Semiconductor device and its manufacturing method

Abstract

To provide a semiconductor device that has improved secondary mounting reliability.SOLUTION: A semiconductor device comprises: a lead frame that includes a bed part and first lead parts; an organic material that extends between the bed part and the first lead parts; a first semiconductor element that is above an upper part of the bed part; a sealing resin that is above the organic material and the first semiconductor element; and first bonding wires that connect electrodes of the first semiconductor element and the first lead parts to each other. The first bonding wires are in the sealing resin. The first lead parts each include a lead upper side, a lead bottom side on the opposite side of the lead upper side, inner side faces, and outer side faces on the opposite side of the inner side faces. The first bonding wires are joined to the lead upper sides. The length of the lead upper side and the length of the lead bottom side are different from each other.SELECTED DRAWING: Figure 2-1

Description

[Technical field]

[0001] The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device. [Background technology]

[0002] In recent years, in order to keep up with the trend toward smaller electronic devices, there has been a demand for higher density mounting of semiconductor components mounted on electronic devices, and as a result, semiconductor components have become smaller and thinner. For this reason, there is a demand for packages that include resin-sealed semiconductor devices that can achieve further thinning at low cost.

[0003] There are many types of semiconductor packages depending on their shape, material, and corresponding mounting method. Semiconductor packages can be broadly divided into lead insertion types, in which the package leads are inserted into through holes in a printed wiring board and soldered, and surface mount types, in which the package is soldered directly onto the surface of a wiring board. Among these, a type of semiconductor device called a surface mount QFN (Quad Flat Non-leaded package), in which the leads are exposed on the bottom surface of a resin encapsulant rather than on the side surface, has been attracting attention.

[0004] Figure 6 shows the structure of a typical conventional QFN. The semiconductor device 1 comprises a lead frame 2 having a bed portion (semiconductor element mounting portion) 2b and a plurality of lead portions 2a whose tips extend around the bed portion 2b, a semiconductor element 6 placed on the bed portion 2b, bonding wires 3 connecting electrodes 4 of the semiconductor element 6 to each of the lead portions 2a, and a sealing resin 5 that seals the semiconductor element mounting side of the lead frame 2, the semiconductor element 6, and the bonding wires 3. This semiconductor device 1 uses a back tape to prevent resin leakage during a molding process when performing resin sealing, and the back tape is removed after the resin sealing process.

[0005] However, the use of a back tape causes the following problems. Since the resin surface is flush with the lead frame, as shown in FIG. 7A, connection by solder 11 is only on the surfaces of the lead portions 2a and bed portions 2b, making it difficult to improve secondary mounting reliability. If the adhesion of the back tape 12 is poor, mold resin burrs 5a will occur as shown in FIG. 7B. Conversely, if the adhesion is too good, adhesive residue 12a of the back tape 12 will remain when peeled off. In either case, this will reduce reliability. The lead frame 2 has a metal base material, so even if the surface of the base material is roughened or otherwise improved, it does not adhere well to the mold resin, which is an organic material. When an evaluation was performed under an accelerated environment to determine the reliability guarantee period, internal peeling 13 occurred after a certain period of time due to damage caused by repeated stress, thermal damage caused by high temperatures, chemical damage caused by humidity, etc., as shown in Figure 7C.

[0006] Patent Document 1 describes a method for manufacturing a semiconductor device in which, during the QFN manufacturing process, metal plating is applied to the exposed surfaces of the leads before resin sealing, and after resin sealing, the metal plating is chemically removed, thereby simultaneously removing resin burrs that have occurred on the exposed lead surfaces.

