CN100490163C - Method for manufacturing image sensor element - Google Patents

Abstract

The invention discloses a manufacturing method of an image sensor element, which is suitable for a substrate with at least one welding pad, wherein a plurality of photodiode sensing areas are formed in the substrate, at least one dielectric layer is formed on the substrate, the welding pad is arranged in the dielectric layer, a first protective layer with an opening is arranged on the dielectric layer, and at least part of the surface of the welding pad is exposed in the opening, the method comprises the following steps: forming a second protective layer on the first protective layer and in the opening, forming a color filter film layer on the second protective layer, forming a flat layer on the second protective layer and the color filter film layer, and forming a plurality of micro-lenses on the flat layer. The manufacturing method can keep the surface of the welding pad complete, thereby ensuring that the subsequent wire bonding process can be well carried out.

Description

Method for manufacturing image sensor element

technical field

The present invention relates to a method of manufacturing an image sensor element, and more particularly to a method of manufacturing an image sensor element that avoids pits on the surface of solder pads.

Background technique

Charge Coupled Device (CCD) has a high dynamic range, low dark current, and its technology is mature, so it is the most commonly used solid-state image sensor today. On the other hand, the complementary metal oxide semiconductor image sensor (CMOS Image Sensor, CIS) is compatible with the process of the complementary metal oxide semiconductor transistor, and can be easily integrated on the same chip with other peripheral circuits on the same chip, so The cost and power consumption of the image sensor can be significantly reduced. Therefore, CMOS image sensors have become a substitute for charge-coupled devices in low-cost applications in recent years, and the importance of CMOS transistors has increased day by day.

In the above-mentioned solid-state image sensor elements such as charge-coupled devices and complementary metal-oxide-semiconductor image sensors, welding pads must be provided to electrically connect with external circuits. By setting the welding pads, the external circuit can provide voltage to the The transistor in the image sensor element is used for the operation of the image sensor element, and the electronic signal obtained by the photodiode in the image sensor element after photoelectric conversion must also be output to the external circuit through the soldering pad, so that it can be passed through the appropriate device Convert electronic signals into images.

FIG. 1A to FIG. 1D illustrate a conventional manufacturing method of an image sensor element, and for the sake of simplicity, some components and their corresponding descriptions are omitted in the following processes.

First, please refer to FIG. 1A , a semiconductor silicon substrate 100 is provided, wherein a plurality of photodiode sensing regions 102 are formed in the semiconductor silicon substrate 100 . Furthermore, a dielectric layer 104 with solder pads 106 is disposed on the substrate 100 . Next, a passivation layer 108 having an opening 110 is disposed on the surface of the dielectric layer 104 and the bonding pad 106 , and the surface of the bonding pad 106 is exposed in the opening 110 .

Next, referring to FIG. 1B , a color filter film layer 112 is formed on the protective layer 108 outside the opening 110, wherein these color filter film layers 112 cover different photodiode sensing regions 102, and these The color filter layer 112 has three different colors (red, blue, green).

Next, referring to FIG. 1C, a patterned flat layer 114 is formed on the color filter layer 112 and the protective layer 108, so that the surface of the color filter layer 112 is planarized, and the opening 110 is exposed in the flat layer 114. .

Next, referring to FIG. 1D , the photoresist material is coated on the planar layer 114 , followed by the steps of exposure and development, and the photodiode sensing region 102 and the corresponding color filter film layer 112 are formed above The continuous photoresist pattern is then subjected to a thermal process to form the photoresist pattern into an arc shape to form the microlens 116 . According to the processes of FIGS. 1A to 1D mentioned above, the fabrication of the image sensor element can be completed.

In the process of the above-mentioned image sensor element, since the material of the color filter film layer 112 and the microlens 116 belongs to photoresist material, before forming the color filter film layer 112 and the microlens 116, a protective layer must be defined. Opening 110 is formed at 108 to expose at least a portion of a surface of solder pad 106 . However, in the process of forming the color filter film layer 112 and the microlens 116, the chemical liquids such as photoresist and developer used therein will corrode the surface of the welding pad 106, and then the surface of the welding pad 106 will be eroded. Holes 118 are formed, and the generation of these holes 118 will affect the wire bonding process of the subsequent packaging, such as easy peeling of the wires, or poor electrical properties between the wires and the solder pads.

