ambient light sensor

Abstract

An ambient light sensor includes: a first plurality of sensor elements (11a), each sensor element being configured to provide a signal in response to an illuminance; and a second plurality of reference elements (12a), wherein each reference element is configured to provide a reference signal and wherein each includes a blocking element (121a) configured to shield the respective reference element from being illuminated; wherein the first plurality (11a) is larger than the second plurality (12a) and the first plurality of sensor elements and the second plurality of reference elements are arranged in an arrangement; wherein a sensor element (11a) and a reference element (12a) are arranged laterally on or in a substrate (125) with a common layer, sharing at least one common first contact (124); wherein, in a top view of the ambient light sensor, the blocking element (121a) is larger than the corresponding reference element (12a); wherein the blocking element (121a) extends over a part of a sensor element (11a) of the first plurality of sensor elements adjacent to the reference element (12a); and wherein the part of the sensor element covered by the blocking element is between 5% and 50% of a total sensor area of ​​the sensor element.

Description

TECHNICAL FIELD

[0001] The present application relates to an ambient light detector. The application also discloses a detector assembly and a method of forming an ambient light sensor. BACKGROUND

[0002] An ambient light sensor (ALS) is an electronic device that measures ambient light intensity and outputs an electrical signal proportional to the illuminance. The output can then be used to control the intensity or color temperature of a lighting device. An ALS may include a photodiode array and a current amplifier.

[0003] Dark current is the relatively small electric current that flows through photosensitive devices such as photodiodes, even when no photons enter the device. Dark current consists of charge carriers generated in a detector when the detector is not illuminated by incident light. It is a temperature-dependent characteristic of semiconductors. Dark current can be increased by heating photodiodes and correspondingly reduced when the diode is cooled.

[0004] US 2014 / 0014818 A1 shows a pixel array configured to detect local and global dark currents through integrated black pixel blocks.

[0005] US 2011 / 0068255 A1 shows a light detector with several photodiode areas that are partially covered by an optical filter, a light-blocking material and not covered, in order to generate different currents.

[0006] To provide better measurement results with ambient light sensors, it is desirable to reduce the influence of dark current in such sensors.

[0007] The object of the present invention is to improve the sensitivity of an ambient light sensor by avoiding crosstalk between adjacent optical elements, in particular in the case of light scattering or at small light incidence angles.

[0008] This object is achieved with regard to the ambient light sensor according to the features of claim 1. SUMMARY

[0009] Embodiments provide an ambient light sensor with improved dark current compensation. In one aspect, the ambient light sensor comprises a first plurality of sensor elements, each sensor element configured to provide a signal when illuminated by light. In other words, each sensor element is configured to provide a signal in response to light illumination. The sensor signal may be proportional to the illuminance. The ambient light sensor comprises a second plurality of reference elements, each reference element configured to provide a reference signal and comprising a blocking element to shield the reference element from being illuminated. The first plurality is larger than the second plurality, and the first plurality of sensor elements and the second plurality of reference elements are arranged in an array.Furthermore, a sensor element and a reference element are arranged laterally in a common substrate, sharing at least one common contact.

[0010] In another aspect, an ambient light sensor comprises first sensor elements, each sensor element configured to provide a signal in response to an illuminance, and reference elements, each reference element configured to provide a reference signal, and each reference element comprising a blocking element configured to shield the respective reference element from being illuminated. The number of sensor elements is greater than the number of reference elements. Sensor elements and reference elements are arranged in an array. A sensor element and a reference element are laterally disposed on or in a common layer substrate, sharing at least one common first contact.

[0011] In one aspect, second contacts for the reference elements are arranged on a surface of the reference elements facing the blocking element. Furthermore, second contacts for the sensor elements can be arranged on a surface of the sensor elements facing the blocking element. Alternatively, these contacts can be arranged on a surface facing away from the blocking element. In some embodiments, the common contact is arranged on a surface of the substrate with a common layer facing away from the blocking element. This can be achieved, for example, by contact through the common substrate.

[0012] In some embodiments, the blocking element is larger from a top view than an area occupied by the respective reference element. For example, the blocking element may completely cover the reference element and extend further laterally between a gap between the reference elements and an adjacent sensor element of the first plurality of sensor elements.

