A kind of plasma etching equipment and its sheath voltage measuring method

Abstract

The invention discloses a plasma etching device and a method for measuring the sheath voltage thereof, which can simply and accurately measure the sheath voltage of the plasma etching device. The plasma etching equipment includes: an electrostatic chuck arranged in the reaction chamber for placing the workpiece to be etched; the electrostatic chuck includes at least one set of electrode pairs, and each set of electrode pairs includes a first electrode and a second electrode; each electrode The surface of the pair is covered by an insulating medium; each first electrode is connected to a first DC voltage source with adjustable output voltage; each second electrode is connected to a second DC voltage source with adjustable output voltage; the first electrode is connected to A first resistor is also connected in series in the circuit of the first DC voltage source, and a second resistor is connected in series in the circuit of the second electrode connected to the second DC voltage source; the polarity of the output voltage of the first DC voltage source and the second DC voltage source on the contrary. The reaction chamber is also provided with a voltage measuring device for measuring the voltage on each first resistor or second resistor.

Description

technical field [0001] The invention relates to the technical field of semiconductor processing technology, in particular to a plasma etching device and a method for measuring sheath voltage. Background technique [0002] In the RF plasma etching system, the thermal movement rate of electrons is much higher than that of ions, and the electrons are more affected by the RF electric field. During each RF cycle, the directional movement of electrons forms a sheath near the RF electrode. Ions near the sheath can be attracted by the sheath voltage to enter the sheath and accelerate to bombard the wafer, thereby etching the wafer. [0003] The above-mentioned sheath voltage is usually called the plasma DC bias voltage, which is related to the area of ​​the radio frequency electrode, radio frequency loading power, gas, cavity pressure and other conditions. In a plasma etch tool, the ions are usually able to reach energies close to the RF voltage. The ion energy is directly relate...

AI Technical Summary

Problems solved by technology

This method is more common in early plasma etching machines, but the problem is that metal electrodes are easily etched or deposited in a plasma environment, resulting in resistance changes, resulting in measurement errors

Due to the indirect relationship between the RF voltage and the plasma sheath, and the plasma sheath is easily affected by conditions such as plasma density and chamber grounding, it is difficult for the RF voltage to directly characterize the sheath voltage

In addition, the nonlinear characteristics of the plasma sheath and the increasing use of multi-frequency RF power lead to the doping of many other frequencies in the measured signal, such as harmonic frequency, beat frequency and other signals, which seriously affect the measurement of RF voltage. precision

[0007] For the problem of how to measure the plasma sheath voltage with high precision, there is no good solution in related fields

Images