JP2019040702A - Specimen processing method and ion beam processing device - Google Patents

Abstract

To ensure a wide range where a specimen can be used, without deteriorating the performance of the specimen, in the processing of a specimen using an ion beam processing device.SOLUTION: A specimen processing method using an ion beam processing device has (a) a step of forming a pore in the specimen by irradiating the specimen with an ion beam in the vacuum container of the ion beam processing device (step S1), (b) a step of measuring the electrical characteristics of the specimen in the vacuum container multiple times, according to multiple preset pressures (step S2), (c) a step of determining the sealing pressure when sealing the pore, on the basis of the measurement results of multiple times (step S3), and (d) a step of sealing the pore of the specimen by irradiating with an ion beam by the ion bem processing device, while setting the sealing pressure in the vacuum container (step S4).SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sample processing method and an ion beam processing apparatus using an ion beam.

  As a technique for locally processing a semiconductor such as silicon (Si), a processing technique using a focused ion beam (hereinafter also referred to as FIB) is known. The focused ion beam is also used to form a sensor element by, for example, MEMS (Micro Electro Mechanical Systems) technology.

  2. Description of the Related Art An ion beam processing apparatus that performs measurement of electrical characteristics of a MEMS sensor and processing using a focused ion beam in a chamber of the ion beam processing apparatus in a MEMS sensor manufacturing process is known.

  For example, Japanese Patent Laying-Open No. 2015-43425 (Patent Document 1) discloses an apparatus technique that can alternately perform processing of a sample with a focused ion beam and measurement of electrical characteristics with a probe.

JP2015-43425A

  In the manufacturing process of the MEMS sensor, a factor that causes variations in sensor characteristics includes gap amount and mechanical characteristic errors due to variations in the thickness of device layers and insulating layers formed on the silicon substrate.

  Furthermore, an error in gas viscosity due to variation in edge shape after processing of the device layer can be mentioned. Since these errors are caused by the position of the lower portion of the device layer, correction is often difficult only by observation from the upper surface or obliquely.

  Therefore, in order to use the device as a linear device, it is necessary to use only a region where the vibration frequency is sufficiently lower than the resonance frequency region as the device, or to adjust the sealing pressure for each semiconductor chip.

  However, in the method of using only a region whose frequency is sufficiently lower than the region of the resonance frequency as a device, it is a problem that the sensitivity of the sensor is lowered. On the other hand, in the method of adjusting the sealing pressure for each semiconductor chip, there arises a problem that cost increase due to correction for each semiconductor chip is unavoidable.

  An object of the present invention is to provide a technique capable of ensuring a wide usable range of a sample without reducing the performance of the sample in processing the sample.

  The above object and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

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

  In one embodiment, a sample processing method includes (a) a step of irradiating a sample with an ion beam in a vacuum container of an ion beam processing apparatus to form a hole in the sample, and (b) in the vacuum container in advance. Measuring the electrical characteristics of the sample a plurality of times according to a plurality of set pressures. Further, (c) a step of determining a sealing pressure at the time of processing for sealing the hole portion based on the measurement results of the plurality of times, and (d) setting the inside of the vacuum vessel to the sealing pressure. In this state, there is a step of sealing the hole of the sample by irradiating the ion beam with the ion beam processing apparatus.

  An ion beam processing apparatus according to an embodiment includes an ion source, a plurality of lenses that focus an ion beam emitted from the ion source, a stage that holds a sample, and the stage inside. A vacuum vessel in which the sample held by the stage is irradiated with the ion beam to process the sample. And a pressure adjusting unit that adjusts the pressure in the vacuum vessel; and a measurement unit that measures the electrical characteristics of the sample in the vacuum vessel, and the pressure corresponding to a plurality of preset pressures. The inside of the vacuum vessel is changed to a plurality of pressures by the adjusting unit, and the electrical characteristics of the sample are measured a plurality of times according to the plurality of pressures by the measuring unit.

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

  A wide usable range of the sample can be ensured without degrading the performance of the sample in the processing of the sample. In the MEMS sensor, a usable range of the MEMS sensor can be secured widely without lowering the sensor sensitivity.

