CN1790036A - Electro-optical detector capable of calibrating voltage - Google Patents

Abstract

The voltage-calibrable electro-optic detector of the invention belongs to a device for integrated circuit detection. It consists of a laser 8, a microscope objective lens 13, an electro-optical probe 14; an illumination source 15, a filter mirror 16, a photoelectric detector 26, etc.; , its lower surface is plated with ground conductive film 3, the electro-optical medium layer 4 under the ground conductive film 3 is formed, the polarization direction of electro-optic medium layer 4 and the beam propagation direction are all parallel to the normal direction of ground conductive film 3. The amplitude of the voltage signal in the circuit corresponding to the electro-optic signal output by the electro-optic probe of the present invention can be calibrated, which enhances the application of the electro-optic detection technology in the internal characteristic test of integrated circuit chips and circuit fault diagnosis; the electro-optic probe has higher voltage sensitivity and Higher spatial resolution for detecting electric field distribution; no observable interference to circuit working state; avoiding electro-optic string signals between adjacent signal transmission lines.

Description

Electro-optic detector with calibrated voltage

technical field

The invention belongs to a device for integrated circuit detection, in particular to a detector for nondestructively detecting voltage signals in microstrip transmission lines in integrated circuits by using electro-optical effects.

Background technique

In order to increase the integration and operating speed of integrated circuits, efforts are being made to reduce the size of devices in integrated circuit chips. In the development process of this high-speed large-scale integrated circuit, problems such as leakage, thermal effects, parasitic parameter effects in circuit chips, and uncertainty of device model parameters have become obstacles to further improving the yield and reliability of device chips. As we all know, it is impossible for a device with a low yield rate to improve its reliability through a simple screening process; a highly reliable device is manufactured with a highly reliable design and a highly reliable process. Therefore, how to improve the design and manufacturing technology of high-speed large-scale integrated circuits, improve the yield and reliability of device chips, and thus improve the application level of devices is a research topic of great significance.

In order to improve the design and manufacturing process in the development process of the device, it is necessary to detect, analyze and diagnose the internal characteristics of the integrated circuit chip obtained in the development process. There are mainly three types of devices currently used for this detection: scanning electron microscopes, atomic force microscopes, and electro-optical sampling detection devices. These devices are all measured by the interaction between the probe and the signal electric field on the circuit under test, and the measured signal amplitude mainly depends on the normal component of the signal electric field. However, the ratio of the normal component and the transverse component of the signal electric field on the circuit under test is closely related to the circuit wiring near the detection point. Figure 1 describes a coplanar waveguide circuit with microstrip size jump, there are two adjacent conductive metal microstrip lines AB and A ₁ B ₁ , under quasi-static approximation conditions, at any time t between them There is the same potential difference V(t) between them. However, the distance AA ₁ between detection point A and its nearest neighbor conductor is smaller than the distance BB ₁ between detection point B and its nearest neighbor conductor. Because point A and point B are on the same conductor, the signal voltage on these two points should be the same, but because the electric force line strives to be shortened, the normal component of the signal electric field at point A (the direction perpendicular to the paper) will be smaller than that of point B The normal component of the signal electric field at the point. Since the signal amplitude detected by the probe is determined by the normal component of the electric field of the signal, when the same voltage signal is measured at these two different detection points, different signal amplitude values will be obtained. For example, in the electro-optic detection schemes reported abroad, a tiny electro-optic crystal is used as a probe, such as a GaAs crystal cut and polished along the (100) crystal plane, and it is placed on the microstrip circuit under test during measurement. An air gap inevitably exists between the crystal surface and the metal film of the microstrip line, as shown in Figure 2. When the microstrip line that transmits the electrical signal under test is very close to the adjacent microstrip line, the inductive effect between the conductors makes the electric force line (or electric field flux) more in the air gap directly on the microstrip line. The electric field component passing vertically upward into the electro-optic crystal is relatively reduced. As shown in Figure 1, for the same voltage signal, even if the microstrip line has ideal conductivity, the amplitude of the electro-optical signal measured at point A is smaller than that at point B. As a result, the electro-optic signal waveforms and relative time relationships measured at points A and B are consistent with reality, but the amplitudes of electro-optical signals measured at these two different points are different due to the influence of adjacent wiring. Voltage calibration cannot be performed directly by experiment. This is a problem to be solved in the various electro-optic probes reported so far. In order to analyze the electronic characteristics inside the integrated circuit chip or diagnose faults, not only the signal waveform, time and phase on the circuit nodes need to be measured, but also the voltage distribution needs to be measured.

