JP2008002952A - Scanning probe microscope, sample for scanning probe microscope and its forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To heighten sensitivity of detection capability in SSRM, and to heighten space resolution thereof. <P>SOLUTION: A scanning probe microscope used for SSRM measurement includes the first amplifier 17 for amplifying a signal from a probe 12, and outputting an amplified signal; the first logarithmic amplifier 18 for converting the amplified signal output from the first amplifier 17 into a logarithmic signal; the second logarithmic amplifier 19 for converting the signal from the probe 12 into a logarithmic signal; a switching circuit 16 for switching connection to the probe 12 between the first amplifier 17 and the second logarithmic amplifier 19 corresponding to the magnitude of a signal value from the probe 12; and a means 110 for acquiring a spreading resistance from logarithmic signals from the first logarithmic amplifier 18 and/or the second logarithmic amplifier 19. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a scanning probe microscope, a sample for a scanning probe microscope, and a method for forming the same.

  In recent years, with the miniaturization of devices, it has become necessary to evaluate the impurity concentration in the submicron and nanometer regions. The scanning spread resistance evaluation technique using a scanning probe microscope was developed in response to the needs, and an apparatus for evaluating this technique is a so-called SSRM (Scanning Spreading Resistance Microscopy) apparatus (for example, patent document) 1).

  SSRM uses a current log amplifier and has a wide impurity concentration range in semiconductor materials and devices, and is expected as a technology that can evaluate such a wide concentration distribution at a time.

  This device is based on the principle of Conductive Atomic Force Microscopy, which is a type of Scanning Probe Microscopy. The probe is scanned along the cross-section to be tested while a voltage is applied between the surface, and a surface three-dimensional uneven image, a three-dimensional uneven image expressed by detecting a current flowing through the probe, and a two-dimensional spread current distribution are obtained. Can be acquired simultaneously.

  When measuring the spreading resistance, scanning is performed with the contact pressure of the probe to the sample increased (the load force is set larger). A local current distribution on the sample surface is measured by measuring a minute current on the sample surface at the probe contact position by the bias voltage applied to the sample. Since the resistance value inside the sample directly under the probe may be close to an insulator depending on the configuration of the sample, a logarithmic amplifier having a wide range of amplification factors is required for the current detection amplifier. Since the detected spreading current value can be converted into a spreading resistance value, a two-dimensional spreading resistance distribution can be obtained, and a two-dimensional impurity concentration distribution can be derived from the spreading resistance distribution, and carrier density distribution evaluation in a semiconductor device, etc. Has been used.

  However, there is a demand for higher detection capability in the conventional SSRM. It depends on the following factors.

  That is, (1) The SSRM used in the past has a current measurement range of 7 digits from 10 pA to 0.1 mA, and the current detection sensitivity in the minute current region (high resistance region) is insufficient. For example, when examining the two-dimensional carrier concentration distribution in the cross section of a fine MOS transistor device, the gate electrode and source / drain regions have high carrier concentrations, so a clear SSRM image can be obtained, while the source / drain extended regions. (Extension) and the HALO region provided to suppress the short channel effect has a small current region with a low carrier concentration, and the current detection sensitivity of the conventional SSRM device does not provide a clear contrast, and the cross section To obtain impurity concentration distribution data, it is necessary to increase the sensitivity of detection.

  (2) In SSRM, a conductive probe with a tip radius of about 100 nm directly contacts the sample to detect current. Therefore, if there is a region with high conductivity near the test location, the current signal in that region is detected. Is detected by mixing with the signal at the test location, or due to the long distance from the contact provided on the sample for voltage application to the test cross-section of the sample, There was a problem that the current path was not determined, and the current at the test location was affected by the surrounding high conductivity region, and the spatial resolution of the measurement was low. The spatial resolution of SSRM was set to several tens of nanometers, which was insufficient for evaluating a device of 100 nm node or less.

(3) If the difference in impurity concentration between the test site and its surroundings is small, for example, a two-dimensional impurity in a HALO region having a higher impurity concentration than the well or the substrate, which is formed so as to surround the extension part of the MOS transistor, for example. When measuring the distribution, etc., the HALO region is the same conductivity type as the substrate, so there is no steep impurity concentration difference from the substrate, and the two-dimensional carrier concentration distribution in the HALO region at the boundary between the HALO and the substrate should be detected with high accuracy. It was difficult.
JP 2000-154810 A

  It is an object of the present invention to provide a probe microscope capable of achieving high sensitivity and high spatial resolution in detecting spread resistance in a conventional SSRM.

