JP2011107107A - Shape processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shape processing method capable of processing of highly precise at high speed, even when correlation is not defined uniquely between processing time and processing amount by means of local processing tool. <P>SOLUTION: By measuring sequentially the processing amount by means of local processing tool at each processing point P<SB>i</SB>during the period of processing and by estimating the temporal change of the processing amount, the processing amount V<SB>i, i+1, i</SB>and V<SB>i, i+1, i+1</SB>processed during the time of moving between the processing points are calculated. When the sum of the processing amount during the time of moving derived from such a calculation and the processing amount V<SB>i</SB>at the present processing point become more than the requested processing amount V<SB>i, f</SB>at the present processing point P<SB>i</SB>, movement of local processing tool to a next processing point P<SB>i+1</SB>is started. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a shape processing method for performing shape processing using a local processing tool having a unit processing area smaller than the area of a workpiece.

  As a method of processing a workpiece into an arbitrary shape using a local processing tool, a method of scanning while varying the stay time of the local processing tool according to a desired processing amount is known. In this method, the processing time of the local processing tool is relatively long at a processing point with a large desired processing amount, and the processing time is relatively short at a processing point with a small desired processing amount. Become. First, the shape before processing of the workpiece is measured, and the distribution of the desired processing amount is calculated from the difference between the shape before processing and the desired shape. Next, a dummy work piece having the same quality as the work piece is machined by the local machining tool, thereby obtaining a machining shape (unit machining shape) per unit time of the local machining tool. Then, the distribution of the desired machining amount is deconvoluted by the unit machining shape, and the distribution data of the staying time of the local machining tool is created. According to the distribution data of the staying time, the local processing tool and the workpiece are processed by relative movement to obtain a desired shape.

  The above processing method is based on the premise that the processing speed does not change with time. On the other hand, a method for obtaining a desired machining shape even when the machining speed has changed over time is known (see Patent Document 1 and Patent Document 2). All of these local processing tools of the prior art perform processing using activated species generated by discharging a gaseous material.

  The one disclosed in Patent Document 1 monitors the processing amount during processing by interference based on the optical path difference between the workpiece and the reflector, and when the actual processing amount and the desired processing amount coincide with each other, By stopping the processing, a desired shape is obtained.

  What is disclosed in Patent Document 2 acquires in advance correlation data between the processing time and the processing amount determined according to the type of reaction gas and the material of the workpiece, The processing time is controlled based on the coordinate difference between the two and the correlation data.

Japanese Patent No. 3917703 Japanese Patent No. 2962583

  However, since what is disclosed in Patent Document 1 starts movement between machining points after the actual machining amount and the desired machining amount match, if the machining speed at the start of movement is different, Variations in the processing amount make it impossible to perform highly accurate processing. In addition, in order to eliminate machining during movement, it is necessary to start and stop machining at all machining points, which makes the total machining time redundant. Furthermore, when there are a large number of machining points and the staying time differs between the machining points, the surface temperature of the machining point changes depending on the history of the staying time. Particularly in the case of machining by chemical reaction, the machining speed depends on the temperature of the machined surface, so that there are as many correlations between the machining time and the machining amount as the number of stay time history patterns.

  In the technique disclosed in Patent Document 2, it is necessary to obtain in advance correlation data between the machining time and the machining amount assuming all stay time histories, and a large amount of labor is required for the preliminary experiment.

  An object of the present invention is to provide a shape machining method capable of high-precision, high-speed and efficient machining even when the correlation between the machining time and the machining amount by the local machining tool is not uniquely determined. is there.

  In order to solve the above problems, a shape processing method of the present invention is a shape processing method for processing a local processing tool while sequentially moving to a plurality of processing points of a workpiece, and each processing point of the workpiece is processed. Measuring the machining amount by the local machining tool in machining during machining, and the time variation of the machining quantity at each machining point, the current machining point by the local machining tool moving from the previous machining point to the current machining point Calculating the sum of the machining amount, the machining amount of the current machining point by the local machining tool that is moving from the current machining point to the next machining point, and the machining amount by the local machining tool at the current machining point; And the movement of the local machining tool from the current machining point to the next machining point is started when the sum of the machining amounts exceeds a desired machining amount at the current machining point.

