US20010010952A1 - Color image sensor with embedded microlens array - Google Patents

Abstract

A method for producing a color CMOS image sensor including a matrix of pixels (e.g., CMOS APS cells) that are fabricated on a semiconductor substrate. A silicon-nitride layer is deposited on the upper surface of the pixels, and is etched using a reactive ion etching (RIE) process to form microlenses. A protective layer including a lower color transparent layer formed from a polymeric material, a color filter layer and an upper color transparent layer are then formed over the microlenses. Standard packaging techniques are then used to secure the upper color transparent layer to a glass substrate.

Description

FIELD OF THE INVENTION
• The present invention relates to solid state image sensors. More specifically, the present invention relates to a method for fabricating color image sensors and to a color image sensor fabricated by the method.[0001]
RELATED ART
• Solid state color image sensors are used, for example, in video cameras, and are presently realized in a number of forms including charge-coupled devices (CCDs) and CMOS image sensors. These image sensors are based on a two dimensional array of pixels. Each pixel includes color filter located over a sensing element. An array of microlenses located over the color filter focuses light from an optical image through the color filter into the image sensing elements. Each image sensing element is capable of converting a portion of the optical image passed by the color filter into an electronic signal. The electronic signals from all of the image sensing elements are then used to regenerate the optical image on, for example, a video monitor.[0002]
• FIG. 1(A) is a cross-sectional view showing a portion of a conventional[0003]color image sensor10.Color image sensor10 is formed on an n-type semiconductor substrate11 having a p-well layer15. An array ofphotodiodes20 andcharge transfer regions25 are formed in p-well layer15, and are covered by a silicon oxide ornitride film30. Apolysilicon electrode35 is located overcharge transfer region25 such that it is surrounded byfilm30. A photo-shielding metal layer40 is formed overelectrode35, and a surfaceprotective coating45 and aplanarization layer50 are formed overmetal layer40. Acolor filter layer60 is formed onplanarization layer50, and an intermediatetransparent film70 is formed overcolor filter layer60. Amicrolens80 for focusinglight beams85 is formed from silicon dioxide (SiO₂) or a resin material on intermediatetransparent film70. Anair gap90 is provided overmicrolens80, and aglass packaging substrate95 is located overair gap90.
• In operation,[0004]light beams85 are focused bymicrolens80 throughcolor filter layer60 such that they converge along the focal axis F ofmicrolens80 to strikephotodiode20, wherein photoenergy fromlight beams85 frees electrons inphotodiode20. When a select voltage is applied topolysilicon electrode35, these freed electrons generate a current incharge transfer region25. A sensor circuit (not shown) ofcolor image sensor10 then determines the amount of light received byphotodiode20 by measuring the amount of current generated incharge transfer region25.
• Conventional solid-[0005]state imaging device10 is designed forlight beams85 whose incident angle is perpendicular tosubstrate11, as shown in FIG. 1(A), before being focused bymicrolens80 ontophotodiode20. However, during actual operation ofcolor image sensor10, light beams can strikemicrolens80 at oblique incident angles. A consequence of these oblique light beams is shown in FIG. 1(B). In particular,light beams87 entermicrolens80 at an oblique angle, which directslight beams87 away from focal axis F such that they converge at the edge ofphotodiode20. Because the photoenergy oflight beams87 is not fully transferred tophotodiode20,color image sensor10 is unable to generate an accurate image.
• Another problem associated with conventional solid-[0006]state imaging device10 is that non-standard packaging methods are required due to the formation ofmicrolenses80 overcolor filter layer60 andintermediate transfer layer70. Standard packaging methods typically include securing a glass substrate to an IC device using a layer of cement (e.g., epoxy). This cement typically has an index of refraction that is the same as silicon-dioxide and other resins typically used to formmicrolens80 and other layers of conventional solid-state imaging device10. Therefore, to facilitate proper focusing of the light beams,air gap90 must be provided betweenglass packaging substrate95 andmicrolens80. Becauseair gap90 is used in place of cement, the packaging method used to produce conventional solid-state imaging device10 is non-standard.
• It would be possible to avoid the oblique light beam problem (discussed above) by moving[0007]microlens80 closer tophotodiode20, thereby shortening the distance traveled by the light beams betweenmicrolens80 andphotodiode20. This shortened distance would reduce the displacement of focused oblique light beams87 (see FIG. 1(B)) relative to the center ofphotodiode20, thereby transferring more photoenergy from these oblique light beams tophotodiode20.
