Method for making image sensors using wafer-level processing and associated devices

The present disclosure relates to the field of electronic device manufacturing, and, more particularly, to image sensors and related methods.

Typically, electronic devices include one or more optical sensor modules for providing enhanced media functionality. For example, the typical electronic device may utilize the optical sensor modules for photo capturing and video teleconferencing. In the typical electronic device with multiple optical sensor modules, the primary optical sensor module has a high pixel density and an adjustable focus lens system, while the secondary optical sensor module is front-facing and has a lower pixel density. Also, the secondary optical sensor module may have a fixed focus lens system.

For example, U.S. Patent Application No. 2009/0057544 to Brodie et al, assigned to the present application's assignee, discloses a optical sensor module for a mobile device. The optical sensor module comprises a lens, a housing carrying the lens, and a lens cap over the lens and housing. The optical sensor module includes a barrel mechanism for adjusting the lens. During manufacture of an electronic device including one or more optical sensor modules, there is a desire to manufacture the electronic device as quickly as possible, particularly in mass production runs.

The typical optical sensor module is manufactured in a multi-step process. The first steps include semiconductor processing to provide the image sensor integrated circuit (IC). The next steps include some form of testing for the image sensor IC and packaging. The image sensor IC may be assembled into the optical sensor module, along with a lens and movable barrel if needed. This assembly of the optical sensor module may be performed manually or via machine. For example, in electronic devices that use surface mounted components, a pick-and-place (PNP) machine may assemble the components onto a printed circuit board (PCB). A drawback to such singular packaging is that it is inefficient and also may require that each device be tested individually, adding to the manufacturing time.

In view of the foregoing background, it is therefore an object of the present disclosure to provide a method of making image sensor devices that is efficient and robust.

This and other objects, features, and advantages in accordance with the present disclosure are provided by a method of making a plurality of image sensor devices that may comprise forming a sensor layer comprising a plurality of image sensor integrated circuits (ICs) in an encapsulation material, bonding a spacer layer to the sensor layer. The spacer layer may have a plurality of openings therein and aligned with the plurality of image sensor ICs. The method may further include bonding a lens layer to the spacer layer, with the lens layer comprising a plurality of lenses in an encapsulation material and aligned with the plurality of openings and the plurality of image sensor ICs. The method may include dicing the bonded-together sensor, spacer and lens layers to provide the plurality of image sensor devices. For example, the bonded together layers may comprise wafer sized layers. Advantageously, this wafer-level processing (WLP) method may extend the wafer fabrication process to include device interconnection and device protection processes.

More specifically, the method may further comprise forming at least one electrically conductive via in the sensor layer, forming first and second electrically conductive layers respectively on first and second sides of the sensor layer, and forming a plurality of electrically conductive contacts on the first side of the sensor layer. The method may further comprise forming an adhesive layer on the second side of the sensor layer. For example, the plurality of electrically conductive contacts may comprise a ball grid array of electrically conductive contacts. The method may further comprise forming a passivation layer on each of the first and second sides of the sensor layer.

Additionally, the forming of the sensor layer may comprise positioning the plurality of image sensor ICs on a first carrier layer, forming the encapsulation material on the plurality of image sensor ICs and the first carrier layer, and removing the first carrier layer. In some embodiments, the method may further comprise forming the spacer layer by at least positioning a plurality of sacrificial bodies on a second carrier layer, forming encapsulation material on the plurality of sacrificial bodies and the second carrier layer, and removing the second carrier layer. Also, the forming of the spacer layer may comprise thinning the spacer layer so that a thickness of the spacer layer is equal with that of each sacrificial body, forming an adhesive layer on the encapsulation material, forming recesses in the adhesive layer over each of the sacrificial bodies, and etching the plurality of sacrificial bodies to define the plurality of openings.

Moreover, the method may further comprise forming the lens layer by at least forming a coating layer on a glass layer, dicing the glass layer to define the plurality of lenses, and positioning the plurality of lenses on a third carrier layer. The forming of the lens layer may further comprise forming the encapsulation material on the plurality of lenses and the third carrier layer, thinning the lens layer so that a thickness of the encapsulation material is equal to that of the plurality of lenses, and removing the third carrier layer.

Another aspect is directed to an image sensor device that may comprise a sensor layer having first and second sides and comprising an encapsulation material layer, and a plurality of image sensor ICs therein, and a spacer layer over the first side of the sensor layer and comprising a plurality of openings therein aligned with the plurality of image sensor ICs. The image sensor device may also include a lens layer over the spacer layer and comprising an encapsulation material layer, and a plurality of lenses therein and aligned with the plurality of openings and the plurality of image sensor ICs.

FIG. 1 is a cross-section view of a plurality of image sensor devices, according to the present disclosure.

FIG. 2 is an exploded view of the lens layer, the spacer layer, and sensor layer from the plurality of image sensor devices of FIG. 1 .

FIGS. 3A-3F are cross-section views of steps for forming the sensor layer of the image sensor devices of FIG. 1 .

FIGS. 4A-4G are cross-section views of steps for forming the spacer layer of the image sensor devices of FIG. 1 .

FIGS. 5A-5H are cross-section views of steps for forming the lens layer of the image sensor devices of FIG. 1 .

The present embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments are shown. This present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present embodiments to those skilled in the art. Like numbers refer to like elements throughout.

