JP2007214337A - Wire bonding method and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To permit the formation of a bonding wire connecting a long wiring distance with a low loop height, so that the wire will not be contacted with a chip angle upon bonding it by pressure at a second bonding point, and a distance becomes short as much as possible between the chip and the second bonding point. <P>SOLUTION: When a capillary has arrived at the highest point, the capillary is moved so that the bonding wire is provided with bending habit from a first bond point toward the second bond point, and is provided with a camber (D) whose radius of convex curvature is 0.5 mm-3.0 mm, above a part (C) having the bending habit toward the second bond point, while a part positioned above a chip angle after forming a loop is provided with a bending part (E) toward the second bond point with a bending angle of more than 15 degrees. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wire bonding method for connecting a long wiring distance with a low loop height in a semiconductor device, and a semiconductor device obtained by using this method.

  In a semiconductor device assembly process, a wire bonding method for connecting a first bond point and a second bond point with a bonding wire uses a capillary to crimp the wire tip at the first bond point and open the capillary. By pulling up the wire in a state, the wire is fed out for a predetermined length, and then the clamp of the capillary is closed, the capillary is moved in the direction of the second bond point, and the wire is connected to the second bond point.

  As such a method, for example, as disclosed in Japanese Patent Publication No. 5-60657 and Japanese Patent Laid-Open No. 4-318943, there is a method of making the loop shape a triangle. In the wire bonding method in which the loop shape is triangular, in order to control the loop height, after the step of crimping the tip of the bonding wire to the first bond point, the capillary is raised slightly, and the capillary is connected to the second bond point. It is characterized by performing a reverse operation for moving in the opposite direction. By such a reverse operation, a bent ridge is applied to the wire, and the wire is bent around the bent ridge portion, thereby obtaining a triangular loop shape having the portion as a vertex.

  As an improvement of the wire bonding method for making the loop shape triangular, a wire bonding method for making the loop shape trapezoidal by performing the reverse operation twice as disclosed in JP-A-7-176558 is carried out. Has been. The second reverse operation in this method is performed in order to prevent a contact between the bonding wire and the chip angle by giving a bending wrinkle to a specific portion of the bonding wire that will be positioned at the chip angle after the loop is formed.

  However, this method has a drawback in that since the capillary performs the second reverse operation at a high position away from the first bond point, the curl is not sufficiently imparted and a stable loop shape cannot be obtained.

  In order to eliminate this drawback, Japanese Patent Application Laid-Open Nos. Hei 10-189441 and 2000-114304 describe a wire bonding method in which a downward recess is formed in the upper side portion of a trapezoidal loop shape, The loop shape obtained by this method is called an M-type loop.

  The wire bonding method for forming an M-type loop is effective for forming a loop shape having a loop height of about 200 μm or less if the wiring distance is about 3 mm or less. Recently, however, ultra-high-density integrated circuit chips require a large number of wires, and multi-stage loops that are formed to overlap multiple loops have been adopted, requiring longer wiring distances and lower loop heights. Has been. Such a request cannot be met by a conventional wire bonding method for forming an M-type loop.

  For example, when forming a loop having a triangular or trapezoidal loop shape with a wiring distance of more than 3 mm and a loop height of about 100 μm or less based on a conventional method, the first position from the first bond point is used. In order to lower the bent portion, the height of the initial reverse operation and the capillary moving distance are adjusted, and in order to increase the wiring distance, it is conceivable to carry out wire bonding by extending the bonding wire long. In this case, as shown in FIG. 10A, the central portion of the loop is lifted up like a mountain, making it difficult to make the loop height about 100 μm or less.

  Also, when the M-type loop is formed based on the conventional method, since the center portion of the M-type loop has a depression, the bent portion is lifted up like a mountain as shown in FIG. It has a loop shape with two peaks. In this case as well, it is difficult to make the loop height about 100 μm or less.

  Even if the center part of the loop is prevented from lifting like a mountain and the loop is kept almost horizontal, the position of the bent part where the loop makes a transition from vertical to horizontal is just above the first bond point. For example, in the case of a bonding wire made of a gold wire having a diameter of 25 μm, it is difficult to make the loop height 80 μm or less. This requires a certain curvature to bend without damaging the neck portion directly above the first bond point. In the conventional loop shape, the vicinity of the base of the first bond point is vertical, The height of the bent portion, which is the highest point, cannot be lowered below a certain level.

  Therefore, if the vicinity of the base of the first bond point is tilted toward the second bond point, the height of the bent portion, which is the highest point, can be further reduced. As a method therefor, for example, a wire It is conceivable that the wire is pulled when the second bond point is crimped by slightly shortening the feeding length. However, in this method, the neck portion immediately above the first bond point is strongly bent, and a large stress is generated in the bent portion, resulting in damage to the neck portion such as cracks or disconnection. There's a problem.

