JPH05102447A - Semiconductor sensor - Google Patents

Abstract

PURPOSE:To obtain a semiconductor sensor in which sensitivity is enhanced and stability of an amplifier is improved by forming a structure in which a capacitor and a sensor section are laminated on a driving circuit. CONSTITUTION:Since a driving circuit 10, a capacitor 30 and a sensor section 20 are so disposed in this order as to be longitudinally superposed on a single crystalline silicon substrate 1, an area of a photodiode to be formed of a lower electrode 31, a dielectric layer 32 and an upper electrode 33 can be reduced. Since a light is incident from the substrate 1 side to the sensor section 20, the light is incident to the section 20 without intermediary of the substrate, the sensitivity of a detecting wavelength range at a short wavelength side is not reduced by the substrate material, but the detecting wavelength range is increased. Further, the circuit 10 integrated on the substrate 1 is shielded by the electrodes 31, 33 and lead wiring 25 of the capacitor 30 thereby to highly integrate a semiconductor sensor and enhance sensitivity, thereby obtaining its stability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor sensor having a thin film laminated structure, which comprises a photosensor for reading out an optical signal and a sensor output amplifying section.

[0002]

2. Description of the Related Art Conventionally, as a photosensor having a photodiode, a structure for increasing the sensitivity of the photodiode and reducing the area of the entire sensor has been proposed.
A photosensor has been proposed in which a photodiode is formed on a glass substrate, a capacitor for accumulating charges is further laminated on the photodiode, and light is incident from the lower surface of the glass substrate (see Japanese Patent Laid-Open No. 59-138371). ..

On the other hand, as shown in FIG. 8, in order to amplify and extract the output from the photodiode, a semiconductor sensor having a structure in which the photodiode is laminated on an amplifier circuit integrated on the single crystal silicon substrate 1 has been proposed. I have (IEE
E Transactions on Electric
on Devices, VOL. 37, No. 6, JU
NE, 1990, pp1432-1438 references). This semiconductor sensor is composed of a single crystal silicon substrate 1, an amplifier 10 composed of a diffusion layer 2, an insulating film layer 3, a polycrystalline silicon 4 and a wiring layer 5, and a metal film formed on the amplifier 10 via an interlayer insulating film 6. It is composed of a lower electrode 7, a SiO ₂ film 8 a, a semiconductor layer 8 b, and a transparent electrode 9 formed of a transparent conductive film 9 which are stacked, and a sensor portion 20 which is a photodiode.

[0004]

However, the above-mentioned conventional structure has the following drawbacks. That is, according to the photo sensor, a photodiode and a capacitor for storing charges are sequentially laminated on a glass substrate,
Since the structure is such that light is incident from the lower surface of the glass substrate, it is affected when the incident light passes through the glass substrate, and when the incident light is detected by the photodiode, the short wavelength side of the detection wavelength band, especially in the ultraviolet range, is detected. The sensitivity was lost and it was disadvantageous for reading light in a wide wavelength range. In particular, when information about light in the ultraviolet region is required as in a sensor used for medical purposes, the sensitivity of light in the region is lost.

Further, when the sensor section 20 is laminated on the amplifier circuit 10 integrated on the single crystal silicon substrate 1, the parasitic capacitance of the photodiode is used as a substitute for the charge storage capacitor, so that high sensitivity is achieved. I can't. Furthermore,
Light is incident on the circuit element portion of the amplifier circuit 10 formed in the portion not covered by the lower electrode of the sensor portion 20, and the amplifier circuit 1 is latched up due to generation of unnecessary carriers.
There is a problem that the operation instability of 0 occurs.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor sensor capable of improving the sensitivity of the sensor and improving the stability of the amplifier circuit.

[0007]

In order to achieve the above object, a semiconductor sensor according to a first aspect of the present invention is characterized by including a drive circuit section having a semiconductor substrate, a sensor section, and a capacitor section. The sensor unit is provided on the drive circuit, senses light, and converts it into a charge amount. The capacitor section is provided between the drive circuit section and the sensor section,
At least a part of the light incident on the drive circuit unit is blocked, and electric charges from the sensor unit are accumulated.

According to a second aspect of the present invention, in the semiconductor sensor according to the first aspect, the drive circuit portion includes at least one first interlayer insulating film provided on the semiconductor substrate and a first interlayer insulating film formed on the first interlayer insulating film. And one wiring layer.

According to a third aspect of the present invention, a semiconductor sensor further comprises a second interlayer insulating film and a second wiring layer formed on the second interlayer insulating film, wherein the second wiring layer is And, blocking at least a part of the light incident on the drive circuit unit in combination with the capacitor unit.

