Semiconductor element

Abstract

The utility model provides a semiconductor element. The semiconductor element includes a plurality of apertures in the top surface of the silicon medium forming a plurality of sub-superlenses to create a plurality of focuses rather than a single focus (resulting from the use of a single superlens). Thus, compared to a single optical path associated with a single superlens, the number of optical paths of incident light is reduced, which in turn reduces the angular response of incident photons. Accordingly, a pixel sensor including a plurality of sub-superlenses experiences improved light focusing and a larger signal-to-noise ratio. In addition, the size of the pixel sensor is reduced (in particular, the height of the pixel sensor), which makes the image sensor including the pixel sensor more miniaturized.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to a semiconductor device. BACKGROUND

[0002] Complementary metal-oxide-semiconductor (CMOS) image sensors convert light energy into electrical energy using a photosensitive CMOS circuit. The photosensitive CMOS circuit can include a photodiode formed in a silicon substrate. When the photodiode is exposed to light, a charge (known as photo current) is induced in the photodiode. The photodiode can be coupled to a switch transistor, which is used to sample the charge of the photodiode. The color can be determined by placing a filter over the photosensitive CMOS circuit.

[0003] The light received by the pixel sensors of a CMOS image sensor is typically based on three primary colors: red, green, and blue (R, G, B). The pixel sensors that sense light of each color can be defined by using a color filter that allows a specific color of light wavelength to enter the photodiode. Some pixel sensors can include a near-infrared (NIR) pass filter that blocks visible light and allows NIR light to pass through the photodiode. SUMMARY

[0004] Embodiments of the present application provide a semiconductor device including: a light sensor configured to convert incident light into an electrical signal; a medium configured to transmit the incident light to the light sensor; and a plurality of apertures located on a top surface of the medium opposite the light sensor and configured to direct the incident light toward a plurality of focal points associated with a top surface of the light sensor.

[0005] In some embodiments, the light sensor includes a germanium light sensor. In some embodiments, each aperture of the plurality of apertures has a width of about 0.5 micrometers (pm) or less. In some embodiments, the medium includes a silicon substrate. In some embodiments, further comprising: a dielectric layer filling the plurality of apertures. In some embodiments, further comprising: an isolation structure formed in the medium and surrounding the light sensor.

[0006] Embodiments of the present application provide a semiconductor device including: a light sensor configured to convert incident light into an electrical signal; a medium configured to transmit the incident light to the light sensor; and a set of apertures located on a top surface of the medium opposite the light sensor. The set of apertures includes: a first subset of apertures having a first opening arranged over a plurality of focal points associated with a top surface of the light sensor; and a second subset of apertures having a second opening smaller than the first opening that substantially surrounds the first subset of apertures in a plurality of circular patterns.

[0007] In some embodiments, the medium has a thickness of about 6.0 micrometers (pm) or less. In some embodiments, a light path from the top surface of the medium to the plurality of focal points is shorter than a light path from the top surface of the medium to a single focal point. In some embodiments, each hole of the set of holes has a height of about 0.5 micrometers (pm) or more. In some embodiments, further comprising: a dielectric layer filling the set of holes. In some embodiments, further comprising: an isolation structure formed in the medium and surrounding the photosensor.

[0008] Based on the above, the present disclosure provides techniques and apparatuses for forming holes in a silicon medium, which forms a plurality of sub-metalenses to generate a plurality of light focal points. In this way, the light path of the incident light is reduced compared to a single light path associated with a single metalens, which in turn reduces the angular response of the photons. As a result, the pixel sensor has better light focusing and a larger signal-to-noise ratio (SNR). In addition, the size of the pixel sensor is reduced (especially the height of the pixel sensor), which makes the image sensor containing the pixel sensor more miniaturized. BRIEF DESCRIPTION OF DRAWINGS

[0009] Various aspects of the disclosure will be best understood with reference to the following detailed description together with the drawings. It should be noted that the various features are not necessarily drawn to scale. In fact, the dimensions of the various features can be arbitrarily increased or decreased for the sake of clarity.

[0010] Figure 1 is a diagram of an example pixel array described herein.

[0011] Figures 2A-2C is a diagram of an example semiconductor structure described herein.

[0012] Figures 3A-3B is a diagram of an example light and energy focal points described herein.

[0013] Figures 4A-4E is a diagram of an example implementation described herein.

[0014] Figures 5A-5G is a diagram of an example implementation described herein.

[0015] Figure 6 is a flowchart of an example process related to forming a semiconductor structure described herein. DETAILED DESCRIPTION

[0016] The following disclosure provides a number of different embodiments or examples for implementing different features of the present application. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the making of first and second features on top of each other in the following description can include embodiments in which the first and second features are formed in direct contact, and can also include embodiments in which additional features can be formed between the first and second features such that the first and second features can not be in direct contact. Additionally, the present disclosure can repeat use of reference numerals and / or letters in various instances. This repetition of reference numerals and / or letters is for the purpose of simplification and clarity and is not intended to identify related items. The disclosure may, however, include related items not shown or described implying that the related items are in combination with or aligned in place with the items shown or described.

