JPS5833880A - Semiconductor photodetector - Google Patents

Abstract

PURPOSE:To enhance a photodetector by forming the shallow second conductive type impurity introduce layer on a region isolated from one main surface in the first conductive type semiconductor substrate and using the substrate semiconductor and two P-N junction surfaces with upper and lower surfaces of the layer as a photodetecting region. CONSTITUTION:An N type epitaxial Si layer 1 is formed on a P<-> type substrate 3, is surrounded by a P type isolation layer 4 and is electrically isolated from other element region. A P type layer 5 is formed by B ion implantation in a region isolated from the surface of the layer 1 in such a manner that impurity ion flying distance is deepened by increasing ion implantation energy, for example, up to appox. 200keV, and upper and lower P-N junctions (Xj1, Yj2) are by one ion implantation formed between the layer and an N type Si layer, a light incident from the surface of the element excites electrons-holes at the upper and lower P-N junction surfaces, thereby increasing the sensitivity and the area efficiency and improving the efficiency as a photodetector.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor light receiving element, a so-called photodiode.

When a source/t is applied to a semiconductor PN junction biased in the reverse direction, the electron-hole pairs are excited by the light, and the concentration of minority carriers becomes larger than the thermal equilibrium value, resulting in an increase in the reverse current. A photodiode (or phototransistor) used as a photo-electric conversion element is known. As shown in FIG. 1, a conventional photodiode for IC uses, for example, a shallow P-type layer 2 formed by implanting P-type impurities, such as B (boron) t- ions, into the surface of an N-type epitaxial layer 1. I am trying to increase the light receiving sensitivity. The ion implantation energy in this case was 75 KeV@JJi, and one pit was formed along the surface of the mold layer as shown in FIG.

Incidentally, as the integration of Xa becomes higher, higher density of photodiodes is required, but the above-mentioned I'N junction structure has poor area efficiency and it is difficult to achieve higher density.

The present invention solves the above problems, and its purpose is to improve the efficiency of the light receiving element.

The present invention will be described in detail below with reference to some embodiments.

Example 1 #3 and Figure 4 are examples of photodiodes according to the present invention [
show. 1 is formed on a P-type substrate 3 with 81% N-type epitaxial structure, and is electrically isolated from other device regions by being surrounded by a PWl isolation layer 4. 5 is a P-type layer formed in a region away from the surface of the layer 1 by B (boron) ion implantation, and the ion implantation energy t-
For example, by increasing the impurity ion range to 200°C, the range of impurity ions is deepened, and as shown in the $5gK example, two upper and lower PM junctions (xj,
.

Xj, ), and particles incident from the surface of the element excite electrons and holes at the upper PN junction surface and the lower PM junction surface, increasing the sensitivity and increasing the area. The efficiency increases, and the efficiency as a light receiving element becomes the same as above.

In the figure, 6 is a P+ diffusion layer (done during base diffusion) for taking out the electrode of the ion-implanted first layer 5,
An ohmic contact is established by the At electrode 7. 8 is M
This is an N+ diffusion (emitter diffusion) layer for taking out the MilA electrode, and is broken into ohmic contact by the Att electrode 9. 6 Example 2 FIGS. 6 and 7 show other examples of photodiodes according to the present invention. In this example, the same mask is used and high energy (
250KeV) and low energy (40KeV).
By repeatedly implanting B (boron) ions, two layers 2 and P layer 5' are formed sandwiching the N-type layer 1ali above and below. As a result, although the PM junctions are formed at three different depths as shown in FIG. 7, the area of the PM junction as a light-receiving surface increases by nearly three times, and high integration as well as light-receiving sensitivity can be expected.

Embodiment fl13 FIG. 118 and FIG. 9 show still other embodiments of the photodiode according to the present invention. This example uses the same mask and B
(Boron) ion implantation at high energy (200KeV)
) and low energy (50 Kev) to form 2nd layer 2 and 2nd layer 5, and then implant P (phosphorus) with the same mask to a depth between 2nd layer 2 and 1st layer 5. An N layer 11 is formed by performing ion implantation. This creates a PN junction (
Xj, ), N PM junction (x
jl), PM junction (Xj,)t between layer 1 5 and layer M 1
- Obtained. In this example, since the embodiment 2 has a regular shape with the addition of the rcN'' layer 11, the presence of this H layer 11 can reduce the electrical resistance to the N extraction portion B. Therefore, in this example, the light receiving sensitivity and The effect of increasing area efficiency can be expected.

The present invention is extremely effective when used in cameras, photoelectric switches, etc. with built-in photodiodes and light receiving/chip ○.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the basic structure of a conventional photodiode, and Figure 2 is a cross-sectional view showing the basic structure of a conventional photodiode. This is a curve diagram showing the impurity concentration distribution on the # plane. FIG. 3 is a plan view showing an embodiment of a photodiode according to the present invention, FIG. 4 is a sectional view taken along line A-A of FIG. aI3, FIG. 5 is an impurity concentration-1 diagram corresponding to FIG. 4, and FIG. is a sectional view showing another embodiment of the photodiode according to the present invention, FIG. 7 is an impurity concentration distribution curve diagram corresponding to FIG. 6, and FIG. 8 is a sectional view showing another embodiment of the photodiode according to the present invention.
FIG. 9 is an impurity concentration distribution curve diagram corresponding to FIG. 8. l...M'f! ! ! Epitaxial Si layer, 2...
P-type ion implantation layer, 3...P-type 81 substrate, number...
・P type isolation, 5...FW ion implantation layer, 6...P+ type diffusion layer, 7...AAt pole, 8-...
N-type diffusion layer, 9...m electrode, 10... absolutely film,
11...N type ion implantation layer. Agent Patent Attorney Bo 1) Li Xin Figure 1 Chain 2 Diagram η ′ Surface s'1us9 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. Five main surfaces within a first conductivity type semiconductor substrate. A shallow second conductivity type impurity-introduced layer was entirely formed in a region away from the semiconductor light-receiving element to form two PM junction surface receiving regions formed by the base semiconductor and the upper and lower surfaces of the impurity-introduced layer. . 2. Form a shallow first layer on the main surface of the first conductivity type semiconductor substrate by introducing impurities of the second conductivity type, and form a second layer by introducing impurities into the semiconductor substrate away from the first layer into the semiconductor substrate. - A semiconductor light-receiving element in which 20 layers are formed shallowly, and the light-receiving regions are the lower surface of the first layer, the upper and lower surfaces of the second layer, and the base semiconductor. 3. Form a shallow first layer on the main surface of the first conductive substrate by introducing impurities of the second conductivity type, and form a second layer by introducing impurities of the second conductivity type into the substrate away from the first layer. When the layer is formed shallowly, #C-th layer and I! ! The first layer is different from the second layer.
A shallow @3 layer is formed by introducing a conductivity type impurity, and the top surface of the third layer and the third layer, the top surface of the third layer and the second layer, and the second layer are formed.
A semiconductor light-receiving element characterized in that the entire light-receiving area is formed by three PM junction surfaces formed by the lower surface of the layer and the base semiconductor.