JP2813755B2 - Sensor for non-contact electric measurement of semiconductor wafer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact electric measurement used for measuring electric characteristics of a semiconductor wafer such as a CV curve.
It relates to a constant sensor .

[0002]

2. Description of the Related Art As one method of evaluating a process of a semiconductor having an MIS structure, an evaluation method based on CV measurement is used. In the conventional CV measurement, it is necessary to form an electrode for electric measurement on the surface of an oxide film on a semiconductor substrate. However, the process of forming an electrode only affects the electric characteristics itself of a semiconductor wafer. No. There is a problem that it takes time and effort to form the electrode itself. Therefore, the present applicant has developed an electric measurement apparatus for a semiconductor wafer that can perform an electric characteristic evaluation such as a CV measurement or a Ct method without forming an electrode on the surface of the semiconductor wafer.
FIG. 1 is a conceptual diagram showing an outline of a semiconductor electrical measurement device developed by the present applicant. In FIG. 1A, an oxide film 102 is formed on a surface of a semiconductor substrate 101,
An electrode 202 is formed on the back surface. Oxide film 102
The measurement electrode 201 is held by the electrode holding unit 300 with a gap Ge therebetween. The gap Ge between the oxide film 102 and the measurement electrode 201 is about 1
It is controlled by the electrode holding unit 300 so as to be not more than μm.

The capacitance Ct between the two electrodes 201 and 202 is, as shown in FIG.
, The capacitance Ci of the oxide film 102, and the capacitance Cg of the gap Ge.
The CV curve is the voltage dependency of the combined capacitance Cta of the capacitance Cs of the semiconductor substrate 101 and the capacitance Ci of the oxide film 102. The value of the gap Ge is accurately measured by the electrode holding unit 300, and the capacitance Cg of the gap is calculated based on the value of the gap Ge. The combined capacitance Ct is measured by the measuring unit 400, and the combined capacitance Ct
The CV curve is determined by calculating the capacitance Cta by subtracting the capacitance Cg of the gap from.

[0004]

The accuracy of the measurement of the gap between the semiconductor and the measurement electrode 201 and the accuracy of the electric measurement depend on the structure of the sensor including the measurement electrode 201. Conventionally, there has been no known device for non-contact electrical measurement of a semiconductor as described above, and in particular, no structure of a sensor unit suitable for this device has been known. Further, since a fine electrode pattern is formed at the tip of the sensor, it is necessary to make the sensor structure easy to manufacture.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to provide a sensor which can be easily manufactured and is suitable for non-contact measurement of electrical characteristics of a semiconductor.

[0006]

In order to solve the above-mentioned problems, a non-contact electric measurement sensor according to the present invention has a reflecting surface which is held substantially parallel to a surface of a semiconductor wafer with a gap therebetween. A non-contact electric measurement sensor for measuring the gap based on the intensity of the laser light reflected by the reflection surface and for measuring electric characteristics of the semiconductor wafer, the sensor including the reflection surface A light-transmitting member having a first surface, a second surface substantially parallel to the first surface, and an electrode for electric measurement formed on the first surface. It said second surface includes an incident surface to said light-transmitting member of the laser beam, the test electrode is in the electrode groove provided on the first surface, the test electrode Are arranged without protruding from the first surface. As described above, by using a light-transmitting member having first and second surfaces that are substantially parallel to each other, an electrode can be easily formed on the first surface by photolithography. In addition, the first electrode
The gap between the reflecting surface of the translucent member and the semiconductor wafer can be made smaller because of the arrangement in the electrode groove provided on the surface of the semiconductor device. Can be improved. Furthermore, since the electrodes can be prevented from contacting the semiconductor wafer, disconnection of the electrodes can be prevented.

[0007] The light-transmitting member is provided around the first surface .
Having a conical surface extending from the vicinity toward the second surface side,
To the conical surface, it is preferable that the electric wiring that is connected to the test electrode is formed. In this case, the external lead wire and the electric wiring can be connected by a conical surface . That is, the external lead wire and the electric wiring of the sensor can be connected at a position farther from the semiconductor wafer than the reflection surface of the laser beam. Therefore, even when connection is made with, for example, silver paste, there is no concern that the swelling of the connection portion is caught in the gap between the reflection surface and the semiconductor wafer.

The first surface and the semiconductor wafer
In order to adjust the degree of parallelism , N pieces (N is an integer of 3 or more) of the same shape provided on the first surface at symmetric positions with respect to the electrode for electric measurement.
May be provided. If the inclination of the first surface of the sensor is adjusted so that the capacitances of the N parallelism adjusting electrodes are equal to each other, the parallelism between the first surface and the semiconductor wafer can be adjusted.

[0009] The light-transmissive member is provided around the first surface .
In part, the first surface and comprising a substantially parallel the wiring formation surface formed stepwise at a position closer to the second surface than the first surface, the test electrode to the wiring formation surface It is preferable to form an electric wiring connected to the wiring .

In this case, the wiring formation surface and the semiconductor wafer are
Since the parasitic capacitance generated during
Accuracy can be improved.

[0011] In the non-contact electric measurement sensor, the laser light may be further introduced from the second surface to the translucent member, and the laser light reflected by the reflection surface may be applied to the second surface. It is preferable to provide an optical waveguide unit that emits light from the light transmitting member to the outside of the light transmitting member. The optical waveguide means may be an optical element such as a prism bonded to the light transmitting member, or a part of the light transmitting member is processed to form an incident surface and an emission surface of laser light, and It may be used as optical waveguide means.

A guard ring electrode to which a predetermined potential is applied may be formed between the electric measurement electrode and the parallelism adjustment electrode. By providing the guard ring electrode, mutual interference between a plurality of electrodes can be reduced, thereby improving the parallelism adjustment and the accuracy of electric measurement. Above sensor for non-contact electricity measurement
And the surface of the electrode for electric measurement and the first table
The plane may be matched. In this way, the first
Consider the level difference between the reflective surface of the surface 1 and the electrode for electrical measurement
No need.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Configuration of Apparatus FIG. 2 is a conceptual diagram showing a configuration of an electric measurement apparatus MD including a sensor as an embodiment of the present invention. The electric measuring device MD includes a measuring unit 20 for storing the semiconductor wafer 100.
, A light amount measuring device 22, an impedance meter 24,
A position control device 26 and a host controller 28 are provided. The light quantity measuring device 22, the impedance meter 24, and the position control device 26 are connected to a host controller 28, which controls the entire measuring device and processes the obtained data. As the host controller 28, for example, a personal computer is used.

The measuring section 20 includes a base 32 and a base 32
The apparatus includes a driving device 34 provided thereon, a gantry 36 connected to a ball screw portion 34a of the driving device, and a sample table 38 mounted on the gantry 36. Sample table 3
Reference numeral 8 denotes a table on which a semiconductor wafer 100 as a test object is mounted, and is driven by a motor (not shown) to rotate in an XY plane.

A flange 42 is fixed to the upper opening of the housing 40 of the measuring section 20 with bolts, and three piezoelectric actuators 44, 45, and 46 utilizing piezo elements are provided below the flange 42. I have. Further, a support plate 48 is provided below the piezoelectric actuator units 44, 45, 46, and a sensor head 60 is fixed to a tip of a support cylinder 50 extending below the support plate 48.
The support plate 48 is connected to the flange 42 by a plurality of springs (not shown).
5 and 46 are pushed up to the flange 42 side. The sensor head 60 includes a right-angle prism 62 for introducing a laser beam, and a light-transmitting electrode forming portion 64 bonded to the bottom surface of the right-angle prism 62 with an optical adhesive.

