Patent Grant
9536857
This application is based upon and claims the benefit of prior Japanese Patent Application No. 2015-166794 filed on Aug. 26, 2015, the entire contents of which are incorporated herein by reference.
An embodiment relates to a heating header of a semiconductor mounting apparatus and a bonding method for a semiconductor.
As processors and memories to be used in servers and the like, a laminated semiconductor chip in which a plurality of semiconductor chips are laminated is sometimes used for enhancement of performance. As illustrated in
As illustrated in
[Patent document 1] Japanese Laid-open Patent Publication No. 2000-332390
[Patent document 2] Japanese Laid-open Patent Publication No. 2011-66027
[Patent document 3] Japanese Laid-open Patent Publication No. 2015-18897
According to an aspect of the application, a heating header of a semiconductor mounting apparatus includes: a first material; and a second material, the second material being bonded to the first material and coming into contact with a first semiconductor chip when the first semiconductor chip is compressed, wherein a contact surface of the second material with the first semiconductor chip is a curved surface that is convex toward the first semiconductor chip side, and the contact surface of the second material with the first semiconductor chip becomes a planar surface when each temperature of the first material and the second material reaches a melting temperature of a solder that is formed between a first terminal of the first semiconductor chip and a second terminal of a second semiconductor chip.
According to an aspect of the application, a bonding method for a semiconductor includes: forming a first solder on each of a plurality of first terminals formed on a first semiconductor chip; forming a second solder on each of a plurality of second terminals formed on a second semiconductor chip; forming a resin on the second semiconductor chip such that the resin covers the second terminal and the second solder; placing the first semiconductor chip on the resin such that the plurality of first terminals face the plurality of second terminals; making a second material of a heating header contact with the first semiconductor chip, the heating header including a first material and the second material, the second material being bonded to the first material; and heating and compressing the first semiconductor chip to bond the first solder and the second solder, wherein a contact surface of the second material with the first semiconductor chip is a curved surface that is convex toward the first semiconductor chip side, and the contact surface of the second material with the first semiconductor chip becomes a planar surface when each temperature of the first material and the second material reaches a melting temperature of the first solder and the second solder in the bonding.
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.
The heating by the heating header 201 produces a temperature difference between an upper portion (the side of the heating header 201) of the semiconductor chip 101A and a lower portion (the side of the terminals 102A) of the semiconductor chip 101A. Therefore, the thermal expansion at the upper portion of the semiconductor chip 101A is larger than the thermal expansion at the lower portion of the semiconductor chip 101A, and a warp appears on the semiconductor chip 101A. For bonding the terminals 102A of the semiconductor chip 101A and the terminals 102B of the semiconductor chip 1016, it is desirable to suppress the warp amount of the semiconductor chip 101A to 5 μm or less.
In the case where the external size of the chip is 20 mm square or greater, the warp amount of the semiconductor chip 101A sometimes exceeds 5 μm. Further, by the resistance of the reinforcement resin 104 interposed between the semiconductor chip 101A and the semiconductor chip 1016, it is sometimes impossible to push and penetrate the reinforcement resin 104. Therefore, there is a possibility that terminals 102A formed at a central portion of the semiconductor chip 101A and terminals 102B formed at a central portion of the semiconductor chip 1016 are not bonded as illustrated in
Hereinafter, an embodiment will be described with reference to the drawings. The constitution of the embodiment is an example, and the present invention is not limited to the constitution of the embodiment.
The heater 22 is a heating mechanism, and heats the materials 31, 31. The materials 31, 32, for example, are metal materials, alloy materials or ceramic materials. The materials 31, 32 have a good thermal conductivity. The material 31 and the material 32 are bonded, for example, by roll bonding. The thermal expansion rate (thermal expansion coefficient) of the material 31 is different from the thermal expansion rate of the material 32, and the thermal expansion rate of the material 31 is higher than the thermal expansion rate of the material 32. Among the surfaces of the material 31, the opposite surface (S1 in
For example, the material 32 may be formed by pouring a ceramic material into a mold and sintering the ceramic material. For example, the material 32 may be formed by the turning processing or milling processing of a flat plate shaped metal material, a flat plate shaped alloy material or a flat plate shaped ceramic material.
A mounting flow according to the embodiment will be described with reference to
Next, as illustrated in
Subsequently, as illustrated in
In the above description, an example in which after the step illustrated in
Next, as illustrated in
Since the contact surface of the material 32 with the semiconductor chip 41 is a curved surface that is convex toward the side of the semiconductor chip 41, the material 32 is pressed against a central portion of the back surface of the semiconductor chip 41. That is, the material 32 contacts with the central portion of the back surface of the semiconductor chip 41. In the state in which the material 32 contacts with the semiconductor chip 41, the heating and compressing of the semiconductor chip 41 is started. The compressing of the semiconductor chip 41 may be started after the heating of the semiconductor chip 41 is started, or the heating of the semiconductor chip 41 may be started after the compressing of the semiconductor chip 41 is started. Thus, the starting time point of the heating of the semiconductor chip 41 may be different from the starting time point of the compressing of the semiconductor chip 41. Further, the heating and compressing of the semiconductor chip 41 may be started at the same time.
