Patent Description:
Solid-state image sensors (e.g., charge-coupled device (CCD) image sensors, complementary metal-oxide semiconductor (CMOS) image sensors, and so on) have been widely used in various image-capturing apparatuses such as digital still-image cameras, digital video cameras, and the like. The light-sensing portion of a solid-state image sensor may be formed at each of a plurality of pixels, and signal electric charges may be generated according to the amount of light received by the light-sensing portion. In addition, the signal electric charges generated in the light-sensing portion may be transmitted and amplified, whereby an image signal is obtained.

Recently, the trend has been for the pixel size of image sensors typified by CMOS image sensors to be reduced for the purpose of increasing the number of pixels per unit area so as to provide high-resolution images. An image sensor which has been designed with the aim of providing a high resolution image is, amongst others, known from <CIT> and <CIT>. However, while pixel size continues to decrease, there are still various challenges in the design and manufacturing of image sensors. For example, cross-talk of electrical signals among pixels will be a serious problem with smaller pixel sizes, which may have an adverse influence on the performance of the image sensors. New manufacturing techniques are also needed to decrease the pixel size further without leading to serious cross-talk of electrical signals among pixels. Therefore, these and related issues need to be addressed by improving the design and manufacture of image sensors.

In accordance with some embodiments of the invention, an image sensor is provided. The features of this image sensor are defined in independent claim <NUM>.

Amongst others, the image sensor includes a substrate, an isolation structure on the substrate, a photoelectric conversion layer, a transparent electrode layer, an encapsulation layer, a color filter layer, and a micro-lens layer. The isolation structure is electrically non-conductive and defines a plurality of pixel regions on the substrate. The isolation structure prevents cross-talk of electrical signals among pixels. The photoelectric conversion layer is disposed on the pixel regions defined by the isolation structure. The transparent electrode layer is disposed over the isolation structure and the photoelectric conversion layer. The encapsulation layer is disposed over the transparent electrode layer. The micro-lens is disposed on the color filter layer.

The isolation structure comprises isolation walls.

The isolation walls are portions of the isolation structure between adjacent ones of the plurality of pixel regions.

The photoelectric conversion layer exposes at least a portion of sidewalls of the isolation walls.

In accordance with some other embodiments of the invention, a method of forming an image sensor is provided. The features of this method are defined in independent claim <NUM>.

Amongst others, the method includes providing a substrate. The method also includes forming an isolation structure on the substrate, wherein the isolation structure is electrically non-conductive and defines a plurality of pixel regions on the substrate. The method also includes forming a photoelectric conversion layer disposed on the pixel regions defined by the isolation structure, wherein the isolation structure prevents electrical signals in the photoelectric conversion layer among the pixel regions. The method also includes forming a transparent electrode layer over the isolation structure and the photoelectric conversion layer. The method also includes forming an encapsulation layer over the transparent electrode layer. The method also includes forming a color filter layer disposed over the encapsulation layer corresponding to the pixel regions. The method further includes forming a micro-lens layer disposed on the color filter layer.

Forming the isolation structure comprises forming the isolation structure having isolation walls.

The aspects of the present invention may be further embodied or equipped with one or more of the following optional features:.

An angle between a sidewall and a bottom surface of the isolation walls may be between <NUM>° and <NUM>°.

In one or more embodiments, the isolation walls may have a rectangular, triangular, trapezoidal, or an inversely trapezoidal shape in a cross-sectional view.

In one or more embodiments, a height of the isolation walls may be between <NUM> and <NUM>.

In one or more embodiments, an average width of each of the isolation walls may be between <NUM> and <NUM>.

In one or more embodiments, a sum of an average width of each of the isolation walls and an average width of the pixel regions may be less than <NUM>.

In one or more embodiments, the image sensor may further comprise an isolation cap disposed on a top surface of the isolation structure.

In one or more embodiments, a width of the isolation walls may be less than a width of the isolation cap.

In one or more embodiments, the isolation cap may comprise an inorganic material.

In one or more embodiments, the isolation structure may comprise an organic material.

In one or more embodiments, the photoelectric conversion layer may extend continuously across adjacent ones of the pixel regions.

In one or more embodiments, a refractive index of the isolation structure may be between <NUM> and <NUM>.

In one or more embodiments, the isolation structure may comprise at least one of silicon nitride, silicon oxide, aluminum oxide, photoresist, or combination thereof.