[0013] In some examples, the blocking element may extend over a portion of a sensor element of the first plurality of sensor elements adjacent to the reference element. The portion of the sensor element covered by the blocking element may be between 5% and 50% of a total sensor area of ​​the sensor element, and in particular between 5% and 10%.

[0014] The sensor elements and the reference elements may each comprise a p-doped layer, an n-doped layer, and an active region therebetween configured to generate the signal when illuminated. In some other aspects, the sensor elements and / or the reference elements each comprise a well disposed in the common substrate to form an active layer between the well and the common substrate.

[0015] The number of sensors and reference elements may vary. In some embodiments, the sensor elements and reference elements are arranged in an array such that a ratio of sensor elements and reference elements along an edge of the array corresponds to a ratio between the first plurality and the second plurality.

[0016] In another aspect, an ambient light detector comprises a current mirror, the current mirror including a first current path and a second current path. The first current path includes a first plurality of photodiodes, and the second current path includes a second plurality of dark current diodes. The first plurality of photodiodes and the second plurality of dark current diodes are laterally arranged in a common substrate, while the first plurality and second plurality are different.

[0017] A mirror transistor is associated with the first current path, and a reference transistor is associated with the second current path. The mirror transistor and the reference transistor include a parameter ratio corresponding to a ratio between the first plurality and the second plurality.

[0018] In one embodiment, a compensation device is provided for supplying a compensation current into at least one of the first and second current paths in response to a digital mismatch compensation signal. In some aspects, the compensation device may be connected to the first current path between the first plurality of photodiodes and the mirror transistor, and / or the compensation device may be connected to the second current path between the second plurality of dark current diodes and the reference transistor.

[0019] In some aspects, an additional current limiter is configured to limit a current in the first current path. The current limiter may comprise a current sense resistor coupled to a clamping element, wherein said current sense resistor is configured to control a current-limiting element arranged in parallel with the mirror transistor in the first current path.

[0020] Furthermore, some aspects may relate to a gain adjustment element to be coupled to a first signal input or a second signal input, wherein the second signal input is the supply input. The gain adjustment element is configured to set a high gain when coupled to the first signal input and to a lower gain when coupled to the second signal input. The coupling of the gain adjustment element is substantially permanent in some aspects.

[0021] In some aspects, the gain adjustment element may comprise a gain adjustment transistor arranged in parallel with the mirror transistor and connected to its control input between the first plurality of photodiodes and the mirror transistor.

[0022] Another aspect relates to a photodiode of the first plurality. The photodiode may comprise a layer of a first conductivity type disposed in or on the common substrate. A dark current diode of the second plurality may comprise a layer of a first conductivity type disposed in or on the common substrate; wherein said common substrate has a second conductivity type. In some aspects, the ambient light detector may comprise at least one common contact for a photodiode of the first plurality and for a dark current diode of the second plurality, wherein one contact contacts the layer of the photodiode and one contact contacts the layer of the dark current diode.

[0023] Each dark current diode of the second plurality may include a blocking element configured to shield the respective dark current diode from being illuminated. In plan view, the blocking element may be larger and therefore completely cover the area of ​​the respective dark current diode and extend further laterally between a gap between the dark current diode and adjacent photodiodes of the first plurality. Thus, the blocking element may extend over a portion of the photodiodes of the first plurality adjacent to the dark current diode.

[0024] In some aspects, the first plurality is four times the second plurality. The photodiodes and the dark current diodes may be arranged in an array in or on the common substrate such that a ratio of sensor elements and reference elements along an edge of the array corresponds to a ratio between the first plurality and the second plurality.

[0025] In another aspect, a light detector array comprises a first plurality of photodiodes and a second plurality of reference diodes arranged laterally relative to one another such that a ratio of photodiodes and reference diodes along an edge of the array corresponds to a ratio between the first plurality and the second plurality.

[0026] In some aspects, each corner of the array may include a photodiode of the first plurality of photodiodes. For example, the first plurality of photodiodes is four times larger than the second plurality of photodiodes.

