JP5002329B2 - Semiconductor device and wire bonding method - Google Patents

Abstract

The invention relates to a semiconductor device and a wire bonding method. In the semiconductor device, a wire is stacked on a pad (3) as a second bonding point to form a bump (21) having a sloped wedge (22) and a first bent wire convex portion (21), and a wire (12) is looped from a lead as a first bonding point to the bump (21) and is pressed to the sloped wedge (22) of the bump (21) with a face portion (33) of a tip end of a capillary to bond the wire to the bump (21). At the same time, the wire (12) is pressed to the first bent wire convex portion (25) using an inner chamfer (31) of a bonding wire hole in the capillary to form a wire bent portion (20) having a bow-shaped cross section. The wire (12) is pulled up and cut at the wire bent portion (20). In the semiconductor device, improved bondability between a wire and a bump and cutting property of the wire to improve the bonding quality are provided.

Description

  The present invention relates to a structure of a semiconductor device and a wire bonding method.

  An assembly process for a semiconductor device such as an IC includes a wire bonding process for connecting a semiconductor chip and a lead frame with a wire. The wire bonding step uses a capillary through which a wire is inserted, forms a ball at the tip of the wire protruding from the capillary by discharge from the torch electrode, and after the primary bonding is performed by positioning the capillary on the pad of the semiconductor chip In general, a method of connecting the semiconductor chip and the lead frame with a wire by moving the capillary onto the lead of the lead frame and performing secondary bonding is generally used (see, for example, Patent Document 1).

  In this case, a gold wire is often used as the wire. Gold is excellent in bondability with gold of the same material, but is poor in bondability with materials such as copper, nickel, flash gold plating, etc., and pad or lead material is, for example, copper, nickel, flash If the material is poorly bonded to the gold wire, such as gold plating, the gold wire cannot be bonded directly on the pad or lead. For this reason, a method of forming a bump by ball bonding using a gold wire on a pad or a lead and bonding the gold wire on the bump is used.

  According to this method, since the gold wire is bonded onto the bump formed of gold of the same material, the bondability of the gold wire is improved, and the pad or lead formed of the material having poor bondability with gold is used. It is possible to improve the bondability between the two. However, if the bump upper surface does not have a sufficient inclination and flat surface for bonding the gold wire, the bonding failure due to insufficient bonding area, or the gold wire deforms downward after bonding the bump and the gold wire, and the lead frame or semiconductor chip. There was a problem that contact occurred between the two.

  Therefore, in the prior art described in Patent Documents 1 and 2, a slant wedge is formed by pressing a capillary on the bump upper surface after ball bonding in order to form a sufficient tilt and flat surface for gold wire bonding on the bump upper surface. A method of bonding a gold wire to an inclined wedge on the bump has been proposed.

  For example, as shown in FIG. 15A, the first bumps 21 a and the first bumps 21 a and the first bumps 21 are arranged on the pads 3 of the semiconductor chip 2 so that the inclined surface of the inclined wedge 22 is opposite to the leads 4. A bump 21 composed of a two-step bump 21b is formed, and a ball 5 is formed on the tip of the wire 12 by discharging spark or the like. Then, as shown in FIG. 15 (b), the ball 5 is pressed onto the lead 4 to perform primary bonding to form a press-bonded ball 6, and the lead 4 is connected to the pad 3 as shown in FIG. 15 (c). There is a wire bonding method in which the capillary 16 is moved to loop the wire 12, the wire 12 is pressed against the inclined wedge 22 of the bump 21 to perform secondary bonding, and then the wire 12 is cut. Further, as shown in FIG. 16, a bump 21 having an inclined wedge 22 is formed on the lead 4 so that the inclined surface is opposite to the semiconductor chip 2, and primary bonding is performed on the pad 3 of the semiconductor chip 2. There is a method in which after forming the press-bonded ball 6, the wire 12 is looped toward the lead 4 to perform secondary bonding on the inclined wedge 22 of the bump 21. According to such a method, since the wire 12 is bonded along the inclined wedge 22 of the bump 21, the bonding area of the inclined wedge 22 is increased, the bonding strength is improved, and the wire 12 is supported by the inclined wedge 22. Therefore, contact between the wire 12 and the semiconductor chip or the lead frame 15 can be prevented.

  On the other hand, there has been a problem that bending of the wire tip occurs during wire cutting in the wire bonding process. For this reason, there is a problem that the connection wires are bent in an S shape after bonding, and defects such as contact between adjacent connection wires occur. In order to solve this problem, for example, before the wire is pulled up and cut, the position of the capillary and the clamper is moved laterally, and the wire crushing portion formed so as to be narrowed up is pulled up (for example, And a wire crushing portion formed by narrowing the wire by resonating the tail wire by vibrating the capillary at the natural frequency of the tail wire after the tail wire is led out by opening the clamper. A method of cutting and preventing wire bending during wire cutting has been proposed (see, for example, Patent Document 4).

Japanese Patent No. 3570551 JP 2004-247672 A Japanese Patent No. 2723277 Japanese Patent No. 2969953

  However, as shown in FIG. 17, when the bonding area of the wire 12 and the bump 21 is increased by bonding the wire 12 to the inclined wedge 22 on the pump 21, the wire crushing between the wire 12 and the bump 21 is performed. The cross-sectional shape of the part 20 may not become thin. In such a case, in the related art as described in Patent Document 3, when the wire 12 is gripped by the clamper 17 and pulled up, a large tension is applied to the wire 12 and the wire 12 is stretched. Then, since the wire 12 is cut by the thick wire crushing portion 20, the stretched wire 12 jumps upward by a reaction force at the time of cutting and bends in an S shape. The bending of the wire 12 is caused by defective ball formation due to discharge or the like during bonding to the next pad 3, or bonding by the bent wire remaining inside the capillary 16 or between the capillary 16 and the clamper 17 as shown in FIG. As shown in FIG. 2, there is a problem that the connection wire 12 is bent in an S shape and a defect such as contact between adjacent connection wires 12 occurs.

  In the prior art described in Patent Document 4, it is necessary to apply ultrasonic vibration for a long time in order to cut the thick wire crushing portion 20, and the connection between the capillary 16 of the wire 12 and the bonding point is required. Since the resonance of the tail wire 18 extending between them is used, the method cannot be applied to a short tail wire and cannot be applied to a high-speed bonding apparatus having a short tail wire.

  As described above, when the wire 12 is connected between the pad 3 of the semiconductor chip 2 or the lead 4 of the lead frame 15 formed of a metal material having poor bonding property to the wire, bonding is performed to improve the bonding property. The formation of the bump 21 having a good shape and the cutting ability of the wire 12 after bonding to the bump 21 are contrary to each other. In the conventional technique, if the bonding ability is improved, the cutting ability of the wire 12 is deteriorated. There was a problem that bending occurred.

  Therefore, an object of the present invention is to improve the bonding quality between the wire and the bump and improve the cutting property of the wire and improve the bonding quality.

The semiconductor device of the present invention is a semiconductor device in which a wire is connected between a first bond point and a second bond point, and is formed by bending and laminating a wire on the second bond point. A bump including a wire bent convex portion on the opposite side, a tensile cut surface extending from the first bond point side to the bump and bonded to the bump upper surface, and having a shear cut surface and a cross sectional area smaller than the wire cross sectional area on the wire bent convex portion side And a wire including.

