Present application advocates the rights and interests of No. 61/789,013 U.S. Provisional Application case filed in 15 days March in 2013.TheNo. 61/789,013 U.S. Provisional Application case is hereby incorporated herein by hereby.
Embodiment
The embodiment of the imaging sensor described herein for possessing the pixel with increased optical crosstalk.It is described belowIn, numerous specific details are stated to provide a thorough understanding of embodiments.However, those skilled in the relevant art it will be recognized thatTechnology described herein can without one of described specific detail or it is one or more of in the case of practice or canPut into practice by other methods, component, material etc..In other examples, not showing or describing in detail well-known structure, materialMaterial operates to avoid making some aspects from obscuring.
Referring to for " one embodiment " or " embodiment " is meant with reference to the embodiment institute in the whole text in this specificationSpecial characteristic, structure or the characteristic of description are contained at least one embodiment of the present invention.Therefore, in this specification in the whole textThe appearance of phrase " in one embodiment " or " in one embodiment " are not necessarily all referring to same embodiment in each position.ThisOutside, the special characteristic, structure or characteristic can be combined in any suitable manner in one or more embodiments.
Fig. 1 is the block diagram for illustrating imaging sensor 100 according to an embodiment of the invention.Imaging sensor 100Illustrated embodiment includes the zone of action (that is, pel array 105), reading circuit 110, function logic 115 and control electricityRoad 120.
Pel array 105 can for dorsal part or front side-illuminated formula imaging pixel (for example, pixel PD1 ..., Pn) two-dimentional battle arrayRow.In one embodiment, each pixel is effect element sensor (" APS "), such as complementary metal oxide semiconductor(" CMOS ") imaging pixel.As illustrated, each pixel is arranged into a line (for example, row R1 to Ry) and a row (for example, rowC1 to Cx) in obtain people, place or the view data of object, described image data then can be used reproduce the people,The image of point or object.
After each pixel has obtained its view data or image charge, described image data are read by reading circuit 110Go out and be sent to function logic 115.Reading circuit 110 can include amplifying circuit, analog/digital conversion circuit or other.Function logic115 can only store described image data or even by effect after application image (for example, cut out, rotate, remove blood-shot eye illness, adjustmentBrightness, adjustment contrast or other) manipulate described image data.In one embodiment, reading circuit 110 can be along readingAlignment once reads a line view data (illustrated) or can be used a variety of other technologies (not illustrating) readings describedView data, such as series read-out or all pixels of full parellel reading simultaneously.
Control circuit 120 is coupled to pel array 105 to control the operating characteristic of pel array 105.For example, controlCircuit 120 can produce the shutter signal for controlling image to obtain.
Fig. 2 is the figure of the pel array 200 for the imaging sensor that embodiments in accordance with the present invention illustrate RGBC patterns.Array 200 is a possible embodiment of Fig. 1 pel array 105.It can be included in the zone of action of imaging sensor severalColour imaging pixel, such as red (R), green (G) and blue (B) imaging pixel.In imaging sensor also comprising transparent orThe pixel of further referred to as panchromatic (P).Fig. 2 shows wherein transparent diagonal 204- of (that is, panchromatic (the P)) pixel along array 200206 arrange to form a possible RGBC pattern of checkerboard pattern.However, when transparent pixels are arranged on diagonal, colorObscuring to occur.As mentioned above, color, which is obscured, refers to wrong color and appears in effect in the region of image.CitingFor, for example red or blueness color can be seen in the region that should be green.In the RGBC patterns shown in fig. 2,Color obscure can at least partially due to transparent filter diagonally 204-206 alignment and in those diagonal sidesOccur upwards.
Therefore, embodiments of the invention intentionally increase the optical crosstalk in pel array to reduce the effect that color is obscuredShould.Optical crosstalk refer to when the light being guided at object pixel it is spuious into adjacent pixel when.In Conventional image sensor, lightIt is the adverse effect being mitigated to learn crosstalk, because can often make the realistic colour information of object pixel from the spuious light of adjacent pixelDistortion.However, optical crosstalk, which has, blends the color of object pixel pixel adjacent thereto expecting of reducing that color obscures wherebyLess than benefit.Embodiments of the invention intentionally induce and/or increased the light of the desired characteristics as cmos image sensorCrosstalk is learned to reduce the effect that color is obscured.
