Analyzing device, analyzing method, and program for analysis

Abstract

To monitor a processing amount to a processed material with high accuracy.SOLUTION: An analyzing device comprises: a measurement part 2 that measures a concentration or a partial pressure of a reaction product generated when processing a processed material W; and a calculation part 3 that calculates the processing amount to the processed material W by using an output value of the measurement part 2. The measurement part 2 includes: a laser beam source 22 that irradiates a laser beam to a measurement object gas containing the reaction product; a light detection device 23 that detects the laser beam penetrating a measurement object gas; and a signal processing part 242 that calculates the concentration or the partial pressure of the reaction product on the basis of a detection signal of the light detection device 23. The calculation part 3 includes: a time integration part 32 that calculates a time integration value obtained by performing a time integration of an output value of the measurement part 2; a relation data storage part 31 that stores a relation data indicating a relation between a time integration value obtained by performing the time integration of the output value of the measurement part 2 and the processing amount to the processed material; and a processing amount calculation part 33 that calculates the processing amount to the processed material from the time integration value obtained by the time integration part 32 and the relation data.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an analysis device, an analysis method, and an analysis program used in processes such as semiconductor processes. [Background technology]

[0002] Conventionally, in semiconductor processes, for example, in order to monitor an end point (etching depth) in an etching process, a plasma emission monitor (OES; Optical Emission Spectrometer) that detects plasma emission during the process, as shown in Patent Document 1, for example, has been used.

[0003] However, since OES detects plasma emission caused by the action of plasma, it cannot be used in etching processes that do not use plasma. In addition, the output value of OES varies from process to process, day to day, and individual to individual due to individual differences in process chambers and OES, errors in installation position, dirt on windows caused by process gases and reaction products, and the state of luminescent species. For this reason, OES cannot obtain data with good reproducibility, and the endpoint is determined from the trend of change by using the OES output value relatively.

[0004] In addition, analyzers that use the non-dispersive infrared (NDIR) method (NDIR analyzers) are used to monitor the endpoint. However, NDIR analyzers do not have enough resolution (sensitivity) to measure the endpoint accurately. In particular, in recent years, as semiconductors have become increasingly miniaturized and the semiconductor node (minimum line width) becomes smaller, measurement errors due to insufficient resolution (sensitivity) become larger. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-170812 A Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, the present invention has been made to solve the above-mentioned problems, and its main object is to accurately monitor the processing amount of a workpiece in a process for treating the workpiece. [Means for solving the problem]

[0007] That is, the analytical apparatus according to the present invention comprises a measurement unit which measures the concentration, partial pressure or a value related thereto of a reaction product generated when a workpiece is treated in a process for treating the workpiece, and a calculation unit which calculates the processing amount for the workpiece using an output value of the measurement unit, the measurement unit having a laser light source which irradiates a measurement target gas containing the reaction product with laser light, a photodetector which detects the laser light transmitted through the measurement target gas, and a signal processing unit which calculates the concentration, partial pressure or a value related thereto of the reaction product based on a detection signal from the photodetector, and the calculation unit has a time integration unit which calculates a time integral value obtained by integrating the output value of the measurement unit over time, a relationship data storage unit which stores relationship data showing the relationship between the time integral value obtained by integrating the output value of the measurement unit over time and the processing amount for the workpiece, and a processing amount calculation unit which calculates the processing amount for the workpiece from the time integral value obtained by the time integration unit and the relationship data.

[0008] According to this analytical device, the reaction products generated when the workpiece is treated in the process of treating the workpiece are measured by laser spectroscopy, so that the concentration, partial pressure, or values ​​related thereto of the reaction products can be measured with high accuracy.Then, the processing amount for the workpiece is calculated using the relationship between the time integral value obtained by integrating the output value of the measurement unit over time and the processing amount for the workpiece, so that the processing amount for the workpiece can be monitored with high accuracy.

[0009] It is preferable that the calculation unit further includes a processing determination unit that determines whether a processing speed for the workpiece has changed based on a time change in the output value of the measurement unit. With this configuration, for example, when the same film or substance is being treated, if the output value of the measuring unit changes, it can be seen that the treatment speed of the film or substance has changed.

[0010] As described above, in a semiconductor process such as an etching process, the processing speed (etching rate) of the workpiece may vary within the surface. In order to calculate this variation within the surface, it is preferable that the calculation unit further includes a variation calculation unit that calculates the variation in the processing amount within the surface of the workpiece based on the time change in the output value of the measurement unit.

[0011] In order to measure the concentration, partial pressure or values ​​related thereto of reaction products with even greater accuracy by multi-reflection laser spectroscopy, it is desirable that the measurement unit further includes a multi-reflection mirror, the laser light source is configured to direct laser light between the multi-reflection mirrors, and the photodetector is configured to detect light emitted from between the multi-reflection mirrors.

