JP6926706B2 - Manufacturing method of solid-state image sensor - Google Patents

Description

The present invention relates to a method for manufacturing a solid-state image sensor, a solid-state image sensor, and an image pickup device.

In recent years, it has been desired to reduce the size, cost, and performance of color measuring devices. Color measuring equipment is used, for example, in the production and inspection of products, for the purpose of accurately measuring minute differences in color of products that cannot be discerned by the naked eye, and for other purposes, in which consumers perform color measurement according to their purpose. It is used for various purposes.

As a color measuring device, it is known to use a color filter (called a color separation element) for selecting a transmission wavelength. For example, a multilayer interference filter made by laminating a multilayer film of an inorganic dielectric material is known. A multi-layer interference filter is a type of structural color filter that can freely control the selected wavelength band and full width at half maximum of the spectrum by adjusting the optical constants and physical film thickness of the multilayer film, and has a degree of design freedom. It is known to be expensive. Further, a structural color filter using waveguide mode resonance and surface plasmon resonance is also known.

For example, Patent Document 1 describes a color separation filter for a dye-dispersed photosensitive material provided on a solid-state image sensor, in which the spectral characteristics of the filter corresponding to each pixel are combined by additive color mixing. It is disclosed that the region is divided into a plurality of regions, and each of the divided portions is provided with a coloring element having different spectral characteristics.

By the way, in a general digital still camera or the like, three-color (R, G, B) spectroscopy using a color resist composed of an organic polymer is often used. Since it is extremely difficult to freely control the absorption wavelength band of the polymer constituting this color resist at the molecular synthesis stage, it is difficult to obtain a desired transmission wavelength band with high accuracy.

On the other hand, for example, in the multilayer film interference filter, since the dielectric material is deposited by vapor deposition, sputtering, or the like, the same film configuration must be formed on the entire single plate glass. Therefore, at the time of photographing, the multilayer film filter glass having a different film configuration is switched on the solid-state image sensor for image pickup, and it is not possible to perform one-shot imaging or continuous imaging of moving images and the like. In addition, the camera module also requires a control mechanism for switching the filter glass, and it has not been possible to reduce the size at high cost.

On the other hand, for example, a multilayer film interference filter is formed by directly forming a multilayer film on a solid-state image sensor, such as a Bayer array or a line array, for each light receiving pixel as in the mounting form of an organic color resist. Furthermore, by changing the film thickness of the cavity layer for each region of the light receiving pixels using semiconductor micromachining such as dry etching, the multilayer film interference filter and the light receiving pixels are coupled one-to-one, and the multilayer film interference at the sensor wafer level. It is considered to be a color filter.

However, there is a problem that the difference between the design film thickness and the actual film thickness of the filter occurs within the same pixel region due to the variation in the manufacturing of the color separation element, and the peak wavelength position shift of the transmission spectrum occurs. ..

Therefore, an object of the present invention is to provide a method for manufacturing a solid-state image sensor equipped with a high-quality color-separating element that realizes a transmission spectrum close to a design target value.

In order to achieve such an object, the method for manufacturing a solid-state image sensor according to the present invention comprises a solid-state image sensor including a light receiving region that receives incident light and a filter that selectively transmits a specific wavelength of the incident light. In the manufacturing method, the filter is a structural color color filter utilizing multilayer film interference, waveguide mode resonance, or surface plasmon resonance, and the filter is directly deposited on the solid-state image sensor to receive one light source. The region is divided into a plurality of divided filters for transmitting the incident light received by the one light receiving region , and repeated etching processing is performed under processing conditions in which the cavity layers of the plurality of divided filters have the same film thickness. By doing so, a plurality of regions in which the peak wavelength positions of the transmission spectra are dispersed are provided in the one light receiving region, and the plurality of division filters are provided so that the spectrum obtained by synthesizing the transmission spectra of the plurality of division filters has a predetermined value. you made is also of the.

According to the present invention, it is possible to provide a solid-state image sensor provided with a high-quality color separation element that realizes a transmission spectrum close to a design target value.

It is explanatory drawing of the color filter arrangement on the solid-state image sensor, and is an example of (a) line arrangement, (b) Bayer arrangement. It is sectional drawing which shows an example of the solid-state image sensor which mounted the color filter. This is an example of a schematic diagram of a solid-state image sensor in a Bayer array on which a color filter is mounted. It is explanatory drawing which shows an example of the transmission spectrum of a color filter. It is explanatory drawing which shows an example of the manufacturing method of a color filter. It is explanatory drawing which shows another example of the manufacturing method of a color filter. It is explanatory drawing which shows the manufacturing variation of the film thickness of the cavity layer at the measurement point in the wafer plane. It is explanatory drawing of the pixel area division of the color filter of a line arrangement. It is explanatory drawing of the pixel area division of the color filter of a Bayer array. It is a perspective explanatory view (1) which shows an example of the manufacturing method of the color filter shown in FIG. 8 (b). It is a perspective explanatory view (2) which shows an example of the manufacturing method of the color filter shown in FIG. 8 (b). It is explanatory drawing which shows the relationship between the measurement point in the wafer plane and the peak position shift amount at the time of executing the pixel area division of 3 divisions. It is a graph which shows the transmission spectrum and the composite spectrum thereof at each in-wafer measurement point. An example of an external view of a digital camera according to an embodiment of an imaging device, (a) is a top view, (b) is a front view, and (c) is a back view. This is an example of a functional block diagram of an imaging device.

