Encapsulated electronic die with microcavity and method for forming an encapsulated electronic die with microcavity

Abstract

An encapsulated electronic die having a microcavity and a method for forming the encapsulated electronic die. The encapsulated electronic die includes a photoresist frame secured to the electronic die and extending completely around the device. The photoresist frame is also secured to a first major surface of a substrate so as to form an enclosure around the device. An encapsulant material is on the electronic die and extends around the sides of the electronic die. The encapsulant material contacts the first major surface of the substrate around the entire periphery of the electronic die so as to form a seal around the electronic die.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 62 / 913,129, filed on October 9, 2019, the contents of which are incorporated by reference in their entirety; and claims priority to U.S. Non-Provisional Patent Application Serial No. 16 / 816,010, filed on March 11, 2020, the contents of which are incorporated by reference in their entirety. Background Art

[0003] Surface acoustic wave (SAW) components require an encapsulation that leaves the surface of the SAW device uncovered and keeps the surface of the SAW device clean and dry. Otherwise, the microacoustic waves will attenuate. Therefore, SAW components typically include a sealed cavity that exposes the interior of the SAW device. Microelectromechanical systems (MEMS) and bulk acoustic wave (BAW) components also require an internal sealed cavity for the corresponding devices thereon.

[0004] Conventional processes for forming packages of SAW, BAW or MEMS components with internal sealed cavities apply a spherical top sealing material to a carrier substrate, where the sealing structure on the substrate side is such as a solder ring (e.g., Au / Sn solder ring), a protective foil, a buffer layer at the edge of the chip, or a metal shield to prevent the spherical top sealing material from entering the cavity. One problem with these conventional processes is that the spherical top material can enter the cavity and damage the SAW, MEMS or BAW device. Moreover, conventional processes using solder rings, protective foils, buffer layers at the edge of the chip and metal shields are expensive.

[0005] Therefore, there is a need for a method and apparatus that will provide good sealing of devices requiring a sealed cavity at reduced cost. Summary of the invention

[0006] An apparatus is disclosed, the apparatus comprising a substrate; an electronic die having a device formed thereon; and a photoresist frame secured to the electronic die and extending completely around the device. The photoresist frame is secured to a first major surface of the substrate so as to form an enclosure around the device. The apparatus also includes an encapsulant material extending over the electronic die and around the sides of the electronic die such that the encapsulant material contacts the first major surface of the substrate around the entire periphery of the electronic die so as to form a seal around the electronic die.

[0007] A method for forming an encapsulated electronic die using a substrate and a device wafer is disclosed. The method includes depositing a first metal layer on the device wafer; forming a plurality of bonding pads on the device wafer; depositing a photoresist layer on the device wafer; patterning the photoresist layer to form a photoresist frame that completely surrounds the device; depositing conductive balls on the bonding pads; cutting the wafer to form the electronic die; and placing the electronic die on the substrate. The method also includes heating and pressing the conductive balls so that each conductive ball is coupled to one of the bonding pads on the wafer and to the substrate, the heating and pressing causing the electronic die to move closer to the substrate so that the photoresist frame is in direct contact with the substrate or with a landing pad formed on the substrate; depositing an encapsulant material so that the encapsulant material covers the electronic die and the substrate; curing the encapsulant material to encapsulate the electronic die; and cutting the substrate to separate the encapsulated electronic die.

[0008] The method and apparatus of the present invention produce a microcavity that exposes the device within the cavity. The encapsulant material ensures that the microcavity is sealed, protecting the device from moisture and contaminants. Because the method and apparatus of the present invention do not require solder rings, protective foils, buffer layers at the chip edge or metal shields, in many cases, it is less expensive than prior art processes. In addition, the photoresist frame is effective in sealing the microcavity, thereby preventing or reducing the intrusion of the ball top material into the cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The invention will be explained in more detail below with reference to examples and with reference to the accompanying drawings in which is shown. It should be understood that the drawings are not drawn to scale.

[0010] Figure 1 is a block diagram illustrating a method for forming an encapsulated electronic die having a microcavity according to an example of the present invention.

[0011] Figure 2 is a diagram showing a cross-sectional view of a portion of a device wafer after metal layers have been deposited and patterned to form bond pads and metal regions extending completely around the device in accordance with an example of the present invention.