  The machining amount of the moving local machining tool is calculated based on the measured machining amount, and the stay time of each machining point is determined, so there is no need to stop at each machining point, and all machining points are continuous. Thus, it is possible to improve the processing efficiency. Moreover, a desired machining shape can be obtained even when the correlation between the machining time and the machining amount is not uniquely determined by sequentially measuring the change in the machining amount over time (change over time) during machining.

It is a flowchart which shows the shape processing method by one Embodiment. It is a graph which shows the relationship between the processing time by a local processing tool, and processing amount. It is a figure which shows the unit removal shape by the processing apparatus which concerns on Example 1, and a local processing tool. It is a figure which shows the distribution data of the shape which should be processed, and desired processing amount. It is a graph which shows the relationship between the processing time by the shape processing method of Example 1, and a processing amount. It is a graph which shows the relationship between the processing time by the shape processing method of Example 2, and a processing amount. FIG. 6 is a diagram illustrating a processing apparatus according to a third embodiment. It is a graph which shows the relationship between the processing time by the shape processing method of Example 4, and a processing amount.

1 and 2, serve to explain the shaping method according to an embodiment, the processing amount V _{i, i + 1, j} moves the local machining tool from the machining point P _i of the workpiece to the machining point P _{i + 1} It is the amount of processing of the processing point P _j by the moving local processing tool that is sometimes processed. Also, the V _i measured processing amount as a processing weight measured at the processing point P _i after moving the machining point P _i, V _{i, f} is the desired processing amount of the machining point P _i.

As shown in the flowchart of FIG. 1, when machining while sequentially moving the local machining tool to a plurality of processing points of the workpiece, calculating the distribution data of a desired processing amount of each machining point P _i (step S01). The machining starts at time t = 0 from a point P ₀ that is far enough not to affect the distribution data of the desired machining amount. Then, the processing amount is monitored (measured) with the start of processing (step S02).

  The processing amount is monitored by detecting the emission intensity of the etching product. The emission intensity at the emission wavelength inherent to the etching product is proportional to the amount of etching product generated. Therefore, by acquiring the correlation between the integrated value of the emission intensity at the emission wavelength and the processing amount in advance, the processing amount can be monitored by the emission intensity. Note that the processing amount monitoring method is not limited to this. Examples of alternative means are listed below. The first example is a method of monitoring the amount of etching products generated with a known quadrupole mass spectrometer. The second example is a method of monitoring the difference between the supply amount of the etchant measured in advance before processing and the amount of the etchant exhausted during processing using a known quadrupole mass spectrometer or the like. The third example is a method of monitoring the displacement of the processing point with a laser displacement meter. A fourth example is a method of monitoring by interference based on the optical path difference between the workpiece and the reflector.

  In calculating the machining amount during the movement of the local machining tool, the time change (time-dependent change) of the machining amount is estimated (step S03). The change of the machining amount with respect to the machining time is fitted by a known function such as a polynomial or an exponential function. For the fitting, a part or all of the data including the latest data is used among the data related to the machining of the current machining point. Using these data, the coefficient of the known function is determined, and a time change curve of the machining amount is determined. Further, the time Δt required to move to the next machining point is calculated from the scanning speed, the scanning acceleration, and the distance between the machining points. Using the time change curve of the machining amount, the increment of the machining amount until after Δt / 2 is set as the machining amount at the current machining point, and the increment of the machining amount between Δt / 2 and after Δt is set as the machining amount at the next machining point. Add.

  As another method for estimating the time change of the machining amount, a method by measuring the temperature of the machining point will be described. In particular, when a chemical reaction is used for processing, there is a strong correlation between the processing point temperature and the processing speed. Therefore, a dummy workpiece having the same quality as the target workpiece is processed in advance by controlling the temperature of the processing point to various values, and correlation data between the temperature and the processing speed is acquired. During actual machining, the machining amount is monitored and the temperature at the machining point is sequentially measured. Then, the time change curve of the machining amount is estimated using the machining amount at each time, the machining point temperature, and the machining speed obtained from the correlation data between the temperature and the machining speed. The machining amount during movement is calculated as follows. The time required to move to the next machining point is set as Δt, and the machining speed is integrated between Δt / 2 after the current time and added to the machining amount at the current machining point. Further, the machining speed is integrated between Δt / 2 and Δt and added to the machining amount at the next machining point.