  The semiconductor device of the present invention is a semiconductor device in which a first bond point and a second bond point are connected by a wire, and is formed by bending and laminating a wire on the second bond point, and is on the first bond point side. And a bump including a wire bending convex portion on the opposite side to the first bond point, extending from the first bond point side to the bump and bonded to the upper surface of the bump, and shearing on the wire bending convex portion side opposite to the first bond point A wire including a cut surface and a tensile cut surface having a smaller cross-sectional area than the wire cross-sectional area.

Further, in the semiconductor device of the present invention, the bump is an inclined wedge including an inclined surface which is on the upper surface on the first bond point side and whose height decreases along the direction from the first bond point to the second bond point. The wire is bonded to the upper surface of the bump along the inclined wedge, and the bump is provided on the upper surface adjacent to the wire bending convex portion on the first bond point side. Including an inclined wedge including an inclined surface whose height decreases along the direction from the first bond point to the second bond point, and the wire is bonded to the bump upper surface along the inclined wedge;
Also to be suitable as a shear cut surface substantially parallel to the surface of a semiconductor device including a second bonding point, tensile cut surface that is arcuate cross-sectional shape, also Ru suitable der as.

The wire bonding method of the present invention is a wire bonding method in which a first bond point and a second bond point of a semiconductor device are connected by a wire, and the wire is bent and laminated on the second bond point. A bump forming process for forming a bump including a wire bending convex part on the opposite side of the point, a loop of the wire from the first bond point toward the bump, and the wire is pressed against the upper surface of the bump by the face part at the tip of the capillary to join the wire A bonding step, and after raising the capillary from the upper surface of the bump to a position where the tip height is lower than the upper end height of the wire bending convex portion, the capillary is moved in a direction from the first bond point toward the wire bending convex portion, A part of the wire is sheared and cut by the corner, and the wire is cut by the inner chamfer of the capillary. A wire crushing portion forming step of forming a wire crushing portion having a cross-sectional area smaller than the wire cross-sectional area by pressing the wire against the wire bending convex portion; and a wire cutting step of lifting the wire and cutting the wire at the wire crushing portion; It is characterized by having.

  The wire bonding method of the present invention is a wire bonding method in which a first bond point and a second bond point of a semiconductor device are connected by a wire, and the first bond is formed by bending and laminating the wire on the second bond point. A wire bending convex part is formed on the opposite side of the point, the wire is pressed by the face part of the capillary tip to form an inclined wedge on the upper surface on the first bond point side, and the tip height is the upper end of the wire bending convex part from the upper surface of the inclined wedge After raising the capillary to a position lower than the height, the capillary is moved in the direction from the inclined wedge toward the wire bending convex part, and a part of the wire is sheared by the corner of the capillary, and the inner chamfer part of the capillary Wire crushing with a smaller cross-sectional area than the wire cross-sectional area by pressing the wire against the wire bending projection A bump forming step of pulling up the wire and cutting the wire at the wire crushing portion, looping the wire from the first bond point toward the bump, and pressing the wire against the upper surface of the inclined wedge by the face portion of the capillary tip A bonding step for bonding the wire, and after raising the capillary to a position where the tip height is lower than the upper end height of the wire bending convex portion from the upper surface of the inclined wedge, the capillary is moved in a direction from the inclined wedge toward the wire bending convex portion, A wire crushing portion that shears and cuts a part of the wire by the corner of the capillary and presses the wire against the wire bending convex portion by the inner chamfer portion of the capillary to form a wire crushing portion having a smaller cross-sectional area than the wire cross-sectional area Forming process and pulling the wire And having a wire cutting step of cutting the wire at the crushed part.

  In the wire bonding method of the present invention, it is also preferable that the shear-cut surface is substantially parallel to the surface of the semiconductor device including the second bond point, and the wire crushing portion has an arcuate cross-sectional shape. is there.

  The present invention has an effect that the bonding quality between the wire and the bump can be improved and the cutting property of the wire can be improved to improve the bonding quality.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

Before describing an embodiment of the present invention, a reference example of the present invention will be described. As shown in FIG. 1, a semiconductor device 14 according to a reference example of the present invention includes a lead frame 15 provided with leads 4, a semiconductor chip 2 attached to the lead frame 15 by die bonding, and the semiconductor chip 2. The bumps 21 formed on the pads 3 formed on the wires 3 and the wires 12 connecting the leads 4 and the bumps 21 are provided. The wire 12 is looped and bonded to the bump 21 from the press-bonded ball 6 formed on the lead 4 by bonding. The wire 12 is a gold wire, and the pad 3 and the lead 4 are made of a material having poor bondability with gold, such as copper, nickel, and flash gold plating.

  As shown in FIG. 2, the bump 21 formed on the pad 3 includes, in order from the surface of the pad 3, the first-stage bump 21a composed of the press-bonded ball 6 and the bump wire 21a ′ pressed thereon, 4, the first wire bending convex portion 25 formed in the opposite direction to the wire 4, the second step bump 21 b formed by pressing the wire 12 from above the first step bump, and the second step formed on the lead 4 side. The wire bending convex portion 27, the inclined wedge 22 on the upper surface of the bump, and the wire cutting surface 29 obtained by cutting the wire 12 when the wire 12 is bent to form the bump 21, and the wire 12 is bent and laminated. Yes. The wire 12 is subjected to primary bonding on the lead 4 that is the first bond point to form the press-bonded ball 6, and then looped toward the bump 21 to form the bump formed on the pad 3 that is the second bond point. A wire cutting surface 19 is provided on the side of the first wire bending convex portion 25 which is joined to the inclined wedge 22 on the upper surface of the bump 21 and formed in the direction opposite to the lead 4 of the bump 21.

  The center of the upper surface of the bump 21 is a concave portion, and the first and second wire bending convex portions 25 and 27 on both sides along the connecting direction of the wire 12 are convex upward. The inclined wedge 22 is an inclined plane formed from the central concave portion toward the second wire bending convex portion 27 on the lead 4 side which is the first bond point. As described above, the inclination of the inclined wedge 22 is high on the side of the lead 4 that is the first bond point, and is low along the direction from the first bond point toward the pad 3 side of the second bond point. It has a slope like this. The wire 12 is bonded along the surface of the inclined wedge 22.

  The upper surface of the bump 21 has a slope that becomes higher from the central concave portion toward the first wire bending convex portion 25 on the opposite side of the lead 4 as the first bond point. Along the first wire bending convex portion 25, a wire cutting surface 29 for bump formation and a wire cutting surface 19 for wire bonding are located.

  FIG. 3 is a plan view of the wire 12 bonded to the bump 21. As shown in FIG. 3, the first wire bending convex portion 25 of the bump 21 projects in a direction opposite to the lead 4 that is the first bond point, and the second wire bending convex portion 27 is the direction of the lead 4 that is the first bond point. Overhangs. As can be seen from FIG. 1 and FIG. 2, the first wire bending convex portion 25 has a substantially semi-spherical protrusion shape toward the upper surface of the bump 21, and the second wire bending convex portion 27 is at the first bond point. A certain lead 4 side has a partially spherical projection shape toward the upper surface of the bump 21, and the opposite side is an inclined surface of the inclined wedge 22.

  Each wire cutting surface 19, 29 has an arcuate cross section. The wire cutting surface 29 of the wire 12 at the time of bump formation may be between the wire cutting surface 19 of the wire 12 at the time of wire bonding and the first wire bending convex portion 25, or below the wire cutting surface 19. Therefore, it may be between the wire cut surface 19 and the second bump 21b.

