WO1997029517A2 - Detecteur de rayonnement ultraviolet - Google Patents

Detecteur de rayonnement ultraviolet Download PDF

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Publication number
WO1997029517A2
WO1997029517A2 PCT/CH1997/000025 CH9700025W WO9729517A2 WO 1997029517 A2 WO1997029517 A2 WO 1997029517A2 CH 9700025 W CH9700025 W CH 9700025W WO 9729517 A2 WO9729517 A2 WO 9729517A2
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Prior art keywords
photodiode
layer
semiconductor layer
conductivity type
photolithography
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PCT/CH1997/000025
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German (de)
English (en)
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WO1997029517A3 (fr
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Daniel Bolliger
Piero Malcovati
Pasqualina Sarro
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Laboratorium Für Physikalische Elektronik
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Publication of WO1997029517A2 publication Critical patent/WO1997029517A2/fr
Publication of WO1997029517A3 publication Critical patent/WO1997029517A3/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/1443—Devices controlled by radiation with at least one potential jump or surface barrier
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0216—Coatings
    • H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/02162—Coatings for devices characterised by at least one potential jump barrier or surface barrier for filtering or shielding light, e.g. multicolour filters for photodetectors

Definitions

  • the invention relates to a radiation detector which is particularly suitable for the detection of ultraviolet (UV) radiation, and a method for producing the same, according to the preambles of the independent claims.
  • UV ultraviolet
  • Ultraviolet-sensitive radiation detectors made from semiconductor materials, in particular from silicon, are known. They are used, for example, in flame monitoring in combustion plants. Common to all is the pursuit of high spectral selectivity, i. H. after a high sensitivity at those UV wavelengths for which the emission of a burner flame is high, and after a low sensitivity at the other wavelengths. If this requirement is met, only the burner flame is actually monitored and extraneous light in the combustion chamber does not cause false signals.
  • EP-296 371 tries to achieve a high photodiode sensitivity in the wavelength range between 200 nm and 400 nm by limiting the depth of the effective sensor volume. It is known (cf. S. Sze, "Physics of Semiconductor Devices", Wiley, New York, 1981) that the majority of UV radiation penetrating into silicon is absorbed in silicon after a penetration depth of 10 nm. In contrast, the penetration depth of longer-wave light (in the visible and infrared spectral range) is orders of magnitude greater, so that it is practically not absorbed in the thin sensor volume near the surface and does not contribute to the output signal. The depth of the effective sensor volume is limited by means of an additional potential threshold built into the silicon in a special manufacturing step. Additional optical absorption and interference filters as well as lenses in front of the photodiode can further improve the spectral sensitivity and selectivity.
  • the photocurrents of the UV radiation detector disclosed in EP-296 371 are very small, typically 1 pA to 1 nA. This makes the UV radiation detector sensitive to external electromagnetic interference. It is therefore necessary to install a signal amplifier very close to the photodiode. This can be achieved with many discrete components, for example in the patent specification CH-680 390. However, this increases the assembly effort and the arrangement is complex; in addition, with such a detector, the electrical connection paths between the individual components are long and therefore prone to failure.
  • EP-579 045 the photodiode and the evaluation electronics are integrated on the same chip. Such an integration brings with it the problem that the UV photodiode with a limited depth of the active sensor volume requires a special manufacturing process which is incompatible with processes used in the manufacture of integrated circuits (IC). For this reason, bipolar transistors and resistors must be developed and used for the evaluation electronics.
  • EP 579 045 solves this problem by coupling doping values and layer thicknesses of the photodiode and the transistors to one another, ie using the same doped semiconductor layers for the photodiode and transistors at the same time.
  • EP-579 045 also has the disadvantage that it uses special electronic elements such as special bipolar transistors or high-impedance resistors which cannot be produced using standard processes.
