Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
  • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
  • G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
  • G01B11/0625—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating with measurement of absorption or reflection
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
  • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
  • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
  • G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
  • G01B11/0658—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating with measurement of emissivity or reradiation
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/22—Measuring arrangements characterised by the use of optical techniques for measuring depth
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
  • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
  • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
  • H01L21/76898—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics formed through a semiconductor substrate

Definitions

• the invention relates to a method of analysing an optoelectronic device or luminescent layer(s) using fluorescence radiation and an apparatus therefore.
• spectroscopic ellipsometry Several methods for determining the thickness of thin films are known. These include atomic force microscopy (AFM), profilometry, scanning electron microscopy (SEM), spectroscopic ellipsometry and spectroscopic reflexion or transmission methods.
• the microscopic methods are invasive as the samples need to be destroyed and cannot be used after measurement.
• Methods using spectroscopic ellipsometry as well as reflection or transmission methods are non-invasive, but usually consider only one spot or line within a manufacturing line.
• application to larger areas at once (thickness imaging) is neither very common with these methods, nor is the contrast very high.
• German Patent Application No DE 10 2004 037555 Al teaches a method of non-destructive testing of a photocatalytic surface coating, such as found on roof tiles.
• the object to be tested is placed in a test chamber and irradiated with UV light.
• the reflected radiation is captured by an imaging device and converted to a grey scale or artificial colour image and compared with a reference to establish the thickness of the coating.
• the thickness determination from fluorescent radiation enables a higher contrast between excitation light and detection light, as the excitation light and detection light can be in completely different spectral ranges.
• EP 1 348 945 Al Another method for measuring the thickness of an organic thin film is known from European Patent Application No. EP 1 348 945 Al which teaches the illumination of an organic electroluminescence device with a UV light and then measuring the intensity of fluorescence produced by the electroluminescence device. The thickness of the thin film is obtained from the intensity of the fluorescence by a comparison with reference coatings.
• the method of this disclosure comprises a method for analysing an optoelectronic device comprising one or more fluorescing element(s) in at least one layer within a layer stack.
• the method comprises illuminating an area of a surface of the optoelectronic device, collecting fluorescent radiation from the fluorescing element(s), and comparing the collected fluorescent radiation with simulated values to produce an analysis.
• the analysis enables, for example, the laterally resolved thickness of the luminescent layer within a layer stack to be determined.
• the method of this disclosure can be used in-line in a manufacturing plant or in a test plant on which the optoelectronic devices are continuously produced on a roll or in which the optoelectronic devices are placed on transport belts and tested.
• the method can be carried out on the layer directly after manufacture, i.e. before it is covered with an electrode or another layer. It is possible to use the method, however, when the layer - referred to later as the luminescent layer - has been covered by futher transparent layers, such as a transparent electrode. The simulated values must take this additional transparent layer (or layers) into account.
• the method uses UV to visible radiation for excitation and the fluorescing elements generate fluorescing radiation (fluorescence or luminescence) which typically has a wavelength from 250 nm to 1800 nm.
• the method comprises a further step of illuminating the area of the surface of the optoelectronic device with radiation at a different angle of incidence; and collecting the further fluorescent radiation from the area to produce a further analysis.
• the combination of both analyses provides a more accurate result.
• An apparatus for analysis of the optoelectronic device comprises a first illumination device for illuminating the optoelectronic device and a first detector for collecting fluorescent radiation from the one or more fluorescing elements.
• a processor is used for comparing the collected fluorescent radiation from the detector with a simulation based on the optical properties of the single layer or of a layer stack which includes the fluorescent/luminescent layer to produce the analysis.
• the optoelectronic device is moved through the illumination device, for example on a transport belt or on a self-supporting substrate.
• the analysis can also be done on resting samples.
• the analysis can reveal problems with the manufacture of devices or films, for example, when the measured thickness of the layer is different than the specified value of the layer.
• a real-time continuous monitoring of the thickness of the layer enables adjustments to be made quickly and efficiently to the manufacturing process if issues with layer thicknesses are established.
• the analysis can also reveal problems with the manufacture of device or films, for example, when the local signal shows deviations beyond a threshold, which can be used for indicating defects in such layers.
• Fig. 1 shows an example of the apparatus.
• Fig. 2 shows a flow chart of the method.
• Fig. 3 shows the measured components of the refractive index.
• Fig. 4 shows the absorption of incoming UV radiation at depth.
• Fig. 5 shows spectrum of incoming UV radiation.
• Fig. 6 shows calculated number of excitons against thickness.
