Image sensor and method for manufacturing the same

An image sensor and method of manufacturing thereof are provided. In an embodiment, an image sensor can include a photodiode on a substrate, an interlayer dielectric formed on the substrate, an insulating layer micro-lens on the interlayer dielectric, and an organic micro-lens on the insulating layer micro-lens.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit under 35 U.S.C. §119 of Korean Patent Application No. 10-2006-0131353, filed Dec. 20, 2006, which is hereby incorporated by reference in its entirety.

BACKGROUND

In an image sensor, to improve photo sensitivity, either a fill factor, which is a ratio of a photodiode area to the whole area of the image sensor, is increased, or a photo-gathering technology is used to change the path of light incident onto an area other than the photodiode area such that the light can be collected in the photodiode.

When a manufacturing process of an image sensor has been completed, the image sensor is subject to a packaging process, and an external lens is attached to the image sensor.

However, according to the related art as illustrated inFIG. 1, although the image sensor does not have a problem in forming images at the center of the image sensor chip using light incident from an external lens3, the amount of light introduced into a photodiode2by passing through a micro-lens1is gradually decreased from the center of the image sensor chip to an edge (A) of the image sensor chip.

Accordingly, as the amount of light incident onto a unit pixel is changed, the number of generated electrons changes, so that a color image formed at the center of the image sensor is different from a color image formed at the edge of the image sensor even if the color of an the original image is not changed.

Such a phenomenon, together with crosstalk to adjacent pixels, lowers reliability of the image sensor, so that light efficiency is lowered.

BRIEF SUMMARY

Embodiments of the present invention can provide an image sensor and a method of manufacturing the same, capable of reducing a focal difference of light between the center portion and the edge portion of the image sensor chip.

An image sensor according to an embodiment comprises a photodiode on a substrate, an interlayer dielectric on the substrate, a first type layer micro-lens on the interlayer dielectric and a second type layer micro-lens on the first type layer micro-lens. The first type layer can be a material having a refraction index of 1.4 or above in 633 nm wavelength. The second type layer can be an organic material.

In addition, a method of manufacturing an image sensor according to an embodiment comprises forming a photodiode on a substrate, forming an interlayer dielectric on the substrate, forming a first material layer on the interlayer dielectric, forming a first material layer micro-lens by etching the first material layer and forming a second material layer micro-lens on the first material layer micro-lens.

DETAILED DESCRIPTION

Hereinafter, an image sensor and a method of manufacturing the same according to embodiments of the present invention will be described with reference to the accompanying drawings

In the disclosure, the expression ‘formed on/under layer’ includes the cases directly formed on/under layer or indirectly formed by interposing other layer(s) therebetween.

FIG. 2is a cross-sectional view of an image sensor according to an embodiment.

An image sensor according to an embodiment can include a photodiode12formed on a substrate10and at least one interlayer dielectric layer formed on the substrate10(for example,20and30ofFIG. 2). A first type micro-lens62can be formed on the substrate and a second type micro-lens72can be formed on the first type micro-lens62. The first type micro-lens62can be formed of a highly reflective material, and the second type micro-lens72can be formed of a conventional microlens material. For example, the first type micro-lens62can be an insulating layer micro-lens formed on the substrate, and the second type micro-lens72can be a first organic micro-lens formed on the insulating layer micro-lens62.

In the image sensor according to an embodiment, the insulating layer micro-lens having a high refractive index can be formed at an edge portion of the pixel so as to prevent light mismatch between the edge portion and the center portion of the pixel, thereby improving light efficiency and preventing crosstalk an adjacent pixel.

For example, an insulating layer micro-lens62can be formed at the edge portion of the image sensor chip. The edge portion is a portion of the upper surface of an image sensor around a center portion. For example, the center portion of the image sensor can correspond to 4% of an entire upper surface of the image sensor, and the remaining area of the image sensor can be defined as the edge portion, but embodiments are not limited thereto.

In addition, according to the embodiment, the insulating layer micro-lens62includes an insulating layer having a high refractive index. In one embodiment, the insulating layer micro-lens62can be formed using an insulating layer having a refractive index (RI) of 1.4 or above in 633 nm of wavelength. However, other materials having a high refractive index and that are transparent can be used.

The insulating layer micro-lens62can include an oxide layer micro-lens.

In an embodiment, the insulating layer micro-lens62and the first organic micro-lens72can have hydrophobic characteristics, so that they can be easily bonded to each other while forming the lens configuration.