  • the maximum sensitivity is at a wavelength of 310 nm. This is a serious disadvantage when used in flame monitoring. With a conventional arrangement of a flame detector in a fire system, it cannot be ruled out that extraneous light will fall into the combustion chamber. Sunlight in particular can have a greater intensity at 310 nm than the burner flame; Even light from fluorescent tubes can cover the flame signal at 310 nm. Thus, the above-mentioned UV radiation sensors would have to be operated in complete darkness and could only be used with great uncertainty in industrial burners into which stray light penetrates.
  • EP-579 045 also has the disadvantage that unfiltered scattered light can fall onto the UV photodiode and the transistors without hindrance. In this way, parasitic currents are generated in the photodiode and in the transistors, which are still powerful be reinforced. External light in the combustion chamber leads to a large error signal.
  • EP-579 045 Another disadvantage of EP-579 045 is the very long response time of up to 2.5 s of the electrical evaluation circuit. This makes the UV radiation detector disclosed therein unsuitable for flame monitoring in firing systems, since the risk that a flame failure will not be registered quickly enough and fuel will continue to be fed into the hot combustion chamber unburned for seconds poses a great security risk represents.
  • the photodiode and the evaluation electronics should be integrated on one chip; however, the semiconductor layers, which are used on the one hand for the photodiode and on the other hand for the transistors, should be able to be produced in a decoupled manner, so that a separate optimization of the UV sensor and the transistors is achieved without mutual impairment.
  • the maximum sensitivity of the UV radiation detector should be at a wavelength below 250 nm, so that it is insensitive when used as a flame monitor on scattered radiation from the sun and artificial light sources.
  • the sensitive spectral band should be adjustable in the manufacturing process.
  • a bipolar standard process is used, as is customary in the manufacture of ICs.
  • the evaluation electronics are produced with such a standard process.
  • the photodiode is produced in a few additional additional steps that are shifted between the standard process steps.
  • the manufacture of the photodiode is consequently decoupled from that of the evaluation electronics. Both components can therefore be optimized independently of one another in such a way that each individual component exhibits ideal behavior.
  • the manufacturing method according to the invention is divided into method steps such that structures produced in previous method steps are not significantly impaired by the process variants and / or process temperatures used in one method step.
  • the additional steps inserted into the standard process are the following: use of a thin TEOS oxide with a very low thermal budget, which is compatible with the bipolar transistors previously produced in standard process steps; Implantations of the photodiode layers; Contacting method for a thin PN junction with implanted polysilicon; two step etching process for the Opening the contact window; Adaptation of standard bipolar transistors; brief annealing of the photodiode layers without changing the properties of the bipolar transistors.
  • Basing on a standard process has great advantages.
  • the evaluation electronics circuit uses a feedback-controlled differential amplifier with load current at both inputs and adjustable step response time.
  • a constant input current is added to the photocurrent in an input stage;
  • the total current and the constant input current are amplified by an essentially identical amplification factor and converted into voltages, the difference of which serves as the output voltage. Only standard elements are used for the evaluation electronics.
  • UV radiation detector can be efficiently shielded from stray light by applying a second metallization to its surface with the exception of the active sensor surface.
  • Interference filters directly on the active sensor surface and / or absorption filters in front of the photodiode additionally improve the spectral selectivity.
  • FIG. 1 shows a schematic cross section through a photodiode according to the invention
  • FIG. 3 shows schematic electronic band structures in the photodiode according to FIG. 1,
  • FIG. 6 shows a schematic cross section through a contact window produced using a two-stage etching process according to the invention
  • FIG. 8 shows an electrical circuit diagram of a differential amplifier of an amplifier according to the invention.
  • FIGS. 1, 4 and 5 show an electrical circuit diagram of a feedback-controlled differential amplifier according to the invention.
  • individual elements of FIGS. 1, 4 and 5 are not drawn to scale in the vertical direction.
  • the same vertical and horizontal scales are not used in FIGS. 1, 4, 5 and 6.
  • a photodiode and an evaluation circuit are integrated in a single integrated circuit on the same chip.
  • schematic cross sections through exemplary embodiments of photodiode and transistors are shown separately in FIGS. 1 and 4 and 5.
  • the integrated circuit is located on a surface of a generally doped semiconductor substrate and essentially consists of semiconductor layers which differ in their position, geometry and doping with different charge carriers of different concentrations.
