Lead welding structure, lead welding method and semiconductor device

Abstract

The present application relates to a wire welding structure, a wire welding method based on the wire welding structure, and a semiconductor device formed by the wire welding method. The wire welding structure includes a circuit layer formed in a substrate and a pad, a barrier layer, and a passivation layer sequentially stacked on the circuit layer. The hardness of the barrier layer is greater than the hardness of the pad. A first window exposing the pad is opened in a preset area of ​​the barrier layer and the first window does not exceed the preset area. The width of the preset area is less than the width of the solder ball after wire bonding. A second window with a width greater than the preset area is opened on the passivation layer, and the second window of the entire preset area is exposed through the second window. By setting a barrier layer between the passivation layer and the pad, a first window can be set on the barrier layer and the window opening range of the barrier layer can be limited. The solder ball after wire bonding can cover all the first windows, so that the solder ball can be welded to the pad while avoiding the pad from overflowing.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a lead welding structure, a lead welding method and a semiconductor device. Background Art

[0002] In the back-end process of semiconductor devices, the welding of leads is involved to lead out electrical connection terminals from the circuit layer in the substrate. In order to protect the circuit layer, a soft metal layer is usually provided on the circuit layer as a welding pad, and the solder ball is specifically welded to the welding pad. Since the welding pad is relatively soft, when the solder ball is pressed on the welding pad, on the one hand, the squeezed welding pad metal will be discharged to both sides, making the welding pad between the solder ball and the circuit layer thinner or the solder ball directly acts on the circuit layer, causing the circuit layer to be subjected to a large impact force and break; on the other hand, when the squeezed welding pad metal is discharged to both sides, conductive particles will be formed on both sides, affecting the electrical performance of the device. Summary of the invention

[0003] Based on this, the present application proposes a wire welding structure, a wire welding method and a semiconductor device, which can avoid the influence of the wire welding process on the device performance.

[0004] In order to solve the above technical problems, the first technical solution proposed in this application is:

[0005] A lead welding structure, comprising:

[0006] substrate;

[0007] A circuit layer formed in the substrate;

[0008] a welding pad formed on the circuit layer and electrically connected to the circuit layer;

[0009] a barrier layer formed on the pad, the hardness of the barrier layer being greater than the hardness of the pad, a first window exposing the pad being opened in a preset area of ​​the barrier layer and not exceeding the preset area, and a width of the preset area being smaller than a width of the solder ball after wire bonding; and

[0010] A passivation layer is formed on the barrier layer, and a second window having a width greater than that of the preset area is opened on the passivation layer, so that the entire preset area is exposed through the second window.

[0011] In one of the embodiments, a first window is opened in a preset area of ​​the barrier layer, and a projection of the first window coincides with a projection of the preset area.

[0012] In one of the embodiments, a first window is opened in the preset area of ​​the barrier layer, the first window is annular and the outer edge of the first window coincides with the edge of the preset area.

[0013] In one embodiment, the predetermined area includes an island area surrounded by the first window, and the width of the island area is smaller than the width of the solder ball before wire bonding.

[0014] In one embodiment, a plurality of first windows arranged at intervals are opened in a preset area of ​​the barrier layer, the first windows are in a strip shape and the first windows are arranged in parallel.

[0015] In one of the embodiments, a plurality of first windows arranged at intervals are opened in a preset area of ​​the barrier layer, and the barrier layer in the preset area is in a grid shape.

[0016] In one embodiment, the opening width of the second window is greater than the width of the solder ball after wire bonding.

[0017] In one embodiment, the width of the preset area is 8 μm to 12 μm smaller than the width of the solder ball after wire bonding.

[0018] The above-mentioned lead welding structure is used to weld the lead on the lead welding structure through the gold wire ball welding process. First, the passivation layer is provided with a second window and the width of the second window is greater than the width of the solder ball after wire bonding, so that the solder ball can be smoothly moved down to the preset area of ​​the barrier layer and avoid the solder ball from being mistakenly welded on the passivation layer. Secondly, a barrier layer is provided between the passivation layer and the solder pad, and a first window is provided in the preset area of ​​the barrier layer. When the solder ball reaches the barrier layer and presses the solder ball, the solder ball can be welded to the solder pad below through the first window of the barrier layer. At the same time, since the width of the preset area of ​​the barrier layer is less than the width of the solder ball after wire bonding, the solder ball after wire bonding will cover the entire preset area, that is, cover all the first windows, thereby preventing the solder pad metal from overflowing outward, which can ensure that there is a solder pad of a certain thickness under the solder ball to avoid the circuit layer from breaking, and can also avoid the formation of excess conductive particles. Therefore, by forming the above-mentioned lead welding structure, the influence of the lead welding process on the electrical performance of the device can be eliminated.

