Electronic circuit chip, and electronic circuit device and method for manufacturing the same

An insulating layer 12 is formed as a surface layer of electronic circuit chip 10. A conductor interconnect 14 is formed in the insulating layer 12. The conductor interconnect 14 is exposed in the surface of the insulating layer 12. A solder wetting metallic film 16 (a metallic film) is formed on a portion of the conductor interconnect 14 to be exposed in the surface of the insulating layer 12. Typical metallic material (second metallic material) available for composing the solder wetting metallic film 16 includes a material that requires higher free energy for forming an oxide thereof, as compared with a free energy required for forming an oxide of the metallic material composing the conductor interconnect 14.

This application is based on Japanese patent application No. 2005-295052, the content of which is incorporated hereinto by reference.

BACKGROUND

1. Technical Field

The present invention relates to an electronic circuit chip, and an electronic circuit device and a method for manufacturing thereof.

2. Related Art

Conventional electronic circuit devices include an electronic circuit device disclosed by, for example, the non-patent document 1 cited below. In an electronic circuit device described thereof, first and second electronic circuit chips are mutually joined. Respective electronic circuit chips include a benzocyclobutene (BCB) resin layer provided as a surface layer in the side of the joined surface and a copper (Cu) pad formed in the BCB resin layer. The Cu pad is exposed in the surface of the BCB resin. The first and second electronic circuit chips are mutually joined by connecting the Cu pads by a thermo compression-bonding.

SUMMARY OF THE INVENTION

However, when the metal juncture between Cu members is employed in this way, a thermo compression bonding process conducted at an elevated temperature for longer time is required, in order to obtain sufficient metal juncture. Actually, the non-patent document 1 discloses that a heating process at a temperature of equal to or higher than 350 degree C. for equal to or longer than 90 minutes is required. Therefore, there is a narrower choice for selecting materials for composing the electronic circuit chip (insulating material, for example). This is because a range of the available materials is limited to materials that exhibits a resistance to an elevated temperature environment in the thermo compression bonding process.

On the contrary, if a solder layer is formed in advance in a surface layer of one of the electronic circuit chips and then a Cu pad of the other electronic circuit chip is connected to the solder layer, the juncture can be formed at a lower temperature for shorter time. However, in such case, a problem may be caused in the connection reliability between Cu and solder.

The present inventors have eagerly investigated on such issue, and have found that a part of the reason for reducing the connection reliability between Cu and solder is that a wettability of Cu for solder is reduced by a natural oxidation of a surface of Cu.

According to the present invention, there is provided an electronic circuit chip having an insulating layer provided as a surface layer, comprising a patterned conductor, provided in the insulating layer and exposed in a surface of the insulating layer; and a metallic film, provided on a portion of the patterned conductor and composed of a second metallic material, which requires higher free energy for forming an oxide than a free energy that is required by a first metallic material for forming an oxide, the first metallic material composing the patterned conductor.

In this electronic circuit chip, a metallic film is provided on the patterned conductor. The metallic film is composed of a metallic material, which requires higher free energy for forming an oxide thereof than a free energy that is required for forming an oxide of another metallic material, which composes the patterned conductor. More specifically, the metallic film has a property that it is more difficult to be oxidized than the patterned conductor. Therefore, when this electronic circuit chip is joined to another electronic circuit chip having solder provided on the surface thereof, the above-described metallic film may be interposed therebetween, so that an improved connection reliability is obtained between the patterned conductor and the solder.

According to the present invention, there is also provided an electronic circuit device, comprising a first electronic circuit chip, which is the electronic circuit chip according to the present invention; and a second electronic circuit chip, which is joined to the first electronic circuit chip in the side of the surface layer, wherein the second electronic circuit chip includes a resin layer provided in a surface layer in the side of the first electronic circuit chip; and a solder layer, provided in the resin layer and exposed in a surface of the resin layer, and wherein the first and second electronic circuit chips are joined to each other by connecting the metallic film and the solder layer.

In this electronic circuit device, the patterned conductor of the first electronic circuit chip is connected to the solder layer of the second electronic circuit chip via the above-described metallic film. This provides an improved connection reliability between the patterned conductor and the solder layer.