The heating temperature of the heater 22 is increased, and thereby the semiconductor chip 41 is heated. That is, the heat generated by the heater 22 is transferred to the materials 31, 32, and thereby the semiconductor chip 41 is heated. Above the heat insulating material 21, a compressing mechanism not illustrated is provided. By the drive of the compressing mechanism, a load is given to the semiconductor chip 41, and the semiconductor chip 41 is compressed.
Since the material 32 contacts with the back surface of the semiconductor chip 41, the temperature of the back surface of the semiconductor chip 41 is higher than the temperature of the circuit surface of the semiconductor chip 41, resulting in a temperature difference between the front and back of the semiconductor chip 41. The material 32 contacts with the central portion of the back surface of the semiconductor chip 41, and the material 32 does not contact with a peripheral portion of the back surface of the semiconductor chip 41. Accordingly, the central portion of the semiconductor chip 41 starts to warp, such that the central portion of the semiconductor chip 41 rises to the side of the heating header 1. However, since the material 32 contacts with the central portion of the back surface of the semiconductor chip 41, the load is concentrated on the central portion of the semiconductor chip 41, and the warp of the central portion of the semiconductor chip 41 is suppressed.
In the above description, after the heating header 1 is pressed against the back surface of the semiconductor chip 41, the heating temperature of the heater 22 is increased, and the heating of the semiconductor chip 41 is started. The embodiment is not limited to the above example, and the heating temperature of the heater 22 may be increased before the heating header 1 is pressed against the back surface of the semiconductor chip 41. In this case, as soon as the material 32 comes into contact with the semiconductor chip 41, the heating of the semiconductor chip 41 is started. Thereafter, the compressing of the semiconductor chip 41 may be started. Thus, the starting time point of the heating of the semiconductor chip 41 may be different from the starting time point of the compressing of the semiconductor chip 41. Further, the starting time point of the heating of the semiconductor chip 41 may be matched with the starting time point of the compressing of the semiconductor chip 41, by starting the compressing of the semiconductor chip 41 as soon as the material 32 comes into contact with the semiconductor chip 41.
The heat is transferred from the semiconductor chip 41 to the reinforcement resin 61 through the terminals 42 and the solders 43. The reinforcement resin 61 is heated, and thereby, the reinforcement resin 61 is softened. In the state in which the reinforcement resin 61 is softened, the semiconductor chip 41 is compressed. Thereby, the terminals 42 and the solders 43 are buried in the reinforcement resin 61, and therewith, the reinforcement resin 61 is pushed out. As illustrated in
The thermal expansion rate of the material 31 is higher than the thermal expansion rate of the material 32, and therefore, when the heating by the heater 22 progresses, the material 31 warps to the side of the material 32 (the side of the semiconductor chip 41). Thereby, the material 32 is deformed from the convex shape to a flat plate shape, and the contact surface of the material 32 with the semiconductor chip 41 becomes a planar surface. Since the contact surface of the material 32 with the semiconductor chip 41 is a planar surface as illustrated in
The progress of the heating by the heater 22 melts the solders 43, 53 formed between the terminals 42 of the semiconductor chip 41 and the terminals 52 of the semiconductor chip 51, so that the solders 43 and the solders 53 are bonded. Further, the terminals 42 and the solders 43 are bonded, and the terminals 52 and the solders 53 are bonded. Since the terminals 42 and the terminals 52 are bonded through the solders 43, 53, the semiconductor chip 41 and the semiconductor chip 51 are mechanically connected, and the semiconductor chip 41 and the semiconductor chip 51 are electrically connected.
The contact surface of the material 32 with the semiconductor chip 41 may be a planar surface at the time point when each temperature of the materials 31, 32 reaches the melting temperature of the solders 43, 53. Further, the contact surface of the material 32 with the semiconductor chip 41 may be a planar surface from a time point before each temperature of the materials 31, 32 reaches the melting temperature of the solders 43, 53 to the time point when each temperature of the materials 31, 32 reaches the melting temperature of the solders 43, 53. Accordingly, when each temperature of the materials 31, 32 reaches the melting temperature of the solders 43, 53 formed between the terminals 42 of the semiconductor chip 41 and the terminals 52 of the semiconductor chip 51, the contact surface of the material 32 with the semiconductor chip 41 becomes a planar surface. The contact surface of the material 32 with the semiconductor chip 41 is a planar surface until the bonding between the terminals 42 and the terminals 52 are completed, and therefore, the occurrence of the imperfect bonding of the terminals 42, 52 is suppressed. By the completion of the bonding between the terminals 42 and the terminals 52, a semiconductor device including the semiconductor chips 41, 51 is produced. The temporary curing of the reinforcement resin 61 is completed at the temperature at which the solders 43, 53 melt.
The external size (the area in planar view) of the material 32 may be equal to the external size (the area in planar view) of the semiconductor chip 41, or the external size of the material 32 may be larger than the external size of the semiconductor chip 41. When the external size of the material 32 is equal to the external size of the semiconductor chip 41 or is larger than the external size of the semiconductor chip 41, the load on the semiconductor chip 41 is easily evened.
