Patent EP-2562784-A2 (EP)
Inventor: ELLMER KLAUS
IPC: H01J37/32
Filed: 2012-08-22
Abstract: Sensor arrangement for characterizing plasma coating- and plasma etching in a plasma system, comprises: at least one quartz crystal (1) with a front electrode (2) and a back electrode (3), where the front electrode of the quartz crystal exposed to the plasma etching or plasma coating, is insulated against the housing (5) of the arrangement and is formed as a planar Langmuir probe; a pyrometric sensor (4) for measuring the average temperature of the back electrode; and a pivotable screening diaphragm arranged outside the sensor housing between the opening and plasma source in the plasma unit. Sensor arrangement for characterizing plasma coating- and plasma etching in a plasma system, comprises: at least one quartz crystal (1) with a front electrode (2) and a back electrode (3), where the front electrode of the quartz crystal exposed to the plasma etching or plasma coating, is insulated against the housing (5) of the arrangement and is formed as a planar Langmuir probe, and is connected with a current-voltage characteristic curve measuring device arranged outside the plasma system, for measuring the Langmuir characteristic curve; a pyrometric sensor (4) arranged with respect to the back electrode, for measuring the average temperature of the back electrode, and the quartz crystal with its front electrode formed as planar Langmuir probe and the pyrometric sensor, forms a combination sensor, which is arranged in sensor housing, and which has an opening lying opposite to the front electrode; and a pivotable screening diaphragm arranged outside the sensor housing between the opening and plasma source in the plasma unit. The combination sensor is movable, and has measurement- and evaluation units, which are connected to a computer for data acquisition, -analysis and -display. The quartz crystal with a measuring unit for determining frequency of quartz crystal and the planar Langmuir probe is connected with a measuring unit for measuring its current-voltage characteristic curve, and the pyrometric sensor is connected with a measuring amplifier. The computer determines the deposition- or etching rate, and the plasma density, the electron temperature and the total energy input of the plasma processes, using a measurement program from the measured quantities. An independent claim is also included for determining the characteristics of the plasma coating and plasma etching in a plasma system, for producing thin layers, comprising (i) simultaneously measuring (a) the resonant frequency of the quartz crystal, (b) the I-U characteristic curve of a planar Langmuir probe, and (c) the mean temperature of the rear electrode at a position of the sensor combination in the plasma chamber with a time resolution of milliseconds to seconds, (ii) transmitting the measured data to the computer for data acquisition, -analysis and -display, and (iii) determining the parameters of the plasma coating or plasma etching, such as layer thickness or deposition- or etch rate, plasma density, electron temperature and energy influx from the transmitted data by means of the computer program, where the geometrical dimensions of quartz crystal and Langmuir probe are considered during the determination of layer thickness, or deposition- or etch rate, plasma density and electron temperature and an energy influx calibration factor is considered during the determination of total energy influx.