TW200837934A - Image sensor and fabrication method thereof - Google Patents

Abstract

A fabrication method of an image sensor is disclosed. A semiconductor substrate is provided, wherein a plurality of pixels is defined on the semiconductor substrate. A plurality of pixel electrodes is formed on the pixels and then a barrier element is filled between adjacent pixel electrodes, wherein the barrier element contains a high k material. A photoconductive layer and a transparent conductive layer are successively formed on the high-k material layer and the pixel electrodes.

Description

200837934 IX. Description of the Invention: [Technical Field] The present invention provides an image sensor, and more particularly to an image sensor including a barrier element disposed between pixel electrodes. [Prior Art] With the development of technology, various image sensors have been widely used in digital electronic products such as % scanners or digital cameras, and the current wide range of image sensing includes complementary metal oxide semiconductors. (C〇mplementary metal 〇xide semiconductors ' CMOS) or charge coupled device (CCD). The image sensors are all germanium semiconductor devices, which can be used to capture photons, then convert the photons into electrons, and then convert them into measurable voltages to obtain digital data. At present, the industry has developed a photoconductor overlay active pixel

(photoconductor-on-active-pixel, POAP) image sensor, the structure of which is stacked on a CCD or CMOS device with a δ-densified amorphous silicon (〇Si:H) photosensitive element. It can get an image sensor that performs better than traditional CCD or CMOS image sensors. Since the photo-conductor-covered active pixel image sensor has a special stacked structure, it has the advantage of high-concentration effective area ratio (611 factor), which enables the entire pixel area to be used for sensing photons, and then with a-Si:H material. By effectively converting the energy characteristics, high quantum efficiency can be achieved. However, in known studies, the photo-conductor-covered active pixel image sensor still has problems such as cross-talk, 200837934 (cross-talk), image delay (imagelag), and leakage current signals. Among them, the problem that the carrier crosses the adjacent pixels in particular causes serious problems of insufficient resolution and uniformity, and also causes color interference between pixels, resulting in color distortion. Please refer to FIG. 1 and FIG. 2 . FIG. 1 is a side cross-sectional view of a conventional image sensor 10 with a light-emitting active pixel, and FIG. 2 is an analog potential diagram between pixel electrodes shown in FIG. 1 . . The conventional image sensor 10 includes a plurality of pixels 14a, 14b and a dielectric layer 16 disposed on a substrate 12, a plurality of pixel circuits (not shown) disposed within each of the pixels 14a, 14b, and a plurality of pixel electrodes. 18a, 18b are disposed on the pixel circuits and the dielectric layer 16, a photoconductive layer 20 is disposed on the pixel electrodes iga, 18b, and a transparent conductive layer 28 is disposed on the photoconductive layer 20, wherein the photoconductive layer 2 is bottom to top Including an n-type layer (n-iayer) 22, an intrinsic layer (such as 111^%61', ^^61〇24, and a p-type layer (p-typeiayer) 26, forming a so-called stacking layer "layer structure, It is used to receive light and convert the light into a corresponding amount of charge according to the intensity. However, in the case of illumination, the different pixel electrodes 18a, 18b of the image sensor 10 will have different voltages, resulting in between adjacent pixels 14a, 14b. An electric field having a voltage difference is generated. For example, if the pixel electrode 18b has a high potential Vh after illumination, and the pixel electrode 18a has a low potential V1, and the transparent conductive layer 28 is in a grounded state, between adjacent pixels 14a, 14b Leakage current occurs, by pixel electrode with high potential VH 18b flows to the pixel electrode 18a adjacent to the low potential VL, as shown in FIG. 2, the direction of movement of the leakage current is not indicated by the arrow. Therefore, the crosstalk problem occurs, which affects the correctness of the image 6 200837934 sensing, resulting in sensing. The result is distorted. Therefore, how to improve the image sensor structure of the photo-conductor-covered active pixel to avoid the adjacent pixel to cross the dry problem and provide the contact image_result is still an urgent problem to be solved in the industry. The main object of the present invention is to provide an optical pixel-coated active pixel image with a rotating element to solve the problem of cross-interference of the above-mentioned conventional imager. According to the patent application scope of the present invention, a sense of image is provided. The method of the detector first provides a substrate having a plurality of pixels defined on its surface. Then, a plurality of pixels are formed on the substrate, and the image is filled with a barrier element. Ff (high_k) material. Finally, a light riding and a transparent conductive layer are sequentially formed on the barrier element and the pixel electrode. According to the present invention, the patent is disclosed, and another one is disclosed. The image sensor includes a semiconductor substrate, a plurality of pixel wires on the semiconductor substrate, and a light guiding layer and a transparent conductive layer sequentially disposed on the pixel-pixel electrodes. The image sensing of the present invention further includes The rotating component is disposed between any adjacent pixel electrodes, and the shielding component comprises a high dielectric constant material. Since the present invention is disposed between each pixel electrode of the image sensor, it has a high dielectric 200837934

