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Patent Analysis of

Thermally enhanced semiconductor package with thermal additive and process for making the same

Updated Time 12 June 2019

Patent Registration Data

Publication Number

US10153223

Application Number

US15/914538

Application Date

07 March 2018

Publication Date

11 December 2018

Current Assignee

QORVO US, INC.

Original Assignee (Applicant)

QORVO US, INC.

International Classification

H01L23/31,H01L21/56,H01L23/29,H01L23/373

Cooperative Classification

H01L23/3135,H01L21/56,H01L23/3737,H01L23/3121,H01L23/295

Inventor

COSTA, JULIO C.,MAXIM, GEORGE,LEIPOLD, DIRK ROBERT WALTER,SCOTT, BAKER,HATCHER, JR., MERRILL ALBERT,MOBLEY, STEPHEN

Patent Images

This patent contains figures and images illustrating the invention and its embodiment.

US10153223 Thermally enhanced semiconductor package 1 US10153223 Thermally enhanced semiconductor package 2 US10153223 Thermally enhanced semiconductor package 3
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Abstract

The present disclosure relates to a thermally enhanced semiconductor package, which includes a module substrate, a thinned flip chip die over the substrate, a first mold compound component, and a thermally enhanced mold compound component. The first mold compound component resides over the module substrate, surrounds the thinned flip chip die, and extends above an upper surface of the thinned flip chip die to form a cavity over the upper surface of the thinned flip chip die. The thermally enhanced mold compound component includes a lower portion filling a lower region of the cavity and residing over the upper surface of the thinned flip chip die, and an upper portion filling an upper region of the cavity and residing over the lower portion. A first average thermal conductivity of the lower portion is at least 1.2 times greater than a second average thermal conductivity of the upper portion.

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Claims

1. A method comprising:

providing a precursor package including a module substrate, a thinned flip chip die attached to an upper surface of the module substrate, a cavity over the upper surface of the thinned flip chip die, and a first mold compound component, wherein:

the first mold compound component resides over the upper surface of the module substrate, surrounds the thinned flip chip die, extends above the upper surface of the thinned flip chip die and surrounds the cavity; and the cavity includes a lower region and an upper region that resides over the lower region; applying at least one thermal additive throughout the lower region of the cavity and immediately adjacent to the upper surface of the thinned flip chip die, wherein the at least one thermal additive comprises a plurality of particulates; applying a second mold compound in the cavity to fill the lower region and the upper region of the cavity such that the second mold compound is dispersed throughout the plurality of particulates of the at least one thermal additive in the lower region; andcuring the second mold compound to form a thermally enhanced mold compound component, which includes a lower portion filling the lower region of the cavity and an upper portion filling the upper region of the cavity, wherein:

the at least one thermal additive is dispersed throughout the lower portion; and a first average thermal conductivity of the lower portion is at least 1.2 times greater than a second average thermal conductivity of the upper portion.

2. The method of claim 1 wherein the second mold compound is dispersed throughout the plurality of particulates of the at least one thermal additive in the lower region without any air pockets or voids.

3. The method of claim 1 wherein providing the precursor package comprises:

providing a semiconductor package including the module substrate, a flip chip die attached to the upper surface of the module substrate, and the first mold compound component over and surrounding the flip chip die; thinning the first mold compound component down to expose a backside of a silicon handle layer of the flip chip die; and removing substantially the entire silicon handle layer to form the cavity and provide the thinned flip chip die with the upper surface, wherein the upper surface of the thinned flip chip die is exposed to the cavity.

4. The method of claim 3 wherein removing substantially the entire silicon handle layer is provided by an etching process.

5. The method of claim 1 wherein applying the at least one thermal additive throughout the lower region of the cavity is provided by dispensing the at least one thermal additive over the upper surface of the thinned flip chip die and squeegeeing the at least one thermal additive into the lower region of the cavity.