A first aspect of the present invention is a probe having conductivity and in contact with a sample;
Bias voltage applying means for applying a bias voltage to the sample;
A first amplifier that amplifies a signal from the probe generated when a bias voltage is applied to the sample and outputs an amplified signal, and the minimum value of the signal detection width is a1 and the maximum value is b1;
A first log amplifier connected to the first amplifier for converting the amplified signal output from the first amplifier into a log signal;
A signal from the probe generated when a bias voltage is applied to the sample is converted into a log signal, and the minimum value of the signal detection width is A2, the maximum value is B2, and a1 <A2 and b1 <B2 A second log amp that satisfies the relationship;
A switching circuit that switches the connection between the probe and the first amplifier and the second log amplifier according to the magnitude of the signal value from the probe;
A scanning probe microscope comprising means for obtaining spreading resistance from a log signal from the first log amplifier and / or the second log amplifier.

The second of the present invention is a conductive probe that contacts the sample;
Bias voltage applying means for applying a bias voltage to the sample;
A first amplifier that detects and amplifies a signal generated when a bias voltage is applied to the sample, outputs the amplified signal, and has a minimum signal detection width of a1 and a maximum value of b1; ,
A signal from the probe generated when a bias voltage is applied to the sample is detected and converted to a log signal, and the minimum value of the signal detection width is A2, the maximum value is B2, and a1 <A2 and b1 <Second log amplifier satisfying the relationship of B2;
A switching circuit that switches the connection between the probe and the first amplifier and the second log amplifier according to the magnitude of the signal value from the probe;
A scanning probe microscope comprising: means for obtaining spreading resistance from a signal from the first amplifier and / or a log signal from the second log amplifier.

According to a third aspect of the present invention, there is provided a sample body having a measurement surface for measurement by a scanning probe microscope, wherein the first conductive region and the second conductive region that is the measurement target are exposed on the measurement surface;
A first electrode formed on the sample body for applying a bias voltage to the surface to be measured;
A sample for a scanning probe microscope, comprising: a second electrode formed on the sample body and in contact with the second conductive region and the first electrode.

According to a fourth aspect of the present invention, a surface to be measured from which the first conductive region and the second conductive region are exposed is formed in a sample body having a first conductive region and a second conductive region to be measured. Process,
Etching the sample body to form a trench penetrating to the outside from the second conductive region;
Depositing a conductive material in the trench and forming a second electrode in contact with the second conductive region;
Forming a first electrode for applying a bias voltage to the surface to be measured on the sample body so as to be electrically connected to the second electrode. A method for forming a sample for a scanning probe microscope as described in 1. above.

According to a fifth aspect of the present invention, there is provided a measurement surface for measurement by a scanning probe microscope, and the first conductivity type first semiconductor region that is the test object and the first semiconductor region on the measurement surface A sample body that is exposed around a region to be measured and is exposed to a second semiconductor region that is a second conductivity type different from the first conductivity type and that forms a pn junction with the first semiconductor region When,
A sample for a scanning probe microscope, comprising: a first electrode formed on the sample body and for applying a bias voltage to the surface to be measured.

  According to the present invention, high sensitivity and high spatial resolution of detection capability in SSRM can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
In the first embodiment, the sensitivity of SSRM (Scanning Spreading Resistance Microscopy) measurement is improved by improving the apparatus configuration of a scanning probe microscope (hereinafter referred to as SPM).

  A schematic diagram of an SPM capable of measuring the spreading resistance according to the first embodiment of the present invention is shown in FIG.

  A bias voltage is applied from a power source 15 to the semiconductor device cross-sectional sample 13 on the sample stage 14 installed in the vacuum chamber 11. A conductive cantilever probe (probe) 12 installed in the vacuum chamber 11 is in contact with the sample 13 and detects the current at the location where the probe 12 is in contact mode. A detection signal (current signal in this embodiment) from the probe 12 generated when a bias voltage is applied to the sample 13 is sent to a data detection circuit connected to the probe 12.

