JPH01199466A - Solid-state image sensing device and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce the blooming or smearing defect and to miniaturize a device by a method wherein a light-screening film is provided on a charge transfer section and, further thereon, a photodiode is provided. CONSTITUTION:A device of this design is constituted of a semiconductor substrate 1, a charge transfer section consisting of an electrode 8 provided on the substrate 1 through the intermediary of an insulating film 7, a light-screening film 10 provided on the charge transfer section, a photodiode 16a provided on the light-screening film 10, and a connecting section 19 connecting the photodiode 16a and the charge transfer section. That is, it is so designed that a charge transfer section is constituted when the electrode 8 is provided on the semiconductor substrate 1 through the intermediary of the insulating film 7, the light- screening film 10 is formed thereon, a part of the substrate 1 is allowed to expose, and the exposure is utilized as a seed crystal for the formation of a singlecrystal semiconductor film on the light-screening film 10, the photodiode 16a is formed in the single-crystal semiconductor film, and the photodiode 16 is connected to the charge transfer section.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention is applied to charge coupled devices (Charge Coupled Devices).
The present invention relates to a solid-state imaging device using a dDevice (hereinafter referred to as CCD) and a manufacturing method thereof.

←) A problem with solid-state imaging devices using conventional technology COD is that when excess charge exceeding the maximum transfer charge amount generated by strong light irradiation exceeding a predetermined illuminance flows into the surrounding signal transfer section or adjacent photoelectric conversion section. and the blooming phenomenon that occurs,
There is a smear phenomenon that occurs when charges generated deep from the incident surface due to long-wavelength incident light diffuse laterally and enter the surrounding transfer section or adjacent photoelectric conversion section.

These phenomena deteriorated the imaging screen.

Among these, in order to prevent the pluming phenomenon tl-, it has been proposed to provide an over 7o-drain structure.

Figure 7 National Technical Report as one of such overflow drain structures
1 is a cross-sectional view showing one pixel of a solid-state imaging device having a vertical over-7 μm drain structure, which is shown in an article entitled “Small CCD imaging device” published in Vol. 31 No. I Feb. 1985.

fυ is an n-type silicon substrate, Vυ is an n-type silicon substrate Vα
The p-type silicon layer laminated on top, σ2 is a silicon oxide film, V is a transfer electrode provided on the silicon oxide film 2, and V is an insulating film above the transfer electrode ff3) via an insulating film υ. A transfer electrode (an n-type channel region provided opposite to 73, V″I) is formed on the surface of a light shielding film provided, σe is a p-type silicon layer (G), and a transfer electrode is formed on the surface area of the mill-type silicon layer υ. This n+ type diffusion region ση is provided so as not to face between the transfer electrodes, and this n+ type diffusion region ση forms a p-type silicon layer υ and a photodiode σ9. p provided between the diffusion region and
Type transfer game area, - is n-type channel area ff1le
A p+ type channel stop region provided adjacent to the p+ type channel stop region. With these, one pixel is divided into grooves. The pixels having such a configuration are arranged in parallel in the direction perpendicular to the paper surface. 51) is a silicon substrate Qα and a silicon layer ff1
) is a power supply that reverse biases between

In such a structure, the p-type silicon layer (71) in the photodiode decoy portion is depleted by the power supply (8υ).

Then, when the transfer electrode V is biased to the maximum positive voltage while charges are accumulated due to light incident on the photodiode 7 barrel, the charges accumulated in the photodiode 4 are transferred to the n-type channel region. This part is read out.

The charges read out in this way are transferred along the pixels arranged perpendicularly to the paper by alternately biasing the transfer electrodes of each pixel arranged perpendicularly to the paper with an intermediate voltage and a low voltage. be transferred.

By the way, the potential of the p-type silicon layer σl) in the portion of the photodiode 71)G is always the p-type transfer gate region, 79
) The voltage of the power supply βυ is adjusted so that it is deeper than the potential of the part. Therefore, when charges are accumulated in the photodiode μs, excessive charges do not flow toward the n-type channel region 1FQ, but are absorbed by the n-type silicon substrate υ.

With such a structure, the pluming phenomenon does not occur even if light with an illuminance 200 times higher than the predetermined illuminance is irradiated.

f→ Problems to be Solved by the Invention However, even with such a structure, the blooming phenomenon cannot be sufficiently suppressed, and the same is true for the smear phenomenon.