6. The method of claim 5 wherein applying the second mold compound to the cavity is provided by compression molding.

7. The method of claim 1 wherein the at least one thermal additive is formed from boron nitride particulates.

8. The method of claim 1 wherein the at least one thermal additive is formed from one of a group consisting of aluminum nitride, silicon nitride, alumina, beryllium oxide, carbon nanotube, and metamaterials.

9. The method of claim 1 wherein the at least one thermal additive comprises a first thermal additive and a second thermal additive, which are each applied throughout the lower region of the cavity.

10. The method of claim 1 wherein the first mold compound component and the second mold compound component are formed from different materials.

11. The method of claim 1 wherein the first average thermal conductivity is at least 1.2 w/m·k.

12. The method of claim 1 wherein the second average thermal conductivity is at least 0.8 w/m·k.

13. The method of claim 1 wherein the first average thermal conductivity is at least 3 w/m·k.

14. The method of claim 1 wherein the second average thermal conductivity is at least 2.5 w/m·k.

15. The method of claim 1 wherein the lower region is at least 1% of the entire cavity.

16. The method of claim 1 further comprises planarizing an upper surface of the thermally enhanced mold compound component.

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Claim Tree

  • 1
    1. A method comprising:
    • providing a precursor package including a module substrate, a thinned flip chip die attached to an upper surface of the module substrate, a cavity over the upper surface of the thinned flip chip die, and a first mold compound component, wherein: the first mold compound component resides over the upper surface of the module substrate, surrounds the thinned flip chip die, extends above the upper surface of the thinned flip chip die and surrounds the cavity
    • and the cavity includes a lower region and an upper region that resides over the lower region
    • applying at least one thermal additive throughout the lower region of the cavity and immediately adjacent to the upper surface of the thinned flip chip die, wherein the at least one thermal additive comprises a plurality of particulates
    • applying a second mold compound in the cavity to fill the lower region and the upper region of the cavity such that the second mold compound is dispersed throughout the plurality of particulates of the at least one thermal additive in the lower region
    • andcuring the second mold compound to form a thermally enhanced mold compound component, which includes a lower portion filling the lower region of the cavity and an upper portion filling the upper region of the cavity, wherein: the at least one thermal additive is dispersed throughout the lower portion
    • and a first average thermal conductivity of the lower portion is at least 1.2 times greater than a second average thermal conductivity of the upper portion.
    • 2. The method of claim 1 wherein
      • the second mold compound is dispersed throughout the plurality of particulates of the at least one thermal additive in the lower region without any air pockets or voids.
    • 3. The method of claim 1 wherein
      • providing the precursor package comprises:
    • 5. The method of claim 1 wherein
      • applying the at least one thermal additive throughout the lower region of the cavity is provided by dispensing the at least one thermal additive over the upper surface of the thinned flip chip die and squeegeeing the at least one thermal additive into the lower region of the cavity.
    • 7. The method of claim 1 wherein
      • the at least one thermal additive is formed from boron nitride particulates.
    • 8. The method of claim 1 wherein
      • the at least one thermal additive is formed from one of a group consisting of
    • 9. The method of claim 1 wherein
      • the at least one thermal additive comprises
    • 10. The method of claim 1 wherein
      • the first mold compound component and the second mold compound component are formed from different materials.
    • 11. The method of claim 1 wherein
      • the first average thermal conductivity is at least 1.2 w/m·k.
    • 12. The method of claim 1 wherein
      • the second average thermal conductivity is at least 0.8 w/m·k.
    • 13. The method of claim 1 wherein
      • the first average thermal conductivity is at least 3 w/m·k.
    • 14. The method of claim 1 wherein
      • the second average thermal conductivity is at least 2.5 w/m·k.
    • 15. The method of claim 1 wherein
      • the lower region is at least 1% of the entire cavity.
    • 16. The method of claim 1 further comprises
      • planarizing an upper surface of the thermally enhanced mold compound component.
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Description

FIELD OF THE DISCLOSURE

The present disclosure relates to a semiconductor package and a process for making the same, and more particularly to a thermally enhanced semiconductor package, and a process to apply at least one thermal additive into the semiconductor package for enhanced thermal performance.