Hereinafter, the configuration according to the present invention will be described in detail based on the embodiments shown in FIGS. 1 to 15.

The method for manufacturing a solid-state image sensor according to the present embodiment includes a light receiving region (light receiving pixel 202) that receives incident light and a filter (color filter 205) that selectively transmits a specific wavelength of the incident light. A method for manufacturing a solid-state image sensor (solid-state image sensor 200), in which a filter is formed from a plurality of divided filters (for example, regions 205H to 205K shown in FIG. 8) for transmitting incident light received by one light receiving region. Therefore, it includes a filter manufacturing step of manufacturing a plurality of split filters so that the spectrum obtained by synthesizing the transmission spectra of the plurality of split filters has a predetermined value.

(Color filter array)
First, an arrangement example of a color filter, which is a color separation element, will be described. The color filter is arranged on the pixels of the solid-state image sensor, and examples of the arrangement method include a line arrangement and a Bayer arrangement. FIG. 1A shows an example of a line arrangement of color filters, and FIG. 1B shows an example of a Bayer arrangement.

In the line-arranged color filter 205, as shown in FIG. 1A, for example, a region 205A in which the same filter is arranged in a row on the pixel 202 and a color filter having different color separation characteristics from the region 205A are arranged. Region 205B and region 205C are formed. An array that has the same spectral function in the same direction and is used by scanning incident light is called a line array, and a color filter of the line array is mainly used for line scanner applications.

Further, as shown in FIG. 1B, in the Bayer array color filter 205, for example, regions 205D, 205E, 205F, 205G in which one filter is combined and arranged for each pixel 202 are formed. This combination is arranged periodically. This enables one-shot imaging in which information can be obtained with a single exposure to incident light. The Bayer array color filter is mainly used in applications such as digital still cameras and video cameras, in which an image of an object is obtained by forming a lens image.

The color filter array can take various forms depending on the application, and the color filter array is not limited to the above example.

(Color filter structure)
Next, the structure of the color filter will be described. The color filter 205 is a wafer-level multilayer film interference type filter having characteristics different from those of a color resist composed of an organic polymer. That is, while the organic color resist selects the transmission wavelength of the incident light by the absorption band of the organic polymer, this color filter 205 uses multiple interference of light due to the multilayer film structure of the dielectric material which is an inorganic material. The transmission wavelength of the incident light is selected. In other words, it is a filter that selectively separates and transmits specific wavelengths of incident light.

FIG. 2 is a cross-sectional view showing an example of the solid-state image sensor 200 on which the color filter 205 is mounted. The solid-state image sensor 200 includes a semiconductor substrate 201, light-receiving pixels 202 (202r, 202g, 202b), an insulating film 203, a light-shielding film 204, a color filter 205, and a moisture-proof layer 206.

In the color filter 205, low refractive index dielectric materials (205b, 205d) of _{silicon oxide (SiO 2} ) and high refractive index dielectric materials (205a, 205c, 205e) of _{titanium oxide (TiO 2) are alternately laminated.} 205a, 205b, 205d, 205e are mirror layers, and 205c is a cavity layer.

Here, when n is the refractive index of the dielectric material, d is the physical film thickness of the dielectric material, and λ is the reference wavelength of the transmission wavelength band, the mirror layers 205a, 205b, 205d, 205e have the optical film thickness nd = It has λ / 4.

Further, by changing the film thickness of the cavity layer 205c, the multiple interference optical path can be changed to change the peak wavelength position of the transmitted light. That is, by changing the film thickness of the cavity layer 205c on each light receiving pixel, transmitted light having a different peak wavelength can be incident on each light receiving pixel. For example, by changing the film thickness of the cavity layer 205c of the color filter 205 located above the three light receiving elements 202r, 202g, 202b by etching or the like for each light receiving region, the three light receiving elements 202r, 202g, 202b can be formed. It is possible to receive the transmitted light of three colors of R, G, and B, respectively.

With such a color filter structure, it is possible to provide regions having different spectral characteristics for each light receiving pixel as in the case of using an organic color resist while using a multilayer film structure.