Contents of the invention

Therefore, the present invention provides a method for manufacturing an image sensor element, which can maintain the integrity of the surface of the welding pad, thereby ensuring that the subsequent wire bonding process can be performed well.

The invention provides a method for manufacturing an image sensor element, which is suitable for a substrate having at least one welding pad, wherein a plurality of photodiode sensing regions are formed in the substrate, and at least one dielectric layer is formed on the substrate , and the welding pad is disposed in the dielectric layer, and a first protection layer with an opening is disposed on the dielectric layer, and at least part of the surface of the welding pad is exposed in the opening, this method is on the first protection layer and the opening Form a second protective layer in the middle, and then form a color filter film layer on the second protective layer, and then form a flat layer on the second protective layer and the color filter film layer, and then form multiple layers on the flat layer a microlens.

The invention provides another method for manufacturing an image sensor element, which is suitable for a substrate having at least one welding pad, wherein a plurality of photodiode sensing regions are formed in the substrate, and at least one dielectric is formed on the substrate. layer, and the solder pads are disposed in the dielectric layer, the method forms a protective layer on the dielectric layer, and then patterns the protective layer to form an opening in the protective layer over at least part of the solder pads, and retains part of the protection in the opening. The layer is not removed to cover at least part of the surface of the soldering pad, and then, a color filter film layer is formed on the protective layer, and then a flat layer is formed on the protective layer and the color filter film layer, and then a plurality of microlenses.

Moreover, in the above-mentioned two methods of manufacturing image sensor elements, it also includes after forming a flat layer on the second protective layer (protective layer) and the color filter film layer, and before forming microlenses on the flat layer, moving Remove the second protective layer (protective layer) on the surface of the solder pad in the opening.

As in the process of the above-mentioned image sensor element, since the surface of the welding pad is formed with a protective layer and is not exposed during the formation of the color filter film layer and the microlens, it can prevent the surface of the welding pad from being covered by the above-mentioned color filter film layer and the microlens. The destruction of the chemical solution used in the microlens process can maintain the integrity of the solder pad surface.

In order to make the above-mentioned purpose, features, and advantages of the present invention more comprehensible, a preferred embodiment will be described in detail below together with the accompanying drawings.

Description of drawings

FIG. 1A to FIG. 1D are schematic cross-sectional diagrams illustrating a manufacturing process of an existing image sensor element;

2A to FIG. 2F are schematic cross-sectional views illustrating a manufacturing process of an image sensor element according to a preferred embodiment of the present invention;

3A to 3F are schematic cross-sectional views illustrating a manufacturing process of an image sensor element according to another preferred embodiment of the present invention.

Explanation of reference signs

100, 200, 300: Substrate

102, 202, 302: photodiode sensing area

104, 204, 304: dielectric layer

106, 206, 306: Solder pads

108, 208, 220, 308, 308a, 308b: protective layer

110, 210, 310: opening

112, 212, 312: color filter film layer

114, 214, 314: flat layer

116, 216, 316: microlenses

Detailed ways

first embodiment

2A to FIG. 2F are schematic cross-sectional schematic diagrams of the manufacturing process of an image sensor element according to a preferred embodiment of the present invention, and for the sake of simplicity and to avoid unnecessary limitations of the present invention, they are omitted in the following processes Some components and their corresponding descriptions.

First, referring to FIG. 2A, a semiconductor silicon substrate 200 is provided, and a plurality of photodiode sensing regions 202 are formed in the semiconductor silicon substrate 200. In zone 202, optical signals can be converted into electrical signals. By arranging a large number of photodiode sensing regions 202 in an array, many pattern units, which are so-called pixels, can be formed on the surface of the substrate 200 .

Next, please continue to refer to FIG. 2A , at least a dielectric layer 204 is formed on the substrate 200 , and at least a solder pad 206 is formed in the dielectric layer 204 . The material of the welding pad 206 here is, for example, aluminum metal, and the welding pad 206 is used to connect with an external circuit, so as to control the image sensor element.

