CN-122002932-A - Image sensor with improved color accuracy

Abstract

The present disclosure relates to an image sensor with improved color accuracy. An imaging device comprising a plurality of optical sensors disposed on an integrated circuit and a plurality of sets of interference filters, wherein one set of interference filters of the plurality of sets of interference filters comprises a plurality of interference filters comprising an array, wherein each interference filter is configured to allow light of a different wavelength range to pass. The invention also includes a plurality of sets of absorption filters, wherein one set of absorption filters in the plurality of sets of absorption filters includes a plurality of absorption filters forming an array, each absorption filter being associated with one or more interference filters to form an absorption filter and interference filter pair. Each absorption filter and interference filter pair is associated with one or more optical sensors configured to allow light having a narrower wavelength range to pass than the individual absorption filters.

Inventors

• J. Bolemans

Assignees

• 光谱公司

Dates

Publication Date

20260508

Application Date

20211008

Priority Date

20210913

Claims (10)

1. 1. An image forming apparatus comprising: a plurality of optical sensors disposed on one integrated circuit; A plurality of sets of interference filters, wherein one set of interference filters of the plurality of sets of interference filters comprises a plurality of interference filters forming an array, wherein each interference filter is configured to allow light of a different wavelength range to pass through, and A plurality of sets of absorption filters, wherein a set of the plurality of sets of absorption filters comprises a plurality of absorption filters comprising an array, wherein each absorption filter is associated with one or more interference filters, forming an absorption filter and interference filter pair, wherein each absorption filter and interference filter pair is configured to allow light having a narrower wavelength range than an individual absorption filter to pass, wherein each absorption filter and interference filter is associated with one or more of the plurality of optical sensors.
2. 2. The imaging device of claim 1, wherein the plurality of sets of interference filters are separated from the plurality of optical sensors by an etch stop layer.
3. 3. The imaging device of claim 1, wherein the plurality of sets of interference filters are further separated from the plurality of optical sensors by an air gap or substantially transparent material.
4. 4. The imaging device of claim 3, wherein the substantially transparent material comprises one or more organic materials.
5. 5. An imaging device according to claim 3, wherein the transparent material is optimized to limit reflection and/or may comprise an alloy gradient or layer stack.
6. 6. The imaging device of claim 1, wherein each interference filter is selected from a group of filters comprising a short pass filter, a long pass filter, a bandpass filter, or a bandstop filter, wherein each interference filter is configured to allow light of at least one of the ultraviolet spectral range, the visible spectral range, the near infrared spectral range, and the infrared spectral range to pass.
7. 7. The imaging device of claim 1, wherein one or more of the plurality of sets of interference filters comprises a fabry-perot filter.
8. 8. The imaging device of claim 1, wherein at least some of the plurality of sets of absorption filters are configured to block light in the infrared wavelength range.
9. 9. The imaging device of claim 1, wherein some of the at least multiple sets of absorption filters comprise at least one organic filter or plasma filter.
10. 10. The imaging device of claim 1, wherein the plurality of sets of absorption filters are separated from the plurality of interference filters by an etch stop layer.

Description

Image sensor with improved color accuracy The application is a divisional application of Chinese application patent application with the application date of 2021, 10-month 08, the application number of 202111170589.6 and the name of 'image sensor with improved color precision'. Technical Field The present invention relates generally to imaging, and more particularly to digital imaging with improved color accuracy. Background Most digital image sensors use color filters placed on a grid of photosensors to enable replication of various colors. For example, red Green Blue (RGB) color sensors use filters superimposed on the three main "channels" of red, green and blue to represent the complete spectrum. The filters employed in RGB color sensors typically comprise organic "absorbing" filters, possibly with poor filtering characteristics. Filters with better filtering characteristics (e.g., interference filters) may be used, but the interference filters are more complex to produce and can produce ghost images by adversely reflecting light outside the filter pass. Furthermore, while providing more channels by incorporating additional filters to improve color accuracy, adding too many additional channels may reduce the resolution of the image sensor. Disclosure of Invention In one embodiment, an imaging device is provided that includes a plurality of optical sensors disposed on an integrated circuit, a plurality of sets of interference filters, wherein a set of interference filters of the plurality of sets of interference filters includes a plurality of interference filters that form an array, wherein each interference filter is configured to allow light of a different wavelength range to pass, and a plurality of sets of absorption filters, wherein a set of absorption filters of the plurality of sets of absorption filters includes a plurality of absorption filters that form an array, wherein each absorption filter is associated with one or more interference filters, forming an absorption filter and interference filter pair, wherein each absorption filter and interference filter pair is configured to allow light of a narrower wavelength range than an individual absorption filter, wherein each absorption filter and interference filter is associated with one or more optical sensors of the plurality of optical sensors. Drawings FIG. 1A shows an example of passband response of an interference filter; FIG. 1B shows an example of the reflectivity response of an interference filter; FIG. 2A provides a side view of an image sensor system, showing the characteristic reflectivity of an interference filter; FIG. 2B shows an example of the response of a long pass filter; FIG. 3A provides an example of passband response of an RGB absorption filter; FIG. 3B provides a top view of an RGGB filter mosaic array that meets the requirements of the present invention; FIG. 4A provides a characteristic passband response of selected short-pass and long-pass interference filters overlaid on a selected absorption filter response in accordance with the requirements of the present invention; FIG. 4B provides a combined passband response of selected short-pass and long-pass interference filters and matching RGB absorption filters that meet the requirements of the present invention; FIG. 5 provides a top view of an example of a6 channel color filter array consistent with the requirements of the invention; FIG. 6 provides a side view of an image sensor having an absorptive filter overlaying an interference filter in accordance with the requirements of the present invention; FIG. 7 provides a side view of an image sensor with microlenses covering the absorptive and interference filters in accordance with the requirements of the present invention; Fig. 8 provides a characteristic passband response of the multi-band interference filter overlaid on each absorption filter of the RGB filter configuration. FIG. 9 provides an example of spectral results of the combined passband response of a characteristic RGB absorber filter and interference filter pair consistent with the requirements of the present invention; FIG. 10 provides a side view of an image sensor having an absorptive filter overlaying an interference filter in accordance with the requirements of the present invention; FIG. 11 is a flow chart illustrating an example of a sensor manufacturing method consistent with the requirements of the present invention. Detailed Description In various embodiments, the digital image sensor combines an absorbing color filter with an interference filter to expand the available color channels to provide additional color channels. In other embodiments, an absorbing color filter is combined with an interference filter to provide additional channels for Ultraviolet (UV), near Infrared (NIR) and Infrared (IR) wavelengths. In some embodiments, the interference filter and the absorption filter are arranged in a stack above the photosensor array. In other embodiments