Optical sensor package and method of manufacture

Abstract

The invention relates to an optical sensor package and a method of manufacture. The package substrate panel includes die mounting regions separated from each other by inter-die mounting regions. An optical integrated circuit die having a sacrificial cover above the location of the optical sensor is mounted at each die mounting region. An encapsulation resin material is molded over the package substrate panel to encapsulate the optical integrated circuit die and at least around the sacrificial cover to form an encapsulated panel structure. The sacrificial cap is then removed to expose the optical sensor of the optical integrated circuit die. The encapsulation panel structure is cut at the inter-die mounting region to divide the encapsulation panel structure into optical integrated circuit packages.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 612,125, filed on December 19, 2023, the disclosure of which is incorporated herein by reference. Technical field

[0003] The present invention generally relates to the packaging of optical integrated circuits. Background art

[0004] Reference Figure 1 , which shows a cross - sectional view of an optical integrated circuit package 10. The package 10 includes a package substrate 12 in the form of, for example, a multilayer board 14 (e.g., of the printed circuit board type), including an interconnect network 16 (formed by wired lines and vias) that electrically connects a front solder pad 18 to a rear solder pad 20. The rear solder pad 20 may include, for example, a portion of a redistribution layer (RDL). Although not explicitly shown, it should be noted that the front and rear surfaces of the package substrate 12 may include solder mask layers with openings at the locations of the pads 18 and 20. The rear solder pad 20 may include, for example, a support pad for a pillar 21p or a ball 21b (in a ball grid array (BGA) type package). The rear solder pad 20 may include, for example, a connection solder pad (in a land grid array (LGA) type package).

[0005] The optical integrated circuit die 22 is mounted to the upper surface of the package substrate 12 using a suitable adhesive material (e.g., a die attach film (DAF)). The optical integrated circuit die 22 includes an optical sensor 24 (e.g., formed by an array of photosensitive elements such as photodiodes) associated with a surface (e.g., the front surface) opposite to the surface (e.g., the rear surface) attached to the package substrate 12 and a plurality of electrical connection die bond pads 26. The electrical connection die bond pads 26 of the optical integrated circuit die 22 are electrically connected to the front solder pads 18 of the package substrate 12 using bond wires 28.

[0006] A bonding ring 30 is provided at the front surface of the optical integrated circuit die 22 to surround (i.e., encircle) the optical sensor 24. The bonding ring 30 is positioned in a gap region 32 between the perimeter of the optical sensor 24 and the electrical connection die bond pads 26 at the front surface of the optical integrated circuit die 22. A diffractive optical element (DOE) 34 (e.g., including one or more of an optical lens and an optical filter (e.g., an infrared (IR) filter) and having a flat plate form) is attached to the optical integrated circuit die 22 using the bonding ring 30. The DOE 34 is positioned to extend over the optical sensor 24 of the optical integrated circuit die 22. The bonding ring 30 may include additives such as spacer balls for controlling the spacing between the bottom surface of the DOE 34 and the optical sensor 24 (e.g., in the case of providing an array of microlens structures over the optical sensor 24). The bonding ring 30 also forms a dam structure that prevents the encapsulation encapsulant material for forming the encapsulant resin package 36 from oozing out and covering portions over the optical sensor 24. In an embodiment, the bonding ring 30 may include an epoxy bead for bonding the DOE 34 to the front surface of the optical integrated circuit die 22. The encapsulant resin package 36 seals the peripheral side edges of the DOE 34, thereby encapsulating the optical integrated circuit die 22 and the bonding wires 28 and attaching to the package substrate 12.

[0007] Due to the advancement of the technology node for fabricating the optical integrated circuit die 22, the size of the gap region 32 between the perimeter of the optical sensor 24 and the electrical connection die bond pads 26 at the front surface of the optical integrated circuit die 22 is shrinking. In many packaging embodiments, this gap region is no longer large / wide enough to accommodate the placement of the bonding ring 30 without the risk of contaminating the optical sensor 24 or the risk of damaging the bonding wires at the connection of the electrical connection die bond pads 26 of the optical integrated circuit die 22.

