JPH08139302A - Optical semiconductor wafer and manufacture of optical semiconductor light-receiving element - Google Patents

Abstract

PURPOSE: To provide an optical semiconductor wafer high in measurement precision of an optical short-circuit current and capable of preventing reduction in the optical short-circuit current, and a method of manufacturing an optical semiconductor light-receiving element. CONSTITUTION: In a semiconductor wafer 52, in a scribe line region 71 provided to respectively separate a photodiode 51, a diode part 70 is formed that an anode and a cathode are electrically short-circuited by a short-circuit electrode 69. Accordingly, when measuring an optical short-circuit current to examine the photodiode 51, an influence by other adjacent photodiodes can be reduced. Further, as the diode part 70 is reduced together with the scribe line region 71, the optical short-circuit current of the processed photodiode 51 is not reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor wafer having a plurality of light receiving elements formed on a semiconductor wafer and a method for manufacturing the optical semiconductor light receiving element.

[0002]

2. Description of the Related Art FIG. 6 is a plan view of a semiconductor wafer 12 having a plurality of photodiodes 11 as a typical conventional example, and FIG. 7 is a section line VII-VII in FIG.
FIG. 8 is a cross-sectional view viewed from above, and FIG. 8 is a cross-sectional view showing a manufacturing process of the photodiode 11.

The photodiode 11 in the semiconductor wafer 12 has a P on the one surface 1a side of the N-type silicon wafer 1.
^{The +} diffusion region 3 is formed, and the electrode 7 is provided so as to contact the P ⁺ diffusion region 3. An oxide film 2 of silicon dioxide is formed on a region other than the electrode 7 on the one surface 1a of the N-type silicon wafer 1. N-type silicon wafer 1
An N ⁺ diffusion region 4 is formed on the peripheral edge of the photodiode 11 on the one surface 1a side. On the other surface 1b side of the N-type silicon wafer 1, the other surface 1b is entirely covered with N.
^{The +} diffusion region 14 is formed, and the bottom electrode 8 is formed so as to cover the N ⁺ diffusion region 14.

The manufacturing process of the photodiode 11 will be described below. An oxide film 2 made of silicon dioxide is formed on both surfaces of the N-type silicon wafer 1 shown in FIG. 8 (1), and the oxide film 2 is removed according to a predetermined pattern as shown in FIG. 8 (2). Next, as shown in FIG. 8C, impurities such as boron are diffused to form a P ⁺ diffusion region 3 on the one surface 1a side of the N-type silicon wafer 1. After that, the oxide films 2 are formed again on both sides of the N-type silicon wafer 1, and
As shown in (4), the oxide film 2 is removed according to a predetermined pattern to expose the surface of the N-type silicon wafer 1. Next, as shown in FIG. 8 (5), impurities such as phosphorus are diffused into the removed regions of the oxide film 2 to form N ⁺ diffusion regions 4 and 14.
To form. In the step shown in FIG. 8 (6), the oxide film 2 is removed and the electrode contact 5 and the contact 6 for connecting the electrode 7 described later to the P ⁺ diffusion region 3 are formed. Next, as shown in FIG. 8 (7), the electrode 7 is formed so as to fit in the electrode contact 5 and come into contact with the P ⁺ diffusion region 3, and the other surface 1 b of the N-type silicon wafer 1 is formed.
The bottom electrode 8 is formed so as to cover the N ⁺ diffusion region 14 formed on the side. After the semiconductor wafer 12 is formed as described above, as shown in FIG.
Is divided into dicings, and each photodiode 11
To separate. When separating into the respective photodiodes 11, along the scribe line region 9 which is determined so as to pass through the N ⁺ diffusion region 4 provided on the one surface 1a side of the N-type silicon wafer 1 shown in FIG. Dicing is performed.

