KR20070057983A - Methods and apparatus for monitoring a process in a plasma processing system by measuring impedance - Google Patents

Abstract

A method for in-situ monitoring a process in a plasma processing system having a plasma processing chamber is disclosed. The method includes positioning a substrate in the plasma processing chamber. The method also includes striking a plasma within the plasma processing chamber while the substrate is disposed within the plasma processing chamber. The method further includes obtaining a measured impedance that exists after the plasma is struck, the measured impedance value having a first value when the plasma is absent and at least a second value different from the first value when the plasma is present. The method also includes correlating the measured impedance value with an attribute of the process, if the measured impedance value is outside of a predefined impedance value envelope.

Description

METHODS AND APPARATUS FOR MONITORING A PROCESS IN A PLASMA PROCESSING SYSTEM BY MEASURING IMPEDANCE

background

FIELD OF THE INVENTION The present invention generally relates to substrate manufacturing techniques, and more particularly, to a method and apparatus for monitoring a process in a plasma processing system by measuring impedance.

For example, in the processing of glass panels used in the manufacture of substrates such as semiconductor substrates or flat panel displays, plasma is often used. For example, as part of substrate processing, the substrate is divided into a plurality of dies or rectangular regions, each to be an integrated circuit. The substrate is then processed in a series of steps in which the material is selectively removed (etching step) and stacked (lamination step) to form the electrical component.

In an exemplary plasma treatment, the substrate is coated with a thin film of hardening emulsion (eg, a photoresist mask) before being etched. Thereafter, the area of the curing emulsion is selectively removed to expose the components of the underlying layer. The substrate is then placed on a substrate support structure comprising a monopolar or bipolar electrode called a chuck or pedestal in a plasma processing chamber. A suitable etchant source is then introduced into the chamber and priced to form a plasma, etching the exposed area of the substrate.

Referring to FIG. 1, a schematic diagram of a capacitively coupled plasma processing system is shown. In general, the capacitively coupled plasma processing system may consist of a single RF power source or two separate RF power sources. The source RF generated by the source RF generator 134 is typically used to generate a plasma and to control the plasma density through capacitive coupling. On the other hand, the bias RF generated by the bias RF generator 138 is typically used to control DC bias and ion explosion energy. A matching network 136 is further coupled to the source RF generator 134 and the bias RF generator 138 that attempt to match the impedance of the RF power source to the impedance of the plasma 110. The matching network 136 also includes a V / I probe capable of measuring the plasma frequency generated to further optimize the plasma to processing conditions, and the impedance and voltage of the current delivered to the plasma 110 ( Not shown).

Generally, a suitable set of gases enters the chamber 102 from the gas distribution system 122 through the inlet of the top electrode 104. This plasma processing gas treats (eg, etches or otherwise) exposes an exposed area of a substrate 114, such as a semiconductor substrate or glass panel, positioned by an edge ring 115 on an electrostatic chuck 116 that also functions as an electrode. Lamination) may subsequently be ionized to form plasma 110.

Typically, when the plasma ignites, cooling system 140 is coupled to the static chuck to achieve thermal equilibrium. The cooling system itself includes a cooler that pumps coolant through the cavity into the chuck, and helium gas is pumped between the chuck and the substrate (eg, He flow) by the pump 111. Helium gas not only removes the generated heat, but also allows the cooling system to quickly control heat dissipation. In other words, increasing the helium pressure subsequently increases the heat transfer rate. Most plasma processing systems are also controlled by sophisticated computers containing operating software programs. In a typical operating environment, manufacturing parameters (eg, voltage, gas flow mixing ratio, gas flow rate, pressure, etc.) are configured for a particular plasma processing system and a particular recipe.

In a conventional substrate manufacturing method such as dual damascene, the dielectric layer is electrically connected by a conductive plug filling the via hole. In general, openings are formed in the dielectric layer, typically aligned along a TaN or TiN barrier, and then allow conductive contact between the two sets of conductive patterns (eg, aluminum (Al), copper ( Cu) and the like). This establishes electrical contact between two active regions on the substrate, such as source / drain regions. Extra conductive material on the dielectric layer surface is typically removed by chemical mechanical polishing (CMP). Thereafter, a blanket layer of silicon nitride is laminated to cover copper.