[0012] Figure 3 is an example showing an example according to the present invention Figure 2 FIG. 1 is a diagram of a cross-sectional view of a portion of a device wafer shown in FIG. 1 after a photoresist layer has been deposited and patterned to form a photoresist frame covering the metal areas and completely surrounding the device.

[0013] Figure 4 is an example showing an example according to the present invention Figure 3FIG. 4 is a diagram of a cross-sectional view of a portion of a device wafer shown in FIG. 4 after conductive balls have been deposited on bond pads.

[0014] Figure 5 is an example showing an example according to the present invention Figure 4 FIG. 4 is a diagram of a cross-sectional view of a portion of a device wafer shown in FIG. 4 after the wafer has been diced to form individual die.

[0015] Figure 6 is a diagram showing a top view of an electronic die according to an example of the present invention;

[0016] Figure 7 is a diagram showing a side cross-sectional view of a substrate assembly according to an example of the present invention.

[0017] Figure 8 is an example showing an example according to the present invention Figure 7 FIG. 1 is a diagram of a top view of a baseboard assembly.

[0018] Fig. 9 is an example showing an example according to the present invention Figures 7 and 8 FIG. 1 is a top view of a substrate assembly after an electronic die has been placed on the substrate and a bonding process has been performed to bond the die to the substrate.

[0019] Fig.10 is an example showing an example according to the present invention Fig. 9 FIG. 1 is a side cross-sectional view of a baseplate assembly.

[0020] Fig.11 is an example showing an example according to the present invention Fig.10 FIG. 1 is a side cross-sectional view of the substrate assembly after the globular top encapsulant material has been deposited.

[0021] Fig.12 is an example showing an example according to the present invention Fig.11 FIG. 1 is a side cross-sectional view of a substrate assembly after a dicing process has been performed to separate the individual encapsulated electronic dies.

[0022] Fig.13 is a diagram showing a top view of an electronic die according to an example of the present invention, and shows an example in which the device is a SAW device.

[0023] Fig.14 is a diagram showing an example according to the present invention Figure 1 FIG. 1 is a side cross-sectional view of a method in which a landing pad is not formed on a substrate.

[0024] Fig.15 is an example showing an example according to the present invention Fig.14 FIG. 1 is a side cross-sectional view of a substrate assembly after encapsulant material has been deposited.

[0025] Fig.16 is an example showing an example according to the present invention Fig.15 FIG. 1 is a side cross-sectional view of a substrate assembly after a dicing process has been performed to separate the individual encapsulated electronic dies.

[0026] Fig.17 is a diagram showing a cross-sectional view of a portion of a device wafer after a metal layer has been deposited and patterned to form bond pads according to an example of the present invention.

[0027] Fig.18 is an example showing an example according to the present invention Fig.17 FIG. 1 is a diagram of a cross-sectional view of a portion of a device wafer shown in FIG. 1 after a photoresist layer has been deposited and patterned to form a photoresist frame that completely surrounds the device.

[0028] Fig.19 is a diagram showing a side cross-sectional view of a substrate assembly according to an example of the present invention.

[0029] Fig. 20 is an example showing an example according to the present invention Fig.19 FIG. 1 is a side cross-sectional view of a substrate assembly after encapsulant material has been deposited.

[0030] Fig.21 is an example showing an example according to the present invention Fig. 20 FIG. 1 is a side cross-sectional view of a substrate assembly after a dicing process has been performed to separate the individual encapsulated electronic dies.

[0031] Fig. 22 is a diagram showing an example according to the present invention. Figure 1 FIG. 1 is a diagram of a side cross-sectional view of a portion of a method for producing a substrate assembly.

[0032] Fig.23 is an example showing an example according to the present invention Fig. 22 FIG. 1 is a side cross-sectional view of a substrate assembly after encapsulant material has been deposited.

[0033] Fig.24 is an example showing an example according to the present invention Fig.23 FIG. 1 is a side cross-sectional view of a substrate assembly after a dicing process has been performed to separate the individual encapsulated electronic dies. DETAILED DESCRIPTION

[0034] Those of ordinary skill in the art will recognize that the following description is illustrative only and not limiting in any way. Other examples will readily occur to those of ordinary skill in the art.