[0027] Another aspect relates to the formation of an ambient light sensor. In some embodiments, an ambient light sensor is formed by providing a layer having a major surface and a first conductivity type. At least two regions of a second conductivity type are formed on or within the layer. At least two regions are formed laterally adjacent to each other and separated by a first distance. Contacts are provided to electrically contact the layer and each of the at least two regions. Furthermore, a light shielding element is provided over one of the at least two regions substantially parallel to the major surface such that the light shield covers the one of the at least two regions and extends at least along the distance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Further aspects and various examples are further described in detail with accompanying illustrations in which: Fig. illustrates an exemplary embodiment of a dark current compensation circuit; Fig. shows an embodiment of an ambient light sensor according to some aspects of the proposed principle; Fig. shows a diagram illustrating crosstalk versus overlap of a blocking element; Fig. shows an embodiment of an ambient light detector; Fig. illustrates an exemplary embodiment of a DAC circuit used in the embodiment of Fig. must be used; Fig. shows an exemplary embodiment of an ambient light detector assembly according to some aspects; Fig. shows another exemplary ambient light detector arrangement; Fig. shows yet another exemplary ambient light detector arrangement; and Fig. shows an example of a method for forming an ambient light sensor. DETAILED DESCRIPTION OF ILLUSTRATIVE DESIGNS

[0029] An ambient light sensor is an electronic device that measures the intensity of ambient light. It outputs an electrical signal that is related to the illuminance, for example, directly proportional to the illuminance. However, due to thermal motion and varying ambient temperatures, the photodiode used to measure ambient light will deliver a small current, even when the sensor's photodiode itself is not illuminated. This is called dark current. To achieve dark current cancellation, a second photodiode is often used. Fig. Figure 1 illustrates the principle. A pickup 1 comprises the sensor photodiode 11 and a dark current photodiode 12. The dark current photodiode is shielded so that no measured light can reach the aperture of diode 12. In a combiner 15, the dark current of diode 12 is subtracted from the photodiode 11. The result is amplified in amplifier 14 and delivered to output 16.

[0030] The total response of the exposed photodiode 11 comprises the generated photocurrent induced by the incident ambient light and the (primarily thermally) generated dark current. The dark current diode 12 supplies only the dark current. This cancellation results in an improvement in sensor sensitivity, especially at low illuminance levels.

[0031] To achieve good results, both the photodiode and the dark current diode should be arranged similarly and close to each other. However, light incident on a photodiode structure at small angles of incidence or scattered light can reach the dark current diode and create crosstalk between neighboring structures.

[0032] To improve sensitivity, a photodiode array is proposed that includes a plurality of photodiode structures; and a light-blocking shield arranged to cover a first portion of the photodiode structure while allowing ambient light to reach a second portion of the photodiode structures, the first portion defining a group of reference photodiodes and the second portion defining a group of exposed photodiodes. The light-blocking shield is arranged relative to the photodiode structures such that the light-blocking material of the shield covers the reference photodiodes from ambient light while allowing ambient light to reach the remaining photodiode structures, thus exposing them to ambient light.The shield comprises a light-blocking structure such that the light protection blocks at least 90% of the light incident on the shielding structure or at least 99% of the light incident on the shielding structure.

[0033] In the context of the present disclosure, the phrase "reference diode" or "dark current diode" may be used in relation to a photodiode of a group of photodiode structures that are completely covered by the shield (when viewing the photodiode from a viewpoint along the normal of the photodiode).

[0034] In the context of the present disclosure, the phrase "exposed diode" or "photodiode" may be used in relation to a photodiode of the group of photodiode structures that are at most partially covered by the shield (when viewing the photodiode from a viewpoint along the normal of the photodiode).

[0035] Fig. Figure 2 shows an exemplary embodiment to illustrate some aspects. Both diodes are arranged adjacent to each other in a common p-type substrate 125. Each diode comprises an n-doped well 112 and 122, each arranged in a p-type substrate. Common anode contacts 124 are arranged on the surface to electrically contact substrate 125. Contacts 113 are arranged on the n-type well 112 to electrically contact the exposed photodiode 11a. Likewise, contacts 123 are arranged on the well 122 of the reference diode 12a.

[0036] The reference photodiodes and the exposed photodiodes are preferably physically identical and adjacent to each other at a distance d. However, due to manufacturing variances, the lateral diffusion of the n-doped wells 112 and 122 is not well controlled. It can vary from diode to diode, for both photodiodes and reference diodes. As a result, the photocurrent and dark current distributions can be broad.