  On the other hand, in Japanese Patent Application Laid-Open No. 2005-39192, after crimping at the first bond point, the capillary is slightly lifted, then moved in the direction of the second bond, and then lowered by an amount smaller than the lift amount. After that, the capillary is lifted, the wire is fed out, and a reverse operation is performed, whereby an arc portion extending in an arc from the first bond point, a horizontal portion extending from the arc portion, and a horizontal portion extending from the horizontal portion to the second bond point A loop shape is disclosed which is composed of an extending inclined portion, and a refracting portion is formed at each connecting portion.

  However, using this technique, a bonding wire that connects a long wiring distance with a low loop height is not touched at the chip angle when crimping at the second bond point, and between the chip and the second bond point. If the distance is made as short as possible, it is difficult to adjust the capillary trajectory. In addition, when trying to form an arc portion extending in an arc shape without damaging the neck portion immediately above the first bond point, a certain curvature is required for the arc portion, so the loop height is set to 80 μm or less. Difficult to do.

Japanese Patent Publication No. 5-60657

Japanese Laid-Open Patent Publication No. 4-318943

Japanese Patent Laid-Open No. 7-176558

JP-A-10-189441

JP-A-2005-39192

JP 2000-114304 A

  An object of the present invention is to bond a bonding wire that connects a long wiring distance with a low loop height such that the wiring distance exceeds 3 mm and the loop height is about 100 μm or less at the second bond point. There is provided a wire bonding method that can be formed so as to make the distance between a chip and a second bond point as short as possible without sometimes touching the chip angle.

  Furthermore, a bonding wire that connects a long wiring distance with a lower loop height is cracked at the neck portion of the first bond point so that the wiring distance exceeds 3 mm and the height from the chip surface is about 80 μm or less. Alternatively, a wire bonding method capable of forming without causing fatal damage such as disconnection is provided.

  As described above, the present inventor found out that there are two main causes as a result of investigating the cause of the problem that the central portion of the loop is lifted up like a rough mountain.

  The first main cause is that in normal reverse operation, it is difficult to bend strongly at a lower position above the first bond point, so the bending angle becomes large. Therefore, as shown in FIG. The wire is lifted up toward the second bond point.

  The second main cause is that in the last reverse operation to bend the crease at the point where it hits the tip angle, the longer the bonding wire feed length, the more the capillary moves backward from the first bond point. As a result, bending creases become insufficient, so that when the bonding wire touches the chip angle and the chip angle serves as a fulcrum and is crimped at the second bond point, as shown in FIG. The bonding wire is lifted upward toward the first bond point.

  Therefore, as shown in FIG. 10A, the first main cause that the bonding wire is lifted upward from the bending point above the first bond point toward the second bond point, and the bonding wire is As shown in FIG. 10 (b), the chip corner is touched to intensively study to prevent the second main cause that the bonding wire lifts upward toward the first bond point above the chip angle. Thus, the present invention has been completed.

  One aspect of the wire bonding method of the present invention relates to a wire bonding method for connecting a first bond point and a second bond point. When moving the capillary from the first bond point to the highest point, In the vicinity of the point, a bend toward the second bond point from the first bond point is given, and a convex radius toward the second bond point is raised above the portion where the bend is given. A warp of 0 mm is formed, and a bent portion having a bend angle of 15 ° or more is formed in a portion located above the chip angle after forming the loop.

  That is, when the capillary reaches the highest point, the bonding wire has a bent ridge in the vicinity of the first bond point from the first bond point to the second bond point, and above the portion where the fold is present. It has a warp that is convex toward the second bond point and has a curvature radius of 0.5 mm to 3.0 mm, and further, a bending angle is formed toward the second bond point at a portion located above the chip angle after the loop is formed. It has a shape having a bent portion that is 15 ° or more.

  In order to provide such a shape, when a bonding wire made of a gold wire having a diameter of 15 μm to 30 μm is used, after the step of crimping the tip of the bonding wire to the first bond point, the capillary is slightly raised, Is moved in the direction opposite to the second bond point, and then the capillary is slightly raised so that the capillary has an elevation angle of 45 ° to 70 ° and a moving distance of 0.2 mm or more. As shown in FIG. 1, the capillary is moved upward, and the capillary is further lifted to feed the bonding wire to a point located above the chip angle after the loop is formed, and then the capillary is formed into an arc centered around the vicinity of the first bond point. Preferably, the second reverse operation is performed to move the arc in the direction opposite to the second bond point so that the center angle of the arc is 25 ° or more. Yeah. Thereafter, the capillary is moved to the second bond point along a predetermined locus to complete the formation of the loop.