• One possible method of moving[0008]microlens80 closer tophotodiode20 would be to reduce the thickness of the various layers located belowmicrolens80. A problem with this method is that the thicknesses of these underlying layers are not easily reduced. First, photo-shielding layer40 is typically formed during the formation of aluminum wiring utilized to transmit signals to and from each pixel of conventional solid-state imaging device10. Therefore, the thickness of photo-shielding layer40 is limited by the wiring specifications. Repositioningmicrolens80 closer tophotodiode20 is further restricted byplanarization layer50, which is required to provide a flat surface for formingcolor filter layer60 andmicrolens80. Therefore, it is not possible to significantly reduce the distance between a surface-mountedmicrolens80 andphotodiode20 in conventional solid-state imaging device10 by reducing the thickness of thelayers underlying microlens80.
• Another possible method of moving[0009]microlens80 closer tophotodiode20 would be to form microlens So under color filter layer60 (i.e., betweenphotodiode20 and color filter layer60). This arrangement would also address the non-standard packaging problem because, with color filter layer70-located abovemicrolens80, it would be possible to use cement to secureglass packaging substrate95 according to standard packaging methods. However, formingmicrolens80 undercolor filter layer60 is not practical because, as discussed above, the index of refraction of conventional microlens materials (i.e., resin) is the same as that of other materials typically used to produce conventional solid-state imaging device10. Therefore, becauseair gap90 must be provided overconventional microlens80, it would be very difficult to produce conventional solid-state imaging device10 withmicrolens80 located undercolor filter layer60 using conventional microlens materials.
• What is needed is a method for fabricating a color image sensor that minimizes the distance between the microlens and photodiode, and minimizes the fabrication and production costs of the color image sensor.[0010]
SUMMARY
• The present invention is directed to a method for producing a color CMOS image sensor in which the microlens structure is embedded (i.e., located between the photodiode array and the color filter layer), thereby avoiding the oblique light beam problem, discussed above, because each microlens is located closer to its associated photodiode than in conventional image sensor structures. In addition, because the color filter layer is located above the microlenses and sandwiched between two color transparent layers, conventional image sensor packaging techniques (i.e., applying cement to the upper color transparent layer, then applying a glass substrate) may be utilized to produce color CMOS image sensors.[0011]
• In accordance with a first embodiment of the present invention, an image sensor is produced by depositing a dielectric (e.g., silicon-nitride) layer over an image sensing element (e.g., a photodiode), etching the dielectric layer to form a microlens, and then depositing a protective layer on the microlens, wherein the protective layer has an index of refraction that is different from that of the dielectric. When silicon-nitride is utilized as the dielectric, conventional protective layer materials may be formed on the microlens because the refractive index of silicon-nitride is different from silicon-dioxide and other materials utilized as conventional protective layer materials. Therefore, the silicon-nitride microlenses of the present invention may be embedded under conventional protective materials without eliminating the optical performance of the microlenses. In alternative embodiments, other dielectrics may be used to form the microlens, provided the protective materials formed on the microlens have an index of refraction that is different from that of the dielectric. Because the microlens surface is located below a protective layer, conventional packaging techniques may be used that attach the protective layer to a substrate using cement, thereby reducing manufacturing costs and complexity.[0012]
• In accordance with another embodiment of the present invention, a color image sensor is produced by depositing a silicon-nitride layer over an image sensing element (e.g., a photodiode), etching the silicon-nitride layer to form a microlens, depositing a color transparent layer on the microlens, and then forming a color filter on the color transparent layer. The silicon-nitride microlens has an index of refraction that is different from the color transparent layer, thereby forming an effective microlens structure that is embedded below the color filter. By forming the microlens below the color filter, the microlens is positioned closer to the image sensing element, thereby minimizing the oblique light beam problems, described above. In addition, by forming a second color transparent layer over the color filter, conventional packaging techniques may be used that attach the second color transparent layer to a substrate using cement, thereby reducing manufacturing costs and complexity.[0013]
