Method for forming image sensor device

Abstract

A method for forming an image sensing device is provided, comprising forming a first groove in a semiconductor substrate. The semiconductor substrate has a front side and a back side, and the first groove extends from the front side into the semiconductor substrate. The method comprises forming a first isolation structure in the first groove. The method comprises forming a light sensing region in the semiconductor substrate. The first isolation structure surrounds the light sensing region. The method comprises forming a second groove in the semiconductor substrate. The second groove extends from the back side into the semiconductor substrate and exposes the first isolation structure. The method comprises forming a second isolation structure in the second groove. The second isolation structure comprises a light blocking structure to absorb or reflect incident light.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to an image sensing device, and more particularly to a light blocking structure of an isolation structure thereof. Background Art

[0002] The semiconductor integrated circuit industry has experienced rapid growth. Technological advances in integrated circuit materials and design have made each generation of integrated circuits smaller and more complex than the previous generation. New generations of integrated circuits have greater functional density (such as the number of interconnect components in a fixed chip area) and smaller size (such as the smallest component formed by the process). These advances increase the complexity of integrated circuit processing. To achieve the above advances, the integrated circuit process needs to develop similarly.

[0003] In addition to reducing the size of the geometry to achieve the above advantages, it is straightforward to improve integrated circuit devices. One such integrated circuit device is an image sensor device. An image sensor device includes an array of pixels (or grids) that detect light and record the intensity (brightness) of the detected light. The pixel array can accumulate charge in response to the light intensity. The higher the light intensity, the more charge is accumulated in the pixel array. The accumulated charge is then used to provide image information (which can be provided by other circuits) for use in appropriate applications (such as digital cameras).

[0004] However, the size of structures continues to shrink, making them increasingly difficult to process. As a result, it is a major challenge to create reliable and increasingly smaller image sensor devices. Summary of the invention

[0005] An embodiment of the present disclosure provides a method for forming an image sensing device, comprising: forming a first groove in a substrate, wherein the substrate has a front side and a back side, and the first groove extends from the front side into the substrate; forming a first isolation structure in the first groove; forming a light sensing region in the substrate, wherein the first isolation structure surrounds the light sensing region; forming a second groove in the substrate, wherein the second groove extends from the back side into the substrate and exposes the first isolation structure; and forming a second isolation structure in the second groove, wherein the second isolation structure includes a light blocking structure to absorb or reflect incident light. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figures 1A to 1E 2 is a cross-sectional view of various stages of a process for forming an image sensing device in some embodiments.

[0007] Figure 2A In some embodiments, Figure 1B A top view of a semiconductor substrate, an etching stop layer, and an insulating layer.

[0008] Figure 2B In some embodiments, Figure 1D A top view of the light blocking structure and the insulating layer.

[0009] Figure 3 is a cross-sectional view of an image sensing device in some embodiments.

[0010] Figure 4 is a cross-sectional view of an image sensing device in some embodiments.

[0011] Figure 5 is a cross-sectional view of an image sensing device in some embodiments.

[0012] Figure 6 is a cross-sectional view of an image sensing device in some embodiments.

[0013] Figure 7 is a cross-sectional view of an image sensing device in some embodiments.

[0014] Figure 8 is a cross-sectional view of an image sensing device in some embodiments.

[0015] Fig. 9 is a cross-sectional view of an image sensing device in some embodiments.

[0016] Fig.10 is a cross-sectional view of an image sensing device in some embodiments.

[0017] Description of reference numerals:

[0018] D1, D2 Depth

[0019] D3 Distance

[0020] E1 First end

[0021] E2 Second end

[0022] I-I' section line

[0023] L, L1, L2 Incident light

[0024] S, 120 isolation structure

[0025] S1, 120a end surface

[0026] T1, T2, T3, T4, T5 thickness

[0027] V1, V2 direction

[0028] W1, W2 Width

[0029] W1m, W2m minimum width

[0030] W1x, W2x maximum width

[0031] 100, 300, 400, 500, 600, 700, 800, 900, 1000 Image sensor

[0032] 110 Semiconductor substrate

[0033] 112 Front

[0034] 114 Back

[0035] 116, 119 groove

[0036] 116a, 119a lower surface

[0037] 116b, 119b Inner wall

[0038] 118 Light Sensing Area

[0039] 120b Sidewall

[0040] 122 Etch stop layer

[0041] 122a, 124a, 150a, 160a, 164a upper surface

[0042] 124, 150 Insulation layer

[0043] 130 Internal connection structure

[0044] 132 Interlayer dielectric layer

[0045] 134 Multi-layer interconnect structure

[0046] 134a Wire

[0047] 134b Through hole

[0048] 140 Carrier substrate

[0049] 160 Light blocking structure

[0050] 162 Light Reflection Structure

[0051] 164 Light Absorption Structure

[0052] 170 Anti-reflective coating

[0053] 180 Buffer layer

[0054] 190 Reflection Grid

[0055] 192 Reflection Unit

[0056] 210 Dielectric layer

[0057] 212R, 212G, 212B recessed

[0058] 220R, 220G, 220B color filters

[0059] 230 Lens DETAILED DESCRIPTION

[0060] The following disclosure provides many different embodiments or examples to implement different structures of the present disclosure. The following specific components and arrangement embodiments are used to simplify the present disclosure but are not intended to limit the present disclosure. For example, the description of forming a first component on a second component includes direct contact between the two, or there are other additional components between the two instead of direct contact. In addition, multiple examples of the present disclosure may use repeated numbers and / or symbols to simplify and clarify the description, but these repetitions do not mean that the same corresponding relationship exists between the elements with the same number in the multiple embodiments.

[0061] In addition, spatially relative terms such as "below", "beneath", "below", "above", "above", or the like may be used to simplify the description of the relative relationship of one element to another element in a diagram. Spatially relative terms may be extended to elements used in other orientations and are not limited to the orientation shown. Elements may also be rotated 90° or other angles, so directional terms are only used to describe the orientation shown in the diagram. It should be understood that additional steps may be performed before, during, and after the method, and other embodiments of the method may replace or omit some of the steps described below.

[0062] Figures 1A to 1E 1 is a cross-sectional view of various stages of the process of the image sensor device 100 in some embodiments. Figure 1A As shown, a semiconductor substrate 110 is provided. The semiconductor substrate 110 has a front surface 112 and a back surface 114 opposite to the front surface 112. In some embodiments, the semiconductor substrate 110 has a thickness T1. In some embodiments, the thickness T1 is equal to the distance between the front surface 112 and the back surface 114.