[0035] Figure 1A method 100 for forming an encapsulated die is shown. A device is formed (101) on a device wafer. Bond pads are formed (102) on the device wafer. Optionally, a first metal layer is deposited on the device wafer and patterned (103) to form a first metal region extending completely around the device. In one example, patterning a first portion of the first metal layer forms a plurality of bond pads, and patterning a second portion of the first metal layer forms a first metal region extending completely around the device. The patterning of step 103 may include depositing a photoresist, exposing the photoresist in a desired pattern, one or more baking steps, photoresist stripping, etching to remove portions of the metal layer not covered by the photoresist, and a resist stripping process.

[0036] exist Figure 2 In the example shown in FIG, a device wafer 1 is shown having a device 4 formed thereon. Steps 102 to 103 pattern the metal layer to form a bonding pad 3 and a first metal region 2 extending completely around the device 4. The bonding pad 3 is electrically coupled to the device 4 to provide input and output to the device 4. The first metal region 2 extends completely around both the device 4 and the bonding pad 3.

[0037] In this example, the metal layer is aluminum or an aluminum alloy. However, alternatively, the bonding pad 3 and / or the first metal region 2 may be copper or a copper alloy, gold or a gold alloy or other metals.

[0038] A photoresist layer is deposited (104) on the device wafer. The photoresist layer is patterned (105) such that a photoresist frame is formed that covers the first metal region 2 and completely surrounds the device 4.

[0039] The photoresist layer can be composed of any photoresist with high durability that allows the formation of thick, high aspect ratio structures (e.g., structures with 15 to 20 microns in width and 16 to 25 microns in height). In a non-limiting example of the present invention, the photoresist is an epoxy-based photoresist, such as SU-8 photoresist (e.g., SU-8 3000) manufactured by Kayaku Microchem and purchased by Microchem Corp, Westborough, Massachusetts. In this non-limiting example, the photoresist layer is deposited by a spin coating process, followed by a soft bake (at 100° C.), exposure through a photomask, a post-exposure bake (65° C. for 1 minute and 95° C.), followed by a development process step (e.g., soaking, spraying, or sprinkling with Micro Chem SU-8 developer, ethyl lactate, or diacetone alcohol) and a final hard bake at 150° C. for 1 hour.

[0040] exist Figure 3 In the example shown in FIG. 1 , steps 104 to 105 form a photoresist frame 6 that directly covers and is directly attached to the metal area 2 covering the device wafer 1. It can be seen that the photoresist frame 6 extends completely around the device 4 and the bonding pad 3. The bottom surface of the photoresist frame 6 is in direct contact with the metal area 2.

[0041] Conductive balls (106) are deposited on the bonding pads. As used in the present invention, the term "bonding pad" includes not only rectangular or circular pads explicitly designated for bonding, but also larger structures having different shapes as long as a portion of such structure is designed to receive conductive balls for connection to other structures.

[0042] exist Figure 4 In the example shown in , step 106 deposits a conductive ball 7 on each bonding pad 3 on the device wafer 1. The conductive ball 7 is coupled to the device 4 and is surrounded by the metal region 2 and the photoresist frame 6. The conductive ball 7 can be gold or a gold alloy and can be deposited using a stud-bump process. In one example, a gold stud-bump process is used to form the gold conductive ball 7. Alternatively, conventional solder materials (e.g., Sn-Pb), lead-free solders (e.g., Sn-Cu, Sn-Ag-Cu, Au-Sn), conductive epoxy, copper, or other conductive materials can be used to form the conductive balls 7. In yet another example, the conductive balls 7 are each conventional solder balls deposited using a conventional solder bump process.

[0043] The device wafer is then diced (107) to form individual electronic dies. Figure 5 The die 10 is shown having been cut to form individual die 10. Figure 4 Each electronic die 10 includes a bonding pad 3, a device 4, a metal region 2, a photoresist frame 6 and a conductive ball 7.

[0044] Figure 6 A top view of an exemplary electronic die 10 is shown after steps 101 to 107 have been performed. The first metal region 2 extends completely around the device 4 and the bond pads 3; and has a width, i.e., a lateral thickness of its constituent parts, which is equal to or greater than the width of the photoresist frame 6 along the entire portion of the metal region 2 covered by the photoresist 6. The width of the first metal region 2 and the width of the photoresist 6 can be kept to a minimum in order to maximize the surface area available for the device 4 or to increase the number of electronic die 10 that can be formed from each device wafer 1.

