CN218973412U - Non-invasive ultrathin metal film thickness gauge - Google Patents
Non-invasive ultrathin metal film thickness gauge Download PDFInfo
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- CN218973412U CN218973412U CN202222540700.2U CN202222540700U CN218973412U CN 218973412 U CN218973412 U CN 218973412U CN 202222540700 U CN202222540700 U CN 202222540700U CN 218973412 U CN218973412 U CN 218973412U
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- 229910052751 metal Inorganic materials 0.000 title claims abstract description 68
- 239000002184 metal Substances 0.000 title claims abstract description 68
- 239000000523 sample Substances 0.000 claims abstract description 58
- 238000012360 testing method Methods 0.000 claims description 11
- 230000035515 penetration Effects 0.000 claims description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 5
- 230000005284 excitation Effects 0.000 claims description 5
- 229910052710 silicon Inorganic materials 0.000 claims description 5
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- 239000000696 magnetic material Substances 0.000 claims description 4
- 238000001259 photo etching Methods 0.000 claims description 3
- 238000005259 measurement Methods 0.000 abstract description 20
- 230000001681 protective effect Effects 0.000 abstract description 5
- 238000000034 method Methods 0.000 description 12
- 238000001514 detection method Methods 0.000 description 7
- 229910052782 aluminium Inorganic materials 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
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- 238000006243 chemical reaction Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 238000000691 measurement method Methods 0.000 description 2
- 238000009659 non-destructive testing Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
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- 238000000354 decomposition reaction Methods 0.000 description 1
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- 230000001066 destructive effect Effects 0.000 description 1
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- 238000005566 electron beam evaporation Methods 0.000 description 1
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Abstract
The utility model relates to a non-invasive ultrathin metal film thickness gauge, which comprises a nondestructive probe and a complete machine, wherein the complete machine comprises a high-frequency oscillator, an alternating current amplifier, a measuring bridge, a wave detector, a direct current amplifier, a microprocessor, a display screen and a power supply; the input end of the nondestructive probe is connected with the whole machine to obtain high-frequency electromotive force, the high-frequency electromotive force is input to the two ends of a coil of the nondestructive probe, and a high-frequency magnetic field is generated in the coil; compared with the prior art, the utility model has the advantages of high measurement precision, intuitionistic and easy operation, and is not influenced by the surface of the metal film to be measured covered by the printing film or the non-conductive protective film (below 10 um).
Description
[ technical field ]
The utility model belongs to the technical field of precision instruments, and particularly relates to a non-invasive ultrathin metal film thickness gauge.
[ background Art ]
Currently, there are many methods for measuring thickness of metal film, such as: resistance, coulomb, radiation, ultrasound, etc., and different methods are used in different situations. However, these methods of measuring thickness are either not high in measurement accuracy or are affected by the surface coverage of the metal film to be measured with a printed film or a nonconductive protective film, even if some test instruments are destructive, and so on. It would be of great importance if an atraumatic ultra-thin metal film thickness gauge could be provided to solve the above-mentioned problems.
[ summary of the utility model ]
The utility model aims to solve the defects and provide the noninvasive ultrathin metal film thickness gauge which has high measurement accuracy, is visual and easy to operate, and is not influenced by a printed film or a non-conductive protective film covered on the surface of a metal film to be measured.
The non-invasive ultrathin metal film thickness gauge comprises a nondestructive probe and a whole machine, wherein the whole machine comprises a high-frequency oscillator, an alternating current amplifier, a measuring bridge, a wave detector, a direct current amplifier, a microprocessor, a display screen and a power supply, the output end of the high-frequency oscillator is connected with the input end of the alternating current amplifier, the output end of the alternating current amplifier is connected with the input end of the measuring bridge, the measuring bridge is connected with a measuring head, the output end of the measuring bridge is connected with the input end of the wave detector, the output end of the wave detector is connected with the input end of the direct current amplifier, the output end of the direct current amplifier is connected with the input end of the microprocessor, the output end of the microprocessor is connected with the display screen, the display screen is a touch screen control type display screen, and the high-frequency oscillator, the alternating current amplifier, the measuring bridge, the wave detector, the direct current amplifier, the microprocessor and the display screen are respectively connected with the power supply; the non-invasive probe is characterized in that the non-invasive probe is internally provided with an excitation coil carrying high-frequency signals, the input end of the non-invasive probe is connected with the whole machine to obtain high-frequency electromotive force, the high-frequency electromotive force is input to the two ends of the coil of the non-invasive probe, a high-frequency magnetic field is generated in the coil, and the center of the coil is a round magnetic material rod for increasing magnetic flux density.