[0063] The semiconductor substrate 110 may be a silicon substrate doped with a p-type dopant such as boron, and thus the semiconductor substrate 110 is a p-type substrate. On the other hand, the semiconductor substrate 110 may be another suitable semiconductor material. For example, the semiconductor substrate 110 may be a silicon substrate doped with an n-type dopant such as phosphorus or arsenic, and thus the semiconductor substrate 110 is an n-type substrate. The semiconductor substrate 110 may include other semiconductor elements such as germanium.

[0064] In some embodiments, Figure 1A As shown, a portion of the semiconductor substrate 110 is removed to form a trench 116 in the semiconductor substrate 110 . In some embodiments, the trench 116 extends from the front surface 112 into the semiconductor substrate 110 . In some embodiments, the trench 116 surrounds a portion of the semiconductor substrate 110 .

[0065] In some embodiments, the groove 116 has a lower surface 116a and an inner sidewall 116b. In some embodiments, the inner sidewall 116b is connected to the lower surface 116a (or adjacent to the lower surface 116a). In some embodiments, the groove 116 has a depth D1. In some embodiments, the ratio of the depth D1 to the thickness T1 is between about 0.02 and about 0.5.

[0066] In some embodiments, Figure 1A As shown, an etch stop layer 122 is formed on the semiconductor substrate 110 to cover the lower surface 116a, the inner sidewall 116b, and the front surface 112. In some embodiments, the etch stop layer 122 covering the lower surface 116a has a thickness T2. In some embodiments, the etch stop layer 122 covering the inner sidewall 116b has a thickness T3. In some embodiments, the thickness T2 is greater than the thickness T3.

[0067] In some embodiments, the etch stop layer 122 is used to control a subsequent etching process performed on the semiconductor substrate 110. In some embodiments, the etch stop layer 122 and the semiconductor substrate 110 may be made of different materials. In some embodiments, the etch stop layer 122 is made of an insulating material.

[0068] In some embodiments, the etching stop layer 122 is composed of silicon nitride, silicon oxynitride, silicon oxide, silicon carbide, a combination thereof, or the like. The etching stop layer 122 may be formed by a deposition process such as a chemical vapor deposition process, a physical vapor deposition process, an atomic layer deposition process, or another suitable deposition process.

[0069] In some embodiments, Figure 1A As shown, the insulating layer 124 is formed on the etch stop layer 122. In some embodiments, the insulating layer 124 fills the trench 116. In some embodiments, the etch stop layer 122, the insulating layer 124, and the semiconductor substrate 110 are made of different materials.

[0070] The insulating layer 124 is made of silicon oxide, silicon nitride, fluorine-doped silicate glass, a low-k dielectric material, another suitable insulating material, or a combination thereof. The insulating layer 124 may be formed by a deposition process such as chemical vapor deposition, physical vapor deposition, or another suitable deposition process.

[0071] In some embodiments, Figure 1B As shown, the insulating layer 124 and the etching stop layer 122 outside the trench 116 are removed. In some embodiments, the insulating layer 124 and the etching stop layer 122 remaining in the trench 116 after the removal process together form the isolation structure 120.

[0072] In some embodiments, the isolation structure 120 is used to define a light sensing region to be subsequently formed in the semiconductor substrate 110 and to electrically isolate adjacent devices such as transistors from each other. In some embodiments, the isolation structure 120 is adjacent to (or close to) the front surface 112 .

[0073] In some embodiments, the removal process includes a planarization process, such as a chemical mechanical polishing process. In some embodiments, the upper surface 122a of the etch stop layer 122 and the upper surface 124a of the insulating layer 124 are thus substantially coplanar (or substantially aligned with each other). The term "substantially coplanar" herein may include slight errors from coplanar geometry, which may come from the process.

[0074] Figure 2A In some embodiments, Figure 1B FIG. 1 is a top view of a semiconductor substrate 110, an etch stop layer 122, and an insulating layer 124. Figure 1B and Figure 2A As shown, the light sensing region 118 is formed in a portion of the semiconductor substrate 110 surrounded by the trench 116 (or the isolation structure 120). In some embodiments, the light sensing region 118 is also referred to as a radiation sensing region.

[0075] In some embodiments, the photosensitive region is formed by one or more ion implantation processes or diffusion processes. The doping polarity of the photosensitive region 118 is opposite to the doping polarity of the semiconductor substrate 110. The photosensitive region 118 is close to the front surface 112 of the semiconductor substrate 110 (i.e., adjacent to the front surface 112 or close to the front surface 112).

[0076] The light sensing region 118 is operable to sense incident light (or incident radiation) entering the light sensing region 118. The incident light may be visible light. Alternatively, the incident light may be infrared light, ultraviolet light, X-rays, microwaves, other suitable types of light, or combinations thereof.

[0077] In some embodiments, the image sensing unit is formed on the light sensing region 118. To simplify the description, the present disclosure does not illustrate the complete structure of the image sensing unit. In some embodiments, the image sensing unit includes a pinning layer, a photodiode gate, a reset transistor, a source follower transistor, and a conversion transistor.

[0078] In some embodiments, the conversion transistor is electrically connected to the light sensing region 118 to collect electrons generated when incident light (incident radiation) reaches the light sensing region 118 and convert the electrons into a voltage signal.

[0079] In some embodiments, Figure 1BAs shown, an interconnect structure 130 is formed on the front surface 112. The interconnect structure 130 includes a plurality of patterned dielectric layers and conductive layers, and the conductive layers are coupled to various doped structures, circuits, photodiode gates, reset transistors, source follower transistors, and transfer transistors. For example, the interconnect structure 130 includes an interlayer dielectric layer 132, and a multilayer interconnect structure 134 in the interlayer dielectric layer.

[0080] The multilayer interconnect structure 134 includes a conductive line 134a and a through hole (or contact) 134b connected to the conductive line 134a. It should be understood that the conductive line 134a and the through hole 134b are only used as examples. The actual position and arrangement of the conductive line 134a and the through hole 134b depend on design requirements and process considerations.

