Integrated circuit device with package of deformable cover and related methods

Abstract

A packaged integrated circuit device includes a substrate having a top surface and a bottom surface; a chip mounted on the top surface of the substrate; a cover including a central region and a peripheral region; wherein the central region comprises the deformable film over the die, and the peripheral region is attached to a top surface of the substrate, and wherein the deformable film in the central region is recessed toward the substrate. The invention further discloses a corresponding manufacturing method.

Description

Technical Field

[0001] The present invention relates to integrated circuit (IC) device packaging, and more particularly to a lid attached to a packaging substrate for packaging an integrated circuit (IC) device. Background Art

[0002] Figure 1A A cross-sectional side view of a conventional IC package 100 is shown. Figure 1B A top view of a conventional IC package 100 with the lid removed is shown. The IC package 100 includes a substrate 102 having a bottom surface 104 and a top surface 106. A conventional metal lid 108, consisting of a top 110, sidewalls 112, and ends 114. The lid 108 is attached to the top surface 106. The substrate 102 is formed by a bonding layer 120. A semiconductor die 116 is mounted on the substrate 102. The bonding layer 120 is discontinuous and the IC package 100 has some gaps 118 between the ends 114 of the lid 108 and the substrate 108 to allow gases to escape during package assembly and assembly or mounting of the packaged IC to a printed circuit board (not shown), which typically occurs during the solder reflow process.

[0003] However, moisture from the outside can also penetrate into the internal cavity of the package body 100 through these gaps 118. For example, after the cover 108 is attached to one side of the substrate, solder balls (not shown) are attached to the bottom side 104 of the substrate 102, and then a water washing process is performed to remove the flux used in the solder ball attachment process. Due to the gaps 118, water may enter the package. Moisture inside the IC package 100 will reduce the reliability level of the package.

[0004] Therefore, there is a need for an integrated circuit package that provides a substantially sealed environment to prevent water from entering the package and to relieve gas pressure in the package. Summary of the invention

[0005] This Summary provides a selection of concepts in simplified form that will be described in detail in the Detailed Description. This Summary is not intended to identify key features or essential features of the subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0006] According to one aspect of the present invention, a packaged integrated circuit device is provided. The packaged integrated circuit device comprises: a substrate having a top surface and a bottom surface; a die mounted on the top surface of the substrate; a cover comprising a central region and a peripheral region; wherein the central region comprises a deformable membrane over the die, and the peripheral region is attached to the top surface of the substrate, and wherein the deformable membrane in the central region is concave toward the substrate.

[0007] In accordance with one or more embodiments, the deformable membrane is a plastic film.

[0008] According to one or more embodiments, the deformable membrane is coated with a metal layer.

[0009] According to one or more embodiments, the metal layer includes the material tin.

[0010] According to one or more embodiments, the peripheral region comprises a top edge and a side wall connected to the top edge, wherein the top edge and the side wall are both attached to the deformable membrane.

[0011] According to one or more embodiments, the angle between the side wall and the horizontal plane is between 30 degrees and 90 degrees.

[0012] According to one or more embodiments, the side walls are vertical walls.

[0013] According to one or more embodiments, the peripheral region includes an end portion attached to a top surface of the substrate.

[0014] According to one or more embodiments, the end portion has two ends, and wherein a proximal end of the end portion close to the tube core is connected to the side wall.

[0015] According to one or more embodiments, the end portion has two ends, and wherein a distal end of the end portion away from the die is connected to the sidewall.

[0016] In accordance with one or more embodiments, the sidewall is attached to a top surface of the substrate.

[0017] In accordance with one or more embodiments, the die comprises a flip chip.

[0018] According to a second aspect of the present invention, there is provided a cover for attachment to a packaging substrate, the cover comprising: a central region; a peripheral region around the central region; wherein the central region comprises a deformable membrane, and wherein the deformable membrane in the central region is concave toward the substrate.

[0019] In accordance with one or more embodiments, the deformable membrane is a plastic film.

[0020] In accordance with one or more embodiments, the deformable membrane is coated with a metal layer.

[0021] According to one or more embodiments, the metal layer includes the material tin.