Contents of the invention

The technical problem to be solved by the present invention is to design a detector that can not only measure the waveform, time, frequency, phase relationship, and relative amplitude of the voltage signal, but also determine the absolute value of the signal voltage amplitude. The electro-optic probe of the invention can realize voltage calibration for the amplitude of the electro-optic signal measured from the electric signal transmission line. This is a new development of electro-optical detection technology, which will lead to the further development of dynamic characteristic detection and fault diagnosis technology inside integrated circuit chips.

An electro-optic detector with calibrated voltage of the present invention is composed of an electro-optic detection unit, a detection point position monitoring unit and an integrated circuit test bench (see Figure 4 and Figure 5 of the accompanying drawings):

The component parts of said electro-optical detection unit are according to the order of the optical path, the detection beam sent by the laser drive device 7 and the laser 8 is converted into circularly polarized light through the collimator lens 9, the polarizing beam splitter 10, and the λ/4 wave plate 11, and passes through The beam expander 12, the probe light beam splitter 18 and the microscope objective lens 13 are injected into the electro-optic probe 14 and are focused onto the metal microstrip transmitting the electrical signal in the integrated circuit chip 19 to be tested, and the metal microstrip is reflected back When the probe light passes through the electro-optic probe 14 in reverse, it is converted into intensity-modulated signal light, and then passes through the microscope objective lens 13, the probe beam splitter 18, the beam expander 12, the λ/4 wave plate 11 and the polarization beam splitter 10, The returned signal light is completely reflected by the polarizing beam splitter 10 to the photodetector 26, and the electrical signal output by the photodetector 26 is input to the signal amplifier and storage display device 27;

In the optical path of the above-mentioned electro-optical detection unit, the optical path structure adopts the coaxial optical path form, and the detection light is converted into intensity-modulated signal light during the round-trip process in the electro-optical probe 14, and the λ/4 wave plate 11 and the polarization beam splitter 10 The function is only to reflect all the detection light carrying the signal to the photodetector 26 under the coaxial optical path condition. For the structure of the coaxial optical path, refer to Figure 4 of the accompanying drawings. A non-coaxial optical path can also be used to complete the same electro-optical detection function. That is, keep an included angle between the reflected probe light and the incident probe light, and use the wedge-shaped reflector 29 to reflect all the intensity-modulated probe light reflected back into the photodetector 26, and no longer use λ The /4 wave plate 11 and the polarization beam splitter 10 can complete the same electro-optic detection function. For the non-coaxial optical path structure, refer to Figure 5 of the accompanying drawings.

The component parts of said detection point position monitoring unit are according to the light path sequence, the spontaneous radiation light sent by the illumination light source 15 selects the appropriate waveband as the illumination light through the filter mirror 16, passes through the illumination light beam splitter 17, the detection light beam splitter Mirror 18, microscope objective lens 13 and electro-optical probe 14, irradiate the device surface of the integrated circuit chip 19 to be tested and be reflected back, and the reflected illumination light passes through electro-optic probe 14, microscope objective lens 13 and probe light splitting in reverse. The mirror 18 is combined with the part of the detection light that passes through the detection light beam splitter 18, and is imaged on the CMOS camera head of the video camera 20 through the illumination light beam splitter 17, and displays the detected integrated circuit chip 19 on the monitor 21. The device pattern and the position of the probe light focusing spot.

The feature of the detection point position monitoring unit is to use the filter 16 to select the illumination light of an appropriate wavelength. The device surface of the same tested integrated circuit chip 19 is imaged on the CMOS camera head of the camera 20 through the same microscope objective lens 13 .

The components of said integrated circuit test bench are probe station 25 , probes 24 and integrated circuit test power supply 28 .

Said laser driver 7 is a microwave signal generator or a DC power supply.