[0081] In some embodiments, the carrier substrate 140 is then bonded to the interconnect structure 130. The carrier substrate 140 includes a silicon substrate, a glass substrate, or another suitable substrate. Figure 1B and Figure 1C As shown, a thinning process is then performed to thin the semiconductor substrate 110 from the back side 114. The thinning process may include a chemical mechanical polishing process.

[0082] In some embodiments, thereafter Figure 1C As shown, the semiconductor substrate 110 is flipped over and a trench 119 is formed in the semiconductor substrate 110. In some embodiments, the trench 119 extends from the back surface 114 into the semiconductor substrate 110. In some embodiments, the trench 119 is located between every two adjacent light sensing regions 118. In some embodiments, the trench 119 surrounds each light sensing region 118.

[0083] In some embodiments, the trench 119 is located on the isolation structure 120. In some embodiments, the trench 119 exposes the isolation structure 120. In some embodiments, the end surface 120a of the isolation structure 120 faces the back surface 114. In some embodiments, the trench 119 exposes the end surface 120a. In some embodiments, the trench 119 exposes the etch stop layer 122.

[0084] In some embodiments, the trench 119 has a depth D2. In some embodiments, the ratio between the depth D2 of the trench 119 and the thickness T1 of the semiconductor substrate 110 is between about 0.2 and about 0.98. In some embodiments, the ratio between the depth D2 of the trench 119 and the thickness T1 of the semiconductor substrate 110 is between about 0.5 and about 0.98. In some embodiments, the depth D2 is greater than the depth D1.

[0085] In some embodiments, thereafter Figure 1DAs shown, an insulating layer 150 is formed on the back surface 114 and the trench 119. In some embodiments, the insulating layer 150 continuously and conformably covers the back surface 114, and the lower surface 119a (eg, the end surface 120a) and the inner sidewall 119b of the trench 119.

[0086] In some embodiments, the insulating layer 150 is also referred to as a liner layer. In some embodiments, the insulating layer 150 directly contacts the isolation structure 120 and the semiconductor substrate 110. In some embodiments, the insulating layer 150 directly contacts the etching stop layer 122.

[0087] In some embodiments, the insulating layer 150 is used to passivate the back surface 114 , the lower surface 119 a , and the inner sidewall 119 b . In some embodiments, the insulating layer 150 is also used to electrically isolate the light sensing regions 118 from each other to reduce electrical crosstalk between the light sensing regions 118 .

[0088] In some embodiments, the insulating layer 150 includes silicon oxide. The insulating layer 150 includes a high-k dielectric material, a dielectric material, or other suitable insulating materials. The high-k dielectric material may include hafnium oxide, tantalum oxide, zirconium oxide, aluminum oxide, other suitable materials, or combinations thereof.

[0089] For example, the dielectric material includes silicon nitride, silicon oxynitride, other suitable materials, or combinations thereof. For example, the insulating layer 150 may be formed by a thermal oxidation process or a deposition process (eg, a chemical vapor deposition process or a physical vapor deposition process).

[0090] In some embodiments, then Figure 1D As shown, a light blocking structure 160 is formed in the trench 119. In some embodiments, the light blocking structure 160 is formed on the insulating layer 150. In some embodiments, an upper surface 150a of the insulating layer 150 and an upper surface 160a of the light blocking structure 160 are substantially coplanar.

[0091] Figure 2B In some embodiments, Figure 1D FIG. 1 is a top view of the light blocking structure 160 and the insulating layer 150 . Figure 1D In some embodiments, the intermediate structure of the image sensing device is along Figure 2B In some embodiments, as shown in FIG. Figure 1D and Figure 2B As shown, the trench 119 and the light blocking structure 160 therein surround each light sensing region 118 .

[0092] In some embodiments, the insulating layer 150 is located between the light blocking structure 160 and the semiconductor substrate 110 to separate the light blocking structure 160 from the semiconductor substrate 110. In some embodiments, the insulating layer 150 can electrically insulate the light blocking structure 160 from the semiconductor substrate 110.

[0093] In some embodiments, the insulating layer 150 and the light blocking structure 160 fill the trench 119. In some embodiments, the light blocking structure 160 is located between every two adjacent light sensing regions 118. In some embodiments, the light blocking structure 160 is used to block incident light to prevent the incident light from penetrating different light sensing regions 118.

[0094] In some embodiments, the light blocking structure 160 includes a light reflecting structure. In some embodiments, the refractive index of the light reflecting structure is lower than the refractive index of the semiconductor substrate 110, so that part of the incident light reaching the light reflecting structure can be reflected (i.e., the so-called total internal reflection phenomenon). The light reflecting structure can include a dielectric material, such as silicon oxide, silicon nitride, or silicon carbide.

[0095] In some embodiments, the light reflectivity of the light reflective structure is between about 60% and about 100%. In some embodiments, the light reflective structure comprises a metal material or an alloy material. The light reflective structure may comprise aluminum, tungsten, copper, titanium, alloys thereof, combinations thereof, or another suitable reflective material.

[0096] In some other embodiments, the light blocking structure 160 includes a light absorbing structure. In some embodiments, the light absorption rate of the light absorbing structure is between about 60% and about 100%. In some embodiments, the light absorbing structure is used to absorb incident light reaching the light absorbing structure to prevent the incident light from penetrating different light sensing regions 118.

[0097] In some embodiments, the light absorption structure comprises black silicon material, semiconductor material with energy gap less than 1.5 eV (such as germanium, indium antimonide, or indium arsenide), or polymer material (opaque polymer material). In some embodiments, the light absorption structure comprises an invisible light filter (such as an infrared filter or an ultraviolet filter), which can be used to block visible light and allow invisible light to pass through.

[0098] In some embodiments, the method of forming the light blocking structure 160 includes depositing a light blocking material layer on the semiconductor substrate 110 to fill the trench 119 ; and removing the light blocking material layer outside the trench 119 .

[0099] The method for depositing the light blocking material layer may include a chemical vapor deposition process, a physical vapor deposition process, a coating process, or another suitable process. The method for removing the light blocking material layer outside the trench 119 may include a chemical mechanical polishing process or another suitable process.

[0100] In some embodiments, the light blocking structure 160 and the insulating layer 150 together form an isolation structure S. In some embodiments, the isolation structure S is used to separate the light sensing regions 118 from each other and to electrically isolate adjacent devices (eg, transistors) from each other.

