NL2024439B1

NL2024439B1 - Semiconductor photo detector device

Info

Publication number: NL2024439B1
Application number: NL2024439A
Authority: NL
Inventors: Chen Tao; Gerard Van Der Wiel Wilfred
Original assignee: Univ Twente
Priority date: 2019-12-12
Filing date: 2019-12-12
Publication date: 2021-09-01
Also published as: WO2021118360A1

Abstract

A photodetector is provided for sensing radiation in middle and long wave infrared domain. The sensor has a sensor layer of a ﬁrst material having a ﬁrst conductivity type and a ﬁrst permittivity in which the shortest distance of any point in the sensor layer to an adjacent layer having a second conductivity type and a second permittivity lower than the ﬁrst permittivity is 20 nanometres or less. Conductivity type may be semiconductor n-type or p-type or insulator. If, for example, a silicon sensor layer is sandwiched between two silicon oxide layers, the sensor layer of preferably p-type semiconductor has a maximum thickness of 40 nanometres. If a p-type layer of a ﬁrst material is sandwiched between a dielectric layer with the second permittivity and an n-type layer of the ﬁrst material, the maximum thickness is 20 nanometres. Spaced apart, two contacts are provided in contact with the sensor layer.

Description

P122513NL00 Title: Semiconductor photo detector device

TECHNICAL FIELD The various aspects related to a semiconductor sensor for detection of medium and long wavelength infrared light.

BACKGROUND Semiconductor sensors and in particular silicon sensors are known for detection of near infrared. With a bandgap of about 1.1 eV, light having wavelengths around 1.1 micron or smaller may be detected. Light - electromagnetic radiation - having larger wavelengths may not be detected, in particular not at a temperature interval around room temperature.

SUMMARY With a desire to reduce use of energy and to conserve energy, there is a need for sensors that may be used for imaging thermal radiation in the mid- and long-infrared field that are convenient to use: portable and without cooling.

A first aspect provides a semiconductor photo detector device for detecting light having a wavelength between 1 micrometre and 20 micrometres, preferably between 3 micrometre and 15 micrometre. The device comprises a semiconductor sensor layer having a sensor region having a first conductivity type and a first permittivity - or dielectric constant -, a first terminal for providing a first electrical contact to the sensor region and a second terminal for providing a second electrical contact to the sensor region, the second electrical contact being spaced away from the first electrical contact. The device further comprises a first boundary layer having a second conductivity type and a second permittivity provided at a first side of the sensor layer and a second boundary layer having a third conductivity type and a third permittivity provided at a second side of the sensor layer, the second side being opposite to the first side. In this device, at least one of the second permittivity and the third permittivity is less than the first permittivity and the sensor region has a thickness of 20 nanometres or less if one of the second permittivity and the third permittivity is less than the first permittivity and the sensor region has a thickness of 40 nanometres or less if the second permittivity and the third permittivity are less than the first permittivity.

In this device, the distance between any point in the sensor region and a material in a boundary layer having a permittivity less than that of the sensor region is 20 nanometres or less.

With any point in the sensor region being 20 nanometres or less away from lower permittivity material, conductivity in the sensor region is at least partially and preferably dominantly or fully governed by hopping conduction. The ionisation energy of majority charge carriers is significantly larger than the dopant ionisation energy in the bulk semiconductor material - for boron and phosphorous in silicon about 45 meV (other types of material may be used as well). Rather, with a sensor region having a thickness of 20 nanometres or less - or 40 nanometres or less, depending on the configuration -, the ionisation energy has been found to be increased from 45 meV in bulk silicon to 100 meV, 150 meV, 200 meV or higher in the vicinity of an interface with a material with lower permittivity. Majority charge carriers thus have a significantly higher ionisation energy in thin layers, having doping regimes between 1016 and 1019 per cubic centimetre.

With an ionisation energy at this level, electromagnetic radiation in the middle- and far-infrared spectrum may be detected, i.e. with a wavelength of approximately 3 ym and up, to a level of 5 um, 6 um, 7 pm, 8 um, 9 pm, 10 pm, 15 pm or more. In some other embodiments, the spectrum to be detected may cover the near infrared, with a wavelength of 1 um, 1.5 pm, 2 pm or 2.5 pm and up, with a limit that may be as mentioned in the previous sentence.

A second aspect provides a circuit for detecting infrared radiation having light with a wavelength between 3 micron and 20 micron. The circuit comprises the semiconductor photo detector device according to the first aspect, a voltage source or a current source for providing a first of a voltage across the device or a current through the device, a monitoring module for monitoring a second of a voltage across the device or a current through the device. The circuit further comprises a processing module arranged to determine, from the monitored second of a voltage across the device or a current through the device, an intensity of electromagnetic radiation received by the semiconductor photo detector device.

A third aspect provides a method of manufacturing the semiconductor photo detector device according to the first aspect. The method comprises providing the first boundary layer having the second conductivity type and the second permittivity, providing, either on or in the first boundary layer, the semiconductor sensor layer having the sensor region having the first conductivity type and the first permittivity and providing the second boundary layer having the third conductivity type and the third permittivity on the sensor layer. In this third aspect, at least one of the second permittivity and the third permittivity is less than the first permittivity, the sensor region has a thickness of 20 nanometres or less if one of the second permittivity and the third permittivity is less than the first permittivity and the sensor region has a thickness of 40 nanometres or less if the second permittivity and the third permittivity are less than the first permittivity.