[0045] The photoresist frame 6 may have a width of 15 to 20 microns and a height of 16 to 25 microns. In one example, the conductive balls 7 are reduced to a thickness of about 16 microns during the heating process, the photoresist frame 6 has a thickness of 16 microns, the first metal region 2 and the bonding pad 3 have a thickness of 1 micron, and the second metal region 13 and the bonding pad 12 have a thickness of 8 microns, thereby giving a microcavity with an exemplary height of 25 microns.

[0046] Device 4 may be any type of semiconductor, electronic or mechanical device that requires an open cavity to operate effectively, and may be a MEMS device (eg, a MEMS switch, a MEMS sensor or a MEMS oscillator), a SAW device or a BAW device.

[0047] Optionally, bonding pads (108) are formed on the substrate by depositing a metal layer on a second major surface of the substrate (e.g., the "bottom surface" of the substrate) and patterning the metal layer (e.g., by thick film printing or by depositing a photoresist, exposing the resist in a desired pattern, one or more baking steps, photoresist stripping, etching to remove portions of the metal layer not covered by the photoresist, and a resist stripping process).

[0048] Optionally, a through hole (109) is formed in the substrate by creating an opening extending through the substrate (e.g., by depositing a photoresist, exposing the photoresist in a desired pattern, one or more baking steps, photoresist stripping, etching to form the opening, and a resist stripping process) and then filling the opening with a conductive material such as, for example, a metal.

[0049] Optionally, 110 bonding pads are formed on a first major surface of the substrate (e.g., the "top surface" of the substrate). Optionally, a landing pad (111) of a photoresist frame is formed on the first major surface of the substrate. In one example, one or more metal layers are deposited on the substrate and patterned to form a second metal region and a third metal region, the second metal region forming the landing pad of the photoresist frame, the third metal region including the bonding pad. In one example, the one or more metal layers are formed by printing a tungsten layer on the substrate, followed by nickel plating and gold plating, forming a three-layer metal region, the three-layer metal region including a tungsten layer covered by a nickel layer, the nickel layer covered by a gold layer. Patterning can include a printing process or depositing a photoresist, exposing the photoresist in a desired pattern, one or more baking steps, photoresist stripping, etching to remove portions of the metal layer not covered by the photoresist, and a resist stripping process.

[0050] Figures 7 and 8An exemplary substrate assembly is shown after forming bonding pads 12 on first major surface 31 of substrate 30, forming bonding pads 16 on second major surface 32 of substrate 30, and through-holes 14 electrically coupled to bonding pads 16 and electrically coupled to bonding pads 12 so that bonding pads 12 are electrically coupled to bonding pads 16 in steps 108 to 111. Substrate 30 may be ceramic. Alternatively, substrate 30 may be a circuit board. Steps 110 to 111 form second metal regions 13 that form landing pads for photoresist frame 6. As shown in FIG. Figure 8 As shown in FIG. 1 , the second metal region 13 extends outside the bonding pad 12 and completely around the bonding pad 12. In this example, the second metal region 13 has a shape corresponding to the shape of the photoresist frame 6.

[0051] The electronic die is placed on a substrate (112). Fig. 9 The placement of the electronic die 10 on the substrate 30 is shown, and the position of the photoresist frame 6 relative to the second metal region 13 is shown. The lateral extent of the second metal region 13 is greater than the lateral extent of the photoresist frame 6, so that the complete lateral extent of the photoresist frame 6 extends within the lateral extent of the second metal region 13.

[0052] A heating process step (113) is performed to heat the conductive balls 7 and apply pressure (114) to the back side of the electronic die 10. Optionally, acoustic energy (115) is applied to perform a thermo-acoustic bonding process. Fig.10 The applied pressure indicated by arrows 62 is combined with heat, and optionally thermo-acoustic energy to bond each conductive ball 7 to one of the corresponding bonding pads 12, and the heating causes the conductive ball 7 to reflow or plastically deform (e.g., when ultrasonic energy is applied), moving the electronic tube die 10 closer to the substrate 30 so that the photoresist frame 6 is in direct contact with the second metal region 13. The temperature achieved by the applied heat, pressure, and optional thermo-acoustic energy is a function of the material used in the conductive ball 7. When the conductive ball 7 is gold, a temperature of 190 degrees Celsius can be used. In one example, steps 113 to 114 and optional step 115 reduce the thickness of the conductive ball 7 to about 16 microns.

[0053] In one example, the bonding process of steps 113 to 115 is a thermo-sonic bonding process using a force of 90 g / bump, a temperature of 190° C., and a maximum ultrasonic power of 0.5 watts.

