Abstract
A semiconductor device has a substrate and first and second electrical component disposed over the substrate. A first metal bar is disposed over the substrate between the first electrical component and second electrical component. The first metal bar is formed by disposing a mask over a carrier. An opening is formed in the mask and a metal layer is sputtered over the mask. The mask is removed to leave the metal layer within the opening as the first metal bar. The first metal bar can be stored in a tape-and-reel.
Claims
1. A method of making a semiconductor device, comprising: providing a substrate; disposing a first electrical component over the substrate; disposing a second electrical component over the substrate; and disposing a first metal bar over the substrate between the first electrical component and second electrical component.
2. The method of claim 1, further including forming the first metal bar by: providing a carrier; disposing a mask over the carrier; forming an opening in the mask; sputtering a metal layer over the mask; and removing the mask to leave the metal bar on the carrier.
3. The method of claim 2, further including using a pick and place process or device to move the first metal bar from the carrier to a tape-and-reel storage.
4. The method of claim 1, further including disposing a second metal bar over the substrate with the first electrical component between the first metal bar and second metal bar.
5. The method of claim 4, further including disposing a third metal bar and fourth metal bar over the substrate with the first electrical component between the third metal bar and fourth metal bar.
6. The method of claim 1, further including disposing a second metal bar over the substrate, wherein a length of the second metal bar is different from a length of the first metal bar.
7. A method of making a semiconductor device, comprising: providing an electrical component; and disposing a first metal bar adjacent to the electrical component.
8. The method of claim 7, further including disposing a second metal bar adjacent to the electrical component.
9. The method of claim 8, further including disposing a third metal bar and fourth metal bar adjacent to the electrical component, wherein the first metal bar, second metal bar, third metal bar, and fourth metal bar in combination substantially surround the electrical component.
10. The method of claim 8, wherein a length of the second metal bar is different from a length of the first metal bar.
11. The method of claim 7, further including forming the first metal bar by: forming an opening in a mask; and sputtering a metal material into the opening.
12. The method of claim 7, further including removing the first metal bar from a tape-and-reel storage prior to disposing the first metal bar adjacent to the electrical component.
13. The method of claim 7, further including disposing the first metal bar using a pick-and-place nozzle.
14. A semiconductor device, comprising: a substrate; a first electrical component disposed over the substrate; a second electrical component disposed over the substrate; and a first metal bar disposed over the substrate between the first electrical component and second electrical component.
15. The semiconductor device of claim 14, further including a second metal bar disposed over the substrate adjacent to the first electrical component.
16. The semiconductor device of claim 15, wherein a length of the second metal bar is different from a length of the first metal bar.
17. The semiconductor device of claim 15, wherein a length of the second metal bar is the same as a length of the first metal bar.
18. The semiconductor device of claim 15, further including a third metal bar and fourth metal bar disposed over the substrate, wherein the first metal bar, second metal bar, third metal bar, and fourth metal bar in combination substantially surround the first electrical component.
19. The semiconductor device of claim 14, further including an encapsulant deposited over the substrate, first electrical component, second electrical component, and first metal bar.
20. A semiconductor device, comprising: an electrical component; and a first metal bar disposed adjacent to the electrical component.
21. The semiconductor device of claim 20, further including a second metal bar disposed over the substrate adjacent to the electrical component.
22. The semiconductor device of claim 21, wherein a length of the second metal bar is different from a length of the first metal bar.
23. The semiconductor device of claim 21, wherein a length of the second metal bar is the same as a length of the first metal bar.
24. The semiconductor device of claim 21, further including a third metal bar and fourth metal bar disposed over the substrate, wherein the first metal bar, second metal bar, third metal bar, and fourth metal bar in combination substantially surround the electrical component.
25. The semiconductor device of claim 20, further including an encapsulant deposited over the substrate, electrical component, and first metal bar.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIGS. 1a-1c illustrate a semiconductor wafer with a plurality of semiconductor die separated by a saw street;
[0016] FIGS. 2a-2d illustrate using a shielding can for compartment shielding;
[0017] FIGS. 3a-3h illustrate forming metal bars for shielding use;
[0018] FIGS. 4a-4d illustrate packing the metal bars into a tape and reel;
[0019] FIGS. 5a-5h illustrate using the metal bars to form compartment shielding;
[0020] FIGS. 6a and 6b illustrate other embodiments; and
[0021] FIGS. 7a and 7b illustrate integrating the shielded semiconductor packages into an electronic device.
