阅读说明：本技术 用于半导体包封材料的离子操纵方法及相关装置和系统 (Ion manipulation method for semiconductor encapsulation materials and related apparatus and system ) 是由 R·杰默尔 M·鲍尔 S·米特哈纳 于 2019-06-13 设计创作，主要内容包括：本发明提供了一种用于操纵半导体器件的包封材料中包含的离子的方法。所述方法包括处理包封材料,并且在包封材料被最终固化之前将电场施加到包封材料。包封材料中包含的离子具有随着包封材料固化而降低的迁移率。通过在包封材料被最终固化之前将电场施加到包封材料,减少了包封材料中包含的离子的量和/或将包含的离子浓缩在包封材料的一个或多个区域中。还描述了通过该方法制造的对应装置和半导体封装。(The present invention provides a method for manipulating ions contained in an encapsulation material of a semiconductor device. The method includes processing the encapsulating material and applying an electric field to the encapsulating material before the encapsulating material is finally cured. The ions contained in the encapsulating material have a mobility that decreases as the encapsulating material is cured. By applying an electric field to the encapsulating material before the encapsulating material is finally cured, the amount of ions contained in the encapsulating material is reduced and/or the contained ions are concentrated in one or more regions of the encapsulating material. Corresponding devices and semiconductor packages manufactured by the method are also described.)

1. A method, comprising:

processing an encapsulating material for a semiconductor device, the encapsulating material comprising ions having a mobility that decreases as the encapsulating material cures; and

applying an electric field to the encapsulating material to reduce the amount of ions contained in the encapsulating material and/or concentrate the ions contained in the encapsulating material in one or more regions of the encapsulating material before the encapsulating material is finally cured.

2. The method of claim 1, wherein applying the electric field to the encapsulating material before the encapsulating material is finally cured comprises: applying a voltage across at least one pair of electrodes proximate the encapsulating material such that positive ions contained in the encapsulating material are attracted to each negatively charged electrode of the at least one pair of electrodes and negative ions contained in the encapsulating material are attracted to each positively charged electrode of the at least one pair of electrodes.

3. The method of claim 2, wherein the at least one pair of electrodes is in direct contact with the encapsulating material.

4. The method of claim 1, wherein the electric field applied to the encapsulating material is constant.

5. The method of claim 1, further comprising:

varying the electric field applied to the encapsulating material.

6. The method of claim 1, wherein processing the encapsulating material comprises: forcing a liquefied base material for forming the encapsulation material through a conduit, and wherein applying the electric field to the encapsulation material before the encapsulation material is finally solidified comprises: a voltage is applied across at least one pair of electrodes disposed outside of the conduit, disposed inside of the conduit, or forming part of the conduit.

7. The method of claim 1, wherein treating the encapsulating material comprises forcing the encapsulating material in an uncured state through a catheter, and wherein applying the electric field to the encapsulating material before the encapsulating material is finally cured comprises: a voltage is applied across at least one pair of electrodes disposed outside of the conduit, disposed inside of the conduit, or forming part of the conduit.

8. The method of claim 1, wherein processing the encapsulation material comprises inserting the encapsulation material into a cavity or mold cavity holding the semiconductor device, and wherein applying the electric field to the encapsulation material before the encapsulation material is finally cured comprises: a voltage is applied across a first electrode provided by the semiconductor device and a second electrode spaced apart from the semiconductor device in the cavity or mold cavity.

9. The method of claim 1, wherein processing the encapsulation material comprises curing the encapsulation material in a curing oven after applying the encapsulation material to the semiconductor device, and wherein applying the electric field to the encapsulation material before the encapsulation material is finally cured comprises: a voltage is applied across a first electrode provided by the semiconductor device and a second electrode spaced apart from the semiconductor device in the curing oven.

10. The method of claim 9, further comprising one of:

thinning the encapsulating material after the encapsulating material is cured in the curing oven;

selectively etching the encapsulating material after the encapsulating material is cured in the curing oven; and

after the encapsulating material is cured in the curing oven, a specific chemical reaction is applied to the encapsulating material.

11. A semiconductor device, comprising:

a semiconductor die;

an encapsulant in contact with the semiconductor die; and

a first set of ions concentrated in the encapsulation material and at a first distance from the semiconductor die.

12. The semiconductor device of claim 11, wherein the first set of ions comprises a distribution of positively charged ions that is offset from a distribution of negatively charged ions.

13. The semiconductor device of claim 11, further comprising a second set of ions concentrated in the encapsulation material and at a second distance from the semiconductor die, the second distance being greater than the first distance.

14. The semiconductor device of claim 13, wherein the first set of ions comprises a first distribution of positively charged ions offset from a first distribution of negatively charged ions, and wherein the second set of ions comprises a second distribution of positively charged ions offset from a second distribution of negatively charged ions.

15. An apparatus, comprising:

a housing configured to contain an encapsulating material for a semiconductor device, the encapsulating material containing ions having a mobility that decreases as the encapsulating material cures;

at least one pair of electrodes configured to apply an electric field to the encapsulating material contained by the housing before the encapsulating material is finally cured to reduce an amount of ions contained in the encapsulating material and/or concentrate the ions contained in the encapsulating material in one or more regions of the encapsulating material; and

a power supply configured to provide a voltage across the at least one pair of electrodes.

16. The apparatus of claim 15, wherein the housing is a conduit configured to transport liquefied base material for forming the encapsulation material to a chamber or molding cavity or to transport the encapsulation material in an uncured state to the chamber or molding cavity, and wherein the at least one pair of electrodes is disposed outside of the conduit, inside of the conduit, or forms part of the conduit.

