JP2013080818A - Joining material, semiconductor device, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influences of heat generated as joining work or rework is conducted.SOLUTION: A joining material 10 is applied to electrode pads 3 on a circuit board 1 to be formed thereon. The joining material includes an electromagnetic wave absorber 11, a temperature control body 12, a molten metal 13, and an active ingredient 14. When a bump 22 is joined to each electrode pad 3, an electromagnetic wave is radiated. The electromagnetic wave absorber 11 in the joining material 10 generates heat thereby melting the molten metal 13 and a lower part of the bump 22. The bump 22 is joined to each electrode pad 3 in this process. Since the joining material 10 includes the temperature control body 12, excessive temperature increase is suppressed and the temperature increase of regions of the circuit board 1, excluding the electrode pads 3, becomes small.

Description

  The present invention relates to a bonding material, a semiconductor device, and a manufacturing method thereof.

  In recent years, in the manufacturing process of a semiconductor device, a lead-free bonding material is used instead of solder containing lead for bonding between a semiconductor element and a circuit board or between a semiconductor device and a circuit board. As the bonding material, tin, silver, copper, an alloy of tin, bismuth, or the like is used. At the time of bonding, the semiconductor device is carried into a reflow furnace and the entire semiconductor device is heated. As a result, the bonding material is melted and the semiconductor element and the semiconductor device are bonded. Such a bonding material is also used for bonding between semiconductor elements and circuit boards.

  Further, when a semiconductor device or the like is replaced and a semiconductor element or a semiconductor device is replaced, a separation work called rework is performed. In the rework operation, the entire circuit board is heated, and a bonding material for bonding the circuit board and the semiconductor element or semiconductor device is melted and then removed. Furthermore, new semiconductor elements and semiconductor devices are remounted on the circuit board as necessary. Since the entire circuit board is heated during rework, other semiconductor elements that do not need to be replaced and other electronic components such as capacitors and capacitors mounted on the circuit board are also heated. For this reason, when the heat-resistant temperature of other semiconductor elements and electronic components is low, these components may be deteriorated by repeated heating.

  Therefore, conventionally, in a configuration in which solder is used as the bonding material, an electric resistor is disposed so as to cover the solder, and during rework, the electric resistor is energized to generate heat, and the solder covered with the electric resistor is removed. It was melted. Further, an electromagnetic wave absorber is attached so as to cover the solder, and the electromagnetic wave absorber is heated by irradiating the electromagnetic wave, and the solder covered with the electromagnetic wave absorber is melted. This makes it possible to heat only specific solder during rework.

JP2000-183513

However, although the temperature rise of the entire circuit board can be suppressed, it has been difficult to suppress the influence of heat on the semiconductor element and the circuit board at the time of soldering. For example, when used in a reflow furnace for bonding semiconductor elements, the circuit board is also heated to near the melting point of the bonding material, so that the circuit board is affected by heat. In particular, in recent years, the melting point of the bonding material has been increased for the purpose of improving the reliability of bonding, and the difference between the melting point of the bonding material and the heat resistance temperature of the circuit board has been reduced. For this reason, the circuit board is easily affected by heat. Furthermore, when mounting a plurality of semiconductor elements and circuit components having different sizes on one circuit board, the reflow temperature is determined in accordance with the heat capacity of the largest semiconductor element or circuit component. There is a possibility of heating more than necessary.
This invention is made | formed in view of such a situation, and it aims at reducing the influence of the heat | fever which generate | occur | produces with the joining operation | work by a joining material and a rework operation | work.

According to one aspect of the embodiment, an electromagnetic wave absorber that is disposed and used on an electrode pad and generates heat by absorbing electromagnetic waves, a temperature control body that suppresses temperature rise, and when the electromagnetic wave absorber is irradiated with electromagnetic waves There is provided a joining material comprising a molten metal that melts with heat generated in the active material and an active component.