[0054] Fig.10A side cross-sectional view of the substrate assembly is shown after steps 112 to 115 have been performed to electrically and physically couple the electronic die 10 to the substrate 30 via the conductive balls 7 to form a microcavity 80 that allows the device 4 to be exposed within the microcavity 80. In this example, the photoresist frame 6 directly covers the second metal region 13 and directly contacts the second metal region 13 along the entire length and width of the photoresist frame 6. As described above, the photoresist frame 6 is in direct contact with the metal region 2 and completely surrounds the device 4, the bonding pad 3, and the bonding pad 12.

[0055] The encapsulant material is deposited (116) so that the encapsulant material covers the substrate 30 and the bonded electronic die 10. The encapsulant material is then cured (117) to form a seal around the electronic die 10, thereby encapsulating the electronic die 10. The encapsulant material can be a plant or synthetic insulating resin that provides protection from external media (e.g., moisture and dust). Preferably, a solvent-free resin with high ionic purity (e.g., Cl content less than 10 ppm) is used, such as, for example, PROTAVIC PNE30270 manufactured by Protavic International of Paris, France, which can be cured at a temperature of 125 to 175 degrees Celsius for a period of 1 to 30 minutes. The curing process can include a second heating process (post-curing) at 150 degrees Celsius for 1 hour. Fig.11 shows after the encapsulant material 8 has been deposited Fig.10 This type of encapsulant material is also known as a globe top.

[0056] A cutting process (118) is performed to cut the substrate assembly so as to separate the encapsulated dies. The cutting process can be by rotating a cutting blade or a laser, and cutting the substrate 30 and the encapsulant material around each die 10, thereby leaving enough space around each die 10 so that the seal around the die 10 is maintained.

[0057] Fig.12 An encapsulated electronic die 9 formed according to method 100 is shown. Encapsulant material 8 extends over electronic die 10 around the sides of electronic die 10 and contacts first major surface 31 of substrate 30 around the entire periphery of electronic die 10. Microcavity 80 extends between substrate 30 and the active surface of electronic die 10. Microcavity 80 has sides including photoresist frame 6, first metal region 2, and landing pad 13. As described above, photoresist frame 6 completely surrounds device 4, conductive balls 7, bond pad 3, and bond pad 12. Device 4 is coupled to one or more of bond pads 16 through vias 14.

[0058] Fig.13An example is shown in which the encapsulated electronic die is a SAW filter 40 formed on a piezoelectric wafer 42 such as a LiTaO3 or LiNbO3 wafer. Fig.13 In the example shown in , patterning step 103 forms a first metal region 2 that is in electrical contact with a portion of the metal layer that forms a bonding pad 3 (e.g., at region 43 to region 44 for grounding metal region 2). As described above, photoresist frame 6 completely surrounds SAW filter 40 and conductive ball 7.

[0059] although Figures 7 to 13 A substrate assembly is shown wherein substrate 30 exhibits a single layer and vias 14 extending through the entire thickness of substrate 30 to couple each bond pad 12 to a single bond pad 16, but it is understood that substrate 30 may include multiple layers and bond pads 12 may be coupled to more than one bond pad 16. In an alternative example, substrate 30 is a circuit board having multiple layers wherein vias 14 extend between the circuit board layers to couple each bond pad 12 to one or more bond pads 16, or other connection points on or within the circuit board.

[0060] Figures 14 to 16 An example in which a landing pad is not formed on the substrate in step 111 is shown. Fig.14 The substrate assembly is shown in which steps 101 to 107 have formed an electronic die 10 with bonding pads 3, conductive balls 7, a first metal region 2 extending completely around the device 4, and a photoresist frame 6a extending completely around the device 4; steps 108 to 110 have formed bonding pads 12 on the first major surface 31 of the substrate 30, through holes 14, and bonding pads 16 on the second major surface 32 of the substrate 30; and the electronic die 10 has been placed (112) on the substrate 30. When the bonding process of steps 113 to 115 is performed, the conductive balls 7 will melt or plastically deform, and the electronic die 10 will move toward the substrate 30, where the photoresist frame 6a contacts the first major surface 31 of the substrate 30. Thus, each conductive ball 7 will contact one of the bonding pads 3 and the bonding pads 12. The photoresist frame 6a will be in direct contact with the first major surface 31 of the substrate 30 along the entire length and width of the photoresist frame 6a so as to form a housing around the device 4.

