TW201342554A - Wire structure for semiconductor package and manufacturing method thereof - Google Patents

Abstract

A wire structure for a semiconductor package and a manufacturing method thereof are provided. The method has steps of: heating an indium-containing material, so that the indium-containing material is melt to form an indium-containing ball; providing a copper wire having a front end; and connecting the front end of the copper wire with the indium-containing ball, so as to construct a wire structure. The copper wire is connected to a pad of a chip through the indium-containing ball. Thus, the structural integrity of the pad of the chip can be maintained, in order to enhance the quality and yield of the wire bonding process of copper wires.

Description

Conductor structure of semiconductor device and manufacturing method thereof

The present invention relates to a wire structure of a semiconductor device and a method of fabricating the same, and more particularly to a wire structure of a semiconductor device comprising a copper wire and an indium containing ball and a method of manufacturing the same.

In the conventional semiconductor integrated circuit (IC) chip package manufacturing process, most of the gold wire is used to connect the wafer and the carrier board, but the copper wire has the advantage of low cost compared with the gold wire. And having better conductivity, thermal conductivity and mechanical strength, the wire diameter of the copper wire can be designed to be finer and can provide better heat dissipation efficiency. Therefore, there is a research and development trend in which the copper wire is gradually replacing the traditional gold wire and It is applied to a wire bonding process of a semiconductor wafer.

According to the prior art, a wire bonding process generally includes the following steps: First, a wafer and a carrier are provided, the wafer having a plurality of pads (eg, aluminum pads) having a plurality of pads ( For example, a copper pad), and the carrier carries the wafer; then, a copper wire is electronically ignited by a soldering needle to form a ball end (ie, the first end), and the ball end is heated by the soldering pin Pressing and bonding on the pad of the wafer; thereafter, moving the soldering pin to guide the copper wire to the corresponding pad of the carrier; finally, the copper wire is thermally pressed and broken on the pad by the soldering pin A tail end (ie, the second end) is formed.

During the above-mentioned wire bonding, when the copper wire forms the ball end, the welding pin impacts the pad with a vertical pressing force, and then guides the copper wire with a lateral pulling force, so that the copper wire is curved. Finally, the copper wire is torn off to form the tail end.

However, the pads on the active surface of the wafer are usually aluminum pads, and the Young's modulus of the aluminum metal itself is about 68-70 GPa, and the Young's modulus of the copper metal itself is about 110 GPa. Since the hardness of the copper wire with reference to the Young's modulus is significantly greater than the hardness of the pad of the wafer, when the soldering pin has a vertical pressing force (ie, a positive stress), the ball end of the copper wire hits the ball end. In the case of the pad, in addition to the deformation of the ball end (ie, the forward strain), the pad is also prone to severe deformation or cracking due to the forward stress of the ball end impact. In severe cases, even a passivation, integrated circuit layer or germanium substrate under the pad may cause cracking defects. As a result, the problem of the rupture of the pad caused by the ball end will reduce the processing quality and yield of the wire bonding process of the copper wire.

Therefore, it is necessary to provide a wire structure of a semiconductor device and a method of manufacturing the same to solve the problem of rupture of a pad existing in the prior art.

An object of the present invention is to provide a wire structure for a semiconductor device comprising: a copper wire and an indium containing solder ball. The copper wire has a front end, and the indium containing solder ball is bonded to the front end of the copper wire. The copper wire is inserted into the indium-containing solder ball at the front end to form a wire structure.

Furthermore, another object of the present invention is to provide a semiconductor device including: a wafer, a carrier, and at least one wire structure. The wafer has at least one pad. The carrier has at least one pad and the carrier carries the wafer. The at least one wire structure each has a copper wire and an indium-containing solder ball, the copper wire has a front end and a tail end, and the indium-containing solder ball is coupled to the front end of the copper wire, and the copper wire is inserted at the front end Indium-containing solder balls. The indium-containing solder ball is pressure-deformed and bonded to the pad of the wafer, and the tail end of the copper wire is bonded to the pad of the carrier.

Another object of the present invention is to provide a method of fabricating a wire structure for a semiconductor device comprising the steps of: heating an indium containing material to melt it to form an indium containing solder ball. Next, a copper wire is provided having a front end. Subsequently, the copper wire front end is combined with the indium containing solder ball to constitute a wire structure.