In one or more embodiments, the image sensor may further comprise a sensing device embedded in each of the pixel regions of the substrate.

In one or more embodiments, the sensing device may be electrically connected to the photoelectric conversion layer through a conductive portion.

In one or more embodiments, forming the isolation structure may comprise forming an organic material layer on the substrate; forming an inorganic material layer covering a top surface of the organic material layer; forming a patterned mask layer on the inorganic material layer; etching the inorganic material layer to form an isolation cap.

The inorganic material layer is etched by an anisotropic etching process until at least a portion of the organic material layer is exposed.

In one or more embodiments, etching the organic material layer until the substrate may be exposed to form the isolation structure with the isolation walls.

In one or more embodiments, the organic material layer may be etched by an isotropic etching process until a width of the isolation walls is less than a width of the isolation cap.

In one or more embodiments, etching the inorganic material layer may comprise using an etchant comprising CF<NUM>, C<NUM>F<NUM>, or a combination thereof.

In one or more embodiments, etching the organic material layer may comprise using an etchant comprising CO<NUM>, N<NUM>, or a combination thereof.

In one or more embodiments, the method may further comprise forming a sensing device embedded in each of the pixel regions of the substrate.

The sensing device may be electrically connected to the photoelectric conversion layer.

The invention may be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:.

The image sensor of the present disclosure is described in detail in the following description. In the following detailed description, for purposes of explanation, numerous specific details and embodiments are set forth in order to provide a thorough understanding of the present invention. The specific elements and configurations described in the following detailed description are set forth in order to clearly describe the present disclosure. It will be apparent, however, that the exemplary embodiments set forth herein are used merely for the purpose of illustration, and the concept of the present invention may be embodied in various forms without being limited to those exemplary embodiments, as long as they fall within the scope of the appended claims.

In addition, the drawings of different embodiments may use like and/or corresponding numerals to denote like and/or corresponding elements in order to clearly describe the present disclosure. However, the use of like and/or corresponding numerals in the drawings of different embodiments does not suggest any correlation between different embodiments. It should be understood that this description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. The drawings are not drawn to scale. In addition, structures and devices are shown schematically in order to simplify the drawing.

In addition, the expressions "a layer overlying another layer", "a layer is disposed above another layer", "a layer is disposed on another layer" and "a layer is disposed over another layer" may indicate that the layer is in direct contact with the other layer, or that the layer is not in direct contact with the other layer, there being one or more intermediate layers disposed between the layer and the other layer.

In addition, in this specification, relative expressions are used. For example, "lower", "bottom", "upper" or "top" are used to describe the position of one element relative to another. It should be appreciated that if a device is flipped upside down, an element that is "lower" will become an element that is "upper".

It should be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers, portions and/or sections, these elements, components, regions, layers, portions and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, portion or section from another element, component, region, layer or section. Thus, a first element, component, region, layer, portion or section discussed below could be termed a second element, component, region, layer, portion or section without departing from the teachings of the present disclosure.

The terms "about" and "substantially" typically mean +/- <NUM>% of the stated value, more typically mean +/- <NUM>% of the stated value, more typically +/- <NUM>% of the stated value, more typically +/- <NUM>% of the stated value, more typically +/- <NUM>% of the stated value and even more typically +/- <NUM>% of the stated value. The stated value of the present disclosure is an approximate value. When there is no specific description, the stated value includes the meaning of "about" or "substantially".

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It should be appreciated that, in each case, the term, which is defined in a commonly used dictionary, should be interpreted as having a meaning that conforms to the relative skills of the present disclosure and the background or the context of the present disclosure, and should not be interpreted in an idealized or overly formal manner unless so defined.

In accordance with some embodiments of the disclosure, an image sensor including an electrically non-conductive isolation structure among pixels is provided. In particular, a photovoltaic material for an image sensor may be patterned by the isolation structure to form a photoelectric conversion layer covering at least a portion of the isolation structure. By forming the above isolation structure, electron/hole cross-talk in the organic material among pixels will be prevented, which allows the image sensor with smaller pixel size to be formed without cross-talk adversely affecting the performance of the image sensor.

<FIG> illustrate cross-sectional views of various stages in the manufacturing of an image sensor, in accordance with some embodiments of the present disclosure.

