CN116678845A - Silicon wafer oxygen content determination method and device - Google Patents

Silicon wafer oxygen content determination method and device Download PDF

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Publication number
CN116678845A
CN116678845A CN202310636160.4A CN202310636160A CN116678845A CN 116678845 A CN116678845 A CN 116678845A CN 202310636160 A CN202310636160 A CN 202310636160A CN 116678845 A CN116678845 A CN 116678845A
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silicon wafer
sample
oxygen content
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temperature
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金铉洙
徐永帅
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Xian Eswin Silicon Wafer Technology Co Ltd
Xian Eswin Material Technology Co Ltd
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Xian Eswin Silicon Wafer Technology Co Ltd
Xian Eswin Material Technology Co Ltd
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    • 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
    • G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
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    • 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
    • G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
    • 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
    • G01N1/32—Polishing; Etching
    • 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
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
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    • C30B29/06—Silicon
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    • 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
    • G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
    • G01N2001/2866—Grinding or homogeneising
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract

The disclosure provides a method and a device for measuring the oxygen content of a silicon wafer, wherein the method comprises the following steps: slicing the monocrystalline silicon rod to obtain a plurality of silicon wafers; treating the surface of the silicon wafer, removing pollutants on the surface of the silicon wafer and reducing the surface roughness; cutting a silicon wafer into a plurality of samples; putting a sample with an oxide film formed on the surface into a reaction chamber, wherein the oxide film contains oxygen elements; heating the sample in the reaction chamber in a first stage to decompose the oxide film on the surface of the sample and remove oxygen elements contained in the oxide film on the surface, wherein the heating temperature in the first stage is a first temperature; heating the sample heated in the first stage in a second stage to completely melt the sample, wherein the heating temperature in the second stage is a second temperature; and detecting the analyte gas released by the reaction of the sample and the reaction chamber to obtain the element content in the sample, and calculating the oxygen content based on the element content. The silicon wafer oxygen content measuring method and device are safer, and the measuring difficulty is reduced.

Description

Silicon wafer oxygen content determination method and device
Technical Field
The invention relates to the technical field of silicon wafer processing, in particular to a method and a device for measuring the oxygen content of a silicon wafer.
Background
In the production of single crystals by the Czochralski method (Czochralski process, CZ for short), oxygen is inevitably generated inside the single crystal silicon or silicon wafer due to the interaction of the molten silicon and the quartz crucible, and 95% of the oxygen exists in the silicon lattice in a interstitial state. During the process of single crystal silicon or silicon wafers, oxygen existing in the silicon body is precipitated by a certain amount, and the oxygen precipitates are trapped or absorbed (gettering) by foreign substances such as metallic impurities, so that there is an advantage in that the quality of semiconductor products can be improved. However, when the oxygen content in silicon exceeds the semiconductor process conditions, the oxygen precipitates generated on the near surface of silicon cause defects related to the oxygen precipitates generated in the device structure, or induce Leakage (Leakage Current), so that the control of the oxygen content in the silicon wafer has a critical relation to the device performance.
In the related art, methods for measuring the oxygen content in silicon crystals mainly include fourier transform infrared spectrometry (Fourier Transform infrared spectroscopy, abbreviated as FTIR), secondary ion mass spectrometry (Secondary Ion Mass Spectroscopy, abbreviated as SIMS), and gas phase fusion analysis (Gas Fusion Absorption, abbreviated as GFA).
FTIR measurement has the problem that the measurement effect is poor or cannot be measured for a low-resistance high-concentration doped silicon wafer; the SIMS analysis equipment is expensive, so that not only is a great deal of cost required for maintenance and management, but also the efficiency of silicon wafer manufacturing and management is low as a destructive experimental method for checking after the sample is made into small blocks; current GFA assays require etching with mixed acids for sample preparation and are not safe. After the sample is melted at high temperature, the oxygen contained in the sample is gasified to contain CO and CO 2 Is subject to the nature of the sample surface when the gas is subjected to chemical analysisInfluence of the oxide film.
Disclosure of Invention
The embodiment of the disclosure provides a silicon wafer oxygen content measuring method and device, which can solve the problems existing in the silicon wafer oxygen content measuring method in the related art, are safer, and reduce the measuring difficulty.