  In a different aspect of the wire bonding method of the present invention, when the capillary is moved from the first bond point, a shape inclined toward the second bond point is formed at the base part of the first bond point of the bonding wire, and thereafter This inclination is maintained also in the process.

  In the subsequent process, a bent portion having a bend angle of 15 ° or more toward the second bond point is formed at a point located above the chip angle after forming the loop.

  In order to provide such a shape, when a bonding wire made of a gold wire having a diameter of 15 μm to 30 μm is used, after the step of crimping the tip of the bonding wire to the first bond point, the capillary is slightly raised, Is moved horizontally in the direction of the second bond point, and then the capillary is raised.

  After that, the capillary is raised to a point located above the chip angle after the loop is formed, and the bonding wire is fed out. Then, the capillary is moved in the direction opposite to the second bond point along the arc around the first bond point. Reverse operation to move to. In addition, about the process of forming this bend angle, you may make it pass through the process of the first aspect. Thereafter, the capillary is moved to the second bond point along a predetermined locus to complete the formation of the loop.

  In the semiconductor device of the present invention, since the loop of the bonding wire is formed by any one of the wire bonding methods described above, even if the distance between the first bond point and the second bond point is 3 mm or more, the loop height The thickness can be made 100 μm or less, preferably 80 μm or less, and the distance between the chip and the second bond point can be kept short.

  According to the present invention, even when the wiring distance exceeds 3 mm, a good wire bonding is possible with a loop shape having an extremely low loop height of about 80 μm or about 100 μm from the chip. An excellent semiconductor device is provided by connecting the second bond point and the second bond point with a wire loop.

  One embodiment of the wire bonding method of the present invention will be specifically described with reference to FIGS.

  FIG. 1 is a side view and an enlarged view showing a bonding wire when a capillary reaches the highest point in an embodiment of the wire bonding method of the present invention.

  As shown in FIG. 1, the bonding wire in the state where the capillary reaches the highest point has a bent ridge directly from the first bond point to the second bond point immediately above the first bond point, and It has a warp (D) that is convex toward the second bond point above a certain part (C) and has a curvature radius of 0.5 mm to 3.0 mm, and is located above the chip angle after the loop is formed. The portion has a bent portion (E) having a bend angle of 15 degrees or more toward the second bond point.

  The shape of the instantaneous bonding wire is specified by analyzing the image obtained by shooting the process with high-speed video. In the present invention, when the capillary reaches the highest point, it can be considered that the shape of the bonding wire shows only the shape of plastic deformation. Therefore, it can be said that the shape of the bonding wire at this time has the following two characteristics. .

  The first feature is that there is a bent crease from the first bond point to the second bond point, and it is convex toward the second bond point above the portion (C) with the crease and has a radius of curvature of 0.1. It has the curvature (D) by the plastic deformation which is 5 mm-3.0 mm. The radius of curvature indicates the strength of the warp.

  If the radius of curvature is less than 0.5 mm, there is a problem that the formed loop comes into contact with the chip. When the curvature radius exceeds 3.0 mm, the strength of the warp is insufficient and a good loop shape cannot be obtained.

  As a means for realization, after the step of crimping the tip of the bonding wire to the first bond point, the capillary is opened, the capillary is raised slightly, and then the capillary is moved in the direction opposite to the second bond point. A reverse operation is performed, after which the capillary is raised slightly, and further, the capillary is moved to the second bond point side by an appropriate obliquely upward angle and distance.

  Conventionally, after the first reverse operation, the capillary has been moved to an obliquely upper position, but the purpose is to enhance the effect obtained by the second reverse operation, and there is some characteristic in the wire. It was not intended to give. Therefore, it is not necessary to specify the moving direction and moving distance of the capillary when performing such movement, and there is no description in any known document.

  However, in the present invention, the characteristic is imparted to the bonding wire by means of moving the capillary to an obliquely upper position, and details of the capillary moving process are important. Giving distance is important. For example, in the case of a material characteristic close to pure gold with a wire diameter of 15 mm to 30 mm, the appropriate moving direction and moving distance obliquely upward of the capillary are such that the elevation angle is 45 ° to 70 ° and the moving distance is 0.2 mm or more. Adjust to.

  The second feature is that a portion that is located above the chip angle after the loop formation has a bent portion that is bent toward the second bond point and the bent angle is 15 ° or more. If the bending angle is less than 15 °, the distance from the chip angle to the second bond point becomes longer as the angle becomes smaller, and the demand for miniaturization of the semiconductor device cannot be satisfied.

  As a means for realization, following the above-described movement of the capillary obliquely upward, further raising the capillary with a predetermined trajectory until a portion that will be located above the tip angle appears after the loop formation, After feeding out the bonding wire, a second reverse operation is performed in which an arc centered around the first bond point is drawn and moved in the direction opposite to the second bond point. For example, in the case of a bonding wire made of a gold wire close to pure gold with a wire diameter of 15 mm to 30 mm, the moving distance necessary for the second reverse operation is around the first bond point in order to make the bending angle 15 ° or more. The circumferential angle of the center arc must be 25 ° or more, preferably 35 ° or more.

