IMAGE SENSOR PACKAGES AND ASSOCIATED METHODS

Abstract

Implementations of an image sensor package may include: an optically transparent cover that includes a groove along an entire circumference of the optically transparent cover; an image sensor die; an adhesive material that couples the optically transparent cover to the image sensor die; and a molding compound that contacts the sidewalls of the image sensor die, is in contact with the adhesive material, and extends into the groove.

Description

BACKGROUND 1. Technical field

[0001] Aspects of this document generally relate to image sensing devices, such as devices for detecting electromagnetic radiation. 2. Background

[0002] Semiconductor device packages were developed to protect semiconductor dies from a variety of environmental conditions, including electrostatic discharge and moisture. Semiconductor packages were also developed that provide electrical routing from the semiconductor die to a printed circuit board or motherboard on which the semiconductor package is mounted. SUMMARY

[0003] Implementations of an image sensor package may include: an optically transmissive cover including a groove along an entire perimeter of the optically transmissive cover; an image sensor die; an adhesive material coupling the optically transmissive cover to the image sensor die; and a molding compound contacting the sidewalls of the image sensor die, in contact with the adhesive material, and extending into the groove.

[0004] Image sensor package implementations may include one, all, or any of the following: The package may include a substrate coupled to the image sensor die. The substrate may include a ball grid array. The substrate may include a ball grid array. An outer edge of the package can only enclose molding compound and the substrate. The plurality of wire bonds may be located in the adhesive material.

[0005] The groove may be adjacent to a largest planar side of the optically transmissive cover, which may be opposite a largest planar side facing the image sensor die.

[0006] Implementations of a method for manufacturing an image sensor package may include: providing an optically transmissive cover including a groove along an entire perimeter of the optically transmissive cover and an image sensor die; applying an adhesive material along the perimeter of the image sensor die; contacting the optically transmissive cover with the adhesive material; irradiating the adhesive material through the optically transmissive cover with electromagnetic radiation to at least partially cure the adhesive material; and applying a molding compound to the image sensor die, the adhesive material, and into the groove.

[0007] Implementations of a method of manufacturing an image sensor package may include one, all, or any of the following: The groove may be adjacent to a largest planar side of the optically transmissive cover, which may be opposite a largest planar side facing the image sensor die. The electromagnetic radiation can be ultraviolet light. The process may include thermally curing the adhesive material. The method may include providing a substrate and forming a plurality of wire bonds between the substrate and the bond pads included on the image sensor die. Applying the adhesive material may further include applying the adhesive material over the plurality of wire bonds.

[0008] Implementations of a method for manufacturing an image sensor package may include: providing an optically transmissive plate; cutting a first set of grooves into the optically transmissive plate in a first direction; cutting a second set of grooves into the optically transmissive plate in a second direction; and singulating the optically transmissive plate in the first set of grooves in the first direction. The method may also include singulating the optically transmissive plate in the second set of grooves in the second direction to form a plurality of optically transmissive covers. The first width of the first set of grooves and a second width of the second set of grooves may form a step along an entire perimeter of each optically transmissive cover of the plurality of optically transmissive covers.

[0009] Implementations of a method of manufacturing an image sensor package may include one, all, or any of the following: The first set of grooves and the second set of grooves can be sawn. Separating may also include sawing. The first width and the second width can be the same. The first width and the second width can be different.

[0010] The method may further include: providing an image sensor die; applying an adhesive material along the perimeter of the image sensor die; bonding the optically transmissive cover to the adhesive material; irradiating the adhesive material with electromagnetic radiation to at least partially cure the adhesive material; and applying a molding compound into the optically transmissive cover stage.

[0011] The method may further include: providing a substrate; forming a plurality of wire bonds between the substrate and the bond pads included on the image sensor die; and applying the adhesive material over the plurality of wire bonds.