[0037] To reduce the consequences of such a distribution, a blocking element, ie, a light shield 121a, is arranged over the reference diode 12a according to the proposed principle. The area covered by shield 121a is larger than the area covered by reference diode 12a in the substrate. In other words, as in Fig. As seen in Figure 2, the lateral dimensions of light shield 121a in this side view extend beyond the lateral dimensions of the reference diode, including the n-well 122, and the distance d between the photodiode and the reference diode. Consequently, the light shield overlaps laterally on the n-well of photodiode 112. Assuming that the lateral region of the photodiode "extends" half the distance d and that the reference diode also extends half the distance d, light shield 121a completely covers the region of the reference diode 12a and partially covers the region of the photodiode, and in particular the region with the p-substrate at its surface. The overlap of the light shield over the region of photodiode 11a can be a few micrometers. For example, the distance a can be between 1 µm and 20 µm. Likewise, the total overlap can be in the range of 5 µm to 50 µm or more.

[0038] The opening of the light shield is therefore smaller than the corresponding area of ​​the photodiode. The light shield 121a may comprise aluminum or any other light-blocking material. Such a light-blocking material is often impermeable and will prevent gases from flowing through the light-blocking regions of the shield. Fabrication of the photodiode array often includes annealing steps, which may be performed after the light-blocking shield has been mounted on the light sensor. To achieve uniform and efficient annealing of the photodiode structures, the shield is preferably arranged to allow space for the diffusion flow of hydrogen between the shield and the photodiode array.Accordingly, the light-blocking shield 121a is arranged at a distance h relative to the reference diode 12a, thus providing a space between the light-blocking shield and the reference diode. The space between them is filled with an annealed photoresist, silicon oxide, or any other suitable material. The distance h between the surface of the reference diode 12a and the light shield can be a few micrometers. The distance h can depend on the size of the light shield.

[0039] In some embodiments, the ratio between the lateral area of ​​an exposed photodiode and the area of ​​the corresponding transparent region not overlapped by the light shield is below 0.9, such as below 0.75, such as below 0.5.

[0040] Fig. Figure 3 shows a graph illustrating the resulting crosstalk of incident light versus the degree of overlap for a given distance h between the light shield and the reference diode. "Crosstalk" in this context refers to incident light that reaches the reference diode and causes a false signal. As can be seen, increasing overlap significantly reduces crosstalk. The benefit due to the overlap still outweighs the signal loss due to the smaller illumination area of ​​the photodiode.

[0041] Fig. Figure 4 shows an embodiment of an ambient light detector circuit. The circuit comprises a differential amplifier 150 having a first signal or current path 151 and a second signal or current path 152. The first signal path includes at least one photodiode 11b and a mirror transistor 158 arranged between an output node IOUT and a supply node VDD. The second signal path includes at least one reference diode 12b and a reference transistor 153, both also arranged in series between the output node IOUT and the supply node VDD. As shown in Fig. In Figure 4, there are five reference diodes connected in parallel (M=5), of which only one symbol is shown here. Likewise, there are 20 photodiodes (M=20) in the first current path, resulting in a ratio of 1:4.

[0042] In operation of the as in Fig. In the ambient light detector shown in Figure 4, a dark current of equal magnitude is generated in each reference diode and photodiode. Consequently, the dark current flowing through the first current path 151 is four times greater than the corresponding dark current flowing through the second current path 152. To compensate for the dark current, the differential amplifier, which uses transistors 153 and 154 to compensate for the dark current, must accommodate the different dark currents in the respective paths.

[0043] For this purpose, transistors 154 and 153 form a current mirror. Reference transistor 153 and mirror transistor 154 can be implemented as field-effect transistors as shown, but various types of elements such as MOSFETs, BJTs, and MES-FETs can be used as needed. The gates of both transistors 153 and 154 are connected to node 156 between the reference diode and reference transistor 153, thereby forming the current mirror. Such a current mirror mirrors the current through the reference transistor into the mirror transistor in a predefined ratio. This ratio is determined by the physical dimensions of the two transistors, given by a parameter M. Such a parameter can include the channel width of the transistor, its length, or a combination thereof. In the example of Fig. 4, the current mirrored into transistor 154 is 4 times the current through the reference transistor, thus matching the ratio between the number of reference diodes and photodiodes. In other words, the dark current through the reference diodes 12b in the second current path is mirrored into the first current path by a factor of 4. It is thus amplified by this factor and now compensates for the dark current in the first current path.

