Method for automatically matching radio frequency impedance

Abstract

The invention provides a radio frequency impedance automatic matching method, which comprises: firstly, adjusting the impedance of the second variable reactive element repeatedly according to a before generated fuzzy control rule table, until the matching network input admittance real part deviation fuzzy value is zero; then, adjusting the impedance of the first variable reactive element repeatedly according to the fuzzy control rule table, until the matching network input admittance imaginary part deviation fuzzy value is zero. Wherein, the fuzzy control rule table uses the fuzzy value of the matching network input admittance real part deviation and the matching network input admittance imaginary part deviation as input parameter, and uses the fuzzy value of the impedance adjusting amount of the first variable reactive element and the second variable reactive element as output parameter; and the value of the matching network input admittance real part deviation is only influenced by the second variable reactive element impedance. By utilizing said characteristics, the invention effectively solves the control coupling problem in impedance automatic matching process, and achieves the advantage that the fuzzy control rule table is easy to realize.

Description

technical field [0001] The invention relates to microelectronic technology, in particular to a method for automatic matching of radio frequency impedance. Background technique [0002] In a typical radio frequency plasma generator, a radio frequency generator with constant output impedance (usually 50Ω) generates radio frequency waves with a fixed frequency (usually 13.56MHz) to provide radio frequency power to the plasma reaction chamber to energize the plasma reaction chamber The gas is excited as a plasma for etching or other processes. Usually, the impedance of the nonlinear load of the plasma reaction chamber is not equal to the constant output impedance of the RF generator, so there is a serious impedance mismatch between the RF generator and the plasma reaction chamber, resulting in a large impedance on the RF transmission line. The reflected power of the RF generator cannot be fully delivered to the plasma chamber. [0003] To solve the above problems, such as fig...

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Problems solved by technology

[0011]In the above method, according to the calculation formula of |Z|error and |θ|error, we can see Both |Z|error and |θ|error are affected by changes in the impedance values ​​of variable reactance components C1 and C2 at the same time, so there is a variable reactance component adjustment process The strong coupling problem of mutual influence between variable reactance elements, especially when the impedance amplitude and phase deviation is large, the chance of misoperation of the variable resistive element is high, and repeated adjustments of one or two variable reactance elements may occur The problem

In addition, because the experience and adjustment strategy of manual control impedance matching needed to design fuzzy control rules are obtained through a large number of experiments and data analysis calculations, it is difficult to design effective fuzzy control rules through "trial and error" without rich experience. big

[0012] It can be seen that the traditional fuzzy control method to achieve impedance matching has problems such as difficult design of fuzzy control rules and strong coupling in the adjustment process.

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