Semiconductor device and method of manufacturing the same

Abstract

The embodiment relates to a semiconductor device and a manufacturing method thereof. According to one embodiment, a semiconductor device includes a semiconductor element having a first surface, a second surface on an opposite side of the first surface, and a side surface between the first surface and the second surface. The first electrode layer is arranged on the first surface of the semiconductor element. The second electrode layer is arranged on the second surface of the semiconductor element. The outer edge portion of the second surface is rounded than the outer edge portion of the first surface. The film thickness of the second electrode layer is gradually reduced as the second electrode layer approaches the side surface.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2023-144353 (filing date: September 6, 2023). This application includes all the contents of the basic application by reference to the basic application. Technical Field

[0002] This embodiment relates to a semiconductor device and a method for manufacturing the same. Background Art

[0003] The semiconductor wafer is ground to form a back electrode, and then cut with a blade to perform the semiconductor chip cutting process. However, when the blade is cut, burrs are generated on the back electrode, and the burrs are sometimes embedded in the cutting sheet. In this case, it is difficult to pick up the semiconductor chip from the cutting sheet. In addition, the burrs on the back electrode sometimes cause short circuits between terminals or cracks on the end face of the semiconductor chip.

[0004] In laser cutting, burrs on the back electrode are suppressed, but there is a concern that the laser may damage the semiconductor chip. In addition, since the laser groove width is extended to about twice the width of the scribe line, resin enters the metal-removed portion of the back chip end during the assembly process. As a result, there is a concern that the characteristics of the semiconductor device will be affected. Summary of the invention

[0005] The semiconductor device of the present embodiment has a semiconductor element, which has a first surface, a second surface located on the opposite side of the first surface, and a side surface located between the first surface and the second surface. The first electrode layer is provided on the first surface of the semiconductor element. The second electrode layer is provided on the second surface of the semiconductor element. The outer edge of the second surface is more rounded than the outer edge of the first surface. The film thickness of the second electrode layer gradually becomes thinner as it approaches the side surface.

[0006] According to the present embodiment, it is possible to provide a semiconductor device and a method for manufacturing the same, which can perform dicing without causing burrs on the back surface electrode and without affecting the characteristics of the semiconductor device. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a partial cross-sectional view showing a structural example of a semiconductor device according to an embodiment.

[0008] Figure 2 It is a cross-sectional view showing an example of a method for manufacturing a semiconductor device according to an embodiment.

[0009] Figure 3 It means continuation Figure 2 A cross-sectional view of an example of a method for manufacturing a semiconductor device.

[0010] Figure 4 It means continuation Figure 3 A cross-sectional view of an example of a method for manufacturing a semiconductor device.

[0011] Figure 5A It means continuation Figure 4 A cross-sectional view of an example of a method for manufacturing a semiconductor device.

[0012] Figure 5B It means continuation Figure 4 A cross-sectional view of an example of a method for manufacturing a semiconductor device.

[0013] Fig. 6A It means continuation Figure 5A A cross-sectional view of an example of a method for manufacturing a semiconductor device.

[0014] Figure 6B It means continuation Figure 5B A cross-sectional view of an example of a method for manufacturing a semiconductor device.

[0015] Fig. 7A It means continuation Fig. 6A A cross-sectional view of an example of a method for manufacturing a semiconductor device.

[0016] Figure 7B It means continuation Figure 6B A cross-sectional view of an example of a method for manufacturing a semiconductor device.

[0017] Fig. 8A It means continuation Fig. 7A A cross-sectional view of an example of a method for manufacturing a semiconductor device.

[0018] Figure 8B It means continuation Figure 7B A cross-sectional view of an example of a method for manufacturing a semiconductor device.

[0019] Fig. 9A It means continuation Fig. 8A A cross-sectional view of an example of a method for manufacturing a semiconductor device.

[0020] Fig. 9B It means continuation Figure 8B A cross-sectional view of an example of a method for manufacturing a semiconductor device. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments do not limit the present invention. The accompanying drawings are schematic or conceptual diagrams. In the specification and the accompanying drawings, the same reference numerals are used for the same elements.

[0022] Figure 11 is a partial cross-sectional view showing a structural example of a semiconductor device according to an embodiment. The semiconductor device 1 includes a semiconductor element 10, a surface electrode 20, an insulating film 30, a back electrode 40, and a surface electrode 50. Figure 1 The end portion of the semiconductor device 1 is partially shown. The surface electrode 20 and / or the surface electrode 50 is an example of a first electrode layer.