  According to another aspect of the embodiment, an electrode pad formed above the substrate, a metal bump electrically bonded to the electrode pad, and disposed around the bump to absorb electromagnetic waves. Thus, there is provided a semiconductor device having an electromagnetic wave absorber that generates heat, a temperature control body that suppresses a rise in temperature, and a coating layer containing an active component.

  Further, according to another aspect of the embodiment, on the electrode pad formed above the substrate, the molten metal, the electromagnetic wave absorber that absorbs electromagnetic waves and generates heat, the temperature control body that suppresses the temperature rise, the activity A step of disposing a bonding material containing components; a step of placing a metal bump on the bonding material; and heating the bonding material by irradiating the bonding material with electromagnetic waves, and the molten metal and the And a step of melting at least a part of the bump.

  Since the molten metal can be melted by irradiating electromagnetic waves to raise the temperature of the electromagnetic wave absorber, the temperature rise of other parts can be reduced during the joining work and the rework work.

FIG. 1A is a cross-sectional view (part 1) illustrating an example of a manufacturing process of a semiconductor device according to an embodiment of the present invention. FIG. 1B is a cross-sectional view (part 2) illustrating the example of the manufacturing process of the semiconductor device according to the embodiment of the present invention. FIG. 1C is a cross-sectional view (part 3) illustrating an example of the manufacturing process of the semiconductor device according to the embodiment of the present invention. FIG. 1D is a sectional view (No. 4) showing an example of the manufacturing process of the semiconductor device according to the embodiment of the present invention. FIG. 1E is a cross-sectional view (part 5) illustrating the example of the manufacturing process of the semiconductor device according to the embodiment of the present invention. FIG. 2 is a diagram showing an example of a result obtained by examining the temperature rise of the bonding material during electromagnetic wave irradiation by changing the content of the temperature control body in the bonding material according to the embodiment of the present invention. FIG. 3 is a diagram showing an example of a rework process of the semiconductor device according to the embodiment of the present invention. FIG. 4 is a diagram illustrating an example of a manufacturing process of a semiconductor device according to a modification of the embodiment of the present invention.

The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
The foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to limit the invention.

First, the manufacturing process of the semiconductor device of this embodiment will be described.
First, a process until obtaining the cross-sectional structure of FIG. 1A will be described. First, a printing mask 5 is positioned and arranged on the circuit board 1. The circuit board 1 is produced, for example, by forming a conductor pattern including electrode pads 3 on a resin or ceramic substrate 2. The electrode pad 3 is electrically connected to a circuit not shown. The conductor pattern is formed by, for example, printing. Also, the conductor pattern is
The conductive layer formed uniformly on the substrate 2 may be formed by patterning with a chemical solution or the like. A plurality of through holes 6 are formed in the mask 5 arranged on the circuit board 1 in accordance with the positions where the electrode pads 3 are formed. The size and shape of the through hole 6 are substantially equal to the size and shape of the electrode pad 3. Therefore, when the mask 5 is overlaid on the circuit board 1, the electrode pad 3 is exposed from the through hole 6.

  Next, the bonding material 10 is printed on the circuit board 1 using the mask 5 so as to show a partially enlarged cross-sectional structure in FIG. 1B. As a result, the bonding material 10 is filled in the through holes 6. Thereafter, when the mask 5 is removed, the bonding material 10 is disposed on the electrode pad 3 of the circuit board 1 so as to overlap.

Here, the bonding material 10 includes an electromagnetic wave absorber 11, a temperature controller 12, a molten metal 13, and an active component 14.
The electromagnetic wave absorber 11 is made of a material that generates heat by efficiently absorbing electromagnetic waves. For example, SiC, BaTiO ₃ , MnO _2, or the like is used.
The temperature control body 12 is made of a material that absorbs less electromagnetic waves than the electromagnetic wave absorber 11 but has very high temperature controllability. For example, Al ₂ O ₃ is used. The temperature controllability refers to, for example, a characteristic that allows the temperature of the bonding material 10 to be kept within a predetermined temperature without becoming too high.
The molten metal 13 includes metals other than lead having a melting point of 350 ° C. or less, such as Sn, In, Sn—Ag, Sn—Ag—Cu, Sn—Cu, Sn—Pb, Sn—Bi, Sn—Zn, Sn-Au or the like is used.

