JP4587887B2 - Sample measuring device - Google Patents

Description

  The present invention relates to a sample measuring apparatus for measuring light generated by irradiating a sample with energy rays.

  This type of sample measurement device (optical measurement device) performs physical property evaluation or analysis of a semiconductor element in a minute region of a sample using light (cathode luminescence) generated from the sample by irradiating the sample with an electron beam. is there.

  In this sample measuring apparatus, as shown in Patent Document 1, in order to collect cathodoluminescence, a condensing mirror portion is disposed so as to cover the sample, and an optical fiber or spectroscope incident outside the electron microscope is incident. The focus is formed on the slit. Since this condensing mirror part covers the sample, a passage through which the electron beam passes is provided in order to irradiate the sample with the electron beam. When measuring, since the electron beam from the electron microscope passes through the path of the collector mirror unit, the collector mirror unit must be positioned in order to set the axis of the electron beam in the channel. Don't be. Furthermore, the irradiation position where the electron beam is irradiated must be adjusted within the focal point of the condensing mirror unit.

  However, conventionally, in order to set the axis of the electron beam in the passage and to adjust the irradiation position within the focal point, a position adjusting mechanism for moving and adjusting the condensing mirror is necessary, and the apparatus becomes complicated and enlarged. Moreover, even if the position adjusting mechanism is used, there is a problem that the movement and adjustment are very troublesome.

  In particular, when a high-resolution scanning electron microscope is used, the irradiation area of the electron beam is a very small area that is less than 10 nanometers, and it is very difficult to match the irradiation position within the focal point of the collector mirror section. It is difficult and it is not easy even with skilled skills.

In addition, the lens barrel and the condenser mirror of the electron microscope are not fixed to each other, and the relative position changes due to vibration or the like, and the focal point and the irradiation position often shift.
JP 2003-157789 A

  Therefore, the present invention has been made to solve the above-mentioned problems all at once, and is capable of easily adjusting the irradiation position of the energy beam within the focal point of the condensing mirror unit and vibration while having a simple configuration. The main purpose of the present invention is to prevent misalignment of the condensing mirror due to the above.

That is, the sample measurement device according to the present invention is a sample measurement device that measures light generated by irradiating a sample with an energy beam, the energy beam generator that generates the energy beam, and the energy beam generator generated by the energy beam generator. An energy beam control means for converging the energy beam, and the energy beam control means causes the energy beam to converge so that the axis thereof coincides with the axis of the energy beam control means; and the lens barrel unit And an energy beam path for passing the energy beam converged by the lens barrel portion and irradiating the sample with the energy beam, and a focal point on the axis of the channel. A mirror surface, and a condensing mirror portion that condenses light generated from the sample by the mirror surface, and the lens barrel portion and the condensing mirror portion are detachable, The axis of the energy beam control means and the axis of the energy beam passage are positioned coaxially, and the focusing mirror is supported by the lens barrel so that the axis of the energy beam and the focal point coincide with each other. A cylindrical projecting portion that is formed on at least the upper surface of the condenser mirror portion and defines the energy beam path on the inner peripheral surface thereof, and is substantially the same as the outer peripheral surface of the cylindrical convex portion. It is comprised from the inner peripheral surface of the energy ray exit of the said lens-barrel part formed in this. Here, the light generated from the sample includes, for example, cathodoluminescence.

If it is such, although it is a simple structure, it can adjust the irradiation position of an energy beam easily in the focus of a condensing mirror part, and can prevent position shift of a condensing mirror part by vibration etc. . Further, by combining the lens barrel part and the condenser mirror part separated from each other, the condenser mirror part can be supported by the lens barrel part. Furthermore, since the positioning structure is composed of a cylindrical convex portion formed on the upper surface of the condensing mirror portion and the inner peripheral surface of the energy ray exit of the lens barrel portion, the configuration of the positioning structure is simplified. , Positioning can be further ensured.

  As described above, according to the present invention, the position of the energy beam irradiation position can be easily adjusted within the focal point of the collector mirror unit and the position of the collector mirror unit can be prevented from being displaced due to vibration or the like, although the configuration is simple. it can.

  An embodiment of the present invention will be described below with reference to the drawings.