[0022] According to one or more embodiments, the peripheral region includes a top edge connected to the deformable membrane, a sidewall connected to the top edge, and an end connected to the sidewall, wherein the end of the peripheral region is configured to be attached to the packaging substrate.

[0023] According to a third aspect of the present invention, there is provided a method for manufacturing a cover for attachment to a package substrate. The method comprises: (a) providing a metal frame; (b) providing a deformable membrane; (c) laminating the metal frame with the deformable membrane to form a membrane-metal frame; (d) deforming the membrane-metal frame to form a cover having a central region and a peripheral region, wherein the central region comprises the deformable membrane above the die and the peripheral region is attached to the substrate, and wherein forming the cover comprises forming the deformable membrane concave downward in the central region.

[0024] According to one or more embodiments, the method further comprises coating the deformable membrane in the central region with a metal layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to be able to understand in detail the manner of the above-mentioned features of the present application, a more specific description of the present application can be obtained by reference to the embodiments, some of which are shown in the accompanying drawings. It will be noted, however, that the accompanying drawings only show typical embodiments of the present application and are therefore not considered to be limiting of the scope, as the present application may have other equally effective embodiments. It should be understood that the accompanying drawings are only schematic and are not drawn to scale. The advantages of the claimed subject matter will be apparent to those skilled in the art upon reading this specification and the resulting accompanying drawings, in which reference numerals are used to represent elements such as:

[0026] Figure 1A is a cross-sectional side view of a conventional IC package;

[0027] Figure 1B is a top view of a conventional IC package after removing a cover;

[0028] Figure 2A is a cross-sectional side view of an IC package according to an embodiment of the present invention;

[0029] Figure 2B is a top view of an IC package with a cover removed according to an embodiment of the present invention;

[0030] Figure 3A-Figure 6B It is a main process diagram showing the manufacturing process of the cover;

[0031] Figure 7 is an example flow chart of a process for manufacturing a cover according to one embodiment of the present invention;

[0032] Figure 8 is an example flow chart of a process for manufacturing a packaged semiconductor device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0033] Figure 2A A cross-sectional side view of an IC package 200 is shown in accordance with one embodiment of the present invention. Figure 2B A top view of IC package 200 is shown after the cover is removed. IC package 200 includes a substrate 202 having a bottom surface 204 and a top surface 206. Typically, for rectangular shaped devices, the substrate includes a rectangular shape. Package contact pads (not shown) are disposed on bottom surface 204. The package contact pads may include spherical structures or balls arranged in a grid pattern to form a ball grid array BGA. For example, the balls contain solder. Various types of solder may be used, such as lead-based, non-lead-based alloys, or conductive polymers. The package contact pads may be arranged in other patterns or other types of package contact pads may be used.

[0034] Semiconductor die 216 is mounted on top surface 206 of substrate 202. The die can be any type of IC. For example, the IC can be a memory device such as dynamic random access memory (DRAM), static random access memory (SRAM), digital signal processor (DSP), microcontroller, system on chip, etc. As with other types of devices. Die 216 is connected to the substrate by wire bonding or tape automated bonding.

[0035] In some embodiments, the tube core 216 is in the form of a flip chip. In the flip chip configuration, the tube core 216 is oriented so that the active surface 218 faces downward toward the substrate 202. Conductive bumps 220 are arranged on the active surface 218 of the tube core 216 to attach the tube core to the upper surface 206 of the substrate 202. The conductive bumps include solder bumps, for example. Various types of solder, such as lead-based, non-lead-based alloys or conductive polymers, can be used to form conductive bumps. The tube core contact pads (not shown) are arranged on the top surface of the substrate. The tube core contact pads are connected to the package contact pads by conductive traces (not shown). When the tube core is mounted on the substrate, the bumps match the tube core contact pad pads. The solder paste melts during the assembly process and forms a connection between the pads of the chip and the conductive bumps during the reflow process.

[0036] An underfill 222, such as epoxy, may be provided under the die to seal the conductive bumps and improve reliability. Various techniques may be used to provide the underfill in the cavity. For example, the underfill may be needle-dispensed along the edge of the chip and drawn into the space between the chip and the substrate by capillary action and cured to form a permanent bond. Other techniques may also be used, such as moldable underfills for applying the underfill.