[0101] In some embodiments, the isolation structure S extends from the back surface 114 into the semiconductor substrate 110. In some embodiments, the isolation structure S surrounds each light sensing region 118. In some embodiments, the isolation structure S is substantially aligned with the isolation structure 120.

[0102] In some embodiments, the isolation structure S directly contacts the isolation structure 120. In some embodiments, there is no gap (or semiconductor substrate 110) between the end surface 120a of the isolation structure 120 and the end surface S1 of the isolation structure S. In this way, the isolation structure 120 and the isolation structure S can reduce optical crosstalk and electrical crosstalk between adjacent light sensing regions 118.

[0103] In some embodiments, then Figure 1E As shown, an anti-reflection coating 170 and a buffer layer 180 are sequentially formed on the back surface 114 of the semiconductor substrate 110. The anti-reflection coating 170 is used to reduce the optical reflection of the back surface 114 of the semiconductor substrate 110 to ensure that the main incident light enters the light sensing area 118 and is sensed by the light sensing area 118.

[0104] The composition of the anti-reflective coating 170 can be a high dielectric constant material, a dielectric material, other suitable materials, or a combination thereof. The high dielectric constant material can include hafnium oxide, tantalum oxide, zirconium oxide, aluminum oxide, other suitable materials, or a combination thereof. For example, the dielectric material includes silicon nitride, silicon oxynitride, other suitable materials, or a combination thereof.

[0105] The buffer layer 180 serves as a buffer between the anti-reflective coating 170 and the subsequently formed upper layers. The buffer layer 180 may be made of a dielectric material or other suitable materials. For example, the buffer layer 180 may be made of silicon oxide, silicon nitride, silicon oxynitride, other feasible materials, or combinations thereof.

[0106] In some embodiments, then Figure 1EAs shown, a reflective grid 190 is formed on the buffer layer 180. The reflective grid 190 may include a reflective element 192. In some embodiments, the reflective element 192 is aligned with the light blocking structure 160. In some embodiments, the reflective element 192 is located directly on the light blocking structure 160. In some other embodiments, the reflective element 192 is not located directly on the light blocking structure 160. Each reflective element 192 is used to prevent incident light from entering adjacent light sensing regions 118, thereby avoiding or reducing the crosstalk problem between the light sensing regions 118.

[0107] In some embodiments, the reflective grid 190 is made of a reflective material such as a metal material. The reflective grid 190 may be made of aluminum, silver, copper, titanium, platinum, tungsten, tantalum, tantalum nitride, other suitable materials, or a combination thereof. In some embodiments, the reflective grid 190 is formed on the buffer layer 180 by a suitable process. For example, the suitable process includes physical vapor deposition, electroplating process, chemical vapor deposition, other feasible processes, or a combination thereof.

[0108] In some embodiments, a dielectric layer 210 is then formed on the buffer layer 180 to cover the reflective grid 190. The dielectric layer 210 may be made of silicon oxide, silicon nitride, silicon oxynitride, or other suitable materials. The dielectric layer 210 may be formed by chemical vapor deposition or another suitable process. The dielectric layer 210 has a plurality of recesses 212R, 212G, and 212B.

[0109] Then, visible light filters (such as color filters 220R, 220G, and 220B) are formed in the recesses 212R, 212G, and 212B, respectively. In some embodiments, the visible light filter can be used to filter light and allow visible light to pass through. The color filters 220R, 220G, and 220B can filter light to allow light in the red wavelength band, the green wavelength band, and the blue wavelength band to pass through, respectively. In some embodiments, the light blocking structure 160 includes a non-visible light filter (such as an infrared filter or an ultraviolet filter), which can be used to block visible light passing through the visible light filter.

[0110] In some embodiments, lenses 230 are then formed on the color filters 220R, 220G, and 220B, respectively. The lenses 230 are used to guide and focus incident light. The lenses 230 may include a microlens array. The lenses 230 may be composed of a high light transmittance material. For example, the high light transmittance material may include a transparent polymer material such as polymethyl methacrylate, a transparent ceramic material such as glass, other feasible materials, or a combination thereof. In some embodiments, this step has substantially formed the image sensor device 100.

[0111] like Figure 1EAs shown, the light blocking structure 160 can absorb or reflect the incident light L that passes through the color filter 220R and reaches the light blocking structure 160. In this way, the light blocking structure 160 can reduce the optical crosstalk between adjacent light sensing regions 118.

[0112] In some embodiments, since the isolation structure 120 directly contacts the isolation structure S, the isolation structure 120 and the isolation structure S completely separate the light sensing regions 118 from each other. In this way, the isolation structure 120 and the isolation structure S can further reduce optical crosstalk.

[0113] In some embodiments, the isolation structure 120 in the image sensing device 100 extends from the front surface 112 into the semiconductor substrate 110 . In some embodiments, the isolation structure 120 surrounds the light sensing region 118 .

[0114] In some embodiments, the insulating layer 124 extends from the front surface 112 into the semiconductor substrate 110 . In some embodiments, the etch stop layer 122 is located between the insulating layer 124 and the isolation structure S. In some embodiments, the light blocking structure 160 extends from the back surface 114 into the semiconductor substrate 110 .

[0115] In some embodiments, the minimum width W1m of the isolation structure S in the trench 119 is smaller than the minimum width W2m of the isolation structure 120. In some embodiments, the width W1 of the isolation structure S in the trench 119 continuously decreases from the back surface 114 toward the isolation structure 120 thereunder. In some embodiments, the width W1 of the isolation structure S in the trench 119 continuously decreases in a direction V1 toward the front surface 112.

[0116] In some embodiments, the width W2 of the isolation structure 120 continuously decreases from the front surface 112 toward the isolation structure S thereon. In some embodiments, the width W2 of the isolation structure 120 continuously decreases in a direction V2 toward the back surface 114 .

[0117] Figure 3 is a cross-sectional view of the image sensing device 300 in some embodiments. In some embodiments, Figure 3 The image sensing device 300 shown is Figure 1E The image sensing device 300 is similar to the image sensing device 100 , except that the etch stop layer 122 of the image sensing device 300 only covers a portion of the inner sidewall 116 b adjacent to the lower surface 116 a of the trench 116 .