Fig. 3 is to illustrate the flow chart that embodiments in accordance with the present invention reduce the process 300 that color is obscured.As in Fig. 3Shown, process 300 is included in the first process frame 305 that light is received at the first lenticule of the first pixel.In process frame 310In, light is received also at the second lenticule of the second pixel.In process frame 315, the light received at the first lenticule is drawnThe light-sensitive element to the second pixel is led to increase optical crosstalk.By way of example, Fig. 4 A are with increased optical crosstalkBackside illuminated imaging (BSI) sensor 400 three pixels (that is, pixel 1, pixel 2 and pixel 3) cross-sectional view.IntoIt is a possible embodiment party of at least some pixels in the pixel included in Fig. 1 pel array 105 as sensor 400Case.
The illustrated example of imaging sensor 400 is shown as comprising the front side for being placed in Semiconductor substrate 404Metal level 402 on (that is, such as the bottom side oriented in Figure 4 A) and the dorsal part (that is, top side) for being placed in Semiconductor substrate 404On planarization/passivation layer 406.Each pixel of imaging sensor 400 includes optical filter (that is, 408-412), lenticule (i.e.,414-418) and light-sensitive element (that is, photodiode 420-424).Fig. 4 A lenticule 414-418 is convex lens.It is more specific nextSay, each lenticule has plano-convex exterior shape.Planoconvex spotlight can make light convergence and referred to as positive lens due to it.Fig. 4 A are illustrated inThe light received at each pixel converges to the focus (that is, 430,432 substantially in the top of light incident side 438 of photodiodeAnd 434) so that at least some light in the light received at each lenticule are directed into the photodiode of neighborhood pixels.For example, light 428 is received at lenticule 416, wherein some light in the light are respectively directed to neighborhood pixels 1 and 3Photodiode 420 and 424.Similarly, some light in the light 426 received at lenticule 414 are directed into neighbouring pictureThe photodiode 422 of element 2.Therefore, imaging sensor 400 intentionally induces and/or increased optical crosstalk, as mentioned aboveAnd, this can reduce the effect that color is obscured.
In the presence of several embodiments of the imaging sensor 400 for inducing and/or increasing optical crosstalk.In one embodimentIn, pixel can be made for higher.In Fig. 4 A illustrated example, each pixel has can be from the bottom side of lenticuleThe 436 height H measured to the light incident side 438 of photodiode.Can be (such as micro- by increasing one or more elementsMirror, optical filter, complanation layer 406 and Semiconductor substrate 404) thickness the height H of pixel is made for it is larger to increase opticsCrosstalk.The height H of pixel can be also adjusted by changing the junction depth of each photodiode, following article will be more detailed with reference to Fig. 7Carefully discuss.
In another embodiment, it can be lured by reducing effective depth of focus of each focus (that is, focus 430,432 and 434)Hair and/or increase optical crosstalk.Can be approximately from the bottom side 436 of lenticule to the distance of focus, so as to consider by effective depth of focus DThe characteristic of the medium (for example, lenticule, optical filter, complanation layer and substrate) passed through wherein to light.In an example, lead toCross and change the material of lenticule to change (for example, increase) refractive index to reduce effective depth of focus D.In another example, it can changeThe curvature of lenticule is shorter so as to which effective depth of focus D is made for.By way of example, the curvature of lenticule is bigger, effective depth of focusIt is shorter.Again in another example, the thickness for changing lenticule also changes effective depth of focus.By way of example, lenticule is thicker, hasImitate depth of focus shorter.