[0019] In order to solve the above technical problems, the second technical solution proposed in this application is:

[0020] A lead welding method, comprising:

[0021] Acquire a wire welding structure, wherein the wire welding structure is any of the wire welding structures described above;

[0022] The solder ball is aligned with the preset area, pressed and wired, so that the wired solder ball covers the preset area to form a lead wire welded on the pad.

[0023] In the above-mentioned wire welding method, since the barrier layer is formed inside the wire welding structure, during the wire welding process, the solder balls after wire bonding will cover all the first windows, thereby preventing the pad metal from overflowing outward, which can not only avoid the circuit layer from breaking, but also avoid the formation of excess conductive particles, eliminating the influence of the wire welding process on the electrical performance of the device.

[0024] In order to solve the above technical problems, the third technical solution proposed in this application is:

[0025] A semiconductor device, comprising:

[0026] substrate;

[0027] A circuit layer formed in the substrate;

[0028] a welding pad formed on the circuit layer and electrically connected to the circuit layer;

[0029] A barrier layer is formed on the pad, the hardness of the barrier layer is greater than the hardness of the pad, a first window exposing the pad is opened in a preset area of ​​the barrier layer and the first window does not exceed the preset area, and the width of the preset area is smaller than the width of the solder ball after wire bonding;

[0030] a passivation layer formed on the barrier layer, wherein a second window having a width greater than that of the preset area is opened on the passivation layer, and the entire preset area is exposed through the second window;

[0031] The wire-bonded solder ball covers the preset area and is embedded in the solder pad to be soldered to the solder pad;

[0032] The lead is connected to the solder ball after the wire bonding.

[0033] In one embodiment, a first annular window and an island region surrounded by the first window are provided in a preset area of ​​the barrier layer, and a portion of the bottom surface of the solder ball after wire bonding contacts the island region.

[0034] In one embodiment, a plurality of first windows arranged at intervals are opened in a preset area of ​​the barrier layer, the first windows are in a strip shape and the first windows are arranged in parallel.

[0035] In one of the embodiments, a plurality of first windows arranged at intervals are opened in a preset area of ​​the barrier layer, and the barrier layer in the preset area is in a grid shape.

[0036] The above-mentioned semiconductor device is formed by the above-mentioned lead welding method, wherein a barrier layer is formed between the passivation layer and the solder pad, and the solder ball after wire bonding covers the barrier layer and is welded to the solder pad below through the first window. The solder pad metal does not overflow from the barrier layer, thereby ensuring the thickness of the solder pad at the bottom of the solder ball and no excess conductive particles are formed. Therefore, the above-mentioned semiconductor device with leads welded thereon still has good electrical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the structure after welding the lead wire to the lead welding structure in the traditional technology;

[0038] Figure 2a A side cross-sectional view of the lead welding structure in the first embodiment of the present application;

[0039] Figure 2b A top view of the lead welding structure in Example 1 of the present application;

[0040] Figure 2c This is a schematic structural diagram of a semiconductor device formed based on the wire bonding structure in Embodiment 1 of the present application;

[0041] Figure 3a A side cross-sectional view of the lead welding structure in the second embodiment of the present application;

[0042] Figure 3b A top view of the lead welding structure in the second embodiment of the present application;

[0043] Figure 3c This is a schematic structural diagram of a semiconductor device formed based on the wire bonding structure in Embodiment 2 of the present application;

[0044] Figure 4a It is a side sectional view of the lead welding structure in the third embodiment of the present application;

[0045] Figure 4b A top view of the lead welding structure in the third embodiment of the present application;

[0046] Figure 4c This is a schematic structural diagram of a semiconductor device formed based on the wire bonding structure in Embodiment 3 of the present application;

[0047] Figure 5a It is a side sectional view of the lead welding structure in the fourth embodiment of the present application;

[0048] Figure 5b A top view of the lead welding structure in the fourth embodiment of the present application;

[0049] Figure 5c This is a schematic structural diagram of a semiconductor device formed based on the wire bonding structure in Embodiment 4 of the present application;

[0050] Figure 6 This is a flowchart of the steps corresponding to the wire welding method in one embodiment of the present application.