Said electro-optic probe 14 is made of transparent substrate 1, anti-reflection film 2 plated on the upper surface of transparent substrate 1, grounded conductive film 3 plated on the lower surface of transparent substrate 1, and a layer of electro-optical medium under the grounded conductive film 3. The polarization direction of the electro-optical medium layer 4 is parallel to the normal direction of the ground conductive film 3 .

The said grounding conductive film 3 preferably has a reflectivity of 0.3-0.4 and a transmittance of 0.6-0.7 to the detection light wavelength; said electro-optic medium layer 4 can be a polarized polymer film with a thickness in the range of 0.2-2 μm . The electro-optic medium layer can be any kind of electro-optic material film with rotational axis symmetry, one of which is organic chromophore/silicon oxide hybrid electro-optic polymer, which is based on disperse red or disperse red silylating agent As a chromophore (electric dipole molecule) material, it is prepared by a sol-gel method with tetraethyl orthosilicate as a cross-linking agent.

The transparent substrate can be transparent silicon oxide glass, or a transparent crystal with no birefringence effect on the probe light, its upper and lower surfaces are approximately parallel and optically polished, and the anti-reflection film on the upper surface interferes with the reflection of the probe light The effect is so small that it can be ignored, and the reflectivity of the grounded conductive film on its lower surface to the probe light can just make the unmodulated reflected light generated by it, and the signal electric field applied by the electro-optical medium layer vertically reflected from the electrical signal transmission line The phase-modulated reflected light is superimposed and completely converted into intensity-modulated signal light through interference.

The electro-optic detector with calibrated voltage of the present invention has the following application effects:

1. The condition that the vertical distance from the measured point on the metal microstrip line that transmits electrical signals to the reference electrode surface in the electro-optical probe (ie, the grounded conductive film 3) is equal to or less than the distance between the measured point and the nearest neighbor conductor Next, the amplitude of the electro-optical signal output by the electro-optical probe is proportional to the amplitude of the voltage signal transmitted on the metal microstrip line. Therefore, the voltage value corresponding to the amplitude of the electro-optic signal can be calibrated, or can be calibrated. The reference electric signal of the calibration voltage can be measured by an oscilloscope from the signal input pin of the integrated circuit chip, and the corresponding electro-optical signal can be measured by an electro-optical probe from the metal microstrip connection line at the input joint of the integrated circuit chip.

2. Because the voltage signal amplitude in the circuit corresponding to the electro-optical signal output by the electro-optic probe of the present invention can be calibrated, it can not only measure the signal waveform on the circuit node in the integrated circuit chip, time and phase relationship, but also allow the measurement of various The distribution of the signal voltage at a node; it also allows the determination of the distribution of the DC bias voltage in the circuit if it is chopped into a very low frequency square wave. This significantly enhances the application of electro-optical detection technology in the internal characteristic testing and circuit fault diagnosis of integrated circuit chips.

3. Because the electro-optical probe of the present invention can measure the absolute voltage value of the electric signal on the circuit node in the integrated circuit chip, thereby allowing the S parameter of measuring the microwave integrated circuit (MMIC) with the network analyzer.

4. The dielectric constant of organic chromophore/silicon oxide hybrid electro-optic polymer is smaller than that of other electro-optic materials, but its electro-optic coefficient can reach the order of 50pm/V, making this material into The electro-optic probe has high voltage sensitivity and high spatial resolution to detect electric field distribution.

5. The wavelength of the probe light used in the electro-optical detection system is greater than the band gap absorption wavelength of the circuit substrate to be tested. The probe light irradiates on the substrate and does not excite photoelectrons, so there is no observable disturbance to the working state of the circuit. Therefore, there is no total reflection film for detecting light on the end face of the electro-optical probe of the present invention in contact with the circuit under test. This not only significantly reduces the shielding effect on the electric field of the signal, but also results in a transmission-assisted increase in spatial resolution. Because, even if the diameter of the focused spot of the probe beam is larger than the metal microstrip linewidth, as long as the diameter is smaller than the sum of the microstrip linewidth and its nearest neighbor conductor spacing, the microstrip transmission line can be measured effectively by using the reflection of the measured microstrip For the generated electro-optic signal, part of the probe light that is not reflected back will be scattered and lost through the substrate, so as to avoid the electro-optic signal between adjacent signal transmission lines. At present, the commercially available microscope objective lens with long focal length and large numerical aperture can focus the spot diameter of the probe light to less than 1 μm. According to the above theory, the microstrip linewidth allowed to be detected can be less than 0.5 μm. However, specific voltage calibration should be done for different microstrip line widths.