When the photodiode 11 is manufactured as described above, the state of the semiconductor wafer 12 is left as it is for the defect detection of the photodiode 11, that is, the state where the photodiode 11 is built in the N-type silicon wafer 1. In this state, one photodiode 11 is irradiated with light and the photo-short circuit current flowing from the electrode 7 is measured. Semiconductor wafer 1
Since there are a plurality of photodiodes on the substrate 2, when light is irradiated, carriers are also generated in the photodiodes around the photodiode, which is the element to be measured, and reach the light receiving portion PN junction in the element to be measured. Since the optical short circuit current increases, it is impossible to measure the original value of the optical short circuit current of the device under test. Therefore, it becomes different from the value of the optical short-circuit current measured after being separated into the respective photodiodes 11 and processed, and accurate defect detection cannot be performed, leading to a decrease in yield.

FIG. 9 is a plan view of a semiconductor wafer 32 having a plurality of phototransistors 31 formed therein, which is another technical example, and FIG. 10 is a sectional view taken along the section line XX in FIG. Semiconductor wafer 32 shown in FIGS. 9 and 10.
In the above, the same components as those of the semiconductor wafer 12 described above are designated by the same reference numerals and the description thereof will be omitted.

Since the light receiving element formed on the semiconductor wafer 32 is the phototransistor 31, impurities of different conductivity types are diffused into the P ⁺ diffusion region 3 corresponding to the light receiving portion to form the N ⁺ diffusion emitter region 35, and the emitter is formed. The electrode 36 is connected. In the phototransistor 31, the electrode 7 is a base electrode and the bottom electrode 8 is a collector electrode.

When measuring the photoshort-circuit current of the phototransistor 31 in the semiconductor wafer 32, as in the case of the semiconductor wafer 12 described above, an increase in the photoshort-circuit current due to carriers generated in another adjacent phototransistor is a problem. Becomes

As another conventional example, the structure shown in FIGS. 11 and 12 is conceivable in order to solve the above-mentioned problem at the time of measuring the optical short-circuit current. FIG. 11 is a plan view of a semiconductor wafer 22 having a plurality of photodiodes 21 formed therein, and FIG. 12 is a cross section line XII- in FIG.
It is sectional drawing seen from XII. In the semiconductor wafer 22, the same components as those of the semiconductor wafer 12 described above are designated by the same reference numerals, and the description thereof will be omitted.

In the semiconductor wafer 22, the N ⁺ diffusion region 4 provided on the side of the one surface 1a of the N-type silicon wafer 1 is 2.
It is divided into two parts, and the P ⁺ diffusion region 3 is formed between them to form the diode portion 25. Furthermore, the short-circuit electrode 2
6, the anode and cathode of the diode portion 25 are electrically short-circuited.

When the photodiodes 21 are formed on the N-type silicon wafer 1 as described above, when measuring the photo-short circuit current, the adjacent photodiodes are connected by the diode portion 25 in which the anode and the cathode are electrically short-circuited. It is possible to absorb the carriers generated in. Therefore, there is no increase in the optical short-circuit current due to the adjacent photodiodes, and a more accurate value can be obtained in the state of the semiconductor wafer 22 as compared with the value of the optical short-circuit current measured after dicing and processing.

FIG. 13 is a diagram showing a state in which the semiconductor wafer 22 is irradiated with light in order to measure the optical short-circuit current of the photodiode 21. In FIG. 13, the length of the photodiode 21, which is one chip, in one direction is indicated by W. The out-chip carrier 28 and the in-chip carrier 29 generated by the irradiation of light from the direction of the arrow 27 respectively travel in random directions, move by the distance of the diffusion length, and then disappear. By providing the diode portion 25 around the photodiode 21, the off-chip carrier 28 that causes an increase in the optical short-circuit current is
When passing near the diode portion 25, it diffuses due to the PN junction concentration gradient and reaches the depletion layer region. At that time, the electrons move to the N-type region and the holes move to the P-type region. Since the diode portion 25 electrically short-circuits the anode and the cathode, current flows and the carriers are consumed. In the semiconductor wafer 22, the out-chip carriers 28 are absorbed and at the same time, some in-chip carriers 29 a are also absorbed by the diode portion 25.

