CN104157663A - CMOS image pixel array capable of improving incident light efficiency - Google Patents
CMOS image pixel array capable of improving incident light efficiency Download PDFInfo
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- CN104157663A CN104157663A CN201410427380.7A CN201410427380A CN104157663A CN 104157663 A CN104157663 A CN 104157663A CN 201410427380 A CN201410427380 A CN 201410427380A CN 104157663 A CN104157663 A CN 104157663A
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Abstract
The invention discloses a CMOS image pixel array capable of improving incident light efficiency. Optical fiber is arranged in an optical channel of a pixel array body, a micro lens layer in the prior art is omitted, and an original micro lens forming the micro lens layer and a color filtering lens are reasonably arranged in the optical fiber, so that the incident light can reach a light sensing region nearly without reflection along the optical fiber, and the utilization efficiency of the incident light is greatly improved; meanwhile, the crosstalk phenomenon occurring between adjacent pixels is effectively inhibited through the shielding effect of the optical fiber, and the overall height of the pixel array body is obviously reduced.
Description
Technical field
The present invention relates to a kind of cmos image sensor, more specifically, relate to a kind of pel array of the cmos image sensor that improves incident light efficiency.
Background technology
Imageing sensor is the device that light signal is converted to the signal of telecommunication, is widely used in civilian and business category at Digital Television, face-to-face communication etc.According to the difference of photoelectric conversion mode, imageing sensor can be divided into ccd image sensor (Charge-coupled Device, CCD) and cmos image sensor (CMOS IMAGE SENSOR, CIS) two classes conventionally.
For CCD, on the one hand, at professional scientific research and industrial circle, the CCD with high s/n ratio becomes first-selection; On the other hand, in high-end photography and vedio recording field, can provide the CCD of high image quality also quite to be favored.And for CIS, be also widely applied at IP Camera and mobile phone photograph module.
CCD is compared with CIS, and higher, the integrated difficulty of the former power consumption is larger, and the latter is low in energy consumption, easy of integration and resolution is higher.Although CCD may be better than CIS aspect picture quality, still, along with improving constantly and the significantly lifting of CMOS manufacturing technology level of CIS technology, the picture quality of a part of CIS is close to the CCD of same specification.CIS is obtaining substantial progress in performance, and relies on the advantages such as its low cost, high efficiency, transmission speed be fast to be widely used in all kinds of emerging fields such as panel computer, smart mobile phone.Be accompanied by the promotion of the field of consumer electronics such as camera cell phone to CIS, the market prospects of following cmos image sensor will be more wide.The design of small size, high-performance CIS becomes one of important topic of this area research.
One of imageing sensor intuitively performance index is exactly the reproduction ability to image, and the pel array of imageing sensor is exactly the critical function module that is directly connected to this index.Pel array can be divided into front illuminated formula (Front Side Illuminated, FSI) pel array and back-illuminated type (Back Side Illuminated, BSI) pel array.In the structure of FSI pel array, comprise successively filter layer, metal level and sensitization diode layer along incident light direction.Filter layer generally comprises the two or one of lenticule (Micro-lens) and color filter array (Color Filter Array, CFA), for incident light being focused on and obtained coloured image; Metal level comprises the circuit structure being formed by multi-layer metal wiring, for the electric signal transmission of opto-electronic conversion is processed to peripheral circuit; In sensitization diode layer, include light sensitive diode (Photo Diode, PD), for the incident light receiving is carried out to opto-electronic conversion.If BSI pel array comprises filter layer, sensitization diode layer and metal level successively along incident light direction, the metal level position in its structure and sensitization diode layer exchange, and are positioned at the distal-most end layer that deviates from incident light.Between filter layer and sensitization diode layer, be provided with optical channel, incident light, through filter layer, arrives the PD in sensitization diode layer along optical channel, realizes opto-electronic conversion, analog-to-digital conversion, output digital image.Adopting CMOS active pixel sensor (Active Pixel Sensor, APS) in the pel array as the CIS of its photosensitive unit, an APS (i.e. a pixel cell) comprises a PD and an activated amplifier (Active Amplifier).
Refer to Fig. 1, Fig. 1 is the planar structure schematic diagram of the FSI pel array of a kind of cmos image sensor of prior art.As shown in Figure 1, its color filter array adopts Bayer pattern to arrange, in figure, exemplify wherein a kind of arrangement mode of Bayer pattern, if represent red filter with letter r, G represents green filter, B represents blue filter, and in the color filter array of this kind of spread pattern of Bayer pattern, the color filter is according to the first row RGRG ..., the second row GBGB ... by that analogy and by 4 the color filters be unit repeat form arrange.A filter 4-1～4-4 below correspondence of every kind of color arranges a PD1-1～1-4, and center-aligned.In the structure of illustrated FSI pel array, because the metal level between the color filter and PD will be placed metal line (circuit structure), so need to stay at regular intervals between adjacent PD.Do BSI pel array if changed, because metal level is positioned at PD below, between adjacent PD, spacing can relative decrease (figure of this place omits, please refer to Fig. 1).
