JP2011160002A - Method of manufacturing solid-state imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a solid-state imaging apparatus in which the distance from a light receiving surface to below an in-layer lens is shortened to enhance light condensing efficiency without lowering sensitivity. <P>SOLUTION: A method of manufacturing the solid-state imaging apparatus having an effective pixel region and an optical black region for generating a reference signal, those regions being arranged on one principal surface of a substrate, includes: a first process of forming a first metal layer on the one principal surface of the substrate; a second process of forming a first insulating film on the first metal layer; a third process of forming a second metal layer for shielding the optical black region from light after the second process; a fourth process of forming a passivation layer and inner lens forming film without forming a flattening film after the third process; and a fifth process of processing the passivation layer and inner lens forming film to form the in-layer lens at least in the effective pixel region and forming a passivation film using the remaining film of the passivation layer and inner lens forming film after the formation of the in-layer lens. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

Relates to a manufacturing method of the present invention is a solid-state imaging device, more particularly to a method of manufacturing a solid-state image pickup device comprising a layer lens.

  In recent years, image input devices such as digital cameras, video cameras, and image readers are called CCD image sensors, non-CCD image sensors such as bipolar transistor image sensors, field effect transistor image sensors, and CMOS image sensors. A solid-state imaging device is used. In such an image input device, optical image information (optical image) is converted into an electric signal by a photoelectric conversion unit, and the converted electric signal is subjected to various signal processing and displayed on a display device or stored in a storage medium. Or recording.

  As a higher-performance solid-state imaging device, the area (pixel area) of the light-receiving surface of the photoelectric conversion element, which is a light-receiving unit that actually performs photoelectric conversion, is reduced, the number of arranged photoelectric conversion elements is increased, and solid-state imaging is performed. It is desired to reduce the chip size of the device.

  However, when the density of pixels and the reduction in size of chips are promoted, the amount of light that can be received by one photoelectric conversion element that becomes a pixel decreases as the area of the light receiving surface decreases, and the sensitivity of the apparatus is lowered. In order to improve this, a technique is known in which a microlens is formed on a flattened surface of a protective film provided on a light receiving surface, and the light is condensed on the light receiving surface to suppress a decrease in sensitivity.

  In addition, as the pixels are required to have higher density and smaller chips, an in-layer lens composed of a film having a refractive index different from that of the adjacent layer between the microlens and the photoelectric conversion element. The need to provide increased.

  For example, Patent Document 1 discloses a solid-state imaging device having a microlens and a convex inner lens. Here, the configuration of the solid-state imaging device disclosed in Patent Document 1 will be briefly described with reference to FIG. In FIG. 15, 13 is a semiconductor member, 1 is a photoelectric conversion element formed in the semiconductor member, and 2 is an element isolation region. Reference numeral 4 denotes a first wiring pattern, and reference numeral 6 denotes a second wiring pattern. The first wiring pattern 4 and the second wiring pattern 6 are separated by the first insulating film 3 and the second insulating film 5, respectively. ing. Then, after planarizing with the third insulating film 7 on the second wiring pattern 6, the convex inner lens 8 is formed. Further, after the inner planar lens 8 is planarized with the first planarizing film 9, the color filter layer 10 is formed, and after further planarizing with the second planarizing film 11, the microlens 12 is formed. Reference numeral 14 denotes a pad portion. It is described that if such a method is taken, the convex intra-layer lens 8 can be formed with high accuracy and the light collection efficiency can be increased without causing a substantial reduction in sensitivity.

  Here, a configuration in the case where a solid-state imaging device having a light shielding region at the end of the photoelectric conversion unit is designed based on Patent Document 1 will be described with reference to FIG.

  FIG. 16 shows a cross section of an end portion of the solid-state imaging device including the light receiving region and the light shielding region. In FIG. 16, 101 is a light shielding area pixel, 102 is a light receiving area pixel, 103 is a photosensitive area (photoelectric conversion element), 104 is a first metal wiring layer, 105 is a second metal wiring layer, and 106 is a first light shielding element for incident light. This is a three-metal wiring layer 106. Most of the photoelectric conversion element 103, the first metal wiring layer 104, the second metal wiring layer 105, and the third metal wiring layer are physically and electrically separated by an interlayer insulating film. Some are connected by contact plugs and via plugs. The pixels whose incident light is shielded by the third metal wiring layer 106 become pixels in the light shielding region, and the third metal wiring layer 106 is configured not to cover the light receiving region pixel 102. Reference numeral 112 denotes a planarizing film that fills the steps of the third metal wiring layer 106 so that the surface on which an inner lens 108 described later is formed becomes uniform. Reference numeral 107 denotes a passivation layer, and 108 denotes an in-layer lens. After forming the in-layer lens 108, planarization is performed by the planarization film 109 to form the color filter layer 110. Thereafter, the surface is further flattened by a flattening film 109, and a microlens 111 is formed thereon.