[0061] The photoresist frame 6a needs to have a sufficient height so that when the bonding process of steps 113 to 115 is performed, the photoresist frame 6a will come into contact with the first main surface 31. Therefore, the photoresist frame 6a may have a height greater than Figures 2 to 6 and Figures 9 to 13 The photoresist frame 6 shown in FIG.

[0062] The photoresist frame 6a may have a width of 15 to 20 microns and a height of 16 to 25 microns. In one example, the conductive ball 7 is reduced to a thickness of about 16 microns during the heating process, wherein the thickness of the bonding pad 3 is 1 micron and the thickness of the bonding pad 12 is 8 microns, the photoresist frame 6a has a thickness of 24 microns, and the first metal region 2 has a thickness of 1 micron, thereby giving a microcavity with a height of 25 microns.

[0063] Fig.15 shows the encapsulant material 8 after it has been deposited (116). Fig.14 More specifically, encapsulant material 8 has been deposited on a substrate assembly that includes electronic die 10, device 4, bonding pads 3, conductive balls 7, first metal regions 2, photoresist frame 6a, bonding pads 12 on first major surface 31 of substrate 30, through-holes 14, and bonding pads 16 on substrate 30.

[0064] Fig.16 shows the encapsulated electronic die 19 after the sawing process of step 118 has been performed Fig.15 The substrate assembly encapsulating the electronic die includes the electronic die 10, the device 4, the bonding pad 3, the conductive ball 7, the first metal region 2, the photoresist frame 6a, the bonding pad 12 on the first major surface 31 of the substrate 30, the through hole 14 and the bonding pad 16 on the substrate 30. It can be seen that the encapsulant material 8 extends around the side of the electronic die 10 on the electronic die 10 and contacts the first major surface 31 of the substrate 30 around the entire periphery of the electronic die 10 so as to form a seal around the electronic die 10.

[0065] Encapsulated electronic die 19 includes a microcavity 80 extending between substrate 30 and an active surface of electronic die 10. Encapsulated electronic die 19 includes electronic die 10, device 4, bonding pad 3, conductive ball 7, first metal region 2, photoresist frame 6a, bonding pad 12 on first major surface 31 of substrate 30, through hole 14, and bonding pad 16 on substrate 30. Microcavity 80 has a side including photoresist frame 6a and metal region 2. First metal region 2 of encapsulated electronic die 19 may have Figure 6 or may have a shape such as Fig.13 The shape shown in FIG. 1 is in electrical contact with a portion of the metal layer forming bonding pad 3 (eg, for grounding metal region 2 ), and may be formed of aluminum, aluminum alloy, or other conductive material.

[0066] Although the previous examples have discussed a single metal deposition and a single patterning process (103) such that the bonding pad 3 and the first metal region 2 are formed of the same material at the same time; alternatively, a first metal deposition and patterning process forms the bonding pad 3 and a second metal deposition and patterning process forms the metal region 2. In this example, a different material may be used in the first metal deposition than in the second deposition such that the bonding pad 3 and the first metal region 2 are formed of different materials and / or have different thicknesses.

[0067] Figures 17 to 21 The metal regions extending around the device are shown (e.g. Figures 2 to 13 and Figures 14 to 16 An example in which the first metal region 2) is not formed on the device wafer 1. Fig.17 A cross-sectional view of an example is shown in which devices 4 are formed on a device wafer 1 and in which a metal layer has been deposited and patterned to form bond pads 3 . Fig.18 The photoresist frame 6b completely surrounding the bonding pad 3 and the device 4 is shown after step 104 to step 105. Fig.17 The photoresist frame 6b is in direct contact with the top surface of the device wafer 1 along the entire bottom surface of the photoresist frame 6b.

[0068] Fig.19 The figure shows the electronic tube core 10a after the electronic tube core 10a having the bonding pad 3, the photoresist frame 6b and the conductive ball 7 has been formed in steps 101 to 102 and steps 104 to 107; the bonding pad 12, the bonding pad 16 and the through hole 14 have been formed in steps 108 to 109; the second metal region 13 has been formed in steps 110 to 111; and the electronic tube core 10a has been placed (112) on the substrate 30. Fig.18 The second metal region 13 completely extends around the bonding pad 12 and has Figure 8 When the bonding process of steps 113 to 115 is performed, the conductive balls 7 will melt or plastically deform, and the electronic die 10a will move toward the substrate 30, so that the photoresist frame 6b contacts the second metal region 13. Preferably, the photoresist frame 6b will directly contact the second metal region 13 along the entire length and width of the photoresist frame 6b.

