JPS61263267A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To prevent the operation of a signal processor from being disturbed by forming a light shielding film made of a polycrystalline silicon which contains a large quantity of arsenic directly above a signal processor in a semiconductor integrated circuit which has a photodetector. CONSTITUTION:A P-N junction photodiode 2, an MOS transistor 3 and a capacitor 4 are formed on the surface of an N-type silicon substrate 1. A light shielding film 9 is coated on a plasma nitride film 8 on a CVD oxide film 7 to coat on a light signal processor. The film 9 is formed of a polycrystalline silicon film which contains a large quantity of arsenic. The film 9 is provided to almost shield the light of a shorter wave length side from 1,100nm, a light is not almost incident to the processor to prevent the operation from being disturbed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to a method for preventing deterioration of the operation of circuit components due to light in a semiconductor integrated circuit including a photodetecting element.

[Prior art and its problems]

Conventionally, many devices that apply photodetection elements have been put into practical use, and in all of them, the photodetection section and the signal processing circuit section were housed in separate containers, but recently, systems have become more compact and signal processing speeds have increased. In order to improve the performance of the device, such as improving the performance of the device, it has come to be used as a semiconductor integrated circuit device in which a photodetection section and a signal processing circuit section are built into the same substrate.

In that case, the problem is that when the source is incident on an integrated circuit component other than the photodetector, it excites unnecessary electron-hole pairs in the semiconductor, which increases the leakage current of the device, etc. Unfavorable phenomena occur. The above phenomenon may limit the operation of integrated circuits and circuits in cases where peripheral circuits such as scanning circuits are included in addition to light detection elements, such as facsimile source detector arrays, solid-state imaging devices, and optical distance measuring devices. This is a big factor. - Taking scanning circuits as an example, scanning circuits are generally capable of high integration density, use high-yield MOS shift registers, and use the gate capacitance of MOS transistors as temporary information storage to shift scanning pulses. It is often done. However, when a source enters this part, unnecessary electrons are generated in the junction area.
A leakage current flows due to the hole pairs, significantly shortening the storage time.

As a countermeasure to the above-mentioned problem, for example,
As disclosed in No. 6, there is a method in which a conductive material is provided via an insulating film on a region including a semiconductor element other than a photodetecting element. This method can solve problems such as leakage current due to unnecessary electron-hole pairs, but
The following new serious drawbacks arise. That is, if a conductive material is formed over a large area including semiconductor devices, a short circuit may occur between the semiconductor devices through the conductive material. This short circuit phenomenon is caused by the fact that inorganic films such as silicon dioxide and silicon nitride, or organic films such as polyimide, which are used as insulating films to provide interlayer insulation between conductive substances and semiconductor elements, have low cracking and scratch resistance.
This is also due to the fact that they have defects such as the tendency to generate pinholes. Therefore, if a conductive substance is formed over a wide area on these films, there is a high probability that conduction will occur between the conductive substance and the wiring related to the semiconductor element, and a short circuit will occur between the semiconductor elements over a wide area, making it difficult to manufacture the device. A problem arises in that the yield is seriously reduced.

[Purpose of the invention]

The present invention has been made in order to eliminate the above-mentioned problems, and provides a semiconductor integrated circuit device that can protect a semiconductor integrated circuit including a photodetecting element from noise caused by light and fully exhibit its characteristics. The purpose is to

[Key points of the invention]

The present invention provides an insulating film deposited on a semiconductor integrated circuit fabricated using a normal manufacturing method in order to protect a semiconductor integrated circuit including a photodetecting element from noise caused by the source by shielding a signal processing circuit section from light. Thereafter, the parts other than the photodetecting element are covered with a thin film made of single crystal or polycrystalline silicon containing a large amount of arsenic to prevent light from entering the parts other than the photodetecting element.

[Example of origination]

FIG. 1 is a cross-sectional view of the structure of a main part of a semiconductor integrated circuit for embedding optical signals to explain one embodiment of the present invention, and is an example in which a light-shielding film is provided in an area other than a photodetecting section. In Figure 1, 2
．． 3 and 4 are P, N-junction photodiodes, MOS) transistors, and capacitors formed on the surface of the N-type silicon substrate 1, respectively, and 9 is deposited on the plasma nitride film 8 on the CVD oxide film 7 for original signal processing. This is a light-shielding film that covers the area.