[0017] Furthermore, spatial or directional terms, such as "beneath", "below", "lower", "above", "upper" and the like, can be used in this disclosure and are intended to provide relative positions for one component or feature with respect to another component or feature. Such spatial or directional terms are intended to encompass different orientations of the device in use or operation, such as when the device is turned over. The device can be otherwise oriented (rotated 90 degrees or otherwise) and the spatial or directional terms will be interpreted accordingly.

[0018] In some cases, a pixel sensor converts a photon into an electrical signal. To focus the photon, a microlens can be used. However, microlenses are thick, and thus are not suitable for small image sensors, such as near-infrared (NIR) image sensors. A metalens can replace the microlens to achieve a thinner pixel sensor. For example, a metalens can include holes in a top surface of a silicon layer that are configured to focus incident light. However, when the light path through the silicon is long, the light rays are not well focused.

[0019] Some implementations herein provide techniques and apparatuses for forming holes in a silicon medium that form a plurality of sub-meta lenses to produce a plurality of light focusing points (also referred to as "foci") instead of a single point (produced due to the use of a single metalens). In this way, the light path of the incident light is reduced compared to the single light path associated with a single metalens, which in turn reduces the angular response of the photons. As a result, the pixel sensor has better light focusing and a greater signal-to-noise ratio (SNR). Additionally, the size of the pixel sensor is reduced (particularly the height of the pixel sensor), which makes the image sensor containing the pixel sensor more compact.

[0020] Figure 1is a diagram of an example pixel array 100 (or a portion thereof) described herein. The pixel array 100 can be included in an image sensor, such as a complementary metal-oxide-semiconductor (CMOS) image sensor, a back-side illuminated (BSI) CMOS image sensor, or another type of image sensor.

[0021] Figure 1 A top view of the pixel array 100 is shown. As shown, the pixel array 100 can include a plurality of pixel sensors 102. As further shown, the pixel sensors 102 can be arranged in a grid. In some implementations, the pixel sensors 102 are square-shaped (as shown in the example in Figure 1 Figure 1 In some implementations, the pixel sensors 102 include other shapes, such as circular, octagonal, diamond-shaped, and / or other shapes. Figure 1

[0022] The pixel sensors 102 can be configured to sense and / or accumulate incident light (e.g., light directed to the pixel array 100). For example, the pixel sensors 102 can absorb and accumulate photons of incident light in a photodiode. Accumulation of photons in the photodiode can generate a charge that is representative of an intensity or brightness of the incident light (e.g., a greater amount of charge can correspond to a greater intensity or brightness, while a lesser amount of charge can correspond to a lower intensity or brightness).

[0023] The pixel array 100 can be electrically connected to a back-end-of-line (BEOL) metallization stack (not shown) of the image sensor. The BEOL metallization stack can electrically connect the pixel array 100 to control circuitry that can be used to measure the accumulation of incident light in the pixel sensors 102 and convert the measurements into electrical signals.

[0024] As described above, Figure 1 are provided by way of example. Other examples can differ from those described Figure 1 For example, the pixel sensors 102 can be electrically isolated and optically isolated through an isolation structure, such as a deep trench isolation (DTI) structure (e.g., as described in connection with Figure 2A Figure 2C The isolation structure can include a plurality of interconnected trenches that are filled with a dielectric material, such as an oxide material. The trenches of the isolation structure can be included around a perimeter of the pixel sensors 102, such that the isolation structure encircles the pixel sensors 102. Further, the trenches of the isolation structure can extend into the substrate, where the isolation structure is formed to encircle the photodiodes and other structures of the pixel sensors 102 in the substrate. In some embodiments, the isolation structure includes a backside DTI (BDTI) structure having a high aspect ratio formed from a backside of the pixel array 100.

[0025] Figure 2A ​​​is a diagram of an example pixel sensor 200 described herein. The example pixel sensor 200 includes multiple sub-metalenses to produce multiple light focal points. In some embodiments, Figure 2A The example pixel sensor 200 shown may include the pixel array 100 (or a portion thereof), or may be included in the pixel array 100 (or a portion thereof). In some embodiments, the example pixel sensor 200 may be included in an image sensor. The image sensor may be a CMOS image sensor, a BSICMOS image sensor, or another type of image sensor.

[0026] like Figure 2A As shown, pixel sensor 200 may include pixel 202. Pixel 202 is supported by substrate 204, which may include a semiconductor die substrate, a semiconductor wafer, or another type of substrate in which semiconductor pixels may be formed. In some embodiments, substrate 204 is formed of silicon (Si), a material including silicon, a III-V compound semiconductor material such as gallium arsenide (GaAs), or silicon-on-insulator (SOI).