[0012] For example, in a semiconductor process such as an etching process, it is considered that the processing speed (etching rate) of the workpiece varies within the surface. The within-surface distribution of the processing speed can be determined by the generation state of reaction products, and the generation state of reaction products can be determined from the output value of the measurement unit. Therefore, it is preferable that the calculation unit further includes a uniformity determination unit that determines the uniformity of the processing amount for the workpiece based on the time change of the output value of the measurement unit.

[0013] As a specific embodiment, the uniformity determination unit may determine the uniformity of the amount of processing for the workpiece based on the slope of the time change in the output value of the measurement unit. For example, consider a case where the workpiece has a first layer and a second layer below the first layer, and the amount of reaction products generated per unit time by etching the first layer is different from the amount of reaction products generated per unit time by etching the second layer. In this case, if the uniformity of the in-plane distribution of the etching rate is high, the magnitude of the slope in the time change of the output value of the measurement unit will be large when the layer to be etched changes from the first layer to the second layer. On the other hand, if the uniformity of the in-plane distribution of the etching rate is low, the magnitude of the slope in the time change of the output value of the measurement unit will be small when the layer to be etched changes from the first layer to the second layer.

[0014] In order to reduce error factors due to components adhering inside the process chamber, dirt on the optical window, etc., and to measure the reaction products with high accuracy, it is desirable that the measurement unit has a zero calibration function that performs zero calibration in a state where no processing is being performed on the workpiece. More specifically, it is desirable that the measurement unit has a zero calibration function that performs zero calibration in a state where no reaction products are present in the process chamber, for example, (1) a state where no processing is being performed on the workpiece and the process chamber is evacuated, or (2) a state where no processing is being performed on the workpiece and an inert gas such as nitrogen or argon is flowing into the process chamber.

[0015] The laser light source may be a semiconductor laser, and this semiconductor laser is preferably a quantum cascade laser. Quantum cascade lasers are the only practical semiconductor lasers capable of oscillating at wavelengths in the mid-infrared region at room temperature, and because many gas molecules have strong absorption in the mid-infrared region, they can be used to improve analytical instruments.

[0016] In addition, one possible method for creating the relationship data for the above-mentioned analytical device is to use, for example, an ellipsometer to measure the processing amount at multiple points on the processed workpiece, and to obtain a correlation between the average processing amount at those multiple points and the time integral value of the output value of the measurement unit. However, it is necessary to measure the amount of processing at a plurality of points, which not only makes the work complicated but also raises the risk of errors occurring due to averaging. Therefore, the method for creating relational data for an analytical device according to the present invention is characterized in that it processes the workpiece in a process for treating the workpiece, calculates a time integral value by integrating the output value of the measurement unit over time, calculates the processing amount from the weight of the processed workpiece, and generates the relational data from the calculated time integral value and the calculated processing amount.

[0017] According to this method of creating relationship data for an analytical device, the processing volume is calculated from the weight of the processed material, making it easy to create the relationship data and enabling accurate relationship data to be created.

[0018] Furthermore, the analytical method of the present invention is an analytical method using a measurement unit that measures the concentration, partial pressure, or values ​​related to these, of reaction products generated when a workpiece is treated in a process of treating the workpiece, and the measurement unit has a laser light source that irradiates laser light onto a measurement target gas containing the reaction products, a photodetector that detects the laser light that has passed through the measurement target gas, and a signal processing unit that calculates the concentration, partial pressure, or values ​​related to these, of the reaction products based on the detection signal of the photodetector, and is characterized in that it calculates a time integral value by integrating an output value of the measurement unit over time, and calculates the processing amount for the workpiece using relationship data showing the relationship between the time integral value by integrating the output value of the measurement unit over time and the processing amount for the workpiece.

[0019] In addition, an analytical program according to the present invention is an analytical program used in an analytical device having a measurement unit that measures the concentration, partial pressure, or values ​​related thereto of a reaction product generated when a workpiece is treated in a process for treating the workpiece, and is for calculating a processing amount for the workpiece using an output value of the measurement unit, wherein the measurement unit has a laser light source that irradiates a measurement target gas containing the reaction product with laser light, a photodetector that detects the laser light that has passed through the measurement target gas, and a signal processing unit that calculates the concentration, partial pressure, or values ​​related thereto of the reaction product based on a detection signal from the photodetector, and the analytical program causes a computer to perform the functions of a time integration unit that calculates a time integral value obtained by integrating the output value of the measurement unit over time, a relationship data storage unit that stores relationship data showing the relationship between the time integral value obtained by integrating the output value of the measurement unit over time and the processing amount for the workpiece, and a processing amount calculation unit that calculates the processing amount for the workpiece from the time integral value obtained by the time integration unit and the relationship data. Effect of the Invention