It is a schematic block diagram which shows an example of the ion beam processing apparatus of embodiment of this invention. It is sectional drawing which shows an example of schematic structure of the MEMS sensor processed with the ion beam processing apparatus of FIG. It is a graph which shows the characteristic of the MEMS sensor processed with the ion beam processing apparatus of FIG. It is a flowchart which shows an example of the procedure of the manufacturing method of the MEMS sensor of embodiment of this invention. It is sectional drawing which shows an example of the structure before sealing of the MEMS sensor processed with the ion beam processing apparatus of FIG. It is sectional drawing which shows an example of the structure at the time of the pressure dependence measurement of the MEMS sensor processed with the ion beam processing apparatus of FIG. It is sectional drawing which shows an example of the structure after sealing of the MEMS sensor processed with the ion beam processing apparatus of FIG. It is sectional drawing which shows an example of the structure at the time of the pressure dependence measurement after sealing of the MEMS sensor processed by the ion beam processing apparatus of FIG. It is a flowchart which shows the procedure of the manufacturing method of the MEMS sensor of a comparative example.

  FIG. 1 is a schematic configuration diagram showing an example of an ion beam processing apparatus according to an embodiment of the present invention.

  The configuration of the ion beam processing apparatus according to the present embodiment will be described with reference to FIG. In the present embodiment, the ion beam processing apparatus is also simply referred to as an ion beam apparatus or a focused ion beam apparatus.

  The ion beam processing apparatus 23 shown in FIG. 1 includes a vacuum container 41 that is a chamber in which the focused ion beam 36 is irradiated onto the sample 11. In addition, an ion beam irradiation system including an ion source 31 that emits gallium ions, a condenser lens 32, an aperture rotation mechanism 37 on which the aperture 33 is placed, an ion beam scanning deflector 34, and the like is attached to the vacuum container 41. It has been.

  That is, in the ion beam irradiation system, the ion beam emitted from the ion source 31 is focused through a condenser lens 32, which is a plurality of lenses, and further focused through an aperture 33 and an ion beam scanning deflector 34. Then, the sample 11 is irradiated with the sample 11 and processed.

  In addition, a stage 13 that holds the sample 11 is provided in the vacuum container 41, and the sample 11 that is held by the stage 13 is irradiated with the focused ion beam 36 to process the sample 11.

  The ion beam processing apparatus 23 according to the present embodiment also includes a chamber pressure adjusting device 35 that is a pressure adjusting unit that adjusts the pressure in the vacuum vessel 41 and the sample 11 placed on the stage 13 in the vacuum vessel 41. And a measurement unit 40 for measuring the electrical characteristics of.

  An intake device 35a and an exhaust device 35b are connected to the chamber pressure adjusting device 35, and the pressure in the vacuum vessel 41 can be increased by the intake device 35a. The pressure can be reduced.

  In addition, a measurement probe 39 that measures the electrical characteristics of the sample 11 such as a MEMS sensor is electrically connected to the measurement unit 40. That is, the measurement probe 39 can be brought into contact with the electrode of the sample 11 to measure the electrical characteristics of the sample 11.

  Further, the ion beam processing apparatus 23 includes an electron beam irradiation system including an electron gun 7 that emits an electron beam 8, an electron lens 9 that focuses the electron beam 8, an electron beam scanning deflector 10, and the like.

  Furthermore, the ion beam processing apparatus 23 includes a secondary particle detector 12, a manipulator 42 provided with a hand unit 15, a gas source 17, and the like.

  In addition, the ion beam processing device 23 includes, as its control system, an ion source control device 81, a lens control device 82, a stage control device 14, a manipulator control device 16, a gas source control device 18, a secondary particle detector control device 19, An aperture rotation control device 38 and a calculation processing device 85 are provided.

  Here, the calculation processing device 85 includes an information input means for inputting information necessary for the user of the ion beam processing device 23, an image generated based on the detection signal of the secondary particle detector 12, and the information input. The display etc. which display the information input by the means are provided.

  In addition, the stage 13 of the ion beam processing apparatus 23 has a linear movement mechanism that enables movement in two directions (X direction and Y direction) that are parallel to and orthogonal to the sample placement surface, and a sample placement surface. A linear movement mechanism that enables movement in the vertical direction, a rotation mechanism with respect to the sample mounting surface, and a tilting mechanism having an tilt axis with respect to the sample mounting surface. Control of the movement of the stage 13 is performed by the stage control device 14 in accordance with a command transmitted from the calculation processing device 85.

