semiconductor device of this embodiment, the inner diameter of the annular groove 51 is set to 60% to 90% of the outer diameter of the annular groove 51. This allows the second bonding material 20 to spread sufficiently into the first opening 13 of the first insulating film 12, and prevents the second bonding material 20 from remaining on top of the first insulating film 12.

[0049] The annular groove 51 is preferably formed in a rectangular shape with respect to the bonding surface 55. In most cases, the semiconductor chip 10 is rectangular in shape. Therefore, by forming the annular groove 51 to match the shape of the semiconductor chip 10, the way the second bonding material 20 spreads within the first opening 13 can be easily controlled. In addition, the corners of the rectangular shape are easier to form if they are chamfered.

[0050] Furthermore, the bonding surface 55 may have a plurality of annular grooves 51. By appropriately controlling the number of annular grooves 51, it becomes easier to ensure that the second bonding material 20 spreads sufficiently into the first opening 13 of the first insulating film 12, and to prevent the second bonding material 20 from remaining on top of the first insulating film 12.

[0051] When the bonding surface 55 has multiple annular grooves 51, it is preferable that the inner diameter of the innermost annular groove 51 is 60% to 90% of the outer diameter of the outermost annular groove. This is because it is possible to sufficiently spread the second bonding material 20 into the first opening 13 of the first insulating film 12 and to prevent the second bonding material 20 from remaining on top of the first insulating film 12.

[0052] When the joint surface 55 has multiple annular grooves 51, it is preferable that the depth of the annular grooves 51 provided on the outside is greater than the depth of the annular grooves 51 provided on the inside. This is because if the inner annular grooves 51 are made deeper, the second joint material 20 will not be able to spread sufficiently into the first opening 13.

[0053] Furthermore, it is preferable that the outer diameter of the annular groove 51 be 90% or more but less than 100% of the length of the joint surface 55. Consider the case where the outer diameter of the annular groove 51 is less than 90% and there is too much second bonding material 20 placed near the first insulating film 12. In this case, the second bonding material 20 is likely to overflow onto the first insulating film 12 without entering the annular groove 51. This can be suppressed by making the outer diameter of the annular groove 51 90% or more but less than 100% of the length of the joint surface 55.

[0054] According to the semiconductor device of this embodiment, it is possible to provide a highly reliable semiconductor device.

[0055] While several embodiments and examples of the present invention have been described, these embodiments and examples are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0056] 2: Die pad 3: First bed section 4:Top surface 6: First outer lead 10: Semiconductor chips 12: First insulating film 13: First opening 16:First metal film 18:Second metal film 20:Second bonding material 50: First connector 50a: First end 50b: 2nd end 51: Ring groove 53: corner 54: First Post Section 55: Joint surface 56: Second outer lead 58: Second bed section 59:Third bonding material 60: Second connector 61a: Third end 61b: 4th end 64: Second Post Section 66: Third outer lead 68: Third Bed Section 69: 5th bonding material 70: 1st bonding material 80: 4th bonding material 100: Semiconductor Device L1:Outer diameter L2: Inner diameter L3:Outer diameter L4: Inner diameter L6: Inner diameter L7:Outer diameter d1: depth d2: depth

Claims

1. A metal film placed on a semiconductor chip, An insulating film having an opening is provided on the aforementioned metal film, A bonding material provided on the metal film within the opening and bonded to the metal film, Joint surface and, An annular groove provided on the joint surface, along the outer circumference of the joint surface, with an inner diameter of 60% or more and 90% or less of the outer diameter, A connector having the joining surface joined to the joining material, Equipped with, A semiconductor device in which the annular groove is disposed between the bonding surface and the metal film.

2. The joining surface has a rectangular shape, The annular groove is formed in a rectangular shape with respect to the joining surface. The semiconductor device according to claim 1.

3. The corners of the aforementioned rectangular shape are beveled. The semiconductor device according to claim 2.

4. The outer diameter of the annular groove in a predetermined direction parallel to the joint surface is 90% or more and less than 100% of the length of the joint surface in the predetermined direction. The semiconductor device according to claim 1.

5. Having a plurality of annular grooves arranged concentrically with respect to each other, The semiconductor device according to claim 1.

6. The depth of the annular groove provided on the outside is greater than the depth of the annular groove provided on the inside. The semiconductor device according to claim 5.

7. The inner diameter of the annular groove located on the innermost side in a predetermined direction parallel to the joint surface is 60% or more and 90% or less of the outer diameter of the annular groove located on the outermost side in the predetermined direction. The semiconductor device according to claim 5.

8. The semiconductor device according to claim 5, wherein the outer diameter of the outermost annular groove provided in a predetermined direction parallel to the bonding surface is 90% or more and less than 100% of the length of the bonding surface in the predetermined direction.

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