KR101053718B1 - Image sensor and its manufacturing method - Google Patents

Abstract

Embodiments relate to an image sensor of a new structure. The image sensor according to the embodiment may include a transparent substrate having a pixel region and a logic region formed thereon, a first metal interconnection layer formed on the transparent substrate, an organic transistor formed on the first metal interconnection layer of the logic region, and stacked on the pixel region. And a first color filter, a first photodiode, a second photodiode and a second color filter, an insulating film covering the second color filter and the organic transistor, and a second metal wiring layer formed on the insulating film.

Bidirectional Image Sensor, Organic Transistor

Description

Image sensor and fabrication method thereof

Embodiments relate to an image sensor and a manufacturing method.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal, and is generally a charge coupled device (CCD) and CMOS metal (Complementary Metal Oxide Silicon) image. It is divided into Image Sensor.

In the charge coupled device (CCD), a plurality of photo diodes (PDs) for converting a signal of light into an electrical signal are arranged in a matrix form, and the photo diodes in each vertical direction arranged in the matrix form. A plurality of vertical charge coupled device (VCCD) formed between the plurality of vertical charge coupled devices (VCCD) for vertically transferring charges generated in each photodiode, and horizontally transferring charges transferred by the respective vertical charge transfer regions; A horizontal charge coupled device (HCCD) for transmitting to the sensor and a sense amplifier (Sense Amplifier) for outputting an electrical signal by sensing the charge transmitted in the horizontal direction.

However, such a CCD has a disadvantage in that the manufacturing method is complicated because the driving method is complicated, the power consumption is large, and the multi-step photo process is required.

In addition, the charge coupling device has a disadvantage in that it is difficult to integrate a control circuit, a signal processing circuit, an analog / digital converter (A / D converter), and the like into a charge coupling device chip, which makes it difficult to miniaturize a product.

Recently, CMOS image sensors have attracted attention as next generation image sensors for overcoming the disadvantages of the charge coupled device.

The CMOS image sensor uses CMOS technology that uses a control circuit, a signal processing circuit, and the like as peripheral circuits to form MOS transistors corresponding to the number of unit pixels on a semiconductor substrate, thereby forming the MOS transistors of each unit pixel. The device adopts a switching method that sequentially detects output.

That is, the CMOS image sensor implements an image by sequentially detecting an electrical signal of each unit pixel by a switching method by forming a photodiode and a MOS transistor in the unit pixel.

The CMOS image sensor has advantages, such as a low power consumption, a simple manufacturing process according to a few photoprocess steps, by using CMOS manufacturing technology.

In addition, since the CMOS image sensor can integrate a control circuit, a signal processing circuit, an analog / digital conversion circuit, and the like into the CMOS image sensor chip, the CMOS image sensor has an advantage of easy miniaturization.

Therefore, the CMOS image sensor is currently widely used in various application parts such as a digital still camera, a digital video camera, and the like.

The embodiment provides a new structure of the image sensor.

The embodiment provides an image sensor capable of realizing an image by receiving light in both directions as well as in both directions.

The embodiment provides an image sensor that can implement a logic circuit using an organic thin film transistor.

The image sensor according to the embodiment may include a transparent substrate having a pixel region and a logic region formed thereon, a first metal interconnection layer formed on the transparent substrate, an organic transistor formed on the first metal interconnection layer of the logic region, and stacked on the pixel region. And a first color filter, a first photodiode, a second photodiode and a second color filter, an insulating film covering the second color filter and the organic transistor, and a second metal wiring layer formed on the insulating film.

According to an embodiment, a method of manufacturing an image sensor may include forming organic transistors in a logic region of a transparent substrate, forming an insulating layer covering organic transistors of the transparent substrate, and trenches in each unit pixel of a pixel region of the transparent substrate. Forming a first color filter, a first photodiode, a separation pattern, a second photodiode, and a second color filter in the trench.