According to the present invention, there is also provided a method for manufacturing an electronic circuit device, comprising (a) preparing a first electronic circuit chip, which is the electronic circuit chip according to the present invention; (b) preparing a second electronic circuit chip that includes a resin layer provided in a surface layer and a solder layer provided in the resin layer and exposed in a surface of the resin layer; and (c) connecting the metallic film of the first electronic circuit chip and the solder layer of the second electronic circuit chip by heating the solder layer, while the solder layer is pressed against the metallic film.

In this method for manufacturing an electronic circuit device, the patterned conductor of the first electronic circuit chip is connected to the solder layer of the second electronic circuit chip via the above-described metallic film. This provides an improved connection reliability between the patterned conductor and the solder layer.

According to the present invention, an electronic circuit chip, which is capable of exhibiting an improved connection reliability with other electronic circuit chips, and an electronic circuit device including the electronic circuit chip and a method for manufacturing thereof are achieved.

DETAILED DESCRIPTION

Preferable embodiments for illustrating an electronic circuit chip and an electronic circuit device according to the present invention, and a method for manufacturing thereof, will be described in detail, in reference to the annexed figures. In all figures, identical numeral is assigned to an element commonly appeared in the figures, and the detailed description thereof will not be presented.

FIG. 1is a cross-sectional view, illustrating an embodiment of an electronic circuit device according to the present invention. An electronic circuit device1includes an electronic circuit chip10(first electronic circuit chip) and an electronic circuit chip20(second electronic circuit chip).

The electronic circuit chip10is an interconnect member. More specifically, the electronic circuit chip10includes a conductor interconnect14(patterned conductor), and meanwhile includes no semiconductor element. In the present embodiment, in particular, the electronic circuit chip10has a multiple-layered interconnect structure. The conductor interconnects14, which are respectively formed in adjacent layers, are mutually connected by a via plug15. In addition, an external electrode pad19is formed on the conductor interconnect14of the lowermost layer. A solder bump32, serving as an external electrode terminal, is connected to the external electrode pad19.

The electronic circuit chip20, includes a semiconductor chip22, an adhesive resin layer24(resin layer) and conductor electrodes28. The semiconductor chip22is, for example, large scale integrated circuit (LSI) chip. Side surfaces of such electronic circuit chip20are covered with an encapsulating resin34. In addition to above, both sides of the side surfaces and the top surface of the electronic circuit chip20(back surface of semiconductor chip22) may be covered with the encapsulating resin34.

FIG. 2is a cross-sectional view, illustrating a portion of the electronic circuit chip10. The configuration of the electronic circuit chip10will be further described in detail, in reference toFIG. 2. An insulating layer12is formed as a surface layer of the electronic circuit chip10. A conductor interconnect14is formed in the insulating layer12. The conductor interconnect14is exposed in the surface of the insulating layer12. More specifically, the whole side surface of the conductor interconnect14provided in the insulating layer12is covered with the insulating layer12, and meanwhile, the whole top surface of the conductor interconnect14is exposed in the surface of the insulating layer12. Here, “the top surface of the conductor interconnect14is exposed in the surface of the insulating layer12” means that the top surface is not covered with the insulating layer12, regardless of whether or not the top surface is exposed outside. Typical metallic material (first metallic material) for composing the conductor interconnect14includes, for example, copper (Cu), nickel (Ni) and aluminum (Al).

A solder wetting metallic film16(metallic film) is formed on a portion of the conductor interconnect14exposed in the surface of the insulating layer12. Typical metallic material (second metallic material) available for composing the solder wetting metallic film16includes a material that requires higher free energy for forming an oxide thereof, as compared with a free energy required for forming an oxide of the above-described first metallic material. Typical second metallic material includes, for example, gold (Au), silver (Ag), platinum (Pt) and palladium (Pd). A metal oxide film18is formed on a region where no solder wetting metallic film16is provided in the exposed region on the conductor interconnect14, which is exposed on the surface of the insulating layer12. The metal oxide film18is composed of an oxide of the above-described first metallic material.

FIG. 3is a cross-sectional view, illustrating a portion of the electronic circuit chip20. The configuration of the electronic circuit chip20will be further described in detail, in reference toFIG. 3. An adhesive resin layer24is formed on one side of the semiconductor chip22. This provides a configuration of the electronic circuit chip20, in which an adhesive resin layer24is provided as a surface layer in the side thereof facing the electronic circuit chip10. Typical resin available for composing the adhesive resin layer24may be, for example, a thermoplastic resin or a partially cured (B-stage) thermosetting resin. Typical examples for the former and the latter resins may be polyimide resin and benzocyclobutene (BCB) resin, respectively.