[0008] Thus, there is a need in the art for a new packaging process and optical sensor package. SUMMARY OF THE INVENTION

[0009] In an embodiment, a method includes: providing a package substrate panel including a plurality of die mounting regions separated from each other by an inter-die mounting region; at each die mounting region, mounting an optical integrated circuit die having a sacrificial cover over the location of an optical sensor; molding an encapsulant resin material over the package substrate panel to encapsulate the optical integrated circuit die and at least around the sacrificial cover to form an encapsulation panel structure; removing the sacrificial cover to expose the optical sensor of the optical integrated circuit die; and cutting the encapsulation panel structure at the inter-die mounting region to divide the encapsulation panel structure into a plurality of optical integrated circuit packages.

[0010] A vent is formed in the encapsulation resin material of the encapsulation panel structure that covers each optical sensor, removing the sacrificial cover. Then, each vent is covered with a diffractive optical element. The diffractive optical element can be adhesively mounted to the upper surface of the encapsulation panel structure.

[0011] An encapsulation resin material is molded on the encapsulation substrate panel to form sub-openings in the encapsulation resin material of the encapsulation panel structure above each sacrificial cover. The sacrificial cover is removed to form additional sub-openings in the encapsulation resin material of the encapsulation panel structure above each optical sensor. Each additional sub-opening is covered with a diffractive optical element. The formation of the sub-openings defines a ledge around each sacrificial cover, and the diffractive optical element is adhesively mounted to the ledge.

[0012] In an embodiment, an optical integrated circuit package includes: an encapsulation substrate; an optical integrated circuit die having an optical sensor and an electrical connection die pad; an encapsulation resin package located on the encapsulation substrate and encapsulating the optical integrated circuit die and the electrical connection die pad of the optical integrated circuit die; wherein the encapsulation resin package includes a vent exposing the optical sensor of the optical integrated circuit die; and a diffractive optical element mounted on the surface of the encapsulation resin package to cover above the vent.

[0013] In an embodiment, the vent includes: a first sub-opening having a first cross-sectional area; a second sub-opening having a second cross-sectional area greater than the first cross-sectional area; wherein the first sub-opening and the second sub-opening are aligned; wherein the second sub-opening defines a ledge around the first sub-opening; and wherein the ledge is the surface of the encapsulation resin package for mounting the diffractive optical element. Description of the Drawings

[0014] To better understand the embodiments, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0015] Figure 1 A cross-sectional view of an optical integrated circuit package is shown;

[0016] Figure 2 A cross-sectional view of an optical integrated circuit package is shown;

[0017] Figure 3 A cross-sectional view of an optical integrated circuit package is shown;

[0018] Figure 4A - Figure 4M Illustrates the steps in the process for manufacturing the package as shown in Figure 2 and;

[0019] Figure 5 A cross-sectional view of an optical integrated circuit package is shown. Detailed Description

[0020] Reference Figure 2, which shows a cross-sectional view of the optical integrated circuit package 110. The package 110 includes a package substrate 112 in the form of, for example, a multilayer board 114 (e.g., a printed circuit board type), including an interconnect network 116 (formed by wired lines and vias) that electrically connects the front solder pads 118 to the rear solder pads 120. The rear solder pads 120 may include, for example, portions of a redistribution layer (RDL). Although not explicitly shown, it should be noted that the front and rear surfaces of the package substrate 112 may include solder mask layers having openings at the positions of the solder pads 118 and 120. The rear solder pads 120 may include, for example, support solder pads for pillars 121p or balls 121b (in a ball grid array (BGA) type package). The rear solder pads 120 may include, for example, connection solder pads (in a land grid array (LGA) type package).