Refer to Fig. 2, Fig. 2 is the structural profile schematic diagram of the FSI pel array of a kind of cmos image sensor of prior art.As shown in Figure 2, from section, pel array is divided into three layers of upper, middle and lowers substantially, upper strata is filter layer 6, be used for placing lenticule 5 and the color filter 4, each lenticule 5 is convex lens, the optical channel 3 of its corresponding metal level 7 in below, optical channel 2 and the PD1 of PD layer 9.Middle level is metal level 7, and matrix is silica material, is placed with multi-layer metal wiring 8 (being illustrated as 4 layers), and form circuit structure with electric connection mode, be used for transmitting the signal of telecommunication, the space between adjacent metal wiring forms optical channel 3, and incident light from then on optical channel 3 passes arrival PD1.Lower floor is PD layer 9, and host material is silicon, is used for placing PD1, and the optical channel 2 of PD layer 9 is communicated with and aims at the optical channel 3 of metal level 7.Lenticule 5 is used for collected light, and incident light (as figure hollow core arrow indication) is entered metal level optical channel 3, PD layer optical channel 2 and arrived the PD1 of lower floor successively by filter layer 6, and PD1 meets photon generation photoelectric effect, then spreads out of the signal of telecommunication.In the structure of FSI pel array, when incident light is when the optical channel, because metal level wherein has very multi-layer metal wiring, part light will be reflected (as filled arrows indication in figure), light intensity is incurred loss, cause image quality to be affected.
Refer to Fig. 3, Fig. 3 is the structural profile schematic diagram of the BSI pel array of a kind of cmos image sensor of prior art.As shown in Figure 3, different from FSI pel array, in the structure of BSI pel array, be followed successively by filter layer 14, PD layer 15, metal level 16 from top to bottom, metal level 16 is positioned at the below of PD layer 15.Filter layer 14 is used for placing lenticule 13 and the color filter 12, and each lenticule 13 is convex lens, optical channel 11 and the PD10 of its corresponding PD layer 15 in below.Incident light (as figure hollow core arrow indication) will only need directly to arrive PD10 by the optical channel 11 of PD layer 15, and needn't pass through metal level 16, has shortened optical channel.Therefore, can there is not the reflex of incident light and metal level 16.Meanwhile, because optical channel does not need the space because the metal line 17 of metal level 16 is transferred to other use, the distance between neighbor can suitably be shortened.The problem of BSI picture element array structure is, compare FSI pel array, although can improve by the optical channel shortening the lightsensitivity of its pel array, but after the distance between neighbor too shortens, crosstalking between pixel (crosstalk) will become obviously (as filled arrows indication in figure), cause the phenomenon of fading of coloured image.
In 2 kinds of pel arrays of the above-mentioned prior art exemplifying, or there is the problem that incident light efficiency is lower, or have the cross-interference issue between pixel.Therefore, design a kind of efficiency, the while that can further improve incident light and can avoid again the cmos image picture element array structure of crosstalking between pixel, become when previous important improvement problem.
Summary of the invention
The object of the invention is to overcome the above-mentioned defect that prior art exists, a kind of cmos image pel array of novel improved incident light efficiency is provided, by optical fiber being set in the optical channel of pel array, and cancel the microlens layer of prior art, and the lenticule of former formation microlens layer and the color filter are arranged in optical fiber, make incident light almost arrive to areflexia photosensitive region along optical fiber, greatly improve the utilization ratio of incident light, also effectively suppressed the crosstalk phenomenon between neighbor simultaneously, and the whole height of pel array is obviously reduced.
For achieving the above object, the present invention has adopted following two kinds of technical schemes:
One of technical scheme:
Improve a cmos image pel array for incident light efficiency, described pel array is taking the version of FSI pel array as basis, but cancelled microlens layer, only includes the metal level that is positioned at upper strata and the sensitization diode layer that is positioned at lower floor.Described metal level and sensitization diode layer are provided with the optical channel of aiming at and interconnecting, and described sensitization diode layer is provided with light sensitive diode, and described optical channel is communicated with described light sensitive diode.In described optical channel, be provided with optical fiber, described optical channel is led to and is positioned at the upper end open of described metal level, the described light sensitive diode of the closely sealed connection of the other end in one end of described optical fiber.Cancelling after microlens layer, the lenticule of former formation microlens layer and the color filter are being replaced with single independently form, be arranged in described optical fiber by upper-lower position.Thereby incident light can directly enter by the upper end open of described optical fiber from the top of described metal level, through described lenticular in described optical fiber converge, the reduction of described the color filter, along described fiber optic conduction to described light sensitive diode.
In technique scheme, on the basis of traditional F SI structure, the structure of pel array is done to simplify and optimized.The path that incident light leads to light sensitive diode is retrained by optical fiber, and between metal level, just can there is hardly any reflex, make incident light almost arrive to areflexia photosensitive region, the FSI structure of its utilance under compared to existing technology improves greatly, simultaneously, also can itself crosstalk on low basis in FSI structure, further utilize the screen effect of optical fiber to suppress crosstalking between CIS pixel.Therefore, under same illumination condition, the CIS pel array of discussing in the technical program can obtain more bright, clear, noise color digital image still less.And, owing to there is no filter layer, make the whole height of pel array be able to obvious reduction, thereby shortened light path, the utilization ratio of incident light is further improved; Related system designer can utilize this characteristic to realize the thin design of system product.So, adopt the cmos image pel array of the technical program, in can further improve incident light efficiency, can realize again succinct thin design, and provide more, the possibility of high-quality more for the realization of relevant product systems scheme.
