KR100821474B1 - Method of measuring resistance of photo-diode and method of manufactruing device for measuring resistance of photo-diode - Google Patents

Abstract

A photo diode resistance measuring method and a method for manufacturing a photo diode resistance measuring device are provided to improve the performance and operation of a vertical image sensor by precisely calculating resistance of a photo diode in the vertical image sensor having the photo diode and a plug connected to the photo diode. A photo diode resistance measuring method is composed of steps for disposing a photo diode(252) with a first width and a first length connected to a pair of first contact plugs(254), on a semiconductor substrate(200); forming a dummy photo diode with a second width and a second length connected to second contact plugs(258) having the same resistance of the first contact plug, on the semiconductor substrate; calculating first total resistance of the first contact plugs and the photo diode by applying a preset test voltage to the first contact plug; calculating second total resistance of the second contact plugs and the dummy photo diode by applying a test voltage to the second contact plug; and computing sheet resistance of the photo diode by dividing deviation between the first and second total resistances by the first length.

Description

METHOD OF MEASURING RESISTANCE OF PHOTO-DIODE AND METHOD OF MANUFACTRUING DEVICE FOR MEASURING RESISTANCE OF PHOTO-DIODE}

1 is a cross-sectional view of a vertical image sensor including a photodiode according to the present invention.

2 and 3 are cross-sectional views illustrating a method for measuring sheet resistance of the red photodiode shown in FIG. 1.

4 to 11 are cross-sectional views illustrating a method of manufacturing a photodiode resistance measuring apparatus according to an embodiment of the present invention.

The present invention relates to a photodiode resistance measuring method and a manufacturing method of a photodiode resistance measuring apparatus.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal, in which charge carriers are stored and transferred to a capacitor while individual metal oxide-silicon (MOS) capacitors are located in close proximity to each other. By using CMOS technology that uses charge coupled device (CCD), control circuit, and signal processing circuit as peripheral circuit, CMOS transistors are made as many as the number of pixels. There is a CMOS (complementary MOS) image sensor that employs a switching scheme that detects the output sequentially.

The general CMOS image sensor adopts a method of reproducing an image by forming a color filter layer on a pixel array and selectively transmitting specific wavelengths to a photodiode.

However, the above-described method has a disadvantage in that it takes up a large area of a pixel to implement one color in reproducing an image. For example, in the case of an RGB color filter that decomposes natural light into three primary colors of light, three pixels are required to detect red, green, and blue colors.

Recently, unlike a horizontal color filter structure in which a color filter layer is arranged on a pixel area, a vertical image sensor having a vertical photo diode capable of realizing various colors in one pixel has been proposed. The vertical photodiodes of the vertical image sensors are connected with contact plugs.

The performance of the vertical image sensor is determined by various factors, but the surface resistance of the vertical photodiode has a great influence on the performance and operation of the vertical image sensor.

However, in the case of the vertical image sensor, since the vertical photodiode is connected to the contact plug, when the surface resistance of the vertical photodiode is measured by applying a test voltage to the vertical photodiode through the contact plug, As a result, it is difficult to accurately measure the sheet resistance of the vertical photodiode.

One object of the present invention is to provide a resistance measuring method of a photodiode capable of accurately measuring the resistance of a photodiode of a vertical image sensor.

Another object of the present invention is to provide a method of manufacturing a resistance measuring device of a photodiode for measuring the resistance of the photodiode.

A resistance measuring method of a photodiode for realizing one object of the present invention comprises the steps of providing a photodiode having a first width and a first length on the semiconductor substrate and connected to a pair of first contact plugs, the semiconductor substrate Providing a dummy photodiode having a first width and a second length on the second contact plug, the dummy photodiode connected to second contact plugs having the same resistance as the first contact plug, and a test set in the first contact plug. Calculating a first summation resistance of the first contact plugs and the photodiode by applying a voltage, and applying a test voltage to the second contact plug to generate a second sum of the second contact plugs and the dummy photodiode. Calculating a summation resistance; And calculating the sheet resistance of the photodiode by dividing the deviation of the first summing resistor by the first length.

According to another aspect of the present invention, there is provided a method of manufacturing a resistance measuring apparatus for a photodiode, forming a photodiode having a first width and a first length and a dummy photodiode having the first and second lengths on a semiconductor substrate. And a thin film having first contact holes covering the photodiode and the dummy photodiode on the semiconductor substrate and opening both ends of the photodiode and second contact holes opening both ends of the dummy photodiode. And forming first contact plugs connected to the photodiode through the first contact holes and second contact plugs connected to the dummy photodiode through the second contact hole.

Hereinafter, a method and apparatus for measuring a resistance of a photodiode according to embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to the following embodiments, and is commonly used in the art. Those skilled in the art will be able to implement the invention in various other forms without departing from the spirit of the invention.

1 is a cross-sectional view of a vertical image sensor including a photodiode according to the present invention.