[0051] Description of symbols

[0052] 110 circuit layer; 120 solder pad; 130 barrier layer; 131 first window; 132 island region; 140 passivation layer; 141 second window; 210 solder ball after wire bonding; 220 lead; A preset region. DETAILED DESCRIPTION

[0053] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0055] like Figure 1 FIG. 1 is a schematic diagram of a conventional technique in which a lead is welded on a lead welding structure, wherein the lead welding structure comprises a circuit layer 110', a welding pad 120' and a passivation layer 130' which are stacked in sequence, and a window is provided in the passivation layer 130' to expose the welding pad 120', and the solder ball 210' contacts the welding pad 120' through the window. Since the welding pad 120' is relatively soft, the squeezed welding pad 120' will flow to both sides and overflow from the gap between the passivation layer 130' and the solder ball 210' (e.g., Figure 1 As shown by the arrow, the pad 120' at the bottom of the solder ball is thinner, the circuit layer 110' is subjected to a greater impact force and may break, and the pad overflowing outward is likely to form conductive particles, affecting device performance.

[0056] To this end, the present application proposes a new lead welding structure, which can avoid the influence of the welding process on the device performance when welding the lead on the lead welding structure.

[0057] like Figure 2a As shown, the wire bonding structure includes a substrate (not shown) and a circuit layer 110 formed in the substrate, and a bonding pad 120, a barrier layer 130 and a passivation layer 140 are sequentially stacked on the circuit layer 110.

[0058] The substrate may be a semiconductor substrate, specifically a silicon substrate. The circuit layer 110 is an electrical component such as a MOS tube, a diode, a resistor, and a capacitor. The soldering pad 120 is electrically connected to the circuit layer 110 in the lead-out region, and specifically, the soldering pad 120 may be provided only on the circuit layer in the lead-out region. The soldering pad 120 is specifically made of a relatively soft conductive material, such as copper, aluminum, tungsten, and other metal materials.

[0059] The hardness of the barrier layer 130 is greater than that of the pad 120, and can withstand the impact of the pad 120 and prevent the pad 120 from overflowing when welding the lead. The barrier layer 130 can be made of either insulating material or conductive material, for example, it can be made of one or more hard materials such as silicon dioxide, silicon nitride, silicon oxynitride, silicon carbonitride, metal nitride, etc. A preset area A is defined on the barrier layer 130, and the width of the preset area A is smaller than the width of the solder ball after bonding, so that the solder ball after bonding can cover the preset area A. It should be noted that when welding the lead, the hot-melt metal sphere formed by heating the metal wire is pressed on the pad and bonded to form the lead. The metal sphere will become an oblate sphere after being pressed, so the coverage area of ​​the solder ball after bonding is larger than the coverage area of ​​the solder ball before bonding. A first window 131 exposing the solder pad 120 is opened in the preset area A of the barrier layer 130, and the first window 131 does not exceed the preset area A, that is, the opening of the first window 131 does not extend outside the preset area A. Therefore, when the solder ball after wire bonding covers the preset area A, the first window 131 is also covered by the solder ball after wire bonding, and there is no gap between the first window 131 and the solder ball after wire bonding that can cause the solder pad 120 to overflow.

[0060] The passivation layer 140 is formed on the barrier layer 130, but does not cover the preset area A, that is, the passivation layer 140 also has a second window 141, and the opening width of the second window 141 is greater than the width of the preset area A. The entire preset area A can be exposed through the second window 141. At this time, all the first windows 131 and the second windows 141 are connected. Further, the opening width of the second window 141 is greater than the width of the solder ball after wire bonding to avoid limiting the press wire bonding of the solder ball, and is conducive to allowing the solder ball to smoothly avoid the passivation layer 140 and move down to the barrier layer 130 during welding, thereby avoiding the solder ball from being mistakenly welded on the passivation layer 140.

[0061] In the above-mentioned lead welding structure, a barrier layer is arranged between the welding pad and the passivation layer, a preset area is defined on the barrier layer and the width of the preset area is limited to be smaller than the width of the solder ball after wire bonding, a first window is opened in the preset area and the first window does not exceed the preset area, and the entire preset area is exposed through the second window of the passivation layer. In the present application, the lead welding structure is improved as above, when the lead welding is performed by the gold wire ball welding process, the solder ball moves down to the preset area of ​​the barrier layer through the second window, and the solder ball is pressed and wired, and the solder ball after wire bonding is flat and covers the entire preset area. Since the first window is arranged in the preset area, the solder ball after wire bonding can be welded to the welding pad below through the first window, and since the first window does not exceed the preset area, the solder ball after wire bonding covers the preset area and also covers all the first windows, and there is no gap between the first window and the solder ball. At this time, even if the welding pad located below the barrier layer is squeezed, it will not overflow from the barrier layer, thereby ensuring the thickness of the welding pad between the solder ball and the circuit layer, which can avoid the generation of excess conductive particles and prevent the circuit layer from breaking. Therefore, when the above welding structure is subjected to wire welding, it can be ensured that the electrical performance of the device is not affected by the welding process.