17. The apparatus of claim 15, wherein the housing is a cavity or mold cavity configured to house the semiconductor device and the encapsulation material, and wherein the at least one pair of electrodes includes a first electrode provided by the semiconductor device and a second electrode spaced apart from the semiconductor device in the cavity or mold cavity.

18. The device of claim 17, wherein the chamber or mold cavity forms the second electrode.

19. The apparatus of claim 15, wherein the enclosure is a curing oven configured to cure the encapsulating material after applying the encapsulating material to the semiconductor device, and wherein the at least one pair of electrodes includes a first electrode provided by the semiconductor device and a second electrode spaced apart from the semiconductor device in the curing oven.

20. The apparatus of claim 19, wherein the curing oven includes a cradle on which the semiconductor device rests during curing of the encapsulating material, and wherein the cradle forms the second electrode.

Background

Mobile ions or charges in the die encapsulation material (e.g., molding compound) may reduce the reliability of the encapsulated semiconductor package. This problem is exacerbated for products that must withstand high operating voltages and/or withstand extreme operating conditions (e.g., high temperatures above 150 ℃). For higher operating temperatures and voltages, the probability of ions migrating into critical areas of the package during the lifetime of the encapsulated semiconductor package increases. Excessive ion migration may adversely affect the electrical parameters and functionality of the encapsulated semiconductor package. Accordingly, there is a need for improved techniques for limiting ion migration within encapsulated semiconductor packages.

Disclosure of Invention

According to an embodiment of a method, the method comprises: processing an encapsulation material for a semiconductor device, the encapsulation material comprising ions having a mobility that decreases as the encapsulation material cures; and applying an electric field to the encapsulating material to reduce the amount of ions contained in the encapsulating material and/or concentrate the ions contained in the encapsulating material in one or more regions of the encapsulating material before the encapsulating material is finally cured.

According to an embodiment of a semiconductor package, the semiconductor package comprises: a semiconductor die; an encapsulant in contact with the semiconductor die; and a first set of ions concentrated in the encapsulation material and at a first distance from the semiconductor die.

According to an embodiment of an apparatus, the apparatus comprises: a housing configured to contain an encapsulating material for a semiconductor device, the encapsulating material containing ions having a mobility that decreases as the encapsulating material cures; at least one pair of electrodes configured to apply an electric field to the encapsulating material contained by the housing before the encapsulating material is finally cured to reduce the amount of ions contained in the encapsulating material and/or concentrate ions contained in the encapsulating material in one or more regions of the encapsulating material; and a power supply configured to provide a voltage across the at least one pair of electrodes.

Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

Drawings

The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts. Features of the various illustrated embodiments may be combined unless they are mutually exclusive. Embodiments are shown in the drawings and are described in detail in the following description.

Fig. 1 illustrates an embodiment of a method for manipulating ions contained in an encapsulation material of a semiconductor device.

Fig. 2 illustrates a general block diagram of an embodiment of implementing the ion manipulation method shown in fig. 1 in a system for manufacturing a molding compound encapsulant material.

Fig. 3 illustrates a general block diagram of an embodiment of the ion manipulation method shown in fig. 1 implemented in a system for encapsulating a semiconductor device in a molding compound encapsulation material.

Fig. 4 to 9 show respective schematic diagrams of embodiments in which the ion manipulation method shown in fig. 1 is used with a housing configured for accommodating an encapsulation material of a semiconductor device, the encapsulation material containing ions having a mobility that decreases as the encapsulation material cures.

Fig. 10A shows a schematic diagram of an embodiment of a system configured to implement the ion manipulation method shown in fig. 1 in a mold cavity housing configured to contain a melted or liquefied mold compound encapsulant material containing ions having a mobility that decreases as the encapsulant material solidifies.

Fig. 10B shows a schematic diagram of an embodiment of a system configured to implement the ion manipulation method shown in fig. 1 in a chamber configured to contain a PCB or eWLB encapsulation material containing ions having a mobility that decreases as the encapsulation material solidifies.

FIG. 11 shows a schematic diagram of an embodiment of a system configured to implement the ion manipulation method shown in FIG. 1 in a curing oven.

Fig. 12-14 illustrate respective embodiments of packaged semiconductor devices processed using the ion manipulation method illustrated in fig. 1.

Fig. 15A-15C illustrate an embodiment of removing one or more sets of concentrated ions within an encapsulation material of a packaged semiconductor device processed using the ion manipulation method shown in fig. 1.

Fig. 16 illustrates an embodiment of a packaged semiconductor device processed using the ion manipulation method illustrated in fig. 1 and including an absorption structure for absorbing (trapping) ions displaced from a surface of the semiconductor device by the ion manipulation method.

Detailed Description

Embodiments described herein provide methods, and related apparatus and systems, for manipulating ions contained in an encapsulation material of a semiconductor device. Ions may be formed in and/or added to the encapsulation material as part of the material fabrication process, may be present at the surface of the semiconductor device to be at least partially covered by the encapsulation material, and may be introduced during the encapsulation process. Mobile sodium is particularly problematic and is often present in common molding compounds, where the source may be, for example, aluminum hydroxide (flame retardant). Other types of mobile ions present in the semiconductor device encapsulating material may also affect the electrical parameters and functionality of the semiconductor device at least partially covered by the encapsulating material.

By applying an electric field to the encapsulating material before it is finally cured, the amount of ions contained in the encapsulating material may be reduced and/or the ions contained in the encapsulating material may be concentrated in one or more less critical areas of the encapsulating material, which areas have a smaller impact on the electrical parameters and the functionality of the semiconductor device at least partly covered by the encapsulating material.

Ions contained within the encapsulating material of a semiconductor device typically have a mobility that decreases with curing. Thus, the methods, apparatuses, and systems described herein may be used during the manufacture of the encapsulating material, during the application of the encapsulating material to the semiconductor device, and/or during the curing of the encapsulating material.