[0027] Pixel 202 may include a transfer gate 206 to control the transfer of photocurrent between photosensor 210 and a drain region (not shown). Transfer gate 206 may be energized (e.g., by applying a voltage or current to transfer gate 206) to form a conductive channel between photosensor 210 and the drain region (and / or drain extension region). Transfer gate 206 may be de-energized to remove or close the conductive channel, thereby blocking and / or preventing the flow of photocurrent between photosensor 210 and the drain region (and / or drain extension region). Thus, transfer gate 206 may facilitate electrical communication between pixel 202 and a BEOL metallization stack (not shown) for measuring the accumulation of incident light in pixel sensor 200 and converting the measurement into an electrical signal.

[0028] In some embodiments, an etch stop layer (ESL) 208 can prevent over-etching during the formation of the light sensor 210 and / or the isolation structure 214. The ESL includes a material that is resistant (or at least partially resistant) to certain types of dry and / or wet etching. The ESL can include a material that is resistant to etchants that can be used to etch other layers near the ESL. Selecting such a material provides etch selectivity and enables the ESL to remain unetched (or largely unetched) while other layers are etched. For example, the ESL 208 can include a nitride (e.g., aluminum nitride (AlN) and / or silicon nitride (SiN)) and / or an oxide (e.g., silicon oxynitride (SiO x N y ), aluminum oxynitride (AlON) and / or silicon oxide (SiO x))In some implementations, the ESL 208 includes multiple ESLs stacked together and configured to function as a single ESL.

[0029] The light sensor 210 can function as a photodiode. A photodiode includes a p-n junction or a PIN junction (e.g., a junction between a p-type portion, an intrinsic (or un-doped) portion, and an n-type portion) doped with multiple types of ions. For example, an ion implantation element tool can be used to implant n-type dopants to form a first portion (e.g., an n-type portion) of the photodiode and to implant p-type dopants to form a second portion (e.g., a p-type portion) of the photodiode. The light sensor 210 can be configured to absorb photons of incident light. The absorption of the photons causes the light sensor 210 to accumulate charge (referred to as a photocurrent) due to the photoelectric effect. Here, the photons strike the light sensor 210, which causes the light sensor 210 to emit electrons. The emission of the electrons causes the formation of electron-hole pairs, where the electrons migrate to a cathode of the light sensor 210 and the holes migrate to an anode, which in turn generates the photocurrent. The light sensor 210 can be formed of germanium (Ge), silicon (Si), or another type of semiconductor material capable of generating charge from photons of incident light.

[0030] In some implementations, the light sensor 210 is formed on a seed layer 212. The seed layer 212 can allow for the growth of crystalline germanium. For example, the seed layer 212 can chemically bond with a precursor such that the light sensor 210 is formed through epitaxial growth. Although Figure 2A The seed layer 212 is illustrated as a single layer, but other examples can include multiple seed layers arranged to improve lattice matching, reduce threading dislocations, reduce tensile stress, and / or improve the quality of the light sensor 210.

[0031] The isolation structure 214 can isolate the pixel sensor 200 from neighboring pixel sensors (e.g., in a pixel array). The isolation structure 214 can provide optical isolation by blocking or preventing light from spreading or leaking from the pixel sensor 200 to another pixel sensor, thereby reducing crosstalk. The isolation structure 214 can include trenches or DTI structures coated or lined with an anti-reflective coating (ARC) and filled with a dielectric layer. The isolation structure 214 can be formed in a grid layout, where the isolation structure 214 extends around the perimeter of the pixel sensor 200 (and intersects at various locations of the pixel array).

[0032] The medium 216 can transmit incident light to the light sensor 210. For example, incident light on a top surface of the medium 216 can propagate through the medium 216 and toward the light sensor 210 (where the photons are converted to an electrical signal). The medium 216 can include silicon (Si) or another type of light-transmissive material.

[0033] The pixel sensor 200 may further include a plurality of holes 218 formed on the top surface of the medium 216. The plurality of holes 218 are not uniform or random, but are configured to direct incident light toward a plurality of focal points associated with the top surface of the light sensor 210. For example, the plurality of holes 218 may be arranged as a combination of Figure 2B The circular pattern in the plurality of apertures 218 controls the phase of the incident light waves so that the waves focus toward a plurality of focal points (eg, combine constructively along paths to the focal points and destructively along other paths).

[0034] like Figure 2A As further shown, each hole has a height of about 0.5 micrometers (μm) or greater (e.g., Figure 2A Selecting a height of at least 0.5 μm allows for reflection and refraction of incident light initially directed away from light sensor 210, whereas using a smaller height will cause incident light to be reflected and / or refracted away from light sensor 210. Additionally, each aperture has a width of approximately 0.5 μm or less (e.g., as indicated by Figure 2A Selecting a width of no more than 0.5 μm allows for reflection and refraction of incident light initially directed away from light sensor 210 , while using a larger width would allow excessive reflection off the bottom surface of aperture 218 and away from light sensor 210 .

