JP2009157397A - Method for manufacturing solid image pickup device and solid image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a solid image pickup device capable of manufacturing a solid image pickup device having high sensitivity by reducing an invalid region. <P>SOLUTION: The method for manufacturing a solid image pickup device having a lens of which surface side is convex on each sensor part comprises: a process for forming a film of lens material with a plasma CVD film on a planarized film; a process for forming a resist of a predetermined lens shape on the film of lens material; a process for transferring the lens shape of this resist onto the film of lens material in a manner so as to expand the gap between the convex lenses; and a process for forming a lens by making a film of the same lens material on the film of lens material onto which the lens shape has been transferred, by a plasma CVD method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a solid-state imaging device formed by forming an in-layer lens on a sensor, and a solid-state imaging device.

With the miniaturization of solid-state image sensors, improvement in sensitivity is demanded, and the sensitivity cannot be improved only with the uppermost on-chip lens on the color filter, which is a conventional technology, and between the on-chip lens and the sensor unit. Further, it is considered to form a lens (in-layer lens).
As an example of the in-layer lens, there is an in-layer convex lens in which a lens having a convex surface on the surface side is formed on a surface flattened by filling a step due to a transfer electrode or the like.

One method of manufacturing this intra-layer convex lens is a method of dry etching a laminated film of a lens material film and a resist of the intra-layer convex lens.
In this method, a lens material film is deposited, a resist is patterned on the lens shape thereon, and then the lens shape of the resist is transferred to the lens material film by dry etching.

However, in the process of transferring the lens shape to the lens material, the gap between the in-layer convex lenses is widened by the side etching of the dry etching.
Light that has entered the gap between the in-layer convex lenses cannot be incident on the sensor unit because it is not focused by the in-layer convex lens.

Therefore, the gap portion between the lenses is an invalid area for the incident light.
As the invalid area is formed in this way, the sensitivity of the solid-state imaging device is lowered accordingly.

  In order to solve the above-described problems, in the present invention, a solid-state imaging device manufacturing method capable of manufacturing a solid-state imaging device having high sensitivity by reducing the ineffective region, and a solid-state imaging device having high sensitivity are provided. Is to provide.

The method for manufacturing a solid-state imaging device according to the present invention includes a step of forming a lens material film on a planarizing film by a plasma CVD film when manufacturing a solid-state imaging device having a lens having a convex surface on each sensor portion. And a step of forming a lens-shaped resist having a convex surface on the lens material film, and a lens shape having a convex surface on the surface side of the resist so that the gap between the convex lenses is widened in the lens material film. The method includes a step of transferring, and a step of forming a lens by forming a film of the same lens material on the lens material film onto which the lens shape has been transferred by a plasma CVD film.
The solid-state imaging device of the present invention has a lens having a convex surface on each sensor part, and the lens is further formed on a lens-shaped lens material film having a convex surface on the surface side by a plasma CVD film. The same lens material film is formed by a plasma CVD film.

According to the above-mentioned manufacturing method of the present invention, when the lens shape is transferred by forming the lens by forming the same lens material film on the lens material film to which the lens shape has been transferred, for example, side etching is performed. The distance between the lenses can be shortened by filling the space between the more distant lenses, and the ineffective area between the lenses can be reduced.
According to the above-described solid-state imaging device of the present invention, the lens is formed by further forming the same lens material film on the lens material film, thereby reducing the distance between the lenses and invalid regions between the lenses. Can be reduced.

According to the above-described present invention, since the gap between the convex lenses that has been an ineffective area for incident light can be narrowed, the effective area can be expanded and the sensitivity can be improved.
Therefore, according to the present invention, a highly sensitive solid-state imaging device can be manufactured.

Further, according to the present invention, it is possible to arbitrarily adjust the gap length between the lenses by arbitrarily changing the film thickness of the lens material to be formed.
Therefore, it is possible to improve the sensitivity with respect to the solid-state imaging device having unit cells of various dimensions.

1A to 1C are manufacturing process diagrams (cross-sectional views) showing an embodiment of a method for manufacturing a solid-state imaging device of the present invention. DF is a manufacturing process diagram (cross-sectional view) showing an embodiment of a method for manufacturing a solid-state imaging device of the present invention. It is a schematic block diagram (sectional drawing) of the CCD solid-state image sensor to which this invention is applied.

The present invention relates to a method of manufacturing a solid-state imaging device having a lens having a convex surface on each sensor portion, the step of forming a lens material film on a planarizing film by a plasma CVD film, and the lens material Forming a lens-shaped resist having a convex surface on the surface , transferring the lens shape having a convex surface on the resist surface to the lens material film so that a gap between the convex lenses is widened, and a lens. And a step of forming a lens by forming a film of the same lens material on the film of the lens material to which the shape has been transferred by a plasma CVD film.

The present invention has a lens having a convex surface on each sensor part. This lens is formed by a plasma CVD film, on a lens-shaped lens material film having a convex surface, and further by a plasma CVD film. It is a solid-state imaging device formed by forming a film of the same lens material.