[0020] According to the present invention thus configured, it is possible to accurately monitor the amount of a workpiece being treated in a process for treating the workpiece. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic diagram illustrating an analysis device according to an embodiment of the present invention. [Diagram 2] 4 is a functional configuration diagram of a signal processing device and a calculation unit of the measurement unit in the embodiment. FIG. [Diagram 3] 5A to 5C are schematic diagrams showing a method of modulating a laser oscillation wavelength in the embodiment. [Figure 4] 11 is a time series graph showing an example of an oscillation wavelength, a light intensity I(t), a logarithmic intensity L(t), a feature signal Fi(t), and a correlation value Si in the embodiment. [Diagram 5] FIG. 4 is a diagram showing a concept of concentration or partial pressure calculation using a single correlation value and a sample correlation value in the embodiment. [Figure 6] 13 is an experimental result showing a correlation between the output value of the measuring unit of the embodiment and the etching rate, and a correlation between the output value of a conventional plasma optical emission monitor (OES) and the etching rate. [Figure 7] FIG. 13 is a functional configuration diagram of a signal processing device and a calculation unit of a measurement unit according to a modified embodiment. [Figure 8] 13A and 13B are diagrams showing stages of etching in a modified embodiment and output values ​​of a measuring unit at each stage. [Figure 9] 13A is a functional configuration diagram of a calculation unit according to a modified embodiment, and FIG. 13B is a diagram for explaining processing determination. [Figure 10] 13A is a functional configuration diagram of a calculation unit according to a modified embodiment, and FIG. 13B is an explanatory diagram of variation calculation. [Figure 11] FIG. 13 is a diagram showing a method for calculating an etching end point in a modified embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of an analysis device according to the present invention will be described with reference to the drawings. In addition, in any of the drawings shown below, for the purpose of easy understanding, some parts are omitted or exaggerated in schematic form as appropriate. The same components are denoted by the same reference numerals and the description thereof is omitted as appropriate.

[0023] The analytical device 100 according to this embodiment is for monitoring the etching depth of an etched workpiece W. This analytical device 100 measures the concentration, partial pressure, or a value related thereto of a reaction product generated when etching the workpiece W, and obtains the etching depth using an output value indicating the concentration, partial pressure, or a value related thereto.

[0024] 1, the analysis device 100 is installed in an exhaust pipe H of a process chamber PC where etching is performed, and configured to analyze reaction products contained in a gas (hereinafter, a measurement target gas) flowing through the exhaust pipe H. In this embodiment, a turbo molecular pump TMP and a dry pump DP are provided in the exhaust pipe H, and the analysis device 100 is installed between the turbo molecular pump TMP and the dry pump DP, but is not limited to this.

[0025] Specifically, as shown in Figures 1 and 2, the analytical device 100 includes a measurement unit 2 that measures the concentration, partial pressure, or values ​​related to these of reaction products generated when the workpiece W is etched, and a calculation unit 3 that calculates the etching depth of the workpiece W using the output value of the measurement unit 2.

[0026] <Configuration of measurement unit 2> The measurement unit 2 detects reaction products (here, SiF 4 ) concentration, for example, by using infrared laser absorption modulation method (see Patent No. 6886507; IRLAM (Infrared Laser Absorption Modulation)).

[0027] Specifically, as shown in Figures 1 and 2, the measurement unit 2 includes a measurement cell 21 having a pair of multi-reflection mirrors M1 and M2 arranged on either side of the gas to be measured, a semiconductor laser 22 that irradiates laser light onto the measurement cell 21 and causes the laser light to enter between the pair of multi-reflection mirrors M1 and M2, a photodetector 23 that detects the laser light that is emitted from between the pair of multi-reflection mirrors M1 and M2 and passes through the measurement cell 21, and a signal processing device 24 that calculates the concentration or partial pressure of the reaction product based on the detection signal of the photodetector 23.

[0028] The measurement cell 21 is a so-called Herriott cell that reflects the laser light multiple times by providing a pair of multi-reflection mirrors M1 and M2 inside. Note that the measurement cell 21 may be a White cell having a plurality of multi-reflection mirrors provided on either side of the gas to be measured, or a ring cell having an annular multi-reflection mirror surrounding the gas to be measured, in addition to the Herriott cell.

[0029] The semiconductor laser 22 is a quantum cascade laser. A quantum cascade laser is a semiconductor laser that uses intersubband transitions due to a multi-stage quantum well structure, and oscillates laser light of a specific wavelength in the wavelength range of about 4 μm to about 20 μm. This semiconductor laser 22 is capable of modulating (changing) the oscillation wavelength by a given current (or voltage).

[0030] Here, the photodetector 23 used is a thermal type such as a relatively inexpensive thermopile, but other types such as quantum type photoelectric elements such as HgCdTe, InGaAs, InAsSb, PbSe, etc., which have good responsiveness, may also be used.

[0031] The signal processing device 24 comprises analog electrical circuits including buffers, amplifiers, etc., digital electrical circuits including a CPU, memory, etc., and AD converters, DA converters, etc. that mediate between these analog and digital electrical circuits.