  A sample measurement apparatus (optical measurement apparatus) 1 according to the present embodiment uses a light L (cathode luminescence) generated from a sample W by irradiating the sample W with an electron beam EB, which is an energy beam, and uses a micro region of the sample W. 1 for performing physical property evaluation and semiconductor element analysis (hereinafter referred to as an electron beam measuring apparatus). As shown in FIG. 1, the sample stage 1 and the sample W placed on the sample stage 1 are energy beams. An electron beam irradiation device 2 that irradiates an electron beam EB, a detection device 3 that is a light detection unit that splits and detects the luminescence L generated from the sample W by irradiation of the electron beam EB, and an output signal from the detection device 3 And an information processing device 4 that performs predetermined arithmetic processing to receive and evaluate the sample W (for example, stress measurement).

  Each part 1-4 is demonstrated.

  The sample stage 1 is movable in the X-axis, Y-axis, and Z-axis directions. Further, in this embodiment, the sample stage 1 is illustrated in order to reduce the peak half-value width of the sample spectrum and obtain meaningful information from the spectrum. Further, a cooling means and a temperature control mechanism are provided so that the sample stage 1 and the sample W can be cooled to a predetermined temperature of several tens of K or less.

  The electron beam irradiation device 2 is, for example, of a scanning type, and converges and scans the electron gun 21 that is an energy beam generation unit and the electron beam EB emitted from the electron gun 21 to the measurement site of the sample W. An energy beam control unit 22 including a lens mechanism such as a condenser lens 221, an aperture 222, a deflection coil 223, and an objective lens (an objective lens such as an electric field type) 224, an electron gun 21, and an energy beam control unit 22 are housed. A lens barrel portion 23 is provided. The lens barrel 23 has an energy beam exit 23A for irradiating the sample W with the electron beam EB from the electron gun 21 (see FIG. 2), and the energy beam exit 23A is an electron that is an energy beam. Opening along the axis O of the line EB. In the present embodiment, the electron gun 21 is of a hot filament electric field open type.

  The detection device 3 includes a condensing mirror unit 31, a spectroscopic unit 32, and a sensing unit 33.

  The condensing mirror part 31 is provided between the lens barrel part 23 and the sample W, collects the luminescence L generated from the sample W with a minimum loss, and guides it to the spectroscopic part 32, and is converged by the lens barrel part 23. The energy beam path 312 for passing the measured energy beam EB and irradiating the sample W with the energy beam EB, and the mirror surface 311 having the focal point F set on the axis of the channel 312 are provided. By using an electromagnetic shield material such as permalloy, iron, silicon steel plate, etc., the collector mirror unit 31 including the energy beam passage 312 can be electromagnetically shielded until just before the sample.

  The mirror surface 311 may be a parabolic mirror or an elliptical mirror, but an elliptical mirror is used in this embodiment. The ellipsoidal mirror 311 itself has the advantages of receiving and condensing light, and has the advantage that the focal point F can be freely set by the ellipsoid. On the other hand, the ellipsoidal mirror 311 has a defect that the coupling with the spectroscopic unit 32 is not successful because the imaging magnification is determined by the mechanical arrangement condition. In order to solve this problem and simplify the optical axis adjustment, the luminescence L collected by the ellipsoidal mirror 311 is transferred to the spectroscopic unit 32 using the optical fiber 321. Here, the optical axis adjustment is performed by adjusting the light incident portion 321A of the optical fiber by an adjustment mechanism (not shown) in conjunction with the focal point F of the ellipsoidal mirror 311.

  As shown in FIG. 2, the energy beam passage 312 is for irradiating the sample W with the electron beam EB emitted from the energy beam outlet 23A, and the electron beam EB that has passed through the energy beam passage 312 is irradiated with the sample. W is irradiated. The energy beam passage 312 is defined by an inner peripheral surface of a cylindrical convex portion 313, which will be described later, and the irradiation position P at which the sample W is irradiated with the electron beam EB that has passed through the energy beam passage 312 is the condensing mirror portion. It falls within the focal point F of 31.

  The spectroscopic unit 32 separates the luminescence L collected by the condensing mirror unit 31 into monochromatic light, and is configured using, for example, a monochromator.

  The sensing unit 33 measures the intensity of each monochromatic light split into a plurality of wavelengths for each wavelength by the spectroscopic unit 32, and outputs an output signal having a current value (or voltage value) corresponding to the intensity of each monochromatic light. Output. In the present embodiment, the sensing unit 33 is configured using a photomultiplier (PMT), but the device to be used may be changed depending on the wavelength region to be measured. For example, in the infrared (from 1 μm), it is preferable to use a Ge detector, a Pbs detector, an infrared PMT, or the like. Further, a CCD may be used because of its excellent photoelectric conversion efficiency, dynamic range, and S / N. According to the CCD, it is possible to detect the spectrum collectively.