FIG. 3 is a schematic configuration diagram (cross-sectional view) of a CCD solid-state imaging device as a solid-state imaging device to which the manufacturing method of the present invention is applied.
In the CCD solid-state imaging device 1, for example, a sensor unit 2 made of a photodiode is arranged on the surface of a semiconductor substrate 4 made of silicon, and a transfer electrode 11 made of polycrystalline silicon is interposed via an oxide film 5 on the semiconductor substrate 4. Is formed.
An oxide film 5 is formed on the transfer electrode 11, and an oxide film, for example, is formed thereon as the interlayer insulating film 6.

  A light shielding film 3 made of an Al film or a refractory metal film (for example, tungsten, molybdenum, tantalum) is formed on the interlayer insulating film 6. In the light shielding film 3, an opening 3 a is formed on the sensor unit 2 so that light enters the sensor unit 2.

  A planarizing film 7 is formed on the entire surface so as to cover the light shielding film 3, and an intralayer lens 9 made of an insulating film (SiN film or SiON film) 8 formed by, for example, plasma CVD is formed on the planarizing film 7. Yes. This inner lens 9 has a convex surface on the upper surface 9a on the front side and a flat surface on the lower surface 9b, and constitutes the above-mentioned intra-layer convex lens.

A color filter 17 is formed on the in-layer lens 9 via a planarizing film 16. Further, an on-chip lens 19 is formed thereon via a planarizing film 18.
A CCD transfer channel 15 constituting the vertical transfer register 10 is formed in the semiconductor substrate 4, and a channel stop region is formed between the sensor unit 2 and the CCD transfer channel 15 (not shown).

  The CCD solid-state imaging device 1 has a planar structure (not shown), but a large number of sensor units 2 are arranged in a matrix corresponding to the pixels, and each sensor unit 2 has a CCD transfer channel 15 on one side. A vertical transfer register 10 having a CCD structure is provided.

According to the configuration of the CCD solid-state imaging device 1, since the in-layer lens 9 is formed on the sensor unit 2, the light collected by the on-chip lens 19 is further condensed by the in-layer lens 9. Thus, the light can be efficiently incident on the sensor unit 2.
That is, by providing the on-chip lens 19 and the in-layer lens 9, incident light can be efficiently incident on the sensor unit 2 and has high sensitivity.

  Subsequently, as one embodiment of the method for manufacturing the solid-state imaging device of the present invention, a manufacturing process when the CCD solid-state imaging device 1 shown in FIG. 3 is manufactured by the manufacturing method of the present invention will be described with reference to FIGS. I will explain.

  First, as shown in FIG. 1A, the transfer channel 15 and the photodiode of the sensor unit 2 are formed in the semiconductor substrate 4, and the layers up to the light shielding film 3 such as the transfer electrode 11 are formed. In the light shielding film 3, an opening 3 a is formed on the sensor unit 2.

Next, as shown in FIG. 1B, a planarizing film 7 is formed so as to cover the light shielding film 3.
As the planarizing film 7, a reflow film or an HDP (high density plasma) -CVD film can be used, whereby the surface can be planarized.

Note that a material for the light shielding film 3 is selected in accordance with the planarization method.
For example, when a reflow film is used, a high melting point metal is used for the light shielding film 3 because high temperature reflow is required for planarization.
On the other hand, when flattening with a CVD film, the light shielding film 3 may be formed of aluminum or the like.

Subsequently, wiring for a peripheral circuit portion of a CCD solid-state imaging device (not shown) is formed.
Thereafter, as shown in FIG. 1C, a plasma CVD film 8 serving as a lens material is formed on the planarizing film 7.
When the refractive index of the in-layer lens 9 is set to 1.9 to 2.0, a plasma SiN film is formed as the plasma CVD film 8 and the refractive index of the in-layer lens 9 is set to 1.5 to 1.9. In this case, a plasma SiON film is formed as the plasma CVD film 8.
Then, the plasma CVD film 8 is formed to a thickness of 0.5 to 2.0 μm according to the required height of the in-layer lens 9.

Next, a resist 21 is applied on the plasma CVD film 8 and desired patterning is performed. Then, the resist 21 is reflowed at 140 to 180 ° C. in order to obtain a lens shape.
Thereby, the lens-shaped resist 21 shown in FIG. 2D is formed.

  Next, by performing dry etching, the lens shape of the resist 21 is transferred to the plasma CVD film 8 to form an in-layer lens 9 as shown in FIG. 2E. At this time, the gap between the convex lenses is widened by dry etching side etching.

Therefore, as shown in FIG. 2F, a film of the same type as the lens material film (plasma CVD film 8) of the in-layer lens 9, that is, a plasma CVD film 22 is deposited by plasma CVD.
Thereby, the gap between convex lenses can be narrowed.
At this time, the film thickness of the plasma CVD film 22 can be arbitrarily set, and the gap length can be adjusted.

