JP2018006063A - Ion beam processing device and ion beam processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of detecting a correct end point corresponding to a processing object.SOLUTION: An ion beam processing device comprises: a charged particle detector 15 that detects a secondary particle generated from an object by performing a scanning of an ion beam 13a; and a control device 20 that detects a time change of brightness of an SIM image at a plurality of processed portions in the SIM image by the secondary particle detected in the charged particle detector 15 and controls a processing condition by the ion beam 13a in response to the brightness. The control device 20 includes: a detection processing part 21a that independently detects the time change of the brightness of the SIM image for a plurality of processed regions arranged on the SIM image; a setting processing part 21b that sets a threshold value of the brightness; and a termination processing part 21c that independently terminates the processing in each processed region as a processing termination point of each processed region in a case where the brightness of each processed region detected in the detection processing part 21a is corresponded to the threshold value set in the setting processing part 21b during processing of the object.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ion beam processing apparatus and an ion beam processing method, for example, an ion beam processing apparatus and an ion beam processing method for manufacturing MEMS (Micro Electro Mechanical Systems).

  Patent Document 1 discloses an ion beam apparatus including a luminance change detection unit that detects a change in luminance of an ion microscope image observed during processing, and an end point detection unit that stops processing when the change in luminance is detected. Is disclosed.

JP 2002-33070 A

  In the technique of Patent Document 1 described above, the processing end point can be detected by the change in the brightness of the ion microscope image, but it is difficult to accurately detect the end point when there is processing variation in the processing target. For example, in end point detection for each of a plurality of processing points, if there is a variation in film thickness on the processing target, end point detection is required for each processing point.

  An object of the present invention is to provide a technique that enables accurate end point detection corresponding to an object to be processed.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  An ion beam processing apparatus according to an embodiment includes a detector that detects secondary particles generated from an object by scanning an ion beam, and a plurality of processing locations in a scanning ion microscope image of the secondary particles detected by the detector. And a control device that detects temporal changes in the brightness of the scanning ion microscope image and controls processing conditions by the ion beam in accordance with the brightness.

  An ion beam processing method according to an embodiment includes a detection step of detecting secondary particles generated from an object by scanning an ion beam, and a plurality of processing locations in a scanning ion microscope image of the secondary particles detected in the detection step. And a control step of detecting a time change in the brightness of the scanning ion microscope image and controlling a processing condition by the ion beam according to the brightness.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  According to one embodiment, accurate end point detection corresponding to a processing target can be performed.

It is a block diagram which shows an example of a structure of the ion beam processing apparatus in embodiment. (A)-(c) is explanatory drawing which shows the case where the end point detection with respect to several process area | region is performed as a 1st example of the ion beam processing method in embodiment. (A)-(c) is explanatory drawing which shows the case where the end point detection which reflected the process variation in one process area is performed as a 2nd example of the ion beam processing method in embodiment. (A) And (b) is explanatory drawing which shows the case where the film thickness measurement for every multilayer film in process is performed as a 3rd example of the ion beam processing method in embodiment. (A) And (b) is explanatory drawing which shows the case where the optimal process conditions are reset for every layer as a 4th example of the ion beam processing method in embodiment.

  In the following embodiments, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant to each other. There are some or all of the modifications, details, supplementary explanations, and the like.

  Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.

  Further, in the following embodiments, the constituent elements (including element steps and the like) are not necessarily indispensable unless otherwise specified and apparently essential in principle. Needless to say.

  Similarly, in the following embodiments, when referring to the shape, positional relationship, etc. of components, etc., the shape of the component is substantially the case unless it is clearly specified and the case where it is clearly not apparent in principle. And the like are included. The same applies to the above numerical values and ranges.

  In all the drawings for explaining the embodiments, the same members are denoted by the same reference symbols in principle, and the repeated explanation thereof is omitted. In order to make the drawings easier to understand, even a plan view may be hatched, and even a sectional view may be omitted.

  Hereinafter, embodiments will be described in detail with reference to the drawings. In order to make the features of the embodiments easy to understand, first, room for improvement existing in the related art will be described.

[Room for improvement]
In recent years, there has been an IoT (Internet of Things) era, and the demand for sensors capable of various sensing is increasing. In particular, MEMS sensors are widely used, and there is a demand for quickly supplying a wide variety of MEMS sensors. The conventional MEMS manufacturing process is mainly a lithography process similar to LSI (Large Scale Integrated Circuit) using so-called silicon. For this purpose, it is effective to form the MEMS structure by a direct modeling process using a FIB (Focused Ion Beam) apparatus.