[0062] Specifically, the width of the preset area A is smaller than the width of the solder ball after wire bonding, which means that when the solder ball after wire bonding covers the preset area A, on any side section, the width of the preset area A is smaller than the width of the solder ball after wire bonding, so that the preset area A is completely covered by the solder ball after wire bonding. Usually, the area covered by the solder ball after wire bonding is circular, then the preset area A can also be designed to be circular, and the diameter of the preset area A is smaller than the diameter of the area covered by the solder ball after wire bonding. Here, the width of the solder ball after wire bonding can be known in advance based on multiple welding tests, or it can be estimated based on experience. In one embodiment, the width of the preset area A is smaller than the width of the solder ball after wire bonding, and the difference between the width of the preset area A and the width of the solder ball after wire bonding is in the range of 8μm to 12μm. For example, the width of the solder ball after wire bonding ranges from 30μm to 50μm, and the width of the preset area A ranges from 20μm to 40μm. Furthermore, the width of the preset area A is greater than or equal to the width of the solder ball before wire bonding. On the premise that the preset area A can be covered by the solder ball after wire bonding, the area of ​​the preset area A is increased as much as possible, and then the window area in the preset area A can be increased to ensure the welding effect between the solder ball and the solder pad.

[0063] Specifically, there are multiple implementations for designing the first window 131 in the preset area A, and four embodiments are described in detail below.

[0064] Embodiment 1

[0065] like Figure 2a and Figure 2bAs shown, a first window 131 is opened in the preset area A of the barrier layer 130, and the projection of the first window 131 coincides with the projection of the preset area A, that is, the first window 131 is opened in the entire preset area A. On the premise of ensuring that the first window 131 can be completely covered by the pad after wire bonding, the window opening range of the barrier layer 130 is increased as much as possible to expose more solder pads 120, so as to increase the contact area between the solder ball and the solder pad 120 after wire bonding and enhance the welding effect.

[0066] like Figure 2c For Figure 2a and Figure 2b The schematic diagram of the structure after welding the lead on the lead welding structure is shown, wherein the solder ball 210 after wire bonding completely covers the first window on the barrier layer 130, so that there is no gap between the solder ball 210 after wire bonding and the barrier layer 130. Therefore, when the solder ball contacts the welding pad 120 through the first window and squeezes the welding pad 120, the welding pad 120 will not overflow from the barrier layer 130 to form conductive particles, and at the same time, it is ensured that there is a welding pad of a certain thickness between the solder ball 210 after wire bonding and the circuit layer 110 to protect the circuit layer 110.

[0067] Embodiment 2

[0068] like Figure 3a and Figure 3b As shown, a first window 131 is provided in the preset area A, and the first window 131 is annular. Furthermore, the outer edge of the first window 131 coincides with the edge of the preset area A. At this time, the preset area A also includes an island area 132 surrounded by the first window 131. When the solder ball presses the solder pad 120, the island area 132 can buffer and disperse the impact force, so that the impact of the solder ball on the circuit layer 110 is weakened, and the circuit layer 110 is further protected.

[0069] like Figure 3c For Figure 3a and Figure 3bThe schematic diagram of the structure after welding the lead on the lead welding structure shown in the figure, wherein the solder ball 210 after wire bonding completely covers the first window on the barrier layer 130, so that there is no gap between the solder ball 210 after wire bonding and the barrier layer 130. Therefore, when the solder ball contacts the welding pad 120 through the first window and squeezes the welding pad 120, the welding pad 120 will not overflow from the barrier layer 130 to form conductive particles. At the same time, the island area 132 will also move down with the solder ball and embed into the welding pad 120 to form an island support layer 132'. The island area 132 can buffer and disperse the impact force of the solder ball on the welding pad 120, keep the welding pad 120 under the solder ball, so that the welding pad 120 at the bottom of the solder ball has a certain thickness, and further enhance the protection of the circuit layer 110. Furthermore, the width of the island area 132 is smaller than the width of the solder ball before wire bonding. When the solder ball before wire bonding moves downward and contacts the island area 132, part of the solder ball faces the first window 131. When the solder ball presses the wire bonding, it is ensured that the solder ball can fully contact the solder pad 120 to ensure the welding effect.

[0070] In one embodiment, the solder ball before wire bonding is approximately spherical, the area covered by the solder ball before wire bonding is circular, the island area can also be designed to be circular, and the diameter of the island area is smaller than the diameter of the area covered by the solder ball before wire bonding. In a specific embodiment, the width of the island area 132 is smaller than the width of the solder ball before wire bonding, and the difference between the width of the island area 132 and the width of the solder ball before wire bonding is in the range of 8μm to 12μm. For example, the width of the solder ball before wire bonding is in the range of 18μm to 42μm, and the width of the island area 132 is in the range of 10μm to 30μm.