[0035] Because the multiple apertures 218 direct the incident photons toward multiple focal points (e.g., as combined Figure 3A and Figure 3B As described above, the plurality of apertures 218 can be configured to have a shorter focal length than would be possible using a single focal point. In this manner, the thickness or depth of the medium 216 (e.g., as determined by Figure 2A The thickness of the medium (denoted by d in FIG) is approximately 6.0 μm or less. Selecting a thickness of no more than 6.0 μm can improve the dark performance of the pixel sensor 200 by reducing the optical path length and the angular response of the incident light, and allow the pixel sensor 200 to be further miniaturized. Using a thicker medium will result in a decrease in the performance of the pixel sensor 200 and hinder the development of miniaturization. Figure 2A As shown, the thickness is measured from the top surface of the light sensor 210 to the bottom surface of the at least one hole 218 .

[0036] Figure 2B is a diagram of an example pixel sensor 200 described herein. Figure 2B and Figure 2A Similarly, the example pixel sensor 200 is shown in a top view rather than a cross-sectional view. Figure 2BAs shown, the plurality of holes 218 includes a first set of holes 218a and a second set of holes 218b. The first set of holes 218a is larger than the second set of holes 218b. Each hole in the first set of holes 218a has a larger surface area (on the top surface and / or on the bottom surface) than each hole in the second set of holes 218b. For example, each hole in the first set of holes 218a can have a larger width than each hole in the second set of holes 218b. Thus, each hole in the first set of holes 218a has a larger volume than each hole in the second set of holes 218b, even if each hole has approximately the same height (e.g., the same height within 5% or 10% error).

[0037] The first set of holes 218a is arranged over a plurality of focal points on the light sensor 210 (which are located below the medium 216, thus below the light source 212 in Figure 2B Additionally, the second set of holes 218b is arranged in a plurality of circular patterns (e.g., patterns 220a, 220b, 220c, and 220d in Figure 2B approximately surround the first set of holes 218a. As used herein, a first set of holes “approximately surround” a second set of holes when a hole in the first set of holes exists along at least three perpendicular vectors that originate at a center associated with the second set of holes and are oriented outward from the center. As used herein, a “circular pattern” refers to a set of holes that are approximately equidistant (e.g., within 5% or 10% error) from a center point. Based on the plurality of circular patterns, the plurality of holes 218 direct incident light toward a plurality of focal points (e.g., as described in connection with Figure 3A and Figure 3B

[0038] As further shown in Figure 2B The third set of holes 218c can be larger than the second set of holes 218b but smaller than the first set of holes 218a. Each hole in the third set of holes 218c has a larger surface area (on the top surface and / or on the bottom surface) than each hole in the second set of holes 218b, but has a smaller surface area (on the top surface and / or on the bottom surface) than each hole in the first set of holes 218a. For example, each hole in the third set of holes 218c can have a larger width than each hole in the second set of holes 218b, but have a smaller width than each hole in the first set of holes 218a. Thus, each hole in the third set of holes 218c has a larger volume than each hole in the second set of holes 218b, and has a smaller volume than each hole in the first set of holes 218a, even if each hole has approximately the same height (e.g., the same height within 5% or 10% error).

[0039] Similarly, the third set of holes 218c is arranged in a plurality of circular patterns (e.g., patterns 220a, 220b, 220c, and 220d in Figure 2B ​The circular patterns 225a, 225b, 225c, and 225d are substantially concentric with the circular patterns 220a, 220b, 220c, and 220d, respectively. As used herein, a first circular shape is "substantially concentric" with a second circular shape based on a center associated with the first circular shape being proximate to a center associated with the second circular shape (e.g., the same point or a 5% or 10% error range relative to the circular radius). Based on the concentric circular patterns, the plurality of holes 218 control the phase of the incident light waves in order to focus the incident light waves to a plurality of focal points (e.g., as described in connection with Figure 3A and Figure 3B

[0040] Figure 2C is a diagram of an example pixel sensor 250 described herein. The example pixel sensor 250 has an anti-reflective layer. In some implementations, the example pixel sensor 250 can include or can be included in the pixel array 100 (or a portion thereof). In some implementations, the pixel sensor 250 can be included in an image sensor. The image sensor can be a CMOS image sensor, a BSICMOS image sensor, or other type of image sensor. Figure 2C

[0041] As shown, the dielectric layer 252 fills the plurality of holes 218. In addition, as shown, the dielectric layer 252 covers the top surface of the medium 216. The dielectric layer 252 has anti-reflective properties. For example, the dielectric layer 252 can reduce reflection from the bottom surface of the holes 218 to improve performance of the light sensor 210. In addition, the dielectric layer 252 has a different index of refraction than the medium 216 in order to allow the holes 218 to direct incident light to the light sensor based on refraction. The dielectric layer 252 can include an oxide material and / or another type of material having anti-reflective properties. Figure 2C Figure 2C As described above, the provision of the dielectric layer 252 is provided as an example. Other examples can differ with respect to the dielectric layer 252 as described in connection with