[0118] In some embodiments, the etching stop layer 122 of the image sensor device 300 does not cover the inner sidewall 116 b adjacent to the front surface 112 , thereby reducing the aspect ratio of the trench 116 and improving the process yield of filling the trench 116 with the insulating layer 124 .

[0119] Figure 4 is a cross-sectional view of the image sensing device 400 in some embodiments. In some embodiments, Figure 4 The image sensing device 400 is shown with Figure 1E The image sensor device 100 is similar to the image sensor device 100, except that the ratio between the depth D1 of the trench 116 and the thickness T1 of the semiconductor substrate 110 of the image sensor device 400 is greater than the ratio between the depth D1 of the trench 116 and the thickness T1 of the semiconductor substrate 110 of the image sensor device 100. In this way, the aspect ratio of the trench 119 can be reduced.

[0120] In this way, the process yield of filling the light blocking structure 160 into the trench 119 can be improved. The ratio between the depth D1 of the trench 116 and the thickness T1 of the semiconductor substrate 110 of the image sensor device 400 can be between about 0.3 and about 0.5.

[0121] Figure 5 is a cross-sectional view of the image sensing device 500 in some embodiments. In some embodiments, Figure 5 The image sensing device 500 shown is Figure 1E The image sensing device 100 is similar to the image sensing device 500 , except that the isolation structure S extends into the isolation structure 120 of the image sensing device 500 .

[0122] In some embodiments, the trench 119 extends into the isolation structure 120. In some embodiments, the isolation structure S in the trench 119 is partially formed in the isolation structure 120. In some embodiments, the trench 119 extends to the etch stop layer 122. In some embodiments, the trench 119 does not pass through the etch stop layer 122. In some embodiments, the portion of the etch stop layer 122 between the insulating layer 124 and the isolation structure S can separate the insulating layer 124 into the isolation structure S.

[0123] In some embodiments, the isolation structure S has a first end E1 and a second end E2. In some embodiments, the first end E1 is located between the second end E2 and the isolation structure 120. In some embodiments, the first end E1 partially extends into the isolation structure 120. In some embodiments, the first end E1 does not pass through the etching stop layer 122.

[0124] In some embodiments, a distance D3 is provided between the back surface 114 and the lower surface 116a of the trench 116. In some embodiments, a depth D2 of the trench 119 is greater than the distance D3. In some embodiments, a sum of the depth D1 and the depth D2 is greater than the thickness T1 of the semiconductor substrate 110.

[0125] Figure 6 is a cross-sectional view of an image sensing device 600 in some embodiments. Figure 6The image sensing device 600 shown is Figure 1E The image sensing device 100 is similar to the image sensing device 100 except that the minimum width W1m of the isolation structure S in the trench 119 is greater than the minimum width W2m of the isolation structure 120. In some embodiments, the maximum width W1x of the isolation structure S in the trench 119 is greater than the maximum width W2x of the isolation structure 120.

[0126] Figure 7 is a cross-sectional view of the image sensing device 700 in some embodiments. In some embodiments, Figure 7 The image sensing device 700 shown is Figure 6 The image sensing device 600 is similar to the image sensing device 600 except that the isolation structure 120 partially extends into the isolation structure S. In some embodiments, the etch stop layer 122 partially extends into the isolation structure S (or the insulating layer 150).

[0127] In some embodiments, a distance D3 is provided between the back surface 114 and the lower surface 116a of the trench 116. In some embodiments, a depth D2 of the trench 119 is greater than the distance D3. In some embodiments, before forming the isolation structure S, the trench 119 exposes the end surface 120a and the sidewall 120b of the isolation structure 120.

[0128] In some embodiments, the surface 120 a faces the back surface 114 , and the sidewall 120 b is adjacent to the end surface 120 a . In some embodiments, the insulating layer 150 covers the end surface 120 a and the sidewall 120 b of the isolation structure 120 .

[0129] Figure 8 is a cross-sectional view of the image sensing device 800 in some embodiments. In some embodiments, Figure 8 The image sensing device 800 shown is Figure 1E The image sensing device 800 is similar to the image sensing device 100 , except that the light blocking structure 160 of the image sensing device 800 includes a light reflecting structure 162 and a light absorbing structure 164 .

[0130] In some embodiments, the light reflecting structure 162 and the light absorbing structure 164 are sequentially formed in the groove 119. In some embodiments, the light absorbing structure 164 is formed on the light reflecting structure 162. In some embodiments, the light absorbing structure 164 has an upper surface 164a. In some embodiments, the upper surface 164a is substantially coplanar with the upper surface 150a of the insulating layer 150. In some embodiments, the light absorbing structure 164 and the light reflecting structure 162 are made of different materials.

[0131] In some embodiments, the refractive index of the light reflective structure 162 is lower than that of the semiconductor substrate 110, so the light reflective structure 162 can reflect a portion of incident light reaching the light reflective structure 162. The light reflective structure 162 includes a dielectric material, such as silicon dioxide, silicon nitride, or silicon carbide.

[0132] In some embodiments, the light reflectivity of the light reflective structure 162 is between about 60% and about 100%. In some embodiments, the light reflective structure 162 includes a metal material or an alloy material. The light reflective structure 162 includes aluminum, tungsten, copper, titanium, alloys thereof, combinations thereof, or another suitable reflective material.

[0133] In some embodiments, the light absorption rate of the light absorption structure 164 is between about 60% and about 100%. In some embodiments, the light absorption structure 164 is used to absorb incident light reaching the light absorption structure 164 to prevent the incident light from passing through different light sensing regions 118 .

[0134] In some embodiments, the light absorption structure 164 includes black silicon material, semiconductor material with an energy gap less than 1.5 eV (such as germanium, indium antimonide, or indium arsenide), or polymer material (opaque polymer material). In some embodiments, the light absorption structure 164 includes an invisible light filter (such as an infrared filter or an ultraviolet filter), which can be used to block visible light and allow invisible light to pass through.

[0135] In some embodiments, the light absorbing structure 164 is located closer to the back surface 114 than to the front surface 112. In some embodiments, the light reflecting structure 162 is located between the light absorbing structure 164 and the isolation structure 120. In some embodiments, the thickness T4 of the light absorbing structure 164 is less than the thickness T5 of the light reflecting structure 162.