  The FIB apparatus is capable of direct modeling (etching and deposition) using an ion beam. When the FIB apparatus is used for manufacturing the MEMS, there is a problem different from the wafer process. In the wafer process, etch stop by gas etching with a high selection ratio and end point detection technology by SIMS (Secondary Ion Mass Spectrometry) are used. In the case of using FIB, in general, the depth is controlled by determining the etching time from the etching rate calculated in advance. However, since the etching rate varies depending on the processing shape, it is difficult to control with high accuracy.

  In addition, the FIB apparatus can acquire a real-time image only at a processing portion (processing window) during etching with an ion beam. For example, in a laminated film having a layered structure made of a plurality of different materials, when etching is finished at a desired layer, the lightness of the processing window (here, lightness is described, but similar, reflecting the electron density of each layer) Including concepts such as brightness and contrast). Using this, it is possible to finish etching with a desired layer.

  Patent Document 1 described above includes an ion having a luminance change detecting unit that detects a change in luminance of an ion microscope image observed during processing, and an end point detecting unit that stops processing when the change in luminance is detected. A beam device is disclosed. In this ion beam apparatus, the processing end point can be detected by changing the brightness of the ion microscope image using the processing ion beam and the observation ion beam.

  However, in the technique of Patent Document 1 described above, it is difficult to accurately detect the end point when there is processing variation in the processing target. For example, in end point detection for each of a plurality of processing points, if there is a variation in film thickness on the processing target, end point detection is required for each processing point.

  Therefore, in the present embodiment, a device is devised for room for improvement existing in the related art described above. In the following, the technical idea in the present embodiment in which this device is applied will be described with reference to the drawings. The technical idea of the present embodiment is to provide a technique that enables accurate end point detection corresponding to a processing target.

[Embodiment]
An ion beam processing apparatus and an ion beam processing method according to an embodiment will be described with reference to FIGS. In this embodiment, an ion beam processing apparatus and an ion beam processing method for manufacturing a MEMS structure device will be described as an example of a device in an ion beam processing apparatus and an ion beam processing method. Applicable.

<Ion beam processing equipment>
An ion beam processing apparatus according to an embodiment will be described with reference to FIG. FIG. 1 is a configuration diagram illustrating an example of a configuration of an ion beam processing apparatus according to an embodiment.

  As shown in FIG. 1, the ion beam processing apparatus according to the present embodiment includes a FIB apparatus 10 and a control apparatus 20. The FIB apparatus 10 can be directly modeled by an ion beam, and can acquire a real-time image at the time of processing by the ion beam. The FIB device 10 is controlled by the control device 20.

  The FIB apparatus 10 includes a vacuum chamber 11, a stage 12, an ion gun 13, a gas gun 14, a charged particle detector 15, and the like. The vacuum chamber 11 is a chamber that performs processing such as etching and deposition of a device manufactured on the substrate 30 and observation of the device after processing. The stage 12 is in the vacuum chamber 11 and is a stage on which a substrate 30 for manufacturing a device is placed.

  The ion gun 13 is an ion gun that is in the vacuum chamber 11 and is used for etching and deposition using the ion beam 13a and acquisition of a SIM (Scanning Ion Microscope) image. The gas gun 14 is in the vacuum chamber 11 and is a gas gun used for etching and deposition using the gas 14a. The charged particle detector 15 is a detector used for SIM image acquisition. The charged particle detector 15 is a detector that detects secondary particles generated from a device that is an object by scanning the ion beam 13a.

  The control device 20 is a device that controls the driving of the stage 12, which is a component of the FIB apparatus 10, the irradiation of the ion beam 13 a from the ion gun 13, and the blowing of the gas 14 a from the gas gun 14.

  Further, the control device 20 includes a calculation processing device 21, a display input device 22, an output device 23, and the like as functions of the computer system. The calculation processing device 21 includes a detection processing unit 21a, a setting processing unit 21b, an end processing unit 21c, a calculation processing unit 21d, an application processing unit 21e, a storage 21f, and the like. The control device 20 is also a system that instructs the FIB device 10 to process or observe a device.

  This control device 20 detects the time change of the brightness of the SIM image at a plurality of processing locations in the SIM image by the secondary particles detected by the charged particle detector 15, and controls the processing conditions by the ion beam 13a according to this brightness. It is a control device.

  In the control device 20, for example, in the processing, the calculation processing device 21 performs processing for detecting an end point of etching using a change in brightness of the SIM image acquired during etching by the ion beam 13 a.