Fig. 1 illustrates an embodiment of a method for manipulating ions contained in an encapsulation material of a semiconductor device. The encapsulating material includes ions having a mobility that decreases as the encapsulating material cures. For example, the encapsulant material may be a molding compound and/or resin used in injection molding, compression molding, Film Assisted Molding (FAM), Reaction Injection Molding (RIM), Resin Transfer Molding (RTM), blow molding, and the like. Common molding compounds and resins include, but are not limited to, thermosetting resins, gel elastomers, encapsulants, potting compounds, composites, optical grade materials, and the like. The molding compound is typically supplied in the form of pellets, films, liquids, and/or powders. Other types of encapsulation materials for semiconductor devices and containing ions with mobility that decreases as the encapsulation material cures may include, but are not limited to, any standard insulating PCB (printed circuit board) material with or without glass fibers, polymer films or stacks of polymer films, any standard insulating eWLB (embedded wafer level ball grid array) material, and the like.

The method shown in fig. 1 includes processing an encapsulant (block 100). The type of processing performed on the encapsulating material may depend on the type of material and/or the stage of manufacture/use.

For example, in the case of making a Molding Compound (MC) -type encapsulant material, the process (block 100) may include forcing liquefied base material used to form the MC encapsulant material through a conduit. The liquefied base material may be a resin and possible fillers and/or additives, such as glass fiber reinforcement, flame retardants, hardeners, etc., may be added to the base material.

Where the encapsulation material is applied to the semiconductor device, for example, by molding, PCB encapsulation, eWLB encapsulation, or the like, the processing (block 100) may include inserting the encapsulation material into a cavity or mold cavity. The cavity or mold cavity includes each semiconductor device at least partially covered by an encapsulation material. For molding, the encapsulating material may be liquefied and forced through a conduit into a molding cavity. For PCB and eWLB encapsulation, the encapsulation material may be placed in a process chamber.

After encapsulation, the processing (block 100) may include curing the encapsulation material in a curing oven.

The method also includes applying an electric field to the encapsulation material before the encapsulation material is finally cured (block 102). The manner in which the electric field is applied may depend on the type of material and/or the stage of manufacture/use.

For example, in the case of manufacturing an encapsulant material, an electric field may be applied (block 102) to the liquefied base material used to make the MC encapsulant material by applying a voltage across at least one pair of electrodes disposed outside of, within, or forming part of a conduit carrying the liquefied base material. Positive ions, such as sodium, contained in the liquefied base material flowing through the conduit are attracted to each of the negatively charged electrodes, and negative ions contained in the liquefied material are attracted to each of the positively charged electrodes. The electrodes may be periodically cleaned, for example by flushing the catheter, to prevent the accumulation of ions inside the catheter.

In the case where the encapsulant material is applied to the semiconductor device, such as by molding, an electric field may be applied (block 102) to the liquefied MC encapsulant material as it flows through the conduit and into the mold cavity by applying a voltage across at least one pair of electrodes disposed outside of the conduit, inside of the conduit, or forming part of the conduit. The electrodes may be periodically cleaned, for example by flushing the catheter, to prevent the accumulation of ions inside the catheter. For PCB and eWLB encapsulation, an electric field may be applied (block 102) to the PCB or eWLB encapsulation material inside the processing chamber by applying a voltage across a first electrode provided by the semiconductor device and a second electrode spaced apart from the semiconductor device in the chamber. In each encapsulation process, positive ions contained in the encapsulating material are attracted to each of the negatively charged electrodes, and negative ions contained in the encapsulating material are attracted to each of the positively charged electrodes.

During curing of the encapsulation material, an electric field may be applied (block 102) to the encapsulation material before the encapsulation material is finally cured by applying a voltage across a first electrode provided by the encapsulated semiconductor device and a second electrode spaced apart from the encapsulated semiconductor device in a curing oven. When the encapsulating material is cured, positive ions contained in the encapsulating material are attracted to each of the negatively charged electrodes, and negative ions contained in the cured encapsulating material are attracted to each of the positively charged electrodes. For PCB and eWLB encapsulation, the process chamber used to apply the PCB or eWLB encapsulation material to the semiconductor device may also be used as a furnace for final curing of the PCB or eWLB encapsulation material. In other embodiments, the curing oven is separate from the processing chamber used for the encapsulation process.

In each of these examples, at least one pair of electrodes is sufficiently close to the encapsulating material such that positive ions contained in the encapsulating material are attracted to each negatively charged electrode and negative ions contained in the encapsulating material are attracted to each positively charged electrode. By applying an electric field to the encapsulating material before the encapsulating material is finally cured, the amount of ions contained in the encapsulating material is reduced and/or the ions contained in the encapsulating material are concentrated in one or more less critical areas of the encapsulating material which have a smaller impact on the electrical parameters and the functionality of the semiconductor device which is at least partly covered by the encapsulating material. The electric field may be applied for a fixed duration or until certain conditions occur or criteria are met, such as molding is complete, final cure is complete, sensor activation, safety interruption, etc. (block 104). The electric field applied to the encapsulating material as part of the ion manipulation method may be constant or variable (varied). Application of the electric field to the encapsulation material is terminated at block 106.