[0136] In some embodiments, Figure 8 The light reflecting structure 162 shown can reflect the incident light L1 that passes through the color filter 220R and reaches the light reflecting structure 162. The light absorbing structure 164 can absorb the incident light L2 that passes through the color filter 220R and reaches the light absorbing structure 164, so as to prevent the incident light L2 from being reflected to the adjacent light sensing area 118. In this way, the light blocking structure 160 composed of the light reflecting structure 162 and the light absorbing structure 164 can reduce optical crosstalk.

[0137] Fig. 9 is a cross-sectional view of the image sensing device 900 in some embodiments. In some embodiments, Fig. 9 The image sensing device 900 shown is Figure 1E The image sensing device 100 is similar to that shown, except that the image sensing device 900 does not include Figure 1EThe insulating layer 150 of the image sensing device 100. In some embodiments, the light blocking structure 160 is made of an insulating material.

[0138] In some embodiments, the light blocking structure 160 directly contacts the isolation structure 120. In some embodiments, the light blocking structure 160 directly contacts the etch stop layer 122.

[0139] Fig.10 is a cross-sectional view of an image sensing device in some embodiments. In some embodiments, Fig.10 The image sensing device 1000 shown in FIG. Fig. 9 The image sensing device 900 is similar to the image sensing device 900, except that the image sensing device 1000 does not include Fig. 9 The etch stop layer 122 of the image sensing device 900 is shown in FIG. 1 . In some embodiments, the light blocking structure 160 directly contacts the insulating layer 124 .

[0140] In some embodiments, an image sensing device and a method for forming the same are provided. The method for forming the image sensing device forms a first isolation structure and a second isolation structure in a semiconductor substrate, and between adjacent light sensing regions of the semiconductor substrate. The semiconductor substrate has a front side and a back side. The first isolation structure and the second isolation structure extend from the front side and the back side respectively, and meet each other in the semiconductor substrate. The first isolation structure and the second isolation structure completely separate the light sensing regions from each other. In this way, the first isolation structure and the second isolation structure can block incident light reaching the first isolation structure and the second isolation structure to prevent the incident light from penetrating adjacent light sensing regions. Therefore, optical crosstalk between light sensing regions can be reduced. The first isolation structure and the second isolation structure can electrically isolate the light sensing regions from each other to reduce electrical crosstalk between the light sensing regions.

[0141] In some embodiments, a method for forming an image sensing device is provided. The method includes forming a first groove in a substrate. The substrate has a front side and a back side, and the first groove extends from the front side into the substrate. The method includes forming a first isolation structure in the first groove. The method includes forming a light sensing region in the substrate. The first isolation structure surrounds the light sensing region. The method includes forming a second groove in the substrate. The second groove extends from the back side into the substrate and exposes the first isolation structure. The method includes forming a second isolation structure in the second groove. The second isolation structure includes a light blocking structure to absorb or reflect incident light.

[0142] In some embodiments, the steps of forming a first isolation structure in the above method include: forming an etch stop layer on the lower surface of the first trench, wherein the second trench exposes the etch stop layer; and forming a first insulating layer in the first trench and on the etch stop layer, wherein the etch stop layer, the first insulating layer, and the substrate are composed of different materials.

[0143] In some embodiments, the step of forming the second isolation structure in the above method includes: forming a second insulating layer in the second trench; and forming a light blocking structure in the second trench and on the second insulating layer, wherein the second insulating layer is located between the light blocking structure and the substrate to separate the light blocking structure and the substrate, and the light blocking structure surrounds the light sensing area.

[0144] In some embodiments, the second insulating layer of the above method directly contacts the etch stop layer.

[0145] In some embodiments, the etching stop layer of the above method covers the lower surface and the inner sidewall of the first trench, and the etching stop layer covering the lower surface is thicker than the etching stop layer covering the inner sidewall.

[0146] In some embodiments, the light blocking structure of the above method includes a light reflecting structure having a refractive index lower than a refractive index of the substrate.

[0147] In some embodiments, the light blocking structure of the above method includes a light reflecting structure, and the light reflecting structure is made of a metal material or an alloy material.

[0148] In some embodiments, the light blocking structure of the above method includes a light absorbing structure having a light absorption rate between about 60% and about 100%.

[0149] In some embodiments, a method for forming an image sensing device is provided. The method includes: forming a first groove in a substrate. The substrate has a front side and a back side. The first groove extends from the front side into the substrate. There is a distance between the lower surface of the first groove and the back side. The method includes forming a first isolation structure in the first groove. The method includes forming a light sensing area in the substrate. The first isolation structure surrounds the light sensing area. The method includes forming a second groove in the substrate. The second groove extends from the back side into the substrate and exposes the first isolation structure, and the depth of the second groove is greater than the distance. The method includes forming a second isolation structure in the second groove. The second isolation structure includes a light blocking structure to absorb or reflect incident light.

[0150] In some embodiments, the second trench of the above method further extends into the first isolation structure.

[0151] In some embodiments, the second isolation structure in the second trench of the above method is partially formed in the first isolation structure.

[0152] In some embodiments, the steps of forming a first isolation structure in the above method include: forming an etch stop layer on the lower surface of the first trench; and forming a first insulating layer in the first trench and on the etch stop layer; wherein the etch stop layer, the first insulating layer, and the substrate are composed of different materials, the second trench extends into the etch stop layer, and a portion of the etch stop layer is located between the first insulating layer and the second isolation structure.

[0153] In some embodiments, the second trench of the above method exposes a surface and a sidewall of the first isolation structure, the surface of the first isolation structure faces the back surface, and the sidewall is adjacent to the surface.

[0154] In some embodiments, the steps of forming the second isolation structure in the above method include: forming an insulating layer in the second groove, wherein the insulating layer covers the surface and side walls of the first isolation structure; and forming a light blocking structure in the second groove and on the insulating layer, wherein the insulating layer is located between the light blocking structure and the substrate to separate the light blocking structure and the substrate.

[0155] In some embodiments, the step of forming the second isolation structure in the above method includes: forming a light reflecting structure in the second groove, wherein the light reflectivity of the light reflecting structure is between about 60% and about 100%; and forming a light absorbing structure in the second groove and on the light reflecting structure, wherein the light absorption rate of the light absorbing structure is between about 60% and about 100%, and the light reflecting structure and the light absorbing structure together form a light blocking structure.