_{Although an example in which silicon oxide (SiO 2} ) is used as the low refractive index dielectric material and _{titanium oxide (TiO 2} ) is used as the high refractive index dielectric material has been described, the present invention is not limited to this, and the low refractive index is not limited to this. As the dielectric material, for example, magnesium fluoride (MgF ₂ ), thiolite (Na ₅ Al ₃ F ₁₄ ), cryolite (Na _{3 Al F 6} ) and the like can be used. Examples of the high refractive index dielectric material include tantalum oxide (Ta ₂ O ₅ ), zirconium oxide (ZrO ₂ ), niobium oxide (Nb ₂ O ₅ ), hafnium oxide (HfO ₂ ), and zinc sulfide (ZnS). , Lantan titanate (LaTIO ₃ ), cerium oxide (CeO ₂ ) and the like can be used. Moreover, any of the above-mentioned mixed materials and the like can also be used.

FIG. 3 is an example of a schematic diagram of a solid-state image sensor 200 having a Bayer array on which the color filter 205 is mounted. For example, when the color filters have three colors R, G, and B, the color filter 205 having different film thickness regions of the cavity layer is mounted in a one-to-one combination with respect to the light receiving pixel surface 202A. Since the color filter 205 is directly deposited on the solid-state image sensor 200 and mounted by the lithography process and the etching process, the mounting dimensional error with the light receiving element 202 is determined by the alignment accuracy of the etching mask in the lithography process.

(Transmission spectrum of color filter)
FIG. 4 is an explanatory diagram showing an example of the transmission spectrum of the color filter 205. Each transmission spectrum includes the transmission spectrum R of the color filter mounted on the light receiving element 202r shown in FIG. 2, the transmission spectrum G of the color filter mounted on the light receiving element 202g, and the transmission of the color filter mounted on the light receiving element 202r. It represents spectrum B.

When the color filter 205 has a five-layer structure and the reference wavelength is λ445 nm, the low refractive index material L is silicon oxide (SiO ₂ ), the λ / 4 film thickness of the mirror layer is 76.72 nm, and the high refractive index material H is titanium oxide. As (TiO ₂ ), the λ / 4 film thickness of the mirror layer was set to 50.08 nm. The peak wavelength positions of the transmission spectrum are R = 595 nm, G = 555 nm, and B = 445 nm, respectively. In this way, by changing only the film thickness of the cavity layer 205c of the color filter 205, it is possible to generate transmission spectra of completely different transmission wavelength bands even with the same film configuration.

It should be noted that the film configuration, film thickness, dielectric material, number of color separations, transmission spectrum, etc. described so far are examples, and are not limited to the above and illustrated examples.

(Manufacturing method of color filter)
Next, a method of manufacturing a color filter will be described. FIG. 5 is an explanatory diagram showing an example of a method for manufacturing the color filter 205. First, as shown in FIG. 5A, a light receiving pixel 202 (202r, 202g, 202b), an insulating film 203, and a light shielding film 204 are formed on the semiconductor substrate 201. The method for forming each layer other than the color filter 205 may be a known or new method, and the film structure, film thickness, etc. are not limited, and thus the description thereof will be omitted.

Next, as shown in FIG. 5B, a titanium oxide layer (mirror layer 205a), a silicon oxide layer (mirror layer 205b), and a titanium oxide layer (cavity layer 205c) are produced by forming a film on the insulating film 203. .. At this time, the film thickness of the cavity layer 205c formed on the entire wafer is set to the film thickness of the cavity layer 205c formed in the upper region of the light receiving element 202r. As the film forming method, any of a chemical vapor deposition method such as thermal CVD and PECVD, a physical vapor deposition method such as vapor deposition and sputtering, and an atomic layer deposition method may be used.

Next, as shown in FIG. 5C, the photoresist 210 is applied onto the cavity layer 205c and exposed using a mask in which only the upper region of the light receiving element 202b is open, and the upper region of the light receiving element 202b is exposed. Photoresist 210 is removed.

Further, the cavity layer 205c is etched to a desired film thickness to remove the entire photoresist 210. As a result, the cavity layer region 205c-1 corresponding to the region above the light receiving element 202b is formed. As the etching method, either dry etching such as reactive ion etching or wet etching may be used.

Next, as shown in FIG. 5D, the cavity layer 205c is etched to a desired film thickness only in the upper region of the light receiving element 202g, as in the previous step. As a result, the cavity layer region 205c-2 corresponding to the region above the light receiving element 202g is formed.

Here, as shown in FIG. 5E, the cavity layer region 205c-3 corresponding to the light receiving element 202r uses the film thickness when the cavity layer 205c is formed as it is. Since this film thickness does not vary in size due to etching, the cavity layer region 205c-3 corresponding to the light receiving element 202r can be manufactured with high accuracy while omitting the number of etching steps.

Next, as shown in FIG. 5 (f), a silicon oxide layer (mirror layer 205d) and a titanium oxide layer (mirror layer 205e) are formed.

Then, as shown in FIG. 5 (g), the wafer level multilayer film interference type color filter 205 is completed by forming the moisture-proof layer 206.

FIG. 6 is an explanatory diagram showing another example (list-off method) of the method for manufacturing the color filter 205. The description of the same points as in the above example of the manufacturing method (FIG. 5) will be omitted as appropriate.

