JP2023042566A - Semiconductor device - Google Patents

Abstract

To provide a semiconductor device capable of improving reliability.SOLUTION: A semiconductor device comprises: a semiconductor part; a first electrode provided on the semiconductor part; a first protection film provided on the semiconductor part so as to cover an outer edge of the first electrode; a second electrode provided on the first electrode so as to cover a part of the first protection film; and a second protection film provided on the semiconductor part so as to cover the first protection film and an outer edge of the second electrode.SELECTED DRAWING: Figure 1

Description

Embodiments relate to semiconductor devices.

In a power module for power control, it is preferable to mount a semiconductor chip using a copper wire with low electrical resistance. However, copper wire has higher hardness than aluminum wire and the like, and may cause bonding damage to the semiconductor chip.

JP-A-2004-128513

Embodiments provide a semiconductor device with improved reliability.

A semiconductor device according to an embodiment includes a semiconductor section, a first electrode provided on the semiconductor section, a first protective film provided on the semiconductor section so as to cover an outer edge of the first electrode, a second electrode provided on the first electrode and covering a portion of the first protective film; and a second electrode provided on the semiconductor section so as to cover the outer edge of the second electrode and the first protective film. and a second protective film.

1 is a schematic diagram showing a semiconductor device according to an embodiment; FIG. 4A to 4C are schematic cross-sectional views showing the manufacturing process of the semiconductor device according to the embodiment; FIG. 3 is a schematic cross-sectional view showing the manufacturing process following FIG. 2 ; 1 is a schematic plan view showing a semiconductor device according to an embodiment; FIG. It is a perspective view which shows typically the mounting method of the semiconductor device which concerns on embodiment. It is a schematic diagram which shows typically another mounting method of the semiconductor device which concerns on embodiment. 1 is a schematic cross-sectional view showing a power module according to an embodiment; FIG. It is a schematic cross section showing a semiconductor device according to a modification of the embodiment.

Hereinafter, embodiments will be described with reference to the drawings. The same parts in the drawings are given the same numbers, and detailed descriptions thereof are omitted as appropriate, and different parts will be described. Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each portion, the size ratio between portions, and the like are not necessarily the same as the actual ones. Also, even when the same parts are shown, the dimensions and ratios may be different depending on the drawing.

Furthermore, the arrangement and configuration of each part will be explained using the X-axis, Y-axis and Z-axis shown in each drawing. The X-axis, Y-axis, and Z-axis are orthogonal to each other and represent the X-direction, Y-direction, and Z-direction, respectively. Also, the Z direction may be described as upward and the opposite direction as downward.

FIGS. 1A and 1B are schematic diagrams showing a semiconductor device 1 according to an embodiment. FIG. 1(a) is a cross-sectional view taken along line AA shown in FIG. 1(b). FIG. 1B is a plan view showing the upper surface of the semiconductor device 1. FIG. The semiconductor device 1 is, for example, a switching element such as a MOSFET, an IGBT (Insulated Gate Bipolar Transistor), or a Schottky diode.

As shown in FIG. 1A, the semiconductor device 1 includes a semiconductor portion 10, a first electrode 20, a second electrode 30, a first protective film 40, and a second protective film 50. As shown in FIG. The semiconductor section 10 contains, for example, silicon, silicon carbide, gallium nitride, or the like.

The first electrode 20 is provided on the surface of the semiconductor section 10 and electrically connected to an active region (not shown) of the semiconductor section 10 . The first electrode 20 contains, for example, aluminum. The first electrode 20 is, for example, the source electrode of the MOSFET. Also, the first electrode 20 is an emitter electrode of an IGBT or an anode electrode of a Schottky diode.