[0156] In some embodiments, an image sensing device is provided. The image sensing device includes a substrate having a front side, a back side, and a light sensing region. The image sensing device includes a first isolation structure extending from the front side into the substrate. The first isolation structure surrounds the light sensing region. The image sensing device includes a second isolation structure extending from the back side into the substrate. The second isolation structure directly contacts the first isolation structure. The second isolation structure surrounds the light sensing region. The second isolation structure includes a light blocking structure.

[0157] In some embodiments, the first isolation structure of the image sensor device includes: a first insulating layer extending from the front side into the substrate; and an etching stop layer located between the first insulating layer and the second isolation structure, wherein the etching stop layer, the first insulating layer, and the substrate are composed of different materials.

[0158] In some embodiments, the light blocking structure of the image sensor device extends from the back side into the substrate, and the second isolation structure further includes: a second insulating layer located between the light blocking structure and the substrate to electrically insulate the light blocking structure from the substrate, wherein the second insulating layer directly contacts the etching stop layer.

[0159] In some embodiments, the second isolation structure of the image sensor device has a first end portion and a second end portion, the first end portion is located between the second end portion and the first isolation structure, and the first end portion partially extends into the first isolation structure.

[0160] In some embodiments, the first isolation structure of the image sensing device partially extends into the second isolation structure.

[0161] The present disclosure has been disclosed as above with several embodiments to facilitate the understanding of the present disclosure by those skilled in the art. Those skilled in the art may adopt the present disclosure as a basis to design or adjust other processes and structures to implement the same purpose of the embodiments and / or achieve the same advantages of the embodiments. Those skilled in the art should understand that the above-mentioned equivalent substitutions do not deviate from the concept and scope of the present disclosure, and may make these different changes, substitutions, and adjustments without deviating from the concept and scope of the present disclosure.

Claims

1. A method for forming an image sensor device, comprising: Forming a first trench in a substrate, wherein the substrate has a front surface and a back surface, and the first trench extends from the front surface into the substrate; A first isolation structure is formed in the first trench, wherein the step of forming the first isolation structure comprises: forming an etch stop layer on a lower surface of the first trench; and forming a first insulating layer in the first trench and on the etch stop layer, wherein the etch stop layer, the first insulating layer, and the substrate are composed of different materials, and the etch stop layer and the first insulating layer together form the first isolation structure; forming a light sensing region in the substrate, wherein the first isolation structure surrounds the light sensing region; forming a second trench in the substrate, wherein the second trench extends from the back surface into the substrate and exposes the etching stop layer of the first isolation structure; and A second isolation structure is formed in the second trench, wherein the second isolation structure includes a light blocking structure to absorb or reflect incident light.

2. The method for forming an image sensor device as claimed in claim 1, wherein the step of forming the second isolation structure comprises: forming a second insulating layer in the second trench; as well as The light blocking structure is formed in the second trench and on the second insulating layer, wherein the second insulating layer is located between the light blocking structure and the substrate to separate the light blocking structure from the substrate, and the light blocking structure surrounds the light sensing area. 3 . The method for forming an image sensor device as claimed in claim 2 , wherein the second insulating layer directly contacts the etching stop layer. 4 . The method for forming an image sensor device as claimed in claim 1 , wherein the etching stop layer covers the lower surface and inner sidewall of the first trench, and the etching stop layer covering the lower surface is thicker than the etching stop layer covering the inner sidewall. 5 . The method for forming an image sensor device as claimed in claim 1 , wherein the light blocking structure comprises a light reflecting structure having a refractive index lower than a refractive index of the substrate. 6 . The method for forming an image sensor device as claimed in claim 1 , wherein the light blocking structure comprises a light reflecting structure, and the light reflecting structure is made of a metal material or an alloy material. 7 . The method for forming an image sensor device as claimed in claim 1 , wherein the light blocking structure comprises a light absorbing structure, and a light absorption rate thereof is between 60% and 100%.

8. A method for forming an image sensing device, comprising: Forming a first trench in a substrate, wherein the substrate has a front surface and a back surface, and the first trench extends from the front surface into the substrate; forming a first isolation structure in the first trench; forming a light sensing region in the substrate, wherein the first isolation structure surrounds the light sensing region; forming a second trench in the substrate, wherein the second trench extends from the back surface into the substrate and exposes the first isolation structure; as well as A second isolation structure is formed in the second groove, wherein the second isolation structure includes a light blocking structure to absorb or reflect incident light, the second isolation structure has an end portion in the first isolation structure, the end portion has an end surface and a side wall adjacent to the end surface, and the first isolation structure covers the end surface and the side wall.

9. The method for forming an image sensor device as claimed in claim 8, wherein the step of forming the first isolation structure comprises: forming an etch stop layer on the lower surface of the first trench; as well as forming a first insulating layer in the first trench and on the etching stop layer; The etching stop layer, the first insulating layer, and the substrate are made of different materials. The second trench extends into the etching stop layer, and a portion of the etching stop layer is located between the first insulating layer and the second isolation structure.

10. The method for forming an image sensor device as claimed in claim 9, wherein the step of forming the second isolation structure comprises: forming an insulating layer in the second trench, wherein the insulating layer covers the etching stop layer; as well as A light blocking structure is formed in the second trench and on the insulating layer, wherein the insulating layer is located between the light blocking structure and the etching stop layer. 11 . The method for forming an image sensor device as claimed in claim 10 , wherein the insulating layer is partially located in the etching stop layer.

12. The method for forming an image sensor device as claimed in claim 8, wherein the step of forming the second isolation structure comprises: forming a light reflective structure in the second groove, wherein the light reflectivity of the light reflective structure is between 60% and 100%; as well as A light absorbing structure is formed in the second groove and on the light reflecting structure, wherein the light absorption rate of the light absorbing structure is between 60% and 100%, and the light reflecting structure and the light absorbing structure together form a light blocking structure.

13. A method for forming an image sensing device, comprising: Forming a first trench in a substrate, wherein the first trench extends from a front surface of the substrate into the substrate; forming a first isolation structure in the first trench; forming a light sensing region in the substrate, wherein the first isolation structure surrounds the light sensing region; forming a second trench in the substrate, wherein the second trench extends from a back side of the substrate into the substrate and exposes the first isolation structure; as well as A second isolation structure is formed in the second trench, wherein the first isolation structure partially extends into the second isolation structure. 14 . The method for forming an image sensor device as claimed in claim 13 , wherein the second trench exposes a surface and a side wall of the first isolation structure, the surface faces the back surface of the substrate, and the side wall is adjacent to the surface.