In this way, the machining amount during movement is sequentially measured, and the machining amount V _0,1, of the machining point P ₁ machined by the local machining tool moving from the machining point P ₀ to the first machining point P _{1 . 1} is obtained (step S04). At time t = t ₀ when measurement data of the machining amount sufficient to calculate the machining amount V _0,1,1 during movement is obtained, the machining point P ₀ is moved to the machining point P ₁ (step S05). Step S06). At the same time we arrived at the processing point _{P 1} (time t = _{t 1),} and starts the measurement of the processing amount, obtain the actual processing amount _{V 1} of the after movement to the machining point _{P 1} (step S07). By sequentially measuring the processing amount, and estimates the amount of machining time changes in the machining point P ₁ (step S08). Then, the processing amount _{V 1,2,1} and processing amount _{V 1,2,2} of the next machining point _{P 2} of the current working point _{P i} to be processed by the next local machining tool moving to the machining point _{P 2} Sequential calculation is performed (step S09). If the sum of V _0,1,1 and V ₁ and V _{1,2,1 exceeds} the desired machining amount V _{1, f} of the machining point P _{1 in} step S10, machining is performed from the machining point P ₁ in step S11. The movement of the local processing tool to the point P ₂ is started (time t = t ₂ ).

  The desired shape is obtained by repeating the steps of measuring the machining amount, calculating the machining amount during movement of the local machining tool, and moving the local machining tool, and scanning the entire distribution data of the desired machining amount.

Instead of starting the processing with the point P ₀ sufficiently separated from the distribution data of the desired processing amount, the processing may be started with the processing point P ₁ as the starting point. When starting the processing of the processing point P ₁ to the origin, it starts with the step of obtaining immediate processing point P ₁ the measured processing amount V _i. In this case, although depending on the type of the local processing tool, since the unit removal shape may be disturbed at the start of processing, the processing can be performed with higher accuracy by using the processing point P ₀ as the starting point.

  In this example, a workpiece made of synthetic quartz was processed by chemically reacting with an active species containing fluorine. FIG. 3A shows the configuration of the apparatus used in this example. The workpiece 301 was placed in the chamber 311 together with the holder 302. The chamber 311 is evacuated by a vacuum pump (not shown). A gas introduction line 308 and a power introduction line 309 are connected to the processing tool 307 which is a local processing tool. The gas introduced from the gas introduction line 308 was ionized with the power introduced from the power introduction line 309 to generate a jet 310 of active species containing fluorine, and the workpiece 301 was irradiated with the active species to perform processing. . The amount of processing was monitored by inputting light emitted from the processing point into the light detector 305 through the optical fiber 304 and inputting it into the control device 306. Note that the correlation between the emission intensity and the processing amount was input to the control device 306 in advance. The photodetector 305 includes a band-pass filter that transmits only a specific wavelength, a photodetector, and an optical system that guides light to the photodetector. The measured emission wavelength is 440 nm, which is caused by the emission of SiF, which is an etching product. Based on the measured light emission intensity, the control device 306 controls the drive mechanism 303 to scan the processing tool 307. The drive mechanism 303 can scan the processing tool 307 in the horizontal direction in the paper plane and in the XY directions perpendicular to the paper plane. Further, it is also movable in the vertical direction in the drawing, and the distance between the processing tool 307 and the workpiece 301 can be adjusted.

  Next, details of the machining process will be described. The shape before processing of the workpiece was measured, and the shape to be processed was calculated from the difference between the shape before processing and the desired shape as shown in FIG. In addition, as shown in Fig. 3 (b), by processing a dummy workpiece with the same quality as the workpiece with the local processing tool, the processing shape with the local processing tool is normalized to the processing shape per unit volume. The processed unit shape was determined. Then, the shape to be machined was deconvoluted by a unit machining shape, and distribution data of a desired machining amount by a local machining tool was created as shown in FIG. The distance between the processing points is 4 mm, and the distribution data of the desired processing amount is data divided by a 4 mm square mesh in the XY plane.

In the processing, the active species jet was positioned at the center of the mesh of the distribution data of the desired processing amount, and stayed until the movement start condition described below was satisfied. A scanning method will be described with reference to the graph of FIG. Since the moving speed between the processing points is 50 mm / s and the acceleration is 1000 mm / s ² , the moving time between the processing points is 130 ms. Monitor processing amount of each processing point (current working point) Pi began at time t = t _i. In estimating the time change of the processing amount, the data of the processing amount was the data of the latest 50 ms, and fitting was performed with a quadratic function. Using the fitting function obtained here, the increment of the machining amount from the current time to 65 ms later was calculated as the machining amount V _{i, i + 1, i} of the current machining point P _i to be machined during the movement. Further, the increment of the machining amount from 65 ms to 130 ms later was calculated as the machining amount V _{i, i + 1, i + 1} of the next machining point to be machined during the movement. Using the calculated value of the processing amount, processing amount of the current working point P _i to be processed before processing point while moving in the current working point V _{i-1, i,} and _i, actually measured processing of the current processing point P _i the amount V _i, the processing amount V _i of the current working point P _i to be processed during the _movement, the sum of _{i + 1, i,} and the total processing amount of the current working point P _i. Then, at the time t = t ₂ when the total machining amount at the current machining point P _i becomes equal to or greater than the desired machining amount V _{i, f} , the machine moves to the next machining point.

  As a result of repeating the above scanning and processing the entire distribution data of the desired processing amount, the processing variation with respect to the desired shape could be suppressed to 19 nm or less. For comparison, when the machining amount at the current machining point coincided with the desired machining amount, a case where machining was performed by a method of moving to the next machining point was examined. As a result, machining variation was 36 nm.

  In the first embodiment, the movement speed and acceleration between the machining points are fixed, and the scanning is performed by modulating the machining amount at the time of starting the movement. However, in this embodiment, the movement at the time of starting the movement is described. The remaining machining amount with respect to the desired machining amount is fixed, and scanning is performed by modulating the moving speed between the machining points. Since the apparatus configuration of the present embodiment and the process of creating the distribution data of the desired machining amount are the same as in the first embodiment, the details of the scanning method will be described with reference to FIG.

In the processing, the active species jet was positioned at the center of the mesh of the distribution data of the desired processing amount, and stayed until the movement start condition described below was satisfied. The distance between the machining points is 4 mm, and the acceleration is 1000 mm / s ² . Simultaneously with the start of machining, monitoring of the machining amount is started, and when the machining amount at the current machining point becomes equal to or more than the value obtained by subtracting 1.18 × 10 ⁻² mm ³ from the desired machining amount, the next machining point is reached. We decided to start moving.

Monitor of the processing amount of the machining point _{P i} was initiated at a time _t = t _1. In estimating the time change of the processing amount, the data of the processing amount was the data of the latest 50 ms, and fitting was performed with a quadratic function. Using a fitting function obtained here was calculated required time T _i until processing of the current processing point reaches the desired processing amount. Then, the moving speed v _i between the processing points was determined so as to move 2 mm, which is ½ of the distance between the processing points, in the required time T _i . That movement speed _{v i is} a _{v i / 1000 × v i ×} 1/2 + (T i -v i / 1000) × v = 2 becomes _{v i.} Furthermore, using the fitting function, the increment of amount of machining after T _i until after 2T _i, are processed during the movement, processing amount V _i of the next machining _point, was calculated as _{i + 1, i + 1.}

In this way, the machining amount V _{i−1, i, i} of the current machining point to be machined while moving from the previous machining point to the current machining point is obtained, and the sum of the machining amount V _i of the current machining point and the actual machining point V _i is obtained. The machine moved to the next machining point at time t = t ₂ when the value was equal to or greater than the value obtained by subtracting 1.18 × 10 ⁻² mm ³ from the desired machining amount V _{i, f} . The moving speed at this time is v _i .

  As a result of repeating the scanning described above and processing the entire distribution data of the desired processing amount, the processing variation with respect to the desired shape could be suppressed to 19 nm or less. For comparison, when the machining amount at the current machining point coincided with the desired machining amount, a case where machining was performed by a method of moving to the next machining point was examined. As a result, machining variation was 36 nm.

  In this example, data obtained by measuring the temperature of the machining point was used in estimating the time change of the machining amount. The configuration of the apparatus used in this example is shown in FIG. The difference from the apparatus used in Example 1 is that a radiation thermometer 404 and a temperature detector 405 are installed in order to measure the temperature of the processing point. Since the process of creating the distribution data of the desired machining amount and the scanning method are the same as those in the first embodiment, only the process of estimating the time variation of the machining quantity and the process of calculating the machining quantity during movement will be described.

  Simultaneously with the start of processing, monitoring of the processing amount and the temperature of the processing point was started. In estimating the time change of the machining amount, correlation data between the temperature of the machining point and the machining speed input in advance to the control device were used. That is, the machining speed was obtained from the measured temperature of the machining point based on the correlation data between the temperature of the machining point and the machining speed, and the time change of the machining amount was estimated with a straight line with the machining speed as an inclination. Then, the machining amount obtained by multiplying the machining speed by 65 ms, which is 1/2 of the movement time between machining points, is machined while moving from the current machining point to the next machining point, and the machining amount at the current machining point and the next machining point. It was calculated as the processing amount of the processing point.

In this embodiment, scanning is performed while intermittently changing the moving speed. Since the apparatus configuration of the present embodiment and the process of creating the distribution data of the desired machining amount are the same as those of the first embodiment, description thereof is omitted. The boundary position between two adjacent machining points P _i and machining point P _{i + 1} is denoted by p _{i, i + 1} , and the position of the local machining tool at time t is denoted by p (t), and p _i−1,1 to p _{i ,} the scanning of the machining point in P _i with _{i + 1} of the area will be described with reference to FIG.

It is assumed that the local processing tool has entered p _{i−1, i} at a speed v ₀ at time t ₀ . The interval between p _{i−1, i} and p _{i, i + 1} is equally divided, and the processing amount is monitored while scanning the first one section to reach p (t _j ). Based on the time variation of the monitored machining amount, a fitting function, which is a function that estimates the time variation of the machining amount, is obtained. A time T _j required to reach the desired machining amount V _{i, f} at the current machining point P _i is obtained by the fitting function. The scanning speed is changed from p (t _j ) to the speed v _j at which p _{i, i + 1} is scanned at the required time T _j , and the next one section is scanned to reach p (t _{j + 1} ). A fitting function is obtained in the same manner as described above based on the change over time in the machining amount measured while scanning between p (t _j ) and p (t _{j + 1} ). By the fitting function, a required time T _{j + 1} to reach the desired machining amount V _{i, f} at the current machining point P _i is obtained. The scanning speed is changed from p (t _{j + 1} ) to the speed v _{j + 1} for scanning p _{i, i + 1} at the required time T _j , and the next one section is scanned to reach p (t _{j + 2} ). The above-described scanning is repeated to process the entire distribution data of the desired processing amount.

301 Workpiece 302 Holder 303 Drive Mechanism 304 Optical Fiber 305 Photodetector 306 Control Device 307 Processing Tool 311 Chamber 404 Radiation Thermometer 405 Temperature Detector

Claims (3)

A shape machining method for machining while sequentially moving a local machining tool to a plurality of machining points of a workpiece,
Measuring a machining amount by the local machining tool at each machining point of the workpiece during machining;
Based on the time change of the machining amount at each machining point, the machining amount of the current machining point by the local machining tool moving from the previous machining point to the current machining point, and the above-mentioned moving from the current machining point to the next machining point Calculating the sum of the amount of machining at the current machining point by the local machining tool and the amount of machining by the local machining tool at the current machining point;
A shape machining method characterized by starting movement of the local machining tool from a current machining point to a next machining point when a sum of the machining amounts exceeds a machining amount at a current machining point.   The shape processing method according to claim 1, wherein the processing amount is measured by detecting the emission intensity of the etching product.   The shape processing method according to claim 1, wherein a time change of a processing amount is estimated by detecting a temperature of the workpiece during processing.

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