Further, the nondestructive probe is vertically arranged on the surface of the detected metal film, an alternating high-frequency magnetic field generated by the nondestructive probe penetrates through the ultrathin metal film, an eddy current perpendicular to the magnetic field is generated in the metal film, and the strength of the eddy current and the thickness of the metal film are in a theoretical linear relation.
Further, the working frequency of the nondestructive probe excitation coil is 750KC or 375KC, the eddy current penetration depth is larger than that of the working frequency of 750KC when the working frequency is 375KC, and the working frequency of 375KC is used for measuring the thickness of a thicker metal film layer.
Further, a step sample is arranged on the test table surface, the metal surface of the step sample is clung to the test table surface, and the tested piece is arranged on the test table surface.
Further, the step sample is a high-resistance silicon wafer with polished surface, a layer of uniform metal film which is the same as the tested product is evaporated on the step sample, and a rectangular step pattern is formed by photoetching.
Compared with the prior art, the utility model adopts the eddy current measurement principle, the metal film layer obtained after evaporation is regarded as an infinite coil with a plurality of turns, and the exciting coil loaded with high-frequency signals in the measuring probe, according to Faraday electromagnetic induction law, eddy current is induced in the metal film layer, and the eddy current magnetic field in the metal film reacts with the exciting magnetic field to generate reflection resistance and reflection reactance, and then the reflection resistance and reflection reactance are amplified by an amplifier, and then are subjected to linearization treatment by a microprocessor, and finally are displayed by a display, so that the measuring precision is high and can be achieved
The level is provided with intelligent touch screen control, is visual and easy to operate, and can directly read the thickness of the metal film of the tested sample without conversion; in addition, the utility model is not affected by the surface of the metal film to be tested covered by a printing film or a non-conductive protective film (below 10 um) to the measurement, and no step of the sample to be tested is needed to be formed, thus the utility model is a nondestructive testing instrument; in addition, the utility model has short measurement response time, only in the second level, is widely used for conventional detection means in production sites, and is worthy of popularization and application.
[ description of the drawings ]
FIG. 1 is a circuit block diagram of the present utility model;
FIG. 2 is a graph of the characteristics of the present utility model between penetration depth um and high frequency electromotive force of 750 KC;
FIG. 3 is a schematic diagram of an impedance matching transformer according to the present utility model;
fig. 4 is a measurement circuit diagram of the present utility model.
Detailed description of the preferred embodiments
The utility model is further described below with reference to the accompanying drawings:
the utility model provides a non-invasive ultrathin metal film thickness gauge, which comprises a nondestructive probe and a complete machine, wherein the complete machine comprises a high-frequency oscillator, an alternating current amplifier, a measuring bridge, a wave detector, a direct current amplifier, a microprocessor, a display screen and a power supply, the output end of the high-frequency oscillator is connected with the input end of the alternating current amplifier, the output end of the alternating current amplifier is connected with the input end of the measuring bridge, the measuring bridge is connected with the measuring head, the output end of the measuring bridge is connected with the input end of the wave detector, the output end of the wave detector is connected with the input end of the direct current amplifier, the output end of the direct current amplifier is connected with the input end of the microprocessor, the output end of the microprocessor is connected with the display screen, the display screen is a touch screen control type display screen, and the high-frequency oscillator, the alternating current amplifier, the measuring bridge, the wave detector, the direct current amplifier, the microprocessor and the display screen are respectively connected with the power supply; the input end of the nondestructive probe is connected with the whole machine to obtain high-frequency electromotive force, the high-frequency electromotive force is input into the two ends of the coil of the nondestructive probe, a high-frequency magnetic field is generated in the coil, and the center of the coil is a circular magnetic material rod for increasing the magnetic flux density.
The measuring principle of the utility model is as follows: an aluminum film was evaporated on a nonmetallic substrate, and the thickness was measured by an eddy current method. The aluminum film is regarded as an infinite turn coil, eddy current is induced in the film by utilizing the electromagnetic induction principle, and the eddy current generates an eddy current magnetic field which in turn acts against the measurement excitation magnetic field to change the impedance of the measurement coil, and the impedance change is generated in proportion to a voltage signal through the thickness of the detection bridge.