  The active component 15 is a material that facilitates the joining with the molten metal 13 by activating the molten metal 13 at the time of joining. The active component 15 is rosin represented by aniline hydrochloride, hydrazine hydrochloride, cetylpyridine bromide, hydrochloric acid, fluoride. Inorganic acids such as hydroacid, lithium fluoride, potassium fluoride, fluorides such as sodium fluoride, lithium chloride, potassium chloride, chlorides such as sodium chloride, lithium bromide, potassium bromide, Bromides represented by sodium bromide, organic acids represented by lactic acid, citric acid and oleic acid, organic halogen compounds represented by glutamic acid hydrochloride and aniline hydrochloride are used.

  The electromagnetic wave absorber 11 and the temperature control body 12 have a content of 10 wt% to 90 wt% with respect to the bonding material 10. This is because if the content ratio of the electromagnetic wave absorber 11 and the temperature control body 12 to the bonding material 10 is 5 wt%, the temperature rise of the bonding material 10 becomes extremely slow, and the mounting process takes too much time. Further, when the content ratio is 10 wt%, the temperature rise of the bonding material 10 becomes moderate, but it is possible to mount a semiconductor chip or a circuit component. On the other hand, when the content ratio is 95 wt%, the amounts of the electromagnetic wave absorber 11 and the temperature controller 12 are too large, and voids are easily generated in the bonding material 10.

Further, the temperature control body 12 is contained in an amount of 50 mol% to 100 mol% with respect to the electromagnetic wave absorber 11. In FIG. 2, the result of having investigated the temperature rise of the joining material 10 at the time of electromagnetic wave irradiation is shown. The horizontal axis represents electromagnetic wave irradiation time, and the vertical axis represents temperature. Line L1 shows the temperature rise of the bonding material 10 containing 40 mol% of the temperature control body 12. The bonding material 10 reached, for example, 400 ° C. by irradiation with electromagnetic waves. At this temperature, it is necessary to consider the thermal effect on the circuit board 1. On the other hand, the line L2 shows the temperature rise of the bonding material 10 containing 50 mol% of the temperature control body 12. The bonding material 10 reached, for example, 350 ° C. by irradiation with electromagnetic waves. This temperature is a temperature at which the molten metal 13 is sufficiently melted even when it is a refractory metal, and is a level at which there is no or little influence on the circuit board 1. Furthermore, the line L3 shows the temperature rise of the bonding material 10 containing 100 mol% of the temperature control body 12. The bonding material 10 reached, for example, 80 ° C. by irradiation with electromagnetic waves. This temperature is a temperature at which the molten metal 13 can be melted when it is a low melting point metal. Furthermore, since the temperature rise is small, it is not necessary to consider the thermal effect on the circuit board 1.

  Thus, from the graph of the temperature rise shown in FIG. 2, it is difficult to heat the electromagnetic wave absorber 11 to a certain temperature or more by adding the temperature control body 12, and the reached temperature increases as the ratio of the temperature control body 12 increases. You can see that it goes down. Therefore, by containing 50% to 100% in a molar ratio with respect to the electromagnetic wave absorber 11, the molten metal 13 can be reliably melted and an increase in ambient temperature can be suppressed low.

  Next, as shown in FIG. 1C, metal bumps 22 attached to the semiconductor element 21 are placed on the bonding material 10. The bumps 22 are bonded to electrode pads 24 arranged on the back surface of the semiconductor element 21. The electrode pad 24 is electrically connected to a semiconductor circuit (not shown). The bumps 22 are preferably manufactured from the same material as the molten metal 13 of the bonding material 10. Examples of the bump material include Sn, In, Sn—Ag, Sn—Ag—Cu, Sn—Cu, Sn—Pb, Sn—Bi, Sn—Zn, and Sn—Au.