However, in these plasma processes and other plasma processes, it is difficult to accurately determine when the process conditions deviate from established parameters. More specifically, as device dimensions are reduced and more advanced low k materials are used, the requirement for substantially stable process conditions to maintain uniform etch rate, improved yield, and the like becomes more stringent.

More specifically, contamination tends to cause substantial problems. Typically, the degree of contamination depends on the particular plasma process (eg chemicals, power and temperature) and the initial surface conditions of the chamber. Since complete removal of the stack may be time consuming, the plasma processing system chamber may have a consumable structure (e.g., edge ring, etc.) or scheduled when the particle contamination level has reached an unacceptable level. It is only cleaned if the plasma treatment system has to be opened to replace parts of preventive maintenance.

Similarly, hardware deterioration also causes problems. As the plasma chamber component is exposed to the plasma, the component itself may be damaged, the mechanical and electrical properties may change, and may also create contamination. Indeed, the cleaning process itself may damage the component, such as in an electrostatic chuck (chuck) during Waferless Auto Clean (WAC).

However, in general, without the initial initial processing and subsequent testing of the partial fabrication substrate, there is no effective way to determine in situ whether the plasma process deviated from established parameters. That is, the sample substrate is removed from the batch and tested after the batch of substrates has been processed. If the test determines that the substrate does not meet the established specifications, it may be required that the entire placement of the substrate be destroyed.

Creating a simplified experimental model of the plasma processing system to fully capture the motion of the tool may be one solution. However, creating an experimental model can be problematic. For example, a modified inoperative plasma chamber may be analyzed to extract parameters for a simplified experimental model. In another technique, individual components of the plasma processing system may be measured individually using a network analyzer.

However, it is difficult to obtain a roughly correlated (and therefore weak predictive) model because the iteration of the plasma process itself may affect the electrical properties of the plasma processing system component. Generation of simplified experimental models may be done infrequently or only by a skilled person.

In view of the foregoing, a need exists for a method and apparatus for measuring impedance to monitor a process in a plasma processing system.

summary

In one embodiment, the present invention relates to a method for in situ monitoring a process in a plasma processing system having a plasma processing chamber in the plasma processing system. The method includes positioning a substrate in a plasma processing chamber. The method also includes striking the plasma in the plasma processing chamber while the substrate is disposed in the plasma processing chamber. The method further includes obtaining a measured impedance present after the plasma has been charged, wherein the measured impedance has a first value in the absence of the plasma and at least a second value in the presence of a plasma different from the first value. Have The method also includes correlating the measured impedance value with the nature of the process if the measured impedance value is outside the predefined impedance value range.

In one embodiment, the present invention is directed to an apparatus for in situ monitoring a process in a plasma processing system having a plasma processing chamber in the plasma processing system. The apparatus includes means for positioning a substrate in a plasma processing chamber. The apparatus also includes means for striking the plasma in the plasma processing chamber while the substrate is disposed in the plasma processing chamber. The invention further comprises means for obtaining the measured impedance present after the plasma has been charged, wherein the measured impedance has a first value in the absence of the plasma and at least a second value in the presence of a plasma different from the first value. Have The apparatus also includes means for correlating the measured impedance value with the nature of the process if the measured impedance value is outside the predefined impedance value range.

These and other features of the present invention are described in further detail in the following detailed description and the accompanying drawings.

Brief description of the drawings

The invention is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like reference characters designate like elements.

1 is a schematic diagram of a capacitively coupled plasma processing system.

2 is a simplified statistical process control diagram of a set of blanket oxidation etch in certain specific plasma processing systems in accordance with one embodiment of the present invention.

3 is a schematic diagram of FIG. 2 with the addition of a backside He flow chart in accordance with one embodiment of the present invention.

4 is a schematic diagram of FIG. 2 with added impedance measured for 27 MHz in a V / I probe in accordance with an embodiment of the present invention.

5 is a schematic diagram of FIG. 2 with the added impedance measured for 2 MHz in a V / I probe according to one embodiment of the invention.