Referring to <FIG>, a substrate <NUM> is provided. In some embodiments, the substrate <NUM> may be, for example, a wafer or a chip, but the present disclosure is not limited thereto. In some embodiments, the substrate <NUM> may be a semiconductor substrate, for example, silicon substrate. Furthermore, in some embodiments, the semiconductor substrate may also be an elemental semiconductor including germanium, a compound semiconductor including gallium nitride (GaN), silicon carbide (SiC), gallium arsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), indium arsenide (InAs), and/or indium antimonide (InSb), an alloy semiconductor including silicon germanium (SiGe) alloy, gallium arsenide phosphide (GaAsP) alloy, aluminum indium arsenide (AlInAs) alloy, aluminum gallium arsenide (AlGaAs) alloy, gallium indium arsenide (GaInAs) alloy, gallium indium phosphide (GaInP) alloy, and/or gallium indium arsenide phosphide (GaInAsP) alloy, or a combination thereof.

Then, referring to <FIG>, a plurality of sensing devices <NUM> are embedded in the substrate <NUM>, in accordance with some embodiments of the present disclosure. The plurality of sensing devices <NUM> may be disposed corresponding to each of the pixel regions which will be defined on the substrate <NUM> in subsequent manufacturing stages. In some embodiments, the sensing devices <NUM> are isolated from each other by isolation regions (not shown) in the substrate <NUM>, such as shallow trench isolation (STI) regions or deep trench isolation (DTI) regions. The isolation regions may be formed in the substrate <NUM> using etching process to form trenches and filling the trenches with an insulating or dielectric material.

The sensing devices <NUM> may include a variety of elements depending on the function of the resulting image sensor. For example, in some embodiments, the sensing devices <NUM> include charge storage portions, which serve to store signal charges generated in a subsequently formed photoelectric conversion layer in each pixel. In some embodiments, the sensing devices <NUM> include signal readout circuits, each of which serves to output a voltage signal corresponding to the signal charge stored in an associated charge storage portion.

Then, as shown in <FIG>, each of the sensing devices <NUM> may be electrically connected to a conductive portion <NUM>. The conductive portion <NUM> may further extend to a top surface of the substrate <NUM> to electrically connect to a subsequently formed photoelectric conversion layer (for example, a photoelectric conversion layer <NUM> as described below) over the substrate <NUM>.

Referring to <FIG>, an isolation structure <NUM> is formed on the substrate <NUM>, wherein the isolation structure <NUM> defines a plurality of pixel regions <NUM> on the substrate <NUM>. The isolation structure <NUM> is formed with isolation walls <NUM>, and the isolation walls <NUM> are portions of the isolation structure <NUM> between adjacent ones of the pixel regions <NUM>. In some embodiments, the angle between the sidewall and the bottom surface of the isolation walls <NUM> (referred to hereinafter as the sidewall angle of the isolation walls <NUM>) is between <NUM>° and <NUM>°. According to some embodiments of the present disclosure, the isolation walls <NUM> have a rectangular, trapezoidal, inversely trapezoidal, or a triangular shape in a cross-sectional view.

<FIG> illustrates a schematic diagram of an intermediate stage in the manufacturing of the image sensor corresponding to <FIG>, in accordance with some embodiments of the present disclosure. The isolation structure <NUM> may define an array of the pixel regions <NUM> on the substrate <NUM>, wherein the conductive portions <NUM> are exposed in each of the pixel regions <NUM>. In addition, as shown in <FIG>, the isolation walls <NUM> are portions of the isolation structure <NUM> between adjacent ones of the pixel regions, wherein each of the plurality of the pixel regions <NUM> is surrounded by the isolation walls <NUM>, and the pixel regions <NUM> are separated from each other by these isolation walls <NUM> of the isolation structure <NUM>. By forming the isolation structure <NUM>, a subsequently formed organic photoelectric layer (for example, a subsequently formed photoelectric conversion layer <NUM>) can be formed within the corresponding pixel regions <NUM>, and thus electron/hole cross-talk in the organic photoelectric layer among pixel regions <NUM> will be prevented.

The isolation structure <NUM> may include electrically non-conductive materials, such as silicon nitride, silicon oxide, aluminum oxide, photoresist, other suitable materials, or a combination thereof. The formation of the isolation structure <NUM> may include using suitable deposition techniques, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), spin coating, combinations thereof, or the like. After the materials for the isolation structure <NUM> is deposited, photolithography and etching processes are performed to form the isolation structure <NUM>. The cross-sectional profile of the isolation walls <NUM> may be adjusted by the etching conditions to obtain desired shapes.