No matter using which embodiment of increase optical crosstalk, embodiment disclosed herein is provided which suitably and onlyThe optical crosstalk increase of amount.That is, the optical crosstalk of the desired amount can be comprising directing light to adjacent photodiode and notFurther guiding.Therefore, in an example, light is only directed to the photodiode of adjacent pixels.In one embodiment,This can be by adjusting pixels tall H, effective depth of focus D or both combination so that effective depth of focus D is more than or equal to pixels tall H'sA quarter is realized.In addition, want the increased optical crosstalk of minimum in order to ensure realizing, adjustable pixels tall and/Or depth of focus D causes effective depth of focus D to be less than or equal to pixels tall H half.
As mentioned above, the dorsal part that imaging sensor 400 is incident in for wherein light on the dorsal part of imaging sensor 400 shinesMing Dynasty style imaging sensor.However, embodiment disclosed herein is also applied equally to front side-illuminated formula (FSI) imaging sensingDevice.For example, Fig. 4 B are the front side-illuminated formula imaging sensors 400 ' that embodiments in accordance with the present invention have increased crosstalkThree pixels cross-sectional view.The illustrated example of front side-illuminated formula imaging sensor 400 ' is shown as comprising placementMetal level 402 on the front side (that is, top side) of Semiconductor substrate 404.Complanation layer 406, optical filter 408-418 and lenticule414-418 is also placed on the front side of imaging sensor 400 ' (that is, top side).It is discussed herein above to be used to induce and/or increaseThe embodiment of optical crosstalk in imaging sensor 400 is applied equally to Fig. 4 B front side-illuminated formula imaging sensor 400 ',The height H of pixel only can be increased in addition by increasing the thickness of metal level 402.
In Fig. 4 A and 4B illustrated example, each pixel has identical pixels tall H and effective depth of focus D.Therefore, incident light is directed at least one neighborhood pixels by each pixel in array.Or, only some pixels can be configuredTo increase optical crosstalk.That is, incident light can be directed on the photodiode of neighborhood pixels by some pixels, and it is describedNeighborhood pixels are by the fenced photodiode to its own of incident light.By way of example, colour element is made to increase crosstalk but notIt can be favourable transparent pixels is increased crosstalk.In other words, the light being incident in colour element can be directed into adjacent transparentIn pixel, but it is incident in the light on transparent pixels and will be substantially held in the transparent pixels.In order to illustrate, Fig. 5 isEmbodiments in accordance with the present invention have the cross-sectional view of three pixels of the imaging sensor 500 of the lenticule of the curvature of change.As can be seen, nearly lenticule 514 and 518 is more curved near lenticule 516.Therefore, effective depth of focus D2 of focus 530 and 534 is bigIn effective depth of focus D1 of focus 532.In one embodiment, effective depth of focus D2 is more than the height H of pixel half so as to by lightIt is enclosed in pixel 1 and 3.In addition, optical filter 508 and 512 can be transparent (that is, panchromatic) optical filter, and optical filter 510 is colour(for example, red, green or blueness) optical filter.In this way, the light being incident on the lenticule 514 of transparent pixels 1 is channeledTo be substantially incident on photodiode 420 without being incident on other photodiodes.Similarly, transparent pixels are incident inLight on 3 lenticule 518 is channeled to be substantially incident on photodiode 424 without being incident in other photodiodesOn, and at least some light in the light being incident on the lenticule 516 of colour element 2 are directed into the photoelectricity of neighbouring transparent pixelsOn both diodes 420 and 424.