Next, please continue to refer to FIG. 2A , a patterned protective layer 208 is formed on the surface of the dielectric layer 204 and the welding pad 206, and the patterned protective layer 208 has an opening 210, and at least part of the welding pad 206 is exposed in the opening 210. On the surface, the material of the protective layer 208 is, for example, silicon nitride, and its formation method is, for example, chemical vapor deposition (chemical vapor deposition, CVD).

Next, referring to FIG. 2B , a thin protective layer 220 is formed on the substrate 200 to cover the protective layer 208 and the opening 210, wherein the material of the protective layer 220 is, for example, silicon oxide or silicon nitride, forming the protective layer 220 The method is, for example, to form a substantially conformal protective layer 220 in the protective layer 208 and the opening 210 by chemical vapor deposition, and the thickness of the protective layer 220 can be between 250 angstroms and 500 angstroms, for example.

Next, referring to FIG. 2C, a color filter layer 212 is formed on the protective layer 220 outside the opening 210, wherein the color filter layer 212 has three different colors (red, blue, green), for example, and respectively cover different photodiode sensing regions 202 . The method for forming the color filter film layer 212 is, for example, to form a color filter film layer of the first color (for example, red) by existing means, and the color filter film layer of the first color is, for example, made of red Pigment is formed, then, forms the color filter film layer (for example is blue) of the second color by existing means, and the color filter film layer of this second color is formed by blue pigment for example, its Finally, a third color filter film layer (for example, green) is formed by existing means, and the third color filter film layer is formed of green pigment, for example.

Next, referring to FIG. 2D, a patterned flat layer 214 is formed on the color filter layer 212 and the protective layer 220, so that the surface of the color filter layer 212 is planarized, and the opening 210 is exposed in the flat layer 214. And the protective layer 220 formed in the opening 210, wherein the material of the flat layer 214 is a transparent material, which can be formed of a transparent polymer material, for example.

During the process of forming the color filter film layer 212 and the flat layer 214, the protective layer 220 is formed on the surface of the welding pad 206, that is, the surface of the welding pad 206 is not exposed, so the welding pad 206 can be protected. The surface is not eroded by chemical liquids such as photoresist and developer used to form the color filter layer 212 and the flat layer 214 .

Next, referring to FIG. 2E , the protection layer 220 in the opening 210 is removed to expose the surface of the solder pad 206 , wherein the removal method of the protection layer 220 is, for example, a dry etching method. It is worth noting here that since the step of removing the protection layer 220 is performed after the flat layer 214 is formed, it is possible to avoid damaging the integrity of the color filter film layer 212 by this removal method.

Moreover, the material of the above-mentioned protection layer 220 is preferably easily removed by the removal method used in this step, so as to reduce or avoid the damage caused by this removal method to the color filter film layer 212 or the flat layer 214. damage.

In addition, since in the step of FIG. 2B , the thickness of the protective layer 220 formed is very thin, which also helps to make the protective layer 220 easier to be removed, and can also reduce or avoid damage to the protective layer 220 when removing it. Damage caused by the color filter layer 212 or the planarization layer 214 .

Next, referring to FIG. 2F, a plurality of microlenses 216 (micro lenses) are formed on the flat layer 214, and these microlenses 216 correspond to different color filter film layers 212 respectively, and these microlenses 216 can focus the incident light of the image The photodiode sensing area 202 is projected onto the surface of the image sensor element. The material of these microlenses 216 is, for example, a photoresist material with high light transmittance, generally a positive photoresist, and the method of its formation is, for example, coating the above-mentioned photoresist material on the flat layer At 214, the steps of exposure and development are then performed to form a discontinuous photoresist pattern above each single pixel (that is, the photodiode sensing region 202), and then heat treatment is performed to pattern the photoresist arc-shaped to form a microlens 216 with lens focusing function. The fabrication of the image sensor element can be completed through the above-mentioned process in FIG. 2A to FIG. 2F .

second embodiment

3A to FIG. 3F are schematic cross-sectional diagrams illustrating a manufacturing process of an image sensor element according to another preferred embodiment of the present invention. Similarly, for the sake of simplicity and to avoid unnecessary limitations of the present invention, the following Some components and their corresponding descriptions are omitted in the process. .

