JPH10107238A - Solid state image-sensing device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid state image-sensing device and its manufacturing method which reduce etching damage at wiring pads in formation of on-chip lens by etch-back processing, so as to stabilize the wiring pads. SOLUTION: A flat film 4 is formed on sensors 1 and a pad 2 formed on a semiconductor substrate, and color filters 3 are formed on the flat film 4 at the sensors 1 and the pad 2. Then, lens material 5 is applied to the flat film 4, and a lens pattern 6 is formed by a photolithography process and a heat process. Next, the entire surface is etched back to form an on-chip lens. At this time, as the color filter 3 on the pad 2 remains, the thickness of the etched-back film on the pad 2 is thick, and the damage on the pad 2 upon etching back of on-chip lens is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device used for, for example, a camera-integrated VTR and a method of manufacturing the same, and more particularly, to a wiring pad having an on-chip microlens on the front side of a solid-state image pickup device light receiving portion. The present invention relates to a solid-state imaging device having an improved method for forming a substrate and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, efforts have been made to improve the resolution and performance of solid-state imaging devices. In this solid-state imaging device, a microlens for improving sensitivity is generally formed on the front side of a light receiving unit for each pixel. There is an on-chip type micro lens (hereinafter simply referred to as “on-chip lens”) formed by etch-back as a method of forming a micro lens. Hereinafter, a method for manufacturing a conventional on-chip lens for a solid-state imaging device related to the present invention will be described with reference to FIG. 3A to 3C are cross-sectional views showing a process of manufacturing a conventional on-chip lens for a solid-state imaging device, in which FIG. It is.

When an on-chip lens for a solid-state imaging device is formed by etch-back, as shown in FIG. 3A, a sensor portion 1 and a wiring pad portion (bonding pad portion: hereinafter referred to as a bonding pad portion) formed on a semiconductor substrate. A flattening film 4 is applied on the (pad portion) 2 by a coater. The color filter 3 is formed on the flattening film 4, and after the lens material 5 is applied by a coater, a resist is applied to the sensor portion 1 using a photomask (reticle: not shown) by a photolithography process. Pattern at the corresponding position. Thereafter, the lens surface 6 is formed by heat treatment to make the resist surface spherical.

Next, the entire surface is etched back with an etch back amount 7 to form an on-chip lens 8 as shown in FIG. At this time, in order to expose the metal of the pad portion 2 used for wiring with the chip package, the upper flattening film 4 is also etched back on the pad portion 2 when the lens material 5 is etched back. The process of obtaining the shape of (b) is employed.

However, since the etch-back amount 7 of the lens material 5 is determined so as to optimize the shape of the on-chip lens 8, the etch-back amount 7 is determined because the on-chip lens 8 having a large curvature is formed. If you increase
The amount of etching received by the flattening film 4 on the pad portion 2 also increases. Since the etching rate of the flattening film 4 is higher than the etching rate of the lens material 5, the pad section 2 is exposed to the etching atmosphere for a long time even after the metal of the pad section 2 is exposed. As a result, damage occurs in the pad portion 2. In particular, when the on-chip lens 8 is formed on a wafer having a needle mark due to measurement in the pad portion 2, the metal of the pad portion 2 may directly contact the semiconductor substrate, resulting in a product defect.

In order to improve the sensitivity to light having a small F-number, a technique of forming a lens at a low position is used. That is, if the color filter 3 is formed directly on the protective film (not shown) without using the flattening film 4, the lens position can be lowered. However, when the on-chip lens 8 is formed without using the flattening film 4, when the color filter 3 is formed by exposure and development using a photoresist, the exposed metal of the pad portion 2 is etched by the developer. There's a problem.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object of the present invention is to provide a pad portion when an etch back amount is increased to form an on-chip lens having a large curvature. It is to reduce the damage. Another object of the present invention is to prevent a pad portion from being etched when an on-chip lens is formed without using a flattening film in order to improve sensitivity to light having a small F value, and to prevent the pad portion from being etched. An object of the present invention is to provide a stabilized solid-state imaging device and a method for manufacturing the same.

[0008]

According to the present invention, there is provided a method for manufacturing a solid-state imaging device in which a microlens provided on the front surface of a sensor unit of a solid-state imaging device is formed by etch-back according to the present invention. A step of forming a flattening film on the semiconductor substrate on which at least the wiring pad portion is formed, and a step of forming a color filter at a position of the sensor portion and the wiring pad portion on the flattening film,
Forming a lens material at a position corresponding to the sensor portion on the color filter and performing patterning, while leaving the color filter on the wiring pad portion, etching back to form an on-chip lens and a wiring pad window; and Shall be included. This makes it possible to increase the film thickness etched back on the wiring pad portion, and to reduce damage to the wiring pad portion when the on-chip lens is etched back.