  The data detection circuit mainly has two paths through the switching circuit 16. The minute current path includes a minute current-voltage amplifier (first amplifier) 17 connected to the switching circuit 16 and a minute voltage log amplifier (first log amplifier) 18 connected to the minute current-voltage amplifier (first amplifier) 17. Is provided. In the large current path, a current-voltage log amplifier (second log amplifier) 19 connected to the switching circuit 16 is provided.

  The switching circuit 16 detects, for example, a detection signal of a minute current of 20 pA or less in a minute current path, for example, a detection of a large current exceeding 20 pA, depending on the magnitude relationship between the magnitude of the detection signal and a predetermined current value that is a preset reference. The signal is switched to send the detection signal to a large current path.

  First, the switching circuit 16 switches to a large current path and is connected to a current-voltage log amplifier 19. This voltage output is sent to the controller 110, the output voltage is converted into a current value by the controller 110, and the switching method is fed back to the switching circuit 16 via the feedback path 111 depending on the magnitude of the signal. For example, when the current value exceeds 20 pA, the controller 110 directly calculates the spread resistance value from the signal. On the other hand, when the current value is 20 pA or less, for example, a signal for switching to the minute current detection path is sent to the switching circuit 16, and an output signal is sent to the controller 110 via the minute current-voltage amplifier 17 and the minute voltage log amplifier 18.

A signal sent to the minute current path or the large current path is converted into a log signal by a circuit on each path and sent to the controller 110, and the controller 110 calculates the value of the spreading resistance. The controller 110 has a voltage-current conversion function and a function for converting a resistance from an output current and an applied bias.
In the minute current path, a minute current signal of, for example, 20 pA or less from the switching circuit 16 is first converted into a voltage signal by the minute current-voltage amplifier 17, and the voltage signal is further converted into a log signal using the minute voltage log amplifier 18. And output to the controller 110 as a voltage. The current measurement range (signal detection width) of the minute current-voltage amplifier 17 is typically a three-digit range where the minimum value is 0.1 pA and the maximum value is 100 pA, for example. Can be detected by using a high-performance microcurrent amplifier.

  In the large current path, a current-voltage log amplifier (second log amplifier) 19 connected to the switching circuit 16 is provided. In the large current path, a current signal exceeding, for example, 20 pA from the switching circuit 16 is converted into a log signal and output to the controller 110 as a voltage signal. The current measurement range (signal detection width) of the current-voltage log amplifier 19 is typically a 7-digit range, for example, a minimum value of 10 pA and a maximum value of 0.1 MA. The range can be further expanded by using.

  When the ranges of the two amplifiers, the minute current amplifier 17 and the current log amplifier 19, are combined, nine digits can be measured. For example, the measurement range of the minute current amplifier 17 is one digit at a minimum value of 1 pA and a maximum value of 20 pA. Even if it exists, a measurement range will increase by one digit compared with the case where the current-voltage log amplifier 19 is provided independently.

    Then, the probe 12 scans in a two-dimensional direction along the measurement surface of the cross-sectional sample 13, and calculates a two-dimensional spread resistance distribution.

  In this embodiment, the minimum current-voltage amplifier (first amplifier) 17 and the minimum value of the signal detection range are a1, the maximum value is b1, and the signal detection range of the current-voltage log amplifier (second log amplifier) 19 is When the minimum value is A2 and the maximum value is B2, the relations of a1 <A2 and b1 <B2 are satisfied. In the minute current path, an amplifier suitable for minute current amplification is used, and in the large current path, a large current is obtained. A log amp suitable for amplification is used.

  In this way, by using a small current-voltage amplifier and a small voltage log amplifier together with a conventional current-voltage log amplifier, and switching and using a switching circuit, the spread current measurement can be measured in a range with more digits than the conventional one. It becomes like this. Therefore, the spreading resistance can be measured with high sensitivity in a high range including the high resistance region.