15. The method for forming an image sensor device as claimed in claim 14, wherein the step of forming the second isolation structure comprises: forming an insulating layer in the second trench, wherein the insulating layer covers the surface and the sidewall of the first isolation structure; as well as A light blocking structure is formed in the second trench and on the insulating layer, wherein the insulating layer is located between the light blocking structure and the substrate to separate the light blocking structure from the substrate. 16 . The method for forming an image sensor device as claimed in claim 15 , wherein the insulating layer is located between the light blocking structure and the first isolation structure.

17. The method for forming an image sensor device as claimed in claim 13, wherein the step of forming the first isolation structure comprises: forming an etch stop layer on a lower surface of the first trench, wherein the second trench exposes the etch stop layer; as well as A first insulating layer is formed in the first trench and on the etching stop layer, wherein the etching stop layer, the first insulating layer, and the substrate are composed of different materials. 18 . The method for forming an image sensor device as claimed in claim 17 , wherein the etching stop layer is partially located in the second isolation structure. 19 . The method for forming an image sensor device as claimed in claim 18 , wherein the etching stop layer directly contacts the second isolation structure.

20. The method for forming an image sensor device as claimed in claim 18, wherein the step of forming the second isolation structure comprises: forming an insulating layer in the second trench, wherein the insulating layer covers the etching stop layer; as well as A light blocking structure is formed in the second trench and on the insulating layer, wherein the insulating layer is located between the light blocking structure and the etching stop layer.

21. An image sensing device, comprising a substrate having a front surface, a back surface, and a light sensing area; a first isolation structure extending from the front surface into the substrate, wherein the first isolation structure surrounds the light sensing region, the first isolation structure comprises a first insulating layer and an etch stop layer, the first insulating layer extending from the front surface into the substrate, the etch stop layer is located between the first insulating layer and the substrate, and the etch stop layer, the first insulating layer, and the substrate are made of different materials; and a second isolation structure extending from the back side into the substrate, wherein the second isolation structure directly contacts the etching stop layer, the isolation structure surrounds the light sensing region, the second isolation structure includes a light blocking structure extending from the back side into the substrate, and the second isolation structure further includes: A second insulating layer is located between the light blocking structure and the substrate, and between the light blocking structure and the etching stop layer, the etching stop layer directly contacts the first insulating layer, the second insulating layer, and the substrate, wherein a first end portion of the first isolation structure surrounds a second end portion of the second isolation structure.

22. The image sensing device as claimed in claim 21, wherein the second insulating layer is partially located in the first isolation structure.

23. The image sensing device as claimed in claim 21, wherein the second insulating layer is partially located in the etch stop layer. 24 . The image sensing device as claimed in claim 23 , wherein the etch stop layer is located between the first insulating layer and the second insulating layer.

25. The image sensing device as claimed in claim 21, wherein the light blocking structure is partially located in the first isolation structure. 26 . The image sensor device as claimed in claim 21 , wherein the first insulating layer has an end surface and a side wall adjacent to the end surface, the end surface faces the second isolation structure, and the etching stop layer continuously covers the end surface and the side wall. 27 . The image sensing device as claimed in claim 21 , wherein the light blocking structure comprises a light reflecting structure, and a refractive index of the light reflecting structure is lower than a refractive index of the substrate.

28. An image sensing device, comprising: A substrate having a front surface, a back surface, and a light sensing area; a first isolation structure extending from the front surface into the substrate, wherein the first isolation structure surrounds the light sensing area; as well as A second isolation structure extends from the back side to the substrate and the first isolation structure, wherein the second isolation structure surrounds the light sensing area, the second isolation structure has a first end portion in the first isolation structure, the first end portion has an end surface and a side wall adjacent to the end surface, the first isolation structure covers the end surface and the side wall, and the second isolation structure includes a light blocking structure.

29. An image sensing device as described in claim 28, wherein the first isolation structure includes an insulating layer and an etch stop layer, the insulating layer extends from the front side into the substrate, the etch stop layer encapsulates the insulating layer, the etch stop layer covers the end surface and the side wall, and the etch stop layer, the insulating layer, and the substrate are composed of different materials. 30 . The image sensing device as claimed in claim 28 , wherein the first isolation structure has a second end portion, the first end portion is buried in the second end portion, and the second end portion is wider than the first end portion. 31 . The image sensing device as claimed in claim 28 , wherein the light blocking structure comprises a light reflecting structure, and the light reflecting structure is made of a metal material or an alloy material.

32. The image sensing device as claimed in claim 28, wherein the light blocking structure comprises a light absorbing structure, and a light absorption rate thereof is between 60% and 100%.

33. An image sensing device comprising: A substrate having a front surface, a back surface, and a light sensing area; a first isolation structure extending from the front surface into the substrate, wherein the first isolation structure surrounds the light sensing area; as well as A second isolation structure extends from the back side into the substrate, wherein the second isolation structure surrounds the light sensing area, the first isolation structure is partially buried in the second isolation structure, the second isolation structure includes a light blocking structure, a first end portion of the first isolation structure is partially buried in a second end portion of the second isolation structure, and the second end portion is wider than the first end portion.

34. An image sensing device as described in claim 33, wherein the first isolation structure includes a first insulating layer and an etch stop layer, the first insulating layer extends from the front side into the substrate, the etch stop layer covers the first insulating layer, and the etch stop layer is partially buried in the second isolation structure.

35. The image sensing device of claim 34, wherein the light blocking structure extends from the back surface into the substrate, and the second isolation structure further comprises: A second insulating layer is located between the light blocking structure and the substrate, and between the light blocking structure and the etching stop layer.

36. The image sensing device as claimed in claim 35, wherein the etch stop layer is partially buried in the second insulating layer.

37. The image sensing device as claimed in claim 35, wherein the second insulating layer covers a portion of the etch stop layer.

38. The image sensing device as claimed in claim 37, wherein the etching stop layer has an end surface and a side wall adjacent to the end surface, the end surface faces the second isolation structure, and the second insulating layer continuously covers the end surface and the side wall.

39. The image sensing device as claimed in claim 33, wherein the light sensing area covered by the first isolation structure is wider than the light sensing area covered by the second isolation structure.

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