V electric constant material of the rotating component towel, so between the complement of the money pole _ into the car ▲ large energy barrier, (four) leakage-free He-pixel electrode flow to the adjacent pixel electric or transparent and conductive layer, so the financial effect Listening to the cross-theft question, improving the positive of the image sensor [Embodiment] Please refer to Figures 3 to 8, and Figures 3 to 8 are schematic views of the process of the image sensor of the present invention. First, as shown in FIG. 3, a semiconductor wafer is provided,

102' contains a basal brain, such as a silk bottom. A plurality of pixels 108' are defined on the surface of the semiconductor substrate L to form a matrix of pixels. Next, a plurality of electronic components are fabricated on the semiconductor substrate 104 to form a pixel circuit (7) disposed in the dielectric layer. A conductive layer m is then formed over the dielectric layer eagle, above the pixel and dielectric layers 106. The conductive layer 112 may comprise a metallic material, such as titanium nitride (TiN). Then, as shown in FIG. 4, a lithography and etching process is performed to form a photoresist layer (not shown) on the surface of the semiconductor substrate 104, and then a photomask having a pixel electrode pattern is used on the photoresist layer. A pixel electrode pattern is defined, and a portion of the conductive layer 112 is removed by etching, and the photoresist layer is removed to form a pixel electrode 114 ′ in each of the pixels 1 〇 8 electrically connected to the corresponding via the contact hole 116 The pixel circuit 11A has an electrode pitch G between adjacent pixel electrodes 114. Next, a barrier element 12A is formed between the adjacent pixel electrodes 114. For the formation method of the barrier element 200837934 120, please refer to FIG. 5 and FIG. 6. First, as shown in FIG. 5, a high-k material layer 118 is formed on the semiconductor substrate 104 to cover the dielectric. The layer 1〇6 and the pixel electrode 114 are over, and a portion of the high dielectric constant material layer 118 is also filled in the electrode pitch G of the adjacent pixel electrode 114. The high-k material layer 118 can be formed by chemical vapor deposition (CVD) or physical vapor deposition (physical v-print (10). The dielectric constant material layer 118 The dielectric constant may be about 25 to 3 Å, for example, may include a pentoxide group (tantalumpent oxide, also (8) material. Then, as shown in the first step, a chemical mechanical polishing process is performed, or a re-etching process is used to remove a portion of the pixel electrode. The surface of the high dielectric material layer ι 8 is such that the thickness of the high dielectric constant material layer II8 is approximately equal to the thickness of the pixel (4) 4, so as to be adjacent to the pixel electrode m of the adjacent pixel electrode m. The % is formed by the high dielectric constant material 118 filled in the electrode pitch G, so that the bottom surface of the barrier element 120 and the bottom surface of the pixel electrode 114 are located on the same plane, that is, on the upper surface of the dielectric layer 106. *Test Figure 7 'Figure 7 is the pixel electrode 114 and the barrier element 120 shown in Figure 6 & he #一-