A conductor electrode28is formed in the adhesive resin layer24. The conductor electrode28is composed of a conductor layer26and a solder layer27. The solder layer27is formed on one end surface of the conductor layer26, and another end of the conductor layer26is connected to the semiconductor chip22. The solder layer27is exposed in the surface of the adhesive resin layer24.

Typical solder material composing the solder layer27may include tin (Sn), tin-silver (SnAg), tin-copper (SnCu) and tin-silver-copper (SnAgCu). In addition to above, the conductor material available for composing the conductor layer26may be a material, which exhibits higher melting point than that of the solder material composing the solder layer27. Typical conductor material may be, for example, Cu or Ni. In addition to above, the conductor layer26may have a multiple-layered structure of Cu and Ni.

FIG. 4is a cross-sectional view, illustrating a portion of the electronic circuit device1. A configuration of a juncture between the electronic circuit chips10and20in the electronic circuit device1will be described in reference toFIG. 4. The electronic circuit chips10and20are mutually joined by connecting the solder wetting metallic film16of the electronic circuit chip10and the solder layer27of the electronic circuit chip20(seeFIG. 3). The solder wetting metallic film16and the solder layer27compose an alloy layer30. The alloy layer30includes at least metallic element that composes the solder wetting metallic film16and metallic element that composes the solder layer27. For example, when material composing the conductor interconnect14, the solder wetting metallic film16, the conductor layer26and the solder layer27are Cu, Au, Cu and SnAg, respectively, the alloy layer30serves as an alloy-diffusion layer containing Cu, Sn and Au. In addition, in the joined surface between the electronic circuit chips10and20, the metal oxide film18of the electronic circuit chip10is connected to the adhesive resin layer24of the electronic circuit chip20.

An example of a method for manufacturing the electronic circuit device1will be described as an exemplary implementation of a manufacture of an electronic circuit device according to the present invention, in reference toFIG. 5AtoFIG. 12. By summarizing the process, the process for manufacturing the electronic circuit device includes: preparing the electronic circuit chip10; preparing the electronic circuit chip20; and connecting the solder wetting metallic film16of the electronic circuit chip10and the solder layer27of the electronic circuit chip20by heating the solder layer27, while the solder layer27is pressed against the solder wetting metallic film16. In addition to above, the operation of preparing the electronic circuit chip10and the operation of preparing the electronic circuit chip20are carried out in an arbitrary sequential order.

First of all, a Cu film92is formed on a silicon wafer90that serves as a support substrate by a process such as a sputter process or the like (FIG. 5A). Next, an external electrode pad19is formed on the Cu film92by employing a photolithographic process and a plating process (FIG. 5B). Subsequently, an insulating resin layer94is formed on the Cu film92so as to cover the external electrode pad19. Thereafter, a top surface of the external electrode pad19is exposed by a planarization process such as a chemical mechanical polishing (CMP) process, a grinding process and a cutting process (FIG. 6A). Various types of resins such as polyimide resin, epoxy resin may be employed for an insulating resin composing the insulating resin layer94.

Further, the conductor interconnects14(lower conductor interconnects14inFIG. 1), which are respectively connected to the external electrode pads19, are formed on the insulating resin layer94, and then, via plugs15respectively connected to the conductor interconnects14are formed on this conductor interconnect14(FIG. 6B). Subsequently, an insulating resin layer95is formed on the insulating resin layer94, so as to cover the conductor interconnects14and the via plugs15. Thereafter, top surfaces of via plugs15are exposed by the above-described planarization process (FIG. 7A). Next, the conductor interconnects14(upper conductor interconnect14inFIG. 1) are formed on the insulating resin layer95(FIG. 7B).

Subsequently, an insulating resin layer (insulating layer12) is formed to cover the conductor interconnect14, and then, a top surface of the insulating layer12is exposed by the above-described planarization process (FIG. 8A). Next, a resist layer96is formed on the insulating layer12except the portions for forming the solder wetting metallic film16(FIG. 8B). Typical process for forming thereof may include a photolithographic process employing a photo resist and a printing process for printing a resist.