[0007] In addition, in Patent Document 2, as shown in FIG. 8, a semiconductor element 24 is mounted on a bed portion 22 of a lead frame 21, and a bonding wire 25 electrically connects an electrode of the semiconductor element 24 to a lead portion 23 of the lead frame. The semiconductor device 20 shown in the figure is provided with a sealing resin 26 that seals the lead portions 23, and a resin 27 that is filled on one side of the opening of the lead frame 21 to a thickness that is a predetermined thickness d thinner than the thickness of the lead frame 21. This semiconductor device has the lead portions 23 and bed portions 22 protruding at a uniform height from the back surface of the semiconductor device 20, thereby improving the reliability of the semiconductor device 20 when it is mounted. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2001-156233 A [Patent Document 2] JP 2002-93982 A Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention aims to provide a semiconductor device with improved secondary mounting reliability by eliminating the conventional method of providing a back tape on the side of the lead frame opposite the semiconductor element mounting surface during resin sealing. [Means for solving the problem]

[0010] That is, the present invention is as described below. (1) a lead frame consisting of a lead portion and a bed portion; an organic material layer that covers at least the space of the lead frame from the semiconductor element mounting surface side; an opening provided in an organic material layer in a lead portion to be connected to a bonding wire; A semiconductor element mounted on the bed portion; a bonding wire that electrically connects the lead portion of the opening to an electrode of a semiconductor element; a sealing resin for sealing the organic material layer, the bonding wires, and the semiconductor element; A semiconductor device having the above structure. (2) The semiconductor device according to (1) above, wherein the organic material layer is also formed on a semiconductor element mounting position of the bed portion, and the semiconductor element is mounted on the organic material layer at this semiconductor mounting position. (3) The semiconductor device according to (1) above, wherein the organic material layer also has an opening at a position on the bed portion where a semiconductor element is to be mounted, and the semiconductor element is mounted on the bed portion through the opening at the position where the semiconductor element is to be mounted. (4) The semiconductor device according to (1) above, comprising a plurality of semiconductor elements, the semiconductor elements being mounted on an organic material layer formed on a bed portion, and a semiconductor element being mounted on the bed portion in an opening formed in the organic material layer. (5) The semiconductor device according to any one of (1) to (4) above, wherein at least a portion of the periphery of the bed portion and / or the periphery of the lead portion has a step. (6) forming an organic material layer on a semiconductor element mounting surface side of a lead frame having a bed portion and a lead portion; forming an opening A in an organic material layer formed at a connection portion between the lead portion and a bonding wire; forming an opening B in the organic material layer at a position where a semiconductor element is mounted on the bed portion; forming a plating film in an opening A of an organic material layer formed at a connection portion between the lead portion and a bonding wire; fixing a semiconductor element to the bed portion at the opening of the bed portion with an adhesive; a step of electrically connecting the electrodes of the semiconductor element and the plating film of the lead portion by bonding wires; a step of sealing the semiconductor element, the bonding wires, and the organic material layer with a sealing resin; A method for manufacturing a semiconductor device comprising the steps of: (7) A method for manufacturing a semiconductor device according to (6) above, comprising the steps of: forming an opening A in an organic material layer formed at a connection portion of the lead portion with a bonding wire; and forming an opening B in the organic material layer at a semiconductor element mounting position of the bed portion. (8) forming an organic material layer on a semiconductor element mounting surface side of a lead frame having a bed portion and a lead portion; forming an opening A in an organic material layer formed at a connection portion between the lead portion and a bonding wire; forming an opening B at at least one of the plurality of semiconductor element mounting positions of the bed portion; forming a plating film in the opening A; a step of fixing a semiconductor element on the organic material layer by an adhesive at the semiconductor element mounting position having the organic material layer, and fixing a semiconductor element on the bed portion by an adhesive at the semiconductor element mounting position having the opening B; a step of electrically connecting the electrodes of the semiconductor element and the plating film of the lead portion by bonding wires; a step of sealing the semiconductor element, the bonding wires, and the organic material layer with a sealing resin; A method for manufacturing a semiconductor device comprising the steps of: (9) A method for manufacturing a semiconductor device according to (8) above, comprising the steps of: forming an opening A in an organic material layer formed at a connection portion between the lead portion and a bonding wire; and forming an opening B in at least one of the semiconductor element mounting positions of the bed portion. Effect of the Invention