[0037] Provide lid 208 to include central area 232 and peripheral area 234. Central area 232 includes film 228. Film 228 is deformable or elastic. As shown, in normal state or configuration, film 228 in central area 232 is usually curved downward toward substrate 202, because at room temperature, the center of film is deformed inward or downward toward tube core. That is to say it is concave toward substrate. Peripheral area 234 includes top edge 226 attached to film 228, sidewall 216 connected to film 228 and peripheral edge or end 230 connected to sidewall 216. Figure 2A It is not shown how the film is attached to the top edge - this will be discussed in more detail below. The peripheral area of ​​the cover is generally or substantially metallic. Specifically, the top edge 226, the side wall 216 and the end 230 can be made of a high thermal conductivity material, such as tin, copper, aluminum or a metal composite material. In one embodiment, the side wall 216 is a vertical wall. In other embodiments, the side wall is inclined so that the angle between the side wall 216 and the horizontal plane can be between 30 degrees and 90 degrees.

[0038] Conventional covers are typically homogeneous structures, or are composed of a single material, such as tin, copper, and the like. According to an embodiment of the present disclosure, the film 228 of the cover 208 is composed of a material different from the material of the edge and side walls of the cover. In a preferred embodiment, the material is one of the material categories generally referred to as "plastic" or "plastic family". Specifically, the material may be PO, EVA, PET, and the like, and the thickness of the film 228 may be in the range of 5 μm to 20 μm. The film 228 may be printed, or otherwise covered, coated, or protected by a very thin thickness of a metal material (typically in the range of 1-5 μm) to mitigate damage from the external environment. The metal coating may be located on the outer surface of the film (i.e., the surface away from the mold), or on the inner surface, or on both. In one embodiment, the printed metal layer comprises material tin because tin has good elastic properties.

[0039] As will be discussed in more detail below, the membrane 228 is attached ( Figure 2A The membrane 228 is formed to be concave or concave under normal conditions such as room temperature and atmospheric pressure to form the center of the cover 208. The membrane 228 is concave downward. This may be due in part to the weight of the membrane and may be due in part to the pre-molding of the membrane into a concave configuration. During the solder reflow process, the membrane will deform upward, and particularly when the air pressure within the package increases, the membrane may "pop" upward. The upward deformation or even popping of the membrane generally serves to release the air pressure within the package, which may also reduce damage to the substrate. In some embodiments, the membrane 228 is attached only to the inner surface of the edge 228. The skilled person will appreciate that in some other embodiments, the membrane 228 is attached to the inner surfaces of the edge 228, the sidewall 216, and the end 230. The membrane attached to the inner surface of the edge or sidewall or end is not in the Figure 2A Shown in.

[0040] The end 230 of the cover 208 is connected to the substrate 202 by a bonding layer 236. The bonding layer 236 is typically an adhesive layer. Figure 2B As shown, the bonding layer 236 is continuous. That is, there is no gap therebetween. The peripheral edge or end 230 of the cover 208 contacts the bonding layer 236 on the upper surface of the substrate 202, thereby forming a substantially sealed cavity 224 around the tube core, so that there is no gap in the connection between the periphery of the cover 208 and the substrate 202. The cover can be of any shape as long as it can be properly adapted to the cavity of the IC package. The connection without a gap between the cover and the substrate provides a sealed environment, or a substantially sealed environment, which prevents external water, moisture or other fluids from entering the package during the solder ball reflow process after flux cleaning. The upward deformation of the film can relieve the thermal pressure inside the package during the heating of the solder reflow process because the deformation of the film can expand the internal space to relieve the air pressure.

[0041] It should be noted that as used herein, the term "package" includes a substrate and a lid, while the term "packaged integrated circuit (IC) device" includes the package with all of its constituent components as well as the die mounted within the package.

[0042] The cover 208 of the preferred embodiment can be formed by any of a variety of methods. The details of the manufacturing method of the cover according to one or more embodiments of the present invention are described below. The process of manufacturing the cover can adopt multiple steps, including blanking, stamping, perforating, deburring, cleaning, electroplating, inspection, lamination and stamping, etc. In short, these steps convert raw materials from different sources, such as tin coils and films, into finished parts. One or more of these steps, such as cleaning and inspection steps, can be repeated during the manufacturing process. Although tin coils or metal strips are referred to as raw materials in this process description, it should be understood that tin can be replaced by another suitable thermally conductive material.