Description of drawings

FIG. 1 is a schematic diagram of different signal amplitude values obtained when the same voltage signal is measured at two different detection points using the background technology.

FIG. 2 is a schematic diagram of the background art when a tiny electro-optic crystal is used as a probe, and an air gap inevitably exists between the crystal surface and the metal film of the microstrip line.

Fig. 3 is a structural schematic diagram of the electro-optic probe of the present invention.

Fig. 4 is a schematic diagram of the coaxial optical path structure of the electro-optical detector with calibrated voltage of the present invention.

Fig. 5 is a schematic diagram of the non-coaxial optical path structure of the electro-optical detector with calibrated voltage of the present invention.

Detailed ways

Embodiment 1 The structure and working principle of the electro-optical probe of the present invention

The structure of the electro-optic probe of the present invention is shown in FIG. 3 . The transparent substrate 1 can be transparent silicon oxide glass or a transparent crystal that has no birefringence effect on the probe light. A layer of anti-reflection film 2 is coated on the upper surface of the transparent substrate 1, and a layer of grounded conductive film 3 with selective reflection characteristics is coated on the lower surface of the transparent substrate 1. The conductive film has a reflectivity r ₁ of about 0.35 for the wavelength of the probe light. and a transmittance t ₁ of around 0.65. The optimal selection of the specific values of the reflectivity _r1 and the transmittance _t1 is related to the reflectivity _r2 of the metal microstrip line 5 transmitting electrical signals of the circuit under test to the probe light. 6 in FIG. 3 is a grounded metal microstrip line, and the microstrip line 5 for transmitting electrical signals and the grounded metal microstrip line 6 form a coplanar waveguide. The transmittance of the ground conductive film 3 to the illuminating light is sufficient to ensure that the camera 20 can produce a resolvable image display for the observed integrated circuit pattern. When applied, the grounded conductive film 3 is grounded. A layer of polarized polymer film composed of organic chromophore and silicon dioxide cross-linked network is coated on the grounding conductive film 3 , that is, the electro-optical medium layer 4 , and its polarization direction is parallel to the normal direction of the grounding conductive film 3 . The thickness of the polarized polymer film of the electro-optic medium layer 4 is in the range of 0.2-2 μm, which is selected according to practical needs. The electro-optic medium layer 4 of the present invention is made of disperse red/silicon oxide mixed material, which has high electro-optic coefficient and temperature stability meeting practical requirements.

The operating principle of the electro-optical probe of the present invention is as follows: the vertically incident illumination light and the probe light with intensity of 1 _in reach the selectively reflective grounding conductive film of the transparent substrate 1 lower surface through the anti-reflection film 2 on the upper surface of the transparent substrate 1 3. Then pass through the electro-optical medium layer 4 and focus vertically onto the chip of the device under test. In order to prevent the illumination light from exciting photogenerated carriers in the integrated circuit substrate, weak illumination light is used, so the transmittance of the anti-reflection film 2 and the ground conductive film 3 to the illumination light is sufficient. The illuminating light forms an image of the circuit pattern under test, and the focused light spot of the probe light falls on the metal microstrip line 5 transmitting electrical signals under test. The grounded conductive film 3 has a reflectivity of about 0.35 for the probe light, denoted as r ₁ , and a transmittance of about 0.65, denoted as t ₁ . The reflected light intensity of the detection beam on the grounded conductive film 3 is I _r1 =r ₁ I _i . The metal microstrip line 5 that transmits electrical signals has a reflectivity r ₂ of about 0.6 for the probe light, and the reflected light intensity of the probe beam on the metal microstrip is r ₂ t ₁ I _i . The light reflected by the metal microstrip 5 that transmits electrical signals returns to the grounded conductive film 3 , and is phase-modulated by the signal electric field from the metal microstrip 5 that transmits electrical signals during its round trip in the electro-optical medium layer 4 . Due to the symmetry (∞mm) of the electro-optic medium layer 4 with its polarization direction as the axis of symmetry, and the direction of the signal electric field, the polarization direction of the electro-optic medium layer 4 and the propagation direction of the probe beam are all parallel to the direction of the ground conductive film 3 In the normal direction, the probe light is only phase modulated. An electro-optic phase-modulated part of the probe light with an intensity of t ¹ r ₂ t ₁ I _i passes through the grounded conductive film 3 and meets the unmodulated reflected light I _r1 , t ¹ is the detection light transmitted from the electro-optic medium layer 4 to the ground The transmittance of the conductive film 3 , when the two meet and interfere, the phase-modulated light is converted into intensity-modulated light, which becomes an optical signal that can be received by the photodetector 26 (which may be a photodiode). This is the first order effect of the electro-optic probe of the present invention. There is also a part of the probe light with intensity r ¹ r ₂ t _{1 I} reflected by the grounded conductive film 3 re-radiating to the metal microstrip line 5 that transmits electrical signals through the electro-optic medium layer 4, and then between the grounded conductive film 3 and the transmitted electrical signal The process of multiple reciprocating reflections similar to that in the Fabry-Perot (FP) cavity occurs between the metal microstrip lines 5, r ¹ is the reflectivity of the grounded conductive film 3 to the probe light from the electro-optic medium layer 4. As a result, the total reflected light intensity reflected by the metal microstrip line 5 that transmits electrical signals and returns to the original incident light path through the grounded conductive film 3 is