[0042] As described above, the provision of the dielectric layer 252 is provided as an example. Other examples can differ with respect to the dielectric layer 252 as described in connection with Figures 2A-2C For example, while the example pixel sensor 250 is described in connection with two different sizes of holes, other examples can include additional variability (e.g., three different sizes of holes, four different sizes of holes, etc.). For example, a group of medium-sized holes can be substantially encircled by a circular pattern around the first group of holes 218a, but remain inscribed within the second group of holes 218b. Figures 2A-2C Figure 2B In addition to the provision of the dielectric layer 252, other examples can differ with respect to the pixel sensor 250 as described in connection with

[0043] In addition to the provision of the dielectric layer 252, other examples can differ with respect to the pixel sensor 250 as described in connection with Figure 2B ​​​​In addition to the described pattern, the plurality of apertures 218 may alternatively be arranged based on output from a machine learning model trained on historical data. For example, the machine learning model may include historical focal paths of incident light (e.g., estimated based on energy measurements from light sensor 210, an example of which is shown in FIG. Figure 3A 210 ) is associated with a historical pattern of the plurality of apertures 218. Other parameters used by the model may include a historical thickness (and / or desired thickness) of the medium 216, a material used as the medium 216, a thickness and / or material used for the dielectric layer 252, a height associated with the plurality of apertures 218, and / or a width range associated with the plurality of apertures 218, etc. For a combination of focal points on the light sensor 210, the machine learning model may have been trained to estimate the pattern of apertures that would result in the combination of focal points. Thus, the machine learning model may accept as input a set of desired focal points on the light sensor 210 and output data indicating a pattern of apertures to be used.

[0044] Figure 3A is a diagram of an example energy distribution 300 for an example pixel sensor 200 described herein. Figure 3A As shown, the energy associated with the light sensor 210 is concentrated at multiple points due to the multiple sub-metalenses, as shown in FIG. Figure 2A and Figure 2B The example energy distribution of a pixel sensor with a single metalens would be concentrated at a single point on the top surface of the light sensor 210, rather than Figure 3A Multiple points shown in .

[0045] Figure 3B is a cross-sectional view of an example pixel sensor 350 described herein. In some embodiments, Figure 3B The example pixel sensor 350 shown can include the pixel array 100 (or a portion thereof), or can be included in the pixel array 100 (or a portion thereof). In some embodiments, the example pixel sensor 350 can be included in an image sensor. The image sensor can be a CMOS image sensor, a BSICMOS image sensor, or another type of image sensor.

[0046] Figure 3B An example pixel sensor 350 is similar to Figure 2A and Figure 2B Example pixel sensor 200. Figure 3B As shown, a plurality of holes 218 formed on the top surface of the medium 216 focus the incident light toward a plurality of focal points 352. Figure 3B A cross section is shown, so two focal points 352a and 352b are shown. However, additional focal points may be used, e.g. Figure 3AThe four focal points that can be detected in the example energy distribution 300. In comparison to using a single focal point (e.g., caused by using a single superlens instead of multiple sub-superlenses), the multiple focal points 352 are associated with a shorter focal length. As such, the thickness of the medium 216 can be reduced in comparison to a pixel sensor using a single superlens, which in turn reduces the angular response of the incident photons in comparison to the angular response caused by a single superlens.

[0047] As described above, providing Figures 3A-3B as an example. Other examples can vary from the described examples in relation to Figures 3A-3B For example, additional focal points can be configured (e.g., six focal points or eight focal points, etc.), or fewer focal points can be configured (e.g., three focal points or two focal points).

[0048] Figures 4A-4E is a diagram of an example implementation 400 described herein. The example implementation 400 can be an example process or method for forming a pixel sensor 250. The implementation 400 can include a photolithography technique for forming multiple apertures that function as multiple sub-superlenses.

[0049] As Figure 4A illustrated, an example process for forming a pixel sensor can be performed in relation to a substrate 204 that supports a transfer gate 206, an ESL 208, and a light sensor 210 formed on a seed layer 212. As Figure 4A further illustrated, a medium 216 can be formed over the light sensor 210. A deposition tool can deposit the medium 216 using a spin-on technique, a chemical vapor deposition (CVD) technique, a physical vapor deposition (PVD) technique, an atomic layer deposition (ALD) technique, and / or another deposition technique. As described in relation to Figure 3A the medium 216 can be formed to a thickness of approximately 6.0 pm or less.

[0050] The medium 216 also includes an isolation structure 214 that surrounds the light sensor 210. For example, a deposition tool can form a photoresist layer over and / or on a front side surface of the medium 216, an exposure tool can expose the photoresist layer to a source of radiation to form a pattern on the photoresist layer, and a development tool can develop and remove portions of the photoresist layer to expose the pattern. An etching tool can etch the medium 216 according to the pattern of the photoresist layer using a wet etching technique, a dry etching technique, a plasma enhanced etching technique, and / or another type of etching technique to form a trench for the isolation structure 214. After etching the medium 216, a photoresist removal tool can remove remaining portions of the photoresist layer (e.g., using a chemical stripper, a plasma asher, and / or other techniques), and a deposition tool can deposit a dielectric material in the trench to form the isolation structure 214 using a spin-on technique, a CVD technique, a PVD technique, an ALD technique, and / or another deposition technique.

