Backside thinning of image array devices
First Claim
1. A CMOS imaging device supported on a die, said die having a reverse side and a front side, said CMOS imaging device comprising a pixel array disposed on a first areal portion of said die, circuits for readout of said pixel array disposed on another areal portion of said die, a region of said reverse side of said die thinned to a thickness in the range 2 to 20 μ
- m, said region of said reverse side limited to the area of projection of said pixel array on the corresponding portion of said front side.
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Accused Products
Abstract
Backthinning in an area selective manner is applied to imaging sensors 12 for use in electron bombarded devices. A further arrangement results in an array of collimators 51 aligned with pixels 42 or groups of pixels providing improved image contrast of such image sensor. Provision of a thin P-doped layer 52 on the illuminated rear surface provides both a diffusion barrier resulting in improved resolution and a functional shield for reference pixels. A gradient in concentration of P-doped layer 52 optimizes electron collection at the pixel array.
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Citations
40 Claims
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1. A CMOS imaging device supported on a die, said die having a reverse side and a front side, said CMOS imaging device comprising a pixel array disposed on a first areal portion of said die, circuits for readout of said pixel array disposed on another areal portion of said die, a region of said reverse side of said die thinned to a thickness in the range 2 to 20 μ
- m, said region of said reverse side limited to the area of projection of said pixel array on the corresponding portion of said front side.
- View Dependent Claims (2, 3, 4)
- 5. A solid state imaging device comprising a die, said die having a reverse side and a front side, said solid state imaging device comprising a pixel array substantially disposed on said front side within a first areal portion of said die, circuits for readout of said pixel array disposed on another areal portion of said die, a region of said reverse side being directly opposite said pixel array, an array of collimating structures overlying said region, said collimating structures aligned with said pixel array.
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14. A solid state imaging device comprising a die, said die having a front side and a reverse side, a pixel array disposed on said front side at a first areal section of said die, said reverse side of said die corresponding to said first areal section thinned to a thickness of approximately 2 to 20 μ
- m, circuits for readout of said pixel array disposed on a second areal section of said die, an array of collimators disposed on said thinned first areal section to transmit an electron flux directed toward said areal portion of said die through said collimators to said die.
- View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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15. A digital imaging camera comprising
optical components for forming an image on a focal surface, a photocathode disposed on said focal surface, a solid state imaging device supported on a die, said die having a reverse side and a front side, said solid state imaging device comprising a pixel array disposed on a first areal portion of said die, circuits for readout of said pixel array disposed on another areal portion of said die, the region of said reverse side directly opposite said pixel array disposed facing said photocathode, a vacuum enclosure for maintaining an evacuated space between said photocathode and said solid state imaging device, an electric potential imposed between said photocathode and said imaging device to maintain the distribution of said photoelectrons in accord with the optical distribution on said photocathode and to cause said photoelectrons penetrating said reverse side to interact with said active pixel array, said reverse side comprising a selectively thinned region in a predetermined pattern encompassing less than the entire surface of said reverse side of said die, wherein said predetermined pattern comprises portions adjacent said at least one selectively thinned region and overlaying a projection of selected pixels of said pixel array, whereby said selected pixels comprise reference pixels for obtaining a reference pixel signal.
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19. An imaging device sensitive to energetic electrons incident on the backside thereof, said device comprising a semiconductor die, said die having a reverse side and a front side, said imaging device comprising a pixel array substantially disposed on said front side and disposed on a first areal portion of said die, circuits for readout of said pixel array disposed on another areal portion of said die, a region of said reverse side of said die thinned to a thickness in the range 2 to 20 μ
- m, said region of said reverse side limited to the projection of said pixel array on said reverse side, said reverse side comprising a P-doped layer that introduces a potential barrier in the conduction band of at least 3 kT to electrons generated in the substrate, said P-doped layer comprising a concentration of at least 1018 dopant atoms/cm3 at said backside.
- View Dependent Claims (20, 21, 22)
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23. A backside illuminated pixel array sensor for intercepting an electron flux at said back surface, said electron flux having a spatial distribution comprising an image, said sensor comprising a P-doped layer of enhanced conductivity disposed intermediate pixels comprising said pixel array and the illuminated surface of said sensor, said P-doped layer having a maximum doping concentration in excess of 1018 atoms per cubic centimeter at said back surface and further comprising a smoothly varying concentration of a selected doping agent over the thickness of said P-doped layer, whereby a corresponding conduction band gradient is achieved.
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24. A solid state imaging device comprising first and second dice, said first die having a reverse side and a front side, said first die comprising a pixel array substantially disposed on said front side within a first areal portion of said first die, said pixels having a selected spacing p, circuits for readout of said pixel array disposed on another areal portion of said first die, a region of said reverse side being directly opposite said pixel array, and,
a said second die comprising an array of collimating structures, each said collimator having a collimation axis having an extension h and a cross-section sufficient to receive a pixel of said pixel array, said cross-section and said pixel characterised by similar geometrical shapes, a bonding medium disposed intermediate said the reverse side of said first die on selected portions thereof to adhere said first and second dice said collimating structures oriented in respect to said pixel array with no more than tolerable misalignment.
Specification