The ratio of carriers absorbed by the diode portion 25 in which the anode and the cathode are short-circuited is determined by the pattern shape, substrate concentration, P ⁺ concentration profile,
Also, it is affected by the substrate lifetime and changes. However, since the amount of change is very small with respect to the optical short circuit current of the light receiving portion, it can be ignored. Therefore, it becomes easy to judge the quality of the photodiode 21 on the semiconductor wafer 22, and the value of the optical short circuit current measured in the state of the semiconductor wafer 22 and the value of the optical short circuit current after being divided into the respective photodiodes. It is possible to perform highly accurate measurement.

[0014]

When the semiconductor wafer 22 as described above is formed, the inflow of carriers generated in other adjacent photodiodes is reduced, so that the accuracy at the time of measuring the optical short-circuit current is improved. Diode part 2
Since 5 remains after dicing and dividing for each photodiode 21, the optical short circuit current, which is an important characteristic of the photodiode 21 alone, is reduced. In addition, the photodiode 21 must be made large in proportion to the decrease in the optical short circuit current.

An object of the present invention is to provide an optical semiconductor wafer and a method for manufacturing an optical semiconductor light receiving element, which can measure the optical short circuit current with high accuracy and can prevent the decrease of the optical short circuit current.

[0016]

According to the present invention, a plurality of light receiving elements formed on the same semiconductor wafer and a scribe line region for surrounding each light receiving element and separating each light receiving element are provided. An optical semiconductor wafer comprising a diode formed by diffusing impurities having the same conductivity type as that of the light receiving portion, and having an anode and a cathode electrically short-circuited. Further, according to the present invention, a plurality of light receiving elements formed on the same semiconductor wafer are surrounded, and a diode is formed at the same time as the light receiving element in a scribe line region for separating each light receiving element. Manufacture of an optical semiconductor light receiving element characterized by measuring the light receiving characteristics of each light receiving element with the cathode electrically short-circuited and removing the diode when performing dicing division along the scribe line. Is the way. Further, the present invention is characterized in that the optical semiconductor light receiving element is a photodiode, and the light receiving characteristic is an optical short circuit current.

[0017]

According to the present invention, the optical semiconductor wafer includes a plurality of light receiving elements formed on the same semiconductor wafer, and a scribe line region provided so as to surround each light receiving element in order to separate each light receiving element. And a diode formed by diffusing an impurity having the same conductivity type as that of the light receiving portion and having an anode and a cathode short-circuited. Therefore, a diode whose anode and cathode are short-circuited is formed in the scribe line region surrounding a plurality of light receiving elements formed on the same semiconductor wafer, and the light receiving characteristics of each light receiving element are measured in the state of the optical semiconductor wafer. The accuracy when doing can be improved. When the light receiving elements are separated, the diode is removed, and the influence on the light receiving characteristics of each light receiving element is also removed.

According to the present invention, the method of manufacturing an optical semiconductor wafer and an optical semiconductor light receiving element includes a plurality of light receiving elements on the same semiconductor wafer and surrounding each light receiving element to separate each light receiving element. A photo semiconductor wafer is formed by simultaneously forming a diode formed in the scribe line region provided in the photo diode, and the light receiving characteristics of each light receiving element are measured with the anode and cathode of the diode electrically short-circuited. Then, the diode in the optical semiconductor wafer is removed when the dicing division is performed along the scribe line. Therefore, the diode provided to suppress the influence of other light receiving elements when measuring the light receiving characteristics of each light receiving element in the state of the optical semiconductor wafer is removed when dicing into the respective light receiving elements. After the downsing division, the light receiving characteristic is improved.

