KR20040000877A - Cmos type image sensor with positive and negative micro-lenses and method for manufacturing same - Google Patents

Abstract

PURPOSE: A CMOS(Complementary Metal Oxide Semiconductor) image sensor having a concave and convex type microlens and a manufacturing method thereof are provided to be capable of improving concentration efficiency and preventing the malfunction of a photosensitive device. CONSTITUTION: A CMOS image sensor is provided with a semiconductor substrate, a photosensitive device(102) and an interlayer dielectric(104) sequentially deposited on the semiconductor substrate, and a light shielding layer(106) and a device protecting layer(110) sequentially formed at the upper portion of the interlayer dielectric. The CMOS image sensor further includes a color filter array and a flat layer(116) formed at the upper portion of the device protecting layer, a concave type microlens(117) formed at the upper portion of the flat layer opposite to the color filter array, and a convex type microlens(118a) connected with the concave type microlens.

Description

CMOS image sensor with concave and convex microlenses and method for manufacturing the same {CMOS TYPE IMAGE SENSOR WITH POSITIVE AND NEGATIVE MICRO-LENSES AND METHOD FOR MANUFACTURING SAME}

The present invention relates to a CMOS image sensor and a method of manufacturing the same, and more particularly to a CMOS image sensor having a concave and convex microlenses that can increase the light condensing efficiency of the lens.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal. In a double charge coupled device (CCD), individual metal-oxide-silicon (MOS) capacitors are very different from each other. A device in which a charge carrier is stored and transported in a capacitor while being in close proximity. Moreover, CMOS (Complementary MOS) image sensors use CMOS technology that uses a control circuit and a signal processing circuit as peripheral circuits to make MOS transistors as many as the number of pixels. It is a device that employs a switching method that detects an output in turn.

In manufacturing such various image sensors, efforts are being made to increase the photo sensitivity of the image sensor. For example, the CMOS image sensor is composed of a light sensing unit for detecting light, and a CMOS logic circuit unit for processing the detected light into an electrical signal and converting the data into data. Efforts have been made to increase the ratio of the area of the photodetector to the total image sensor area (commonly referred to as the fill factor) in order to increase the light sensitivity. There is a limit. Therefore, in order to increase the light sensitivity, a lot of research has focused on the condensing technology to collect the light by changing the path of light incident to the area other than the light sensing unit.

In the current technology, a method of transmitting a larger amount of light to a light sensing unit by refracting a path of incident light by making a convex microlens with a material having a high light transmittance on the light sensing unit is used. In this case, light parallel to the optical axis of the microlens is refracted by the microlens to form a focal point at a predetermined position on the optical axis.

1 is a vertical sectional view showing an image sensor having a microlens according to the prior art, in which only the main part of a CMOS image sensor related to condensation is shown.

Referring to FIG. 1, a conventional CMOS image sensor includes at least one photosensitive device 102, a field insulating film 100, a field insulating film 100, and a photosensitive device 102 on a semiconductor substrate (not shown). Interlayer insulating films 104 and 108 for interlayer insulating the upper portion, and a light shield layer 106 in the interlayer insulating film 108 to prevent light from entering the region 100 other than the photosensitive device. The device protection layer 110 is formed on the interlayer insulating layer 108, and the red, green, and blue color filters 112a, 112b, are disposed on the device protection layer 110. 112c are arrayed, and a flat layer 116 is formed on these color filter arrays 112a, 112b, and 112c, and convex microlenses 118 are formed at opposite positions of the color filters 112a, 112b, and 112c, respectively. It is. Unexplained reference numeral 114 denotes an interlayer insulating film.

Here, the photosensitive device 102 is formed of a photogate, a photodiode, or the like. The light shielding film 106 is formed of a metal layer. As the material of the color filters 112a, 112b, and 112c, photoresist dyed with a color capable of absorbing only light of a specific wavelength is mainly used. As a material of the microlens 118, a polymer resin is used. Is mainly used.