  In the ion beam processing apparatus 23, the gallium ions emitted from the ion source 31 are focused on the sample by the condenser lens 32 or the like. The focusing condition is set by input to the calculation processing device 85. Further, the beam diameter of the ion beam applied to the sample 11 is determined by the image formation on the sample 11 using the ion source 31 as a light source and the aberration caused by the lens.

  The ion beam processing apparatus 23 includes a chamber pressure adjusting device 35 and a measuring unit 40. The chamber pressure adjusting device 35 causes a plurality of chambers to adjust a plurality of pressures in the vacuum container 41 in accordance with a plurality of preset pressures. The pressure can be changed (adjusted). Further, the measurement unit 40 can measure the electrical characteristics of the sample 11 a plurality of times according to a plurality of preset pressures.

  As described above, in the ion beam processing apparatus 23 according to the present embodiment, the measurement unit 40 measures the electrical characteristics of the sample 11 a plurality of times in accordance with a plurality of preset pressures in the vacuum vessel 41, and the above measurement is performed. Thereafter, the sealing pressure is determined based on the results of the plurality of measurements. Further, the inside of the vacuum vessel 41 is set to a predetermined sealing pressure by the chamber pressure adjusting device 35, and in this state, the focused ion beam 36 is irradiated onto the sample 11 to form a hole 2d described later formed in the sample 11. Sealing can be performed.

  Next, details of the subject of the present application will be described in detail using an example examined by the present inventors. 2 is a sectional view showing an example of a schematic structure of a MEMS sensor processed by the ion beam processing apparatus of FIG. 1, and FIG. 3 is a graph showing characteristics of the MEMS sensor processed by the ion beam processing apparatus of FIG. .

  Here, the case where the sample 11 processed by the ion beam processing apparatus 23 shown in FIG. 1 is the MEMS sensor 1 as shown in FIG. 2 will be described. In the manufacturing process of the MEMS sensor 1, the following two can be considered as factors that cause variations in sensor characteristics.

  One is an error in the gap 2g and mechanical characteristics due to variations in the thickness of the device layer 2a and the insulating layer (BOX layer) 2b formed on the semiconductor chip (silicon substrate) 2. Furthermore, the other one is an error in gas damping (gas viscosity) due to variation in the shape of the edge 2f after processing of the through hole 2k formed in the device layer 2a.

  Since these errors are caused by the lower part of the through-hole 2k (the shape of the edge part 2f) of the device layer 2a, it is often difficult to correct by only observing the upper part of the device layer 2a or obliquely. Therefore, in order to use the MEMS sensor 1 as a linear device, it is necessary to design a resonance frequency about 10 times higher than the measurement region, or to adjust the sealing pressure for each chip. However, designing a resonance frequency about 10 times higher from the measurement region causes a problem that the sensitivity of the sensor is reduced. On the other hand, adjusting the sealing pressure for each chip leads to a problem that cost increases due to inspection and correction for each chip are unavoidable.

  Here, the relationship between gas damping (viscosity) and pressure dependence will be described with reference to FIG.

The magnitude of the gas damping depends on the sealing pressure and the shape of the MEMS (including the gap 2g size and the variation in the shape of the edge portion 2f). Therefore, when the protrusion structure of the comb-shaped detection electrode attached to the MEMS sensor inertial body is the main cause when receiving the air viscous resistance effect, the damping coefficient C by the sealing gas is
C = 96 η _eff LW ³ / (π ⁴ g ³ )
η _eff = η / (1 + 9.638K _n ^1.159 )
K _n = λ / L _c = k _B T / ((√2) πd _gas ² PL _c )
It is known that However, W is the width of the protrusion structure, g is the distance between the projection structure (gap), eta _eff is the effective value of the viscosity of the peripheral gas, eta is the viscosity constant of the peripheral gas, K _n is Knudsen number, lambda is around gas Mean free path, L is the typical length of the flow field and is the length corresponding to the distance between the protrusion structures, k _B is the Boltzmann constant, T is the absolute temperature, d _gas is the diameter of the molecule of the surrounding gas, P is the surrounding gas Pressure.

  Here, in MEMS, the line segment (a) in FIG. 3 is the sensitivity frequency characteristic when the pressure is the lowest, and the line segment (c) is the sensitivity frequency characteristic when the pressure is the highest.