[0032] The signal processing device 24, by cooperation of the CPU and its peripheral devices in accordance with a predetermined program stored in a predetermined area of ​​the memory, fulfills the functions of a light source control unit 241 that controls the output of the semiconductor laser 22, and a signal processing unit 242 that receives a detection signal from the photodetector 23 and processes the value to calculate the concentration, partial pressure or a value related thereto of the measurement target component, as shown in Fig. 2. The value related to the concentration or partial pressure includes a value correlated with the concentration or partial pressure, such as absorption intensity.

[0033] Each unit will be described in detail below. In the following, an example in which the signal processing unit 242 calculates the concentration of the measurement target component will be described.

[0034] The light source control unit 241 controls the current source (or voltage source) of the semiconductor laser 22 by outputting a current (or voltage) control signal. Specifically, the light source control unit 241 changes the drive current (or drive voltage) of the semiconductor laser 22 at a predetermined frequency, and modulates the oscillation wavelength of the laser light output from the semiconductor laser 22 at a predetermined frequency with respect to the center wavelength (see FIG. 3). This causes the semiconductor laser 22 to emit modulated light modulated at a predetermined modulation frequency.

[0035] In this embodiment, the light source control unit 241 changes the drive current to a triangular wave shape, and modulates the oscillation frequency to a triangular wave shape (see "Oscillation Wavelength" in FIG. 4). In practice, the drive current is modulated with another function so that the oscillation frequency becomes triangular. Also, the oscillation wavelength of the laser light is modulated with the peak of the optical absorption spectrum of the component to be measured as the center wavelength, as shown in FIG. 3. Alternatively, the light source control unit 241 may change the drive current to a sine wave shape, sawtooth wave shape, or any other function shape, and modulate the oscillation frequency to a sine wave shape, sawtooth wave shape, or any other function shape.

[0036] The signal processing unit 242 includes a logarithm calculation unit 242a, a correlation value calculation unit 242b, a storage unit 242c, a concentration calculation unit 242d, and the like.

[0037] The logarithmic calculation unit 242a performs logarithmic calculation on the light intensity signal, which is the detection signal of the photodetector 23. The function I(t) showing the time-series change of the light intensity signal obtained by the photodetector 23 is shown as "light intensity I(t)" in Fig. 4, and by performing logarithmic calculation, it becomes as shown as "logarithmic intensity L(t)" in Fig. 4.

[0038] The correlation value calculation unit 242b calculates correlation values ​​between an intensity-related signal related to the intensity of sample light obtained when measuring the gas to be measured and a plurality of predetermined feature signals. The feature signal is a signal for extracting a waveform feature of the intensity-related signal by taking a correlation with the intensity-related signal. As the feature signal, for example, a sine wave signal or various other signals that match the waveform feature to be extracted from the intensity-related signal can be used. Here, the correlation value calculation unit 62 uses a logarithmically calculated light intensity signal (logarithmic intensity L(t)) as the intensity-related signal.

[0039] In addition, the correlation value calculation unit 242b calculates a feature signal F that is greater than the total number of types of the measurement target components (reaction products in this embodiment) and the interference components. i (t) (i=1, 2, . . . , n), a plurality of sample correlation values ​​S, which are correlation values ​​between the intensity-related signal of the sample light and each of the plurality of feature signals, are calculated by the following formula (1). i In addition, T in the formula 1 is the modulation period.

[0040]

number

[0041] When calculating the sample correlation value, the correlation value calculation unit 242b calculates the sample correlation value by using the intensity-related signal L(t) of the sample light and the plurality of feature signals F i Correlation value S with (t) i to the reference light intensity-related signal L 0 (t) and multiple feature signals F i The reference correlation value R i The corrected sample correlation value S i It is desirable to calculate "sample correlation value'". This removes the offset contained in the sample correlation value, resulting in a correlation value proportional to the concentrations of the measurement target component and interference component, making it possible to reduce measurement errors. Note that a configuration may be adopted in which the reference correlation value is not subtracted.

[0042] Here, the timing of acquiring the reference light may be simultaneous with the sample light, before or after the measurement, or at any arbitrary timing. The intensity-related signal or the reference correlation value of the reference light may be acquired in advance and stored in the storage unit 242c. In addition, a method of simultaneously acquiring the reference light may be, for example, to provide two photodetectors 23 and split the modulated light from the semiconductor laser 22 by a beam splitter or the like, with one being used for measuring the sample light and the other being used for measuring the reference light.

[0043] In this embodiment, the correlation value calculation unit 242b calculates the correlation value based on a plurality of feature signals F i For (t), a function that is easier to capture the waveform characteristics of the logarithmic intensity L(t) than a sine function is used. In the case of a sample gas containing the target component and one interference component, two or more characteristic signals F 1 (t), F 2 (t) is considered, and two feature signals F 1 (t), F 2 As (t), for example, a function based on a Lorentzian function that is close to the shape of the absorption spectrum and a differential function of the function based on the Lorentzian function can be used. Also, as the feature signal, a function based on a Voigt function or a function based on a Gaussian function can be used instead of the function based on the Lorentzian function. By using such a function as the feature signal, a larger correlation value can be obtained than when a sine function is used, and the measurement accuracy can be improved.