Fig. 2 illustrates a general block diagram of an embodiment of implementing the ion manipulation method described herein and shown in fig. 1 in a system 200 for making an MC (mold compound) encapsulation material. The system 200 includes a supply 202 for a base material, such as a resin, and a supply 204 for possible fillers and/or additives (e.g., glass fiber reinforcement, flame retardants, hardeners, etc.). The system 200 includes one or more conduits or lines 206 for conveying materials to a mixing unit 208, the mixing unit 208 mixing the base materials and possible fillers and/or additives. The material may be liquefied prior to mixing. The system 200 includes a curing unit 210 for optionally extruding and at least partially curing the mixture output by the mixing unit 208. This stage provides intermediate curing. Final curing of the encapsulating material occurs after the encapsulating material is applied to the semiconductor device. The system may include one or more post-cure stages 212. The MC encapsulating material 214 is then ready for application to a semiconductor device, for example, in pellet form, film form, liquid form, powder form, and the like. The ion manipulation method described herein and shown in fig. 1 may be used at any stage of the MC encapsulation material manufacturing process shown in fig. 2, where the ions in the material have sufficient mobility to be moved by an applied electric field. The dashed boxes in fig. 2 show exemplary stages at which the ion manipulation method may be employed.

Fig. 3 illustrates a general block diagram of an embodiment of an ion manipulation method described herein and shown in fig. 1 implemented in a system 300 for encapsulating a semiconductor device in an MC (mold compound) encapsulation material. The system 300 includes a supply 302 for MC encapsulating material (e.g., thermoset resin, gel elastomer, encapsulant, potting compound, composition, optical grade material, etc.). The system 300 includes one or more conduits or lines 304 for carrying the MC encapsulating material and possible additives (e.g., mold, hardener, etc.) to a viscosity unit 308. The viscosity unit 308 increases the viscosity of the MC encapsulating material and possible additives, for example by melting, liquefying, etc., to press the MC encapsulating material into the cavity. The system 300 includes another conduit or line 310 for conveying the molten MC encapsulation material from the viscosity unit 308 to a molding cavity 312, the molding cavity 312 containing the semiconductor device at least partially covered by the MC encapsulation material. The molding cavity 312 may be closed or opened to a fill plunger depending on the type of molding process. As the MC encapsulating material cools, some intermediate solidification may occur in the molding cavity 312. The system 300 may include one or more post-cure stages 314, such as trimming, thinning, deburring, scribing, and the like. The molded semiconductor package 316 is then ready for final curing. The ion manipulation method described herein and shown in fig. 1 may be used at any stage in the molding process shown in fig. 3, where the ions in the material have sufficient mobility to be moved by the applied electric field. The dashed boxes in fig. 3 show exemplary stages at which the ion manipulation method may be employed.

Fig. 4-9 illustrate embodiments in which the ion manipulation method is used with a housing configured to house an encapsulation material for a semiconductor device, the encapsulation material containing ions having a mobility that decreases as the encapsulation material cures. Even if the mobility of one type of ion is not reduced during curing, an electric field can still be used to move the other type of ion away from the critical region, thereby improving the reliability of the device. Additional layers may be provided to trap ions with reduced mobility and/or move ions without reducing mobility. The ions contained in the encapsulating material may be ions naturally present in the encapsulating material during the manufacture of the raw materials used to make the encapsulating material or the partially manufactured material and/or ions added intentionally or unintentionally. In each case, any layer to which a cure/field can be applied can be used by the methods described herein to clean ions on the surface prior to molding. In general, the ion source is not critical as long as the ions are movable in an electric field.

According to the embodiment shown in fig. 4-9, the housing is a conduit 400 configured to carry MC encapsulating material indicated by the downward dashed arrow. The conduit 400 may be any type of pipe, tube, line, etc. for carrying the MC encapsulating material prior to final curing. The MC encapsulating material carried by conduit 400 may be in its final form just prior to application to the semiconductor device, may be in its base material form, or may be in some intermediate form. For example, the conduit 400 may be configured to carry liquefied base material for forming MC encapsulation material, e.g., as shown in fig. 2. The conduit 400 may be configured to carry the MC encapsulating material in an uncured state to a cavity or molding cavity, for example, as shown in fig. 3. In each case, at least one pair of electrodes 402, 404 is provided for applying an electric field to the MC encapsulating material carried by the catheter 400 before the MC encapsulating material is finally cured.

Fig. 4 shows an embodiment of a catheter 400 in which at least one pair of electrodes 402, 404 is disposed outside the catheter 400. An electric field is applied to the MC encapsulating material carried by the catheter 400 by at least one pair of electrodes 402, 404. A controller 406 may be provided for controlling a power supply 408, the power supply 408 applying a voltage across at least one pair of electrodes 402, 404 disposed outside the catheter 400. The controller 406 and the power supply 408 may be integrated or separate components. The controller 406 may control the power source 408 such that a constant electric field is applied to the MC encapsulating material by at least one pair of electrodes 402, 404. In another embodiment, the controller 406 may control the power supply 408 such that a varying electric field (e.g., a pulsed electric field), a voltage waveform with a continuously increasing field, a voltage waveform with a continuously decreasing field, a voltage waveform with alternating amplitudes (even within one polarity), or the like, is applied to the MC encapsulating material through at least one pair of electrodes 402, 404. That is, the electric field may be constant or vary in polarity and/or intensity in any suitable combination.

In each case, the ions contained in the MC encapsulation material have sufficient mobility to be moved by the applied electric field. Positive ions (+) contained in the MC encapsulating material carried by conduit 400 are attracted to each negatively charged electrode 402, and negative ions (-) contained in the MC encapsulating material carried by conduit 400 are attracted to each positively charged electrode 404. An electric field applied to at least one pair of electrodes 402, 404 disposed outside the conduit 400 holds (traps) ions along the inner wall 410 of the conduit 400 such that the amount of ions contained in the MC encapsulating material is reduced. The inner wall 410 of the catheter 400 may be periodically cleaned, for example, by rinsing the catheter, to prevent the accumulation of ions along the inner wall.