A second electrode 30 is provided on the first electrode 20 . The second electrode 30 contacts the first electrode 20 and is electrically connected to the first electrode 20 . The second electrode 30 contains a material with higher hardness than the material of the first electrode 20 . The second electrode 30 contains, for example, copper (Cu). In addition, the second electrode 30 is provided thicker than the first electrode 20 in the direction perpendicular to the surface of the semiconductor section 10, for example, the Z direction. As a result, the impact applied to the semiconductor section 10 when bonding, for example, a copper wire to the second electrode 30 can be reduced, and bonding damage can be prevented.

The first protective film 40 is provided on the semiconductor section 10 so as to cover the outer edge 20 e of the first electrode 20 . The first protective film 40 contains, for example, an insulating first resin. The first protective film 40 contains polyimide, for example. The first protective film 40 covers, for example, the outer periphery of the first electrode 20 and the outer periphery of the contact surface between the semiconductor section 10 and the first electrode 20 to protect them from the outside air.

The first protective film 40 includes a first portion 40 a covering the outer edge 20 e of the first electrode 20 and a second portion 40 b contacting the surface of the semiconductor section 10 . The first portion 40a and the second portion 40b are integrally provided. Also, the first portion 40 a is provided so as to extend between the first electrode 20 and the second electrode 30 .

The second protective film 50 is provided on the semiconductor section 10 so as to cover the outer edge 30 e of the second electrode 30 and the first protective film 40 . The second protective film 50 contains, for example, a second insulating resin. The second resin of the second protective film 50 may contain the same component as the first resin of the first protective film 40 . The second protective film 50 contains polyimide, for example. Also, the second resin may be a resin different from the first resin.

The second protective film 50 includes, for example, a first portion 50a, a second portion 50b, and a third portion 50c. The first portion 50 a contacts the surface of the second electrode 30 and extends along the surface of the second electrode 30 inward from the outer edge 30 e of the second electrode 30 . For example, the first portion 50a extends inward beyond the portion where the first portion of the first protective film 40 extends between the first electrode 20 and the second electrode 30, and extends between the first electrode 20 and the second electrode 30. It is provided so as to cover the portion where the two electrodes 30 are in contact with each other. The second portion 50b is provided so as to be in contact with the surface of the semiconductor section 10 . The third portion 50c is provided to cover the first protective film 40 between the first portion 50a and the second portion 50b. The first portion 50a, the second portion 50b and the third portion 50c of the second protective film 50 are integrally provided.

The second protective film 50 doubly protects the contact surface between the semiconductor section 10 and the first electrode 20 . Furthermore, the second protective film 50 prevents the third electrode 30 from peeling off from the first protective film 40 starting from the outer edge 30 e of the third electrode 30 .

For example, since the first protective film 40 contains resin, the adhesion between the first protective film 40 and the second electrode 30 is not so strong. During operation of the semiconductor device 1 , stress is generated between the first protective film 40 and the second electrode 30 due to the difference in coefficient of linear thermal expansion. Therefore, if the second protective film 50 is not provided, the adhesion between the first protective film 40 and the second electrode 30 is lowered, and the second electrode 30 may be rolled up from the outer edge. Further, the interface between the first electrode 20 and the second electrode 30 may be separated due to repeated temperature increases and decreases during operation of the semiconductor device 1 . Such defects reduce the reliability of the semiconductor device 1 .

In the semiconductor device 1 according to the embodiment, the provision of the second protective film 50 makes it possible to prevent peeling of the outer edge of the second electrode 30 from the first protective film 40 . In addition, by using a highly moisture-proof resin for the first protective film 40 and the second protective film 50, the reliability of the semiconductor device 1 can be further improved. For the second protective film 50, it is preferable to use, for example, a resin having higher moisture resistance than the first protective film 40 does.

FIG. 1B shows the second electrode 30 and the first protective film 40 . In FIG. 1B, the outer edge 20e of the first electrode 20 and the inner edge 40e of the first protective film 40 (see FIG. 1A) are indicated by broken lines. Note that the second protective film 50 is omitted in FIG. 1(b).