After the formation of the isolation structure <NUM>, referring to <FIG>, a photoelectric conversion layer <NUM> is formed on the pixel regions <NUM> defined by the isolation structure <NUM>. The photoelectric conversion layer <NUM> in the reference embodiment in <FIG> extends continuously across adjacent ones of the pixel regions <NUM>. The photoelectric conversion layer <NUM> according to the present invention exposes at least a portion of the sidewalls of the isolation walls <NUM>. For example, an upper portion of the sidewalls of the isolation walls <NUM> may be exposed. In some embodiments, the thickness of the photoelectric conversion layer <NUM> on a top surface of the substrate <NUM> is about <NUM> to about <NUM>. By forming the above isolation structure, electron/hole cross-talk in the photoelectric conversion layer <NUM> among pixel regions <NUM> will be prevented, which allows the image sensor with smaller pixel size to be formed without cross-talk adversely affecting the performance of the image sensor.

In some embodiments, as shown in <FIG>, the photoelectric conversion layer <NUM> may be electrically connected to the conductive portion <NUM> exposed in each of the pixel regions <NUM>, and the photoelectric conversion layer <NUM> is thus electrically connected to the sensing devices <NUM>. In such configuration, the signal charges generated by the photoelectric conversion layer <NUM> are collected by the sensing devices <NUM> through the conductive portion <NUM>. Therefore, these signal charges are processed in elements (such as a charge storage portion, a signal readout circuit, combinations thereof, or the like) contained in the sensing devices <NUM>.

The photoelectric conversion layer <NUM> may include a photoelectric conversion material that absorbs light irradiation and generates signal charges corresponding to an amount of the absorbed light, such as an organic material, a perovskite material, a quantum dots material, other suitable materials, or a combination thereof. The photoelectric conversion layer <NUM> may be formed by a deposition process including spin coating, thermal evaporation, combinations thereof, or the like.

According to some embodiments of the present disclosure, as shown in <FIG>, a pixel width W1 of the isolation structure <NUM> is defined as the sum of the average width W2 of each of the isolation walls <NUM> and the average width W3 of the pixel regions <NUM>. The value of the pixel width W1 is not particularly limited in the present disclosure. In some embodiments, the pixel width W1 of the resulting image sensor is less than <NUM>.

The refractive index of the isolation structure <NUM> is not particularly limited in the present disclosure. In some embodiments of the present disclosure, the refractive index of the isolation structure <NUM> may be between <NUM> and <NUM>. For example, the refractive index of the isolation structure <NUM> may be between <NUM> and <NUM>. In some embodiments, a material with a higher refractive index (such as silicon nitride, aluminum oxide, or the like with a refractive index higher than <NUM>) may provide the isolation structure <NUM> with better water/oxygen resistance. In some other embodiments, a material with a lower refractive index (such as silicon oxide, photoresist, or the like with a refractive index lower than <NUM>), may provide the isolation structure <NUM> with higher optical efficiency. In the case where the isolation structure <NUM> is formed with a lower refractive index, light penetrating the isolation walls <NUM> is decreased due to the total internal reflection, thereby improving the light absorption and quantum efficiency of the image sensor.

Again, with reference to <FIG>, the height H and the average width W2 of each of the isolation walls <NUM> are not particularly limited in the present disclosure. For example, the height H of the isolation structure <NUM> may be between <NUM> and <NUM>, and the average width W2 of each of the isolation walls <NUM> may be between <NUM> and <NUM>. In reference embodiments where the photoelectric conversion layer <NUM> extends continuously across adjacent ones of the pixel regions <NUM>, the portion of the photoelectric conversion layer <NUM> on the surface of the isolation walls forms a passage for electron/hole drifting. Therefore, the electron/hole generated in the photoelectric conversion layer <NUM> may drift in the passage along the isolation walls <NUM>.