[0044] The output signal is applied to node 155. Node 155 is therefore connected to the gate of output transistor 158, which is located between supply node VDD and node 158. It thus also forms part of the amplifier's output stage 170. The output stage 170 also includes a current mirror stage, which includes path transistor 172, resistor 178, and current mirror 174. Path transistor 172 is connected in series with transistor 175 of current mirror 174 between supply node VDD and output node IOUT. Resistor 178 is connected in series with transistor 176 of current mirror 174 between supply node VDD and output node IOUT. The gates of transistors 175 and 176 are connected to node 171 between transistors 172 and 175, thus mirroring the current through transistor 175 to transistor 176.

[0045] Transistor 172 and transistor 158 also comprise a predefined current ratio given by the geometric parameter m and its respective values ​​m=1 and m=M, respectively. In other words, the current of transistor 172 is M-fold greater than transistor 158. Transistors 158 and 172 also form a current mirror with the mirror ratio 1:M. The current through transistor 158 is mirrored M-fold in transistor 172. Again, the current through transistor 172 is mirrored in transistor 176 with the same ratio (transistors 175 and 176 also comprise a 1:N ratio as in Fig. 4). Consequently, the output current at node IOUT during operation is equal to the photodiode current times the ratio of transistors 172 and 158 (M / 1) times the ratio of t=transistors 176 and 175 (N / 1) : I out = I photo * M * N equal.

[0046] In some examples, the light protection can be applied to the structure as in Fig. 2 illustrates introducing some stress into the structure. Hydrogen left over from the healing process can change the characteristics of the reference diodes. This could lead to a mismatch between the reference diodes in the second current path and the photodiodes in the first current path. A compensation circuit 160 is provided for mismatch compensation. The compensation circuit includes a DAC that provides a compensation signal at node 162. Depending on whether any signal needs to be added or subtracted, the output nodes are selectively coupled to the first or second signal path.

[0047] With reference to Fig. 5, the DAC may include reference node VSS and supply node VDD, as well as two output nodes OUT1 and OUT2. These are connected to the first and second current paths, respectively. The DAC also includes a plurality of compensation diodes D1 to D14 and switches S1 to S14. Each diode has a switch connected in series. Diodes D1 to D7 are arranged in parallel with their associated switches in series between reference node VSS and output nodes OUT1 / OUT2. Diodes D8 to D14 are arranged with their associated switches in series between supply node VDD and output nodes OUT1 / OUT2. Two further switches S15 and S16 are switched to selectively supply the signal from the compensation diodes to the corresponding output node.

[0048] Each compensation diode can thus be selectively switched into or out of the path and provides a signal to one of the output nodes. The range of diodes D1 to D7 (and D14 to D8) is selected so that the range of one diode is half the range of a subsequent diode. Therefore, an 8-bit logic signal, when switching the diode connections, can provide 256 different compensation values. Conventional transistors can be used instead of diodes.

[0049] With reference back to Fig. 4, another problem can arise because the gain of the current amplifier is large and, depending on the factor of M*N, can be in the range of several tens of thousands. In cases of very bright illumination, e.g., lasers and the like, the output current at node IOUT can be very large, causing overheating and damage to the ambient light detector. To prevent such an event, the circuit includes a current limiter. The current limiter uses resistor 178 of the output stage and further includes a clamping transistor 180. The clamping transistor 180 is arranged between supply node VDD and node 155. The gate of transistor 180 is connected to resistor 178 and transistor 176 of the output stage. In operation, the total output current is sensed by resistor 178.When a voltage drop across resistor 178 reaches a predefined threshold, the gate of clamp transistor 178 turns on and provides a clamp signal to the current mirror of transistors 158 and 172. This clamp signal sets the gate voltage of transistor 158, limiting the total output to a defined maximum output current value. Such a maximum output current value can be set by the threshold voltage of clamp transistor 180—adjustable by the physical parameter of this transistor—divided by the value of resistor 178.