  The present invention can also be specified by a specific capillary trajectory.

  2A and 2B are diagrams respectively showing (a) a capillary trajectory from a first bond point to a second bond point in an embodiment of the present invention, and (b) an enlarged view showing a trajectory in an initial operation of the capillary. c) It is an enlarged view showing an initial position as an origin of these trajectories.

  The specific locus shown in FIG. 2 is that a bonding wire made of a gold wire having a diameter of 25 μm is used, the loop height is 100 μm or less, and the distance between the first bond point and the second bond point is 5.6 mm. This is the locus of the center of the capillary tip opening when forming a loop. That is, as shown in FIG. 2C, the origin of the locus is the center of the capillary tip opening when the tip of the bonding wire is crimped to the first bond point.

  The movement of the capillary can be divided into steps 1 to 9 as follows.

  [Step 1] After the step of crimping the tip of the bonding wire to the first bond point, the capillary is raised slightly. In the illustrated example, the height is increased by about 40 μm.

  [Step 2] A reverse operation for moving the capillary in the direction opposite to the second bond point is performed. In the illustrated example, it is moved by about 10 μm.

  [Step 3] Raise the capillary slightly. In the illustrated example, the height is increased by about 30 μm.

  [Step 4] The capillary is moved obliquely upward in the direction of the second bond point so that the elevation angle is 45 ° to 70 °. In the illustrated example, the horizontal movement distance is about 0.6 mm and the height is about 1 mm. The elevation angle in the obliquely upward movement is about 59 °. The shape of the bonding wire at the end of step 4 is shown in FIG.

  [Step 5] Raise the capillary in the open state so that the capillary feeds the bonding wire to the point where it will be located above the tip angle after the loop formation. In the illustrated example, it is raised by about 3.2 mm. The shape of the bonding wire at the end of step 5 is shown in FIG.

  [Step 6] The capillary is caused to perform a reverse operation so that the circumferential angle of the arc becomes 25 ° or more along the arc centered around the first bond point on the side opposite to the second bond point. In the illustrated example, the reverse operation is performed in which the center angle of the arc is about 50 °. The shape of the bonding wire at the end of step 6 is shown in FIG.

  [Step 7] The capillary is raised obliquely upward toward the second bond point. The shape of the bonding wire at the end of step 7 is shown in FIG.

  [Step 8] The capillary is moved to the position immediately above the first bond point in the open state. The shape of the bonding wire at the end of step 8 is shown in FIG.

  [Step 9] The capillary is moved from right above the first bond point to the second bond point along an arc centered around the first bond point, and the bonding wire is crimped to the second bond point. The shape of the bonding wire in the middle and at the end of step 9 is shown in FIG.

  In the present invention, particularly important steps are step 4 and step 6.

  In step 4, the opening edge of the capillary tip moves while squeezing the bonding wire diagonally. That is, since the opening edge of the capillary slides while pressing the side surface of the bonding wire in one direction, warping (D) in which the lower side is convex occurs. The effect of this warp (D) can prevent the conventional phenomenon in which the bonding wire is lifted from above the first bond point by pressure bonding at the second bond point in the formed loop shape.

  In Step 4, since the effect obtained by pressing the side surface of the bonding wire in one direction is based on the elasticity of the bonding wire, the distance from the first bond point becomes weaker. Even if it is too long, many effects are not obtained. The strength of warpage (D) depends on the elevation angle when the capillary moves, but if the elevation angle is reduced, the bonding wire will come into contact with the chip surface even if the warpage becomes too strong. It is. For example, in the case of a material characteristic close to pure gold with a wire diameter of 15 mm to 30 mm, the appropriate moving direction and moving distance in step 4 are 45 ° to 70 ° in elevation angle, and the moving distance is 0.2 mm or more. Adjust it. If the elevation angle is less than 45 ° and it is too small, the warp above the first bond point becomes too strong, and the bonding wire touches the chip surface at the portion of the bonding wire from above the first bond point to the second bond point. There is a risk that. On the other hand, if the elevation angle exceeds 70 ° and is too large, the effect of causing warpage above the first bond point is too small. If the moving distance is less than 0.2 mm, and if it is too small, the length of the portion where the warp occurs above the first bond point is too short, and in the loop shape of the obtained loop, the second bond from above the first bond point. The conventional problem that rises in the part toward the point cannot be solved. If the moving distance is long, there is no problem in the effect of preventing such swell, and the upper limit of the moving distance may be determined based on the conditions given to the loop shape.