• The novel aspects of the present invention will be more fully understood in view of the following description and drawings.[0014]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIGS.[0015]1(A) and1(B) are cross-sectional side views showing a conventional solid-state imaging device in which normal and oblique light beams are focused by a microlens;
• FIG. 2 is a schematic diagram of a solid-state imaging device according to a first embodiment of the present invention;[0016]
• FIG. 3 is a flow diagram showing the basic steps for fabricating the solid-state imaging device shown in FIG. 2;[0017]
• FIG. 4(A) is a schematic diagram of a color image sensor device according to a second embodiment of the present invention;[0018]
• FIG. 4(B) is a flow diagram showing the basic steps for fabricating the color image sensor device shown in FIG. 4(A); and[0019]
• FIGS.[0020]5(A) through5(K) are cross-sectional views showing process steps associated with the production of a color imaging device in accordance with another embodiment of the present invention.
DETAILED DESCRIPTION
• The present invention is described below with reference to color CMOS active-pixel sensors (APSs), and in particular to color CMOS APSs utilizing photodiode light sensitive regions. The fabrication and operation of CMOS active-pixel sensors (APSs) are described in co-owned and co-pending U.S. application Ser. No. 09/315,893, entitled “Method And Structure For Minimizing White Spots In CMOS Image Sensors”, invented by Yossi Netzer [Docket No. TSL-031], which is incorporated herein by reference. However, the methods and structures described below may also be used to produce passive CMOS image sensors and CMOS APSs utilizing photogate light sensitive regions. In addition, the methods and structures may be used to produce CMOS APSs having any number of transistors (e.g., one, four or five). Moreover, the present inventors believe the methods and structures of the present invention may also be used to produce image sensors including MOS pixel arrays. As used herein, the general phrase “image sensor” is intended to cover all of these sensor array types.[0021]
• FIG. 2 is a cross-sectional view showing a portion of an[0022]image sensor100 in accordance with an embodiment of the present invention.Image sensor100 includes animage sensing element110, adielectric layer140 formed overimage sensing element110 that is etched to include amicrolens145, and aprotective layer150 formed onmicrolens145.Image sensing element110 includes aphotodiode region114 that is diffused into asilicon substrate112, and apassivation layer118 formed onsubstrate112. In one embodiment,dielectric layer140 is formed onpassivation layer118, and has an index of refraction that is different from that ofprotective layer150, thereby allowingmicrolens145 to focus light beams passing throughprotective layer150 ontophotodiode region114. In another embodiment, one or more intermediate layers (e.g., oxi-nitride, not shown) are formed betweenpassivation layer118 anddielectric layer140.
• FIG. 3 is a flow diagram showing the basic steps associated with the formation of[0023]image sensor100 in accordance with the present invention. The process shown in FIG. 3 is performed after image sensing element110 (FIG. 2) is fabricated using known techniques. At the end of this initial fabrication process,image sensing element110 includespassivation layer118 formed overphotodiode region114.
• Referring to FIG. 3, the process begins with the deposition of[0024]dielectric layer140 over passivation layer118 (Step310). The term “rover” is intended to cover both the deposition of dielectric material directly onpassivation layer118, and the deposition of dielectric material on an intermediate layer(s) formed onpassivation layer118. In a presently preferred embodiment, dielectric material is silicon-nitride, which has an index of refraction that is higher than silicon-dioxide and other materials typically utilized in CMOS fabrication processes to formprotective layer150.
• Next,[0025]dielectric layer140 is etched to form microlenses145 (Step320). In one embodiment, this step is performed using a reactive-ion etching process according to known techniques. As indicated in FIG. 2, the etching process is controlled such that a portion ofdielectric layer140 remains overpassivation layer118.
• Finally,[0026]protective layer150 is formed overmicrolens145 and other residual portions of dielectric layer140 (Step330). In black-and-white image sensors,protective layer150 may be polyimide, resin, or may be packaging adhesive (e.g., epoxy cement) that is applied directly to the upper surface ofmicrolens145. As discussed in additional detail below, in color image sensor applicationsprotective layer150 may include one or more color transparent layers and color filter layers. In either of these applications, at least the portion ofprotective layer150 that contacts microlens145 is formed using a material having an index of refraction that is different from (i.e., lower than) that ofdielectric layer140. By forming protective layer in this manner, microlens145 is able to effectively focus light beams ontophotodiode region114. Further, becausemicrolens145 is formed either directly on or immediately overpassivation layer118, the distance betweenmicrolens145 andphotodiode114 is minimized, thereby minimizing the problems caused by oblique light beams (discussed above).