First, referring to FIG. 3A, a semiconductor silicon substrate 300 is provided, and a plurality of photodiode sensing regions 302 are formed in the semiconductor silicon substrate 300. In zone 302, optical signals can be converted into electrical signals.

Next, please continue to refer to FIG. 3A , at least a dielectric layer 304 is formed on the substrate 300 , and at least a solder pad 306 is formed in the dielectric layer 304 . Then, a protection layer 308 is formed on the surfaces of the dielectric layer 304 and the welding pad 306 , wherein the material of the protection layer 308 is formed by silicon nitride, and the formation method is, for example, chemical vapor deposition.

Next, please refer to FIG. 3B, pattern the protective layer 308 to form a protective layer 308b with an opening 310, wherein the opening 310 is located above at least part of the solder pad 306, and has a thin protective layer 308a in the opening 310 to cover at least part of the soldering Pad 306 surface. The method for forming the protective layer 308b with the opening 310 above is, for example, forming a patterned photoresist layer (not shown) with the opening 310 on the protective layer 308 to expose the protective layer above the welding pad 306 308, and then remove the protective layer 308 in the part not covered by the photoresist layer by dry etching to form the opening 310, and in the process of removing part of the protective layer 308, the protective layer 308 in the opening 310 is not completely removed to form a protection layer 308 a covering at least part of the surface of the solder pad 306 .

Next, referring to FIG. 3C, a color filter layer 312 is formed on the protective layer 308b outside the opening 310, wherein the color filter layer 312 has three different colors (red, blue, green), for example, and respectively cover different photodiode sensing regions 302 . The method for forming the color filter layer 312 is, for example, to form a color filter layer of the first color (for example, red) by existing means, and the color filter layer of the first color is, for example, made of red Pigment is formed, then, forms the color filter film layer (for example is blue) of the second color by existing means, and the color filter film layer of this second color is formed by blue pigment for example, its Finally, a third color filter film layer (for example, green) is formed by existing means, and the third color filter film layer is formed of green pigment, for example.

Next, referring to FIG. 3D, a patterned flat layer 314 is formed on the color filter layer 312 and the protective layer 308b, so that the surface of the color filter layer 312 is planarized, and the opening 310 is exposed in the flat layer 314. And the protection layer 308 a in the opening 310 , wherein the material of the flat layer 314 is a transparent material, which can be formed of a transparent polymer material, for example.

Because during the process of forming the color filter film layer 312 and the flat layer 314, the protective layer 308a is formed on the surface of the welding pad 306, that is, the surface of the welding pad 306 is not exposed, so the surface of the welding pad 306 can be protected. It is not eroded by chemical liquids such as photoresist and developer used to form the color filter layer 312 and the flat layer 314 .

Next, referring to FIG. 3E , the protective layer 308 a in the opening 310 is removed to expose the surface of the solder pad 306 , wherein the method of removing the protective layer 308 a is, for example, dry etching. Likewise, since the step of removing the protection layer 308 a is performed after the flat layer 314 is formed, it can avoid the removal method from damaging the integrity of the color filter film layer 312 .

Moreover, the material of the protective layer 308a is preferably easily removed by the removal method used in this step, so as to reduce or avoid damage to the color filter film layer 312 or the flat layer 314 caused by this removal method. damage.

In addition, since in the step of FIG. 3B , the thickness of the protective layer 308a formed above the solder pad 306 is very thin, it also helps to make the protective layer 308a easier to be removed, and can also reduce or avoid the removal process. The protection layer 308a is the damage caused to the color filter film layer 312 or the flat layer 314 .

Next, referring to FIG. 3F , a plurality of microlenses 316 (micro lenses) are formed on the flat layer 314, and these microlenses 316 correspond to different color filter film layers 312 respectively, so that the incident light of the image can be focused and projected onto the image. Photodiode sensing region 302 on the surface of the sensor element. The material of these microlenses 316 is, for example, a photoresist material with high light transmittance, generally a positive photoresist, and the method of its formation is, for example, coating the above-mentioned photoresist material on the flat layer 314, and then carry out the step of exposure and development, and form a discontinuous photoresist pattern above each single pixel (that is, refer to the photodiode sensing area 302), and then perform heat treatment to pattern the photoresist into Arc-shaped to form a microlens 316 with lens focusing function. The fabrication of the image sensor element can be completed through the above-mentioned processes in FIG. 3A to FIG. 3F .

