Method for determining wet etching process window

Abstract

The invention discloses a method for determining a wet etching process window. The method is carried out on a same wafer. The method comprises the following steps of: immersing the wafer into an acid liquid in an acid tank in the way of being vertical to the liquid level in the acid tank, and changing etching thicknesses at different height positions on the wafer according to different moments when different height positions on the wafer are immersed into the acid liquid; and determining a wet etching process window according to electric testing results corresponding to etching thicknesses at different height positions on the wafer. The method provided by the invention can be used for accurately obtaining the wet etching process window.

Description

technical field [0001] The invention relates to semiconductor device manufacturing technology, in particular to a method for determining a wet etching process window. Background technique [0002] In the manufacturing process of semiconductor devices, in order to achieve the purpose of detecting the process window (process check), different wafers are wet-etched in the prior art. Different etching thicknesses are obtained by using different etching times. For example, in order to control the height difference between the STI and the active area (AA) in the shallow trench isolation (STI) manufacturing process, it is necessary to detect the process window of the wet etching of the STI, and separate the STI on different wafers. Different heights are obtained by etching, thereby obtaining different height differences between STI and AA. The electrical results obtained in the subsequent Wafer Acceptance Test (WAT) for the different height differences are different. According to ...

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Problems solved by technology

[0003] It should be noted that the WAT test is performed after other processes are completed, so it is likely that the test results obtained will be affected by other subsequent processes, because the impact of other processes on each wafer is different, making Some test results are not clear whether it is because the etch thickness in the wet etching process exceeds the tolerance value and the WAT test results do not meet customer requirements

According to the above example, it is very likely that the wafer with an etching thickness of 20mm is also within the process window, but due to the influence of other subsequent processes, its electrical results are unqualified

Therefore, other processes have different effects on each wafer, resulting in inaccurate results of process window detection, which has become a problem that plagues people now.

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