DETAILED DESCRIPTION OF THE DRAWINGS
[0022] The present invention is described in one or more embodiments in the following description with reference to the figures, in which like numerals represent the same or similar elements. While the invention is described in terms of the best mode for achieving the invention's objectives, it will be appreciated by those skilled in the art that it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims and their equivalents as supported by the following disclosure and drawings. The term “semiconductor die” as used herein refers to both the singular and plural form of the words, and accordingly, can refer to both a single semiconductor device and multiple semiconductor devices.
[0023] Rather than using pre-formed cans for compartment shielding as in the prior art, the below disclosure teaches forming compartment shielding out of individual metal bars placed using normal surface mount technology (SMT) processes. FIGS. 3a-3h illustrate a process of forming metal bars to use in compartment shielding. Formation of the metal bars starts in FIGS. 3a and 3b with a base film, substrate, or carrier 200 and a mask layer 202 formed over the carrier. FIG. 3a shows a top-down view and FIG. 3b shows a cross-sectional view of the same process step. Mask 202 can be an adhesive tape disposed over carrier 200 or an insulating or photoresist layer sprayed or otherwise coated onto carrier 200 as a liquid and then cured.
[0024] In FIGS. 3c and 3d, openings 210 are formed in mask 202. FIG. 3c shows a top-down view and FIG. 3d shows a cross-sectional view of the same process step. Openings 210 will define the size and shape of the metal bars being formed. Openings 210 can have any suitable length and width as desired for the metal bars being formed. The footprint of openings 210 defines a length and width of the metal bars, while a thickness of mask 202 defines a height of the metal bars if the openings are completely filled with metal. Openings 210 are formed using a laser cutting tool 212 to burn away portions of mask 202 where openings are desired. Openings 210 are formed using a photolithography process in other embodiments. Openings 210 extend completely through mask 202 to expose carrier 200 under the mask. Any number and size of openings 210 can be formed depending on the size of carrier 200 and the capability of the equipment being used.
[0025] In FIGS. 3e and 3f, a conductive layer 220 is formed over carrier 200 and mask 202, including extending into and completely filing openings 210. FIG. 3e shows a top-down cross-sectional view and FIG. 3f shows a cross-sectional view from the side of the same process step. Conductive layer 220 is formed using any suitable metal deposition technique, e.g., chemical vapor deposition, physical vapor deposition, other sputtering methods, spraying, or plating. Arrows 222 indicate sputtering of metal occurring from the top-down onto carrier 200 and mask 202. The sputtered material can be copper, steel, aluminum, gold, titanium, combinations thereof, or any other suitable conductive material. In some embodiments, conductive layer 220 can be made by sputtering on multiple layers of differing material, e.g., stainless steel-copper-stainless steel or titanium-copper.
[0026] In FIGS. 3g and 3h, mask 202 is removed along with the portions of conductive layer 220 formed on the mask. FIG. 3g shows a top-down view and FIG. 3h shows a cross-sectional view of the same process step. Mask 202 is removed by a chemical solvent dissolving the mask. In other embodiments, mask 202 is removed by peeling or other suitable means. Removing mask 202 leaves metal bars 230 on carrier 200 in substantially the same size and shape as openings 210 were formed. In some embodiments, conductive layer 220 is sputtered with a substantially flat top surface so that the remaining bars 230 have a substantially uniform thickness with the desired height. In other embodiments, conductive layer 220 is backgrinded before or after mask 202 is removed to create bars 230 with a uniform thickness. Metal bars 230 do not necessarily need to have all flat surfaces. Forming metal bars 230 by sputtering allows a smaller bar to be formed compared to conventional metal deposition techniques, which have a minimum wall thickness of around 200 pm. Sputtering allows bars 230 to be formed with a thickness of 80 pm or less.
[0027] FIGS. 4a-4d illustrate packing metal bars 230 into a tape and reel. FIGS. 4a and 4b illustrate an optional initial step of separating bars 230 to make the pick-and-place operation easier. In FIG. 4a, carrier 200 with bars 230 is cut into a plurality of strips 240. In FIG. 4b carrier 200 is optionally further cut into individual units 242. Carrier 200 is cut using a saw blade, laser, or other appropriate cutting tool. The strips 240 or units 242 are spread apart from each other using an expansion table or other suitable means to make bars 230 easier to grab for the pick-and-place equipment.
[0028] FIG. 4c shows a pick-and-place nozzle 250 grabbing a bar 230 off of a strip 240. Nozzle 250 is attached to a vacuum hose and pulls air through an opening in the bottom of the nozzle. When nozzle 250 approaches a bar 230, the bar is attached to the nozzle by the air pressure differential from ambient to within the nozzle. While nozzle 250 holds bar 230, the bar can be moved and rotated by the nozzle to place the bar as desired.