• While[0027]Steps310,320 and330 include the basic process steps for forming an image sensor in accordance with the present invention, another benefit ofimage sensor100 is that conventional packaging techniques may be utilized. In particular, a packaging substrate may be attached toprotective layer150 using a packaging adhesive, such as epoxy cement (Step340). Alternatively, whenprotective layer150 is formed from packaging adhesive, the packaging substrate is attached directly toprotective layer150. Unlike prior art image sensors that require air gaps between the microlens and the packaging substrate, the present invention facilitates the use of conventional packaging techniques (i.e., applying cement directly ontoprotective layer150 ormicrolens145, and attaching the packaging substrate directly to the cement), thereby reducing packaging costs.
• FIG. 4(A) is a cross-sectional view showing a portion of a[0028]color image sensor200 in accordance with a second aspect of the present invention.Color image sensor200 includes animage sensing element210, a silicon-nitride layer240 formed overimage sensing element210 that is etched to include amicrolens245, a lower (first) color transparent (CT)layer252 formed onmicrolens245, acolor filter layer255 formed onlower CT layer252, and anupper CT layer257 formed oncolor filter layer255. Similar to image sensor device100 (discussed above),image sensing element210 includes aphotodiode region214 that is formed insubstrate212, and a passivation region including silicon-dioxide (SiO₂)layer218 that is formed onsubstrate212.
• [0029]Lower CT layer252,color filter layer255 andupper CT layer257 form a color filter structure (protective layer)250 overmicrolens245 that functions, in part, to protectmicrolens245. In one embodiment,lower CT layer252 is formed from a polymeric material (e.g., negative photoresist based on an acrylic polymer) having an index of refraction that is lower than that of silicon-nitride, thereby allowing8microlens245 to focus light beams passing throughlower CT layer252 ontophotodiode region214.Lower CT layer252 provides both a planar surface and adhesion forcolor filter layer255.Color filter layer255 is formed from known materials (e.g., negative photoresist based on an acrylic polymer including color pigments) using known techniques. Finally,upper CT layer257 is formed from a polymeric material-(e.g., negative photoresist based on an acrylic polymer), and serves both to seal and protectcolor filter layer255.
• FIG. 4(B) is a flow diagram showing the basic steps associated with the formation of[0030]color image sensor200 in accordance with the present invention. The process shown in FIG. 4(B) is performed after image sensing element210 (FIG. 4(A)) is fabricated using known techniques.
• Referring to FIG. 4(B), silicon-[0031]nitride layer240 is deposited over silicon-dioxide layer218 (Step410), and silicon-nitride layer240 is etched to form microlenses245 (Step420). Next,lower CT layer252 is formed overmicrolens245 and other residual portions of silicon-nitride layer240, and is then planarized using known techniques (Step430).Color filter layer255 is then formed onlower CT layer252 using known techniques (Step440). Finally,upper CT layer257 is formed oncolor filter layer255. Although not shown in FIG. 4(B), a subsequent step of attaching a packaging substrate toupper CT layer257 using conventional packaging techniques is made possible by embeddingmicrolens245 belowcolor filter structure250.
• FIGS.[0032]5(A) through5(K) illustrate the method of producingcolor image sensor200 in additional detail.
• FIG. 5(A) is a cross-sectional view showing an initial structure that includes[0033]image sensing element210.Image sensing element210 includesphotodiode region214 and acharge transfer region215 that are diffused into semiconductor (e.g., silicon)substrate212, and base silicon-dioxide (SiO₂)layer218 formed onsubstrate212.Metal wires220 are located in base SiO₂layer218 that connect to apolysilicon gate region222 and to chargetransfer region215, thereby forming select transistor116. These structures are fabricated using known techniques.
• FIG. 5(B) illustrates an optional step of depositing a supplemental passivation (SiO[0034]₂)layer219 on base SiO₂layer218, and planarizing supplemental SiO₂layer219 to provide a flat surface for the dielectric material used to form the embedded microlens. The planarized surface provided by supplemental SiO₂layer219 is not always required (in some cases, base SiO₂layer218 has a sufficiently planar surface). When used, the thickness of supplemental SiO₂layer219 is determined by the surface features of base SiO₂layer118 (e.g., by exposed wires220), but made as thin as possible so that the subsequently-formed microlens structures are as close tophotodiode region214 as possible.
