JP2009168872A - Lens manufacturing method and solid-state imaging device manufacturing method - Google Patents

Abstract

It is possible to form irregularities of a desired size on a lens surface by a method having a small number of manufacturing steps.
A step of forming a lens forming layer on a substrate, a step of forming an organic film including metal particles on the surface of the lens forming layer, and an organic film including the metal particles are formed on the organic film. The step of forming the first lens mold 15, the first lens mold 15 and the organic film 13 are etched, and the surface shape of the first lens mold 15 is transferred by the organic film 13 including the metal particles 14. Forming the second lens mold 16 having irregularities on the surface, and etching the second lens mold 16 and the lens forming layer 12 so that the surface shape of the second lens mold 15 is formed by the lens forming layer 12. And a step of forming a lens 17 having irregularities on the transferred surface.
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a lens having nanostructure irregularities on a lens surface and a method for manufacturing a solid-state imaging device.

Along with the high integration of semiconductor devices, there is a demand for miniaturization of lenses of solid-state imaging devices.
However, a simple downsizing of the lens, that is, a reduction in the condensing area reduces the sensitivity of the solid-state imaging device. Therefore, there is a strong demand for a lens processing technique that can realize both downsizing and an improvement in sensitivity. ing.

  In the solid-state imaging device, the microlens is formed in a convex dome shape above the light receiving portion formed for each pixel, and plays a role of refracting light and condensing it on the light receiving portion.

As shown in FIG. 6A, the current microlens portion is formed by forming a lens forming film 112 on a substrate 111, further forming a resist pattern 113 on the lens forming layer 112, and performing a reflow process to form a resist pattern. 113 is transformed into a convex shape.
Next, the lens forming film 112 is etched back together with the resist pattern 113 by dry etching.

As a result, as shown in FIG. 6 (2), the resist pattern 113 (see FIG. 6 (1)) is removed by etching, the surface shape of the resist pattern 113 is transferred to the lens forming layer 112, and a convex lens. A shaped microlens 114 is formed.
The above lens forming method is generally used frequently.

However, in the above lens shape, incident light is reflected by several percent. In order to reduce this, a structure in which irregularities are formed on the surface of the microlens has been proposed (for example, see Patent Document 1).
The irregularities on the surface of the microlens are formed by performing plasma treatment or wet etching treatment.

However, it is difficult to obtain desired large irregularities by the method of performing plasma treatment or wet etching treatment.
In addition, high ion energy dry etching conditions can form large irregularities, but in this case, plasma damage on the lens surface becomes significant, causing side effects such as surface turbidity and surface hardening. It will be.

Therefore, a method for improving the light collection efficiency of the lens while avoiding the process of roughening the lens surface has been proposed.
For example, a method has been proposed in which the light collection efficiency is improved by stacking a fluorine-based acrylic resin layer (antireflection film) having a refractive index different from that of the lens on the lens (see, for example, Patent Document 2).
Moreover, by embedding a light-absorbing resin (antireflection film) between the lens gaps, the scattered light of the light incident between the lenses and the oblique light incident on the bottom of the lens with poor light collection efficiency are reduced. A technique for improving the light collection efficiency is disclosed (for example, see Patent Document 3).

However, there is a limit in the technology for improving the light collection efficiency using these antireflection films.
Smoothing the gradient of the refractive index between the air and the lens suppresses the reflected light and further improves the light collection efficiency. In the case of using an antireflection film, it is necessary to stack antireflection films having different refractive indexes in multiple layers on the lens in order to further improve the light collection efficiency.
This method has a limit to device miniaturization.
In addition, there is a problem in the manufacturing aspect that the number of manufacturing steps increases as the light collection efficiency increases.

Japanese Patent Laid-Open No. 2006-1000076 JP 2007-53153 A JP 2002-33466 A

  The problem to be solved is that, in order to obtain an antireflection effect, it is difficult to obtain the desired large unevenness by the method of forming the unevenness by performing plasma treatment or wet etching treatment on the lens surface. In order to avoid this problem, the method of forming an antireflection film on the lens surface requires the formation of antireflection films with different refractive indexes in multiple layers, which increases the number of manufacturing processes. It is a point to do.