An embodiment of the third aspect, wherein the first boundary layer is a semiconductor bulk layer, the semiconductor bulk layer having a top surface, further comprises introducing dopant atoms in the semiconductor bulk layer, yielding a doped sensor region provided in the semiconductor bulk layer having the first conductivity type, based on the introduction, determining an initial distance between the top surface and a boundary between the semiconductor bulk layer with the first conductivity type and the sensor region, removing surface material from the top surface of the doped sensor region such that the distance between the top surface and the boundary between the semiconductor bulk layer with the first conductivity type and the sensor region is 20 nanometres or less; and providing the second boundary layer after removing the surface material.

BRIEF DESCRIPTION OF THE DRAWINGS The various aspects and implementations thereof will now be discussed in further detail with drawings. In the drawings, Figure 1: shows an implementation of a photo sensor; Figure 2 A: shows a first stage in manufacturing of a photo Sensor; Figure 2 B: shows a first stage in manufacturing of a photo sensor; Figure 2 C: shows a first stage in manufacturing of a photo Sensor; Figure 2 D: shows a first stage in manufacturing of a photo Sensor; Figure 2 E: shows a first stage in manufacturing of a photo Sensor; Figure 3: shows another implementation of a photo sensor; Figure 4: shows an implementation of a photo sensor with an optical module; and Figure 5: shows a circuit comprising a photo sensor.

DETAILED DESCRIPTION Figure 1 shows a photo sensor 100 as an implementation of the first aspect. The photo sensor 100 comprises a bulk layer 102, above which a sensor layer 104. In this implementation, the photo sensor 100 is manufactured in monocrystalline silicon; it may be implemented in other type IV, III-V or II-VI compound semiconductor substrates as well. In one implementation, the bulk layer 102 has an n-type doping, preferably arsenic or phosphorous, though indium or any other material suitable for doping of 5 silicon for establishing an n-type semiconductor may be used as well. The dopant level of the bulk layer is preferably in the order of 1016 atoms per cubic centimetre, but may in other embodiments be anywhere between 1012 and 1018. The sensor layer 104 has a p-type doping, preferably provided by insertion - implanting, diffusion or other - of boron, though epitaxial growth of the layer may be used as well, as well as other methods of chemical vapour deposition. The sensor layer may have a dopant level between 1016 to 1019 or even more dopant atoms per cubic centimetre. An advantage of deposition of the sensor layer 104 and chemical vapour deposition like epitaxy is that the thickness and doping level of the sensor layer 104 and the sensor region 122 in particular may be well controlled and no further steps like down etching may be required.

At the left side and the right side of the photo sensor 100, at the top, optionally, a first higher doped region 106 and a second higher doped region 106' are provided. Through the sensor layer 104 and the first higher doped region 106 and the second higher doped region 106, vertically in the orientation of Figure 1, a first doped contact region 108 and a second doped contact region 108' are provided. The higher doped regions 106 and the doped contact regions 108 have the same conductivity type as the sensor region 104, in this case p-type. The transition in doping level from the sensor layer 104 to the higher doped regions 106 is preferably a smooth and/or gradual and/or continuous transition, but may have a step function.

Above the higher doped regions 106, an insulating layer 112 is provided. The insulating layer 112 may be also a passivation layer or merely an electrically isolating layer. The insulating layer may comprise silicon dioxide, silicon nitride, spin-on polymer or spin-on glass, other, or a combination thereof. In the insulating layer, a contact hole is provided in order to contact the doped contact regions 108 by means of a first contact plug 114 and a second contact plug 114’. Optionally, a silicide may be provided between the doped contact regions 108 and the contact plugs 114". The contact plugs 114 may comprise any suitable material, including copper, tungsten, aluminium, other or a combination thereof.

The contact plugs 114 and the doped contact regions 108 are provided at a distance from one another, allowing light - that may be represented as photons, wavelets, waves, other or a combination thereof - to impinge on the sensor layer 104. The top of the sensor layer 104 may be covered by the insulating layer 112 or another protective layer. Such protective layer is to be transparent to light of the wavelength the photo sensor 100 is to detect or have such characteristics that light is attenuated to only a small degree, preferably less than 50%, more preferably less than 40%, 30%, 20%, 10% and even more preferably less than 5%.

At the bottom right of Figure 1, a detail of the boundary between the bulk layer 102 and the sensor layer 104 is shown. The upper half of the detail shows the sensor layer 104 and the lower half of the detail shows the bulk layer 102. As the bulk layer 102 has, in this implementation, an n-type doping and the sensor layer 104 has a p-type doping, depletion layer exists at the boundary between the bulk layer 102 and the sensor layer 104. The depletion layer comprises a sensor depletion region 124 and a bulk depletion region 126. The thicknesses of the depletion region depend on the doping levels of the semiconductor material on either side of the boundary, in the depletion layer and an optional voltage or potential difference between the bulk layer 102 and the sensor layer 104, creating an electric field over the boundary.