• Figs. 7A and 7B shows the emission against thickness.
• Figs. 8 A and 8B show two results.
• Fig. 1 shows an example of the apparatus 10 for the analysis of an optoelectronic device 20 with a photoactive layer 25.
• the photoactive layer 25 is shown as the uppermost layer in Fig. 1, but may be part of a layer stack and may, indeed, be buried within the layer stack.
• the term photoactive layer is used in a general sense in this document to include any layer that reacts to incoming photons and includes, for example, the emissive layer in OLEDs.
• the apparatus 10 comprises a first illumination source 30, such as a UV to visible light source (e.g. simply an LED), and a first radiation detector 40.
• the radiation detector 40 is connected to a computer system, including a processor 50 which has a storage area 60 for storage of simulated data.
• the illumination source 30 typically produces radiation at wavelengths in the range of 200 nm to 600 nm.
• the radiation detector 40 detects fluorescent radiation, for example, in the range of 600nm to 1100 nm.
• Typical ones of the radiation detectors 40 are GaAs detectors which detect radiation in the range of 800 nm to 1700 nm and Si detectors which detect in the range of 300 nm to 1100 nm. It will be realised, however, that these values are not limiting of the invention.
• the optoelectronic device 20 could be, for example, a plurality of photonic devices, such as but not limited to an array of organic light emitting diodes.
• the organic LEDs are shown as elements 22 in the optoelectronic device 20.
• Fig. 2 shows a flow diagram for the implementation of the method.
• a simulation of the expected fluorescent intensity as function of photoactive layer thickness is earned out.
• This simulation is carried out in the processor 50 and is stored, for example, in the storage area 60 and will be required at a later stage for comparison with the experimental data acquired at a later stage.
• the simulation is carried out based on previously determined complex index of refraction of the photoactive layer 25 and all other layers penetrated by the excitation light of the optoelectronic device 20.
• This complex index of refraction includes both the real component as well as the imaginary component.
• the photoluminescent spectrum 1( ⁇ ) and the number of excitons n from the fluorescent elements in the photoactive layer 25 can then be calculated for example based on coherent light propagation and absorption processes within a multi-layer stack by the transfer matrix formalism.
• This calculation depends on a number of factors. These factors include the absorption of the photons from the illumination source 30 in the photoactive layer 25, which will be a function of the wavelength and the depth within the photoactive layer 25. It will also be appreciated that some of the excitons producted from the absorbed photons will recombine non-radiatively in the photoactive layer 25 and others will emit photons from the photoactive layer 25, but not all of the emitted photons will be detected as fluorescent radiation in the radiation detector 40. The calculation gives the relative number of photons detected by the radiation detector 40. The total amount of fluorescent radiation will be a function of the strength of the incoming excitation light.
• An area of the upper surface 25 of the optoelectronic device 20 is illuminated in step 210 and one or more the photonic devices 22 in the upper surface 25 will emit fluorescent radiation in step 215.
• the emitted fluorescent radiation is collected by the radiation detector 40 in step 220 with a certain quantum yield, as discussed above, and compared in step 230 with the simulated values to produce an analysis.
• the illumination source 30 can illuminate the area of the upper surface 25 at a different angle of incidence in step 210 and the further fluoresced radiation is collected in a further radiation detector 40' in step 240.
• the second radiation source 30' illuminates the area of the upper surface 25.
• Fig. 3 shows the modelled components n and k of the complex refractive index for a conjugated polymer layer based on evaluation of for example transmission and reflection spectra. It is possible to calculate the spectral absorption of the incoming illumination using the Fresnel equations, in dependence on the thickness d of the photoactive layers / layer stack 25, the depth z and the wavelength ⁇ of the illumination and this is shown in Fig. 4. [0030] The convolution of the absorbed amount of photons with the spectrum of incoming illumination (shown in Fig. 5) leads to the calculation of the number N of generated excitons, shown in Fig. 6, against thickness.
• Figs. 7A and 7B The total number of emitted photons (thus the integral over spectrum and depth of the photoactive layer) against photoactive layer thickness is then given in Figs. 7A and 7B.
• This fluorescence-photoactive layer thickness correlation can be inverted to give the results shown in Figs. 7A and 7B which can be stored in the look-up table. It will be seen that between 140 nm and 250 nm there is a risk of miscalculation. This risk can be eliminated by either making additional measurements at a different angle of incidence or by making the assumption that there is no "jump" (discontinuity) between adjacent areas in which the thickness d can be calculated and the areas in which there is more than one possible value of the thickness.
• Figs. 8A and 8B shows two comparative results for the measurements for a nominal thickness of 60 nm (Fig. 8A) and 64 nm (Fig 8B) in which the intensity of photoluminescence is shown (top one of figures) against calculated photoactive layer thickness (bottom one of figures).

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Manufacturing & Machinery (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
• Electroluminescent Light Sources (AREA)
• Length Measuring Devices By Optical Means (AREA)

Priority Applications (2)

Applications Claiming Priority (1)

Publications (1)

Family

ID=57868195

Family Applications (1)

Country Status (2)

Citations (6)

• 2016
  • 2016-12-31 WO PCT/EP2016/002197 patent/WO2018121832A1/en active Application Filing
  • 2016-12-31 DE DE112016007568.5T patent/DE112016007568T5/de not_active Withdrawn

Patent Citations (7)

Also Published As

Similar Documents

Legal Events