  In addition, there is a demand for using SSRM for gate insulating film degradation and device breakdown process evaluation. This is because in the process of deterioration of the gate insulating film, the leakage current may change by several orders of magnitude until breakdown, and it is difficult to follow with a normal linear current amplifier. Therefore, it is possible to observe the progress of destruction by using the log amplifier module of SSRM. For this purpose, the contact pressure between the probe and the sample is reduced to perform SSRM measurement without destroying the sample, measurement of a high resistance region (that is, a region where the detection current is small) such as a gate insulating film, and low resistance. It is necessary to satisfy the condition of performing high-sensitivity, high-range measurement that enables both areas (that is, areas where detection current is large). Therefore, if this embodiment is used, high-sensitivity measurement is possible, so measurement is possible even when the contact pressure of the probe is low (for example, <500 nN), that is, nondestructive measurement is possible, and low current region In the current measurement, the current and voltage breakdown amplifiers are used to evaluate the insulation degradation in the large current region and the current measurement of the device breakdown process using the current-voltage log amp. Both can be evaluated. Therefore, the apparatus of this embodiment can be used when it is necessary to non-destructively evaluate a sample in which a high resistance region and a low resistance region are mixed, such as deterioration of a gate insulating film or device breakdown process evaluation.

(Second Embodiment)
In the second embodiment, the sensitivity of SSRM measurement is increased by improving the SPM device configuration.

  The second embodiment is an example in which the minute voltage log amplifier 18 is not used in the first embodiment.

  FIG. 2 shows a schematic diagram of an SPM capable of measuring the spreading resistance according to the second embodiment of the present invention.

  A bias voltage is applied from a power source 25 to the semiconductor device cross-sectional sample 23 on the sample stage 24 installed in the vacuum chamber 21. A conductive cantilever probe (probe) 22 installed in the vacuum chamber 21 is in contact with the sample 23 and detects a current at a location where the probe 22 is in contact mode. A detection signal (current signal in this embodiment) generated from the probe 22 when a bias voltage is applied to the sample 23 is sent to a data detection circuit connected to the probe 22.

  In the data detection circuit, there are mainly two paths through the switching circuit 26. In the minute current path, a minute current-voltage amplifier (first amplifier) 27 connected to the switching circuit 26 is provided. A current-voltage log amplifier 28 is provided in the large current path.

  The switching circuit 26 uses, for example, a small current of 20 pA or less as a minute current path and a large current area exceeding 20 pA as a large current path depending on the magnitude relationship between the magnitude of the detection signal and a predetermined reference current value as a reference. Switch to send the signal.

  First, the switching circuit 26 switches to a large current path and is connected to a current-voltage log amplifier 28. This voltage output is sent to the controller 29, the output voltage is converted into a current value by the controller 29, and the switching method is fed back to the switching circuit 26 via the feedback path 111 depending on the magnitude of the signal. For example, when the current value exceeds 20 pA, the controller 29 calculates the spread resistance value from the signal. On the other hand, for example, when the current value is 20 pA or less, a signal for switching to the minute current detection path is sent to the switching circuit 26, and an output signal is sent to the controller 110 via the minute voltage-current amplifier 27.

  A signal sent to the minute current path or the large current path is converted by a circuit on each path and sent to the controller 29, and the controller 29 calculates the value of the spreading resistance.

  The probe 22 scans in a two-dimensional direction along the measurement surface of the sample 23, and calculates a two-dimensional spread resistance distribution.

  In the minute current path, a minute current-voltage amplifier (first amplifier) 27 connected to the switching circuit 26 is provided. In the minute current path, a minute current signal of 20 pA or less from the switching circuit 26 is converted into a voltage signal and output to the controller 29 as a voltage signal. In the controller 29, the voltage signal is converted into a current signal by software, and the spreading resistance is converted from the bias voltage and output in a log scale.

  The current measurement range (signal detection width) of the minute current-voltage amplifier 27 is typically three digits, for example, a minimum value of 0.1 pA and a maximum value of 100 pA. It is also possible to use a high-performance minute current-voltage amplifier.

  In the large current path, a current-voltage log amplifier 28 (second log amplifier) 28 connected to the switching circuit 26 is provided. In the large current path, a current signal of 20 pA or more from the switching circuit 26 is converted into a log signal and output to the controller 29 as a voltage signal. The current measurement range (signal detection width) of the current log amplifier 28 is typically and preferably a 7-digit range, for example, a minimum value of 10 pA and a maximum value of 0.1 MA. By using it, it is possible to further expand the range.

  When the ranges of the two amplifiers, the minute current amplifier 27 and the current log amplifier 28, are combined, it becomes possible to measure 9 digits, but the measurement range of the minute current amplifier 27 is one digit at the maximum value 20pA and the minimum value 1pA. However, the measurement range is increased by one digit as compared with the case where the current log amplifier 28 is provided alone.

