KR100835379B1 - Method for chamber condition monitoring using quadrupole mass spectrometry - Google Patents

Abstract

A chamber condition monitoring method using a quadrupole mass spectrometer is provided to reduce a manufacturing time by performing a seasoning process or monitoring a change of states. A measuring process is performed to measure dissociated ions or mass and energy distribution of reaction kinds of plasma, and density of radicals by using a quadrupole mass spectrometer. A producing process is performed to produce relative distribution of the dissociated ions, and an ionization ratio of the plasma by using the measured results. The ionization ratio of the plasma, the relative distribution and ratio of the dissociated ions, and the density of the radicals are with a normal state of a plasma apparatus(S340). A seasoning process for the process chamber is performed to change a produced value to a normal range when the determined result exceeds the normal range(S350-S380).

Description

Method for Chamber Condition Monitoring Using Quadrupole Mass Spectrometry

1 is a schematic diagram for explaining the configuration of the plasma equipment used in the chamber monitoring method using a quadrupole mass spectrometer according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of a quadrupole mass spectrometer equipped with an energy analyzer mounted on the plasma apparatus of FIG. 1.

3 is a schematic flowchart illustrating a real-time chamber monitoring method using a quadrupole mass spectrometer according to an embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

101: reaction chamber 102: pumping area

110: lower electrode 120: electrostatic chuck

130: upper quartz 140: induction coil

150, 170: RF power source 160, 180: first and second matching network

190: quadrupole mass spectrometer mounting unit 200: quadrupole mass spectrometer

210: pumping area 220: orifice

230: filament 240: ion energy analyzer

250: quadrupole

The present invention relates to a plasma chamber monitoring method, and more particularly, to monitoring a chamber state using a quadrupole mass spectrometer during the initial operation of the plasma equipment, and again after the wet cleaning of the chamber or after the chamber non-operation time. It relates to a plasma chamber monitoring method.

As semiconductor devices are highly integrated, a high selectivity ratio, high anisotropy, and an appropriate etching rate are required in a dry etching process due to a reduction in design rules, and in a dry etching process, it is important to have reproducibility of processes for each wafer. In the dry etching process, when the dry etching chamber is first set or after the wet cleaning of the chamber, the chamber has an idle time between processes, and then proceeds to the main etch process, the atmosphere in the dry etching chamber Because it is not stabilized, a process failure, called the first wafer effect, results in a loss of run wafers. In particular, the first wafer effect described above is serious when starting the etching process and when the etch by-products and polymers, etc. are excessively deposited on the chamber walls, and thus, to avoid this, the test way before the main etching process is avoided. The seasoning process is performed using a test wafer.

The seasoning process refers to a process performed before the stock angle to form an atmosphere inside the chamber, and is a process necessary for discharging. The seasoning process typically cleans the chamber when one cycle of use of the etching equipment is completed, performs about 1 lot of seasoning, and then checks the etching rate and particles, which are process monitoring, and updates the equipment if controlled within the specification. Has been used.

However, when the equipment is used in the above order, it is not possible to determine whether the conditions in the chamber are stable or may cause any problems, and by simply using the equipment depending on the monitoring, the actual problem of the chamber is accurately corrected. There is a problem that cannot be detected.

In particular, apart from the initial product failure of the plasma equipment chamber, the idle time is involved even during continuous production, and thus the condition of the chamber is continuously diagnosed during continuous production, and the initial operation such as this first wafer effect when producing a small quantity or a large quantity of product is performed. It helps to prevent the occurrence of defects in advance and to effectively deal with product defects during the process. Plasma diagnostic equipment is used to analyze the type and concentration of the radicals or compounds formed in the plasma, such as plasma etching and plasma enhanced chemical vapor deposition (PECVD) deposition equipment using plasma, and the type and concentration of charged particles. To measure the properties of these particles, Langmuir probe, quadrupole mass spectrometer (QMS), optical emission spectroscopy (OES), laser induce fluorescence (LIF), etc. This has been used mainly.