Referring to FIG. 1, a red photodiode 252 is formed in the P-type first epitaxial layer 200 formed on the photodiode region of the semiconductor substrate 200.

Subsequently, the second epitaxial layer 210 is grown on the P-type first epitaxial layer 200, and the P-type second epitaxial layer 210 is formed by implanting P-type ions into the second epitaxial layer 210. .

The red photodiode 252 is formed by forming a first plug 254 in which a high concentration of ions are implanted in a portion of the P-type second epitaxial layer 210 to be connected to the red photodiode 252 to extract a signal. And a first plug 254.

Thereafter, a photoresist pattern (not shown) is formed on the P-type second epitaxial layer 210 and ions are implanted into the P-type second epitaxial layer 210 to form a green photo diode 256. To form.

A shallow trench isolation (STI) is formed in the third epitaxial layer 220 to grow the third epitaxial layer 220 on the P-type second epitaxial layer 210 including the green photodiode 256 and define an active region. 260 forms a region.

A photoresist pattern (not shown) is formed on the third epitaxial layer 220 and ion implanted to form a second plug 258 in the third epitaxial layer 220. The second plug 258 is electrically connected to the green photodiode 256.

Subsequently, a well process is performed to form a photoresist pattern (not shown) on the P-type third epitaxial layer 220 including the STI 260, and ion implanted to connect the red photodiode 252. A second plug 258 connected to the first plug 254 and the green photodiode 256 is formed.

Thereafter, a photoresist pattern is formed on the P-type third epitaxial layer 220 and ion implanted to form a blue photo diode 259.

The red photodiode 252, the green photodiode 256, and the blue photodiode 259 are each arranged vertically to form one pixel.

2 and 3 are cross-sectional views illustrating a method for measuring sheet resistance of the red photodiode shown in FIG. 1.

Referring to FIG. 2, the red photodiode 252 is formed on the P-type first epitaxial layer 200 of the bare wafer to measure the sheet resistance of the red photodiode. In the present embodiment, the red photodiode 252 has a first width and a first length L / 2 when viewed in plan view.

The red photodiode 252 is connected to the first plugs 254 and 258 formed in the contact holes formed in the P-type second epitaxial layer 220 and the P-type third epitaxial layer 230. In this embodiment, both ends of the red photodiode 252 are connected to a pair of first plugs 254 and 258 to measure the sheet resistance of the red photodiode 252.

Referring to FIG. 3, a dummy red photodiode 253 is formed on the P-type first epitaxial layer 200 of the bare wafer to measure sheet resistance of the red photodiode. In the present embodiment, the dummy red photodiode 253 has a first width and a second length L when viewed in plan view. In the present embodiment, the second length L of the dummy red photodiode 253 is twice the first length of the red photodiode 252.

The dummy red photodiode 253 is connected to the second plugs 254 and 258 formed in the contact holes formed in the P-type second epitaxial layer 220 and the P-type third epitaxial layer 230. In the present exemplary embodiment, second plugs 254 and 258 are connected to both ends of the dummy red photodiode 253 to measure the sheet resistance of the dummy red photodiode 253. In this embodiment, the first plug and the second plug are given the same reference numerals because they are formed under substantially the same conditions.

When the red photodiode 252 and the first plug are prepared on the bare wafer, a test voltage is applied to the first plugs to calculate a current flowing in the red photodiode 252.

At this time, the sheet resistance of the red photodiode 252 is Rs, the length is L / 2, the first total resistance of the red photodiode 252 and the first plugs is R (L / 2), and the resistances of the two first plugs are measured. When defined as P1 and P2, the first summation resistance R (L / 2) of the red photodiode 252 is [Rs × (L / 2)] + [2 × (P1 + P2)].

When the dummy red photodiode 253 and the second plug are prepared on the bare wafer, a test voltage is applied to the second plugs to calculate a current flowing in the dummy red photodiode 253.

In this case, the sheet resistance of the dummy red photodiode 253 is Rs', the length is L, the second summation resistance of the dummy red photodiode 253 and the second plugs is R (L), and the resistances of the two second plugs are P1. When defined as', P2 ', the second summation resistance R (L) of the dummy red photodiode 253 is [Rs' × (L)] + [2 × (P1' + P2 ')].

When the first summation resistance R (L / 2) of the red photodiode 252 and the second summation resistance R (L) of the dummy red photodiode 253 are calculated, the second summation resistance of the dummy red photodiode 253 is calculated. The deviation D of the first summation resistance R (L / 2) of R (L) and red photodiode 253 is calculated. Subsequently, by dividing the deviation D by the length L / 2 of the red photodiode 252, the resistance of only the red photodiode 252 excluding the resistance of the first plug may be calculated.

Meanwhile, as the resistance of the red photodiode 252 is calculated, the resistance of the first plug connected to the red photodiode 252 may also be calculated.