I _r2 ＝(1-r ₁ ) ² r ₂ I _in /(1+r ₁ r ₂ -2·COS ² δ·√r ₁ r ₂ )

The phase factor δ is the phase shift generated by the probe light going back and forth in the electro-optic medium layer 4 once. In the above discussion, the light reflection effect on the interface between the electro-optic medium layer 4 and the air gap is neglected, because the refractive index of the disperse red/silicon oxide hybrid electro-optic film used is close to that of air. When there is a voltage signal on the metal microstrip line 5 that transmits electrical signals, the electric field of the signal enters the electro-optical medium layer 4 through the air gap, and the electric force line terminates at the grounded conductive film 3 . The signal electric field modulates the phase of the probe light through the electro-optical medium layer 4 . After the part of the probe light I r2 that has been phase modulated and reflected from the metal microstrip line 5 that transmits the electrical signal into the original incident light path meets the unmodulated part of the probe light I _r1 that is directly reflected back from the grounded conductive film ₃ Coherently superimposed, the result is that the phase modulation is converted into an intensity modulation. In order to achieve the most effective level of this conversion, that is, to obtain the maximum intensity modulation signal, it should approximately satisfy I _r1 ≈ I _r2 , or written as

r ₁ I _i ≈(1-r ₁ ) ² r ₂ I _in /(1+r ₁ r ₂ -2·COS ² δ·√r ₁ r ₂ ).

In fact, since the reflection, scattering and transmission of the detection beam by the metal microstrips at different positions inside the integrated circuit are different, a rough average value of about 0.6 is provided for _r2 based on experience. If the grounding conductive film 3 has a reflectivity of 0.36 to the probe light of λ=1.3 μm, and the ordinary light refractive index n ₀ of the dispersed red/silicon oxide hybrid polarized polymer of the electro-optic medium layer 4 is 1.47, from the transmission of electrical signals The detection light intensity reflected by the metal microstrip line 5 is about 0.357I _in , which approximately satisfies the requirement of I _r1 ≈I _r2 .

Embodiment 2 Electro-optic detection optical unit structure used in conjunction with the electro-optic probe of the present invention