6 is a schematic diagram of FIG. 2 with the added frequency measured for 27 MHz in a V / I probe in accordance with an embodiment of the present invention.

7 is a schematic diagram of FIG. 2 with the addition of the impedance phase angle measured in the V / I probe according to one embodiment of the invention.

8 is a schematic diagram of a method for in situ monitoring of a process in accordance with an embodiment of the present invention.

Detailed Description of the Preferred Embodiments

Hereinafter, the present invention will be described in detail with reference to some preferred embodiments as shown in the accompanying drawings. In the following description, specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps and / or structures have not been described in detail in order not to unnecessarily obscure the present invention.

While not wishing to be bound by theory, the inventors are convinced that substantially easy to measure plasma parameter excursions may be related to substrate property deviations that are substantially difficult to measure. In general, excursions represent data points that are outside the established statistical range or range of values. That is, the deviation may be a data point higher than the upper limit of the statistical control limit or a data point lower than the lower limit of the statistical control limit. In a plasma process, any deviation that is not detected or disturbed may endanger a significant amount of substrate material.

For example, during normal operation, the plasma parameters may have a specific range or range of values (ie, one set of impedances for each plasma frequency, one set of phase angles for each plasma frequency, specific for each plasma frequency). Frequency range, self bias voltage, etc.) is expected. This range is 3 standard deviations (ie 3σ) of some targets or baselines.

Typically the standard deviation (σ) is the square root of the variance. The standard deviation is a measure of diffusion most commonly used. In general, once the mean and standard deviation of a normal distribution are known, the percentile rank associated with any given score (ie, data points, etc.) can be calculated. In the normal distribution, about 68% of the scores are within 1 standard deviation of the mean, about 95% of the scores are within 2 standard deviations of the mean, and about 99% of the scores are within 3 standard deviations of the mean.

식 (1)

Formula (1)

Where X is a specific score, μ is the mean, and N is the number of scores.

However, plasma processing recipes are optimized for plasma parameters and therefore tend to be very sensitive to plasma parameters. Thus, for certain problems in a plasma processing system, substrate attribute deviations (ie, inadequate etch rate, etc.) may be correlated to plasma parameter deviations (ie, impedance values greater than 3σ for a particular frequency, etc.). That is, certain problems tend to create a set of deviations in both the plasma and the substrate. Common plasma processing problems (and possible process deviations) include chamber contamination, structural damage and deterioration of the plasma, gas pressure leakage, gas flow mixing problems, chamber temperature out of specification, poor RF cables, improperly connected cables, and the like. .

In one embodiment, the correlation between the excursion in the impedance of the RF power supply and the substrate property excursion (eg, inappropriate photoresist etch rate, etc.) at a particular frequency can be determined.

In yet another embodiment, the correlation between frequency deviation and substrate attribute deviation (eg, inappropriate photoresist etch rate, etc.) in a frequency tuned plasma system can be determined. In general, a frequency tuned plasma system can change the set of frequencies used to generate the plasma to minimize the power reflected during the process. As a result, the frequency changes in response to a change in plasma impedance.

In another embodiment, the correlation between the phase angle excursion of the RF power supply and the substrate attribute excursion (eg, inappropriate photoresist etch rate, etc.) at a particular frequency can be determined.

In yet another embodiment, the correlation between the excursion in its own bias voltage and the substrate property excursion (eg, inappropriate photoresist etch rate, etc.) may be determined.

In general, an electric field must be generated in front of the substrate (eg, between the substrate and the plasma) so that plasma ions of sufficient energy impinge upon the substrate. The larger the potential difference between plasma discharge voltages, commonly known as self bias voltages, the greater the tendency for the substrate to attract plasma ions. However, there may also be a voltage potential difference in the plasma chamber between the plasma discharge and other non-target surfaces (ie, chamber walls, top electrodes, etc.), which may dislodge plasma ions from the substrate, so that a self bias voltage is applied to these surfaces. Should have a substantially large potential difference. Subsequently, problems affecting the plasma and the substrate tend to affect self bias voltage.