[0071] Embodiment 3

[0072] In one embodiment, if Figure 4a and Figure 4b As shown, a plurality of first windows 131 arranged at intervals may also be provided in the preset area A of the barrier layer 130, each first window 131 being in a strip shape, and all the first windows 131 being arranged in parallel. At this time, the solder pad 120 is exposed through each first window 131, and the solder ball after wire bonding may contact the exposed solder pad 120 through each first window 131. At the same time, when the solder ball is pressed for wire bonding, the barrier layer between adjacent first windows 131 may also disperse and buffer the impact force of the solder ball on the solder pad 120, and keep the solder pad 120 under the solder ball, so that the solder pad 120 at the bottom of the solder ball has a certain thickness to protect the circuit layer 110 below. Specifically, the barrier layer in the preset area A is integrally formed with the barrier layer outside the preset area A to enhance the degree of buffering against the impact force.

[0073] like Figure 4c For Figure 4a and Figure 4bThe schematic diagram of the structure after welding the lead on the lead welding structure shown in the figure, wherein the solder ball 210 after wire bonding completely covers each first window on the barrier layer 130, so that there is no gap between the solder ball 210 and the barrier layer 130, therefore, when the solder ball 210 contacts and squeezes the solder pad 120 through the first window, the solder pad 120 will not overflow the barrier layer 130 to form conductive particles, and at the same time, the barrier layer between adjacent first windows can buffer and disperse the impact force of the solder ball on the solder pad 120, and keep the solder pad 120 under the solder ball, so that the solder pad 120 at the bottom of the solder ball has a certain thickness, further enhancing the protection of the circuit layer 110. It should be noted that when the barrier layer in the preset area A and the barrier layer outside the preset area A are integrally formed, under the impact of the solder ball, the barrier layer in the preset area A may also be deformed and bend toward the solder pad 120.

[0074] Embodiment 4

[0075] like Figure 5a and 5b As shown, a plurality of first windows 131 are provided in the preset area A of the barrier layer 130, and the first windows 131 are evenly distributed in the horizontal and vertical directions, so that the barrier layer in the preset area A is in a grid shape. Figure 5c For Figure 5a and Figure 5b The effect of the fourth embodiment is the same as that of the third embodiment, and will not be described again.

[0076] In the present application, the wire welding structure is improved as described above. When wire welding is performed by the gold wire ball welding process, the solder ball moves down to the preset area of ​​the barrier layer through the second window, and the solder ball is pressed and wired. The solder ball after wire bonding can be welded to the welding pad below through the first window. Since the first window does not exceed the preset area, the solder ball after wire bonding can cover all the first windows, and there is no gap between the first window and the solder ball after wire bonding. At this time, even if the welding pad located below the barrier layer is squeezed, it will not overflow from the barrier layer. At the same time, the thickness of the welding pad between the solder ball and the circuit layer is also guaranteed, which can avoid the generation of excess conductive particles and prevent the circuit layer from breaking. Therefore, when the above welding structure is wire-welded, it can ensure that the electrical performance of the device is not affected by the welding process.

[0077] The present application also relates to a lead welding method, such as Figure 6 As shown, the lead welding method includes the following steps:

[0078] Step S610: Obtain a wire welding structure, the wire welding structure comprising: a substrate; a circuit layer formed in the substrate; a welding pad formed on the circuit layer and electrically connected to the circuit layer in a lead-out area; a barrier layer formed on the welding pad, the hardness of the barrier layer being greater than the hardness of the welding pad, a first window exposing the welding pad being opened in a preset area of ​​the barrier layer and the first window does not exceed the preset area, and a width of the preset area is smaller than a width of the solder ball after wire bonding; and a passivation layer formed on the barrier layer, a second window having a width greater than the preset area being opened on the passivation layer, and the entire preset area is exposed through the second window.

[0079] Specifically, the detailed introduction of the lead welding structure can be referred to the above introduction, which will not be repeated here.

[0080] Step S620: Align the solder ball with the preset area, press and bond the solder ball so that the bonded solder ball covers the preset area to form a lead wire bonded to the pad.

[0081] Specifically, a solder ball is formed by melting the gold wire with an instantaneous high voltage, and the solder ball is sent into the preset area through the first window, and the solder ball is pressed and wired to form a lead welded on the pad. At this time, the coverage area of ​​the solder ball after wire bonding increases, and it can cover the entire preset area, so that there is no gap between the solder ball and the barrier layer after wire bonding. The solder ball is welded to the pad below through the first window, and the pad will not overflow from the barrier layer after being squeezed, which can avoid the formation of excess conductive particles and ensure the thickness of the pad below the solder ball, so as to avoid the circuit layer from being broken by impact. Therefore, in the present application, the lead welding is performed by the above method, which can avoid the influence of the welding process on the electrical performance of the device and improve the product yield.