In addition, the interlayer insulating films 104, 108, 114, and the device protection layer 110 are transparent materials, and a silicon oxide film is generally used, and the flat layer 116 uses a photoresist to compensate for roughness of the color filter.

The incident light is filtered through the red lens 112a, the green color filter 112b, and the blue color filter 112c through the microlens 118 to filter the corresponding red light, green light, and blue light. The light is incident on the photosensitive device 102 positioned at the bottom of each color filter through the device protection film 110 and the interlayer insulating films 108 and 104. In this case, the light shielding layer 106 serves to prevent the incident light from escaping to another path.

The microlens 118 of the related art configured as described above has the configuration of each photosensitive device 102, that is, the size and position, the shape of the unit pixel, the thickness of the photosensitive device 102, and the light shielding film 106. It should be formed with the optimum size, thickness and radius of curvature determined by height, position, size, etc.

On the other hand, in the CMOS image sensor of the prior art, the method of forming the convex microlenses 118 is made by forming a flat layer 116, forming a resist pattern for microlens, flowing a resist by heat treatment, and then baking and curing. The method to make it is used. In the case of the hemispherical convex microlens 118, light parallel to the optical axis is refracted by the lens and reaches a specific light sensing element 102 at the opposite position of the lens to operate the device normally, but light not parallel to the optical axis is When the light is refracted by and reaches the light sensing element 102 of the path that light should not reach, the device may malfunction.

In addition, in the case of the hemispherical convex microlens 118, the position where the focus of the light is formed is constant, but the amount of light reaching the photosensitive device 102 is generated according to the type and thickness of the lower film quality, so that the light condensing efficiency decreases. There is a problem in that it interferes with the smooth operation of the image sensor device and shows a bad image.

An object of the present invention is to provide a convex microlens and a concave microlens having a convex shape of the top and bottom of the lens in order to solve the problems of the prior art as described above to increase the light collection efficiency and perpendicular to the light sensing element The present invention provides a CMOS image sensor having concave and convex microlenses that can incident light to prevent malfunction of the photosensitive device.

Another object of the present invention is to increase the condensing efficiency by making the lens shape convex microlens and concave microlens of the upper and lower parts, and incident light to the photosensitive device perpendicularly to prevent the malfunction of the photosensitive device. The present invention provides a method for manufacturing a CMOS image sensor having concave and convex microlenses that can be prevented.

In order to achieve the above object, the present invention provides a CMOS image sensor, at least one or more photosensitive devices and an interlayer insulating film sequentially stacked on a semiconductor substrate, a light shielding film and a device protective film sequentially stacked on the interlayer insulating film, A concave microlens consisting of a color filter array and a flat layer sequentially stacked on the passivation layer, a hemispherical groove opposing the color filter on the flat layer, and both a top and a bottom of the lens convex in the concave microlens groove. It has a convex microlens formed to have a.

In accordance with another aspect of the present invention, there is provided a method of manufacturing a CMOS image sensor, the method comprising: sequentially forming at least one photosensitive device and an interlayer insulating film interlayer insulating thereon on a semiconductor substrate; Sequentially forming a light shielding film and a device protection film on the substrate; sequentially forming a color filter array and a flat layer on the device protection film; and forming a hemispherical groove on the flat layer opposite the color filter. And forming a convex microlens such that both the top and the bottom of the lens are convex in the groove of the concave microlens.

1 is a vertical cross-sectional view showing a CMOS image sensor having a microlens according to the prior art,

2 is a vertical sectional view showing a CMOS image sensor having concave and convex microlenses according to the present invention;

3A to 3F are process flowcharts sequentially illustrating a manufacturing process of CMOS image sensors having concave and convex microlenses according to the present invention;

4A and 4B are views showing light refraction states in convex microlenses and concave microlenses;

5 is a view showing a state of light refraction in the microlens of the CMOS image sensor according to the present invention.

