MOCVD (metal organic chemical vapor deposition) capable of monitoring stress in real time

Abstract

The invention discloses MOCVD (metal organic chemical vapor deposition) capable of monitoring stress in real time. The MOCVD comprises a MOCVD reaction chamber, a height-adjustable microscope, a raman optical fiber probe capable of adjusting height in real time, a step motor for controlling Z-axis height in a vertical direction, a driver, nitrogen gas purging parts, a raman test part, a control computer and a CCD (charge coupled device). The MOCVD is characterized in that the height-adjustable microscope and the raman optical fiber probe capable of adjusting height in real time are internally arranged in the MOCVD reaction chamber; and the nitrogen gas purging parts are additionally arranged at the two sides of the optical fiber probe. According to the MOCVD, thickness of an epitaxial layer is computed by a control computer in an epitaxial growth process, and then, the positions of the step motor and the driver are adjusted in real time, so that a raman laser source is always kept in a state of being focused on a sample surface; meanwhile, the optical fiber probe is guaranteed to be not contaminated by the nitrogen gas purging parts, so that the sensitivity and a signal to noise ratio of a raman signal are improved, and real-time stress monitoring in epitaxial growth is realized.

Description

technical field [0001] The invention relates to the field of semiconductor epitaxial growth, chemical vapor deposition equipment, photoelectric growth and semiconductor testing system, in particular to an MOCVD that can monitor stress in real time. Background technique [0002] For MOCVD epitaxial materials, especially III-nitrides, due to structural design requirements and high cost of homogeneous substrates, heterogeneous epitaxial growth is mostly used. There are differences in lattice constants and thermal expansion coefficients between different materials, and stress will be generated during the epitaxial growth process, resulting in problems such as dislocation generation, degradation of crystal quality, and degradation of device performance and photoaging. Traditional stress testing generally uses XRD or Raman testing systems, but there are the following problems: (1) It is very difficult to build an XRD testing system in MOCVD, because the sample stage, X-ray light s...

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Problems solved by technology

There are differences in lattice constants and thermal expansion coefficients between different materials, and stress will be generated during the epitaxial growth process, resulting in dislocation generation, crystal quality degradation, etc., causing device performance degradation, photoaging, etc.

Traditional stress testing generally uses XRD or Raman testing systems, but there are the following problems: (1) It is very difficult to build an XRD testing system in MOCVD, because the sample stage, X-ray light source and detector need to constantly change the angle during the testing process, However, in MOCVD, the size of the sample stage (slide tray) is very large, and it is difficult to control the angle change; in addition, when the sample stage (slide tray) changes, the uniformity and rate of the reaction gas to the substrate surface will be uneven, resulting in inability to epitaxial growth

Therefore, it is difficult to use the XRD system to monitor the stress changes in the epitaxial growth process in real time; (2) The Raman test system cannot be directly integrated in MOCVD, because the Raman test system needs to be gathered on the sample surface to obtain a test with a normal signal-to-noise ratio As a result, during the epitaxial growth process, with the gradual growth of the epitaxial structure, the distance between the thickness of the epitaxial layer and the microscope is constantly changing, and the focus position of the microscope cannot be adjusted in real time in the high-temperature MOCVD reaction chamber, so that the focus cannot be performed in real time; , when MOCVD is performing epitaxial growth, the reactive gas is easy to react on the lens of the microscope, resulting in damage to the lens. Therefore, it is impossible to directly integrate the Raman test system in MOCVD

[0003] In view of the fact that there is currently no test system that can effectively monitor the stress change of epitaxial growth in real time, and the stress change is particularly important for the epitaxial growth of MOCVD, it is necessary to propose a MOCVD that can monitor stress in real time and a method for real-time monitoring of stress using this MOCVD

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