BACKGROUND

With the current popularity of portable communication devices and developed semiconductor fabrication technology, high speed and high performance transistors are more densely integrated on semiconductor dies. Consequently, the amount of heat generated by the semiconductor dies increases significantly due to the large number of transistors integrated on the semiconductor dies, the large amount of power passing through the transistors, and the high operation speed of the transistors. Accordingly, it is desirable to package the semiconductor dies in a configuration for better heat dissipation.

Flip chip assembly technology is widely utilized in semiconductor packaging due to its preferable solder interconnection between flip chip dies and the laminate, on which the flip chip dies are mounted. The flip chip assembly technology eliminates the space needed for wire bonding and the die surface areas of a package, and essentially reduces the overall size of the package. In addition, the elimination of the wire bonding and implementation of a shorter electrical path from the flip chip dies to the laminate reduces undesired inductance and capacitance.

Further, semiconductor dies with silicon on insulator (SOI) structures are trending due to the low cost of silicon materials, a large scale capacity of wafer production, well-established semiconductor design tools, and well-established semiconductor manufacturing techniques. However, harmonic generations and low resistivity values of the SOI structures severely limit the SOI's usage in radio-frequency (RF) applications. By using SOI structures in RF fabrications, an interface between the silicon handle layer and an adjacent dielectric layer will generate unwanted harmonic and intermodulation products. Such spectrum degradation causes a number of significant system issues, such as unwanted generation of signals in other RF bands, which the system is attempting to avoid.

To accommodate the increased heat generation of high performance dies and to utilize the advantages of flip chip assembly, it is therefore an object of the present disclosure to provide an improved semiconductor package design with flip chip dies in a configuration for better heat dissipation. In addition, there is also a need to eliminate the deleterious effects of harmonic generations and intermodulation distortions.

SUMMARY

The present disclosure relates to a thermally enhanced semiconductor package, and a process for making the same. The disclosed thermally enhanced semiconductor package includes a module substrate, a thinned flip chip die, a first mold compound component, and a thermally enhanced mold compound component. The thinned flip chip die includes a device layer, a number of interconnects extending from a lower surface of the device layer and coupled to an upper surface of the module substrate, and a dielectric layer over an upper surface of the device layer. The first mold compound component resides over the upper surface of the module substrate, surrounds the thinned flip chip die and extends above an upper surface of the thinned flip chip die to form a cavity over the upper surface of the thinned flip chip die. Herein, the cavity includes a lower region and an upper region that resides over the lower region. The thermally enhanced mold compound component includes a lower portion filling the lower region of the cavity and residing over the upper surface of the thinned flip chip die, and an upper portion filling the upper region of the cavity and residing over the lower portion. A first average thermal conductivity of the lower portion is at least 1.2 times greater than a second average thermal conductivity of the upper portion.

According to an exemplary process, a precursor package including a module substrate, a thinned flip chip die attached to an upper surface of the module substrate, a cavity over an upper surface of the thinned flip chip die, and a first mold compound component is provided. Herein, the first mold compound component resides over the upper surface of the module substrate, surrounds the thinned flip chip die, extends above the upper surface of the thinned flip chip die and surrounds the cavity. The cavity includes a lower region and an upper region that resides over the lower region. Next, at least one thermal additive is dispersed throughout the lower region of the cavity and immediately adjacent to the upper surface of the thinned flip chip die, where the at least one thermal additive includes a number of particulates. A second mold compound is then applied in the cavity to fill the lower region and the upper region of the cavity such that the second mold compound is dispersed throughout the number of particulates of the at least one thermal additive in the lower region without any air pockets or voids. Finally, the second mold compound is cured to harden the second mold compound in order to form a thermally enhanced mold compound component, which includes a lower portion with at least one thermal additive filling the lower region of the cavity, and an upper portion filling the upper region of the cavity and residing over the lower portion. A first average thermal conductivity of the lower portion is at least 1.2 times greater than a second average thermal conductivity of the upper portion.

Those skilled in the art will appreciate the scope of the present disclosure and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

FIG. 1 shows an exemplary thermally enhanced semiconductor package according to one embodiment of the present disclosure.