  Before describing the operation of forming the bumps 21, the configuration of the capillary 16 will be described. As shown in FIG. 4, the capillary 16 has an inner chamfer part 31, a face part 33, an outer radius part 35, and a straight hole 37, and is made of a hard material such as ceramics. The face portion 33 is provided on the front end surface of the capillary 16 and is a flat surface having a minute angle with respect to the pad 3. Crimp toward the pad 3. The straight hole 37 is a through-hole having a slightly larger inner diameter than the outer diameter of the wire 12 provided in the center of the capillary 16, and the wire 12 is inserted therethrough. The inner chamfer part 31 is a tapered hole provided between the straight hole 37 and the face part 33 and extends toward the face part 33. The inner chamfer portion 31 presses the ball 5 toward the pad 3 in bonding and compresses the ball in the diameter direction to form the press-bonded ball 6. The inner chamfer 31 has a corner 32 between the face 33 and the inner chamfer 31. Since the face portion 33 has a minute angle with respect to the pad 3, when the face portion 33 of the capillary 16 is pressed against the wire 12, the corner portion 32 between the inner chamfer portion 31 and the face portion 33 is a wire. 12 is configured to bite in.

With reference to FIG. 4, the process of forming the bump 21 on the pad 3 of the semiconductor chip 2 of the semiconductor device 14 of the reference example will be described. The bump 21 is formed by moving the capillary 16 which is a bonding tool through which the wire 12 is inserted, up and down and left and right by a wire bonding apparatus (not shown).

  As shown in FIG. 4A, the capillary 16 presses the ball formed at the tip of the wire 12 against the pad 3 to form the press-bonded ball 6, and then rises and is opposite to the lead 4 as the first bond point. It moves toward the right direction in the figure. When the capillary 16 moves in the lateral direction, the wire 12 is joined to the pad 3 by the press-bonded ball 6, so that the inner chamfer portion 31 of the capillary 16 hits the outer surface of the wire 12, and the wire 12 moves in the lateral movement direction of the capillary 16. Bending towards and causing deformation. The capillary 16 moves laterally to a position where the lead 4 side face portion 33 is centered on the press-bonded ball 6 so that the wire 12 is inserted between the face portion 33 and the press-bonded ball 6.

  As shown in FIG. 4B, the capillary 16 moves downward, and the lead 12 side face portion 33 causes the wire 12 between the face portion 33 on the lead 4 side and the press-bonded ball 6 to be placed on the surface of the pad 3. Press toward it. The wire 12 is pressed against the press-bonded ball 6 to form a flat shape and becomes a bump wire 21a '. A first bump 21a is formed by the press-bonded ball 6 and the bump wire 21a 'formed in a flat shape. Further, the wire 12 inserted into the capillary 16 and the first step bump 21 a are continuous on the opposite side of the lead 4 of the bump 21, and the continuous portion of the wire 12 is pressed downward by the inner chamfer portion 31 of the capillary 16. Therefore, the wire 12 is formed along the tapered shape of the inner chamfer portion 31. Thus, the wire 12 is shaped to be guided in the straight hole 37 while being inclined upward toward the opposite side of the lead 4 by the clearance between the straight hole 37 of the capillary 16 and the wire 12.

  As shown in FIG. 4C, the capillary 16 moves up after forming the first step bump 21a, and moves toward the lead 4 in the direction opposite to the previous lateral operation. The inner chamfer 31 of the capillary 16 hits the outer surface of the wire 12 by the lateral movement of the capillary 16. In the state where the first step bump 21a is formed, the wire 12 is inclined toward the side opposite to the lead 4, and therefore the wire 12 between the face portion 33 and the first step bump 21a is connected to the capillary 16. By lateral movement, the lead wire 4 is bent from the opposite side of the lead 4 toward the lead 4 side, and the first wire bending convex portion 25 is formed. The capillary 16 moves laterally toward the lead 4 until the face portion 33 on the opposite side of the lead 4 comes to the approximate center position of the first step bump 21a.

  As shown in FIG. 4D, after the capillary 16 moves laterally, the capillary 16 moves downward and enters between the face portion 33 and the first step bump 21a by the face portion 33 on the opposite side of the lead 4. The wire 12 is pressed toward the pad 3. The wire 12 is pressed against the first step bump 21a to form a flat shape, and the wire 12 is pressed against the first step bump 21a to form a second step bump 21b. Since the first wire bending convex part 25 is displaced from the face part 33 of the capillary 16, it is not pressed in the direction of the pad 3 by the downward movement of the capillary 16, and upward on the opposite side of the lead 4 of the second step bump 21 b. Convex semi-spherical shape. Further, the first wire bending convex portion 25 is bent approximately 180 degrees by the formation of the second step bump 21b by the downward movement of the capillary 16. For this reason, the 1st wire bending convex part 25 becomes higher hardness than another part by the work hardening by bending. Further, the wire 12 inserted into the capillary 16 and the second bump 21 b are continuous on the lead 4 side of the bump 21, and the continuous portion of the wire 12 is pressed downward by the inner chamfer portion 31 of the capillary 16. Accordingly, the wire 12 is formed along the tapered shape of the inner chamfer portion 31. As a result, the wire 12 is shaped to be guided toward the straight hole 37 while being inclined upward toward the lead 4 by the clearance between the straight hole 37 of the capillary 16 and the wire 12.

  As shown in FIG. 4E, after the formation of the second bump 21b and the first wire bending convex portion 25, the capillary is raised and moved toward the opposite side of the lead 4 in the direction opposite to the previous lateral movement. To do. The inner chamfer 31 of the capillary 16 hits the outer surface of the wire 12 by the lateral movement of the capillary 16. Since the wire 12 is inclined toward the lead 4 side in the state where the second step bump 21b is formed, the wire 12 between the face portion 33 and the second step bump 21b moves laterally of the capillary 16. Thus, the second wire bending convex portion 27 is formed by bending from the lead 4 side toward the opposite side of the lead 4. Then, the capillary 16 moves to a position where the center position of the straight hole 37 is substantially the center position of the first bent convex portion 25. When the center of the capillary 16 moves to the center position of the straight hole 37, the second wire bending convex part 27 is detached from the face part 33 of the capillary 16, and a part thereof is closer to the lead 4 than the outer radius part 35.

  As shown in FIG. 4 (f), after the capillary 16 moves laterally, the capillary 16 moves downward so that the first semi-spherical first wire bending projection 25 enters the straight hole 37, The wire 12 interposed between the face portion 33 and the second step bump 21 b is pressed toward the pad 3 by the face portion 33. The wire 12 is pressed against the second step bump 21b to form a flat shape, and is crimped to the second step bump 21b to form a third step bump 21c. The wire 12 inserted through the capillary 16 and the third bump 21 c are continuous on the opposite side of the lead 4 of the bump 21, and the continuous portion of this wire 12 is the first wire on the pad 3 side by the inner chamfer portion 31 of the capillary 16. It is pressed against the bent convex part 25. Since the first wire bending convex part 25 is harder than the other part by the work hardening of the bending process in the previous step, it is sandwiched between the inner chamfer part 31 of the capillary 16 made of a hard material. The wire 12 can be compressed and deformed. For this reason, the inner chamfer part 31 compresses the wire 12 sandwiched between the first wire bending convex part 25 by the downward movement of the capillary 16, and the corner part 32 of the inner chamfer part 31 bites into the wire 12. The wire crushing portion 30 having an arcuate cross section in which the cross-sectional area of the joint portion is smaller than the cross-sectional area of the wire 12 is formed.