Fig. 5 shows another embodiment of a catheter 400 in which at least one pair of additional electrodes 412, 414 is disposed on the exterior of the catheter 400. The embodiment shown in fig. 5 is similar to the embodiment shown in fig. 4. However, with the difference that at least one additional pair of electrodes 412, 414 is provided with an opposite voltage polarity to the first pair of electrodes 402, 404. According to this embodiment, positive ions (+) contained in the MC encapsulating material carried by conduit 400 are attracted to different sides of conduit 400, as are negative ions (-) contained in the MC encapsulating material.

Fig. 6 illustrates one embodiment of a catheter 400 in which at least one pair of electrodes 402, 404 is disposed inside the catheter 400. An electric field is applied to the MC encapsulating material carried by the catheter 400 by at least one pair of electrodes 402, 404. The controller 406 may control the power source 408 such that a constant or varying electric field is applied to the MC encapsulating material by at least one pair of electrodes 402, 404 disposed inside the catheter 400. Mobile ions contained in the MC encapsulation material move in response to an applied electric field. Positive ions (+) are attracted to each negatively charged electrode 402 and negative ions (-) are attracted to each positively charged electrode 404. An electric field applied to at least one pair of electrodes 402, 404 disposed inside the conduit 400 holds (traps) ions against the electrodes 402, 404 such that the amount of ions contained in the MC encapsulating material is reduced. The electrodes 402, 404 may be periodically cleaned, for example, by flushing the catheter, to prevent the accumulation of ions on the electrodes 402, 404.

Fig. 7 shows another embodiment of a catheter 400 in which at least one pair of additional electrodes 412, 414 is disposed inside the catheter 400. The embodiment shown in fig. 7 is similar to the embodiment shown in fig. 6. However, with the difference that at least one additional pair of electrodes 412, 414 is provided with an opposite voltage polarity to the first pair of electrodes 402, 404. According to this embodiment, positive ions (+) contained in the MC encapsulating material carried by the conduit 400 are attracted to the electrodes 402, 414 on different sides of the conduit 400, as are negative ions (-) contained in the MC encapsulating material.

Fig. 8 shows an embodiment of a catheter 800 in which at least one pair of electrodes 402, 404 forms part of the catheter 400. For example, at least one pair of electrodes 402, 404 may be integrated into the wall structure of the catheter 400. In another example, the wall or region of the wall of the conduit 400 may be electrically segmented to form at least one pair of electrodes 402, 404. In either case, an electric field is applied to the MC encapsulating material carried by the catheter 400 by at least one pair of electrodes 402, 404 forming part of the catheter 400. The controller 406 controls the power source 408 such that a constant or varying electric field is applied to the MC encapsulating material by at least one pair of electrodes 402, 404. Mobile ions contained in the MC encapsulation material move in response to an applied electric field. Positive ions (+) are attracted to each negatively charged electrode 402 and negative ions (-) are attracted to each positively charged electrode 404. In fig. 8, an electric field applied to at least one pair of electrodes 402, 404 forming part of the conduit 400 holds (traps) ions against the portion of the conduit wall with the integrated electrodes 402, 404 such that the amount of ions contained in the MC encapsulation material is reduced. The inner wall of the catheter 400 may be periodically cleaned, for example by flushing the catheter, to prevent the accumulation of ions on the inner wall.

Fig. 9 shows another embodiment of a catheter 400, wherein at least one pair of additional electrodes 412, 414 form part of the catheter 400. The embodiment shown in fig. 9 is similar to the embodiment shown in fig. 8. However, differently, at least one pair of additional electrodes 412, 414 integrated into the wall structure of the catheter 400 is provided with an opposite voltage polarity to the first pair of integrated electrodes 402, 404. According to this embodiment, positive ions (+) contained in the MC encapsulating material carried by the conduit 400 are attracted to the electrodes 402, 424 integrated in different sides of the conduit 400, as are negative ions (-) contained in the MC encapsulating material.

Fig. 10A illustrates an embodiment in which the ion manipulation methods described herein are used with a housing configured to contain an encapsulation material for a semiconductor device that contains ions having a mobility that decreases as the encapsulation material cures. According to the embodiment shown in fig. 10A, the enclosure is a mold cavity 500, the mold cavity 500 being configured to contain a melted or liquefied MC encapsulant material containing ions having a mobility that decreases as the encapsulant material solidifies and one or more semiconductor devices 502 at least partially covered by the MC encapsulant material. The MC encapsulating material is indicated by the dashed arrow to the right in fig. 10A.

Each semiconductor device 502 has terminals electrically connected to a substrate 504, the substrate 504 being for example a leadframe, a PCB, a ceramic substrate with metallized sides, etc. For ease of illustration only, electrical connections 506 are shown in fig. 10A as bond wire connections, however, other types of electrical connections may be used, such as metal clips, straps, solder bumps, and the like. The semiconductor device 502 may be any type of semiconductor die (chip) or package that is at least partially covered by an encapsulation material. For example, each semiconductor device 502 may be a passive device such as an inductor, a resistor, and/or a capacitor, or an active device such as a power device (e.g., a power transistor, a power diode, etc.), a logic device (e.g., a controller, an ASIC (application specific integrated circuit), etc.), a memory device, a sensor, a MEMS (micro-electro-mechanical system), etc.

Regardless of the type and number of semiconductor devices 502, the mold cavity 500 includes an input 506 for containing the liquefied MC encapsulant as it flows through a conduit (not shown) and into the mold cavity 500. The mold cavity 500 may also include a vent 508.

An electric field may be applied to the MC encapsulating material inside the molding cavity 500 by a power supply 510 controlled by a controller 512. The controller 512 and the power supply 510 may be integrated or separate components. The controller 512 may control the power source 408 such that a constant electric field is applied to the MC encapsulant inside the molding cavity 500. In another embodiment, the controller 512 may control the power supply 510 such that a varying electric field is applied to the MC encapsulating material inside the molding cavity 500. In either case, the ions contained in the MC encapsulation material have sufficient mobility to be moved by the applied electric field.