[0012] The foregoing and other aspects, features and advantages will be apparent to those skilled in the art from the DESCRIPTION and DRAWINGS, as well as from the CLAIMS. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Implementations are described below in conjunction with the accompanying drawings, wherein like reference numerals denote like elements and wherein: Fig. 1 is a diagram of an implementation of a method for manufacturing an optically transmissive cover; Fig. Figure 2 is a diagram of an implementation of a method for manufacturing an optically transmissive cover; Fig. 3 is a perspective view of an implementation of an optically transmissive cover; Fig. 4 a cross-sectional view of the implementation of the optically transparent cover of Fig. 3 is; Fig. Figure 5 is a plan view of an implementation of an optically transmissive cover; Fig. 6 is a side cross-sectional view of an implementation of an image sensor die coupled to a substrate; Fig. 7 a cross-sectional view of the implementation of the image sensor package of Fig. 6 after the formation of wire bonds and the application of adhesive material; Fig. 8 a cross-sectional view of the implementation of the image sensor package of Fig. 7 after coupling an optically transmissive cover to the adhesive material; Fig. 9 a cross-sectional view of the implementation of the image sensor package of Fig. 8 after application of a molding compound; Fig. 10 is a cross-sectional view of two implementations of image sensor packages after application of molding compound during a singulation process; Fig. 11 is a cross-sectional view of two image sensor packages that are not wire-in-dam image sensor packages; Fig. 12 is a cross-sectional view of two image sensor packages, one of which is a ball grid array package and the other of which is a land grid array package; and Fig. 13 is a cross-sectional view of another image sensor package showing a tilt of the molding compound. DESCRIPTION

[0014] This disclosure, its aspects, and implementations are not limited to the specific components, assembly procedures, or method elements disclosed herein. Many other components, assembly procedures, and / or method elements known in the art that are compatible with the contemplated image sensor packages, and associated methods, will be apparent from this disclosure for use with particular implementations. Accordingly, for example, although particular implementations are disclosed, these implementations and implementing components may include any shapes, sizes, styles, types, models, versions, dimensions, concentrations, materials, quantities, method elements, method steps, and / or the like known in the art for these image sensor packages, as well as implementing components and methods, that are compatible with the contemplated operation and methods.

[0015] The term flare refers to image artifacts caused by stray light received by an image sensor's pixel array. Flare caused by package components is a problem in various image sensor applications, particularly those used in advanced driver assistance and autonomous driving systems, because this flare source is not caused by environmental factors but by the package structure itself. Since the package components are carried with the image sensor, minimizing the possibility of flare caused by package components can be an important consideration in package design. Components shown to contribute to flare include the edge of the optically transparent cover over the image sensor die, the bead / edge of the adhesive material, bond wires, wire bonds, and / or bond pads.

[0016] In various image sensor package implementations, flare caused by package components can be mitigated by using a black mask under a glass structure, in which an optically black mask layer is applied around the perimeter of an optically transparent cover. This technique is used in wire-in-dam package implementations, where the bond wires, wire bonds, and bond pads are located beneath the adhesive material that holds the optically transparent cover and the image sensor die together. One of the major challenges with the black mask under glass technique is that the black mask material makes it difficult to perform an ultraviolet (UV) light curing process with the adhesive material, as the black mask itself absorbs the curing light.

[0017] The implementations of the package and method disclosed herein include various structures designed to mitigate flares caused by package components. Referring to Fig. 1, a flowchart of a method for creating optically transmissive covers for image sensor package implementations as disclosed herein is illustrated. Fig. Figure 1 illustrates an optically transparent plate 2 made of a material that is transparent to the specific wavelength(s) of electromagnetic radiation that the optical sensor package is designed to detect. In various implementations, these wavelengths may include, as a non-limiting example, visible light, ultraviolet light, infrared light, x-rays, microwaves, laser light, or any other type of electromagnetic radiation. While in Fig. 1 illustrates the use of a square plate, the optically transmissive plate 2 may also have the shape of a circle or other wafer-shaped product when wafer-scale processing techniques are used.

[0018] As in Fig. 1, a first set of grooves 4 is cut into the material of the optically transmissive plate 2 using a saw blade 6 having a first cutting width in a first direction. While the use of sawing to form the first set of grooves 4 is illustrated, other methods for removing the material of the optically transmissive plate 2 may also be used in various process implementations, including, as a non-limiting example, laser cutting, waterjet cutting, etching, scribing, any combination thereof, or any other technique for removing the material of the optically transmissive plate 2. As in Fig. 1, a second set of grooves 8 is then cut into the material of the optically transmissive plate 2 using a saw blade 6 with the first cutting width in a second direction that crosses the first direction, thereby forming a set of islands 10 in the material of the optically transmissive plate 2. The first set of grooves 4 and the second set of grooves 8 are each cut to a width. In the implementation of Fig. 1, the width of the first set of grooves 4 and the width of the second set of grooves 8 are the same because they are cut using the same saw blade with the same cutting width. However, in other implementations, the width of the first set of grooves 4 and the width of the second set of grooves 8 may be different, so that the dimensions of the step cut into each optically transparent plate 2 differ on two sides, as explained in more detail below.