First, as shown in FIG. 6A, a light receiving pixel 202 (202r, 202g, 202b), an insulating film 203, and a light shielding film 204 are formed on the semiconductor substrate 201. The method for forming each layer other than the color filter 205 may be a known or new method, and the film structure, film thickness, etc. are not limited, and thus the description thereof will be omitted.

Next, as shown in FIG. 6B, a titanium oxide layer (mirror layer 205a), a silicon oxide layer (mirror layer 205b), and a titanium oxide layer (cavity layer 205c) are produced by forming a film on the insulating film 203. .. At this time, the film thickness of the cavity layer 205c formed on the entire wafer is set to the film thickness of the cavity layer 205c formed in the upper region of the light receiving element 202b.

Next, as shown in FIG. 6C, the photoresist 211 is applied onto the cavity layer 205c and exposed using a mask in which only the region other than the upper portion of the light receiving element 202b is open, except for the upper portion of the light receiving element 202b. The photoresist 211 in the region is removed.

Further, a titanium oxide layer is additionally formed so that the total film thickness of the cavity layer 205c of the entire wafer becomes the film thickness of the cavity layer 205c formed in the upper region of the light receiving element 202g, and the lift-off method is performed. The titanium oxide layer is removed only in the upper region of the light receiving element 202b.

As a result, as shown in FIG. 6D, a cavity layer region 205c-1 corresponding to the upper region of the light receiving element 202b and a cavity layer region 205c-2 corresponding to the upper region of the light receiving element 202g are formed. NS.

Next, as shown in FIG. 6 (e), the photoresist 211 is formed to form a film and lifted off in the same manner as in the previous step, so that the light receiving element 202r is shown in FIG. 6 (f). A cavity layer region 205c-3 is formed corresponding to the region above. In this way, by using the lift-off method, it is possible to form a color filter corresponding to each light receiving region while maintaining the film formation accuracy.

Next, as shown in FIG. 6 (g), a silicon oxide layer (mirror layer 205d) and a titanium oxide layer (mirror layer 205e) are formed.

Then, as shown in FIG. 6H, the wafer level multilayer film interference type color filter 205 is completed by forming the moisture-proof layer 206.

(Variation in color filter manufacturing)
Next, the manufacturing variation of the color filter 205 will be described. In the method for manufacturing the color filter 205 shown in FIGS. 5 and 6, dimensional variation in film thickness may occur in the film forming step and the etching step of the cavity layer.

In particular, in the case of dry etching processing, position-dependent variation within the wafer surface becomes a problem. FIG. 7A shows variations in dry etching production of the film thickness of the cavity layer 205c at the in-plane measurement points (measurement points A to E). The measurement point is a measurement position in the wafer surface as shown in FIG. 7 (b).

The peak position shift amount [Δλ / nm] shown in FIG. 7A indicates how much the peak wavelength position of the transmission spectrum deviates from the design median value. Here, the median design value is G = 555 nm (Fig. 4).

Here, as a result of dry-etching different wafers three times under the same conditions, as shown in FIG. 7A, variations in the film thickness of the cavity layer 205c having a diameter of −8 to 6 nm occurred at each measurement point. Here, the peak wavelength position of the transmission spectrum shifts by about 1 nm due to the variation in the film thickness of the 1 nm cavity layer 205c, which makes the shift amount unacceptable depending on the application. Further, it is practically difficult to eliminate the variation in the wafer on the order of nanometers with the current dry etching apparatus.

(Pixel area division)
As described with reference to FIG. 7, in the film forming process and the etching process of the cavity layer, manufacturing variation of the color filter 205 occurs as a film thickness error. Therefore, the peak wavelength position of the transmission spectrum of the color filter 205 in the wafer surface varies with respect to the desired design target value.

Therefore, in the method for manufacturing a color filter according to the present embodiment, a region within one pixel is divided into a plurality of regions, and the cavity layers in each region are repeatedly etched under processing conditions having the same film thickness. That is, a plurality of regions in which the peak wavelength positions of the transmission spectrum are dispersed are intentionally provided in one pixel (this is called pixel region division).

As a result, the transmission spectrum in one pixel composed of a plurality of regions becomes a composite spectrum of the transmission spectrum of each region in one pixel, and the peak wavelength position variation is averaged. Therefore, the variation is suppressed, and the peak wavelength position can be stabilized with respect to the design target value in the wafer surface and between the wafer surfaces.

Here, as the processing conditions for etching the cavity layer to have the same film thickness, numerical values such as gas flow rate, pressure, lower electrode temperature, antenna power, bias power, processing time, etc. are set to the same values in the etching apparatus. Refers to a condition. As the gas, _{a mixed gas of sulfur hexafluoride SF 6} , chlorine Cl ₂ , or argon Ar is used, the lower electrode temperature is 25 ° C. or lower, the pressure is 1 Pa or lower, the antenna power is 100 to 500 W, and the bias power is 100. Perform at ~ 500W.