[0011] By using the semiconductor device of the present invention, the secondary mounting reliability of the semiconductor device can be improved. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a semiconductor device according to a first embodiment of the present invention. [Figure 2-1] FIG. 2-1 is a diagram showing a semiconductor device according to a second embodiment of the present invention. [Figure 2-2] FIG. 2-2 is a diagram showing the structure of a lead frame in the semiconductor device shown in FIG. 2-1. [Figure 3-1] FIG. 3-1 is a diagram showing a semiconductor device according to a third embodiment of the present invention. [Figure 3-2] FIG. 3-2 is a diagram showing the lead frame and the organic material layer in the semiconductor device shown in FIG. 3-1. [Figure 4] FIG. 4 is a diagram showing a semiconductor device according to a fourth embodiment of the present invention. [Diagram 5]5A to 5E are diagrams illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention. In each diagram, (a) is a plan view, and (b) is a cross-sectional view. FIG. 5A is a diagram showing a lead frame. FIG. 5B is a diagram showing a state in which an organic material layer has been formed on the surface of the lead frame. FIG. 5C is a diagram showing a state in which an opening for a wire connection portion has been formed in the organic material layer on the lead portion of the lead frame. FIG. 5D is a diagram showing a state in which a plating film has been formed in the opening for the wire connection portion. FIG. 5E is a diagram showing a state in which a semiconductor element has been mounted on the organic material layer on the semiconductor element mounting portion of the lead frame. [Figure 6] FIG. 6 is a cross-sectional view of a conventional semiconductor device. [Figure 7] Figures 7A to 7C are cross-sectional views of a conventional semiconductor device. Figure 7A is a diagram showing solder attached to a lead frame. Figure 7B is a diagram showing a state in which the back tape is being peeled off from the semiconductor device. Figure 7C is a diagram showing a state in which internal peeling of the sealing resin has occurred within the semiconductor device. [Figure 8] FIG. 8 is a cross-sectional view of a conventional semiconductor device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It is easy for anyone to modify or alter the present invention within the scope of the claims to create other embodiments, and these modifications and alterations are intended to be included in the scope of the claims. The following description illustrates examples of embodiments of the present invention and does not limit the scope of the claims.

[0014] (First embodiment) The semiconductor device of this embodiment is shown in FIG. The semiconductor device 1 shown in FIG. 1 comprises a lead frame 2 having a lead portion 2a and a bed portion 2b, an organic material layer 10 covering the semiconductor element mounting surface side of the lead frame 2 and having an opening 9, a semiconductor element 6 mounted on the semiconductor element mounting portion 2b via the organic material layer 10 and an adhesive layer 7, a plating film 8 formed on the lead portion 2a in the opening 9, bonding wires 3 electrically connecting the electrodes 4 of the semiconductor element 6 to the plating film 8, and a sealing resin 5 for sealing the semiconductor element 6 with resin.

[0015] In the semiconductor device of this embodiment, since the organic material layer 10 covers the space of the lead frame 2, the molding resin does not flow around to the terminal surface of the lead frame 2 when performing resin sealing, and therefore in addition to the bottom surface of the lead portion 2a, the side surface 2c of the lead portion 2 can also be secured as a mounting surface. As a result, fillets are formed in all directions on both the lead portion 2a and the bed portion 2b, improving the secondary mounting reliability.

[0016] In addition, in the semiconductor device of this embodiment, since the organic material layer 10 is used as a component of the semiconductor device instead of a back tape (mold tape) for preventing resin leakage during resin sealing, there is no need to peel off the back tape, and no adhesive residue is left behind. In addition, a cost reduction effect can be expected. The material of the organic material layer 10 is preferably one that is durable against the injection pressure of the mold, and a dry film or LαZ, a high Tg material manufactured by Sumitomo Bakelite Co., Ltd., can be used.

[0017] In the semiconductor device of this embodiment, an opening 9 is provided in a part of the organic material layer 10 formed on the lead portion 2a, and the surface of the lead portion 2a at this opening 9 is plated. This makes it possible to minimize the metal exposed area of ​​the lead frame 2 on the semiconductor element mounting surface side, which is expected to result in strong adhesion between the organic material layer 10 and the sealing resin 5, and to be effective in suppressing peeling in various reliability evaluations.