  As shown in FIG. 5C, the wire 12 is compression-molded by being sandwiched between a circular tapered inner chamfer portion 31 and a substantially semi-spherical first wire bending convex portion 25, and the first wire bending convex portion 25. An arcuate wire crushing portion 30 is formed along the outer surface. The wire crushing portion 30 is located on the lead 4 side of the first wire bending convex portion 25. As shown in FIG. 5A, the wire 12 after being formed is inclined toward the opposite side of the lead 4 by the clearance between the straight hole 37 of the capillary 16 and the wire 12, and becomes the straight hole 37. The shape is such that it is guided and extends upward.

  Since the second wire folding projection 27 is displaced from the face portion 33 of the capillary 16 due to the movement of the capillary 16, the third step bump is not pressed against the second step bump 21b by the downward movement of the capillary 16. It becomes a partially spherical convex shape that is higher than the portion pressed by the face portion 33 on the lead 4 side of 21c. Further, since the second wire bending convex portion 27 is bent approximately 180 degrees by the formation of the third step bump 21c by the downward movement of the capillary 16, the second wire bending convex portion 27 is harder than other portions by work hardening by bending. Becomes higher. Between the second wire bending convex portion 27 having a convex shape and the portion where the corner portion 32 of the inner chamfer portion 31 is pressed against the wire, the height decreases from the lead 4 side toward the opposite side of the lead 4. An inclined wedge 22 that is an inclined surface is formed. The shape of the surface of the inclined wedge 22 is a shape substantially along the face portion 33 and the outer radius portion 35.

  As shown in FIG. 4G, when the formation of the third step bump 21c is completed, the capillary 16 is raised. At this time, since the clamper (not shown) is in an open state, the tail wire 18 is extended under the capillary 16 by raising the capillary 16.

  As shown in FIG. 4 (h), when the capillary 16 is raised until the length of the tail wire 18 reaches a length necessary for forming the next ball, a clamper (not shown) is closed and the wire 12 is gripped. As the capillary 16 rises, it rises. Then, the wire 12 is pulled upward by the clamper, and tension is applied to the wire 12. In the formation of the third step bump, the wire crushing portion 30 having a cross-sectional area smaller than the cross-sectional area of the wire 12 is formed, so that the wire crushing portion 30 has a tension applied to the wire 12. A large tensile stress is generated. Then, due to the tensile stress, the wire 12 is cut at the wire crushing portion 30 to form the wire cut surface 29. Since the area of the wire crushing portion 30 is formed to be small, the pulling force applied to the entire wire 12 is small when the wire 12 is cut, and the tension is repelled when the wire 12 is cut. Therefore, the occurrence of bending in the wire 12 can be reduced. When the wire 12 is cut, the step of forming the bumps 21 that are multi-stage bent and laminated including the first wire bending convex portion 25 and the inclined wedge 22 is completed.

A process of bonding the wire 12 on the bump 21 formed on the pad 3 of the semiconductor chip 2 of the semiconductor device 14 of the reference example will be described with reference to FIG.

  As shown in FIG. 6A, after the first bonding to the lead 4 as the first bonding point, the wire is looped, and the center of the straight hole 37 of the capillary 16 through which the wire 12 is inserted is opposite to the lead 4. The capillary 16 is moved so as to be approximately at the center of the first wire bending convex portion 25 formed on the side. And if the center position of the capillary 16 comes to the approximate center of the 1st wire bending convex part 25, the capillary 16 will be moved down.

  As shown in FIG. 6B, the capillary 16 moves downward so that the substantially semicircular first wire bending convex portion 25 enters the straight hole 37, and the face portion 33 is formed by the face portion 33 on the lead 4 side. And the wire 12 between the inclined wedge 22 and the inclined wedge 22 are pressed against the inclined wedge 22. On the lead 4 side of the bump 21 to which the wire 12 is looped, the hardened second wire bending convex portion 27 protrudes upward, so that the wire 12 pushed down by the face portion 33 of the capillary 16 is pressed. The lead 4 side is supported by the second wire bending projection 27. When the capillary 16 is further moved downward, the wire 12 between the face portion 33 and the inclined wedge 22 is deformed into a shape along the inclined wedge 22. When the capillary 16 is further moved downward, the upper surface of the wire 12 becomes a shape that conforms to the shape of the face portion 33 and the outer radius portion 35 of the capillary 16, and the lower surface of the wire 12 is pressed against the surface of the inclined wedge 22. The bottom surface of the wire 12 is bonded to the bump 21. Since the surface of the inclined wedge 22 and the wire 12 have a large bonding area, the bonding property between the wire 12 and the bump 21 is improved.

  Since the wire 12 extending toward the lead 4 is supported by the hardened second wire bending convex portion 27, even if the face portion 33 and the outer radius portion 35 of the capillary 16 push down the wire 12, Since the wire 12 is not deformed downward, it is possible to prevent the wire 12 from contacting the lead 4 or the semiconductor chip 2.

  The wire 12 inserted into the capillary 16 and the upper surface of the inclined wedge 22 are continuous on the opposite side of the lead 4 of the bump 21, and the continuous portion of the wire 12 is a first wire bending protrusion that is cured by the inner chamfer portion 31 of the capillary 16. The wire crushing portion 20 is formed in which the cross-sectional area of the bonded portion of the wire 12 is compressed by being pressed against the portion 25 and is smaller than the cross-sectional area of the wire 12. The shape and cross section of the wire crushing portion 20 is an arcuate shape along the outer surface of the first wire bending convex portion 25 as in the wire crushing portion 30 described above with reference to FIG. It is located on the lead 4 side of the portion 25.

  When the bonding of the wire 12 to the bump 21 is completed, the capillary 16 is raised as shown in FIG. At this time, since the clamper (not shown) is in an open state, the tail wire 18 is extended under the capillary 16 by raising the capillary 16.

  As shown in FIG. 6 (d), when the capillary 16 is raised until the length of the tail wire 18 reaches a length necessary for forming the next ball, a clamper (not shown) is closed and the wire 12 is gripped. Then, the capillary 16 rises with the rise. Then, the wire 12 is pulled upward by the clamper, tension is applied to the wire 12, and the wire 12 is cut at the wire crushing portion 20 where the cross-sectional area is smaller than the cross-sectional area of the wire 12. Since the area of the wire crushing portion 20 is formed to be small, it is possible to reduce the occurrence of bending in the wire 12 due to the repulsion of the tension when the wire 12 is cut. When the wire 12 is cut, an arcuate wire cutting surface 19 is formed along the side surface of the first wire bending projection 25 on the lead 4 side. When the wire 12 is cut, the bonding process ends.

In the semiconductor device 14 of the reference example described above, since the wire 12 is bonded to the surface of the inclined wedge 22 having a large bonding area, the bonding property between the wire 12 and the bump 21 is improved. Further, when the bump 21 is formed and when the wire 12 is bonded to the bump 21, the wire 12 is sandwiched between the hardened first wire bending convex portion 25 and the inner chamfer portion 31, and the cross-sectional area thereof is the wire 12. The wire crushing portions 20 and 30 that are smaller than the cross-sectional area of the wire 12 are formed, and the wire 12 is cut by the wire crushing portions 20 and 30. It is possible to reduce the occurrence of. Further, when the wire 12 is bonded to the bump 21, the wire 12 is supported by the hardened second wire bending convex portion 27, so that it is not deformed downward toward the pad 3 surface side by bonding, and the wire 12 It is possible to prevent the contact with the lead 4 or the semiconductor chip 2. As described above, in this reference example , the bonding property between the wire 12 and the bump 21 can be improved, and the cutting property of the wire 12 can be improved to improve the bonding quality.