<Description of the code | symbol about the principal part of drawing>

100 field insulating film 102 photosensitive device

104, 108, 114: interlayer insulating film 106: light shielding film

110: element protection film 112a, 112b, 112c: color filter

116: flat layer 117: concave microlens

118: convex microlens 120: light

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2 is a vertical cross-sectional view showing a CMOS image sensor having concave and convex microlenses according to the present invention.

Referring to FIG. 2, the CMOS image sensor according to the present invention may include at least one photosensitive device 102, a field insulating film 100, and a field insulating film on a semiconductor substrate (not shown). The interlayer insulating films 104 and 108 which insulate the upper portion of the photosensitive element 100 and the photosensitive device 102 and the light shielding film in the interlayer insulating film 108 to prevent light from entering the region 100 other than the photosensitive device. a light shield layer 106 is formed, an element protection layer 110 is formed on the interlayer insulating layer 108, and red, green, and blue are formed on the element protection layer 110. Color filters 112a, 112b, and 112c are arrayed, and on the color filter arrays 112a, 112b, and 112c, hemispherical grooves are disposed on the flat layer 116 in a position opposite to the color filters 112a, 112b, and 112c. The top and bottom of the lens in the concave microlens 117 and the groove of the concave microlens 117 All have convex microlenses 118a having convex shapes. Unexplained reference numeral 114 is an interlayer insulating film.

Here, the photosensitive device 102 is formed of a photogate, a photodiode, or the like. The light shielding film 106 is formed of a metal layer. As the material of the color filters 112a, 112b, and 112c, photoresist dyed with a color capable of absorbing only light of a specific wavelength is mainly used.

In addition, the interlayer insulating films 104, 108, 114, and the device protection layer 110 are transparent materials, and a silicon oxide film is generally used, and the flat layer 116 uses a photoresist to compensate for roughness of the color filter.

At this time, the concave microlens 117 is made of a low temperature oxide film, and the convex microlens 118a is made of a photoresist.

According to the CMOS image sensor of the present invention configured as described above, light is incident on the convex and concave microlenses 118a and 117 and the incident light is applied to each of the red color filter 112a, the green color filter 112b, and the blue color. The filter 112c filters the corresponding red light, green light, and blue light, and passes the filtered light to the photosensitive device 102 located at the bottom of each color filter through the device protection layer 110 and the interlayer insulating films 108 and 104. Let it enter. In this case, the light shielding layer 106 serves to prevent the incident light from escaping to another path.

Detailed descriptions of the process of injecting the convex and concave microlenses 118a and 117 through the CMOS image sensor according to the present invention will be made later with reference to FIGS. 4A, 4B and 5.

3A to 3F are process flowcharts sequentially illustrating a manufacturing process of CMOS image sensors having concave and convex microlenses according to the present invention.

First, as illustrated in FIG. 3A, a field insulating film 100 is formed on a semiconductor substrate (not shown) for electrical insulation between unit pixels of an image sensor, and at least one photosensitive device is disposed between the field insulating films 100. 102 is formed and the light shielding film 106 pattern is formed after depositing the interlayer insulating film 104 over the resultant. The light shielding layer 106 pattern may be made of a single layer metal pattern or a multilayer metal pattern.

Then, after the interlayer insulating film 108 is deposited on the resultant pattern of the light shielding film 106, a planarized device protection film 110 is formed thereon to protect the device from moisture or scratches.

Subsequently, a dyed photoresist is applied and developed on the device passivation layer 110 to arrange the red, green, and blue color filters 112a, 112b, and 112c, and then the planarization layer 116 for planarization and focal length control thereon. To form.

As shown in FIG. 3B, a low temperature oxide film 117a is deposited on the flat layer 116 for the concave microlens.

Subsequently, as shown in FIG. 3C, a photoresist pattern 119 is formed on the low temperature oxide film 117a to define the microlens region.

As shown in FIG. 3D, the low temperature oxide film 117a exposed by the photoresist pattern 119 is selectively wet etched to hemisphere groove 112 at a position opposite to the color filters 112a, 112b and 112c. ) To form a concave microlens 117 having a shape.

