JPS5846183B2 - Manufacturing method of solid-state image sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a high-sensitivity, high-density solid-state imaging device having a photoconductive film.

As shown in FIGS. 1 and 2, a conventional solid-state image sensor of this kind consists of a photodiode that senses an optical image, a charge transfer element that transfers an optical signal, etc. in the center of a p-type base substrate 1. A picture element section 2 (the specific structure will be described later) is provided, a drive circuit section 3 such as a shift register or CCD for driving the picture element section 2 is provided around this picture element section 2, and a An insulating film 4 is provided.

On the upper part of this insulating film 4, a conductor wiring part 6 and a photoconductive film connecting electrode 7 are connected to the terminals of the drive circuit part 3 through the opening of the insulating film 4 and extend to the external wiring pad part 5. It is provided.

Furthermore, a photoconductive film (for example, Z
n5e-Zn1-xCdxTe1 amorphous silicon, etc.) 8 and a transparent electrode 9 are laminated, and a color filter 11 is further adhered via an adhesive layer 10.

Next, the configuration of the picture element section 2 will be explained in detail.

In FIGS. 3 and 4, n+ diffusion region 12 and p-type base substrate 1 form a photodiode.

The n+ diffusion region 12 and the p-type base substrate 1 form a photodiode.

The n+ diffusion region 13 is a diffusion region that constitutes the BBD, and by applying a voltage to the first gate electrode 14, the n+
Charges are transferred from the diffusion region 12.

15 and 16 are insulators, respectively.

The electrode 17 is M. It is electrically connected to the n+ diffusion region 12 and also serves as an electrode of the photoconductive film 8.

The second gate electrode 18 constitutes a BBD gate.

Next, the optical information reading operation of this solid-state image sensor will be explained with reference to FIG.

FIG. 5A shows a drive/malus pattern, and FIG. 5B shows potential changes in the n+ diffusion region 12.

At time t11, voltage V is applied to the first gate electrode 14.

When a read pulse P of H is applied, the n+ diffusion region 12
As shown in Figure 5B, the potential at (VOH-■T
) will be charged.

Here, {circle around (2)} is the threshold voltage of the FET consisting of n'7, the diffused region 12.degree. 13, and the first gate electrode 14.

Now, when there is incident light as shown by arrow A, the photoconductive film 8I
Here, electron-hole pairs are generated and reach the electrode 17 and the transparent electrode 9, respectively, and the potential of the n+ diffusion region 12 decreases.

Moreover, this potential drop is proportional to the amount of incident light (Q indicates normal light and Q2 indicates very strong light). (2) Since the potential is accumulated in TF during the field period, the voltage decreases to (2) 8.

Further, at time t2, when the voltage VOH is applied to the first gate electrode 14, the surface potential of the p-type base substrate 1 thereunder increases, and as a result, electrons are transferred from the n+ diffusion region 12 to the n+ diffusion region 13. Movement occurs.

Subsequently, the potential of the n0 diffusion region 12 rises again, and (
Van-VT).

Therefore, the total amount of charges transferred to the n0 diffusion region 13 corresponds to the incident light.

The optical information read into the n0 diffusion region 13 in this way is transferred to the second transfer pulse P2 at the voltage ■φ shown in FIG. 5A.
By applying voltage to the gate electrode 18, optical information is transferred in the vertical direction (indicated by arrow 2) in the paper of FIG. 3 in the form of BBD charge transfer.

That is, the signal photoelectrically converted by the photodiode can be sent to the output stage as a two-phase lock signal.

In the manufacturing process of such a solid-state image sensor, after forming the conductive wiring section 6 and the photoconductive film connection electrode 7, a method of forming the photoconductive film 8 and the transparent electrode 9 only on the top surface of the picture element section 2 is to use metal A method was used in which a cover mask was used to perform vapor deposition only on predetermined areas (hereinafter referred to as mask vapor deposition method).

The reason why this mask vapor deposition method is used is as follows.

That is, in general, the sensitivity of the photoconductive film 8 is easily deteriorated by solvents and moisture, and resists conventionally used in the manufacture of semiconductor devices (for example, KTFR (trade name), AZ1
350J (trade name), etc.),
The resist removal liquid used in the resist removal process, such as J-100 (trade name) or fuming nitric acid, significantly deteriorates the characteristics.

Therefore, in the past, manufacturing was possible only by the mask evaporation method, but with this mask evaporation method, when adjusting the position of the metal mask on the substrate, it was difficult to damage the p-type base substrate 1 or cause dust to adhere. A large number of defects occurred due to the above, and when the completed solid-state image sensor was operated, a large number of line scratches and dots were formed.

Furthermore, since the photoconductive film and the transparent electrode 9 that are generally formed by vapor deposition have very low strength, it is difficult to remove dust that adheres when cutting the completed wafer by cleaning or the like.