The electro-optic detection optical unit used in conjunction with the electro-optic probe of the present invention is shown in FIG. 4 . Wherein, 7 is the driving device of the laser. If electro-optic sampling measurement is to be done, the driving device 7 of the laser should be a microwave signal generator, and the microwave power of its output drives the laser device 8 to generate a gain switch ultrashort pulse beam; if the electro-optic measurement of continuous light is to be done, the driving device 7 of the laser Should be a DC power supply. The laser 8 may be a laser diode, which generates near-infrared light of any wavelength within the range of 1.25 microns to 1.3 microns as probe light. The detection beam is transformed into parallel light by the collimator lens 9, its polarization direction is determined by the polarizing beam splitter 10, the detection beam is transformed into circularly polarized light by the λ/4 wave plate 11, and the diameter of the detection beam is slightly larger by the beam expander 12. Greater than the clear aperture of the microscope objective lens 13 with long focal length and large aperture. The illuminating light source 15 is a spontaneous radiation lamp, and the spontaneous radiating light emitted by it is selected by a filter mirror 16 to select an appropriate band as illuminating light, reflected by the illuminating light beam splitter 17, to the detection beam splitter 18 and from the beam expander 12 The probe beams meet and are projected onto the microscope objective lens 13 together. The probe light and illumination light are converged into the electro-optic probe 14 by the microscope objective lens 13 (the structure of the electro-optic probe 14 is as described in Embodiment 1), and the converging probe beam passes through the electro-optic medium layer 4 in the electro-optic probe 14, and the focus falls on the electro-optic probe 14. Measure the device surface of the integrated circuit chip 19. The wavelength of the illuminating light selected by the optical filter 16 just makes the illuminating light pass through the microscope objective lens 13 and when the device surface of the integrated circuit chip 19 under test is imaged, the microscope objective lens 13 is simultaneously aligned with the object plane of the illuminating light and the focal plane of the probe light. The surface of the tested device is coplanar, and as a result, the device pattern of the integrated circuit chip 19 and the position of the focused light spot of the detection beam in the device pattern are displayed on the monitor 21 of the camera 20 . The electro-optic probe 14 can be lifted from the device surface of the integrated circuit chip 19 or placed on a certain position to be measured on the device surface by using the electro-optic probe holder 22 and its position fine-tuner 23 . The device on the integrated circuit chip 19 is driven by the integrated circuit test power supply 28 and the probe 24, and the position to be detected can be selected in a relatively large range by the position fine-tuning mechanism of the probe station 25. The devices on the integrated circuit chip 19 are each at a certain level during operation, thus generating their own electric fields. When the electro-optic probe 14 is close to or lands on the device surface of the integrated circuit chip 19, the electric field emitted by the device is distributed in the electro-optic medium layer 4 of the electro-optic probe 14, and the electric force line is terminated on the grounded conductive film 3 in the electro-optic probe 14. The induced refractive index of the electro-optic medium layer 4 changes with the electric field. As described in Embodiment 1, the probe light is subjected to phase modulation, which is transformed into intensity modulation through the reflection interference process in the electro-optic probe 14 . Most of the probe light reflected from the electro-optical probe 14 is reflected by the probe beam splitter 18 to the beam expander 12 , and then reaches the λ/4 wave plate 11 . The λ/4 wave plate 11 reconverts circularly polarized light into linearly polarized light, but its polarization direction is perpendicular to that of the incident light, and is then reflected by the polarization beam splitter 10 to the photodetector 26 . The electrical signal output by the photodetector 26 is a replica of the electrical signal on the internal components of the integrated circuit chip 19 , and it is input to the signal amplifier and storage display device 27 .

In the above optical structure, the purpose of applying the polarization beam splitter 10 and the λ/4 wave plate 11 is only to separate the reflected probe light carrying the intensity modulation signal from the incident probe light under the condition of maintaining the coaxial optical path structure , and input all the reflected intensity-modulated detection light into the photodetector 26. Also can not need coaxial optical path structure, Fig. 5 provides the non-coaxial optical path structure of the electro-optical detector of the present invention that can calibrate voltage, just need not use polarization beam splitter 10 and λ/4 wave plate 11 in this structure , as long as an appropriate small angle is maintained between the reflected detection light and the incident detection light, and the wedge-shaped reflector 29 is used to reflect all the reflected detection light modulated by intensity into the photodetector 26, then The same electro-optic detection function can be accomplished.

The above-mentioned optical structure for monitoring that determines the position of the focused spot on the electrical signal transmission line through the monitor 21 is characterized in that a spontaneous radiation lamp is used as the illumination source 15, and the illumination light of an appropriate wavelength and intensity is sorted out by a filter 16 , through the illumination light beam splitter 17 and the detection light beam splitter 18, the illumination light and the detection light are combined, and through the same microscope objective lens 13 used for the detection beam focusing, the illumination light is irradiated to the circuit under test through the electro-optic probe 14 Above, while the detection light is focused on the surface of the circuit device, the illumination light causes the pattern of the circuit device under test to be imaged on the CMOS camera head of the camera 20 .