Preferably, the upper end open of described optical fiber and described optical channel are positioned at concordant and closely sealed connection of the upper end open of described metal level, prevent that incident light from entering and conducting to light sensitive diode from the gap between optical fiber and optical channel; Closely sealed connection between described lenticule and described the color filter, avoid light intensity to incur loss and disturb; The closely sealed connection of inwall of described lenticule and described the color filter and described optical fiber, prevent that a small amount of incident light is without lenticule and the color filter in the situation that, conduct to light sensitive diode from the gap between lenticule and the color filter and optical fiber.
Preferably, described lenticule is graded index (Gradient – index, GRIN) lenticule, utilizes the refractive index parameter of gradual change in these lens, the directional light of incident is bent, and then be tending towards converging a bit; The lenticular lower surface of described graded index is connected with hot amalgamation mode with the upper surface of described the color filter, and described graded index lenticule and the side of described the color filter and the inwall of described optical fiber are connected with hot amalgamation mode.For lenticule, fusion characteristics that what the color filter and optical fiber had be heated, utilize integration technology, adopt graded index lenticule and the color filter of adapting with fusion technique, graded index lenticule and the color filter fusion are formed to closely sealed entirety in optical fiber inwall, the making feasibility of lenticule of the present invention and the color filter and the stability that structure arranges are ensured, thereby substitute the filter layer of pel array under prior art, greatly reduce the height of pel array, in further having improved incident light efficiency, realize succinct thin design.
Preferably, the lenticular upper surface of described graded index is plane, and concordant with the upper end open of described optical fiber, has ensured the controllability of pel array height.The upper end open three of the optical channel of the upper end open of optical fiber, the lenticular upper surface of graded index and metal level is mutually concordant and closely sealed fixing, has ensured the controllability of pel array height and the stability of structure.
Two of technical scheme:
A kind of cmos image pel array that improves incident light efficiency, described pel array is taking the version of BSI pel array as basis, but similarly cancel microlens layer with one of technical scheme, only included and be positioned at the sensitization diode layer on upper strata and the metal level of lower floor.Described sensitization diode layer is provided with optical channel and light sensitive diode, and described optical channel is communicated with the light sensitive diode that below is provided with.In described optical channel, be provided with optical fiber, the upper end open of described optical channel is led in one end of described optical fiber, the described light sensitive diode of the described optical channel of the closely sealed connection of other end below.Cancelling after microlens layer, the lenticule of former formation microlens layer and the color filter are being replaced with single independently form, be arranged in described optical fiber by upper-lower position.Thereby incident light can directly enter by the upper end open of described optical fiber from the top of described sensitization diode layer, through described lenticular in described optical fiber converge, the reduction of described the color filter, along described fiber optic conduction to described light sensitive diode.
Technique scheme two in, the path that incident light leads to light sensitive diode is similarly retrained by optical fiber, because lenticule is arranged in optical fiber, and one end of optical fiber and light sensitive diode close communication, make actual being formed in optical fiber of light path of incident light, make incident light can almost nondestructively arrive at photosensitive region.Therefore,, in the time adopting the version of BSI pel array, even because metal level is positioned at sensitization diode layer below, the spacing relative decrease of adjacent light sensitive diode, also can utilize the screen effect of optical fiber, effectively suppresses crosstalking between CIS pixel.Similarly, owing to there is no filter layer, make the whole height of pel array be able to obvious reduction, thereby shortened light path, the utilization ratio of incident light is further improved, can realize again succinct thin design.Sensor designer can also be by adding extra metal level to expand the function of this pel array.
Preferably, the upper end open of described optical fiber and closely sealed be connected concordant with the upper end open of described optical channel, prevent that incident light from entering and conducting to light sensitive diode from the gap between optical fiber and optical channel; Closely sealed connection between described lenticule and described the color filter, avoid light intensity to incur loss and disturb; The closely sealed connection of inwall of described lenticule and described the color filter and described optical fiber, prevent that a small amount of incident light is without lenticule and the color filter in the situation that, conduct to light sensitive diode from the gap between lenticule and the color filter and optical fiber.
Preferably, described lenticule is graded index (Gradient – index, GRIN) lenticule, utilizes the refractive index parameter of gradual change in these lens, the directional light of incident is bent, and then be tending towards converging a bit; The lenticular lower surface of described graded index is connected with hot amalgamation mode with the upper surface of described the color filter, and described graded index lenticule and the side of described the color filter and the inwall of described optical fiber are connected with hot amalgamation mode.For lenticule, fusion characteristics that what the color filter and optical fiber had be heated, utilize integration technology, adopt graded index lenticule and the color filter of adapting with fusion technique, graded index lenticule and the color filter fusion are formed to closely sealed entirety in optical fiber inwall, the making feasibility of lenticule of the present invention and the color filter and the stability that structure arranges are ensured, thereby substitute the filter layer of pel array under prior art, greatly reduce the height of pel array, in further having improved incident light efficiency, realize succinct thin design.