In the above reference example , the bump 21 is formed on the pad 3 of the semiconductor chip 2 at the second bond point that is higher than the lead 4 of the lead frame 15 at the first bond point. It may be formed at a position higher or lower than one bond point, and may be formed not only on the pad 3 but also on the lead 4 of the lead frame 15.

Hereinafter, another reference example of the present invention will be described with reference to the drawings. Parts similar to those of the reference example described above are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 7, the bump 21 formed on the lead 4 includes, in order from the surface of the lead 4, a first-stage bump 21 a configured by the press-bonded ball 6 and a bump wire 21 a ′ pressed thereon. A first wire bending convex portion 25 formed in a direction opposite to the pad 3, a second step bump 21b formed by pressing the wire 12 from above the first step bump, an inclined wedge 22 on the upper surface of the bump, a wire When the bumps 21 are formed by bending the wire 12, the wire 12 is cut, and the wire 12 is bent and laminated. The wire 12 is subjected to primary bonding on the pad 3 that is the first bond point to form the press-bonded ball 6, and then looped toward the bump 21 to form the bump 4 formed on the lead 4 that is the second bond point. A wire cutting surface 19 is provided on the side of the first wire bending convex portion 25 which is bonded to the inclined wedge 22 on the upper surface of the bump 21 and formed in the direction opposite to the pad 3 of the bump 21.

A process of forming the bumps 21 on the leads 4 of the lead frame 15 of the semiconductor device 14 of the reference example will be described with reference to FIG. The bump 21 formation process from FIG. 8A to FIG. 8D is the same as the bump 21 formation process of FIG. 4A to FIG. 4D described in the previous reference example . ) To (d) in which the pad 3 is replaced with the lead 4 and the lead 4 is replaced with the pad 3. The first bond point is the pad 3 of the semiconductor chip 2 and the second bond point is the lead 4 of the lead frame 15. is there. The first step bump 21a, the second step bump 21b, and the first wire bending convex portion 25 are formed by the steps of FIG. 8A to FIG. 8D. An inclined wedge 22 having an inclined surface is formed by pressing the face portion 33 of the capillary 16 when forming the second bump 21b. The inclined wedge 22 has an inclined surface that becomes lower toward the pad 3 side from the first wire bending convex portion 25 on the opposite side to the pad 3 that is the first bond point. Further, the wire 12 inserted into the capillary 16 and the second step bump 21 b are continuous on the pad 3 side of the bump 21, and the continuous portion of the wire 12 has a cross-sectional area smaller than the cross-sectional area of the wire 12. A portion 34 is formed.

  As shown in FIG. 8 (e), when the formation of the second bumps 21b is completed, the capillary 16 moves up with a clamper (not shown) opened. When the capillary 16 is raised, the tail wire 18 is extended to the lower side of the capillary 16.

  As shown in FIG. 8 (f), after the capillary 16 is raised until the length of the tail wire 18 reaches a predetermined length, the clamper is closed and the wire 12 is gripped to rise together with the capillary 16. Then, when the second step bump 21b is formed, a large stress is applied to the wire crushing portion 34 formed by the tip of the capillary 16 so that the cross-sectional area becomes smaller than the cross-sectional area of the wire 12, and the wire 12 is cut. The When the wire 12 is cut, a wire cut surface 28 is formed. The wire cutting surface 28 is slightly convex upward from the upper surface of the inclined wedge 22.

With reference to FIG. 9, the bonding of the wire 12 to the bump 21 in the reference example will be described. Parts similar to those in FIG. 2 described above are denoted by the same reference numerals, and description thereof is omitted. The bump 21 of the reference example has a wire cut surface 28 formed on the pad 3 side where the wire 12 is looped. The wire cutting surface 28 is not cured because the wire 12 is not bent. Therefore, the force for supporting the wire 12 is lower than that of the previous reference example . However, as shown in FIG. 7, in this reference example , the bump 21 is formed on the lead 4 located at a position lower than the pad 3 of the semiconductor chip 2, and therefore looped as shown in FIG. The pad 3 side which is the first bond point side of the wire 12 is pulled upward. For this reason, the wire 12 can be supported by the uncured wire cut surface 28, and the wire 12 is not deformed downward and does not contact the lead 4. The contact area between the inclined wedge 22 that joins the wire 12 and the wire 12 is large, and the center position of the straight hole 37 of the capillary 16 is bonded to the center position of the hardened first wire bending convex portion 25 to bond the wire 12. The wire crushing portion 20 having a cross-sectional area smaller than the cross-sectional area is formed, and the wire 12 is cut by the wire crushing portion 20 as in the above-described reference example .

The semiconductor device 14 of the reference example described above can improve the bonding quality between the wire 12 and the bump 21 as well as the cutting ability of the wire 12 and improve the bonding quality as in the previous reference example. There is an effect that can be done. Furthermore, since the number of laminations of the bumps 21 is only two in the first and second stages, the present reference example has the effect that the bump formation can be performed in a short time and the bonding time can be shortened. Play.

In the reference example described above, the bump 21 is formed on the lead 4 that is the second bond point at a position lower than the first bond point. However, the second position at a position lower than the first bond point is described. As long as the bump 21 is formed at the bond point, the bump 21 may be formed not only on the lead 4 but also on the pad 3 of the semiconductor chip 2.

Hereinafter, with reference to the accompanying drawings, a description will be given implementation of the invention. Parts similar to those of the reference example described above with reference to FIGS. 2 to 6 are denoted by the same reference numerals, and description thereof is omitted. The present embodiment relates to a wire bonding method using a capillary 16 having a narrower tip than the reference example described above and a semiconductor device manufactured by the method. In order to cope with the fine pitch of semiconductor devices in recent years, a capillary 16 having a thin tip is often used. However, if the tip of the capillary 16 becomes thin, the reference described with reference to FIGS. In an example , the 2nd wire bending convex part 27 may be formed in the independent hemisphere, and a looping wire may not be supported. In the present embodiment, even when wire bonding is performed using the capillary 16 having a narrow tip, it is possible to effectively support the looping wire and improve the bonding property between the wire 12 and the bump 21.

  As shown in FIG. 10, the bump 21 formed on the pad 3 includes, in order from the surface of the pad 3, the first-stage bump 21 a configured by the press-bonded ball 6 and the bump wire 21 a ′ pressed thereon, 4, the first wire bending convex portion 25 formed in the opposite direction to the wire 4, the second step bump 21 b formed by pressing the wire 12 from above the first step bump, and the second step formed on the lead 4 side. A wire bending convex portion 27, an inclined wedge 22 on the upper surface of the bump, and a wire cutting surface 29 which is a tensile cutting surface obtained by pulling the wire 12 in the longitudinal direction when the wire 12 is bent to form the bump 21; The wire 12 is bent and laminated. The wire 12 is subjected to primary bonding on the lead 4 that is the first bond point to form the press-bonded ball 6, and then looped toward the bump 21 to form the bump formed on the pad 3 that is the second bond point. 21 is joined to an inclined wedge 22 on the upper surface of 21. On the side of the first wire bending convex portion 25 formed in the direction opposite to the lead 4 of the bump 21, a wire shear cutting surface 43, which is a shear cutting surface obtained by cutting a part of the wire 12 by a radial shear force, The wire cutting surface 19 which is a tensile cut surface obtained by pulling the wire 12 in the longitudinal direction and cutting the wire 12 is provided. The wire shear cut surface 43 is a surface substantially parallel to the surface including the pad 3 of the semiconductor device 14.