[0029] FIG. 4d shows nozzle 250 moved to place bar 230 into a tape-and-reel storage 260. Tape-and-reel storage 260 includes a carrier tape 262 with a plurality of pockets 264. Each pocket 264 is designed to hold a single bar 230. A cover tape is placed over carrier tape 262 to keep bars 230 in pockets 264 and then the carrier tape is wrapped up around a reel 266. The reel 266, once wrapped with tape 262 to the desired number of units, can be shipped to a customer for use in manufacturing semiconductor packages. Disposing bars 230 onto tape-and-reel storage 260 is optional. In other embodiments, the same manufacturer of semiconductor packages makes bars 230 and then disposes bars 230 directly from strips 240 to a semiconductor package being manufactured.
[0030] FIGS. 5a-5h illustrate using bars 230 to form a compartment shield as part of a semiconductor package 270. FIG. 5a shows a plan view of package 270 with semiconductor die 104a and 104b mounted on substrate 272. Semiconductor die 104a and 104b are simply exemplary components to be shielded from each other. The components on substrate 272 may include discrete active and passive components or any other electrical components instead of or in addition to one of the semiconductor die 104. For instance, semiconductor die 104a may need to be shielded from an RF filter formed from surface mount passive components.
[0031] FIG. 5b shows a cross-sectional view of a bar 230a being disposed over substrate 272 between semiconductor die 104a and 104b. Nozzle 250 can be the same or a different nozzle as shown in FIG. 4c. Nozzle 250 is used to pick up individual bars 230 from strip 240 or tape-and-reel storage 260 and move them into the desired place over package substrate 272. Nozzle 250 can be programmed to dip bars 230 into a solder paste prior to placement of the bars onto substrate 272. Alternatively, solder paste can be printed onto substrate 272 prior to placement of bars 230. The solder paste is later reflowed to mechanically attach bars 230 to substrate 272. Other attachment mechanisms are used between bars 230 and substrate 272 in other embodiments. FIG. 5c shows bar 230a placed in plan view.
[0032] In FIG. 5d, a second bar 230b is picked up using nozzle 250 and placed on the opposite side of semiconductor die 104a from bar 230a. FIG. 5e shows bars 230a and 230b placed in plan view. FIG. 5f shows a third bar 230c being placed. Nozzle 250 can be rotated in addition to moving in the x, y, and z directions. FIG. 5f shows nozzle 250 having been used to turn bar 230c 90 degrees. Bar 230c is placed between bars 230a and 230b on a perpendicular side of semiconductor die 104a.
[0033] FIG. 5g shows a plan view with four bars 230a-230d placed to surround semiconductor die 104a on all four sides. Bars 230a-230d are placed in any suitable order. In one embodiment, bars 230 are placed in a clockwise or counterclockwise fashion, e.g., in the order of bar 230d, 230b, 230c, and finally 230a, instead of placing bars on opposite sides from each other first.
[0034] An encapsulant 280 is deposited over package 270 in FIG. 5h. Encapsulant 280 is optionally backgrinded to expose bars 230 if desired. In some embodiments, packages 270 are formed as a panel and then singulated into the individual units shown in FIG. 5h after encapsulant 280 is deposited. A shielding layer can be formed over encapsulant 280. The shielding layer could be sputtered over package 270 to contact the top surfaces of bars 230 and optionally extend down the sides of the package to contact the sides of substrate 272 including conductive layers formed within the substrate.
[0035] Bars 230a-230d surround semiconductor die 104a and have a similar effect as the can used in the prior art. However, bars 230 are much easier to use and allow for a flexible layout that can be changed without having to manufacture different bars. Forming metal bars 230 by sputtering or spraying metal into mask openings 210 enables formation of bars 230 under 200 μm, which was not feasible in the prior art. Bars 230 are placed using traditional pick-and-place equipment, e.g., the same nozzle 250 that is also used to place semiconductor die 104 and other discrete electrical components onto substrate 272, and therefore can be used in cheaper and simpler manufacturing lines.
[0036] FIGS. 6a and 6b illustrate alternative metal bar embodiments. FIG. 6a shows a package 270a formed with smaller bars 290. Bars 290 have the same thickness and height as bars 230 but have a shorter length. The shorter length of bars 290 allows a single length of bar to be used in a wider variety of situations and to make more varied wall shapes. For instance, having three bars 290 on the top and bottom sides of semiconductor die 104a in FIG. 6a allow the length of the bars to correspond more closely to the length of the semiconductor die than the single bar 230 did. Using bars 290 with a shorter length will allow the compartmentalized path to conform to tighter turns or curves.