[0044] Here, it is desirable to adjust the offset of the characteristic signal so that the DC component is removed, that is, the offset becomes zero when integrated over the modulation period. This makes it possible to remove the effect of an offset being added to the intensity-related signal due to fluctuations in light intensity. Instead of removing the DC component of the characteristic signal, the DC component of the intensity-related signal may be removed, or the DC components of both the feature signal and the intensity-related signal may be removed. Alternatively, the characteristic signal may be a sample value of the absorption signal of the measurement target component and / or interference component, or a value simulating these.

[0045] In addition, the two feature signals F 1 (t), F 2 By setting (t) to a sequence of mutually orthogonal orthogonal functions or a sequence of functions close to an orthogonal function sequence, the characteristics of the logarithmic intensity L(t) can be extracted more efficiently, and the concentration obtained by the simultaneous equations described later can be more accurately obtained.

[0046] The storage unit 242c stores the intensity-related signals and the feature signals F when the measurement target component and each interference component are present alone. i The single correlation value, which is the correlation value per unit concentration of the measurement target component and each interference component calculated from (t), is stored. i (t) is a plurality of feature signals F used in the correlation value calculation unit 242b. i Same as (t).

[0047] Here, when storing the single correlation value, the storage unit 242c desirably subtracts the reference correlation value from the correlation value when the measurement target component and each interference component exist alone, and then stores the corrected single correlation value converted to a unit concentration. This removes the offset contained in the single correlation value, resulting in a correlation value proportional to the concentrations of the measurement target component and interference components, making it possible to reduce measurement errors. Note that a configuration in which the reference correlation value is not subtracted may also be used.

[0048] The concentration calculation section 242d calculates the concentration of the measurement target component using the multiple sample correlation values ​​obtained by the correlation value calculation section 242b.

[0049] Specifically, the concentration calculation unit 242d calculates the concentration of the component to be measured based on the multiple sample correlation values ​​obtained by the correlation value calculation unit 242b and the multiple single correlation values ​​stored in the storage unit 242c. More specifically, the concentration calculation unit 242d calculates the concentration of the component to be measured by solving simultaneous equations consisting of the multiple sample correlation values ​​obtained by the correlation value calculation unit 242b, the multiple single correlation values ​​stored in the storage unit 242c, and the concentrations of the component to be measured and each of the interference components. Note that FIG. 5 shows a conceptual diagram of concentration or partial pressure calculation using the single correlation value and the sample correlation value in the concentration calculation unit 242d.

[0050] The sample gas contains one target component (here, SiF 4 ) and one interference component, the concentration calculation unit 242d calculates the sample correlation value S 1 ', S 2 ' and the single correlation value s 1t , s 2t , s 1i , s 2i and the concentration C of the target component and each interfering component tar , C int Solve the following simultaneous equations consisting of: 1t is the single correlation value of the measured component in the first feature signal, s 2t is the single correlation value of the measured component in the second feature signal, s 1i is the single correlation value of the interference component in the first feature signal, s 2i is the single correlation value of the interference component in the second characteristic signal.

[0051]

number

[0052] This allows the concentration C of the measurement target component (reaction product) with interference effects removed to be calculated by a simple and reliable calculation of solving the simultaneous equations shown above (Equation 2). tar can be determined.

[0053] Even when it is assumed that there are two or more interfering components, the concentration of the component to be measured with the interference effects removed can be determined by adding a single correlation value for each interfering component and solving a system of simultaneous equations with the same number of elements as the number of component types.

[0054] <Configuration of Calculation Unit 3> Next, a description will be given of the calculation unit 3 that calculates the etching depth of the workpiece W using the output value of the measurement unit 2. Here, the output value of the measurement unit 2 is the concentration of the reaction product obtained by the signal processing unit 242 or a value related to the concentration.

[0055] The calculation unit 3 includes analog electric circuits including buffers, amplifiers, etc., digital electric circuits including a CPU, memory, etc., and AD converters, DA converters, etc. that mediate between these analog and digital electric circuits.

[0056] The calculation unit 3 has a relational data storage unit 31 for storing relational data for determining the etching depth (throughput), a time integration unit 32 for calculating a time integral value obtained by integrating the output value of the measurement unit 2 over time, and a depth calculation unit (throughput calculation unit) 33 for calculating the etching depth (throughput) from the time integral value obtained by the time integration unit 32 and the relational data, as shown in FIG. 2, by the CPU and its peripheral devices working together in accordance with a predetermined analysis program stored in a predetermined area of ​​the memory.