The embodiment provides a new structure of the image sensor, which can receive and process light in both directions, and can process an image in both directions in a single logic circuit, so that an image sensor having a thin thickness can be manufactured. It is cheaper.

An image sensor and a method of manufacturing the same according to an embodiment will be described in detail with reference to the accompanying drawings.

In the description of the embodiments, where described as being formed "on / over" of each layer, the on / over may be directly or through another layer ( indirectly) includes everything formed.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not necessarily reflect the actual size.

1 to 7 are cross-sectional views illustrating a method of manufacturing an image sensor according to an embodiment.

As illustrated in FIG. 7, the image sensor includes a transparent substrate 100, color filters 171a, 171b, 172a, 172b, 173a, and 173b formed in the light receiving region of the transparent substrate 100 and photodiodes ( 175a and 175b and logic circuits including a plurality of transistors formed in the non-light-receiving region of the transparent substrate 100.

The color filters 171a, 171b, 172a, 172b, 173a, and 173b and the photodiodes 175a and 175b are formed in a pixel area, and the logic circuits are formed in a logic area.

Light blocking patterns 160 are formed on the upper and lower portions of the logic region to prevent leakage current or malfunction of the transistor by light.

Transistors connected to the photodiodes 175a and 175b to output signals are formed in the pixel region, and are classified into 3T, 4T, and 5T types according to the number of the transistors. The 3T type consists of one photodiode and three transistors, and the 4T type consists of one photodiode and four transistors.

Looking at the method of manufacturing the image sensor as described above are as follows.

As shown in FIG. 1, the first metal wiring layer 101 is formed on the transparent substrate 100.

The transparent substrate 100 may be a glass substrate.

The first metal wiring layer 101 is formed of a transparent conductive metal.

The first metal wiring layer 101 includes at least one of a transparent conductive metal including indium tin oxide (ITO) and indium zinc oxide (IZO).

An insulating film 110 is formed on the first metal wiring layer 101.

The insulating film used in the embodiment may include at least one of an oxide film, a nitride film, and an oxynitride film, and as shown in the drawings, the insulating films are represented and referred to as one layer without being distinguished from each other, but may be formed in a multilayer according to a manufacturing process. It is.

A gate electrode 121 is formed on the insulating layer 110, and a gate insulating layer 123 is formed on the gate electrode 121. An active layer 125 made of an organic semiconductor is formed on the gate insulating layer 123. The source electrode 127 and the drain electrode 129 connected to both sides of the active layer 125 are formed. As a result, organic thin film transistors (OTFTs) may be formed.

The organic transistors may form a logic circuit of an image sensor.

The organic semiconductor used as the active layer 125 can be formed in a low temperature process to realize a low-cost thin film transistor.

The gate electrode 121, the source electrode 127, and the drain electrode 129 may be used as a transparent conductive metal, and may include at least one of metal groups including cobalt, titanium, tantalum, aluminum, nickel, and copper. have.

Meanwhile, a first via metal 103 may be formed on the insulating layer 110 to electrically connect the gate electrode 121 and the first metal wiring layer 101.

The first metal wiring layer 101 may be formed of a multilayer insulating film and a multilayer metal wiring.

The first metal wiring layer 101 may be formed by depositing a transparent conductive metal film on an insulating film and patterning the metal film using a method such as photolithography.

The metal wires of the first metal wiring layer 101 formed in the light receiving region must be transparent because light must pass therethrough, but the first metal wiring layer 101 of the logic region corresponding to the non-light receiving region must be made of a transparent conductive metal. It is not intended to be an opaque metal.

Meanwhile, an insulating film 110 is formed on the entire surface of the substrate to cover the transistors.

A first connection metal 105 is then formed in the pixel region to transfer photoelectrons to transistors from later formed photodiodes.

Therefore, the first connection metal 105 corresponds to each photodiode and is connected to the first metal wiring layer 101.

An insulating layer 110 is formed on the entire surface of the substrate to cover the first connection metal 105.

When the first connection metal 105 is connected to the photodiode for back light reception, a second connection metal 109 for connection with the photodiode for front light reception is formed.