• FIG. 5(C) illustrates another optional step of depositing an oxi-[0035]nitride layer230 on planarized supplemental SiO₂layer219. Alternatively, oxi-nitride layer230 may be formed directly on base SiO₂layer219 (i.e., when planarized supplemental SiO₂layer219 is not used). In one embodiment, oxi-nitride layer230 has a thickness in the range of 2.5 to 3.5 microns, and functions as a stress relief layer.
• FIG. 5(D) illustrates a subsequent step of depositing silicon-[0036]nitride layer240 overimage sensing element210. When both steps shown in FIGS.5(B) and5(C) are used,8 silicon-nitride layer240 is formed on oxi-nitride layer230. Note that silicon-nitride layer240 may be formed on planarized supplemental SiO₂layer219 or base SiO₂layer218 if these steps are respectively omitted. In the present example, silicon-nitride layer240 has a thickness in the range of 3 to 5 microns.
• FIG. 5(E) is a cross-sectional view showing the formation of a[0037]photoresist portion510 on silicon-nitride layer240 and subsequent application ofetchant520.Photoresist portion510 is formed by depositing a layer of photoresist on silicon-nitride layer240, exposing the photoresist layer through a mask (either “halftone” or sharp geometry), developing the photoresist layer, and removing portions of the photoresist layer that were exposed. This process is performed using well-known techniques. When a sharp geometry mask is used,photoresist portion510 is heated to create the required lens-shaped geometry using known techniques. This heating process is not needed when a “halftone” mask is used to formphotoresist portion510. The resultingphotoresist portion510 has a shape that essentially mirrors than of the desired microlens and is located directly over the portion of silicon-nitride layer240 used to form the microlens. The actual shape ofphotoresist portion510 depends upon the selectivity of the photoresist material versus that of silicon-nitride layer240. Etching is subsequently performed using an anisotropic reactive ion etching (RIE) process that “copies” the lens-like shape ofphotoresist portion510 into silicon-nitride layer240. That is, the thinner peripheral portions ofphotoresist portion510 are removed before the thicker central portions, thereby causing more etching of silicon-nitride layer240 under the periphery ofphotoresist portion510 than under the central portion. Consequently, the lens-like shape ofphotoresist portion510 is “copied” into silicon-nitride layer240.
• FIG. 5(F) is a cross-sectional view showing silicon-[0038]nitride layer240 after the etching process. The resulting shape ofmicrolens240 is essentially the same as that ofphotoresist portion510. In one embodiment,microlens245 has a peak thickness T1 in the range of 3 to 5 microns. The remaining portions of silicon-nitride layer240 located adjacent to microlens245 have a thickness T2 in the range of 0.65 to 1 micron.Residual photoresist material515 and other polymeric residues are then removed using a solvent530.
• FIG. 5(G) is a cross-sectional view showing the subsequent deposition and planarization of[0039]lower CT layer252 onmicrolens245 and the remaining portions of silicon-nitride layer240. After planarization, lower CT layer preferably has a thickness T3 in the range of 1.1 to 1.3 microns.
• FIG. 5(H) is a cross-sectional view showing the subsequent formation of[0040]color filter layer255 onlower CT layer252.Color filter layer255 is formed using known techniques and has a resulting thickness T4 in the range of 1.0 to 1.4 microns.
• FIG. 5(I) is a cross-sectional view showing the subsequent formation of[0041]upper CT layer257 oncolor filter layer255.Upper CT layer257 is formed from polymeric material or resin, and has a resulting thickness T5 in the range of 0.8 to 1.1 microns.
• A benefit provided by the fabrication process illustrated in FIGS.[0042]5(A) through5(I) is that standard packaging techniques can be used, thereby reducing overall production costs. A simplified representation of these standard packaging techniques is depicted in FIGS.5(J) and5(K). As shown in FIG. 5(J), a transparent cement540 (e.g., novolac epoxy resin) is applied to an upper surface of upper colortransparent layer257. Next, as shown in FIG. 5(K), a packaging substrate550 (e.g., glass) is mounted ontocement540, thereby attachingpackaging substrate550 to colortransparent layer257. Note that, unlike the prior art structure shown in FIG. 1(A),microlens245 is embedded betweencolor filter structure250 andimage sensing element210. Therefore, the present invention facilitates the use of standard packaging (i.e., attachingpackaging substrate550 using cement), thereby providing such color CMOS image sensor devices at a lower cost than conventional devices.
• Although the invention has been described in connection with several embodiments, it is understood that this invention is not limited to the embodiments disclosed, but is capable of various modifications which would be apparent to a person skilled in the art. For example, the particular parameters set forth in the above examples are exemplary, and may be altered to meet the requirements of particular fabrication processes. Thus, the invention is limited only by the following claims.[0043]