However, when using a Langmuir probe, the mass and ion energy distribution of charged particles formed in the plasma cannot be measured. In practice, an error occurs in the use of the Langmuir prism because the effective current-collecting area of the probe is not the actual surface area of the probe but the surface area of the sheath formed around the probe. In addition, a probe located in the plasma may emit secondary electrons by collision with ions, electrons, or photons, which may cause errors.

In addition, in the electron saturation current region, a very large current flows in comparison with the ion saturation current region. In this case, the plasma may fluctuate severely and foreign matter may adhere to the probe surface in the plasma during measurement. There is a need for development of technology that can do this. The biggest problem is that the probe can be inserted into the reactor and thus affect the plasma itself. In addition, in the case of optical emission spectroscopy (OES), argon intensity is often used for quantitative analysis, and the intensity of specific wavelengths and the intensity of argon-induced wavelengths must be considered. There is a disadvantage that there is a peak that cannot be clearly interpreted for the peak and some peaks overlap.

In the prior art, for example, after performing a preliminary stock angle process using a preliminary seasoning recipe, a method of conducting the seasoning process by calculating a standard deviation of the end point detection time, a seasoning effect control method by DC bias, and a photoresist film There is a seasoning method of forming an atmosphere in the etching chamber using the patterned seasoning wafer, and a method of measuring and seasoning the ratio of the radiation intensities of chemical species present in the etching chamber before performing the plasma process. However, these conventional methods have a disadvantage in that it is impossible to accurately detect plasma parameters that are sensitive to etching results and decrease in production efficiency due to defective processing of the used wafers.

Conventional techniques using an optical emission analyzer (OES) include a silicon oxide-based resin present in a process chamber of a plasma apparatus before Song Young-soo (Public Patent Publication No. 10-2005-0062741) and the like perform a plasma process to season a plasma apparatus. SiOx) is a method of measuring the optical emission intensity ratio of the species of the species and the carbon-based compound (CFy), and after the determination whether it is within or outside the steady-state range previously set experimentally, it is presented Xu (Patent No. : US7,067,432 B2), such as the free radical density (free radical density; by measuring the density of a group of atoms to move to the other molecules do not decompose when the chemical change occurs) it was to predict the surface state to the reaction. When the measured radical density value exceeds the allowable range, the above method of cleaning and seasoning the chamber to proceed the process unconditionally repeats cleaning and seasoning without considering the chamber condition according to the process. Etc. are expected.

In contrast, Quadruple Mass Spectroscopy (QMS) accelerates hot electrons by heating filaments, collides with neutral particles to create ions, and applies direct current and alternating voltage to each pole to provide specific mass / charge ratios. The mass of the neutral particles and ions is measured by allowing ions to pass through a mass filter consisting of quadrupoles that pass only particles having a diameter. The mass spectrum of gas in low temperature plasma is very simple and is very useful for measuring the amount of plasma reactive species in the study of plasma chemistry or control of production processes. In addition, quadrupole mass spectrometers can measure the density, mass, and energy distribution of ions or radicals dissociated by collision with electrons to reveal mechanisms for dissociation of electrons and radicals in the plasma, or apply them to process control.

Accordingly, the present invention was devised to solve the above-mentioned problems, and an object of the present invention is to measure the amount of reactive species in a chamber using a quadrupole mass spectrometer and the density of ions or radicals dissociated by collision with electrons. The present invention provides a plasma chamber monitoring method for monitoring a state of a plasma chamber by measuring mass and energy distribution.

In order to achieve the above technical problem, the plasma monitoring method according to the present invention operates the plasma equipment equipped with a quadrupole mass spectrometer to determine the chamber state of the plasma equipment before or during the plasma process, Using a quadrupole mass spectrometer to measure the mass and energy distribution of the ion or plasma reactive species dissociated in the collision with electrons, and the density of radicals; Calculating a relative distribution and ratio of the dissociated ions and an ionization rate of the plasma using the measured results; Determining whether the calculated ionization rate of the plasma and the relative distribution and ratio of the dissociated ions and the density of the radicals are within a steady state range of the plasma equipment; And seasoning the process chamber so that the calculated value is converted into the steady state range when the determination result is out of the steady state range.