FIGS. 2A-2B show an alternative thermally enhanced semiconductor package according to one embodiment of the present disclosure.

FIGS. 3-8 provide exemplary steps that illustrate a process to fabricate the exemplary thermally enhanced semiconductor package shown in FIG. 1.

It will be understood that for clear illustrations, FIGS. 1-8 may not be drawn to scale.

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

It will be understood that when an element such as a layer, region, or substrate is referred to as being “on” or extending “onto” another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or extending “directly onto” another element, there are no intervening elements present. Likewise, it will be understood that when an element such as a layer, region, or substrate is referred to as being “over” or extending “over” another element, it can be directly over or extend directly over the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly over” or extending “directly over” another element, there are no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present.

Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,”“an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,”“comprising,”“includes,” and/or “including” when used herein specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The present disclosure relates to a thermally enhanced semiconductor package, and a process for making the same. FIG. 1 shows an exemplary thermally enhanced semiconductor package 10 according to one embodiment of the present disclosure. For the purpose of this illustration, the exemplary thermally enhanced semiconductor package 10 includes a module substrate 12, a thinned flip chip die 14, an underfilling layer 16, a first mold compound component 18, and a thermally enhanced mold compound component 20. In different applications, the thermally enhanced semiconductor package 10 may include multiple thinned flip-chip dies.

In detail, the module substrate 12 may be formed from a laminate, a wafer level fan out (WLFO) carrier, a lead frame, a ceramic carrier, or the like. The thinned flip chip die 14 includes a device layer 22, a number of interconnects 24 extending from a lower surface of the device layer 22 and coupled to an upper surface of the module substrate 12, a dielectric layer 26 over an upper surface of the device layer 22, and essentially no silicon handle layer (not shown) over the dielectric layer 26. Herein, essentially no silicon handle layer over the dielectric layer 26 refers to at most 2 μm silicon handle layer over the dielectric layer 26. In some applications, an upper surface of the thinned flip chip die 14 is an upper surface of the dielectric layer 26. For other cases, the upper surface of the thinned flip chip die 14 is an upper surface of the thin silicon handle layer (not shown). The device layer 22 with a thickness between 10 nm and 20000 nm may be formed of silicon oxide, gallium arsenide, gallium nitride, silicon germanium, or the like, and the dielectric layer 26 with a thickness between 10 nm and 20000 nm may be formed of silicon oxide, silicon nitride, or aluminum nitride. The interconnects 24 with a height between 5 μm and 200 μm may be copper pillar bumps, solder ball bumps, or the like.

The underfilling layer 16 resides over the upper surface of the module substrate 12, such that the underfilling layer 16 encapsulates the interconnects 24 and underfills the thinned flip chip die 14 between the lower surface of the device layer 22 and the upper surface of the module substrate 12. The underfilling layer 16 may be formed from conventional polymeric compounds, which serve to mitigate the stress effects caused by Coefficient of Thermal Expansion (CTE) mismatch between the thinned flip chip die 14 and the module substrate 12.

The first mold compound component 18 resides over the underfilling layer 16, surrounds the thinned flip chip die 14, and extends above the upper surface of the thinned flip chip die 14 to form a cavity 28 over the upper surface of the thinned flip chip die 14. Herein, the cavity 28 includes a lower region LR and an upper region UR that resides over the lower region LR, and the upper surface of the thinned flip chip die 14 is exposed to the lower region LR of the cavity 28. In this embodiment, the lower region LR is at least 1% of the entire cavity 28. The first mold compound component 18 may be formed from a same or different material as the underfilling layer 16. When the first mold compound 18 and the underfilling layer 16 are formed from a same material, the first mold compound 18 and the underfilling layer 16 may be formed simultaneously. One exemplary material used to form the first mold compound component 18 is an organic epoxy resin system.