Referring to FIG. 1 , a wire structure 10 for a semiconductor device according to an embodiment of the present invention is disclosed. The wire structure 10 is mainly applied to a wire bonding operation in a packaging process of a semiconductor device. The wire structure 10 includes: A copper wire 11 and an indium containing solder ball 12. The copper wire 11 has a front end 111, the indium containing solder ball 12 is bonded to the front end 111 of the copper wire 11, and the front end 111 of the copper wire 11 is inserted into the indium containing solder ball 12. The material of the copper wire 11 of the present embodiment may be selected from pure copper (Cu) or a copper alloy, wherein the copper metal has a Young's modulus of about 110 GPa. The copper wire 11 has a wire diameter of substantially between 15 and 35 micrometers (μm), for example, 15, 20, 25, 30 or 35 micrometers. The material of the indium containing solder ball 12 is selected from pure indium (In), indium silver (In/Ag) alloy or indium tin (In/Sn) alloy, wherein the indium metal has a Young's modulus of about 10 GPa. In the present embodiment, the indium containing solder ball 12 has a spherical diameter of substantially between 50 and 65 microns, such as 50, 55, 60 or 65 microns. The length of the front end 111 of the copper wire 11 inserted into the indium containing solder ball 12 is between 1/4 and 3/4 of the ball diameter of the indium containing solder ball, for example, 1/4, 1/3, 1/ 2, 2/5 or 3/4, etc.

Furthermore, an intermetallic compound (IMC) layer 13 is formed between the front end 111 of the copper wire 11 and the indium containing solder ball 12. The intermetallic compound of the intermetallic layer 13 may be Cu ₂ In, Cu ₇ In ₃ or Cu ₁₁ In ₉ ; and the thickness of the intermetallic layer 13 is generally between 0.01 and 1 micron, for example 0.01, 0.05, 0.1, 0.5 or 1 micron or the like. In addition, the surface of the indium-containing solder ball 12 has an indium oxide protective layer 121, and the indium oxide protective layer 121 has a thickness of approximately 10 to 100 nanometers (nm), for example, 10, 20, 30, 50, 70, 80 or 100 nm, etc.

Referring to FIG. 2, the copper wire 11 front end 111 can be bonded to one of the pads 21 of the wafer 20 by using the indium solder ball 12, and the copper wire 11 is further provided by the existing wire bonding operation. A tail end 14 is coupled to a pad 31 of one of the carrier plates 30, thereby electrically connecting the wire structure 10 to the pad 21 and the pad 31.

As described above, the above embodiment of the present invention processes and forms the indium-containing solder ball 12 by the low melting point of the indium metal and the material properties which are easy to process, and bonds it to the front end 111 of the copper wire 11, and between copper and indium. The formed metal layer 13 has the characteristics of slow growth and sufficient bonding strength, so that the bonding reliability between the copper wire 11 and the indium containing ball 12 is ensured. Furthermore, the above embodiment of the present invention further utilizes the material property of the Young's modulus (hardness) of the indium-containing solder ball 12 which is significantly smaller than the Young's modulus (hardness) of the pad 21 (aluminum pad) of the wafer 20, so that The copper wire 11 is bonded to the pad 21 of the wafer 20 via the medium containing the indium solder ball 12, so that the indium-containing solder ball 12 can be firmly pressed and bonded to the pad 21 of the wafer 20, Moreover, the pad 21 of the wafer 20 does not affect the structural integrity of the indium-containing solder ball 12, and thus it is advantageous to improve the processing quality and yield of the wire bonding process of the copper wire 11.

In addition, the wafer 20 refers to, for example, a semiconductor wafer cut from a semiconductor wafer, such as a germanium wafer or a gallium arsenide wafer. The pad 21 of the wafer 20 refers to a metal pad having a hardness (or Young's modulus) smaller than copper but larger than indium, such as an aluminum pad, but is not limited thereto, wherein the Young's modulus of the aluminum metal is about 68-70. GPa.

Furthermore, the carrier 30 can be selected from a multilayer printed circuit substrate or a leadframe. The pad 31 of the carrier 30 is a metal pad with good conductivity, such as a copper pad. The surface of the pad 31 may also be pre-formed with a solder layer, such as a nickel-gold (Ni/Au) composite layer, and nickel/palladium. / Gold (Ni / Pd / Au) composite layer, silver layer or organic solderability preservative (OSP).