The external size of the material 32 may be equal to the size (the area in planar view) of a formation region for the terminals 42 in the semiconductor chip 41, or the external size of the material 32 may be larger than the size of the formation region for the terminals 42 in the semiconductor chip 41. For example, in the case where the plurality of terminals 42 are arranged in a predetermined region on the circuit surface of the semiconductor chip 41, the formation region for the terminals 42 in the semiconductor chip 41 is the size (the area in planar view) of the predetermined region in the semiconductor chip 41. When the external size of the material 32 is equal to the formation region for the terminals 42 in the semiconductor chip 41 or is larger than the formation region for the terminals 42 in the semiconductor chip 41, the load on the plurality of terminals 42 of the semiconductor chip 41 is easily evened.
In a conventional mounting apparatus, for giving an even load to the semiconductor chip 41, it is demanded to give a load of 50 kg/20 mm2 or more to the semiconductor chip 41. In the semiconductor mounting apparatus according to the embodiment, the local loading is performed on the semiconductor chip 41 at the initial stage of the compressing of the semiconductor chip 41, and the even loading is performed on the semiconductor chip 41 at the time of the bonding between the terminals 42 and the terminals 52. Thereby, it is possible to suppress the warp of the semiconductor chip 41, and to bond the terminals 42 and the terminals 52, without giving, to the semiconductor chip 41, a load causing the physical destruction. In the semiconductor mounting apparatus according to the embodiment, it is possible to bond the semiconductor chips 41, 51 of 20 mm square or greater, for example, by compressing the semiconductor chip 41 with a low load of 50 kg/20 mm2 mm or less.
<Example>
In the heating process by the heater 22, after the heating is started, the temperature may be increased in stages. At a first stage (at the time of an ordinary temperature) before the heating is performed, the material 32 contacts with the central portion of the back surface of the semiconductor chip 41, and in this state, the pressing force to the semiconductor chip 41 is concentrated on the central portion of the semiconductor chip 41 (see
At a third stage, the temperature is further increased compared to the second stage. The contact surface of the material 32 with the semiconductor chip 41 is deformed from the convex curved surface to a planar surface, and therefore, in this state, the pressing force concentrated on the central portion of the semiconductor chip 41 is dispersed to the peripheral portion of the semiconductor chip 41 (see
In the case where the semiconductor chip 41 of 20 mm square or greater is mounted on the semiconductor chip 51, it is preferable that the external size of the material 32 be equal to or greater than the external size of the semiconductor chip 41. The materials 31, 32 may be selected based on thermal expansion rate (α) and Young's modulus (E), or the materials 31, 32 may be selected based on thermal expansion rate.
The curvature radius of the convex shape (convex curved surface) of the material 32 at the time of an ordinary temperature is determined such that the contact surface of the material 32 with the semiconductor chip 41 becomes a planar surface at the time of reaching a targeted heating temperature (for example, the melting temperature of the solders 43, 53). The warp amount of the material 31 and the curvature radius of the curved surface of the material 32 depend on the thermal expansion rates, Young's moduli and thicknesses of the selected materials 31, 32. Therefore, the materials 31, 32 are selected and the thicknesses of the materials 31, 32 are determined, such that the material 31 generates a warp amount equivalent to or more than the inter-terminal gap amount (=the pushing amount of the semiconductor chip 41 by the material 31) that appears in the case where the semiconductor chips 41, 51 are mounted by the conventional mounting scheme. In the case where the thicknesses of the materials 31, 32 are too small, there is a possibility that the heat warp action is restrained by the pressing force. On the other hand, in the case where the thicknesses of the materials 31, 32 are too large, there is a possibility that the heat transfer property is poor and the performance of the heating header 1 is impaired. Therefore, it is preferable that each thickness of the materials 31, 32 be 1 mm or greater and 3 mm or less, depending on the selection of the materials 31, 32.
For example, in the case where the semiconductor chips 41, 51 are mounted by the conventional mounting scheme and the warp amount (=inter-terminal gap amount) of the semiconductor chip 41 is 7 μm, it is preferable to select AlN as the material 31 and select SiC as the material 32. Further, as for the initial shape of the material 32 before the heating, it is preferable that the curvature radius R of the material 32 be about 7000 mm. In this case, when each temperature of the materials 31, 32 reaches the melting temperature of the solders 43, 53, the warp amount of the material 32 becomes 7 μm, and the contact surface of the material 32 with the semiconductor chip 41 becomes a planar surface. Accordingly, the pushing amount of the semiconductor chip 41 by the material 32 is 7 μm, and the warp of the semiconductor chip 41 is suppressed.
According to the application, it is possible to suppress the warp of the semiconductor chip and bond the terminals to each other with a low load.
All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiment of the present invention has been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-166794 | Aug 2015 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20030115747 | Schnetzler | Jun 2003 | A1 |
| 20110020983 | Tomura | Jan 2011 | A1 |
| 20150357226 | Liu | Dec 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 2000-332390 | Nov 2000 | JP |
| 2011-066027 | Mar 2011 | JP |
| 2015-018897 | Jan 2015 | JP |