The thermally enhanced mold compound component 20 includes a lower portion with a first average thermal conductivity and an upper portion with a second average thermal conductivity. The lower portion of the thermally enhanced mold compound component 20 fills the lower region LR of the cavity 28 and resides over the upper surface of the thinned flip chip die 14. The upper portion of the thermally enhanced mold compound component 20 fills the upper region UR of the cavity 28 and resides over the lower portion of the thermally enhanced mold compound component 20. In some applications, the upper portion of the thermally enhanced mold compound component 20 may further reside over the first mold compound component 18.

The thermally enhanced mold compound component 20 is formed from a second mold compound component 30 mixed with a thermal additive 32, and has no air pockets or voids. The second mold compound component 30 may be formed from a same or different material as the first mold compound component 18. By definition, materials are different if they include different elements or have a different element composition. In higher performing embodiments, the second mold compound component 30 may be a high thermal conductivity mold compound component. Compared to the normal mold compound component having a thermal conductivity about 0.8 w/m·k, the high thermal conductivity mold compound component has a thermal conductivity greater than 2.5 w/m·k, such as Hitachi Chemical Electronic Materials GE-506HT.

In addition, the thermal additive 32 is dispersed throughout the lower portion of the thermally enhanced mold compound component 20 at a first average density. The thermal additive 32 may have a varied density, which decreases gradually from a bottom to a top of the lower portion of the thermally enhanced mold compound component 20. The thermal additive 32 may be also dispersed in the upper portion of the thermally enhanced mold compound component 20 at a second average density, which is less than the first average density. In some applications, the upper portion of the thermally enhanced mold compound component 20 is void of the thermal additive 32. The thermal additive 32 has a thermal conductivity between 10 w/m·k and 5000 w/m·k, which is higher than the second mold compound component 30. Consequently, the thermally enhanced mold compound component 20 has greater thermal conductivity than the second mold compound component 30 alone. Depending on the different densities of the thermal additive 32 dispersed in the lower portion and upper portion of the thermal conductivity mold compound component 20, the first average thermal conductivity of the lower portion of the thermally enhanced mold compound component 20 is different from the second average thermal conductivity of the upper portion of the thermally enhanced mold compound component 20. In this embodiment, the first average thermal conductivity is at least 1.2 times greater than the second average thermal conductivity.

Notice that, besides the high thermal conductivity, the thermal additive 32 also has high electrical resistivity to accommodate radio-frequency (RF) properties of the thinned flip chip die 14. The thermal additive 32 may be formed from a number of micro-level particulates utilizing materials such as boron nitride, aluminum nitride, silicon nitride, alumina, beryllium oxide, carbon nanotube, and metamaterials. Boron nitride, due to its extremely high thermal conductivity (between 50 W/mK and 150 W/mK), extremely high electrical resistivity (greater than 1E12 Ohm-cm), and low cost, is a desired material for the thermal additive 32.

Heat generated by devices in the device layer 22 will travel upward to an area above the dielectric layer 26 and into the lower region LR of the cavity 28. The heat then passes downward through the dielectric layer 26, the device layer 22, and the interconnects 24 to the module substrate 12, which will dissipate the heat. It is therefore highly desirable to have a high thermal conductivity region immediately adjacent to the upper surface of the thinned flip chip die 14 to conduct most of the heat generated by the thinned flip chip die 14. Consequently, the higher the thermal conductivity in the lower region LR of the cavity 28, the better the heat dissipation performance of the thinned flip chip die 14. In this embodiment, the thermal additive 32 may directly contact the upper surface of the thinned flip chip die 14 in the lower region LR of the cavity 28. If the thinned flip chip die 14 does not have the silicon handle layer (not shown), the thermal additive 32 directly contacts the dielectric layer 26.

It will be clear to those skilled in the art that more than one thermal additive may be used to enhance the heat dissipation performance of the thinned flip chip die 14. A thermally enhanced semiconductor package 10A with a thermally enhanced mold compound component 20A that includes a first thermal additive 34 and a second thermal additive 36 is illustrated in FIG. 2A. The first thermal additive 34 and the second thermal additive 36 are each dispersed throughout a lower portion of the thermally enhanced mold compound component 20A. The first thermal additive 34 and the second thermal additive 36 may be formed from different materials having different thermal conductivities. By definition, materials are different if they include different elements or have a different element composition.

