JPH01257319A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor integrated circuit device where a characteristic of a photodetector is displayed sufficiently by reducing a reflection loss of an incident beam on the photodetector and whose reliability has been secured by laying a specific surface protective film between an insulating film composed mainly of silicon oxide on a semiconductor substrate and a transparent resin layer of a beam incidence route to the photodetector. CONSTITUTION:An insulating film composed mainly of silicon oxide is applied onto a semiconductor integrated circuit formed by an ordinary manufacturing method, after that, a surface protective film 7 is deposited on the insulating film exposed at a photodetector part in such a way that a portion of silicon nitride is reduced continuously from an upper layer of an oxysilicon nitride film one after another and that a lowest layer becomes a silicon oxide film. Since a refractive index of an oxysilicon nitride film is smaller than that of a silicon nitride film of a conventional surface protective film, a reflection loss at an interface between the film and a transparent epoxy resin 9 of a package is reduced; in addition, a composition is changed in such a way that the lowest layer is only the portion of silicon oxide; accordingly, a problem of interfacial reflection at a silicon oxide film 4 on a substrate 1 is eliminated. By this setup, it is possible to obtain a semiconductor integrated circuit device containing the photodetector which can suppress the interfacial reflection of a beam and whose sensitivity has been enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor integrated circuit device that includes a photodetecting element, has an insulating surface protective film coated on the element, and is further subjected to transparent resin puff casing. Regarding.

[Conventional technology]

Conventionally, many devices to which photodetecting elements are applied have been put into practical use. In all of them, the light detection section and signal processing section were housed in separate containers, but recently, in order to make the system more compact and improve the performance of the signal processing speed section If, the light detection section and signal processing section have been housed in separate containers. A semiconductor integrated circuit device in which the circuit part is built on the same substrate! It is now used as a.

[411 that the invention attempts to solve! ] In such a semiconductor integrated circuit device, in order to ensure reliable operation of the signal processing circuit section, a surface image fl! Since these WAA films with different optical properties are stacked, it is necessary to apply a film and perform packaging in order to mount this integrated circuit device on a circuit board. A phenomenon occurs in which the amount of light incident on the sensor decreases, and the detection ability decreases.

For example, silicon nitride is generally used as a surface protective film for semiconductor integrated circuit devices, and epoxy resin is used as a transparent resin for packaging, but the refractive index of silicon nitride is 2.00 in the visible wavelength region. On the other hand, the refractive index of the underlying film mainly composed of silicon oxide is 1.46, and the refractive index of the upper layer of epoxy mm is 1.55. Therefore, the reflection loss at the interface with the underlying film whose main component is silicon oxide is 16%, and the reflection loss at the interface with the upper layer epoxy resin is 1.
It reaches as much as 3%, greatly reducing the sensitivity of the photodetecting element.

To solve the above problem, there is a method of depositing silicon nitride as a surface protective film over the entire surface of the semiconductor integrated circuit device and removing only the silicon nitride on the photodetector element. Although this method allows the reflection loss at the interface to remain at 3% and solves the problem of decreased sensitivity, it also creates the following serious drawback. In other words, since the silicon nitride that has been deposited on the photodetecting element is removed using, for example, a gas plasma containing CP4 gas as the main component, damage occurs to the PN junction interface and surface of the photodetecting element, causing damage at the junction interface. leakage current and surface recombination rate increase. Therefore, the interface reflection reduction effect is canceled out, and sensitivity improvement is not substantially achieved, or dark current characteristics are deteriorated due to leakage current. Furthermore, a surface layer is formed on the photodetecting element. Since this is not provided, a problem arises in that the reliability of the entire device, including not only the photodetecting element but also the signal processing circuit section, is degraded.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor integrated circuit device that reduces reflection loss of incident light to a photodetector element, fully exhibits its characteristics, and at the same time ensures reliability.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a semiconductor integrated circuit device in which a part of the element is a photodetecting element, and at least a portion of the puff cage located on the light incident path to the photodetecting element is made of transparent resin. , between the insulating film mainly composed of silicon oxide on the semiconductor substrate and the transparent resin layer of the light incident path to the photodetector element, the part in contact with the insulating film is made of a silicon oxide film, and the silicon nitride part is successively formed. The surface image il! increases, and the portion in contact with the transparent resin layer is made of silicon oxynitride! Assume that a membrane is present.

[Effect]

The silicon oxynitride portion of the surface image a film in contact with the transparent resin has a refractive index of 1.62, which is 1.5 of the refractive index of the epoxy resin.
5 is closer to silicon nitride than silicon nitride, and the reflectance at the interface is 2.
%, and since the portion of this surface protective layer that is in contact with one of the insulating films mainly composed of silicon oxide is made of silicon oxide, the reflectance at the interface is 0%4. Moreover, the interface has good adhesion because the same materials are in contact with each other.