The electric field may be generated by applying a voltage across a first electrode provided by the semiconductor device 502 included in the mold cavity 500 and a second electrode spaced apart from the semiconductor device 502 in the mold cavity. One terminal of the power supply may be electrically connected to the substrate 504 to which the semiconductor device 502 is attached. In some cases, all terminals of each semiconductor device 502 may be shorted via the substrate 504 until after final curing, and thus no large voltage may build up within the device 502 in response to an applied electric field. If the terminals of each semiconductor device 502 are not shorted together by the substrate 504 during the packaging process, additional care should be taken to ensure that problematic voltages do not build up within the device 502 in response to applied electric fields. In either case, the semiconductor device 502 included in the mold cavity 500 may form one electrode for applying an electric field to the MC encapsulation material.

In one embodiment, the molding cavity 500 or portions of the molding cavity 500 are electrically conductive and form a second electrode for applying an electric field to the encapsulation material. Since the ions are still mobile at this point in the fabrication process, the electric field applied by the electrodes in mold cavity 500 concentrates the mobile ions contained in the MC encapsulant in one or more regions of the MC encapsulant that have less impact on the electrical parameters and functionality of semiconductor device 502. Mobile ions contained in the MC encapsulation material may be concentrated in one or more regions of the MC encapsulation material that are spaced apart from the surface 512 of the semiconductor device 502 that contacts the MC encapsulation material.

Fig. 10B illustrates an embodiment in which the enclosure is a chamber 600 configured to house a PCB or eWLB and one or more semiconductor devices 602 at least partially covered by an encapsulation material containing ions having a mobility that decreases as the encapsulation material cures. For example, each semiconductor device 602 may be placed between sheets of PCB or eWLB lamination layers 604. Each semiconductor device 602 has terminals 606 electrically connected by conductive traces 608 and/or vias 610, which conductive traces 608 and/or vias 610 extend through the PCB/eWLB encapsulation material 604 and/or are formed on a surface of the PCB/eWLB encapsulation material 604. The semiconductor device 602 may be any type of semiconductor die (chip) or package that is at least partially covered by a PCB/eWLB encapsulation material 604. For example, each semiconductor device 602 may be a passive device such as an inductor, a resistor, and/or a capacitor, or an active device such as a power device (e.g., a power transistor, a power diode, etc.), a logic device (e.g., a controller, an ASIC (application specific integrated circuit), etc.), a memory device, a sensor, a MEMS (micro-electro-mechanical system), etc. Regardless of the type and number of semiconductor devices 602, the chamber 600 contains the semiconductor devices 602 and the PCB/eWLB encapsulation material 604.

An electric field may be applied to the PCB/eWLB encapsulation material 604 inside the chamber 600 by a power supply 612 controlled by a controller 614. The controller 614 and the power supply 612 may be integrated or separate components. The controller 614 may control the power supply 612 such that a constant electric field is applied to the PCB/eWLB encapsulation material 604 inside the chamber 600. In another embodiment, the controller 614 may control the power supply 612 such that a varying electric field is applied to the PCB/eWLB encapsulation material 604 inside the chamber 600. In either case, the ions contained in the PCB/eWLB encapsulation material 604 have sufficient mobility to be moved by the applied electric field.

The electric field may be generated by applying a voltage across a first electrode provided by the semiconductor device 602 included in the chamber 600 and a second electrode spaced apart from the semiconductor device 602 in the chamber 600. One terminal of the power supply 612 may be electrically connected to the semiconductor device 602, for example, by one or more of conductive traces 608 and/or vias 610, which conductive traces 608 and/or vias 610 extend through the PCB/eWLB encapsulant 604 and/or are formed on a surface of the PCB/eWLB encapsulant 604. In some cases, all of the terminals 606 of each semiconductor device 602 may be shorted, and thus, large voltages may not accumulate within the device 602 in response to an applied electric field. If the terminals 606 of the semiconductor device 602 are not shorted together during the packaging process, additional care should be taken to ensure that problematic voltages do not build up within the device 602 in response to the applied electric field. In either case, the semiconductor device 602 included in the chamber 600 forms one electrode for applying an electric field to the PCB/eWLB encapsulation material 604.

In one embodiment, chamber 600 or a portion of chamber 600 is conductive and forms a second electrode for applying an electric field to PCB/eWLB encapsulation material 604. Because the ions are still mobile at this point in the fabrication process, the electric field applied by the electrodes in the chamber 600 concentrates the mobile ions contained in the PCB/eWLB encapsulant 604 in one or more regions of the PCB/eWLB encapsulant 604 that have less impact on the electrical parameters and functionality of the semiconductor device 602. Mobile ions contained in the PCB/eWLB encapsulation material 604 may be concentrated in one or more regions of the PCB/eWLB encapsulation material 604 that are spaced apart from a surface of the semiconductor device 602 that contacts the PCB/eWLB encapsulation material 604.

As previously described herein, the encapsulant material to which the ion manipulation methods described herein are applied may be any standard encapsulant material for semiconductor devices and contains ions having a mobility that decreases as the encapsulant material cures. For example, the encapsulation material may be any standard insulating PCB material, polymer film or polymer film stack, any standard insulating eWLB material, etc., with or without glass fibers. The type of housing in which the semiconductor device is at least covered by the encapsulation material depends on the type of encapsulation material used and can be easily adapted to accommodate the electrode configurations described above and shown in fig. 10A and 10B.

Standard mold cavities and PCB/eWLB processing chambers typically include metal components, such as metal plates, platforms, etc., which can form the second electrode, and the semiconductor device can be easily electrically contacted to form the first electrode. Typically, the second electrode may be an additional metal electrode or may be realized by an electrically conductive part that has been used as part of, for example, a molding chamber, a curing oven, etc.