As shown in FIG. 1B , the second electrode 30 is provided inside the first electrode 20 in plan view parallel to the surface of the semiconductor section 10 . That is, the outer edge 30 e of the second electrode 30 is located inside the outer edge 20 e of the first electrode 20 . For example, the width of the first electrode 20 in the X direction is wider than the width of the second electrode 30 in the X direction. Also, the width of the first electrode 20 in the Y direction is wider than the width of the second electrode 30 in the Y direction.

As shown in FIG. 1B, the first protective film 40 is provided along the outer edge 20e of the first electrode 20 so as to surround the first electrode 20. As shown in FIG. Also, the first protective film 40 is provided along the outer edge of the second electrode 30 so as to surround the second electrode 30 .

In this way, by providing the second electrode 30 inside the first electrode 20, the creepage distance from the surface of the semiconductor section 10 to the outer edge 30e of the second electrode 30 via the surface of the first protective film 40 is reduced. can be longer. Thereby, the breakdown voltage of the semiconductor device 1 can be improved. Further, by providing the second protective film 50 covering the outer edge 30e of the first protective film 40 and the second electrode 30, the breakdown voltage of the semiconductor device 1 can be further improved.

Next, a method for manufacturing the semiconductor device 1 will be described with reference to FIGS. 2(a) to 3(c). 2A to 3C are schematic cross-sectional views showing the manufacturing process of the semiconductor device 1 according to the embodiment.

As shown in FIG. 2A, a wafer 100 having a first electrode 20 and a first protective film 40 provided on its surface is prepared. The first protective film 40 is provided on the wafer 100 so as to cover the outer edge of the first electrode 20 .

An active region (not shown) of the semiconductor device 1 is provided immediately below the first electrode 20 . Further, when the semiconductor device 1 is a MOSFET, a drain electrode (not shown) is provided on the back side of the wafer 100 . If the semiconductor device 1 is an IGBT or a Schottky diode, a collector electrode or a cathode electrode (not shown) is provided on the rear surface side of the wafer 100 .

For example, the wafer 100 can be cut in the state shown in FIG. 2A to separate a plurality of semiconductor devices 1 into individual pieces. In that case, the first electrode 20 , for example, an aluminum electrode is exposed on the surface of the semiconductor device 1 . When mounting the semiconductor device 1 , for example, an aluminum wire is bonded onto the first electrode 20 .

In the embodiment, a metal layer 33 is provided on the surface of the wafer 100, as shown in FIG. 2(b). The metal layer 33 is provided so as to cover the first electrode 20 and the first protective film 40 . The metal layer 33 contains nickel, for example.

A resist mask 103 is formed on the metal layer 33 as shown in FIG. The resist mask 103 has an opening 103p positioned above the first electrode 20 . Also, the resist mask 103 partially covers the first protective film 40 and covers the surface of the wafer 100 between the adjacent first protective films 40 .

As shown in FIG. 3A, the second electrode 30 is formed inside the opening 103p of the resist mask 103. As shown in FIG. The second electrode 30 is formed, for example, by electroplating through the metal layer 33 . The second electrode 30 contains, for example, copper (Cu). The second electrode 30 is provided so as to protrude above the first protective film 40 .

As shown in FIG. 3B, the resist mask 103 and part of the metal layer 33 are removed to expose the surface of the wafer 100 and part of the first protective film 40 . The resist mask 103 and the metal layer 33 are removed by wet etching, for example. After removing the resist mask 103, the exposed portions of the metal layer 33 are removed.

A second protective film 50 is formed on the surface of the wafer 100, as shown in FIG. 3(c). The second protective film 50 is formed to cover the outer edges of the first protective film 40 and the second electrode 30 . The second protective film 50 is formed, for example, by selectively removing a film-like resin formed on the front surface side of the wafer 100 . Subsequently, the wafer 100 is cut using, for example, a dicer to singulate the semiconductor devices 1 .