According to a fourth aspect of the present invention, in the semiconductor sensor according to the first aspect, the drive circuit section has an analog circuit section for processing an analog signal from the sensor section and a digital circuit section for processing a digital signal. The capacitor section is characterized by blocking at least a part of the light incident on the analog circuit section.

According to a fifth aspect of the present invention, in the semiconductor sensor according to the first aspect, the semiconductor substrate is made of silicon single crystal.

According to a sixth aspect of the present invention, in the semiconductor sensor according to the first aspect, the sensor portion includes a lower electrode, a semiconductor layer formed on the lower electrode, and a translucent upper electrode formed on the semiconductor layer. It is characterized by being composed of and.

According to a seventh aspect of the present invention, in the semiconductor sensor according to the sixth aspect, the capacitor section has a capacitor electrode and a dielectric layer disposed between the capacitor electrode and the lower electrode of the sensor section. I am trying.

[0014]

According to the semiconductor sensor of the present invention, since the sensor portion is formed on the capacitor portion for charge storage, the area of the semiconductor sensor plane is determined by the area of either the sensor portion or the capacitor portion, The structure can be made advantageous for downsizing, high sensitivity, and high integration.
Further, since the capacitor section is provided between the drive circuit section and the sensor section so that the light enters from the side opposite to the semiconductor substrate,
Incident light is not affected by the semiconductor substrate material, and the detection wavelength band by the sensor unit is expanded.

Further, by using any one of the wiring layers of the sensor portion, the capacitor portion or the drive circuit portion or a combination thereof as a light shielding layer, at least a part of the light incident on the drive circuit portion is blocked. To do.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of the semiconductor sensor of the present invention will be described with reference to FIGS. 1, 2 and 3. 2 is a plan view of a semiconductor sensor for one pixel, and FIG. 1 is a cross-sectional view taken along the line AA of FIG. The semiconductor sensor includes a drive circuit unit 10 formed on a single crystal silicon substrate 1 serving as a semiconductor substrate and a sensor unit 2 for converting an optical signal into an electric signal.
0 and a charge storage capacitor section 30 for storing the converted electric signal. A plurality of semiconductor sensors are arranged in the front-back direction of FIG. 1 (the vertical direction of FIG. 2) to form a sensor array.

On the surface of the single crystal silicon substrate 1, four diffusion layers 11a, 11b, 11c and 11d and an insulating layer 12 made of SiO2 are formed, and the diffusion layers 11a, 11b and 11 are formed.
Polycrystalline silicon layers 13a, 13b and 13c which will be the gate electrodes of the transistors T1, T2 and T3 are provided between c and 11d.
Are formed. The diffusion layer 11a includes the sensor unit 20.
Is connected to the anode side of the photodiode and the lower electrode 31 of the capacitor section 30, and a wiring layer 14a is connected to the polycrystalline silicon layer 13b. A wiring 14b for supplying a constant voltage to the drive circuit 10 is connected to the diffusion layer 11b. Diffusion layer 11c
A wiring 14c which is an output line of the drive circuit unit 10 is connected to the. A control signal is applied to the polycrystalline silicon layer 13a via the wiring 14d, and a control signal is applied to the polycrystalline silicon layer 13c via the wiring 14e. An interlayer insulating film 16 is formed between each wiring layer 14.

On the drive circuit section 10, a capacitor section 3 is formed by sandwiching a dielectric layer 32, which is individualized for each pixel, between a lower electrode 31 and an upper electrode 33, which are also individualized for each pixel.
0 is formed. A semiconductor layer 21 and a transparent electrode 22 that are individualized for each pixel are stacked on the capacitor unit 30, and the transparent electrode 22 and the upper electrode 33 of the capacitor unit are stacked.
The semiconductor layer 21 is sandwiched between and to form the sensor unit 20 including a photodiode. A band-shaped common electrode 34 is connected to the upper electrode 32 of the capacitor unit 30 in the front-back direction of FIG. 1 (vertical direction in FIG. 2), and a bias voltage of a photodiode is applied to the common electrode 34. .. Further, the transparent electrodes 22 of the sensor section 20 are connected to the individual lead lines 25 via the contact holes 24 formed in the insulating layer 23, and the individual lead electrodes 2
3 is connected to the lower electrode 31 of the capacitor section 30. The entire semiconductor sensor is covered with a passivation film 26 for protection. In the photodiode that constitutes the sensor unit 20, the upper electrode 32 is connected to the capacitor unit 3
The lower electrode 31 and the lead wiring 25 connected to the transparent electrode 22 of the sensor unit 20 are connected in common with the electrode of No. 0. In addition, the lower electrode 31 and the upper electrode 32 of the capacitor section 30 and the lead wiring 25 allow the drive circuit section 10 to be formed.
Is shielded from light.

