JPH0227764A - Solid state image sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention will be described in the following order.

A. Industrial field of application B1 Overview of the invention C1 Prior art [Fig. 3] D1 Problem to be solved by the invention E1 Means for solving the problem F Effect G. Examples [Fig. 1, 2 [Figure] H1 Effects of the invention (A, industrial application field) The present invention relates to a solid-state imaging device such as a CCD or MOS type.

(B. Summary of the invention) The present invention relates to a solid-state imaging device.

In order to more effectively prevent light from entering areas other than the light-receiving opening 0IR5, a tungsten noride film containing a substance that reduces light transmittance is used to block light from entering areas other than the light-receiving opening. It is.

(C, Prior Art) [Figure 3] A solid-state imaging device has a large number of light-receiving parts arranged in a 7-trix shape on a semiconductor substrate -F, and charges generated by photoelectric conversion in areas other than the light-receiving parts are A register is provided to transfer the data. The resistor is generally driven by a drive pulse applied to a drive electrode formed on the semiconductor surface via an insulating film.

Incidentally, in such a solid-state imaging device, smear occurs when light enters a region other than the light receiving section, so it is necessary to shield the region from light. FIG. 3 shows a conventional example of a solid-state imaging device, in which parts other than the center are shielded from light by aluminum IIQ. In the same figure,
a is a semiconductor substrate, b is t, for example, a PSGffQ formed on the surface of the conductor substrate a, c, c, "-" is a drive electrode made of polycrystalline silicon provided in the PSG film, d
, d, . . . are drive electrodes C1C5- on the surface of the PSGI.
・A light-shielding film made of aluminum formed on the part that covers the .

In addition, in a solid-state imaging device, a drive electrode is formed of metal silicide, and the drive electrode blocks light to prevent light from entering the register section, thereby preventing the occurrence of smear. It is introduced in the publication No.-159564.

(D. Problems to be solved by the invention) By the way, the third problem
The solid-state imaging device shown in Figure 7 has the following problems.

First, the drive electrode C of the light shielding Md or PSGII2b
, e, ... is formed on the raised part, covering the sides of the raised part and blocking the light diagonally entering the register part.
Since it is necessary to block light, the length 2 of the drive type J4c, C1 of the light shielding films d, d, ... that protrudes outward from the top of the side surface becomes considerably long, and the aperture ratio increases accordingly. becomes smaller. That is, the length including the length actually increases to about 1.0.8 μmff degree. In HDVS solid-state imaging devices, the distance between adjacent drive electrodes C and 0 must be approximately 3 μm, but the actual width of the pixel portion is L-22, and as mentioned above, Since the width is about 0.8 μm, the actual width of the pixel portion becomes very small, about 1.4 μm. This is undesirable because it leads to a low aperture ratio.

Therefore, instead of forming the R light films 1, ffi, - on the PSG film 2, it is recommended to form them inside psaHb. By arranging them very close together, it is possible to effectively block oblique light while increasing the open Lll, which is preferable in response to HDVS. However, when trying to form a light-shielding film made of aluminum in PS Glli,
There is a problem in that the aluminum film melts (melts at 500° C. or higher) due to high-temperature treatment (900° C. or higher) during the formation of the G film, causing the shape to collapse.

In addition, aluminum has excellent light blocking properties, but on the other hand, it is also highly reflective and reflects incident light towards the lens.
The problem is that the reflected light is re-reflected by the lens and enters the photodetector, creating noise.

In this respect, the solid-state image transfer device disclosed in Japanese Patent Application Laid-Open No. 59-159564 has a drive electrode formed of a metal silicide film,
This can be said to be excellent because the drive electrode also functions as a light shielding film.

However, according to such a solid-state imaging device.

Due to the high-temperature treatment for forming the PSGJ film, the metal silicide r;4 (for example, a tungsten silicide film) becomes polycrystalline, and the light transmittance of the metal silicide film increases.
There is a problem with C being put away. In particular, red copper, ie, light with a long wavelength (approximately 700 nm), has a high A path rate and has a low light shielding effect against red. Therefore, there is an undesirable problem in that red spots and mares are likely to occur.

The present invention has been made to solve these problems, and an object of the present invention is to more effectively prevent light from entering areas other than the light-receiving opening.

(E. Means for Solving the Problems) In order to solve the problems described in -F, the solid-state imaging device of the present invention uses a tungsten silicide film containing a substance that reduces light transmittance to prevent light from reaching areas other than the light-receiving aperture. It is characterized by being designed to block the

(F. Effect) According to the solid-state imaging device of the present invention, the tungsten silicide film in the area other than the light-receiving opening contains a substance that reduces the light transmittance. The treatment can prevent a decrease in light transmittance due to the progress of crystallization, and can further effectively prevent light from entering areas other than the light-receiving aperture, thereby reducing smear. .

(G. Embodiment) [FIGS. 1 and 2] Hereinafter, the solid-state imaging device of the present invention will be described in detail according to the illustrated embodiment.