Next, as shown in FIG. 3E, the photoresist pattern 119 is removed.

3F, a photoresist pattern is formed on the structure in which the concave microlens 117 is formed, and the lens is formed in a hemispherical groove of the concave microlens 117 by high temperature baking. Both upper and lower portions of the convex microlens 118a have a convex shape.

4A and 4B are diagrams showing light refraction states of convex microlenses and concave microlenses.

Referring to FIG. 4A, in the convex microlens 118, light 120 incident in parallel with the optical axis passes through the lens and bends inward to collect at a point (focus). In addition, the light 120 incident by refraction that is not parallel to the optical axis has a characteristic that the light 120 continues to travel in the direction of travel through the convex microlens 118.

Referring to FIG. 4B, in the concave microlens 117, light 120 incident to the optical axis in parallel or in refraction may travel in a straight straight direction through the lens.

5 is a view showing a state of light refraction in the microlens of the CMOS image sensor according to the present invention.

Referring to FIG. 5, since the CMOS image sensor of the present invention adopts the convex microlens 118 of FIG. 4A and the concave microlens 117 of FIG. 4B, all the light parallel or not parallel to the optical axis is convex. The light is bent inwardly through the microlens 118a and the light is advanced in parallel through the concave microlens 117 to pass through the color filters 112a, 112b and 112c positioned below the photosensitive device 102 thereunder. Until it reaches vertically.

As described above, the present invention provides and manufactures a convex micro lens and a concave micro lens having convex shapes of the upper and lower parts of the lens so that light is incident perpendicularly to the photosensitive device, thereby preventing malfunction of the photosensitive device. There is an effect that can be prevented. That is, the present invention is a case in which the light that is not parallel to the optical axis generated when using a conventional hemispherical convex microlens is refracted by the lens to reach the light sensing element of the path that should not reach the light, so that the device malfunctions. You can prevent it.

In addition, the present invention has the effect of increasing the condensing efficiency of the microlens by bending the light inward through the convex microlens and directing the light in the straight direction through the concave microlens.

On the other hand, the present invention is not limited to the above-described embodiment, various modifications are possible by those skilled in the art within the spirit and scope of the present invention described in the claims to be described later.

Claims (6)

CMOS image sensor, At least one photosensitive device and an interlayer insulating film sequentially stacked on the semiconductor substrate; A light shielding film and a device protection film sequentially stacked on the interlayer insulating film; A color filter array and a flat layer sequentially stacked on the device passivation layer; A concave microlens formed of a hemispherical groove opposing the color filter on the flat layer; And CMOS image sensor having a concave and convex micro-lens, characterized in that the concave and convex micro-lens is provided in the groove of the concave micro-lens to have a convex shape of both the top and bottom of the lens. The method of claim 1, wherein the concave microlens, CMOS image sensor having a concave and convex micro-lens, characterized in that the low-temperature oxide film. The method of claim 1, wherein the convex microlenses, CMOS image sensor having a concave and convex micro-lens, characterized in that made of the photoresist. In the method of manufacturing the CMOS image sensor, Sequentially forming at least one photosensitive device on the semiconductor substrate and an interlayer insulating film interlayer insulating thereon; Sequentially forming a light shielding film and a device protection film on the interlayer insulating film; Sequentially forming a color filter array and a flat layer on the device passivation layer; Forming a concave microlens by forming a hemispherical groove opposing the color filter on the flat layer; And And forming a convex microlens in the groove of the concave microlens such that both the top and the bottom of the lens have a convex shape. The method of claim 4, wherein the forming of the concave microlens comprises: A method of manufacturing a CMOS image sensor having concave and convex microlenses, wherein a low-temperature oxide film is deposited on the flat layer and selectively wet-etched to form a hemispherical groove of a low-temperature oxide film pattern facing the color filter. The method of claim 4, wherein the forming of the convex microlenses comprises: And forming a photoresist pattern on the structure on which the concave microlens is formed and performing a high temperature bake process after the flow of the photoresist pattern.