A laser oscillator 70 such as a GaAlAs laser and a light receiving sensor 72 such as a photodiode are fixed to the support cylinder 50. The laser light emitted from the laser oscillator 70 passes through the right-angle prism 62 and the electrode forming portion 6
4 and is reflected on the bottom surface of the electrode forming portion 64 under geometrical optical total reflection conditions. Then, the reflected laser light is emitted from the right-angle prism 62 and received by the light receiving sensor 72.

When electric measurement of the semiconductor wafer 100 is performed, the gap between the bottom surface of the sensor head 60 and the surface of the semiconductor wafer 100 is kept at about 1 μm or less. An optical system including the laser oscillator 70, the sensor head 60, and the light receiving sensor 72 is an optical measurement system for accurately measuring the gap. This optical measurement system uses a laser oscillator 7
Utilizing the tunneling phenomenon of the laser light when the laser light oscillated from 0 is reflected on the bottom surface of the sensor head 60 under the geometric total reflection condition, it is measured by the light receiving sensor 72 and the light quantity measuring device 22. The value of the gap is measured based on the amount of light. The method for measuring the gap is described in detail in Japanese Patent Application Laid-Open No. Hei 4-32704, which was disclosed by the present applicant, and the details are omitted here.

The piezoelectric actuators 44, 46, and 48 are electrically connected to the position control device 26, and the light receiving sensor 72 is connected to the light amount measuring device 22 and is connected to an electrode formed on the bottom surface of the sensor head 60. The impedance meter 24 is connected to the metal sample table 38.
The impedance meter 24 is connected to each electrode and the sample table 3.
This is a device for measuring the capacitance and conductance between the device and the device.

B. Basic Configuration of Electrode Forming Section FIG. 3A is a bottom view of the electrode forming section 64, and FIG. 3B is a BB cross-sectional view thereof. The electrode forming portion 64 includes a cone glass 66 formed of optical glass and an electrode pattern 200 formed on the bottom surface 66a of the cone glass 66. The electrode pattern 200 is the electrode 2 for electric measurement.
01, three parallelism adjusting electrodes 111 to 113, and a guard ring 120.
Wirings 20 connected to 111 to 113 and 120, respectively
1a, 111a to 113a, and 120a. These wirings are formed from the bottom surface 66a of the cone glass 66 to the side slope 66b. Cone glass 66
As described later, disk-shaped glass is polished and the side surface is cut into a tapered shape. Since the two bottom surfaces of the cone glass 66 are parallel to each other, the electrode pattern 200 can be easily formed by photolithography.

The electrode 201 for electric measurement is a ring-shaped electrode, and the surface of the cone glass exposed at the center is a reflection surface 66c from which the laser light L is geometrically totally reflected. In this embodiment, the inner diameter of the electrode 201 for electrical measurement is 0.5 mmφ, and the outer diameter is 1.0 mmφ.

Three parallelism adjusting electrodes 111 to 113
Has a ring-like shape equally divided into three. In this embodiment, the parallelism adjusting electrode 111 is used.
The inner diameter of the ring of ~ 113 is 1.6mmφ, the outer diameter is 2.4
mmφ. The interval between the electrodes 111 to 113 is 0.7 mm. The shape of each of these electrodes may be circular, but if they are divided into ring shapes as shown in FIG. 3A, there is an advantage that an electrode having a larger area can be formed in a smaller region. is there. The parallelism adjusting electrodes 111 to 113 are provided on the bottom surface 6 of the cone glass 66.
This is an electrode used when adjusting the parallelism between 6a and the surface of the semiconductor wafer 100. That is, if the inclination of the bottom surface 66a of the cone glass 66 is adjusted by adjusting the amount of extension of the piezo elements of the piezoelectric actuator units 44, 45, and 46, and the capacitance values of the electrodes 111 to 113 are made equal to each other, the cone Semiconductor wafer 1 with bottom surface 66a of glass 66
00 surface can be parallel. The details of the parallelism adjustment will be described later.

The guard ring 120 is connected to the electrode 2 for electric measurement.
01 and a ring-shaped electrode provided between the parallelism adjusting electrodes 111 to 113, the inner diameter of which is 1.2 mmφ,
The outer diameter is 1.4 mmφ. The guard ring 120 is maintained at a predetermined potential (for example, ground potential) and has a role of preventing interaction between the four electrodes 201, 111 to 113. By providing such a guard ring 120, the capacitance value of the electrode 201 for electric measurement can be measured without being affected by the electrodes 111-113 for parallelism adjustment, so that the measurement accuracy of electric measurement can be improved. There is an advantage. Also, three parallelism adjusting electrodes 111
Can be measured without being influenced by each other, the bottom surface 66a of the cone glass 66 and the semiconductor wafer 10 can be measured.
There is an advantage that the parallelism with the zero surface can be adjusted with higher precision. In addition, each electrode 201, 111-113,
The gap between 120 is set to 0.1 mm,
Also, the wirings 201a, 111a to
The width of 113a is set to 0.1 mm.

FIG. 4 is a front view showing the connection state of the wiring of the sensor head 60. Wiring 111 on cone glass 66
a to 113a, 120a and 201a are cone glass 6
The end of the side slope 6 is connected to an external lead wire 116. The connection of the wiring is performed by wire bonding or curable silver paste, and the connection portion may be raised by several hundred μm. The reason why the wiring is connected at a position above and away from the bottom surface 66a of the cone glass 66 is that the bottom surface 66a of the cone glass 66 and the semiconductor wafer 10 are connected.
This is to prevent the swelling of the connection portion from being caught between the surface and the zero surface. At the time of electrical measurement, the gap between the bottom surface 66a and the surface of the semiconductor wafer 100 is set to about 1 μm or less. The problem of contact with the wafer 100 occurs. One of the reasons for using the frusto-conical cone glass 66 is to enable the connection between the wiring on the electrode forming portion 64 and an external lead wire at a distance from the bottom surface 66a.

C. Structure for Reducing Parasitic Capacitance of Wiring Part In measurement of CV characteristics and Ct characteristics of a semiconductor wafer, the capacitance between the electrode 201 for electric measurement and the semiconductor wafer 100 is measured. By the way, the electrode forming portion 64 shown in FIG.
01 and the wiring 201a thereof, the capacitance Cm measured by the impedance meter 24 is given by the following equation. Cm = Cg + Cp where Cg is the electric measurement electrode 201 and the semiconductor wafer 1
00 and the capacitance (measured capacitance) Cp is the wiring 20
This is the capacitance (parasitic capacitance) between the semiconductor wafer 100 and the semiconductor wafer 1a. FIG. 5 is a diagram schematically illustrating a cross section of the electrode forming portion 64 and a measured capacitance Cm.

The measured capacitance Cg and the parasitic capacitance Cp are expressed by the following equations. Cg = Sg · ε / Ge Cp = Sp · ε / Ge where Sg is the area of the electrode 201, ε is the dielectric constant of air,
Ge is the gap between the electrode 201 and the surface of the semiconductor wafer 100, and Sp is the area of the wiring 201a. The parasitic capacitance Cp is determined by the gap Ge between the wiring 201a and the surface of the semiconductor wafer.
, The value of the parasitic capacitance Cp can be obtained based on the measured value of the gap Ge. However, when the capacitance Cg to be measured and the parasitic capacitance Cp have substantially the same value, the measurement accuracy of the measured capacitance Cg may be reduced. Therefore, it is preferable that the parasitic capacitance Cp be as small as possible.