Thereafter, the solder wetting metallic films16are formed on the conductor interconnects14exposed in apertures of the resist layer96by a process such as an electrolytic plating process or electroless plating process (FIG. 9A). Next, an oxygen (O2) plasma-processing or the like is conducted after the resist layer96is removed (FIG.9B). In this case, a native oxide film (metal oxide film18) is formed on portions of the surface of the conductor interconnect14, where no solder wetting metallic film16is formed (FIG. 10A). Such native oxide film can be easily formed by simply leaving the circuit device within atmospheric air without conducting particular plasma-processing. As described above, the electronic circuit chip10is obtained.

Next, the electronic circuit chip10is joined to the electronic circuit chip20, which has been prepared in advance. In this operation for joining these circuits, as described above, the solder wetting metallic film16of the electronic circuit chip10is connected to the solder layer27of the electronic circuit chip20by heating the solder layer27, while the solder layer27is pressed against the solder wetting metallic film16. Having such procedure, the electronic circuit chips10and20are mutually joined (FIG. 10B).

Further, the top surface of the electronic circuit chip10having the electronic circuit chip20mounted thereon is encapsulated with an encapsulating resin34(FIG. 11A). In this case, a back surface of the semiconductor chip22may be exposed, or may not be exposed. Typical encapsulating process available in the present embodiment may include a molding process, a printing process, a potting process and the like. Next, the silicon wafer90is removed from the electronic circuit chip10(FIG. 11B). Thereafter, the Cu film92remaining on the electronic circuit chip10is removed by an etch process (FIG. 12). Subsequently, the solder bump32is joined to the exposed upper surface of the external electrode pad19of the electronic circuit chip10, and then a dividing operation of the wafer is carried out by a process such as a dicing process and the like. As described above, the electronic circuit device1shown inFIG. 1is obtained.

Advantageous effects obtainable by employing the configuration of the present embodiment will be described. In the electronic circuit chip10, the solder wetting metallic film16is provided on the conductor interconnect14. The solder wetting metallic film16is composed of a metallic material, which requires higher free energy for forming an oxide thereof, as compared with a free energy required for forming an oxide of the metallic material composing the conductor interconnect14. More specifically, the solder wetting metallic film16is resistant to being oxidized, as compared with the conductor interconnect14. Therefore, a reduction in the wettability of the solder wetting metallic film16against solder, which is caused because the solder wetting metallic film16is oxidized, can be inhibited. Therefore, when the electronic circuit chip10is joined to another electronic circuit chip having solder provided on the surface thereof (electronic circuit chip20in the present embodiment), the solder wetting metallic film16may be interposed between the conductor interconnect14and solder, so that an improved connection reliability would be obtained. Thus, the electronic circuit chip10, which is capable of exhibiting an improved connection reliability with other electronic circuit chips, can be achieved. In addition to above, Au, Ag, Pt or Pd may be preferably employed for a material of the solder wetting metallic film16.

Actually in the present embodiment, the conductor interconnect14of the electronic circuit chip10is connected to the solder layer27of the electronic circuit chip20via the solder wetting metallic film16. This provides an improved connection reliability between the conductor interconnect14and the solder layer27.

Further, in the present embodiment, an injection of an underfill resin in the spacings between the electronic circuit chip10and the electronic circuit chip20or a formation of a solder resist film on the electronic circuit chip10are not necessary. Consequently, the configuration is suitable for a reduction in a connection density between both chips.

The metal oxide film18is formed on a region of the conductor interconnect14, where no solder wetting metallic film16is provided. In general, wettability of an oxide of a metal against resins is higher than that of the metal itself. Therefore, an existence of the metal oxide film18therebetween provides an improved connection reliability between the conductor interconnect14and the adhesive resin layer24. This configuration provides further improved connection reliability between the electronic circuit chip10and the electronic circuit chip20. However, providing the metal oxide film18is not essential.

As a patterned conductor of the electronic circuit chip10, an interconnect of the electronic circuit chip10is employed. As such, by utilizing an existing configuration as a patterned conductor, the electronic circuit chip10provided with a patterned conductor can be obtained, without causing an increase in number of manufacturing process operations. Meanwhile, Cu, Ni or Al, which is generally employed as an interconnect material, has a nature of being easily naturally oxidized. Therefore, when these metals are directly connected with solder, better connection reliability can not be obtained, as described above. Therefore, in such case, the electronic circuit chip10having the solder wetting metallic film16provided on the conductor interconnect14is particularly useful. However, it is not essential to employ an interconnect for a patterned conductor of the electronic circuit chip10.