Above the depletion layer - in the orientation of Figure 1 - a sensor region 122 is provided. With given doping levels, the sensor region 122 may vary in thickness as a function of a voltage applied between the sensor layer 104 and the bulk layer 106. The sensor region 122 may also be limited within the sensor layer 104 at sides of the sensor region 122. The doping levels in the photo sensor 100 and the thickness of the sensor layer 104 are preferably provided such that with no voltage applied, the sensor region has a thickness of 20 nanometres of less, which thickness is indicated with the arrow 120 in Figure 1, of which the lower arrow point is also indicated in the detail at the lower right.

It is preferred to bias the Junction between the sensor region 122 and the bulk region 128 such that the junction is in reverse.

Such may be established if no bias -0V -is applied; alternatively, a particular voltage may have to be actively applied.

A bias provides a depletion layer as barrier between the sensor region and the bulk region 128, of which the thickness depends on the applied voltage between bulk and sensor region 122. This, in turn, allows the thickness of the sensor region 122 to be tuned, which allows also other properties thereof to be tuned, including, but not limited to spectral sensitivity and sensitivity in general.

In another embodiment, the bulk may be floating.

In the doping regimes referenced above and with the sensor region 122 having a thickness of 20 nanometres or less, conductivity of the sensor region 122 is at least partially and preferably dominantly or fully governed by hopping conduction.

This means that the ionisation energy of majority charge carriers is significantly higher than in bulk semiconductor material - for silicon about 45 meV.

Rather, with a sensor region having a thickness of 20 nanometres or less, the ionisation energy has been found to be about five times or more higher than in the bulk material.

Majority charge carriers thus have a significantly higher ionisation energy in thin layers having doping regimes between 1016 and 1019 per cubic centimetre.

This characteristic applies with the sensor region 122 and the bulk region 128 in which the sensor region 122 is provided predominantly comprising the same material, for example silicon, in which a small amount of dopant atoms are provided. Predominantly, within the context of this description and related to material, is to be understood as 99% or more comprising a single material or a material compound with a particular constitution of two, three, four or more ingredients, like silicon carbide, silicon germanium, any III-V or II-VI compounds, other, or a combination thereof. The further 1% - or less - may consist of deliberately introduced impurities to give the (compound) material specific electrical properties.

With the sensor region 122 being exposed to the ambient or the photo sensor 100 being provided with a finish layer being sufficiently transparent to light to be detected, the ionisation energy between about 0.1 eV and 0.4 eV allows for detection of light having wavelengths between 3 micron and 15 micron. Detection of such light in the mid and long infrared spectrum allows for detection and imaging of thermal radiation of objects and living beings like humans and other animals.

Figure 2 A through Figure 2 E depict an implementation of the third aspect. Figure 2 A shows a semiconductor substrate providing the bulk layer 102 with n-type doping as a first conductivity type. The dopant level of the bulk layer is preferably in the order of 106 atoms per cubic centimetre, but may be adapted to provide an optional concentration by picking a value between 1012 and 1018 per cubic centimetre. Figure 2 B shows formation of a top layer 142 having a second conductivity type. In this implementation, the top layer 142 has a p-type doping, preferably provided by insertion - implanting, diffusion or other - of boron, though epitaxial growth of the layer may be used as well, as well as other methods of chemical vapour deposition.

In the particular embodiment that chemical vapour deposition is used, the doping of the top layer 142 may be provided as substantially uniform over the full thickness of the top layer 142. Using insertion of dopant atoms, like diffusion or implantation, the doping level may vary over the thickness of the top layer 142. In the latter case, implantation of p-type doping atoms may result in a higher doped layer 106 and a lower doped sensor layer 104. The p-type dopant atoms - or donor atoms - are provided such that the sensor layer 104 preferably has a dopant level between 1016 to 1019 or even more dopant atoms per cubic centimetre.

Between the stage shown by Figure 2 B and the stage shown by Figure 2 C, an insulation layer 112 is inserted and in the insulation layer 112 and a first contact hole 144 and a second contact hole 144' have been provided through the insulation layer 112. Through the contact holes, optional highly doped contact regions 108 have been provided. With other parts of the photo sensor 100 covered by the insulating layer 112, implantation of dopant atoms only enter the top layer 142 through the contact holes 144, resulting in self-aligned doped contact regions 108. The doped contact regions 108 preferably have a conductivity type of the same type as that of the top layer 142 and the sensor layer 104 in particular.

Between the contact holes 144, a distance may be provided between hundreds of nanometres and hundreds of micrometres. The distance between the contact holes 144 may determine sensitivity of the photo sensor. In one implementation, the distance between the contact holes 144 is relatively small and an array of photo sensors 100 is provide on one and the same substrate, allowing for manufacturing of an image sensor for thermal emission.

Figure 2 D shows a first contact plug 114 and a second contact plug 114' having been formed. Optionally, a silicide may be provided between the doped contact regions 108 and the contact plugs 114’. The contact plugs 114 may comprise any suitable material, including copper, tungsten, aluminium, other or a combination thereof. The metal or equivalent electrically conductive material is deposited on the insulating layer 112 and in the contact holes 144’, for example by means of physical vapour deposition or another suitable method. The layer thus deposited is patterned, for example by means of photolithography and subsequent etching. In case the sensor layer 104 is manufactured using layer deposition techniques like chemical vapour deposition and epitaxy in particular, the contact plugs 114 may be provided directly on the sensor layer 104, optionally preceded by a masked or selective implant step for providing a higher doped region at the contact holes 144.