As can be seen from the above equation of the parasitic capacitance Cp,
In order to reduce the parasitic capacitance Cp, it is effective to reduce the area S and increase the gap Ge. In this embodiment, as shown in FIG. 3A, the width of the wiring 201a on the bottom surface 66a of the cone glass 66 is reduced to reduce its area Sp. On the bottom surface 66a, the area ratio between the electrode 201 for electric measurement and the wiring 201a is about 10: 1, so that the parasitic capacitance Cp is about 1% of the capacitance Cg to be measured.
/ 10.

Another measure for reducing the parasitic capacitance Cp is to provide a step in the portion where the wiring 201a is formed and increase the gap between the wiring 201a and the semiconductor wafer 100 as shown in FIG. . The measured capacitance Cg and the parasitic capacitance Cp in the case of FIG. 6 are respectively expressed by the following equations. Cg = Sg · ε / Ge Cp = Sp · ε / (Ge + △ Ge) The value of the step ΔGe depends on the value of the gap Ge during electric measurement. FIG. 7 is a graph showing the resolution of the gap measurement obtained in consideration of the detection accuracy of the laser beam by the light receiving sensor 72 (FIG. 2). According to FIG. 7, the best resolution is obtained when the gap Ge is in the range of 0.2 to 0.3 μm. Since the accuracy of the CV measurement depends on the measurement accuracy of the gap Ge, the value of the gap Ge at the time of measurement is optimally about 0.2 to 0.3 μm.

Assuming that the gap Ge is 0.2 μm and the step ΔGe is 2 μm, the gap (Ge + ΔGe) between the wiring 201a and the semiconductor wafer 100 is 2.2 μm.
m, which is 11 times the gap Ge. This step ΔG
Due to the effect of e, the parasitic capacitance Cp is 1/1 / of the measured capacitance Cg.
It becomes 11. Further, the electrode 201 and the wiring 201 described above are used.
Considering the area ratio of a, the measured capacitance Cg and the parasitic capacitance Cg
Since the ratio to p is about 100: 1, the influence of the parasitic capacitance Cp on the CV measurement can be suppressed to a considerably small value.

FIG. 8 is a sectional view showing an electrode forming portion 500 of a type in which a step is provided at the boundary between the electrode 201 and the wiring 201a, and corresponds to FIG. 3B. In the example of FIG. 8, the height of 2 μm is set around a circle having an outer diameter of 2.4 mmφ corresponding to the outer circumference of the three parallelism adjusting electrodes 111 to 113.
Is provided. For convenience of illustration, the step of 2 μm is exaggerated.

FIG. 9 is a sectional view showing an electrode forming part 510 obtained by further improving the electrode forming part 500 of FIG. In the electrode forming section 510, the electrode pattern 200 is embedded in the bottom surface 512a of the cone glass 512. Reflection surface 512c of cone glass 512 and electrode pattern 20
If the surface is matched with the surface of the reflective surface 512 during the electrical measurement,
There is an advantage that there is no need to consider the step between c and the electrode surface.

FIG. 10 is a sectional view showing an electrode forming portion 520 having a structure in which the electrode pattern 200 is embedded deeper than the reflection surface 522c of the cone glass 522. In the electrode forming portion 520, the electrode pattern 200 formed on the bottom surface of the cone glass 522 does not come into contact with the semiconductor wafer 100. Therefore, there is an advantage that disconnection of the electrode pattern 200 can be prevented. Electrode pattern 20
Since the disconnection of 0 is one of the main factors that determine the life of the sensor head, the structure shown in FIG. 10 can extend the life of the sensor head. The step between the reflection surface 522c of the cone glass 522 and the surface of the electrode pattern 200 can be precisely measured in advance with an interference microscope.

D. Manufacturing Process of Electrode Forming Section FIG. 11 is a cross-sectional view showing a manufacturing process of the cone glass 522 of FIG. FIG. 11A shows a cross section of a disk-shaped glass 521 used as a material for cone glass. The glass material is an optical glass such as BK7. When the periphery of the upper surface of the disc-shaped glass 521 is polished in a conical shape, FIG.
The cone glass 522 shown in FIG. 1 (b) is obtained. The smaller bottom surface 522a of the cone glass 522 is a surface on which an electrode is formed. Since the two bottom surfaces of the cone glass 522 are parallel to each other, a photolithography process to be described later can be performed using a processing apparatus for a semiconductor wafer.

The peripheral edge of the bottom surface 522a has a rounded edge with a rounded edge, and the side slope 522 extends from the bottom surface 522a.
The shape is formed so as to have a gentle curved surface from b. The reason why the edge of the peripheral portion of the bottom surface 522a is rounded is to prevent disconnection when an electrode pattern is formed. That is, if there is a sharp edge (corner) at the peripheral portion of the bottom surface 522a, the resist pattern becomes thick at the edge portion, and an extra resist may be left in a thin wiring pattern portion. In this case, a problem occurs in that the wiring pattern is cut off at the extra resist portion. Therefore, the edge of the peripheral portion of the bottom surface 522a is rounded so that extra resist is not left on the edge, thereby preventing disconnection. Note that FIG.
Is manufactured in the process up to FIG. 11B.

Next, as shown in FIG. 11C, a resist 702 is applied on the bottom surface 522a of the cone glass 522 to form a 2.4 mmφ circular resist pattern. Further, the peripheral portion of the bottom surface 522a of the cone glass 522 and the side slope 522b are
Is etched to a predetermined depth (here, about 2 μm). As a result, as shown in FIG. 11D, a cone glass 522 in which a step is formed at the peripheral edge of the upper bottom surface is obtained. As described above, this step is for reducing the capacitance of the wiring portion. FIG. 11E shows the resist 70.
2 shows the cone glass 522 from which 2 has been removed. The cone glass 512 in FIG. 9 is manufactured through the steps up to FIG.

FIG. 12 shows the cone glass 5 shown in FIG.
FIG. 14 is a cross-sectional view showing a main step of forming an electrode pattern 200 on the bottom surface 522a of the substrate 22. First, as shown in FIG. 12A, a resist pattern 704 is formed on the bottom surface 522a.
To form FIG. 13 is a plan view showing the resist pattern 704. As can be seen from FIG. 13, this resist pattern 704 is a pattern obtained by inverting the electrode pattern 200 (see FIG. 3).

By performing etching in this state, a groove is formed in the electrode pattern portion, and a cone glass 522 having the structure shown in FIG. 12B is obtained. The depth of the groove of the electrode pattern is about 0.1 μm. Next, FIG.
By depositing a metal 706 and performing lift-off as shown in FIG. 12, a structure shown in FIG. FIG.
2 (d), the metal remaining in the groove
An electrode pattern 200 shown in FIG. Various metals such as gold and tungsten can be used as the metal to be deposited. Here, chromium (Cr) is used. This is because chromium is relatively inexpensive and has high hardness and is hard to be disconnected.

When the thickness of the metal to be deposited is made smaller than the depth of the groove of the cone glass 522 at the time of metal deposition, FIG.
As shown in FIG. 2 (d) and FIG.
A structure is obtained in which 0 is set back to the inside of the glass from the reflection surface 522c of the cone glass 522. On the other hand, when the thickness of the metal to be deposited is equal to the depth of the groove of the cone glass 522, a structure in which the surface of the electrode pattern matches the reflection surface of the cone glass is obtained as shown in FIG.

As described above, if a cone glass having two bottom surfaces parallel to each other is used, there is an advantage that an electrode pattern can be easily formed on the cone glass by photolithography.

