JP6008332B2 - Probe card and noise measuring device - Google Patents

Description

  The present invention relates to a probe card and a noise measuring device, and is particularly suitable for measuring noise of a MOS field effect transistor.

  With the miniaturization of MOS field effect transistors (hereinafter referred to as “MOSFETs”), fluctuations in characteristics become obvious and become a problem. The fluctuations can be divided into static characteristic fluctuations such as threshold voltage fluctuations and temporal (dynamic characteristic) fluctuations typified by noise. The characteristic of noise is generally evaluated as a frequency spectrum.

The noise characteristic of the low frequency band of the MOSFET is also called 1 / f noise or flicker noise, and shows a characteristic that decreases at 1 / f with respect to the frequency. Many papers have been reported on low frequency noise of 1 to 10 ³ Hz (for example, Non-Patent Documents 1 to 3).

  FIG. 6 shows the results of noise measurement using a commercially available device (Agilent, B1530A). 100 is the noise intensity of the measurement system when not connected to the MOSFET, and 101 is the noise intensity when connected to the MOSFET. From this figure, the noise of the MOSFET is larger than the noise of the measurement system in the region of 1 MHz or less, and the evaluation thereof is possible. It can be seen that measurement cannot be performed with. Even if other commercially available equipment is used, it is practical to measure noise characteristics up to several kHz.

  The current leading-edge SRAM is rewritten in 5 ns or less, and the speed corresponds to 200 MHz or more in the frequency band. SRAM write / read errors are a problem, but in order to verify the direct cause of the errors and the correlation with process conditions, MOSFET noise measurement is performed in the operating frequency band of SRAM, from 100 MHz to 1 GHz. It is necessary to carry out in the band.

K. K. Hung et al., IEEE TED 37 (1990) 654. F. N. Hooge IEEE TED41 (1994) 1926. E. Simoen et al., Solid-State Electronics 43 (1999) 865.

  However, the conventional noise measurement apparatus has a problem that noise measurement cannot be performed in the 100 MHz to 1 GHz band which is the operating frequency band of the SRAM.

  In view of the above-described problems, an object of the present invention is to provide a probe card and a noise measuring device that can measure noise in a high frequency band of several MHz or more.

  The present invention has a probe abutting on a MOS field effect transistor, and a probe card for measuring noise of the MOS field effect transistor is provided with an amplifier circuit for amplifying the output signal of the MOS field effect transistor. It is characterized by being.

  According to the present invention, the amplifier card is mounted on the probe card, and the distance between the MOS field effect transistor and the amplifier circuit is shortened. As a result, the present invention can suppress loss of signal transmission such as phase shift, so that noise can be measured in a high frequency band.

It is a block diagram which shows the whole structure of the noise measuring device which concerns on 1st Embodiment. It is a figure which shows the structure of the probe card which concerns on 1st Embodiment, FIG. 2A is a top view, FIG. 2B is AA fragmentary sectional view in FIG. 2A. It is a figure which shows the structure of the probe card which concerns on 1st Embodiment, and is a bottom view in the state which removed the cover. It is a circuit diagram which shows the structure of the probe card which concerns on 1st Embodiment. FIG. 5A is a graph showing a measurement result using the noise measurement apparatus according to the first embodiment. FIG. 5A shows a result of measuring the noise of the MOSFET. FIG. 5B shows a result of subtracting “Noise floor” from the measurement result of FIG. It is a graph which shows the result converted into noise intensity. It is a graph which shows the example of a measurement in a prior art. FIG. 7A is a perspective view and FIG. 7B is a bottom view of the probe card according to the second embodiment with a cover removed. It is a circuit diagram which shows the structure of the probe card which concerns on 2nd Embodiment. It is a graph which shows the measurement result using the noise measuring device concerning a 2nd embodiment.