Preferably, the lenticular upper surface of described graded index is plane, and concordant with the upper end open of described optical fiber, has ensured the controllability of pel array height.The upper end open three of the upper end open of optical fiber, the lenticular upper surface of graded index and optical channel is mutually concordant and closely sealed fixing, has ensured the controllability of pel array height and the stability of structure.
Can find out from technique scheme, the present invention by arranging optical fiber in the optical channel of pel array, make actual being formed in optical fiber of light path of incident light, utilize optical fiber incident light almost nondestructively can be conducted to the light sensitive diode of photosensitive region, thereby greatly improved the utilization ratio of incident light; Can also utilize the screen effect of optical fiber, effectively suppress the crosstalk phenomenon between CIS pixel.Simultaneously, cancel and be present in microlens layer of the prior art, and graded index lenticule and the color filter are merged in optical fiber, make the whole height of pel array be able to obvious reduction, thereby shorten light path, not only can make the utilization ratio of incident light be further improved, can also provide related system designer to utilize this design feature to realize the thin design of system product.Therefore, the design of image pixel array of the present invention, is a kind of innovation that makes full use of prior art basis, and its cost is controlled, in having improved picture quality, for the physical specification aspect of system provides the possibility of flexible selection.
Brief description of the drawings
Fig. 1 is the planar structure schematic diagram of the FSI pel array of a kind of cmos image sensor of prior art;
Fig. 2 is the structural profile schematic diagram of the FSI pel array of a kind of cmos image sensor of prior art;
Fig. 3 is the structural profile schematic diagram of the BSI pel array of a kind of cmos image sensor of prior art;
Fig. 4 is a kind of structural profile schematic diagram of a kind of cmos image pel array that improves incident light efficiency of the present invention;
Fig. 5 is the local structure for amplifying generalized section of the one of the optical fiber in Fig. 4 structure;
Fig. 6 is the another kind of structural profile schematic diagram of a kind of cmos image pel array that improves incident light efficiency of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.
It should be noted that, in following embodiment, in the time that embodiments of the present invention are described in detail in detail, in order clearly to represent structure of the present invention so that explanation, spy does not draw according to general ratio to the structure in accompanying drawing, and carried out local amplification, distortion and simplified and process, therefore, should avoid being understood as limitation of the invention using this.
The present invention can adopt following two kinds of embodiments to realize.
In following the first embodiment of the present invention, refer to Fig. 4, Fig. 4 is a kind of structural profile schematic diagram of a kind of cmos image pel array that improves incident light efficiency of the present invention.Cmos image pel array of the present invention is made as basis taking the version of FSI pel array, but with existing FSI picture element array structure difference be to have cancelled microlens layer.As shown in Figure 4, cmos image pel array of the present invention only includes PD (light sensitive diode) layer 26 that is positioned at the metal level 24 on upper strata and is positioned at lower floor.The main component of metal level 24 is silica, can be also other applicable compositions in this pel array device.In metal level 24, can there is multi-layer metal wiring 25, for example as shown in the figure 4 layers but be not limited to the metal line of 4 layers.Metal line 25 forms circuit structure with electric connection mode, is used for transmitting the signal of telecommunication.Space between adjacent metal wiring forms the optical channel 20 of metal level 24.The host material of PD layer 26 is silicon, can be also other applicable compositions in this pel array device.In PD layer 26, be provided with PD18 and optical channel 19, optical channel 19 lower ends are communicated with PD18, and upper end is communicated with and aims at the optical channel 20 of metal level 24.The optical channel 20 of metal level 24 has opening 27 at the upper surface of metal level 24, as the entrance of incident light.
Please continue to refer to Fig. 4.The present invention, in order to improve the utilization ratio of incident light, has packed 1 optical fiber 21 in each optical channel 20,19.Can, after this pel array element manufacturing completes, optical fiber 21 be inserted into optical channel 20,19 from the opening 27 of the optical channel 20 of metal level 24 upper surfaces.The upper surface open 27 of optical channel 20 at metal level 24 led in the upper end of optical fiber 21, so that optical fiber 21 receives incident light, and make between the lower end of optical fiber 21 and PD18 mode to fit tightly or ensure mutually closely sealedly and is communicated with binder and other existing applicable patterns, the light of avoiding optical fiber 21 to receive is lost from optical fiber 21 lower ends.In order to realize the inherent function of FSI pel array, cancelling after microlens layer, originally lenticule and the color filter of forming microlens layer are replaced with single independently form, and lenticule 23 and the color filter 22 are processed into the size matching with optical fiber 21 bores, put into optical fiber 21 by upper-lower position from the upper end open portion of optical fiber 21.Then, then by optical fiber 21 be inserted in optical channel 20,19.Optical fiber 21 is inserted into the method in optical channel 20,19, can adopt for example Free Space Coupling (free space coupling) technology, use micro-control position table (its motor stepping is minimum) optical fiber is put into optical channel and align with the position of optical channel.Like this, incident light can directly enter by the upper end open of optical fiber 21 from the top of metal level 24, through the reduction of the converging of the lenticule 23 of optical fiber 21 interior placements, the color filter 22, conducts to PD18 (as figure hollow core arrow indication) along optical fiber 21.The CIS pel array of discussing in the present invention also uses the color filter array of Bayer pattern, the corresponding PD18 of a filter 22 of every kind of color, and the center of optical fiber 21, lenticule 23, the color filter 22, PD18 is aimed at and is arranged.