  The present invention makes it possible to form irregularities of a desired size on the lens surface by a method with a small number of manufacturing steps.

  The method for manufacturing a lens of the present invention includes a step of forming a lens forming layer on a substrate, a step of forming an organic film containing metal particles on the surface of the lens forming layer, and a lens mold on the organic film containing the metal particles. Etching the lens mold, the organic film containing the metal particles, and the lens forming layer to form a lens having irregularities on the surface onto which the surface shape of the lens mold is transferred by the lens forming layer. And a step of performing.

In the method for producing a lens of the present invention, an organic film containing metal particles is formed on the surface of a lens forming layer formed on a substrate, and a lens mold is formed on the organic film containing the metal particles. The organic film containing metal particles and the lens forming layer are etched. In this etching process, first, the organic film containing metal particles is etched together with the lens mold. Then, the surface shape of the lens mold is transferred to the organic film containing the metal particles, and the metal particles in the organic film containing the metal particles serve as an etching mask. In the delayed state, the organic part in the organic film containing the metal particles is etched. As a result, the lens-shaped surface shape is transferred to the organic film containing the metal particles, and the metal particles serve as an etching mask, whereby irregularities are formed on the surface. This uneven shape can be controlled by, for example, the distribution density and size of the metal particles.
Then, the etching is advanced to etch the lens forming layer, and the surface shape of the lens mold is transferred by the lens forming layer, so that a lens having irregularities on the surface is formed.
Therefore, the size and distribution density of the irregularities formed on the lens surface can be intentionally controlled by appropriately changing the size, material, and distribution density of the metal particles.
As the etching proceeds, the metal particles are also etched. For example, even if the metal particles are etched and disappeared during the progress of the etching of the organic film containing the metal particles, at that time, the uneven shape due to the metal particles remains on the etching surface of the organic film containing the metal particles, The shape is transferred to the lens forming layer.
Also, if metal particles on the lens surface remain when the lens is formed, the remaining metal particles can be selectively removed, so there is a problem even if metal particles remain when the lens is formed. It will not be.

  The method of manufacturing a solid-state imaging device according to the present invention includes a light-receiving unit that photoelectrically converts incident light, and a solid-state imaging device that forms a lens that collects incident light on the light-receiving unit on the incident light side of the light-receiving unit. In the manufacturing method, the lens forming step includes a step of forming a lens forming layer on a substrate on which the light receiving portion is formed, a step of forming an organic film containing metal particles on the surface of the lens forming layer, and the metal Forming a lens mold on the organic film containing particles, etching the lens mold, the organic film containing the metal particles, and the lens forming layer, and transferring the surface shape of the lens mold to the lens forming layer. Forming a lens having irregularities on the surface.

In the method for manufacturing a solid-state imaging device of the present invention, since the method for manufacturing a lens of the present invention is applied, as described above, irregularities are formed on the lens surface by a simple method.
The size and distribution density of the irregularities can be intentionally controlled by appropriately changing the size, material, and distribution density of the metal particles.

  Since the lens manufacturing method of the present invention can form desired irregularities on the lens surface with a simple method with good controllability, the light collection efficiency of the lens can be increased. Moreover, since unevenness | corrugation can be formed in the lens surface by a simple method, manufacturing cost can be reduced. Therefore, an increase in the number of manufacturing processes can be suppressed in response to a request for high light collection efficiency, and it can be applied to devices of different generations.

  The manufacturing method of the solid-state imaging device of the present invention can form desired irregularities on the lens surface by a simple method with good controllability, so that the condensing efficiency of the lens can be increased and the light receiving sensitivity can be improved. Can do. Moreover, since unevenness | corrugation can be formed in the lens surface by a simple method, manufacturing cost can be reduced. Therefore, an increase in the number of manufacturing steps can be suppressed in response to a request for high light collection efficiency, and it can be applied to solid-state imaging devices of different generations.