FIG. 8 is an explanatory diagram of pixel area division of the color filter 205 of the line arrangement. In the case where the color filters 205 have the same pixel arrangement in the horizontal direction, FIG. 8A shows the regions 205H, 205I, 205J, 205K divided into four, and FIG. 8B shows the regions 205H, 205I, 205J 3. Division, FIG. 8C shows an example in which regions 205H and 205I are divided into two.

FIG. 9 is an explanatory diagram of pixel region division of the Bayer array color filter 205. In the case where the color filters 205 have different pixel arrangements, FIG. 9A shows four divisions of regions 205L, 205M, 205N, 205O, and FIG. 9B shows three divisions of regions 205L, 205M, 205N. 9 (c) shows an example in which the regions 205L and 205M are divided into two.

A method for manufacturing a color filter according to the present embodiment will be described with reference to FIGS. 10 and 11. In the present embodiment, the color filter 205 of the line arrangement in which the pixel area shown in FIG. 9B is divided into three will be described as an example, but the number of divisions of the pixel area is an example, and FIGS. 8 and 9 ( The same manufacturing method can be applied to each of the color filters 205 shown in a) and (c).

10 and 11 are perspective explanatory views of a method for manufacturing a color filter according to the present embodiment. It should be noted that FIGS. 10 and 11 show a state in which each part of the color filter is transmitted. Further, the description of the same points as the above-mentioned manufacturing method (FIG. 5) will be omitted as appropriate.

First, as shown in FIG. 10A, a light receiving pixel 202 (202r, 202g, 202b), an insulating film 203, and a light shielding film 204 are formed on the semiconductor substrate 201.

Next, as shown in FIG. 10B, a titanium oxide layer (mirror layer 205a), a silicon oxide layer (mirror layer 205b), and a titanium oxide layer (cavity layer 205c) are produced by forming a film on the insulating film 203. .. At this time, the film thickness of the cavity layer 205c formed on the entire wafer is set to the film thickness of the cavity layer 205c formed in the upper region of the light receiving element 202r.

The regions 205L, 205M, and 205N shown in FIGS. 10 (c) and later indicate the regions of the color filter 205 that are divided into three pixel regions.

Next, as shown in FIGS. 10 (c), 10 (d), and (e), the upper regions 205 L ₁ , M ₁ , and N ₁ of the light receiving element 202 b are etched. First, as shown in FIG. 10C, a photoresist 210 is applied onto the cavity layer 205c, _{exposed using a mask in which only the region 205L 1} corresponding to the upper region 205L of the light receiving element 202b is open, and the light is received. The photoresist 210 in the upper region 205L _{1 of the element 202b is removed. Further, the cavity layer 205c in the upper region 205L 1} of the light receiving element 202b is etched to a desired film thickness, and after the etching is performed, all the photoresist 210 on the cavity layer 205c is removed.

Next, as shown in FIG. 10D, the etching process of the _{region 205M 1} corresponding to the region 205M above the light receiving element 202b is performed. The etching process is the same as the process described in FIG. 10 (c).

Further, as shown in FIG. 10 (e), the etching process of the _{region 205N 1 corresponding to the region 205N above the light receiving element 202b is performed.} The etching process is the same as the process described in FIG. 10 (c). By performing the processes shown in FIGS. 10 (c), 10 (d), and 10 (e), the cavity layer region can be formed only in the upper region 205 of the light receiving element 202b.

Next, as shown in FIGS. 11 (a), 11 (b), and 11 (c), the upper regions 205 L ₂ , M ₂ , and N ₂ of the light receiving element 202 g are etched. First, as shown in FIG. 11A, the photoresist 210 is applied onto the cavity layer 205c, _{exposed using a mask in which only the region 205L 2} corresponding to the upper region 205L of the light receiving element 202g is open, and the light is received. The photoresist 210 in the upper region 205L _{2 of the element 202g is removed. Further, the cavity layer 205c of the region 205L 2} above the light receiving element 202g is etched to a desired film thickness, and after the etching is performed, all the photoresist 210 on the cavity layer 205c is removed.

Next, as shown in FIG. 11B, the etching process of the _{region 205M 2} corresponding to the upper region 205M of the light receiving element 202g is performed. The etching process is the same as the process described in FIG. 11 (a).

Further, as shown in FIG. 11C, the etching process of the _{region 205N 2} corresponding to the region 205N above the light receiving element 202g is performed. The etching process is the same as the process described in FIG. 11 (a). By performing the processes shown in FIGS. 11A, 11B, and 11C, the cavity layer region can be formed only in the upper region 205 of the light receiving element 202g.

In the present embodiment, the film thickness of the cavity layer 205c is set to the film thickness of the cavity layer 205c formed in the upper region of the light receiving element 202r. Since there is no dimensional variation in the cavity layer region due to etching only in the upper region 205 of the light receiving element 202r, the film thickness when the cavity layer 205c is formed is used as it is. Of course, it may be formed by using the forming method for the upper region of.