In above-mentioned the first embodiment of the present invention, on the basis of traditional F SI structure, the structure of pel array is done to simplify and optimized.The path that incident light leads to light sensitive diode is retrained by optical fiber, and between metal level, just can there is hardly any reflex, make incident light almost arrive to areflexia photosensitive region, the FSI structure of its utilance under compared to existing technology improves greatly, simultaneously, also can itself crosstalk on low basis in FSI structure, further utilize the screen effect of optical fiber to suppress crosstalking between CIS pixel.Therefore,, under same illumination condition, in this embodiment, disclosed CIS pel array can obtain more bright, clear, noise color digital image still less.And, owing to there is no filter layer, make the whole height of pel array be able to obvious reduction, thereby shortened light path, the utilization ratio of incident light is further improved; Related system designer can utilize this characteristic to realize the thin design of system product.So, adopt the cmos image pel array of this embodiment, in can further improve incident light efficiency, can realize again succinct thin design, and provide more, the possibility of high-quality more for the realization of relevant product systems scheme.
Please continue to refer to Fig. 4.In a preferred embodiment of the present invention, the upper end open of optical fiber 21 is arranged to concordant with the upper end open 27 of the optical channel 20 of metal level 24, and and upper end open 27 between adopt for example interference fit or use binder and other existing applicable patterns to carry out closely sealed connection, prevent that incident light from entering and conducting to PD18 from the gap between optical fiber 21 and optical channel 20.Be placed on and between the lower surface of the lenticule 23 in optical fiber 21 and the upper surface of the color filter 22, can adopt that the mode fitting tightly is closely sealed to be connected.For example lenticule 23 and the color filter 22 are processed into separately to suitable size, ensure that to stack mode mutual closely sealed formation connects; Or according to traditional manufacture craft, together with lenticule 23 is processed in advance with the color filter 22, and be processed into the size matching with optical fiber bore, to put into optical fiber 21.After lenticule 23 is connected with the color filter 22 is closely sealed, can avoid light intensity incur loss and disturb between the lower surface of lenticule 23 and the upper surface of the color filter 22.Between the inwall of the side of lenticule 23 and the color filter 22 and optical fiber 21, can adopt too the mode that fits tightly, for example, be pressed in optical fiber 21 or ensure that with binder and other existing applicable patterns mutual closely sealed formation is connected in the mode of interference fit, prevent that incident light from passing and conducting to PD18 from the gap between lenticule 23 and the color filter 22 and the inwall of optical fiber 21 without lenticule 23 and the color filter 22 in the situation that.
Taking the above embodiments as basis, in present invention further optimization embodiment, as shown in Figure 4, lenticule 23 has adopted graded index (Gradient – index, GRIN) lenticule, can utilize the refractive index parameter of gradual change in GRIN lenticule, the directional light of incident be bent, and then be tending towards converging a bit.Certainly, lenticule 23 also can adopt completely traditional convex lens form (only profile different from GRIN lenticule, pretend figure and slightly process, Fig. 4 draws as an example of GRIN lenticule example) realize function of the present invention.Only, adopt GRIN lenticule to there is larger manufacture craft advantage realizing time of the present invention, specifically will put and be described hereinafter.Identical with the structure of traditional FSI pel array, between lenticule 23 of the present invention and PD18, to leave necessary physical distance, to guarantee to realize incident light focusing on through lenticule 23, after the color filter 22 reduction, arrive at PD18 sensitization according to the requirement of device performance.
Refer to Fig. 5, Fig. 5 is the local structure for amplifying generalized section of the one of the optical fiber in Fig. 4 structure.As shown in Figure 5, in the above-mentioned further preferred embodiment of the present invention, lenticule has adopted GRIN lenticule 23, and it has the upper and lower surface of plane.Can utilize the refractive index parameter of gradual change in GRIN lenticule, the directional light of incident is bent, and then be tending towards converging a bit (as arrow indication in figure).Between GRIN lenticule 23, the color filter 22, optical fiber 21 threes, be closely connected with each other.The fusion characteristics of being heated that can utilize GRIN lenticule and optical fiber to have, and employing has the color filter of the fusion characteristics of being heated equally, utilize existing fusion (Fuse) technology and electric arc fusion device, the lower surface of GRIN lenticule 23 is mutually closely sealed with hot amalgamation mode with the upper surface of the color filter 22, and GRIN lenticule 23 and the side of the color filter 22 and the inwall of optical fiber 21 are mutually closely sealed with hot amalgamation mode.Also can use if desired index matching glue to merge performance in order to promote.After fusion, the signal integrity rate that optical fiber receives can reach more than 90%, considers that the lenticular optically focused effect of GRIN can improve lightsensitivity greatly, and the loss of signal effect of fusion is negligible.In the situation that installing space possesses, can also use connector (Connectors) that GRIN lenticule 23, the color filter 22 and optical fiber 21 threes are connected.The existing numerous known technology of method of attachment between concrete optical fiber and other photoelectric devices, therefore no longer launch explanation.Like this, just GRIN lenticule 23 and the color filter 22 are merged in optical fiber 21 inwalls and form closely sealed entirety, the making feasibility of lenticule of the present invention and the color filter and the stability that structure arranges are ensured, thereby substitute the filter layer of pel array under prior art, greatly reduce the height of pel array, in further having improved incident light efficiency, realize succinct thin design.