Moreover, in the above-mentioned first embodiment and second embodiment, the removal of the protective layer 220 (308a) is performed after the definition of the flat layer 214 (314) and before the formation of the microlens 216 (316), so as to reduce or avoid this problem. The removal of the protective layer 220 (308a) causes damage to the color filter film layer 212 (312) or the flat layer 214 (314). However, the present invention is not limited thereto. The removal timing of the protective layer 220 (308a) in the above embodiments of the present invention can also be after the microlens 216 (316) is defined, preferably after forming the photoresist pattern Afterwards, heat treatment is carried out, so that the surface of the welding pad can be further prevented from being corroded by the photoresist and developer used to form the microlens 216 (316), and the removal of the protective layer 220 (308a) can also be reduced or avoided. Damage to microlens 216 (316).

In summary, in the process of the image sensor element of the present invention, since a thin protective layer is formed on the surface of the welding pad during the formation of the color filter film layer and the microlens, the surface of the welding pad can be prevented from being covered by the above-mentioned color. The chemical solution used in the filter film layer and the microlens process is destroyed, thereby maintaining the integrity of the surface of the soldering pad, and further enabling the subsequent wire bonding process to be performed correctly and well.

Moreover, since the process of removing the protective layer on the surface of the welding pad can be performed after the definition of the flat layer is completed, it is possible to avoid damaging the integrity of the color filter layer when removing the protective layer.

In addition, since the process of removing the protective layer on the surface of the welding pad can be performed after the definition of the microlens is completed, preferably after forming the photoresist pattern and before the heat treatment, it can further prevent the surface of the welding pad from being formed. The photoresist used in the microlens and the erosion of the developer can also reduce or avoid the damage to the microlens caused by the removal of the protection layer.

Moreover, since the protective layer formed on the welding pad is very thin, it is easier to remove, thereby reducing or avoiding damage to the color filter layer, the planar layer or the micro-lens when removing the protective layer.

Although the present invention has been disclosed above in conjunction with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make various modifications and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall prevail as defined by the appended claims.

Claims (7)

1. the manufacture method of an image sensor element, be applicable to a substrate with at least one welded gasket, wherein in this substrate, be formed with a plurality of photo sensitive diode sensitive areas, and on this substrate, be formed with a dielectric layer at least, and this welded gasket is arranged in this dielectric layer, and this manufacture method comprises the following steps:

On this dielectric layer, form a protective layer;

This protective layer of composition, with formation one opening in this protective layer above this welded gasket of small part, and this protective layer of reserve part is not removed in this opening, to cover to this welded gasket surface of small part;

On the protective layer outside this opening, form a colored light filter membrane layer;

Form a flatness layer on this protective layer and this colored light filter membrane layer, this flatness layer exposes this protective layer in this opening and this opening; And

On this flatness layer, form a plurality of lenticules.

2. the manufacture method of image sensor element as claimed in claim 1; wherein also be included in and form after this flatness layer on this protective layer and this colored light filter membrane layer; and before forming those lenticules on this flatness layer, remove this protective layer that keeps in this opening.

3. the manufacture method of image sensor element as claimed in claim 2, the method that wherein removes this protective layer that keeps in this opening comprises the dry-etching method.

4. the manufacture method of image sensor element as claimed in claim 1 wherein forms those lenticular methods and comprises the following steps:

On this flatness layer, form a microlens material layer;

This microlens material layer of composition is to form a plurality of microlens pattern; And

Those microlens pattern are carried out a heat treatment to form those lenticules.

5. the manufacture method of image sensor element as claimed in claim 4 wherein also is included in this microlens material layer of composition forming after those microlens pattern, and this microlens pattern is carried out removing this protective layer that keeps in this opening before this heat treatment.

6. the manufacture method of image sensor element as claimed in claim 5, the method that wherein removes this protective layer that keeps in this opening comprises the dry-etching method.

7. the manufacture method of image sensor element as claimed in claim 1, wherein the material of this protective layer comprises silicon nitride.

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