[0057] The relational data storage unit 31 stores relational data indicating the relationship between the etching depth and a time integral value obtained by time-integrating the output value of the measurement unit 2. This relational data is created in advance and stored in the relational data storage unit 31.

[0058] Here, a method for creating the relationship data will be described. First, the workpiece W is etched, and the output value of the measuring unit 2 is integrated over time (0 to t1) to obtain a time integral value G t1 Calculate.

[0059] In addition, the weight W of the etched workpiece Wt1 Measure the initial weight W 0 Difference from (W 0 -W t1 Then, the etching depth d is calculated by the following formula using the density ρ of the processed object (etched film) and the area A of the etched region. d t1 =(W 0 -W t1 ) / (ρ×A)

[0060] Next, the calculated time integral G t1 and the calculated etching depth d t1 The relational data is generated from the set of data (G t1 ,d t1 ) or multiple sets of data (G t1 ,d t1 )~(G tn ,d tn ) The relational data may be created in advance according to the layer structure, material, and other types of the workpiece W.

[0061] The time integration unit 32 receives the output value of the measurement unit 2 and integrates the output value over time to obtain a time integration value G T Here, the time integration unit 32 calculates the elapsed time T E Then, the output value of the measurement unit 2 is integrated over time. In this embodiment, the output value of the measurement unit 2 is the concentration calculated by the concentration calculation unit 242d.

[0062] The depth calculation unit (processing amount calculation unit) 33 calculates the time integral value G T and from the relational data stored in the relational data storage unit 31, the etching depth d T The etching depth d obtained by the depth calculation unit 33 is calculated. TThe etching depth d obtained by the depth calculation unit 33 may be displayed on the display unit 4 such as a display, or may be output in other manners, such as by transmitting the data to another device. In addition, the display unit 4 can display a graph showing the output value of the measurement unit 2 or its change over time, and can also display the etching rate. The calculation unit 3 also calculates the etching depth d obtained by the depth calculation unit 33 using the data obtained by the depth calculation unit 33. T The information processing device may have a notification unit that issues an alarm when a predetermined condition is met, such as when the detected value exceeds a predetermined threshold value.

[0063] <Effects of this embodiment> According to the thus configured analyzing device 100 of the present embodiment, the reaction products generated when etching the workpiece W are measured by a semiconductor laser spectroscopy of a multiple reflection type, so that the concentration or partial pressure of the reaction products can be measured with high accuracy. Furthermore, the etching depth is calculated using the relationship between the time integral value obtained by time-integrating the output value of the measuring unit 2 and the etching depth, so that the etching depth can be monitored with high accuracy.

[0064] In particular, in this embodiment, since an IRLAM is used in the measurement unit 2, it is possible to reduce the influence of interference from interfering components other than the reaction products that are the components to be measured. As a result, it is possible to measure the concentration of the reaction products with high accuracy, to obtain accurate relationship data, and to calculate the etching depth with high accuracy.

[0065] 6 shows the experimental results showing the correlation between the output value of the measuring unit (IRLAM) of this embodiment and the etching rate, and the correlation between the output value of a conventional plasma optical emission monitor (OES) and the etching rate. In the "1st" and "2nd", the same workpieces were etched under the same etching conditions, and the correlation between the measuring unit 2 of this embodiment and the etching rate (IRLAM vs. ER) and the correlation between the conventional plasma optical emission monitor (OES) and the etching rate (OES vs. ER) were obtained.

[0066] In the measurement unit 2 of this embodiment, it is found that the correlation between the etching rate and the output value is reproducible, and that the correlation between the etching rate and the output value is always linear. Since the correlation between the etching rate and the output value is reproducible, it is found that the correlation between the time integral value of the etching rate (etching depth) and the time integral value of the output value is also reproducible. On the other hand, in the conventional plasma optical emission monitor (OES), the correlation between the etching rate and the output value is not reproducible, and in some cases, the sign (±) of the slope changes.

[0067] <Other embodiments> 7, the calculation unit 3 may further include a uniformity determination unit 34 that determines the uniformity of the etching based on the time change in the output value of the measurement unit 2. The uniformity determination unit 34 determines the uniformity of the etching based on the slope of the time change in the output value of the measurement unit 2.

[0068] Here, SiO 2 When etching a workpiece having a resist film formed on a semiconductor substrate on which a film is formed, the output value of the measuring unit 2 (here, SiF 4 The divided pressure of the output voltage Vcc is as shown in FIG.

[0069] In FIG. 8, (1) and (2) are SiO 2 (3) is a state in which only the SiO 2 In this state, not only the film but also the Si substrate is etched. In addition, (4) and (5) show that the SiO 2 This is the state where etching of the film has ended and etching of only the Si substrate continues. The uniformity of the etching can be judged by the slope of the time change of the output value in (3). When the slope of the time change of the output value in (3) is large, it indicates that the uniformity of the in-plane distribution of the etching is high, and when the slope is small, it indicates that the uniformity of the in-plane distribution of the etching is low.