[0082] The present application also relates to a semiconductor device, such as Figure 2c As shown, the semiconductor device includes a substrate (not shown in the figure) and a circuit layer 110 formed in the substrate, on which a solder pad 120, a barrier layer 130, and a passivation layer 140 are stacked in sequence, and also includes a solder ball 210 after wire bonding and a lead 220 formed by solder ball wire bonding, wherein the solder ball 210 after wire bonding is welded to the solder pad 120.

[0083] The substrate may be a semiconductor substrate, specifically a silicon substrate. The circuit layer 110 is an electrical component such as a MOS tube, a diode, a resistor, and a capacitor. The soldering pad 120 is electrically connected to the circuit layer 110 in the lead-out region, and specifically, the soldering pad 120 may be provided only on the circuit layer in the lead-out region. The soldering pad 120 is specifically made of a relatively soft conductive material, such as copper, aluminum, tungsten, and other metal materials.

[0084] The hardness of the barrier layer 130 is greater than that of the pad 120, and can withstand the impact of the pad 120 and prevent the pad 120 from overflowing when welding the lead. The barrier layer 130 can be made of either insulating material or conductive material, for example, one or more of hard materials such as silicon dioxide, silicon nitride, silicon oxynitride, silicon carbonitride, metal nitride, etc. Figure 2a and Figure 2b As shown, a preset area A is defined on the barrier layer 130, and the width of the preset area A is smaller than the width of the solder ball after wire bonding, so that the solder ball after wire bonding can cover the preset area A. A first window 131 exposing the solder pad 120 is opened in the preset area A of the barrier layer 130, and the first window 131 does not exceed the preset area A, that is, the opening of the first window 131 does not extend outside the preset area A.

[0085] The passivation layer 140 is formed on the barrier layer 130, but does not cover the preset area A, that is, the passivation layer 140 also has a second window 141, and the opening width of the second window 141 is greater than the width of the preset area A. The entire preset area A can be exposed through the second window 141. At this time, all the first windows 131 and the second windows 141 are connected. Further, the opening width of the second window 141 is greater than the width of the solder ball after wire bonding to avoid limiting the press wire bonding of the solder ball, and is conducive to allowing the solder ball to smoothly avoid the passivation layer 140 and move down to the barrier layer 130 during welding, thereby avoiding the solder ball from being mistakenly welded on the passivation layer 140.

[0086] The solder ball is bonded to form the lead 220, and the bonded solder ball 210 covers the preset area A and is embedded in the pad 120. It should be noted that the solder ball is initially a hot-melt metal sphere formed by heating the metal wire, and becomes an oblate sphere when the wire is pressed on the pad. Therefore, the coverage area of ​​the solder ball after bonding is greater than the coverage area of ​​the solder ball before bonding. A first window 131 is provided in the preset area A of the barrier layer 130 to expose the pad 120, and the first window 131 does not exceed the preset area A, that is, the opening of the first window 131 does not extend outside the preset area A. Therefore, when the bonded solder ball 210 covers the preset area A, the first window 131 is also covered by the bonded solder ball 210, and there is no gap between the first window 131 and the solder ball 210 that can cause the pad 120 to overflow.

[0087] The above-mentioned semiconductor device is formed by the above-mentioned lead welding method, wherein a barrier layer is formed between the passivation layer and the pad, a first window is opened on the barrier layer, and the solder ball after wire bonding covers the first window and is welded to the pad below through the first window. The pad metal does not overflow from the barrier layer, thereby ensuring the thickness of the pad at the bottom of the solder ball and not forming excess conductive particles. Therefore, the above-mentioned semiconductor device with leads welded still has good electrical performance.

[0088] Specifically, the width of the preset area A is smaller than the width of the solder ball after wire bonding, which means that when the solder ball after wire bonding covers the preset area A, on any side section, the width of the preset area A is smaller than the width of the solder ball after wire bonding, so that the preset area A is completely covered by the solder ball after wire bonding. Usually, the area covered by the solder ball after wire bonding is circular, then the preset area A can also be designed to be circular, and the diameter of the preset area A is smaller than the diameter of the area covered by the solder ball after wire bonding. Here, the width of the solder ball after wire bonding can be known in advance based on multiple welding tests, or it can be estimated based on experience. In one embodiment, the width of the preset area A is smaller than the width of the solder ball after wire bonding, and the difference between the width of the preset area A and the width of the solder ball after wire bonding is in the range of 8μm to 12μm. For example, the width of the solder ball after wire bonding ranges from 30μm to 50μm, and the width of the preset area A ranges from 20μm to 40μm. Furthermore, the width of the preset area A is greater than or equal to the width of the solder ball before wire bonding. On the premise that the preset area A can be covered by the solder ball after wire bonding, the area of ​​the preset area A is increased as much as possible, and then the window area in the preset area A can be increased to ensure the welding effect between the solder ball and the solder pad.