  In the calculation processing device 21, for example, the detection processing unit 21 a performs a process of detecting a temporal change in brightness of the SIM image independently for a plurality of processing regions arranged on the SIM image. The setting processing unit 21b performs processing for setting a lightness threshold. The end processing unit 21c uses the case where the brightness of the processing region detected by the detection processing unit 21a during processing of the device as the target corresponds to the threshold set by the setting processing unit 21b as the processing end point of each processing region. For each processing region, processing for independently finishing processing is performed.

  Details of each processing of the detection processing unit 21a, the setting processing unit 21b, the end processing unit 21c, the calculation processing unit 21d, and the application processing unit 21e in the calculation processing device 21 will be described later in each example of the ion beam processing method.

  The storage 21f is a storage device that stores, as electronic information, design data of devices manufactured on the substrate 30, manufacturing recipes and processing data for performing processing based on the design data.

  The display input device 22 has a display function and an input function by a touch method or the like. The display input device 22 includes a display input interface 22a, a start button 22b, and the like. The display input interface 22a performs display of a SIM image, confirmation of a SIM image by an operator, display of a machining area, input of a machining area by an operator, display of machining conditions, input of machining conditions by an operator, and the like. The display input interface 22a is a display unit that displays temporal changes in brightness of the SIM image at a plurality of processing locations in the SIM image. The start button 22b is a button for instructing the start of processing by inputting a start (one-click, one-touch, one-tap) after inputting necessary information by the operator.

  The output device 23 outputs processing and observation results. The output device 23 outputs a SIM image, a processing region, processing conditions, and the like.

  In the ion beam processing apparatus according to the present embodiment, the start button 22b is input after the operator inputs necessary information, whereby the manufacturing of the MEMS structure device is automatically executed. For example, the ion beam processing apparatus detects a secondary particle generated from a device that is an object by scanning the ion beam 13a, and the SIM image of a plurality of processing locations in the SIM image by the detected secondary particle. A control step of detecting a change in lightness over time and controlling processing conditions by the ion beam 13a according to the lightness is automatically performed.

  Details of the detection step and the control step by the ion beam processing apparatus will be described later in each example of the ion beam processing method.

<Ion beam processing method>
An ion beam processing method in the embodiment will be described with reference to FIGS. 2 illustrates a first example of an ion beam processing method, FIG. 3 illustrates a second example of the ion beam processing method, FIG. 4 illustrates a third example of the ion beam processing method, and FIG. 5 illustrates a fourth example of the ion beam processing method. It is explanatory drawing to do.

  The ion beam processing method in the present embodiment is executed in the above-described ion beam processing apparatus, and includes a first example as shown in FIG. 2, a second example as shown in FIG. 3, and a first example as shown in FIG. There are three examples and a fourth example as shown in FIG.

  The ion beam processing method according to the present embodiment includes a detection step of detecting secondary particles generated from a target device by scanning with an ion beam 13a, and a plurality of processing locations in a SIM image by the detected secondary particles. A control step of detecting a temporal change in brightness of the SIM image and controlling processing conditions by the ion beam 13a according to the brightness.

  In the ion beam processing method, the detection process is a process performed by the charged particle detector 15 of the ion beam processing apparatus, and the control process is a process performed by the control apparatus 20 of the ion beam processing apparatus. In this ion beam processing method, the display input interface 22a of the display input device 22 can display temporal changes in brightness of SIM images at a plurality of processing locations in the SIM image.

  Hereinafter, a first example, a second example, a third example, and a fourth example of the ion beam processing method will be described in order.

<< First Example >>
A first example of the ion beam processing method in the present embodiment will be described. FIG. 2 is an explanatory diagram illustrating a case where end points are detected for a plurality of machining regions as a first example. 2A is a cross-sectional view showing a device before etching, FIG. 2B is a cross-sectional view showing a device after etching, and FIG. 2C is an explanatory view showing a change in brightness with respect to etching time.

  In the first example, the control device 20 of the ion beam processing apparatus shown in FIG. 1 includes a detection processing unit 21a, a setting processing unit 21b, and an end processing unit 21c. The detection processing unit 21a detects a temporal change in lightness of the SIM image independently for a plurality of processing regions arranged on the SIM image. The setting processing unit 21b sets a lightness threshold value. The end processing unit 21c sets the case where the brightness of the processing area detected by the detection processing unit 21a during processing of the device corresponds to the threshold set by the setting processing unit 21b as the processing end point of each processing area for each processing area. Finish processing independently.

  In the ion beam processing method of the first example, in the control step by the control device 20, during the processing of the device, the time change of the brightness of the SIM image is detected independently for a plurality of processing regions arranged on the SIM image, When the detected brightness of the machining area corresponds to the set threshold value, the machining end point of each machining area is regarded as the machining end point for each machining area independently.