Forming a 120 114 ι Next, please refer to FIG. 8a, sequentially forming a light guide 200837934 layer 122 and a transparent conductive layer 130 on the surface of the semiconductor substrate 104, wherein the light guide layer 122 sequentially includes an n-layer layer from bottom to top. 124. An intrinsic layer (i-layer) 126 and a p-type layer 128. The n-type layer 124 and the p-type layer 128 may respectively comprise a hydrogenated amorphous silicon carbide (a_SiC:H) material doped with an n-type dopant or a p-type dopant, and the intrinsic layer 126 may A hydrogenated amorphous silicon (a_Si:H) material is included. As can be seen from Fig. 8a, the n-type φ layer 124 formed on the pixel electrode 114 is in direct contact with the barrier element 120 and the pixel electrode Π4. However, in other embodiments, the photoconductive layer 122 may sequentially include a p-type layer, an intrinsic layer, and an n-type layer from bottom to top. Further, the transparent conductive layer 13A may include an Indium Tin Oxide (ITO) material. After the photoconductive layer 122 and the transparent conductive layer 130 are to be formed, the photoconductor-covered active pixel image sensor 1 of the present invention is completed. In other embodiments of the present invention, the 11-type layer 124/p-type layer 128 may be formed on the pixel electrode 114, and then dry-etched to remove a portion of the n-type layer 124 / p-type layer 128. A plurality of grooves 132 are formed between the adjacent pixel electrodes ι 4 (the surface of each pixel electrode 114 is still covered by the !! type layer 124 / p type layer 128), and the high dielectric is filled in the groove 132 The barrier element 12A is formed by a constant material, and the mobility of the barrier element 120 is approximately equal to the height of the n-type layer 124/p-type layer 128. The method for forming the barrier element 120 is to form a high dielectric constant material layer (not shown) on the semiconductor substrate 1〇4, and to cover the n-type. Above the layer 124/p-type layer 128, and filled into the recess 132, and then chemically polished or etched back. The high dielectric constant material partially higher than the surface of the /p-type layer (3) is removed. 200837934 Material layer. Finally, the intrinsic layer 126, the p-type layer 128/n-type layer 124, and the transparent conductive layer 13G are sequentially formed on the surface of the semiconductor substrate 104, thereby completing the photo-conductor-covered active pixel image sensor 100 as shown in FIG. . Please refer to Chapters 9 and 9, which are potential diagrams of the conventional image sensor 10 and the image sensor 100 of the present invention. When two adjacent pixel electrodes respectively have a low potential W and a horse potential vH, the Lu_region between the two-pixel electrode plate of the conventional image sensor 10 does not have a potential barrier height or only a small The height of the potential barrier is high. Therefore, the electrons generated in the intrinsic layer 24 are easily moved by the right-side high-potential pixel electrode 18b to the left-side low-potential V1 pixel electrode, causing a cross-interference problem (as shown in Fig. 2). In contrast, as can be seen from FIG. 9, the adjacent pixel electrodes m of the image sensor of the present invention have a high potential % and a low potential, respectively, but the electrode pitch 0 between the pixel electrodes m has a large The energy barrier is high and the effect is avoided. Figure 10 is a diagram of the pseudo potential between two adjacent pixels (10) touched by the image sensor of the present invention. As shown in FIG. 1G, although the adjacent pixel electrodes 114 have a lightning potential VH and a low potential V1 ', respectively, since the barrier element (10) provides a higher energy density at the adjacent pixel electrode electrode spacing G, the shaky current will be The right pixel electrode 114 having an ancient lightning position flows to the left pixel electrode having a low potential %. Therefore, the interference problem does not occur, resulting in an error in the color of the image. Compared with the prior art, the image sensor structure of the present invention is provided with a barrier element between adjacent pixels or like the 200837934 element electrode, so that the electrode spacing has a high potential barrier to avoid the situation of crossing interference' Can have Wei Shanying Lai Qing's image sensing silk. Since the barrier element of the present invention is formed of a high dielectric constant material, the electric field distribution between adjacent pixels can be blocked, and the crosstalk caused by the leakage current of the pixel electrode can be avoided. Therefore, according to the structure and the manufacturing method of the image sensor of the present invention, the ft単 process and the low cost can be utilized to create an image sensing benefit that avoids the problem of crossing interference, and effectively improve the correctness of the image sensing. The above description is only the preferred embodiment of the present invention, and all the modifications and modifications made by the scope of the present invention should be within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS =1 is a side cross-sectional view of a conventional optical-reflector image of an active pixel. FIG. 2 is an analog potential diagram between pixel electrodes shown in FIG. 3 to 8a are diagrams showing the process of the image sensor of the present invention. Figure 8b is a cross-sectional view showing another embodiment of the image sensor of the present invention. Figure 9 is a potential diagram of a conventional image sensor and an image sensor of the present invention. Figure 10 is an analog potential diagram of two adjacent pixels of the image sensor of the present invention. 12 200837934 [Main component symbol description] 10 image sensor 14a, 14b pixel 18a, 18b pixel electrode 22 n-type layer 26 germanium layer 100 image sensor 104 semiconductor substrate 108 pixel 112 conductive layer 116 contact hole 120 barrier element 124 n-type layer 128 germanium layer 132 recess 12 substrate 16 dielectric layer 20 photoconductive layer 24 intrinsic layer 28 transparent conductive layer 102 semiconductor wafer 106 dielectric layer 110 pixel circuit 114 pixel electrode 118 high dielectric constant material layer 122 light guide Layer 126 intrinsic layer 130 transparent conductive layer

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Claims (1)