  • FIG. 1 shows a schematic cross section through an embodiment of a photodiode 1 according to the invention.
  • a UV radiation detector according to the invention can be used with one or even with several such photodiodes be equipped.
  • a semiconductor substrate 2 is preferably doped so that it belongs to the first conductivity type P;
  • the semiconductor substrate 2 is one having an impurity concentration of 10 14 -10 17 cm -3, preferably 5 "10 1S cm" 3, doped monocrystalline, preferably ⁇ 100> oriented, silicon wafer.
  • a first, structured semiconductor layer 4 of the second conductivity type N + a so-called buried layer 2, on the semiconductor substrate 2.
  • the entire surface 3 of the semiconductor substrate 2 is covered with a second semiconductor layer 5 of the second conductivity type N, preferably one 3.5 ⁇ m thick epitaxial layer made of monocrystalline silicon doped with a concentration of IO 16 cm "3 .
  • Connection regions 6 of the second conductivity type N + connect the buried layer 4 to the surface 7 of the epitaxial layer 5.
  • the photodiode 1 essentially consists of a sequence of differently doped structured semiconductor layers in the epitaxial layer 5.
  • a first photodiode semiconductor layer 9 of the first conductivity type P lies at a depth of approximately 800 to approximately 350 nm below the surface 7 of the Epitaxial layer 5.
  • a second photodiode semiconductor layer 10 of the second conductivity type N + adjoins it and ranges from approximately 350 nm to approximately 100 nm.
  • a third photodiode semiconductor layer 11 of the first conductivity type P + lies directly below the surface 7 of the epitaxial layer 5 and is approximately 100 nm thick.
  • the three photodiode semiconductor layers 9-11 are interleaved: at their edge, the first photodiode semiconductor layer 9 extends to the surface 7 of the epitaxial layer 5, so that the second photodiode semiconductor layer 10 on the surface 7 in the first photodiode half - layer 9 is arranged;
  • the first and second photodiode semiconductor layers 9 and 10 have connection regions 12 and 13 of the first conductivity type P + and the second semiconductor type N, respectively Mistake.
  • first, structured oxide layer 14 On the surface 7 of the epitaxial layer 5 there is a first, structured oxide layer 14 outside the photodiode 1 and in the area of the photodiode 1 a second, structured oxide layer 15, which are interrupted in particular in the connection regions 12, 13, so that contact windows are formed .
  • a first, structured metal layer 16 on the first and second oxide layers 14 and 15 forms a conductor system with corresponding contacts in the connection regions 12, 13; it is preferably 600 nm thick and preferably consists of aluminum with approximately 1% silicon.
  • a third, structured oxide layer 17 separates the first metal layer 16 from a second, structured metal layer 18.
  • the second metal layer 18 is preferably 600 nm thick and preferably consists of aluminum with approximately 1% silicon.
  • a 150-400 nm thick, preferably 200 nm thick polycrystalline silicon layer 19 of the first conductivity type P + essentially forms the connection region 20 of the third photodiode semiconductor layer 11. It prevents 16 metal tips from being deposited by the extraordinarily thin third layer when the first metal layer 16 is applied Photodiode semiconductor layer 11 penetrate (“spiking") and form undesirable short-circuits of the PN junction between the third and second photodiode semiconductor layers 10 and 11. There are no metal layers above the actual photodiode 1, so that there an entry window 21 (only partially shown in FIG. 1) enables the access of electromagnetic radiation 22 to be detected to the photodiode 1.
  • the entrance window 21 can be provided with an interference filter 23 which only allows a desired part of the electromagnetic spectrum, for example UV radiation with wavelengths between 200 nm and 250 nm, to pass.
  • an interference filter 23 which only allows a desired part of the electromagnetic spectrum, for example UV radiation with wavelengths between 200 nm and 250 nm, to pass.
  • Methods for calculating such interference filters 23 are known per se (cf. B. Baltes, D. Bradley, "Interference filters for the far ultraviolet (1700 ⁇ to 2400 ⁇ )", Appl. Opt. 5, 971-975 (1966)) .