Further, preferably, the optical semiconductor element is a photodiode, and the light receiving characteristic is an optical short circuit current. Therefore, when measuring the optical short-circuit current, which is important for determining the quality of the photodiode, the diode provided to suppress the influence of other photodiodes and to perform accurate measurement on the semiconductor wafer is diced to each photodiode. It is removed when splitting, and there is no reduction in the optical short circuit current as the final photodiode.

[0020]

1 is a plan view of a semiconductor wafer 52 having a plurality of photodiodes 51 according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along the section line II--II in FIG. FIG. 3 is a sectional view showing a manufacturing process of the photodiode 51.

In the photodiode 51 of the semiconductor wafer 52, a P ⁺ diffusion region 63 is formed on the one surface 61a side of the N-type silicon wafer 61, and an electrode 67 is provided so as to be in contact with the P ⁺ diffusion region 63. N-type silicon wafer 6
An oxide film 62 made of silicon dioxide is formed in a region other than the electrode 67 on the one surface 61a of the first substrate. N
An N ⁺ diffusion region 64 is formed on the peripheral edge of the photodiode 51 on the one surface 61a side of the mold silicon wafer 61, and a P ⁺ diffusion region 63 is formed so as to surround the N ⁺ diffusion region 64. On the other surface 61b side of the N-type silicon wafer 61, the N ⁺ diffusion region 74 is formed on the entire other surface 61b.
And a bottom electrode 68 is formed so as to cover the N ⁺ diffusion region 74.

The manufacturing process of the photodiode 51 will be described below. An oxide film 62 is formed on both surfaces of the N-type silicon wafer 61 shown in FIG. 3 (1), and the oxide film 62 is removed according to a predetermined pattern as shown in FIG. 3 (2). Next, as shown in FIG. 3C, an impurity such as boron is diffused on the one surface 61a side of the N-type silicon wafer 61 to form a P ⁺ diffusion region 63, and the both surfaces of the N-type silicon wafer 61 are again oxidized. The film 62 is formed. Then, according to a predetermined pattern, as shown in FIG.
2 is removed and one surface 61a of the N-type silicon wafer 61 is removed.
And the other surface 61b is exposed. Next, the oxide film 62
Impurities such as phosphorus are diffused in the region where
N ⁺ diffusion regions 64 and 74 are formed as shown in (5). The diode portion 70 is formed by the P ⁺ diffusion region 63 and the N ⁺ diffusion region 64. After forming the N ⁺ diffusion region 64, each surface of the N-type silicon wafer 61 is covered with the oxide film 62. In the step shown in FIG. 3 (6), the oxide film 62 at a predetermined position is removed to form the electrode contact 65 and the contact 66. Next, as shown in FIG. 3 (7), an electrode 67 is formed of aluminum or the like so as to fit in the electrode contact 65 and come into contact with the P ⁺ diffusion region 63. At the same time, the bottom electrode 68 is formed of gold or the like so as to cover the N ⁺ diffusion region 74 formed on the other surface 61b side of the N-type silicon wafer 61. Further, at the contact 66, a short-circuit electrode 69 is formed of aluminum or the like so as to make common contact with the P ⁺ diffusion region 63 and the N ⁺ diffusion region 64 in the diode portion 70. After the semiconductor wafer 52 is formed as described above, the semiconductor wafer 52 is diced and divided into photodiodes 51 as shown in FIG.

[0023] The semiconductor wafer 52 when the dicing division, P in the semiconductor wafer 52 as shown in FIG. 2 ⁺
This is done along a scribe line region 71 defined to include a diode portion 70 formed by diffusion region 63 and N ⁺ diffusion region 64.

In the semiconductor wafer 52, the one surface 61 of the N-type silicon wafer 61 is the same as the semiconductor wafer 22 described above.
The anode and cathode of the diode portion 70 formed by the P ⁺ diffusion region 63 and the N ⁺ diffusion region 64 provided on the a side are short-circuited by the short-circuit electrode 69.