In a further embodiment, a second organic micro-lens72acan be formed at the center portion of the image sensor chip.

Other reference numerals not described above will be explained with reference to a method of manufacturing an image sensor as described below.

Hereinafter, a method of manufacturing the image sensor according to an embodiment will be described with reference toFIGS. 3 to 8.

Referring toFIG. 3, a photodiode12can be formed on the substrate10.

In addition, according to an embodiment, a gate electrode11, interconnections, and interlayer dielectric layers can be formed.

For example, referring toFIG. 3, a first interlayer dielectric20and a first interconnection21can beformed. After that, a second interlayer dielectric30and a second interconnection31can be formed on the first interlayer dielectric20.

Then, referring toFIG. 4, a passivation layer40can be formed on the second interlayer dielectric30. The passivation layer40can include a PE-TEOS layer41and a PE-Nitride layer42. The PE-TEOS layer41can be deposited on the second interlayer dielectric30, and then a PE-Nitride layer42can be deposited on the PE-TEOS41, thereby forming the passivation layer40.

After that, a color filter51can be formed on the passivation layer40and a planarization layer50including organic material can be formed on the passivation layer40. The planarization layer50can have a thickness of 1000 Å to 10,000 Å. Then, an insulating layer60can be formed on the planarization layer50. The insulating layer60can include a nitride layer or an oxygen layer, but the insulating layer60is not limited thereto.

In an embodiment, the insulating layer60can be a low temperature nitride layer60having a thickness of 1000 Å to 10,000 Å formed on the planarization layer50at a temperature of 200° C. or below. The insulating layer60can be used to form an insulating layer micro-lens.

In an image sensor according to an embodiment, an insulating layer micro-lens having a high refractive index can be formed at the edge portion of the pixel so as to prevent light mismatch between the edge portion and the center portion of the pixel, thereby improving light efficiency. For instance, the insulating layer micro-lens can include an insulating layer60having a refractive index (RI) of 1.4 or above in 633 nm of wavelength.

Referring toFIG. 5, a first photoresist pattern (not shown) can be formed on the insulating layer60. Then, a second photoresist pattern70in the form of a lens shape can be formed by reflowing the first photoresist pattern.

Then, as shown inFIG. 6, the insulating layer60can be etched by using the second photoresist pattern70as a mask to form an insulating layer micro-lens62.

In an embodiment, the insulating layer micro-lens62can be formed by a dry-etching of the insulating layer60. At this time, the insulating layer60can be etched using at least one gas selected from an etching gas based on CXHYFZ(X, Y, and Z are 0 and natural numbers). The etching can optionally include an inert gas such as Argon (Ar), Helium (He), Oxygen (O2) and Nitrogen (N2) with the etching gas.

The insulating layer micro-lens62can be formed at the edge portion of the image sensor chip. For example, in a case where the center portion of the image sensor corresponds to 4% of an entire upper surface area of the image sensor, the insulating layer micro-lens62can be formed at the remaining area of the image sensor, that is, the edge portion.

Accordingly, an insulating layer micro-lens62can be formed at the edge portion of the image sensor chip. Although the insulating layer micro-lens62is described as being formed at the edge portion of the image sensor chip, embodiments are not limited thereto. That is, the insulating layer micro-lens62can be formed on the entire surface of the image sensor chip.

Referring toFIG. 7, a third photoresist layer71can be formed on the insulating layer micro-lens62.

According to an embodiment, a fourth photoresist pattern71acan be further formed on the center portion of the image sensor chip while the third photoresist pattern71is being formed on the insulating layer micro-lens62.

After that, as shown inFIG. 8, a first organic micro-lens72can be formed on the insulating layer micro-lens62by reflowing the third photoresist pattern71.

In addition, a second organic micro-lens72acan be formed by reflowing the fourth photoresist pattern71aformed at the center portion of the image sensor chip, which is performed simultaneously with the step of forming the first organic micro-lens72on the insulating layer micro-lens62.

In this case, according to an embodiment, the insulating layer micro-lens62and the first organic micro-lens72can have hydrophobic characteristics, so they can be easily bonded to each other to form the lens configuration.

According to an embodiment, an insulating layer lens having a high refractive index (RI) can be formed at the edge portion of the pixel to prevent light mismatch between the edge portion and the center portion of the pixel, thereby improving light efficiency.

In addition, according to an embodiment, an insulating lens having a high refractive index (RI) can be formed at the edge portion of the pixel, thereby inhibiting cross talk to the adjacent pixel.