  As described above, the FIB apparatus uses the charged particle detector 15 to detect the SIM image of the processing portion (processing window) during the hole processing etching by the ion beam 13a and the secondary particles generated from the device by scanning the ion beam 13a. Can be obtained by doing.

As a device, for example, as shown in FIG. 2A, a first layer film 52 of silicon dioxide SiO ₂ , a second layer film 53 of tungsten W, and a third layer of silicon dioxide SiO ₂ are formed on a silicon Si substrate 51. Consider a MEMS structure having a multilayer structure in which a layer film 54 and a fourth layer film 55 of silicon nitride SiN are sequentially stacked. The device has a layered structure composed of a plurality of different materials.

In this multilayer structure device, the brightness of the processing window changes reflecting the electron density of each layer during etching of the hole processing by the ion beam 13a. The brightness is determined by the amount of secondary electrons (secondary particles) detected by the charged particle detector 15. If the material of each layer is different, the electron density of each layer is different, so that the amount of secondary electrons to be detected differs. For this reason, a difference occurs in brightness. In the brightness of silicon dioxide SiO ₂ , tungsten W and silicon nitride SiN, silicon nitride SiN, silicon dioxide SiO ₂ and tungsten W are arranged in order from the darker to the brighter.

  In the present embodiment, it is possible to end the hole processing etching with a desired layer by utilizing such a change in brightness. For example, when the etching is finished when the second layer film 53 of tungsten W is detected, the etching is finished when the brightness changes to the brightness corresponding to tungsten W in FIG. To do. In this case, the brightness corresponding to tungsten W is set in advance by the setting processing unit 21b as a threshold value.

  In particular, in the first example, as shown in FIG. 2B, when there are a plurality of processing regions 61 and 62, the detection processing unit 21 a independently generates a SIM image for the plurality of processing regions 61 and 62. When the brightness change over time is detected and the brightness of the processing areas 61 and 62 detected by the detection processing section 21a in the end processing section 21c corresponds to the threshold set by the setting processing section 21b, the processing of the processing areas 61 and 62 is performed. As an end point, the processing is terminated independently for each processing region.

  In the detection of the end point of independent hole processing for each processing region, when there is a variation in the film thickness of the second layer film 53 of tungsten W, the end point detection is performed independently for each processing region, and the hole processing is ended independently. To do. 2B, since the film thickness of the second layer film 53 of tungsten W in the processing region 61 is small and the film thickness of the second layer film 53 of tungsten W in the processing region 62 is large, the end point of the processing region 61 is obtained. Detection is performed to end the hole processing, and end point detection of the processing region 62 is performed to complete the hole processing.

  According to the first example of the ion beam processing method in the present embodiment, the end point is detected independently for a plurality of processing regions 61 and 62 arranged on the SIM image, and the processing depth is controlled independently for each processing region. can do. As a result, the processing depth differs for each processing region in the wafer surface, and processing for each processing region with different end point detection in the wafer surface becomes possible.

<< Second Example >>
A second example of the ion beam processing method in the present embodiment will be described. FIG. 3 is an explanatory diagram showing a case where end point detection reflecting machining variations in one machining area is performed as a second example. In FIG. 3, (a), (b), and (c) show changes in the brightness of the SIM image of one processing region with respect to the etching time.

  In the second example, the control device 20 of the ion beam processing apparatus shown in FIG. 1 includes a detection processing unit 21a, a setting processing unit 21b, and an end processing unit 21c. The detection processing unit 21a detects a time change of the brightness of the SIM image independently at a plurality of detection points with respect to one processing region arranged on the SIM image. The setting processing unit 21b sets a lightness threshold value. The end processing unit 21c includes the detection points when the brightness of the detection point detected by the detection processing unit 21a during the processing of the device corresponds to the threshold set by the setting processing unit 21b as the processing end point of each detection point. The machining of one machining area is finished.

  In the ion beam processing method of the second example, in the control step by the control device 20, during the processing of the device, the time of the brightness of the SIM image independently at a plurality of detection points with respect to one processing region arranged on the SIM image. A change is detected, and the processing of one processing region including the detection point is terminated with the case where the brightness of the detected detection point corresponds to the set threshold value as the processing end point of each detection point.

In the second example, the device, as in the first example, on the substrate 51 of silicon Si, first layer film 52 of silicon dioxide SiO _2, the second layer film 53 of tungsten W, a third silicon dioxide SiO ₂ Consider a MEMS structure having a multilayer structure in which a layer film 54 and a fourth layer film 55 of silicon nitride SiN are sequentially stacked.

