JPH0360156A - Solid-state image sensing device - Google Patents

Abstract

PURPOSE:To form a second elecrode with a step of small difference, and to prevent electric field concentration by uniformizing a photoconductive film, to reduce white marks and sensitivity irregularity, by introducing a third electrode for connecting a first electrode and a second electrode. CONSTITUTION:A third electrode 14 is formed so as to fill a contact hole bored in an insulating film 8 whose surface is flattened. The lower surface of the third electrode 14 is connected with a first electrode 7. A second electrode 9 is formed on the third electrode 14. The first electrode 7 and the second electrode 9 are electrically connected with each other. The upper surface of the third electrode 14 is in the same surface as that of the insulating film 8 whose surface is flattened. On these surfaces, the second electrode 9 is formed by vapor-depositing or sputtering metal such as Al and Mo, or preferably, the same metal as the first electrode 7 and the third electrode 14. A step- difference scarcely generates in the second electrode 9, because the third electrode 14 being a substratum and the insulating film 8 are flattened so as to be in the same plane.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention is directed to a semiconductor substrate in which a signal charge transfer section (solid-state image sensor chip) and a photoelectric conversion section made of a photoconductive film are laminated on a semiconductor substrate. The present invention relates to a stacked solid-state imaging device, and particularly relates to a solid-state imaging device in which electrical connection between a first electrode (extracting electrode) and a second electrode (pixel electrode) is improved.

(Prior Art) In recent years, solid-state imaging devices have been developed that use photodiodes as photoelectric conversion sections and COD as signal charge transfer sections. This solid-state image sensor has the advantage of being able to realize a camera that is smaller, lighter, and more reliable than a conventional image pickup tube, and can obtain high-quality images with almost no afterimages. However, the solid-state Jlil image element is mainly formed on a Si wafer, and has the drawback that the usable sensitivity wavelength range is limited to the visible wavelength range.Furthermore, the effective photosensitive area and signal transfer area of the pn photodiode that performs photoelectric conversion are ineffective. There is a photosensitive part,
It has drawbacks that image pickup tubes do not have, such as reduced sensitivity and the tendency to generate false signals such as moiré. As a solid-state image sensor that eliminates these drawbacks, there is a stacked solid-state image sensor that uses a conventional solid-state image sensor as a signal charge transfer unit (solid-state image sensor chip) and performs photoelectric conversion with a photoconductive film provided on the top of the solid-state image sensor. is proposed.

FIG. 2 is a cross-sectional view of a pixel portion of a stacked solid-state imaging device in which a solid-state m-image device chip and a photoconductive film are combined. p
A vertical C0D2 consisting of an n-type buried channel COD, an n+ type storage diode 3, and a p+ type channel stop portion 4 separating each pixel are formed on a type 3i substrate 1, and a polygonal layer is formed as a transfer gate electrode on the vertical C0D2. 3i electrode 5
is formed. In the area of the storage diode 3, a contact hole is formed in the oxide film 6 made of a thermal oxide film, a CVDM film, etc. so that the n+ part of the M-product diode 3 is exposed, and then, for example, A! A first electrode (extracting electrode) 7 made of J, MoS, or the like is formed in a predetermined shape. Then, for example, polyimide or BPSG through a melt process.
A surface flattened insulating FJ8 made of (boron-phosphorus-silicate glass) or the like is formed, and a contact hole is formed in this insulating film 8 to expose a part of the first electrode 7. A second electrode (pixel electrode) 9 is formed in a predetermined shape.

On the solid-state imager chip thus formed, a photoconductive film 1o of amorphous 3i or the like is formed by glow discharge or photo-CVD, and is roughly coated with ITO (indium tin oxide film).
By forming transparent electrodes 11 such as the above, a stacked solid-state imaging device can be obtained.

(Problems to be Solved by the Invention) In the conventional stacked solid-state imaging device as shown in FIG. Since the second electrode 9 is formed on the first electrode 7, a concave portion 12 with a steep step is formed at the joint portion of the second electrode 9 with the first electrode 7. Therefore, a recess is formed in the photoconductive film formed on the second electrode 9 and the transparent electrode 11 due to the influence of the recess 12 of the second electrode 9.
1 is not always a constant width, the electric field becomes low between the upper surface of the second electrode 9 and the transparent electrode 11 in the recessed part, a leak N current occurs, and a local There is a problem in that electric field concentration causes uneven sensitivity and white scratches, which leads to a decrease in reliability.

In view of the above circumstances, it is an object of the present invention to provide a solid-state imaging device that is free from white scratches and uneven sensitivity and has improved reliability by eliminating the recessed portion of the second electrode.

[Structure of the Invention j (ii! Means for Solving the Problem) The present invention provides a third electrode that electrically connects the first electrode and the second electrode in the solid-state imaging device as described above. The above problem is solved by interposing it between the two electrodes.

(Function) According to the present invention, since the third electrode is interposed between the first electrode and the second electrode so as to be electrically connected, the second electrode
The level difference in the recessed portion of the electrode is reduced or eliminated, and therefore the recessed portion of the photoconductive film and transparent electrode formed thereon is also reduced or eliminated.