  Hereinafter, the relationship between the sensitivity frequency characteristic of the MEMS sensor and the sealing pressure will be described with reference to FIG. When the frequency is low (for example, in the case of vacuum), the sensitivity is almost constant with respect to the frequency and is not pressure-dependent. When the frequency is increased, a peak (Q portion) is generated at the resonance frequency of the MEMS sensor at a low pressure as shown in the line segment (a). When the pressure becomes higher than in the case of the line segment (a), as shown in the line segment (b) and the line segment (c), an overdamped damping characteristic in which the peak disappears due to the influence of the damping of the sealing gas is obtained. . In the case of a MEMS sensor, if a peak is generated due to resonance, vibrations increase and accurate sensor characteristics cannot be detected, and there is a risk that the element is destroyed.

  Therefore, after measuring the sensor sensitivity at a plurality of locations by oscillating the vibration frequency for one MEMS sensor, the magnitude of the sensor sensitivity in the obtained line segment is flat up to the high frequency region (R section). Obtain a damping coefficient such that In FIG. 3, it is a line segment (a), and the damping coefficient C at that time is smaller than the damping coefficient C of the line segment (c). Furthermore, regarding the pressure P of the surrounding gas, the pressure P of the line segment (a) is smaller than the pressure P of the line segment (c). As for the distance (gap) g between the protrusion structures, the distance (gap) g between the protrusion structures of the line segment (a) is larger than the distance (gap) g of the protrusion structure of the line segment (c).

  Next, the sample processing method of the present embodiment will be described with reference to FIGS. Here, the case where the sample 11 is the MEMS sensor 1 will be described. FIG. 4 is a flowchart showing an example of the procedure of the manufacturing method of the MEMS sensor according to the embodiment of the present invention, and FIG. 5 shows an example of the structure before sealing the MEMS sensor processed by the ion beam processing apparatus of FIG. It is sectional drawing. 6 is a cross-sectional view showing an example of a structure at the time of measuring the pressure dependence of the MEMS sensor processed by the ion beam processing apparatus of FIG. 1, and FIG. 7 is a seal of the MEMS sensor processed by the ion beam processing apparatus of FIG. FIG. 8 is a cross-sectional view showing an example of the structure after the sealing of the MEMS sensor processed by the ion beam processing apparatus of FIG.

  First, MEMS shape processing by FIB shown in step S1 of FIG. 4 is performed. Here, the shape of the MEMS sensor 1 is processed in the semiconductor chip 2 on the silicon substrate shown in FIG. The MEMS sensor 1 is, for example, an acceleration sensor or an angular acceleration sensor. That is, in the vacuum vessel 41 of the ion beam processing apparatus 23, the semiconductor chip 2 which is the sample 11 is irradiated with the focused ion beam 36, a desired film is deposited, the shape of the MEMS sensor 1 is processed, and the semiconductor chip 2 is processed. A hole 2d is formed in the upper coating layer, for example, a silicon film. In the MEMS sensor 1, a MEMS element 2e is formed on a space 2c communicating with the hole 2d, and an electrode 2i and an electrode 2j are further formed on the element 2e.

  A lid (covering layer) 2n is formed on the semiconductor chip 2 so as to cover the space 2m on the device layer 2a in which the shape of the MEMS sensor 1 is processed. A hole portion 2d communicating with the through hole 2k is formed.

  After processing the shape of the MEMS sensor 1, electrical characteristics are measured in the FIB shown in step S2 of FIG. That is, the pressure dependence of the electrical characteristics of the MEMS is measured in the ion beam processing apparatus 23. Specifically, in the same vacuum container 41 of the ion beam processing apparatus 23, the electrical characteristics of the MEMS sensor 1 are measured a plurality of times according to a plurality of preset pressures.

  Here, the measurement of the pressure dependence will be described in detail. First, the internal pressure of the vacuum vessel 41 is adjusted by the chamber pressure adjusting device 35 shown in FIG. Next, the measurement probe 39 shown in FIG. 1 is brought into contact with the test pad 2p for sensor operation test shown in FIG. 6 electrically connected to the electrodes 2i and 2j of the MEMS sensor 1 on the semiconductor chip 2. Then, a voltage with a constant (predetermined) frequency is applied with the measurement probe 39 in contact with the test pad 2p, and the voltage flowing through the test pad 2p is measured. At this time, the voltage at the test pad 2p at each frequency is measured while shifting the frequency value to a plurality of frequency values. As a result, as shown in the sensor characteristics shown in FIG. 3, the frequency dependence of the sensor characteristics is measured by determining the line segment (characteristic, relationship between frequency and sensor sensitivity) of the MEMS sensor 1 to be measured.