Please continue to refer to Fig. 4 and Fig. 5.As the preferred embodiments of the present invention, the upper surface of GRIN lenticule 23 is arranged to concordant with the upper end open of optical fiber 21 and is merged fixing.In an embodiment who has introduced before, because the upper end open 27 of the upper end open of optical fiber 21 and the optical channel 20 of metal level 24 is also mutually concordant, and and upper end open 27 between adopt for example interference fit or use binder and other existing applicable patterns to carry out closely sealed connection, thereby upper end open 27 threes of the optical channel 20 of the upper end open of optical fiber 21, the upper surface of lenticule 23 and metal level 24 are simultaneously mutually concordant and mutually closely sealed fixing.Like this, ensureing, under physical distance necessary between lenticule 23 and PD18, can to ensure the controllability of pel array height, realize the optimal design of pel array height.
In following the second embodiment of the present invention, refer to Fig. 6, Fig. 6 is the another kind of structural profile schematic diagram of a kind of cmos image pel array that improves incident light efficiency of the present invention.In this embodiment, pel array of the present invention is made as basis taking the version of BSI pel array, but has similarly cancelled microlens layer with aforementioned the first embodiment.As shown in Figure 6, cmos image pel array of the present invention only includes the PD layer 34 that is positioned at upper strata and the metal level 35 that is positioned at lower floor.The host material of PD layer 34 is silicon, can be also other applicable compositions in this pel array device.PD layer 34 is provided with optical channel 29 and PD28, and optical channel 29 lower ends are communicated with PD28, and upper end has opening 33 in the upper surface of PD layer 34, as the entrance of incident light.The main component of metal level 35 is silica, can be also other applicable compositions in this pel array device.In metal level 35, can there is multi-layer metal wiring 36, for example as shown in the figure 4 layers but be not limited to the metal line 36 of 4 layers.Metal line 36 forms circuit structure with electric connection mode, is used for transmitting the signal of telecommunication.
Please continue to refer to Fig. 6.The present invention, in order further to improve the utilization ratio of incident light, has packed 1 optical fiber 30 in each optical channel 29.Can, after this pel array element manufacturing completes, optical fiber 30 be inserted into optical channel 29 from the upper end open 33 of optical channel 29.The upper end open 33 of optical channel 29 is led in the upper end of optical fiber 30, so that optical fiber 30 receives incident light, and make between the lower end of optical fiber 30 and PD28 mode to fit tightly or ensure mutually closely sealedly and is communicated with binder and other existing applicable patterns, the light of avoiding optical fiber to receive is lost from optical fiber lower end.In order to realize the inherent function of BSI pel array, cancelling after microlens layer, originally lenticule and the color filter of forming microlens layer are replaced with single independently form, and lenticule 32 and the color filter 31 are processed into the size matching with optical fiber 30 bores, put into optical fiber 30 by upper-lower position from the upper end open portion of optical fiber 30.Then, then by optical fiber 30 be inserted in optical channel 29.Optical fiber 30 is inserted into the method in optical channel 29, can adopt for example Free Space Coupling (free space coupling) technology, use micro-control position table (its motor stepping is minimum) optical fiber is put into optical channel and align with the position of optical channel.Like this, incident light can directly enter by the upper end open of optical fiber 30 from the top of PD layer 34, through the reduction of the converging of the lenticule 32 of optical fiber 30 interior placements, the color filter 31, conducts to PD28 (as figure hollow core arrow indication) along optical fiber 30.The CIS pel array of discussing in the present invention also uses the color filter array of Bayer pattern, the corresponding PD28 of a filter 31 of every kind of color, and the center of optical fiber 30, lenticule 32, the color filter 31, PD28 is aimed at and is arranged.
In above-mentioned the second embodiment, the path that incident light leads to PD is similarly retrained by optical fiber.Because lenticule is arranged in optical fiber, and one end of optical fiber and PD close communication, make actual being formed in optical fiber of light path of incident light, make incident light can almost nondestructively arrive at photosensitive region.Therefore,, in the time adopting the version of BSI pel array, even because metal level is positioned at PD layer below, the spacing relative decrease of adjacent PD, also can utilize the screen effect of optical fiber, effectively suppresses crosstalking between CIS pixel.Similarly, owing to there is no filter layer, make the whole height of pel array be able to obvious reduction, thereby shortened light path, the utilization ratio of incident light is further improved, can realize again succinct thin design.Sensor designer can also be by adding extra metal level to expand the function of this pel array.