  • the transmission of the interference filter 23 can be matched to the desired spectral band, ie the wavelength at which the UV radiation detector has its maximum sensitivity can be set during manufacture.
  • an interference filter 23 for the wavelength of 310 nm can consist of a sequence of the following layers listed in the direction of incidence of the light: 37.5-42.5 nm, preferably 40.0 nm, SiO 2 ; 12.5-17.5 nm, preferably 15 nm, Al; 70-76 nm, preferably 72.5 nm, SiO ,; 17-23 nm, preferably 19.8 nm, Al; 68-98 nm, preferably 83 nm, Si0 2 .
  • This coating of the entry window 21 also serves to protect the photodiode 1 from external influences.
  • An additional, suitably chosen absorption filter 24, which is attached in front of the entrance window 21, can additionally increase the spectral selectivity of the UV radiation detector.
  • FIG. 2 shows schematically doping concentrations C (logarithmically plotted) in the photodiode 1 along the line II-II shown in broken lines in FIG. 1, as a function of the depth d.
  • line 25 means the concentration of charge carriers of the first conductivity type P
  • line 26 the concentration of charge carriers of the second conductivity type N
  • the line 27 the concentration of charge carriers of the first conductivity type P + .
  • the individual regions 5, 9, 10, 11 and 19 correspond to the first, second and third photodiode semiconductor layers or the polycrystalline silicon layer.
  • FIG. 3 schematically shows the electronic band structures in the photodiode along the line II-II shown in dash-dot lines in FIG. 1, ie electrical potentials E as a function of the depth d.
  • the line E v corresponds to the valence band, the line E c to the conduction band; E F represents the Fermi level.
  • a potential barrier 28 in the region of the second photodiode semiconductor layer 10 is clearly recognizable.
  • Electromagnetic radiation 22 incident through the entrance window 21 is absorbed in the semiconductor materials and generates charge carriers. If the corresponding semiconductor material belongs to the first conductivity type P, the majority carriers are holes and the minority carriers are electrons, and vice versa.
  • a course of the band structures, as shown in FIG. 3, is a direct consequence of the doping profiles shown in FIG. 2 and has the following two advantages.
  • the band structure contributes to the spectral selectivity of the photodiode.
  • selectivity is achieved by the potential barrier 28 for holes and electrons caused by the second and third photodiode semiconductor layer, which limits the depth of the active sensor volume.
  • This limitation means that practically only UV radiation with its small penetration depth (typically 10 nm or less in silicon) contributes to the photodiode output signal, but longer-wave electromagnetic radiation with greater penetration depths does not.
  • Charge carriers that are generated beyond the potential barrier 28 can This is because they do not cross barrier 28 and therefore do not contribute to the photodiode output signal.
  • the charge carriers are locally separated from one another by the band structure shown in FIG. 3 before they can recombine.
  • the greatest doping concentration is in the second oxide layer 15 above the photodiode 1; the holes drift toward the boundary between the third photodiode semiconductor layer 11 and the second oxide layer 15 because of the internal electric field, while the electrons move in the opposite direction.
  • the doping concentrations and the band structures in the region of the entry window 21 are qualitatively similar to those in FIGS. 2 and 3.
  • FIGS. 4 and 5 show bipolar transistors which are known per se and can be produced using the method according to the invention on the same semiconductor substrate 2. They have the buried layer 4 already described on the occasion of FIG. 1 with a connection region 6, the epitaxial layer 5 and an insulation ring 8. Analogously to the photodiode 1 in FIG. 1, the bipolar transistors are covered with a first oxide layer 14 with contact windows, a first metal layer 16, a third oxide layer 17 and a second metal layer 18.
  • FIG. 5 shows a vertical bipolar transistor 29, for example of the NPN
  • the epitaxial layer 5 acts as a collector, the buried layer 4 reducing the collector resistance.
  • the base is covered by an approximately 200 nm thick, structured transistor semiconductor layer 30 of the first guide.
  • Ability type P formed with a connection region 31.