  In this second example as well, the hole processing etching is terminated when a desired layer, for example, the second layer film 53 of tungsten W is detected, using the change in brightness at the time of the hole processing etching by the ion beam 13a. Is possible.

  In particular, the second example is a case where end point detection that reflects machining variations in one machining area is performed. In the hole processing, there may be a case where uniform processing cannot be performed, reflecting processing variations in deposition and the roughness of the base. In such a case, in the second example, the brightness is measured at a plurality of detection points of the processing window, and different end points are set at the respective detection points. In this case, the lightness threshold value is set in advance by the setting processing unit 21b.

  In the second example, as shown in FIG. 3, the detection processing unit 21 a detects the time change of the brightness of the SIM image independently at a plurality of detection points 72, 73, 74 for one processing region 71, and ends. In the processing unit 21c, when the brightness of the detection points 72, 73, 74 detected by the detection processing unit 21a corresponds to the threshold value set by the setting processing unit 21b, the detection points 72, 73, 74 are detected as processing end points. Processing of one processing area 71 including 72, 73, and 74 is completed.

In FIG. 3, the etching time elapses in the direction from (a) to (c), and the SIM image of the processed region 71 at each etching time is as shown in (a), (b), and (c) of silicon nitride SiN. The brightness changes corresponding to the fourth layer film 55, the third layer film 54 of silicon dioxide SiO ₂ , and the second layer film 53 of tungsten W. In this case, the processing region 71 is further divided into a plurality of processing regions, and detection points 72, 73, 74 corresponding to the processing regions 71 are set. When the detection point 74 reaches the end point, the processing region including the detection points 74 is processed. However, since the processing area including the detection points 72 and 73 has not reached the end point, the processing is continued. Next, when the detection point 73 reaches the end point, the processing of the processing region including the detection point 73 is finished. Finally, when the detection point 72 reaches the end point, the processing of the processing region including the detection point 72 is finished.

  According to the second example of the ion beam processing method in the present embodiment, the end point is detected and detected independently at a plurality of detection points 72, 73, 74 for one processing region 71 arranged on the SIM image. The processing depth can be independently controlled for each processing region including the detection point. As a result, the processing depth differs for each detection point of the processing region in the wafer surface, and processing for each processing region including detection points having different end point detections in the wafer surface becomes possible.

<< Third Example >>
A third example of the ion beam processing method in the present embodiment will be described. FIG. 4 is an explanatory diagram showing a case where film thickness measurement is performed for each multilayer film being processed as a third example. 4A shows the measurement of the thickness of the fourth layer film of silicon nitride SiN, and FIG. 4B shows the measurement of the thickness of the third layer film of silicon dioxide SiO ₂ .

  In the third example, the control device 20 of the ion beam processing apparatus illustrated in FIG. 1 includes a detection processing unit 21a, a setting processing unit 21b, and a calculation processing unit 21d. When processing a device having a layered structure made of one or more different materials, the detection processing unit 21a detects a processing time for each layer using a point where the brightness of the SIM image changes greatly as a layer boundary. The setting processing unit 21b sets a processing rate for each material. The calculation processing unit 21d calculates the film thickness of each layer from the processing rate for each material set by the setting processing unit 21b based on the processing time detected by the detection processing unit 21a during processing of the device.

  In the ion beam processing method of the third example, in the control step by the control device 20, the layer boundary is set at a point where the brightness of the SIM image changes greatly during processing of a device having a layered structure made of one or more different materials. The processing time for each layer is detected, and the film thickness of each layer is calculated from the set processing rate for each material based on the detected processing time.

In the third embodiment, the device, as in the first example, on the substrate 51 of silicon Si, first layer film 52 of silicon dioxide SiO _2, the second layer film 53 of tungsten W, a third silicon dioxide SiO ₂ Consider a MEMS structure having a multilayer structure in which a layer film 54 and a fourth layer film 55 of silicon nitride SiN are sequentially stacked.

Also in this third example, a desired layer, for example, the third layer film 54 of silicon dioxide SiO ₂ and the second layer film 53 of tungsten W are detected by utilizing the change in brightness at the time of etching of the hole processing by the ion beam 13a. At this point, it is possible to finish the hole processing etching.

  In particular, in the third example, the film thickness is measured for each multilayer film being processed. In the processing of a device having a layered structure made of one or more different materials, the interface can be detected from the change in brightness of the SIM image, so that the film thickness can be obtained from the processing time of each layer and the processing rate of each layer. Also in the third example, the film thickness is measured from the processing time of each layer and the processing rate of each layer. In this case, the processing rate for each material of each layer is set in advance by the setting processing unit 21b.

