Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
  • G01N1/44—Sample treatment involving radiation, e.g. heat
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
  • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
  • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
  • G01N21/3563—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing solids; Preparation of samples therefor
• • 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
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/67005—Apparatus not specifically provided for elsewhere
  • H01L21/67242—Apparatus for monitoring, sorting or marking
  • H01L21/67253—Process monitoring, e.g. flow or thickness monitoring

Definitions

• the invention relates to a method for determining oxygen or carbon in semiconductor material by means of gas fusion analysis (gas fusion analysis,
• the GFA is a method that is used in particular to quantitatively determine oxygen or carbon in a measurement sample made of semiconductor material.
• the measurement sample is melted, containing oxygen or
• Analytical systems for determining oxygen or carbon in silicon for solar cells are available on the market (S. Sakakura, “Determination of Oxygen and Carbon of Silicon for Solar Cells”, Readout, English Edition No.14, pages 66-69, February 2011) .
• the two elements are determined by means of GFA, whereby separate apparatuses with different measuring processes are required, which involve complex, multi-stage cleaning of the crucible and the measuring sample.
• the cleaning of the measurement sample is intended to remove foreign material on the surface of the measurement sample, so that it is ensured that the subsequently determined
• the object is achieved by a method for determining oxygen or carbon in semiconductor material by means of gas fusion analysis, comprising
• Measurement sample is inductively heated in a gas stream with the same composition and melted in the crucible, and oxygen contained in the measurement sample with
• Carbon or carbon contained in the measurement sample is reacted with oxygen to form at least one oxidation product, the amount of which is determined and used as a measure of the oxygen or carbon contained in the measurement sample.
• the invention it is provided to clean the crucible and the measurement sample at the same time by inductively heating the measurement sample lying in the crucible and, if appropriate, the crucible itself to a temperature of at least 1300 ° C. in a gas stream consisting of nitrogen or a mixture of nitrogen and at least an inert gas, for example a mixture of nitrogen and argon.
• a gas stream consisting of nitrogen or a mixture of nitrogen and at least an inert gas, for example a mixture of nitrogen and argon.
• nitrogen impurities containing oxygen or carbon can be removed comparatively easily from the surface of the measurement sample, so that the measurement result is not falsified by foreign material adhering to the surface.
• the presence of nitrogen causes nitriding of the semiconductor material, which causes the diffusion of
• Semiconductor material that does not have sufficient intrinsic conductivity because it is not or only weakly doped it is preheated to a temperature of, for example, 300 ° C. to 500 ° C., for example by means of radiation from a halogen lamp.
• the measurement sample is supplemented with semiconductor material which has sufficient intrinsic conductivity and whose content of oxygen and carbon is known and, according to Dilution in the volume of the measurement sample is low compared to the expected content of the measurement sample.
• the known carbon content added by the supplement is preferably less than 10% of the expected carbon content of the measurement sample.
• the specific electrical resistance of the semiconductor material added as a supplement is preferably not more than 0.5 ohmcm. Afterwards, such a measurement sample can also be easily inductively heated to the target cleaning temperature. If the crucible is made of carbon, none of this is required
• the crucible is also inductively heated and, in the course of this, the measurement sample inside is preheated
• the measurement sample is preferably heated to a temperature at which the measurement sample begins to melt on the surface.
• the temperature of the measurement sample can be measured without contact, for example, using an IR thermometer.
• the duration of the cleaning depends in particular on the weight of the measurement sample and the degree of contamination of the crucible and can be determined empirically, for example. For this purpose, measurement samples are cleaned over different periods of time and their surfaces are examined after cleaning.
• the crucible and the measurement sample are cleaned outside the measuring device, in which the content of oxygen or carbon is determined.
• they are transported into the measuring device under protective gas, for example argon.
• protective gas for example argon.
• Cleaning of the crucible and the measurement sample is carried out in the measuring device (in situ cleaning), in which the determination of the oxygen or carbon content in the measurement sample is carried out after the cleaning.
• This has the advantage that the measurement sample no longer has to be cooled and transported before the determination of the oxygen content or the carbon content begins.