  In step 6, since the opening edge of the capillary tip always pressurizes one point of the bonding wire, a strong bending crease (E) can be applied. As a result, when crimping at the second bond point, It is possible to prevent the bonding wire from being lifted toward the first bond point.

  In Step 6, the movement distance of the reverse operation in which the vicinity of the first bond point advances about 50 ° along the central arc to the opposite side of the second bond point is as the bonding wire becomes thinner and the first bond point The longer the distance between the second bond point and the second bond point, the weaker the brazing. Therefore, in order to obtain a predetermined wire bending angle, it is necessary to increase the length. For example, when the bonding wire diameter is 15 mm to 30 mm and the material characteristics are close to pure gold, in order to obtain a wire bending angle of 15 ° or more, the moving distance of the reverse operation is an arc centered around the vicinity of the first bond point. A circumferential angle (reverse motion rotation angle) of 25 ° or more, preferably 35 ° or more is required. If the moving distance of the reverse operation for drawing the arc is longer than necessary, it takes time for the wire bonding, and the burden on the neck portion increases, which is inconvenient. Accordingly, the movement distance is preferably within 70 ° as the circumferential angle of the arc.

  Step 4 can be modified within the scope of the present invention. Instead of the movement of the straight line, it may be a movement of a downwardly convex curve as shown in FIG. However, as shown in FIG. 4 (b), it is convex upward and has a substantially circular arc. In particular, if it is first raised almost vertically, it is difficult to generate warp, which is inconvenient. Further, as shown in FIG. 4 (c), the initial operation may omit the step 3. On the other hand, after the step 3, as shown in FIG. 4 (d) or FIG. A step of moving horizontally or slightly downward in the direction may be provided. Further, as shown in FIG. 4 (f), a horizontal movement operation in the direction of the second bond point, as seen in the M-type loop formation process, may be added before being raised directly in step 5. . In this case, in the formed loop, a recess similar to the M-type loop is formed in the middle of the horizontal portion as shown in FIG. Furthermore, Step 7, Step 8, and Step 9 can be variously modified within the scope of the gist of the present invention. For example, in Step 7 and Step 8, as shown in FIG. As shown in FIG. 4H, the capillary may reach the highest point at the end of step 7 as shown in FIG. However, in order to balance the unrolled length of the bonding wire and the distance between the first bond point and the second bond point, it is necessary to adjust the clamping position or change the aspect ratio of the locus.

  Different aspects of the wire bonding method of the present invention will be specifically described with reference to FIGS.

  FIG. 6 is an enlarged view showing (a) the trajectory of the capillary from the first bond point to the second bond point, and (b) the trajectory in the initial operation of the capillary, respectively, in a different embodiment of the present invention. .

  First, a different aspect of the wire bonding of the present invention will be described based on a specific capillary trajectory with reference to FIG. The specific trajectory shown in FIG. 6 is a bonding wire made of a gold wire having a diameter of 25 μm, a height of 80 μm or less, and a distance between the first bond point and the second bond point of 5.6 mm. This is the locus of the center of the capillary tip opening when a certain loop is formed. That is, the origin of the locus is the center of the capillary tip opening when the tip of the bonding wire is crimped to the first bond point (see FIG. 2C).

  The movement of the capillary can be divided into steps 1 to 9 as follows.

  [Step 1] After the step of crimping the tip of the bonding wire to the first bond point, the capillary is raised slightly. In the illustrated example, the height is increased by about 40 μm.

  [Step 2] The capillary is moved horizontally in the direction of the second bond point. In the example shown in the figure, it is moved about 20 μm.

  [Step 3] Raise the capillary. In the illustrated example, it is raised by about 0.5 mm.

  [Step 4] The capillary is moved horizontally in the direction of the second bond point. In the example shown in the figure, it is moved about 0.15 mm.

  [Step 5] The capillary is moved vertically upward. In the illustrated example, the height is increased by about 3.7 mm.

  [Step 6] A reverse operation is performed in which the capillary is moved along an arc centered around the first bond point to the opposite side of the second bond point so that the circumferential angle of the arc is about 45 °.

  [Step 7] The capillary is vertically moved upward. In the illustrated example, the height is raised to about 4.4 mm. This is the highest point.

  [Step 8] The capillary is moved to the second bond point so as to draw a general parabola.

  [Step 9] A bonding wire is pressure-bonded to the second bond point.

  As shown in FIG. 7, the shape of the bonding wire at the highest point of the trajectory, that is, the end point of step 7, is inclined near the base of the first bond point (C) in the direction of the second bond point. Further, the shape of the finally formed loop is shown in FIG. As shown in FIG. 8, since the inclination is maintained near the base of the first bond point (D), a loop having a height of 70 μm or less from the chip surface is formed. According to the simulation of wire bonding by nonlinear structural analysis, the stress generated in the neck portion in this aspect is not more than the breaking stress at the maximum.