  Thereafter, the pressure in the vacuum container 41 is changed (adjusted) to another preset pressure value by the chamber pressure adjusting device 35. Then, the frequency dependence of the sensor characteristic is measured at the changed pressure. That is, in the state where the pressure in the vacuum vessel 41 is changed, the voltage at the test pad 2p at each frequency is measured while swinging to a plurality of frequency values as described above. Thereby, the line segment (characteristic, frequency and sensor sensitivity) of the MEMS sensor 1 in a state where the pressure in the vacuum vessel 41 is changed is obtained, and the frequency dependence of the sensor characteristic is measured.

  In the sample processing method of the present embodiment, the measurement of the frequency dependence of the sensor characteristics described above is measured a plurality of times as the electrical characteristics of the MEMS sensor 1 in accordance with a plurality of preset pressure values. That is, the pressure dependence of the electrical characteristics of the MEMS sensor 1 is measured a plurality of times in accordance with a plurality of preset pressure values in the vacuum vessel 41 of the ion beam processing apparatus 23 that processes the MEMS sensor 1.

  Thereafter, the damping coefficient C of the formed MEMS sensor 1 is acquired based on a plurality of measurement results. That is, an appropriate damping coefficient C is determined (selected) from a plurality of damping coefficients C obtained by a plurality of measurements.

  Next, the sealing pressure shown in step S3 of FIG. 4 is determined. Here, the sealing pressure at the time of processing for sealing the hole 2d is determined based on the above-described measurement results of a plurality of times.

  Note that whether the line segment (characteristic) of the relationship between the frequency and the sensor sensitivity based on the measurement result of the formed MEMS sensor 1 is a curved line depends on the opening of the through hole 2k provided in the device layer 2a of the MEMS sensor 1. It depends on the size of the portion in plan view and the measurement results of the electrical characteristics of the MEMS sensor 1 a plurality of times described above. That is, since the size of the opening portion of the through hole 2k is determined by the shape of the edge portion 2f in the through hole 2k shown in FIG. 5, the pressure of the gas passing through the opening portion is also affected by the size of the opening portion. Therefore, the damping coefficient C of the MEMS sensor 1 is determined by the size of the opening portion of the through hole 2k of the device layer 2a in the MEMS sensor 1 and the measurement results of the electrical characteristics of the MEMS sensor 1 a plurality of times described above.

  Specifically, an appropriate sealing pressure is determined from the correlation between the size of the opening portion of the through hole 2k and the sealing pressure calculated in advance and the sensor characteristics of the MEMS sensor 1.

  Next, sealing (deposition by FIB) is performed at a predetermined pressure shown in step S4 of FIG. Here, the focused ion beam 36 is irradiated using the ion beam processing apparatus 23 shown in FIG. 1 in a state where the inside of the vacuum container 41 is set to a predetermined sealing pressure, whereby the hole 2d of the semiconductor chip 2 is irradiated. Is sealed.

  Specifically, the deposition conditions are adjusted so as to be the sealing pressure determined in step S3. That is, the pressure in the vacuum vessel 41 of the ion beam processing device 23 is adjusted by the chamber pressure adjusting device 35 to be the sealing pressure determined in step S3, and the gas source 17 is controlled by the gas source control device 18. Adjust the position.

  After adjusting the deposition conditions as described above, the hole 2d of the lid 2n formed on the semiconductor chip 2 is sealed. That is, as shown in FIG. 7, in the lid 2n on the semiconductor chip 2 on which the MEMS sensor 1 is formed, the sealed portion 2h is formed by irradiating the hole 2d in FIG. 5 with the focused ion beam 36, The hole 2d is closed (sealed) with the sealing portion 2h.

  As a result, the space 2m formed on the semiconductor chip 2 is sealed by the sealing portion 2h.

  In the sample processing method of the first embodiment, the processes from the MEMS shape processing by FIB in step S1 in FIG. 4 to the sealing (deposition by FIB) at a predetermined pressure in step S4 are performed in the vacuum of the ion beam processing apparatus 23. This is performed without opening the atmosphere in the container 41. That is, the process from the shape processing of the MEMS sensor 1 by FIB to sealing with a predetermined pressure (deposition by FIB) to form the MEMS sensor 1 is released to the atmosphere in the same vacuum vessel 41 of the ion beam processing apparatus 23. Do without.