Therefore, the equivalent circuit diagram of the semiconductor sensor having the above structure is as shown in FIG.
0 and 0 are connected in parallel. The gate electrode 13b of the transistor T2 is connected to the sensor section 20 and the capacitor section 30 via the wiring 14a. Further, a constant voltage is applied to the wiring 14b connected to the transistors T1 and T2, and the transistors T1 and T3 are connected.
Since a clock signal (control signal) is alternately applied to the gates (polycrystalline silicon layers 13a and 13c) of the sensor via the wirings 14a and 14c, the potential of the anode side of the sensor unit 20 is It operates so as to transfer and amplify and output to the output terminal VC of the transistor T3.

Next, a manufacturing process of the semiconductor sensor having the above structure will be described. An insulating film 12 made of a thick SiO ₂ film is formed on the single crystal silicon substrate 1 using a mask in order to separate the device manufacturing region from other portions. The mask is removed and the whole is oxidized to form an interlayer insulating film 16a made of a thin oxide film. Next, polysilicon is deposited and patterned by photolithography and etching to form a polycrystalline silicon film 13. Next, the diffusion layer 11 is formed by implanting ions from above using the polycrystalline silicon film 13 and the mask. An interlayer insulating film 16b is deposited so as to cover the whole, and contact holes 17 are formed in the portions corresponding to the diffusion layers 11a, 11b, 11c by photolithography and etching. A metal film is deposited and patterned by photolithography and etching to form wirings 14a, 1
4b and 14c are formed. Further, an interlayer insulating film 16c is deposited for flattening.

After forming the contact hole 18 in the interlayer insulating film 16c corresponding to the wiring 14a, a metal film such as aluminum is evaporated and deposited, and patterned by photolithography and etching to become a part of the capacitor section 30. The shaped lower electrode 31 is formed. SiNx to C
A film is deposited by VD or the like and patterned by photolithography and etching to form the dielectric layer 32 of the capacitor section 30. Next, a metal film of aluminum or the like is evaporated and deposited, and patterned by photolithography and etching to form a rectangular upper electrode 33 that constitutes the capacitor unit 30.

Next, a semiconductor film is deposited by a CVD method, a transparent conductive film of indium tin oxide or the like is subsequently deposited and deposited, a resist pattern is formed by a photolithography method, and etching is performed using the resist pattern. The semiconductor layer 2 of the sensor unit 20 is patterned by processing.
1 and the transparent electrode 22 are formed.

After depositing an insulating film by the CVD method or the spinner method and patterning it by the photolithography and etching method to form the insulating layer 23 and the contact holes 24, a wiring material such as aluminum is vapor-deposited, and the photolithography and etching method is used. The lead wire 25 and the common electrode 34 are formed by patterning. Finally, a passivation film 26 is formed as a protective film so as to cover the whole.

According to the semiconductor sensor having the above-described structure, since the drive circuit section 10, the capacitor section 30, and the sensor section 20 are vertically stacked on the single crystal silicon substrate 1, the lower electrode 31 and the dielectric layer are arranged. The area of the photodiode formed by 32 and the upper electrode 33 can be made smaller than in the case where the sensor unit 20 and the capacitor unit 30 are formed on the same plane, and a highly sensitive, small-sized, highly integrated semiconductor is provided. A sensor can be realized. In addition, the anti-single crystal substrate 1
Since the light is made incident on the sensor unit 20 from the side, the light is incident on the sensor unit 20 without passing through the substrate, and the sensitivity of the short wavelength side of the detection wavelength region does not decrease due to the substrate material. It is possible to realize a semiconductor sensor having a wide wavelength range. Since the drive circuit unit 10 integrated on the single crystal silicon substrate 1 is shielded from light by the lower electrode 31 and the upper electrode 33 of the capacitor unit 30 and the lead wiring 25,
It is possible to prevent the optical influence on the portion other than the light receiving surface of the sensor unit 20 and ensure the stability of the drive circuit unit 10.

Further, since the photodiode of the sensor section 20 and the capacitor of the capacitor section 30 are connected in parallel as shown in FIG. 3, the dynamic range can be widened especially when used in the charge storage mode, The sensitivity of the photodiode can be improved. Further, the drive circuit 10 and the capacitor section 3 are formed on the single crystal silicon substrate 1.
Since 0 and the sensor unit 20 are integrated, the signal from the sensor unit 20 can be directly amplified and the SN ratio can be improved.