[0023] The semiconductor device 1 may be, for example, an IGBT (Insulated Gate Bipolar Transistor), a HEMT (High Electron Mobility Transistor), a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), or a diode or other power semiconductor device. The semiconductor device 1 is monolithicized into a semiconductor chip.

[0024] The semiconductor element 10 has a first surface F1, a second surface F2, and a side surface F3. The second surface F2 is located on the opposite side of the first surface F1. The side surface F3 is located between the first surface F1 and the second surface F2. The semiconductor element 10 is composed of a semiconductor material such as silicon. The thickness of the semiconductor element 10 is, for example, less than 100 μm. The semiconductor element 10 includes a semiconductor substrate, an impurity diffusion layer, an epitaxial growth layer, etc.

[0025] On the first surface F1 of the semiconductor element 10 , a relatively thin surface electrode 50 formed by sputtering or the like, a relatively thick surface electrode 20 formed by plating, vapor deposition or the like, and an insulating film 30 are provided.

[0026] The surface electrode 20 is formed on the surface electrode 50 by plating or evaporation to be a metal film having a film thickness equal to or greater than that of the insulating film 30, and the two are electrically connected. The surface electrode 50 is composed of, for example, a conductive metal such as titanium, aluminum, or an alloy of aluminum, silicon, and copper. The surface electrode 20 is composed of, for example, a laminated film of a conductive metal such as copper, aluminum, titanium, nickel, and gold.

[0027] The insulating film 30 is provided to electrically isolate the surface electrode 50 and the surface electrode 20 from other semiconductor elements or to protect the surface electrode 50 and the surface electrode 20. The insulating film 30 is made of an insulating material such as polyimide.

[0028] The back electrode 40 as the second electrode layer is provided on the second surface F2 of the semiconductor element 10. The back electrode 40 covers the second surface F2 and functions as, for example, a collector electrode of an IGBT or a drain electrode of a MOSFET of the semiconductor device 1. The back electrode 40 is composed of, for example, a laminated film of a conductive metal such as copper, aluminum, titanium, nickel, or gold.

[0029] Here, in the outer edge portion AE of the semiconductor element 10, the end E2 of the outer edge portion of the second surface F2 is more rounded than the end E1 of the outer edge portion of the first surface F1. That is, the curvature radius of the end E1 of the first surface F1 is relatively small and is substantially a right angle, while the curvature radius of the end E2 of the second surface F2 is larger than that of the end E1 and is rounded in a curved shape. The outer edge portion AE is a curved surface portion of the second surface F1 located near the side surface F3. The outer edge portion AE can also be referred to as a curved surface portion connecting the second surface F1 and the side surface F3.

[0030] The back electrode 40 also covers the outer edge of the second surface F2 and covers the curved surface of the end E2. Therefore, the back electrode 40 is bent from the second surface F2 along the side F3 toward the first surface F1 in the +Z direction at the outer edge of the second surface F2. In addition, the film thickness of the back electrode 40 gradually becomes thinner at the end E2 as it approaches the side F3. Moreover, in the top view (plane parallel to the first surface F1) observed from the vertical direction (Z direction) of the first surface F1, the back electrode 40 does not protrude outward from the side F3. That is, in the top view observed from the Z direction, the back electrode 40 does not protrude from the side F3 to the outside of the semiconductor element 10, but is arranged on the inner side of the semiconductor element 10.

[0031] The end E2 of the semiconductor element 10 is rounded, and the back electrode 40 covers the end E2 from the second surface F2 along the side F3. Thus, on the second surface F2 of the semiconductor element 10, cracks and debris from the end E2 can be suppressed. In addition, the back electrode 40 covers the end E2 from the second surface F2 along the side F3 and does not protrude from the side F3 to the outside. Therefore, it is possible to suppress the back electrode 40 from accidentally short-circuiting with other wiring and semiconductor elements.

[0032] Next, a method for manufacturing the semiconductor device 1 according to the embodiment will be described.

[0033] Figure 2 to Figure 9B 1 is a cross-sectional view showing an example of a method for manufacturing a semiconductor device according to an embodiment. Figure 5B , Figure 6B , Figure 7B , Figure 8B as well as Fig. 9B is shown in more detail Figure 5A , Fig. 6A , Fig. 7A , Fig. 8A as well as Fig. 9A A local cross-sectional view between adjacent semiconductor chips.

[0034] First, if Figure 2As shown, in the pre-process of the semiconductor manufacturing process, after the semiconductor element 10 is manufactured, the surface electrode 20 , the surface electrode 50 , and the insulating film 30 are formed on the first surface F1 of the semiconductor element 10 .