Alternatively, the first thermal additive 34 and the second thermal additive 36 may be dispersed in different portions of a thermally enhanced mold compound component 20B within a thermally enhanced semiconductor package 10B as depicted in FIG. 2B. The lower portion of the thermally enhanced mold compound 20B includes a first lower portion, which resides over the upper surface of the thinned flip chip die 14, and a second lower portion, which resides over the first lower portion. The first thermal additive 34 is dispersed throughout the first lower portion, and the second thermal additive 36 is dispersed throughout the second lower portion. The first thermal additive 34 and the second thermal additive 36 may be formed from different materials, and the first thermal additive 34 may have higher thermal conductivity than the second thermal additive 36.

FIGS. 3-8 provide exemplary steps that illustrate a process to fabricate the exemplary thermally enhanced semiconductor package 10 shown in FIG. 1. Although the exemplary steps are illustrated in a series, the exemplary steps are not necessarily order dependent. Some steps may be done in a different order than that presented. Further, processes within the scope of this disclosure may include fewer or more steps than those illustrated in FIGS. 3-8.

Initially, a semiconductor package 38 is provided as depicted in FIG. 3. For the purpose of this illustration, the semiconductor package 38 includes the module substrate 12, a flip chip die 14F, the underfilling layer 16, and the first mold compound component 18. In different applications, the semiconductor package 38 may include multiple flip chip dies. In detail, the flip chip die 14F includes the device layer 22, the interconnects 24 extending from a lower surface of the device layer 22 and coupled to the upper surface of the module substrate 12, the dielectric layer 26 over the upper surface of the device layer 22, and a silicon handle layer 40 over the dielectric layer 26. As such, the backside of the silicon handle layer 40 is a top surface of the flip chip die 14F. In addition, the underfilling layer 16 resides over the upper surface of the module substrate 12, such that the underfilling layer 16 encapsulates the interconnects 24 and underfills the flip chip die 14F between the lower surface of the device layer 22 and the upper surface of the module substrate 12. The first mold compound component 18 resides over the underfilling layer 16 and encapsulates the flip chip die 14F. The first mold compound component 18 may be used as an etchant barrier to protect the flip chip die 14F against etching chemistries such as Tetramethylammonium hydroxide (TMAH), potassium hydroxide (KOH), sodium hydroxide (NaOH), and acetylcholine (ACH) in the following steps.

Next, the first mold compound component 18 is thinned down to expose the backside of the silicon handle layer 40 of the flip chip die 14F, as shown in FIG. 4. The thinning procedure may be done with a mechanical grinding process. The following step is to remove substantially the entire silicon handle layer 40 of the flip chip die 14F to create the cavity 28 and provide the thinned flip chip die 14 with the upper surface exposed to the cavity 28, as shown in FIG. 5. Herein, removing substantially the entire silicon handle layer 40 refers to removing at least 95% of the entire silicon handle layer 40, and perhaps a portion of the dielectric layer 26. As such, in some applications, the thinned flip chip die 14 may refer to a device including the device layer 22, the interconnects 24 extending from the lower surface of the device layer 22 and coupled to the module substrate 12, and the dielectric layer 26 over the upper surface of the device layer 22, where the upper surface of the dielectric layer 26 is the upper surface of the thinned flip chip die 14. For other cases, the thinned flip chip die 14 may refer to a device including the device layer 22, the interconnects 24 extending from the lower surface of the device layer 22 and coupled to the module substrate 12, the dielectric layer 26 over the upper surface of the device layer 22, and a thin (less than 2 μm) silicon handle layer 40 left over the dielectric layer 26, where the upper surface of the thin silicon handle layer 40 is the upper surface of the thinned flip chip die 14. Because the silicon handle layer 40 is removed substantially, deleterious harmonic generations and intermodulation distortions at an interface between the silicon handle layer 40 and the dielectric layer 26 may be eliminated. Removing substantially the entire silicon handle layer 40 may be provided by an etching process with a wet/dry etchant chemistry, which may be TMAH, KOH, ACH, NaOH, or the like.