The technical scheme provided by the embodiment of the disclosure is as follows: a method for determining the oxygen content of a silicon wafer, comprising the following steps:
carrying out surface treatment on the silicon wafer, removing pollutants on the surface of the silicon wafer and reducing the surface roughness;
cutting a silicon wafer into a plurality of samples;
putting the sample with the surface formed with the oxide film into a reaction chamber, wherein the oxide film contains oxygen element;
heating the sample in the reaction chamber in a first stage to decompose the surface oxide film of the sample and remove oxygen elements contained in the surface oxide film, wherein the heating temperature in the first stage is a first temperature;
heating the sample heated in the first stage in the second stage to completely melt the sample, wherein the heating temperature in the second stage is a second temperature;
and detecting the analyte gas released by the reaction of the sample and the reaction chamber to obtain the element content in the sample, and calculating the oxygen content in the silicon wafer based on the element content.
Illustratively, the first temperature is greater than the second temperature, and the value of the first temperature ranges from 1200 ℃ to 1350 ℃; the value range of the second temperature is 2000-2300 ℃.
Illustratively, the first temperature is 1300 ℃; the second temperature is 2100 ℃.
Illustratively, the reaction chamber includes a graphite crucible.
Illustratively, the detecting the analyte gas released by the reaction of the sample with the reaction chamber to obtain the element content in the sample, where the element content includes at least an oxygen content, specifically includes:
the oxygen element in the sample reacts with the reaction chamber to release the analyte gas containing carbon monoxide and carbon dioxide, and the analyte gas is detected by an infrared detector to calculate the oxygen content in the sample.
Illustratively, the silicon wafer has a thickness of 1.2mm or greater and is a low resistance silicon wafer having a resistivity of 0.1 Ω -cm or less.
Exemplary, the surface treatment of the silicon wafer, removing the pollutants on the surface of the silicon wafer, and reducing the surface roughness specifically includes:
the surface roughness Ra of the silicon wafer after surface treatment is in the range of 0.01-0.1 mu m.
Exemplary, the surface treatment of the silicon wafer, removing the pollutants on the surface of the silicon wafer, and reducing the surface roughness specifically includes:
and carrying out surface treatment on the silicon wafer by adopting a grinding or polishing mode.
Illustratively, the sample is 5mm to 19mm in length and 5mm to 19mm in width.
An oxygen content measurement device for a silicon wafer, comprising:
the surface treatment unit is used for carrying out surface treatment on the silicon wafer, removing pollutants on the surface of the silicon wafer and reducing the surface roughness;
the cutting unit is used for cutting the silicon wafer into a plurality of samples;
a transport unit for throwing the sample with the oxide film formed on the surface into a reaction chamber, wherein the oxide film contains oxygen element;
a heating unit for heating the sample in the reaction chamber in a first stage to decompose the surface oxide film of the sample and remove oxygen elements contained in the surface oxide film, and heating the sample heated in the first stage in a second stage to completely melt the sample, wherein the heating temperature in the first stage is a first temperature, and the heating temperature in the second stage is a second temperature;
and the detection unit is used for detecting the analyte gas released by the reaction of the sample and the reaction chamber so as to obtain the element content in the sample, and calculating the oxygen content in the silicon wafer based on the element content.
The beneficial effects brought by the embodiment of the disclosure are as follows:
according to the method and the device for measuring the oxygen content of the silicon wafer, in the sample preparation stage, the oxide film on the surface of the sample can contain oxygen elements, the oxygen elements contained in the oxide film on the surface of the sample can be removed without acid etching and other modes, but the surface pollutants are removed and the surface roughness is reduced only by processing the surface of the silicon wafer, the oxide film on the surface of the sample is decomposed by heating in the first stage when the sample is heated by the GFA measuring method, the oxygen elements contained in the oxide film on the surface of the sample are removed, the sample is completely melted by heating in the second stage, and then the oxygen content of the sample is obtained by detecting the analyte gas released by the reaction of the sample and the reaction chamber. In the method, acid etching samples can be omitted, so that the safety of the method can be improved, a two-stage heating mode is adopted in the heating stage, the whole oxygen content measuring process can be free from the influence of a surface natural oxide film, the method is more stable than a single heating mode, more accurate measuring results can be obtained, and the measuring method is simple and easy to operate.