Preferably, in the step of determining the steady state range, when the ionization rate of the plasma, the relative distribution and ratio of the ions, and the density of the radicals do not exceed the normal state range, a seasoning process using a polymer-generated plasma is performed. . On the other hand, in the step of determining the steady state range, if the ionization rate of the plasma, the relative distribution and ratio of the ions, and the density of the radical exceeds the steady state range, performing a seasoning process using a chamber cleaning plasma do. The plasma monitoring method performs a seasoning process using the polymer generating plasma or the chamber cleaning plasma according to the determination of the steady state range, and then performs a plasma diagnostic process step to stabilize the state of the chamber.

Steady state ranges such as the ionization rate of the plasma, the relative distribution and ratio of the ions, and the density of the radicals are measured values obtained by performing a plasma diagnosis using a quadrupole mass spectrometer when the process is secured after initial equipment setup. When setting the calculated value to C, you can set from C-α to C + α. Here, α represents a variation allowance range of the plasma, so that the process operator may compare the process result using the plasma with the plasma diagnosis result and set the result within the process margin range.

The measuring step may include heating the filament using the quadrupole mass spectrometer to accelerate the released hot electrons; Accelerating the released hot electrons to collide with neutral particles to dissociate ions; And applying a direct current and an alternating voltage to each pole of the quadrupole mass spectrometer to pass particles having a constant mass / charge ratio through the quadrupole to measure the mass of neutral particles and ions. The constant mass / charge ratio is characteristic of a quadrupole mass spectrometer, expressed in m / z, which is used to collect the desired particles.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

1 is a schematic diagram for explaining the configuration of the plasma equipment used in the chamber monitoring method using a quadrupole mass spectrometer according to an embodiment of the present invention. Referring to FIG. 1, a plasma apparatus used in a chamber monitoring method includes a reaction chamber 101, a pumping region 102 formed under the reaction chamber 101, and a lower electrode 110 capable of supporting a wafer. Cathode) and an electrostatic chuck (ESC) 120 formed thereon, an upper quartz 130 formed on the reaction chamber 101 and an induction coil 140 formed on the upper quartz 130. ). In addition, the plasma equipment includes RF power sources 150 and 170 connected to the lower electrode 110 and the upper quartz 130 to supply power, and the first and second RF power sources 150 and 170 respectively. Further comprising a first and a second matching network (160, 180) connected, the quadrupole pole analyzer analyzer 190 is mounted on one side of the reaction chamber 101, the quadrupole mass spectrometer (200) is formed. Quadrupole mass spectrometer 200 shown in FIG. 1 is shown as a schematic block for convenience of description, and will be described in detail below.

The reaction chamber 101 of the above-described plasma equipment is made of aluminum (Al), and the first RF power source 150 is connected to the support substrate 130 to be used as DC bias power, and the second RF power source. 170 is connected to induction coil 140 and used as induction coil power. Plasma equipment according to the present embodiment does not use a separate external magnetic field, so that the structure is simple and spatially uniform plasma can be obtained. The reaction chamber 101 is configured to be pumped downward through the pumping region 102, and the plasma and the induction (RF) coil 140 in the reaction chamber 101 can be insulated by the upper quartz 130. Are separated. Since the first RF power source 150 used as the DC bias power supply and the first matching network 160 and the second RF power source 170 used as the induction coil power and the second matching network 180 are independent of each other, Ion behavior can be controlled. As a result, it has recently been applied to a plasma apparatus capable of processing a wafer having a large area.

FIG. 2 is a schematic diagram illustrating a configuration of a quadrupole mass spectrometer equipped with an energy analyzer mounted on the plasma apparatus of FIG. 1.

According to FIG. 2, the quadrupole mass spectrometer 200 is used to measure the amount of plasma reactive species and to measure the density, mass and energy distribution of ions or radicals dissociated by collision with electrons. The quadrupole mass spectrometer 200 includes a pumping region 210, an orifice 220 formed at one end, a filament 230 formed adjacent to an orifice 220, and a position adjacent to the filament 230. Ion energy analyzer 240 and quadrupole 250 (secondary electron multiplier, SEM). The pumping region 210 of the quadrupole mass spectrometer 200 is equipped with independent mechanical pumps and turbo molecular pumps to allow differential exhaustion, and the orifice 220 is a part of the reaction chamber 101. It is located in the center of the quadrupole dipole analyzer mounted on the side wall 190, the size is 50 ~ 250 ㎛. The relationship between the absolute flux reaching the lower electrode 110 side of the plasma equipment and the signal intensity was determined by the collision rate of the ions reaching the SEM and the signal intensity. Since the quadrupole mass spectrometer 200 does not measure absolute flux, the quadrupole mass spectrometer 200 is represented as a relative signal strength, but it is suitable to consider the effect of the change of important ions on the semiconductor process.