In the electronic circuit device1, the alloy layer30, which contains metallic elements composing the solder wetting metallic film16and the solder layer27, respectively, is formed. This configuration provides considerably firm juncture between the electronic circuit chip10and the electronic circuit chip20.

The conductor electrode28is composed of the conductor layer26and the solder layer27formed thereon. If the conductor electrode28is composed of only the solder layer27, the whole conductor electrode28may be possibly melted when the electronic circuit chip20is joined to the electronic circuit chip10, so that a height of the conductor electrode28could be considerably changed. On the contrary, in the present embodiment, the conductor layer26having higher melting point than the solder layer27is provided for serving as a base of the conductor electrode28. Consequently, only a portion of the conductor electrode28(portion corresponding to solder layer27) is melted when the electronic circuit chip20is joined to the electronic circuit chip10, so that variation in height of the conductor electrode28would be reduced. However, the conductor electrode28may be composed of only the solder layer27. In addition to above, Cu or Ni may preferably be employed as a material of the conductor layer26. In addition, Sn, SnAg, SnCu or SnAgCu may be preferably employed as a material of the solder layer27.

A thermoplastic resin or a partially cured thermosetting resin may be preferably employed for a material of the adhesive resin layer24.

It is not intended that the electronic circuit chip and method for manufacturing the electronic circuit device according to the present invention is limited to the configurations illustrated in the above-described embodiments, and thus various modifications thereof are available. For example, in the exemplary implement of the above-described embodiment, only one of the first and the second electronic circuit chips includes the semiconductor chip and the other is the interconnect member. Nevertheless, both of the first and the second electronic circuit chips may include a semiconductor chip, as shown inFIG. 13, or may be an interconnect member, as shown inFIG. 14.

InFIG. 13, electronic circuit chips50and20are provided, serving as the first and the second electronic circuit chips, respectively. Configuration of the electronic circuit chip20is the same as what has been described in reference toFIG. 1andFIG. 3. The electronic circuit chip50includes a semiconductor chip51. In addition, an insulating layer52is formed as a surface layer of the electronic circuit chip50. In the insulating layer52, a patterned conductor54that is exposed in the surface of the insulating layer52is formed. Further, on a portion of the patterned conductor54is formed a metallic film (not shown), which requires higher free energy for forming an oxide thereof, as compared with a free energy required for forming an oxide of the metallic material for composing the patterned conductor54. This metallic film forms an alloy layer60in cooperation with the solder layer27of the electronic circuit chip20.

In addition, the electronic circuit chip20is covered with the encapsulating resin34. In the encapsulating resin34, conductor posts62extending through the encapsulating resin34are formed. One end of the conductor post62is connected to the patterned conductor54, and the other end thereof is connected to the solder bump64. In addition to above, another semiconductor chip may be deposited on the semiconductor chip22and/or the semiconductor chip51. In such case, a through-hole via may be formed in the semiconductor chips22and51, thereby providing an electrical connection between the semiconductor chips.

InFIG. 14, electronic circuit chips10and70are provided, serving as the first and the second electronic circuit chips, respectively. Structure of the electronic circuit chip10is the same as described in reference toFIG. 1andFIG. 2. Electronic circuit chip70is an interconnect member. An adhesive resin layer74is formed as a surface layer of the electronic circuit chip70. In the adhesive resin layer74, a solder layer (not shown) exposed in the surface of the adhesive resin layer74is formed. This solder layer forms an alloy layer80in cooperation with the solder wetting metallic film16of the electronic circuit chip10.

In addition, the electronic circuit chip70has multiple-layered interconnect structure, and the conductor interconnects72, which are formed in adjacent layers, respectively, are mutually connected through a via plug73. Further, a back surface of the electronic circuit chip70(i.e., surface in the side opposing to the joined surface with the electronic circuit chip10) is provided with exposed electrode pads79, one end of which is connected to the conductor interconnect72. The electrode pad79serves as a pad for connecting the semiconductor chip to the electronic circuit chip70. According to the electronic circuit device having such structure, one interconnect member, which includes fine interconnect structure, and another interconnect member, which is desirable to be manufactured at lower cost with larger design rule, may be separately manufactured, and then the separately manufactured interconnect members may be joined together.