  Subsequently, in this state, electromagnetic waves are applied to the entire circuit board 1 from above. The electromagnetic wave absorber 11 absorbs the electromagnetic wave and generates heat. As a result, the temperature of the bonding material 10 increases. When the temperature of the bonding material 10 exceeds the melting point of the molten metal 13, the molten metal 13 is dissolved. On the other hand, since the bump 22 placed on the bonding material 10 is made of the same material as the molten metal 13 or a metal material having the same melting point, the lower region of the bump 22 is heated by the temperature rise of the bonding material 10. And melt.

  As a result, as shown in an enlarged cross section in FIG. 1D, the lower part of the bump 22 dissolves the electrode pad 3 for the cylinder, and the bump 22 is joined to the electrode pad 3. At this time, the molten metal 13 is integrated with the bumps 22 in the bonding material 10. On the other hand, the active component 14 in the bonding material 10 takes in the electromagnetic wave absorber 11 and the temperature control body 12 and covers the periphery of the bump 22. This is because the surface tension of the molten metal 13 is much larger than that of the electromagnetic wave absorber 11, the temperature controller 12, and the active component 14. As a result, the coating layer 26 is formed so as to surround the lower portion of the bump 22 and the electrode pad 3. On the other hand, in the portion where the bonding material 10 is not disposed, for example, the region where the electrode pad 3 of the circuit board 1 is not formed, the electromagnetic wave absorber 11 does not exist. . For this reason, the circuit board 1 is hardly affected by heat.

  As a result, a semiconductor device 30 as shown in FIG. 1E is obtained. In the semiconductor device 30, semiconductor elements 21, 41, 51 and an electronic component 61 are mounted on the electrode pads 3 of the circuit board 1 via bumps 22. The semiconductor element 21 has a semiconductor chip 25 mounted on a substrate 23. The semiconductor element 41 is electrically connected to the electrode pad 3A of the circuit board 1 through a metal bump 22A. The semiconductor element 51 is mounted on the circuit board 1 via metal bumps 22B. The electronic component 61 is, for example, a capacitor, a resistor, a capacitor, or the like. The circuit component 61 is electrically connected to the electrode pad 3C of the circuit board 1 through the metal bump 22C.

  A bonding material 10 is used for bonding the bumps 22A, 22B, 22C and the circuit board 1. For this purpose, a coating layer 26A is formed around the lower portion of the bump 22A. A coating layer 26B is formed around the lower portion of the bump 22B. A coating layer 26C is formed around the lower portion of the bump 22C. Each of the coating layers 26A, 26B, and 26C covers the periphery of the bumps 22A, 22B, and 22C so that the active component 14 takes in the electromagnetic wave absorber 11 and the temperature control body 12. When the bonding material 10 is used for bonding the semiconductor element 21 and the electrode pad 25, the covering layer 26 is formed so as to cover the electrode pad 25 and the bump 22 of the semiconductor element 21.

Here, as an example of the bonding material 10, SiC is used for the electromagnetic wave absorber 11, Al ₂ O ₃ is used for the temperature control body 12, Sn-3.0Ag-0.5Cu is used for the molten metal 13, and citric acid is used for the active component 14. The temperature rise of the circuit board 1 when the semiconductor elements 21, 41, 51 and the circuit component 61 were joined to the circuit board 1 by irradiating electromagnetic waves at a frequency of 2.4 GHz was examined. At this time, the particle size of the electromagnetic wave absorber 11 and the temperature controller 12 was 1 μm, and the particle size of the molten metal 13 was 20 μm. The weight ratios of the electromagnetic wave absorber 11, the temperature controller 12, the molten metal 13, and the active component 14 were 5 wt%, 4 wt%, 81 wt%, and 10 wt%, respectively. By using such a bonding material 10, the temperature reached by the circuit board 1 at the time of bonding was suppressed to about 150 ° C.

  On the other hand, as a comparative example, when the circuit board 1 and the semiconductor element 21 were joined using Sn-Ag-Cu for the bump and cetylpyridine bromide as the active component, the temperature reached by the circuit board 1 was about It became 250 degreeC. From this, when the bonding material 10 of this embodiment is used, the temperature rise of the circuit board 1 can be suppressed, and the thermal influence on the circuit board 1 can be reduced.