  An important step in the present embodiment is step 2. In step 2, an operation of pressing in the horizontal direction near the base of the first bond point is performed. Therefore, the bonding wire near the base is plastically deformed and tilted obliquely in the direction of the second bond point. Since this inclination is maintained until the loop is formed in the subsequent process, the loop shape in which the vicinity of the base of the first bond point is inclined obliquely in the direction of the second bond point without cracking or breaking in the neck portion. Formation is possible. Therefore, the neck height can be suppressed without causing a defect in the first bond point.

  In this way, if the capillary is moved while pressing the vicinity of the base of the first bond point in the horizontal direction, the trajectory may be different from that of the capillary shown in FIG. After the tip of the bonding wire is crimped, change is made so that the step 1 of raising the capillary vertically and the step 2 of horizontally moving in the direction of the second bond point are performed simultaneously, that is, obliquely upward. May be.

  On the other hand, after the step 3, it is one of the means for preventing the conventional problem that the center of the formed loop is lifted up like a mountain. Steps 3 and 4 prevent the vicinity of the first bond point from being lifted upward toward the second bond point as shown in FIG. Also, in Step 6, by attaching a strong bend to the portion of the wire above the chip corner, the bonding wire is lifted upward from the top of the chip corner toward the first bond point as shown in FIG. 10B. Is preventing. In this way, the capillary may be moved so as to draw another trajectory as long as the center of the loop is prevented from lifting like a mountain.

  In addition, following step 1 and step 2 of the present embodiment, the steps 4 to 9 of the above-described embodiment are sequentially performed so that the bonding wire is crimped to the second bond point. It is also effective to form a loop using a method that combines the two embodiments.

Example 1
Using a bonding wire made of a gold wire having a wire diameter of 15 μm and close to pure gold, the following steps 1 to 9 are performed, the wiring length is 5.6 mm, and the distance between the chip and the second bond point is A loop with about 1000 μm and a loop height of 80 μm to 100 μm was obtained. The shape of the bonding wire in steps 4 to 9 is as shown in FIG.

  [Step 1] After the step of crimping the tip of the bonding wire to the first bond point, the capillary was raised by about 40 μm.

  [Step 2] A reverse operation was performed in which the capillary was moved 10 μm in the direction opposite to the second bond point.

  [Step 3] The capillary was raised by 30 μm.

  [Step 4] The capillary was moved in the direction of the second bond point so as to follow any one of 30 conditions with the moving distance and the elevation angle shown in Table 1 as parameters.

  [Step 5] The capillary was raised by 3.2 mm while feeding the bonding wire to the point where it would be located above the tip angle after the loop formation.

  [Step 6] A reverse operation was performed in which the capillary was moved along an arc centered near the first bond point so that the center angle of the arc was about 50 ° on the side opposite to the second bond point.

  [Step 7] The capillary was raised obliquely upward toward the second bond point.

  [Step 8] The capillary was moved to a position just above the first bond point along an arc centered around the vicinity of the first bond point. This was the highest point of the Capilary trail.

  [Step 9] The capillary was moved to the second bond point by continuing the arc-shaped movement of Step 8, and then the bonding wire was crimped to the second bond point.

  The curvature radius of the warp above the first bond point in the shape when the capillary reached the highest point was measured, and comprehensive evaluation was performed based on the loop shape of the obtained loop. The evaluation was “◯” if the loop shape was preferable (the wire did not touch the chip and the loop height did not greatly exceed 100 μm), and “Δ” otherwise. The evaluation results are shown in Table 1.

(Example 2)
A loop was obtained and evaluated in the same manner as in Example 1 except that the wire diameter was 20 μm and the conditions of Step 4 were as shown in Table 2. The evaluation results are shown in Table 2.

(Example 3)
A loop was obtained and evaluated in the same manner as in Example 1 except that the wire diameter was 30 μm and the conditions of Step 4 were as shown in Table 3. The evaluation results are shown in Table 3.

Example 4
In step 4, the capillary is moved in the direction of the second bond point, the horizontal distance is about 0.6 mm, the height is 1 mm (elevation angle of about 60 °), and the capillary in step 6 is near the first bond point. A loop was obtained in the same manner as in Example 1 except that the center angle (reverse motion rotation angle) of the arc when moving to the opposite side of the second bond point along the arc centered on .

  The evaluation was performed by measuring the relationship between the wire bending angle (15 ° or more) indicating the change in the strength of the resulting wire bending wrinkles and the reverse motion rotation angle in Step 6. The measurement results are shown in FIG.

(Example 5)
A loop was obtained and evaluated in the same manner as in Example 4 except that the wire diameter was 20 μm. The measurement results are shown in FIG.