As mentioned above, the plasma processing system is powered by some type of RF power supply. Typically, there are source RF generators used to generate plasma and control plasma density, and bias RF generators used to control plasma DC bias and ion bombardment energy. Typically these RF sources are in turn coupled to the plasma through a matching network to match the impedance of the RF power supply to the impedance of the plasma.

In addition, the matching network includes voltage (V), current (I), phase angle (θ) between the voltage (V) and current (I) of the plasma, impedance (Z), transmission power, forward power, reflected power, and reactive. It may also include a V / I probe for measuring the vehicular power, reflection coefficient, and the like. In addition, the matching network may modify the generated plasma frequency within established range values to further optimize the plasma to process conditions. As mentioned above, a plasma processing system that can modify one set of frequencies used to generate the plasma is commonly referred to as a frequency tuned plasma system.

The transmission power is usually

Power = V × I × cos (θ) Equation (2)

May be induced.

Complex impedances are typically

Z = V ₀ / I ₀ = R + jX equation (3)

Where V ₀ is the voltage of the base (peak voltage), I ₀ is the current of the base (peak current), R is the real resistance value, and j is the square root of -1 (complex imaginary part). And X is a complex reactance. Complex reactance is an expression of the limit at which an electronic component stores and releases energy as the current and voltage oscillate in an AC cycle of each of the resulting signals having an angular frequency expressed as ω.

ω is the angular frequency of the signal generated by the voltage source,

ω = 2π (frequency) equation (4)

It is expressed as

The phase angle of the plasma impedance is

Phase angle (θ) = tan ^-1 (X / R) equation (5)

Where R = Zcos (θ) and X = Zsin (θ).

Referring to FIG. 2, a simplified statistical process control diagram of a set of blanket oxide etch in a particular same plasma processing system for several weeks is shown, in accordance with one embodiment of the present invention. In general, the quality of a plasma processing system is referred to as compliance with requirements. In general, conformity refers to the extent to which a substrate meets a pre-established requirement or specification in a recipe, such as a target, tolerance, and the like.

In addition, any given plasma process may include some degree of uncertainty, also known as dispersion. In general, the reduction in variance is directly related to the increase in the corresponding quality. Some causes of dispersion are considered to be typical or acceptable and do not necessarily require treatment. For example, minute differences may occur in substrates produced by performing the same process in different plasma processing systems. That is, in attempts to match one plasma processing system to another, deviations almost certainly occur. Other causes of dispersion are not common or particular. These causes are not expected parts of the process and may therefore require some type of correction. That is, they exceed the boundaries of conventional dispersion. For example, moisture in the plasma chamber can destroy the substrate.

In this figure, the target is the desired average etch rate of about 110.52 nm / min and the tolerance is about etch rate within an upper control limit (ER UCL) and about 100.91 nm Maintain an etch rate within an lower control limit (ER LCL) per minute. This particular set of etching is performed in a Lam Research Exelan ^™ 2300 dual frequency plasma processing system, although other plasma processing systems may be used. The process parameters are as follows.

Pressure: 70 milli-torr

Power (2 MHz): 1000.0 Watts

Power (27 MHz): 2000.0 Watts

Gas Mixing: 5 SCCM CH ₂ F ₂ , 6 SCCM C ₄ F ₈ , 180 SCCM N ₂ & 200 SCCM Ar

Temperature: 80 ℃ at TP & 20 ℃ at ESC

Process time: 60 seconds

CW: 37

Plot 202 reflects the etch rate of the blanket oxide at nanometers per minute (nm / minute) over the course of several weeks. Analyzing this figure, two deviation points: 204 performed in 4/6/2004, and 206 performed in 4/9/2004 may be apparent. As noted above, excursions represent data points that exist outside of established statistical ranges or ranges of values, and include a number of factors (ie chamber contamination, structural damage and deterioration of plasma, gas pressure leakage, gas flow mixing problems). , Out-of-spec chamber temperature, poor RF cable, improperly connected cable, He flow on the back, etc.).

Referring to FIG. 3, there is shown a schematic diagram of FIG. 2 with the He flowchart of the back side added in accordance with an embodiment of the present invention. As noted above, plot 202 reflects the etch rate of the blanket oxide at nanometers per minute (nm / minute) over the course of several weeks. Similarly, plot 208 reflects correspondingly measured backside He flow during each etch.