[0019] Referring again to Fig. 1, the optically transparent plate 2 with the islands 10 formed therein is then cut using a second saw blade 12 having a narrower cutting width than the cutting width of the first saw blade 6. The second cut passes through the entire material of the optically transparent plate 2 and separates a plurality of optically transparent covers 14 from the optically transparent plate 2. The effect of cutting with the narrow cutting width blade is to form a step cut that creates a step or groove 17 on each side of each optically transparent cover that extends around the entire circumference of each optically transparent cover.

[0020] The process implementation of Fig. 1 uses a two-step cutting process to form the steps or grooves in the optically transmissive cover. Referring to Fig. 2 illustrates another method implementation using an optically transmissive plate 16 into which islands 18 have been prefabricated, i.e., they have been produced by a process other than a cutting, etching, or ablation process. An example of a method for prefabricating the islands includes, as a non-limiting example, molding, casting, welding, gluing, or any other method for forming the islands from the respective material of the optically transmissive plate 16. As in Fig. 2, the areas between the islands 18 of the optically transmissive plate 16 are then cut using any dicing technique disclosed herein to leave a step or groove around each of the resulting optically transmissive covers.

[0021] Referring to Fig. 3 illustrates an implementation of an optically transmissive cover 20 which is produced using one of the method implementations of Fig. 1 and Fig. 2. As illustrated, the optically transmissive cover 20 includes a groove or step 22 extending over the entire perimeter 24 of the cover. Fig. Figure 4 illustrates a cross-sectional view of the optically transmissive cover 20 showing the shape of the groove or step 22. In various implementations of the package, the side of the optically transmissive cover into which the groove or step 22 is formed is the largest planar side 26, which is opposite the largest planar side 28 of the optically transmissive cover 20, which will ultimately face the image sensor die.

[0022] Fig. Figure 5 illustrates a top view of an implementation of an optically transmissive cover 30 having a groove / step 32 with different dimensions in the material of the optically transmissive cover 30. Upon inspection, it is seen that the distances / widths L1 and L3 are the same, while the distances / widths L2 and L4 are different from each other and from the distances / widths L1 and L3. The different widths can be more easily determined using the method implementation of Fig. 2, where the shape of the islands is pre-defined, making it possible for some or all of the distances / widths L1, L2, L3, L4 to be the same or all different. The different widths can be achieved using the method implementation of Fig. 1, but the indexing of the saw cuts may need to be adjusted in one or both cutting directions to isolate one side of the optically transmissive cover 30 closer to the island 34 than the other side. Those of ordinary skill in the art will readily recognize how grooves / steps of varying widths can be implemented using the methods disclosed herein for forming optically transmissive covers.

[0023] The implementations of optically transmissive covers disclosed herein can be used in various implementations of a method for manufacturing image sensor packages. Referring to Fig. 6 shows an implementation of an image sensor die 36 bonded to the substrate 38 using the bonding material 40. As illustrated, the image sensor die 36 includes the pixel array 42. Here, the die bonding process has been completed, bonding the image sensor die 36 to the substrate, thereby beginning the formation of the image sensor package 44. Fig. Figure 7 illustrates the image sensor package 44 after completion of the wire bonding, in which the bond wires 46 are bonded to bond pads (in Fig. 7 not visible). As shown in Fig. As illustrated in Figure 7, after wire bonding to the substrate 38, adhesive material 50 is applied to the wire bonds 48, the bond wires 46, and the bond pads around the perimeter of the image sensor die 36. In various implementations, the adhesive material is a glass-applied epoxy. Various implementations of adhesive materials may be partially or fully curable using ultraviolet (UV) light and partially or fully curable using thermal energy. For implementations where the adhesive material is partially curable using UV light and fully curable by thermal energy, the use of UV light assists in reducing the overall thermal energy applied to the image sensor package.If the adhesive material is fully cured using thermal energy alone, in some image sensor package implementations, the optically transparent cover may separate from the adhesive material, leaving gaps through which contaminants can enter the air gap containing the pixel array 42. Therefore, the ability to complete the UV curing process of the bonding process can be critical to the overall reliability and function of the image sensor package.