Figure 2 E shows the final photo sensor 100. Between the stage depicted by Figure 2 D and the stage depicted by Figure 2 E, a sensor opening 146 has been etched between the first contact 114 and the second contact 114. The sensor opening 146 may be provided by means of plasma etching or another preferably non-isotropic etching method - though isotropic etching, for example wet etching, may be used as well. With the etching, the higher doped layer 106 is removed and only the sensor layer 104 with a desired, lower, doping level is left. Furthermore, such etching also allows for manufacturing of a sufficiently thin sensor region 122 (Figure 1).

The sensor region 122 may be covered by a finish layer 118. The finish layer 118 is preferably transparent to the electromagnetic radiation to be detected (1 um to 20 um or a sub-interval thereof, as discussed above) or transmit at least 50%, 60%, 70%, 80%, 90%, 95% thereof to the sensor region 122. The finish layer 118 may be a passivation layer, passivating bonds at the upper surface of the sensor region 122. Alternatively, the finish layer 118 comprises an inactive material that merely covers the sensor region 122. It is preferred the finish layer 118 has a relatively low dielectric constant, preferably lower than that of silicon (relative permittivity of approximately 12), more preferred lower than that of silicon nitride (relative permittivity of approximately between 7 and 8) and even more preferred equal to or less than that of silicon dioxide (relative permittivity of approximately 4). The finish layer most preferably has a relative permittivity of 2 or less, which may be achieved using polymers, for example organic polymers.

In the implementations discussed above, top layer 142 has been discussed as being p-type doped as a second conductivity type and the bulk layer 102 being n-type doped as a first conductivity type. It is noted that both may be switched, i.e. the top layer 142 has an n-type doping and the bulk layer having a p-type doping. Figure 3 A shows another embodiment, with the first conductivity being an insulator and the second conductivity type being either n-type or p-type.

Figure 3 A shows a photo sensor 100 manufactured on a silicon on insulator substrate, with an insulator bulk layer 110 being provided between the top layer 142 and the bulk layer 102. The material of the insulating bulk layer 110 may be silicon oxide, silicon nitride, another oxide or any other equivalent sufficiently insulating material. The material of the insulating bulk layer 110 preferably has a permittivity lower than the permittivity of the material predominantly comprised by the top layer 142 and the sensor layer 104 in particular.

In the configuration as depicted by Figure 3 A, the top layer may be silicon, silicon carbide, germanium or another IV (compound) semiconductor, a III-V compound semiconductor, a II-VI compound semiconductor, other, or a combination thereof. On top of the top layer 142, a finish layer may be provided, as discussed in conjunction with Figure 2 E.

With the top layer 142 in the configuration having a permittivity higher than the insulating bulk layer 102 and higher than a finish layer provided on top of the sensor region 104, the sensor layer 104 may have a thickness of 40 nanometres or less, with the increased ionisation energy of the charge carriers still being maintained. A reason for this is that with the configuration of Figure 3 A as discussed above, the shortest distance between any point in the sensor layer 104 and a material - which may be a compound material - having a lower permittivity than that of the sensor layer 104 is less than 20 nanometres.

The photo sensor 100 as shown by Figure 3 A may be manufactured in a way equivalent to the procedure as depicted by Figure 2 A through Figure 2 E.

If the top layer 142 as provided on the insulator bulk layer 110 is thin enough - 20 nanometres or less - the etching step between Figure 2 D and Figure 2 E may be omitted, as depicted by Figure 3 B. In such case, the doping of the sensor layer 104 is preferably still between 1016 and 1019 dopant atoms per cubic centimetre, preferably in a substantially uniform way, with doping levels within the layer not varying more than two orders of magnitude and more preferably varying not more than one order of magnitude.

As discussed above, the photo sensor 100 may be covered by protective, preferably insulating, layer, as long as the covering layer is sufficiently transparent to any light that is to be detected. In further implementations, the photo sensor 100 may be provided with optical elements arranged to shape or direct impinging light in a particular way. Figure 4 shows a photo sensor 100 as another implementation of the first aspect. The photo sensor 100 comprises at least most elements as discussed in conjunction with other implements discussed above. It is noted that the photo sensor 100 as depicted by Figure 4 may also be implemented on a buried insulating layer, like a nitride or oxide layer.

The photo sensor 100 of Figure 4 comprises, on top of the sensor layer 104, an light guide module 130 as an optical module. In this implementation, the light guide module 130 comprises multiple layers of a first type 132 and a second type 134. By providing the light guide module 130, a waveguide may be provided to guide Light to the sensor layer 104. Also the silicon itself on the insulator may function as a waveguide. This may remove a need to have the photo sensor 100 exposed directly to the light source, which may be undesirable in case of impurities or extreme heat mn an environment in which the photo sensor 100 is to acquire data.