A semiconductor wafer 52 constructed as described above
In the same manner as in the semiconductor wafer 12 described above, in order to detect a defect of each photodiode 51, the optical short circuit current is measured for each photodiode 51 in the state of the semiconductor wafer 52 and the inspection is performed. As described above, at the time of measuring the optical short-circuit current, carriers are also generated in the photodiode adjacent to the device under test and flow into the device under test, but since the diode portion 70 absorbs the carrier, the influence of the adjacent photodiode is reduced. Can be suppressed. Since the ratio of carriers absorbed in the diode portion 70 is fixed and is determined by the pattern of the photodiode, etc., the measurement value of the optical short-circuit current on the semiconductor wafer and the measured value after the photodiode separation are highly accurate. You can

Therefore, the value of the optical short-circuit current measured in the state of the semiconductor wafer 52 and the value of the optical short-circuit current measured after being divided into one photodiode and processed are highly accurately associated with each other. Becomes Further, since the diode portion 70 exists in the scribe line region 71 that is deleted when the semiconductor wafer 52 is diced and divided into the respective photodiodes, an optical short circuit occurs when the respective photodiodes 51 are formed. The current does not decrease, and the size of the photodiode 51 for obtaining the same output of the optical short-circuit current can be formed smaller than the case where the diode portion 70 is formed in the photodiode 51.

As described above, according to this embodiment, when the semiconductor wafer 52 is formed, the diode portion 70 is formed in the scribe line region 71 around the plurality of photodiodes 51 formed on the N-type silicon wafer 61. Therefore, the carriers generated in the other photodiodes adjacent to each other when measuring the optical short-circuit current are absorbed by the diode portion 70, and the influence from the other photodiodes can be suppressed. In addition, the diode portion 70 is formed in the scribe line region 71, and the photodiode 5 is formed.
Since 1 is deleted when it is divided into 1 pieces, the value of the optical short circuit current measured after the processing of the photodiode 51 does not decrease, and it is more than in the case where the diode portion 70 is formed in the photodiode 51. The size of the photodiode 51 for obtaining the same optical short circuit current output can be formed small.

FIG. 4 is a plan view of a semiconductor wafer 82 having a plurality of phototransistors 81 formed therein according to the second embodiment of the present invention, and FIG. 5 is a sectional view taken along the section line V--V in FIG. Is.

In the semiconductor wafer 82 shown in FIGS. 4 and 5, the same components as those of the semiconductor wafer 52 in the first embodiment described above are designated by the same reference numerals and the description thereof will be omitted. The light receiving element formed on the semiconductor wafer 82 is
Since it is the phototransistor 81, impurities having different conductivity types are diffused in the P ⁺ diffusion region 63 to form an N ⁺ diffusion emitter region 94, and the emitter electrode 95 is connected to the P ⁺ diffusion region 63. The other components are the same as those of the semiconductor wafer 52. In the phototransistor 81, the electrode 67 is a base electrode and the bottom electrode 68 is a collector electrode.

In order to inspect the semiconductor transistor 82 for defects in the phototransistor 81, the optical short circuit current is measured for each phototransistor 81 as in the semiconductor wafer 52 described above. Also in the phototransistor 81, since the diode between the collector and the base has the same structure as that of the photodiode, an optical short-circuit current similar to that of the photodiode flows between the collector and the base. Therefore, also in this embodiment, the same effect as that of the above-described first embodiment can be obtained.

In each of the embodiments, the PN photodiode and the phototransistor are used for description, but the PIN photodiode or the like can similarly obtain the effects of the present invention.

[0032]

As described above, according to the present invention, a plurality of light receiving elements are provided on the same semiconductor wafer, and within a scribe line region provided to surround the light receiving elements and separate each light receiving element. Since the anode and the cathode are short-circuited to form a diode, the influence of another adjacent light receiving element can be reduced by the diode when measuring the light receiving characteristic for the inspection of the light receiving element. Further, since the diode is in the scribe line region, it is deleted when the respective light receiving elements are separated, so that the influence of the diode when each light receiving element becomes a single unit can be eliminated.