Next, a rework method for removing the semiconductor element 21 from the semiconductor device 30 will be described with reference to FIG.
When removing the semiconductor element 21 from the circuit board 1, the mask 71 is used. The mask 71 is manufactured from, for example, a material that does not transmit electromagnetic waves, and a through hole 72 is formed in accordance with the position and size of a component to be joined to the circuit board 1. For this reason, only the electromagnetic wave that has passed through the through hole 72 of the mask 71 is applied to the semiconductor device 30. Thereby, only the coating layer 26 under the semiconductor element 21 is heated, and the coating layers 26 of the other components 41, 51, 61 are not heated. As a result, only the bump 22 joining the semiconductor element 21 to be reworked to the circuit board 1 is heated and melted. As a result, only the semiconductor element 21 can be removed from the circuit board 1. By using the mask 71 at the time of reworking, only the target bonding material can be selectively melted at a pinpoint.

  As described above, since the bonding material 10 including the electromagnetic wave absorber 11 is used in this embodiment, the temperature of the bonding material 10 can be increased only by irradiating the electromagnetic wave. In addition, since the bonding material 10 is disposed between the electrode pad 3 and the bump 22, the semiconductor element 21 and the circuit board 1 can be bonded only by irradiating electromagnetic waves. Since only the bonding material 10 and its periphery can be intensively heated, the influence of heat on other regions of the circuit board 1 and other components 41, 51, 61 can be reduced.

  Further, since the temperature control body 12 is included in the bonding material 10, the temperature of the bonding material 10 does not increase excessively. Furthermore, since the bonding material 10 includes the temperature control body 12, the bonding material 10 can be adjusted to an optimum temperature for bonding the semiconductor element 21 and the like.

  Further, at the time of reworking, only the bonding material 10 and its periphery can be intensively heated and adjusted to an optimum temperature for bonding of the semiconductor element 21 and the like, as in the bonding. Even when the rework target has a larger amount of heat than other parts, the influence of heat on other parts can be minimized. The process using the mask 71 can also be used when the semiconductor element 21 is bonded to the circuit board 1. Only the portion of the bonding material 10 and the bumps 22 exposed in the through holes 72 of the mask 71 can be dissolved, and the influence of heat on other portions can be minimized.

Here, a modified example of the work at the time of rework will be described.
First, the whole circuit board 1 shown in FIG. 1E is irradiated with electromagnetic waves. The electromagnetic wave is absorbed by the electromagnetic wave absorber 11 of the coating layer 26. As a result, the temperature of the coating layer 26 increases. Coating layer 26
This temperature rises to a temperature adjusted by the temperature control body 12 and dissolves the lower portion of the bump 22 surrounded by the coating layer 26. In this state, the semiconductor element 21 is sucked and removed from the circuit board 1 with a probe (not shown) or the like.

  Further, such a manufacturing method using the bonding material 10 can be used for bonding the semiconductor device 30 and another circuit board 81 as shown in FIG. 4A, for example. On the circuit board 81, electrode pads 82 connected to the circuit are formed. On the electrode pad 82, the bonding material 10 is formed by application, for example. An electrode pad 83 connected to a circuit is formed on the lower surface of the semiconductor device 30, and the bump 22 is bonded to the electrode pad 83. In the bonding step, the semiconductor device 30 is placed on the circuit board 81 and then irradiated with electromagnetic waves. The bump 22 is melted by the bonding material 10. As a result, as shown in FIG. 4B, the semiconductor device 30 and the circuit board 81 are bonded. A coating layer 26 is formed around the bumps 22. The rework process for the component 85 (semiconductor device) in which the semiconductor device 30 is mounted on the circuit board 81 can be performed in the same manner as described above. Here, this embodiment can also be used for bonding or reworking of the semiconductor device 30 and another semiconductor device, or bonding or reworking of circuit boards.