2: Noise measuring device 6A: Probe card 14: DUT (MOS type field effect transistor)
32: First shield 34: Second shield 38: Probe for gate (probe)
40: Probe for drain (probe)
42: Probe for source (probe)
44: Probe for substrate (probe)
56: Amplifier circuit

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(1) First embodiment (overall configuration)
The noise measuring apparatus 2 shown in FIG. 1 measures a noise by receiving a stabilized power source 4, a probe card 6A electrically connected to the stabilized power source 4, and an output signal output from the probe card 6A. A measuring instrument 10. The probe card 6A is provided with a probe group 8 having a plurality of (four in this figure) probes. The probe group 8 includes a gate probe 38, a drain probe 40, a source probe 42, and a substrate probe 44. The probe group 8 comes into contact with the DUT 14 formed on the wafer 12 at the time of noise measurement. As a result, the probe card 6A electrically connects the DUT 14 and the measuring instrument 10. The DUT 14 is a MOSFET serving as a device under test.

  The noise measuring device 2 applies a DC voltage supplied from the stabilized power supply 4 to the DUT 14 through the probe group 8 and outputs an output signal output from the DUT 14 to the measuring instrument 10 via the probe group 8. The measuring device 10 measures the noise of the DUT 14.

  As shown in FIG. 2, the probe card 6A includes a probe group 8, a first substrate 16 and a second substrate 18A electrically connected to the probe group 8, a mounting portion 15, a first substrate 16 and a second substrate. The cable group 20 is electrically connected to the substrate 18A. The probe group 8 is held at one end of the probe card 6A by a holding portion 37, and the cable group 20 is drawn out from the insertion portion 17 formed on the other end side. The first substrate 16 and the second substrate 18A are stacked.

  The cable group 20 is composed of a plurality of cables, seven in the drawing (first to seventh cables 21 to 27), and one end is electrically connected to the first board 16 or the second board 18A. The other ends are each provided with a connector 30. The cable group 20 is preferably a coaxial cable. The surfaces of the first substrate 16 and the second substrate 18A are covered with a cover 36.

  As shown in FIG. 3, the second substrate 18 </ b> A is disposed between the one end where the probe group 8 is provided and the other end where the insertion portion 17 is provided, and at the approximate center of the first substrate 16. ing. A first cable 21 and a seventh cable 27 are arranged on both sides of the second board 18A. That is, the first cable 21 is arranged on one side of the second substrate 18A from the insertion portion 17 toward one end. The seventh cable 27 is arranged on the other side of the second substrate 18A from the insertion portion 17 toward one end.

  The second to sixth cables 22 to 26 are introduced from substantially the center of the insertion portion 17 and are arranged substantially parallel to each other. The second to fifth cables 22 to 25 are connected to the second substrate 18A. The sixth cable 26 is connected to the source probe 42 by wiring not shown.

  In the probe card 6 </ b> A, a first shield 32 is provided on the outer edge of the first substrate 16, and the first substrate 16 and the second substrate 18 </ b> A are accommodated in the first shield 32. Further, a second shield 34 is provided on the outer edge of the second substrate 18 </ b> A, and the second substrate 18 </ b> A is accommodated in the second shield 34. Thus, the second substrate 18A is accommodated in the space shielded by the first shield 32 and the second shield 34.

  As shown in FIG. 4, the DUT 14 includes a gate pad 46, a drain pad 48, a source pad 50, and a substrate pad 52 that are electrically connected to the gate, drain, source, and substrate, respectively. The gate pad 46 may be in contact with the gate probe 38, the drain pad 48 may be in contact with the drain probe 40, the source pad 50 may be in contact with the source probe 42, and the substrate pad 52 may be in contact with the substrate probe 44. The gate probe 38 is connected to the first cable 21 through a first filter circuit 58 provided on the first substrate 16. The drain probe 40 is connected to an amplifier circuit 56A provided on the second substrate 18A. A characteristic configuration of the present embodiment is that a probe board 6A is provided with a second substrate 18A having an amplifier circuit to be described later.