[0021] The optical integrated circuit die 122 is mounted on the upper surface of the package substrate 112 using a suitable adhesive material (e.g., a die attach film (DAF)). The optical integrated circuit die 122 includes an optical sensor 124 (e.g., formed by an array of photosensitive elements such as photodiodes) and a plurality of electrically connected die bond pads 126 associated with a surface (e.g., the front surface) opposite to the surface (e.g., the rear surface) attached to the package substrate 112. It should be noted that Figure 2 the size of the gap region 132 between the periphery of the optical sensor 124 and the electrically connected die bond pads 126 at the front surface of the optical integrated circuit die 122 is much smaller than Figure 1 the size of the gap region 32 between the periphery of the optical sensor 24 and the electrically connected die bond pads 26 at the front surface of the optical integrated circuit die 22. The electrically connected die bond pads 126 of the optical integrated circuit die 122 are electrically connected to the front solder pads 118 of the package substrate 112 using bonding wires 128.

[0022] The encapsulating resin package 136 encapsulates the optical integrated circuit die 122, the electrical connection die bonding pads 126 at the outer periphery of the front surface of the optical integrated circuit die 122, the bonding wires 128, and is attached to the package substrate 112. A through-hole 138 is provided in the encapsulating resin package 136, and the through-hole 138 exposes the optical sensor 124 of the optical integrated circuit die 122. The cross-sectional area of the through-hole 138 is slightly larger than the cross-sectional area of the optical sensor 124 (but not so large as to expose the electrical connection die bonding pads 126 and / or the bonding wires 128, which remain encapsulated within the encapsulating resin package 136). An adhesive ring 130 is mounted to the front surface of the encapsulating resin package 136 to surround (i.e., encircle) the through-hole 138. A diffractive optical element (DOE) 134 (e.g., including one or more of an optical lens and an optical filter (e.g., an infrared (IR) filter) and having a flat plate form) is attached to the front surface of the encapsulating resin package 136 using the adhesive ring 130. The DOE 134 is positioned to extend over the through-hole 138 and the optical sensor 124 of the optical integrated circuit die 122.

[0023] Reference Figure 3 , which shows a cross-sectional view of the optical integrated circuit package 210. The package 210 is similar to Figure 2 the package 110. Figure 2 and Figure 3 Like reference numerals in Figure 2 refer to the same or similar components. The package 210 differs from the package 110 of Figure 3The via 138 in the encapsulation resin encapsulant 136 in the encapsulation 210 includes a first sub - opening 138a and a second sub - opening 138b. The first sub - opening 138a has a first cross - sectional area that is slightly larger than the cross - sectional area of the optical sensor 124 (but not so large as to expose the electrical connection die bond pads 126 and / or the bond wires 128, which remain encapsulated within the encapsulation resin encapsulant 136). The second sub - opening 138b has a second cross - sectional area that is larger than the first cross - sectional area (and is also slightly larger than the cross - sectional area of the DOE 134 and can be larger than the area of the optical integrated circuit die 122). The first sub - opening 138a and the second sub - opening 138b are aligned with each other (e.g., they can be concentric openings). Due to the alignment of the sub - openings 138a, 138b and the different cross - sectional area dimensions of the sub - openings 138a, 138b, the overall via 138 includes a ledge 138c that peripherally surrounds the first sub - opening 138a. The adhesive ring 130 is mounted to the ledge 138c of the encapsulation resin encapsulant 136 to surround (i.e., encircle) the first sub - opening 138a. The DOE 134 is mounted to the ledge 138c using the adhesive ring 130. The DOE 134 is thus positioned within the second sub - opening 138b and extends over the optical sensor 124 of the first sub - opening 138a and the optical integrated circuit die 122. In an embodiment, the adhesive ring 130 can include an epoxy bead or an adhesive film layer.

[0024] Now refer Figure 4A - Figure 4M , these figures illustrate steps in a process for manufacturing an encapsulation 110 as shown in Figure 2 .

[0025] Figure 4A – The integrated circuit wafer 200 includes a plurality of integrated circuits 202 that are separated from each other by scribes 204. Figure 4A Illustrated is a portion of the wafer 200 that contains two such circuits 202. The wafer 200 is prepared using conventional front - end - of - line (FEOL), middle - end - of - line (MEOL), and back - end - of - line (BEOL) processing operations. Each integrated circuit 202 includes an optical sensor 124 (e.g., formed by an array of photosensitive elements) associated with a surface (e.g., the front surface) and a plurality of electrical connection die bond pads 126. The front surface of the wafer 200 can be provided, for example, by an upper passivation layer structure.