The remaining dust was also a major cause of defects that occurred when adhering the color filter 11 (normally, the gap between the color filter 11 and the transparent electrode 9 must be about 5 to 6 microns, so the color Dust is compressed by the filter 11, causing defects in the solid-state image sensor).

In this way, with conventional manufacturing methods, defects occur during manufacturing,
Yield during manufacturing was poor.

Therefore, an object of the present invention is to provide a method for manufacturing a solid-state image sensor that can significantly improve yield.

An embodiment of the present invention will be explained based on FIGS. 6 to 8.

First, as shown in FIG. 6, a silicon p-type base substrate 1
9, there is a picture element section 2 consisting of a photodiode for sensing an optical image and a transfer BBD element using a normal MOS process.
After forming the drive circuit section 21 consisting of 0, MOS transistor, and CCD element, the conductive wiring section 23, the photoconductive film connecting electrode 24, and the photodiode are connected to the photoconductive film to be formed later through the insulating film 22. An electrode 25 is formed.

Next, the photoconductive film 26 (for example, Zn5e-Zn1=
XCdxTe, etc.) and a transparent electrode 27 (for example, In20s doped with Sn) are sequentially deposited over the entire surface.

Thereafter, as shown in FIG. 7, a collar having a predetermined pattern and cut into a predetermined size is formed using an adhesive layer 28 such as a photocurable resin (for example, product name Summers UV-74, Norland N0A-61, etc.). The filter 29 is bonded while being aligned.

Thereafter, the adhesive protruding from the color filter 29 is removed by washing with a solvent or by 02 plasma assembly, and a resin 30 such as photoresist is applied to a part of the transparent electrode 27, as shown in FIG. As shown, unnecessary portions of the transparent electrical film 27 and photoconductive film 26 are removed by etching using the color filter 29 and the resin 30 as masks, and the resin 30 is further removed to expose a portion of the transparent electrode 27.

In this case, the photoconductive film 26 is Zn5e Zn 1-
Cd X Te 1 transparent electrode 27 is In 20 s
If so, etching can be completed in a few minutes using IO-specified nitric acid.

Next, the p-type base substrate 19 is cut into chips, and the chips are cleaned using the color filter 29 as a protective film.

Finally, after performing the wire bonding, the exposed portion 21a of the transparent electrode 27 and the pad at the end of the conductor wiring portion 23 are wire bonded to external lead electrodes to complete the solid-state imaging device.

As described above, according to the manufacturing method of this embodiment, since the mask vapor deposition method is not used for vapor deposition of the photoconductive film 26 and the transparent electrode 27, the probability of causing scratches on the device or adhesion of dust to the device is reduced compared to the conventional method. The amount of p-type base substrate 1 is very small.
When cutting 9, the color filter 2 whose main part is made of glass
9, dirt associated with cutting can be easily removed using a normal cleaning method.

Therefore, the yield during manufacturing of solid-state imaging devices can be improved.

Furthermore, when this manufacturing method is used, the only thing that requires pattern alignment after the formation of the photoconductive film 26 is the adhesion process of the color filter 29, which greatly simplifies the manufacturing process and reduces the manufacturing cost. becomes cheaper.

As described above, the method for manufacturing a solid-state image sensor of the present invention prevents scratches and dust from attaching during position adjustment by vapor-depositing a photoconductive film and a transparent electrode over the entire surface without using a metal mask. Moreover, since a color filter cut to a predetermined size and glued onto the transparent electrode is used as an etching mask to leave the photoconductive film and transparent electrode in a predetermined area, the yield of defect-free manufacturing of fixed image pickup devices is improved. This has the effect of significantly improving the

[Brief explanation of the drawing]

Figure 1 is a plan view of a conventional solid-state image sensor, and Figure 2 is its
3 is a plan view of the main part, FIG. 4 is a sectional view taken along the IV-4V line, FIG. 5 is a waveform diagram for explaining the operation, and FIGS. 6 to 8 2A and 2B are cross-sectional views for explaining one embodiment of the present invention, respectively. 19...P-type base substrate, 20...Picture element section, 21...Drive section, 23...Conductor wiring section, 26... - Photoconductive film, 27...Transparent electrode, 29...Color filter.

Claims (1)

[Claims] 1. A step of preparing a base substrate, a step of forming a picture element section for sensing and transferring an optical image and a drive circuit section for driving the picture element section on the base substrate, and a step of forming the picture element section and the drive circuit section on the base substrate. A step of forming a photoconductive film to be connected to the photosensitive portion of the picture element portion on the entire substrate surface of the formed base substrate, a step of forming a transparent electrode on the entire surface of this photoconductive film, and a step of cutting into a predetermined shape. a step of aligning and adhering the colored filter to a portion corresponding to the pixel portion on the transparent electrode; and a step of etching away unnecessary portions of the transparent electrode and the photoconductive film using the color filter as a mask. A method for manufacturing a solid-state image sensor including.