FIGS. 4 and 5 show another embodiment of the present invention, in which a semiconductor sensor is formed by using a two-layer metal process. FIG. 4 is a cross-sectional explanatory view taken along the line BB of FIG. In this embodiment, the two-layer wiring layer 19 is formed via the interlayer insulating film 16d to form a two-layer wiring structure. Therefore, a circuit that requires many elements such as an analog-digital converter can be integrated on the single crystal silicon substrate 1. That is, the capacitor section 30 and the sensor section 20 are formed on the digital circuit 10a of the drive circuit section 10 formed on the single crystal silicon substrate 1. In addition, the digital circuit 10 a and the analog circuit 10 of the drive circuit unit 10
The two-layer wiring layer 19, the lower electrode 31 and the upper electrode 33 of the capacitor section 30, the lead-out wiring 25 and the common electrode 34 connected to the sensor section 20 are used as a light-shielding layer for blocking b. Although the capacitor section 30 and the sensor section 20 are formed on the digital circuit 10a in this embodiment, it goes without saying that they may be formed on the analog circuit 10b. In the figure, the parts denoted by the same reference numerals as those in FIG. 1 constitute the same circuit part, and the description of each part and the manufacturing process will be omitted.

FIGS. 6 and 7 show another embodiment of the present invention, which uses a two-layer metal process as in FIGS. 4 and 5. FIG. 6 is a cross-sectional explanatory view taken along the line CC of FIG.
In this embodiment, the digital circuit 10a and the analog circuit 1
Each of the two wiring layers 19 and 19 forming 0b is extended to the center side, whereby the driving circuit of the digital circuit 10 of FIG.
A and the analog circuit 10b are shielded from light. Other configurations are the same as those of the semiconductor sensor of FIGS. 4 and 5, and therefore, the same reference numerals are given and the description thereof is omitted.

[0028]

According to the present invention, since the capacitor section and the sensor section are laminated on the drive circuit, the density of the sensor section can be increased and the signal from the sensor section can be directly amplified. Therefore, high integration and high sensitivity of the semiconductor sensor can be achieved. Further, by using the electrodes and wirings forming the sensor section, the capacitor section or the drive circuit section as a light-shielding film, the elements of the drive circuit section formed on the substrate can be protected from optical interference,
The stability of the semiconductor sensor can be ensured.

[Brief description of drawings]

FIG. 1 is a sectional explanatory view showing an embodiment of a semiconductor sensor according to the present invention.

FIG. 2 is a plan view of the semiconductor sensor of FIG.

FIG. 3 is an equivalent circuit diagram of a semiconductor sensor.

FIG. 4 is a cross-sectional explanatory view showing another embodiment of the semiconductor sensor.

5 is a plan view showing the entire semiconductor sensor of FIG. 4. FIG.

FIG. 6 is a cross-sectional explanatory view showing another embodiment of the semiconductor sensor.

7 is a plan view showing the entire semiconductor sensor of FIG.

FIG. 8 is a cross-sectional explanatory view of a conventional semiconductor sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Single crystal silicon substrate, 10 ... Drive circuit part, 10
a ... Digital circuit, 10b ... Analog circuit, 14 ... Wiring layer, 16 ... Interlayer insulating film, 19 ... Two-layer wiring layer, 2
0 ... Sensor part, 21 ... Semiconductor layer, 22 ... Transparent electrode,
23 ... Insulating layer, 25 ... Lead wiring, 30 ... Capacitor part, 31 ... Lower electrode, 32 ... Dielectric layer, 33
... Upper electrode, 34 ... Common electrode

Claims (7)

[Claims] 1. A drive circuit portion having a semiconductor substrate, a sensor portion provided on the drive circuit for receiving light and converting it into a charge amount, and provided between the drive circuit portion and the sensor portion. And a capacitor section for blocking at least a part of light incident on the drive circuit section and accumulating charges from the sensor section. 2. The semiconductor sensor according to claim 1, wherein
The drive circuit unit has at least one provided on the semiconductor substrate.
A semiconductor sensor comprising: one first interlayer insulating film; and a first wiring layer formed on the first interlayer insulating film. 3. The semiconductor sensor according to claim 1, wherein
A second interlayer insulating film and a second wiring layer formed on the second interlayer insulating film are provided, and the second wiring layer is at least partially incident on the drive circuit unit together with the capacitor unit. Sensor that blocks the light of. 4. The semiconductor sensor according to claim 1, wherein
The drive circuit unit includes an analog circuit unit that processes an analog signal from the sensor unit and a digital circuit unit that processes a digital signal, and the capacitor unit is at least a part of the light incident on the analog circuit unit. A semiconductor sensor that shuts off. 5. The semiconductor sensor according to claim 1, wherein
A semiconductor sensor whose semiconductor substrate is made of silicon single crystal. 6. The semiconductor sensor according to claim 1, wherein
The sensor unit is a semiconductor sensor including a lower electrode, a semiconductor layer formed on the lower electrode, and a translucent upper electrode formed on the semiconductor layer. 7. The semiconductor sensor according to claim 6,
A semiconductor sensor having a capacitor electrode and a dielectric layer disposed between the capacitor electrode and the lower electrode of the sensor unit.