[0070] For example, the uniformity determining unit 34 may compare the gradient of the time change in the output value caused by a change in the layer to be etched with a predetermined threshold value to determine the uniformity of the in-plane distribution of the etching.

[0071] Moreover, the calculation unit 3 may further include a processing determination unit 35 that determines whether the processing speed for the workpiece has changed based on the time change in the output value of the measurement unit 2.

[0072] For example, when the thickness of the film being etched is known, the process determination unit 35 determines that the etching rate has changed based on the time change in the output value of the measurement unit 2 while the same type of film is being etched. Specifically, while the same type of film is being etched, it is considered that the output value of the measurement unit 2 is constant or approximately constant unless the etching conditions are changed. At this time, as shown in FIG. 9, the process determination unit 35 determines that the etching rate is unstable when the output value increases or decreases by a predetermined value or more. It should be noted that the determination that the output value is an output value during the etching of the same type of film, rather than an output value during a transition period when the film being etched changes, can be performed by calculating the etching depth from the time integral value of the output value and the relational data, and comparing it with the known film thickness. In other words, if the etching depth calculated from the time integral value of the output value and the relational data is smaller than the known film thickness, it can be determined that the same type of film is being etched.

[0073] Furthermore, the calculation unit 3 may further include a variation calculation unit 36 ​​that calculates the variation in the processing amount within the surface of the workpiece based on the time change in the output value of the measurement unit 2.

[0074] As shown in FIG. 10, this variation calculation unit 36 ​​can calculate the maximum etching depth and the minimum etching depth from a first stable section (etching of only the first layer) in the output value of the measurement unit 2, a transition section (etching of the first layer and the second layer therebelow) following the stable section, and a second stable section (etching of only the second layer) following the transition section.

[0075] Here, the maximum etching rate is x 1 , the minimum etching rate is x 2 , the average etching rate is x ave The end time of the first stable period is t 1 , the end time of the transition period is t 2 Then, the film thickness h of the first layer can be calculated from the time integral G of the output value of the measurement unit 2, and the following relationship is obtained. t 1 =h / x 1 , t 2 =h / x 2 From these equations, t 2 / t 1 =x 1 / x 2 (t 2 :t 1 =x 1 :x 2 ) This means that t 2 :t 1 :t ave =x 1 :x 2 :x ave and t 1 , t 2 , x ave is known, and t ave =(t 1 +t 2 ) / 2, so x 1 , x 2 can be calculated. Note that x ave is obtained by dividing the average etching depth, which is obtained from the time integral value and the relational data, by time, or may be obtained from the correlation between the etch rate and the output value. As a result, the maximum etching depth (x 1 ×t 2 ) and the minimum etching depth (x 2 ×t 2 ) can be calculated, and the variation in etching depth can be determined.

[0076] 11, the calculation unit 3 may calculate the end point of etching by first or second differentiation of the output value of the measurement unit 2. 2 In a workpiece having a first layer (SiO 2 ) to the second layer (Si) as the end point.

[0077] The measurement unit 2 of the embodiment has a zero calibration function for performing zero calibration in a state where etching is not being performed. More specifically, the measurement unit 2 has a zero calibration function for performing zero calibration in a state where no reaction products are present in the process chamber PC, for example, in a state where (1) no processing is being performed on the workpiece W and the process chamber PC is evacuated, or in a state where (2) no processing is being performed on the workpiece W and an inert gas such as nitrogen or argon is being flowed into the process chamber PC. This reduces error factors due to components adhering to the inside of the process chamber PC or dirt on the optical window, and allows the reaction products to be measured with high accuracy.

[0078] Although the measurement unit 2 in the above embodiment measures the concentration of the reaction product or a value related to the concentration, it may measure the partial pressure of the reaction product in the measurement target gas or a value related to the partial pressure. In this case, the output value of the measurement unit 2 is the partial pressure of the reaction product obtained by the signal processing unit 242 or a value related to the partial pressure.

[0079] Furthermore, in the above embodiment, the measurement unit 2 is incorporated into the exhaust pipe H of the process chamber PC, but it may be provided in a bypass pipe branching off from the exhaust pipe H, or in a measurement pipe connected to the process chamber PC separately from the exhaust pipe H. Also, a pair of multi-reflection mirrors M1, M2 may be provided inside the process chamber PC, or may be connected to an enclosing wall such as a side wall or an upper wall of the process chamber PC.

[0080] Moreover, the functions of the signal processing device 24 and the calculation device 3 of the measurement device 2 in the above embodiment may be provided in one computer (information processing device).

[0081] In the above embodiment, the etching process is taken as an example of a semiconductor process, and the etching depth is calculated, but the present invention may be applied to other semiconductor processes, such as a film formation process, in which a film formation amount is calculated by measuring a reaction product generated in the film formation process, or a process chamber or a cleaning process of a workpiece such as a wafer is calculated. The present invention can also be applied to manufacturing processes for organic electroluminescence (EL) devices, solar cells, etc.