JP 2005-012189 A

  However, as shown in FIG. 16, when the solid-state imaging device is configured by the method as shown in FIG. 15, the distance from the light receiving surface to the lower side of the inner lens becomes longer, and conversely, the light collection efficiency is deteriorated. there were.

The present invention has been made in consideration of the above situation, to shorten the distance to the under-layer lens from the light-receiving surface, that you produce solid-state imaging device having improved light collection efficiency without producing desensitization Objective.

In order to achieve the above object, the manufacturing method of the present invention for a solid-state imaging device having an effective pixel region and an optical black region for generating a reference signal arranged on one main surface of the substrate includes: A first step of forming a first metal layer on one main surface; a second step of forming a first insulating film on the first metal layer; and for shielding the optical black region after the second step. A third step of forming the second metal layer, a fourth step of forming a passivation layer / inner lens forming film without forming a planarizing film after the third step, and forming the passivation layer / inner lens A film is processed to form an in-layer lens at least in the effective pixel region, and a passivation film is formed from the remaining film of the passivation layer / in-layer lens forming film after the formation of the in-layer lens. Including the extent, the.

According to the present invention, to shorten the distance to the under-layer lens from the light-receiving surface, can you to produce solid-state imaging device having improved light collection efficiency without causing desensitization.

It is sectional drawing which shows the structure of the solid-state imaging device which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the improvement effect of the solid-state imaging device which concerns on the 1st Embodiment of this invention. , , , , , , , It is a figure explaining the manufacturing method of the solid-state imaging device shown in FIG. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the solid-state imaging device shown in FIG. It is sectional drawing which shows the structural example of another solid-state imaging device of this invention. It is sectional drawing which shows the structural example of another solid-state imaging device of this invention. It is sectional drawing which shows the structure of the conventional solid-state imaging device. It is sectional drawing which shows the structure of the solid-state imaging device designed based on the prior art example.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components exemplified in this embodiment should be changed as appropriate according to the configuration of the apparatus to which the present invention is applied and various conditions. However, the present invention is not limited to these examples.

<First Embodiment>
A first embodiment of the present invention will be described.

  FIG. 1 is a diagram showing a cross section of the solid-state imaging device according to the first embodiment of the present invention, and shows an end of the solid-state imaging device having a light receiving region and a light shielding region. In FIG. 1, the same components as those in FIG. 16 are denoted by the same reference numerals, and description thereof is omitted. In the configuration shown in FIG. 1, the passivation portion 107 is formed directly on the interlayer insulating layer and the third metal wiring layer 106 without performing the planarization by the planarizing film 112 shown in FIG. The step of the layer 106 is left without being filled.

  With this configuration, in the configuration shown in FIG. 1 of the present embodiment, the leveling film 112 that fills the step of the uppermost metal layer can be made lower, so compared to the configuration shown in FIG. The height from the photoelectric conversion element 103 of the light receiving region pixel 102 to the lower side of the inner lens 108 can be configured to be low. For this reason, it is possible to increase the light collection efficiency, and it is possible to improve the decrease in sensitivity especially when the F number becomes small.

  FIG. 2 shows F-number dependent characteristics in the configuration shown in FIG. 16 and the configuration of the present embodiment. As shown in FIG. 2, it can be seen that in the configuration of the first embodiment, the sensitivity when the F number is small is improved as compared with the configuration to which the conventional method shown in FIG. 16 is applied.

  Next, the manufacturing process of the solid-state imaging device according to the first embodiment shown in FIG. 1 will be described with reference to FIGS.

  First, as shown in FIG. 3, a semiconductor member 121 made of a silicon wafer or the like is prepared, and an element isolation region 122 is formed on the semiconductor member 121 by a LOCOS method (silicon local oxidation method), an STI (shallow trench element isolation) method, or the like. To form. Next, a photoresist pattern is formed, and ion implantation and heat treatment are performed to form a diffusion layer on the semiconductor member 121, which serves as a cathode or an anode of a photodiode (photoelectric conversion element 103), for example.

  Subsequently, the first insulating film 123 is formed on the semiconductor member 121 by thermal oxidation, CVD (chemical vapor deposition), sputtering, coating, or the like. Here, if the surface of the first insulating film 123 is planarized by CMP or the like, the patterning accuracy in the next step can be improved.