Additionally or alternatively, the optical module may be implemented as one or more lenses. Such lens may be used to focus impinging light and/or to spread impinging light more evenly over the area at which the sensor layer 104 is exposed. In such implementation, but also in other implementations, the optical module may be implemented having only one or more than two different types of layers, in any number possible in view of required functionality, ranging from one layer, two layers, three layers, four layers to any larger number of layers.

Figure 5 shows a circuit 500 for determining whether light impinges on the photo sensor 100. The circuit 500 may comprises the photo sensor 100 and comprises a voltage source 502, a current sensor 504 and a processing unit 506. The processing unit 506 may control the voltage over the photo sensor 100. If light impinges on the photo sensor 100 and light having a photon energy similar to that of excitation energy of majority carriers of the sensor region of the photo sensor 100, majority carriers are excited. The impinging light may ionise the charge carrier directly or indirectly. With direct ionisation, the photon energy is directly transferred to the charge carrier to 10nise the charge carrier. With indirect ionisation, the photon energy is absorbed by the material of the photo sensor 100 (like the sensor region 122) and the thermal energy thus available ionises charge carriers.

These majority carriers form a current, under influence of the voltage applied. The processing unit 506 is arranged to determine, based on voltage applied and current sensed, what the intensity is of the Light 1mpinging on the photo sensor 100. Alternatively, a current may be applied to the photo sensor and a voltage is sensed and processed.

In summary, a photodetector is provided for sensing radiation in middle and long wave infrared domain. The sensor has a sensor layer of a first material having a first conductivity type and a first permittivity in which the shortest distance of any point in the sensor layer to an adjacent layer having a second conductivity type and a second permittivity lower than the first permittivity is 20 nanometres or less. Conductivity type may be semiconductor n-type or p-type or insulator. If, for example, a silicon sensor layer 1s sandwiched between two silicon oxide layers, the sensor layer of preferably p-type semiconductor has a maximum thickness of 40 nanometres. If a p-type layer of a first material is sandwiched between a dielectric layer with the second permittivity and an n-type layer of the first material, the maximum thickness is 20 nanometres. Spaced apart, two contacts are provided in contact with the sensor layer.

Various implementations of the various aspects may be summarised by means of the following, not limitative list of numbered examples:

1. Semiconductor photo detector device for detecting electromagnetic radiation having a wavelength between 1 micrometre and micrometres, preferably between 3 micrometre and 15 micrometre, the device comprising: - a semiconductor sensor layer having a sensor region having a first conductivity type and a first permittivity; - a first terminal for providing a first electrical contact to 20 the sensor region; - a second terminal for providing a second electrical contact to the sensor region, the second electrical contact being spaced away from the first electrical contact; - a first boundary layer having a second conductivity type and a second permittivity provided at a first side of the sensor layer; and - a second boundary layer having a third conductivity type and a third permittivity provided at a second side of the sensor layer, the second side being opposite to the first side; Wherein:

- at least one of the second permittivity and the third permittivity is less than the first permittivity; - the sensor region has a thickness of 20 nanometres or less if one of the second permittivity and the third permittivity is less than the first permittivity; and - the sensor region has a thickness of 40 nanometres or less if the second permittivity and the third permittivity are less than the first permittivity.

2. Semiconductor photo detector device according to example 1, wherein the first conductivity type is a p-type conductivity.

3. Semiconductor photo detector device according to example 2, wherein the sensor region is doped with boron.

4. Semiconductor photo detector device according to any of the examples 2 to 3, wherein the dopant concentration in the sensor region 1s between 1016 cm-3 and 1013 cm.

5. Semiconductor photo detector device according to example 4, wherein the dopant concentration in the sensor region is between 1013 cm’? and 8 1013 cm’.

6. Semiconductor photo detector device according to any of the preceding examples, wherein the first boundary layer predominantly comprises a semiconductor material and the second conductivity type is of an n-type.

7. Semiconductor photo detector device according to any of the examples 1 to 5, wherein the second conductivity type is an insulator.

8. Semiconductor photo detector device according to any of the preceding examples, wherein the distance between the first contact and the second contact is between 1 and 102 micrometres.

9. Semiconductor photo detector device according to any of the examples 1 to 6 and 8, wherein the first boundary layer and the sensor layer predominantly comprise silicon.

10. Semiconductor photo detector device according to any of the preceding examples, further comprising an optical element for forming light impinging on the photo detector.

11. Circuit for detecting infrared radiation having light having a wavelength between 3 micron and 15 micron, the circuit comprising: - the semiconductor photo detector device according to any of the preceding examples; - a voltage source or a current source for providing a first of a voltage over the device or a current through the device; - a monitoring module for monitoring a second of a voltage over the device or a current through the device; and - a processing module arranged to determine, from the monitored second of a voltage over the device or a current through the device, an intensity of radiation received by the semiconductor photo detector device.