[0026] Figure 4B – A layer of photoresist material 206 is deposited on the front surface of the wafer 200.

[0027] Figure 4C– The layer 206 is lithographically patterned using conventional lithography processing techniques to form a sacrificial cover 208 over the optical sensor 124. The lithography processing techniques may include, for example: soft baking the layer 206; forming a pattern mask over the layer 206, where the pattern mask includes an opening at the location of the optical sensor 124; exposing the layer 206 through the mask opening; and developing the layer 206 to remove the unexposed portions of the layer 206 while leaving the exposed portions of the layer in place to form the sacrificial cover 208.

[0028] Figure 4D – The wafer 200 is diced at the scribe lines 204 to divide (also known as singulating in the art) the wafer 200 into a plurality of optical integrated circuit dies 122. During the division (singulation) of the wafer 200, the scribe lines 204 may be cut, for example, using a saw or a laser (schematically indicated by the arrow 210). This operation does not disturb the sacrificial cover 208, which provides a hermetic protection over the optical sensor 124 to ensure that debris from the dicing process does not contaminate the optical sensor 124.

[0029] Figure 4E – The package substrate panel 300 is a multi-layer board structure 302, including a plurality of die mounting areas 304 separated from each other by the inter-die mounting areas 306. Each die mounting area 304 includes an interconnect network 116 (formed by connecting lines and vias) that electrically connects the front solder pads 118 to the back solder pads 120. The back solder pads 120 may include, for example, a portion of a redistribution layer (RDL). The back solder pads 120 may include, for example, support pads for pillars or balls (in a ball grid array (BGA) type package). The back solder pads 120 may include, for example, connection solder pads (in a land grid array (LGA) type package).

[0030] Figure 4F – As Figure 4A - Figure 4D produced by the steps of, the optical integrated circuit die 122 having the sacrificial cover 208 located over the position of the optical sensor 124 is then mounted to the upper surface of the package substrate panel 300 at each die mounting area 304. For example, the mounting of each optical integrated circuit die 122 having the cover 208 can be achieved using a pick-and-place process with a suitable adhesive material (e.g., a die attach film (DAF)) positioned between the bottom surface of the die 122 and the top surface of the package substrate panel 300.

[0031] Figure 4G – Then a wire bonding process is performed to wire bond each optical integrated circuit die 122 having the cover 208 to the package substrate panel 300. The wire bonding process forms bonding wires 128 that electrically connect the electrical connection die bond pads 126 of the optical integrated circuit die 122 to the front solder pads 118 of the interconnect network 116.

[0032] Figure 4H - 1 and Figure 4H - 2 – Then, a package substrate panel 300 having optical integrated circuit dies 122 (each die having a sacrificial cap 208) mounted thereon is placed within a cavity 320 of a mold 324. As shown in Figure 4H - 1 , the upper mold portion of the mold 324 is placed in contact with the upper surface of the sacrificial cap 208, and the lower mold portion of the mold 324 is placed in contact with the bottom surface of the package substrate panel 300. Alternatively, as shown in Figure 4H - 2 , only the bottom surface of the package substrate panel 300 is placed in contact with the lower mold portion of the mold 324.

[0033] Figure 4I - 1 and Figure 4I - 2 – Then, the cavity 320 of the mold 324 is filled with an encapsulation resin material 330 to produce an encapsulated panel structure 332.

[0034] The encapsulated panel structure 332 is removed from the mold 324. For the embodiments shown in Figure 4H - 2 and Figure 4I - 2 , a grinding or polishing operation is used to remove the encapsulation resin material 330 covering the sacrificial cap 208 such that the upper surface of the sacrificial cap 208 is exposed from the encapsulation resin material 330. Similarly, a grinding or polishing operation can be used to remove any unwanted encapsulation resin material 330 (e.g., in the form of molding flash) that may be present on the upper surface of the sacrificial cap 208 when molding is performed using the embodiments shown in Figure 4H - 1 and Figure 4I - 1 .