  In this embodiment, the minimum current-voltage amplifier (first amplifier) 27, the minimum value of the signal detection range is a1, the maximum value is b1, and the signal detection range of the current-voltage log amplifier (second log amplifier) 28 is When the minimum value is A2 and the maximum value is B2, the relations of a1 <A2 and b1 <B2 are satisfied. In the minute current path, an amplifier suitable for minute current amplification is used, and in the large current path, a large current is obtained. A log amp suitable for amplification is used.

  As described above, by using the minute current-voltage amplifier together with the conventional current-voltage log amplifier and switching the switching circuit to use it, the spread current measurement can be performed in a range having more digits than the conventional one. Therefore, the spreading resistance can be measured with high sensitivity in a high range including the high resistance region.

  In addition, there is a demand for using SSRM for gate insulating film degradation and device breakdown process evaluation. For this purpose, the contact pressure between the probe and the sample is reduced to perform SSRM measurement without destroying the sample, measurement of a high resistance region (that is, a region where the detection current is small) such as a gate insulating film, and low resistance. It is necessary to satisfy the condition of performing high-sensitivity, high-range measurement that enables both areas (that is, areas where detection current is large). Therefore, if this embodiment is used, it is possible to measure a high resistance region, so that even if the contact pressure of the probe is low (for example, <500 nN), measurement is possible, that is, nondestructive measurement is possible, and low current In the region, a small current-voltage amplifier is used, and the insulation degradation in the large current region and the current measurement of the device breakdown process are evaluated using the current-voltage log amplifier, so that the low current region and the large current region in the insulation and high resistance regions are evaluated. Both can be evaluated. Therefore, the apparatus of this embodiment can be used when it is necessary to non-destructively evaluate a sample in which a high resistance region and a low resistance region are mixed, such as deterioration of a gate insulating film or device breakdown process evaluation.

(Third embodiment)
In the third embodiment, the sensitivity of SSRM measurement is increased by improving the structure of the SPM sample.

  FIG. 3 is a perspective view showing a method for forming an SPM sample having a MOS transistor cross-sectional structure according to this embodiment. The sample according to the present embodiment is a sample for obtaining the spreading resistance of the drain region of the MOS transistor cross-sectional structure and the two-dimensional impurity distribution in the drain region by SSRM measurement.

First, as shown in FIG. 3A, the configuration of the Si semiconductor MOS transistor device as a sample covers the SiO ₂ gate insulating film 34 on the silicon substrate 31, the poly Si gate electrode 35 thereon, and the gate electrode 35. An interlayer insulating film 36 is provided, and a source region 32 and a drain region 33 are formed on the silicon substrate 31 through a channel region below the gate insulating film 34.

  Next, the MOS transistor was cut by mechanical cutting to cut out a cross section. Next, in order to enable SPM measurement, the sample cross section is flattened by means such as polishing so that the roughness (RMS) is several nanometers or less.

  Conventionally, an SSRM measurement was performed by providing an electrode for applying a bias voltage to the sample in this state. However, in that case, in the SSRM measurement, since a conductive probe having a tip radius of about 100 nm directly contacts the sample to detect current, high conductivity is provided in the vicinity of the drain region 33 (second conductive region) to be measured. Since the gate electrode 35 (first conductive region) is present, the current signal from the drain region 33 is mixed with the current signal from the drain region 33 and detected, or the sample is detected from the bias voltage application electrode. Due to the long distance to the cross section, the current path from the drain region 33 to the electrode for applying the bias voltage is not determined, and the current value from the drain region 33 is affected by the gate electrode region 35 and the spatial value is high. This causes the problem that measurement cannot be performed with

  Next, as shown in FIG. 3B, a trench 37 of several micrometers reaching the drain region 33 was dug in the sample by etching means such as a focused ion beam (FIB).

  Next, as shown in FIG. 3C, a conductive material such as W is deposited therein by FIB processing to form a contact electrode (second electrode) 38, and W (on the surface of the interlayer insulating film 36 of the sample). A bias voltage application electrode (first electrode) 39 made of tungsten) is formed by forming an electrode such as Pt by electron beam evaporation, and a drain region 33, a second electrode 38, and a first electrode 39 are formed. Make electrical contact with each other.