  • the emitter is formed by a second, structured transistor semiconductor layer 32 of the second semiconductor type N.
  • FIG. 6 shows a lateral bipolar transistor 33, for example of the PNP type.
  • collector 34 and emitter 35 are formed analogously to the base connection region 31 of the vertical bipolar transistor from FIG. 5.
  • the epitaxial layer 5 acts as a base.
  • a semiconductor substrate 2 with a surface 3 is assumed.
  • a doped semiconductor substrate 2 is selected which belongs to the first conductivity type P, for example one with a foreign atom concentration of 10 14 -10 17 cm “3 , preferably 5" 10 15 cm “3 , doped with boron or phosphorus, Preferably ⁇ 100> -oriented silicon wafer with a polished surface 3.
  • the method according to the invention essentially consists of the following process steps carried out in succession: a) pretreatment of one surface 3 of the semiconductor substrate 2, b) production of bipolar transistors 29, 33 and parts of at least one photodiode 1 over this surface 3 of the semiconductor substrate 2, c) production of at least one photodiode 1 by successively implanting different ions with energies determining the depth of the implantation by means of appropriately structured photoresist layers and d) producing contact windows for contacting transistors 29, 33 and photodiode 1 and manufacture of a conductor system.
  • the pretreatment of the surface 3 of the semiconductor substrate 2 comprises the production of the buried layer 4 and the epitaxial layer 5, the production of the insulation rings 8 and the connections 6 and the deposition of the first oxide layer 14; it is known per se. There are some process steps with high temperatures, typically over 1000 ° C.
  • the buried layer 4 is a first semiconductor layer of the second conductivity type N +, structured by means of photolithography, and is preferably produced by means of ion implantation, for example of antimony ions, and then annealed at approximately 1200 ° C.
  • the second semiconductor layer 5 of the second conductivity type N is preferably deposited by means of epitaxy and is, for example, an arsenic-doped single-crystalline silicon layer with an arsenic concentration of approximately IO 16 cm "3.
  • the insulation rings 8 of the first conductivity type P + and the connections 6 of the second Conductivity type N + are defined by means of photolithography and produced by implantation and diffusion of foreign atoms.
  • the first oxide layer 14 is preferably deposited thermally at a temperature of approximately 1000 ° C., so that it has a thickness of approximately 330 nm.
  • the base connection regions 31 are preferably first produced, then the bases 30 themselves and then the emitters 32. Simultaneously with the corresponding transistor elements, connection regions 12, 13 of the photo diode are produced in the method according to the invention.
  • the base connection regions 31 and the photodiode connection regions 12 of the first semiconductor type P + are preferably made by implanting boron ions using a correspondingly structured photoresist layer made.
  • the bases 30 of the first conductivity type P are preferably produced by implanting boron ions through a correspondingly structured photoresist layer.
  • a previously structured oxide mask which can be formed by the suitably structured first oxide layer 14, is preferably required; arsenic ions are preferably implanted through these.
  • the dopants are activated and tempered in a chemically inert environment, preferably for 10-90 minutes at 900-1250 ° C. in an argon environment.
  • collectors 34 and emitters 35 of the first conductivity type P + are produced analogously to the manufacture of the base connection regions 31 in the vertical bipolar transistors 29.
  • the active photodiode region is first defined by producing a window in the first oxide layer 14 by means of photolithography and etching. Then a second oxide layer 15 applied as an implant oxide. This is preferably done by deposition of a 10-40 nm thick tetraethyl orthosilicate (TEOS) oxide layer using the gravure chemical vapor depositon process, for example at 700 ° C. for 4 minutes.
  • TEOS oxide layer 15 has the advantage that it can be manufactured with a low thermal budget.
  • the three photodiode semiconductor layers 9-11 of the photodiode 1 are preferably produced in succession from the first, deepest, to the third photodiode semiconductor layer lying directly below the surface of the epitaxial layer 5.
  • the implantation energies determine the depth, the implanted ions the conductivity type and the surface density the concentration of the layers 9-11.