4A and 4B are schematic plan views showing the semiconductor device 1 according to the embodiment. 4A and 4B are plan views illustrating the surface side of the semiconductor section 10. FIG. In this example, the semiconductor device 1 is, for example, a MOSFET or IGBT having a gate electrode.

As shown in FIG. 4A, the surface side of the semiconductor section 10 is covered with the second protective film 50, and the second electrode 30 (see FIG. 1) and part of the control pad 60 are exposed. Control pad 60 is electrically connected to a gate electrode (not shown).

The second protective film 50 is provided to expose the bonding area 30BA where the metal wire of the second electrode 30 is bonded. Also, the second protective film 50 is provided so as to expose the bonding area 60BA of the control pad 60 . The bonding areas 30BA and 60BA exposed in this manner need only have an area for bonding metal wires, and the second protective film 50 preferably covers the second electrodes 30 and the control pads 60 as widely as possible.

In the example shown in FIG. 4B, the second protective film 50 is provided so as to expose four bonding areas 30BA of the second electrode 30. In the example shown in FIG. In this example, the area of the bonding area 30BA can be made smaller, and the second protective film 50 is provided so as to cover a wider area.

In this manner, the second protective film 50 effectively suppresses the separation of the second electrode 30 from the first protective film 40 , prevents entry of moisture and the like from the outside air, and increases the breakdown voltage of the semiconductor device 1 . provided to improve

5A and 5B are perspective views schematically showing a mounting method of the semiconductor device 1 according to the embodiment. FIGS. 5( a ) and 5 ( b ) show metal wire 70 and metal wire 80 bonded to second electrode 30 and control pad 60 .

A plurality of metal wires 70 are bonded onto the second electrode 30, as shown in FIG. 5(a). Each of the metal wires 70 is bonded to the second electrode 30 at two points by providing looping, for example. A metal wire 70 is connected onto the bonding area 30BA of the second electrode 30 . In this example, one metal wire 70 is connected to one bonding area 30BA, and there are two connection positions.

Metal wire 80 is bonded onto bonding area 60BA of control pad 60 (see FIG. 4). Metal wire 80 is, for example, a copper wire. Also, the metal wire 80 may be, for example, an aluminum wire.

In the example shown in FIG. 5(b), one metal wire 70 is connected to two bonding areas 30BA. There is one bonding position in each bonding area 30BA.

FIGS. 6A and 6B are schematic diagrams showing another mounting method of the semiconductor device 1 according to the embodiment. FIG. 6A is a plan view illustrating the surface side of the semiconductor section 10. FIG. FIG. 6(b) is a perspective view showing the metal connector 75 bonded onto the second electrode 30. FIG. FIG. 6(c) is a cross-sectional view showing the bonding structure.

As shown in FIG. 6A, the second protective film 50 is provided so as to expose one bonding area 30BA of the second electrode 30 and the bonding area 60BA of the control pad 60. As shown in FIG.

As shown in FIG. 6B, for example, a plate-shaped metal connector 75 is connected to the second electrode 30 in the bonding area 30BA. The metal connector 75 is, for example, a metal plate containing copper. The bonding area 30BA is provided to have an area matching the size of the connection surface of the metal connector 75. As shown in FIG. Such a metal connector 75 has a large current capacity and a small electrical resistance value. That is, it is suitable for applications in which a large current flows. The metal connector 75 is not limited to this example, and may be, for example, a block-shaped metal material. Also, the aspect ratio of the cross section orthogonal to the longitudinal direction of the metal connector 75 is, for example, 1.5 to 6.0, but is not limited to this. On the other hand, to the bonding area 60BA of the control pad 60, for example, a metal wire 80 (see FIG. 5) is connected.

As shown in FIG. 6( c ), the metal connector 75 is connected to the second electrode 30 via a connecting member 77 . The connection member 77 is, for example, a solder material. Also, the connection member 77 may be a sintered material containing silver, copper, or the like.

FIG. 7 is a schematic cross-sectional view showing the power module 2 according to the embodiment. The power module 2 is, for example, a power converter containing the semiconductor device 1 .