[0089] In one embodiment, the semiconductor device is formed by welding a lead wire to the lead welding structure mentioned in the above embodiment 1. The lead welding structure can refer to the introduction of the above embodiment 1, and will not be repeated here. The semiconductor device is formed by adding a lead wire welded to the pad on the basis of the lead welding structure. Figure 2c As shown, the solder ball 210 after wire bonding completely covers the first window on the barrier layer 130, so that there is no gap between the solder ball 210 and the barrier layer 130. Therefore, when the solder ball 210 contacts the solder pad 120 through the first window and squeezes the solder pad 120, the solder pad 120 will not overflow from the barrier layer 130 to form conductive particles, and at the same time, it is ensured that there is a solder pad of a certain thickness between the solder ball 210 and the circuit layer 110 to protect the circuit layer 110.

[0090] In one embodiment, in combination Figure 3a and Figure 3b As shown, the predetermined area A of the barrier layer 130 has a first annular window 131 and an island area 132 surrounded by the first window 131, that is, the semiconductor device can be formed by welding a lead to the lead welding structure mentioned in the second embodiment above. Specifically, the semiconductor device is based on the lead welding structure, and a lead welded to the pad is added, wherein the lead welding structure can refer to the introduction of the third embodiment above, and will not be repeated here. Specifically, as Figure 3cAs shown, the solder ball 210 after wire bonding completely covers the first window on the barrier layer 130, so that there is no gap between the solder ball 210 and the barrier layer 130. Therefore, when the solder ball 210 contacts the solder pad 120 through the first window and presses the solder pad 120, the solder pad 120 will not overflow from the barrier layer 130 to form conductive particles. At the same time, the island area 132 moves downward under the pressure of the solder ball and may be embedded in the solder pad 120. Part of the bottom of the solder ball 210 after wire bonding is located on the island area 132. The island area 132 can buffer and disperse the impact force generated by pressing the solder ball on the solder pad 120, keep the solder pad 120 under the solder ball, so that the solder pad 120 at the bottom of the solder ball has a certain thickness, and further enhance the protection of the circuit layer 110.

[0091] In one embodiment, in combination Figure 4a and Figure 4b As shown, a plurality of first windows 131 are provided in a predetermined area A of the barrier layer 130, each of which is in a strip shape and all of which are arranged in parallel. That is, the semiconductor device is formed by welding a lead wire to the lead welding structure mentioned in the third embodiment above. The lead welding structure can refer to the introduction of the third embodiment above, and will not be described here. The semiconductor device is formed by adding a lead wire welded to the pad on the basis of the lead welding structure. Specifically, as Figure 4c As shown, the solder ball 210 after wire bonding completely covers each first window on the barrier layer 130, so that there is no gap between the solder ball 210 and the barrier layer 130. Therefore, when the solder ball 210 contacts and squeezes the solder pad 120 through the first window, the solder pad 120 will not overflow the barrier layer 130 to form conductive particles. At the same time, the barrier layer between adjacent first windows can buffer and disperse the impact force of the solder ball on the solder pad 120, and keep the solder pad 120 under the solder ball, so that the solder pad 120 at the bottom of the solder ball has a certain thickness, further enhancing the protection of the circuit layer 110. It should be noted that when the barrier layer in the preset area A and the barrier layer outside the preset area A are integrally formed, under the impact of the solder ball, the barrier layer in the preset area A may also be deformed and bend toward the solder pad 120.