  In the third example, as shown in FIG. 4, the processing time for each layer is detected using the point where the lightness of the SIM image greatly changes in the detection processing unit 21a as a layer boundary, and the calculation processing unit 21d Further, based on the processing time detected by the detection processing unit 21a, the film thickness of each layer is calculated from the processing rate for each material set by the setting processing unit 21b.

FIG. 4A shows a case where the etching of the hole processing is temporarily terminated when the third layer film 54 of silicon dioxide SiO ₂ is detected in the processing region 81, and the etching is further advanced. FIG. 6B shows a case where the etching for drilling is finally finished when the second layer film 53 of tungsten W is detected. It is also possible to finally end the hole processing etching when the third layer film 54 of silicon dioxide SiO ₂ is detected. In this case, only FIG.

As shown in FIG. 4A, when the hole processing etching is temporarily terminated when the third layer film 54 of silicon dioxide SiO ₂ is detected, the interface 82 is detected from the change in brightness of the SIM image. The thickness of the etched fourth layer film 55 of silicon nitride SiN is calculated from the processing time of the fourth layer film 55 of silicon nitride SiN and the processing rate of the material of silicon nitride SiN.

When the etching is further advanced and the hole processing etching is finally finished when the second layer film 53 of tungsten W is detected as shown in FIG. 4B, the interface changes from the change in brightness of the SIM image. 83 detects the thickness of the third layer film 54 of silicon dioxide SiO ₂ was etched, calculated from the processing rate of the processing time and silicon dioxide SiO ₂ material of the three-layer film 54 of the silicon dioxide SiO _2.

  According to the third example of the ion beam processing method in the present embodiment, when processing a device having a layered structure made of one or more different materials, up to the interfaces 82 and 83 at the plurality of layer boundaries in the processing region 81. From the processing time and the processing rate of each layer, the film thickness for each multilayer film can be calculated during processing. As a result, the film thickness can be measured during device processing, and the quality control of the film thickness for each multilayer film can be performed.

<< Fourth Example >>
A fourth example of the ion beam processing method in the present embodiment will be described. FIG. 5 is an explanatory diagram showing a case where optimum processing conditions are reset for each layer as a fourth example. 5A shows resetting of the processing current value of the fourth layer film of silicon nitride SiN, and FIG. 5B shows resetting of the processing current value of the third layer film of silicon dioxide SiO ₂ .

  In the fourth example, the control device 20 of the ion beam processing apparatus illustrated in FIG. 1 includes a detection processing unit 21a, a setting processing unit 21b, and an application processing unit 21e. When processing a device having a layered structure made of one or more different materials, the detection processing unit 21a detects, as a layer boundary, a point where the brightness of the SIM image changes greatly. The setting processing unit 21b sets processing conditions (processing current value, presence / absence of gas assist, etc.) for each layer. The application processing unit 21e applies the processing conditions for each layer set by the setting processing unit 21b according to the detection of the layer boundary by the detection processing unit 21a during the processing of the device.

  In the ion beam processing method of the fourth example, in the control step by the control device 20, a point where the brightness of the SIM image changes greatly during processing of a device having a layered structure made of one or more different materials is detected as a layer boundary. Depending on the detection of the layer boundary, the set processing conditions for each layer are applied.

In the fourth embodiment, the device, as in the first example, on the substrate 51 of silicon Si, first layer film 52 of silicon dioxide SiO _2, the second layer film 53 of tungsten W, a third silicon dioxide SiO ₂ Consider a MEMS structure having a multilayer structure in which a layer film 54 and a fourth layer film 55 of silicon nitride SiN are sequentially stacked.

Also in the fourth example, a desired layer, for example, the third layer film 54 of silicon dioxide SiO ₂ and the second layer film 53 of tungsten W are detected by utilizing the change in brightness at the time of the hole processing etching by the ion beam 13a. At this point, it is possible to finish the hole processing etching.

Particularly, in the fourth example, the optimum processing conditions are reset for each layer. When processing a device having a layered structure made of one or more different materials, the interface can be detected from the change in brightness of the SIM image, so that each interface can be detected and optimum processing conditions can be reset for each layer. . For example, it is possible to reduce the machining current value of the layer immediately before the layer for which machining is finished, and to obtain a reliable end point detection and a flat machining shape. The layer of silicon dioxide SiO _2, since available gas assist xenon difluoride XeF _2, and the like are possible to select only the gas-assisted machining silicon dioxide layer SiO _2. In this case, the processing conditions such as the processing current value and the presence / absence of gas assist for each layer are set in advance by the setting processing unit 21b.

