Method for polishing back surface of ultra-small sample

Abstract

The invention provides a method for polishing the back surface of an ultra-small sample. The method comprises the following steps of sticking an ultra-small chip on a first gasket with the front surface facing downwards, splicing a splicing gasket at the periphery of the chip, cooling and fixing the chip, polishing the back surface of the chip, heating the first gasket and taking down the chip andthe splicing gasket for later use, sticking the chip on a glass slide with the front surface facing upwards, cooling and fixing, pricking needles on the front surface of the chip and obtaining hot spots on the back surface, heating the glass slide with the chip, and taking down the chip, putting the chip on a second gasket coated with AB glue in a manner that the front surface of the chip faces upwards, tightly jointing and splicing a ground splicing gasket with the same height as the chip around the chip, then heating, fixing and cooling, removing a layer from the front surface of the sample, and determining a failure position around the hot spot. According to the method, the difficulty of polishing the back surface of the ultra-small sample can be greatly reduced, subsequent analysis can be carried out, meanwhile, a splicing gasket with a proper height is provided for subsequent wafer grinding, and the wafer grinding difficulty is reduced. The success rate of sample preparation is greatly improved, the improvement of an online process is assisted and promoted, and the product yield is further improved.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a method for polishing the back of an ultra-small sample. Background technique [0002] The failure analysis process of semiconductors is to first conduct electrical verification of the failure mode, and use electrical and physical means to locate the failure, so as to find the root cause. Failure analysis is performed on a chip on the order of centimeters or millimeters, requiring manual grinding layer by layer to find failure points at the nanometer level. With the continuous development of manufacturing technology, the size of the sample is continuously reduced, and the processing requirements for the failure analysis of the sample are getting higher and higher. [0003] Due to the thinning of the back of the sample for the ultra-small package sample, the back of the sample is rough and has scratches. After physical removal of the sample package, residues and scratche...

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Problems solved by technology

[0006] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a method for polishing the back of an ultra-small sample, which is used to solve the problems in th

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