  The amplifier circuit 56 </ b> A includes an amplifier 57, a pair of capacitors 59 and 61, and a feedback resistor 62. Capacitors 59 and 61 are provided in series on the input side and output side of the amplifier 57. The feedback resistor 62 is provided in parallel with the amplifier 57. In the amplifier 57, the drain probe 40 is connected to the input, and the fourth cable 24 is connected to the output. The fifth cable 25 is connected to the power supply terminal of the amplifier 57. Further, a bias circuit 54 is connected to the input of the amplifier 57. The bias circuit 54 is connected to the second and third cables 22 and 23. In the present embodiment, the feedback resistor 62 provided in the amplifier circuit 56A and the pull-up resistor (not shown) provided in the bias circuit 54 have different values.

  The source probe 42 is grounded via the sixth cable 26. The substrate probe 44 is connected to the seventh cable 27 through a second filter circuit 60 provided on the first substrate 16. The fourth cable 24 is connected to the measuring instrument 10 via the connector 30 and the coaxial cable. The first, second, sixth, and seventh cables 21, 22, 26, and 27 are connected to the stabilized power supply 4 via a connector 30 and a coaxial cable (not shown). The third cable 23 is connected to a voltmeter (not shown), and measures the net voltage value applied to the drain excluding the voltage related to the pull-up resistor. The fifth cable 25 is connected to a stabilized power source (not shown) for driving the amplifier 57.

(Function and effect)
In the above configuration, the noise measuring device 2 first brings the probe group 8 into contact with the pads 46, 48, 50, 52. That is, the gate probe 38 is brought into contact with the gate pad 46, the drain probe 40 is brought into contact with the drain pad 48, the source probe 42 is brought into contact with the source pad 50, and the substrate probe 44 is brought into contact with the substrate pad 52. When the probe is brought into contact with the pad, the position is confirmed using a microscope (not shown).

  Next, a voltage supplied from the stabilized power supply 4 is applied to the gate and drain of the DUT 14 through the gate probe 38 and the drain pad 48. Thereby, DUT14 will be in the conduction | electrical_connection state according to a threshold voltage. As a result, a current flows between the source and the drain of the DUT 14. This current amount fluctuates. The current that causes the fluctuation is converted into a voltage, and the output signal obtained by amplifying only the high frequency component by the amplifier circuit 56A is measured by the measuring instrument 10 as noise.

  In the noise measuring apparatus 2 according to the present embodiment, the amplifier circuit 56A is mounted on the probe card 6A, and the distance between the drain pad 48 of the DUT 14 and the amplifier 57 is shortened. Thereby, since the noise measuring apparatus 2 can suppress loss of signal transmission such as a phase shift, noise can be measured in a high frequency band.

  Incidentally, in the conventional noise measuring device, the distance from the MOSFET to the signal amplifier / detector is as long as 15 cm to 60 cm, so that a phase shift or the like occurs.

FIG. 5 shows the results of MOSFET noise measurement using the probe card 6A configured as described above. The probe card 6A was formed so that the distance from the drain pad 48 to the amplifier 57 was about 10 mm. As the MOSFET, an n-MOSFET having a gate length (L) / width (W) of 1 / 2.5 μm was used. The thickness of the gate SiO ₂ film is 3 nm. The voltage applied to the gate is 1.0 (71 in the figure), 0.8 (72 in the figure), 0.6 (73 in the figure), 0.4 (74 in the figure) with respect to the threshold voltage. ), 0.2 (75 in the figure) V. The measurement results are shown in FIG. Also, “Noise floor” in FIG. A is a result of measuring noise when the probe group 8 is connected to the DUT 14 that is not energized. Further, FIG. B shows a result obtained by subtracting “Noise floor” from the measurement result of FIG. From this figure, since the noise floor and noise intensity of the measurement system do not overlap, it was confirmed that noise at a high frequency of 40 MHz can be normally obtained by using the probe card 6A according to this embodiment. In the probe card 6A according to the present embodiment, it is considered that the noise characteristics of MOSFETs up to several hundred MHz can be measured by improving the performance of the amplifier or improving the mounting form.