  An embodiment (example) according to the method for manufacturing a lens of the present invention will be described with reference to the manufacturing process sectional view schematically shown in FIG. 1 and the enlarged sectional view schematically shown in FIG.

As shown in FIG. 1A, a lens forming layer 12 for forming a lens is formed on a substrate 11. The lens forming layer 12 is formed of, for example, a lens organic film. For example, polystyrene, an acrylic transparent resin, a novolac transparent resin, or the like can be used for the lens organic film.
Next, an organic film 13 containing metal particles is formed on the lens forming layer 12.

  The organic portion 14 of the organic film 13 containing the metal particles is formed of a material having higher plasma resistance during etching than the lens forming layer 12. For example, the organic portion 14 may be a natural resin or a synthetic resin, for example, or may be a modified natural substance, chlorinated rubber, viscose, or the like.

For example, copper (Cu) particles are used as the metal particles 15 of the organic film 13 containing the metal particles.
The content of the copper particles is, for example, 1% to 10%, for example, 3%.
The material of the metal particles 15 may be other particles such as nickel (Ni), molybdenum (Mo), aluminum (Al), titanium (Ti), chromium (Cr), gold (Au), Its content is 1% or more and 10% or less. When the content of the metal particles 15 is less than 1%, there are too few irregularities formed on the surface of a lens to be formed later, and the effect of preventing surface reflection cannot be sufficiently obtained. On the other hand, if the content of the metal particles 15 exceeds 10%, the amount of the metal particles 15 is so large that the surface shape of a lens to be formed later cannot be transferred sufficiently.
Further, the average particle size of the metal particles 15 is set to 0.05 μm or more and 0.12 μm or less. When the average particle diameter of the metal particles 15 is smaller than 0.05 μm, the unevenness formed on the surface of the lens to be formed later becomes too small or the unevenness is not sufficiently formed. On the other hand, when the average particle diameter of the metal particles 15 is larger than 0.12 μm, the unevenness of the lens surface to be formed later becomes too large, and a sufficient antireflection effect cannot be obtained.
Further, as a basic material of the metal particles, an isoindoline, azo, or quinophthalone organic pigment may be used.

Next, the lens mold 16 is formed on the organic film 13 containing the metal particles. For example, the lens mold 16 is formed of a photoresist. The lens mold 16 is preferably formed of a material that is etched at the same time when the organic portion 14 of the organic film 13 containing the metal particles is etched.
The size (diameter) of the lens mold 16 is, for example, 2 μm. This size is equivalent to the size of the lens to be formed, and is, for example, several hundred nm to several tens μm. Of course, it is possible to fabricate a film having a size smaller than several hundreds nm or larger than several tens of μm. A specific method for forming the lens mold 16 will be described in detail later.

  Next, as shown in FIG. 1B, first, the lens mold 16 (see FIG. 1A) and the organic film 13 containing the metal particles are etched. In this etching, the lens mold 16 and the organic portion 14 of the organic film 13 containing the metal particles are simultaneously etched, and the surface shape of the lens mold 16 is transferred to the organic film 13 containing the metal particles. . Then, the organic film 13 containing the metal particles is formed in a convex lens shape. At this time, since the metal particles 15 serve as an etching mask, irregularities are formed on the surface of the organic film 13 containing the metal particles. Eventually, the lens mold 16 disappears by etching. Moreover, a part of the lens forming layer 12 starts to be etched.

  When the etching rate of the organic component 14 of the organic film 13 containing the metal particles is equal to the etching rate of the metal particles 15, the organic component 14 and the metal particles 15 are simultaneously etched as shown in FIG. As a result, irregularities are not formed on the etched surface. Under such conditions, a lens having irregularities on the surface cannot be formed.