[0092] In one embodiment, in combination Figure 5a and Figure 5b As shown, a plurality of first windows 131 are provided in a preset area A of the barrier layer 130, so that the barrier layer in the preset area A is in a grid shape, that is, the semiconductor device is formed by welding leads on the lead welding structure mentioned in the fourth embodiment above. The lead welding structure can refer to the introduction of the fourth embodiment above, and will not be repeated here. The semiconductor device is formed by adding a lead welded on the pad on the basis of the lead welding structure. Specifically, as Figure 5cAs shown, the solder ball 210 after wire bonding completely covers each first window on the barrier layer 130, so that there is no gap between the solder ball 210 and the barrier layer 130. Therefore, when the solder ball 210 contacts and squeezes the solder pad 120 through the first window, the solder pad 120 will not overflow the barrier layer 130 to form conductive particles. At the same time, the barrier layer between adjacent first windows can buffer and disperse the impact force of the solder ball on the solder pad 120, and keep the solder pad 120 under the solder ball, so that the solder pad 120 at the bottom of the solder ball has a certain thickness, further enhancing the protection of the circuit layer 110. It should be noted that when the barrier layer in the preset area A and the barrier layer outside the preset area A are integrally formed, under the impact of the solder ball, the barrier layer in the preset area A may also be deformed and bend toward the solder pad 120.

[0093] The above-mentioned semiconductor device forms a barrier layer between the passivation layer and the welding pad. The solder ball after wire bonding covers the barrier layer and is welded to the welding pad below through the first window. The welding pad metal does not overflow from the barrier layer, thereby ensuring the thickness of the welding pad at the bottom of the solder ball and no excess conductive particles are formed. Therefore, the above-mentioned semiconductor device with welded leads still has good electrical performance.

[0094] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A lead welding structure, characterized in that: include: substrate; A circuit layer formed in the substrate; a welding pad formed on the circuit layer and electrically connected to the circuit layer; a barrier layer formed on the pad, the hardness of the barrier layer being greater than the hardness of the pad, a first window exposing the pad being opened in a preset area of ​​the barrier layer and not exceeding the preset area, a width of the preset area being smaller than a width of a solder ball after wire bonding, the barrier layer being an insulating material, the preset area including a support area composed of the insulating material, and a width of the support area being smaller than a width of a solder ball before wire bonding; and A passivation layer is formed on the barrier layer, and a second window having a width greater than that of the preset area is opened on the passivation layer, so that the entire preset area is exposed through the second window.

2. The wire welding structure according to claim 1, characterized in that: A first window is provided in the preset area of ​​the barrier layer. The first window is annular and the outer edge of the first window coincides with the edge of the preset area.

3. The wire welding structure according to claim 2, characterized in that: The preset area includes an island area surrounded by the first window, and the width of the island area is smaller than the width of the solder ball before wire bonding.

4. The wire welding structure according to claim 1, characterized in that: A plurality of first windows arranged at intervals are opened in a preset area of ​​the barrier layer, the first windows are in a strip shape and the first windows are arranged in parallel.

5. The wire welding structure according to claim 1, characterized in that: A plurality of first windows arranged at intervals are provided in a preset area of ​​the barrier layer, and the barrier layer in the preset area is in a grid shape.

6. The wire welding structure according to any one of claims 1 to 5, characterized in that: The opening width of the second window is greater than the width of the solder ball after wire bonding.

7. The wire welding structure according to claim 1, characterized in that: The width of the preset area is 8 μm to 12 μm smaller than the width of the solder ball after wire bonding.

8. A wire welding method, characterized in that: include: Obtaining a lead welding structure, wherein the lead welding structure is the lead welding structure according to any one of claims 1 to 7; The solder ball is aligned with the preset area, pressed and wired, so that the wired solder ball covers the preset area to form a lead wire welded on the pad.

9. A semiconductor device, characterized in that: include: substrate; A circuit layer formed in the substrate; a welding pad formed on the circuit layer and electrically connected to the circuit layer; A barrier layer is formed on the pad, the hardness of the barrier layer is greater than the hardness of the pad, a first window is opened in a preset area of ​​the barrier layer to expose the pad and the first window does not exceed the preset area, the width of the preset area is smaller than the width of the solder ball after wire bonding, the barrier layer is an insulating material, the preset area includes a support area composed of the insulating material, and the width of the support area is smaller than the width of the solder ball before wire bonding; a passivation layer is formed on the barrier layer, a second window is opened on the passivation layer with a width greater than the width of the preset area, and the entire preset area is exposed through the second window; The wire-bonded solder ball covers the preset area and is embedded in the solder pad to be soldered to the solder pad; The lead is connected to the solder ball after the wire bonding.

10. The semiconductor device according to claim 9, wherein: The barrier layer has a first annular window and an island region surrounded by the first window in a preset region, and a portion of the bottom surface of the solder ball after wire bonding contacts the island region.

11. The semiconductor device according to claim 9, wherein A plurality of first windows arranged at intervals are opened in a preset area of ​​the barrier layer, the first windows are in a strip shape and the first windows are arranged in parallel.

12. The semiconductor device according to claim 9, wherein A plurality of first windows arranged at intervals are provided in a preset area of ​​the barrier layer, and the barrier layer in the preset area is in a grid shape.

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