(Example 6)
A loop was obtained and evaluated in the same manner as in Example 4 except that the wire diameter was 30 μm. The measurement results are shown in FIG.

  In the case of Examples 4 to 6, as is clear from FIG. 9, when the reverse motion rotation angle is 25 ° or more, when the linearity is 30 μm, a wire bending angle of 15 ° or more can be obtained. It is understood that if the motion rotation angle is 35 ° or more, a wire bending angle of 15 ° or more can be obtained even when the wire diameter is 15 μm.

(Example 7)
Using a bonding wire made of a gold wire close to pure gold having a wire diameter of 25 μm, the following steps 1 to 9 are performed, the wiring length is 5.6 mm, and the distance between the chip and the second bond point is A semiconductor device having a thickness of about 1000 μm was produced.

  [Step 1] After the step of crimping the tip of the bonding wire to the first bond point, the capillary was raised by about 40 μm.

  [Step 2] The capillary was horizontally moved by about 20 μm in the direction of the second bond point.

  [Step 3] The capillary was raised about 0.5 mm.

  [Step 4] The capillary was moved horizontally by about 0.15 mm in the direction of the second bond point.

  [Step 5] The capillary was raised vertically by about 3.7 mm.

  [Step 6] A reverse operation was performed in which the capillary was moved about 55 ° to the opposite side of the second bond point along an arc centered around the first bond point.

  [Step 7] The capillary was raised vertically to a height of about 4.4 mm. This point is the highest point of the capillary trajectory.

  [Step 8] The capillary was moved to the second bond point so as to draw a general parabola.

  [Step 9] The bonding wire was crimped at the second bond point.

  As a result, the locus of the capillary was as shown in FIG. 6, and a loop with a loop height of 75 μm with respect to the chip was obtained.

(Example 8)
Using a bonding wire made of a gold wire having a wire diameter of 25 μm and close to pure gold, the following steps 1 to 8 are performed. The wiring length is 5 mm, and the distance between the chip and the second bond point is about 1000 μm. A semiconductor device was produced.

  [Step 1] After the step of crimping the tip of the bonding wire to the first bond point, the capillary was raised by about 40 μm.

  [Step 2] The capillary was horizontally moved about 20 μm in the direction of the second bond point.

  [Step 3] The capillary was moved in the direction of the second bond point by a horizontal distance of about 0.8 mm and a height of about 1.5 mm. The elevation angle in the diagonally upward movement was about 62 °.

  [Step 4] The capillary was raised 1.5 mm while feeding the bonding wire to the point where it would be located above the tip angle after the loop formation.

  [Step 6] A reverse operation was performed in which the capillary was moved about 55 ° to the opposite side of the second bond point along an arc centered around the first bond point.

  [Step 6] The capillary was moved obliquely upward toward the second bond point.

  [Step 7] The capillary was moved to the second bond point side along an arc centered around the vicinity of the first bond point to just above the first bond point.

  [Step 8] The capillary was moved to the second bond point by continuing the circular movement in Step 7, and the bonding wire was crimped to the second bond point.

  As a result, a loop having a loop height of 70 μm with respect to the chip was obtained.

In one Example of the wire bonding method of this invention, it is the side view and enlarged view which showed the bonding wire when the capillary reached the highest point. In one Example of this invention, (a) The figure of the locus | trajectory of a capillary, (b) The enlarged view which shows the locus | trajectory of the initial operation | movement of a capillary, (c) The enlarged view which shows the initial position which is the origin of these locus | trajectories is there. It is a side view which shows the bonding wire in the process 4-the process 9 in the embodiment which showed the locus | trajectory in FIG. It is a side view which shows the modification of the locus | trajectory of a capillary which shows the process 4 in the embodiment which showed the locus | trajectory in FIG. It is a side view which shows the loop shape of the loop obtained by the embodiment which showed the locus | trajectory in FIG. (A) Drawing of locus of capillary and (b) Enlarged view showing locus of initial operation of capillary in different embodiments of the present invention. It is a side view which shows the bonding wire in the last point of the process 7 in the embodiment which showed the locus | trajectory in FIG. It is a side view which shows the loop shape of the loop obtained by the embodiment which showed the locus | trajectory in FIG. It is a graph which shows the relationship between the reverse motion rotation angle and the wire bending angle in the process 6 of one Example of this invention. It is a side view which shows the loop shape of the loop obtained by a prior art.