The present invention will be described in detail below using FIGS. 3A through 3C, 4A through 4C, and 5A through 5C drawings to illustrate in detail the various implementation details and principles of the various embodiments of the wire construction 10 and its various steps:

Referring to FIG. 3A, in the manufacturing method of the wire structure disclosed in one embodiment of the present invention, the indium-containing material 120 is formed into a spherical shape in advance, and the spherical indium-containing material is loaded by a dosing tube 40. 120. Then, the spherical indium-containing material 120 is outputted to the accommodating groove 41 one by one, and an internal passage of the dispensing tube 40 and an accommodating space of the accommodating groove 41 have a width. Slightly larger than the spherical diameter of the spherical indium-containing material 120, and the accommodating groove 41 can be moved to a desired position by a moving device such as a robot arm or a conveyor belt.

Referring to FIG. 3B, the spherical indium-containing material 120 positioned in the accommodating groove 41 is heated to melt or soften and initially form the indium-containing solder ball 12. In this embodiment, a laser device 42 is used to emit a laser beam to instantaneously heat the spherical indium-containing material 120 in the accommodating groove 41, so that the temperature of the spherical indium-containing material 120 is obtained. Above or near its melting point (e.g., the melting point of indium is 156.6 ° C) thus melts or softens and initially forms the indium containing solder balls 12, at which point the indium containing solder balls 12 are still in a molten or softened state.

Referring to FIG. 3C, the moving device moves the receiving groove 41 or moves the welding pin 50 to the position of the receiving groove 41. A soldering pin 50 is provided to provide a copper wire 11; and the soldering pin 50 is moved to bond the front end 111 of the copper wire 11 with the indium containing solder ball 12 to form a wire structure 10. The soldering pin 50 has a wire supply hole 51 for continuously supplying the copper wire 11, and can temporarily stop the threading operation when the indium-containing solder ball 12 is to be combined, and the front end 111 of the copper wire 11 is exposed to the supply wire. The hole 51 is about a predetermined length outside. When bonding, the front end 111 of the copper wire 11 is inserted into the indium-containing solder ball 12 by moving the soldering pin 50 or the moving device of the receiving groove 41, so that the wire structure 10 can be completed. The wire structure 10 is moved by the welding pin 50 to a wire working area for wire bonding.

Referring to FIG. 4A, in a method for fabricating a wire structure according to another embodiment of the present invention, a linear indium-containing material 120 is first supplied by a wire supply unit 60; and then a section of the wire is cut. The indium-containing material 120 is placed and placed in a receiving groove 61. The wire supply unit 60 is, for example, selected from another welding pin for continuously supplying the linear indium-containing material 120, and temporarily suspending the threading action when the linear indium-containing material 120 is to be intercepted. One of the front ends of the linear indium-containing material 120 exposes one of the wire supply units 60 for a predetermined length outside the line hole. Then, a portion of the linear indium-containing material 120 may be cut and intercepted by a cutter or a laser and placed into the accommodating groove 61.

Referring to FIG. 4B, the linear indium-containing material 120 located in the accommodating groove 61 is heated to be melted or softened to form a spherical indium-containing solder ball 120. The width of the accommodating space of the accommodating groove 61 is slightly larger than the predetermined ball diameter of the subsequent indium-containing solder ball 12, and a heater 62, for example, a heating coil, may be disposed inside or outside the accommodating groove 61 itself. Therefore, the heater 62 can be used (or a laser beam can be emitted by a laser device) to heat the linear indium-containing material 120 located in the accommodating groove 61 so that the temperature is higher or closer to the melting point thereof. (For example, the melting point of indium is 156.6 ° C), thereby melting or softening and initially forming spherical indium-containing solder balls 120.

Referring to FIG. 4C, a copper wire 11 is provided by a soldering pin 50; and a further step is to combine the front end 111 of the copper wire 11 with the indium containing solder ball 12 by moving the soldering pin 50. To form a wire construction 10. The detailed steps are as described above and will not be described here.

Referring to FIG. 5A, in the manufacturing method of the wire structure disclosed in another embodiment of the present invention, the copper wire 11 and the linear indium containing material 120 are simultaneously supplied by using a composite welding pin 70. The composite soldering pin 70 has a first supply hole 71 and a second supply hole 72 for continuously supplying the copper wire 11 and the linear indium containing material 120, respectively. The copper wire 11 and the linear indium-containing material 120 respectively expose a predetermined length of the first and second supply holes 71, 72 of the composite soldering pin 70, wherein the length of the copper wire 11 exposed may be less than or It is equal to the length of the linear indium containing material 120 exposed.