On the other hand, in the above structure, since the photodiode decoy that receives incident light and the transfer electrode are arranged in parallel, the entire device is It is impossible to reduce the size of the device.

(b) Means for Solving the Problems The solid-state imaging device of the present invention includes a charge transfer section consisting of a semiconductor substrate and an electrode provided on the substrate with an insulating film interposed therebetween;
A light shielding film provided above the charge transfer section, a photodiode provided above the light shielding film, and a connection section connecting the photodiode and the charge transfer section. shall be.

Furthermore, the method for manufacturing a solid-state imaging device of the present invention includes a step of forming a charge transfer section by providing an electrode on a semiconductor substrate via an insulating film, and a step of forming a light shielding film above the charge transfer section. And a part of the semiconductor substrate f! : forming a single crystal semiconductor film above the light shielding film by exposing and using this exposed part as an fJ@ product;
The method is characterized in that it includes a step of forming a photodiode in the single crystal semiconductor film, and a step of connecting the photodiode and the charge transfer section.

(E) Function According to the solid-state imaging device according to the present invention, the charge generated in the photodiode is carried and transferred only to the charge transfer section located directly below the photodiode.

(F) Embodiment FIGS. 1 to 6 are cross-sectional views showing one pixel according to the manufacturing process according to an embodiment of the present invention.

In the process shown in FIG. 1, an n-type silicon substrate (1) is selectively oxidized to form an insulating isolation region (2) made of silicon dioxide.
form. After that, by normal LSI process,
On the surface of the p-type silicon substrate 1), a p-type channel stop region (31), an n-type signal input region (4), and a p-medium transfer gate region (51) are arranged in order from one insulating isolation region (2) side. , an n-type buried channel region (6) and a p-type channel stop region (3), and a p-type medium transfer gate region (5) via a 5i02 film (7).
and a polycrystalline silicon transfer electrode (8) is placed above the n-9 buried channel region (6). In the process shown in Fig. 2, the film thickness o,
The first P S G of sp m (Phosph.

-3i1icate ()I! ass) film (9), insulating isolation region (2), 5i02 film (7) and transfer electrode (8).
), a light shielding MoC molybdenum film (
1G is formed on the first PSG film (9). After that, R
I E (React ive Ion Etchin
The MO film αα is selectively etched using the P) method, and the Mo film (10
) to remain.

At the factory shown in Figure 6, the temperature was raised to 450°C using the CVD method.
The second PEG film (1) with a film thickness of o, s μm in the state of 1
All, 1st (DP S Gl [Qf91 and H M o N
After flattening its surface, the second P8G film 1) υ is selectively etched by RIE to form a through hole and expose the p-type channel stop region +3+. Next, PCVD
A p-type silicon layer is formed at 800° C. using a plasma enhanced CVD method. As a result, a p-type single crystal silicon layer (IJ) is formed by epitaxial growth on the p-type channel stop region I3). Furthermore, a polycrystalline silicon layer is formed on the second psosuD. Once a monocrystalline silicon layer (one crystal) is formed, the polycrystalline silicon layer is removed using the RIE method, leaving only the silicon tau:4, and then a film is formed at 550°C using the PCVD method. A 0.6 μm thick amorphous silicon layer is deposited on the second PSGB'
s" (1) 1 and the single crystal silicon layer 1) J. Then, B (poron) 1 is formed on the amorphous silicon j-
After fr ion implantation, L8PE (La
teraJSol! id phase Epitaxy
) method to obtain a single crystal silicon film with a thickness of 0.3 μm, and then use the PCVD method to form a 2 μm thick p A p+ type/p type single crystal silicon film (131) is finally formed on the second PSG film αυ.

In other words, the process shown in FIG.
n) exposed through the p++ channel stop region (3
) with the single crystal silicon layer 0 formed on the second layer as a seed crystal.
A p+ type/pffi single crystal silicon film (13+) is formed on the PSG film 1) υ.

