Introduction of sapphire substrate performance and testing methods

Introduction of sapphire substrate performance and testing methods

2021-11-17 14:24:24 1

Sapphire crystal has excellent characteristics such as high hardness, high melting point, good light transmission, good thermal stability and chemical stability, which is widely used in national defense, aerospace, industry and life, and is especially suitable for LED substrate material.


The quality of the sapphire substrate has a great impact on the subsequent growth of GaN epitaxial layer and the performance and yield of the prepared blue diode, and the production of high-quality substrates requires not only excellent substrate preparation technology, but also the quality of the substrate inspection technology is a very important link.


The flatness of sapphire substrate is one of the key indicators to measure the quality of substrate. Currently, the industry is mainly concerned about the flatness of sapphire in terms of bending (BOW), warpage (SORI) and overall thickness deviation (TTV).

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Bendiness (BOW): the distance between the free unclamped wafer neutral plane


The distance between the center point and the neutral plane. The neutral plane is a plane determined by three equidistant points on the circumference of a specified diameter smaller than the nominal diameter of the wafer.


The measurement of the BOW value of sapphire substrates is now more commonly used in the industry by optical wave interferometry (tilted incidence), and the commonly used measurement instruments are NIDEX's FT-17 and FT-900 series.


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The BOW value is the sum of the absolute value of the center measurement (measuring surface) and the absolute value of the measurement with the largest absolute value that differs from the sign of the center value, using a non-absorbing state and a virtual plane calculated by the least squares method as the reference surface. The symbol is the symbol of the center measurement value.


When the reference surface is close to the fixture: BOW = | A |


For the standard of BOW value, there are specific regulations in the relevant SEMI standards. However, with the development of sapphire substrate patterning (PSS), epitaxial manufacturers have higher requirements for the curvature of sapphire substrates, and the industry has reached a higher consensus on this index.


Warpage (SORI): The difference between the maximum and minimum distance between the neutral plane of a free unclamped wafer and the neutral reference plane. The neutral reference plane is the plane determined by three equidistant points on the circumference of a specified diameter smaller than the nominal diameter of the wafer.


The measurement of the SORI value of sapphire substrates is also commonly used in the industry by optical wave interferometry (tilted incidence), and the common measurement instruments are NIDEX's FT-17 and FT-900 series.


SORI value measurement using non-absorbing state, the virtual plane calculated by the least squares method as the reference plane of measurement, SORI value is the difference between the maximum and minimum value of the whole measurement point.


SORI = | A | | B |

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The total thickness deviation (TTV) is also called GBIR (Global Back Range). When NIDEX FT-17 and FT-900 series are used as measuring instruments, the measuring state is the suction state, the reference plane is the virtual plane parallel to the back of the workpiece and including the center of the workpiece, and the GBIR value is the difference between the maximum value and the minimum value of the difference between the reference plane and each measuring point in the measuring range.


GBIR = | A | | B |

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was established in June 2001, is a national high-tech enterprise specializing in the research and development, production and operation of ultra-precision grinding and polishing materials in China, and is a pioneer in the industry with a number of international and domestic independent intellectual property rights, many years of experience in product technology development and many customer applications.


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Its ultra-precision polishing film & polishing tape, electrostatic flocking abrasive tape & polishing tape, 3D three-dimensional bump abrasive, single crystal & polycrystalline & polycrystalline like - diamond micro powder and corresponding abrasive solution, CMP polishing solution, abrasive additives and other ultra-precision polishing consumables developed and produced by GRISH are widely used in optical communication, automotive, semiconductor, LED, sapphire, ceramics, LCD, 3C electronics, rollers, oral medicine and other industries, and have been exported to many countries and regions such as USA, UK, Germany, Russia, Japan, Korea, India, Brazil, etc.

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