An electric field is applied to the encapsulating material contained in the housing by means of electrodes. A controller may be provided for controlling the power supply for applying the voltage across the electrodes. The controller may control the power source such that a constant electric field is applied to the encapsulation material through the electrodes. In another embodiment, the controller may control the power source such that a varying electric field is applied to the encapsulation material through the electrodes. In either case, the ions contained in the encapsulating material have sufficient mobility to be moved by the applied electric field. Positive ions (+) contained in the encapsulating material are attracted to the negatively charged electrode, and negative ions (-) contained in the encapsulating material are attracted to the positively charged electrode.

Fig. 11 illustrates an embodiment in which the ion manipulation methods described herein are used with a curing oven 700, the curing oven 700 configured to cure an encapsulant 702 encapsulating a semiconductor device 704. Curing oven 700 may hold a plurality of packaged semiconductor devices 704. Each packaged semiconductor device 704 includes one or more semiconductor devices and/or dies (not shown) in contact with the encapsulation material 702. The encapsulating material 702 contains ions that are still mobile because the encapsulating material 702 has not yet fully cured. By applying an electric field to the encapsulating material 702 before the encapsulating material 702 is finally cured, ions contained in the encapsulating material 702 may be concentrated in one or more less critical regions of the encapsulating material 702 that have less impact on the electrical parameters and functionality of the semiconductor device in contact with the encapsulating material 702.

A first electrode for applying an electric field is provided by the packaged semiconductor device 704 and a second electrode for applying an electric field is spaced apart from the packaged semiconductor device 704 in the curing oven 700. In one embodiment, curing oven 700 includes one or more racks 706 on which packaged semiconductor devices 704 rest during final curing of encapsulating material 702. In one embodiment, the rack 706 forms a second electrode for applying an electric field and may be electrically connected together within the curing oven 700 by, for example, jumpers, cables, wires, etc., as shown in FIG. 11. The packaged semiconductor devices 704 may be electrically connected together within the curing oven 700, such as by jumpers, cables, wires, etc., as also shown in fig. 11, to form a first electrode for applying an electric field. The wiring between packaged semiconductor devices 704 may be only natural connections within the same lead frame. In some cases, packaged 704 may not be used as an electrode, but rather a separate pair of electrodes (positive and negative) is provided without contacting device 704.

An electric field is applied through electrodes to an encapsulating material 702 encapsulating a semiconductor device 704 contained in a curing oven 700. A controller 708 may be provided for controlling a power supply 710, the power supply 710 applying a voltage across the electrodes. The controller 708 may control the power supply 710 such that a constant electric field is applied to the encapsulating material 702 through the electrodes. In another embodiment, the controller 708 may control the power supply 710 such that a varying electric field is applied to the encapsulating material 702 through the electrodes. In either case, the ions contained in the encapsulating material 702 of each packaged semiconductor device 704 have sufficient mobility to be moved by an applied electric field during the final curing process. Positive ions (+) contained in the encapsulating material 702 are attracted to the negatively charged electrode, and negative ions (-) contained in the encapsulating material 702 are attracted to the positively charged electrode.

Fig. 12 illustrates an embodiment of a packaged semiconductor device 800 processed with the ion manipulation methods described herein at least during embedding and/or final curing. According to this embodiment, packaged semiconductor device 800 includes a semiconductor die 802 and an encapsulant 804 contacting semiconductor die 802. Packaged semiconductor device 800 may include more than one semiconductor die 802. For ease of illustration, only one semiconductor die 802 is shown in fig. 12.

The ion manipulation methods described herein result in a first set of ions 806 being concentrated in the encapsulation material 804 and at a first distance X1 from the semiconductor die 802. The second set of ions 808 may be concentrated in the encapsulation material 804 and at a second distance X2 from the semiconductor die 802, the second distance X2 being greater than the first distance X1. Additional sets of ions may be concentrated in the encapsulation material 804 and at a greater distance from the semiconductor die 802, but are not shown in fig. 12 for ease of illustration. The distances X1, X2 may be selected such that each set of concentrated ions 806, 808 is disposed in a less critical region of the encapsulation material 804 that has less impact on the electrical parameters and functionality of the semiconductor die 802 in contact with the encapsulation material 804.

Different arrangements of the positive (+) and negative (-) ion concentrations may be achieved in the encapsulating material depending on the manner in which the electric field is applied to the encapsulating material 804 during processing. As the encapsulating material 804 cures, the ion mobility changes (decreases). For example, the ion mobility may be initially high and then decrease over time as the encapsulating material 804 hardens. Negative ions are larger and less mobile than positive ions. In one embodiment, a negative voltage may be applied to the encapsulation material 804 at the beginning of the ion manipulation method to force negative (larger/slower) ions out of the die 802 when mobility is high. The voltage polarity may be switched positive later to force the positive (smaller/faster) ions out of the die 802 as mobility decreases. The negative ions will still be attracted to the positive (device) potential, but far enough away from the die 802, and much less mobile at this point in the process, and therefore should not migrate back to their original position. The positive ions still have sufficient mobility to move away from the die 802 even though their mobility has decreased. The switching point from negative to positive device voltage may be determined by trial and error and/or based on a measurable mobility curve of the encapsulating material 804. In other embodiments, the positive device voltage may be applied first and then the negative voltage applied.

Fig. 13 illustrates an embodiment of a packaged semiconductor device 900 processed at least during device embedding and/or final curing with an ion manipulation method implemented by means of a switching point from a negative device voltage to a positive device voltage. Packaged semiconductor device 900 includes a semiconductor die 902 and an encapsulant 904 in contact with semiconductor die 902. The packaged semiconductor device 900 may include more than one semiconductor die 902. For ease of illustration only, one semiconductor die 902 is shown in fig. 13. The concentrated first set of ions 906 within the encapsulating material 904 includes a layer or distribution of positively charged ions (+) that is offset from a layer or distribution of negatively charged ions (-). The second set 908 of ions concentrated within the encapsulating material 904 similarly includes a layer or distribution of positively charged ions (+) that is offset from the layer or distribution of negatively charged ions (-).