Drawings
FIG. 1 is a flow chart of a method for determining oxygen content of a silicon wafer according to an embodiment of the disclosure;
FIG. 2 is a graph of heating temperature versus time with time and with time on the abscissa and heating temperature on the ordinate for a silicon wafer oxygen content measurement method employing an embodiment of the present disclosure;
FIG. 3 is a graph of oxygen concentration versus time, plotted on the abscissa as time, and on the ordinate as oxygen content, detected using a silicon wafer oxygen content measurement method in accordance with an embodiment of the present disclosure;
FIG. 4 shows the results of comparing the oxygen content measured by the method of the examples of the present disclosure with the oxygen content measured by the FTIR assay;
fig. 5 is a schematic diagram of a silicon wafer oxygen content measurement device according to an embodiment of the present disclosure.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. It will be apparent that the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments, which can be made by one of ordinary skill in the art without the need for inventive faculty, are within the scope of the present disclosure, based on the described embodiments of the present disclosure.
Unless defined otherwise, technical or scientific terms used in this disclosure should be given the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The terms "first," "second," and the like, as used in this disclosure, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Likewise, the terms "a," "an," or "the" and similar terms do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.
Before explaining the silicon wafer oxygen content measurement method and device provided by the implementation of the present disclosure in detail, the following description is necessary for the related art:
the Czochralski method (Czochralski process, abbreviated as CZ), also known as Czochralski method, is a crystal growth method used to obtain monocrystalline materials of semiconductors (e.g., silicon, germanium, gallium arsenide, etc.), metals (e.g., palladium, platinum, silver, gold, etc.), salts, and synthetic precious stones.
In the production of single crystals by the Czochralski method (Czochralski process, CZ for short), oxygen is inevitably generated inside the single crystal silicon or silicon wafer due to the interaction of the molten silicon and the quartz crucible, and 95% of the oxygen exists in the silicon lattice in a interstitial state. During the process of single crystal silicon or silicon wafers, oxygen existing in the silicon body is precipitated by a certain amount, and the oxygen precipitates are trapped or absorbed (gettering) by foreign substances such as metallic impurities, so that there is an advantage in that the quality of semiconductor products can be improved. The control of the oxygen content in the silicon wafer has a crucial relation to the device performance.
In the related art, methods for measuring the oxygen content in silicon crystals mainly include fourier transform infrared spectrometry (Fourier Transform infrared spectroscopy, abbreviated as FTIR), secondary ion mass spectrometry (Secondary Ion Mass Spectroscopy, abbreviated as SIMS), and gas phase fusion analysis (Gas Fusion Absorption, abbreviated as GFA).
FTIR is a relatively simple and non-destructive measurement technique that uses infrared light to transmit through a silicon wafer to measure the infrared absorption of oxygen between crystal lattices in the silicon crystal and to quantify the oxygen in the crystal based on the absorption. Since the light absorption amount is very sensitive to the concentration of inter-lattice oxygen in the silicon crystal, high sensitivity, high reliability (hi-reliability) evaluation can be performed.
For a heavily doped silicon wafer, for example, a silicon wafer heavily doped with boron element, since the internal boron content thereof is high and the internal oxygen content thereof cannot be measured using a general method, the prior art is based on the FTIR method and improves infrared rays in order to apply it to the measurement of the internal oxygen content of a heavily doped silicon wafer, but the FTIR measurement method is a method that can be measured only by transmitting infrared rays to a certain extent, and for a highly doped silicon wafer having a low electrical resistance (for example, a resistivity of 0.1 Ω·cm or less), since infrared rays are absorbed by free electrons (free electrons) existing in a large amount in the silicon wafer and cannot be transmitted, there is a problem in that the measurement effect of FTIR is poor or cannot be measured.
The SIMS analysis equipment is expensive, and not only requires a lot of maintenance and management, but also is inefficient in terms of manufacturing and management of silicon wafers as a destructive experimental method for inspecting a sample after it is formed into a small block.
The gas phase melt analysis method can measure the internal oxygen content of the heavily doped silicon wafer and is used for measuring the oxygen, nitrogen and hydrogen content in refractory metals and other inorganic materials.