(2) Second Embodiment Next, a probe card according to a second embodiment will be described with reference to FIGS. In addition, about the structure similar to the said 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted. The probe card 6B shown in FIG. 7 differs from the first embodiment in the configuration of the second substrate 18B.

  As shown in FIG. 8, the second substrate 18B includes an amplifier circuit 56B. The amplifier circuit 56B includes an amplifier 57, a pair of capacitors 59 and 61, and a feedback resistor 62. In the present embodiment, the amplifier circuit 56B is configured by a single IC (Integrated Circuit), and four transistors are arranged. Thus, by making the amplifier circuit 56B into an IC, the probe card 6B can measure higher frequency noise characteristics.

  FIG. 9 shows the result of noise measurement of the DUT 14 using the probe card 6B according to this embodiment. The amplifier circuit 56B was manufactured using an IBM 0.13 μm, 8HP SiGe BiCMOS Process.

The DUT 14 was a MOSFET formed on a 12-inch wafer having a gate length (L) of 85 nm. The probe group 8 was connected to the MOSFET and noise was measured. The thickness of the gate SiO ₂ film is 3 nm. The voltage applied to the gate was measured with respect to the threshold voltage at three types of 0.2 (81 in the figure), 0.4 (82 in the figure), and 0.6 (83 in the figure) V. “Noise floor” in this figure is the result of measuring noise when the probe group 8 is connected to the DUT 14 that is not energized. From this figure, it was confirmed that noise at a higher frequency of 800 MHz can be normally obtained by using the probe card 6B according to the present embodiment.
The probe card 6B according to the present embodiment uses, for example, a spectrum analyzer instead of an oscilloscope to monitor current in an ultra-high-speed time domain, or to use an SRAM (Static Random Access Memory) cell, a memory device (RRAM (registered)). (Trademark) (Resistive Random Access Memory: Filament formation) and NAND flash memory transfer, as well as monitoring various phenomena such as switching of super-high-speed monitoring for reliability testing Can do.

(3) Modifications The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the gist of the present invention. In the above embodiment, the case where noise is measured by converting the fluctuation of the drain current into voltage has been described, but the present invention is not limited to this, and noise may be measured directly from the current without being converted into voltage, It is good also as measuring by both a voltage and an electric current.

Claims (6)

In a probe card having a probe abutting on a MOS field effect transistor and measuring noise of the MOS field effect transistor,
A first substrate provided with a filter circuit;
A second substrate provided on the first substrate and provided with an amplifier circuit for amplifying an output signal of the MOS field effect transistor;
The first substrate and the second substrate are provided in a first shield provided on an outer edge of the first substrate;
The second substrate is provided in a second shield provided at an outer edge of the second substrate;
The probe card, wherein the second substrate is accommodated in the first shield and the second shield. A cable group electrically connected to the first substrate and the second substrate;
The probe card according to claim 1, wherein the probe is held at one end by a holding portion, and the cable group is drawn out from an insertion portion formed on the other end side. 2. The probe card according to claim 1, wherein the amplifier circuit is an IC. In a noise measuring device having a probe that abuts on a MOS field effect transistor and having a probe card for measuring noise of the MOS field effect transistor,
The probe card is
A first substrate provided with a filter circuit;
A second substrate provided on the first substrate and provided with an amplifier circuit for amplifying an output signal of the MOS field effect transistor;
The first substrate and the second substrate are provided in a first shield provided on an outer edge of the first substrate;
The second substrate is provided in a second shield provided at an outer edge of the second substrate;
The noise measurement apparatus, wherein the second substrate is accommodated in the first shield and the second shield. A cable group electrically connected to the first substrate and the second substrate;
5. The noise measurement according to claim 4, wherein the probe card is held at one end by a holding portion, and the cable group is drawn out from an insertion portion formed on the other end side. apparatus. 5. The noise measuring apparatus according to claim 4, wherein the amplifier circuit is an IC.

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