Method for measuring thickness of film in semiconductor epitaxial wafer

Abstract

The invention provides a method for measuring the thickness of a film layer in a semiconductor epitaxial wafer, and relates to the technical field of semiconductor testing. The method comprises the following steps: providing a side surface of a semiconductor epitaxial wafer; treating the side surface for a preset time period by adopting a pretreatment solution; observing the processed side surfaceunder a preset multiple by adopting an optical microscope, and acquiring a corresponding microscope picture by utilizing a microscope camera; carrying out data processing on the microscope picture toobtain pixel number data corresponding to the film layer; calculating to obtain the thickness of the film layer according to the pixel number data and the pixel scale value. The side surface is processed by adopting the solution, wherein epitaxial layers with different aluminum-containing components can present different gray-scale patterns in a photo, the number of pixels corresponding to the thickness is obtained by utilizing a preset algorithm, and the thickness of a film layer is calculated by combining a pixel scale value. The method has low requirements on measuring equipment, can measure the thickness of the film layer only by using an optical microscope equipped with a camera and a computer, and is easy to popularize and apply.

Description

technical field [0001] The invention relates to the technical field of semiconductor testing, in particular to a method for measuring the thickness of a film in a semiconductor epitaxial wafer. Background technique [0002] In the mass production of molecular beam epitaxy (MBE), XRD (X-ray diffraction) technology is usually used to measure the thickness of each film layer in the epitaxial structure of the grown semiconductor epitaxial wafer. However, for a combined epitaxial layer formed by stacking any two or three materials of GaAs, AlGaAs, and AlAs adjacent to each other, it is difficult to distinguish the specific thickness of each layer in the combined epitaxial layer by XRD technology. [0003] In MBE production, generally, the growth rates of Ga and Al can be determined respectively by using a preset growth rate calibration structure, and then a GaAs / AlGaAs / AlAs combined epitaxial layer of desired thickness can be grown at the growth rate. [0004] However, when some...

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Problems solved by technology

When wet etching the epitaxial layer structure, it is usually difficult to achieve high selectivity wet etching of the GaAs / AlGaAs combined epitaxial layer, and the etching rate of the epitaxial layer in the wet etching solution will vary depending on the etching operating conditions (for example, ambient temperature, Humidity, shaking frequency of the sample during corrosion, etc.), so it is difficult to accurately know the depth of wet corrosion

In order to solve this problem, the photolithography process can be combined with a step meter to achieve depth measurement. However, the process steps of this method are complicated, and the step meter is expensive, and the step meter is not a routine necessary equipment in the molecular beam epitaxy manufacturing industry.

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