The difference between the above-mentioned electro-optical detection optical system of the present invention and other existing electro-optical detection optical systems is firstly that the detection beam here is only subjected to phase modulation without polarization modulation, and is coherently superimposed by phase-modulated light and unmodulated light and converted to intensity modulation. The role of the polarizing beam splitter 10 and the λ/4 wave plate 11 here is only to fully reflect the probe light carrying the intensity modulation signal fed back by the electro-optic probe 14 into the photodetector 26 under the condition of maintaining the coaxial optical path structure go. Secondly, the illuminating light source here is a spontaneous radiation lamp, and the illuminating light of the appropriate band is selected from the spontaneous radiating light by filter 16, so as to ensure that when the light of this band passes through the objective lens 13 to observe the device pattern of the circuit chip 19, imaging The object plane of the object plane and the focal plane when the probe light is focused by the object lens 13 are just coplanar with the device surface of the integrated circuit chip 19 to be tested, so that the monitor 21 of the camera 20 can display the focused light spot of the probe beam and the surface of the device to be tested. Clear image of the surface.

The preparation of embodiment 3 electro-optical medium layer

The electro-optic medium layer 3 can be any electro-optic material film with rotational axis symmetry, and a convenient and applicable material is a non-linear optical material film prepared by sol-gel method.

Dissolve the appropriate proportion of chromophores and crosslinking agent materials in the same solvent to form a sol, and evenly spin-coat the sol on the grounded conductive film 3 of the transparent substrate 1, and perform corona polarization and heat curing on the formed dielectric film Processing, that is to obtain a polarized polymer film with electro-optic effect, the polarization direction is the normal direction of the grounding conductive film 3, and also the direction of the rotational symmetry axis of the film material, and the thickness of the film requires that when the electro-optic probe 14 contacts the electric signal transmission line The vertical distance from the measured point on the electrical signal transmission line to the grounded conductive film 3 is equal to or less than the distance from the point to its nearest neighbor conductor, so as to realize the condition that the signal electric field is approximately parallel to the normal direction of the grounded conductive film 3 .

Disperse red or disperse red silylating reagent can be used as chromophore (electric dipole molecule) material, tetraethyl orthosilicate (TEOS) can be used as crosslinking agent, dimethylformamide (DMF) can be used as solvent, and the formula can be massaged Er ratio is disperse red silylating agent: ethyl orthosilicate: dimethylformamide: hydrochloric acid: pure water=1:8～12:18～22:10:30～40. Mix the chromophore material and the crosslinking agent material in a certain proportion, dissolve it with dimethylformamide, add acid water dropwise, and stir evenly at room temperature to make it undergo hydrolysis and polycondensation reactions. When the sol reaches the required film thickness When the viscosity is low, it is evenly spin-coated on the grounding conductive film 3 of the transparent substrate 1 to form a polymer film, and then it undergoes curing and polarization treatment to become a polymer electro-optic film.

When manufacturing the electro-optic probe of the present invention, the formula used once was 0.1Mol of disperse red silylating agent, 1.0Mol of orthoethyl silicate (TEOS), 2.0Mol of dimethylformamide (DMF), 3.5Mol of Pure water and 1.0Mol hydrochloric acid are uniformly mixed, and after hydrolysis and polycondensation process, a mixture of sol formed by dispersing red silylating agent and silicic acid condensation reaction is generated, which is spin-coated on the grounding conductive film 3 to form a polymer film, spin-coated Finally, under the protection of nitrogen, it is cured at a certain temperature of 80°C to 100°C for 30 minutes at a constant temperature, and then corona polarization is performed, and the electric field strength is about 150V/μm perpendicular to the grounding conductive film 3. At the same time, under the protection of nitrogen, the polarization The temperature is increased from 80°C to 100°C to 150°C to 170°C for constant temperature polarization for 3 hours, so that the silicic acid condensate is further polymerized into a three-dimensional network structure of silicon oxide compounds, and the electric dipole molecules of disperse red are formed during the polarization process The normal arrangement along the grounding conductive film 3 is fixed. At the end of the polarization curing process, the temperature should be lowered to room temperature first, and then the polarization voltage should be reduced to zero.

Claims (4)

1. An electro-optic detector capable of calibrating voltage is composed of an electro-optic detection unit, a detection point position monitoring unit and an integrated circuit test bench; the components of said integrated circuit test bench are a probe station (25), a probe ( 24) and integrated circuit test power supply (28); It is characterized in that, The component parts of said electro-optical detection unit are according to the order of optical path, the detection light beam sent by laser device (7) and laser (8) passes through collimator lens (9), beam expander (12) and detection light beam splitter ( 18) and the microscope objective lens (13), inject the electro-optic probe (14) and be focused on the metal microstrip of the transmission electric signal in the integrated circuit chip (19) to be tested, and the detection light is reflected back by the metal microstrip; The light is converted into intensity-modulated signal light during the round-trip process in the electro-optical probe (14), and then reflected to the photodetector ( 26), the electrical signal output by the photodetector (26) is input to the signal amplifier and storage display device (27); The component parts of said detection point position monitoring unit are according to the light path sequence, the spontaneous radiation light sent by the illumination light source (15) selects the appropriate wave band as the illumination light through the filter mirror (16), and passes through the illumination light beam splitter (17) ), the detection light beam splitter (18), the microscope objective lens (13) and the electro-optic probe (14), irradiate the device surface of the integrated circuit chip (19) under test and are reflected back, and the reflected illumination light reverses Pass through the electro-optic probe (14), microscope objective lens (13) and detection light beam splitter (18), meet together with part of the detection light transmitted through the detection light beam splitter (18), pass through the illumination light beam splitter (17) The image is formed on the CMOS camera head of the video camera (20), and the device pattern on the tested integrated circuit chip (19) and the position of the focused light spot of the detection light are displayed on the monitor (21). 2. The electro-optical detector capable of calibrating voltage according to claim 1, characterized in that said electro-optic probe consists of a transparent substrate (1), an anti-reflection film (2) plated on the upper surface of the transparent substrate (1), The ground conductive film (3) plated on the lower surface of the transparent substrate (1) and a layer of electro-optical medium layer (4) under the ground conductive film (3) are composed, and the polarization direction of the electro-optic medium layer (4) is electrically conductive to the ground. The normal direction of the film (3) is parallel; the grounded conductive film (3) has a reflectivity of 0.3 to 0.4 and a transmittance of 0.6 to 0.7 to the wavelength of the probe light; the electro-optical medium layer (4) is polarized polymerization Thin films with a thickness in the range of 0.2-2 μm. 3. The electro-optic detector according to claim 1 or 2, characterized in that, between the beam expander (12) and the photodetector (26), a λ/4 wave plate (11) and a polarization The beam splitter (10) fully reflects the detection light carrying the signal into the photodetector (26) under the coaxial optical path condition; or a beam expander (12) and the photodetector (26) are equipped with The wedge-shaped reflector (29) maintains an angle between the reflected detection light and the incident detection light, and reflects all the detection light carrying the signal into the photodetector (26) under the condition of non-coaxial optical path go. 4. A preparation process of the polarized polymer film according to claim 2, the material formula used is disperse red silylating agent in molar ratio: tetraethylorthosilicate: dimethylformamide: hydrochloric acid: pure water=1: 8～12:18～22:10:30～40; uniformly mix the materials, generate a uniform mixture of sol and disperse red formed by the condensation reaction of silicic acid through hydrolysis reaction, spin-coat on the grounding conductive film (3) to form a polymer After corona polarization and heat curing, the dispersed red electric dipole molecules form a stable arrangement along the direction of the polarized electric field; after spin-coating and forming a film, it is cured at a constant temperature of 80°C to 100°C for 30 minutes under the protection of nitrogen, and then Carry out corona polarization, apply an electric field of about 150V/μm perpendicular to the grounded conductive film (3), and at the same time increase the polarization temperature from 80°C to 100°C to 150°C to 170°C under the protection of nitrogen for 3 hours, so that The silicic acid condensate is further polymerized into a three-dimensional network structure of silicon oxide compound, which fixes the arrangement along the normal direction of the grounding conductive film (3) formed by the electric dipole molecules of the dispersed red during the polarization process.

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