[0051] As shown in Figure 4A Further, a mask layer 402 can be formed. For example, a deposition tool can form the mask layer 402 over and / or on the front side surface of the medium 216 (e.g., using a spin-on technique, a CVD technique, a PVD technique, an ALD technique, and / or another deposition technique).

[0052] As shown in Figure 4B The mask layer 402 can be patterned (e.g., according to a sub-hyperlens pattern, such as the pattern described in connection with Figure 2B For example, an exposure tool can expose the mask layer 402 to a radiation source to form a pattern on the mask layer 402, and a development tool can develop and remove portions of the mask layer 402 to expose the pattern. As described in connection with Figure 3A and Figure 3B The pattern can be configured to direct incident light to a plurality of focal points associated with the top surface of the photosensor 210.

[0053] As shown in Figure 4C Portions of the medium 216 can be removed. For example, an etching tool can etch the medium 216 using a wet etching technique, a dry etching technique, a plasma enhanced etching technique, and / or another type of etching technique. The exposed portions of the medium 216 can be etched according to the pattern of the mask layer 402. In this way, a plurality of holes 218 are formed on the top surface of the medium 216.

[0054] As shown in Figure 4C Further, the mask layer 402 is removed. For example, after the plurality of holes 218 are formed, a photoresist removal tool can remove the remaining portions of the mask layer 402 (e.g., using a chemical stripper, a plasma asher, and / or another technique).

[0055] As shown in Figure 4D A dielectric layer 252 can be formed. For example, a deposition tool can form the dielectric layer 252 over and / or on the front side surface of the medium 216 (e.g., using a spin-on technique, a CVD technique, a PVD technique, an ALD technique, and / or another deposition technique). As described in connection with Figure 2C The dielectric layer 252 can exhibit anti-reflective properties.

[0056] Since the dielectric layer 252 fills the plurality of holes 218 during deposition, the top surface of the dielectric layer 252 is not flat, as shown in Figure 4D Accordingly, as shown in Figure 4E The top surface of the dielectric layer 252 can be smoothed. For example, a planarization tool smoothens the top surface of the dielectric layer 252 by using a chemical mechanical planarization (CMP) technique.

[0057] As described above, aFigures 4A-4E As an example. Other examples can differ with respect to the specific Figures 4A-4E described. In some implementations, the dielectric layer 252 is omitted. Thus, an example process for forming a pixel sensor can be completed after the operations described in connection with Figure 4C described. In some implementations, the dielectric layer 252 is omitted. Thus, an example process for forming a pixel sensor can be completed after the operations described in connection with Figure 4E described. In some implementations, the dielectric layer 252 is omitted. Thus, an example process for forming a pixel sensor can be completed after the operations described in connection with

[0058] Additionally or alternatively, the mask layer 402 can include multiple layers configured to allow the formation of the plurality of holes 218 via photolithography. For example, the multiple layers can include a bottom layer, an intermediate layer, and a photoresist layer.

[0059] Figures 5A-5G is a diagram of an example implementation 500 described herein. The example implementation 500 can be an example process or method for forming a pixel sensor 200. The example implementation 500 can include a double patterning technique for forming a plurality of holes that function as a plurality of sub-hyperlenses. The double patterning can enable a smaller width of some of the holes compared to other photolithography techniques while consuming additional power, processing resources, and raw materials.

[0060] As shown in Figure 5A an example process for forming a pixel sensor can be performed in connection with a substrate 204 that supports a transfer gate 206, an ESL 208, and a light sensor 210 formed on a seed layer 212. Additionally, as further shown in Figure 5A the medium 216 is formed over the light sensor 210, and the medium 216 includes an isolation structure 214 that surrounds the light sensor 210.

[0061] As shown in Figure 5A a first material 502 can be formed. For example, a deposition tool can form the first material 502 over and / or on a front side surface of the medium 216 (e.g., using a spin-on technique, a CVD technique, a PVD technique, an ALD technique, and / or another deposition technique). The first material 502 can include a metal (e.g., titanium nitride (TiN), tungsten (W), and / or aluminum (Al), among others) and / or another material that can be etched separately from the mask layer 402 (e.g., by using a different etchant and / or a different etching technique).

[0062] As further shown in Figure 5A a mask layer 402 can be formed. For example, a deposition tool can form the mask layer 402 over and / or on a front side surface of the first material 502 (e.g., using a spin-on technique, a CVD technique, a PVD technique, an ALD technique, and / or another deposition technique). The mask layer 402 can include a high-k material and / or another material that can be etched separately from the first material 502 (e.g., by using a different etchant and / or a different etching technique).

[0063] As shown in Figure 5B , the mask layer 402 can be patterned. For example, an exposure tool can expose the mask layer 402 to a source of radiation to form a pattern on the mask layer 402, and a development tool can develop and remove portions of the mask layer 402 to expose the pattern. The pattern can be an intermediate pattern that is designed such that the final pattern of the top surface of the medium 216 is configured to direct incident light to a plurality of focal points associated with the top surface of the photosensor 210.