  The SSRM measurement is performed using the sample obtained as described above.

  As in the present embodiment, the contact electrode 38 (second electrode) is provided in the drain region 33 (second conductive region) to be measured, and when the bias voltage is applied in the SSRM measurement, the bias voltage is applied to the second conductive region and the sample. By applying the same potential to the electrode 310 (first electrode) for applying electric current, detection of an electric signal (noise) from the conductive region around the specific location is suppressed, and the two-dimensional distribution of the spreading resistance at the specific location is increased. It can be measured with spatial resolution.

  In this embodiment, W is used for the first electrode and the second electrode, but other metal materials such as Pt may be used as long as the metal can be processed by FIB. Further, a processing means other than FIB may be used as long as the conductive contact can be selectively made from the second conductive region to be measured. In this embodiment, the drain region 33 is an object to be measured, and a contact electrode in contact with the drain region 33 is provided. However, the other source region 32, the gate electrode 35, and other conductive regions are to be measured. It is also good. In this embodiment, a MOS device is taken as an example, but it can also be applied to cross-sectional samples of other electrical devices, organic material devices, or biodevices.

(Fourth embodiment)
In the fourth embodiment, the sensitivity of the SSRM measurement is increased by improving the structure of the SPM sample.

  FIG. 4 is a perspective view showing a method for forming an SPM sample having a MOS transistor cross-sectional structure according to this embodiment. This sample is a sample for observing the interface of the p + type HALO region formed in the drain region.

First, as shown in FIG. 4A, an n-type conductivity type silicon layer 42 and a p-type conductivity type silicon layer 41 are laminated on a silicon substrate 40, respectively. A SiO ₂ gate insulating film 43 and a NiSi gate electrode 44 are provided thereon.
Next, as shown in FIG. 4B, ap ⁺ type HALO region 45 is formed by oblique ion implantation.

Next, as shown in FIG. 4C, an n ⁺⁺ source extension layer 46 and an n ⁺⁺ drain extension layer 47 are formed by ion implantation.

  Next, as shown in FIG. 4D, the side wall 48 is formed.

Further, as shown in FIG. 4E, an n ⁺⁺ source layer 49 and an n ⁺⁺ drain layer 410 are formed by ion implantation. At the same time, a p ⁺ -type HALO region 411 that is an object to be measured is formed. Furthermore, an electrode for bias voltage application (first electrode) (not shown) is formed, and a sample for SPM measurement is completed.

In this sample, the p ⁺ type HALO region 411 is in contact with the n-type conductivity type layer 42, and a pn junction is formed at the interface. In this way, the thicknesses of the n-type conductivity type layer 42 and the p-type conductivity type layer 41 are set in advance so that the p ⁺ -type HALO region 411 as the region measurement target is in contact with the n-type conductivity type layer 42 to form a pn junction. It is necessary to keep it.

  As in this embodiment, since the semiconductor region to be measured is in contact with a region having a conductivity type opposite to the conductivity type of the region, the resistance at the interface between the two becomes high, and the observation of the interface is highly sensitive. Can be done.

  In a normal MOS transistor structure, the n-type conductivity type silicon layer 42 is not formed, but source / drain regions and HALO regions are formed in the p-type conductivity type silicon layer. However, in such a sample with a normal MOS transistor structure, the p-type conductivity type silicon layer and the HALO region to be measured have the same conductivity type, so there is no steep carrier concentration distribution, and the HALO region It was difficult to measure the two-dimensional carrier concentration at the interface.

  Here, the p-type conductive layer is mentioned in the HALO region. However, when the substrate is of the opposite conductivity type, the n-type is used for the HALO region, and the periphery is a p-type conductive layer. Although the evaluation of the HALO region has been given here, the present invention can also be applied to the distribution measurement of other high resistance regions.

The schematic diagram of SPM in 1st Embodiment of this invention. The schematic diagram of SPM in 2nd Embodiment of this invention. The perspective view which shows the preparation process and sample structure of the sample in 3rd Embodiment of this invention. Sectional drawing which shows the preparation process and sample structure of the sample in 4th Embodiment of this invention.