It should be noted that the passage length for electron/hole generated in the photoelectric conversion layer <NUM> is determined by controlling the sidewall angle, the average width W2, and the height H of the isolation walls <NUM>. In the present disclosure, the above passage length is defined as the shortest distance for electron/hole drifting across two adjacent ones of the pixel regions <NUM>. Since the diffusion length of electron/hole in the photoelectric conversion layer <NUM> varies in different kinds of materials of the photoelectric conversion layer <NUM>, the sidewall angle, the average width W2, and the height H of the isolation walls <NUM> may be chosen corresponding to the material of the photoelectric conversion layer <NUM>, such that the passage length for electron/hole drifting is longer than the diffusion length of electron/hole in the photoelectric conversion layer <NUM>. For example, the passage length for electron/hole drifting may be configured to be longer than <NUM>, while in some other embodiments, the passage length is configured to be longer than <NUM>. Once the passage length is configured to be longer than the diffusion length of electron/hole in the photoelectric conversion layer <NUM>, the electron/hole will be blocked by the isolation structure <NUM> and will not drift to other pixel regions <NUM> directly, and thereby electron/hole cross-talk in the photoelectric conversion layer <NUM> among pixel regions <NUM> will be prevented.

<FIG> illustrate cross-sectional views of structural variants of the isolation structure <NUM>, in accordance with some other embodiments of the present disclosure. As illustrated in <FIG>, the isolation walls <NUM> are formed as different shapes in a cross-sectional view, such as a triangular shape, a trapezoidal shape, or an inversely trapezoidal shape. In addition, depending on the sidewall angles of the isolation walls <NUM>, the photoelectric conversion layer <NUM> may or may not extend continuously across adjacent ones of the pixel regions <NUM>.

In a conventional image sensor as illustrated in <FIG>, the sidewall angles of the isolation walls <NUM> is formed to be a right angle, and the shape of the isolation walls <NUM> is rectangular in a cross-sectional view. In this case, the photoelectric conversion layer <NUM> extends continuously across adjacent ones of the pixel regions <NUM>, and the photoelectric conversion layer <NUM> completely covers the top surface and the sidewalls of each of the isolation walls <NUM>.

Referring to <FIG>, in some other conventional embodiments, the sidewall angles of the isolation walls <NUM> is formed to be smaller than <NUM>°, and the shape of the isolation walls <NUM> is triangular in a cross-sectional view. Also, the shape of the isolation walls <NUM> may be trapezoidal shapes, wherein there is a flat top surface on each of the isolation walls <NUM> (for example, the isolation walls <NUM> in <FIG>). In these cases where the sidewall angles are smaller than <NUM>°, the photoelectric conversion layer <NUM> may also extend continuously across adjacent ones of the pixel regions <NUM>. Therefore, in the embodiments where the sidewall angles of the isolation walls <NUM> is formed to be smaller than <NUM>°, the photoelectric conversion layer <NUM> may completely cover the top surface and the sidewalls of each of the isolation walls <NUM>.

Referring to the inventive embodiment in <FIG>, the sidewall angles of the isolation walls <NUM> is formed to be larger than <NUM>°, and the shape of the isolation walls <NUM> is inversely trapezoidal in a cross-sectional view, wherein the top surface of isolation walls <NUM> is larger than the bottom surface of the isolation walls <NUM>. Since the photoelectric conversion layer <NUM> does not extend continuously across adjacent ones of the pixel regions <NUM> and exposes, in accordance with the invention, at least a portion of the sidewalls of the isolation walls <NUM>, the portions of photoelectric conversion layer <NUM> between the adjacent ones of the pixel regions <NUM> fails to form a passage for electron/hole drifting, and thereby electron/hole cross-talk in the photoelectric conversion layer <NUM> among pixel regions <NUM> will be further prevented.

Next, referring to <FIG>, subsequent layers are formed over the isolation structure <NUM> and the photoelectric conversion layer <NUM> to complete the formation of the image sensor. First, a transparent electrode layer <NUM> may be formed over the photoelectric conversion layer <NUM>. The transparent electrode layer <NUM> may be used as a top electrode of the photoelectric conversion layer <NUM> in order to read out electrical signals of the photoelectric conversion layer <NUM>. With its high transmittance (for example, larger than <NUM>%), the transparent electrode layer <NUM> may allow the incident light to pass through and enter the photoelectric conversion layer <NUM>. As shown in <FIG>, the transparent electrode layer <NUM> may be formed to completely cover the underlying photoelectric conversion layer <NUM>, wherein a top surface of the transparent electrode layer <NUM> may be uneven and correspond to the underlying topography of the photoelectric conversion layer <NUM>. The transparent electrode layer <NUM> may include a transparent conductive material, such as ITO, IZO, ZnO, PEDOT-PSS, other suitable materials, or a combination thereof. The formation of the transparent electrode layer <NUM> may include using suitable deposition techniques, such as sputtering deposition, spin coating, thermal evaporation, combinations thereof, or the like. In some embodiments, the transparent electrode layer <NUM> is formed as a thickness from about <NUM> to about <NUM>. However, any suitable thickness may be utilized.