  Therefore, in the lens manufacturing method of the present invention, as shown in FIG. 2 (2), the etching conditions are set so that the etching rate of the organic component 14 is faster than the etching rate of the metal particles 15. In this case, since the organic component 14 is etched and the metal particles 15 are difficult to be etched, the metal particles 15 serve as an etching mask, and irregularities are formed on the etched surface.

  Further, the etching is advanced. As a result, as shown in FIG. 1 (3), the lens forming layer 12 is formed with a lens 17 having irregularities on the surface, onto which the surface shape of the lens mold 16 (see FIG. 1 (1)) is transferred. Is done.

The etching is performed by dry etching, for example.
As an example of the dry etching processing conditions, an ICP (Inductively Coupled Plasma) RIE (Reactive Ion Etching) apparatus is used, the pressure of the etching atmosphere is set to 6.7 Pa, the source power is set to 600 W, and the bias power is set to 100 W. As an etching gas, oxygen (O ₂ ) (supply flow rate = 20 cm ³ / min) and chlorine (Cl ₂ ) (supply flow rate = 50 cm ³ / min) are used.
A gas containing a halogen element such as carbon tetrafluoride (CF ₄ ) may be used instead of chlorine (Cl ₂ ).

As a result, it is possible to obtain the lens 17 having fine irregularities with a diameter of about 3 nm to 10 nm and a depth of about 5 nm to 30 nm formed on the surface.
This minute unevenness is caused by a reaction in dry etching between the metal particles 15 in the organic film 13 containing metal particles and the organic portion 15 in the organic film 13 containing metal particles and the lens forming layer 12 during the dry etching. Since the property (for example, vapor pressure) is different, the etching rate is different between a portion where the metal particles 15 are present and a portion where the metal particles 15 are absent.

The aspect ratio of the irregularities formed on the surface of the lens 17 can be controlled by the type of the metal particles 15.
For example, by using larger atoms such as titanium (Ti), the diameter of the convex portion in the horizontal direction can be increased. On the other hand, if a dry etching reactive material such as aluminum (Al) is used, the convex portion can be made shallow.

In order to control these, the content of the metal particles 15 may be changed.
By increasing the content of the metal particles 15, a convex shape with a lower aspect can be formed. In addition, since the difference in reactivity is used, the aspect ratio of the unevenness can be controlled even if the etching gas or conditions are changed.

For example, a high molecular weight organic material containing 5% of aluminum (Al) particles as the metal particles 15 is applied on the lens forming film 12 made of resin or the like to form the organic film 13 containing metal particles. Further, a resist is applied on the organic film 13 containing metal particles. As this resist material, for example, a positive resist for KrF exposure is used. The pattern of the lens mold 16 is formed by irradiating light in the ultraviolet region with a KrF exposure machine.
Thereafter, dry etching is performed using, for example, an ICP type RIE apparatus, the etching min pressure is set to 6.7 Pa, the source power is set to 600 W, the bias power is set to 100 W, and the etching gas is oxygen (O ₂ ) (supply flow rate = Etching is performed using 20 cm ³ / min) and chlorine (Cl ₂ ) (supply flow rate = 50 cm ³ / min).

Here, in order to deeply form the irregularities on the surface of the final lens 17, it is effective to increase the etching rate difference between the metal particles 15 of the organic film 13 containing metal particles and the organic portion 14 as etching conditions. is there. For this purpose, for example, the flow rate of oxygen (O ₂ ) in the etching gas is increased.
Oxygen radicals have strong chemical reactivity with the organic film, and the amount of oxygen radicals is proportional to the oxygen (O ₂ ) flow rate, so that the irregularities formed on the surface of the lens 17 can be easily controlled.
By increasing the flow rate of oxygen (O ₂ ), the etching rate of the organic portion 14 increases with high sensitivity, while the etching rate of aluminum (Al) that is the metal particles 15 does not change. And the etching rate difference becomes large. As a result, the unevenness on the surface of the lens 17 can be deepened.