Referring to FIG. 5B, when heating is performed, an electronic ignition lever 80, a laser beam (not shown), or a heating coil (not shown) may be selected to heat and expose the composite soldering needle 70. The linear indium-containing material 120 is externally brought to a temperature higher or closer to its melting point (for example, the melting point of indium is 156.6 ° C) to thereby melt or soften and initially form the indium-containing solder ball 12.

The first and second supply holes 71, 72 of the composite soldering pin 70 are designed such that the distance between the copper wire 11 and the linear indium containing material 120 is smaller than the radius of the indium containing solder ball 12. Therefore, when the indium-containing solder ball 12 is formed, the indium-containing solder ball 12 is contactably and spontaneously adhered to the front end 111 of the adjacent copper wire 11, so that the front end 111 of the copper wire 11 is located. Indium-containing solder balls 12 are included.

Referring to FIG. 5C, the indium-containing solder ball 12 is separated from the linear indium-containing material 120. If necessary, the linear indium-containing material 120 may also be appropriately directed into the second supply hole 72 at this time. The short distance is retracted to cause the indium containing solder ball 12 to smoothly break away from the linear indium containing material 120. Thereby, the fabrication of the wire structure 10 can be completed, and the wire structure 10 is moved by the welding pin 50 to a wire working area for wire bonding.

Referring to FIG. 6A, a wire bonding method for a wire structure of a semiconductor device according to an embodiment of the present invention is disclosed. The wire structure 10 prepared by using any of the above manufacturing methods is used to perform a wire bonding process of a copper wire.

A wafer 20 and a carrier 30 are provided. The wafer 20 has a plurality of pads 21 (eg, aluminum pads) having a plurality of pads 31 (eg, copper pads), and the carrier 30 carries the wafers 20 Providing a copper wire 11 by a soldering pin 50, wherein the front end 111 of the copper wire 11 is pre-bonded to the indium-containing solder ball 12; the indium-containing solder ball 12 is used as a ball end (ie, the first end), and The indium containing solder balls 12 are thermocompression bonded to the pads 21 of the wafer 20 by the solder pins 50.

In the above step of using the indium-containing solder ball 12 as the ball end, the present invention may be applied to the indium-containing solder ball 12 immediately after the manufacturing method of the 3A to 3C, 4A to 4C or 5A to 5C drawings. When curing, the indium-containing solder ball 12 is immediately bonded to the pad 21 of the wafer 20 by using the soldering pin 50; or, after the indium-containing solder ball 12 has been cured, an electronic ignition may be further utilized. A rod (not shown) is used to melt or soften the indium containing solder ball 12 again to bond the indium containing solder ball 12 to the pad 21 of the wafer 20 by means of the solder pin 50. If the wire structure 10 is produced by the manufacturing method of Figs. 5A to 5C, the welding pin 50 is the composite welding pin 70.

Referring to FIG. 6B, the soldering pin 50 is then moved to guide the copper wire 11 to the corresponding pad 30 of the carrier 30.

Referring to FIG. 6C, the copper wire 11 is thermally pressed and broken on the bonding pad 30 by the soldering pin 50 to form a tail end 14 (ie, the second end). The solder pin 50 (or the composite solder pin 70) will then return to the position of the 3C, 4C or 5A view to recreate the indium containing solder ball 12 on the front end 111 of the copper wire 11.

The present invention has been disclosed in its preferred embodiments, and is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

10. . . Wire construction

11. . . Copper wire

111. . . front end

12. . . Indium solder ball

120. . . Indium containing material

121. . . Indium oxide protective layer

13. . . Metal layer

14. . . Tail end

20. . . Wafer

twenty one. . . Pad

30. . . Carrier board

31. . . Solder pad

40. . . Batching tube

41. . . Locating slot

42. . . Laser device

50. . . Solder pin

51. . . Supply hole

60. . . Wire supply unit

61. . . Locating slot

62. . . Heater

70. . . Composite welding pin

71. . . First supply hole

72. . . Second supply hole

80. . . Electronic ignition rod

Fig. 1 is a cross-sectional view showing a wire structure of a semiconductor device according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing a semiconductor device according to an embodiment of the present invention.

3A, 3B, and 3C are schematic views showing the flow of a method of manufacturing a wire structure of a semiconductor device according to an embodiment of the present invention.