[0018] A method for manufacturing the semiconductor device according to the first embodiment will be described with reference to Figures 5A to 5E. The semiconductor device is fabricated by collectively manufacturing a large number of semiconductor devices using a lead frame formed by connecting a plurality of unit lead frames using tie bars, and finally singulating the semiconductor devices into individual semiconductor devices. The unit lead frame 2 is composed of a bed portion 2b formed in the center and lead portions formed around the bed portion at intervals. Hereinafter, the unit lead frame may be simply referred to as a "lead frame." In each figure, (a) on the left side is a plan view of a part of the lead frame and semi-finished product in the manufacturing process of the semiconductor device, and (b) on the right side is a cross-sectional view of the unit lead frame and semi-finished product of the unit semiconductor device.

[0019] <Lead frame preparation process (see Figure 5A)> A sheet-like lead frame is prepared in which a plurality of unit lead frames 2, each having a bed portion 2b and a lead portion 2a surrounding the bed portion 2b, are connected together. The lead frame is made of a thin metal plate made of a good conductor such as an iron-based alloy or a copper-based alloy, which is etched. The lead frame is then processed to form a plurality of unit lead frames. In the following, the side of the lead frame on which a semiconductor element is mounted is referred to as the front side, and the side opposite the side on which the semiconductor element is mounted is referred to as the back side.

[0020] <Organic material layer formation process (see FIG. 5B)> An organic material layer 10 is formed on the front surface of the lead frame 2 . By forming the organic material layer 10 on the front surface of the lead frame 2, the space between the lead portion 2a and the bed portion 2b of the lead frame 2 is covered with the organic material layer 10.

[0021] <Bonding Wire Connection Portion Opening Forming Process (see FIG. 5C)> An opening 9 is formed in the organic material layer 10 formed on the bonding wire connection portion of the lead portion 2a. This hole making process can be performed by using a CO2 laser or a YAG laser.

[0022] <Plating process (see FIG. 5D)> A plating film 8 made of a conductive metal is formed in the opening 9 of the lead portion 2a by electrolytic plating. This plating film 8 is provided to improve the electrical connection between the lead portion 2a and the bonding wire. The thickness of the plating film 8 is preferably 1.0 μm to 10.0 μm.

[0023] <Semiconductor element mounting process (see Fig. 5E)> A semiconductor element 6 is fixed onto the bed portion 2b of the lead frame 2 via an adhesive layer 7. As the adhesive 7, an adhesive such as silver paste or an adhesive tape can be used.

[0024] The subsequent steps (wire bonding step, resin sealing step, and singulation step) can be performed in the same manner as in the conventional method, but the subsequent steps are described below.

[0025] <Wire bonding process> The electrode pads 4 of the semiconductor element 6 and the plating films 8 of the corresponding lead portions 2a are connected by bonding wires 3 which are connecting members.

[0026] <Resin sealing process> The semiconductor element 6 is sealed with a sealing resin 5 . In the resin sealing process, the side surfaces of the lead portion 2a and the bed portion 2b are not covered with the sealing resin because the organic material layer 10 is formed on the front surface of the lead frame 2. Therefore, the side surfaces of the lead portion 2a and the bed portion 2b can also be secured as mounting surfaces, and fillets are formed in all directions in both the lead portion 2a and the bed portion 2b of the lead frame, improving secondary mounting reliability. Furthermore, since no back tape is used for resin sealing, no resin burrs are generated and no adhesive residue is left behind when the back tape is peeled off, improving secondary mounting reliability.

[0027] <Semiconductor element individualization process> A plurality of semiconductor devices formed for each of a plurality of unit frames on the lead frame are singulated into individual semiconductor devices.

[0028] Second Embodiment The semiconductor device of this embodiment is shown in FIG. The semiconductor device of this embodiment is similar to the semiconductor device of embodiment 1 in that the thickness of the periphery of the lead portion 2 and the periphery of the bed portion 2b is reduced to provide a step portion s. FIG. 2-2 shows the shape of the lead frame 2 of the semiconductor device of the second embodiment. The peripheral portion of the lead portion 2a and the peripheral portion of the bed portion 2b are removed by etching to a predetermined thickness d to provide a step portion s. This step portion s can improve the adhesion between the organic material layer 10 and the lead frame 2. The step s may be provided in a part of the periphery of the lead portion 2a and the bed portion 2b.