As shown in 4/6/2004, both the etch plot 202 and the plot 208 of the He flow chart show the deviation at 204. That is, as the He flow is reduced to about 33.5 SCCM, the etch rate is also substantially reduced to about 33.4 nm / min, substantially outside of 3σ, which is the control limit lower limit (LCL) of 100.91 nm / min.

This may mean correlation because both the etch rate and the He flow reflect the deviation at the same point. Thus, He flow may be a substantial cause of etch rate deviation in 4/6/2004. Conversely, since the reduced etch plot 202 excursion at 4/9/2004 at about 33.5 nm / min at 206 does not appear to be strongly correlated to the reduced He flow as in plot 204, the reduced He flow is 4/9. It will not be a substantial cause of the etch rate deviation in / 2004.

Referring to FIG. 4, there is shown a schematic of FIG. 2 with the impedance measured for 27 MHz in a V / I probe in accordance with one embodiment of the present invention. As noted above, plot 202 reflects the etch rate of the blanket oxide at nanometers per minute (nm / minute) over the course of several weeks. Plot 402 also reflects the corresponding measured impedance for 27 MHz.

As mentioned above, the desired target etch rate is about 110.52 nm / min, the upper control limit etch rate (ER UCL) is about 120.12 nm / min, and the lower control limit etch rate (ER LCL) is about 100.91 nm / min. Minutes. The desired target impedance is about 3.88 ohms, the upper limit of control limit (Z UCL) is about 4.02 ohms, and the lower limit of control limit (Z LCL) is about 3.75 ohms. Both measured impedances 402 for etch plots 202 and 27 MHz exhibit excursions around 204 in 4/6/2004, and both 206a and 206b in 4/9/2004. Thus, the deviation of the measured impedance appears to correlate with a substantial decrease in etch rate below E / R LCL (ie, attribute excursion) (above Z UCL or below Z LCL).

Without wishing to be bound by theory, the inventors are convinced that a factor that may substantially change the plasma impedance may result in a substantial change in substrate properties such as etch rate. These factors may include deterioration of the chamber material (e.g. electrodes, confinement rings, etc.), gas flow deviation, gas pressure or temperature, substrate type changes, changes in the chuck surface, problems with the RF generator, RF connections, poor RF cable or the like may be included.

Referring to FIG. 5, a schematic diagram of FIG. 2 is shown, with a measured impedance for 2 MHz added in a V / I probe in accordance with an embodiment of the present invention. As noted above, plot 202 reflects the etch rate of the blanket oxide at nanometers per minute (nm / minute) over the course of several weeks. Plot 502 also reflects the corresponding measured impedance for 27 MHz.

As mentioned above, the desired target etch rate is about 110.52 nm / min, the upper control limit etch rate (ER UCL) is about 120.12 nm / min, and the lower control limit etch rate (ER LCL) is about 100.91 nm / min. Minutes. The desired target impedance is about 145.73 ohms, the upper limit of the control limit is about 149.16 ohms, and the lower limit of the control limit is about 142.29 ohms.

Both the impedance 402 measured for the etch plots 202 and 2 MHz exhibited excursions around both 204a and 204b in 4/6/2004 and 206 in 4/9/2004. As in FIG. 5, the excursion in the measured impedance appears to correlate with a substantial decrease in etch rate below E / R LCL (ie, attribute excursion) (either above Z UCL or below Z LCL).

Referring to FIG. 6, there is shown a schematic diagram of FIG. 2 with the measured frequency for 27 MHz in a V / I probe in accordance with an embodiment of the present invention. As noted above, the frequency tuned plasma system can change the set of frequencies used to generate the plasma to minimize the power reflected during the process. As a result, the frequency changes in response to a change in plasma impedance.

As noted above, plot 202 reflects the etch rate of the blanket oxide at nanometers per minute (nm / minute) over the course of several weeks. Plot 602 also reflects the measured frequency, corresponding to the 27 MHz generation. As mentioned above, the desired target etch rate is about 110.52 nm / min, the upper control limit etch rate (ER UCL) is about 120.12 nm / min, and the lower control limit etch rate (ER LCL) is about 100.91 nm. / Minute. The desired target frequency for 27 MHz is about 27.47680 MHz, the upper control limit frequency (FREQ UCL) is about 27.52331 MHz, and the lower control limit frequency (FREQ LCL) is about 27.43029 MHz.