  • ions of the first conductivity type for example boron ions with a surface density of 10 12 -10 14 cm "2 , preferably 3-10 13 cm " 2 , and an energy of 120-300 keV are used. preferably 170 keV implanted.
  • ions of the second conductivity type are used, for example phosphorus ions with a surface density of 10 12 -5 "10 14 cm “ 2 , preferably 3 "10 13 cm “ 2 , and with an energy of 90-250 keV , preferably 170 keV, implanted.
  • ions of the first conductivity type for example boron ions with a surface density of 5 "10 13 -5" 10 15 cm “2 , preferably 1.5" IO 14 cm '2 , and with an energy of 4- 12 keV, preferably 8 keV, implanted.
  • contact windows are produced at the contact points provided. This is done by means of photolithography and etching of the oxide layers 14, 15 present in each case at the contact points provided.
  • electrical contacting of the third photodiode semiconductor layer 11 is prepared.
  • the second oxide layer 15 is removed from the provided contact points by means of photolithography and etching.
  • a 150-400 nm thick, preferably 200 nm thick, polycrystalline silicon layer 19 is deposited by means of gravure chemical vapor deposition methods over the photo diode 1 or also over the entire surface of the processed semiconductor substrate.
  • Ions of the first conductivity type P + are implanted at the intended contact points through a photoresist layer, for example boron ions with a surface density of 10 14 -5 "10 15 cm “ 2 , preferably IO 15 cm “2 , and with an energy of 20-50 keV, preferably 25 keV.
  • the resulting high doping concentration at the transition from the polycrystalline silicon layer 19 to the monocrystalline semiconductor permits low-resistance contact to the third photodiode semiconductor layer 11, which is only about 100 nm thick, without impairing its doping profile at the transition to the second photodiode semiconductor layer 10. Thereafter, if necessary, the polycrystalline silicon layer 19 is removed by means of photolithography and etching outside the photo diode 1.
  • the thermal budget of which is such that the existing doping profiles do not diffuse out.
  • a first annealing step the processed semiconductor substrate is annealed for 10-200 minutes, preferably 20 minutes, at 550-750 ° C., preferably 600 ° C., in a chemically inert environment, preferably an Ar environment.
  • a second annealing step the processed semiconductor substrate is annealed for 3-20 s, preferably for about 5 s, at 900-1200 ° C, preferably at 970 ° C, in a chemically inert environment, preferably in an N 2 environment .
  • the polycrystalline silicon layer 19 acts as a diffusion barrier and effectively prevents bring the first metal layer 16 metal tips through the extraordinarily thin third photodiode semiconductor layer 11 ("spiking") and undesired short-circuits of the PN junction between the third photodiode semiconductor layer 11 and the second photodiode semiconductor layer 10 form.
  • the doping ratios allow low-resistance contacting of the third photodiode semiconductor layer 11.
  • Etching contact windows at the locations at which the first oxide layer 14 and the second oxide layer 15 are located one above the other with known, simple etching processes would have major disadvantages.
  • a strong under-etching of the second oxide layer is observed with wet etching.
  • dry etching leads to a rough contact surface, which results in an unacceptably high contact resistance.
  • a new, two-stage etching process is used in the manufacturing method according to the invention. In a first etching step, dry etching is carried out, for example for about 30 seconds. In a second etching step, the remaining oxide (approx. 20 nm to 50 nm) is wet-etched away.
  • FIG. 6 shows a schematic cross section through a contact window produced with the two-stage etching process according to the invention at a stage in which photoresist 36 has not yet been removed.
  • a first metal layer 16 is applied to the processed surface, preferably an approximately 600 nm thick layer of aluminum and 1% silicon by means of cathode sputtering at approximately 300 ° C.
  • This first metal layer 16 is structured by means of photolithography and etching.
  • a third oxide layer 17 is deposited on the processed surface, preferably 800 nm by means of plasma deposition at 350 ° C.
  • This third oxide layer 17 can be structured by means of photolithography and etching.
  • the second metal layer 18 is applied over the third oxide layer 17, preferably an approximately 1400 nm thick layer of aluminum and 1% silicon by means of cathode sputtering at approximately 300 ° C.