Once the transparent electrode layer <NUM> is formed, an encapsulation layer <NUM> may be formed over the transparent electrode layer <NUM>. In some embodiments, the encapsulation layer <NUM> may be formed as a flat top surface. For example, the encapsulation layer <NUM> may be planarized with a planarization process, such as a chemical mechanical polishing (CMP) process, to form a substantially flat top surface. Therefore, the conductive transparent electrode layer <NUM> may be encapsulated by the encapsulation layer <NUM>, and the encapsulation layer <NUM> may provide a flat top surface for subsequent formation of a color filter layer and a micro-lens layer which includes, for example, color filters CF and micro-lens ML, respectively. The encapsulation layer <NUM> may include silicon nitride, silicon oxide, aluminum oxide, other suitable materials, or a combination thereof. The formation of the encapsulation layer <NUM> may include using suitable deposition techniques, such as CVD, ALD, spin-on coating combinations thereof, or the like. In some embodiments, the encapsulation layer <NUM> is formed as a thickness larger than about <NUM>. However, any suitable thickness may be utilized.

Next, a color filter layer may be formed over the encapsulation layer <NUM>. The color filter layer may include a plurality of color filters CF disposed corresponding to the pixel regions <NUM>, wherein the plurality of color filters CF may include color filters for allowing different wavelengths of light to penetrate, such as a red color filter, a green color filter, and a blue color filter, other kinds of color filters, or a combination thereof. Although each of the color filters CF in <FIG> are illustrated as corresponding to each of the pixel regions <NUM>, it should be noted that the present disclosure is not limited to such configuration. In some embodiments, one color filter CF is disposed corresponding to a plurality of pixel regions <NUM>, while in some other embodiments, a plurality of color filters CF are disposed corresponding to the same pixel region <NUM>. In yet some other embodiments, some of the pixel regions <NUM> may not be covered by the color filter layer. In some embodiments, the color filters CF may be disposed in certain regular pattern. For example, the color filters CF may be disposed according to a Bayer Pattern. However, any suitable pattern and configuration of color filters CF may be utilized. In addition, the color filter layer may be formed in a deposition process at a lower temperature, such as a temperature lower than <NUM>, and thereby the materials of the photoelectric conversion layer <NUM> may undergo less decomposition and the performance of the resulting image sensor may be improved.

Following the formation of the color filter layer, a micro-lens layer may be formed on the color filter layer. The micro-lens layer may include a plurality of micro-lenses ML disposed corresponding to the color filters CF. Although each of the micro-lens ML in <FIG> are illustrated as corresponding to each of the color filters CF, it should be noted that the present disclosure is not limited to such configuration. In some embodiments, one micro-lenses ML is disposed corresponding to a plurality of color filters CF, while in some other embodiments, a plurality of micro-lens are disposed corresponding to the same color filter CF. In yet some other embodiments, some of the color filters CF may not be covered by the micro-lenses ML. The material of the micro-lenses ML may include glass, epoxy resin, silicone resin, polyurethane, any other applicable material, or a combination thereof, but the present disclosure is not limited thereto. As described above, the micro-lens layer may be formed at a lower temperature, such as a temperature lower than <NUM>, and thereby the materials of the photoelectric conversion layer <NUM> may undergo less decomposition and the performance of the resulting image sensor may be improved.

Each of the micro-lens ML may be a semi-convex lens or a convex lens, but the present disclosure is not limited thereto. In some other embodiments, each of the micro-lenses ML may be replaced with a condensing structure, such as a micro-pyramid structures (e.g., circular cone, quadrangular pyramid, and so on), or a micro-trapezoidal structures (e.g., flat top cone, truncated square pyramid, and so on). Alternatively, the condensing structure may be a gradient-index structure.

<FIG>-<NUM> illustrate cross-sectional views of intermediate stages in the manufacturing of an image sensor, in accordance with yet other embodiments of the present disclosure. In these embodiments, different from the embodiments of forming an image sensor in <FIG>, the image sensor is formed to include an isolation cap disposed on a top surface of the isolation structure, wherein a width of the isolation walls is smaller than a width of the isolation cap. In addition, the isolation cap comprises an inorganic material and the isolation structure comprises an organic material. By forming this isolation cap, the electron/hole cross-talk in the photoelectric conversion layer among the pixel regions will be further prevented. The detailed manufacturing process of forming the image sensor including the isolation cap are illustrated and described below with respect to <FIG>-<NUM>, wherein similar elements are indicated with similar reference numerals as recited in <FIG>.