[0024] Referring to Fig. 8, the image sensor package 44 of Fig. 7 after the optically transmissive cover 52 has been coupled to the adhesive material 50. In some implementations, this is achieved by lowering the optically transmissive cover 52 onto the adhesive material 50. In other process implementations, the optically transmissive cover may be placed directly onto the adhesive material 50. Note that the largest planar surface 54 of the optically transmissive cover 52 facing the image sensor die 36 does not include the groove / step 56 therein, but does include the opposite large planar surface 58. Because the optically transmissive cover 52 is optically transmissive, ultraviolet light can pass through it without significant attenuation in various implementations. Here, the UV light is irradiated onto the image sensor package to perform the UV curing process of the adhesive material 50.Since there is no black mask layer adjacent to or covering the adhesive material in the optical path of the UV light, the UV irradiation system used can be any of a wide variety of systems that direct the light downward onto the image sensor package 44.

[0025] After UV curing (and, in some implementations, thermal curing) of the adhesive material 50, Fig. 9 shows the image sensor package 44 after applying a molding compound 60 to the image sensor die 36, the adhesive material 50, and into the groove / step 56 of the optically transmissive cover 52. Here, the molding compound 60 contacts the sidewall 62 of the image sensor die 36, the sidewall 64 of the adhesive material 50, and the sidewall 66 of the optically transmissive cover 52. As illustrated, the molding compound 60 extends into the groove / step 56, thereby forming a mask layer 68 that extends around the perimeter of the optically transmissive cover 52 over the adhesive material 50. Because the molding compound 60 is optically opaque, the effect of the molding compound 60 with respect to optical performance may be substantially identical to the previously discussed black mask layer. However, since the mask layer 68 is formed only after the UV curing of the adhesive material 50 is completed, it does not cause problems with the incomplete curing of the adhesive material 50.In various process implementations, the molding compound 60 is applied using a black liquid encapsulant or using an epoxy molding compound (EMC) in an encapsulation process or using a film-assisted molding (FAM) process.

[0026] Referring to Fig. 10 illustrates two image sensor packages 70, 72 formed on a plate substrate 74 using a ball mounting / ball attachment process in which a plurality of solder balls 76 are mounted / attached to the plate substrate 74. In Fig. 10 illustrates a sawing process in which the saw blade 78 cuts through the material of the plate substrate 74 and the molding compound 80 to form two image sensor packages.

[0027] Although the above examples of image sensor packages have so far been wire-in-dam packages, the principles disclosed herein can also be applied to many other image sensor types / configurations. For example, Fig. 11 a first image sensor package 82, which is a ball grid array package similar to that shown in the Fig. 6 to 10, but in which the adhesive material 84 is arranged much closer to the pixel array and a correspondingly smaller optically transmissive cover 86 is used relative to the size of the image sensor die 88 than in the previously illustrated implementations. For this reason, the wire bonds 90 are not located in the adhesive material 84, but rather in the molding compound 92. Fig. Figure 11 also illustrates the implementation of a second image sensor package 94, similar in structure to the first image sensor package 82, but a land grid array package instead of a sphere grid array package. In both packages, the molding compound 92, 96 forms the mask layers 98, 100 around the perimeter of the optically transmissive covers 86, 102 through the groove / step in each of the covers.

[0028] Referring to Fig. 12 illustrates two implementations of wire-in-dam image sensor packages 104, 106. The image sensor package 104 is a ball grid array package, similar to that shown in Fig. 10, while the image sensor package 106 is a land grid array package. Fig. 11 and Fig. 12 illustrate that the principles and optically transmissive covers disclosed herein can be used with both ball grid array and land grid array packages, as well as wire-in-dam packages where the wire bonds are not in the adhesive material / dam that couples the optically transmissive cover to the image sensor die.

[0029] Referring to Fig. 13 illustrates another implementation of an image sensor package 108. Here, the two areas in the boxed regions indicate that, in certain implementations, a slope 116 may be present in the mask layer 110 away from the top surface 112 of the optically transmissive cover 114. This slope may be created during the molding compound application process. Here, in this implementation, a liquid encapsulant molding process was used, which caused the material to flow away from the top surface 112 of the optically transmissive cover 114. Although the resulting mask layer 110 is thinner than in the Fig. 12 illustrated implementations, it is sufficiently thick to act as an optical mask for scattered light.