Please continue to refer to Fig. 6.In a preferred embodiment of the present invention, the upper end open of optical fiber 30 is arranged to concordant with the upper end open 33 of optical channel, and and upper end open 33 between adopt for example interference fit (in Fig. 6, between optical channel 29 and optical fiber 30, to be easy to identification for making, spy is depicted as and leaves gap form, will be understood that the correct form of implementation of interference fit) or use binder and other existing applicable patterns to carry out closely sealed connection, prevent that incident light from entering and conducting to PD28 from the gap between optical fiber 30 and optical channel 29.Be placed on and between the lower surface of the lenticule 32 in optical fiber 30 and the upper surface of the color filter 31, can adopt that the mode fitting tightly is closely sealed to be connected.For example lenticule 32 and the color filter 31 are processed into separately to suitable size, ensure that to stack mode mutual closely sealed formation connects; Or according to traditional manufacture craft, together with lenticule 32 is processed in advance with the color filter 31, and be processed into the size matching with optical fiber 30 bores, to put into optical fiber 30.After lenticule 32 is connected with the color filter 31 is closely sealed, can avoid light intensity incur loss and disturb between the lower surface of lenticule 32 and the upper surface of the color filter 31.Between the inwall of the side of lenticule 32 and the color filter 31 and optical fiber 30, can adopt too the mode that fits tightly, for example, be pressed in optical fiber 30 or ensure that with binder and other existing applicable patterns mutual closely sealed formation is connected in the mode of interference fit, prevent that incident light from passing and conducting to PD28 from the gap between lenticule 32 and the color filter 31 and the inwall of optical fiber 30 without lenticule 32 and the color filter 31 in the situation that.
Taking the above embodiments as basis, in present invention further optimization embodiment, as shown in Figure 6, lenticule has adopted graded index (Gradient – index, GRIN) lenticule, can utilize the refractive index parameter of gradual change in GRIN lenticule, the directional light of incident is bent, and then be tending towards converging a bit and (refer in the first embodiment the lenticular introduction of GRIN).Certainly, lenticule also can adopt completely traditional convex lens form (only profile different from GRIN lenticule, pretend figure and slightly process, Fig. 6 draws as an example of GRIN lenticule example) realize function of the present invention.Only, adopt GRIN lenticule to there is larger manufacture craft advantage realizing time of the present invention, specifically will put and be described hereinafter.Identical with the structure of traditional BSI pel array, between lenticule 32 of the present invention and PD28, to leave necessary physical distance, to guarantee to realize incident light focusing on through lenticule 32, after the color filter 31 reduction, arrive at PD28 sensitization according to the requirement of device performance.
In the second embodiment of the present invention, same can hot amalgamation mode mutually closely sealed between fiber section and GRIN lenticule and the color filter, its structure is identical with the structure of the fiber section in the first embodiment, therefore, the structure of the fiber section in two kinds of embodiments of the present invention can be consulted Fig. 5 and be understood, this example is no longer separately shown explanation as partial enlarged drawing, can directly illustrate according to Fig. 6.In the above-mentioned further preferred embodiment of the second embodiment of the present invention, lenticule has adopted GRIN lenticule 32, and it has the upper and lower surface of plane.Between GRIN lenticule 32, the color filter 31, optical fiber 30 threes, be closely connected with each other.The fusion characteristics of being heated that can utilize GRIN lenticule and optical fiber to have, and employing has the color filter of the fusion characteristics of being heated equally, utilize existing integration technology and electric arc fusion device, the lower surface of GRIN lenticule 32 is mutually closely sealed with hot amalgamation mode with the upper surface of the color filter 31, and GRIN lenticule 32 and the side of the color filter 31 and the inwall of optical fiber 30 are mutually closely sealed with hot amalgamation mode.Also can use if desired index matching glue to merge performance in order to promote.After fusion, the signal integrity rate that optical fiber receives can reach more than 90%, considers that the lenticular optically focused effect of GRIN can improve lightsensitivity greatly, and the loss of signal effect of fusion is negligible.In the situation that installing space possesses, can also use connector (Connectors) that GRIN lenticule 23, the color filter 22 and optical fiber 21 threes are connected.The existing numerous known technology of method of attachment between concrete optical fiber and other photoelectric devices, therefore no longer launch explanation.Like this, just GRIN lenticule 32 and the color filter 31 are merged in optical fiber 30 inwalls and form closely sealed entirety, the making feasibility of lenticule of the present invention and the color filter and the stability that structure arranges are ensured, thereby substitute the filter layer of pel array under prior art, greatly reduce the height of pel array, in further having improved incident light efficiency, realize succinct thin design.
Please continue to refer to Fig. 6.As the preferred embodiments of the present invention, the upper surface of GRIN lenticule 32 is arranged to concordant with the upper end open of optical fiber 30.In an embodiment who has introduced before, due to the upper end open of optical fiber 30 and the upper end open 33 of optical channel 29 concordant, and and upper end open 33 between adopt for example interference fit or use binder and other existing applicable patterns to carry out closely sealed connection, thereby upper end open 33 threes of the upper end open of optical fiber 30, the upper surface of lenticule 32 and optical channel 29 are simultaneously mutually concordant and closely sealed fixing.Like this, ensureing, under physical distance necessary between lenticule 32 and PD28, can to ensure the controllability of pel array height, realize the optimal design of pel array height.