[0050] In another aspect, the ambient light detector includes a selectable gain using a gain-adjustment transistor 190. The ambient light detector can cover a dynamic LUX range of several orders of magnitude, for example, in the range from 1m LUX to 100k LUX. Therefore, a different range for the output current is required to prevent the detector from reaching the maximum output current value too quickly. In some applications, for example, the light sensor may be exposed to a high LUX range, requiring low gain. This may be the case, for example, on a dashboard in automotive applications. On the other hand, a sensor behind the glass of a mobile phone often has lower light intensities and may therefore require high gain to achieve the same sensitivity. Fig. Figure 4 shows an example of two different selectable, but also permanent, gain settings. The benefit of the selectable gain is that inventory can be reduced and detector manufacturing is simplified because the current setting can be fixed at a later time. In the given example, the gain-setting transistor is arranged between node 155 and a setting node IDIV. The gate of the gain-setting transistor 190 is connected to node 155. In the high-gain setting, node IDIV is not bonded to the supply node VDD. In the low-gain setting, node IDIV is bonded to the supply node VDD, and the gain is reduced by a factor G. Overall, the output current in high-gain mode is given by I out = I photo * M * N. The gain for the low gain mode is given by I out = I photo * (M / G) * N given.

[0051] Another aspect relates to the arrangement of the reference and photodiodes on a surface of the ambient light detector. Fig. Figure 6 illustrates an example of a top view of an ambient light detector array having a first plurality of photodiodes 401 and a second plurality of reference diodes. In the example shown, the first plurality is 4 times larger than the second plurality and thus corresponds to the amplifier array of Fig. 4. The photodiodes and reference diodes are arranged in a pattern with a total length of D. Each diode has a dimension of d with an illuminated area of ​​w. The entire layout of the photodiodes and reference diodes is centered on a common center point, with a reference diode 400a at the center and additional reference diodes along the center of each edge. This reduces process gradient and variation during manufacturing, improving matching.

[0052] Furthermore, the ambient light detector array according to Example 2 shown includes "balanced edges." The number of photodiodes 401 along an edge of the detector is four times the number of reference diodes along such an edge. For example, there are four photodiodes 401a to 401d along the left edge of the detector and one reference diode 400a in the center, forming a mirror symmetry through an x-axis. In other words, the ratio of the total number of photodiodes and reference diodes matches the ratio of photodiodes and reference diodes along an edge of the detector. This reduces the total chip area of ​​the detector array but keeps the ratio the same for leakage current at the edges. The top surface is covered by a transparent material, e.g., an epoxy resin, SOG, or SiO, and the like. The light shield covers each of the reference diodes, as shown in this figure by the darker color.The light shield also extends partially in its lateral dimensions over the adjacent photodiodes (not shown here) to reduce crosstalk. Since the dark current is substantially independent of the illumination intensity, not all of the photodiodes need to be partially covered. As a result, the illumination-induced photocurrent in diode 401d is slightly larger than in photodiode 401c because the latter photodiode is partially covered. Since the photocurrent due to illumination is summed in the differential amplifier, small variances between the photodiodes are compensated.

[0053] Fig. Figure 7 shows another example of an ambient light detector array, such as a 3x3 checkerboard. In this embodiment, the ratio between photodiodes and reference diodes is 6:3 = 2:1. The reference diodes are arranged along a diagonal line within the checkerboard arrangement of the detector array. Furthermore, the ratio of photodiodes to reference diodes along one edge of the detector array is 2:1. A similar example is shown in Fig. Figure 8 illustrates an ambient light detector array having a 4x4 configuration. Reference diodes 400 are again arranged along a diagonal line of the board, while photodiodes 401 occupy the remaining space. The ratio of photodiodes to reference diodes along an edge of the array is 3:1.

[0054] Therefore, in order to maintain the same overall ratio as the ratio of the diodes along the edge, all reference diodes must be arranged across one of the diagonals of the ambient light detector array.

