Offline processing method for metal film thickness data in whole CMP (Chemical Mechanical Planarization) process

Abstract

The invention provides an offline processing method for metal film thickness data in a whole CMP (Chemical Mechanical Planarization) process. The offline processing method comprises the following steps: reading an output signal of an electric eddy sensor, and calculating a sampling signal according to the output signal; setting an amplitude threshold value of the sampling signal; traversing all sampling signals to obtain all non-zero point signal sections according to the amplitude threshold value; calculating the signal width of each non-zero point signal section, and determining a width threshold value of the sampling signals according to the signal width; traversing all non-zero signal sections in a measurement process again according to the amplitude threshold value and the width threshold value, extracting an effective measurement signal section, and calculating an average value of all data points in a central interval of each effective measurement signal section; acquiring the change information of metal film thickness in the whole CMP process according to the average value. According to the offline processing method, the influence of an interference signal and part abnormal signals in the measurement process can be effectively eliminated; a real copper layer thickness change can be calculated concisely and effectively; moreover, the calculation result accuracy is high.

Description

technical field [0001] The invention relates to the technical field of chemical mechanical planarization, in particular to an off-line processing method for metal film thickness data in the whole process of CMP. Background technique [0002] Chemical Mechanical Planarization (CMP) technology is the most effective global planarization method today. It utilizes the synergistic effect of chemical etching and mechanical grinding, which can effectively take into account the local and global flatness of the wafer, and has been widely used in the manufacture of VLSI. For the CMP process, the amount of material removal needs to be strictly controlled. If effective monitoring cannot be achieved, it will be impossible to avoid the occurrence of wafer "over-throw" or "under-throw". [0003] For the copper CMP process, the eddy current method is a low-cost non-contact measurement method with a large measurement range and high measurement accuracy, and is not affected by other non-cond...

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Problems solved by technology

[0004] However, in the CMP process, many factors of the CMP process will have a certain impact on the output signal of the sensor. For example, the rotation and radial swing of the polishing head will cause the measurement track and time of the probe under the wafer to be non-unique, resulting in electrical The number of sampling points of the eddy current sensor under the wafer is not fixed

In addition, the online dressing process of the polishing pad will also introduce interference signals, which will inevitably be mixed into the sampling signals of the whole process, resulting in inaccurate calculation results, which greatly increases the difficulty of offline data processing and analysis

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