Explanation of symbols

A 1st bond point B Tip angle C Bent part D Bend E Bent part

Claims (14)

  In the wire bonding method for connecting the first bond point and the second bond point, when moving the capillary from the first bond point to the highest point, the bonding wire is moved from the first bond point to the second bond in the vicinity of the first bond point. A bent wrinkle toward the point is given, and a warp with a radius of curvature of 0.5 mm to 3.0 mm is formed above the portion where the bent wrinkle is given, and the radius of curvature is 0.5 mm to 3.0 mm. A wire bonding method comprising forming a bent portion having a bent angle of 15 ° or more toward a second bond point at a portion located above the corner. After using the bonding wire made of a gold wire having a diameter of 15 μm to 30 μm and applying the bent wrinkles, the capillary has an elevation angle of 45 ° to 70 ° and a moving distance of 0.2 mm or more. The wire bonding method according to claim 1, wherein the warp is formed by moving obliquely upward. In the step of forming the bent portion using a bonding wire made of a gold wire having a diameter of 15 μm to 30 μm, the capillary has a center angle of 25 ° or more along an arc centered around the first bond point. The wire bonding method according to claim 1, wherein the wire bonding method is moved in a direction opposite to the second bond point.   In the wire bonding method of connecting the first bond point and the second bond point using a bonding wire made of a gold wire having a diameter of 15 μm to 30 μm, after the step of crimping the tip of the bonding wire to the first bond point, A step of slightly raising the capillary, a step of performing a first reverse operation for moving the capillary in a direction opposite to the second bond point, a step of slightly raising the capillary, and an elevation angle of 45 ° to 70 °, The step of moving diagonally upward so that the moving distance becomes 0.2 mm or more, the step of raising the capillary and feeding the bonding wire to the point located above the chip angle after forming the loop, the capillary near the first bond point Performing a second reverse operation for moving the second bond point in a direction opposite to the second bond point along the center arc; Beauty, wire bonding method characterized by comprising the step of moving the capillary to the second bonding point drawing a predetermined trajectory.   The wire bonding method according to claim 4, wherein, in the second reverse operation, the capillary is moved until a center angle of the arc becomes 25 ° or more.   In the wire bonding method for connecting the first bond point and the second bond point, when the capillary is moved from the first bond point, the base portion of the bonding wire is inclined toward the second bond point. A wire bonding method characterized by forming a shape and maintaining the inclined shape even in subsequent steps.   After forming a shape inclined toward the second bond point at the base part of the first bond point of the bonding wire, until the capillary is moved to the highest point, the point positioned above the chip angle after the loop is formed The wire bonding method according to claim 6, wherein a bent portion having a bending angle of 15 ° or more toward the second bond point is formed.   After forming a shape inclined toward the second bond point at the base portion of the first bond point of the bonding wire, the shape is convex toward the second bond point above the portion and has a radius of curvature of 0.5 mm to 3 mm. The wire bonding method according to claim 6, wherein a bent portion having a bent angle of 15 ° or more is formed toward the second bond point after the warp of 0.0 mm is formed and before the capillary is moved to the highest point.   In the wire bonding method of connecting the first bond point and the second bond point using a bonding wire made of a gold wire having a diameter of 15 μm to 30 μm, after the step of crimping the tip of the bonding wire to the first bond point, A step of slightly raising the capillary, a step of horizontally moving the capillary toward the second bond point, a step of raising the capillary and feeding the bonding wire to a point where it is positioned above the chip angle after the loop is formed, A step of performing a reverse operation for moving in a direction opposite to the second bond point along an arc centered around the vicinity of one bond point, and a step of moving the capillary to a second bond point along a predetermined locus Wire bonding method.   The wire bonding method according to claim 9, wherein the step of slightly raising the capillary and the step of horizontally moving the capillary toward the second bond point are performed simultaneously to move the capillary obliquely upward.   In the wire bonding method of connecting the first bond point and the second bond point using a bonding wire made of a gold wire having a diameter of 15 μm to 30 μm, after the step of crimping the tip of the bonding wire to the first bond point, Step of slightly raising the capillary, step of horizontally moving the capillary toward the second bond point, step of moving the capillary obliquely upward so that the elevation angle is 45 ° to 70 ° and the moving distance is 0.2 mm or more The step of raising the capillary and feeding the bonding wire to a point located above the chip angle after forming the loop, and moving the capillary in a direction opposite to the second bond point along an arc centered around the first bond point A step of performing a reverse operation, and a step of moving the capillary to a second bond point along a predetermined locus. A wire bonding method comprising:   The wire bonding method according to claim 11, wherein, in the second reverse operation, the capillary is moved until a center angle of the arc becomes 25 ° or more.   The distance between the first bond point and the second bond point exceeds 3 mm, and a bonding wire loop is formed by the wire bonding method according to claim 1, and the loop height of the loop is 100 μm. The following semiconductor device.   The distance between the first bond point and the second bond point exceeds 3 mm, and a bonding wire loop is formed by the wire bonding method according to claim 6, and the loop height of the loop is 80 μm. The following semiconductor device.

Images