Claims (20)

What is claimed is:

1. A method for forming a microlens over an image sensing element in an image sensor, the method comprising:

depositing a dielectric layer over the image sensing element, the dielectric layer having a first index of refraction;

reactive ion etching the dielectric layer to form a microlens; and

forming a protective layer on the microlens, the protective layer having a second index of refraction;

wherein the first index of refraction of the dielectric layer is different from the second index of refraction of the protective layer.

2. The method according to

claim 1

, wherein depositing the dielectric layer comprises depositing silicon nitride.

3. The method according to

claim 1

, wherein reactive ion etching comprises:

depositing photoresist layer on the dielectric layer;

forming the photoresist layer into a lens-shaped photoresist portion; and

performing an anisotropic reactive ion etching process such that the lens-shaped photoresist portion is copied into the dielectric layer, thereby forming the microlens.

4. The method according to

claim 1

, wherein forming the protective layer comprises depositing packaging adhesive directly onto the microlens.

5. The method according to

claim 1

, wherein forming the protective layer comprises:

depositing a lower color transparent layer over the microlens;

planarizing the lower color transparent layer;

forming a color filter layer on the lower color transparent layer; and

depositing an upper color transparent layer on the color filter layer.

6. The method according to

claim 5

, further comprising:

applying a cement layer to the upper color transparent layer; and

attaching a packaging substrate to the cement layer.

7. The method according to

claim 1

, further comprising attaching a packaging substrate to the protective layer.

8. The method according to

claim 1

, further comprising:

depositing a passivation layer over the image sensing element;

planarizing the passivation layer; and

depositing an oxi-nitride layer on an upper surface of the passivation layer,

wherein depositing the dielectric layer over the image sensing element comprises depositing a silicon-nitride layer on an upper surface of the oxi-nitride layer.

9. A method for forming a microlens over an image sensing element in a color image sensor, the method comprising:

depositing a silicon-nitride layer over the image sensing element;

etching the silicon-nitride layer to form a microlens;

forming a first color transparent layer on the microlens; and

forming a color filter on the first color transparent layer.

10. The method according to

claim 9

, further comprising forming a second color transparent layer on the color filter.

11. The method according to

claim 9

, wherein etching comprises:

depositing photoresist layer on the silicon-nitride layer;

forming the photoresist layer into a lens-shaped photoresist portion; and

performing an anisotropic reactive ion etching process such that the lens-shaped photoresist portion is copied into the silicon-nitride layer, thereby forming the microlens.

12. The method according to

claim 9

, further comprising:

applying a cement layer to the upper color transparent layer; and

attaching a packaging substrate to the cement layer.

13. The method according to

claim 9

, further comprising:

depositing a passivation layer over the image sensing element;

planarizing the passivation layer; and

depositing an oxi-nitride layer on an upper surface of the passivation layer,

wherein the silicon-nitride layer is deposited on an upper surface of the oxi-nitride layer.

14. An image sensor comprising:

an image sensing element formed in a semiconductor substrate;

a microlens located over the image sensing element, the microlens being formed from a dielectric material having a first index of refraction; and

a protective layer formed on the microlens, the protective layer having a second index of refraction,

wherein a first index of refraction of the dielectric material is different from the second index of refraction of the protective layer.

15. The image sensor according to

claim 14

, wherein the dielectric material is silicon-nitride.

16. The image sensor according to

claim 14

, wherein the protective layer comprises packaging cement.

17. The image sensor according to

claim 14

, wherein the protective layer comprises:

a lower color transparent layer formed on the microlens;

a color filter layer formed on the lower color transparent layer; and

an upper color transparent layer formed on the color filter layer.

18. The image sensor according to

claim 17

, wherein the lower color transparent layer comprises an acrylic polymer.

19. The image sensor according to

claim 17

, further comprising a packaging substrate attached to an upper surface of the upper color transparent layer.

20. The image sensor according to

claim 14

, further comprising:

a passivation layer formed over the image sensing element; and

an oxi-nitride layer formed on an upper surface of the passivation layer,

wherein the silicon-nitride layer Is deposited on an upper surface of the oxi-nitride layer.

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