The semiconductor device 1 is mounted, for example, on the surface of a DBC (Direct Bonded Copper) substrate 110 and placed inside a case 120 . DBC substrate 110 includes mounting pads 113 and control wiring 115 . Mount pad 113 and control wiring 115 are, for example, copper foil.

The semiconductor device 1 is mounted with the back side facing the mount pad 113 . Electrodes on the back side of the semiconductor device 1 are electrically connected to the mount pads 113 via the conductive die mount material 13, for example.

The DBC substrate 110 is mounted on the base plate 130 via solder material 117, for example. A solder material 117 connects the back surface of the DBC substrate 110 and the base plate 130 . The base plate 130 is, for example, a metal plate. Heat generated during operation of semiconductor device 1 is dissipated to the outside via DBC substrate 110 and base plate 130 .

Case 120 is provided to surround semiconductor device 1 mounted on base plate 130 and DBC substrate 110 . The bottom of case 120 contacts base plate 130 .

Case 120 has connection terminals 123 and 125 . Semiconductor device 1 arranged inside case 120 is electrically connected to an external circuit via connection terminals 123 and 125 . The connection terminal 123 is electrically connected to the second electrode 30 of the semiconductor device 1 via a metal wire 70, for example. The connection terminals 125 are electrically connected to the mount pads 113 of the DBC substrate 110 via metal wires 90, for example. That is, connection terminal 125 is electrically connected to an electrode on the back side of semiconductor device 1 via metal wire 90 and mount pad 113 .

Further, the control pads 60 (see FIG. 4) of the semiconductor device 1 are electrically connected to the control wirings 115 of the DBC substrate 110 via metal wires 80, for example. The control wiring 115 is electrically connected to signal terminals (not shown) provided on the case 120 .

The semiconductor device 1 mounted on the DBC substrate 110 is immersed in, for example, a gel-like insulating member 140 that fills the space surrounded by the case 120 and the base plate 130 . Furthermore, the space surrounded by case 120 and base plate 130 is sealed by lid 150 connected to the upper end of case 120 .

A large current flows between the connection terminal 123 and the connection terminal 125 in the power module 2 . Therefore, by using, for example, copper wires as the metal wires 70 and 90, reliability of electrical connection between the semiconductor device 1 and the connection terminal 123 and between the mount pad 113 and the connection terminal 125 is improved. . A plate-shaped or block-shaped metal connector 75 may be used instead of the metal wire 70 .

FIGS. 8A and 8B are schematic diagrams showing a semiconductor device 3 according to a modification of the embodiment. FIG. 8(a) is a cross-sectional view taken along line BB shown in FIG. 8(b). 8B is a plan view showing the surface side of the semiconductor section 10. FIG.

As shown in FIG. 8A, the semiconductor device 3 includes a semiconductor section 10, a first electrode 20, a second electrode 30, a first protective film 40, and a second protective film 50. As shown in FIG. The first electrode 20 is provided on the surface of the semiconductor section 10 . A second electrode 30 is provided on the first electrode 20 .

The first protective film 40 is provided on the semiconductor section 10 so as to cover the outer edge 20 e of the first electrode 20 . The first protective film 40 includes a first portion 40 a covering the outer edge 20 e of the first electrode 20 and a second portion 40 b contacting the surface of the semiconductor section 10 . The first portion 40a and the second portion 40b are integrally provided.

The second protective film 50 is provided on the semiconductor section 10 so as to cover the outer edge 30 e of the second electrode 30 and the first protective film 40 . The second protective film 50 includes, for example, a first portion 50a, a second portion 50b, and a third portion 50c. The first portion 50 a contacts the surface of the second electrode 30 and extends along the surface of the second electrode 30 inward from the outer edge 30 e of the second electrode 30 . The second portion 50b is provided so as to be in contact with the surface of the semiconductor section 10 . The third portion 50c covers the first protective film 40 between the first portion 50a and the second portion 50b. The first portion 50a, the second portion 50b and the third portion 50c of the second protective film 50 are integrally provided. The second protective film 50 doubly protects the contact surface between the semiconductor section 10 and the first electrode 20 .