[0035] Then, if Figure 3 As shown, a groove TR is formed in the semiconductor element 10 from the first surface F1 along the scribe line DL located between the plurality of semiconductor chips CH. The groove TR is formed, for example, by cutting with a blade. The groove TR is formed to a depth between the first surface F1 and the second surface F2 of the semiconductor element 10. In addition, the depth of the groove TR is formed to be deeper than the value obtained by adding the thickness of the semiconductor element 10 in the final product to the thickness of the back electrode 40. Thus, after the material of the back electrode 40 is formed, it is not necessary to cut the back electrode 40 by a blade or a laser.

[0036] Next, if Figure 4 As shown, liquid adhesive 60 is supplied onto first surface F1 of semiconductor element 10. Adhesive 60 is made of, for example, acrylic resin, and is supplied so as to fill trench TR.

[0037] Next, the support substrate 70 is placed on the adhesive 60. The support substrate 70 is bonded to the upper side of the semiconductor element 10 via the adhesive 60. The support substrate 70 is made of an insulating material such as glass.

[0038] Next, if Figure 5A as well as Figure 5B As shown in FIG. 1 , the semiconductor element 10 is turned upside down so that the support substrate 70 is facing downward. As a result, the second surface F2 of the semiconductor element 10 appears upward.

[0039] Then, if Figure 5A and Figure 5B As shown in FIG. 1 , the second surface F2 of the semiconductor element 10 is polished by using a CMP (Chemical Mechanical Polishing) method or the like until the adhesive 60 in the groove TR is exposed from the second surface F2. Figure 5B As shown in FIG. 1 , the boundary between the second surface F2 of the semiconductor element 10 and the adhesive 60 is etched further than the other portions of the second surface F2 and the adhesive 60. Therefore, the outer edge (corner) of the second surface F2 of the semiconductor element 10 is etched together with the exposed portion of the adhesive 60 to form a rounded corner. In this way, the curvature radius of the end E2 of the outer edge of the second surface F2 is greater than Figure 1 The outer edge of the first surface F1 has a large curvature radius and is curved. In addition, the thickness of the semiconductor element 10 after grinding becomes the thickness of the semiconductor element 10 in the finished product, the thickness of the back electrode 40, and Fig. 6A , Figure 6BThe sum of the thicknesses of the semiconductor elements 10 etched back.

[0040] Then, if Fig. 6A and Figure 6B As shown, the second surface F2 of the semiconductor element 10 is selectively etched back using the RIE method or the wet etching method. As a result, the adhesive 60 protrudes from the second surface F2. The semiconductor element 10 is etched back to the thickness of the final product. At this time, as shown in FIG. Figure 6B As shown, the end E2 of the second surface F2 maintains Figure 5B The curved side is etched back.

[0041] Next, if Fig. 7A as well as Figure 7B As shown, the material of the back electrode 40 is deposited on the second surface F2 and the adhesive 60 by using a sputtering method or the like. Figure 7B As shown, the adhesive 60 protrudes from the second surface F2, and the end E2 of the second surface F2 is rounded, so the material of the back electrode 40 enters the boundary portion between the end E2 of the second surface F2 and the adhesive 60, and covers the end E2 of the second surface F2 with a rounded corner. As a result, the material of the back electrode 40 gradually becomes thinner at the end E2 of the second surface F2 with a rounded corner as it approaches the side surface F3. In addition, the semiconductor element 10 is in contact with the adhesive 60 at the side surface F3, so the material of the back electrode 40 does not protrude outward from the side surface F3 in a top view observed from the Z direction.

[0042] On the other hand, the material of the back electrode 40 is deposited on the top of the protruding adhesive 60, but is hardly deposited on the side thereof. Therefore, at least a part of the side of the protruding portion of the adhesive 60 is exposed.

[0043] Then, if Fig. 8A and Figure 8B As shown in FIG. 1 , the adhesive 60 is selectively etched while leaving the material of the back electrode 40 on the second surface F2. At this time, since at least a portion of the side surface of the protruding portion of the adhesive 60 is exposed, the protruding portion of the adhesive 60 is selectively etched. Therefore, the material of the back electrode 40 on the protruding portion of the adhesive 60 is removed (peeled off) together with the adhesive 60. At this time, as shown in FIG. Figure 8B As shown, the back electrode 40 remains on the second surface F2 of the semiconductor element 10, and maintains the state of covering the end E2 of the rounded second surface F2. In addition, the adhesive 60 is slightly recessed from the back electrode 40 or the second surface F2 to the first surface F1 side. In this way, the back electrode 40 is separated for each semiconductor chip by peeling based on the adhesive 60, so there is no need to cut the back electrode 40 by a blade or laser.