  Thereby, in the MEMS sensor processing on the semiconductor chip 2, the processing from the shape processing to the sealing of the MEMS sensor 1 can be efficiently processed.

  After sealing, the electrical property confirmation shown in step S5 of FIG. 4 is performed. That is, the electrical characteristics of the MEMS sensor 1 in which the sealing portion 2h is formed and the hole portion 2d is sealed are measured. Here, the pressure dependence of the MEMS sensor 1 is measured in the same vacuum vessel 41 of the ion beam processing apparatus 23 by the same method as the measurement of the electrical characteristics performed in step S2. That is, the electrical characteristics of the MEMS sensor 1 are measured a plurality of times according to a plurality of preset pressures. Specifically, with the internal pressure of the vacuum vessel 41 adjusted to a predetermined pressure, the measurement probe 39 shown in FIG. 1 is brought into contact with the test pad 2p for the sensor operation test shown in FIG. A voltage having a constant (predetermined) frequency is applied, and the voltage flowing through the test pad 2p is measured. Thereby, the frequency dependence of the MEMS sensor 1 is measured.

  And based on the result of the said measurement, it progresses to the following steps shown in FIG.

  When the measurement result matches the measurement result performed in step S2 (OK), the process shown in step S6 is completed, and the manufacturing of the MEMS sensor 1 is completed.

  On the other hand, when the measurement result does not coincide with the measurement result performed in step S2 (NG), the hole 2d is sealed again. That is, when the measurement result does not coincide with the measurement result performed in step S2 (NG), the sealing in step S7 is opened. Specifically, the ion beam processing apparatus 23 irradiates the sealing portion 2h with the focused ion beam 36 to open the sealing portion 2h, that is, to form the hole 2d again.

  Thereafter, the determination of the sealing pressure shown in step S3 is performed again. That is, the sealing pressure is determined again. In other words, the sealing pressure is corrected.

  Here, the sealing pressure is re-determined from the correlation between the sealing pressure and the characteristics of the MEMS sensor 1 using the dimension of the through hole 2k calculated in advance (correcting the sealing pressure).

  After determining the sealing pressure again, sealing (deposition by FIB) is performed at the predetermined pressure shown in step S4. Here, in a state where the inside of the vacuum vessel 41 is set to the sealing pressure determined again, the focused ion beam 36 is irradiated to the hole 2d by the ion beam processing apparatus 23, and thereby the hole 2d of the semiconductor chip 2 is irradiated. Seal again. That is, the sealing part 2h is formed in the hole 2d, and the hole 2d is closed again (resealed).

  After resealing, the electrical characteristics of the MEMS sensor 1 shown in step S5 are checked again, and the frequency dependence of the MEMS sensor 1 is measured. If the measurement result matches the measurement result performed in step S2 (OK), the process shown in step S6 is completed, and the manufacturing of the MEMS sensor 1 is completed. On the other hand, when the measurement result does not coincide with the measurement result performed in step S2 (NG), the hole 2d is sealed again. In other words, the sealing pressure is determined again until the measurement result matches the measurement result performed in step S2, and the pressure dependency of the electrical characteristics of the MEMS sensor 1 is measured.

  In the sample processing method of the present embodiment, the steps S1 to S7 shown in FIG. 4 and the second step S3, step S4, and step S5 shown in FIG. In the vacuum container 41 without opening to the atmosphere.

  Thereby, in manufacture of the MEMS sensor 1, from an etching process to sealing can be performed within the same vacuum vessel 41. FIG.

  According to the ion beam processing apparatus and the sample processing method of the present embodiment, for sealing, the electrical characteristics of the MEMS sensor 1 determined by measuring the electrical characteristics of the MEMS sensor 1 a plurality of times in accordance with a plurality of preset pressures in the vacuum vessel 41. By sealing the hole 2d by pressure, a range that can be used linearly in the MEMS sensor 1 can be secured without reducing the sensor sensitivity of the MEMS sensor 1. That is, the usable range of the MEMS sensor 1 can be secured widely. That is, the ion beam processing apparatus 23 according to the present embodiment has a function of measuring the electrical characteristics of the MEMS while changing the degree of vacuum in the vacuum vessel 41. Therefore, in the sample processing method of the present embodiment, the electrical characteristics of the MEMS sensor 1 can be measured a plurality of times for each of the plurality of pressures in the vacuum vessel 41 of the ion beam processing apparatus 23 while adjusting the plurality of pressures. it can.