4A, 4B and 4C are schematic views showing the flow of a method of manufacturing a wire structure of a semiconductor device according to another embodiment of the present invention.

5A, 5B, and 5C are schematic views showing the flow of a method of manufacturing a wire structure of a semiconductor device according to still another embodiment of the present invention.

6A, 6B, and 6C are schematic views showing the flow of a wire bonding method for a wire structure of a semiconductor device according to an embodiment of the present invention.

10. . . Wire construction

11. . . Copper wire

111. . . front end

12. . . Indium solder ball

121. . . Indium oxide protective layer

13. . . Metal layer

Claims (13)

A wire structure of a semiconductor device, comprising: a copper wire having a front end; and an indium-containing solder ball bonded to the front end of the copper wire, wherein the front end of the copper wire is inserted into the indium-containing solder ball to form a Wire construction. The wire structure of the semiconductor device according to claim 1, wherein the material of the copper wire is selected from pure copper or copper alloy; and the material of the indium-containing solder ball is selected from pure indium, indium silver alloy or indium tin alloy. The wire structure of the semiconductor device of claim 1, wherein a front side of the copper wire and the indium containing ball form a metal layer, the metal layer comprising Cu ₂ In, Cu ₇ In ₃ Or at least one of the intermetallic compounds of Cu ₁₁ In ₉ ; and the thickness of the intermetallic layer is between 0.01 and 1 micron. The wire structure of the semiconductor device according to claim 1, wherein the surface of the indium-containing solder ball has an indium oxide protective layer, and the indium oxide protective layer has a thickness of between 10 and 100 nm. A semiconductor device comprising: a wafer having at least one pad; a carrier having at least one pad, the carrier carrying the wafer; and at least one wire structure each having a copper wire and an indium containing ball The copper wire has a front end and a tail end, and the indium containing solder ball is bonded to the front end of the copper wire; wherein the indium containing solder ball is bonded to the pad of the chip, and the tail end of the copper wire is bonded to the copper wire On the pad of the carrier. The semiconductor device according to claim 5, wherein the material of the copper wire is selected from pure copper or a copper alloy; and the material of the indium-containing solder ball is selected from the group consisting of pure indium, indium silver alloy or indium tin alloy. The semiconductor device of claim 5, wherein a dielectric layer is formed between the front end of the copper wire and the indium containing solder ball, and the metal layer comprises Cu ₂ In, Cu ₇ In ₃ or Cu ₁₁ At least one or more of the intermetallic compounds of In ₉ ; and the thickness of the intermetallic layer is between 0.01 and 1 micron. A method of fabricating a wire structure for a semiconductor device, comprising the steps of: heating an indium containing material to melt it to form an indium containing solder ball; providing a copper wire having a front end; and providing the copper wire with a front end and the Indium solder balls are combined to form a wire structure. The method for manufacturing a wire structure of a semiconductor device according to the invention of claim 8, wherein the step of heating the indium-containing material comprises: preliminarily forming the indium-containing material into a spherical shape, and loading the ball with a dosing tube Indium-containing material; the spherical indium-containing material is outputted from the dispensing tube into a receiving groove; and the spherical indium-containing material in the receiving groove is heated to melt or soften to form the Indium solder balls. The method for manufacturing a wire structure of a semiconductor device according to claim 8, wherein the step of heating the indium-containing material comprises: supplying a linear indium-containing material by using a wire supply unit; and cutting a section of the wire And containing the indium material and placing it in a receiving groove; and heating the linear indium-containing material in the receiving groove to melt or soften the indium-containing solder ball. The method for manufacturing a wire structure of a semiconductor device according to claim 8, wherein the step of heating the indium-containing material comprises: simultaneously supplying the copper wire and a linear indium-containing material by using a composite welding pin; The copper wire and the linear indium-containing material are adjacent to each other; and the linear indium-containing material is heated to melt or soften to form the indium-containing solder ball. The method for manufacturing a wire structure of a semiconductor device according to claim 11, wherein the electronic ignition bar, a laser beam or a heating coil is selected to heat the wire which is exposed outside the composite pin. Indium containing material. The method for manufacturing a wire structure of a semiconductor device according to claim 8, wherein the material of the copper wire is selected from pure copper or a copper alloy; and the material of the indium-containing solder ball is selected from pure indium, indium silver alloy or indium. Tin alloy.