E. Other Configuration of Sensor Head FIG. 14A is a cross-sectional view illustrating another configuration of the sensor head. The sensor head 530 includes a right-angle prism 532
The side slope 532b is created by shaving the end of the side slope 5b.
32b and the bottom surface 532a.
Are formed by forming. Bottom 5
The electrode pattern 200 on 32a is the same as that shown in FIG. The central portion of the bottom surface 532a is a laser light reflection surface 532c. That is, the right-angle prism 532 is different from the right-angle prism 62 of FIG.
4 plays both roles. External lead 116
Are connected to the wiring formed on the side slope 532. In this case, as in the case of the sensor head using cone glass, the bulge of the connection portion is not sandwiched by the gap between the sensor head and the semiconductor wafer. FIG.
(B) is a plan view of the prism 532, and the wiring patterns and the lead wires are omitted for convenience of illustration.

FIG. 14C is a cross-sectional view showing a state where the right-angle prism 532 is mounted on the holder 534 in the photolithography process. In this state,
The bottom surface of the lower part of the holder 534 and the bottom surface 5 of the right angle prism 532
32a are parallel to each other, so that photolithography can be easily performed. However, a sensor head using cone glass does not require such a holder, and thus is easier to handle.

FIG. 15A is a sectional view showing still another configuration of the sensor head. This sensor head 540
Is composed of a right-angle prism 542 and an electrode forming portion 544 bonded to the bottom surface of the right-angle prism 542 with an optical adhesive. FIG. 15B is a plan view of the sensor head 540. The electrode forming portion 544 is formed by forming the electrode pattern 200 on the bottom surface of a disc-shaped optical glass. If the disc-shaped optical glass is used, the electrode pattern 200 can be easily formed by photolithography.

FIG. 16A is a sectional view showing another configuration of the sensor head. This sensor head 550 is the same as that shown in FIG.
5, the right-angle prism 552
And a disk-shaped electrode forming portion 554. However, in the sensor head 550 of FIG. 16A, the through-hole 55 penetrates the right-angle prism 552 and the electrode forming portion 554.
6 are provided at several places, and wirings for connecting the electrode pattern 200 and the external lead wires 116 are provided in the through holes 556. In this case, the connecting portion connecting the electrode pattern 200 of the sensor head and the lead wire 116 is formed at a position away from the bottom surface 554a of the electrode forming portion 554 (that is, on the prism surface of the right-angle prism 552). The bulge of the connection portion is not pinched by the gap between the bottom surface 554a and the semiconductor wafer.

FIG. 16B is a cross-sectional view showing another configuration of the sensor head similar to FIG. 16A. This sensor head 560 also has a plurality of through-holes 566 in the disc-shaped electrode forming portion 564, and further has the electrode forming portion 564.
A groove for laying wiring is provided on a boundary surface between the rectangular prism 562 and the rectangular prism 562. That is, the wiring connecting the electrode pattern 200 and the external lead wire 116 is formed in the through hole 566.
And passes through a groove provided on the boundary surface between the electrode forming portion 564 and the right-angle prism 562. In this case, there is no need to provide a through-hole in the right-angle prism 562.
Processing is easier than the sensor head of (a).

In the sensor head shown in FIGS. 14 to 16, as shown in FIG.
A step may be provided at the boundary with 01a. Further, as shown in FIGS. 9 and 10, the electrode pattern may be embedded in the bottom surface of the sensor head. In the above-described sensor head, a right-angle prism is used as a means for introducing laser light to the electrode forming portion. However, another prism having a prism angle other than 90 degrees may be used. Further, an optical element such as an optical fiber other than the prism may be used.

[0045] may be used an angular frustum-shaped translucent member instead of the frustoconical cone glass. In general, if a translucent member having two parallel bottom surfaces and a conical portion is used, it is easy to form an electrode pattern by photolithography and easily connect to an external lead wire. It can be a head.

As the external lead wire, a connector 600 having a plurality of metal claws 602 as shown in FIG. 17A is used instead of a wire-like wiring. May be electrically connected by mechanically contacting the wiring. FIG.
(B) is a sectional view showing a state where the sensor head 60 is fixed to the connector 600. Since the connection portion of the cone glass is separated from the reflection surface of the laser beam, the sensor head 60 can be mechanically fixed to the claw-shaped member 602 in this manner.

F. FIG. 18 is a schematic diagram showing an equivalent circuit including the parallelism adjusting electrodes 111 to 113, the measuring electrode 201, and the semiconductor wafer 100. FIG. 18A shows the parallelism adjusting electrodes 111 to 113 (indicated by letters S, T and U in the figure) and the semiconductor wafer 100 (indicated by letter W in the figure). ) Is shown. Since the distance between the parallelism adjusting electrodes 111 to 113 and the semiconductor wafer 100 is adjusted so as to be very short (about 1 μm or less), the conductance G and the capacitance C are respectively set to the electrodes 111 to 113 and the semiconductor wafer 100. And can be considered to be joined by

Similarly, as shown in FIG. 18B, the conductance G and the capacitance C are coupled between the measurement electrode 201 (indicated by the letter M in the figure) and the semiconductor wafer 100. Can be regarded as being. Therefore, the measurement electrode 201 and the parallelism adjustment electrode 111
The equivalent circuit between (a) and (b) is a circuit in which the equivalent circuit of (a) and the equivalent circuit of (b) are connected in series at the portion of the semiconductor wafer 100. FIG. 18C shows the measurement electrode 2.
FIG. 2 shows an equivalent circuit between 01 and parallelism adjusting electrodes 111 to 113. That is, the measuring electrode 201 and the parallelism adjusting electrodes 111 to 113 constitute a symmetrical load of a Y-shaped connection with the conductance G and the capacitance C centered on the measuring electrode 201.

The electrodes 111, 112, 113, 2
Since the distance between S.01 and S.01 is set to, for example, about 0.1 mm, these electrodes are directly electrically connected (ie, not through a semiconductor wafer). Can also be represented by the equivalent circuit of FIG.

When the CV measurement of the semiconductor wafer is performed, the capacitance of the parallelism adjusting electrodes 111 to 113 is measured by the impedance meter 24, and the piezoelectric actuator units 44 to 46 are controlled so that their values match. Thereby, the parallelism between the semiconductor wafer 100 and the measurement electrode 201 is maintained. Then, a CV curve is measured using the measurement electrode 201.

The capacitance measurement for adjusting the parallelism and the capacitance measurement for obtaining the CV curve are both measurements using the characteristics of the capacitance with respect to the AC applied signal. Therefore, when trying to measure the CV curve with the measuring electrode 201 while measuring the capacitance with the parallelism adjusting electrodes 111 to 113 and maintaining the parallelism, usually the parallelism adjusting electrodes 111 to 113 are used.
The AC signal applied to 13 is applied as disturbance to measurement electrode 201 via conductance G and capacitance C described above. Therefore, it is difficult to perform an accurate CV measurement.

On the other hand, if the parallelism is not adjusted during the CV measurement, the above-described problem does not occur.
However, when an element having expansion and contraction characteristics according to an applied voltage, such as a piezo element, is used as the piezoelectric actuator units 44 to 46, it is necessary to keep adjusting the parallelism during the CV measurement. This is because a transient phenomenon cannot be ignored in a piezo element, and the element may expand and contract in sub-micron units even when the applied voltage is constant.