〔Example〕

FIG. 1 is a cross-sectional view of a main part structure of a semiconductor integrated circuit device for explaining one embodiment of the present invention. A MO3I-transistor formed by forming a gate electrode 5 via the P-type source/drain region 3 and silicon oxide @4 on the substrate, a capacitor formed by two layers 31 sandwiching silicon oxide 1114 and aluminum wiring 6 are integrated, Field oxidation l! between each element! 0 separated by I41
According to the present invention, the bottom layer on the aluminum wiring 6 is a silicon oxide film, and the silicon nitride content increases continuously toward the upper layers, and the top layer is a silicon oxynitride film for surface protection. 1 film 7 is applied. Furthermore, the optical signal processing section excluding the photodiode section is aluminum light-shielded! 8, and the entire element is covered with transparent epoxy resin 9.

Although most of such semiconductor integrated circuits can be manufactured by known conventional techniques, the process of depositing the surface protective film 7 in which the silicon nitride content decreases in order from the silicon oxynitride content in the uppermost layer will be described below. During this adhesion process, aluminum
Although a low-temperature process of 500° C. or lower is required so as not to damage the substrate, it can be formed at a sufficiently low temperature by the following process. First, a substrate on which aluminum wiring 6 is formed is placed on a support stand at a temperature of 350°C between parallel plate 1i electrodes in a plasma CVD reaction tank.
5l) 1# gas and N, 0 while keeping the pressure at orr.
The gas flows at a constant rate of 10 i/min and 200 m1/min, respectively, and the NHZ gas flows at a rate of 5 m/min starting from Owl/min.
When RF power with a frequency of 13.56 MHz and a power of 10 W is applied to the reaction tank at a rate of 1/min, the silicon nitride content increases sequentially from the bottom layer, and the top layer becomes a surface protection layer consisting of silicon oxynitride. A film is deposited on the top surface of the substrate 1 at a rate of 500 per minute, and approximately 10,000 deposits are deposited in a 20 minute reaction.
Human membrane thickness can be obtained.

The surface protective film 7 deposited by such a process has a refractive index of 1.62 because the silicon nitride content decreases in order from the upper layer.
It decreases continuously from 1.46 to 1.46. Therefore, the reflectance at the interface with the silicon oxide film 4 is 0%.

The reflectance at the interface with the transparent epoxy resin 9 is 2%, which is greatly reduced compared to the values of 16% and 13% when silicon nitride is used. In addition, the crack resistance and heat resistance are improved compared to silicon nitride, and the water resistance is comparable to that of silicon nitride, so it has sufficient performance in terms of reliability.

Once the processing of the surface protection film 7 using normal photolithography technology and the formation of the aluminum light-shielding film 8 are completed, a semiconductor integrated circuit chip for optical signal processing is completed, and when molded with transparent epoxy resin 9, the desired integrated circuit device can be obtained. is completed.

〔Effect of the invention〕

According to the present invention, in a semiconductor integrated circuit device in which a part of the element is a photodetecting element, after an insulating film containing silicon oxide as a main component is deposited on a semiconductor integrated circuit manufactured by a normal manufacturing method. , a surface protective film is deposited on the insulating film exposed in the photodetecting element part in such a way that the silicon nitride content decreases sequentially from the top layer containing silicon oxynitride, and the bottom layer becomes a silicon oxide film. did. The silicon oxynitride component has a lower refractive index than the silicon nitride component of conventional surface protection films, so there is less reflection loss at the interface with the transparent epoxy resin of the package, and the bottom layer is only a silicon oxide film. Because the composition has changed, there is no problem of reflection at the interface with the silicon oxide film on the substrate, and the adhesion of the interface is also good, making it necessary to remove the silicon nitride on the photodetector element that degrades the reliability of the entire device. It has become possible to obtain a semiconductor integrated circuit device having a photodetecting element with improved sensitivity and suppressing interfacial reflection of light.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a semiconductor integrated circuit device for optical signal processing according to an embodiment of the present invention. 1: N-type silicon substrate, 2: photodiode anode side layer, 4: silicon oxide film, 5+Aj wiring, 7: surface protection film, 8: light shielding film, 9: epoxy resin.

Claims (1)

[Claims] (1) In a device in which a part of the device is a photodetector and at least the part of the package located on the light incident path to the photodetector is made of transparent resin, an insulating film mainly composed of silicon oxide on the semiconductor substrate The part in contact with the insulating film is made of silicon oxide, the silicon nitride content increases sequentially, and the part in contact with the transparent resin layer is made of silicon oxynitride between the transparent resin layer and the light incident path to the photodetector element. 1. A semiconductor integrated circuit device characterized by having a surface protective film formed of: