TW200912252A - Method of predicting polishing end time - Google Patents

Abstract

The subject of the invention is to precisely predict the polishing end time under joule heat loss caused by not applying strong magnetic force lines to the fine wiring within a conductive film. In a polishing step of removing the conductive film of a wafer W, a two-dimensional planar inductor-type sensor 34 is made to approach the conductive film on the wafer for monitoring the magnetic force lines caused by the inductor-type sensor on the conductive film of the wafer. The conditions, such as the shape of the inductor, the distance between the inductor and the conductive film and the oscillating frequency, etc., are properly constructed to meet a certain extent to which the skin effect is capable of acting on the conductive film, so as to present the peak value of the magnetic force lines before the end of polishing. The magnetic force lines hardly pass through the conductive film before the end of polishing, and thus without worrying that the fine wiring within the wafer is not damaged.

Description

200912252 IX. Description of the Invention: [Technical Field] [0001] The present invention relates to a method for predicting a polishing end time point when polishing a conductive yt formed on a semiconductor wafer, in particular, In the inductor, a change in the characteristics of the oscillation frequency of the conductive film is detected, and a method of predicting the polishing state and the polishing end time point at which the polishing end time is predicted is detected. [Prior Art] [0002] It is understood that the process is such that an oxide film is formed on the surface of the semiconductor wafer, and a groove pattern corresponding to the wiring pattern is formed on the oxygen "needle plate (i) iKmhQgraphy) and (4), and then a film is formed thereon. There is a conductive film made of Cu or the like which is filled with a groove pattern, and the unnecessary portion other than the buried portion such as the groove pattern or the through hole portion in the conductive film is removed by chemical mechanical polishing. Wiring pattern. With the formation of the case, it is important to detect the conduction of the unnecessary portion, and it is important to remove the polishing end and to stop the process when the thickness is appropriately removed. When the electrical film is overgrown, the resistance of the wiring is increased, and when the polishing is too small, the wiring insulation is hindered. [0003] In the conventional art relating to the monitoring method of the grinding state, for example, Patent Document 1 discloses a method of monitoring the change in the thickness of the film on the spot. In the method of removing the conductive film from the substrate (the semi-conductive Zhao Jingyuan) by chemical mechanical polishing, the method of monitoring the thickness variation of the conductive film on the spot is made to contain iron. Oxygen tank type line 200912252 感 The sensor of the resonant circuit in series or parallel connection between the inductor and the capacitor is arranged close to the conductive film, and the scan output from the high frequency excitation signal source is set through the operating point. Applying 'by this' to the sensor by means of impedance means that when the sensor is energized, the oscillating current flows in the coil, creating an alternating electromagnetic field. This alternate electromagnetic field then induces a thirsty current in the conductive film. When the eddy current is induced to the conductive film, two effects are produced. First, the conductive film acts as a loss resistor, and the effect is on the resistance load of the sensing circuit, which lowers the amplitude of the resonance signal and lowers the resonance frequency. Second, when the thickness of the electroconductive thin film is reduced, the same effect as the metal rod disposed at the center of the coil of the inductor is extracted, thereby causing a change in inductance and a frequency shift. By continuously monitoring the frequency shift associated with the resonance peak of the sensor due to the thickness variation of the conductive film, the thickness variation of the conductive film is continuously detected. [0004] Further, other conventional technical aspects are known. There is an eddy current sensor as described below (Patent Document 2). Patent Document 2 is a prior art in which a eddy current is formed by a conductive film provided on a surface of a semiconductor substrate, and an eddy current sensor indirectly performs measurement of a film thickness in accordance with the eddy current. It is difficult to perform the problem of correct thickness detection (segment S GGG4)', and it is possible to provide a film thickness from a very thin film thickness formed on a semiconductor substrate to a thick conductive film. For the purpose of detecting the thirst current sensor (paragraph 0005) » [0005] Thus, in this document, there is a sensing coil disposed near a conductive film or a substrate having a conductive film of 200912252 (vortex) a current sensor) for supplying an alternating current signal of a certain frequency to the sensing coil to form an alternating current signal source for eddy current on the conductive film, and a detecting circuit for measuring a reactance component and a resistance component including the conductive film. The sensing coil includes an oscillation coil connected to the signal source, a detection coil disposed on the conductive film side of the oscillation coil, and a flat surface disposed on the opposite side of the conductive film side of the oscillation coil. Coil 'and so as to balance coil and the detection coil as a mutual connection for the inverter. Then, the resistance component and the reactance component detected by the detection circuit output a combined impedance, and the change in impedance is used to detect the film thickness variation of the conductive film in a wide range as a linear relationship. [0006] In the case of Patent Document 2, for example, an eddy current is generated in a thick film and the film thickness is measured. On the other hand, when the thick film is polished to reduce the amount of eddy current, the eddy current is reduced. Among the reduced components, the energy of the magnetic field is not simply consumed by the conductive film on the surface, and remains as it is inside the element below the conductive film, that is, the energy of the magnetic field that would otherwise be consumed in the conductive film. As the conductive film is removed, the inside of the element is allowed to be exposed to the energy of the excess magnetic field. [0007] Further, regarding other conventional techniques, for example, a thirst current sensor (Patent Document 3) is known. First, as a prior art, in paragraph (0012), the detection method of the polishing end point of the conventional eddy current sensor is that the oscillation frequency used in the eddy current sensor is about 7 MHz, which is small, so When the conductive film to be polished is thick enough, a large eddy current loss of 200912252 can be detected. However, when the polishing of the conductive film is performed and the film thickness is extremely thin, the magnitude of the eddy current loss is small, which is difficult in this case. A film thickness of, for example, 丨〇〇〇a or less is detected. In other words, the conventional eddy current sensor has a problem that the accuracy is insufficient in the detection of the polishing end of the polishing apparatus which is required to have the film thickness detection accuracy of the angstrom level because of the low oscillation frequency. [0008] Here, a method of simply monitoring the film thickness based on the magnitude of the eddy current of the magnetic field in the same manner regardless of the thickness of the film or the thickness of the film is disclosed. The technique of Patent Document 3 also changes the magnetic field lines formed by the sensor coils through the conductive film disposed on the entire substrate of the sensor coils, and alternately changes, as in the prior art. The eddy current is generated in the conductive film, and the eddy current is transmitted through the conductive film. The eddy current loss occurs in the middle of circulation, and the reactance component of the impedance of the sensor coil is reduced by the equivalent circuit (paragraph 〇008) β [0009], and the change of the oscillation frequency of the oscillation circuit is observed, accompanied by When the polishing is performed, when the conductive film is thinned, the oscillation frequency is lowered accordingly. When the conductive film is completely absent due to polishing, it becomes the oscillation frequency of the groove circuit itself, and after that, the oscillation frequency is slightly fixed. Therefore, by detecting this point, the end point of the chemical mechanical polishing of the conductive film can be detected (paragraph 0009). [0010] Further, as shown in Fig. 2 of the document, when the polishing of the conductive film is performed, the eddy current loss changes, and the equivalent resistance value of the sensor turns changes. Therefore, since the oscillation frequency of the oscillating circuit changes, the frequency-dividing signal is divided by the frequency-dividing circuit through the 12112252, or the subtraction is performed by the subtractor, and the signal corresponding to the frequency of the detected width is displayed on the monitoring. Device. Thereby, the transition of the frequency trajectory as shown in Fig. 2 (segment 0025) can be obtained. C 0011) Further, an eddy current sensor such as the following is known (Patent Document 4). In this document, please patent the brain! A full-current sensor is provided with a sensor coil disposed near a substrate on which a conductive film is formed, and an alternating current signal is supplied to the sensor coil to form an eddy current source in the conductive film. And a detection circuit for detecting an eddy current formed on the conductive film as an impedance seen by the sensor coil, wherein the full current sensor is characterized in that the sensor line is modified by a high permeability The inside of the receiving member formed by the magnetic material. [0012] Further, in the seventh application of the document, an eddy current sensor is disclosed which is provided with a sensor coil disposed adjacent to a substrate on which a conductive film or a conductive film is formed, The sensor coil supplies an AC signal, and a signal source for forming an eddy current in the conductive film and a detection circuit for detecting an eddy current formed in the conductive film as an impedance seen by the sensor coil. The eddy current sensor is characterized in that the resistance component and the reactance component of the impedance are displayed on a right coordinate axis, and the conductive is detected from an angle formed by a line connecting a coordinate of the impedance to a coordinate of a specified center point. The film thickness of the film. [Patent Document 1] Patent No. 2878178 (page 2 to page 7) Figs. 1 to 15). [Patent Document 2] Patent No. 3587822 (Page 3, FIG. 1 to FIG. 11) 专利 [Patent Document 3] Patent No. 39〇2〇64 (Patent Document 4) JP-A-2005-121616 [Invention [Problem to be Solved by the Invention] [0013] In the method for monitoring the thickness of the film of Patent Document 1, the sensor is used in a coil of a ferrite tank type which is wound in a directivity for making an electromagnetic field. A series or parallel resonant circuit of the inductor and the capacitor. Next, in the initial stage of grinding, 20Hz~40.  The scanning output of the frequency of 1 MHz is applied to the sensor, and the alternating electromagnetic field having directivity generated by the coil generates a leakage magnetic field line that penetrates the conductivity and is induced from the initial stage of the polishing. The film thickness corresponds to a large thirst current. [0014] In order to induce a large thirst current corresponding to the film thickness of the conductive film, a large alternating electromagnetic field, that is, a magnetic field line which is large enough to penetrate the conductive film, is required, and the thickness of the conductive film changes. The monitoring system is carried out using a thirst current caused by the polishing oil to the end of the polishing and the thinness of the conductivity. Therefore, it is necessary to pass the magnetic lines of force toward the thickness direction of the conductive film while monitoring the change in thickness. In the drawings of the patent document, the magnetic lines of force penetrating through the conductive film described in the entire portion of the conductive film are clear. [0015] 10 200912252 On the surface of the wafer at the initial stage of polishing, a generally non-scaling Cu film (conductive film) is located on the uppermost layer. In order to induce a full current on all of the scale-free Cu films, a very large leak magnetic field line is required. However, although the leakage magnetic field lines can induce eddy currents, they are all consumed as Joule heat in the form of so-called eddy current loss. This "Joule heat loss, for the most surface-free non-scaling Cu film, due to the small volume resistance, the heat is relatively low. The part which is small and has been internally wired has a small cross-sectional area and a large volume resistance, so that a large eddy current is induced by the magnetic lines of penetration, and as a result, a large Joule heat loss is locally generated. This occasion will develop into a part of the problem of wiring melting and disconnection. It becomes a state of so-called induction heating, which is particularly a phenomenon of causing sweltering inside. In particular, in the case of Cu wiring or the like, there is a case where Cu is heated to diffuse on the blocking film of Ta or the like after Cu is heated, or it may be caused by the breakthrough of the blocking film due to the occasion. [0016] In the case where a plurality of layers of wiring are applied to the surface portion of the wafer, not only the Cu film on the surface layer but also the wiring portion inside the processed portion may be partially warmed. Diffusion into the surrounding, or formation of P-type, n-type dopants in the semiconductor substrate and then diffuse and change the characteristics of the components in the substrate. Further, even when heat is not generated, when excessive eddy current is caused to flow through the fine wiring, electromigration may occur to cause disconnection. [0017] Damage to the component caused by the magnetic field invading the component can be explained as follows. In other words, in the method of Patent Document 1, an eddy current is formed in a portion of the conductive film (Cu film) on the surface in accordance with the invading magnetic field, and a repulsive magnetic field is generated depending on the eddy current. At the initial stage of the polishing, since the conductive film 200912252 J that passes through the covering surface prevents the magnetic field from entering the internal element, damage to the element is small. On the energy surface: the eddy current generated by the conductive film covering the surface is consumed as a Joule heat in the conductive film. Therefore, at the initial stage of the grinding, the internal components are protected from the partial magnetic field by the conductive film on the surface. [0018] However, when the polishing is performed to remove the film of the conductive film covering the surface, the magnetic field intrudes into the element without being alleviated. In the initial stage of polishing, although the energy of the magnetic field is consumed as Joule heat loss inside the conductive film on the surface, when the conductive film on the surface is removed by grinding, the energy consumed by the Joule heat loss is maintained as it is. When the conductive film of the extent that no thirst current is generated on the right side of the component side, the magnetic field remains as it is and is consumed in the external space, but in the presence of a conductive film of a certain size The ground generates eddy currents and causes disconnection. This is also caused by the structure of the element. However, when a magnetic field having a high directivity of the eddy current is intruded into the element by a conductive film having a thick surface as a whole, it is clear that a full current is generated everywhere and the adverse effect is caused. [0019] Further, in the method of Patent Document 1, a magnetic field is introduced into the conductive film to monitor the change in the amount of eddy current generated by the magnetic field to estimate the thickness of the film, in order to estimate the film thickness in this case, it is necessary to continue to generate Eddy current. The reason is that when the eddy current is not generated, the circuit system does not operate, and it is impossible to estimate the thickness of the change. Further, the prediction of the end of the polishing is also impossible, when it is impossible to estimate the thickness of the removed, the end point or the vicinity of the end point thereof is impossible. Therefore, in order to monitor the film thickness and perform end point prediction and end point detection, it is necessary to continuously form an eddy current. In the case where the polishing conditions are changed and the processing is performed at a time point of a predetermined amount of the residue near the polishing completion time point, it is difficult to grasp whether or not the predetermined residual film amount is present. It is possible to estimate from the change in the initial film thickness. Since the film thickness is uneven at the initial stage, the estimated amount of residual film may become uneven. Regarding the judgment near the polishing end time point, when the gap between the sensor and the electroconductive thin film slightly changes depending on the vibration of the polishing, the parasitic capacitance change of the entire sensor circuit system causes the resonance frequency to shift as a whole. Therefore, even if it is assumed that the threshold value is set and the setting of the polishing end point is determined when the resonance frequency is set, if the resonance frequency is shifted as a whole, the determination of the polishing end time point based on the setting of the threshold value becomes difficult. [0021] Thus, in the conventional method, in the monotonously and continuously increasing or decreasing the varying resonant frequency, even if the threshold is set to a certain value I, the gap between the sensor and the conductivity _ is slightly changed, Or what kind of dielectric is interposed between them, or there will be a case where the waveform itself moves up and down in parallel as a whole. As a result, the preset threshold does not make sense. Further, in the method of Patent Document 2 or Patent Document 3, the resonance frequency or the resistance component wheeling linearly decreases and changes, and when it is in the vicinity of the selection, the change in the decrease becomes gentle. However, the degree of change is not always slow, and the phase becomes very (4). What is the extent of the remaining material? 13 [ 0023] 200912252 And 'because magnetic lines are penetrated into the component, depending on the structure of the component' is not only a conductive film. There are also eddy currents or the like formed in other elements, so there is no case where the eddy current does not flow at all and becomes zero. Even if the conductive film is completely removed, a part of the eddy current flows through the wiring or the like formed in the element. Therefore, there is a case where the residual film thickness is also present. [0024] In the technique described in Patent Document 2 using an eddy current sensor, the monitoring of the change in the thickness of the conductive film is also observed, and the eddy current is observed from the initial stage of polishing to the end of polishing, and the patent The technique described in Document 1 is substantially the same. (0025) Further, in the above-described conventional technique for monitoring the thickness of the conductive film using an eddy current from the initial stage of polishing to the end of polishing, in order to cause an eddy current in the film, it is necessary to make it sufficiently strong to penetrate the film. The magnetic lines of force, the shape of the inductor is a three-dimensional shape in order to make the magnetic lines of force have directivity. Therefore, after the sensor is placed in the polishing apparatus or the like, the current flowing through the coil is increased, the power consumption of the power is increased, the power supply device is enlarged, and the wire is wound into a coil shape, and the cost is high. . Further, there is a problem that magnetic flux leaks to the periphery and noise is likely to occur. [0026] The eddy current sensor described in Patent Document 3 is that since the initial stage of the polishing, the magnetic field lines are electrically conductive, and the final (fourth) polar (four) current is generated, and the film thickness is changed from the full charge, and only the product is produced. In the hardware of a magnetic field that penetrates the degree of conductivity, a thirsty current cannot be formed and the object cannot be achieved. The region in which the conductive film is loaded and reduced to form the thirsty current 200912252 is monotonously reduced. Therefore, there is a behavior in which the oscillation frequency monotonously decreases, and the oscillation frequency is regarded as an end point and the portion is detected as the end point. . That is, the variation of the oscillation frequency in the calculation logic of the software used in the prior art refers to the change of the oscillation frequency from the decrease to the slightly certain change, for example, the vibration frequency of the vibration is In the case of a change in the point of change, it is difficult to detect the end point. [0272] Thus, the object of the present invention is that a strong magnetic line of force does not conform to the fine wiring formed in the conductive film, and as a result, the occurrence of eddy current caused by electromagnetic induction is suppressed, and the eddy current is induced. Joule heat loss is suppressed to a minimum. [0028] Another purpose is that there is no change in the gap between the sensor and the conductive film or the interposition of the dielectric substance such as the slurry, and the eddy current is totally shifted. The situation that becomes difficult to detect is changed. Even a fine magnetic field that does not penetrate the wafer of the device is sufficient to accurately predict/detect the polishing end time point, and instantly calculate the amount of residual film and the polishing rate to be removed. Etc., it is possible to correctly evaluate whether or not a predetermined conductive film has been properly removed. [Means for Solving the Problem] [0029] The present invention has been made in order to achieve the above object, and the invention according to the first aspect of the invention provides a method for predicting the end time of polishing, which is to supply a polishing stage or a chemical solution. In the grinding process, the processing tool such as the polishing crucible and the wafer having the conductive crucible are slid to perform the removal process of the conductive film. In the grinding process, the inductor is brought close to the conductive film on the wafer, and the inductor is monitored by the inductor. The magnetic lines of force are formed on the conductive film of the wafer, and the magnetic fluxes which change according to the broadening effect of the material of the conductive film are subjected to the polishing process of the wafer surface, and the amount of grinding is estimated instantaneously. 〇 [ 0030] In the conventional method, even if the conductive film is completely removed, most of the magnetic lines of force penetrate through the element, so that the fine conductive film existing in the element still flows a little **** noon current. Therefore, it is difficult to estimate a state in which the thickness of the conductive film after the complete removal of the conductive film is zero. In addition, since the wiring density varies depending on the wafer, the influence of the residual eddy current other than the conductive film is different. Therefore, it is difficult to define a state in which the conductive film is zero. [0031] In the present invention, there is a sharp inflection point due to the effect of the collective effect, and the position of the inflection point based on the skin effect is a conductive film that passes through the surface without being in the state of the element. The true film thickness is almost uniquely determined by the positive. For example, 'in many cases, the Ta film exists under the Cu film, but the current flowing in the skin effect according to the skin effect is on the surface of the pole, and in the material such as the Cu film to the Ta film which is a large change in conductivity. The effect of the skin effect on the Cl1 portion is dominated. Even with the Ta film, most of the magnetic field is not consumed and is reflected. [0032] According to the method of the present invention, the change in the thickness of the film is obtained in detail in the in-plane position of each wafer based on the change in the magnetic field lines characteristic of the sharp inflection point of the skin effect, and the respective thicknesses can be estimated in real time. Uneven film thickness, grinding 200912252 grinding rate, grinding shape and uniformity. [0033] Further, the change in magnetic field lines characteristic of the change is not based on the amount of change from the initial film thickness. It is notified as a sharp inflection point before the end of the polishing in which the residual thickness is based on the state of complete removal. Accordingly, even if the initial film thickness is not uneven, the residual film thickness can be stably monitored. [0034] Further, the amount of the correct residual film to be immediately monitored is detected by measuring the initial film thickness in advance or by the other initial film thickness values measured, and the amount of polishing can be calculated based on the result. Moreover, the polishing rate can also be calculated from the polishing time. [0035] The invention according to claim 2 provides a method for predicting a polishing end time point, wherein the polishing amount is estimated instantaneously, which is a residual film thickness, an average film thickness, a polishing shape, a polishing amount, an average polishing amount, and a grinding. Any of the unevenness of the removal amount, the unevenness of the residual film thickness, and the shape of the residual film. [0036] In the present invention, as the film thickness decreases, a change in the magnetic field line including the characteristic of the inflection point according to the skin effect is exhibited, which is not seen by the prior art and is changed by the characteristic magnetic field line. The residual film thickness average film thickness, the polishing shape, the polishing amount average polishing amount, the unevenness of the polishing removal amount, the variation of the residual film thickness, the shape of the residual film, and the like can be obtained. [0037] The invention described in the third paragraph of the Japanese Patent Laid-Open No. 3 provides a method for predicting the point between the end of the polishing and the 17 200912252, wherein the polishing amount is estimated for a plurality of portions in the wafer surface while polishing the wafer surface. [0038] In the present invention, in this case, the polishing uniformity can be immediately detected or predicted from the time difference of the waveform of the resonance frequency detected by each of the plurality of portions in the wafer surface. [0039] The invention of claim 4 provides a method of predicting a polishing end time point in which an inductor-based secondary element planar inductor is adjacent to the conductive film. [0040] According to this method, the directivity of the magnetic field of the quadratic planar inductor is not sharp, and the magnetic field which is moderately dispersed is imparted to the conductive film, so that it is difficult for the magnetic field to intrude into the conductive film, and the effect of the skin effect is remarkable. Therefore, according to the waveform of the feature, the film thickness unevenness at each position can be accurately estimated. In the same manner as before, the change in the initial film thickness is not based on the amount of residual film in a state in which the film thickness is completely absent, so that the end time can be stably obtained without depending on the initial film thickness. Residual film thickness. [0041] The invention according to claim 5 provides a method for predicting a polishing completion time point by sliding a processing tool such as a polishing pad and a wafer having a conductive film while supplying a polishing slurry or a chemical solution. In the polishing process for removing the conductive germanium, the inductor is brought close to the conductive film on the wafer, and the magnetic field lines formed by the inductor are monitored to cause conductivity on the wafer and the conductive film is used. The magnetic field line of the 200912252 is reduced by the decrease of the film thickness according to the polishing, and the full current of the conductive film is increased, and the eddy current is substantially reduced with the subsequent film thickness reduction. In the process, the state of the characteristic change of the magnetic lines of force caused by the conductive film is converted into the film thickness, and the amount of polishing is immediately estimated based on the relative unevenness. [0042] In this method, since the magnetic field lines caused by the eddy current formed by the reduction of the thickness of the crucible cause a characteristic change due to the collective effect, the time for monitoring the portion passing through the characteristic change can be followed by Time is uneven, and the amount of grinding is instantaneously obtained during processing. [0043] The invention according to claim 6 of the present invention provides a method for predicting a polishing end time point, in which a processing tool such as a polishing pad and a wafer having a conductive film are slid while supplying a polishing slurry or a chemical liquid. In the polishing process for removing the conductive film, the inductor is brought close to the conductive film on the wafer, and the magnetic lines of force formed by the inductor are monitored on the conductive film of the wafer and the conductive (four) material is used. The magnetic field lines that change according to the "factor" of the factor are caused by the decrease in the film thickness due to the polishing, which causes the full current of the conductive film to increase, and the eddy current is substantially reduced as the film thickness thereafter decreases. The elapsed time when the change portion of the characteristic of the magnetic field line caused by the conductive film is obtained at a plurality of positions in the plane of the wafer, and is instantaneously obtained in the processing according to the unevenness of the elapsed time at the plurality of positions The amount of grinding is taken [0044] According to the invention of the present invention, except for the use of the invention 200912252 described in claim 5, the monitoring is carried out through a plurality of positions in the plane of the wafer. Part of the time change of its characteristics, which can be based on elapsed time uneven, instantly strike a comprehensive amount of grinding. [0045] The invention according to claim 7 provides a method for predicting a polishing end time point by sliding a processing tool such as a polishing pad and a wafer having a conductive film while supplying a polishing slurry or a chemical solution. In the polishing process for removing the conductive film, the inductor is placed in a plurality of different track positions with respect to the wafer and is close to the wafer, and the magnetic field lines formed by the inductor are used to monitor the predetermined wafer surface. The magnetic field lines of the conductive defects caused by the plurality of positions in the plurality of positions, and the change portions of the magnetic lines of force caused by the conductive film are obtained at a plurality of positions in the wafer surface according to the collective effect of the conductive film The elapsed time is converted into the unevenness of the amount of polishing removal, or the amount of each film thickness at a plurality of positions is converted from the rate of change of the waveform, and the amount of polishing is immediately obtained during processing based on the unevenness or the amount of film thickness. [0046] In this method, the unevenness of the amount of polishing removal or the thickness of each film at a plurality of positions can be obtained by the elapsed time from the portion where the magnetic field lines which are characteristic of the conductive film are changed, and the precision can be obtained. Good to monitor the amount of grinding. [0047] The invention according to claim 8 provides a method for predicting a polishing end time point, wherein the measuring means of the magnetic field line change caused by the set effect of the conductive enthalpy is an eddy current in the conductive crucible Measuring or measuring the mutual inductance generated by the eddy current generated by the conductive film, 20 200912252 or measuring the change in inductance in the sensor circuit of the inductor based on the mutual inductance of the conductive film, or the sensor The impedance change of the circuit system is measured, or at least one of the measurement of the resonance frequency of the sensor circuit is measured by connecting the high frequency inductor and the capacitor in parallel and oscillating. [0048] In the prediction method of the present invention, as the film thickness decreases, changes in magnetic lines of force including characteristics of the inflection point according to the skin effect appear, which are not seen in the prior art, so that the change is based on the magnetic line of force. Various values (eddy current, mutual inductance, impedance change, etc.) can predict the amount of grinding. [0049] The difference between the present invention described in the first to eighth aspects of the above-mentioned patent application scope and the prior art is described below. First, in the present invention, it is not a measure that positively induces eddy currents in the film to perform thickness measurement. The effect of the skin effect of the conductor film on the magnetic field is to prevent the magnetic field from invading into the conductive film. In the vicinity of the film thickness removal, it is detected that a part of the magnetic field leaks from the conductor film and then changes its shape. The predicted end point β [0050] Further, the eddy current generated by the conductive film on the surface is reduced as much as possible to cause the magnetic field energy consumed by the portion of the element existing under the conductive film. Before the conductive film is removed, the total eddy current is gradually reduced as the film thickness is reduced. Since the energy of the magnetic field affects the internal components, it is possible to prevent the magnetic field from entering the inside of the element to reduce the energy of the magnetic field. [0021] In Patent Document 2, the sensor line 21 200912252 is used for detecting the thickness of the conductive film, and includes an oscillation coil connected to the signal source, a detection coil disposed on the conductive film side of the oscillation coil, and And a balance coil disposed on the opposite side of the conductive film side of the oscillating coil, and the varistor is connected in a series circuit in which the detecting coil and the balanced coil are connected to each other in an inverted manner, and there is no detected object In the case of the conductive film, the output of the series circuit can be adjusted to zero, the combined resistance is outputted from the resistance component and the reactance component detected by the detection circuit, and the film thickness of the conductive film is changed by the change of the combined impedance. In a wide range, it is detected as a linear relationship. [0052] However, in the present invention, as the inductor, it is not necessary to have three coils of the oscillation coil, the detection coil, and the balance coil. Moreover, the coils are not stacked in a three-dimensional manner in a stereoscopic manner to monitor changes in their magnetic lines. Instead, there is only one turn that becomes the inductor, and it is constructed as a 2-dimensional plane. Further, in Patent Document 2, a series circuit in which the variable resistor is connected to the detection coil and the balance coil 反 is connected in reverse, but in the present invention, the resistance of the variable resistor or the like is not Oh. The oscillating circuit of the present invention combines a capacitor and an inductor in parallel. [0054] Further, according to the above publication, the film thickness changes from the resistance component and the reactance component to the combined impedance, and the resultant impedance forms a straight line relationship with respect to the film thickness variation in a wide range, and the film thickness is obtained from the change relationship of the straight line. . However, in the present invention, 'the purpose is not to measure the film thickness in a wide range. The person who correctly predicts the end point of the polishing according to the change in the waveform of the feature before the end time of the grinding. 22 200912252 [0055] Further, the change in the waveform of the feature before the polishing end time is not a slight straight line change. According to the effect of the skin effect, there is a sharp change point. The person who correctly predicts the polishing end time point based on the feature points such as the change point and the sharp change rate before and after. [0056] Further, in accordance with the above publication, in paragraph 0027, the change in the amount of resistance relative to the change in the thickness of the conductive film is not shown in the circle 7 (b) (Attachment 1). The relationship between the change in the resistance amount and the thickness variation is that the resistance component R changes as the thickness changes from thick to thin. That is, in the region (a) of the extremely thin film thickness, the output of the resistance component R changes linearly, and when it becomes the region (b) of a certain thickness, the change in the resistance component R saturates, and then the film thickness becomes thick. The area (c) +, the output of the resistance component R is lowered. Here, in the case of the copper film, the point (a) represents about 1 〇〇〇 λ, the point (b) represents 2000 A to 3000 A, and the point (c) represents 5 〇〇〇 A or more. [0057] However, the behavior of the resistance component such as the thickness of the conductive film becomes larger depending on the film thickness, and then becomes smaller, and the behavior of the circle is shown in the balance of the resistance component and the electric k into the f" The phase is different from each other, and the action is not completely different according to the invention according to the effect of the broadening effect. [0058] In the present invention, the process of "incorporating the magnetic field line from the magnetic field line into the conductive crucible" _The force line leaks as the film thickness decreases, and then, when the magnetic field lines penetrate to a certain extent, the so-called full current is reduced according to the film product of the film), based on the reduction of the series of effects, the sharp change point The system 23 200912252 is generated. The inflection point is not simply the one that affects the frequency. As shown in the example of changing the inductor distance and the inductor diameter shown later, even the same frequency 'is still due to the inductor The diameter or the distance between the inductor and the conductive film changes the directivity of the magnetic field, and the magnetic field changes greatly as the intrusion behavior in the conductive film. The film thickness at the time of polishing decreases with respect to an inductor diameter and an inductor distance. The process has an inflection point based on the skin effect, but in the case of, for example, an inductor size of 1/1000 and an inductor distance, there is a change based on the agglomeration effect in the process of reducing the film thickness during grinding. The case of the curved point. This is clearly indicated, not only the frequency at that time in the shape of the inductor or the distance, etc., the directivity change of the magnetic field, depending on the skin effect, the intrusive characteristic of the magnetic field on the conductive film changes, In the present invention, a process of changing the film thickness by polishing from a state in which the magnetic field does not enter the conductive film to a state in which the magnetic field is continuously invaded is formed. The point at which the conductive film is removed is accurately predicted by the change in state. [0060] Thus, the change in the resistance component according to the broad effect in the present invention is in phase relationship with the resistance component and the reactance component from the conventional technique. The change in the resistance component is completely different. [0061] And 'in accordance with Patent Document 3 (Patent No. 3902064), first, in the paragraph of the prior art 〇〇 1 2. In the detection method of the polishing end point of the conventional eddy current sensor, since the oscillating frequency 24 200912252 used by the eddy current sensor is about 7 Μ 1 较小, the conductivity of the object to be polished 骐In the case of a relatively large thickness, a large eddy current loss can be detected. However, when the conductive film is polished to make the film thickness extremely thin, the magnitude of the eddy current loss is small, and in this case, for example, about 1000 A or less. The film thickness detection system becomes difficult. That is, since the conventional current sensor has a low frequency of vibration, it is detected on the polishing end point of the polishing apparatus which requires the film thickness detection accuracy of the angstrom level. There is a problem that the accuracy is insufficient. [0622] It is also revealed that a thick film thickness or a thin film thickness can also infiltrate a magnetic field into a film, and simply monitor the film according to the magnitude of the current caused by the magnetic field. Thick method. [0063] However, in the present invention, when the conductive film is thick, the thickness of the conductive film is not considered to be a problem. The magnetic field does not intrude into the conductive (4) due to the effect of the broadening, and therefore is not required. A large full current is detected. In addition, in the case where the film thickness is gradually reduced to the extent of the deletion, even the non-directional magnetic field 'because the through-partial conductivity 形成 becomes full with the decrease of the material: the flow generates a repulsive magnetic field, so the accuracy can be Good land check out. It is not intended to measure the film thickness even with a thick film thickness, because the behavior of the (4) in the vicinity of the sexually-removed position is well predicted. The vibration frequency of [0064] is grasped as the frequency: the time gradient of the full-current sensor and the time gradient of the frequency and the calculation of the oscillation frequency 'money, and the determination of the grinding end point according to the characteristic point . Fig. 25 200912252 5 ( a) shows the trajectory of the time t of the oscillating disk frequency from the time of the cat, and the circle 5 (b) shows the trajectory of the differential value (Attachment. [ 0065] The action system of this vibration frequency The behavior of the vibration frequency monotonously decreasing is shown. The judge X of the polishing end point is performed at the lowest point of the monotonic reduction point of the vibration frequency, and the change point in the reduction of the green adjustment is found by the differential waveform to determine the end point. ^ [0066] However, in the context of the present invention, such a vibration frequency is different. That is, in the present invention, the process of reducing the film thickness by grinding, the vibration frequency is based on the skin effect of the conductive film. And as the film thickness decreases, it temporarily rises, then falls again, and has a peak near the end point. This behavior is caused by the process of making the magnetic field from invading to invading the conductive film according to the skin effect. The behavior shown in the prior art example is significantly different. [0067] Moreover, the present invention detects the portion of the inflection point that rises and falls and the feature near the inflection point, and predicts the end time of the polishing with high precision. Point. Further, in Patent Document 3, the spiral-shaped sensor coil is disposed to be orthogonal to the substrate, but in contrast, in the coil of the present invention, a planar inductor is disposed in parallel with the substrate. In the configuration of the device, it is also significantly different. [0069] Further, as shown in the paragraph 〇〇32, in the patent document 3, it is shown that the resistance component increases once and decreases with the decrease of the film thickness. However, 26 200912252 is a behavior that appears to be non-integrated. In the circuit shown in the picture, the inflection point caused by the balance of the resistance component and the reactance component in the phase difference is also known as ' The inflection point in the present invention is completely different from such an inflection point. As described earlier, the 'inflection point varies greatly depending on the size, shape, or distance of the conductive film to the coil, depending on the setting. There is also a case where the behavior according to the skin effect is not seen even in the high frequency band. [0070] In the present invention, the conductivity, the magnetic permeability and the frequency, the shape of the inductor, and the shape of the conductive film are appropriately set. Electricity The distance between the sensor and the conductive film, etc., in the process of reducing the film thickness by polishing, the state in which the oscillation frequency has an inflection point according to the skin effect, and the end of the polishing is accurately predicted according to the characteristics of the waveform. [Invention Effect] [0071] The conductive film on the circle monitors the domain that changes according to the f/ϊ effect of the conductive film to make the inductor close to the crystal

Patent Application No. 1 [0072]

Unevenness of polishing removal, average thickness, unevenness of polishing I: residual 骐 27 200912252 Any data such as thick unevenness and residual shape improves polishing accuracy. [0733] In the invention described in the patent document S1帛3, the waveform of the resonance frequency is detected simultaneously at a plurality of locations in the wafer surface, and the time difference of the waveform of the resonance frequency can be immediately detected or The grinding uniformity is predicted. [0074] According to the invention of claim 4, the use of the secondary element planar inductor makes it difficult for the magnetic field to enter the conductive film, and the effect of the skin effect becomes remarkable, and the film thickness unevenness can be accurately estimated. Residual film thickness and the like. [0075] According to the invention of claim 5, since the skin effect caused by the eddy current caused by the decrease in the film thickness causes a change in characteristics, it is possible to monitor the time passing through the change of the characteristic. The amount of grinding is accurately determined in real time. [0076] The invention according to claim 6 is characterized in that the plurality of positions in the wafer surface are monitored for the time when the change in the characteristics of the magnetic lines of force is monitored, and the amount of polishing is determined by the unevenness of the elapsed time. Thereby, the amount of grinding can be obtained at a higher speed. [0077] The invention according to the seventh aspect of the invention is the method of obtaining the unevenness of the amount of polishing removal or the film at a plurality of positions by the elapsed time when the portion of the magnetic field line which is characteristic of the conductive film is changed. The thickness is used to monitor the amount of grinding with high precision. [0078] 28 200912252 In the above-described invention, since the magnetic line change including the characteristic of the inflection point according to the specific skin effect is exhibited, the invention described in claim 8 can be eddy current, mutual inductance. One or a plurality of kinds of data such as impedance change, resonance frequency change, etc., predict the amount of grinding with high precision. BEST MODE FOR CARRYING OUT THE INVENTION [0079] The present invention utilizes the following method for predicting the end of polishing time to make strong magnetic lines of force less than the fine wiring formed in the conductive film, and as a result, suppresses electromagnetic induction. The occurrence of the eddy current suppresses the Joule heat loss caused by the eddy current to a minimum, irrespective of variations in electrical conditions caused by variations in initial thickness or variations, etc. The purpose of grinding the end time point. This method is characterized in that the inductor is brought close to the crystal in a polishing process in which a polishing tool or a chemical solution is supplied while a processing tool such as a polishing pad is slid with a wafer having a conductive film to remove a conductive film. The conductive film on the circle monitors the magnetic field lines formed by the inductor and causes the magnetic field lines on the conductive film of the wafer to change depending on the skin effect of the conductive material. The surface is ground and the amount of polishing is estimated instantaneously. C. Example 1] [0080] The 化学1 display chemical mechanical polishing apparatus 1 is mounted on a disk-shaped stage 2 on a drive mechanism 4 using a motor 3, and a polishing pad 5 is attached to the upper surface of the stage 2 ^ The polishing head 6' disposed above the platform 2 and displaced from the center of rotation of the platform 2 is a disc shape having a smaller diameter than the platform 2, and 29 200912252 is mounted with a wafer to be polished in the grinding process. The abrasive liquid or slurry is dropped from the liquid supply device (not shown) onto the upper surface of the polishing pad 5 'the polishing head 6 is lowered to the height of the wafer W contacting the polishing pad 5' and the stage 2 and the polishing head The 6 series are rotationally driven to polish the polished surface (bottom) of the wafer w. A planar inductor-type sensor 34 is embedded in the surface of the stage 2 below the polishing pad 5. Each of the stages 2 is rotated, and the inductor-type sensor 34 is passed through a wafer mounted on the polishing head 6. Below.囷2 is a block diagram showing a circle 'circle 2 (a) of a configuration example of the prediction/detection device 33 at the polishing end time point, and 圊 2 (b) is a view showing another configuration example of the planar inductor.圊2(c) is a cross-sectional view of a planar inductor of circle 2(b). The oscillation circuit 35 of the main body of the high-frequency inductor type sensor 34 in the prediction/detection device 33 constituting the polishing end time point is a planar inductor 36 which is a quadratic element of the inductance L, and is connected in series as a capacitor c. The lumped constant current capacitor 37 constitutes an LC circuit. The planar inductor 36 is formed on a substrate 36a made of an insulator or the like, and is formed into a meander shape by using a conductive material such as Cu. [0082] The planar inductor 36 has a spiral shape as shown in FIG. 2(a), and like the planar inductor 41 shown in FIG. 2(b), the dome substrate 4a may be formed in a square shape. . Also, it can be used as a circular spiral. The planar inductors 36 and 41 of the secondary element are formed by forming a conductive film of Cu or the like on the substrates 36a and 41a made of an insulating material such as glass epoxy or paper phenol, and then forming them by means of etching or the like. The line width is made to be extremely fine, and the overall shape is also as shown in Fig. 2 (c), which can be miniaturized into a square 30 200912252 with a side of 23 mm. Further, by miniaturizing the planar inductors 36 and 41, a minute magnetic field can be efficiently generated, and the magnetic field is not deeply penetrated inside the conductive crucible 28, and the end point at which the conductive film 28 is removed can be accurately detected. In the vicinity of the change behavior [0083] The output signal from the oscillation circuit 35 is input to an amplifier 38 composed of an operational amplifier or the like, and the output of the amplifier 38 is input to a feedback network 39 composed of a resistor or the like. The output signal of the feedback network 39 is positively fed back to the planar inductor 36, thereby constituting the oscillation circuit 35 including the planar inductor 36. [0084] The oscillation circuit 35 is basically shown in the configuration example of FIG. 3, and the vibration plate frequency f is as shown in (Expression 1), and the inductance L of the planar inductor 36 and the lumped constant capacitor 37 are formed. The oscillation circuit of the Kepi type determined by the capacitor C0" [0085] [Expression 1]

[0086] The output terminal of the aforementioned amplifier 38 is connected to the counter 4〇. From the counter 40, a detection signal indicating a thickness reference point, which will be described later, and the like are output to the outside in a digital manner. By transmitting the detected signal digitally, the effects of noise and output attenuation are prevented. Further, the management ease of the film thickness data can be obtained. 31 [0087] 200912252 By arranging the oscillation circuit 35 of the high-frequency inductor type sensor 34 and the counter 4〇 for monitoring the frequency of the vibration (resonance) of the high-frequency inductor type sensor 34, the oscillation circuit 35 and the frequency measurement are performed. The wiring/wiring portion between the devices 40 forms a distributed constant circuit to prevent the inductance or the capacitance from becoming unnecessarily large, so that the accompanying conductivity near the high-frequency inductor type sensor 34 can be accurately detected. The change of the magnetic field line. [0088] The prediction/detection device 33 at the polishing completion time point is a component other than the planar inductor 36, and the circuit is c (integrated circuit) and is housed in the package 33a. The planar inductor 36 is covered with a thin insulating film and fixed to the surface of the package 33a. When the prediction/detection device 33 at the end of the polishing end of the encapsulation is assembled to the aforementioned chemical mechanical polishing device!, as shown in FIG. 1, the planar inductor 36 is assembled to be the surface portion of the wafer w. The conductive film is opposite to the crucible. [0089] Further, the lumped constant capacitor 37 constituting the oscillation circuit 35 has a variable capacitance. The high frequency inductor type sensor 34 has an oscillation frequency selectable within the range of the oscillation frequency band. [0090] In the present embodiment, the film thickness reference point to be described later is detected in accordance with the change in the magnetic field line in the case where the conductive film 28 during polishing has a film thickness corresponding to a predetermined skin depth δ. The predetermined skin depth δ in the conductive film 28 is determined by the material of the conductive film 28 and the vibration frequency ί of the high-frequency inductor type sensor 34 (Expression 2). [0091] 32 (2) 200912252 [Expression 2] δ yj mm .. [0092] ω = 2πί, [0093] β is the permeability and σ is the conductivity. Further, the degree δ can be made smaller than the initial film thickness of the predetermined conductive film 28, and the high-frequency electric enthalpy is selected in such a manner that the electric film 28 _ thick red is polished at the end of the polishing process except for the portion other than the buried portion. In the case where the material of the conductive film 28 to be polished and removed is Cu, the vibration cup of the type sensor is selected to have an oscillation frequency band of 20 MHz or more. [0094] Here, the "film thickness corresponding to the depth of the skin" and the "change in the magnetic field line generated by the broadening effect" are described using (a) to (4) of Fig. 4, and the 圊4 system shows the electromagnetic simulation. The magnetic field generated by the coil is a result of what kind of orientation is arranged on the conductor film (the arrow - below the respective circles in FIGS. 4(a) to (4)). This is the case where the maximum turbulence is displayed... (4) The vibration from the sensor is: and the film thickness of the conductor film is 0.2 " m'. Figure 4 (b) The vibration frequency from the sensor is 1 MHz. When the film thickness of the conductor film is 1/m, Figure 4(c) shows that the oscillation frequency from the sensor is side and the film thickness is 〇, 2, and Figure 4 (d) is from The oscillation frequency of the sensor is 4 〇ΜΗζ and the film thickness of the conductive film is 丨Vin. [0095] The electromagnetic simulation is set such that the inductor for forming a magnetic field is a planar inductor having no directivity. The film thickness corresponding to the skin depth of the Γ refers to the film thickness of the magnetic field change caused by the r-wide effect of the sensor. 33. The sensor is 33. The 200912252 vibration frequency is 1 MHz, and the film is present on the lower side of the coil. The magnetic lines of force are oriented in the longitudinal direction. At this frequency, even if the film thickness & 1//〇] and 〇2 vm' magnetic field lines pass through the conductor film (圊4(a), 囷 is in the conductor film through which the magnetic flux penetrates, as in the conventional In the example, the eddy current generated in the inside of the conductor film is reduced with the decrease in the film thickness. Therefore, in the case of 1 MHz, the effect of the broadening effect does not appear because of the following film thickness. "The thickness of the corresponding skin depth" is at least a film thickness thicker than l#m. [0096] In contrast, the magnetic field line on the surface of the conductor is obviously horizontal when the oscillation frequency of the sensor is 40 MHz. In the case where the film thickness is 1 β m, it hardly enters the inside of the conductor (Fig. 4 (d)). e is compared with the case where the previous oscillation frequency is 1 MHz and the film thickness is 1/zm (Fig. 4 (b)). It can be seen that the direction of the magnetic lines of force entering the conductor film is different. [0097] However, when the oscillation frequency is 40 MHz and the conductor film is as thin as (圏4 (c)), only a part of the magnetic lines of force are directed toward the inside of the conductor film. It shows that even if the conductor film is Cu', when it becomes a certain thinness, a part of the magnetic force It will penetrate through the conductor film. [0098] In the case of the alternating magnetic field line of 40 MHz, the penetration state of the magnetic field line in the film is changed corresponding to the effect of the broadening effect. In the case where the film thickness is 1/zm or more, the magnetic field lines are hardly penetrated. Therefore, in this case, when the magnetic field is penetrated or not penetrated, the corresponding 34 200912252 The thickness of the skin ice can be about 1 / m. It can be seen that when the vibration frequency is set to 40MHz, when the planar inductor is used, the magnetic field lines hardly enter the Cu conductor film with the thickness of lvm. 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 In the calculation, when the film thickness is 1 V m, the magnetic field lines are enough to enter the conductor film, but since the magnetic field lines are not directional due to the use of the planar inductor, the actual oscillation frequency is 40 ,, even if the film thickness is Lym The magnetic field does not intrude into the conductor film due to the skin effect. As the conductor film becomes thinner, a part of the magnetic lines of force enter the conductor film, causing a little eddy current. Therefore, the eddy current is not actively used to determine the film thickness. However, the magnetic flux which is slightly leaked/penetrated by the skin effect at the thin film thickness near the end point is used, and the end point of the conductor film can be monitored by the inflection point (maximum point) of the mutual inductance in the conductor film. The film thickness state is nearby. [0100] This mutual inductance also corresponds to the impedance component of the primary side coil. When the impedance change of the coil circuit system is obtained, the relationship between the eddy current change caused by the conductor film and the coil side impedance change is obtained. In the case where an equivalent circuit as shown in Fig. 5 is formed, each component is directly set, and the circuit equation is expressed by Equation 3. [0101] [Expression 3] 35 200912252 f ί ^·2Νί//.—¥Μ Μ + + ¢//.13⁄4^^ II 12 (3)-(4 [0102] Here, il and i2 are respectively The current flowing through the primary side and the secondary side is applied to the coil on the primary side, and the alternating voltage ω having a certain vibration frequency is expressed as [0103] [Expression 4] / 丨 = Re(/〆) /2=Re(/2^) v = KQ(Vej0)l) [0104] and (Expression 3) and (Expression 4) are expressed as follows. [0105] [Expression 5]

Rx + jmL joM X ―-^ V jcoM R2 + jaL2 A 0 ·· · [0106] The solution of this number is as follows. [0107] [Expression 6] J __ 尺 2 + J·1L2__ 36 200912252 (/?, + j〇) Lx ) (R2 + j〇) L2) + co2M2 ^ [0108] The impedance system seen from the coil side It becomes the following. [Expression Ή R2+ jc〇L2 τ + ιω L ^_^2ω2Μ2 Z = — = i?, + jmLx + —

/. /?. 4- irnT

[0109]

The change in the real part of the impedance of the system. [0110] Fig. 6 shows the results obtained by the 2-dimensional electromagnetic simulation for the film thickness dependence of the real part of the impedance in the case where the planar inductor is used. In the case of 4 〇 MH z, there is an inflection point below G.lp, and then the impedance is drastically reduced. In the case of 1 MHz, the 3J* knowledge system is monotonously reduced depending on the film thickness. From this, it can be seen that the point of variation such as this one is first manifested by the frequency of the processing. Further, the occurrence of such a change point is understood to be caused by the influence of the widening effect as shown in Fig. 4 from the change in the direction of the magnetic line. [0111] 37 200912252 However, if the frequency is set to 40 MHz and the inductor shape is a planar sensor, it is not necessary to show the inflection point depending on the effect of the skin effect. As an example of this, in the case where the planar inductor is sufficiently close to the conductive film, it is confirmed by simulation of the quaternary finite element as in Fig. 4 . [0112] Here, the planar inductor is made closer to 1/1 比 than the previously shown distance and is set to 2.4//1 Π, and the size of the coil is also calculated as the radius n ^^ of 1/1 。. When the frequency of the coil is 4 〇 MHz, the conductor film is Cu and the film thickness is 1 A m, and even after the calculation, the film thickness of 1 β m is different from that of 圊4. Through. However, when the frequency is raised to 1 Ghz, the magnetic lines of force become almost opaque (the illustration is omitted [0113]. The circle 7 shows the case where the coil diameter is 1/1 〇〇〇, the coil turns and the conductive film distance is 1/1000. In the middle, the real part of the coil side impedance changes. It is known that even the frequency of 疋40MHz does not have an inflection point. When the frequency is raised to 1 ghz, an inflection point is generated around 1 // m. This is the magnetic field previously entering the conductor. In the orientation, it can be known that the inflection point is generated due to the effect of the collective effect. [0114] ' From the above experimental results, it is known that when the inflection point is formed due to the effect of the broadening effect, the frequency is not set high alone. It is also possible to properly maintain the distance between the coil and the conductive film or the size of the coil by using a planar inductor. Moreover, the conductivity and permeability of the film to be polished, etc., are caused by the physical properties of the material. The waveform of the case where the tungsten is polished in the same manner is clear. [0115] 38 200912252 Therefore, in order to utilize the so-called magnetic lines to intrude/not intrude into the conductive crucible according to the broadening effect, it is possible to appropriately select The frequency, the shape or size of the inductor, the distance between the inductor and the conductive film, the conductivity of the conductive film, and the magnetic permeability. It is found that the inflection point set to be affected by such a skin effect can be seen in the grinding. In the vicinity of the end point, a new method of predicting the calculation point of the inflection point and accurately predicting the end point of the polishing is set as the gist of the present invention. [0116] Secondly, the actual application of the method for predicting the end time of polishing is performed. Figure 8 shows an example of the relationship between the inductor-to-wafer track on the platform, the resonant frequency waveform in the A-to-_E & wafer. The resonance is not shown here. The peak of the frequency appears at the earliest point c, the B point and the 〇 point are followed, and the A point and the point become the slowest, belonging to the center of the wafer. The grinding rate of the point is the fastest, and the point A of the outer circumference is E point is slow. Fig. 1 shows the amount of polishing from time point 1 and time point 2 in Fig. 9 to point E. The shape of the wafer is known from the shape of the curve connecting the points (residual film shape [0117] Figure 11 shows the predicted side of the grinding end time point using the present invention. The reference waveform of the method for conducting the Cu film has a peak of the resonance frequency at a thickness of 710 。. As shown in the figure, if the corresponding film thickness is obtained for each position of the reference waveform in advance, the rate of change of the waveform actually obtained is obtained. The residual film thickness at each position is known. [0118] Further, the unevenness of the residual film is obtained instantaneously from the unevenness of the film thickness at each position for a predetermined period of time, wherein in the following formula, f丨 is the thickness of the position at 2009 3912252. [0119] [Expression 8]

[0120]

The situation is not uniform (Nonunif) [0121] [Expression 9]

Nonunif = 〇〇 (%) [0122] Further, in other methods, the film thickness can be removed by subtracting the residual thickness from the initial film thickness, and the unevenness can be obtained by removing the unevenness of the film thickness. [0123] ° or "The unevenness of the amount of polishing may be obtained from the time when the predetermined rate of change (a predetermined amount of polishing) has been reached. [0124] [Formula 10] £ / : The film thickness at the position/removal (·(: the predetermined honing amount at the position of the predetermined change rate at the position/the amount of honing of X is 40 [0125] 200912252 and From (Expression 8) and (Expression 9), the unevenness of the polishing amount can be obtained. 0 [0126] In addition, in FIG. 1, it is shown that an inductor type sensor 34 is disposed on the upper surface of the platform 2. For example, as shown in FIG. 2, a plurality of inductor-type sensors 34 are arranged in a radial direction on the top of the platform 2, and a polishing pad (not shown) is attached to the platform 2, and is simultaneously monitored on the wafer. The waveform of the resonance frequency at each position may also be used. In this case, the deviation of the waveform of the resonance frequency detected from each of the plurality of inductor-type sensors 34 can immediately detect or predict the polishing uniformity. In the above, the polishing end point prediction method of the present invention is described. The characteristic change of the waveform of the resonance frequency related to the polishing end point prediction is not limited to the inflection point 'including the rising start point, the rising rate', the predetermined amount of rise, and the rise. Detection change to the rate of change of decline, etc. Items of all the features included in the resonance frequency waveform used. [0128] Finally, in order to enumerate the parts of the present invention which differ greatly in composition from the conventionally known examples shown in the foregoing, the following differences can be cited: I does not use an inductor that shapes the magnetic field such as the fertiliser, but uses a non-directional magnetic field, and actively removes the magnetic field from the 2-dimensional planar inductor in the conductive film at the initial stage of the polishing; Set the frequency to the temperature at which the skin effect can be applied. 3. Consider the shape or size of the primary inductor, and the conductive film of the inductor and the removed object. Consider conductivity (IV) Conductivity and permeability. 200912252 The degree to which the skin effect can be properly applied; and 4. Consider the critical depth of the intrusion of magnetic lines of force based on the material of the film to be polished, and set the distance between the inductor, the frequency, and the inductor to the conductive film. [0129] It is understood that each element of the state setting device can be visualized by the influence of the skin effect, and the occurrence of the inflection point is intentionally formed based on such a skin effect, and In addition, as a user who monitors the thickness of the film, it is not known to use the peak value as a film thickness reference position to monitor the film thickness or calculate the polishing rate. In terms of significant effects not found in the prior art, as a consuming part of the eddy current, the conductive film is consumed or leaked to the element without being consumed by the conductive film, and it is not consumed by the conductive film. The state of the state, etc., through the acquisition of the inflection point, can clearly understand the state of the magnetic field intrusion into the conductive film. In the conventional method, it is considered that the magnetic field is invaded by the element and the energy of the magnetic field is not considered. There is a large difference in damage to components, etc. The present invention is based on a hardware composed of such distinct effects of the effects and its detection calculation logic. Further, the present invention is not limited to the above-described embodiments, and various changes can be made within the technical scope of the present invention, and the present invention is of course applicable to the modification (a brief description of the drawings) [0131]

1] shows an embodiment of the present invention, which is a perspective view of a chemical mechanical polishing 42 200912252 device. [囷2(a)~(c)] Circle 2(a) is the square circle for predicting/detecting the set, 囷2(b) is the squint circle of the planar inductor, and Fig. 2(c) is the section circle. 3(a) to (b) FIG. 3(a) is a diagram showing the configuration of an oscillation circuit, and 囷3 (b) is an equivalent circuit circle of the oscillation circuit. 4(a) to (d) are schematic diagrams showing an image of an operation simulation result of the prediction/detection device on the display, and Fig. 4(a) shows a conductor film thickness of 22 Vm and an oscillation frequency of 1 MHz. In the case, FIG. 4(b) shows a case where the conductor film thickness is lym and the oscillation frequency is 1 MHz, and FIG. 4(c) shows a case where the conductor film thickness is 2.2#m and the oscillation frequency is 40 MHz, and FIG. 4(d) shows the conductor thickness iym. A diagram of the case where the oscillation frequency is 40 MHz. [Fig. 5] An equivalent circuit diagram of the prediction/detection device. [Fig. 6] Film thickness of the prediction/detection device: a table of impedance characteristics. [Fig. 7] Film thickness of the prediction/detection device: a table of impedance characteristics. [Circle 8] The interpretation circle of the measurement point of the planar inductor on the conductor film. Fig. 9 is a view showing an example of a resonance frequency waveform at each point of Fig. 8. Fig. 10 is a graph showing an example of the amount of polishing at each point of Fig. 8. [圊11] A graph of a reference waveform at the time of polishing a Cu film by the prediction/detection method of the present invention. [囷12] shows the plane explanation of other configurations of the prediction/detection device. 43 200912252 [Main component representative symbol] [0132] 1 Chemical mechanical polishing device 2 3 Motor 4 5 Polishing pad 6 W Wafer 28 Conductive film 33 Prediction/detection device 34 35 Oscillation circuit 36 36a '41a Substrate 33a 37 Concentration Constant Capacitor 38 39 Feedback Network 40 Frequency Counter 41 Planar Inductor L Inductance C0 Capacitor Platform Drive Mechanism Grinding Head Inductor Type Sensor Planar Inductor Sealing Amplifier 44

Claims (1)

200912252 X. Patent application scope: 1. A method for predicting the end time of polishing, which is characterized in that a polishing tool or a chemical solution is supplied while a processing tool such as a polishing pad is slid with a crystal of a conductive film to conduct electricity. In the polishing process for removing the defects, the inductor is brought close to the conductive film on the wafer, and the magnetic field lines formed by the inductor are monitored on the conductive film of the wafer, and the material of the conductive film is The magnetic field line 'variation of the skin effect of one factor is used to estimate the amount of polishing while polishing the wafer surface. 2. The method for predicting the time of the grinding joint at the time of the application of the patent scope, wherein the grinding amount is estimated instantaneously, which is the residual film thickness, the average film thickness, the grinding shape, the grinding amount, the average grinding amount, and the grinding removal amount. Any of the unevenness, the unevenness of the residual thickness, and the shape of the residual flaw. 3. For the prediction method of the polishing end time point in the first application of the patent scope, in which I grind the wafer surface to the edge and estimate the amount of polishing on a plurality of parts in the wafer surface. 4. A method of predicting a polishing end time point of the patent application, wherein the inductor close to the conductive film is a secondary element planar inductor. 5. A method for predicting the end of the polishing time, which is characterized in that the polishing tool or the chemical liquid is supplied while the processing tool such as a polishing pad is slid with the crystal of the conductive film to perform polishing of the conductive film. In the X process, the inductor is brought close to the conductive film on the wafer, and the voltage line formed by the inductor is caused by the magnetic field line formed by the inductor on the conductive film of the wafer and the material of the conductive film is a factor. The magnetic field lines which change with the skin effect increase in the thickness of the film due to the decrease in the thickness of the film caused by the increase in the eddy current of the conductive film, and the eddy current is substantially reduced in association with the subsequent decrease in the film thickness. The state of the characteristic change of the magnetic lines of force caused by the film is converted into the film thickness, and the amount of polishing is immediately estimated based on the relative unevenness. 6. A method for predicting a polishing time point, which is characterized in that a polishing tool or a chemical liquid is supplied while a processing tool such as a polishing pad is slid with a wafer having a conductive film to remove a conductive film. In the polishing process, the inductor is brought close to the conductive film on the crystal garden, and the magnetic field lines formed by the inductor are monitored on the conductive film of the wafer and the material of the conductive film is a factor of a broadening effect. The varying magnetic lines of force are caused by an increase in the thickness of the film due to the decrease in the thickness of the film caused by the increase in the eddy current of the conductive film, and the eddy current is substantially reduced in association with the subsequent decrease in the film thickness. The elapsed time when a plurality of positions are obtained by the change portion of the characteristic of the magnetic lines of force caused by the conductive film is determined in advance by the unevenness of the elapsed time at the plurality of positions. 7. A method for predicting a polishing time point, which is characterized in that a processing tool such as a polishing pad and a wafer having a conductive film are slid to perform polishing of a conductive film while supplying a polishing or chemical liquid. In engineering, 'the inductor is placed in a plurality of different trajectory positions relative to the wafer and is close to the wafer, and the monitoring utilizes the magnetic field lines formed by the inductor to cause a plurality of positions in a predetermined wafer surface. 200912252 The change of the magnetic field line of the conductive film is based on the skin effect of the conductive film, and the elapsed time when the change portion of the magnetic field line caused by the conductivity 骐 is obtained at a plurality of positions in the wafer surface is converted into The unevenness of the amount of polishing removal or the amount of film thickness at a plurality of positions is converted from the rate of change of the waveform, and the amount of polishing is immediately obtained in the processing in accordance with the unevenness or the amount of film thickness. 8. The method for predicting the end time of polishing according to item 1 of the patent application, wherein the measuring means for changing the magnetic field line caused by the collective effect of the conductive film is the measurement of the eddy current in the conductive film, or The measurement of the mutual inductance generated by the eddy current generated by the conductive film, or the measurement of the inductance change in the sensor circuit of the inductor based on the mutual inductance of the conductive 骐, or the measurement of the impedance change of the sensor circuit, Or at least one of measuring the resonance frequency of the sensor circuit system by connecting the high-frequency inductor and the capacitor in parallel and oscillating to measure the resonance frequency. 47