[0029] (Third embodiment) The semiconductor device of this embodiment is shown in FIG. In the semiconductor device of this embodiment, in the semiconductor device of embodiment 1, an opening 14 is provided in the semiconductor element mounting region of the organic material layer 10 formed on the bed portion 2b as shown in FIG. 3-2, and the semiconductor element 6 is adhered and fixed to the bed portion 2b via an adhesive layer 7. In this way, by directly fixing the semiconductor element 6 to the bed portion 2b, it becomes possible to efficiently dissipate heat generated by the operation of the semiconductor element to the outside. The openings 9 and 14 may be formed simultaneously, or the step of forming the openings 9 and the step of forming the openings 14 may be separate.

[0030] When openings 9 and 14 are formed simultaneously, a method can be employed in which, in the step of forming plating film 8, openings 14 are covered with a plating mask and plating film 8 is formed. When the process of forming opening 9 and the process of forming opening 14 are provided separately, a method can be adopted in which opening 9 is first formed and plating film 8 is then formed, and then opening 14 is formed. Since it is preferable to perform the opening step in one go, it is preferable to adopt the former method.

[0031] (Fourth embodiment) The semiconductor device of this embodiment is shown in FIG. A plurality of semiconductor elements may be mounted on the bed portion 2b, and semiconductor components may also be mounted in addition to the semiconductor elements. In this embodiment, an example is shown in which two semiconductor elements (6a, 6b) are mounted on the bed portion 2b. The semiconductor device of this embodiment is the semiconductor device of embodiment 1, except that a plurality of semiconductor elements 6a and 6b are mounted on bed portion 2b. FIG. 4 shows an example in which a semiconductor element 6a is mounted on the bed portion 2b via an organic material layer 10, and a semiconductor element 6b is mounted on the bed portion 2b without an organic material layer 10 therebetween. The semiconductor elements 6a and 6b may be mounted on the bed portion 2b via the organic material layer 10, or the semiconductor elements 6a and 6b may be mounted on the bed portion 2b without the organic material layer 10 therebetween. By using such a structure, it is possible to provide a multi-functional semiconductor device. Also, by opening the organic material layer 10 according to the characteristics of the semiconductor element, it is possible to realize a package structure suited to the characteristics of the semiconductor element. [Explanation of symbols]

[0032] 1 Semiconductor device 2 Lead Frame 2a Lead part 2b Bed section (semiconductor element mounting section) 2c Lead frame side 3 Bonding Wire 4 electrodes 5 Sealing resin 6, 6a, 6b Semiconductor elements 7 Adhesive layer 8 Plating film 9 Openings 10 Organic material layer 11 Solder 12 Back Tape 12a Glue residue 13 Internal peeling 14 Openings 20 Semiconductor Devices 21 Lead frame 22 Bed section 23 Lead section 24 Semiconductor elements 25 Bonding Wire 26 Sealing resin 27 Resin d Thickness s Step

Claims

1. a lead frame including a bed portion and a first lead portion; an organic material extending between the bed portion and the first lead portion; A first semiconductor element above the upper side of the bed portion; a sealing resin above the organic material and the first semiconductor element; a first bonding wire connecting an electrode of the first semiconductor element and the first lead portion; the first bonding wire is in the sealing resin; the first lead portion includes a lead top side, a lead bottom side opposite the lead top side, an inner side surface, and an outer side surface opposite the inner side surface; a first bonding wire is coupled to an upper side of the lead; The length of the top side of the lead is different from the length of the bottom side of the lead, A semiconductor device, wherein a portion of the organic material is between the lead frame and the sealing resin.

2. The semiconductor device of claim 1 , wherein the outer side surface of the first lead portion is free of the organic material.

3. The semiconductor device according to claim 1 , wherein the outer side surface of the first lead portion is flush with the sealing resin.

4. The semiconductor device according to claim 1 , wherein a portion of said first lead portion is outside said sealing resin.

