JP3912024B2 - PIN type lateral type semiconductor photo detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lateral semiconductor light-receiving element having a PIN structure.
[0002]
[Prior art]
In the vertical photodiode in which the pn junction surface is formed parallel to the semiconductor substrate surface, light is incident on the depletion layer through the p layer or the n layer, whereas the pn junction surface is in contact with the semiconductor substrate surface. In the lateral photodiode formed vertically, light is directly incident on the depletion layer (without passing through the p layer or the n layer). Therefore, the lateral type photodiode is more advantageous in light receiving efficiency than the vertical type photodiode.
[0003]
Conventionally, in a photodiode, an i layer (intrinsic layer) is provided between a p layer and an n layer to thicken a depletion layer. In the vertical photodiode having such a PIN structure, in order to increase the light receiving sensitivity, the i layer is formed to have a thickness greater than the absorption length. As a result, a quantum efficiency of 70% or more can be obtained at wavelengths of around 700 nm to 870 nm.
[0004]
A lateral photodiode with a PIN structure (a photodiode in which the interface between the i layer, the p layer, and the n layer of the PIN structure is formed perpendicular to the surface of the semiconductor substrate) has, for example, an extremely thin impurity concentration forming the i layer. After the region is provided in the surface layer portion of the semiconductor substrate, the p layer and the n layer are formed by adding and diffusing a p-type impurity and an n-type impurity from the upper surface to each position at a predetermined interval in the region. , By leaving between both layers as an i-layer.
[0005]
Therefore, in the case of a lateral type photodiode having a PIN structure, if it is attempted to increase the thickness of the i layer (depth from the light incident surface), it is necessary to form the p layer and the n layer deeply. In order to form the p layer and the n layer deeply while maintaining the width of the i layer (distance between the p layer and the n layer) uniformly in the thickness direction of the substrate, the p layer and the n layer on the substrate surface It is necessary to take a large distance. When the distance between the p layer and the n layer on the substrate surface is increased, the width of the i layer is increased. When the width of the i layer is large, the moving distance until the electrons generated on the p layer side of the i layer reach the electrode of the n layer becomes long, and the response speed becomes slow.
[0006]
Therefore, in the lateral type photodiode having the PIN structure, it is not possible to simply adopt increasing the thickness of the i layer (depth from the light incident surface) as a method for increasing the light receiving sensitivity. Therefore, as a method of increasing the light receiving sensitivity of the lateral photodiode having the PIN structure, it is effective to provide an antireflection film on the upper surface of the i layer to increase the incident efficiency to the i layer.
[0007]
[Problems to be solved by the invention]
However, a lateral photodiode having a PIN structure having an antireflection film on the upper surface of the i layer has a problem that the response speed is low when an element that receives a high-speed signal is used.
The present invention has been made paying attention to such problems of the prior art, and it is an object of the present invention to improve the light receiving sensitivity without reducing the response speed in a lateral type semiconductor light receiving element having a PIN structure.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention converts the light incident on the i layer into a current by forming an interface between the i layer, the p layer, and the n layer of the PIN structure perpendicular to the semiconductor substrate surface. A lateral semiconductor light-receiving element having a PIN structure is provided, in which a dye layer having a photoelectric conversion function is provided on an upper surface and / or inside an i-layer forming a light-receiving region. .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a sectional view showing a photodiode corresponding to one embodiment of the present invention. FIG. 2 is a diagram showing an example of a planar shape when the photodiodes of this embodiment are formed in an array. 1 corresponds to a cross-sectional view taken along line AA in FIG.
[0010]
This photodiode is a lateral type photodiode (semiconductor light receiving element) in which a PIN structure is formed perpendicular to the substrate surface of a silicon substrate (semiconductor substrate) 1, and a portion (p) forming a light receiving region 2 of the i layer 15. A dye layer 4 having a photoelectric conversion function is provided on the upper surface of a portion sandwiched between the layer 5 and the n layer 7.
A p-electrode 6 and an n-electrode 8 are formed on the upper surfaces of the p-layer 5 and the n-layer 7, respectively. The surface between the electrodes 6 and 8 is the light receiving surface 3, and the dye layer 4 is formed between the electrodes 6 and 8 with an insulating layer 91 interposed therebetween. The insulating layer 91 is necessary to prevent conduction between the electrodes 6 and 8 by electrons generated by photoelectric conversion of the dye layer 4.
[0011]
An element protective layer 9 made of a silicon oxide film or the like is formed with a predetermined thickness on the upper surface of the silicon substrate 1 except for the positions of the electrodes 6 and 8, the dye layer 4, and the insulating layer 91. A p-electrode 11 is formed on the lower surface of the silicon substrate 1.
This photodiode can be manufactured, for example, by the following method.
First, an n-well (region with a very low impurity concentration) 10 is provided in the surface layer portion of the p-type silicon substrate 1. Next, a p-type impurity is added to one of the two regions of the n-well 10 that are spaced apart from each other, and an n-type impurity is added to the other to diffuse. As a result, the p layer 5 and the n layer 7 are formed in the n well 10, and the portion between the p layer 5 and the n layer 7 of the n well 10 remains as the i layer 15. Next, after forming the electrodes 6 and 8 on the p layer 5 and the n layer 7, the element protective layer 9 is formed.
[0012]
Next, after removing the element protection layer 9 between the electrodes 6 and 8, a narrow insulating layer 91 in contact with the electrodes 6 and 8 is formed. Alternatively, when the element protective layer 9 is removed, the element protective layer 9 on the electrodes 6 and 8 side is left a little as the insulating layer 91. Next, the dye layer 4 having a photoelectric conversion function is formed in a portion surrounded by the insulating layer 91 on the upper surface of the i layer 15.
Examples of the dye having a photoelectric conversion function include porphyrins (such as heme), phthalocyanines, and rhodopsins (such as bacteriorhodopsin), and those having high response speed and sensitivity are preferably used. Examples of the method for forming the dye layer 4 include Langmuir-Blodget method (LB method), spin coating method, and ink jet method.
[0013]
This photodiode applies a reverse bias voltage by connecting a power source with the n layer 7 side positive between the n electrode 8 in contact with the upper surface of the n layer 7 and the p electrode 11 on the lower surface of the substrate 1. By connecting the p-electrode 6 in contact with the upper surface of the layer 5 to the output circuit, the light incident on the i-layer 15 from the light receiving surface 3 can be converted into a current and detected.
Of the light incident on the light receiving surface 3, the light absorbed by the dye layer 4 is photoelectrically converted by the photoelectric conversion function of the dye layer 4, and the generated electrons pass through the i layer 15 and the n layer 7 to form the n electrode 8. To. The light that has passed through the dye layer 4 is incident on the i layer 15, undergoes photoelectric conversion in the i layer 15, and the generated electrons pass through the n layer 7 and reach the n electrode 8.
[0014]
Therefore, according to this photodiode, the light receiving efficiency can be increased as compared with the case where the dye layer 4 is not formed on the i layer 15. Further, the response speed is faster than that in which an antireflection film is formed on the i layer 15 instead of the dye layer 4.
Also, according to this photodiode, the effect that the dye layer 4 is formed by an ink jet method or the like can be easily manufactured as compared with the case of forming the antireflection film. Furthermore, it becomes possible to detect only light of a predetermined wavelength by utilizing the wavelength selectivity of the material forming the dye layer 4. Further, the light receiving sensitivity can be easily improved by setting the absorption coefficient of the dye to be used and the film thickness of the dye layer 4.
[0015]
The dye layer 4 may be provided on the upper surface and / or inside the i layer 15 forming the light receiving region 2. For example, as shown in FIG. 3, after forming the p layer 5 and the n layer 7, the concave portion 41 is formed in the surface layer portion of the i layer 15, and the concave portion 41 and the region surrounded by the insulating layer 91 are formed. Alternatively, the dye layer 4 may be provided only in the recess 41. Further, as shown by a two-dot chain line in FIG. 3, a structure in which the dye layer 40 is provided inside the i layer 15 and the i layer 15 is also provided on the upper surface of the dye layer 40 may be employed. However, when the dye layer 4 is provided in the i layer 15, the i layer 15 is present between the dye layer 4 and the p layer 5 and the n layer 7, and between the p layer 5 and the n layer 7. It is necessary to apply a reverse bias voltage.
[0016]
In this embodiment, a lateral photodiode having a PIN structure is described. However, the lateral semiconductor light receiving element having the PIN structure of the present invention is not limited to this, and the base and collector portions have a PIN structure. The present invention is also applied to a lateral phototransistor or the like.
[0017]
【The invention's effect】
As described above, according to the lateral type semiconductor light receiving element of the PIN structure of the present invention, the light receiving sensitivity can be improved without lowering the response speed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a photodiode corresponding to one embodiment of the present invention, and corresponds to a cross-sectional view taken along line AA in FIG.
FIG. 2 is a diagram showing an example of a planar shape when the photodiodes of FIG. 1 are formed in an array.
FIG. 3 is a cross-sectional view showing a photodiode corresponding to another embodiment of the present invention.
[Explanation of symbols]
1 Silicon substrate (semiconductor substrate)
10 n-well 11 p-electrode 15 i-layer 2 light-receiving region 3 light-receiving surface 4 dye layer 40 having a photoelectric conversion function dye layer 5 having a photoelectric conversion function p-layer 6 p-electrode 7 n-layer 8 n-electrode 9 element protection layer 91 insulating layer