12. Method of manufacturing the semiconductor photo detector device according to any of the example 1 to 10, comprising: - providing the first boundary layer having the second conductivity type and the second permittivity; - providing, either on or in the first boundary layer, the semiconductor sensor layer having the sensor region having the first conductivity type and the first permittivity; and - providing the second boundary layer having the third conductivity type and the third permittivity on the sensor layer; Wherein: - at least one of the second permittivity and the third permittivity is less than the first permittivity;

- the sensor region has a thickness of 20 nanometres or less if one of the second permittivity and the third permittivity is less than the first permittivity; and - the sensor region has a thickness of 40 nanometres or less if the second permittivity and the third permittivity are less than the first permittivity.

13. Method according to example 12, wherein the first boundary layer is a semiconductor bulk layer, the semiconductor bulk layer having a top surface; the method further comprising: - introducing dopant atoms in the semiconductor bulk layer, yielding a doped sensor region having the first conductivity type provided in the semiconductor bulk layer having the second conductivity type; - Based on the introduction, determining an initial distance between the top surface and a boundary between the semiconductor bulk layer with the second conductivity type and the sensor region; - Removing surface material from the top surface of the doped sensor region such that the distance between the top surface and the boundary between the semiconductor bulk layer with the second conductivity type and the sensor region is 20 nanometres or less; and - providing the second boundary layer after removing the surface material.

14. Method according to example 13, comprising: - Providing a introduction window for locally introducing dopant atoms for forming the sensor region; - Providing the dopant atoms through the introduction window.

15. Method according to example 13 or 14, comprising:

- Providing a removal window; and - removing the surface material through the removal window.

16. Method according to example 15 to the extend dependent on example 14, wherein the introduction window and the removal window are one and the same.

17. Method according to any of the example 13 through 16, further comprising: - applying a first terminal for providing a first electrical contact to the sensor region; and - applying a second terminal for providing a second electrical contact to the sensor region, the second electrical contact being spaced away from the first electrical contact.

18. Method according to example 17, wherein the surface material is removed after application of the terminals.

In the description above, it will be understood that when an element such as layer, region or substrate is referred to as being “on” or “onto” another element, the element is either directly on the other element, or intervening elements may also be present. Also, it will be understood that the values given in the description above, are given by way of example and that other values may be possible and/or may be strived for.

The various aspects may be implemented in hardware, software or a combination thereof. The data to be processed may be digital or analogue or a combination thereof. In case analogue data is provided or received and digital data is required for processing, analogue to digital conversion may be used and subsequently, the digital data is processed.

Furthermore, the invention may also be embodied with less components than provided in the examples described here, wherein one component carries out multiple functions. Just as well may the invention be embodied using more elements than depicted in the Figures, wherein functions carried out by one component in the example provided are distributed over multiple components.

It is to be noted that the figures are only schematic representations of examples of the invention that are given by way of non- limiting examples. For the purpose of clarity and a concise description, features are described herein as part of the same or separate examples, however, it will be appreciated that the scope of the invention may include examples having combinations of all or some of the features described. The word ‘comprising’ does not exclude the presence of other features or steps than those listed in a claim. Furthermore, the words 'a' and 'an' shall not be construed as limited to ‘only one’, but instead are used to mean 'at least one’, and do not exclude a plurality.

A person skilled in the art will readily appreciate that various parameters and values thereof disclosed in the description may be modified and that various examples disclosed and/or claimed may be combined without departing from the scope of the invention.

It is stipulated that the reference signs in the claims do not limit the scope of the claims, but are merely inserted to enhance the legibility of the claims.

Claims

ConclusiesConclusions

1. Halfgeleider fotodetectorapparaat voor detecteren van elektromagnetische staling met een golflengte tussen 1 micrometer en 20 micrometer, bij voorkeur tussen 3 micrometer en 15 micrometer, het apparaat omvattende: - een halfgeleider sensorlaag omvattende een sensorgebied omvattende met een eerste geleidingstype en een eerste permittiviteit; - een eerste aansluiting om te voorzien in een eerste elektrische contact met het sensorgebied; - een tweede aansluiting om te voorzien in een tweede elektrisch contact met het sensorgebied, welke tweede elektrisch contact op afstand van het eerste elektrisch contact is voorzien; - een eerste grenslaag met een tweede geleidingstype en een tweede permittiviteit voorzien aan een eerste zijde van de sensorlaag; en - een tweede grenslaag met een derde geleidingstype en een derde permittiviteit voorzien aan een tweede zijde van de sensorlaag, welke tweede zijde tegenover de eerste zijde ligt; Waarbij: - ten minste een van de tweede permittiviteit en de derde permittiviteit lager is dan de eerste permittiviteit; - het sensorgebied een dikte van 20 nanometer of minder heeft als een van de eerste permittiviteit en de derde permittiviteit lager is dan de eerste permittiviteit; en - het sensorgebied een dikte van 40 nanometer of minder heeft als de eerste permittiviteit en de derde permittiviteit lager zijn dan de eerste permittiviteit.A semiconductor photodetector device for detecting electromagnetic radiation with a wavelength between 1 micrometer and 20 micrometers, preferably between 3 micrometers and 15 micrometers, the device comprising: - a semiconductor sensor layer comprising a sensor region having a first conductivity type and a first permittivity; - a first terminal for providing a first electrical contact with the sensor region; - a second terminal for providing a second electrical contact with the sensor region, the second electrical contact being provided remote from the first electrical contact; - a first boundary layer with a second conductivity type and a second permittivity provided on a first side of the sensor layer; and - a second boundary layer with a third conductivity type and a third permittivity provided on a second side of the sensor layer, which second side is opposite the first side; Where: - at least one of the second permittivity and the third permittivity is lower than the first permittivity; - the sensor region has a thickness of 20 nanometers or less if one of the first permittivity and the third permittivity is less than the first permittivity; and - the sensor region has a thickness of 40 nanometers or less if the first permittivity and the third permittivity are less than the first permittivity.