  The center of the upper surface of the bump 21 is a concave portion, and the first and second wire bending convex portions 25 and 27 on both sides along the connecting direction of the wire 12 are convex upward. The inclined wedge 22 is an inclined surface formed from the central concave portion toward the second wire bending convex portion 27 on the lead 4 side which is the first bond point. As described above, the inclination of the inclined wedge 22 is high on the side of the lead 4 that is the first bond point, and is low along the direction from the first bond point toward the pad 3 side of the second bond point. It has a slope like this. The wire 12 is bonded along the surface of the inclined wedge 22.

  A wire cutting surface 29 for bump formation and a wire cutting surface 19 for wire bonding are located along the first wire bending projection 25. Further, a wire shear cutting surface 43 is located adjacent to the wire cutting surface 19.

  As shown in FIG. 11, the first wire bending convex portion 25 of the bump 21 projects in a direction opposite to the lead 4 that is the first bond point, and the second wire bending convex portion 27 is the direction of the lead 4 that is the first bond point. Overhangs. The first wire bending convex part 25 has a substantially semi-spherical protrusion shape toward the upper surface of the bump 21, and the second wire bending convex part 27 has the lead 4 side that is the first bond point toward the upper surface of the bump 21. It is a partial spherical projection shape, and the opposite side is the inclined surface of the inclined wedge 22.

  Each wire cutting surface 19, 29 has an arcuate cross section. The wire cutting surface 29 of the wire 12 at the time of bump formation may be between the wire cutting surface 19 of the wire 12 at the time of wire bonding and the first wire bending convex portion 25, or below the wire cutting surface 19. Therefore, it may be between the wire cut surface 19 and the second bump 21b. Further, since the wire shear cut surface 43 is a surface obtained by shearing a part of the wire 12 in the radial direction from the lead 4 side toward the pad 3, the wire cut surface has a crescent shape curved toward the lead 4 side. 19 is connected.

With reference to FIG. 12, a process of forming the bump 21 on the pad 3 of the semiconductor device 14 of the present embodiment will be described. By the same process as the bump 21 forming process of FIGS. 4A to 4B described in the previous reference example , the press-bonded ball 6 and the bump wire 21a ′ formed into a flat shape by being pressed against the press-bonded ball 6 Is formed. The first bump 21a is formed by the crimp ball 6 and the bump wire 21a ′, and is crimped to the first wire bending convex portion 25 and the first bump 21a by the same process as in FIGS. 4C and 4D. A second step bump 21b is formed.

  As shown in FIG. 12A, after the formation of the second bump 21 b and the first wire bending convex portion 25, the capillary rises and moves toward the opposite side of the lead 4. By the lateral movement of the capillary 16, the wire 12 is bent from the lead 4 side toward the opposite side of the lead 4, and a second wire bending convex portion 27 is formed. Then, the end surface of the outer radius part 35 on the lead 4 side of the capillary 16 moves to a position where it is substantially the center position of the second wire bending convex part 27. At this position, the center position of the straight hole 37 of the capillary 16 is shifted to the lead 4 side from the center position of the first wire bending projection 25.

  As shown in FIG. 12B, after the capillary 16 is moved laterally, the capillary 16 enters between the face portion 33 and the second step bump 21b by the outer radius portion 35 on the lead 4 side and the subsequent face portion 33. The wire 12 is pressed toward the pad 3. The wire 12 is pressed against the second step bump 21b to form a flat shape, and is crimped to the second step bump 21b to form a third step bump 21c. Since the end surface of the outer radius portion 35 on the lead 4 side of the capillary 16 moves down substantially at the center position of the second wire bending convex portion 27, the end surface of the outer radius portion 35 and the face portion 33 following the end surface are arranged on the second wire bending convex portion. A half convex portion on the opposite side of the lead 4 from the center of 27 is pressed toward the pad 3. As a result, the opposite side portion of the lead 4 of the second wire bending convex portion 27 is formed into a shape along the end surface of the outer radius portion 35 and the face portion 33 subsequent thereto, and the lead is formed from the substantially central position of the second wire bending convex portion 27. A curved surface that curves toward the opposite side of 4 and a flat surface that slopes downward toward the opposite side of the lead 4 are formed following the curved surface. The curved surface and the flat surface become the inclined wedge 22. Further, since the half of the lead 4 side from the center of the second wire bending convex portion 27 is not pressed toward the pad 3 by the outer radius portion 35 and the face portion 33, it becomes a partial spherical shape. Since the second wire bending convex part 27 is bent by about 180 degrees by the formation of the third step bump 21c by the downward movement of the capillary 16, the second wire bending convex part 27 has higher hardness than other parts by work hardening by bending. Become. In this way, the end face of the outer radius part 35 of the capillary 16 and the face part 33 that follows from the end face press the half convex part on the side opposite to the lead 4 from the center of the second wire bending convex part 27 toward the pad 3. Even when the tip of the capillary 16 is thin, the second wire bending convex portion 27 does not become an independent hemispherical convex portion, but can be formed into a partial spherical shape on the lead 4 side and an inclined wedge 22 subsequent thereto.

  As shown in FIG. 12C, when the third step bump 21 c, the second wire bending convex portion 27, and the inclined wedge 22 are formed by the downward movement of the capillary 16, the capillary 16 is moved from the upper surface of the inclined wedge 22. The tip height rises to a position lower than the upper end height of the first wire bending convex portion 25.

  As shown in FIG. 12 (d), the capillary 16 moves upward and then laterally moves in parallel with the pad 3 toward the opposite side of the lead 4. The continuous portion of the wire 12 inserted through the capillary 16 and the third bump 21 c is pressed against the side surface of the lead 4 of the first wire bending convex portion 25 by the straight hole 37 and the inner chamfer portion 31 of the capillary 16. Since the first wire bending convex part 25 is harder than the other part by the work hardening of the bending process in the previous step, the gap between the straight hole 37 of the capillary 16 made of a hard material and the inner chamfer part 31 is made. The wire 12 sandwiched between the two can be deformed. When the capillary 16 is further moved laterally toward the opposite side of the lead 4, the corner portion 32 of the inner chamfer portion 31 of the capillary 16 bites into the wire 12, and the wire 12 is radially moved by the edge of the corner portion 32. The shear cutting starts, and a plate-like wire shear cutting surface 41 whose upper surface is substantially horizontal is formed by the shear cutting. At the same time, the inner chamfer portion 31 compresses the wire 12 sandwiched between the first wire bending convex portion 25 and has an arcuate cross section in which the cross-sectional area of the continuous portion of the wire 12 is smaller than the cross-sectional area of the wire 12. The wire crushing part 30 is formed.

  As shown in FIG. 13C, the wire 12 is compression-molded by being sandwiched between a circular taper-shaped inner chamfer portion 31 and a first semi-spherical first wire bending convex portion 25, and the first wire bending convex portion 25. An arcuate wire crushing portion 30 is formed along the outer surface. The wire crushing portion 30 is located on the lead 4 side of the first wire bending convex portion 25. A wire shear cut surface 41 formed by shear cutting a part of the wire 12 in the radial direction is located on the lead 4 side of the wire crushing portion 30. The wire shear cut surface 41 has a crescent-shaped planar shape that protrudes toward the lead 4, and the upper surface thereof is substantially parallel to the pad 3 and has a plateau shape rising from the inclined wedge 22. Then, as shown in FIG. 13A, the wire 12 after being formed is inclined toward the opposite side of the lead 4 by an amount corresponding to the clearance between the straight hole 37 of the capillary 16 and the wire 12 and becomes the straight hole 37. The shape is such that it is guided and extends upward.