  • This second metal layer 18 can also be structured by means of photolithography and etching.
  • the processed semiconductor substrate is annealed at approximately 350-500 ° C., preferably at 400 ° C., in a chemically inert environment.
  • An interference filter 23 with maximum transmission around the wavelength of 310 nm can be produced, for example, by first reducing the oxide 15, 17 remaining on the active sensor surface by means of photolithography and etching to 68-98 nm, preferably 83 nm becomes.
  • the processed semiconductor substrate is annealed for 10-60 minutes, preferably 15 minutes, at 350-500 ° C., preferably 400 ° C., in a chemically inert environment, preferably in an N 2 environment.
  • Other layer combinations which lead to interference filters 23 with different transmission properties are possible.
  • the evaluation electronics should on the one hand be able to process the electrical signal supplied by the photodiode 1 and on the other hand be able to be produced by the described production method.
  • the photocurrents I Ph supplied by the photodiode 1 according to the invention are in the picoampere range; the bipolar transistors 29, 33 described above and manufactured using the method according to the invention are, however, suitable for less small currents. Therefore, a constant input current I Bl is symmetrically added to the photocurrent I Pn in the evaluation electronics; the bipolar transistors 29, 33 can thus be operated at their optimum operating point.
  • FIG. 7 shows an exemplary embodiment of an input stage 37 of the evaluation circuit according to the invention. It allows good electrical isolation of the photodiode 1 from the electronic components of the UV radiation detector even at higher temperatures.
  • the real photodiode 1 is schematically divided into an ideal UV photodiode in FIG. Iode 1.1, which is only sensitive to ultraviolet electromagnetic radiation, and a parasitic IR photodiode 1.2, which is sensitive to visible and IR radiation.
  • the constant input current I Bj is fed into each of three identical input branches 38-40. Only the constant input current I Bl flows in a first input branch 38.
  • a second input branch 39 is connected to the anodic side of the ideal UV photodiode 1.1. There the UV photocurrent I Ph is added to the constant input current I Bi .
  • a third input branch 40 the cathodic currents of the two photodiodes are added to the constant input current I Bl and led to earth; the anodic current of the IR photodiode is also led to earth.
  • Three identical transistors Q u , Q 13 and Q 15 are kept at the same base-emitter voltage by a constant voltage V Bi .
  • the constant input current I Bl flows in a first output branch 41 of the input stage 37, while the total current I Bl + I Pn flows in a second output branch 42. These currents are fed into a differential amplifier 43.
  • FIG. 8 An exemplary embodiment of a differential amplifier 43 of the evaluation circuit according to the invention is shown in FIG. 8; it is a totally symmetrical two-stage differential amplifier 43.
  • the two input currents are conducted through two input branches 44, 45 into the differential amplifier 43. There they are multiplied by the factors ß 16 and ß 18 or ß 19 and ß 20 .
  • FIG. 9 shows a circuit diagram of an exemplary embodiment of an evaluation circuit according to the invention. It consists of the input stage 37, an amplifier 46 and a feedback loop / current source 47.
  • the two currents amplified in the differential amplifier 43 are combined with one in the amplifier 46
  • Factor K is reflected in the transistors Q 24 and Q 23 and finally converted into voltages by resistors R 3 and R 2 , the difference V 0 of which serves as the output voltage.
  • V 0 ß 16 ß 18 KR 3 I Ph ; V 0 is therefore independent of the input current I Bi .
  • the feedback loop / current source 47 feeds the correct input current I Bi back into the amplifier 46.
  • the charge carriers which must charge the junction capacitance of the photodiode 1 of typically 2.7 nF, are supplied by both the input current I Bj and the photocurrent I Pn .
  • the input current I Bi in the large The order of a few nanoamperes is much larger than the photocurrent I Ph in the order of a few picoamperes.
  • the circuit must be modified slightly. Such modifications are easy for the person skilled in the art to make and are also part of the invention.