In this example, the second electrode 30 is provided on the first electrode 20 so that the outer edge 30 e thereof is separated from the first protective film 40 . The second protective film 50 covers the surface of the first electrode 20 exposed between the first protective film 40 and the second electrode 30 .

FIG. 8B shows the first electrode 20, the second electrode 30, and the first protective film 40. As shown in FIG. In addition, in FIG. 8B, the outer edge 20e of the first electrode 20 is indicated by a dashed line. Furthermore, in FIG. 8B, the second protective film 50 is omitted.

As shown in FIG. 8B , the second electrode 30 is provided inside the first electrode 20 in plan view parallel to the surface of the semiconductor section 10 . That is, the outer edge 30 e of the second electrode 30 is located inside the outer edge 20 e of the first electrode 20 . For example, the width of the first electrode 20 in the X direction is wider than the width of the second electrode 30 in the X direction. Also, the width of the first electrode 20 in the Y direction is wider than the width of the second electrode 30 in the Y direction.

As shown in FIG. 8B, the first protective film 40 is provided along the outer edge 20e of the first electrode 20 so as to surround the first electrode 20. As shown in FIG. Also, the first protective film 40 is provided so as to surround the second electrode 30 while being separated from the outer edge 30 e of the second electrode 30 . A surface of the first electrode 20 is exposed between the second electrode 30 and the first protective film 40 .

In the semiconductor device 3, the creepage distance from the surface of the semiconductor section 10 to the outer edge 30e of the second electrode 30 through the surface of the first protective film 40 is longer, and the breakdown voltage can be improved. Furthermore, by covering the first protective film 40, the exposed surface of the first electrode 20, and the outer edge 30e of the second electrode 30 with the second protective film 50, the breakdown voltage can be further improved.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1... Semiconductor device 2... Power module 10... Semiconductor part 13... Die mount material 20... First electrode 20e, 30e... Outer edge 30... Second electrode 30BA, 60BA... Bonding area 33... Metal layer , 40... First protective film 50... Second protective film 40a, 50a... First part 40b, 50b... Second part 50c... Third part 60... Control pad 70, 80, 90... Metal wire , 75... Metal connector 100... Wafer 103... Resist mask 103p... Opening 110... DBC substrate 113... Mount pad 115... Control wiring 117... Solder material 120... Case 123, 125... Connection terminal, DESCRIPTION OF SYMBOLS 130... Base plate, 140... Insulating member, 150... Lid

Claims (8)

a semiconductor part;
a first electrode provided on the semiconductor part;
a first protective film provided on the semiconductor part so as to cover an outer edge of the first electrode;
a second electrode provided on the first electrode and covering a portion of the first protective film;
a second protective film provided on the semiconductor section so as to cover the outer edge of the second electrode and the first protective film;
A semiconductor device with 2. The semiconductor device according to claim 1, wherein hardness of said second electrode is higher than hardness of said first electrode. the first electrode comprises aluminum;
3. The semiconductor device according to claim 2, wherein said second electrode contains copper. The second protective film extends inwardly from the outer edge of the second electrode along the surface of the second electrode, and covers a portion where the second electrode contacts the first electrode. The semiconductor device according to any one of the above. The first protective film contains a first resin,
5. The semiconductor device according to claim 1, wherein said second protective film contains a second resin. 6. The semiconductor device according to claim 5, wherein said second resin contains the same components as said first resin. further comprising a terminal electrically connected to the second electrode;
7. The semiconductor device according to claim 1, wherein said second electrode and said terminal are connected by a plurality of metal wires. further comprising a terminal electrically connected to the second electrode;
7. The semiconductor device according to claim 1, wherein said second electrode and said terminal are connected by a plate-like metal connector.

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