The cmos image pel array that adopts above-mentioned two kinds of embodiments of the present invention to make, by optical fiber being set in the optical channel of pel array, make actual being formed in optical fiber of light path of incident light, utilize optical fiber incident light almost nondestructively can be conducted to the light sensitive diode of photosensitive region, thereby greatly improved the utilization ratio of incident light; Can also utilize the screen effect of optical fiber, effectively suppress the crosstalk phenomenon between CIS pixel.Simultaneously, cancel and be present in microlens layer of the prior art, and graded index lenticule and the color filter are merged in optical fiber, make the whole height of pel array be able to obvious reduction, thereby shorten light path, not only can make the utilization ratio of incident light be further improved, can also provide related system designer to utilize this design feature to realize the thin design of system product.Therefore, the design of image pixel array of the present invention, is a kind of innovation that makes full use of prior art basis, and its cost is controlled, in having improved picture quality, for the physical specification aspect of system provides the possibility of flexible selection.
Above-described is only the preferred embodiments of the present invention; described embodiment is not in order to limit scope of patent protection of the present invention; therefore the equivalent structure that every utilization specification of the present invention and accompanying drawing content are done changes, and in like manner all should be included in protection scope of the present invention.
Claims (8)
1. one kind can be improved the cmos image pel array of incident light efficiency, comprise upper metal layers and lower floor's sensitization diode layer, described metal level and sensitization diode layer are provided with the optical channel of intercommunication, described sensitization diode layer is provided with light sensitive diode, described optical channel is communicated with described light sensitive diode, it is characterized in that, in described optical channel, be provided with optical fiber, described optical channel is led to and is positioned at the upper end open of described metal level in one end of described optical fiber, the described light sensitive diode of the closely sealed connection of the other end, is provided with lenticule, the color filter by upper-lower position in described optical fiber; Wherein, incident light can directly enter by the upper end open of described optical fiber from the top of described metal level, through described lenticular in described optical fiber converge, the reduction of described the color filter, along described fiber optic conduction to described light sensitive diode.
2. cmos image pel array as claimed in claim 1, it is characterized in that, the upper end open of described optical fiber and described optical channel are positioned at concordant and closely sealed connection of the upper end open of described metal level, closely sealed connection between described lenticule and described the color filter, the closely sealed connection of inwall of described lenticule and described the color filter and described optical fiber.
3. cmos image pel array as claimed in claim 2, it is characterized in that, described lenticule is graded index lenticule, the lenticular lower surface of described graded index merges and is connected with the upper surface heat of described the color filter, and described graded index lenticule and the side of described the color filter and the fusion of the inner surface heat of described optical fiber are connected.
4. cmos image pel array as claimed in claim 3, is characterized in that, the lenticular upper surface of described graded index is plane, and concordant with the upper end open of described optical fiber.
5. one kind can be improved the cmos image pel array of incident light efficiency, comprise upper strata sensitization diode layer and lower metal layer, described sensitization diode layer is provided with optical channel and light sensitive diode, described optical channel is communicated with described light sensitive diode, it is characterized in that, in described optical channel, be provided with optical fiber, the upper end open of described optical channel is led in one end of described optical fiber, the described light sensitive diode of the closely sealed connection of the other end, is provided with lenticule, the color filter by upper-lower position in described optical fiber; Wherein, incident light can directly enter by the upper end open of described optical fiber from the top of described sensitization diode layer, through described lenticular in described optical fiber converge, the reduction of described the color filter, along described fiber optic conduction to described light sensitive diode.
6. cmos image pel array as claimed in claim 5, it is characterized in that, the upper end open of described optical fiber and closely sealed be connected concordant with the upper end open of described optical channel, closely sealed connection between described lenticule and described the color filter, the closely sealed connection of inwall of described lenticule and described the color filter and described optical fiber.
7. cmos image pel array as claimed in claim 6, it is characterized in that, described lenticule is graded index lenticule, the lenticular lower surface of described graded index merges and is connected with the upper surface heat of described the color filter, and described graded index lenticule and the side of described the color filter and the fusion of the inner surface heat of described optical fiber are connected.
8. cmos image pel array as claimed in claim 7, is characterized in that, the lenticular upper surface of described graded index is plane, and concordant with the upper end open of described optical fiber.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100364102C (en) * | 2003-12-08 | 2008-01-23 | 台湾积体电路制造股份有限公司 | Image sensor with light guides and manufacturing method thereof |
| US20080116537A1 (en) * | 2006-11-17 | 2008-05-22 | Adkisson James W | Cmos imager array with recessed dielectric |
| CN102232199A (en) * | 2008-09-04 | 2011-11-02 | 立那工业股份有限公司 | Optical waveguides in image sensors |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100364102C (en) * | 2003-12-08 | 2008-01-23 | 台湾积体电路制造股份有限公司 | Image sensor with light guides and manufacturing method thereof |
| US20080116537A1 (en) * | 2006-11-17 | 2008-05-22 | Adkisson James W | Cmos imager array with recessed dielectric |
| CN102232199A (en) * | 2008-09-04 | 2011-11-02 | 立那工业股份有限公司 | Optical waveguides in image sensors |
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Application publication date: 20141119 |