• oxygen which adheres to the test sample as a foreign substance in a bound form, is reacted with carbon to form at least one oxidation product such as carbon monoxide.
• This oxidation product is expediently analyzed, if appropriate after oxidation to carbon dioxide, by means of infrared spectrometry or another gas analysis method.
• the concentration of oxygen on the surface of the measurement sample can be determined.
• Measurement signal which indicates the presence of the oxidation product, has returned to this lower threshold after initially exceeding a predefined lower threshold.
• the measurement sample is preferably no longer cooled before its oxygen content or its carbon content is determined.
• the measurement sample lying in the crucible is inductively heated and melted in a gas stream, the composition of which corresponds to that of the gas stream during the cleaning of the crucible and the measurement sample.
• Oxygen contained in the measurement sample is reacted with carbon or carbon contained in the interior of the measurement sample is reacted with at least one oxidation product.
• Oxidation product optionally after oxidation to carbon dioxide, is preferably analyzed by means of infrared spectrometry and the concentration of oxygen or carbon in the measurement sample is determined.
• Another gas analysis method can be used in infrared spectrometry, for example a gas analysis method in which a WLD detector (thermal conductivity detector) is used.
• WLD detector thermo conductivity detector
• the choice of the material of the crucible depends on whether it is intended to determine the oxygen content or the carbon content in the measurement sample. If the oxygen content of the measurement sample is intended to be determined, the crucible consists of carbon, in the other case of oxidic ceramic. In the case of determining the oxygen content, the crucible holder consists of oxygen-free material, preferably an insert made of boron nitride. In the case of using a crucible made of carbon, the crucible is cleaned during the cleaning of the crucible and the measurement sample and heated inductively during the determination of the oxygen content in the measurement sample itself.
• the measurement sample preferably consists of silicon or a semiconductor material which contains silicon, for example silicon germanium.
• the semiconductor material is preferably single crystal or polycrystalline.
• the semiconductor material can be doped with one or more electrically active dopants.
• FIG. 1 schematically shows a measuring device which is suitable for carrying out the method according to the invention.
• a crucible 1 in which a measurement sample lies, is arranged in a measuring chamber 2 on a crucible holder 3.
• the crucible holder 3 is preferably made of a material whose structure is free of oxygen and free of carbon.
• the crucible holder 3 preferably consists of boron nitride.
• Measuring chamber 2 is designed to melt the measurement sample in a defined gas flow, which contains nitrogen, in the crucible 1.
• a line 4 is provided which is connected to a gas supply 5.
• the measuring device 100 comprises an inductive heating device 6, which in the
• Measuring chamber 2 which is suitably shielded from the outside
• alternating electromagnetic field is generated, by means of which the measurement sample in the crucible 1 can be heated and melted.
• the crucible 1 and the measurement sample lying therein are cleaned in the gas stream.
• the measurement sample and optionally the crucible 1 are heated inductively.
• a halogen lamp 7 can be provided, by means of which a light beam illustrated in dashed lines can be irradiated through a transparent window 8 to the measurement sample in order to be able to preheat the measurement sample to a temperature which enables the measurement sample to be heated further inductively.
• the measurement sample After cleaning the crucible and the measurement sample contained therein, the measurement sample is melted by means of the inductive heating device 6, oxygen and carbon reacting to form at least one oxidation product.
• This oxidation product is passed via a line 9 to a detector unit 10.
• the gas of the line 9 is passed through a measuring cell 11, which is irradiated by a measuring beam from a suitable source 12, for example an infrared light source.
• a suitable source 12 for example an infrared light source.
• the measuring beam strikes a detector 13 in the measuring cell 11, by means of which a detector signal can be obtained and evaluated in an evaluation device (not shown).
• the Evaluation device determines a content of the at least one oxidation product in the gas of line 9 and in this way allows the determination of the
• Oxygen content or carbon content in the measurement sample is Oxygen content or carbon content in the measurement sample.

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• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)

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Citations (2)

• 2018
  • 2018-09-12 DE DE102018215482.1A patent/DE102018215482A1/de active Pending
• 2019
  • 2019-07-22 WO PCT/EP2019/069666 patent/WO2020052838A1/de active Application Filing
  • 2019-08-29 TW TW108130988A patent/TWI716090B/zh active

Patent Citations (2)

Non-Patent Citations (4)

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