[0035] Although a two-piece mold 324 is shown as the main embodiment, the molding operation performed to encapsulate a package substrate panel 300 having optical integrated circuit dies 122 (each die having a sacrificial cap 208) mounted thereon and form an encapsulated panel structure 332 can alternatively be achieved using an open-top type one-piece mold that forms a dam around the package substrate panel 300. Then, the cavity of the open-top type one-piece mold is filled with an encapsulation resin material 300. If desired, the top of the encapsulated panel structure 332, after removal from the mold, can be treated with grinding or surface polishing to provide a flat upper surface and remove any unwanted portions of the encapsulation resin material that may be present on the upper surface of the sacrificial cap 208.

[0036] The resulting encapsulated panel structure 332 is as shown in Figure 4J .

[0037] It should be noted that, at this point in the process, support pads for the pillars 121p or balls 121b (in a ball grid array (BGA) type package) can be attached to the post pads 120.

[0038] Figure 4K – Then, a resist stripping process is used to remove the sacrificial cover 208 from the encapsulation panel structure 332. This leaves an opening 138 in the encapsulation panel structure 332 at each optical integrated circuit die 122, exposing the optical sensor 124.

[0039] Figure 4L – Then, the DOE 134 is mounted onto the upper surface of the encapsulation resin material 330 of the encapsulation panel structure 332 to cover each opening 138. In an embodiment, this mounting of the DOE 134 is achieved by using an adhesive ring 130 around the opening 138. The adhesive ring 130 can include, for example, an epoxy bead or a layer of adhesive film.

[0040] Figure 4M – Then, the encapsulation panel structure 332 is cut at the location of the die - to - die mounting area 306 to divide (also known as dicing in the art) the encapsulation panel structure 332 into a plurality of optical integrated circuit packages 110. During the division (dicing) of the encapsulation panel structure 332, the die - to - die mounting area 306 can be cut, for example, using a saw or a laser (schematically indicated by the arrow 210).

[0041] It is also possible to use Figure 4A - Figure 4M a process that makes some modifications at the stage of molding the encapsulation resin material 300 to form the encapsulation panel structure 332 and creating the second sub - opening 138b to produce the optical integrated circuit package 210. For example, the upper mold part of the mold 324 can include protrusions shaped like the second sub - opening 138b that are aligned with the position of each sacrificial cover 208 in the encapsulation substrate panel 300 on which the optical integrated circuit die 122 is mounted. The mold filling with the encapsulation resin material 300 around the protrusions in the upper mold part of the mold 324 forms the second sub - opening 138b, and then the sacrificial cover 208 is removed to form the second sub - opening 138b. The alignment of the protrusions with the position of the sacrificial cover 208 and the difference in the cross - sectional area of the protrusions relative to the cross - sectional area of the sacrificial cover 208 define the ledge 138c.

[0042] In an alternative embodiment, the steps of Figure 4L can be omitted to produce a glass - free (i.e., without DOE 134) optical integrated circuit package 410 as shown in Figure 5 .

[0043] Figure 2 、 Figure 3 and Figure 5 The optical integrated circuit packages in Figure 1The encapsulation in [reference] has many advantages, including: a) supporting the encapsulation of an optical integrated circuit die, wherein the size of the gap region between the periphery of the optical sensor at the front surface of the optical integrated circuit die and the electrical connection die bonding pads is reduced; b) supporting the production of packages with a smaller form factor and packages that occupy a smaller area; and c) using a sacrificial cover to protect the optical sensor during the encapsulation process. Relative to Figure 2 and Figure 3 the optical integrated circuit encapsulation in [reference], another advantage compared to the encapsulation of Figure 1 is that the DOE is mounted on the encapsulant rather than on the optical integrated circuit die, and since the material of the encapsulant acts as a stress buffer, the stress directly applied to the die is smaller.