Explanation of symbols

11 ... SPM chamber 12 ... SPM cantilever conductive probe (probe)
DESCRIPTION OF SYMBOLS 13 ... Semiconductor device cross-section sample 14 ... Sample stage 15 ... Bias power supply 16 ... Switching circuit 17 ... Micro current amplifier 18 ... Voltage log amplifier 19 ... Current log amplifier 110 ... Controller 21 ... SPM chamber 22 ... SPM cantilever conductive probe (probe) )
23 ... Semiconductor device cross section sample 24 ... Sample stage 25 ... Bias power supply 26 ... Switching circuit 27 ... Micro current amplifier 28 ... Current log amplifier 29 ... Controller 31 ... Si substrate 32 ... Source region 33 ... Drain region 34 ... SiO ₂ gate insulating film 35 ... Poly-Si gate electrode 36 ... SiN interlayer insulating film 37 ... Trench 38 ... Contact electrode 39 ... Electrode 40 ... Silicon substrate 41 ... p-type silicon layer 42 ... n-type silicon layer 43 ... SiO ₂ gate insulating film 44 ... NiSi gate electrode 45 ... P + type HALO region 46 ... n ⁺⁺ source extension region 47 ... n ⁺⁺ drain extension region 48 ... side wall 49 ... n ⁺⁺ source layer 410 ... n ⁺⁺ drain layer 411 ... p ⁺ type HALO region

Claims (5)

A probe having electrical conductivity and in contact with the sample;
Bias voltage applying means for applying a bias voltage to the sample;
A first amplifier that amplifies a signal from the probe generated when a bias voltage is applied to the sample and outputs an amplified signal, and the minimum value of the signal detection width is a1 and the maximum value is b1;
A first log amplifier connected to the first amplifier for converting the amplified signal output from the first amplifier into a log signal;
A signal from the probe generated when a bias voltage is applied to the sample is converted into a log signal, and the minimum value of the signal detection width is A2, the maximum value is B2, and a1 <A2 and b1 <B2 A second log amp that satisfies the relationship;
A switching circuit that switches the connection between the probe and the first amplifier and the second log amplifier according to the magnitude of the signal value from the probe;
A scanning probe microscope comprising means for obtaining spreading resistance from a log signal from the first log amplifier and / or the second log amplifier. A probe having electrical conductivity and in contact with the sample;
Bias voltage applying means for applying a bias voltage to the sample;
A first amplifier that detects and amplifies a signal generated when a bias voltage is applied to the sample, outputs the amplified signal, and has a minimum signal detection width of a1 and a maximum value of b1; ,
A signal from the probe generated when a bias voltage is applied to the sample is detected and converted to a log signal, and the minimum value of the signal detection width is A2, the maximum value is B2, and a1 <A2 and b1 <Second log amplifier satisfying the relationship of B2;
A switching circuit that switches the connection between the probe and the first amplifier and the second log amplifier according to the magnitude of the signal value from the probe;
A scanning probe microscope comprising: means for obtaining spreading resistance from a signal from the first amplifier and / or a log signal from the second log amplifier. A sample body having a measurement surface for measurement by a scanning probe microscope, wherein the first conductive region and the second conductive region to be measured are exposed on the measurement surface;
A first electrode formed on the sample body for applying a bias voltage to the surface to be measured;
A sample for a scanning probe microscope, comprising: a second electrode formed on the sample body and in contact with the second conductive region and the first electrode. Forming a measurement surface on which a first conductive region and the second conductive region are exposed in a sample body having a first conductive region and a second conductive region to be measured;
Etching the sample body to form a trench penetrating to the outside from the second conductive region;
Depositing a conductive material in the trench and forming a second electrode in contact with the second conductive region;
4. The scanning according to claim 3, wherein a step of forming a first electrode for applying a bias voltage to the surface to be measured on the sample body so as to be electrically connected to the second electrode is performed. Of forming a sample for a scanning probe microscope. A surface to be measured for measurement by a scanning probe microscope, the first surface of the first conductivity type being a test object on the surface to be measured, and the periphery of the measurement target area of the first semiconductor region A sample body that is exposed to a second semiconductor region that is a second conductivity type different from the first conductivity type and that forms a pn junction with the first semiconductor region;
A sample for a scanning probe microscope, comprising: a first electrode formed on the sample body for applying a bias voltage to the surface to be measured.

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