In the step shown in FIG. 4, the portion of the single crystal silicon film U facing the n+ type multiplied signal input region 4) is selectively etched by the PIE method, and the single crystal silicon film 131 is formed into a single crystal silicon film for each pixel. (13a) (13b). Next, single crystal silicon film (13a) (15b) tl
- form 5102 film (141) on the surface by thermal oxidation,
Subsequently, n+ type layers (15a) (15b) are formed by ion-implanting a (arsenic) into the surface regions of the single crystal silicon films (15a) (15b). As a result, single crystal silicon films (15a) (15b) and n-type NJ (1
, 5a) (15h).
) (16b).

In the process shown in FIG.
@1 (7) PSG film (9) and 8 jo2 film (
)) to form a through hole (171) to expose the n-type signal input region (4) and to
Contact hole (181
form.

Finally, in the step shown in FIG. 6, 1.l' (aluminum ), and in order to shield the p-type channel stop region (3) from light, a light-shielding film Q made of AI! is formed (3iQ2).
film (formed on 141).

In this embodiment, the pixels having the above structure are arranged in parallel in the direction perpendicular to the paper surface.

According to a solid-state imaging device having such a structure, a photodiode (
When the transfer electrode (8) is biased to the maximum positive voltage in a state where charges (specifically, electrons) are generated by the light incident on the connection electrode (16a), the electrons are transferred to the connection electrode (19 and n
The readout electrons are read out through the type signal input region (41) to the part of the one-type channel region (6) located directly below.The readout electrons are transferred to the transfer electrode (8) of each pixel arranged in parallel in the direction perpendicular to the plane of the paper. ) are alternately biased to intermediate and low voltages to be transferred in a direction perpendicular to the plane of the paper.

Moreover, according to such a structure, the photodiode (16b)
In order for the electrons generated in to mix into the adjacent n-type channel region (6), the single crystal silicon film (13b),
Single crystal silicon layer uj and p+ type channel stop layer!
You need to pass 31. However, electrons generated in the p-type layer, which is the upper layer (the layer in contact with the n+-type layer (14b)) within the single-crystal silicon film (13b), are transferred between the p-type layer and the lower p+-type layer. Due to the potential barrier, it is difficult to move to the p-type layer. Moreover, even if they move, the electrons in the p-type layer easily recombine and disappear.

Therefore, almost no electrons generated within the single crystal silicon film (13b) are mixed into the adjacent n-type channel region 1G).

In fact, according to the solid-state imaging device of the present invention, the predetermined illuminance is 28
Even if the light is irradiated with 0 times the illuminance, the pluming phenomenon does not occur. Furthermore, 1'- of the smear phenomenon is also reduced by 0002% (conventionally cL04%).

^ Furthermore, the chip area required to manufacture a 200,000 pixel solid-state imaging device by arranging the above pixels in a matrix is 4.9 x 6.
．． It is reduced to 5M (conventionally 6.2×7.51)1).

(G) Effects of the Invention According to the present invention, it is possible to significantly reduce the pluming phenomenon and the square phenomenon compared to the conventional method, and furthermore, it is possible to reduce the size of the apparatus.

[Brief explanation of the drawing]

? FIG. 1 to Section 6 are cross-sectional views showing one embodiment of the present invention according to manufacturing steps, and FIG. 7 is a cross-sectional view showing a conventional example. 1) Silicon substrate, +71...5i02B!
, (81...Transfer 1J!L pole, αα...Fuku ■0 film, α3 (13a) (15b)...Single crystal silicon film,
(15a)(15b)=・n-type layer, (16a)(
16b)...Photodiode, a9...Connection electrode.

Claims (2)

[Claims] (1) A charge transfer section consisting of a semiconductor substrate and an electrode provided on this substrate via an insulating film, a light shielding film provided above this charge transfer section, and a charge transfer section provided above this light shielding film. What is claimed is: 1. A solid-state imaging device comprising: a photodiode; and a connection portion that connects the photodiode to the charge transfer portion. (2) A step of forming a charge transfer part by providing an electrode on the semiconductor substrate via an insulating film, a step of forming a light shielding film above the charge transfer part, and exposing a part of the semiconductor substrate. a step of forming a single crystal semiconductor film above the light shielding film by using the exposed portion as a seed crystal; a step of forming a photodiode in the single crystal semiconductor film; and a step of forming a photodiode in the single crystal semiconductor film; A method for manufacturing a solid-state imaging device, comprising the step of connecting the device to a transfer unit.