The measured frequencies 602 for plots 202 and 27 MHz represent deviations around both points 204a and 204b at 4/6/2004 and point 206 around 4/9/2004. In the figure shown, the deviation is defined as a point that exceeds 3 standard deviations (3σ) of the plot mean. Thus, the excursion at the measured frequency appears to correlate with a substantial reduction in etch rate (ie, attribute excursion) below E / R LCL (whether above FREQ UCL or below FREQ LCL).

Referring to FIG. 7, there is shown a schematic diagram of FIG. 2 with the impedance phase angle measured in a V / I probe in accordance with one embodiment of the present invention. As noted above, plot 202 reflects the etch rate of the blanket oxide at nanometers per minute (nm / minute) over the course of several weeks. Plot 702 also reflects the corresponding measured phase angle for impedance.

As described above, the desired target etch rate is about 110.52 nm / min, the upper control limit etch rate (ER LUL) is 120.12 nm / min and the lower control limit etch rate (ER LCL) is 100.91 nm / min. . The desired target value of the measured impedance phase angle is -59.67 °, the angle of the control limit upper limit (ANGLE UCL) is about -58.17 ° and the angle of the control limit lower limit (ANGLE LCL) is about -61.16 °.

Etch plot 202 and measured phase angle 702 represent deviations around point 204 at 4/6/2004, and both points 206a and 206b around 4/9/2004. In the figure, the deviation is defined as a point that exceeds 3 standard deviations (3σ) of the plot mean. Thus, the deviation in the measured phase angle appears to correlate with a substantial decrease in etch rate below E / R LCL (ie, attribute excursion) (either above ANGLE UCL or below ANGLE LCL).

8, a schematic diagram of a method for in-situ monitoring a process in a plasma processing system having a plasma processing chamber in accordance with one embodiment of the present invention is shown. First, in step 802 the substrate is placed on a plasma processing substrate. Next, in step 804, the plasma is charged in the plasma processing chamber while the substrate is placed in the plasma processing chamber. Then, in step 806, the measured impedance present after the plasma is charged is obtained, the measured impedance having at least a first value in the absence of the plasma, and a second value in the presence of a plasma different from the first value. In step 808, if the measured impedance value is out of the predefined impedance value range, in step 810, the measured impedance value is correlated with an attribute of the process. Otherwise, at step 812, the measured self bias value is not correlated with the nature of the process.

While the invention has been described in terms of various preferred embodiments, there are variations, substitutions, and equivalents within the spirit of the invention. For example, the present invention has been described in connection with Lam Research's plasma processing system (e.g., Exelan ^™ , Exelan ^™ HP, Exelan ^™ HPT, 2300 ^™ , Versys ^™ Star, etc.), but other (e.g., capacity Coupling, inductive coupling, atmospheric, etc.) plasma processing systems may be used. In addition, the present invention may be used for substrates of various diameters (eg, 200 mm, 300 mm, etc.). It should also be appreciated that there are a variety of alternative ways of implementing the methods of the present invention.

Advantages of the invention include methods and apparatus for measuring impedance to monitor a process in a plasma processing system. Additional advantages include the use of substantially reliable signals that can be used for diagnostic or monitoring purposes.

Modifications and variations of the disclosed embodiments may be practiced without departing from the spirit and spirit of the invention as defined by the following embodiments and the best mode disclosed.

