JPS6084076A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To prevent uniformity of sensitivity to a long wavelength light and deterioration of resolution by providing a region having a high impurity consentration than that of a substrate and poled the same as the semiconductor substrate to a part below a photoelectric converting region. CONSTITUTION:A transparent insulation film 2 is provided on a p type substrate 11. Moreover, a BCD (bulk transfer charge transfer element) electrode 3, a storage gate electrode 4, a transfer gate electrode 5, an n<+> diffusion layer 6 being a photoelectric converting section, an n type layer 7 being a channel of the BCD and a p type high concentration region 8 are formed. In figure, 9 indicates an incident light. Then the said region 8 is provided in contact with the n<+> diffusion layer 6. The life of the carrier is short in the region and the spread of depletion layer of p-n junction is small, then the signal carrier subject to photoelectric conversion at the depth in the semiconductor with the light of a long wavelength does not reach the n<+> diffusion layer 6. Thus, the local ununiformity of the sensitivity to the long wavelength light due to the said signal carrier and the deterioration of resolution are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a diode array in the light receiving section and uses a charge transfer element (ChargeTransf) as a readout register.
The present invention relates to a solid-state imaging device equipped with an er device.

In FIG. 1, IJ is a p-type substrate (for example, 81 substrate),
2 is a transparent insulating film, 3 is an electrode of BCD (bulk transfer type charge transfer device), 4 is a storage gate electrode, 5 is a transfer gate electrode, 6 is n÷diffusion layer which becomes a photoelectric conversion part, and 7 is a channel of BCD l 7'j: n-type layer, 8 is p-type high concentration region, 9
indicates the incident light.

In the solid-state imaging device having the structure shown in FIG. 1, the p-type high concentration region 8 is provided in contact with the n+ diffusion layer 6.

In this region, the lifetime of carriers is short and the extent of the depletion layer of the p-n junction is small, so signal carriers that are photoelectrically converted deep inside the semiconductor by light on the long wavelength side are
+Does not reach the diffusion layer 6. Conventionally, signal carriers excited deep inside a semiconductor by the above-mentioned long-wavelength light were the main cause of local non-uniformity in sensitivity to long-wavelength light and deterioration of resolution. The solid-state imaging device having the structure shown in the figure exhibits good characteristics in this respect.

Furthermore, since the capacitance of the pn junction becomes large, the signal retention ability of the n+ diffusion layer is also high.

In FIG. 1, an accumulation gate 4, a transfer gate 5, a BCD 3
Since it is better to lower the concentration of the p-type substrate 11 under each electrode for reasons such as reducing the substrate effect, the p-type high concentration region 8
is preferably limited to the diffusion layer 60 portion.

FIG. 2 shows another embodiment of the present invention, in which a p-type semiconductor substrate l is formed on an n-type semiconductor substrate 21, and an n+ Diffusion layer 6, B
An n-type layer 7 that becomes a channel of CD is provided, and a p-type substrate 1 is provided.
A p-type high concentration region 8 is provided under the n+ diffusion layer 6 inside the.

This structure is such that signal carriers generated deep inside the semiconductor substrate 1 are absorbed toward the n-type substrate 21 by applying a reverse bias between the n-type substrate 21 and the p-type substrate l. In the structure shown in Figure 2, in addition to this,
The strong light hits me! When 1 carriers are generated under the n+ diffusion layer 6, plumping can be suppressed by absorbing them toward the n-type substrate 21 side. The structure shown in FIG. 2, together with the effect of the p-type high concentration region 8, is a solid-state imaging device that has excellent features in terms of nonuniformity, resolution, signal retention ability, and blooming suppression.

Here, in the embodiments of the present invention, a storage gate is provided in contact with the n+ diffusion layer, but it is clear that the present invention can also be applied to a solid-state imaging device having a structure without such a storage gate.

FIG. 3 shows an embodiment of the present invention in which a surface transfer type charge transfer device (S-COD) is used as the charge transfer device.

FIG. 4 shows an example in which the present invention is applied to a solid-state imaging device in which a MOS diode array is provided in the light receiving section.