  As shown in FIG. 12 (e), the capillary 16 ascends when the partial shear cutting of the wire 12 and the formation of the wire crushing portion 30 are completed. At this time, since the clamper (not shown) is in an open state, the tail wire 18 is extended under the capillary 16 by raising the capillary 16.

  As shown in FIG. 12 (f), when the capillary 16 is raised until the length of the tail wire 18 reaches a length necessary for forming the next ball, a clamper (not shown) is closed and the wire 12 is gripped. Then, the capillary 16 rises with the rise. Then, the wire 12 is pulled upward by the clamper, and tension is applied to the wire 12. Since the cross-sectional area of the wire crushing portion 30 is smaller than the cross-sectional area of the wire 12, a large tensile stress is generated in the wire crushing portion 30 due to the tension applied to the wire 12. Then, by this tensile stress, the wire 12 is pulled and cut at the wire crushing portion 30 to form the wire cut surface 29. Since the area of the wire crushing portion 30 is formed to be small, the tensile force applied to the entire wire 12 when the wire 12 is pulled and cut is small, and when the wire 12 is pulled and cut, the tensile force is reduced. The occurrence of bending in the wire 12 due to the repulsion of force can be reduced. When the wire 12 is pulled and cut, the step of forming the multi-stage bent bump 21 including the first wire bending convex portion 25 and the inclined wedge 22 is completed.

  With reference to FIG. 14, a process of bonding the wire 12 onto the bump 21 formed on the pad 3 of the semiconductor chip 2 of the semiconductor device 14 of the present embodiment will be described.

  As shown in FIG. 14A, after the first bonding to the lead 4 as the first bonding point, the wire is looped, and the end surface of the outer radius portion 35 on the lead 4 side of the capillary 16 through which the wire 12 is inserted is bumped. 21. The capillary 16 is moved laterally so as to be positioned at the end of the inclined wedge 22 formed on the upper surface of the inclined wedge 22, and the bonding process is started. When the end surface of the outer radius portion 35 on the lead 4 side of the capillary 16 comes to the position of the lead side end portion of the inclined wedge 22 formed on the upper surface of the pump, the capillary 16 is moved downward.

  As shown in FIG. 14B, the capillary 16 moves downward so that the end surface of the outer radius 35 on the lead 4 side and the face portion 33 that follows the end face are along the surface of the inclined wedge 22, and the face portion 33 on the lead 4 side. Thus, the wire 12 placed between the face portion 33 and the inclined wedge 22 is pressed toward the inclined wedge 22. The second wire bending projection 27 is formed in a partial spherical shape on the lead 4 side of the bump 21 to which the wire 12 is looped, and is hardened by the bending process, so that it is pushed downward by the face portion 33 of the capillary 16. The lead 4 side of the formed wire 12 is supported by the second wire bending projection 27. When the capillary 16 is further moved downward, the wire 12 between the face portion 33 and the inclined wedge 22 is deformed into a shape along the inclined wedge 22. When the capillary 16 is further moved downward, the upper surface of the wire 12 becomes a shape that conforms to the shape of the face portion 33 and the outer radius portion 35 of the capillary 16, and the lower surface of the wire 12 is pressed against the surface of the inclined wedge 22. The bottom surface of the wire 12 is bonded to the bump 21. At this time, the wire 12 is also pressed onto the plate-shaped wire shear cutting surface 41 formed when the bumps 21 are formed, and the wire shear cutting surface 41 is crushed and joined to the wire 12. Since the surface of the inclined wedge 22, the wire shear cut surface 41, and the wire 12 have a wide bonding area, the bonding property between the wire 12 and the bump 21 is improved.

  Since the wire 12 extending toward the lead 4 is supported by the hardened second wire bending convex portion 27, even if the face portion 33 and the outer radius portion 35 of the capillary 16 push down the wire 12, Since the wire 12 is not deformed downward, it is possible to prevent the wire 12 from contacting the lead 4 or the semiconductor chip 2.

  As shown in FIG. 14C, when the bonding of the wire 12 to the bump 21 is finished by the downward movement of the capillary 16, the bonding process is finished, and the wire crushing part forming process is started. The capillary 16 rises from the upper surface of the inclined wedge 22 to a position where the tip height is lower than the upper end height of the first wire bending projection 25.

  As shown in FIG. 14 (d), the capillary 16 moves upward and then laterally moves in parallel with the pad 3 toward the opposite side of the lead 4. Similar to the formation of the bump 21 described above with reference to FIG. 12, when the capillary 16 is moved laterally toward the opposite side of the lead 4, the corner portion 32 of the inner chamfer portion 31 of the capillary 16 becomes the wire 12. The wire 12 is cut in the radial direction by the edge of the corner portion 32, and a plate-like wire shear cutting surface 43 having a substantially horizontal upper surface is formed by the shear cutting. At the same time, the inner chamfer portion 31 compresses the wire 12 sandwiched between the first wire bending convex portion 25 and has an arcuate cross section in which the cross-sectional area of the continuous portion of the wire 12 is smaller than the cross-sectional area of the wire 12. The wire crushing portion 20 is formed. When the wire crushing portion 20 is formed, the wire crushing portion forming step is finished.

  As shown in FIGS. 13B and 13C, the shape and cross section of the wire crushing portion 20 are the same as those of the wire crushing portion 30 described above with reference to FIG. It has an arcuate shape along the outer surface and is located on the lead 4 side of the first wire bending convex portion 25. Also, the wire shear cutting surface 43 is a crescent-shaped planar shape located on the lead 4 side of the wire crushing portion 20 and convex on the lead 4 side, like the wire shear cutting surface 41 described above. The upper surface is substantially parallel to the pad 3 and has a plateau shape rising from the inclined wedge 22.

  As shown in FIG. 14E, when the partial shear cutting of the wire 12 and the formation of the wire crushing portion 20 are completed, the capillary 16 is raised and the wire cutting process is started. At this time, since the clamper (not shown) is in an open state, the tail wire 18 is extended under the capillary 16 by raising the capillary 16.

  As shown in FIG. 14 (f), when the capillary 16 is raised until the length of the tail wire 18 reaches a length necessary for forming the next ball, a clamper (not shown) is closed and the wire 12 is gripped. Then, the capillary 16 rises with the rise. Then, the wire 12 is pulled upward by the clamper, and tension is applied to the wire 12. Since the cross-sectional area of the wire crushing portion 20 is smaller than the cross-sectional area of the wire 12, a large tensile stress is generated in the wire crushing portion 20 due to the tension applied to the wire 12. Then, by this tensile stress, the wire 12 is pulled and cut at the wire crushing portion 20 to form the wire cut surface 19. Since the area of the wire crushing portion 20 is formed to be small, the pulling force applied to the entire wire 12 when the wire 12 is pulled and cut is small, and when the wire 12 is pulled and cut, the tensile force is reduced. The occurrence of bending in the wire 12 due to the repulsion of force can be reduced. When the wire 12 is pulled and cut, an arcuate wire cutting surface 19 is formed along the side surface of the first wire bending projection 25 on the lead 4 side. When the wire 12 is cut, the wire cutting process is finished and the wire bonding is finished.

The semiconductor device 14 of the present embodiment described above improves the bonding quality between the wire 12 and the bump 21 and improves the cutting property of the wire 12 as well as the previous reference example. There is an effect that can be. Furthermore, this embodiment can effectively support the looping wire and improve the bondability between the wire 12 and the bump 21 even when bump formation or wire bonding is performed by the capillary 16 having a narrow tip. There is an effect.

