TWI407559B - Image sensor and related fabricating method thereof - Google Patents

Abstract

A fabricating method of an image sensor includes the steps of: providing a substrate; forming sensing elements on the substrate; forming microlenses on the sensing elements; filling a stuffed material on the microlenses, and air regions are formed in the stuffed material; and forming optical filters on the stuffed material.

Description

Image sensor and related manufacturing method

The present invention relates to an image sensor, and more particularly to a complementary metal oxide semiconductor (CMOS) image sensor (hereinafter referred to as a CMOS image sensor) and related manufacturing methods.

Digital cameras are electronic products that are widely used today, and digital cameras have image sensors for converting light into electric charges. The image sensor can be divided into a Charge-Coupled Device image sensor (also known as a CCD image sensor) and a complementary MOS image sensor (also known as CMOS) according to the principle adopted by the image sensor. Image sensor), wherein the CMOS image sensor is fabricated based on complementary metal oxide semiconductor technology.

Since the CMOS image sensor is fabricated by a conventional CMOS circuit process, the image sensor and the peripheral circuits required thereof can be fabricated together, so that the manufacturing cost is lower than that of the CCD image sensor. In addition to lower cost, CMOS image sensors have the advantages of small size and low power consumption.

Please refer to FIG. 1 , which is a schematic diagram of a conventional CMOS image sensor 100 . The CMOS image sensor 100 includes a substrate 110 and a plurality of pixels, and the plurality of pixels are disposed in the substrate 110. Each of the pixels includes a sensing component 160, a filter 120, and a microlens 130. The microlens 130 is used to collect an incident light 150, and the filter 120 is disposed between the substrate 110 and the microlens 130 for filtering the incident light 150. As shown in FIG. 1, the incident light 150 needs to penetrate the microlens 130 and the filter 120 one by one to reach the sensing element 160. That is to say, the structure of the conventional CMOS image sensor 100 causes the incident light 150 to have a great loss in the process of reaching the sensing element 160, so that only part of the incident light 150 can smoothly reach the sensing element 160. In addition, the conventional CMOS image sensor 100 also faces problems of low quantum efficiency and severe cross talk.

Therefore, there is an urgent need to propose new CMOS image sensors to provide better performance and solve the problems of the prior art.

One of the main objects of the present invention is to provide an image sensor and a method of fabricating the same to solve the problems in the prior art.

According to an embodiment of the invention, a method for fabricating an image sensor includes the steps of: providing a substrate; forming a sensing element on the substrate; forming a microlens on the sensing element; The microlens is filled with a filling material to form at least one air region in the filling material; and a filter is formed on the filling material.

In accordance with another embodiment of the present invention, an image sensor is disclosed that includes a substrate, a sensing element, a microlens, a fill material, and a filter. The sensing element is formed over the substrate. The microlens is formed over the sensing element. The filling material is filled over the microlens, wherein at least one air region is formed in the filling material. The filter is formed on the filling material.

Certain terms are used throughout the description and following claims to refer to particular elements. Those of ordinary skill in the art should understand that a hardware manufacturer may refer to the same component by a different noun. The scope of this specification and the subsequent patent application do not use the difference of the names as the means for distinguishing the elements, but the difference in function of the elements as the criterion for distinguishing. The term "including" as used throughout the specification and subsequent claims is an open term and should be interpreted as "including but not limited to". In addition, the term "coupled" is used herein to include any direct and indirect electrical connection. Therefore, if a first device is coupled to a second device, it means that the first device can be directly electrically connected to the second device or indirectly electrically connected to the second device through other devices or connection means.

Please refer to FIG. 2, which is a schematic diagram of a first embodiment of the image sensor 200 of the present invention. As shown in FIG. 2 , the image sensor 200 includes, but is not limited to, a substrate 210 and a plurality of pixels, and the plurality of pixels are disposed in the substrate 210 , wherein each pixel includes a sensing component 260 . A filter 220, a microlens 230, and a filling material 270. The filter 220 is used to filter an incident light 250 to generate filtered incident light 250f. The microlens 230 is formed on the sensing element 260 and disposed between the substrate 210 and the filter 220 for The filtered incident light 250f is collected to the sensing element 260. It should be noted that the filling material 270 is filled on the microlens 230, that is, the filling material 270 is filled on the microlens 230 to form a planar layer, so that the filter 220 can be formed on the filling material 270. on. Additionally, at least one air region 280 is formed in the fill material 270 for providing a refractive path to the filtered incident light 250f.