A common process for making lenticule can relate to use press mold pressing resin, subsequently then heat (backflow) step.Therefore, the common process can only produce the lenticule of convex shape due to surface tension.If made for each lenticuleWith the resin of similar quantity, then gained lenticule is by with the effective depth of focus of substantially the same curvature and therefore identical.In order toThe lenticule with different curvature is made, the technique using gray scale mask can be used.For example, will be photic by gray scale maskResist-type microlens material layer is exposed to light source.Need only single exposure.Microlens layer be more exposed to correspond to ashLarger thickness or relatively small thickness will be had by spending the part of the light of the part with high transmission of mask, and this depends on the layerIt is negative photoresist or positive photoresist.Similarly, microlens layer have less exposure to covered corresponding to gray scaleThe part of the light with relatively low radioparent part of mould will have relatively small thickness or larger thickness, and it is negative that this, which depends on the layer,Property photoresist or positive photoresist.Positive photoresist is the portion for being exposed to light of wherein photoresistDivide the photoresist for the type for becoming soluble in development of photoresist agent.The unexposed part of photoresist is kept notDissolve in development of photoresist agent.Negative photoresist is that the part for being exposed to light of wherein photoresist becomes notDissolve in the photoresist of the type of development of photoresist agent.The unexposed portion of photoresist is shown by photoresistShadow agent is dissolved.Therefore, it can develop to manufacture with many by the positive photoresist or negative photoresist for making to be exposed throughPlant the lenticule of curvature or shape.The curvature or shape of lenticule are the radioparent patterns of the change according to gray scale mask.
Fig. 6 is the lenticule 614-618 for the height that embodiments in accordance with the present invention have change imaging sensor 600The cross-sectional view of three pixels.As can be seen, lenticule 616 is higher than neighbouring lenticule 614 and 618.That is, lenticule616 height h2 is more than the height h1 of neighbouring lenticule 614 and 618.Therefore, effective depth of focus D2 of focus 630 and 634 is more than JiaoEffective depth of focus D1 of point 632 so that the light being incident on lenticule 616 is directed into photodiode 420 and 424, and incidentIt is enclosed in the light on lenticule 614 and 618 in its respective pixel.
Fig. 7 be embodiments in accordance with the present invention have change junction depth (for example, J1 and J2) light-sensitive element (for example,Photodiode 720-724) imaging sensor 700 three pixels cross-sectional view.In the illustrated embodiment,Junction depth refer to Semiconductor substrate 404 front side (that is, bottom side) between surface 702 and the light incident side of photodiode away fromFrom.For example, junction depth J1 is measured from the light incident side 704 of front side surface 702 and photodiode 720.Similarly,Junction depth J2 is measured from the light incident side 706 of front side surface 702 and photodiode 722.Can be during making by adjustingIt is whole to adjust junction depth being implanted into photodiode region 720-724 implantation energy.In one embodiment, implantation energy is got overHeight, junction depth is shorter.More implantation energy is generally taken to be penetrated into form photodiode region in substrate deeper, so thatCause deeper junction depth.In Fig. 7 illustrated example, the junction depth J2 of photodiode 722 is more than neighbouring photoelectricityThe junction depth J1 of diode 720 and 724.Therefore, as can be seen, the light being incident on lenticule 416 can be respectively directed to neighbourThe photodiode 720 and 724 of nearly pixel 1 and 3, and the light being incident on (for example) lenticule 414 is not incident in photoelectricityOn diode 722.Therefore, Fig. 7 embodiment can allow the optics string that pixel 2 increases on the photodiode of adjacent pixelsDisturb, and pixel 1 and 3 is not added to the optical crosstalk on the photodiode of pixel 2.
Fig. 4 A-7 foregoing lenticule is shown and is described as convex lenticule, it is also referred to as positive convergence lenticule.In another embodiment for increasing optical crosstalk, at least some lenticules in lenticule can be made as to the diverging of negative or light micro-Mirror.In one embodiment, this is realized by the way that lenticule is made as into concave.Because recessed lenticule causes light to dissipate,Therefore it can increase the optical crosstalk between adjacent pixel naturally.
Fig. 8 is three pixels of the imaging sensor 800 that embodiments in accordance with the present invention have recessed lenticule 814-818Cross-sectional view.Such as it can be seen from Fig. 8, each pixel includes the lenticule with the effective depth of focus D1 of identical.The depth of focus of negative lensTo be empty, because the lens dissipate light rather than assemble light.Herein, each pixel included in imaging sensor 800It is configured to be directed on the photodiode of neighborhood pixels to increase optical crosstalk by incident light.Similar to being discussed aboveThe positive lenticule stated, it can be desirable that the light being directed in adjacent pixel, which is not extended past adjacent pixels,.Otherwise, optical crosstalk canTo be excessive.Therefore, in one embodiment, by ensure effective depth of focus D1 of each focus (for example, focus 832) be more than or1/3rd equal to the height H of pixel limit the maximum of optical crosstalk.