Next, as shown in FIG. 11D, a silicon oxide layer (mirror layer 205d) and a titanium oxide layer (mirror layer 205e) are formed.

Then, as shown in FIG. 11E, the wafer level multilayer film interference type color filter 205 is completed by forming the moisture-proof layer 206.

In the pixel region division in the color filter manufacturing method described so far, it can be said that the larger the number of divisions, the closer the variation can be to 0, which is ideal. On the other hand, since the number of steps increases, the number of divisions increases. Is preferably 4 or less, and is preferably determined in consideration of the actual value of dimensional variation.

Further, the division method for dividing the pixel area described so far is an example, and the division method is not limited to this. For example, various modifications such as dividing the pixel diagonally are possible.

Here, the result of dry etching the different wafers shown in FIG. 7 three times under the same conditions is regarded as a case where the etching is repeated in three divisions as shown in FIGS. 8 (b) and 9 (b). , It was verified to what extent the average of the three times can suppress the peak position shift amount.

FIG. 12 is an explanatory diagram showing the relationship between the in-wafer in-plane measurement points (measurement points A to E) and the peak position shift amount when the pixel region division of the three divisions is executed. According to FIG. 12, a large effect was obtained especially when the variation in the peak position shift amount was large as in the measurement point C and the measurement point E, and the average variation could be kept within ± 3 nm. .. As a result, the effectiveness of the present invention can be confirmed, and it can be said that it is particularly effective in controlling the peak wavelength position variation when a sharp transmission spectrum is desired to be obtained.

13 (a) to 13 (e) are graphs showing the three actually measured transmission spectra at the in-wafer measurement points A to E and their composite spectra. In FIG. 13, the actual transmission spectrum is shown by a dotted line, and the composite spectrum thereof is shown by a solid line.

Further, FIG. 13 (f) shows a graph comparing the composite spectra of the in-plane measurement points A to E of each wafer. In particular, even when the three measured spectra are widely dispersed as in the measurement points C and E, the shape of the composite spectrum is maintained, and the effectiveness of the present invention can be confirmed.

As described above, for example, when a sensor wafer level multilayer film interference color filter is manufactured with a bandpass filter configuration, the design film thickness of the filter is within the same pixel region due to manufacturing variations in the film forming process and the dry etching process. And the actual film thickness will be different, and the peak wavelength position shift of the transmission spectrum will occur.

In particular, since the cavity layer etching process requires dry etching accuracy on the order of several nanometers, if unevenness in the wafer surface or variation between wafer surfaces occurs, the transmission spectrum for each different wafer, chip, or light receiving pixel. There was a problem that the peak position changed.

On the other hand, according to the solid-state image sensor manufacturing method and the solid-state image sensor according to the present embodiment described above, the influence of the peak wavelength position variation of the transmission spectrum is suppressed, and the transmission spectrum close to the design target value is realized. It is possible to obtain a solid-state image sensor equipped with a high-quality color separation element.

That is, the peak wavelength position of the transmission spectrum of the color filter varies due to manufacturing variations in the film forming process, the etching process of the cavity layer, and the like. On the other hand, one pixel is intentionally divided into a plurality of regions and etched with the same parameters so as to obtain a desired film thickness. As a result, by averaging the manufacturing variations, a transmission spectrum close to the design target value can be realized, and a high-quality color filter can be obtained.

More specifically, for example, the peak wavelength position of the transmission spectrum in the wafer-level multilayer film interference type filter varies from + to around the design median due to manufacturing variations during the film forming process and the dry etching process. On the other hand, by dividing the region within one pixel into a plurality of regions and repeatedly etching the cavity layer of each region under the same conditions, a plurality of regions in which the peak wavelength position of the transmission spectrum is intentionally dispersed in one pixel can be obtained. prepare. At this time, the transmission spectrum of each pixel becomes a composite spectrum of color filters in a plurality of regions. As a result, the peak wavelength position variation of each pixel becomes close to 0 on average, and it is possible to realize a transmission spectrum close to the design target value.

As described above, according to the present embodiment, unlike the organic color resist, it is possible to cancel the manufacturing variation of the structural color color filter having the processing variation at the time of manufacturing and to realize the transmission spectrum close to the design target value.

Further, in the present embodiment, a structural color color filter utilizing multi-layer film interference has been described as an example. This is because structural color color filters that utilize multilayer film interference have manufacturing variations depending on the film formation process and etching process. Therefore, by having the above steps that cancel out the manufacturing variations, transmission close to the design target value is achieved. This is because the spectrum can be realized.

Here, the structural color filter using waveguide mode resonance and the structural color color filter using surface plasmon resonance are also subjected to the film forming process and the dry etching process in the same manner as the structural color color filter using multilayer film interference. Since there are variations in production depending on the color, it is also preferable to apply the production method according to the present embodiment to the production method.