[0044] Then, if Fig. 9A and Fig. 9BAs shown in FIG. 1 , the semiconductor element 10 is turned upside down. Thus, the first surface F1 of the semiconductor element 10 appears at the top. The back surface electrode 40 on the second surface F2 side is attached to the dicing sheet DS.

[0045] The adhesive 60 is dissolved and the support substrate 70 is peeled off. Next, the semiconductor chip is separated into pieces to complete the Figure 1 The semiconductor device 1 is shown.

[0046] According to the present embodiment, a DBG (Dicing Before Grinding) method is used in which a back electrode 40 is provided and the second surface F2 of the semiconductor element 10 is ground after cutting. However, in the present embodiment, it is not necessary to cut the material of the back electrode 40 by a blade, and the material of the back electrode 40 on the adhesive 60 is peeled off together with the adhesive 60 during the etching process of the adhesive 60. Thus, burrs are not generated on the back electrode 40, and the semiconductor chip can be easily picked up from the cutting sheet DS. In addition, it is possible to prevent the back electrode 40 from short-circuiting with unexpected semiconductor elements, wiring, etc. Furthermore, the back electrode 40 covers the outer edge of the second surface F2 of the semiconductor element 10 with rounded corners. Therefore, the outer edge of the semiconductor element 10 can be protected and the generation of cracks can be suppressed. As a result, the present embodiment can be cut in a manner that does not generate burrs on the back electrode 40 and does not affect the characteristics of the semiconductor device.

[0047] Furthermore, the back electrode 40 covers the outer edge of the second surface F2 of the semiconductor element 10 with rounded corners, so that when the semiconductor chip is mounted on a lead frame or a wiring substrate, the solder (not shown) is easily formed into a fillet shape on the back electrode 40. Thus, the deviation of the film thickness of the solder can be suppressed, and it is difficult for the solder under the semiconductor chip to have gaps.

[0048] The back surface electrode 40 covers the outer edge portion of the rounded second surface F2 of the semiconductor element 10 , thereby improving the heat dissipation performance of the semiconductor chip.

[0049] Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the subject matter of the invention. These embodiments and their variations are included in the scope and subject matter of the invention, and are also included in the invention described in the claims and their equivalents.

[0050] Description of symbols

[0051] 1Semiconductor device

[0052] 10Semiconductor components

[0053] 20 Surface electrodes

[0054] 30 Insulation film

[0055] 40 back electrode

[0056] 50 Surface electrodes

Claims

1. A semiconductor device comprising: A semiconductor element having a first surface, a second surface located on the opposite side of the first surface, and a side surface located between the first surface and the second surface; A first electrode layer, disposed on the first surface of the semiconductor element; as well as a second electrode layer, disposed on the second surface of the semiconductor element, The outer edge of the second surface is more rounded than the outer edge of the first surface, The thickness of the second electrode layer gradually decreases as it approaches the side surface.

2. The semiconductor device according to claim 1, wherein The second electrode layer covers the outer edge portion of the second surface.

3. The semiconductor device according to claim 1 or 2, wherein: In a plane parallel to the first surface, the second electrode layer does not protrude outward from the side surface.

4. The semiconductor device according to claim 1 or 2, wherein: The second electrode layer is bent from the second surface along the side surface toward the first surface at an outer edge portion of the second surface.

5. A method for manufacturing a semiconductor device, comprising the following steps: forming a first electrode layer on the first surface of a semiconductor element having a first surface, a second surface located on the opposite side of the first surface, and a side surface located between the first surface and the second surface; forming a groove in the semiconductor element from the first surface along a line between a plurality of semiconductor chips of the semiconductor element; supplying adhesive to the first surface in a manner of filling the groove; grinding the second surface of the semiconductor element until the adhesive in the groove is exposed from the second surface; selectively etching back the second surface of the semiconductor element so that the adhesive protrudes from the second surface; depositing a material of a second electrode layer on the second surface and the adhesive; as well as The adhesive is selectively removed together with the material of the second electrode layer located on the adhesive, while the material of the second electrode layer located on the second surface remains.

6. The method for manufacturing a semiconductor device according to claim 5, comprising the following steps: After supplying the adhesive and before polishing the second surface, a support substrate is bonded to the adhesive on the first surface, and the semiconductor element is turned upside down so that the support substrate is facing downward. The method for manufacturing the semiconductor device further comprises the following steps: After removing the material of the second electrode layer located on the adhesive, a sheet is attached to the second electrode layer on the second surface, and the semiconductor element is turned upside down so that the sheet faces downward.

7. The method for manufacturing a semiconductor device according to claim 6, wherein: After the sheets are attached, the plurality of semiconductor chips are picked up and mounted on a wiring board.

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