[0030] The Fig. The implementations of image sensor packages illustrated in Figures 11 to 13 all show cross-sections where the width of the formed mask layer is the same on both sides of the package. Referring again to Fig.5, where the widths of L1, L2, L3, and L4 differ from each other, mask layers with correspondingly different widths can also be formed. This can be significant because, in various image sensor die implementations, the pixel array is not actually centered in the center of the image sensor die itself due to routing, interconnections, or other design / process factors. Thus, the ability to create wider and thinner mask layers on different sides of the die by using optically transmissive covers with correspondingly wider and thinner widths L1, L2, L3, and L4 can be advantageous. These mask layers with different widths on different sides of the optically transmissive cover can help prevent stray light from causing flare defects during operation of the image sensor package.

[0031] Implementations of an image sensor package such as those disclosed herein include a ball grid array.

[0032] Implementations of an image sensor package as disclosed herein include a land grid arrangement.

[0033] Implementations of an image sensor package as disclosed herein include a substrate.

[0034] Implementations of image sensor packages such as those disclosed herein include optically transmissive covers having a groove adjacent to a largest planar side opposite a largest planar side facing the image sensor die.

[0035] In implementations of a method for manufacturing an image sensor package, the method uses electromagnetic radiation to cure adhesive material, which is ultraviolet light.

[0036] In implementations of a method for manufacturing an image sensor package, the method utilizes thermal curing of the adhesive material.

[0037] In implementations of a method of manufacturing an image sensor package, the method includes sawing the first set of grooves and the second set of grooves.

[0038] In implementations of a method for manufacturing an image sensor package, the method includes dicing including sawing.

[0039] In implementations of a method of manufacturing an image sensor package, the method may include providing a substrate and forming a plurality of wire bonds between the substrate and bond pads included on the image sensor die.

[0040] It should be readily understood that where the foregoing description refers to particular implementations of image sensor packages and implementing components, subcomponents, methods, and submethods, a number of modifications may be made without departing from their essence, and that these implementations, implementing components, subcomponents, methods, and submethods may also be applied to other image sensor packages.

Claims

[1] Image sensor package, comprising: an optically transmissive cover comprising a groove along an entire circumference of the optically transmissive cover; an image sensor die; an adhesive material that couples the optically transmissive cover to the image sensor die; and a molding compound that contacts the sidewalls of the image sensor die, is in contact with the adhesive material, and extends into the groove. [2] The package of claim 1, wherein an outer edge of the package comprises only molding compound and a substrate. [3] The package of claim 1, wherein a plurality of wire bonds are located in the adhesive material. [4] A method of manufacturing an image sensor package, comprising: Providing an optically transmissive cover comprising a groove along an entire circumference of the optically transmissive cover and an image sensor die; Applying an adhesive material along the perimeter of the image sensor die; Bringing the optically transmissive cover into contact with the adhesive material; Irradiating the adhesive material through the optically transparent cover with electromagnetic radiation to at least partially cure the adhesive material; and Applying a molding compound to the image sensor die, the adhesive material and into the groove. [5] The method of claim 4, wherein applying the adhesive material further comprises applying the adhesive material over the plurality of wire bonds. [6] A method of manufacturing an image sensor package, comprising: Providing an optically transparent plate; Cutting a first set of grooves into the optically transmissive plate in a first direction; Cutting a second set of grooves into the optically transmissive plate in a second direction; Singulating the optically transmissive plate in the first set of grooves in the first direction; and singulating the optically transmissive plate in the second set of grooves in the second direction to form a plurality of optically transmissive covers; wherein a first width of the first set of grooves and a second width of the second set of grooves form a step along an entire circumference of each optically transmissive cover of the plurality of optically transmissive covers. [7] The method of claim 6, wherein the first width and the second width are equal. [8] The method of claim 6, wherein the first width and the second width are different. [9] The method of claim 6, further comprising: Providing an image sensor die; Applying an adhesive material along the perimeter of the image sensor die; Bonding the optically transparent cover with the adhesive material; Irradiating the adhesive material with electromagnetic radiation to at least partially cure the adhesive material; and Applying a molding compound to the optically transmissive cover stage. [10] The method of claim 9, further comprising: Providing a substrate; Forming a plurality of wire bonds between the substrate and the bond pads included on the image sensor die; and Applying the adhesive material over the multitude of wire bonds.

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