The GFA assay mainly comprises: the pre-weighed sample is put into a graphite crucible to be heated and melted, oxygen in the silicon chip and excessive carbon in the graphite crucible are fully reacted to release analyte gas, carbon monoxide is generated, and the carbon monoxide is converted into carbon dioxide after being heated copper oxide, so that the oxygen in the sample reacts with the graphite crucible to form CO and CO 2 . Inert gas carrier (typically helium) is purged from the furnace by mass flow controller and a series of detectors to detect CO and CO in the analyte gas using a non-dispersive infrared (NDIR) cell 2 Oxygen content data can be obtained. The analyte gas then flows through the heated reagent where the CO is oxidized to form CO 2 While H in the analyte gas 2 Is oxidized to form H 2 O. The analyte gas continues through another set of NDIR cells, where H is detected 2 O and CO 2 CO is then scrubbed from the carrier gas stream 2 And H 2 O, by analysis of H 2 O can obtain hydrogen content data, and the remaining analyte gas is detected for N by a Thermal Conductivity (TC) detector 2 Nitrogen content data can be obtained.
In the case of GFA assay, it is necessary to cut a sample into small pieces of a certain size, then clean the sample, put it into a graphite crucible, and finally calcine the graphite crucible into which the sample is added.
In the sample preparation process, a silicon ingot cutting device such as a Band saw (Band saw) and a Wire saw (Wire saw) is generally used for extracting a sample, then mixed acid (acid) is used for etching the surface of the sample so as to remove oxygen elements in an oxide film on the surface of the sample, and a Dicing saw (Dicing saw) is used for cutting the sample into small samples.
Since the mixed acid (nitric acid+hydrofluoric acid+acetic acid, etc.) used in such sample preparation process has a strong acidity, it is very dangerous to use. In order to improve the safety, special etching equipment is required, and the requirements on operators and equipment are high.
In addition, the prepared sample is melted at high temperature, and the oxygen contained in the sample is gasified into CO and CO 2 And (3) gas. The GFA measurement method for quantifying oxygen contained in the original sample by chemically analyzing the gas is affected by the natural oxide film existing on the surface of the sample.
In order to solve the above problems, the embodiments of the present disclosure provide a method and an apparatus for determining oxygen content of a silicon wafer, which can improve operation safety, reduce operation difficulty, and have the advantage of measuring without high skill of an operator.
As shown in fig. 1, the silicon wafer oxygen content measurement method provided in the embodiment of the present disclosure includes a step of sample preparation and a step of oxygen content measurement using a GFA measurement method.
In particular, the step of sample preparation may comprise the steps of:
s01, slicing a monocrystalline silicon rod to obtain a plurality of silicon wafers;
step S02, performing surface treatment on the silicon wafer, removing pollutants on the surface of the silicon wafer, and reducing the surface roughness;
and S03, cutting the silicon wafer into a plurality of samples.
The step of measuring the oxygen content using the GFA measurement method may comprise the steps of:
step S04, putting the sample with the surface formed with the oxide film into a reaction chamber, wherein the oxide film contains oxygen;
step S05, heating the sample in the reaction chamber in a first stage to decompose the surface oxide film of the sample and remove oxygen elements contained in the surface oxide film, wherein the heating temperature in the first stage is a first temperature;
step S06, heating the sample heated in the first stage in a second stage to enable the sample to be completely melted, wherein the heating temperature in the second stage is a second temperature;
and S07, detecting the analyte gas released by the reaction of the sample and the reaction chamber to obtain the element content in the sample, and calculating the oxygen content in the silicon wafer based on the element content.
According to the silicon wafer oxygen content determination method provided by the embodiment of the disclosure, when a sample is prepared, the surface oxide film of the sample can contain oxygen elements, the oxygen elements contained in the surface oxide film of the sample are removed without acid etching and other modes, but only surface pollutants are removed and surface roughness is reduced by processing the surface of the silicon wafer, then the surface oxide film of the sample is decomposed by first heating in a first stage when the sample is heated by a GFA determination method, the oxygen elements contained in the surface oxide film are removed, the sample is completely melted by heating in a second stage, and then the oxygen content of the sample is obtained by detecting analyte gas released by reaction of the sample and a reaction chamber.
Therefore, the method can improve the safety of the method because acid etching samples can not be used, and a two-stage heating mode is adopted in the heating stage, so that the whole oxygen content measuring process can not be influenced by a natural oxide film on the surface, the method is more stable than a single heating mode, more accurate measuring results can be obtained, and the measuring method is simple and easy to operate.
In step S02, the silicon wafer is subjected to a surface treatment, and the surface may be a cut surface of the silicon wafer formed by slicing the single crystal rod.
In some embodiments, in step S01, the thickness of the silicon wafer is greater than or equal to 1.2mm.