Alternatively, the unevenness can be deepened by lowering the ion energy.
In general, the binding energy of metal is larger than that of organic material, and metal is harder than organic material. Therefore, if ion energy is lowered, the etching selectivity to metal is improved. That is, since the etching rate difference of the organic portion 14 becomes large, the unevenness can be deepened.
Incidentally, the bond energy is 72 eV for Al—Al bond, 3.6 eV for C—C bond, and 4.3 eV for C—H bond.

Specific measures for lowering the ion energy can be achieved by lowering the bias power or lowering the pressure in the etching atmosphere.
When the component of the metal particles 15 to be contained is changed from aluminum (Al) to titanium (Ti), titanium has a lower vapor pressure than aluminum (for example, aluminum trichloride (AlCl ₃ having a vapor pressure of 1 mmHg). ) Is 100 ° C., and the temperature of titanium trichloride (TiCl ₃ ) is −25 ° C.), the etching rate can be increased. Thereby, the difference in etch rate between the metal particles 15 and the organic portion 14 can be controlled. As described above, the unevenness depth on the surface of the lens 17 can be controlled depending on the type of the metal particles 15 and the etching conditions.

  Further, as described above, the etching for forming the lens 17 from the etching of the lens mold 16 can be performed by continuously etching the lens mold 16, the organic film 13 containing metal particles, and the lens forming layer 12. Alternatively, after the surface shape of the lens mold 16 is transferred to the organic film 13 containing the metal particles, the etching is temporarily stopped, and the metal particles including the surface shape of the lens mold 16 are transferred under different etching conditions. The lens 17 can also be formed by etching the organic film 13 and the lens forming film 12.

  In the lens manufacturing method, the organic film 13 containing metal particles is formed on the surface of the lens forming layer 12 formed on the substrate 11, and the lens mold 16 is formed on the organic film 13 containing the metal particles. The lens mold 16, the organic film 13 containing metal particles, and the lens forming layer 12 are etched. In this etching process, first, the organic film 13 containing metal particles is etched together with the lens mold 16. Then, the surface shape of the lens mold is transferred to the organic film 13 containing metal particles, and the metal particles 15 in the organic film 13 containing metal particles serve as an etching mask. In a state where the etching of the particles is delayed, the organic portion 15 of the organic film 13 including the metal particles is etched. As a result, the surface shape of the lens mold 16 is transferred to the organic film 13 containing metal particles, and the metal particles 15 become etching masks, thereby forming irregularities on the surface. This uneven shape can be controlled by, for example, the distribution density and size of the metal particles 15.

Then, the etching is advanced to etch the lens forming layer 12, and the surface shape of the lens mold 16 is transferred by the lens forming layer 12, and the lens 17 having irregularities on the surface is formed.
Therefore, the size and distribution density of the irregularities formed on the surface of the lens 17 can be intentionally controlled by appropriately changing the size, material, and distribution density of the metal particles 15.

The metal particles 15 are also etched with the progress of etching. For example, even if the metal particles 15 are etched and disappeared during the etching of the organic film 13 containing metal particles, the uneven shape of the metal particles 15 is left on the etched surface of the organic film 13 containing metal particles. Therefore, the shape is transferred to the lens forming layer 12.
Further, when the metal particles 15 on the surface of the lens 17 remain when the lens 17 is formed, the remaining metal particles 15 may be selectively removed, so that the metal particles 15 are formed when the lens 17 is formed. It doesn't matter if it remains.

  As described above, according to the lens manufacturing method of the present invention, desired concavities and convexities can be formed on the surface of the lens 17 by a simple method with good controllability, so that the light collection efficiency of the lens 17 can be increased. . Moreover, since the unevenness | corrugation can be formed in the lens 17 surface by a simple method, manufacturing cost can be reduced. Therefore, an increase in the number of manufacturing processes can be suppressed in response to a request for high light collection efficiency, and it can be applied to devices of different generations.