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Abstract

Dans un détecteur de rayonnement ultraviolet, une photodiode (1) et un dispositif électronique d'évaluation comportant des transistors bipolaires (29, 33) sont intégrés sur un substrat à semi-conducteur (2). Les couches à semi-conducteur utilisées pour la photodiode (1) et celles utilisées pour les transistors bipolaires (29, 33) sont fabriquées séparément, ce qui permet une optimisation des différents composants. L'électronique d'évaluation est fabriquée suivant les étapes standard de fabrication de circuits intégrés, tandis que la fabrication de la photodiode (1) comporte des étapes intermédiaires supplémentaires. La photodiode (1) est constituée de trois couches à semi-conducteur intercalées (9-11) ayant des types de conductivité différents, disposées à l'intérieur d'une couche épitaxiale (5) sur le substrat à semi-conducteur (2). Les couches de la photodiode (9-11) sont, au niveau de fenêtres de contact traversant toutes les couches d'oxyde (14, 15, 17), en contact avec une première couche métallique structurée (16), qui constitue un système conducteur. Une seconde couche métallique (18) protège les composants électroniques du rayonnement électromagnétique. Un filtre d'interférence (23) et/ou un filtre d'absorption (24) augmente la sensibilité spectrale.
PCT/CH1997/000025 1996-02-05 1997-01-28 Detecteur de rayonnement ultraviolet WO1997029517A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH294/96 1996-02-05
CH29496 1996-02-05

Publications (2)

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WO1997029517A2 true WO1997029517A2 (fr) 1997-08-14
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EP3229278A1 (fr) * 2016-04-07 2017-10-11 ams AG Dispositif de détection et procédé de fabrication associé

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EP0296371A1 (fr) * 1987-06-22 1988-12-28 Landis & Gyr Business Support AG Photodétecteur pour l'ultraviolet et procédé de fabrication
EP0353509A1 (fr) * 1988-08-04 1990-02-07 Siemens Aktiengesellschaft Procédé de fabrication d'un dispositif à semi-conducteur intégré comprenant un élément photosensible et un transistor bipolaire du type npn dans un substrat en silicium
EP0408276A2 (fr) * 1989-07-10 1991-01-16 Texas Instruments Incorporated Attaque sèche de vias dans un circuit intégré en couches
EP0579045A1 (fr) * 1992-07-16 1994-01-19 Landis & Gyr Technology Innovation AG Dispositif comportant une photodiode intégré sélective à la couleur et un amplificateur connecté à la photodiode
US5410175A (en) * 1989-08-31 1995-04-25 Hamamatsu Photonics K.K. Monolithic IC having pin photodiode and an electrically active element accommodated on the same semi-conductor substrate

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JP3394101B2 (ja) * 1993-11-02 2003-04-07 東京エレクトロン株式会社 半導体装置の製造方法

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EP0296371A1 (fr) * 1987-06-22 1988-12-28 Landis & Gyr Business Support AG Photodétecteur pour l'ultraviolet et procédé de fabrication
EP0353509A1 (fr) * 1988-08-04 1990-02-07 Siemens Aktiengesellschaft Procédé de fabrication d'un dispositif à semi-conducteur intégré comprenant un élément photosensible et un transistor bipolaire du type npn dans un substrat en silicium
EP0408276A2 (fr) * 1989-07-10 1991-01-16 Texas Instruments Incorporated Attaque sèche de vias dans un circuit intégré en couches
US5410175A (en) * 1989-08-31 1995-04-25 Hamamatsu Photonics K.K. Monolithic IC having pin photodiode and an electrically active element accommodated on the same semi-conductor substrate
EP0579045A1 (fr) * 1992-07-16 1994-01-19 Landis & Gyr Technology Innovation AG Dispositif comportant une photodiode intégré sélective à la couleur et un amplificateur connecté à la photodiode

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3229278A1 (fr) * 2016-04-07 2017-10-11 ams AG Dispositif de détection et procédé de fabrication associé
WO2017174798A1 (fr) * 2016-04-07 2017-10-12 Ams Ag Dispositif capteur et procédé de fabrication d'un dispositif capteur

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