[0044] Although the present invention has been described in detail in the drawings and the foregoing description, such description and illustration should be regarded as illustrative or exemplary and not restrictive; the present invention is not limited to the disclosed embodiments. Those skilled in the art, when practicing the claimed invention, can understand and implement other variations of the disclosed embodiments by studying the drawings, this disclosure, and the appended claims.

Claims

1. A method comprising: providing a package substrate panel including a plurality of die mounting areas separated from one another by inter-die mounting areas; At each die mounting area, mounting an optical integrated circuit die with a sacrificial cover over the location of an optical sensor; molding an encapsulation resin material on the packaging substrate panel to encapsulate the optical integrated circuit die and at least surround the sacrificial cover to form an encapsulation panel structure; removing the sacrificial cover to expose the optical sensor of the optical integrated circuit die; as well as The encapsulated panel structure is cut at the inter-die mounting regions to separate the encapsulated panel structure into a plurality of optical integrated circuit packages.

2. The method of claim 1, wherein: Each optical integrated circuit die includes a plurality of electrical connection die bond pads, and wherein the encapsulation resin material covers the electrical connection die bond pads.

3. The method of claim 2, further comprising wire bonding the electrical connection die bond pads of the optical integrated circuit die to the front electrical pads of the package substrate panel.

4. The method of claim 3, wherein: The encapsulating resin material also encapsulates bonding wires formed by the wire bonding.

5. The method of claim 1, wherein: Removing the sacrificial cover forms a through hole in the encapsulation resin material of the encapsulation panel structure above each optical sensor, and also includes covering each through hole with a diffractive optical element.

6. The method of claim 5, wherein: Covering includes bonding and mounting the diffractive optical element to the upper surface of the encapsulating panel structure.

7. The method of claim 5, wherein: The diffractive optical element includes one or more of a filter and a lens.

8. The method of claim 1, wherein: The encapsulation resin material is molded on the packaging substrate panel to form a sub-opening in the encapsulation resin material of the encapsulation panel structure above each sacrificial cover, and wherein the sacrificial cover is removed to form additional sub-openings in the encapsulation resin material of the encapsulation panel structure above each optical sensor, and also includes covering each additional sub-opening with a diffractive optical element positioned within the sub-opening.

9. The method of claim 8, wherein: The formation of the sub-openings defines a ledge surrounding each sacrificial cover, and wherein covering includes adhesively mounting the diffractive optical element to the ledge.

10. The method of claim 8, wherein: The diffractive optical element includes one or more of a filter and a lens.

11. The method of claim 1 , further comprising: providing an integrated circuit wafer, the integrated circuit wafer comprising a plurality of integrated circuits separated from each other by scribe lines; wherein each integrated circuit comprises said optical sensor; forming the sacrificial cover over the location of each optical sensor; and The integrated circuit wafer is cut at the scribe lines to separate the integrated circuit wafer into a plurality of optical integrated circuit dies.

12. An optical integrated circuit package, comprising: Package substrate; an optical integrated circuit die having an optical sensor and electrically connected die bond pads; an encapsulation resin package body located on the packaging substrate and encapsulating the optical integrated circuit die and the electrically connected die bonding pads of the optical integrated circuit die; wherein the encapsulating resin package includes a through opening exposing the optical sensor of the optical integrated circuit die; as well as A diffractive optical element is mounted on the surface of the encapsulating resin package so as to cover the through opening.

13. The optical integrated circuit package of claim 12, wherein: The opening comprises: a first sub-opening having a first cross-sectional area; a second sub-opening having a second cross-sectional area greater than the first cross-sectional area; wherein the first sub-opening is aligned with the second sub-opening; wherein the second sub-opening defines a ledge surrounding the first sub-opening; and The ledge is a surface of the encapsulating resin package on which the diffractive optical element is mounted.

14. The optical integrated circuit package of claim 12, further comprising bonding wires electrically connecting the electrical connection die bonding pads of the optical integrated circuit die to the front electrical pads of the package substrate, wherein the bonding wires are encapsulated within the encapsulation resin package.

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