JPS63138784A - Semiconductor photodetector - Google Patents

Abstract

PURPOSE:To make it possible to reduce significantly the crosstalk of split photo diodes by a method wherein a gap is formed between first conductivity type diffused layers corresponding to the arrangement of second conductivity type diffused layers. CONSTITUTION:A gap C is formed in first cnductivity type buried and diffused layers 2 at a position coresponding to the arranged positions of second conductivity type diffused layers 5. A first conductivity type epitaxial layer 3 and a second conductivity type substrate 1 are junctioned to each other in this gap C. Hereby, a rate at which carriers reach the junction between the second conductivity type substrate 1 and the first conductivity type epitaxial layer 3 in the gap C is increased and a rate at which carriers reach the junction of a photo diode (a photo diode B, for example) other than a photo diode (a photo diode A, for example), wherein light is projected, is significantly reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a semiconductor light-receiving element comprising a divided photodiode.

<Prior Art> Recently, in video disc devices and the like, split photodiodes have been used to pick up focus signals and optical signals from the disc.

The cross-sectional structure of a conventional split photodiode is shown in Figure 3.
Its planar structure is shown in FIG. In the figure, 11 is a second conductivity type substrate, 12 is a first conductivity type buried diffusion layer, 13 is a first conductivity type epitaxial layer, 14 is a first conductivity type diffusion layer,
15 is a second conductivity type diffusion layer. A photodiode is configured by the junction between the first conductivity type epitaxial layer 13 and the second conductivity type diffusion layer 15. The second conductivity type diffusion layer 15 is 4
Since the photodiode is divided into four parts, a photodiode divided into four parts is formed.

<Problems to be Solved by the Invention> In split photodiodes used in video disc devices to pick up focus signals and optical signals from discs, crosstalk occurring between each photodiode can lead to malfunction, especially for focus signals. I don't want it to become a cause.

In the conventional structure of the split photodiode shown in Fig. 3, the ratio of carriers generated in photodiode A reaching the junction of photodiode B and becoming the photocurrent of photodiode B (crosstalk) is quite high. It was causing problems.

Means for Solving the Problems> The present invention provides an epitaxial layer of a first conductive type and a second conductive layer divided into a plurality of layers on a substrate of a second conductive type having a diffusion layer of a first conductive type.
A semiconductor light-receiving element formed by bonding with a conductive type diffusion layer is characterized in that a gap is formed in the first conductive type diffusion layer corresponding to the arrangement of the second conductive type diffusion layer.

<Function> In the semiconductor light-receiving device according to the present invention, in the gap between the first conductivity type diffusion layers, carriers have a high rate of reaching the junction between the 2'i4 electric substrate and the first conductivity type epitaxial layer in this gap, Crosstalk can be reduced.

<Example> Figure 1 shows the cross-sectional structure of the semiconductor photodetector of this example.
FIG. 2 shows the planar structure. In the figure, 1 is the 211th L
2 is a buried diffusion layer of a first conductivity type, 3 is an epitaxial layer of a first conductivity type, 4 is a diffusion layer of a first conductivity type, and 5 is a diffusion layer of a second conductivity type.

221st! A first conductivity type buried diffusion N2, a first conductivity type epitaxial layer 3 and a second conductivity type diffusion layer 5 are formed on the conductivity type substrate 1.
It has a layered structure. The first conductivity type diffusion layer 4 surrounds four photodiodes formed by the junction between the first conductivity type epitaxial layer 3 and the second conductivity type diffusion layer 5 divided into four parts.

In the first conductivity type buried diffusion layer 2, a gap C is formed at a position corresponding to the arrangement of the second conductivity type diffusion layer 5.

In this gap C, the first conductivity type epitaxial layer 3 and the second
The conductive type substrate 1 is bonded to the conductive type substrate 1.

In the divided photodiode, carriers generated deep in the first conductivity type epitaxial layer 3 near the boundary with the divided photodiode have a large effect on crosstalk. For this carrier, the first conductivity type diffusion N
2 has a high potential, so the carriers are reflected and the photodiode (for example, photodiode A) where light enters.
The photocurrent reaches other junctions (for example, photodiode B) and becomes a photocurrent, resulting in crosstalk. However, in the present invention, a gap C is formed at a position corresponding to the divided arrangement of the second conductive type diffusion layer 5 of the first conductive type buried diffusion layer 2,
Therefore, the proportion of carriers reaching the junction between the second conductivity type substrate 1 and the first conductivity type epitaxial layer 3 in the gap C increases, and the carriers reach the junction between the second conductivity type substrate 1 and the first conductivity type epitaxial layer 3 in the gap C, and the carriers reach the junction between the second conductivity type substrate 1 and the first conductivity type epitaxial layer 3 in the gap C, and the carriers reach the junction between the second conductivity type substrate 1 and the first conductivity type epitaxial layer 3 in the gap C, and the carriers reach the junction between the second conductivity type substrate 1 and the first conductivity type epitaxial layer 3 in the gap C. For example, the proportion of carriers reaching the junction of photodiode B) is significantly reduced.

It goes without saying that the present invention is applicable not only to a single light-receiving element but also to a light-receiving element having multiple functions including a signal processing circuit and the like.

<Effects of the Invention> As explained above, according to the present invention, by forming a gap in the first conductivity type buried diffusion layer, crosstalk between the split photodiodes can be significantly reduced. Further, since it can be manufactured by simply changing the pattern of the first conductivity type buried diffusion layer in the conventional manufacturing process, the cost does not increase.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the cross-sectional structure of the embodiment of the present invention, Fig. 2 is a diagram showing the planar structure of the embodiment of the invention, Fig. 3 is a diagram showing the cross-sectional structure of the conventional example, and Fig. 4 is the diagram of the conventional example. FIG. 3 is a diagram showing a planar structure. 1... Second conductivity type substrate 2... First conductivity type buried diffusion layer 3... First conductivity type epitaxial layer 4... First conductivity type diffusion layer 5... Second conductivity type diffusion Layer patent applicant, Sharp Corporation agent
Patent Attorney Nishi 1) New Figure 1 Noyo Hikari, Heyarya Figure 2 Figure 3 I Yu Hikari, λ Ya 11 Ma Figure 4

Claims (1)

[Claims] In a semiconductor light-receiving element formed by joining a first conductivity type epitaxial layer and a second conductivity type diffusion layer divided into a plurality of parts on a second conductivity type substrate having a first conductivity type diffusion layer, the second conductivity type A semiconductor light-receiving element comprising a gap formed in the first conductivity type diffusion layer corresponding to the arrangement of the diffusion layer.