  In the said Example, the organic film containing a metal particle is used as a lens formation layer, and the lens formation layer demonstrated in the said Example is not formed. This manufacturing method will be described below with reference to the manufacturing process diagram of FIG.

  As shown in FIG. 3 (1), an organic film 33 containing metal particles to be a lens forming layer for forming a lens is formed on a substrate 31.

  For the organic portion 34 of the organic film 33 containing the metal particles, for example, a natural resin or a synthetic resin can be used, and a modified natural substance, chlorinated rubber, viscose, or the like may be used.

For example, copper (Cu) particles are used as the metal particles 35 of the organic film 33 containing the metal particles.
The content of the copper particles is, for example, 1% to 10%, for example, 3%.
The material of the metal particles 35 may be other particles such as nickel (Ni), molybdenum (Mo), aluminum (Al), titanium (Ti), chromium (Cr), gold (Au), Its content is 1% or more and 10% or less. If the content of the metal particles 35 is less than 1%, the unevenness of the lens surface to be formed later is too small, and the effect of preventing surface reflection cannot be sufficiently obtained. On the other hand, when the content of the metal particles 35 exceeds 10%, there are too many metal particles 35, the light transmittance is deteriorated, and the lens cannot be used.
The average particle size of the metal particles 35 is set to 0.05 μm or more and 0.12 μm or less. When the average particle diameter of the metal particles 35 is smaller than 0.05 μm, the unevenness of the surface of the lens to be formed later becomes too small, and the effect of preventing the reflection on the lens surface cannot be obtained sufficiently. On the other hand, if the average particle size of the metal particles 35 is larger than 0.12 μm, the unevenness of the lens surface to be formed later becomes too large, and a sufficient antireflection effect cannot be obtained.

  Next, a lens mold 36 is formed on the organic film 33 containing the metal particles. For example, the lens mold 35 is formed of a photoresist. The size (diameter) of this lens mold is, for example, 2 μm. This size is equivalent to the size of the lens to be formed, and is, for example, several hundred nm to several tens μm. Of course, it is possible to fabricate a film having a size smaller than several hundreds nm or larger than several tens of μm.

  Next, as shown in FIG. 3B, the lens mold 36 (see FIG. 3A) and the organic portion 34 of the organic film 33 containing the metal particles are etched to contain the metal particles. A lens 37 having irregularities on the surface is formed by transferring the surface shape of the lens mold 36 with the organic film 33.

The etching is performed by dry etching, for example. The dry etching is performed using an ICP (Inductively Coupled Plasma) type RIE (Reactive Ion Etching) apparatus, an etching min pressure of 6.7 Pa, a source power of 600 W, a bias power of 100 W, and an etching gas. Oxygen (O ₂ ) (supply flow rate = 20 cm ³ / min) and chlorine (Cl ₂ ) (supply flow rate = 50 cm ³ / min) are used.
A gas containing a halogen element such as carbon tetrafluoride (CF ₄ ) may be used instead of chlorine (Cl ₂ ).

  As a result, minute irregularities having a diameter of 3 nm to 10 nm and a depth of about 5 nm to 30 nm are formed on the surface of the lens 37.

The aspect ratio of the irregularities formed on the surface of the lens 37 can be controlled by the type of the metal particles 35 as described above.
For example, by using larger atoms such as titanium (Ti), the diameter of the convex portion in the horizontal direction can be increased. On the other hand, if a dry etching reactive material such as aluminum (Al) is used, the convex portion can be made shallow.
Moreover, in order to control these, you may change content of the metal particle 35. FIG. By increasing the content of the metal particles 35, a convex shape with a lower aspect can be formed. In addition, since the difference in reactivity is used, the aspect ratio of the unevenness can be controlled even if the etching gas or conditions are changed.

  Further, as described above, the unevenness formed on the surface of the lens 37 can be deepened by lowering the ion energy.