  Next, a metal film made of Al, Mo, W, Ta, Ti, Cu, or an alloy containing these as a main component is formed on the first insulating film 123 by sputtering, CVD, electrolytic plating, or the like. The first pattern (first metal wiring layer) 104 having a desired shape is formed by removing a portion located above the light receiving surface of the photoelectric conversion element 103 by etching.

  Next, a second insulating film 124 made of SiO or a material mainly containing this is formed on the first insulating film 123 and the first metal wiring layer 104 by a CVD method. Here, if the surface of the second insulating film 124 is planarized by CMP or the like, the patterning accuracy in the next step can be improved.

  Next, similarly to the first metal wiring layer 104, a metal film made of Al, Mo, W, Ta, Ti, Cu, or an alloy containing these as a main component is formed by sputtering, CVD, electrolytic plating, or the like. A second pattern (second metal wiring layer) 105 having a desired shape is formed by etching on the second insulating film 124 and removing the portion located above the light receiving surface of the photoelectric conversion element 103 by etching. To do.

  Note that the first and second metal wiring layers 104 and 105 function as wirings used for transmission of electric signals from the photoelectric conversion element 103, and light to be incident on one photoelectric conversion element 103 is another photoelectric conversion element 103. It also functions as a light-shielding plate that prevents the light from entering the light.

  Next, a third insulating film 125 made of SiO or a material mainly containing this is formed on the second insulating film 124 and the second metal wiring layer 105 by a CVD method. Here, if the surface of the third insulating film 125 is planarized by CMP or the like, the patterning accuracy in the next step can be improved.

  Next, similarly to the first pattern 104 and the second pattern 105, a metal film made of Al, Mo, W, Ta, Ti, or Cu, or an alloy containing these as a main component is formed by sputtering, CVD, or A third pattern (third metal wiring layer) 106 having a desired shape is formed by forming the second insulating film 125 on the second insulating film 125 by electrolytic plating or the like, and removing a portion located in the light receiving region by etching. . The third metal wiring layer 106 is formed to include a light shielding member for forming a light shielding region (optical black) for generating a reference signal in a region outside the effective pixel region.

  Next, a passivation layer / in-layer lens forming film 107 ′ made of SiN, SiON, SiO, or the like is formed on the third metal wiring layer 106 and the third insulating film 125 by the CVD method.

  Subsequently, as shown in FIG. 3, an etching mask 126 for forming the inner lens 108 is formed on the passivation layer / inner lens forming film 107 'by a photolithography process. Thereafter, as shown in FIG. 4, the etching mask 126 is reflowed by heat treatment to form a convex lens shape substantially the same as the shape of the in-layer lens 108. In the present embodiment, the inner lens is also formed in the light shielding region.

Next, the entire surface of the passivation layer / inner lens forming film 107 ′ is etched, and the convex lens shape of the etching mask 126 is transferred to the passivation layer / inner lens forming film 107 ′ as shown in FIG. The inner lens 108 is formed. As the etching gas here, CF ₄ , CHF ₃ , O ₂ , Ar, He, or the like can be used. The etching remaining film of the passivation layer and in-layer lens forming film 107 ′ becomes the passivation layer 107.

  Subsequently, as shown in FIG. 6, in order to open the pad portion 128 ′ by photolithography, a resist pattern 127 having such an opening pattern is formed on the passivation layer 107 and the intralayer lens 108, and FIG. As shown in FIG. 3, the passivation layer 107 located on the pad portion 128 is removed by photolithography.

  Thereafter, as shown in FIG. 8, a first planarizing film 109 is formed on the pad portion 128, the passivation layer 107, and the inner lens 108, and a color filter layer is formed on the first planarizing film 109. 110 is formed. The color filter layer 110 has a color pattern corresponding to the color of light incident on each photoelectric conversion element 103 below the color filter layer 110.

  Subsequently, as shown in FIG. 9, a second planarizing film 109 is formed on the color filter layer 110, and a microlens 111 is formed by resist patterning and reflow. Finally, as shown in FIG. 10, the first and second planarization films 109 remaining above the pad portion 128 are removed by etching to open the upper portion of the pad portion 128.

  Through the above steps, the solid-state imaging device shown in FIG. 1 can be manufactured.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.

  FIG. 11 is a diagram showing a cross section of the solid-state imaging device according to the second embodiment of the present invention, and shows an end portion of the solid-state imaging device having a light receiving area and a light shielding area. In FIG. 11, the same components as those in FIG.