Fig. 14 illustrates an embodiment of a packaged semiconductor device 1000 processed at least during device embedding and/or final curing with an ion manipulation method implemented by means of a switching point from a positive device voltage to a negative device voltage. Packaged semiconductor device 1000 includes a semiconductor die 1002 and an encapsulant 1004 in contact with semiconductor die 1002. Packaged semiconductor device 1000 may include more than one semiconductor die 1002. For ease of illustration only, one semiconductor die 1002 is shown in fig. 14.

The embodiment shown in fig. 14 is similar to the embodiment shown in fig. 13. In contrast, however, the layer or distribution of negatively charged ions (-) of each set 1006, 1008 of ions concentrated within the encapsulation material 904 is spaced closer to the semiconductor die 1002 than the corresponding layer or distribution of positively charged ions (+). Other ion concentration profiles are also contemplated. For example, one set of concentrated ions within the encapsulating material 1004 may have a layer or distribution of positively charged ions (+) stacked above a layer or distribution of negatively charged ions (-) and another set of concentrated ions within the encapsulating material 1004 may have a layer or distribution of negatively charged ions (-) stacked above the layer or distribution of positively charged ions (+). There may be different ions with different mobilities, e.g. more than one ion or the same atom/molecule with different charge states. Generally, the number and orientation of each set of concentrated ions included in the encapsulating material 1004 depends on the number and type of voltage polarity switching points (+ to-or-to +) performed during each instance of the ion manipulation method.

Fig. 15A-15C illustrate embodiments of removing one or more sets of concentrated ions within an encapsulation material that encapsulates a semiconductor device. Each set of concentrated ions is generated using the ion manipulation methods described herein. Packaged semiconductor device 1100 includes a semiconductor die 1102 and an encapsulant 1104 in contact with semiconductor die 1102. Packaged semiconductor device 1100 may include more than one semiconductor die 1102. For ease of illustration only, one semiconductor die 1102 is shown in fig. 15A-15C.

Fig. 15A shows a packaged semiconductor device 1100 having two sets of concentrated ions 1106, 1108 within an encapsulating material 1104. In general, the ion manipulation methods described herein can produce more or fewer sets of concentrated ions within the encapsulating material 1104, the number and (+/-) orientation of which depends on the voltage polarity and the number of voltage polarity switching points performed during each instance of the ion manipulation method.

Fig. 15B shows the packaged semiconductor device 1100 after the uppermost group 1108 of concentrated ions within the encapsulation material 1104 has been removed by thinning the encapsulation material 1104 (e.g., by etching, grinding, leaching, etc.). Alternatively, the encapsulation material 1104 may be selectively etched to remove only ions of the critical ion species without having to thin the entire device. In yet another embodiment, a specific chemical reaction may be applied to the encapsulating material 1104 to remove ions that are rigidly bound to the outer region of the encapsulating material 1104.

Fig. 15C shows the packaged semiconductor device 1100 after all sets of concentrated ions 1106, 1108 within the encapsulation material 1104 have been removed by thinning the encapsulation material 1104 (e.g., by etching, grinding, leaching, etc.). Thus, the final packaged semiconductor device 1100 may include zero, one, or more sets of concentrated ions within the encapsulation material 1104 of the packaged semiconductor device 1100. Each set of concentrated ions included within the encapsulation material 1104 that ultimately encapsulates the semiconductor device 1100 may have a layer or distribution with positive (+) or negative (-) ions stacked on a layer or distribution of opposite ion types. Each set of ions may be concentrated in less critical areas of the encapsulation material 1104 that have less of an impact on the electrical parameters and functionality of the semiconductor die 1102 in contact with the encapsulation material 1104.

Fig. 16 illustrates an embodiment of a packaged semiconductor device 1200 processed with the ion manipulation methods described herein. Packaged semiconductor device 1200 includes a semiconductor die 1202 and an encapsulant 1204 in contact with semiconductor die 1202. Packaged semiconductor device 1200 may include more than one semiconductor die 1202. For ease of illustration only, one semiconductor die 1202 is shown in fig. 16.

The packaged semiconductor device 1200 also includes an absorbing structure 1206, such as a layer added to the encapsulation material 1204, a surface structure of the encapsulation material 1204 having an increased roughness, a treated surface of the encapsulation material 1204, and so forth. The absorbing structure 1206 absorbs or traps ion concentrations 1208, 1210 displaced from the surface of the semiconductor die 1202 by ion manipulation methods. The absorbent structure 1206 prevents or at least reduces migration of the ion concentrations 1208, 1210 after final curing of the encapsulation material 1204. Additionally or alternatively, ionic contamination within the encapsulating material 1204 may be further mitigated by cleaning, etching, leaching, etc. of the encapsulating material 1204.

Spatially relative terms, such as "below," "lower," "above," "upper," and the like, are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations, including orientations other than those illustrated in the figures. Furthermore, terms such as "first," "second," and the like, are also used to describe various elements, regions, sections, etc., and are not intended to be limiting. Like terms refer to like elements throughout the description.

As used herein, the terms "having," "containing," "including," "comprising," and the like are open-ended terms that indicate the presence of stated elements or features, but do not exclude additional elements or features. The articles "a" and "an" are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

With the above range of variations and applications in mind, it should be understood that the present invention is not limited by the foregoing description, nor is it limited by the accompanying drawings. Rather, the present invention is limited only by the following claims and their legal equivalents.