In addition, by arranging the color filters in a line array, the variation in the characteristics of the color filters arranged in the same line is averaged, and by averaging the variation in the characteristics of the light receiving pixels arranged in the same line, the variation in the characteristics of the light receiving pixels arranged in the same line is averaged. Various variation factors are removed, and as a result, a high-purity output value can be obtained.

Further, by arranging the color filters by Bayer, one-shot shooting becomes possible, but the variation in the color filter characteristics on each pixel means that color unevenness occurs in the output image. By eliminating variations in color filter characteristics, it is possible to suppress color unevenness.

(Imaging device)
It is preferable to use an image pickup device having the solid-state image pickup device according to the present embodiment described above. By using the solid-state image pickup device described above in the image pickup device, it is possible to configure an image pickup device capable of improving color reproducibility.

In the present embodiment, a digital camera will be described as an example of the image pickup apparatus. 14A and 14B show an external view of a digital camera, FIG. 14A shows a top view of the camera, FIG. 14B shows a front view of the camera, and FIG. 14C shows a back view of the camera.

As shown in FIG. 14A, the digital camera has a sub LCD 1, a release shutter 2 (SW1), and a mode dial 4 (SW2) on the upper surface.

Further, as shown in FIG. 14B, the digital camera has a strobe light emitting unit 3, a distance measuring unit 5, a remote control light receiving unit 6, a lens unit 7, and an optical finder (front) 11 in front of the digital camera. Have. Further, the memory card throttle 23 indicates a throttle into which a memory card 34 such as an SD card is inserted, and is provided on the side surface of the camera.

Further, as shown in FIG. 14 (c), the digital camera has an AFLED (autofocus LED) 8, a strobe LED 9, an LCD monitor (display means) 10, an optical viewfinder (back surface) 11, and a zoom on the back surface. It has a button (zoom lever) TELE 12 (SW4), a power switch 13 (SW13), a zoom button (zoom lever) WIDE14 (SW3), and a self-timer / delete switch 15 (SW6).

Further, the menu switch 16 (SW5), the OK switch 17 (SW12), the left / image confirmation switch 18 (SW11), the lower / macro switch 19 (SW10), the upper / strobe switch 20 (SW7), and the right. It has a switch 21 (SW8) and a display switch 22 (SW9) for displaying an image.

FIG. 15 shows a functional block diagram of the control system of the digital camera shown in FIG. The system configuration inside the digital camera will be described below.

As shown in FIG. 15, in this digital camera, the electricity output from the CCD 121 and the CCD 121 as solid-state image sensors in which the subject image incident through the photographing lens system installed in the lens unit 7 is imaged on the light receiving surface. Front-end IC (F / E) 120 that processes signals (analog RGB image signals) into digital signals, signal processing IC 110 that processes digital signals output from front-end IC (F / E) 120, and data temporarily An analog (storage means) 33 for storing, a ROM (storage means) 30 for storing control programs and the like, a motor driver 32 and the like are provided.

The lens unit 7 includes a zoom lens, a focus lens, a mechanical shutter, and the like, and is driven by a motor driver 32. The motor driver 32 is controlled by a microcomputer (CPU, control unit) 111 included inside the signal processing IC 110.

The CCD 121 is a solid-state image sensor for photoelectrically converting an optical image, and a color filter (RGB primary color filter) as a color separation element is arranged on a plurality of pixels constituting the CCD, and corresponds to RGB3 primary colors. An electric signal (analog RGB image signal) is output.

The front-end IC (F / E) 120 is a CDS 122 that performs sampling hold (correlation double sampling) for a CCD output electric signal (analog image data), and an AGC (Auto Gain Control) 123 that adjusts the gain of the sampled data. , A / D converter (A / D) 124 that performs digital signal conversion, and CCDI / F112 supply vertical synchronization signal (VD) and horizontal synchronization signal (HD), and drive timing signals between CCD121 and F / E120. It has a TG (timing generator: control signal generator) 125 to be generated.

The oscillator (clock generator) supplies the system clock of the signal processing IC 110 including the CPU 111 and the clock to the TG 125 and the like. The TG 125 receives the clock of the oscillator and supplies the pixel clock for pixel synchronization to the CCDI / F112 in the signal processing IC 110.

The digital signal input from the F / E 120 to the signal processing IC 110 is temporarily stored in the SDRAM 33 as RGB data (RAWRGB) by the memory controller 115 via the CCDI / F112.

The signal processing IC 110 includes a CPU 111 that controls the system, a CCDI / F 112, a resizing processing unit 113, a memory controller 115, a display output control unit 116, a compression / decompression unit 117, a media I / F unit 118, a YUV conversion unit 119, and the like. ing.

The CCDI / F112 outputs a vertical synchronization signal (VD) and a horizontal synchronization signal (HD), captures a digital (RGB) signal input from the A / D 124 in accordance with the synchronization signal, and transmits the digital (RGB) signal via the memory controller 115. RGB data is written to the SDRAM 33.