In the pixel region, the first connection metal 105 is formed in a via formed from the first metal wiring layer 101 to the center portion of the insulating layer 110, and the second connection metal 109 is formed on the insulating layer center portion on the insulating layer. It is formed within.

The first connection metal 105 and the second connection metal 109 correspond to each other, and one first connection metal 105 and a second connection metal 109 are formed for one photodiode region.

That is, the photodiode region includes a first photodiode 175a for back light reception and a second photodiode 175b for front light reception, and the first photodiode 175a includes the first connection metal ( 105 is connected to the second photodiode 175b and a second connection metal 109.

Meanwhile, a second via metal 107 electrically connected to the source electrode 127 and the drain electrode 129 of the organic transistor is formed.

As shown in FIG. 2, a photoresist pattern 151 for forming a photodiode is formed on the insulating layer 110.

The photoresist pattern 151 covers the logic region and opens only the photodiode region in the pixel region.

The insulating layer is reactively etched using the photoresist pattern 151 as an etching mask to form trenches T in the photodiode region of each unit pixel.

The first connection metal 105 and the second connection metal 109 are exposed by the trench T.

As shown in FIG. 3, first color filters 171a, 171b, and 171c are formed in the trench T. As shown in FIG. The first color filters 171a, 171b, and 171c include a red color filter, a green color filter, and a blue color filter, and form one color filter in one trench T.

Thereafter, a first photodiode 175a made of a conductive polymer is formed on the first color filters 171a, 171b, and 171c in the trench T.

The first photodiode 175a generates photo electrons from light entering through the transparent substrate 100 on the rear surface.

The first photodiode 175a is connected to the first connection metal 105.

Thereafter, a separation pattern 180 is formed on the first photodiode 175a in the trench T.

The separation pattern 180 is intended to prevent the light received by the first photodiode 175a from passing through and affecting the second photodiode 175b.

Therefore, the separation pattern 180 is preferably made of a material that can absorb or block light.

The separation pattern 150 may be formed by stacking a red color filter 180a, a green color filter 180b, and a blue color filter 180c.

When the red color filter 180a, the green color filter 180b, and the blue color filter 180c overlap, most wavelengths of light are blocked, so that the first photodiode 175a and the separation below the separation pattern 180 are separated. The second photodiode 175b on the pattern 180 may receive light separately from each other to generate another image.

That is, the separation pattern 180 interposed between the first photodiode 175a and the second photodiode 175b receives light in both directions to generate different images.

As described above, the red color filter 180a, the green color filter 180b, and the blue color filter 180c are sequentially stacked and patterned in each trench T to form the first photodiode 175a in the trench T. Separation pattern 180 is formed on the substrate.

Thereafter, a second photodiode 175b is formed on the separation pattern 180 in the trench T. The second photodiode 175b may be formed of a conductive polymer.

The second photodiode 175b is connected to the second connection metal 109 exposed in the trench T.

Second color filters 171b, 172b, and 173b are formed on the conductive polymer.

The colors of the first color filters 171a, 172a, and 173a and the colors of the second color filters 171b, 172b, and 173b may or may not match.

Thus, the bidirectional photodiode region can be formed.

As shown in FIG. 4, an insulating film 110a covering the second color filters 171b, 172b, and 173b is formed.

As illustrated in FIG. 5, a second metal wiring layer 130 is formed on the insulating layer 110 to be connected to the second connection metal 109 and to the second via metal 107.

The second metal wiring layer 130 may be formed of a transparent conductive metal.

The metal of the second metal wiring layer 130 of the logic region may be made of an opaque metal.

The second metal wiring layer 130 may be formed of a multilayer metal wiring and a multilayer insulating film.

The second metal wiring layer 130 may include at least one of a transparent conductive metal made of ITO and IZO.

The second metal wiring layer 130 may be formed by depositing a transparent conductive metal film on the insulating film and patterning the photolithography layer.