  The information processing apparatus 4 is a general-purpose or dedicated computer including a CPU, a memory, an input / output interface, an AD converter, an input unit, and the like. Then, when the CPU or its peripheral device operates based on a program stored in a predetermined area of the memory, the information processing device 4 receives an output signal from the detection device 3 and scans each measurement. Calculate the stress at the point.

  A specific calculation method is to receive the light intensity signal from the detection device 3, generate spectrum data that is data indicating a spectrum waveform, and smooth the spectrum waveform indicated by the spectrum data. Next, a differential operation is performed on the waveform obtained by smoothing, and the wavelength at the time when the obtained value is inverted from plus to minus is set as the peak wavelength. The peak wavelength may be obtained by fitting with a predetermined function. Then, the stress acting on the sample W is calculated based on the amount of displacement between the peak wavelength obtained from the sample W to be measured and the reference peak wavelength.

  The principle of this stress calculation will be briefly described. The relationship between the stress existing at the site irradiated with the electron beam EB of the measurement sample W and the peak wavelength obtained can be linearly approximated until the magnitude of the stress is about 10 GPa. It is indicated by (1).

ν _σ = ν ₀ + Π · σ (1)

Here, ν _σ is the peak wavelength of the measured spectrum, ν ₀ is the reference peak wavelength, σ is a tensor indicating the stress acting on the measurement sample W, and Π is called a PS (Piezo-Spectroscopic) coefficient. A position-independent tensor that depends only on. Ν ₀ and Π are stored as correlation data in a storage unit in the memory. Such correlation data is statistically obtained by applying a plurality of known stresses to a sample equivalent to the measurement sample W.

  Here, the reference peak wavelength is, for example, when measuring the residual stress of the sample W, from another equivalent sample where no residual stress exists, or from a portion where the residual stress does not exist in the sample W. It identifies from the acquired fluorescence spectrum waveform. On the other hand, for example, when it is desired to measure the internal stress generated due to the external force applied to the sample W, the reference peak wavelength is obtained from the fluorescence spectrum waveform obtained from the sample W in the state where no external force is applied. Identify. Data indicating the reference peak wavelength is stored, for example, in a storage unit set in a predetermined area of the memory.

  Therefore, as shown in FIGS. 2 and 3, the electron beam measuring apparatus according to the present embodiment is provided with the condensing mirror unit 31 in the lens barrel unit 23 so that the axis O and the focal point F of the energy beam EB coincide with each other. By supporting them, they are integrally configured so that the relative position between the lens barrel portion 23 and the condenser mirror portion 31 is constant. In the present embodiment, since the lens barrel portion 23 and the condensing mirror portion 31 are separated from each other, the positioning structure 5 is provided to integrally configure the lens barrel portion 23 and the condensing mirror portion 31. .

  The positioning structure 5 enables the lens barrel portion 23 and the condensing mirror portion 31 to be detachable, while positioning the axis of the energy beam control means 22 and the axis of the energy beam passage 312 coaxially, and the energy beam EB The condensing mirror part 31 is supported by the lens barrel part 23 so that the axis O and the focal point F coincide with each other. And it is comprised from the convex structure provided in one of the lens-barrel part 23 and the condensing mirror part 31, and the concave structure corresponding to the said convex structure provided in the other, and specifically, on the condensing mirror part upper surface 31A A cylindrical convex portion 313 which is formed and defines the energy beam passage 312 on the inner peripheral surface, and an inner periphery of the energy beam outlet 23A of the lens barrel portion 23 which is formed substantially the same as the outer peripheral surface of the cylindrical convex portion 313. And a surface. Then, the cylindrical convex portion 313 is continuously fitted into the inner peripheral surface of the energy beam emission port 23A (in this embodiment, as shown in FIG. 1, in the objective lens 224 formed at the lower end of the lens barrel portion 23). Integrate.

  The cylindrical convex portion 313 has a cylindrical shape, and its outer diameter is substantially the same as the inner diameter of the energy beam exit port 23 </ b> A, and is provided on the upper surface 31 </ b> A of the condenser mirror portion 31. Further, the energy ray passage 312 passes through the central axis of the cylindrical convex portion 313, and the energy ray passage 312 opens at the upper surface central portion 313A (see FIG. 3) of the cylindrical convex portion 313. Thereby, the energy ray exit port 23A and the energy ray passage 312 are continuously formed by fitting the cylindrical convex portion 313 to the energy ray exit port 23A.