The display output control unit 116 sends the display data written in the SDRAM 33 to the display unit, and displays the captured image. The display output control unit 116 can display on the LCD monitor 10 built in the digital camera, or can output as a TV video signal and display it on an external device.

The display data referred to here is YCbCr of a natural image and OSD (on-screen display) data for displaying a shooting mode icon, etc., both of which are read and displayed by the memory controller 115 on the SDRAM 33. It is sent to the output control unit 116, and the data synthesized by the display output control unit 116 is output as video data.

The compression / decompression unit 117 compresses the YCbCr data written in the SDRAM 33 during recording and outputs JPEG-encoded data, and decompresses the read JPEG-encoded data into YCbCr data during reproduction and outputs the data.

The media I / F unit 118 reads the data in the memory card 34 to the SDRAM 33 or writes the data on the SDRAM 33 to the memory card 34 according to the instruction of the CPU 111.

Based on the image development processing parameters set from the CPU 111, the YUV conversion unit 119 converts the RGB data temporarily stored in the SDRAM 33 into brightness Y and color difference CbCr data (YUV data), and writes the RGB data back to the SDRAM 33.

The resizing unit 113 reads out the YUV data and performs size conversion to a size necessary for recording, size conversion to a thumbnail image, size conversion to a size suitable for display, and the like.

Further, the CPU 111, which is a control unit that controls the entire operation, loads a control program and control data for controlling the camera stored in the ROM 30 at startup into, for example, the SDRAM 33, and performs the entire operation based on the program code. Control.

The CPU 111 controls the imaging operation and sets the image development processing parameters according to an instruction by a button key or the like of the operation unit 31, an external operation instruction such as a remote controller (not shown), or a communication operation instruction by communication from an external terminal such as a personal computer. Performs memory control, display control, etc.

The operation unit 31 is for the photographer to give an operation instruction of the digital camera, and a predetermined operation instruction signal is input to the control unit by the operation of the photographer. For example, as shown in FIG. 14, it is provided with various button keys such as a two-step (half-pressed and fully-pressed) release shutter 2 for instructing shooting, and zoom buttons 12 and 14 for setting optical zoom and electronic zoom magnification.

When the operation unit 31 detects that the power key of the digital camera has been turned on, the CPU 111 sets a predetermined setting for each block. With this setting, the image received by the CCD 121 via the lens unit 7 is converted into a digital video signal and input to the signal processing IC 110.

The digital signal input to the signal processing IC 110 is input to the CCDI / F112. In the CCDI / F112, the photoelectrically converted analog signal is subjected to processing such as black level adjustment and temporarily stored in the SDRAM 33. The RAW-RGB image data stored in the SDRAM 33 is read out by the YUV conversion unit 119, subjected to gamma conversion processing, white balance processing, edge enhancement processing, and YUV conversion processing, and written back to the SDRAM 33 as YUV image data. ..

The YUV image data is read out by the display output control unit 116. For example, if the output destination is a TV of an NTSC system, the resizing processing unit 113 performs horizontal and vertical scaling processing according to the system, and the TV is subjected to horizontal and vertical scaling processing. It is output. By performing this process for each VD, monitoring, which is a display for confirmation before still photography, is performed.

Although the above-described embodiment is a preferred example of the present invention, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

200 Solid-state image sensor 201 Semiconductor substrate 202 Light-receiving pixel 203 Insulating film 204 Light-shielding film 205 Color filter 206 Moisture-proof layer 210, 211 photoresist

Japanese Unexamined Patent Publication No. 2-188703

Claims (4)

The light receiving area that receives the incident light and
A method for manufacturing a solid-state image sensor including a filter that selectively transmits a specific wavelength of incident light.
The filter is a structural color color filter utilizing multilayer film interference, waveguide mode resonance, or surface plasmon resonance.
The filter is directly deposited on the solid-state image sensor, and the film is formed.
One light receiving area is divided into a plurality of dividing filters for transmitting the incident light received by the one light receiving area .
By repeatedly etching the cavity layers of the plurality of divided filters under the processing conditions of having the same film thickness, a plurality of regions in which the peak wavelength position of the transmission spectrum is dispersed are provided in the one light receiving region.
Method for producing a plurality of transmission spectrum of the synthesized spectrum is solid-state image pickup device you produce the plurality of dividing filter such that a predetermined value of the dividing filter. The method for manufacturing a solid-state image sensor according to claim 1, wherein the filter comprises a divided filter divided by the number of divided regions of 4 or less in the one light receiving region. The method for manufacturing a solid-state image sensor according to claim 1 or 2 , wherein the etching process is dry etching. The processing condition according to any one of claims 1 to 3, wherein the processing condition is a condition selected from gas flow rate, pressure, lower electrode temperature, antenna power, bias power, and processing time in the etching apparatus. Method for manufacturing a solid-state image sensor.

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