[0055] Fig. illustrates some aspects of a method of forming an ambient light sensor. In step S1, a substrate layer of a first conductivity type is provided, the layer having a main surface. The layer may, for example, be p-doped and made of GaAs, GaN, or any other suitable material. In step S2, a plurality of regions of a second conductivity type are deposited on or in the substrate layer laterally adjacent to one another and separated by a first distance. The formed regions may form a checkerboard in plan view, for example, an NxN checkerboard, where N is an integer greater than 2. Each region contains the second conductivity type region surrounded by a frame of the substrate layer.

[0056] A pn junction is formed between the second conductivity-type region and the substrate layer. The regions can be formed by depositing an n-type dopant in the substrate layer. Alternatively, one or more recesses can be etched into the p-type layer. The recesses can then be filled with n-type material. Other alternatives for forming a pn junction, using photodiodes or LED manufacturing techniques, can be used.

[0057] After forming the n-type well in the substrate layer, both the substrate layer and the n-type well are electrically contacted in step S2. For this purpose, contacts are applied to the surface. One or more common contacts can be arranged on the region of the substrate layer between two adjacent n-type wells. The contacts are formed from metal or a transparent conductive material such as ITO. The contacts are connected to a readout and amplifier circuit, which is either provided separately or formed integrally on the layered substrate.

[0058] Finally, in step S3, a light shielding element is formed over one or more regions. This light shield is positioned such that its lateral dimensions are larger than one of the defined regions, thus completely covering a region and also partially extending into neighboring regions. The light shield can be made of any non-transparent material, such as dark resin and the like. Metal, preferably with limited reflection, can also be used. Before forming the light shield, the array with the formed diodes can be completely covered by a transparent material, such as SOG, SiO, and the like. The light shielding element covers only a portion of the regions, so that the amount of uncovered regions is greater than the amount covered. The light shield can also be applied only over specific and dedicated regions, thus covering a diagonal of the array in plan view.

Claims

[1] An ambient light sensor comprising: a first plurality of sensor elements (11a), each sensor element configured to provide a signal in response to an illuminance; and a second plurality of reference elements (12a), each reference element configured to provide a reference signal and each comprising a blocking element (121a) configured to shield the respective reference element from being illuminated; wherein the first plurality (11a) is larger than the second plurality (12a) and the first plurality of sensor elements and the second plurality of reference elements are arranged in an array; wherein a sensor element (11a) and a reference element (12a) are arranged laterally on or in a common layer substrate (125), sharing at least one common first contact (124); wherein, in a plan view of the ambient light sensor, the blocking element (121a) is larger than the corresponding reference element (12a); wherein the blocking element (121a) extends over a portion of a sensor element (11a) of the first plurality of sensor elements adjacent to the reference element (12a); and wherein the portion of the sensor element covered by the blocking element is between 5% and 50% of a total sensor area of ​​the sensor element. [2] The ambient light sensor according to claim 1, wherein second contacts (123) for the reference elements are arranged on a surface of the reference elements facing the blocking element. [3] The ambient light sensor according to claim 1 or 2, wherein second contacts (113) for the sensor elements are arranged on a surface of the sensor elements facing the blocking element. [4] The ambient light sensor according to one of claims 1 to 3, wherein the common first contact (124) is arranged on a surface of the common layer substrate facing away from the blocking element. [5] The ambient light sensor according to claims 2 and / or 3, wherein the second contacts for the sensor elements and / or the reference elements are arranged on a surface of the common layer substrate facing away from the blocking element. [6] The ambient light sensor according to any one of claims 1 to 5, wherein the first plurality is 4 times the second plurality. [7] The ambient light sensor according to any one of claims 1 to 6, wherein the sensor elements and the reference elements each comprise a p-doped layer, an n-doped layer and an active region therebetween configured to generate the signal when illuminated. [8] The ambient light sensor according to any one of claims 1 to 7, wherein the sensor elements and / or the reference elements each comprise a well disposed in the common substrate to form an active layer between the well and the common substrate. [9] The ambient light sensor according to any one of claims 1 to 8, wherein the blocking element is arranged distally separated from a main surface of the reference element. [10] The ambient light sensor according to any one of claims 1 to 9, wherein the sensor elements and the reference elements are arranged in an array such that a ratio of sensor elements and reference elements along an edge of the array corresponds to a ratio between the first plurality and the second plurality.

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