[0082] In addition, various modifications and combinations of the embodiments may be made without departing from the spirit of the present invention. [Explanation of symbols]

[0083] 100...Analyzer W: Workpiece 2...Measurement part M1, M2: Multi-reflection mirrors 22 Semiconductor laser (laser light source) 23...Photodetector 242 Signal processing unit 3... Arithmetic section 31. Relational data storage section 32...Time integration section 33 Depth calculation unit (processing amount calculation unit) 34...Uniformity determination section

Claims

1. A measurement unit that measures a concentration, a partial pressure, or a value related thereto of a reaction product generated when a workpiece is treated in a process of treating the workpiece; a calculation unit that calculates a processing amount for the workpiece using an output value of the measurement unit, The measurement unit includes: a laser light source that irradiates a laser beam onto the measurement target gas containing the reaction products; a photodetector for detecting a laser beam transmitted through the gas to be measured; a signal processing unit that calculates the concentration, partial pressure, or a value related thereto of the reaction product based on the detection signal of the photodetector; The calculation unit is a time integration unit that calculates a time integral value by integrating the output value of the measurement unit with respect to time; a relational data storage unit that stores relational data indicating a relationship between a time integral value obtained by integrating an output value of the measurement unit with respect to time and a processing amount of the workpiece; the analysis apparatus further comprising a processing amount calculation unit that calculates a processing amount for the workpiece from the time integral value obtained by the time integration unit and the relationship data.

2. The analyzer according to claim 1 , wherein the calculation unit further comprises a process determination unit that determines whether a process speed for the workpiece has changed based on a time change in the output value of the measurement unit.

3. The analyzer according to claim 1 , wherein the calculation section further comprises a variation calculation section that calculates a variation in the processing amount within a surface of the workpiece based on a time change in the output value of the measurement section.

4. The measurement unit further includes a multi-reflection mirror, the laser light source causes laser light to be incident between the multiple reflection mirrors, 2. The analyzer according to claim 1, wherein the photodetector detects light emitted from between the multiple reflection mirrors.

5. The analyzer according to claim 1 , wherein the calculation section further comprises a uniformity determination section that determines uniformity of the processing amount for the workpiece based on a time change in the output value of the measurement section.

6. The analyzer according to claim 5 , wherein the uniformity determination unit determines the uniformity of the amount of processing for the workpiece based on a slope of a time change in the output value of the measurement unit.

7. The analyzer according to claim 1 , wherein the measurement section has a zero calibration function for performing zero calibration in a state where no treatment is being performed on the object to be treated.

8. The process is etching, The analytical device according to claim 1 , wherein the processing amount for the workpiece is an etching depth.

9. A method for creating relationship data for an analysis device according to any one of claims 1 to 8, comprising: Treating a workpiece in a process of treating the workpiece; The output value of the measurement unit is integrated over time to calculate a time integral value; Calculating the amount of the treated material from the weight of the treated material; A method for creating relational data, the method comprising: generating the relational data from a calculated time integral value and a calculated processing amount.

10. An analytical method using a measurement unit for measuring a concentration, partial pressure, or a value related thereto of a reaction product generated when a workpiece is treated in a process of treating the workpiece, comprising: the measurement unit includes a laser light source that irradiates a laser beam onto the measurement target gas containing the reaction product, a photodetector that detects the laser beam that has passed through the measurement target gas, and a signal processing unit that calculates a concentration, a partial pressure, or a value related thereto of the reaction product based on a detection signal from the photodetector; An analysis method comprising: calculating a time integral value by integrating an output value of the measurement unit with respect to time; and calculating a processing amount for the workpiece using relationship data showing a relationship between the time integral value by integrating the output value of the measurement unit with respect to time and the processing amount for the workpiece.

11. An analytical program for use in an analytical device having a measurement unit that measures a concentration, partial pressure, or a value related thereto of a reaction product generated when a workpiece is treated in a process for treating the workpiece, the program calculating a treatment amount for the workpiece using an output value of the measurement unit, The measurement unit includes: a laser light source that irradiates a laser beam onto the measurement target gas containing the reaction products; a photodetector for detecting a laser beam transmitted through the gas to be measured; a signal processing unit that calculates the concentration, partial pressure, or a value related thereto of the reaction product based on the detection signal of the photodetector; The analysis program is a time integration unit that calculates a time integral value by integrating the output value of the measurement unit with respect to time; a relational data storage unit that stores relational data indicating a relationship between a time integral value obtained by integrating an output value of the measurement unit with respect to time and a processing amount of the workpiece; a processing amount calculation unit that calculates a processing amount for the workpiece from the time integral value obtained by the time integration unit and the relationship data, said processing amount calculation unit calculating a processing amount for the workpiece from the time integral value obtained by the time integration unit and the relationship data;

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