JPS58107671A - Image sensor ic - Google Patents

Abstract

PURPOSE:To omit wiring space for laying and to obtain freedom in wiring, by using a second metal layer, which shields light for the active region of an image sensor IC instead of complicated wiring included in a first metal layer. CONSTITUTION:A window is provided in an SiO2 film 4 on a silicon chip. Patterning is performed for a sensor part 3, a signal processing part, a logic part, and the like, with the first wiring metal layer 5. Then, an insulating layer 6 of SiO2, Si3N4, or the like is formed on the active region 2, i.e. the entire part corresponding to the signal processing part and logic part, by a low temperature CVD method and the like. Thereafter, a metal layer 7 ofr screening and wiring, which is a second layer, is applied so as to cover the active region 2 of the IC through the insulating layer 6 and so that it is connected with the first layer wiring metal layer through a contact hole 8. As a result, power source lines and ground lines, which have been forced to be laid in a complicated pattern in the first layer wiring, can be laid in the second layer wiring.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention consists of 5. This invention relates to light shielding of an active region of an image sensor IC.

An image sensor IC is usually constructed by forming a part of an image sensor (for example, a photodiode array), a signal processing section (such as an A/D converter), a logic section, etc. on the same silicon substrate. In this IC, the operation is performed by optically forming an image on an image sensor and processing the output from the sensor. However, light naturally leaks to parts other than the sensor. In this case, if an undesirable current is generated due to the photoelectric effect, it will cause a significant problem in signal processing. Therefore, it is necessary to shield parts other than the sensor by some method. Conventionally, this type of image sensor IC In this method, a method as shown in FIG. 1 is used to shield an active region (that is, a portion where an undesirable generated current flows when exposed to light) including a signal processing section and a logic section from light. This image sensor IC is manufactured by forming a sensor 3 corresponding to a sensor region 1, a signal processing section, a logic section, etc. corresponding to an active region 2 on the same silicon substrate. Then, in the final process of image sensor IC manufacturing, 8i0
After completing the opening of the 2 film 4 and the patterning of the wiring metal 5 such as aluminum, the entire active region is coated with 8i0z or S.
An insulating layer 6 of i3N4 or the like is formed by low-temperature CVD or the like, and then the insulating layer is photo-etched (window opening process for bonding pads, etc.), and then a metal such as aluminum is further formed on the active region 2 for light-shielding purposes. A coating layer 7 is formed.

Thus, the present invention provides an image sensor I as described above.
In C, the light-shielding metal layer, such as aluminum, is not used only for the purpose of light-shielding, but is intended to be actively used as a part of the second wiring metal layer. That is, the second metal layer is used as a substitute for a part of the first wiring metal layer by forming through holes in the insulating layer below it. As a result, parts that conventionally required a large amount of area on the first layer wiring (for example, routing power lines and ground lines) can be absorbed into the second layer wiring, making wiring design easier and chipping easier. It becomes possible to obtain many benefits such as cost reduction due to size reduction.

Therefore, according to the present invention, the sensor region consisting of a part of the image sensor and the active region including the signal processing section and the logic section coexist, and the first metal layer for wiring connecting these sections is connected to the first metal layer for interconnection. In an image sensor IC, an insulating layer is provided on a metal layer, and a second light-shielding metal layer is provided on a portion of the insulating layer corresponding to directly above the active region,
An image sensor IC is provided, characterized in that the second metal layer is connected to the first metal layer through an insulating layer and used as part of the wiring of the second metal layer.

The image sensor IC of the present invention will be explained below with reference to FIG.

FIG. 2 shows an embodiment of the image sensor IC according to the present invention, where 1 indicates a sensor area and 2 indicates an active area. First, a window is opened in the 5i02 film 4 on the silicon chip, and the sensor part 3, the signal processing part, the thick part, etc. are patterned with the i-metal layer 5 for wiring.

Next, an insulating layer 6 of 8i02, Si3N4, etc. is formed over the entire active region 2.6, that is, the portion corresponding to the signal processing section and the logic section.
is formed by a low temperature CVD method or the like. Next, a second light-shielding/wiring metal layer 7 is applied so as to cover the active region 2 of the IC via the insulating layer 6 and at the same time connect to the first wiring metal layer through the contact hole 8 . As a result, it becomes possible to entrust the power supply line and the ground line, which were conventionally forced to be complicatedly routed in the first layer wiring, to the second layer wiring.

As described above, according to the present invention, part or all of the second metal layer that shields the active region of the image sensor Since it is configured to be used in place of a conventional IC, the wiring space for routing, which occupies most of the area of a conventional IC, can be omitted, and the degree of freedom in wiring can also be increased. This makes it possible to simplify the design (for example, significantly shorten the design time) and reduce the chip size, contributing to cost reduction.

The image sensor IC of the present invention is preferably used as an autofocus IC for a camera, for example.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional image sensor IC. FIG. 2 is a cross-sectional view of a specific example of an image sensor IC according to the present invention. Here, 1 is a sensor region, 2 is an active region, 3 is a part of the sensor, 4 is an 8i02 film, 5 is a first metal layer for wiring, 6 is an insulating layer, 7 is a second gold maple layer for wiring and light shielding, 8 is the metal layer kutohole.

Claims (1)

[Claims] 1) A sensor region consisting of a part of the image sensor and an active region including a signal processing section and a logic section coexist, and a first metal layer for wiring connecting these parts is placed on top of the first metal layer with an insulating layer. Then, in an image sensor IC in which a second metal layer for light-shielding is provided on the insulating layer corresponding to the portion directly above the active region, the second metal layer is passed through the insulating layer to form the first metal layer. An image sensor IC characterized in that it is used as part of the wiring of the second metal layer by being connected to the second metal layer.