[0064] As shown in Figure 5C , a portion of the first material 502 can be removed. For example, an etching tool can etch the first material 502 using a wet etching technique, a dry etching technique, a plasma enhanced etching technique, and / or another type of etching technique. The exposed portions of the first material 502 can be etched according to the pattern of the mask layer 402.

[0065] As shown in Figure 5C , the mask layer 402 is removed. For example, after etching the first material 502, a photoresist removal tool can remove the remaining portions of the mask layer 402 (e.g., using a chemical stripper, a plasma asher, and / or other techniques).

[0066] As shown in Figure 5D , a second material 504 can be formed adjacent to the first material 502. For example, a deposition tool can form the second material 504 over and / or on the front side surface of the medium 216 (e.g., using a spin-on technique, a CVD technique, a PVD technique, an ALD technique, and / or another deposition technique). The second material 504 can include a metallic material, an oxide material, and / or another material that can be etched separately from the first material 502 (e.g., by using a different etchant and / or a different etching technique). In some implementations, the second material 504 includes a material that can be selectively deposited on the medium 216. Thus, as shown in Figure 5D , the second material 504 is deposited on the exposed surface of the medium 216, but not on the top surface and sidewalls of the first material 502. Additionally, the second material 504 includes a material that can be selectively deposited on the first material 502. Thus, the second material 504 can be deposited on the top surface and sidewalls of the first material 502, but not on the exposed surface of the medium 216.

[0067] As shown in Figure 5E , the first material 502 can be removed. For example, an etching tool can perform an isotropic etching cycle (e.g., using dry etching or wet etching) to remove the first material 502. For example, the second material 504 can be selected for its resistance to the etchant and / or etching technique used to remove the first material 502. In this way, the second material 504 can remain in the sub-hyperlens pattern, such as in combination withFigure 2B The described pattern.

[0068] As Figure 5F illustrated, the medium 216 can be patterned (e.g., according to a sub-holographic lens pattern, such as the pattern described in connection with Figure 2B ). For example, an etching tool can perform an isotropic etching cycle (e.g., using dry etching or wet etching) to remove a portion of the medium 216 that is not under a remaining portion of the second material 504. For example, the second material 504 can be selected for its resistance to the etchant and / or etching technique used to remove the medium 216. The medium 216 is etched to form a plurality of holes 218. As described in connection with Figure 3A and Figure 3B , the plurality of holes 218 can be configured to direct incident light to a plurality of focal points associated with a top surface of the light sensor 210.

[0069] As Figure 5G illustrated, the second material 504 can be removed. For example, an etching tool can perform an isotropic etching cycle (e.g., using dry etching or wet etching) to remove the second material 504.

[0070] As described above, the provision Figures 5A-5G is provided as an example. Other examples can differ with respect to the specific embodiments described herein. For example, the dielectric layer 252 can be included in some embodiments (e.g., using the operations described in connection with Figures 5A-5G and Figure 4D ). Figure 4E Additionally or alternatively, the mask layer 402 can include a plurality of layers. For example, the plurality of layers can include a bottom layer, a middle layer, and a photoresist layer. Additionally or alternatively, although the example embodiment 400 is described in connection with sidewall image transfer, other multiple patterning techniques can be used, such as pitch splitting, self-aligned double patterning (SADP), or directed self-assembly (DSA), among others.

[0071]

[0072] is a flowchart of an example process 600 associated with forming a sub-holographic lens described herein. In some embodiments, one or more process blocks of Figure 6 are performed using one or more semiconductor processing tools referenced in connection with Figures 4A-4E and Figures 5A-5G . Additionally or alternatively, one or more process blocks of Figure 6 may be performed using another device or set of devices separate from or including the one or more semiconductor processing tools, such as a processing tool that can be included in a lens manufacturing facility. Figure 6 ​

[0073] As shown in Figure 6 Process 600 can include forming a mask layer over a medium configured to transmit incident light to a light sensor (block 610). For example, one or more semiconductor processing tools can be used to form mask layer 402 over medium 216 configured to transmit incident light to light sensor 210, as described herein.

[0074] As further shown in Figure 6 Process 600 can include patterning a top surface of the medium to include a plurality of holes using the mask layer (block 620). For example, one or more semiconductor processing tools can be used to pattern a top surface of medium 216 to include a plurality of holes 218 using mask layer 402, as described herein. The plurality of holes 218 are configured to direct incident light toward a plurality of focal points 352 associated with a top surface of light sensor 210.

[0075] Process 600 can include additional implementations, such as any single implementation or any combination of the implementations described below and / or in connection with one or more other processes described elsewhere herein.

[0076] In a first implementation, patterning the top surface of medium 216 to include a plurality of holes 218 includes forming a first set of holes 218a having a first opening arranged over the plurality of focal points 352, and forming a second set of holes 218b having a second opening smaller than the first opening substantially surrounding the first set of holes 218a in a plurality of circular patterns.