According to another aspect of the present invention, there is provided a method of manufacturing a solid-state imaging device in which a microlens provided on the front surface of a sensor unit of a solid-state imaging device is formed by etch-back.
Forming a predetermined color filter on the sensor portion on the semiconductor substrate, forming a color filter formed at least at the very beginning of the color filter on the wiring pad portion on the semiconductor substrate; Forming a lens material at a position corresponding to the sensor unit and performing patterning, and, while leaving the color filter on the wiring pad unit, etching back to form an on-chip lens and a wiring pad window. I do. This can prevent the developer or the like of the color filter material from directly touching the metal of the wiring pad portion, and can prevent the wiring pad portion from being etched.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The present invention is characterized in that, when simultaneously performing the etch-back of the on-chip lens and the formation of the wiring pad portion of the device, the etch-back is performed with the color filter left on the pad portion. Thus, the main purpose is to reduce damage to the pad portion.

First Embodiment First, a first embodiment of a solid-state imaging device and a method of manufacturing the same according to the present invention will be described with reference to FIG. FIG. 1 is a manufacturing process diagram of Embodiment 1 of an on-chip lens for a solid-state imaging device according to the present invention, and is a cross-sectional view showing a process before etch-back. The same parts as those in the conventional method of manufacturing a solid-state imaging device are denoted by the same reference numerals, and a sectional view of the process after etch-back is omitted.

When an on-chip lens is formed by the method for manufacturing a solid-state imaging device according to the present invention, as shown in FIG.
A flattening film 4 is formed on the sensor portion 1 and the pad portion 2 formed on the semiconductor substrate, and the sensor portion 1 on the flattening film 4 and a color filter also on the pad portion 2 as a feature of the present invention. Form 3 At this time, the color filter 3
It is formed by a process of patterning and dyeing a material or by a process of patterning a color resist. Therefore, in order to leave the color filter 3 on the pad 2, a reticle for patterning the color filter should be formed so that the material of the color filter 3 remains on the pad 2 when patterning the color filter 3. Good. The size of the color filter 3 to be left needs to be larger than the area of the pad portion 2. Accordingly, the thickness of the etched back portion on the pad portion 2 is increased, and the damage to the pad portion 2 during the etch back of the on-chip lens can be reduced.

Further, the color filter 3 of the solid-state image pickup device
In many cases, a plurality of colors are formed for one device. In this case, since a layer of each color is formed one layer at a time, a color filter 3 left on the pad portion 2 so that damage to the pad portion 2 is reduced. Can be arbitrarily adjusted. Thereby, it is possible to avoid the damage of the pad portion 2 according to the etching condition.

After the lens material 5 is applied by a coater, a lens pattern 6 is patterned at a position corresponding to the sensor unit 1 by using a reticle (not shown) by a photolithography process and heat treatment. Next, the entire surface is etched back to form an on-chip lens and a pad window.

Second Embodiment In the second embodiment, at least the first formation is performed when the flattening film used in the first embodiment is not used in order to improve the focusing state of the on-chip lens. This is a manufacturing method in which the color filter thus formed is left on the pad portion, which will be described with reference to FIG. FIG. 2 is a manufacturing process diagram of Embodiment 2 of the on-chip lens for a solid-state imaging device of the present invention, and is a cross-sectional view showing a process before etch-back.

In the method for manufacturing a solid-state image pickup device according to the present invention shown in FIG.
The film thickness to be etched back on the pad portion 2 is increased to reduce the damage at the time of etching back the on-chip lens. In particular, the flattening film 4 used in the first embodiment
When the color filter 9 is not used, it is necessary to leave at least the first formed color filter 9 on the pad portion 2 as in the present invention. The reason will be described below.

To form a color filter, the material is exposed and developed to form a color filter structure, and then, if necessary, dyeing is performed. For example, when the material of the color filter is colored as in the case of a color resist, the dyeing step is not required. In order to form color filters of a plurality of colors, this operation is repeated a predetermined number of times. In any case, in order to form the structure of the material,
Exposure and development steps are required.