As illustrated in FIG. 6, a transparent protective layer 140 may be formed on the entire surface of the second metal wiring layer 130.

The insulating layer 110 and the protective layer 140 mentioned above may be formed of an oxide layer.

In addition, the insulating film 110 and the protective film 140 may include a nitride film, an oxynitride film, or the like.

As shown in FIG. 7, the logic region forms a light blocking pattern 160 on the transparent substrate 100 and the passivation layer 140 so as not to be affected by the received light.

The light blocking pattern 160 may be made of black resin, and the light blocking pattern 160 may be made of a material that absorbs or reflects light.

The bidirectional image sensor manufactured as described above may receive a rear or front surface to generate different images. That is, it can have the effect of using two image sensors.

The logic circuits of the image sensor logic region and the transistors of the pixel region may be connected to the first and second photodiodes 175a and 175b to be commonly used.

That is, the signal of the first photodiode 175a is processed when the first photodiode 175a is operated, and the signal of the second photodiode 175b is operated when the second photodiode 175b is operated. Can be processed.

The first photodiode 175a and the second photodiode 175b may be operated separately, and the first photodiode 175a and the second photodiode 175b simultaneously receive light and receive respective signals. It may be operated simultaneously by processing sequentially in the logic circuit.

As a result, the embodiment can implement an image sensor having a new structure capable of receiving and processing light in both directions, and can manufacture a thin thickness image sensor by processing images in both directions in one logic circuit. This is cheap.

As mentioned above, the present invention has been described in detail through specific embodiments, which are intended to specifically describe the present invention, and the method of forming a semiconductor device according to the present invention is not limited thereto. It is apparent that modifications and improvements are possible to those skilled in the art.

1 to 7 are cross-sectional views illustrating a method of manufacturing an image sensor according to an embodiment.

Claims (13)

A transparent substrate on which a pixel region and a logic region are formed; A first metal wiring layer formed on the transparent substrate; An organic transistor formed on the first metal wiring layer of the logic region; A first color filter, a first photodiode, a second photodiode, and a second color filter stacked in the pixel area; A separation pattern formed between the first photodiode and the second photodiode; An insulating layer covering the second color filter and the organic transistor; And And a second metal wiring layer formed on the insulating film. The method of claim 1, The separation pattern may include a red color filter, a blue color filter, and a green color filter. The method of claim 1, A first connection metal formed between the first metal wiring layer and the first photodiode; And And a second connection metal formed between the second metal wiring layer and the second photodiode. The method of claim 1, And the first metal wiring layer and the second metal wiring layer comprise wirings made of a transparent conductive metal. The method of claim 1, The organic transistor, A gate electrode connected to the first metal wiring layer; A gate insulating film formed on the gate electrode; An organic semiconductor formed on the gate insulating film; And An image sensor comprising a source electrode and a drain electrode connected to both sides of the organic semiconductor. The method of claim 1, And the first and second photodiodes comprise a conductive polymer. Forming organic transistors in a logic region of the transparent substrate; Forming an insulating layer covering the organic transistors of the transparent substrate; Forming a trench in each unit pixel of the pixel area of the transparent substrate; And forming a first color filter, a first photodiode, a separation pattern, a second photodiode, and a second color filter in the trench. The method of claim 7, wherein After forming the second color filter, And forming a second metal wiring layer connected to the second photodiode and the organic transistors. The method of claim 7, wherein Before forming the organic transistors, And forming a first metal wiring layer connected to the first photodiode and the organic transistors on the transparent substrate. The method of claim 7, wherein In the forming of the separation pattern, And forming a red color filter, a blue color filter, and a green color filter in order on the first photodiode. The method of claim 7, wherein And the first and second photodiodes are made of a conductive polymer. The method of claim 8, And the second metal wiring layer comprises a wiring including at least one of a transparent conductive metal group consisting of ITO and IZO. The method of claim 9, And the first metal wiring layer comprises a wiring including at least one of a transparent conductive metal group consisting of ITO and IZO.

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