Claims (44)

A method of in situ monitoring a process in a plasma processing system having a plasma processing chamber, the method comprising: Positioning a substrate in the plasma processing chamber; Striking the plasma in the plasma processing chamber while placing the substrate in the plasma processing chamber; Obtaining a measured impedance present after the plasma has been charged, wherein the measured impedance has at least a first value in the absence of the plasma, and a second value in the presence of the plasma that is different from the first value, Obtaining the impedance; If the measured impedance value is out of a predefined impedance value range, correlating the measured impedance value to an attribute of the process. The method of claim 1, Acquiring the measured impedance value is performed at a specific RF frequency. The method of claim 2, And said specific RF frequency is about 2 MHz. The method of claim 2, And said specific RF frequency is about 27 MHz. The method of claim 2, And said specific RF frequency is about 13.56 MHz. The method of claim 2, Wherein the plasma processing system comprises an RF generator having a V / I probe, wherein obtaining the measured impedance value is performed using the V / I probe. The method of claim 6, The measured impedance value represents a value of a phase angle measurement. The method of claim 6, The measured impedance value represents a value of an amplitude measurement. The method of claim 1, The predefined range of impedance values includes a lower control limit of impedance. The method of claim 9, And the lower control limit of the impedance is within 3σ of a predefined impedance target value. The method of claim 1, The predefined range of impedance values includes an upper limit of the control limit of impedance. The method of claim 11, The upper limit of the control limit of the impedance is within 3σ of the predefined impedance target value. The method of claim 1, And the predefined impedance value range comprises a lower control limit of an impedance and an upper control limit of an impedance. The method of claim 1, And the substrate is a semiconductor wafer. The method of claim 1, And the substrate is a glass panel. The method of claim 1, The attribute of the substrate indicates an etch rate while etching the substrate. The method of claim 1, And wherein said attribute of said substrate represents a selectivity rate during etching said substrate. The method of claim 1, Wherein the attribute of the substrate represents an etch uniformity measurement during etching of the substrate. The method of claim 1, The plasma processing system is a capacitively coupled plasma processing system. The method of claim 1, And the plasma processing system is an inductively coupled plasma processing system. The method of claim 1, The plasma processing system is an atmospheric plasma processing system. The method of claim 1, The plasma processing system is a frequency tuned coupled plasma processing system. An apparatus for in-situ monitoring a process in a plasma processing system having a plasma processing chamber, the apparatus comprising: Means for positioning a substrate in the plasma processing chamber; Means for striking the plasma in the plasma processing chamber while placing the substrate in the plasma processing chamber; Means for obtaining a measured impedance present after the plasma has been charged, wherein the measured impedance has at least a first value in the absence of the plasma, and a second value in the presence of the plasma that is different from the first value, Means for obtaining the impedance; Means for correlating the measured impedance value to an attribute of the process if the measured impedance value is out of a predefined impedance value range. The method of claim 23, And the means for obtaining the measured impedance value is performed at a specific RF frequency. The method of claim 24, And the specific RF frequency is about 2 MHz. The method of claim 24, And the specific RF frequency is about 27 MHz. The method of claim 24, And the specific RF frequency is about 13.56 MHz. The method of claim 24, The plasma processing system comprises an RF generator having a V / I probe, and wherein the means for obtaining the measured impedance value comprises using the V / I probe. The method of claim 28, And the measured impedance value represents a value of a phase angle measurement. The method of claim 28, And the measured impedance value represents a value of an amplitude measurement. The method of claim 23, And the predefined impedance value range comprises a lower control limit of impedance. The method of claim 31, wherein And the lower limit of the control limit of the impedance is within 3σ of a predefined impedance target value. The method of claim 23, And the predefined impedance value range comprises an upper limit of the control limit of impedance. The method of claim 33, wherein The upper limit of the control limit of the impedance is within 3σ of the predefined impedance target value. The method of claim 23, And the predefined impedance value range comprises a lower control limit of an impedance and an upper control limit of an impedance. The method of claim 23, And the substrate is a semiconductor wafer. The method of claim 23, And the substrate is a glass panel. The method of claim 23, The attribute of the substrate indicates an etch rate during etching of the substrate. The method of claim 23, The attribute of the substrate indicates a selectivity rate while etching the substrate. The method of claim 23, Wherein the attribute of the substrate represents a measure of etch uniformity during etching of the substrate. The method of claim 23, And the plasma processing system is a capacitively coupled plasma processing system. The method of claim 23, And the plasma processing system is an inductively coupled plasma processing system. The method of claim 23, And the plasma processing system is an atmospheric plasma processing system. The method of claim 23, And the plasma processing system is a frequency tuned coupled plasma processing system.

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