[0043] refer to Figure 3A and Figure 3B , the first major step in the manufacturing process of making the cover may be to form a metal frame, such as the metal ring 338 shown, from the metal strip. Figure 3A A top view of the metal ring 338 is shown, Figure 3B A top view of the metal ring 338 is shown. This first major step may be performed using an etching process or a stamping process to form the metal ring 338. In other embodiments, the metal frame may be formed into other shapes, such as a rectangular shape with a cavity in the center.

[0044] Please continue to refer to Figure 4A and Figure 4B The second major step in the manufacturing process of making the cover is to form the membrane into the appropriate shape. Figure 4A A top view of the membrane 440 is shown, Figure 4B A side view of a membrane 440 is shown. The membrane 440 is a membrane which may be a plastic material. This second step may be accomplished using, for example, a stamping process to produce a ring as shown or other shapes (eg, a rectangle for a rectangular cover).

[0045] Please continue to refer to Figure 5 The third major step in the manufacturing process of manufacturing the cover is to laminate the metal ring 338 with the plastic film 440 to form a film-metal ring 542 by firmly attaching the film 338 to the metal ring 440. The third step can be completed using a stamping process or a curing process. Those skilled in the art will understand that in Figure 5 In the illustrated embodiment, the perimeter of the membrane 440 is aligned with the perimeter of the metal frame or ring 338. However, according to other embodiments, the horizontal dimension of the membrane 440 may be smaller than the dimension of the outer area of ​​the metal frame or ring 338, but larger than the area of ​​the hole or annulus in the metal frame or ring 338 to ensure that the components at least partially overlap to allow bonding therebetween.

[0046] refer to Fig. 6A and Figure 6B The fourth major step in the manufacturing process of making the cover is to stamp or press the film-metal frame, thereby deforming it to form a cover with a concave film in the center 608. This fourth step can be accomplished using a pressing process. Fig. 6A A side view of a film-metal frame forming a cover by a molding tool or press is shown, where the molding tool 644 has been partially closed so that the lower portion of the molding tool (also called a press) is in contact with the film-metal ring 542. Figure 6B is a side view showing the cover after deformation. Fig. 6A , Figure 6B As shown, by using a press 644, a deformation in a vertical direction is formed between the metal portion 646 and the film 440. Fig. 6A and Figure 6B As shown, according to one or more embodiments, metal portion 646 is pressed downward and forms edge 626, sidewall 616, and peripheral edge or end 630, the portion of membrane 440 located in central region 632 of membrane-metal ring 542 is pressed downward to form concave membrane 648, and the portion of membrane 440 attached to metal portion 646 is pressed to form component 650. Figure 6B As shown, the metal part 646 is pressed to form the edge, the sidewalls, and the ends extending outward from the sidewalls. However, according to other embodiments, the metal part 646 can be pressed to form only the edge 626 and the sidewall 616. In addition, according to other embodiments, the metal part 646 can be pressed to form the edge, the sidewalls, and the ends extending inward from the sidewalls.

[0047] The fifth major step in the lid manufacturing process is to deburr, clean and dry the lid. After these steps, the lid in an open box shape is placed on the substrate with the opening facing downward. The lid can be bonded to the semiconductor substrate by an adhesive layer. The adhesive layer can be placed on certain parts of the lid, or on the substrate, or on both to facilitate bonding with the encapsulated substrate.

[0048] At room temperature, the membrane bends downward. As the temperature rises, the film deforms or pops out to reduce the pressure within the cavity formed between the cover and the substrate, thereby relieving the pressure and reducing the mechanical load on the joint between the cover and the substrate. This ensures that there is no gap in the connection between the cover and the substrate while reducing the possibility of mechanical failure.

[0049] Continue to refer Figure 7 , Figure 7 An example flow chart sequence 700 of a manufacturing process for a lid attached to a package substrate is shown. The process begins at step 702, where a metal frame is provided. At step 704, a deformable membrane is provided. At step 706, the metal frame is laminated with an elastic membrane to form a membrane-metal frame. At step 708, the membrane-metal frame is deformed to form a lid having a central region and a peripheral region. The central region includes the deformable membrane over the die, while the peripheral region is attached to the substrate. Forming the lid includes forming a membrane that is concave downward in the central region.