2. Halfgeleider fotodetectorapparaat volgens conclusie 1, waarbij het eerste geleidingstype een p-type halfgeleider geleiding is.The semiconductor photodetector device according to claim 1, wherein the first conductivity type is a p-type semiconductor conduction.

3. Halfgeleider fotodetectorapparaat volgens conclusie 1, waarbij het sensorgebied is gedoteerd met boor.The semiconductor photodetector device of claim 1, wherein the sensor region is doped with boron.

4. Halfgeleider fotodetectorapparaat volgens een van de conclusies 1 en 2, waarbij de doteringsconcentratie in de sensorlaag tussen 1016cm-3 en 10%em3 ligt.The semiconductor photodetector device according to any one of claims 1 and 2, wherein the doping concentration in the sensor layer is between 1016 cm -3 and 10% em 3 .

5. Halfgeleider fotodetectorapparaat volgens conclusie 4, waarbij de doteringsconcentratie in de sensorlaag tussen 1018cm en 8 10:3cm’? ligt.The semiconductor photodetector device of claim 4, wherein the dopant concentration in the sensor layer is between 1018cm and 10:3cm' ? lies.

6. Halfgeleider fotodetectorapparaat volgens een van de voorgaande conclusies waarbij de eerste grenslaag in hoofdzaak een halfgeleidermateriaal omvat en het tweede geleidingstype n-type halfgeleider geleiding is.A semiconductor photodetector device according to any one of the preceding claims, wherein the first boundary layer substantially comprises a semiconductor material and the second conductivity type is n-type semiconductor conduction.

7. Halfgeleider fotodetectorapparaat volgens een van de conclusies 1 tot en met 5, waarbij het tweed geleidingstype een isolator is.The semiconductor photodetector device according to any one of claims 1 to 5, wherein the second conductivity type is an insulator.

8. Halfgeleider fotodetectorapparaat volgens een van de voorgaande conclusies, waarbij de afstand tussen het eerste contact en het tweede contact tussen 1 en 102 micrometer is.A semiconductor photodetector device according to any one of the preceding claims, wherein the distance between the first contact and the second contact is between 1 and 102 micrometers.

9. Halfgeleider fotodetectorapparaat volgens een van de conclusies 1 tot en met 6 en 8, waarbij de tweede grenslaag en de sensorlaag in hoofdzaak silicium omvatten.The semiconductor photodetector device according to any one of claims 1 to 6 and 8, wherein the second boundary layer and the sensor layer mainly comprise silicon.

10. Halfgeleider fotodetectorapparaat volgens een van de voorgaande conclusies, verder omvattende een optisch element voor vormen van elektromagnetische straling die op de fotodetector valt.The semiconductor photodetector device according to any one of the preceding claims, further comprising an optical element for forming electromagnetic radiation impinging on the photodetector.

11. Circuit voor detecteren van infrarode straling met een golflengte tussen 3 en 15 micrometer, het circuit omvattende: - het halfgeleider fotodetectorapparaat volgens een van de voorgaande conclusies; - een spanningsbron of een stroombron voor leveren van een eerste van een spanning over het apparaat of een stroom door het apparaat; - een waarnemingsmodule voor waarnemen van een tweede van een spanning over het apparaat of een stroom door het apparaat; - een verwerkingseenheid ingericht om te bepalen, op basis van de waargenomen tweede van de spanning over het apparaat of een stroom door het apparaat, een intensiteit van infrarode staling ontvangen door het halfgeleider fotodetectorapparaat.Circuit for detecting infrared radiation having a wavelength between 3 and 15 micrometers, the circuit comprising: - the semiconductor photodetector device according to any one of the preceding claims; - a voltage source or a current source for supplying a first of a voltage across the device or a current through the device; - a sensing module for sensing a second of a voltage across the device or a current through the device; - a processing unit arranged to determine, based on the sensed second of the voltage across the device or a current through the device, an intensity of infrared radiation received by the semiconductor photodetector device.