In one embodiment, made using the technique using the gray scale mask similar to gray scale mask as described aboveMake recessed lenticule.Fig. 9 A illustrate embodiments in accordance with the present invention by the positive photoresist system for forming recessed lenticuleInto gray scale mask 902.If making recessed lenticule using positive photoresist (such as by gray scale mask 902), thatThe interior part of mask must be lighter than the outer portion of mask.Therefore, the interior part of gained lenticule will be relatively thin, and outer portionWill be relatively thick.Fig. 9 B illustrate embodiments in accordance with the present invention by the negative photoresist system for forming recessed lenticuleInto gray scale mask 904.
In the embodiment in fig. 8, bearing each of lenticule has the effective depth of focus D1 of identical.However, in other realitiesApply in example, only some pixels can be configured to increase optical crosstalk.That is, using negative lenticule, some pixels will can enterLight is penetrated to be directed on the photodiode of neighborhood pixels, and the neighborhood pixels are by the fenced pole of photoelectricity two to its own of incident lightPipe.As discussed above, it can be favourable colour element is increased crosstalk but transparent pixels is increased crosstalk.In other words,The light being incident in colour element can be directed into adjacent transparent pixel, but is incident in the light on transparent pixels and will substantially be protectedHold in the transparent pixels.In order to illustrate, Figure 10 is effective depth of focus that embodiments in accordance with the present invention have changeThe cross-sectional view of three pixels of recessed lenticule 1014-1018 imaging sensor 1000.Can in the following manner will be recessed micro-Mirror 1014-1018 is made as with different effective depths of focus：Make the changes in material used between lenticule and photodiodeAnd/or make material, size and the change in shape of lenticule.Such as demonstrated in Figure 10, focus 1032, which has, is shorter than focus 1030Effective depth of focus D2 effective depth of focus D1.In one embodiment, optical filter 508 and 512 is transparent filter, and optical filter 510For colored filter (for example, red, green or blueness).Therefore, colour element 2 is configured to receive light 1028 and by light 1028In at least some light be directed on the photodiode 420 and 424 of neighbouring transparent pixels 1 and 3.Transparent pixels 1 are configured toWith effective depth of focus D2 so that light 1026 is received and channeled to be incident in photodiode 420 at negative lenticule 1014Above it is not incident in adjacent photodiode.
Figure 11 is the imaging sensor 1100 that embodiments in accordance with the present invention have both convex lenticule and recessed lenticuleThe cross-sectional view of three pixels.In the illustrated embodiment, pixel 1 and 3 be respectively with transparent filter 508 and512 transparent pixels, and pixel 2 is the colour element with colored filter 510.The focus 1132 of pixel 2 has effective burntDeep D1 causes at least some light incided in the light on negative (that is, recessed) lenticule 1116 to be directed into neighbouring transparent pixels 1 and 2Photodiode 420 and 424.There is focus 1130 and 1134 effective depth of focus D2 to incide on just (that is, convex) lenticuleLight be only channeled to its corresponding photodiode without being directed into adjacent photodiode.In this embodiment, color imagesElement can increase optical crosstalk and transparent pixels do not increase optical crosstalk.
The above description to illustrated embodiment of the invention comprising content described in abstract of invention is not intended toFor exhaustive or limit the invention to disclosed precise forms.Although this hair is described herein for illustration purposesBright specific embodiment and example, but such as those skilled in the relevant art it will be recognized that can make each within the scope of the inventionPlant modification.
These modifications can be made to the present invention according to discussed in detail above.Term used in appended claims is notIt is interpreted as limiting the invention to the specific embodiment disclosed in specification.But, the scope of the present invention will be completely by instituteAttached claims determine that described claims will be understood according to the claim canons of construction created.