This embodiment takes the above points into consideration,
It is designed so that even if an AC signal is applied to the parallelism adjusting electrodes 111 to 113, it does not cause disturbance to the measuring electrode 201. FIG. 19 shows the parallelism adjusting electrodes 111-1.
13 shows a basic connection relationship between the power supply 13 and the AC power supply 130.
The AC power supply 130 is a power supply that generates a so-called Y-connection three-phase AC, has the same line voltage, and outputs three AC signals whose phases are different by 120 °. Parallelism adjusting electrodes 111-113 and measuring electrode 20
1 is also represented as a Y-connection load as shown in FIG. Then, as shown in FIG. 19, each output line of the AC power supply 130 is connected to each of the parallelism adjusting electrodes 111 to 113.
Connected to.

Since the parallelism adjusting electrodes 111 to 113 have the same shape, the impedance between the measurement electrode 201 and each of the parallelism adjusting electrodes 111 to 113 is maintained when the parallelism is maintained. Are equal, and these equivalent circuits have symmetric Y-type loads. Therefore, if the connection is made as shown in FIG. 19, when the parallelism is maintained, the measurement electrode 20
1 has the same potential as the neutral point NP of the AC power supply 130. As a result, an AC signal applied to the parallelism adjusting electrodes 111 to 113 is not applied to the measuring electrode 201 as a disturbance.

FIG. 20 shows the parallelism adjusting electrodes 111 to 11.
FIG. 3 is a diagram showing an actual connection relationship between the AC power supply 3 and an AC power supply 130.
Three transmission lines 130a to 130c of three-phase AC power supply 130
Are the parallelism adjusting electrodes 111 to 1 via the resistors R, respectively.
13 is connected. Further, neutral point NP of three-phase AC power supply 130 and electrode 202 (see FIG. 1) on the back surface of the semiconductor wafer are grounded.

The signals Sm1 to Sm3 appearing on the parallelism adjusting electrodes 111 to 113 are given to the capacitance meters 131 to 133 as measurement signals, respectively. The signals Sa1 to Sa3 of the transmission lines 130a to 130c are also applied to the capacity meters 131 to 133 as applied signals. The capacitance meters 131 to 133 are connected to the respective parallelism adjusting electrodes 111 to 1 based on these measurement signals and applied signals.
The capacitance between the semiconductor wafer 13 and the semiconductor wafer is measured.
The resistors R connected to the parallelism adjusting electrodes 111 to 113 are a part of the constituent elements of the capacity meters 131 to 133. However, in order to clarify the correspondence with FIG. Is drawn separately. In addition, three-phase AC power supply 1
30 and the capacity meters 131 to 133 are some of the components of the impedance meter 24 shown in FIG.

FIG. 21 is a conceptual diagram for explaining a method of measuring the capacitance in the capacitance meters 131 to 133. FIG. 21A is a cross-sectional view showing one parallelism adjusting electrode 111 and a semiconductor wafer. As described above, the parallelism adjusting electrode 111 and the electrode 202 on the back surface of the semiconductor wafer are used.
(That is, the parallelism adjusting electrode 111)
-Air gap-oxide film 102-depletion layer 103-substrate 1
The equivalent circuit between the 01-electrode 202) can be represented by a capacitance C and a conductance G connected in parallel between the parallelism adjusting electrode 111 and the electrode 202, as shown in FIG. it can.

Although the capacitance Ct is drawn between the electrode 202 and the measurement electrode 201 in FIG. 20, the potential of the measurement electrode 201 is equal to the neutral point NP of the AC power supply 130 as described above. Since it is at the ground potential, this capacitance C
t can be ignored. Therefore, the circuit between the electrode 111 and the electrode 202 in FIG.
This is equivalent to the circuit of FIG. The admittance Y of the circuit shown in FIG.

(Equation 1) The impedance Z of this circuit is represented by the following equation (2).

(Equation 2)

FIG. 21C shows the parallelism adjusting electrode 111.
FIG. 3 is a circuit diagram showing a circuit portion including a power supply, an electrode 202, and an AC power supply 130. The measurement signal Sm1 appearing on the parallelism adjusting electrode 111 is expressed by the following equation (3).

(Equation 3) Further, the applied signal Sa1 is represented by the following Expression 4 by the measurement signal Sm1.

(Equation 4) That is, the phase of the applied signal Sa1 is ahead of the phase of the measurement signal Sm1. Assuming that this phase angle is ψ, the following Expression 5 is established.

(Equation 5)

In equation (5), if ωCR and RG are sufficiently small, the value of K is almost constant at 1. In this case, sin
ψ is proportional to C, and cos す る is proportional to (1 + RG).
For example, the frequency of the applied signal Sa1 is 100 kHz, and C =
Assuming that 100 pF and R = 10 kΩ, 2 of (ωCR)
The power is about 0.004, and G = 0.1 μS (=
0.1 μ / Ω), the value of RG is 0.004 or less, so that K = 1 can be considered.

If the value of K is almost constant, sinψ becomes C
Therefore, if sinψ is obtained, the capacitance C
Can be determined. sinψ is
It can be obtained as follows. First, when the measurement signal Sm1 is expressed by Sm0 · sin (ωt) as in the following Expression 6, the applied signal Sa1 is expressed as in Expression 7 using the phase angle ψ. Here, Sm0 and Sa0 are constants.

(Equation 6)

(Equation 7)

Here, the term sin (ωt + ψ) is changed to (ω
By integrating from π / 2 to 3π / 2 in t), a value proportional to sinψ can be calculated as shown in Expression 8.

(Equation 8) Generally, an integral value In proportional to sinｓ can be obtained by integrating the applied signal Sa1 in each of two phase sections of the measurement signal Sm1 as follows. a. The first phase section [(π / 2 + 2n) of the measurement signal Sm1
π) to (3π / 2 + 2nπ)]: The integral value In is obtained by integrating the applied signal Sa1 (Equation 9).

(Equation 9) b. The second phase section of the measurement signal Sm1 [(3π / 2 + 2
nπ) to (5π / 2 + 2nπ)]: Integrate (Equation 10) the signal -Sa1 obtained by inverting the applied signal Sa1, and obtain an integral value In.
Ask for.

(Equation 10)

As described above, by integrating the applied signal Sa1 in each of the two phase sections with reference to the measurement signal Sm1, the integral value In proportional to the sine sin 正弦 of the phase angle に お い て is obtained in each phase section. Can be. Since this integral value In is proportional to sinψ, if the values of the integral values In for the three parallelism adjusting electrodes 111 to 113 are equal to each other, s for each of the parallelism adjusting electrodes.
The values of inψ are also equal to each other. Further, since the value of sin 比例 is proportional to the capacitance C, as described in Equation 5, if the value of sin に 関 す る for each parallelism adjusting electrode is equal to each other, the distance between each parallelism adjusting electrode and the semiconductor wafer is equal. Are equal to each other. Since the capacity of the gap is inversely proportional to the size of the gap, if the capacities are equal to each other, it can be said that the sizes of the gaps are also equal to each other. Therefore, if the piezoelectric actuator units 44 to 46 are adjusted so that the values of the integral values In of the three parallelism adjusting electrodes 111 to 113 are equal to each other, the bottom surface 66 a of the electrode forming unit 64 of the sensor head 60 and the semiconductor wafer are adjusted. Can be adjusted.

In practice, the value of K in Equation 5 is not constant but depends on the capacitance C. Therefore, the relationship between the integral value In and the capacitance C deviates from the linear proportional relationship as shown by the solid line in FIG. However, it is not necessary to accurately measure the value of the capacitance C in order to adjust the parallelism, and if the value of the capacitance C as a monotonic function can be measured, the measured values at the respective electrodes for adjusting the parallelism are made equal to each other. Thereby, the parallelism can be adjusted. Therefore, as the capacity meter for adjusting the parallelism, it is sufficient to use a device that can obtain the above-described integral value In.