  All examples and conditional expressions given here are intended to help the reader understand the inventions and concepts that have contributed to the promotion of technology, and such examples and It is to be construed without being limited to the conditions, and the organization of such examples in the specification is not related to showing the superiority or inferiority of the present invention. While embodiments of the present invention have been described in detail, various changes, substitutions and variations can be made thereto without departing from the spirit and scope of the present invention.

The features of the above embodiment will be added below.
(Supplementary note 1) An electromagnetic wave absorber that is disposed on an electrode pad and generates heat by absorbing electromagnetic waves, a temperature control body that suppresses temperature rise, and heat generated when the electromagnetic wave absorber is irradiated with electromagnetic waves. A joining material comprising a molten metal to be melted and an active ingredient.
(Additional remark 2) The said temperature control body is contained in 50 mol%-100 mol% with respect to the said electromagnetic wave absorber, The joining material of Additional remark 1 characterized by the above-mentioned.
(Additional remark 3) The electrode pad formed above the board | substrate, the metal bump electrically joined to the said electrode pad, the electromagnetic wave absorber which is arrange | positioned around the said bump and absorbs electromagnetic waves, and heat | fever-generates, A semiconductor device comprising: a temperature control body that suppresses an increase in temperature; and a coating layer containing an active component.
(Additional remark 4) The semiconductor device of Additional remark 3 including the semiconductor device which is electrically connected via the said bump on the said electrode pad, and has a semiconductor circuit.
(Supplementary Note 5) On the electrode pad formed above the substrate, a molten metal, an electromagnetic wave absorber that absorbs electromagnetic waves and generates heat, a temperature control body that suppresses temperature rise, and a bonding material including an active component are disposed. A step of placing a metal bump on the bonding material; and irradiating the bonding material with electromagnetic waves to cause the bonding material to generate heat and to melt at least a part of the molten metal and the bump. A method of manufacturing a semiconductor device.
(Appendix 6) An electromagnetic wave absorber which is disposed around a bump bonded to an electrode pad and absorbs electromagnetic waves to generate heat, and a coating layer including a temperature control body which suppresses a rise in temperature, by irradiating electromagnetic waves to the coating layer A method of manufacturing a semiconductor device, wherein the layer is heated to melt at least a part of the bump.
(Appendix 7)
8. The method of manufacturing a semiconductor device according to appendix 7, wherein a mask that partially transmits electromagnetic waves is disposed above the bonding material, and the metal material is melted using the electromagnetic waves transmitted through the mask.

DESCRIPTION OF SYMBOLS 1 Circuit board 3 Electrode pad 10 Joining material 11 Electromagnetic wave absorber 12 Temperature control body 13 Molten metal 14 Active component 21 Semiconductor device 22 Bump 26 Covering layer 30 Semiconductor device 71 Mask

Claims (4)

  An electromagnetic wave absorber that is used by being placed on an electrode pad and absorbs electromagnetic waves to generate heat, a temperature control body that suppresses temperature rise, and a molten metal that is melted by heat generated when the electromagnetic wave absorber is irradiated with electromagnetic waves A bonding material comprising an active ingredient.   The bonding material according to claim 1, wherein the temperature control body is contained in a range of 50 mol% to 100 mol% with respect to the electromagnetic wave absorber. An electrode pad formed above the substrate;
Metal bumps electrically bonded to the electrode pads;
An electromagnetic wave absorber that is disposed around the bump and generates heat by absorbing electromagnetic waves, a temperature control body that suppresses temperature rise, a coating layer containing an active component, and
A semiconductor device comprising: On the electrode pad formed above the substrate, a molten metal, an electromagnetic wave absorber that generates heat by absorbing electromagnetic waves, a temperature controller that suppresses temperature rise, a step of arranging a bonding material containing an active component,
Placing a metal bump on the bonding material;
Heating the bonding material by irradiating the bonding material with electromagnetic waves, and melting at least a part of the molten metal and the bump;
A method of manufacturing a semiconductor device including:

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