Further, according to the present invention, in a scribe line region provided for surrounding a plurality of light receiving elements formed on the same semiconductor wafer when manufacturing an optical semiconductor light receiving element and for separating each light receiving element. A diode whose anode and cathode are short-circuited is formed, and the dicing division is performed along the scribe line after measuring the light receiving characteristic. Can be suppressed, and since the diode is removed by dicing and dividing, the light receiving characteristic measured after processing the light receiving element is not affected. Further, the size of the light receiving element for obtaining the same optical short circuit current output can be made smaller than that in the case where the diode is formed inside the light receiving element.

Further, according to the present invention, since the light receiving element is a photodiode and the light receiving characteristic is an optical short circuit current, when measuring the optical short circuit current, the influence of another photodiode adjacent to the diode is observed. In addition, since the diode is removed when dicing and dividing, the value of the optical short-circuit current measured after processing the photodiode is not affected. Furthermore, the size of the photodiode for obtaining the same optical short circuit current output can be reduced as compared with the case where the diode is formed inside the photodiode.

[Brief description of drawings]

FIG. 1 is a photodiode 5 according to a first embodiment of the present invention.
FIG. 3 is a plan view of a semiconductor wafer 52 on which a plurality of 1's are formed.

FIG. 2 is a sectional view taken along the section line II-II in FIG.

FIG. 3 is a cross-sectional view showing the manufacturing process of the photodiode 51.

FIG. 4 is a plan view of a semiconductor wafer 82 having a plurality of phototransistors 81 according to a second embodiment of the present invention.

5 is a cross-sectional view taken along the section line VV in FIG.

FIG. 6 is a plan view of a semiconductor wafer 12 having a plurality of photodiodes 11 as a typical conventional example.

FIG. 7 is a sectional view taken along section line VII-VII in FIG.

FIG. 8 is a cross-sectional view showing the manufacturing process of the photodiode 11.

FIG. 9 is a plan view of a semiconductor wafer 32 having a plurality of phototransistors 31 formed therein, which is another technical example.

FIG. 10 is a cross-sectional view taken along line XX of FIG. 9;

FIG. 11 is a photodiode 2 which is still another technical example.
FIG. 3 is a plan view of a semiconductor wafer 22 on which a plurality of 1's are formed.

12 is a cross-sectional view taken along the section line XII-XII in FIG.

FIG. 13 is a diagram showing how the semiconductor wafer 22 is irradiated with light.

[Description of Reference Signs] 51 Photodiode 52 Semiconductor Wafer 61 N-type Silicon Wafer 62 Oxide Film 63 P ⁺ Diffusion Region 64, 74 N ⁺ Diffusion Region 65 Electrode Contact 66 Contact 67 Electrode 68 Bottom Electrode 69 Short Circuit Electrode 70 Diode Part 71 Scribing Line area 81 phototransistor 94 N ⁺ diffused emitter area 95 emitter electrode

Claims (3)

[Claims] 1. A plurality of light receiving elements formed on the same semiconductor wafer, and a scribe line region for surrounding each light receiving element and separating each light receiving element has the same conductivity type as that of the light receiving section. An optical semiconductor wafer comprising a diode which is formed by diffusing impurities and whose anode and cathode are electrically short-circuited. 2. A plurality of light receiving elements formed on the same semiconductor wafer are surrounded, and a diode is formed at the same time as the light receiving element in a scribe line region for separating each light receiving element. Manufacture of opto-semiconductor photodetectors characterized by measuring the photoreception characteristics of each photodetector with the cathode electrically short-circuited, and removing the diode when performing dicing division along the scribe line. Method. 3. The method for manufacturing an optical semiconductor light receiving element according to claim 2, wherein the optical semiconductor light receiving element is a photodiode, and the light receiving characteristic is an optical short circuit current.