  In the fourth example, as shown in FIG. 5, the detection processing unit 21a detects a point where the brightness of the SIM image greatly changes as a layer boundary, and the application processing unit 21e performs detection by the detection processing unit 21a during device processing. The machining conditions set by the setting processing unit 21b are applied according to the detection of the layer boundary.

FIG. 5A shows a case where the etching of the hole processing is temporarily terminated at the time when the third layer film 54 of silicon dioxide SiO ₂ is detected in the processing region 91, and the etching is further progressed. FIG. 6B shows a case where the etching for drilling is finally finished when the second layer film 53 of tungsten W is detected.

As shown in FIG. 5A, when the third hole film 54 of silicon dioxide SiO ₂ is detected and the hole processing etching is temporarily terminated, the fourth layer film 55 of silicon nitride SiN to be etched is Since this is the layer immediately before the third layer film 54 of silicon dioxide SiO ₂ after the etching, the fourth layer film 55 of silicon nitride SiN is etched by increasing the processing current value in order to improve the throughput. In this case, the interface 92 is detected from the change in brightness of the SIM image, and the etching is temporarily terminated.

When the etching is further advanced and the etching of the hole processing is finally finished when the second layer film 53 of tungsten W is detected as shown in FIG. 5B, the second etching of the silicon dioxide SiO _{2 to be} etched is performed. Since the three-layer film 54 is an etching-completed layer, the processing current value is lowered to obtain the flat shape of the hole bottom, and the third layer film 54 of silicon dioxide SiO ₂ is etched. In this case, the interface 93 is detected from the change in brightness of the SIM image, and the etching is finally finished.

FIG. 5B shows a case where the third layer film 54 of silicon dioxide SiO ₂ is etched, so that it is possible to use gas assist that assists the processing by blowing a gas 14a of xenon difluoride XeF _2. is there.

  According to the fourth example of the ion beam processing method in the present embodiment, when processing a device having a layered structure made of one or more different materials, the interface 92, 93 at the layer boundary is reached in the processing region 91. Each layer can be processed by applying optimum processing conditions to each layer. As a result, it is possible to improve the throughput, shorten the machining time, and realize a highly accurate machining by making the hole bottom flat.

<Effect>
According to the ion beam processing apparatus and the ion beam processing method in the present embodiment described above, it is possible to accurately detect the end point corresponding to the processing target. More specifically, end point detection for a plurality of processing regions, end point detection reflecting processing variations in one processing region, film thickness measurement for each multilayer film during processing, and resetting of optimum processing conditions for each layer Can be realized.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, in the above-described embodiment, the MEMS structure device has been described as an example of the device, but the present invention can also be applied to other devices. Also, the MEMS structure is not limited to a multilayer structure in which silicon dioxide SiO ₂ , tungsten W, silicon dioxide SiO ₂ , and silicon nitride SiN are stacked.

  The ion beam processing apparatus is not limited to the FIB apparatus 10, and an FIB-SEM apparatus that is a combined apparatus of an FIB apparatus and a SEM (Scanning Electron Microscope) apparatus can also be used. In this case, by having an electron gun, an SEM image using an electron beam can be acquired during observation. Further, the end point of etching can be detected using the change in brightness of the SEM image, as in the above embodiment.

  The ion beam processing apparatus may target an object including a test digging region in addition to the processing region as described in the above embodiment. In this case, the object includes a processing area and a trial digging area. Then, the ion beam processing apparatus measures the processing time until the end point is reached by performing etching in the trial digging region. Based on the measured machining time, the machining rate of the machining area is determined. Thereby, when etching a process area | region, it can etch with this determined process rate.

  In addition, this invention is not limited to above-described embodiment, Various modifications are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described.

  Further, part of the configuration of the embodiment can be added, deleted, or replaced with another configuration.

DESCRIPTION OF SYMBOLS 10 FIB apparatus 11 Vacuum chamber 12 Stage 13 Ion gun 13a Ion beam 14 Gas gun 14a Gas 15 Charged particle detector 20 Control unit 21 Calculation processing unit 21a Detection processing unit 21b Setting processing unit 21c Completion processing unit 21d Calculation processing unit 21e Application processing Unit 21f Storage 22 Display input device 22a Display input interface 22b Start button 23 Output device 30 Substrate 51 Substrate 52 First layer film 53 Second layer film 54 Third layer film 55 Fourth layer films 61, 62 Processing region 71 Processing region 72, 73, 74 Detection point 81 Machining area 82, 83 Interface 91 Machining area 92, 93 Interface

Claims (15)