  Furthermore, as described above, since the etching process to sealing can be performed in the same vacuum vessel 41 in the manufacture of the MEMS sensor 1, an increase in tact time and an increase in cost of the MEMS sensor 1 are minimized. Can be suppressed.

  Here, FIG. 9 is a flowchart showing the procedure of the method for manufacturing the MEMS of the comparative example, which the inventor of the present application has compared and examined.

  In the MEMS manufacturing procedure of the comparative example shown in FIG. 9, processing is performed in the same chamber of the ion beam apparatus until sealing with the MEMS shape processing shown in step S <b> 11 and the pre-designed pressure shown in step S <b> 12. However, in the electrical property confirmation shown in step S13, when the MEMS is not an ion beam device but the MEMS is moved to a predetermined location of another manufacturing device such as a prober, and the property is measured there, it is determined that the measurement is a non-defective product The process shown in step S14 is completed.

  That is, in the MEMS manufacturing procedure of the comparative example shown in FIG. 9, the MEMS (sample) must be taken out from the chamber of the ion beam apparatus when moving to the electrical property confirmation step, which is very inefficient. Furthermore, if the electrical characteristics are not determined to be a non-defective product, the MEMS is determined as a defective product and fed back to the MEMS manufacturing process as in the process shown in FIG. 4 of the present embodiment. It is not. Therefore, the method of the comparative example shown in FIG. 9 leads to a decrease in yield in manufacturing the MEMS.

  Therefore, in the sample processing method according to the present embodiment, the electrical characteristics of the MEMS sensor 1 are measured in the vacuum vessel 41 of the processed FIB, and the sealing pressure of each MEMS sensor 1 is determined from the above measurement results. It can be determined and sealed without opening to the atmosphere in the same vacuum vessel 41.

  Thereby, in the same ion beam processing apparatus 23, the process from MEMS shape processing to sealing, and further subsequent electrical property confirmation and resealing can be performed efficiently. Further, in the same ion beam processing apparatus 23, sealing is performed with the determined sealing pressure, and subsequent electrical property confirmation and resealing are performed by feeding back in the manufacturing procedure of the MEMS sensor 1, thereby reducing the problem. Non-defective products can be reduced, and the yield of the MEMS sensor 1 can be improved.

  Moreover, since the ion beam processing apparatus 23 of this Embodiment can adjust the pressure (vacuum degree) in the vacuum vessel 41 finely by the chamber pressure adjustment apparatus 35, the sealing pressure is adjusted for each device. be able to. Therefore, acceleration sensor arrays having different sensitivities can be formed on the same semiconductor chip 2. Furthermore, sensors having different required sealing pressures can be simultaneously mounted.

  For example, an angular velocity sensor that requires a high vacuum (for example, about 100 Pa) and an acceleration sensor that requires a medium vacuum (for example, about atmospheric pressure to about 10,000 Pa) are individually sealed on the same semiconductor chip 2. It is also possible to reduce the size of the package (semiconductor device).

  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 above-described embodiment, and includes various modifications. 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, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. . In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. In addition, each member and relative size which were described in drawing are simplified and idealized in order to demonstrate this invention clearly, and it becomes a more complicated shape on mounting.

  In the above-described embodiment, the configuration in which the measurement unit 40 connected to the measurement probe 39 for measuring the characteristics of the sample 11 is provided independently in the ion beam processing apparatus 23 has been described. It may be incorporated in the calculation processing device 85.

1 MEMS sensor 2 Semiconductor chip (silicon substrate)
2a Device layer 2b Insulating layer 2c Space 2d Hole 2e Element 2f Edge 2g Gap 2h Seal 2i 2j Electrode 2k Through hole 2m Space 2n Lid (covering layer)
2p test pad 7 electron gun 8 electron beam 9 electron lens 10 electron beam scanning deflector 11 sample 12 secondary particle detector 13 stage 14 stage controller 15 hand unit 16 manipulator controller 17 gas source 18 gas source controller 19 secondary Particle detector control device 23 Ion beam processing device 31 Ion source 32 Condenser lens 33 Aperture 34 Ion beam scanning deflector 35 Chamber pressure adjusting device (pressure adjusting unit)
35a Intake device 35b Exhaust device 36 Focused ion beam (FIB)
37 Aperture Rotation Mechanism 38 Aperture Rotation Control Device 39 Measuring Probe 40 Measuring Unit 41 Vacuum Container (Chamber)
42 Manipulator 81 Ion source control device 82 Lens control device 85 Calculation processing device