FIG. 23 shows the capacity meter 131 shown in FIG.
FIG. 2 is a block diagram showing an internal configuration of the device. FIG. 24 is a timing chart showing main signals in the circuit of FIG. The resistance R inserted between the transmission line 130a and the parallelism adjusting electrode 111 in FIG.
Is an internal circuit of the capacity meter 131 as described above, and is inserted between the two input terminals T1 and T2 in FIG. This resistor R has a role of delaying the phase of the measurement signal Sm1 appearing at the first input terminal T1 from the phase of the applied signal Sa1, as can be seen from Equation 5. The first input terminal T1 is connected to the parallelism adjusting electrode 11.
1 and the second input terminal T2 is connected to the transmission line 130a.

The capacitance meter 131 includes a first buffer amplifier 151 and a detector 152 in addition to the resistor R.
, An integrator 153, a second buffer amplifier 154,
A voltmeter 155 is provided. The capacitance meters 132, 133 for the other parallelism adjusting electrodes 112, 113
Also has the same configuration as the capacity meter 131 of FIG.

The applied signal S appearing at the second input terminal T2
a1 is a clean sine wave as shown at the top of FIG. The application signal Sa1 corresponds to the power supply signal in the present invention. The measurement signal Sm appearing at the first input terminal T1
1 is amplified by the buffer amplifier 151 and multiplied by α.
The signal α · Sm1 shown in FIG. This signal is a sine wave including a noise component, and its phase is delayed from the applied signal Sa1 by the above-described phase angle ψ.

The signal α · Sm1 output from the buffer amplifier 151 is the signal α · Sm1 applied to the second input terminal.
The signal is input to the detection unit 152 together with a1. Detection unit 152
In order to enable the integrator 153 to perform the integration of the above equations 9 and 10, (a) detects two phase sections of the measurement signal Sm1 and (b) detects two phase sections corresponding to the two phase sections, respectively. Extract the waveforms of the applied signals Sa1 and -Sa1,
(C) The signal SM having this waveform is output. Detector 1
52 is a 90 ° phase shifter 152a and a switching signal generator 15a.
2b, a switch 152c, and a 180 ° phase shifter 152d.
And The 90 ° phase shifter 152a converts the phase of the signal α · Sm1 given from the buffer amplifier 151 by 9
By delaying by 0 °, a signal Sms shown in FIG. 24 is generated.

This signal Sms is supplied to switching signal generator 152b.
, And the switching signal generator 152b generates two switching signals SS1 and SS2 based on the signal Sms. The first switching signal SS1 is H when the value of the signal Sms is positive.
This signal is a signal that becomes L level when the signal is negative.
On the other hand, the second switching signal SS2, on the other hand,
Is a L level when the value is positive, and a H level when the value is negative. The phase of the signal Sms is the measurement signal Sm1
24 is delayed by 90 ° (= π / 2) from the phase of FIG.
As shown in the figure, the first switching signal SS1 has a first phase interval [(π / 2 + 2nπ) to (3π / 2 + 2n) of the signal Sms.
π)], and the second switching signal SS2 becomes the second phase section [(3π / 2 + 2nπ)-(5π)] of the signal Sms.
.pi. / 2 + 2n.pi.)]. These switching signals SS1 and SS2 are provided to a switch 152c.

As described above, as a result of switching the levels of the switching signals SS1 and SS2 at the zero cross point of the signal Sms, the periods of the H level and the L level may not be equal. In this case, the switching signal generator 1
By adjusting the signal level (slice level) for switching at 52b, the periods of the H level and the L level are made equal (that is, the duty is 50%).
).

The switching signal 152 is supplied to the switch 152c.
Along with S1 and SS2, an applied signal Sa1 and its inverted signal -Sa1 (shown by a broken line at the top of FIG. 24) are input. The inverted signal -Sa1 is generated by delaying the phase of the applied signal Sa1 by 180 ° by the 180 ° phase shifter 152d. The switch 152c outputs the first switch signal S
During the period when S1 is at the H level, the applied signal Sa
1 is output as the output signal SM of the detector 152, and
The inverted signal -Sa1 is output as the output signal SM of the detector 152 during the period when the second switching signal SS2 is at the H level. As a result, as shown in FIG. 24, the output signal SM has two phase sections [(π / 2 +) of the measurement signal Sm1.
2nπ) to (3π / 2 + 2nπ)], [(3π / 2 + 2
nπ) to (5π / 2 + 2nπ)].

The integrator 153 converts the output signal SM of the detector 152 into each phase interval [(π / 2 + 2nπ) to (3π / 2 +
2nπ)], [(3π / 2 + 2nπ) to (5π / 2 + 2
nπ)] to generate an integrated signal SI. The integrated signal SI is multiplied by β in the buffer amplifier 154, and the β multiplied signal β · SI is supplied to the voltmeter 155. The other terminal of the voltmeter 155 is grounded. Since the level of the integration signal SI is equal to the integration value In given by Expressions 9 and 10, the voltage value measured by the voltmeter 155 is a monotonic function of the capacitance C between the parallelism adjustment electrode 111 and the semiconductor wafer. The value is represented by

The signal Sc1 indicating the value measured by the voltmeter 155 is supplied to the position controller 26 (see FIG. 2), and is compared with the values measured by the other capacity meters 132 and 133, whereby the signal of the sensor head is obtained. Bottom and semiconductor wafer 1
The parallelism between 00 and 00 is adjusted.

As described above, the capacity meter 1 of this embodiment
31 integrates the applied signal Sa1 with reference to a predetermined phase section of the measurement signal Sm1 to obtain a capacitance C.
The value proportional to is calculated. As also shown in FIG.
The applied signal Sa1, which is a power signal, is a clean sine wave, whereas the measurement signal Sm1 has a distorted waveform including a noise component. Contrary to the above embodiment, the applied signal Sa
There is also a method of integrating the measurement signal Sm1 with reference to one phase section. However, in this method, the integrated value is easily affected by the noise component of the measurement signal Sm1. On the other hand, in the above embodiment, since the clean sine wave applied signal Sa1 is integrated, there is an advantage that the integrated value In is hardly affected by the noise of the measurement signal Sm1.

In the above-described capacitance meter, the electrode 202 as one electrode of the capacitance to be measured is grounded, and an application signal is applied to the parallelism adjusting electrode as the other electrode via the resistor R. In other words, if this capacitance meter is used, a measurement value depending on the capacitance value of the capacitance to be measured can be obtained in the single-ended mode, so that the measurement values depending on a plurality of capacitance values affect each other's measurement values. There is an advantage that measurement can be performed at the same time.

FIG. 25 is a graph showing the relationship between the inclination of the bottom surface of the sensor head and the capacitance Ce of each of the parallelism adjusting electrodes 111 to 113. The dimensions of the parallelism adjusting electrodes 111 to 113 shown in FIG. Inner diameter r0 = 0.08cm Outer diameter r1 = 0.12cm Gap between electrodes Δg = 0.07cm

The results of FIG. 25 (b) are obtained by calculating the capacitance of each electrode under the condition that the bottom surface of the sensor head is tilted about the axis α, as shown in FIG. 25 (a) and (c). is there. The axis α is a mirror-symmetric axis of the electrodes 112 and 113. When the bottom of the sensor head is tilted by the angle θ,
As shown in (c) of the figure, the surfaces of the electrodes 111 to 113 deviate from the positions parallel to the surface of the semiconductor wafer 100 (the positions indicated by broken lines in the figure). At this time, the electrodes 111 to 113
Is shifted from the parallel position by the distance △ d on the horizontal axis in FIG.