Referring to FIGS. 1-2 , an image sensor device 30 a , 30 b according to the present disclosure is now described. The image sensor device 30 a , 30 b illustratively includes a sensor layer 13 having first and second sides and comprising an encapsulation material layer 20 , and a plurality of image sensor ICs 24 a - 24 b therein, and a spacer layer 12 over the first side of the sensor layer and comprising a plurality of openings 45 a - 45 b therein aligned with the plurality of image sensor ICs. In FIG. 1 , only two image sensor devices 30 a , 30 b are illustratively shown. The image sensor device 30 a , 30 b illustratively includes a lens layer 11 over the spacer layer 12 and comprising an encapsulation material layer 15 , and a plurality of lenses 14 a - 14 b therein and aligned with the plurality of openings 45 a - 45 b and the plurality of image sensor ICs 24 a - 24 b.

The image sensor device 30 a , 30 b illustratively includes a first adhesive layer 16 between the lens layer 11 and the spacer layer 12 , and a second adhesive layer 18 between the spacer layer and the sensor layer 13 . The image sensor device 30 a , 30 b illustratively includes a plurality of electrically conductive contacts 23 a - 23 b on the first side (i.e. backside) of the sensor layer 13 . For example, the plurality of electrically conductive contacts 23 a - 23 b illustratively comprises a ball grid array of electrically conductive contacts.

The sensor layer 13 comprises a plurality of electrically conductive vias 21 extending between first and second sides thereof. The image sensor device 30 a , 30 b illustratively includes first and second electrically conductive layers 26 , 25 respectively on the first and second sides of the sensor layer 13 , each being coupled to the electrically conductive vias 21 .

Referring now additionally to FIGS. 3A-3F , a method of making the plurality of image sensor devices 30 a , 30 b according to the present disclosure is now described. The method comprises forming the sensor layer 13 comprising the plurality of image sensor ICs 24 a - 24 b in an encapsulation material 20 . In particular, the forming of the sensor layer 13 illustratively includes positioning the plurality of image sensor ICs 24 a - 24 b on a first carrier layer 40 , forming the encapsulation material 20 on the plurality of image sensor ICs and the first carrier layer, and removing the first carrier layer.

Additionally, the method illustratively comprises forming the plurality of electrically conductive vias 21 in the sensor layer 13 , forming first and second electrically conductive layers 26 , 25 respectively on first and second sides of the sensor layer, and forming a plurality of electrically conductive contacts 23 a - 23 b on the first side of the sensor layer. The method further comprises forming an adhesive layer 18 on the second side of the sensor layer 13 . For example, in the illustrated embodiment, the plurality of electrically conductive contacts 23 a - 23 b comprises a ball grid array of electrically conductive contacts. The method further comprises forming a passivation layer 19 , 22 on each of the first and second sides of the sensor layer 13 .

Referring now additionally to FIGS. 4A-4G , the method also includes bonding the spacer layer 12 to the sensor layer 13 . The spacer layer 12 illustratively includes a plurality of openings 45 a - 45 b therein and aligned with the plurality of image sensor ICs 24 a - 24 b . The forming of the spacer layer 12 illustratively includes positioning a plurality of sacrificial bodies 41 a - 41 b on a second carrier layer 43 (using an adhesive material 42 thereon), forming encapsulation material 17 on the plurality of sacrificial bodies and the second carrier layer, and removing the second carrier layer. Also, the forming of the spacer layer 12 comprises thinning the spacer layer so that a thickness of the spacer layer is equal with that of each sacrificial body 41 a - 41 b , forming an adhesive layer 16 on the encapsulation material, forming recesses 62 a - 62 b in the adhesive layer over each of the sacrificial bodies, and etching the plurality of sacrificial bodies to define the plurality of openings 45 a - 45 b.

Referring now additionally to FIGS. 5A-5H the method also includes bonding the lens layer 11 to the spacer layer 12 , the lens layer comprising the plurality of lenses 14 a - 14 b in an encapsulation material 15 and aligned with the plurality of openings 45 a - 45 b and the plurality of image sensor ICs 24 a - 24 b.

Moreover, the forming of the lens layer 11 comprises forming a coating layer 52 on a glass layer 51 , dicing the glass layer to define the plurality of lenses 14 a - 14 b , and positioning the plurality of lenses on a third carrier layer 53 . The forming of the lens layer 11 further comprises forming the encapsulation material 15 on the diced glass layer 51 and the third carrier layer 53 , thinning the lens layer so that a thickness of the encapsulation material is equal to that of the plurality of lenses 14 a - 14 b , and removing the third carrier layer.

The method illustratively includes dicing the bonded-together sensor 13 , spacer 12 and lens 11 layers to provide the plurality of image sensor devices 30 a , 30 b . As shown in FIG. 1 , a schematic box 61 represents a potential dicing cut line, singularizing the image sensor devices 30 a , 30 b . For example, as perhaps best seen in FIG. 2 , the bonded together layers 11 - 13 may comprise wafer sized layers 10 . Advantageously, the method may provide a large number of image sensor devices on a wafer level.

Advantageously, the herein disclosed method may manufacture the image sensor devices 30 a , 30 b using WLP. This may reduce the cost and time associated with large production runs. Moreover, it allows for a single alignment and bonding process, more like batch processing, instead of a single unit process, which is more costly.

Another aspect is directed to an image sensor device 30 a , 30 b that may comprise a sensor layer 13 having first and second sides and comprising an encapsulation material layer 20 , and a plurality of image sensor ICs 24 a - 24 b therein, and a spacer layer 12 over the first side of the sensor layer and comprising a plurality of openings 45 a - 45 b therein aligned with the plurality of image sensor ICs. The image sensor device 30 a , 30 b may also include a lens layer 11 over the spacer layer 12 and comprising an encapsulation material layer 15 , and a plurality of lenses 14 a - 14 b therein and aligned with the plurality of openings 45 a - 45 b and the plurality of image sensor ICs 24 a - 24 b.

Many modifications and other embodiments of the present disclosure will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the present disclosure is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.