As shown in fig. 4, a measurement circuit diagram of the present utility model is shown, and the measurement circuit principle is as follows: the high-frequency oscillator is used for selecting a proper working frequency through frequency division of the frequency divider, the high-frequency signal is amplified through the alternating current amplifier to meet the requirements of the detection bridge, the detection bridge generates a signal which is detected by the detector and then generates a direct current signal which is amplified through the direct current amplifier, and finally the direct current signal is processed by the microprocessor and then the measured thickness is displayed by the display screen.
The measurement circuit diagram may be specifically configured such that r1=2kΩ, r2=1kΩ, r3=10Ω, r4=10Ω, r5=10kΩ, r6=r7=100deg kΩ, r8=1kΩ resistor, r9=5.1 kΩ, r10=24kΩ, c1=39 pf, c2=c3=200 pf, c4=c5=c6=c7=0.1 μf, c8=510 pf, c9=1000+200 pf, c10=1 μf, c11 to c14=0.1 μf, c15=1 μf; x:6M crystal oscillator; DT1: MC54HC00; DT2: MC74HC4040; u1: BGF3005; u2:7650SCPDZ; d: IN4148X4; t is an impedance matching transformer; BK is a sensor; 1/2DT1, X and other circuits form a 6MC high-frequency oscillator; circuits such as 1/2DT1 and DT2 are frequency dividers, and circuits such as U1 are alternating current amplifiers; t, BK and other circuits form a detection bridge; d, detecting; the circuits such as U2 and the like form a direct current amplifier.
The input end of the nondestructive probe is connected with the whole machine to obtain high-frequency electromotive force v, the high-frequency electromotive force v is input to the two ends of a coil of the nondestructive probe, and the center of the coil is provided with a circular magnetic material rod for increasing magnetic flux density. The nondestructive probe is perpendicular to the metal film, generates an alternating high-frequency magnetic field, penetrates through the ultrathin metal film, generates eddy currents perpendicular to the magnetic field in the metal film, and the strength of the eddy currents and the thickness of the metal film form a theoretical linear relation; deriving v=κi, where v is faraday electromagnetic induction electromotive force; i is the intensity of the vortex; k is a proportionality coefficient and comprises the reflection impedance of the thickness of the metal film to be measured. By measuring the magnitude of the reflected impedance, the decomposition and evolution of the circuit system of the whole machine are realized in the minimum unit of thickness
(angstrom) is shown.
The thickness gauge is suitable for measuring the thickness of a metal film on the surface of an insulator, and the metal film can be formed by the technological means such as electron beam evaporation, magnetron sputtering and the like; is a non-damage measurement method. The input end of the nondestructive probe is connected with the whole machine to obtain high-frequency electromotive force v, the high-frequency electromotive force v is input to the two ends of a coil of the nondestructive probe, and a high-frequency magnetic field is generated in the coil. The nondestructive probe is vertically arranged on the surface of the metal film to be tested to generate an alternating high-frequency magnetic field, penetrates through the ultrathin metal film and generates eddy current vertical to the magnetic field in the metal film. The eddy current strength and the thickness of the metal film form a theoretical linear relation, v=kappa i is obtained through deduction, and v is Faraday electromagnetic induction electromotive force; i is the intensity of the vortex; k is a scaling factor. The two ends of the nondestructive probe can generate reflection impedance r, and the size of the reflection impedance depends on the thickness of the measured metal film.
The patent adopts the eddy current measurement principle, the metal film layer obtained after evaporation is regarded as an infinite turn coil, and the exciting coil loaded with high-frequency signals is arranged in the measuring probe. According to Faraday's law of electromagnetic induction, eddy currents are induced in the metal film layer. The eddy magnetic field in the metal film reacts with the exciting magnetic field to generate a reflecting resistance and a reflecting reactance, and the reflected magnetic field is amplified by an amplifier, is linearized by a microprocessor and is finally sent to a display for display, and the display is shown in the figure 1.
Further, the following description is made for specific implementations of the present utility model:
1. and (3) working frequency selection:
the higher the working frequency of the exciting coil is, the larger the eddy current skin effect is, and the higher the sensitivity of the thin metal film layer is. It is thus possible to effectively distinguish the minimum unit of the metal film thickness:
(angstrom),>
of course, the higher the working frequency is, the smaller the resonance capacitance value is, and the stability of the circuit is affected by the distributed capacitance of the micro circuit. The relation between the two is considered when the working frequency is selected. The presently available product JM301 and JM303 have a selection of 750KC. The working frequency of the JM302 patent product is 750KC and375 KC. (375 KC operating frequency vortex penetration depth is greater than 750KC, thus enabling measurement of thicker metal film layers).