Herein, the cavity 28 includes the lower region LR and the upper region UR that resides over the lower region LR, and the upper surface of the thinned flip chip die 14 is exposed to the lower region LR of the cavity 28. The thermal additive 32 is then applied throughout the lower region LR of the cavity 28 at the first average density as depicted in FIG. 6. The thermal additive 32 may be formed from a number of micro-level particulates and may have a varied density through the lower region LR of the cavity 28. In this embodiment, the density of the thermal additive 32 may decrease gradually from the bottom to the top of the lower region LR of the cavity 28. Applying the thermal additive 32 throughout the lower region LR of the cavity 28 may be provided by dispensing the thermal additive 32 immediately over the upper surface of the thinned flip chip die 14F and squeegeeing the thermal additive 32 into the lower region LR of the cavity 28. Other techniques, such as a direct local dispensing process using an electrostatic header or a local placement process using Pick-and-Place tools, may also be utilized to apply the thermal additive 32 throughout the lower region LR of the cavity 28. It will be clear to those skilled in the art that more than one thermal additive may be applied throughout the lower region LR of the cavity 28 (not shown).

After the thermal additive 32 is dispersed throughout the lower region LR of the cavity 28, the second mold compound 30M is applied in the cavity 28 to fill the lower region LR and the upper region UR of the cavity 28 as depicted in FIG. 7. As such, the second mold compound 30M is dispersed throughout the number of particulates of the thermal additive 32 in the lower region LR of the cavity 28. Because air pockets or voids have poor thermal conductivity, formation of any air pockets or voids will be avoided during filling of the lower region LR and the upper region UR of the cavity 28 by the second mold compound 30M. The second mold compound 30M may further reside over the first mold compound component 18. A curing process (not shown) is followed to harden the second mold compound 30M in order to form the second mold compound component 30 and complete the thermally enhanced mold compound component 20. The curing temperature is between 100° C. and 320° C. depending on which material is used as the second mold compound 30M.

The thermally enhanced mold compound component 20 includes the lower portion filling the lower region LR of the cavity 28 and the upper portion filling the upper region UR of the cavity 28. Herein, the thermal additive 32 is dispersed throughout the lower portion of the thermally enhanced mold compound component 20 without any air pockets or voids. Since the thermal additive 32 has a higher thermal conductivity than the second mold compound component 30, the thermally enhanced mold compound component 20 has greater thermal conductivity than the second mold compound component 30 alone. Further, if the upper portion of the thermally enhanced mold compound component 20 includes the thermal additive 32 at a second average density, which is less than the first average density, the first average thermal conductivity of the lower portion of the thermally enhanced mold compound component 20 is greater than the second average thermal conductivity of the upper portion of the thermally enhanced mold compound component 20. In this embodiment, the first average thermal conductivity is at least 1.2 w/m·k and the second average thermal conductivity is at least 0.8 w/m·k. The first average thermal conductivity is at least 1.2 times greater than the second average thermal conductivity.

Finally, an upper surface of the thermally enhanced mold compound component 20 is planarized to form the thermally enhanced semiconductor package 10 as depicted in FIG. 8. A mechanical grinding process may be used for planarization. The upper portion of the thermally enhanced mold compound component 20 may reside over the first mold compound component 18.

Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

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Citation

Patents Cited in This Cited by
Title Current Assignee Application Date Publication Date
半導体装置の製造方法 株式会社デンソー,株式会社日本自動車部品総合研究所 18 July 2007 05 February 2009
Adhesion method and electronic component POLYMATECH CO., LTD. 08 December 2000 21 June 2001
Microelectronic package having an integrated heat sink and build-up layers INTEL CORPORATION 08 December 2000 13 June 2002
蓋部を備えた半導体ウェハの製造方法及び半導体装置の製造方法 シャープ株式会社 15 June 2004 05 January 2006
MEMSデバイスのパッケージ マイクロケム コーポレイション 14 March 2007 27 August 2009
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