(Example) Hereinafter, the details of the present invention will be explained with reference to an actual flow example shown in the drawings.

FIG. 1 is a side view showing each step in manufacturing a stacked solid-state imaging device according to an embodiment of the present invention.

On a p-type semiconductor 81 substrate 1, there is a surface flattened insulating film 8 consisting of a 0+ type storage diode 3, a poly S1 electrode 5 serving as a transfer gate, a first electrode 7 and an 8PSG, etc., as in the conventional example.
is formed (Fig. 1 (6)). Then, a resist 13 having a predetermined pattern is formed on this surface planarizing insulating film 8 using a normal photolithography process (FIG. 1(b)).

Next, according to this resist pattern, etching is performed to reach the first degree dipping pole 7, followed by surface flattening and insulation! !
8 corresponds to the etched depth A1), M
The third electrode is formed by vapor deposition or sputtering using a metal such as O, preferably the same material as the first electrode 7 and the second electrode.
An electrode 14 is formed (FIG. 1(C)). Then, the resist 13 is dissolved by a lift-off method, and the metal film 14 on the resist 13 is removed. In this state (FIG. 1)), the third electrode 14 is formed to fill the contact hole opened in the surface flattening insulating film 8, and the third electrode 14 is
4 has its lower surface connected to the first electrode 7, and by forming the second electrode 9 on this third electrode 14, the first electrode 7
and the second voltage ff19 are electrically connected.

As is clear from FIG. 1(d), the upper surface of the third electrode 14 is within the same surface as the surface of the surface flattening insulating film 8. Furthermore, A! on these surfaces! Q, metals such as MO,
Preferably, the second electrode 9 is formed by vapor deposition or sputtering of the same metal as the first electrode 7 and the third electrode 14 (FIG. 1(e)). This second electrode 9 is planarized so that the underlying third electrode 14 and the surface flattening insulating film 8 are in the same plane, so that almost no step difference occurs. Thereafter, a photoconductive film 10 made of amorphous S is formed by glow discharge or CVD according to a conventional method, and then IT
A solid-state imaging device can be obtained by forming a transparent electrode 11 such as O or the like (FIG. 1(f)).At this time, by forming a third electrode 14 on the second electrode 9 as described above, the step is removed. As shown in Fig. 1(f),
The photoconductive film 10 and transparent electrode 11 formed on the second electrode 9 do not have recesses caused by the step 12 of the second electrode 9 as in the conventional example, and electric field concentration or leakage current occurs at the step. This prevents the occurrence of

In addition, in this example, an example of an interline transfer type CCD was shown as the scanning section of a photoconductive film stacked solid-state image sensor, but the application is not limited to this, but can also be applied to a MOS type or CPD type having a storage diode. Of course. Also,
Although oxide films such as 8102 are mainly used as the insulating film, S! A 3N+ membrane or a composite membrane thereof may be used. Furthermore, although the example of amorphous S1 has been described as the material of the photoelectric conversion part, the material is not limited to this, and Stz83, Se-As-Te, which are used as photoelectric conversion materials for image pickup tubes, etc.
It is clear that CdSe, CdZnTe can be used, and InSb, PbSnTe, 06g
Infrared photoelectric materials such as Te can also be used. It goes without saying that the present invention can also be applied not only to photoconductive films but also to photoconductive N films.

In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, according to the present invention, in a stacked solid-state imaging device comprising a solid-state imaging probe chip and a photoconductive film, the first
By introducing a third electrode that connects the electrode and the second electrode, it is possible to form the second electrode with fewer steps, so it is possible to form a photoconductive film uniformly, prevent electric field concentration, and improve whiteness. A solid-state imaging device that can reduce scratches and sensitivity unevenness can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a method of forming a portion centered on the first, second, and third electrodes of a stacked solid-state image device according to an embodiment of the present invention, and FIG. FIG. 2 is a cross-sectional view showing the configuration of one pixel part of the solid-state imaging device. 1...Semiconductor 3i substrate 2...Vertical CCD3...
・Storage diode 4... Channel stop part 5... Poly 3i electrode 6... Oxide film 7... First electrode (extracting electrode) 8... Flattening insulating film 9... Second electrode ( Pixel electrode) 10... Photoconductive III 11... Transparent electrode 12... Step 13... Resist 14.
...Third electrode

Claims (4)

[Claims] (1) A signal charge storage diode disposed on a semiconductor substrate, a first electrode connected to the signal charge storage diode, and a first electrode connected to the first electrode through a contact hole in an insulating film provided on the first electrode. In a solid-state imaging device comprising a second electrode connected to an electrode, a photoconductive film laminated on the second electrode, and a transparent electrode formed on the photoconductive film, the first electrode and A solid-state imaging device characterized in that the second electrode is connected to the third electrode via a third electrode. (2) The third electrode is formed to fill a contact hole opened in an insulating film in which the first electrode is embedded to connect the first electrode and the second electrode. The solid-state imaging device according to claim (1). (3) The surface of the third electrode in contact with the second electrode is substantially in the same plane as the surface of the insulating film in contact with the second electrode. ) solid-state imaging device. (4) The third electrode is made of the same material as the first electrode and the second electrode, or a metal such as Al or Mo. Solid-state imaging device.