[0069] The photoresist frame 6b needs to have a sufficient height so that when the bonding process of step 113 to step 115 is performed, the photoresist frame 6b will contact the second metal region 13. Therefore, the photoresist frame 6b may have a height greater than Figures 2 to 13In one example, the photoresist frame 6b may have a greater thickness than the photoresist frame 6 shown in FIG. In one example, the photoresist frame 6b may have a width of 15 to 20 microns and a height of 16 to 25 microns. In an exemplary conductive ball 7 on a bonding pad 3 where the thickness of 1 micron is reduced to a thickness of about 16 microns during the heating process, the photoresist frame 6b has a thickness of 17 microns, and the second metal region 13 and the bonding pad 12 have a thickness of 8 microns, giving a microcavity with a maximum height of 25 microns.

[0070] Fig. 20 shows the encapsulant material 8 after it has been deposited (116). Fig.19 substrate assembly. Fig.21 Shown by cutting Fig.19 The encapsulated electronic die 29 is formed by the substrate assembly of the electronic die 10a. It can be seen that the encapsulant material 8 extends around the sides of the electronic die 10a on the electronic die 10a and contacts the first major surface 31 of the substrate 30 around the entire periphery of the electronic die 10a so as to form a seal around the electronic die 10a. The encapsulated electronic die 29 includes a microcavity 80 extending between the substrate 30 and the active surface of the electronic die 10a. The microcavity 80 has sides including the photoresist frame 6b and the metal region 13.

[0071] Figure 22 to Figure 24 An example is shown in which a metal region (eg, first metal region 2 shown above) is not formed on device wafer 1 and a landing pad (eg, landing pad 13 shown above) is not formed on a substrate. Fig. 22 A side cross-sectional view of an example of an electronic die 10b having a bonding pad 3, a conductive ball 7, and a photoresist frame 6c is shown in which steps 101 to 102 and steps 104 to 107 have formed; after steps 108 to 110 have formed a bonding pad 12, a bonding pad 16 on the second major surface 32, and a through hole 14; and after the electronic die 10b has been placed (112) on the substrate 30. When the bonding process of steps 113 to 115 is performed, the conductive ball 7 will melt or plastically deform, and the electronic die 10b will move toward the substrate 30 so that the photoresist frame 6c contacts the first major surface 31 of the substrate 30. The photoresist frame 6c will preferably be in direct contact with the first major surface 31 of the substrate 30 along the entire length and width of the photoresist frame 6c so as to form a microcavity 80 around the device 4.

[0072] Fig.23 Shown is the encapsulant material 8 after it has been deposited (116). Fig. 22 A side cross-sectional view of a base plate assembly. Fig.24 Shown in Fig.23The encapsulated electronic die 39 is formed by performing a sawing process (118) on the substrate assembly of the electronic die 10b. It can be seen that the encapsulant material 8 extends around the sides of the electronic die 10b on the electronic die 10b and contacts the first major surface 31 of the substrate 30 around the entire periphery of the electronic die 10b so as to form a seal around the electronic die 10b. The encapsulated electronic die 39 includes a microcavity 80 extending between the substrate 30 and the active surface of the electronic die 10. The microcavity 80 has sides formed only by the photoresist frame 6c.

[0073] Although examples and applications of the present invention have been shown and described, it will be apparent to those skilled in the art that more modifications than those described above are possible without departing from the inventive concepts herein. Therefore, the present invention is not to be restricted except in the spirit of the appended claims.

Claims

1. An encapsulated electronic tube die, comprising: substrate; An electronic tube die having a device formed thereon; conductive balls for coupling the device to bond pads on the substrate; a first metal region formed on the electronic die, the first metal region extending completely around the device; a photoresist frame attached to the first metal region and extending completely around the device, the photoresist frame being secured to the first major surface of the substrate so as to form an enclosure around the device; as well as An encapsulant material extends over and around the sides of the electronic die such that the encapsulant material contacts the first major surface of the substrate around the entire periphery of the electronic die to form a seal around the electronic die. 2 . The encapsulated electronic die of claim 1 , wherein the photoresist frame is in direct contact with the first major surface of the substrate.