[0037] In FIG. 6b, shorter bars 290 are used in combination with longer bars 230 to form semiconductor package 270b. Any suitable combination of bars 230 and bars 290 can be used to create a wide variety of compartments within package 270. Metal bars can be formed in any suitable length, width, and height as needed for a particular package or for the desired flexibility in shield shapes. In FIG. 6b, shorter bars 290 are used to form a compartment wall 292 between semiconductor die 104a and 104b splitting package 270 into two areas. Walls 294 extend from wall 292 along the sides of semiconductor die 104a. Two longer bars 230 wouldn't fit between wall 292 and the side of package 270, so utilizing shorter bars 290 in combination with the longer bars 230 provides a more complete shielding. A compartment 296 is completely separated from both semiconductor die 104a and 104b by walls 292 and 294, and may include additional active or passive components mounted onto substrate 272.
[0038] FIGS. 7a and 7b illustrate incorporating the above-described semiconductor packages, e.g., package 270, into an electronic device 340. FIG. 7a illustrates a partial cross-section of package 270 mounted onto a printed circuit board (PCB) or other substrate 342 as part of electronic device 340. Bumps 346 are formed on the bottom of substrate 262 during manufacturing, in a similar process to bumps 112 being formed on die 104, and then reflowed onto conductive layer 344 of PCB 342 to physically attach and electrically connect package 270 to the PCB. In other embodiments, thermocompression or other suitable attachment and connection methods are used. In some embodiments, an adhesive or underfill layer is used between package 270 and PCB 342. Semiconductor die 104 are electrically coupled to conductive layer 344 through substrate 262.
[0039] FIG. 7b illustrates electronic device 340 including PCB 342 with a plurality of semiconductor packages mounted on a surface of the PCB, including package 270. Electronic device 340 can have one type of semiconductor package, or multiple types of semiconductor packages, depending on the application. Electronic device 340 can be a stand-alone system that uses the semiconductor packages to perform one or more electrical functions. Alternatively, electronic device 340 can be a subcomponent of a larger system. For example, electronic device 340 can be part of a tablet computer, cellular phone, digital camera, communication system, or other electronic device. Electronic device 340 can also be a graphics card, network interface card, or another signal processing card that is inserted into a computer. The semiconductor packages can include microprocessors, memories, ASICs, logic circuits, analog circuits, RF circuits, discrete active or passive devices, or other semiconductor die or electrical components.
[0040] In FIG. 7b, PCB 342 provides a general substrate for structural support and electrical interconnection of the semiconductor packages mounted on the PCB. Conductive signal traces 344 are formed over a surface or within layers of PCB 342 using evaporation, electrolytic plating, electroless plating, screen printing, or other suitable metal deposition process. Signal traces 344 provide for electrical communication between the semiconductor packages, mounted components, and other external systems or components. Traces 344 also provide power and ground connections to the semiconductor packages as needed.
[0041] In some embodiments, a semiconductor device has two packaging levels. First level packaging is a technique for mechanically and electrically attaching the semiconductor die to an intermediate substrate. Second level packaging involves mechanically and electrically attaching the intermediate substrate to PCB 342. In other embodiments, a semiconductor device may only have the first level packaging where the die is mechanically and electrically mounted directly to PCB 342.
[0042] For the purpose of illustration, several types of first level packaging, including bond wire package 346 and flipchip 348, are shown on PCB 342. Additionally, several types of second level packaging, including ball grid array (BGA) 350, bump chip carrier (BCC) 352, land grid array (LGA) 356, multi-chip module (MCM) 358, quad flat non-leaded package (QFN) 360, quad flat package 362, and embedded wafer level ball grid array (eWLB) 366 are shown mounted on PCB 342 along with package 270. Conductive traces 344 electrically couple the various packages and components disposed on PCB 342 to package 270, giving use of the components within package 270 to other components on the PCB.
[0043] Depending upon the system requirements, any combination of semiconductor packages, configured with any combination of first and second level packaging styles, as well as other electronic components, can be connected to PCB 342. In some embodiments, electronic device 340 includes a single attached semiconductor package, while other embodiments call for multiple interconnected packages. By combining one or more semiconductor packages over a single substrate, manufacturers can incorporate pre-made components into electronic devices and systems. Because the semiconductor packages include sophisticated functionality, electronic devices can be manufactured using less expensive components and a streamlined manufacturing process. The resulting devices are less likely to fail and less expensive to manufacture resulting in a lower cost for consumers.
[0044] While one or more embodiments of the present invention have been illustrated in detail, the skilled artisan will appreciate that modifications and adaptations to those embodiments may be made without departing from the scope of the present invention as set forth in the following claims.