  In the above-described embodiment, the bump 21 is formed on the pad 3 of the semiconductor chip 2 at the second bond point that is higher than the lead 4 of the lead frame 15 at the first bond point. It may be formed at a position higher or lower than one bond point, and may be formed not only on the pad 3 but also on the lead 4 of the lead frame 15.

It is a top view of the semiconductor device in the reference example of this invention. It is a side view which shows the connection wire and bump between the lead frame and semiconductor chip of a semiconductor device in the reference example of this invention. It is a bump top view formed on the semiconductor chip of the semiconductor device in the reference example of the present invention. It is explanatory drawing which shows the process of forming bump on the semiconductor chip of the semiconductor device in the reference example of this invention. It is sectional drawing which shows the cutting part of the wire in the bump upper surface of the semiconductor device in the reference example of this invention. It is explanatory drawing which shows the process of joining a wire to the bump on the semiconductor chip of the semiconductor device in the reference example of this invention. It is a side view which shows the connection wire and bump between the lead frame and semiconductor chip of a semiconductor device in the reference example of this invention. It is explanatory drawing which shows the process of forming bump on the semiconductor chip of the semiconductor device in the reference example of this invention. It is explanatory drawing which shows the process of joining a wire to the bump on the semiconductor chip of the semiconductor device in the reference example of this invention. Is a side view showing the connecting wires and bumps between the lead frame and the semiconductor chip of the semiconductor device in the implementation of the invention. It is a plan view showing a bump and the connecting wires formed on the semiconductor chip of the semiconductor device in the implementation of the invention. Is an explanatory view showing the step of forming a bump on a semiconductor chip of the semiconductor device in the implementation of the invention. It is a sectional view showing a cutting portion of the wire in the bump upper surface of the semiconductor device in the implementation of the invention. Is an explanatory view showing the step of bonding the wire to the bumps on the semiconductor chip of the semiconductor device in the implementation of the invention. It is explanatory drawing which shows the connection process of the wire of the semiconductor device by a prior art. It is explanatory drawing which shows the connection process of the wire of the semiconductor device by a prior art. It is explanatory drawing which shows the cutting | disconnection of the wire of the semiconductor device by a prior art. It is explanatory drawing which shows the bending deformation of the wire of the semiconductor device by a prior art.

2 Semiconductor chip, 3 Pad, 4 Lead, 5 Ball, 6 Crimp ball, 12 Wire, 14 Semiconductor device, 15 Lead frame, 16 Capillary, 17 Clamper, 18 Tail wire, 19 Wire cut surface, 20 Wire crushing part, 21 Bump, 21a ′ Bump wire, 21a First step bump, 21b Second step bump, 21c Third step bump, 22 Inclined wedge, 25 First wire bent convex portion, 27 Second wire bent convex portion, 28 Wire cut surface, 29 Wire cutting plane, 30, 34 Wire crushing section, 31 Inner chamfer section, 32 Corner section, 33 Face section, 35 Outer radius section, 37 Straight hole, 41, 43 Wire shear cutting plane.

Claims (8)

A semiconductor device in which a wire is connected between a first bond point and a second bond point,
A bump formed by bending and laminating a wire on the second bond point, and including a wire bending convex portion on the side opposite to the first bond point;
A wire extending from the first bond point side to the bump and bonded to the upper surface of the bump, the wire bending convex portion side including a shear cut surface and a tensile cut surface having a smaller cross-sectional area than the wire cross-sectional area;
A semiconductor device comprising: A semiconductor device in which a wire is connected between a first bond point and a second bond point,
A bump formed by bending and laminating a wire on the second bond point, and including a wire bending convex portion on the first bond point side and the opposite side of the first bond point;
A wire that extends from the first bond point side to the bump and is bonded to the upper surface of the bump, and includes a shear cut surface and a tensile cut surface having a smaller cross-sectional area than the wire cross-sectional area on the side of the wire bending convex portion opposite to the first bond point When,
A semiconductor device comprising: The semiconductor device according to claim 1 or 2 ,
The bump includes an inclined wedge including an inclined surface on the upper surface on the first bond point side and having a height that decreases along the direction from the first bond point toward the second bond point,
The wire is bonded to the top surface of the bump along an inclined wedge;
A semiconductor device characterized by the above. The semiconductor device according to claim 2 ,
The bump includes an inclined wedge that includes an inclined surface that is provided on the upper surface adjacent to the wire bending convex portion on the first bond point side and has a height that decreases along the direction from the first bond point to the second bond point. ,
The wire is bonded to the top surface of the bump along an inclined wedge;
A semiconductor device characterized by the above. The semiconductor device according to any one of claims 1 to 4 , wherein
A semiconductor device, wherein the shear cut surface is substantially parallel to the surface of the semiconductor device including the second bond point, and the tensile cut surface has an arcuate cross-sectional shape. A wire bonding method for connecting a first bond point and a second bond point of a semiconductor device with a wire,
A bump forming step of bending and laminating the wire on the second bond point, and forming a bump including a wire bending convex portion on the side opposite to the first bond point;
Looping the wire from the first bond point toward the bump, and bonding the wire by pressing the wire against the upper surface of the bump by the face portion at the tip of the capillary;
After raising the capillary from the bump upper surface to a position where the tip height is lower than the upper end height of the wire bending convex portion, the capillary is moved in the direction from the first bond point to the wire bending convex portion, A wire crushing portion forming step of forming a wire crushing portion having a cross-sectional area smaller than the wire cross-sectional area by shearing and cutting a part and pressing the wire against the wire bending convex portion by the inner chamfer portion of the capillary;
A wire cutting step of pulling up the wire and cutting the wire at the wire crushing portion;
A wire bonding method characterized by comprising: A wire bonding method for connecting a first bond point and a second bond point of a semiconductor device with a wire,
Bending and laminating the wire on the second bond point to form a wire bending convex part on the side opposite to the first bond point,
The wire is pressed by the face part at the tip of the capillary to form an inclined wedge on the upper surface on the first bond point side,
After raising the capillary from the upper surface of the inclined wedge to a position where the tip height is lower than the upper end height of the wire bending convex portion, the capillary is moved in a direction from the inclined wedge toward the wire bending convex portion, and one end of the wire is moved by the corner of the capillary. The part is shear cut and the inner chamfer part of the capillary presses the wire against the wire bending convex part to form a wire crushing part having a smaller cross-sectional area than the wire cross-sectional area,
A bump forming step of lifting the wire and cutting the wire at the wire crushing portion;
Looping the wire from the first bond point toward the bump, and bonding the wire by pressing the wire against the upper surface of the inclined wedge by the face portion at the tip of the capillary;
After raising the capillary from the upper surface of the inclined wedge to a position where the tip height is lower than the upper end height of the wire bending convex portion, the capillary is moved in a direction from the inclined wedge toward the wire bending convex portion, and one end of the wire is moved by the corner of the capillary. A wire crushing part forming step of forming a wire crushing part having a cross-sectional area smaller than the wire cross-sectional area by pressing the wire against the wire bending convex part by the inner chamfer part of the capillary while shear cutting the part,
A wire cutting step of pulling up the wire and cutting the wire at the wire crushing portion;
A wire bonding method characterized by comprising: The wire bonding method according to claim 6 or 7 ,
The wire-bonding method, wherein the shear-cut surface is substantially parallel to the surface of the semiconductor device including the second bond point, and the wire crushing portion has an arcuate cross-sectional shape.

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