5 is a thermal oxide film, and 6 is an aluminum wiring. An example of a method for manufacturing the light shielding film 9 will be described below. First, after completing the formation of the photodetector element 2 and the adhesion of the circuit wiring 6, the photodetection part is protected only with the CVD oxide film 7, and the signal processing circuit part is protected by the CVD oxide film 7.
Two layers, the VD oxide film 7 and the plasma-enhanced film 8, are deposited in this order so as to protect them. The reason why the light detection part is protected only by the CVD oxide film 7 is that the refractive index of the nitride film 8 is 2.
．． This is to suppress the loss of light due to total reflection at the interface with the oxide film 7 with a refractive index of 1.45.Next, a light shielding film 9 is deposited on the plasma nitride film 8. At this time, in order not to damage the lower layer aluminum wiring 6, 500
A low temperature process below ℃ is required. In the present invention, a silicon thin film containing a large amount of arsenic is used as the light shielding film 9, but it can be formed at a sufficiently low temperature by the following process. First, the substrate on which the nitride film 8 has been deposited is placed on a stage at a temperature of 200°C between parallel plate electrodes in a chamber, and hydrogen-based 5% monosilane gas is heated at 10 (PF) while maintaining the chamber pressure at 10 Torr. =+ (
DR amount is supplied into the chamber. In this state, when an RF power of 0.1''/♂ is applied between both electrodes, microcrystalline silicon is deposited on the upper surface of the substrate at a rate of 200λ, and a film thickness of 1 μm is obtained in 1 hour of reaction. Next, arsenic was applied at an accelerating voltage of 100 keV and a dose of 5XIQim.
After ion implantation under the following conditions, the output was 1.3 J/cat.
Laser annealing is performed using QSUI and Chilby laser (pulse @ 20nsec). Thereafter, using a resist pattern with a window open only in the photodetection area as a mask, the silicon film on the photodetection area is removed by plasma etching to form a light shielding film 9. The film thus formed contains 5×10 arsenic
Contains more than crn.

FIG. 2 is a diagram showing the light absorption spectrum of the shading [9] obtained by the above method. As can be seen from FIG. 2, most of the light on the wavelength side shorter than 1l100f1 is blocked, and substantially no light enters the signal processing circuit section. Moreover, since the light-shielding film 9 is provided in close contact with the integrated circuit, there is no stray light due to reflection, diffraction, etc., and it is possible to reliably prevent light from entering parts other than the photodetecting element.

In the above embodiment, a semiconductor integrated circuit including a photodetecting element was described as an object, but the present invention can of course be applied to various other integrated circuits without departing from the spirit of the present invention. For example, in an originally erasable semiconductor memory, its address portion may be shielded using the method of the present invention.

〔Effect of the invention〕

According to the present invention, a shield made of a polycrystalline silicon film containing a large amount of arsenic is provided directly above the signal processing circuit section of a semiconductor integrated circuit including a photodetecting element, thereby controlling the operation of the signal processing circuit section. It has become possible to put into practical use a semiconductor integrated circuit that includes a photodetector element that does not cause interference.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a main part structure of a semiconductor integrated circuit for optical signal processing which is an embodiment of the present invention, and FIG. 2 is a diagram showing a light absorption spectrum of a polycrystalline silicon film. DESCRIPTION OF SYMBOLS 1... N-type silicon substrate, 2... PN junction photodiode, 3..., MOS) transistor, 4... Capacitor, 5... Thermal oxide film, 6... Aluminum wiring, 7... CVD oxide film, 8...CVD nitride film, 9.
...Light-shielding film. Figure 1 Figure 2 Figure 3 Procedural amendment (9 plows) June 18, 1985 1, Indication of the case Patent application 1989-〆Riichi&, 3-90
3. Relationship with the case of the person making the amendment Applicant 4, Agent Figure 2

Claims (1)

[Scope of Claims] 1) In a semiconductor integrated circuit device in which a part of a large number of semiconductor elements manufactured on the same substrate is a photodetector, a large amount of arsenic is applied to a region containing semiconductor elements other than the photodetector. 1. A semiconductor integrated circuit device comprising a light shielding film made of monocrystalline or polycrystalline silicon. 2) In the device according to claim 1, the arsenic content in the light shielding film made of silicon is 5×10^2^0.
A semiconductor integrated circuit device characterized by having a diameter of cm^-^3 or more.