Claims (13)

(A) a step of irradiating the sample with an ion beam in a vacuum container of an ion beam processing apparatus to form a hole in the sample;
(B) After the step (a), in the vacuum vessel, measuring the electrical characteristics of the sample a plurality of times according to a plurality of preset pressures;
(C) After the step (b), based on the measurement results of the plurality of times, a step of determining a sealing pressure at the time of processing for sealing the hole,
(D) After the step (c), a step of sealing the hole of the sample by irradiating an ion beam with the ion beam processing apparatus in a state where the inside of the vacuum vessel is set to the sealing pressure. ,
A sample processing method. The sample processing method according to claim 1,
A sample processing method in which the steps (a) to (d) are processed in the same vacuum vessel without opening to the atmosphere. The sample processing method according to claim 1,
After the step (d), the step (e) of measuring the electrical characteristics of the sample in which the hole is sealed;
(F) After the step (e), the hole is formed again by irradiating the ion beam with the ion beam processing apparatus based on the measurement result of the step (e).
(G) the step of determining the sealing pressure again after the step (f);
After the step (g), the hole of the sample is sealed by irradiating the ion beam with the ion beam processing apparatus in the state where the inside of the vacuum vessel is set to the sealing pressure determined again ( h) a process;
A sample processing method. In the sample processing method of Claim 3,
The sample processing method of processing from the said (a) process to the said (h) process, without air-release in the same said vacuum vessel. The sample processing method according to claim 1,
The sample is a MEMS sensor formed on a semiconductor chip,
The measurement of the electrical characteristics in the step (b) is performed by bringing a measurement probe into contact with a test pad formed on the MEMS sensor, and applying a voltage of a predetermined frequency to the MEMS sensor to obtain an output voltage at the MEMS sensor. Sample processing method to be measured. The sample processing method according to claim 1,
The sample processing method, wherein the sample is a MEMS sensor formed on a semiconductor chip, and the hole is a hole formed in a coating layer on the semiconductor chip. The sample processing method according to claim 6,
The element processing part of the said MEMS sensor is a sample processing method arrange | positioned on the space part connected to the said hole. The sample processing method according to claim 6,
In the step (b), the sample processing method of measuring the output of the MEMS sensor a plurality of times according to the plurality of pressures. An ion source;
A plurality of lenses for focusing an ion beam emitted from the ion source;
A stage for holding the sample;
A vacuum vessel in which the stage is provided and the sample held by the stage is irradiated with the ion beam to process the sample;
A pressure adjusting unit for adjusting the pressure in the vacuum vessel;
A measurement unit for measuring electrical characteristics of the sample in the vacuum vessel;
Have
Corresponding to a plurality of preset pressures, the pressure adjusting unit changes the inside of the vacuum vessel to a plurality of pressures, and the measuring unit measures the electrical characteristics of the sample a plurality of times according to the plurality of pressures. Ion beam processing equipment. In the ion beam processing apparatus according to claim 9,
The measurement unit measures the electrical characteristics of the sample a plurality of times according to a plurality of pressures set in advance in the vacuum vessel, and determines the sealing pressure based on the measurement results after the measurement. Furthermore, an ion beam processing apparatus that seals the hole formed in the sample by irradiating the sample with an ion beam in a state where the inside of the vacuum vessel is set to the sealing pressure. In the ion beam processing apparatus according to claim 9,
The sample is a MEMS sensor formed on a semiconductor chip,
In the measurement of the electrical characteristics, a measurement probe is brought into contact with a test pad formed on the MEMS sensor, and a voltage having a predetermined frequency is applied to the MEMS sensor by the measurement unit to measure an output voltage in the MEMS sensor. Ion beam processing device. In the ion beam processing apparatus according to claim 9,
The sample is an MEMS sensor formed on a semiconductor chip, and an ion beam processing apparatus in which a hole formed in a coating layer on the semiconductor chip is sealed by the ion beam. In the ion beam processing apparatus according to claim 12,
The element part of the said MEMS sensor is an ion beam processing apparatus arrange | positioned on the space part connected to the said hole.