Please note that one of the main advantages of the image sensor 200 disclosed in the present invention is that the microlens 230 of the image sensor 200 is disposed between the substrate 210 and the filter 220, thereby effectively shortening the incident light. The light source path required to reach the pixel area can greatly reduce the light loss of the incident light before reaching the pixel area, thereby improving the performance of the CMOS image sensor. In addition, another advantage of the present invention is that the filter 220 is disposed above the microlens 230, so that the production cost can be reduced because the height of the filter 220 can be reduced compared to the conventional image sensor. .

In another embodiment of the invention, the fill material 270 can be filled over the microlens 260 using a deposition process, a sputtering process, or other process, but this is not a limitation of the invention. In the process of filling the filling material 270 in the microlens 260, at least one air region 280 is formed in the filling material 270, and the air region 280 is determined by adjusting the processing speed of the filling material 270 at the time of filling. Features such as adjusting the size or shape of the air region 280. Please note that in order for the filtered incident light 250f to effectively enter the microlens 230 to condense, the refractive index of the filling material 270 can be selected to be different from the refractive index of the filter 220 and the microlens 230. In addition, another main advantage of the present invention is that a filler 270 having a refractive index between the refractive index of the filter 220 and the refractive index of the microlens 230 can be selected, so that the concentrating effect of the microlens 230 can be increased. .

Furthermore, since the refractive index of the air is equal to 1, the air region 280 formed in the filling material 270 can provide a better refractive path of the filtered incident light 250f. It will be apparent to those skilled in the art that it will be readily appreciated that other processes for forming the air region 280 in the fill material 270 are possible without departing from the spirit of the present invention.

Please refer to FIG. 3, which is a schematic diagram of a second embodiment of the image sensor 300 of the present invention. As shown in FIG. 3, the image sensor 300 includes, but is not limited to, a substrate 210 and a plurality of pixels, and the plurality of pixels are disposed in the substrate 210, wherein each pixel includes a sensing component. 260, a filter 220, a microlens 230, a filling material 270, at least one air region 280, and a shield 340. Since the operation principle of the substrate 210, the sensing element 260, the filter 220, the microlens 230, the filling material 270, and the air region 280 in the image sensor 300 is the same as that in the image sensor 200, it is simple. For the sake of reference, we will not repeat them here. The main difference between the image sensor 300 and the image sensor 200 is that the image sensor 300 further includes a shield 340 disposed around the microlens 230 to prevent the sensing element 260 from being affected by stray light and to be incident on the image sensor 260. The incident light 250 of the shield 340 is reflected to the microlens 230.

Please note that the shield 340 is made of a reflective material such as a metallic substance. However, this is not a limitation of the present invention, and any other material that can achieve the same purpose can be used as the shield 340. In addition, in order to make the microlens 230 more effective from the stray light image, the height of the shield 340 can be designed not lower than the height of the microlens 230, but the invention is not limited thereto.

Referring to FIG. 1 and FIG. 3 simultaneously, one of the main advantages of the image sensor 300 of the present invention is that the image sensor 300 is higher in comparison with the conventional image sensor 100 in FIG. 1 . The shield 340, in this way, more effectively reduces crosstalk between the image sensor and adjacent pixels, and thereby increases quantum efficiency.

First, in order to more clearly understand the structure of the shield 340, refer to FIG. 4, which is a plan view of a plurality of image sensors 300 corresponding to a plurality of pixels, respectively. As shown in FIG. 4, a shield 340 is disposed around each pixel region 260 to reduce cross-interference between the image sensor and adjacent pixels. Through the above description, those skilled in the art can easily understand the mask. The features of the object 340 are not described in detail herein.

Please refer to FIG. 5, which is a schematic diagram of a third embodiment of the image sensor 500 of the present invention. As shown in FIG. 5, the structure of the image sensor 500 is similar to that of the image sensor 300. For the sake of brevity, the same portions will not be described herein. The main difference between the image sensor 500 and the image sensor 300 is the filling material 570 of the image sensor 500 (including a first portion 570A and a second portion 570B), and is used to fill the shield 340 and the filter. Between the light sheets 220. In other words, in the present embodiment, the filling material 570 will be filled in the space between the microlens 230 and the filter 220 (i.e., the first portion 570A), and will be filled in the shield 340. And in the space between the filters 220 (ie, the second portion 570B).

Please note that in the above embodiment, the image sensor 200/300/500 is implemented by a CMOS image sensor. In addition, the image sensor 200/300/500 can adopt a back side illumination (Back Side Illumination). , BSI) technology, but this is not a limitation of the invention, and any variation that conforms to the spirit of the invention belongs to the protection scope of the invention.