3. The encapsulated electronic die of claim 2, further comprising: A plurality of bonding pads are formed on the electronic die, and each of the conductive balls is in contact with one of the bonding pads formed on the electronic die and one of the bonding pads formed on the substrate.

4. The encapsulated electronic die of claim 3, wherein the photoresist frame comprises an epoxy-based photoresist.

5. The encapsulated electronic die of claim 4, wherein the photoresist frame has a height of 16 microns to 25 microns.

6. The encapsulated electronic die of claim 5, wherein the photoresist frame has a width of 15 microns to 20 microns.

7. The encapsulated electronic die of claim 1 , further comprising: A second metal region is disposed on the substrate, the second metal region having a shape corresponding to the shape of the photoresist frame so as to form a landing pad for the photoresist frame, the photoresist frame being in direct contact with the second metal region so as to form a housing around the device.

8. An encapsulated electronic die, comprising: substrate; An electronic tube die having a device formed thereon; conductive balls for coupling the device to bond pads on the substrate; a photoresist frame secured to the electronic die and extending completely around the device; a metal region disposed on the substrate, the metal region having a shape corresponding to the shape of the photoresist frame so as to form a landing pad for the photoresist frame, the photoresist frame being in direct contact with the metal region so as to form a housing around the device; as well as An encapsulant material extends over and around the sides of the electronic die such that the encapsulant material contacts the first major surface of the substrate around the entire periphery of the electronic die to form a seal around the electronic die.

9. The encapsulated electronic die of claim 8, wherein the photoresist frame has a height of 16 microns to 25 microns.

10. The encapsulated electronic die of claim 9, wherein the photoresist frame has a width of 15 microns to 20 microns.

11. The encapsulated electronic die of claim 10, wherein the photoresist frame comprises an epoxy-based photoresist.

12. A method of forming an encapsulated electronic die using a substrate and a device wafer having a device formed thereon, the method comprising: forming a first metal region on the device wafer, the first metal region extending completely around the device; forming a plurality of bonding pads on the device wafer; Depositing a photoresist layer on the device wafer; patterning the photoresist layer to form a photoresist frame attached to the first metal region and completely surrounding the device; depositing conductive balls on the bonding pads; cutting the wafer to form the electronic dies; placing the electronic die on the substrate; heating and compressing the conductive balls so that each conductive ball is coupled to one of the bonding pads and to the substrate, the heating and compressing moving the electronic die closer to the substrate so that the photoresist frame is in direct contact with the substrate or with a landing pad formed on the substrate; depositing an encapsulant material such that the encapsulant material covers the electronic die and the substrate; curing the encapsulant material to encapsulate the electronic die; as well as The substrate is diced to separate the encapsulated electronic dies.

13. The method of claim 12, wherein the photoresist frame is in direct contact with the first major surface of the substrate.

14. The method of claim 12, further comprising forming a landing pad on the substrate, wherein the photoresist frame is in direct contact with the landing pad.

15. The method of claim 12, wherein the first metal region comprises one or more layers of metal, and The photoresist frame is in contact with the first metal region and completely surrounds the device.

16. The method according to claim 15, further comprising: depositing a second metal layer on the substrate; as well as The second metal layer is patterned to form bonding pads on the substrate. 17 . The method of claim 16 , wherein the patterning of the second metal layer forms a second metal region including a landing pad, wherein the photoresist frame is in direct contact with the second metal region.

18. A method of forming an encapsulated electronic die using a substrate and a device wafer having a device formed thereon, the method comprising: forming a first metal region on the device wafer, the first metal region extending completely around the device; forming a plurality of bonding pads on the device wafer; Depositing a photoresist layer on the device wafer; patterning the photoresist layer to form a photoresist frame attached to the first metal region and completely surrounding the device; depositing conductive balls on the bonding pads; cutting the wafer to form the electronic dies; forming a metal region on the substrate, the metal region having a shape corresponding to the shape of the photoresist frame so as to form a landing pad for the photoresist frame; placing the electronic die on the substrate; heating and compressing the conductive balls so that each conductive ball is coupled to one of the bond pads and to the substrate, the heating and compressing moving the electronic die closer to the substrate so that the photoresist frame is in direct contact with the landing pad; depositing an encapsulant material such that the encapsulant material covers the electronic die and the substrate; curing the encapsulant material to encapsulate the electronic die; as well as The substrate is diced to separate the encapsulated electronic dies.

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