JPH0394478A - Semiconductor device - Google Patents

Abstract

PURPOSE:To reduce the dispersion of the photosensitivity of a photodetector by forming the thickness of the passivation film of a chip composed of the photodetector and a semiconductor circuit on the same substrate so that the light-receiving region of the photodetector become thinner than sections on the outside of the light receiving region. CONSTITUTION:An N-type epitaxial growth layer 5 is formed onto a P-type silicon substrate 6, and an N-P-N type bipolar transistor 1 and a photodiode 2 are manufactured in two regions insularly isolated by P-N junction isolation by using a known bipolar IC manufacturing technique. A field silicon oxide film 7 and aluminum wiring electrodes 8, 9 and the like are shaped onto a surface, a silicon nitride film 3 is formed as a passivation film by employing a plasma CVD technique, and the silicon nitride film 10 of the surface protective film on the P-type light-receiving region 4 of the photodiode is dry-etched until the silicon nitride film 10 becomes thinner than the passivation film except the light-receiving region by using a known photolithographic technique. Accordingly, the dispersion of the photosensitivity of a photodetector can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor device incorporating a photodetector such as a phototransistor or photodiode for converting an optical signal into an electrical signal. Conventional Technology Conventionally, this type of semiconductor device has been an ellipse as shown in Figure 2. In Fig. 2, 1 is a bipolar transistor that controls the semiconductor circuit, and 2 is a photodiode that controls the light receiving element. 3 is a surface protective film made of silicon nitride or the like formed on this semiconductor integrated circuit.

Problems to be Solved by the Invention In such a conventional optical system, due to the multiple interference effect of incident light on the surface of the P-type light-receiving region 4 of the photodiode 2 constituting the light-receiving element @protection film 3, the photodiode Ripples as shown in FIG. 3 occur in the spectral sensitivity characteristics of No. 2. This caused variations in photocurrent sensitivity among the photodetectors, hindering quality stabilization. The present invention solves the above-mentioned problems, and aims to provide a semiconductor device that can reduce variations in photosensitivity of light-receiving elements and stabilize quality. Means for Solving the Problem In order to solve this problem, the semiconductor device of the present invention has a structure in which the thickness of the surface protective film on the light-receiving area of a light-receiving element such as a photodiode is made smaller than the thickness of the surface protective film on the light-receiving area other than the above-mentioned light-receiving area. It is also thinner. Effect: With this configuration, it is possible to eliminate the multiple interference effect caused by the surface protective film of the photodetector, and it is possible to reduce the variation in photocurrent sensitivity between photodetectors without reducing reliability. EXAMPLE An example of the present invention will be described below based on the drawings.

FIG. 1 is a cross-sectional structural diagram of a semiconductor device according to an embodiment of the present invention, in which an N-type epitaxial long layer 5 is formed on a P-type silicon substrate 6, and two islands are separated by PN junction separation. In the region, an NPN type bibolar transistor 1
The photodiode 2 and photodiode 2 are shown manufactured using the well-known bibolar IC manufacturing technology. Field silicon oxide WA7 on the surface, aluminum power distribution'! f18
．． 9 etc., using plasma CVD technology,
Silicon nitride II as a surface protective film! 3 to about 1.0 μm
The silicon nitride film 10 serving as the surface protection film on the P-type light receiving region 4 of the photodiode is dry etched to a thickness of about 0.3 μm using a well-known photolithography technique.

Effects of the Invention As described above, according to the present invention, in a semiconductor device in which a semiconductor circuit and a light receiving element are combined, variations in photosensitivity of the light receiving element can be reduced without deteriorating the reliability of the semiconductor device. You can get the effect that you can.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram showing a semiconductor device according to an embodiment of the present invention, FIG. 2 is a cross-sectional structural diagram showing a conventional semiconductor device,
Figure 3 shows an example of the spectral sensitivity characteristics of a photodiode in a conventional semiconductor device. DESCRIPTION OF SYMBOLS 1... Bibolar transistor, 2... Photodiode, 3... Silicon nitride surface protective film, 4... P-type light receiving region of photodiode, 5... N-type epitaxial layer, 6... P-type silicon substrate, 7... field silicon oxide film, 8.
9... Aluminum wiring electrode, 10... Silicon nitride surface protective film on the photodiode light receiving area.

Claims (1)

[Claims] 1. A semiconductor device in which the thickness of the surface protection film of a chip consisting of a light receiving element and a semiconductor circuit on the same substrate is thinner in the light receiving area of the light receiving element than in the outside of the light receiving area. .