The characteristic curve as shown in fig. 2 illustrates: (1)
The inner curve has large slope and linearity; JM301 span 100-1000A and JM 303->
It is what we need, effectively resolve up to +.>
(2) 750KC frequency, the eddy current penetration depth has tended to saturate to 0.2 μm, so JM302 must decrease the operating frequency to 375KC (375 KC increases the eddy current penetration depth) when measuring 2 μm to 5 μm.
2. Impedance matching transformer:
the ac signal output adopts a transformer coupling between the differential output and the detection circuit (as shown in fig. 3), and in order to achieve the maximum signal output, the output impedance of the transformer must be matched with the load.
Let the load impedance be rl=1150 Ω, take wl=rl (WL is inductance)
AL gets 63 too big loss is big
Then
The impedance transformer parameters are as follows:
the secondary side of the transformer is 62 circles, and the primary side of the transformer with the inductance value of 244 mu H is 1.8:1. i.e. 112 turns.
Al=63 (can be achieved by al=400 or al=100 material pad gaps)
3. Calculation of the sensor resonant tank (L.C):
q is the ratio of the inductance to the equivalent loss resistance when the inductor works under the alternating current voltage with a certain frequency, and the Q value is large, the loss is small and the efficiency is high.
Inductance L calculation: q=8r=15 was taken because wl=qr=8×15=120
Inductance (voltage transmitter) coil turns:
the coil of the sensor is internally provided with a short magnetic core so that AL takes 10
Then
Capacitance C calculation:
because of
Therefore->
This gives:
C＝1774×10 -12 f＝1774pf
the sensor resonant tank parameters are as follows:
l=25.4 μh50 turns (with core)
C=1774 pf (C value can be fine-tuned during actual debugging)
4. Film thickness calibration and measurement method:
it is important to measure thickness accurately to obtain a high-precision standard piece, i.e., a step sample. The standard film thickness was calibrated as follows: the standard step piece is precisely measured by an alpha step instrument, precise data of a film on the surface of the step piece are measured, and then the step sample piece is used as an accessory of the thickness gauge. When the thickness of the metal film on the surface of a measured piece is measured, firstly, a standard step piece of the metal film is placed on a special test table board of the thickness gauge, and the metal surface of the standard step piece is tightly attached to the test table board. And then correcting the thickness gauge to enable the thickness gauge to be in a working state to be measured. The measured piece can be placed on the test table top, and the thickness of the metal film on the surface of the measured piece can be measured in an atraumatic manner.
5. Manufacturing of step sample
The surface of the step sample wafer measured by the upper step instrument must reach certain flatness and smoothness, so that a high-resistance silicon wafer with polished surface is selected, then a layer of uniform metal film which is the same as the product to be measured is evaporated on the high-resistance silicon wafer, and a rectangular step pattern is formed by photoetching, wherein a white rectangular table top is the metal film, and the periphery is the surface of the silicon wafer. And finally, measuring the step sample by a step instrument to obtain a measurement report.
To verify the accuracy of the standard sample, we compared to the four-probe and resistance methods.
6. Compared with the four-probe method:
the square resistance of the step sample is measured by a four-probe tester
Then, the thickness of the aluminum film was measured to be 0.75 μm by using JM302 ultra-thin metal film thickness gauge manufactured by the design of this patent.
According to the formula
In the method, in the process of the utility model,
is a square resistance [ or a sheet resistance ]; ρ is the resistivity; x is X j Is the thickness of the film layer;
the resistivity of aluminum was found to be 3.93×10 from the manual -8 omega-CM. Substituting the above formula to obtain:
it follows that the two are completely equivalent.
In addition, another film thickness of the metal film is measured by JM301 type metal film thickness gauge
I.e. 0.077um.
Substitution into
Is calculated according to the calculation formula of (2):
thus, the JM301 type metal film thickness gauge has the same high accuracy as the JM302 type metal film thickness gauge.
7. The tester is compared with three different resistance methods:
the results of the same sample on three different instruments are shown in table 1 below, with greater error. The resistance method measurement is: 1. the measuring heads are stressed differently, and the measured results are different; 2. the sampling area is large and the size is accurate.