  According to the electron beam measuring apparatus 1 configured as described above, since the condensing mirror unit 31 is supported by the lens barrel unit 23, it is not necessary to adjust the position of the condensing mirror unit 31 for each measurement. Although the configuration is simple, the position of the irradiation position P of the electron beam EB can be easily adjusted within the focal point F of the condensing mirror unit 31, and the positional deviation of the condensing mirror unit 31 due to vibration or the like can be prevented. Therefore, since the irradiation position P of the electron beam EB always falls within the focal point F, all the light L generated by being excited at the irradiation position P can be collected, and the decrease in the detection signal can be suppressed as much as possible. .

  In addition, the positioning structure 5 is composed of the energy beam injection port 23A and the cylindrical convex portion 313, and is continuously integrated by fitting the cylindrical convex portion 313 to the energy beam injection port 23A. Can be performed simultaneously, and the labor of positioning can be further saved.

  The present invention is not limited to the above embodiment.

  For example, in the above-described embodiment, the lens barrel portion and the collector mirror portion separated from each other are continuously integrated. However, as shown in FIG. 4, the lens barrel portion and the collector mirror portion may be integrally formed. good.

  According to this, it is not necessary to adjust the position of the condenser mirror part at all, and the positional deviation of the condenser mirror part due to vibration or the like can be prevented.

  Moreover, in the said embodiment, although the positioning structure was comprised from the energy-beam exit and the cylindrical convex part, it is not restricted to this, If a condensing mirror part is directly or indirectly supported by a lens-barrel part Good. As one of the methods, a connecting member may be provided in addition to the lens barrel portion and the condensing mirror portion, and the lens barrel portion and the condensing mirror portion may be connected using this connecting member.

  Furthermore, in the said embodiment, although the ellipsoidal mirror was used as a condensing mirror part, it is not restricted to this, For example, you may use a parabolic mirror. In this case, when the light L from the sample W is reflected due to the characteristics of the parabolic mirror, it becomes parallel light. Therefore, as shown in FIG. 5, in order to collect the parallel light on the light incident part 321A of the optical fiber 321. A convex lens 314 is provided between the condenser mirror unit 31 and the optical fiber 321.

  In addition, the energy line passage provided in the condensing mirror portion of the embodiment may be a differential exhaust aperture. In other words, when measuring biological samples, it is necessary to evacuate the interior of the lens barrel to a high vacuum while evacuating the chamber with the collector mirror and sample stage to a low vacuum. It may be made to function as an aperture for exhausting while maintaining the above.

  In addition, some or all of the above-described embodiments and modified embodiments may be combined as appropriate, and the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. .

The typical block diagram which shows the optical measuring device which concerns on one Embodiment of this invention. The partial expanded sectional view of the lens-barrel part and condensing mirror part in the embodiment. The assembly drawing of the lens-barrel part and condensing mirror part in the embodiment. The partial expanded sectional view of the lens-barrel part and condensing mirror part in other embodiment. The typical block diagram which shows the optical measuring device which concerns on other embodiment of this invention.

1 ... Sample measuring device EB ... Energy beam (electron beam)
W ... Sample 21 ... Energy ray generator (electron gun)
23A ... Energy beam exit 23 ... Lens barrel 311 ... Mirror surface 312 ... Energy beam passage 31 ... Condensing mirror unit O ... Energy beam axis 5 ... Positioning structure 313: cylindrical convex portion F: focal point P: irradiation position

Claims (1)

A sample measuring device for measuring light generated by irradiating a sample with energy rays,
An energy ray generating unit for generating energy rays;
A mirror that has energy beam control means for converging the energy beam generated by the energy beam generator, and that causes the energy beam control means to converge the energy beam so that its axis coincides with the axis of the energy beam control unit; A tube part;
An energy beam path that is provided between the lens barrel and the sample, passes an energy beam converged by the lens barrel, and irradiates the sample with the energy beam, and is focused on the axis of the channel. And a mirror surface that collects the light generated from the sample by the mirror surface,
While allowing the lens barrel and the condensing mirror to be detachable, the axis of the energy beam control means and the axis of the energy beam passage are positioned coaxially, and the axis of the energy beam and the focal point are aligned. A positioning structure for supporting the light collecting mirror part in the lens barrel part so as to match,
The positioning structure is formed on at least the upper surface of the condensing mirror part, and has a cylindrical convex part defining the energy ray path on the inner peripheral surface, and the mirror formed substantially the same as the outer peripheral surface of the cylindrical convex part A sample measuring device comprising an inner peripheral surface of an energy ray injection port of a cylindrical portion .