[0077] In a second implementation, alone or in combination with the first implementation, process 600 includes forming medium 216 having a thickness of about 6.0 pm or less.

[0078] In a third implementation, alone or in combination with one or more of the first and second implementations, process 600 includes removing mask layer 402 after patterning the top surface of medium 216.

[0079] In a fourth implementation, alone or in combination with one or more of the first through third implementations, each hole of the plurality of holes 218 has a height of about 0.5 pm or more and a width of about 0.5 pm or less.

[0080] In a fifth implementation, alone or in combination with one or more of the first through fourth implementations, process 600 includes filling the plurality of holes 218 with a dielectric layer 252. The dielectric layer 252 can also cover the top surface of medium 216. In some examples, process 600 includes smoothing a top surface of dielectric layer 252 using CMP.

[0081] Although Figure 6Example blocks of the process 600 are shown, but in some implementations, the process 600 includes additional blocks, fewer blocks, different blocks, or differently arranged blocks than those shown in FIG. 6. Additionally or alternatively, two or more of the blocks or the process 600 can be performed in parallel. Figure 6

[0082] In this way, the plurality of holes in the top surface of the silicon medium forms a plurality of sub-holograms, resulting in a plurality of focal points instead of a single point (resulting from the use of a single hologram). As such, the optical path of the incident light is reduced compared to the single optical path associated with the single hologram, which in turn reduces the angular response of the incident photons. As a result, the pixel sensor including the plurality of sub-holograms experiences improved light focusing and greater SNR. Additionally, the size of the pixel sensor is reduced (particularly the height of the pixel sensor), which enables the image sensor containing the pixel sensor to be more miniaturized.

[0083] As described in more detail above, some implementations described herein provide a semiconductor element. The semiconductor element includes a light sensor configured to convert incident light into an electrical signal. The semiconductor element includes a medium configured to transmit the incident light to the light sensor. The semiconductor element includes a plurality of holes on a top surface of the medium opposite the light sensor, configured to direct the incident light toward a plurality of focal points associated with a top surface of the light sensor.

[0084] As described in more detail above, some implementations described herein provide a method. The method includes forming a mask layer over a medium configured to transmit incident light to a light sensor. The method includes patterning a top surface of the medium to include a plurality of holes using the mask layer, wherein the plurality of holes are configured to direct the incident light toward a plurality of focal points associated with a top surface of the light sensor.

[0085] As described in more detail above, some implementations described herein provide a semiconductor element. The semiconductor element includes a light sensor configured to convert incident light into an electrical signal. The semiconductor element includes a medium configured to transmit the incident light to the light sensor. The semiconductor element includes a set of holes on a top surface of the medium opposite the light sensor. The set of holes includes a first subset of holes having a first opening arranged over a plurality of focal points associated with a top surface of the light sensor. The set of holes includes a second subset of holes having a second opening smaller than the first opening that substantially surrounds the first subset of holes in a plurality of circular patterns.

[0086] As used herein, “satisfies a threshold” can refer to a value that is greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, depending on the context.

[0087] ​The foregoing summarizes features of several embodiments in order that those skilled in the art can better understand various aspects of the present disclosure. Those skilled in the art should appreciate that they can readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and / or achieving the same advantages of the embodiments presented herein without departing from the spirit and scope of the present disclosure. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and alterations can be made therein without departing from the spirit and scope of the present disclosure.

Claims

1. A semiconductor element comprising: a light sensor configured to convert incident light into an electrical signal; a medium configured to transmit the incident light to the light sensor; as well as A plurality of apertures are located on a top surface of the medium opposite the light sensor and are configured to direct the incident light toward a plurality of focal points associated with the top surface of the light sensor.

2. The semiconductor device according to claim 1, wherein The light sensor comprises a germanium light sensor.

3. The semiconductor device according to claim 1, wherein Each hole in the plurality of holes has a width of about 0.5 microns or less.

4. The semiconductor device according to claim 1, wherein The medium includes a silicon substrate.

5. The semiconductor device according to claim 1, wherein Also includes: A dielectric layer fills the plurality of holes.

6. The semiconductor device according to claim 1, wherein Also includes: An isolation structure is formed in the medium and surrounds the light sensor.

7. A semiconductor device comprising: a light sensor configured to convert incident light into an electrical signal; a medium configured to transmit the incident light to the light sensor; as well as a set of holes located on a top surface of the medium opposite the light sensor and comprising: a first subset of apertures having first openings disposed above a plurality of focal points associated with a top surface of the light sensor; as well as A second subset of holes having a second opening smaller than the first opening substantially surrounds the first subset of holes in a plurality of circular patterns.

8. The semiconductor device according to claim 7, wherein The dielectric has a thickness of about 6.0 microns or less.

9. The semiconductor device according to claim 7, wherein The optical path from the top surface of the medium to the multiple focal points is shorter than the optical path from the top surface of the medium to a single focal point.

10. The semiconductor device according to claim 7, wherein Each hole in the set of holes has a height of about 0.5 microns or greater.

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