In this way, the resistance of only the green photodiode excluding the resistance of the second plug can be accurately calculated.

4 to 11 are cross-sectional views illustrating a method of manufacturing a photodiode resistance measuring apparatus according to an embodiment of the present invention.

Referring to FIG. 4, a P-type first epitaxial layer 200 is formed on the semiconductor substrate 200.

Referring to FIG. 5, after the photoresist pattern having the first opening is formed on the P-type first epitaxial layer 200, the photoresist pattern is used as the ion implantation mask to form ions on the first epitaxial layer 200. Is injected to form a red photo diode (252). In this embodiment, the red photodiode 252 has a first width and a first length to measure resistance.

Referring to FIG. 6, the epitaxial layer is grown on the P-type first epitaxial layer 200 again, and the P-type second epitaxial layer 210 is formed by implanting P-type ions into the epitaxial layer.

Referring to FIG. 7, after forming photoresist patterns 215 corresponding to both ends of the red photodiode 252 on the P-type second epitaxial layer 210, the photoresist pattern 215 may be ion implanted with a mask. The high concentration of ions are implanted onto the P-type second epitaxial layer 210 corresponding to both ends of the red photodiode 252 to form a pair of first plugs 254.

Referring to FIG. 8, the photoresist pattern 211 having an opening is formed again on the second P-type epitaxial layer 210, and ions are implanted onto the second P-type epitaxial layer 210 through the openings. A green photo diode 256 is formed. In this embodiment, green photodiode 256 has a first width and a first length.

Referring to FIG. 9, a third epitaxial layer 220 is grown on the P-type second epitaxial layer 210 including the green photodiode 256.

Referring to FIG. 10, a shallow trench isolation (STI) 260 is formed in the third epitaxial layer 220 to define an active region.

Referring to FIG. 11, a photoresist pattern 225 having an opening for opening the first plug 254 and an opening for opening both ends of the green photodiode 256 is formed on the third epitaxial layer 220. Ion implantation forms a second plug 258 in the third epitaxial layer 220. The second plug 258 is electrically connected to the green photodiode 256 and the red photodiode 256.

Then, the dummy red photodiode having a second length that is about twice the first width and the first length and the dummy green having the second length that is about twice the first width and the first length in the same process as FIGS. 4 to 11. Fabricate a photodiode.

In the present embodiment, the red photodiode and the dummy red photodiode, the green photodiode and the dummy green photodiode may be formed on the same semiconductor substrate or on different semiconductor substrates.

Then, as described with reference to FIGS. 2 to 3, the resistances of the red photodiode and the dummy red photodiode may be calculated, respectively, to calculate the resistance of the red photodiode only.

In addition, as described with reference to FIGS. 2 to 3, the resistances of the green photodiode and the dummy green photodiode may be calculated, respectively, to accurately calculate the resistance of the green photodiode.

As described in detail above, in the vertical image sensor having a photodiode and a plug connected to the photodiode, the resistance of the photodiode can be accurately calculated to improve the performance and operation of the vertical image sensor. Have

Although the detailed description of the present invention has been described with reference to the embodiments of the present invention, those skilled in the art or those skilled in the art will have the spirit and scope of the present invention as set forth in the claims below. It will be appreciated that various modifications and variations can be made in the present invention without departing from the scope of the art.

Claims (8)

Providing a photodiode having a first width and a first length on the semiconductor substrate and connected to the pair of first contact plugs; Providing a dummy photodiode on the semiconductor substrate, the dummy photodiode having the first width and the second length and connected to the second contact plugs having the same resistance as the first contact plug; Calculating a first summation resistance of the first contact plugs and the photodiode by applying a predetermined test voltage to the first contact plug; Calculating a second summation resistance of the second contact plugs and the dummy photodiode by applying the test voltage to the second contact plug; And And calculating the sheet resistance of the photodiode by dividing the deviation between the first summation resistor and the second summation resistor by the first length. The method of claim 1, wherein each of the first contact plugs comprises contact plugs in which at least two are connected in series. The method of claim 1, wherein each second contact plug comprises at least two contact plugs connected in series. The method of claim 1, wherein the second length is twice the first length. Forming a photodiode having a first width and a first length and a dummy photodiode having the first and second lengths on a semiconductor substrate; Forming a thin film on the semiconductor substrate having first contact holes covering the photodiode and the dummy photodiode and opening both ends of the photodiode and second contact holes opening both ends of the dummy photodiode ; And Forming first contact plugs connected to the photodiode through the first contact holes and second contact plugs connected to the dummy photodiode through the second contact hole. The method of claim 5, wherein at least two contact plugs are formed in the first contact hole in the forming of the first contact plug. The method of claim 5, wherein at least two contact plugs are formed in the second contact hole in the forming of the second contact plug. 6. The method of claim 5, wherein the second length is twice the first length.

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