Abstract: A method of transferring a multi-variate process control model from one RF-powered plasma processing chamber (the reference chamber) to another nominally identical RF-powered plasma processing chamber (the target chamber) comprises first determining a multi-variate process control model on the reference tool based upon sensor data, 100. Then, a set of sensor data is taken for the reference chamber by running a designed experiment, 102, and a corresponding set of sensor data is taken for the target chamber using the same designed experiment, 104. The relationship between the reference and target chambers is determined by comparing the results of the designed experiments and calculating a transform matrix representing differences between the two chambers, 106. Finally, the process control model is transformed from the reference chamber to the target chamber using the transform matrix thus obtained, 108.

Abstract: A method of fault identification on a semiconductor manufacturing tool includes monitoring tool sensor output, establishing a fingerprint of tool states based on the plurality of sensors outputs, capturing sensor data indicative of fault conditions, building a library of such fault fingerprints, comparing present tool fingerprint with fault fingerprints to identify a fault condition and estimating the effect of such a fault condition on process output. The fault library is constructed by inducing faults in a systematic way or by adding fingerprints of known faults after they occur.

Abstract: A Langmuir probe for measuring characteristics of a plasma driven by radio frequency (RF) power comprises an elongated conductor 10 having an exposed tip 1 for insertion into an RF plasma and an outer end 3 for connection to external measuring circuitry. In order to reduce distortion over a range of RF frequencies, the probe includes an RF voltage divider 11, 12, 13, 14 in series between the tip and outer end of the conductor.

Abstract: A method for determining optimum plasma chamber cleaning cycles based on an electrical precursor signal. Polymer build up on the interior wall of plasma chamber 1 during normal production runs is monitored by observing the phase of the fundamental RF signal on a pre-selected baseline process. At a predetermined level of this signal, the chamber processing is stopped and the chamber walls are cleaned.

Abstract: A method of fault classification in a plasma process chamber powered by an RF source includes initially running a plurality of different baseline plasma processes on the chamber. For each baseline process, the magnitudes of a plurality of Fourier components of delivered RF power are determined and stored as an impedance fingerprint for that baseline process. In the case of a fault, one or more of the baseline processes is repeated according to a predetermined decision tree to determine the current fingerprints and classify the fault by comparing the current fingerprints with the original fingerprints.

Abstract: A method of fault detection is described for use in a plasma process chamber powered by an RF source and subject to periodic standard preventive maintenance. Prior to a production run, the changes in magnitude of a plurality of Fourier components of the RF source resulting from known changes in a plurality of process conditions are determined and a single parameter which is a linear combination of a selected subset of said components is constructed. The construction is such that the combination is relatively sensitive to pre-selected process changes and relatively insensitive to said standard preventive maintenance. Then, during the production run, the single parameter is monitored to determine if there is a fault in the plasma process.

Abstract: A method of fault detection is described for use in a plasma process chamber powered by an RF source and subject to periodic standard preventive maintenance. Prior to a production run, the changes in magnitude of a plurality of Fourier components of the RF source resulting from known changes in a plurality of process conditions are determined and a single parameter which is a linear combination of a selected subset of said components is constructed. The construction is such that the combination is relatively sensitive to pre-selected process changes and relatively insensitive to said standard preventive maintenance. Then, during the production run, the single parameter is monitored to determine if there is a fault in the plasma process.

Abstract: A method for determining the optimum number of conditioning wafers to be run following a wet clean of the walls of an RF plasma chamber 1 is based on an electrical precursor signal. Polymer build up on a plasma chamber wall during normal chamber conditioning is monitored by observing components of the fundamental RF signal. After a pre-determined number of wafers has been run, a predictive model is used to determine the total number of wafers needed to complete the conditioning cycle.

Abstract: A method for determining optimum plasma chamber cleaning cycles based on an electrical precursor signal. Polymer build up on the interior wall of plasma chamber 1 during normal production runs is monitored by observing the phase of the fundamental RF signal on a pre-selected baseline process. At a predetermined level of this signal, the chamber processing is stopped and the chamber walls are cleaned.

Abstract: A sensor for detecting RF current flowing in a conductor includes a layer 10 of insulating material with a hole 16 for the passage of the RF conductor 18 in a direction normal to the layer. A plurality of conductive tracks 20, 22 (FIG. 3) on the opposite major surfaces of the layer are selectively joined by a plurality of through-holes each containing conductive material. The conductive material selectively connects the conductive elements 20, 22 to form a plurality of loops (FIG. 4) disposed non-parallel to the layer 10 for inductive coupling to the RF conductor 18.

Abstract: A method of processing a high frequency signal containing at least two different fundamental frequencies F1 and F2 and their harmonic components in order to extract at least one harmonic component of each of the two fundamental frequencies comprises sampling the signal at two sampling frequencies CK1=F1(M1/N1) and CK2=F2(M2/N2), where M1 and N1 are a first pair of integers having no common factor and M2 and N2 are a second pair of integers having no common factor. The sample values resulting from sampling at CK1 are stored cyclically in a set of M1 memory locations such that the nth sample value is stored cumulatively in the remM1[n]th memory location, and the sampled values resulting from sampling at CK2 are stored cyclically in a set of M2 memory locations such that the nth sample value is stored cumulatively in the remM2[n]th memory location.

Abstract: An apparatus for sensing RF current delivered to a plasma includes an RF conductor along which the current is delivered to the plasma and which is divided into two parts along part of its length so that substantially equal currents flow in each part. A sensor device is inserted into the gap between the two parts of the conductor and includes first and second inductive loops disposed one n each side of the gap such that when an RF current flows along the RF conductor t magnetic flux surrounding the conductor which is generated by the RF current couples with the loops respectively in opposite directions relative to the sensor device. If a stray magnetic flux normal to the current direction couples with the loops in the same direction relative to the sensor device it will induce voltages in the loops which respectively add to the voltage induced by the RF current in one loop and subtract from the voltage induced by the RF current in the other loop.

Abstract: An apparatus for sensing RF current delivered to a plasma includes an RF conductor along which the current is delivered to the plasma and which is divided into two parts along part of its length so that substantially equal currents flow in each part. A sensor device is inserted into the gap between the two parts of the conductor and includes first and second inductive loops disposed one on each side of the gap such that when an RF current flows along the RF conductor the magnetic flux surrounding the conductor which is generated by the RF current couples with the loops respectively in opposite directions relative to the sensor device. If a stray magnetic flux normal to the current direction couples with the loops in the same direction relative to the sensor device it will induce voltages in the loops which respectively add to the voltage induced by the RF current in one loop and subtract from the voltage induced by the RF current in the other loop.