The capacitance C of the parallelism adjusting electrodes 111 to 113
e is measured using the capacity meters 131 to 133 of the impedance meter 24 as described above. It is relatively easy to make the accuracy of the capacitance measuring system including the impedance meter 24 and the host controller 28 approximately 0.1 pF. Assuming that the accuracy of the capacitance measuring system is 0.1 pF, FIG.
From FIG. 5 (b), it can be seen that the parallelism can be adjusted so that the distance Δd is 0.01 μm or less. When the distance Δd is 0.01 μm, the inclination angle θ of the bottom surface of the sensor head is about 0.0005 °, which is negligible.

FIG. 26 is a graph showing the relationship between the distance Δd and the capacitance Ce of each parallelism adjusting electrode when the sensor head is inclined about an axis β perpendicular to the axis α. Also in this case, as in the case of FIG. 25, if the accuracy of the capacitance measuring system is 0.1 pF, the distance Δd is 0.01 μm.
The parallelism can be adjusted as follows.

As described above, three electrodes for adjusting the degree of parallelism are provided on the bottom surface of the sensor head, and the capacitance is measured by applying a three-phase AC signal to them, so that the capacitance values are substantially equal to each other. By driving the three piezoelectric actuator units 44 to 46, it is possible to precisely adjust the parallelism between the bottom surface of the sensor head (that is, the surface of the measurement electrode 201) and the surface of the semiconductor wafer 100. At this time, it is not necessary to accurately determine the capacitance value of each parallelism adjusting electrode, and the piezoelectric actuator section may be controlled so that those values become equal to each other.

As described above, the parallelism adjusting electrodes 111 to 1
When a three-phase AC signal is applied to the electrode 13, the potential of the measurement electrode 201 is maintained at the same potential as the neutral point NP of the three-phase AC power supply. There is no disturbance to. Therefore, there is an advantage that electrical measurement such as CV measurement can be accurately performed while adjusting the parallelism.

In the above embodiment, since the neutral point NP of the three-phase AC power source and the electrode 202 on the back surface of the semiconductor wafer are both grounded, if the parallelism is maintained, the electrode 202 and the measuring electrode 201 are maintained. (That is, through the semiconductor wafer). This is also an advantage in performing accurate electrical measurement using the measurement electrode.

Further, since no current flows between the electrode 202 and the measuring electrode 201, when the conductive sample table 38 is used as the electrode 202, the gap between the back surface of the semiconductor wafer 100 and the sample table 38 The parallelism can be adjusted accurately without reducing the impedance. That is, the conductive sample table 3 can be used without paying much attention to the adhesion between the semiconductor wafer 100 and the sample table 38.
There is an advantage that 8 can be used as the electrode 202.

Since the capacitance meters 131 to 133 can measure in the single-end mode without using a bridge, the measurement values depending on the capacitance values of the plurality of parallelism adjusting electrodes are influenced by the mutual measurement values. There is an advantage that measurement can be performed without any problem. Further, since a measured value corresponding to the capacitance value is obtained by integrating the applied signals Sa1 to Sa3 in a predetermined phase section of the measured signals Sm1 to Sm3, the measured values are not affected by noise components of the measured signals Sm1 to Sm3. There is also an advantage that can be obtained.

As the parallelism adjusting electrodes, generally, N (N is an integer of 3 or more) electrodes having the same shape may be provided at symmetric positions with respect to the measuring electrodes. In this case, the AC applied signal applied to each electrode is a symmetric N-phase signal having the same frequency and electromotive force and different phases by 2π / N.

If there is no fear that the parallelism will be lost during the electrical measurement, N AC signals having no phase difference (ie, having the same phase) are applied to the N parallelism adjusting electrodes. Is also good. In this case, first, the parallelism is adjusted using the parallelism adjusting electrode, and electrical measurement is performed using the measuring electrode without applying a signal to the parallelism adjusting electrode while maintaining the parallelism. . However, if the symmetrical N-phase signal is used as described above, no disturbance is applied to the measurement electrode, and no current due to the applied signal for the parallelism adjustment flows through the semiconductor wafer. There is an advantage that the electrical measurement can be performed with high accuracy while adjusting the temperature.

When an AC signal having the same phase is applied to the parallelism adjusting electrode, if the shape of the measuring electrode and the shape of the parallelism adjusting electrode are made equal, the parallelism adjusting electrode can be used for measurement. Since it can be used as an electrode, one of the N parallelism adjusting electrodes can also be used as a measuring electrode.

The present invention is not limited to the above-described embodiment, but can be carried out in various modes without departing from the gist thereof. For example, the following modifications are possible. INDUSTRIAL APPLICABILITY The present invention is not limited to a sensor head for a CV measuring device, and can be generally applied to a sensor head used for a device for measuring electric characteristics between a measuring electrode and a semiconductor substrate in a non-contact manner. As another electrical measurement, for example, there is a method of evaluating the characteristics near the semiconductor surface by examining the time dependency of the combined capacitance Cta by the Zerubst method. If the conductance is measured by the impedance meter 24, it is also possible to evaluate the interface state at the interface between the semiconductor substrate 101 and the oxide film 102. Further, during the respective processes such as the cleaning process of the semiconductor substrate, the thermal oxidation process, and the heat treatment for stabilizing the oxide film, if the CV measurement is performed in a state where the oxide film is not formed on the semiconductor wafer, each of these processes is performed. The quality of the processing can be determined.

[0089]

As described above, according to the sensor for non-contact electric measurement of the present invention, the first and second sensors substantially parallel to each other are provided.
Since the translucent member having the surface described above is used, the electrode can be easily formed on the first surface by photolithography. Therefore, there is an effect that a sensor suitable for non-contact electric measurement can be easily manufactured. Also, connect the electrodes
So that it is arranged in the electrode groove provided on the first surface.
Between the reflective surface of the translucent member and the semiconductor wafer.
The gap between them can be smaller, resulting in
The effect that the accuracy of gap measurement can be improved
There is fruit. In addition, make sure that the electrode contacts the semiconductor wafer.
Prevent electrode breakage as it can be prevented
There is an effect that can be.

[0090] translucent member provided conical surface, if so as to form an electrical wire to this conical surface, the outside of the lead wire and the electric wiring of the sensor at the position farther from the semiconductor wafer than the reflecting surface of the laser beam Can be connected. Therefore, for example, even when the connection is made with silver paste, there is an effect that there is no fear that the swelling of the connection portion is caught in the gap between the reflection surface and the semiconductor wafer.

Further, on the first surface, there are provided N (N is an integer of 3 or more) parallelism adjusting electrodes having the same shape and provided at symmetrical positions with respect to the electric measurement electrode. With this configuration, the parallelism between the first surface and the semiconductor wafer can be adjusted by adjusting the inclination of the first surface of the sensor so that the capacitances of the N parallelism adjusting electrodes are equal to each other. There is an effect that can be.

A peripheral surface of the first surface is provided with a wiring forming surface formed in a step shape at a position substantially parallel to the first surface and closer to the second surface than the first surface. If the electric wiring connected to the electric measurement electrode is formed on the wiring forming surface, the value of the parasitic capacitance generated between the wiring forming surface and the semiconductor wafer can be reduced.

As described above, the parasitic capacitance can be reduced.
Can improve the accuracy of electrical measurements.
There is fruit.