In the lens manufacturing method described with reference to FIG. 3, since the metal particles 35 remain inside the lens 37, the light transmittance is reduced, but reflection on the lens surface can be prevented.
Further, the size and distribution density of the irregularities on the surface of the lens 37 can be intentionally controlled by appropriately changing the size, material, and distribution density of the metal particles 35.

  Next, the manufacturing method of the solid-state imaging device of the present invention will be described below. The manufacturing method of the solid-state imaging device of the present invention is characterized in that the manufacturing method of each lens of the present invention is applied to a manufacturing method of a condensing lens that collects incident light on a light receiving portion of the solid-state imaging device.

  One example of this will be described with reference to the schematic sectional views of FIGS.

The solid-state imaging device shown in FIG. 4 is an example of a CCD solid-state imaging device, and the solid-state imaging device shown in FIG. 4 is an example of a CMOS-type solid-state imaging device.
That is, the manufacturing method of the solid-state imaging device of the present invention can be applied to any solid-state imaging device as long as it is a manufacturing method of a lens that collects incident light on the light receiving portion of the solid-state imaging device.

  As shown in FIG. 4, the solid-state imaging device 5 is configured as follows.

  A p-type well region 61 is formed in a semiconductor substrate 51 (for example, an N-type silicon substrate), and a light receiving portion 52 is formed in the p-type well region 61. On one side of the light receiving portion 52, a read gate portion 53, a vertical charge transfer portion 55, a channel stop region 54 are formed, and an adjacent light receiving portion 52 is further formed. A channel stop region 54 is also formed on the other side.

  The light receiving portion 52 is composed of an n-type impurity region 71 and a p-type hole accumulation region 73 formed thereon.

  The vertical charge transfer section 55 includes a p-type well region 81 having a higher concentration than the p-type well region 61 and an n-type channel region 82 formed thereon. A transfer electrode 84 is formed on the n-type channel region 82 via a gate insulating film 83. The electrode 84 also serves as a read gate electrode together with the vertical transfer electrode.

  Further, an interlayer insulating film 91 is formed so as to cover the electrode 84, and a light shielding film 92 is further formed. The light shielding film 92 is formed of a metal film such as tungsten or aluminum. An opening 93 is formed on the light receiving portion 52 in the light shielding film 92. Further, it is covered with a passivation film 94 and a planarizing film 95, and a color filter layer 96 is formed on the planarizing film 95. A condensing lens 97 is provided on the color filter layer 96 so that incident light is efficiently collected on the light receiving unit 52.

  When forming the condensing lens 97, the manufacturing method of each lens of the present invention can be applied.

  Next, FIG. 5 shows a full aperture CMOS image sensor as an example to which the solid-state imaging device of the present invention is applied.

  As shown in FIG. 5, an active layer 112 formed of a semiconductor substrate 111 includes a photoelectric conversion unit (for example, a photodiode) 122 that converts incident light into an electric signal, a transistor group such as a transfer transistor, an amplification transistor, and a reset transistor. A plurality of pixel portions 121 having 123 (a part of which is shown in the drawing) and the like are formed. For example, a silicon substrate is used as the semiconductor substrate 111. Further, a signal processing unit (not shown) for processing the signal charge read from each photoelectric conversion unit 122 is formed.

  An element isolation region 124 is formed between part of the periphery of the pixel portion 121, for example, between the pixel portions 121 in the row direction or the column direction.

  A wiring layer 131 is formed on the surface side of the semiconductor substrate 111 on which the photoelectric conversion unit 122 is formed (the lower side of the semiconductor substrate 111 in the drawing). The wiring layer 131 includes a wiring 132 and an insulating film 133 that covers the wiring 132. A support substrate 135 is formed on the wiring layer 131. The support substrate 135 is made of, for example, a silicon substrate.

  Further, in the solid-state imaging device 6, a planarizing film 141 having optical transparency is formed on the back side of the semiconductor substrate 111. Further, an organic color filter layer 142 is formed on the planarizing film 141 (on the upper surface side in the drawing). A condensing lens 151 that condenses incident light on each photoelectric conversion unit 122 is formed on the organic color filter layer 142.