Claims (4)

In the lateral type semiconductor light-receiving element in which the interface between the PIN layer i layer, the p layer, and the n layer is formed perpendicular to the semiconductor substrate surface, and the light incident on the i layer is detected by converting it into a current.
A lateral type semiconductor light-receiving element having a PIN structure, wherein a dye layer having a photoelectric conversion function is provided on an upper surface and / or inside of an i layer forming a light-receiving region. Electrodes,
A semiconductor substrate electrically connected to the electrode;
A lateral photodiode disposed above the semiconductor substrate and having an interface between the i layer, the p layer, and the n layer of the PIN structure formed perpendicular to the semiconductor substrate surface;
A p-electrode provided on the upper surface of the p-layer;
An n-electrode provided on the upper surface of the n-layer;
A dye layer provided on the upper surface of the i layer and having a photoelectric conversion function;
An insulating layer that insulates the p-electrode and the n-electrode from the dye layer;
A lateral type semiconductor light-receiving device having a PIN structure. In claim 1 or 2,
The lateral type semiconductor light-receiving element having a PIN structure, wherein the dye layer includes at least one of porphyrins, phthalocyanines, and rhodopsins. In any one of Claims 1-3,
The p-electrode and the n-electrode are lateral semiconductor light-receiving elements having a PIN structure, in which the planar shape is a comb shape.

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