  Thereafter, the planarizing film 16 is formed so as to cover the in-layer lens 9, and the color filter 17, the planarizing film 18, and the on-chip lens 19 are sequentially formed to manufacture the CCD solid-state imaging device shown in FIG. can do.

According to the above-described embodiment, after the lens shape of the resist 21 is transferred to the plasma CVD film 8 by dry etching, the plasma CVD film 22 of the same type as the plasma CVD film 8 is formed to form the inner lens 9. By doing so, the gap between the in-layer lenses 9 can be narrowed.
In addition, since the gap between the inner lenses that have been ineffective areas for incident light can be reduced, the ineffective area can be reduced and the light collection efficiency of incident light can be increased.
Therefore, the solid-state imaging device 1 with high sensitivity can be manufactured.

Furthermore, the gap length between the inner lenses 9 can be arbitrarily adjusted by arbitrarily changing the film thickness of the plasma CVD film 22.
Therefore, the sensitivity can be improved with respect to the solid-state imaging device 1 having unit cells of various dimensions.

Incidentally, a resist is usually used as an on-chip lens material such as the on-chip lens 19 in FIG. 3, and after applying the resist and patterning, it is reflowed into a lens shape.
Therefore, if the manufacturing method of the present invention is applied to an on-chip lens made of a normal resist, it is difficult to apply the resist thinner, and it is difficult to arbitrarily control the gap of the on-chip lens.

On the other hand, for example, if the on-chip lens is formed of an inorganic film, the same kind of inorganic film can be easily formed on the lens-shaped inorganic film.
That is, after transferring the lens shape from a resist to an inorganic film such as a plasma CVD film, the same kind of inorganic film such as a plasma CVD film can be formed thereon to narrow the gap of the on-chip lens.
As a result, the inorganic film can be formed with an arbitrary film thickness, and the gap of the on-chip lens can be controlled arbitrarily.

  In the CCD solid-state imaging device 1 shown in FIG. 3, the on-chip lens 19 can be formed of an inorganic film such as a plasma CVD film. In this case, the method of forming an intralayer lens according to the manufacturing method of the present invention is used. In addition, it can be applied to the on-chip lens 19 to increase the sensitivity by narrowing the gap between the two lenses.

In the above-described embodiment, the present invention is applied to the CCD solid-state imaging device. However, the present invention can be similarly applied to solid-state imaging devices having other configurations, for example, MOS type solid-state imaging devices.
Then, by applying the present invention, the gap of the intralayer lens can be narrowed and a solid-state imaging device with high sensitivity can be manufactured.

In addition, the in-layer lens according to the manufacturing method of the present invention can be applied to a liquid crystal display element in addition to a solid-state imaging element.
Then, for example, an intra-layer lens according to the manufacturing method of the present invention is formed on the incident side of external light in a reflective liquid crystal display element and on a light source side such as a backlight in a transmissive liquid crystal display element.
As a result, the light blocked by the black matrix (light-shielding film) between the pixels of the color filter of the liquid crystal display element can be effectively used by passing through the liquid crystal part.

  The present invention is not limited to the above-described embodiment, and various other configurations can be taken without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 1 CCD solid-state image sensor, 2 sensor part, 3 light shielding film, 4 semiconductor substrate, 5 oxide film, 6 interlayer insulation film, 7, 16, 18 planarization film, 8,22 plasma CVD film, 9 inner lens, 10 vertical Transfer register, 11 transfer electrode, 15 CCD transfer channel, 17 color filter, 19 on-chip lens, 21 resist

Claims (8)

A method of manufacturing a solid-state imaging device having a lens having a convex surface on each sensor part,
Forming a lens material film on the planarizing film by a plasma CVD film;
Forming a lens-shaped resist having a convex surface on the surface of the lens material;
Transferring the lens shape having a convex surface on the resist side to the film of the lens material so that a gap between the convex lenses is widened ;
And a step of forming the same lens material film on the film of the lens material to which the lens shape has been transferred by a plasma CVD film to form the lens . The method for manufacturing a solid-state imaging element according to claim 1, wherein an SiN film or an SiON film is formed in the step of forming the lens material film by a plasma CVD film . The method for manufacturing a solid-state imaging device according to claim 1, wherein the planarizing film is a reflow film or a high-density plasma CVD film. The method for manufacturing a solid-state imaging device according to claim 1, further comprising a step of forming a planarizing film so as to cover the lens. The manufacturing method of the solid-state image sensor of Claim 4 which further has the process of forming a color filter on the said planarization film | membrane. The manufacturing method of the solid-state image sensor of Claim 5 which further has the process of forming an on-chip lens on the said color filter. Each sensor unit has a lens whose front side is convex,
The above-mentioned lens is a solid-state imaging device in which a film of the same lens material is formed by a plasma CVD film on a lens-shaped lens material film having a convex surface on the surface side by a plasma CVD film. The solid-state imaging device according to claim 7, wherein the lens-shaped film of the lens material having a convex surface on the front side is a SiN film or a SiON film.

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