12. Werkwijze voor vervaardigen van een halfgeleider fotodetectorapparaat volgens een van de conclusies 1 tot en met 10, omvattende: - voorzien in een eerste grenslaag met het tweede geleidingstype en de tweede permittiviteit; - voorzien, op of in de eerste grenslaag, de halfgeleider sensorlaag omvattende het sensorgebied met het eerste geleidingstype en de eerste permittiviteit; en - voorzien, van de tweede grenslaag met het derde geleidingstype en de derde permittiviteit op de sensorlaag; Waarbij:A method of manufacturing a semiconductor photodetector device according to any one of claims 1 to 10, comprising: - providing a first boundary layer having the second conductivity type and the second permittivity; - providing, on or in the first boundary layer, the semiconductor sensor layer comprising the sensor region with the first conductivity type and the first permittivity; and - providing the second boundary layer with the third conductivity type and the third permittivity on the sensor layer; At which:

- ten minste een van de eerste en de tweede permittiviteit en de derde permittiviteit lager is dan de eerste permittiviteit; - het sensorgebied een dikte van 20 nanometer of minder heeft als een van de eerste permittiviteit en de derde permittiviteit lager is dan de eerste permittiviteit; en - het sensorgebied een dikte van 40 nanometer of minder heeft als de eerste permittiviteit en de derde permittiviteit lager zijn dan de eerste permittiviteit.- at least one of the first and second permittivity and the third permittivity is lower than the first permittivity; - the sensor region has a thickness of 20 nanometers or less if one of the first permittivity and the third permittivity is less than the first permittivity; and - the sensor region has a thickness of 40 nanometers or less if the first permittivity and the third permittivity are less than the first permittivity.

13. Werkwijze volgens conclusie 12, waarbij de eerste grenslaag een halfgeleider bulklaag is, welke halfgeleider bulklaag een bovenoppervlak omvat; - de werkwijze verder omvattende: - introduceren van doopatomen in de halfgeleider bulklaag, wat een gedoteerd sensorgebied met een eerste geleidingstype oplevert in de halfgeleider bulklaag met een tweede geleidingstype; - op basis van de introductie, bepalen van een initiéle afstand tussen het bovenoppervlak en een grens tussen de halfgeleider bulklaag met het eerste geleidingstype en het sensorgebied; - verwijderen van oppervlaktemateriaal van het bovenoppervlak van het gedoteerde sensorgebied zodanig dat de afstand tussen het bovenoppervlak en de grens tussen de halfgeleider bulklaag met het tweede geleidingstype en de sensorlaag met het eerste geleidingstype 20 nanometer of minder is; - voorzien van de tweede grenslaag na verwijderen van het oppervlaktemateriaal.The method of claim 12, wherein the first boundary layer is a semiconductor bulk layer, the semiconductor bulk layer including a top surface; - the method further comprising: - introducing doping atoms into the semiconductor bulk layer, yielding a doped sensor region with a first conductivity type in the semiconductor bulk layer with a second conductivity type; - on the basis of the introduction, determining an initial distance between the upper surface and a boundary between the semiconductor bulk layer of the first conductivity type and the sensor region; - removing surface material from the top surface of the doped sensor region such that the distance between the top surface and the boundary between the second conductivity type semiconductor bulk layer and the first conductivity type sensor layer is 20 nanometers or less; - provided with the second boundary layer after removal of the surface material.

14. Werkwijze volgens conclusie 13, omvattende: - voorzien van een introductievenster voor lokaal introduceren van doopatomen voor vormen van het sensorgebied;Method according to claim 13, comprising: - providing an introduction window for locally introducing doping atoms to form the sensor region;

- voorzien van de doopatomen door het introductievenster.- provided with the baptismal atoms through the introduction window.

15. Werkwijze volgens conclusie 13 of 14, omvattende: - Voorzien van een verwijderingsvenster; en - verwijderen van het oppervlaktemateriaal door het verwijderingsvenster.A method according to claim 13 or 14, comprising: - Provided with a removal window; and - removing the surface material through the removal window.

16. Werkwijze volgens conclusie 15 voor zover afhankelijk van conclusie 14, waarbij het introductievenster en het verwijderingsvenster hetzelfde zijn.The method of claim 15 when dependent on claim 14, wherein the introduction window and the deletion window are the same.

17. Werkwijze volgens een van de conclusies 12 tot en met 16, verder omvattende: - aanbrengen van een eerste aansluitpunt voor voorzien in een eerste elektrisch contact aan het sensorgebied; en - aanbrengen van een tweede aansluitpunt voor voorzien in een tweede elektrische contact aan het sensorgebied, welk tweede elektrisch contact op afstand is van het eerste elektrisch contact.A method according to any one of claims 12 to 16, further comprising: - applying a first terminal for providing a first electrical contact to the sensor region; and - providing a second terminal for providing a second electrical contact to the sensor region, the second electrical contact being spaced from the first electrical contact.

18. Werkwijze volgens conclusie 17 voor zover afhankelijk van conclusie 13, waarbij het oppervlaktemateriaal wordt verwijderd na aanbrengen van de aansluitpunten.The method of claim 17 when dependent on claim 13, wherein the surface material is removed after application of the terminals.

19. Werkwijze volgens conclusie 12 of 17 voor zover afhankelijk van conclusie 12, waarbij de eerste grenslaag in hoofdzaak een kristalstructuur heeft en waarbij aanbrengen van de halfgeleider sensorlaag chemische dampdepositie van materiaal omvat.The method of claim 12 or 17 when dependent on claim 12, wherein the first boundary layer has substantially a crystal structure and wherein application of the semiconductor sensor layer comprises chemical vapor deposition of material.

20. Werkwijze volgens conclusie 19, waarbij de chemische dampdepositie het epitaxiaal groeien van de sensorlaag omvat.The method of claim 19, wherein the chemical vapor deposition comprises epitaxially growing the sensor layer.