Referring to <FIG>, an organic material layer <NUM> may be formed on the substrate <NUM>. The thickness of the organic material layer <NUM> is not particularly limited in the present disclosure. For example, the thickness of the organic material layer <NUM> may be between <NUM> and <NUM>. The organic material layer <NUM> may include an organic material feasible for subsequent patterning processes, such as a photoresist, although any suitable materials may be utilized. The formation of the organic material <NUM> may include using suitable deposition techniques, such as spin coating, bar coating, ink-jet coating, combinations thereof, or the like.

Referring to <FIG>, an inorganic material layer <NUM> may be formed covering a top surface of the organic material layer <NUM>. The thickness of the inorganic material layer <NUM> is not particularly limited in the present disclosure. For example, the thickness of the organic material layer <NUM> may be between <NUM> and <NUM>. The inorganic material layer <NUM> may include silicon nitride, silicon oxide, aluminum oxide, combinations thereof, or the like, although any suitable materials may be utilized. The formation of the inorganic material <NUM> may include using suitable deposition techniques, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), spin coating, combinations thereof, or the like.

Then, referring to <FIG>, a patterned mask layer <NUM> may be formed on the inorganic material layer <NUM> to serve as an etch mask for subsequent etching of the inorganic material layer <NUM>. The patterned mask layer <NUM> may, for example, include photoresist, epoxy, resin, other suitable materials, or a combination thereof. The formation of the patterned mask layer <NUM> may include using suitable deposition techniques, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), spin coating, combinations thereof, or the like. Then, the above deposition techniques are followed by suitable photolithography and etching processes to form a desired pattern corresponding to subsequently formed pixel regions.

After the formation of the patterned mask layer <NUM>, referring to <FIG>, a first etching process <NUM> is performed on the inorganic material layer <NUM> to form openings <NUM> and an isolation cap <NUM> surrounding the openings <NUM>, wherein the first etching process <NUM> is performed until at least a portion of the organic material layer <NUM> is exposed. The first etching process <NUM> may be an anisotropic etching process, such that a portion of the inorganic material layer <NUM> directly under the patterned mask layer <NUM> remains substantially unetched. In some embodiments, the inorganic material layer <NUM> is removed using, for example, a wet or dry etching process that utilizes etchants that are selective to the material of the inorganic material layer <NUM>, while the underlying organic material layer <NUM> remains unetched. For example, the first etching process <NUM> may utilize an etchant including CF<NUM>, C<NUM>F<NUM>, combinations thereof, or the like to remove the portion of the inorganic material layer <NUM> not covered by the patterned mask layer <NUM>. However, any suitable removal process for the inorganic material layer <NUM> may be utilized.

Additionally, the patterned mask layer <NUM> that covers the isolation cap <NUM> may be removed after the first etching process <NUM>. In an embodiment the patterned mask layer <NUM> may be removed using, for example, a wet or dry etching process that is selective to the material of the patterned mask layer <NUM>. However, the patterned mask layer <NUM> may also remain on the isolation cap <NUM> during subsequent etching processes.

After the organic material layer <NUM> is exposed by the first etching process <NUM>, a second etching process <NUM> may be performed on the organic material layer <NUM> to form the isolation structure <NUM> with the isolation walls <NUM>. The second etching process <NUM> is performed until the substrate <NUM> is exposed by the second etching process <NUM>. The second etching process <NUM> may be an isotropic etching process so that the width of the isolation walls <NUM> is less than the width of the isolation cap <NUM>. In addition, pixel regions <NUM> are defined by the resulting isolation structure <NUM>. In some embodiments, the organic material layer <NUM> is removed using, for example, a wet etching or isotropic dry etching process that utilizes etchants that are selective to the material of the organic material layer <NUM>, while the above isolation cap <NUM> and the underlying substrate <NUM> and exposed conductive portion <NUM> remain unetched. For example, the second etching process <NUM> may utilize an etchant including CO<NUM>, N<NUM>, combinations thereof, or the like to remove a portion of the inorganic material layer <NUM>. However, any suitable removal process for the organic material layer <NUM> may be utilized. Then, the remained patterned mask layer <NUM> (if any) that covers the isolation cap <NUM> may be removed after the second etching process <NUM>. In an embodiment the patterned mask layer <NUM> may be removed using, for example, a wet or dry etching process that is selective to the material of the patterned mask layer <NUM>.