[0050] Reference now Figure 8 , Figure 8 An example flow chart 800 of a manufacturing process for a package according to one embodiment of the present invention is shown. The process begins at step 802 by assembling a substrate array by attaching a plurality of integrated circuit dies in an array or matrix pattern to a package substrate array using a flip chip attach method. At step 804, a lid array having a plurality of lids is assembled to align with the substrate array. At step 806, solder ball conductors may be attached to the substrate. Finally, at step 808, the lidded substrate array may be singulated into individual packaged integrated circuit devices, such as by singulation using a saw.

[0051] The use of the terms "a" and "an" and "the" and similar indicators in the context of describing the subject matter (especially in the context of the attached claims) should be interpreted as covering the singular and the plural unless otherwise specified herein or clearly contradicted by the context. Unless otherwise specified herein, the enumeration of numerical ranges herein is intended only to be used as a shorthand method of referring to each individual value falling within the range individually, and each individual value is incorporated into the specification as if it were individually cited herein. In addition, the foregoing description is for illustrative purposes only, not for limiting purposes, because the scope of protection sought is defined by the claims set forth below and any equivalents to which they are entitled. The use of any and all examples or exemplary language (e.g., "such as") provided herein is intended only to better illustrate the subject matter and does not constitute a limitation on the scope of the subject matter, unless otherwise required. The use of the term "based on" and other similar phrases in the claims and description of the specification to indicate the conditions for producing a result is not intended to exclude any other conditions for producing the result. Any language in the specification should not be interpreted as indicating that any unclaimed element is necessary for the practice of the claimed application.

[0052] Preferred embodiments are described herein, including the best modes known to the inventor for implementing the claimed subject matter. Of course, variations of these preferred embodiments will become apparent to those of ordinary skill in the art upon reading. Those skilled in the art appropriately use these variations, and the inventor intends to implement the claimed claims in different ways as specifically described herein. Therefore, the claimed subject matter includes all modifications of the subject matter described in the claims and their equivalents as permitted by applicable law. In addition, unless otherwise noted or explicitly refuted herein, the combination of the above-described elements in all possible variations is encompassed herein.

Claims

1. A packaged integrated circuit device comprising: a substrate having a top surface and a bottom surface; a die mounted on a top surface of the substrate; Cover, including central and peripheral areas; Wherein the central region comprises a deformable membrane over the die, and the peripheral region is attached to the top surface of the substrate, and wherein the deformable membrane in the central region is concave toward the substrate. 2 . The packaged integrated circuit device of claim 1 , wherein the deformable film is a plastic film. 3 . The packaged integrated circuit device of claim 1 , wherein the deformable membrane is coated with a metal layer. The packaged integrated circuit device of claim 1 , wherein the metal layer comprises the material tin. 5 . The packaged integrated circuit device of claim 1 , wherein the peripheral region comprises a top edge and a sidewall connected to the top edge, wherein the top edge and the sidewall are both attached to the deformable membrane. 6 . The packaged integrated circuit device of claim 5 , wherein the sidewalls are at an angle between 30 degrees and 90 degrees to a horizontal plane. The packaged integrated circuit device of claim 5 , wherein the sidewalls are vertical walls.

8. A cover for attachment to a package substrate, comprising Central area; the peripheral areas surrounding the central area; Wherein the central region comprises a deformable membrane, and wherein the deformable membrane in the central region is concave towards the substrate.

9. A method of manufacturing a cover for attachment to a package substrate, comprising: (a) providing a metal frame; (b) providing a deformable membrane; (c) bonding the metal frame to the deformable membrane to form a membrane-metal frame; (d) deforming the film-metal frame to form a cover having a central region and a peripheral region, wherein the central region includes a deformable membrane over the die and the peripheral region is attached to the substrate, and wherein forming the cover includes forming the deformable membrane concave downward in the central region.

10. The method of claim 9, further comprising coating the deformable membrane in the central region with a metal layer.

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