The semi-transparent electrode 31 forms an MO8 capacitor which also serves as a light receiving section and an accumulation section. Since there is a high-concentration p-shade region 8 in the light receiving part and an n-type semiconductor 21 under the p-type semiconductor l, it is excellent in terms of non-uniformity and blooming suppression, as explained in FIGS. 1 and 2. It has the following characteristics.

In the embodiments shown in FIGS. 1 to 3, it is of course possible to optically shield parts other than the light receiving part as necessary, but as shown in FIG. In the case of a diode array, since there is no difference in light transmittance between the light receiving section and the storage section, it is desirable to have a light shield as shown in 32.

FIG. 5 is a diagram illustrating the planar structure of the embodiment of the present invention shown in FIGS. 1, 2, and 3. In m, 41 is a diode array, 42 is a storage gate, 43 is a transfer gate, 4
Reference numeral 4 denotes a charge transfer element, in which signal charges flow as shown by arrows 45 to 47, are transferred to the charge transfer element, and are transferred in the direction shown at 48 to reach the output section. 1, 2, and 3 are cross-sectional views of the portion indicated by 49-50. 51 is a p-type high concentration region in contact with the diode array.

However, as shown in the figure, 51 is not common to all picture elements,
Each picture element may be electrically independent.

The planar structure of the embodiment shown in FIG. 4 is also similar to that shown in FIG. Fourth
The device of the illustrated embodiment differs in that the diode array 41 in FIG. 5 has an MO8 structure.

Although FIG. 5 shows a -dimensional diode array, it is of course possible to arrange the photodiodes two-dimensionally and configure the device of the present invention as a two-dimensional sensor.

[Brief explanation of drawings]

1, 2, 3, and 4 show sectional views of an apparatus according to an embodiment of the present invention, and FIG. 5 is a diagram showing a planar layout of an apparatus according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 11... P-type semiconductor curtain plate, 21... N-type semiconductor substrate, l... P-type semiconductor substrate, 2... Insulating film, 3, 4.
5... Electrode, 6... n+ expansion layer (photoelectric conversion section), 7
. . . n-type layer (channel of BCD), 8 . . . p-type high concentration region. Suiri 1 Zuten 2 eyes, S yl, 51! I (Marriage 5 Figure 9

Claims (1)

[Claims] 1. A semiconductor substrate, a photoelectric conversion region provided on a surface region of the semiconductor substrate, a charge transfer element provided on another surface region of the semiconductor substrate, and below the photoelectric conversion region a region having the same conductivity type as the semiconductor substrate and having a higher impurity concentration than the semiconductor substrate provided in at least a portion of the semiconductor substrate, and inputting the optical signal charge detected in the photoelectric conversion region to the charge transfer element. , A solid-state imaging device characterized in that the signal charge is read out by the charge transfer element. 2. A semiconductor substrate of a first conductivity type, a semiconductor substrate of a second conductivity type provided on the semiconductor substrate, a photoelectric conversion region of a first conductivity type provided in a surface region of the semiconductor substrate, and the semiconductor substrate. a charge transfer element provided on another surface area of the base; and a second charge transfer element provided on at least a portion below the photoelectric conversion area.
a conductive type region with a higher impurity concentration than the semiconductor substrate, and the optical signal charge detected in the photoelectric conversion region is
A solid-state imaging device characterized in that the signal charge is input to the charge transfer element and read out by the charge transfer element. 3. a semiconductor substrate of a first conductivity type, a semiconductor substrate of a second conductivity type disposed on the semiconductor substrate, a photoelectric conversion region of a first conductivity type provided in a surface region of the semiconductor substrate; a charge transfer element consisting of a channel region of type i4 provided on another surface region of the semiconductor substrate and an electrode provided on the channel region via an insulating film; and at least a portion under the photoelectric conversion region. The optical signal charge detected in the photoelectric conversion region is input to the charge transfer element, and the signal charge is transferred to the charge transfer element by the charge transfer element. A solid-state imaging device that reads out . 4. A storage gate electrode is provided between the photoelectric conversion region and the charge transfer element via an insulating film, and the optical signal charge detected in the photoelectric conversion region is transferred to the charge transfer element through the bottom of the storage gate electrode. The solid-state imaging device according to claim 1, 2, or 3, wherein the signal charge is input and read out by the charge transfer element.