Table 1:
the accuracy of the measurement is achieved, which causes many difficulties for the user to measure rapidly and in batches. The patent has been improved for many years to achieve almost the same measured values on membranes of different sizes (see Table 2 below)
Table 2:
8. vortex edge effect:
when the measuring probe is placed near the edge of the sample to be measured, the eddy current generated on the probe is partially damaged, so that the emission signal is weakened, and the measured value is slightly smaller. Although the measurement error is caused by measuring the vicinity of the edge, the measurement error is still far smaller than the technical index (+ -) (20A+2%). Of course, the user is still required to be reminded of measuring without getting too close to the edge.
The noninvasive ultrathin metal film thickness gauge has the following advantages:
(1) Reference standard Hu Q/CB005-86.
(2) Thickness standards were identified by the national academy of metering science.
(3) The method does not need to form a step of a tested sample, and is a nondestructive testing instrument.
(4) The measuring response time is short, only in the order of seconds, and has been widely used for conventional detection means on production sites.
(5) The surface of the metal film to be tested is not covered by a printing film or a non-conductive protective film (below 10 um) to influence the measurement.
(6) High measuring precision, can reach
A stage.
(7) The metal film thickness of the measured sample is directly read out without conversion.
(8) According to the range requirement of different measured samples, the tester is divided into three different types, and the required types of the measured samples can be selected by oneself: [ measuring only the thickness of the evaporated aluminum film ]
(9) The intelligent touch screen control method is visual and easy to operate.
(10) The chassis has metallic texture and attractive appearance.
The present utility model is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principles of the utility model are intended to be equivalent substitutes and are included in the scope of the utility model.
Claims (5)
1. An atraumatic ultra-thin metal film thickness gauge, characterized in that: the device comprises a nondestructive probe and a complete machine, wherein the complete machine comprises a high-frequency oscillator, an alternating current amplifier, a measuring bridge, a detector, a direct current amplifier, a microprocessor, a display screen and a power supply, the output end of the high-frequency oscillator is connected with the input end of the alternating current amplifier, the output end of the alternating current amplifier is connected with the input end of the measuring bridge, the measuring bridge is connected with the measuring head, the output end of the measuring bridge is connected with the input end of the detector, the output end of the detector is connected with the input end of the direct current amplifier, the output end of the direct current amplifier is connected with the input end of the microprocessor, the output end of the microprocessor is connected with the display screen, the display screen is a touch screen control type display screen, and the high-frequency oscillator, the alternating current amplifier, the measuring bridge, the detector, the direct current amplifier, the microprocessor and the display screen are respectively connected with the power supply; the non-invasive probe is characterized in that the non-invasive probe is internally provided with an excitation coil carrying high-frequency signals, the input end of the non-invasive probe is connected with the whole machine to obtain high-frequency electromotive force, the high-frequency electromotive force is input to the two ends of the coil of the non-invasive probe, a high-frequency magnetic field is generated in the coil, and the center of the coil is a round magnetic material rod for increasing magnetic flux density.
2. The atraumatic ultra-thin metal film gauge of claim 1, wherein: the nondestructive probe is vertically arranged on the surface of the metal film to be detected, an alternating high-frequency magnetic field is generated by the nondestructive probe to penetrate through the ultrathin metal film, an eddy current perpendicular to the magnetic field is generated in the metal film, and the strength of the eddy current and the thickness of the metal film are in a theoretical linear relation.
3. The atraumatic ultra-thin metal film gauge of claim 1, wherein: the working frequency of the nondestructive probe excitation coil is 750KC or 375KC, the eddy current penetration depth is larger than that of the working frequency of 750KC when the working frequency is 375KC, and the working frequency of 375KC is used for measuring the thickness of a thicker metal film layer.
4. The atraumatic ultra-thin metal film gauge of claim 1, wherein: the test bench is characterized by further comprising a step sample, wherein the step sample is arranged on the test bench, the metal surface of the step sample is clung to the test bench, and the tested piece is arranged on the test bench.
5. The atraumatic ultra-thin metal film gauge of claim 4, wherein: the step sample is a high-resistance silicon wafer with polished surface, a layer of uniform metal film which is the same as the tested product is evaporated on the step sample, and a rectangular step pattern is formed by photoetching.
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| CN202222540700.2U CN218973412U (en) | 2022-09-26 | 2022-09-26 | Non-invasive ultrathin metal film thickness gauge |
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| CN202222540700.2U CN218973412U (en) | 2022-09-26 | 2022-09-26 | Non-invasive ultrathin metal film thickness gauge |
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