Figure 7jSf is a sectional view showing one embodiment of the solid-state imaging device of the present invention, in which I is a P-type t4 body substrate, 2 is a light receiving region, and 3 is a PSG11! of the semiconductor substrate IL. ! Inside this, there is a drive electrode 4.4 made of polycrystalline silicon.
-1 Light shielding by shading the driving electric rod 4 on the upper side 5,5,.
...is provided. The light-shielding films 5.5, .

Li like this! , according to the one-piece imaging device, after forming the light-shielding film 5゜5,..., the P S G IIQ 3 covers it.
The light-shielding films 5.5, .
Since the light transmittance is blocked by impurities such as, the light transmittance hardly decreases. Therefore, the light shielding films 5.5, . . . can very effectively prevent light from entering areas other than the light receiving portion. Incidentally, the ion implantation of C10, Ar, or N, etc. is performed at an eV of 40 for a thickness of 1000 for a light-shielding film made of tungsten silicide, for example.
The energy of Then, the light transmittance for light with a wavelength of 700 nm can be reduced to 1% or less, and the light transmittance can be made very small.

However, after forming the tungsten silicide film 5.5..., impurities such as C10, A' or N are implanted on -C1.
The impurity is doped by mixing this impurity into the reaction gas supplied to the CVD equipment when forming the tungsten silicide film 5.5, ... by CVD. It is also possible to form light shielding films 5.5, . . . made of tungsten silicide.

Since this solid-state imaging device is disposed in the PSGI area 3 that covers the drive electrodes 4.4, . . . in close proximity to the drive electrodes 4.4, . 1 can be made smaller compared to conventional solid-state imaging devices. Specifically, l can be made 0.4 μm or more, the actual width of the opening can be increased by 0.4 μm, and HD
It is possible to secure the open ratio required when VS is supported.

Nao, J! ! The optical films 4.4, . . . may be formed of WSiGe, which is made by adding germanium Ge to tungsten silicide. This is because tungsten silicide (with a film thickness of 800 mm, for example) has a light transmission characteristic of t1, as shown by the solid line in FIG.
This is because, as shown by the broken line, the characteristic curve of the case of 2000 people) shifts toward higher wavelengths, and the light transmittance for light of 700 to 800 nm and shorter wavelengths becomes significantly lower.

To form a tungsten silicide film containing germanium in this way, for example, tungsten silicide W
Reactive gas WF used to form Si by CVD
Formation of tungsten silicide film 74. Is it suitable to perform CVD by supplying B+SiH with Ge-containing GeH4 etc. as a reaction gas? Formation of tungsten silicide film 74.
Ions of germanium or its compounds such as Ge or GeF may be implanted into the tungsten silicide film, or after the formation of the tungsten silicide film, an excimer laser may be applied to the tank silicide film in a GeH4 atmosphere. The tungsten silicide film may be doped with tungsten in the atmosphere by irradiation.

When impurities such as C, 0, Ar, N, etc. are added to the tungsten silicide film, whether the impurity can prevent the tungsten silicide film from becoming transparent by preventing crystallization of the tungsten silicide film, or whether the tungsten silicide film can be prevented from becoming transparent. When the film contains germanium Ge, the light transmittance can be lowered and light can be blocked by changing the absorption coefficient.

The embodiment shown in FIG. 1 has a structure in which the driving electrodes 4.4, . . . are covered with light shielding films 5.5, . It is also possible to use a structure in which the drive electrode itself functions as a light-shielding film as described above.

Such a solid-state imaging device has drive electrodes of C50 and Ar.
Alternatively, it is formed of tungsten silicide containing impurities such as N or Ge, and has a structure in which a light shielding film separate from the drive electrode is not particularly provided. A solid-state imaging device having such a structure has the advantage that it has a simpler structure and requires fewer manufacturing steps than the solid-state imaging device having the structure shown in FIG. However, the solid-state imaging device having the structure shown in FIG. 1 has the advantage that more complete light shielding can be achieved by forming a light shielding film provided separately from the drive electrode in the most favorable pattern for light shielding. .

(H, Effects of the Invention) As described in -1- below, in the solid-state imaging device of the present invention, a tungsten silicide film is formed on a region other than the light-receiving aperture, and the light of this is formed in the tungsten silicide film. It is characterized by containing a substance that reduces transmittance.

Therefore, according to the solid-state imaging device of the present invention, the tungsten silicide film in the region E other than the light-receiving opening contains a substance that lowers the light transmittance, thereby preventing the decrease in light transmittance caused by high-temperature processing. In addition, it is possible to effectively prevent light from entering areas other than the light-receiving aperture, thereby reducing smear.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing one embodiment of the solid-state imaging device of the present invention, Figure 2 is a diagram showing the light transmission characteristics of a tungsten silicide film and a tungsten silicide film containing germanium, and Figure 3 is a conventional example. FIG. Explanation of symbols 2...Amount of light received [1 part, 4...Tungsten silicide film. Figure 1. Light-transmitting characteristic diagram. Figure 2.

Claims (1)

[Claims] (1) A solid-state imaging device characterized in that a tungsten silicide film is formed on a region other than the light-receiving opening, and a substance that lowers the light transmittance of the tungsten silicide film is contained.