The quadrupole mass spectrometer 200 having the above configuration accelerates the released hot electrons by heating the filament 230 formed in the quadrupole mass spectrometer 200, and accelerates the released hot electrons to collide with neutral particles to dissociate ions. In addition, DC and AC voltages are applied to each pole constituting the quadrupole mass spectrometer to measure the mass of neutral particles and ions by passing particles having a constant mass-to-charge ratio through the quadrupole. . The measurement of a constant mass-to-charge ratio is a principle of quadrupole mass spectrometry, for example 40/1 = 40 for Ar + and 40/2 = 20 for Ar ++, followed by Ar at 20 and 40 positions, respectively. By forming a peak of, various measurements are possible.

3 is a schematic flowchart illustrating a real-time chamber monitoring method using a quadrupole mass spectrometer according to an embodiment of the present invention.

Referring to FIG. 3, when an operation of monitoring a chamber in real time using a quadrupole mass spectrometer 200 is started (S300), first, a dry etching chamber is first set or a wet cleaning of the chamber is checked. (S310). In step S310, if the cleaning is confirmed, normalization time of the equipment is provided by providing an optimized seasoning recipe using a seasoning process (process using a polymer-generated plasma) S320 for forming an atmosphere inside the chamber. Can shorten. On the other hand, in the cleaning check step (S310), if the cleaning is not confirmed, the plasma diagnostic step (S330) is performed so that the chamber can be optimized.

In the plasma diagnosis step (S330), the quadrupole mass spectrometer 200 measures the amount of plasma reactive species and measures the density, mass, and energy distribution of ions or radicals dissociated by collision with electrons. Through the measurement, the relative dissociation of neutral particles, radicals, and ions of the reaction gas can be measured to calculate the ionization rate of the plasma and the like, and the ion energy distribution can be known to be sensitive to changes in the chamber state. have. The ionization rate, energy distribution, and the like react sensitively to the state of the chamber wall. Processes that use a lot of reactive gases can cause excessive etching of the chamber walls, and plasmas with high CHO content can shorten the wet cleaning cycle of the chamber due to excessive polymer formation on the chamber walls, resulting in lower semiconductor manufacturing process yields. However, the present invention can provide an optimal seasoning process according to the process and chamber conditions by diagnosing the plasma.

After performing the plasma diagnosis step (S330), it is checked whether the measured ion and neutral particle ratio and energy distribution are appropriate, that is, the steady state range (S340). In step (S340), if it is confirmed that the measured ion and neutral particle ratio and energy distribution is in the steady state range, the monitoring is terminated (S390). However, in step S340, when it is determined that the measured ion and neutral particle ratios and energy distribution are out of the normal state range, a seasoning process (polymer generated plasma process) S350 for forming an atmosphere inside the chamber is used. By performing a process (S360) for providing an optimized main recipe or performing a process (S380) for providing an optimized main recipe by using a seasoning process (chamber cleaning process) S370 for cleaning the chamber, Maintain an optimized chamber state. At this time, if the ionization rate of the plasma, the relative distribution and ratio of the ions, and the density of the radical does not exceed the range of the steady state range, the steps (S350) and (S360) are performed, and if the range of the steady state is exceeded Steps S370 and S380 are performed. Steady state ranges such as the ionization rate of the plasma, the relative distribution and ratio of the ions, and the density of the radicals are measured values obtained by performing a plasma diagnosis using a quadrupole mass spectrometer when the process is secured after initial equipment setup. When setting the calculated value to C, you can set from C-α to C + α. Here, α represents a variation allowance range of the plasma, so that the process operator may compare the process result using the plasma with the plasma diagnosis result and set the result within the process margin range.