By adopting the scheme, when the monocrystalline silicon rod is sliced, the thickness of the silicon wafer obtained by slicing is too thin, and the oxygen content generated during actual analysis is insufficient, so that the accuracy of measurement is possibly reduced, and the thickness of the silicon wafer is at least more than or equal to 1.2mm.
In addition, the silicon wafer may be a low-resistance silicon wafer having a resistivity of 0.1 Ω·cm or less, so as to perform oxygen content measurement with respect to the low-resistance high-concentration doped silicon wafer. Of course, it can be understood that the application scenario of the silicon wafer oxygen content measurement method provided by the embodiment of the disclosure is not limited to the silicon wafer doped with low resistance and high concentration.
In some embodiments, in the step S02, the surface treatment is performed on the silicon wafer to remove the contaminants on the surface of the cut surface of the silicon wafer and reduce the roughness of the surface of the cut surface, which specifically includes:
and carrying out surface treatment on the silicon wafer by adopting a grinding or polishing mode, wherein the value range of the surface roughness Ra of the silicon wafer after the surface treatment is between 0.01 and 0.1 mu m.
By adopting the scheme, in order to remove the cutting surface pollutants generated in the cutting process of the silicon wafer sample and the rough surface caused by cutting, silicon wafer grinding equipment (Grinder) or polishing equipment can be used for grinding or polishing the cut surface of the silicon wafer, so that the silicon wafer has a smooth surface, and the surface roughness range is between Ra0.01 and 0.1 mu m.
In some exemplary embodiments, in the step S03, the sample has a length of 5mm to 19mm and a width of 5mm to 19mm.
In the above protocol, the sample should be cut to the appropriate size to fit the GFA measuring apparatus. In some embodiments, a Dicing Saw (Dicing Saw) may be used to dice the wafer into samples of a size that has a tolerance of less than ±1 μm from the target size. This is because, if the sizes of the samples are different, the volumes of the samples will be different, and thus it is difficult to obtain a certain measurement value.
Illustratively, the sample may be 6mm in length and 13mm in width, and the sample weight standard may be 0.30g.
Further, in some exemplary embodiments, the first temperature is greater than the second temperature and the first temperature has a value ranging from 1200 ℃ to 1350 ℃; the value range of the second temperature is 2000-2300 ℃.
In the above scheme, when the GFA analysis equipment is used for measuring the oxygen content in the sample, in order to remove oxygen contained in the natural oxide film on the surface, the heating temperature in the first stage can be between about 1200 ℃ and 1350 ℃, and when the temperature is lower than the corresponding range, the natural oxide film (SiO 2 ) Very layeredWhen the temperature is higher than 1350 ℃, not only the natural oxide film of the surface layer but also the silicon body can be melted, and at the moment, the oxygen concentration of the surface layer is difficult to remove, so that the heating temperature in the first stage is about 1200-1350 ℃, and the oxygen components existing on the surface of the sample can be effectively removed; the heating temperature of the second stage is between 2000 ℃ and 2300 ℃, the sample can be completely melted at high temperature, and the oxygen generated in the sample reacts with CO or CO generated by the crucible 2 The gas is placed in an infrared detector to detect the presence of oxygen in the silicon body.
In an exemplary embodiment, the first temperature is 1300 ℃; the second temperature is 2100 ℃.
Illustratively, the reaction chamber includes a graphite crucible. The silicon wafer sample can be placed into a graphite crucible for heating, and the carbon in the graphite crucible can reduce the oxygen in the silicon wafer sample block into CO and/or CO 2 。
In an exemplary embodiment, the step S04 specifically includes:
and the oxygen element in the sample reacts with the reaction chamber to release the analyte gas containing carbon monoxide and carbon dioxide, and the oxygen content of the sample block is obtained by detecting the analyte gas through an infrared detector.
In addition, in some embodiments, the step S04 may further include: passing the analyte gas through a heated reagent in which CO is oxidized to form CO 2 While H in the analyte gas 2 Is oxidized to form H 2 O. The analyte gas continues through another set of NDIR cells, where H is detected 2 O and CO 2 CO is then scrubbed from the carrier gas stream 2 And H 2 O, by analysis of H 2 O can obtain hydrogen content data, and the remaining analyte gas is detected for N by a Thermal Conductivity (TC) detector 2 Nitrogen content data can be obtained.