  When forming the condensing lens 151, the manufacturing method of each lens of the present invention can be applied.

  FIG. 5 shows a so-called back-illuminated CMOS solid-state imaging device. However, in the method for manufacturing a solid-state imaging device according to the present invention, so-called front-illumination in which incident light is taken into the photoelectric conversion unit from the wiring layer side. The present invention can also be applied to a method for manufacturing a CMOS type solid-state imaging device.

Therefore, as described above, the condensing lens 97 (see FIG. 4) and the condensing lens 151 (see FIG. 5) having irregularities formed on the surface can be formed by a simple method.
The size and distribution density of the irregularities can be intentionally controlled by appropriately changing the size, material, and distribution density of the nanostructure.
As described above, since desired irregularities can be formed on the lens surface with good controllability, the light collection efficiency of the lens can be increased, and the light receiving sensitivity of the solid-state imaging device can be improved. Moreover, since unevenness | corrugation can be formed in the lens surface by a simple method, manufacturing cost can be reduced.
Therefore, an increase in the number of manufacturing steps can be suppressed in response to a request for high light collection efficiency, and it can be applied to solid-state imaging devices of different generations.

  Further, the manufacturing method of the lens of the present invention is not limited to the manufacturing method of the lens of the solid-state imaging device, but also a manufacturing method of a condensing lens provided in a device that collects incident light on a light receiving unit such as an optical sensor. Can be applied.

It is manufacturing process sectional drawing which showed typically one Embodiment (Example) which concerns on the manufacturing method of the lens of this invention. It is the expanded sectional view which showed typically the one part process of the manufacturing method of the lens of an Example. It is manufacturing process sectional drawing which showed typically the modification of the manufacturing method of the lens of an Example. It is manufacturing process sectional drawing which showed typically one Embodiment (1st Example) which concerns on the manufacturing method of the solid-state imaging device of this invention. It is manufacturing process sectional drawing which showed typically one Embodiment (2nd Example) which concerns on the manufacturing method of the solid-state imaging device of this invention. It is manufacturing process sectional drawing which showed the manufacturing method of the conventional lens typically.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Base | substrate, 12 ... Lens formation layer, 13 ... Organic film | membrane which has metal particle, 14 ... Metal particle, 15 ... 1st lens type | mold, 16 ... 2nd lens type | mold, 17 ... Lens

Claims (5)

Forming a lens forming layer on the substrate;
Forming an organic film containing metal particles on the surface of the lens forming layer;
Forming a lens mold on the organic film containing the metal particles;
Etching the lens mold, the organic film containing the metal particles, and the lens forming layer to form a lens having irregularities on the surface onto which the surface shape of the lens mold is transferred by the lens forming layer. A method for producing a lens characterized by the above. The method for manufacturing a lens according to claim 1, wherein the metal particles serve as an etching mask when forming the lens. The etching is plasma etching;
The lens manufacturing method according to claim 1, wherein the metal particles have higher plasma resistance during etching than the organic film. In a method for manufacturing a solid-state imaging device, which includes a light receiving unit that photoelectrically converts incident light, and a lens that collects incident light on the light receiving unit on the incident light side of the light receiving unit.
The lens forming step includes:
Forming a lens forming layer on the substrate on which the light receiving portion is formed;
Forming an organic film containing metal particles on the surface of the lens forming layer;
Forming a lens mold on the organic film containing the metal particles;
Etching the lens mold, the organic film containing the metal particles, and the lens forming layer to form a lens having irregularities on the surface onto which the surface shape of the lens mold is transferred by the lens forming layer. A method for manufacturing a solid-state imaging device. A color filter layer is formed on the uppermost layer of the substrate;
The method for manufacturing a solid-state imaging device according to claim 4, wherein the lens forming layer is formed on the color filter layer.

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