After the formation of the isolation structure <NUM>, referring to <FIG>, a photoelectric conversion layer <NUM> is formed on the pixel regions <NUM> defined by the isolation structure <NUM>. As shown in <FIG>, the photoelectric conversion layer <NUM> may not extend continuously across adjacent ones of the pixel regions <NUM>, and the photoelectric conversion layer <NUM> exposes, in accordance with the invention, at least a portion of sidewalls of the isolation walls <NUM>. Since the photoelectric conversion layer <NUM> do not extend continuously across adjacent ones of the pixel regions <NUM>, the portions of photoelectric conversion layer <NUM> between the adjacent ones of the pixel regions <NUM> fails to form a passage for electron/hole drifting, and thereby electron/hole cross-talk in the photoelectric conversion layer <NUM> among pixel regions <NUM> will be further prevented.

In some embodiments, as shown in <FIG>, the photoelectric conversion layer <NUM> may be electrically connected to the conductive portion <NUM> exposed in each of the pixel regions <NUM>, and the photoelectric conversion layer <NUM> is thus electrically connected to the sensing devices <NUM>. In such configuration, the signal charges generated by the photoelectric conversion layer <NUM> are collected by the sensing devices <NUM> through the conductive portion <NUM>. Therefore, these signal charges are processed in elements (such as a charge storage portion, a signal readout circuit, combinations thereof, or the like) included in the sensing devices <NUM>.

The photoelectric conversion layer <NUM> may include similar materials and may be formed by similar deposition process as the photoelectric conversion layer <NUM> as described above. For example, the photoelectric conversion layer <NUM> may include a photoelectric conversion material that absorbs light irradiation and generates signal charges corresponding to an amount of the absorbed light, such as an organic material, a perovskite material, a quantum dots material, other suitable materials, or a combination thereof. The photoelectric conversion layer <NUM> may be formed by a deposition process including spin coating, thermal evaporation, combinations thereof, or the like.

After the formation of the photoelectric conversion layer <NUM>, a transparent electrode layer, encapsulation layer, color filter layer, and a micro-lens layer may be formed sequentially over the photoelectric conversion layer <NUM> according to the suitable materials and manufacturing processes described above, which is not repeated here for the sake of brevity.

In summary, according to some embodiments of the disclosure, an image sensor including an electrically non-conductive isolation structure among pixels is provided. In particular, a photovoltaic material for an image sensor may be patterned by the isolation structure to form a photoelectric conversion layer covering at least a portion of the isolation structure. By forming the above isolation structure, electron/hole cross-talk in the organic material among pixels will be prevented, which allows the image sensor with smaller pixel size to be formed without cross-talk adversely affecting the performance of the image sensor.

Claim 1:
An image sensor, comprising:
a substrate (<NUM>);
an isolation structure (<NUM>) disposed on the substrate (<NUM>), wherein the isolation structure (<NUM>) is electrically non-conductive and defines a plurality of pixel regions (<NUM>) on the substrate (<NUM>);
a photoelectric conversion layer (<NUM>) disposed on the pixel regions (<NUM>) defined by the isolation structure (<NUM>), wherein the isolation structure (<NUM>) prevents cross-talk of electrical signals in the photoelectric conversion layer (<NUM>) among the pixel regions (<NUM>);
a transparent electrode layer (<NUM>) disposed over the isolation structure (<NUM>) and the photoelectric conversion layer (<NUM>);
an encapsulation layer (<NUM>) disposed over the transparent electrode layer (<NUM>);
a color filter layer (CF) disposed over the encapsulation layer (<NUM>) corresponding to the pixel regions (<NUM>); and
a micro-lens layer (ML) disposed on the color filter layer (CF), wherein
the isolation structure (<NUM>) comprises isolation walls (<NUM>), wherein the isolation walls (<NUM>) are portions of the isolation structure (<NUM>) between adjacent ones of the plurality of pixel regions (<NUM>),
characterized in that
the photoelectric conversion layer (<NUM>) exposes at least a portion of sidewalls of the isolation walls (<NUM>).