It should be noted that the silicon wafer oxygen content determination method provided in the embodiments of the present disclosure may be difficult to determine low resistance (e.g., resistance at 0.1 Ω) for FTIR or SIMS determination - cm or less) of the oxygen content of a high-concentration doped silicon waferThe silicon wafer oxygen content determination method provided in the embodiments of the present disclosure can determine the oxygen content in the silicon body in a relatively simple and inexpensive manner by using the GFA determination method. In addition, the GFA analysis of the silicon wafer oxygen content as the GFA determination method in the embodiment of the disclosure by adopting a two-stage heating mode is more stable than that of the GFA determination method in the related art by adopting a single heating mode, and a more accurate determination result can be obtained.
In addition, in order to determine the oxygen content in the silicon wafer, the method for determining the oxygen content in the silicon wafer according to the embodiment of the present disclosure may be used without the sample being limited by the form of the silicon ingot, wafer, or the like.
The following is an illustration of a silicon wafer oxygen content measurement method in one embodiment of the present disclosure.
The oxygen content of the silicon wafer sample having a resistance of 3mΩ -cm was measured in this example.
In this embodiment, the method for determining the oxygen content of the silicon wafer includes the following steps:
first, sample preparation is performed:
cutting the monocrystalline silicon rod with the resistance of 3mΩ -cm at certain intervals by using a cutting tool such as a band saw or a wire saw to obtain a silicon wafer with the thickness of about 1.2mm;
in order to remove pollutants generated on the cut surface of the cut silicon wafer and reduce the surface roughness, grinding equipment (model Grinder #8000 wire mesh) can be used for grinding the surface of the silicon wafer;
in order to allow the sample to be easily put into a carbon crucible (blank) for GFA analysis apparatus, a wafer was cut into a sample of 6mm×13mm size using a dicing saw (dicing saw);
next, GFA measurement was performed:
the sample was placed in the sample-placing port of the GFA meter and GFA measurement was started, wherein the sample was heated at 1300 ℃ at the heating temperature of the first stage as shown in the figure, and the oxide film (SiO 2 ) Removing oxygen existing on the surface; the second stage is heating at 2100 deg.C to melt silicon sample, and extracting CO and CO from the reaction of oxygen (O) generated in the sample and the heating crucible (C) 2 Gas and its preparation methodAn infrared Detector (IR Detector) was fed to measure the oxygen content.
As shown in fig. 3, which shows a graph of the change with time of the oxygen concentration detected by the silicon wafer oxygen content measurement method in this example, t1 represents the time of heating in the first stage, and t2 represents the time of heating in the second stage.
The oxygen content detected by FTIR measurement was used to obtain a calibration curve and a calibration formula for comparison with the oxygen concentration detected by the silicon wafer oxygen content measurement method in this example, and the measurement result was obtained in ppma. Fig. 4 shows the comparison of the oxygen content measured by the method of the examples of the present disclosure with the oxygen content measured by FTIR measurement, and it can be seen from fig. 4 that the regression line consistency (R2) of the two measurement methods is 0.99 or more.
In addition, as shown in fig. 5, an embodiment of the present disclosure further provides a silicon wafer oxygen content measurement device, including:
a surface treatment unit 100 for performing surface treatment on the silicon wafer, removing contaminants on the surface of the silicon wafer, and reducing surface roughness;
a cutting unit 200 for cutting the silicon wafer into a plurality of samples;
a transport unit 300 for feeding the sample having the oxide film formed on the surface thereof into a reaction chamber, wherein the oxide film contains oxygen;
a heating unit 400, configured to perform a first stage heating on the sample, so as to decompose an oxide film on a surface of the sample and remove oxygen elements contained in the oxide film on the surface, and perform a second stage heating on the sample, so as to completely melt the sample, where the heating temperature in the first stage is a first temperature, the heating temperature in the second stage is a second temperature, and the second temperature is greater than the first temperature;
and the detection unit 500 is used for detecting the analyte gas released by the reaction of the sample and the reaction chamber so as to obtain the element content in the sample, and calculating the oxygen content in the silicon wafer based on the element content.
The silicon wafer oxygen content measuring device can also comprise a slicing unit, wherein the slicing unit is used for slicing the monocrystalline silicon, and the slicing unit can be a cutting tool such as a band saw or a wire saw; the surface treatment unit 200 may be an abrasive device or a polishing device.
The following points need to be described:
(1) The drawings of the embodiments of the present disclosure relate only to the structures related to the embodiments of the present disclosure, and other structures may refer to the general design.