200837934 X. Patent application scope: L-type production-image sensor method, the method comprises: providing a half-lead bottom, the surface of the wire has a plurality of pixels; forming a plurality of pixel electrodes on the semiconductor substrate Each of the pixels is filled with a barrier element between the adjacent pixel electrodes, the barrier element includes a back material; a high k material; and the first and second phase of the resistor The photoconductive layer and a transparent conductive layer are sequentially formed on the pixel electrode. 2. The method of claim 2 includes the method of claim 1, wherein the barrier element is formed. Forming a high dielectric constant material layer on the surface of the half-V body substrate; and removing the high dielectric constant material layer of the partial surface of the pixel. Pv_, (Physical vapor deposition), process or chemical vapor deposition (vapc)r depGsiti()n, cv〇) 4+ tear green, which removes part of the high dielectric constant, method contains - chemistry Mechanical research process or -_ engraving process. 5. The method of claim 1, wherein the height of the rotating element is 200837934 m, approximately the height of the pixel electrodes. 6. The method of claim 1, wherein the high dielectric constant material has a dielectric constant of about 25 to 3 Å. 7. The method of claim 1, wherein the high dielectric constant material comprises tantalum pentoxide (Ta2〇5). 8. The method of claim 2, wherein the photoconductive layer is sequentially stacked by a one-layer layer, an intrinsic layer (intrinsic layer), and a p-type layer. The method of item i, wherein the rotating element surrounds each of the pixel electrodes as a mesh. An image sensor comprising: a semiconductor substrate; a complex Z pixel filament on the substrate of the casting body, wherein the pixel comprises a pixel-photoconductive layer and a guiding layer of the barrier gamma It is called a butterfly _ = contains a high dielectric constant material. And the surface device is in which the high dielectric constant is 11. The image sensing according to the claim 1G of the patent claim 15 200837934 m material has a dielectric constant of about 25 to 30. 12. The image sensor of claim 1, wherein the high dielectric material comprises a money shirt. 13. The image sensor of claim 1 wherein the barrier element surrounds each of the pixel electrodes as a mesh. The image sensor of claim 1, wherein the bottom surface of the pixel element of the barrier element is on the same plane. The image sensor of claim 1, wherein the light guiding layer is formed by sequentially stacking a first conductive type doping layer, an intrinsic layer and a second conductive type doping layer. . The image sensor of claim 15, wherein the first conductive type doped layer and the second conductive type doped layer comprise hydrogenated amorphous silicon carbide (a) The image sensor of claim 15, wherein the intrinsic layer comprises a hydrogenated amorphous silicon (〇Si:H) material. The image sensor of claim 15, wherein the first conductive layer 1637937934 is covered with the barrier element and the surface of the pixel electrode, and the height of the barrier element The system is approximately equal to the height of the pixel electrode. " 19. The image sensing method of claim 15, wherein the first conductive type doped layer is covered by the spheroidal wire, and the height of the rotating element is approximately equal to the first conductive type The height of the doped layer. 20) A method for fabricating an image sensor, the method comprising: & ί, a semiconductor substrate having a plurality of pixels defined on a surface thereof; and a plurality of transposons on the bottom of the semi-conducting county Forming a first conductive type doped layer covering the pixel electrodes on the semiconductor substrate; removing a portion of the first conductive type doped layer to form a groove between any two adjacent poles; The electric barrier is filled with a barrier element. The barrier element comprises a high dielectric constant material to sequentially form an intrinsic layer and a first-transparent conductive layer on the semiconductor substrate. The image sensor of claim 20, wherein the first doped layer is an n-type layer, and the second conductive type doped layer is -p type The image sensor of claim 2, wherein the first conductive type is a p-type layer, and the second conductive type doped layer is an n-type Floor. The method of claim 2, wherein the method of forming the barrier element comprises: forming a high dielectric constant material layer on a surface of the semiconductor substrate; and: removing the portion at the first conductive The layer of high dielectric constant material on the surface of the doped layer. The method of claim 23, wherein the method of forming the high dielectric constant material layer comprises a physical vapor deposition process or a chemical vapor deposition process. The method of claim 23, wherein the method of removing a portion of the high dielectric constant material layer comprises a chemical mechanical polishing process or an etching process. The method of claim 20, wherein the height of the barrier element is approximately equal to the height of the first conductive germanium doped layer. 27. The method of claim 20, wherein the dielectric constant material has a dielectric constant of about 25 to 30. 28. The method of claim 2, wherein the high dielectric constant material 18 200837934 comprises a short pentoxide. 29. The method of claim 20, wherein the first conductive type doped layer, the intrinsic layer, and the second conductive type doped layer form a light guiding layer. 30. The method of claim 20, wherein the barrier element surrounds each of the pixel electrodes as a mesh. Reference XI, schema: 19