A detector for detecting secondary particles generated from an object by scanning an ion beam;
A control device that detects temporal changes in brightness of scanning ion microscope images of a plurality of processing locations in a scanning ion microscope image of secondary particles detected by the detector, and controls processing conditions by an ion beam according to the brightness;
An ion beam processing apparatus comprising: In the ion beam processing apparatus according to claim 1,
The controller is
A detection processing unit for detecting a time change in brightness of the scanning ion microscope image independently for a plurality of processing regions arranged on the scanning ion microscope image;
A setting processing unit for setting a lightness threshold;
When the brightness of the processing area detected by the detection processing unit during processing of the object corresponds to the threshold set by the setting processing unit, processing is independently performed for each processing region, with the processing end point of each processing region A termination processing unit to be terminated;
Including an ion beam processing apparatus. In the ion beam processing apparatus according to claim 1,
The controller is
A detection processing unit that detects a time change in brightness of the scanning ion microscope image independently at a plurality of detection points with respect to one processing region arranged on the scanning ion microscope image;
A setting processing unit for setting a lightness threshold;
One processing area including the detection point, where the brightness of the detection point detected by the detection processing unit during processing of the object corresponds to the threshold set by the setting processing unit as the processing end point of each detection point An end processing unit for finishing the processing of
Including an ion beam processing apparatus. In the ion beam processing apparatus according to claim 1,
The controller is
When processing an object having a layered structure made of one or more different materials, a detection processing unit that detects a processing time for each layer, with a point where the brightness of the scanning ion microscope image changes greatly as a layer boundary;
A setting processing unit for setting a processing rate for each material;
Based on the processing time detected by the detection processing unit during processing of the object, a calculation processing unit that calculates the film thickness of each layer from the processing rate for each material set by the setting processing unit,
Including an ion beam processing apparatus. In the ion beam processing apparatus according to claim 1,
The controller is
When processing an object having a layered structure made of one or more different materials, a detection processing unit that detects a point at which the brightness of the scanning ion microscope image greatly changes as a layer boundary;
A setting processing unit for setting processing conditions for each layer;
An application processing unit that applies processing conditions for each layer set by the setting processing unit in response to detection of a layer boundary by the detection processing unit during processing of the object;
Including an ion beam processing apparatus. In the ion beam processing apparatus according to claim 1,
The controller is
An ion beam processing apparatus, comprising: a display unit configured to display a temporal change in brightness of a scanning ion microscope image at a plurality of processing locations in the scanning ion microscope image. In the ion beam processing apparatus according to claim 1,
The object is an ion beam processing apparatus which is a MEMS structure. In the ion beam processing apparatus according to claim 1,
The object includes a machining area and a trial digging area,
The ion beam processing apparatus measures a processing time until etching reaches the end point after performing etching in the trial digging region, and determines a processing rate of the processing region based on the measured processing time. . A detection step of detecting secondary particles generated from the object by scanning an ion beam;
A control step of detecting temporal changes in brightness of scanning ion microscope images of a plurality of processing locations in a scanning ion microscope image of secondary particles detected in the detection step, and controlling processing conditions by an ion beam according to the brightness;
An ion beam processing method comprising: In the ion beam processing method according to claim 9,
In the control step, during processing of the object, a time change in brightness of the scanning ion microscope image is detected independently for a plurality of processing regions arranged on the scanning ion microscope image, and the detected processing region is detected. An ion beam processing method in which processing is terminated independently for each processing region, with the brightness corresponding to a set threshold value as the processing end point of each processing region. In the ion beam processing method according to claim 9,
In the control step, during processing of the object, a time change in brightness of the scanning ion microscope image is detected independently at a plurality of detection points for one processing region arranged on the scanning ion microscope image. An ion beam processing method in which the processing of one processing region including a detection point is terminated with the case where the brightness of the detected detection point corresponds to a set threshold as the processing end point of each detection point. In the ion beam processing method according to claim 9,
In the control step, during processing of an object having a layered structure made of one or more different materials, a processing time for each layer is detected with a point where the brightness of the scanning ion microscope image changes greatly as a layer boundary. An ion beam processing method for calculating a film thickness of each layer from a set processing rate for each material based on a detected processing time. In the ion beam processing method according to claim 9,
In the control step, during processing of an object having a layered structure made of one or more different materials, a point at which the brightness of the scanning ion microscope image changes greatly is detected as a layer boundary, and according to the detection of the layer boundary An ion beam processing method that applies the set processing conditions for each layer. In the ion beam processing method according to claim 9,
In the control step, an ion beam processing method of displaying a temporal change in brightness of a scanning ion microscope image at a plurality of processing locations in the scanning ion microscope image. In the ion beam processing method according to claim 9,
The ion beam processing method, wherein the object is a MEMS structure.

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