(2) In the drawings for describing embodiments of the present disclosure, the thickness of layers or regions is exaggerated or reduced for clarity, i.e., the drawings are not drawn to actual scale. It will be understood that when an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, it can be "directly on" or "under" the other element or intervening elements may be present.
(3) The embodiments of the present disclosure and features in the embodiments may be combined with each other to arrive at a new embodiment without conflict.
The above is merely a specific embodiment of the disclosure, but the protection scope of the disclosure should not be limited thereto, and the protection scope of the disclosure should be subject to the claims.

Claims (10)

1. The method for measuring the oxygen content of the silicon wafer is characterized by comprising the following steps of:
carrying out surface treatment on a silicon wafer, removing pollutants on the surface of the silicon wafer and reducing the surface roughness;
cutting the silicon wafer into a plurality of samples;
putting the sample with the surface formed with the oxide film into a reaction chamber, wherein the oxide film contains oxygen element;
heating the sample in the reaction chamber in a first stage to decompose the surface oxide film of the sample and remove oxygen elements contained in the surface oxide film, wherein the heating temperature in the first stage is a first temperature;
heating the sample heated in the first stage in the second stage to completely melt the sample, wherein the heating temperature in the second stage is a second temperature;
and detecting the analyte gas released by the reaction of the sample and the reaction chamber to obtain the element content in the sample, and calculating the oxygen content in the silicon wafer based on the element content.
2. The method for measuring the oxygen content of a silicon wafer according to claim 1, wherein,
the first temperature is higher than the second temperature, and the value range of the first temperature is 1200-1350 ℃; the value range of the second temperature is 2000-2300 ℃.
3. The method for determining the oxygen content of a silicon wafer according to claim 2, wherein the first temperature is 1300 ℃; the second temperature is 2100 ℃.
4. The method for measuring the oxygen content of a silicon wafer according to claim 1, wherein,
the reaction chamber includes a graphite crucible.
5. The method according to claim 1, wherein the detecting the analyte gas released by the reaction between the sample and the reaction chamber to obtain the element content in the sample, wherein the element content at least includes oxygen content specifically includes:
the oxygen element in the sample reacts with the reaction chamber to release the analyte gas containing carbon monoxide and carbon dioxide, and the analyte gas is detected by an infrared detector to calculate the oxygen content in the sample.
6. The method for measuring the oxygen content of a silicon wafer according to claim 1, wherein,
the thickness of the silicon wafer is larger than or equal to 1.2mm;
the silicon wafer is a low-resistance silicon wafer with resistivity less than or equal to 0.1 omega cm.
7. The method for measuring the oxygen content of a silicon wafer according to claim 1, wherein the surface treatment of the silicon wafer removes contaminants on the surface of the silicon wafer and reduces the surface roughness, and specifically comprises the following steps:
the surface roughness Ra of the silicon wafer after surface treatment is in the range of 0.01-0.1 mu m.
8. The method for measuring the oxygen content of a silicon wafer according to claim 1, wherein the surface treatment of the silicon wafer removes contaminants on the surface of the silicon wafer and reduces the surface roughness, and specifically comprises the following steps:
and carrying out surface treatment on the silicon wafer by adopting a grinding or polishing mode.
9. The method for measuring the oxygen content of a silicon wafer according to claim 1, wherein the length of the sample is 5mm to 19mm and the width is 5mm to 19mm.
10. The silicon wafer oxygen content measuring device is characterized by comprising:
the surface treatment unit is used for carrying out surface treatment on the silicon wafer, removing pollutants on the surface of the silicon wafer and reducing the surface roughness;
the cutting unit is used for cutting the silicon wafer into a plurality of samples;
a transport unit for throwing the sample with the oxide film formed on the surface into a reaction chamber, wherein the oxide film contains oxygen element;
a heating unit for heating the sample in the reaction chamber in a first stage to decompose the surface oxide film of the sample and remove oxygen elements contained in the surface oxide film, and heating the sample heated in the first stage in a second stage to completely melt the sample, wherein the heating temperature in the first stage is a first temperature, and the heating temperature in the second stage is a second temperature;
and the detection unit is used for detecting the analyte gas released by the reaction of the sample and the reaction chamber so as to obtain the element content in the sample, and calculating the oxygen content in the silicon wafer based on the element content.
CN202310636160.4A 2023-05-31 2023-05-31 Silicon wafer oxygen content determination method and device Pending CN116678845A (en)

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