Then, after the steps S360 and S380 are performed, the process returns to the plasma diagnosis step S330 to diagnose the plasma state.

By performing the above-described polymer production plasma process (S350), the chamber cleaning process (S370) and the seasoning process (S360, S380) according to the main recipe performed, respectively, the reaction chamber as quickly as using a preliminary seasoning recipe It is possible to derive the normal condition of. After the cleaning and polymer generation plasma process, the same method as the main etching process (recipe) can be used to stabilize the reaction chamber, and the plasma diagnosis process can be optimized to create an optimized chamber state to minimize the loss of the run wafer. Can be.

In the existing invention, the necessity of seasoning process was determined by recognizing the change in the relative density distribution of radicals or the distribution with the reactants, but there was a limit in detecting defects by causing a decrease in sensitivity in the process flow to be refined, while the present invention was important. It is easy to apply in the micro process because the movement of ions and the like in the plasma can be understood in consideration of the mass and energy of the active species. This is because quadrupole mass spectrometers are easier to measure and analyze plasma and to analyze plasma behavior than conventional plasma diagnostic methods.

As described above, the preferred embodiment of the present invention has been disclosed through the detailed description and the drawings. The terms are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

According to the present invention as described above, it is possible to effectively prevent the start-up defects such as the first wafer effect or the defects caused by the change of chamber conditions during the process by monitoring the seasoning process or the chamber state change after wet cleaning with minimal investment in the existing plasma equipment. As a result, the yield is expected to increase due to the shortening of the semiconductor manufacturing time and the increase of the chamber cleaning cycle, thereby reducing the manufacturing cost. In addition, the user's convenience can be maximized by the user's easy access to the system configuration for determining the seasoning.

The present invention can improve the yield in a minimum amount of time with a simple understanding of the equipment operator compared to other diagnostic equipment by diagnosing the plasma in real time using a quadrupole mass spectrometer during cleaning and polymer generation after the plasma diagnosis. In the conventional OES method, it is difficult to analyze due to the overlap of light wavelength bands of various atoms and molecules, but in the quadrupole mass spectrometer of the present invention, the mass is analyzed using the mass / charge ratio and the energy is analyzed in the energy analyzer. This makes it easier to analyze than existing plasma diagnostic equipment.

Claims (5)

In order to determine the state of the chamber of the plasma equipment before or during the plasma process by operating the plasma equipment equipped with a quadrupole mass spectrometer, ions dissociated by collision with electrons using the quadrupole mass spectrometer, or Measuring the mass and energy distribution of the plasma reactive species and the density of the radicals; Calculating a relative distribution and ratio of the dissociated ions and an ionization rate of the plasma using the measured results; Determining whether the calculated ionization rate of the plasma and the relative distribution and ratio of the dissociated ions and the density of the radicals are within a steady state range of the plasma equipment; And Seasoning the process chamber so that the calculated value is converted into the steady state range when the determination result is out of the steady state range Plasma chamber monitoring method comprising a. The method of claim 1, wherein in the determining of the steady state range, And performing a seasoning process using a polymer-generating plasma when the ionization rate of the plasma, the relative distribution and ratio of the ions, and the density of radicals are less than a normal state range. The method of claim 1, wherein in the determining of the steady state range, And performing a seasoning process using a chamber cleaning plasma when the ionization rate of the plasma, the relative distribution and ratio of the ions, and the density of the radicals exceed a normal state range. The method according to claim 2 or 3, Performing a seasoning process using the polymer generating plasma or the chamber cleaning plasma according to the determination of the steady state range, and then performing a plasma diagnosis step to stabilize the state of the chamber. The method of claim 1, The measuring step, Heating the filaments using the quadrupole mass spectrometer to accelerate the released hot electrons; Accelerating the released hot electrons to collide with neutral particles to dissociate ions; Measuring the mass of the neutral particles and ions by applying a direct current and alternating voltage to each pole constituting the quadrupole mass spectrometer to pass the particles having a constant mass-to-charge ratio through the quadrupole Plasma chamber monitoring method further comprising.

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