  In the configuration of FIG. 1, since the inner lens 108 is also formed on the third metal wiring layer 106 that is a light shielding region, the micro lens 111 is prevented from being inclined at the boundary between the light receiving region and the light shielding region. Therefore, it is necessary to form the first planarization film 109 thick.

  On the other hand, in the configuration according to the second embodiment shown in FIG. 11, the inner lens 108 is not formed on the third metal wiring layer 106 that is the light shielding region. Thereby, the first planarizing film 109 can be made thinner than the structure of FIG. Thereby, it is possible to increase the light collection efficiency, and it is possible to further improve the decrease in sensitivity particularly when the F number becomes small.

  The manufacturing method having the configuration shown in FIG. 11 is different from the first embodiment in that the etching mask 126 for forming the inner lens 108 is not configured in the light shielding region as shown in FIG. Since it is the same, description is abbreviate | omitted. The process shown in FIG. 12 corresponds to the process of FIG.

  As described above, according to the present embodiment, since the distance from the photoelectric conversion unit 3 to the microlens 111 can be shortened, the light collection efficiency can be further increased.

<Modification>
FIG. 13 is a diagram showing a cross section of another solid-state imaging device according to the present invention, and shows an end of the solid-state imaging device having a light receiving region and a light shielding region. In FIG. 13, the same components as those in FIG. FIG. 13 shows a configuration having only the first metal wiring layer 104 and not having the second metal wiring layer 105 unlike the first and second embodiments.

  FIG. 14 is a diagram showing a cross section of another solid-state imaging device according to the present invention, and shows an end of the solid-state imaging device having a light receiving region and a light shielding region. In the configuration shown in FIG. 14, the thickness of the third metal wiring layer 206 is made thinner than that of the third metal wiring layer 106 in the second embodiment, and the thickness of the inner lens 108 is almost the same as the step of the passivation layer 107. This shows the case.

  As described above, even in the configuration shown in FIGS. 13 and 14, the height from the photoelectric conversion element 103 of the light receiving region pixel 102 to the lower side of the inner lens 108 can be reduced, so that the light collection efficiency can be increased. .

DESCRIPTION OF SYMBOLS 101 Light shielding area pixel 102 Light receiving area pixel 103 Photoelectric conversion element 104 1st metal wiring layer 105 2nd metal wiring layer 106,206 3rd metal wiring layer 107 Passivation layer 107 'Passivation layer and in-layer lens formation film 108 Intralayer lens 109 Flattening film 110 Color filter layer 111 Micro lens 112 Flattening film 121 Semiconductor member 122 Element isolation region 123 First insulating film 124 Second insulating film 125 Third insulating film 126 Etching mask 127 Resist pattern 128 Pad portion

Claims (7)

  A method of manufacturing a solid-state imaging device having an effective pixel region and an optical black region for generating a reference signal, which are arranged on one main surface of a substrate,
  A first step of forming a first metal layer on one principal surface of the substrate;
  A second step of forming a first insulating film on the first metal layer;
  A third step of forming a second metal layer for shielding the optical black region after the second step;
  A fourth step of forming a passivation layer-in-layer lens forming film without forming a planarizing film after the third step;
  The passivation layer / inner lens forming film is processed to form an inner lens in at least the effective pixel region, and the passivation film is formed by the remaining film of the passivation layer / inner lens forming film after the inner lens is formed. A fifth step of forming,
  A method for manufacturing a solid-state imaging device, comprising:   The method for manufacturing a solid-state imaging device according to claim 1, further comprising a sixth step of forming a planarizing film after the fifth step.   The method for manufacturing a solid-state imaging device according to claim 2, further comprising a seventh step of forming a color filter after the sixth step.   The method for manufacturing a solid-state imaging device according to claim 3, further comprising an eighth step of forming a microlens after the seventh step.   5. The method of manufacturing a solid-state imaging device according to claim 4, further comprising a ninth step of forming a second planarization film before the eighth step.   A tenth step of removing a portion corresponding to the pad portion of the passivation film after the fifth step;
  After the ninth step, the method includes an eleventh step of exposing the pad portion by removing a part of the planarizing film and the second planarizing film formed in the sixth step. A method for manufacturing a solid-state imaging device according to claim 5.   In the fifth step, the optical black region is not formed with the inner lens, but is formed by the remaining film of the passivation layer / inner lens forming film after forming the inner lens formed in the effective pixel region. The method for manufacturing a solid-state imaging device according to any one of claims 1 to 6, wherein a passivation film is formed.

Images