Plasma etching apparatus and plasma etching method

A plasma etching method for etching a substrate using a plasma etching apparatus comprising:

• a vacuum processing chamber for subjecting a substrate to plasma etching process;
• a substrate stage disposed in the vacuum processing chamber having a support surface for supporting the substrate;
• a plurality of gas inlets provided at an upper portion of the vacuum processing chamber for supplying processing gas into the vacuum processing chamber;
• an electromagnetic wave supply means for supplying electromagnetic waves into the vacuum processing chamber;
• a plurality of light receiving units for receiving plasma emission near a surface of the substrate from a side surface of the vacuum processing chamber, wherein the light receiving units are disposed so that the lengths of optical paths received by the respective light receiving units vary;
• a plasma emission distribution measurement system disposed separately from the plurality of light receiving units for observing an emission intensity of a desired radical at a desired direction near the surface of the substrate;
• a spectroscope for converting the plasma emission received via the plasma emission distribution measurement system and the plurality of light receiving units to emission spectral data;
• a means for computing a radical distribution in the plasma during the plasma etching process using the emission spectral data obtained via the spectroscope;
• a database for storing the radical distribution computed via the means for computing radical distribution and a CD shift distribution of the substrate obtained by the plasma etching process;
• and
• a means for controlling a processing condition of etching using the radical distribution and the CD shift distribution stored in the database and a radical distribution computed via the means for computing the radical distribution during the plasma etching process;
• the method comprising the steps of:
• performing at least two plasma etching processes in advance with the composition or the flow rate of the processing gas varied, and computing the radical density distribution of at least one radical during the plasma etching process;
• measuring the CD shift distribution of the substrate after the plasma etching process;
• storing the condition of the plasma etching processes, the radical density distribution and the CD shift distribution in the database;
• computing a relational expression of the radical density distribution of the at least one radical and the CD shift distribution of the substrate;
• computing a processing condition to realize a uniform CD shift of the substrate;
• and
• computing a control parameter of the etching process in order to realize the computed processing condition, so as to perform the plasma etching process of the substrate using the control parameter.