Incidentally, metal is exposed in the pad portion 2 for wiring. The exposed metal is etched by the developing solution of the color filter material.
To prevent this, patterning is performed with a reticle (not shown) that leaves at least the first formed color filter 9 on the pad portion 2. This prevents the developer or the like of the color filter material from directly touching the metal of the pad portion 2 and prevents the pad portion 2 from being etched. After the pad portion 2 is covered with the color filter 9 formed first, the pad portion 2 may be covered with several layers of color filters as necessary. The reason why the structure without using the flattening film 4 is used is to lower the lens formation position for the purpose of improving the condensing state of the on-chip lens as described above.

Then, after applying the lens material 5 by a coater, a lens pattern 6 is patterned at a position corresponding to the sensor unit 1 using a reticle by a photolithography process and heat treatment. Next, the entire surface is etched back to form an on-chip lens and a pad window. Subsequent steps are duplicated and will not be described.

The present invention is not limited to the above-described embodiment, but can adopt various embodiments. For example, although the solid-state imaging device has been described in the above embodiment, an AMI (Amplified MOS Intelligent Ima
ger) devices, MOS type devices, CCD line sensors, etc., and are not limited to the structure of the solid-state imaging device. It goes without saying that the present invention can be applied to other image input devices.

[0022]

According to the solid-state imaging device and the method of manufacturing the same according to the present invention described above, when manufacturing the solid-state imaging device,
With the color filter left on the wiring pad,
Since the etch back of the on-chip lens and the wiring pad window is started, the difference in the amount of etching between the on-chip lens portion and the wiring pad portion can be reduced, and damage to the wiring pad portion can be reduced. As a result, it is possible to prevent the occurrence of product defects such as leaks caused by excessively etching the wiring pad portion.

According to another aspect of the present invention, there is provided a solid-state image pickup device and a method of manufacturing the same, wherein the color filter formed at least first on the wiring pad portion in the solid-state image pickup device having no flattening film under the color filter. Since it is formed, it is possible to prevent the wiring pad portion from being etched when developing the color filter, and it is possible to stabilize the electrical connection in the wiring pad portion.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a first embodiment of an on-chip lens for a solid-state imaging device according to the present invention, which is a process cross-sectional view before etch-back.

FIG. 2 is a manufacturing process diagram of a second embodiment of the on-chip lens for a solid-state imaging device according to the present invention, and is a cross-sectional view showing a step before etch back.

3A and 3B are cross-sectional views illustrating a process of manufacturing a conventional on-chip lens for a solid-state imaging device, in which FIG. 3A is a process cross-sectional view before etch-back of the on-chip lens, and FIG. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sensor part, 2 ... Pad part, 3 ... Color filter, 4 ... Planarization film, 5 ... Lens material, 6 ... Lens pattern, 7 ... Etch back amount, 8 ... On-chip lens , 9 ... The first color filter formed

Claims (5)

[Claims] 1. A method for manufacturing a solid-state imaging device, wherein a microlens provided on a front surface of a sensor unit of a solid-state imaging device is formed by etch-back, wherein a flattening film is formed on a semiconductor substrate on which a sensor unit and a wiring pad unit are formed. Performing a step of forming a color filter at a position of the sensor section and the wiring pad section on the flattening film; and performing a patterning by forming a lens material at a position corresponding to the sensor section on the color filter, Forming an on-chip microlens and a wiring pad window by etching back while leaving the color filter on the wiring pad section. 2. The color filter formed on the wiring pad portion has a larger size than the area of the wiring pad portion, and the number of color filters is arbitrary so that etching damage to the wiring pad portion is reduced. The method for manufacturing a solid-state imaging device according to claim 1, wherein adjustment is possible. 3. A method for manufacturing a solid-state imaging device, wherein a microlens provided on the front surface of a sensor unit of the solid-state imaging device is formed by etch-back. Forming a color filter formed at least at the beginning of the color filter on the wiring pad portion, and forming a lens material at a position corresponding to the sensor portion on the color filter and performing patterning; Forming an on-chip microlens and a wiring pad window by etching back while leaving the color filter on the wiring pad portion. 4. The number of color filters formed on the wiring pad portion is arbitrary so that the size of the color filter is larger than the area of the wiring pad portion and etching damage of the wiring pad portion is reduced. The method for manufacturing a solid-state imaging device according to claim 3, wherein the method is adjustable. 5. A solid-state imaging device manufactured by the manufacturing method according to claim 1, 2, or 3.