Further, if the laser light guide means for introducing the laser light into the light transmitting member and emitting the laser light reflected by the reflection surface to the outside of the light transmitting member is provided, There is an effect that laser light can be easily introduced into the translucent member.

If a guard ring electrode to which a predetermined potential is applied is formed between the electric measurement electrode and the parallelism adjustment electrode, mutual interference of a plurality of electrodes can be reduced. Thus, there is an effect that the parallelism adjustment and the accuracy of electric measurement can be improved. Sa
Further, the surface of the electrode for electrical measurement and the first surface
If they are made to coincide with each other, the resistance of the first surface during electric measurement can be reduced.
It is not necessary to consider the step between the launch surface and the electrode for electrical measurement
This has the effect.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an outline of a method for measuring electricity of a semiconductor.

FIG. 2 is a diagram showing a configuration of an electricity measuring device as one embodiment of the present invention.

FIG. 3 is a diagram showing a bottom surface of an electrode forming portion and a BB cross section thereof.

FIG. 4 is a front view showing a connection state of wiring of a sensor head.

FIG. 5 is an explanatory view schematically showing a shape of an electrode forming portion having a flat bottom surface, and a non-measurement capacitance and a parasitic capacitance.

FIG. 6 shows the shape of an electrode forming portion having a stepped bottom surface,
FIG. 3 is an explanatory diagram schematically showing a non-measurement capacitance and a parasitic capacitance.

FIG. 7 is a graph showing the resolution of gap measurement.

FIG. 8 is a sectional view showing an electrode forming portion having a stepped bottom surface.

FIG. 9 is a cross-sectional view illustrating an electrode forming portion having a structure in which an electrode pattern is embedded in a bottom surface.

FIG. 10 is a cross-sectional view showing an electrode forming portion having a structure in which an electrode pattern is buried deeper than a reflection surface.

FIG. 11 is a sectional view showing a manufacturing process of the cone glass.

FIG. 12 is a sectional view showing a main step of forming an electrode pattern on the bottom surface of the cone glass.

FIG. 13 is a plan view showing a resist pattern 704 used for forming an electrode pattern.

FIG. 14 is a sectional view showing another configuration of the sensor head.

FIG. 15 is a sectional view showing still another configuration of the sensor head.

FIG. 16 is a sectional view showing another configuration of the sensor head.

FIG. 17 is a diagram showing a connector configuration of a sensor head.

FIG. 18 is an explanatory diagram showing an equivalent circuit between electrodes.

FIG. 19 is a diagram showing a basic connection relationship between an AC power supply and a parallelism adjusting electrode.

FIG. 20 is a diagram showing a connection relationship between an AC power supply, a parallelism adjusting electrode, and a capacitance meter.

FIG. 21 is an explanatory diagram showing an equivalent circuit between an AC power supply, a resistance and parallelism adjustment electrode, and an electrode of a semiconductor wafer.

FIG. 22 is a graph showing a relationship between an integral value and a measured capacity in a capacity meter.

FIG. 23 is a block diagram showing the internal configuration of a capacity meter.

FIG. 24 is a timing chart showing main signals in the capacity meter.

FIG. 25 is a graph showing the relationship between the inclination of the bottom surface of the prism and the capacitance of the parallelism adjusting electrode.

FIG. 26 is a graph showing the relationship between the inclination of a prism and the capacitance of each parallelism adjusting electrode.

[Explanation of symbols]

 Reference Signs List 20 measuring unit 22 light quantity measuring device 24 impedance meter 26 position control device 28 host controller 32 base 34 driving device 34a ball screw unit 36 mount 38 sample table 40 housing 42 flanges 44 to 46 piezoelectric actuator unit 50 support plate 60 sensor head 62 right angle prism 64 Electrode forming part 66 Cone glass 66a Bottom surface 66b Side slope 66c Reflecting surface 70 Laser oscillator 72 Light receiving sensor 100 Semiconductor wafer 101 Semiconductor substrate 102 Oxide film 103 Depletion layer 111-113 Parallelism adjusting electrode 116 Lead wire 120 Guard ring 130 AC power supply 131 To 133 Capacity meter 151 Buffer amplifier 152 Detector 153 Integrator 154 Buffer amplifier 155 Voltmeter 200 Electrode pattern 201 Electrode for electrode 202 Electrode 300 electrode holding unit 400 measuring section 500 electrode forming section 502 cone glass 510 electrode forming section 512 cone glass 520 electrode forming section 521 disc-shaped glass 522 cone glass 530 sensor head 532 right-angle prism 534 holder 540 sensor head 542 right-angle prism 544 electrode Forming part 550 Sensor head 552 Right angle prism 554 Electrode forming part 556 Through hole 560 Sensor head 562 Right angle prism 564 Electrode forming part 566 Through hole 702 Resist 704 Resist pattern 706 Metal Cg Capacitance to be measured Cp Parasitic capacity Ge Gap L Laser light MD Electrical measurement apparatus

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-132236 (JP, A) JP-A-4-32704 (JP, A) JP-A-63-111403 (JP, A) (58) Survey Field (Int.Cl. ⁶ , DB name) H01L 21/66 G01N 27/00

Claims (7)

(57) [Claims] A reflecting surface that is held substantially parallel to a surface of a semiconductor wafer with a gap therebetween, and the gap is measured based on an intensity of a laser beam reflected by the reflecting surface; A non-contact electric measurement sensor for measuring electric characteristics of the semiconductor wafer, comprising: a first surface including the reflection surface; and a substantially parallel second surface facing the first surface. A light-transmitting member; and an electrode for electric measurement formed on the first surface, wherein the second surface includes an incident surface of the laser light to the light-transmitting member, and the electrode for electric measurement. Wherein the surface of the electrode for electric measurement is arranged in a groove for an electrode provided on the first surface without protruding from the first surface. For sensors. 2. The sensor for non-contact electricity measurement according to claim 1, wherein the light-transmitting member has a conical surface extending from a vicinity of a periphery of the first surface toward the second surface. and, in the conical surface, the non-contact electrical measurement sensor electric wires connected to the test electrode is formed. 3. The sensor for non-contact electric measurement according to claim 1, wherein a degree of parallelism between the first surface and the semiconductor wafer is adjusted.
For this reason, the first surface is provided with N (N is an integer of 3 or more) parallelism adjusting electrodes having the same shape and provided at symmetrical positions with respect to the electrode for electric measurement. Sensor for contact electricity measurement. 4. The non-contact electricity measurement sensor according to claim 1, wherein the light-transmissive member is provided at a peripheral portion of the first surface and substantially adjacent to the first surface. A wiring forming surface which is formed in a stepped manner in a position parallel to and closer to the second surface than the first surface;
A non-contact electric measurement sensor in which electric wiring connected to the electric measurement electrode is formed on the wiring forming surface. 5. A non-contact electrical measurement sensor according to any one of claims 1 to 4, further with introducing the laser light into the translucent member from said second surface, said reflective A non-contact electrical measurement sensor including an optical waveguide unit that emits the laser beam reflected by a surface from the second surface to the outside of the translucent member. 6. A non-contact electrical measurement sensor according to any one of claims 1 to 5, further between the parallelism adjustment electrode and the test electrode,
A non-contact electric measurement sensor having a guard ring electrode to which a predetermined potential is applied. 7. The non-volatile memory according to claim 1, wherein
A sensor for measuring contact electricity, further comprising: matching a surface of the electrode for electricity measurement with the first surface.
Sensor for non-contact electrical measurement.