5. The semiconductor device according to claim 1 , wherein the first lead portion includes a stepped shape.

6. 2. The semiconductor device of claim 1, wherein a portion of said organic material is in said bed portion of said lead frame.

7. 2. The semiconductor device according to claim 1, wherein the first bonding wire is connected to the first lead portion through an opening in the organic material.

8. A plurality of semiconductor elements including the first semiconductor element; a plurality of bonding wires including the first bonding wire; a plurality of leads including the first lead portion; the plurality of semiconductor elements are located above the bed portion, 2. The semiconductor device according to claim 1, wherein each of said plurality of bonding wires is connected to one electrode of said plurality of semiconductor elements and one of said plurality of leads.

9. a lead frame including a bed portion and a first lead portion; an organic material extending between the bed portion and the first lead portion; A first semiconductor element above the upper side of the bed portion; a sealing resin above the organic material and the first semiconductor element; a first bonding wire connecting an electrode of the first semiconductor element and the first lead portion; the first bonding wire is in the sealing resin; the first lead portion includes a lead top side, a lead bottom side opposite the lead top side, an inner side surface, and an outer side surface opposite the inner side surface; a first bonding wire is coupled to an upper side of the lead; The length of the top side of the lead is different from the length of the bottom side of the lead, The organic material covers the outer side surface of the first lead portion.

10. The semiconductor device according to claim 9 , wherein the inner side surface is covered with the organic material.

11. The semiconductor device according to claim 9 , wherein the outer side surface of the first lead portion is flush with the sealing resin.

12. The semiconductor device according to claim 9 , wherein a portion of said first lead portion is outside said sealing resin.

13. 10. The semiconductor device according to claim 9, wherein a portion of said organic material is between said lead frame and said sealing resin.

14. The semiconductor device according to claim 9 , wherein the first lead portion includes a stepped shape.

15. 10. The semiconductor device of claim 9, wherein a portion of said organic material is in said bed portion of said lead frame.

16. 10. The semiconductor device according to claim 9, wherein the first bonding wire is connected to the first lead portion through an opening in the organic material.

17. A plurality of semiconductor elements including the first semiconductor element; a plurality of bonding wires including the first bonding wire; a plurality of leads including the first lead portion; the plurality of semiconductor elements are located above the bed portion, 10. The semiconductor device according to claim 9, wherein each of said plurality of bonding wires is connected to one electrode of said plurality of semiconductor elements and one of said plurality of leads.

18. providing a lead frame including a bed portion and a first lead portion; providing an organic material extending between the bed portion and the first lead portion; A first semiconductor element is provided above an upper side of the bed portion; providing a first bonding wire that connects an electrode of the first semiconductor element and the first lead portion; A method for manufacturing a semiconductor device, comprising the steps of: supplying a sealing resin above the organic material and the first semiconductor element, the first lead portion includes a lead top side, a lead bottom side opposite the lead top side, an inner side surface, and an outer side surface opposite the inner side surface; The length of the top side of the lead is different from the length of the bottom side of the lead, the first bonding wire is coupled to an upper side of the lead and is within the sealing resin; A part of the organic material is between the lead frame and the sealing resin.

19. The method of claim 18 , wherein the exterior side of the first lead portion is free of the organic material.

20. The method of claim 18 , wherein the exterior side of the first lead is flush with the encapsulation compound.

21. The method of claim 18 , wherein a portion of the first lead portion is outside the encapsulation resin.

22. The method of claim 18 , wherein the first lead portion includes a step shape.

23. 20. The method of claim 18, wherein a portion of the organic material is in the bed portion of the leadframe.

24. 20. The method of claim 18, wherein the first bond wire connects to the first lead through an opening in the organic material.

25. A plurality of semiconductor elements including the first semiconductor element; a plurality of bonding wires including the first bonding wire; providing a plurality of leads including the first lead portion; the plurality of semiconductor elements are located above the bed portion, 20. The method of claim 18, wherein each of the plurality of bonding wires is connected to an electrode of one of the plurality of semiconductor elements and one of the plurality of leads.

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