Please refer to FIG. 6. FIG. 6 is a flow chart showing an operation example of a method for manufacturing an image sensor according to the present invention, including but not limited to the following steps (note that if substantially the same is obtained) As a result, these steps do not have to be performed in accordance with the execution order shown in Figure 6):

Step 600: Start.

Step 610: Providing a substrate.

Step 620: Form a sensing element on the substrate.

Step 630: Form a microlens on the sensing element.

Step 640: Filling a filling material on the microlens to form at least one air region in the filling material.

Step 650: Form a filter over the fill material.

Please refer to the steps shown in Figure 6 and the components shown in Figure 2 (or Figure 3, Figure 5) for how each component works. For the sake of brevity, it will not be repeated here. The steps of the above-mentioned various processes are only the embodiments of the present invention, and are not intended to limit the present invention, and the method may further include other intermediate steps or may be several without departing from the spirit of the present invention. The steps are combined into a single step to make the appropriate changes.

The embodiments described above are only intended to illustrate the technical features of the present invention and are not intended to limit the scope of the present invention. Obviously, those skilled in the art should be able to easily understand that other designs for implementing image sensors are feasible.

In summary, an image sensor and related manufacturing method are provided in the embodiments of the present invention. By disposing the microlens between the substrate and the filter, the light source path required for the incident light to reach the pixel region can be effectively shortened. Moreover, the architecture of the image sensor of the present invention can provide better light source transmission efficiency to improve quantum efficiency, and more importantly, fill the filling material on the microlens, that is, fill in the microlens and the filter. The area of air formed in the interstitial material provides a better refraction path for the filtered incident light. In addition, the shielding 340 disposed around the microlens or the filling material filled between the shielding 340 and the filter 220 can more effectively improve the cross interference between adjacent pixels of the image sensor.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100, 200, 300, 500‧‧‧ image sensors

110, 210‧‧‧ substrate

120, 220‧‧‧ Filters

130, 230‧‧‧ microlenses

340‧‧‧ Shield

270, 570, 570A, 570B‧‧‧ Filling materials

116, 216‧‧‧ pixel area

115, 212‧‧‧Sensor components

150, 250‧‧‧ incident light

250f‧‧‧Filtered incident light

Figure 1 is a schematic diagram of a conventional CMOS image sensor.

2 is a schematic view of a first embodiment of an image sensor of the present invention.

Figure 3 is a schematic view of a second embodiment of the image sensor of the present invention.

Figure 4 is a top plan view of a plurality of image sensors respectively corresponding to a plurality of pixels.

Fig. 5 is a schematic view showing a third embodiment of the image sensor of the present invention.

Figure 6 is a flow chart showing an operation example of one method of manufacturing an image sensor according to the present invention.

200. . . Image sensor

210. . . Substrate

220. . . Filter

230. . . Microlens

250. . . Incident light

250f. . . Filtered incident light

260. . . Sensing element

270. . . Filling substance

280. . . Air area

Claims (10)

A method for manufacturing an image sensor, comprising: providing a substrate; forming a sensing element on the substrate; forming a microlens on the sensing element; and providing a shielding around the microlens Wherein the mask is made of a metal material, and the height of the mask is not lower than the height of the microlens; filling a filling material on the microlens to form at least one air region in the filling material And forming a filter over the filling material. The manufacturing method of claim 1, wherein the filling the filling material on the microlens comprises: filling a surface of the microlens by a chemical vapor deposition (CVD) process Filling material. The manufacturing method of claim 1, wherein the filling the filling material on the microlens comprises: filling the filling material between the filter and the shielding. The manufacturing method of claim 1, wherein the image sensor adopts a Back Side Illumination (BSI) technology. The manufacturing method of claim 1, wherein the image sensor is a complementary metal oxide semiconductor (CMOS) image sensor. An image sensor includes: a substrate; a sensing element formed on the substrate; a microlens formed on the sensing element; and a mask disposed around the microlens, wherein The mask is made of a metal material, and the height of the mask is not lower than the height of the microlens; a filling material is filled on the microlens, wherein at least one air region is formed in the filling material. And a filter formed on the filling material. The image sensor of claim 6, wherein the filling material is further filled between the filter and the shield. The image sensor of claim 6, wherein the image sensor adopts a back illumination technique. The image sensor of claim 6, wherein the image sensor is a CMOS image sensor. The image sensor of claim 6, wherein the filling material forms a planar layer such that the filter is formed on the filling material.