Optical method for measuring resistivity of silicon wafer in non-contact manner

Abstract

The invention discloses an optical method for measuring resistivity of a silicon wafer in a non-contact manner, which comprises the following steps of exciting the silicon wafer by using laser which is periodically modulated in intensity and has photon energy greater than the width of a silicon forbidden band after collimation and beam expansion, and generating free electron / hole pairs with periodically changed concentration in the silicon wafer; collecting near-infrared fluorescence signals emitted by free electron / hole pairs through radiation recombination by a group of off-axis parabolic mirrors, recording by a near-infrared photoelectric detector and demodulating by a lock-in amplifier, and obtaining the amplitude and phase of the fluorescence signals; obtaining a group of intensity scanning fluorescence signals by continuously changing the average excitation light intensity, and recording the relative change of the excitation light intensity by another photoelectric detector in real time; solving the balanced majority carrier concentration of the silicon wafer by analyzing the intensity scanning data, and then obtaining the resistivity of the silicon wafer. According to the method, the resistivity of the silicon wafer can be measured in a non-contact mode, and an all-optical, lossless and quantitative characterization method is provided for wafer online monitoring / detection in the semiconductor manufacturing industry.

Description

technical field [0001] The invention relates to the field of semiconductor material characteristic detection, in particular to an optical method for non-contact, non-destructive and quantitative measurement of silicon wafer resistivity. Background technique [0002] Resistivity is one of the important parameters to characterize the conductivity of doped semiconductor materials. In today's integrated circuit industry and photovoltaic energy industry production lines, measuring the resistivity of semiconductor materials has become a routine procedure. There are many methods for measuring resistivity. Among them, the four-probe method is a standard method widely used in the global semiconductor industry. Its advantages are simple equipment, high precision, and no strict requirements on the shape of the sample. However, the disadvantages of the four-probe method are also obvious: first, the four-probe method is a contact measurement method, and the process of contacting the pro...

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Problems solved by technology

However, the disadvantages of the four-probe method are also obvious: first, the four-probe method is a contact measurement method, and the process of contacting the probe with the sample will inevitably introduce damage and pollution; Wafers with an insulating layer (such as silicon wafers through surface oxidation passivation), the four-probe method cannot measure the volume resistivity of the wafer unless the probe is used to pierce (damage) the surface insulating layer; the third , the four-probe method belongs to the local detection technology. For the current trend of increasing semiconductor substrate size (16-inch wafers have gradually become the mainstream), the four-probe method can only achieve local sampling, but cannot achieve the entire large Full-coverage scanning measurement of dimensional wafers

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