JPH0666368B2 - Semiconductor evaluation equipment - Google Patents

Description

The present invention relates to a semiconductor evaluation apparatus, and more particularly to an evaluation apparatus improved so that various kinds of information can be obtained without destroying a semiconductor wafer to be evaluated.

[Prior Art] To know various basic constants unique to a semiconductor, such as carrier lifetime, carrier mobility, and surface recombination velocity of the semiconductor, the characteristics of various devices formed thereon are determined by these. Therefore, it is extremely important.

Of course, it is possible to obtain these various basic constants by measuring the characteristics of the device after making some kind of device. It is a great advantage if we can know the basic constants in advance.

Therefore, conventionally, some methods and devices have been proposed for this kind of semiconductor evaluation.

The most basic or primitive method is to use a part of the semiconductor wafer to be evaluated, actually create a transistor or diode for evaluation, and evaluate the semiconductor wafer by measuring its characteristics. Is the way.

On the other hand, there are well-known four-point probe method and spread resistance method as methods for evaluating the semiconductor wafer itself with a special evaluation device. In these methods, usually, high hardness conductive materials such as tungsten and tungsten carbide are used. The needle is used as an electrode structure or a probe structure, but in some cases, a conductive liquid such as mercury is used as the probe.

Furthermore, as disclosed in Japanese Patent Laid-Open No. 59-181549, a semiconductor wafer is irradiated with a single optical pulse having an energy equal to or more than a band gap, and a recombination decay curve of excited minority carriers is detected. There is also a method of measuring the life of the minority carrier. This method also detects the reflection signal of the microwave radiated to the back surface of the semiconductor wafer as a signal for expressing the recombination decay curve, and reduces the surface recombination velocity S on the semiconductor wafer. Bias light is also applied to the semiconductor wafer.

[Problems to be Solved by the Invention] However, among the above-mentioned conventional methods, the method for producing a sample device dedicated to evaluation is too direct, and it is not a burr that requires labor or the like for producing such a device. The basic constants of semiconductors may even change by themselves, which makes it unclear what to evaluate. First, it is fatal that the evaluation cannot be performed in the state of the wafer in which the device is to be formed.

On the other hand, although the four-point probe method in which the tip of a conductive needle is pressed against a semiconductor wafer has the advantage that it can be evaluated in the state of the semiconductor wafer, it is actually a sharp and extremely hard needle. Since the tip is pressed against the wafer surface, the wafer cannot be scratched, and in general, such a destructive evaluation method is not desirable in most cases. However, it was accumulated in several areas such as resistivity measurement at best.

However, as described above, if mercury is used as a conductive probe to perform a measurement similar to the four-point probe method, there is no possibility of physically damaging the semiconductor wafer itself. Although the measurement of the electric capacity becomes relatively easy, the number of types of measurement cannot be denied.

On the other hand, in the method disclosed in the above-mentioned JP-A-59-181549, it is not necessary to provide a physical electrode structure for extracting the evaluation signal, but due to the measurement principle, irradiation with a single light pulse is used. Pulsed conductance decay (carrier recombination decay curve) is observed. As a matter of fact, the carrier lifetime changes every moment depending on the number of carriers, but with this measuring method, since the number of carriers just decreases every moment, an accurate value cannot be obtained. Moreover, it is difficult to obtain a sufficient signal-to-noise ratio (S / N), and it is difficult to obtain high measurement resolution. Further, even if an attempt is made to reduce the carrier recombination rate on the surface of the semiconductor wafer by the bias light, it is impossible in principle to make the bias light intensity higher than the light intensity of the single-shot measurement optical pulse, and there is an application limit.

Furthermore, even from a device perspective, since the evaluation signal is extracted as a reflected signal of microwaves, the generation and introduction of microwaves,
Detection of reflected waves requires expensive and complicated electronic devices.

From this point of view, the present invention can non-destructively evaluate a semiconductor, for example, as a wafer, depending on how it is used.
There are many types of measurable basic constants, the electric signal strength for evaluation is high (S / N is good), and the required value can be obtained with higher accuracy even with a relatively simple device system. Is intended to be provided.

[Means for Solving Problems] In order to achieve the above-mentioned object, the present invention is mainly applied to an object to be inspected in which a semiconductor surface is exposed or a film made of a material different from the semiconductor is formed on the semiconductor surface. At least two locations on the surface are electrically contacted with at least one pair of conductive liquids as a measurement probe, and then at least one location of the subject is not a single pulsed light but an intensity having a predetermined frequency. Irradiate modulated light. Then, the semiconductor is evaluated by measuring an evaluation electric signal obtained through the at least one pair of conductive liquids and having a frequency dependent on the frequency of the intensity-modulated light.

[Operation and Effect] When the semiconductor evaluation device of the present invention is used, the evaluation electric signal obtained through the conductive liquid as the measurement probe depends on the frequency of the intensity-modulated light with which the subject is irradiated for measurement. It becomes an electric signal of the specified frequency. Therefore, it is possible to deal with the dependency on the frequency of the intensity-modulated light without paying attention to only the intensity such as only the voltage value or the current value. Even when handling in strength, it is possible to improve accuracy by repeated measurement.
Therefore, in any case, the electrical signal taken out for the measurement has a high S / N in the first place, or has an effective high S.
/ N, and the accuracy of the measurement result is improved.

Further, since the signal for measurement is taken out as an electric signal through the conductive liquid, the device system itself is relatively simple even for nondestructive measurement. Even so, since it has advanced considerably, errors in the measurement system and deterioration of S / N are good and can be prevented.

[Example] According to the evaluation device of the present invention, it will be described later what kind of basic constant group can be measured, and for the time being,
An example of a static configuration as a device that can be used for various measurements will be described with reference to some examples.

First, FIG. 1 schematically shows a first embodiment which seems to be the most basic embodiment of the semiconductor evaluation apparatus of the present invention.

On one main surface of the subject 10, which may be the semiconductor wafer 11 itself, two places 30 and 31 with an appropriate separation distance,
The conductive liquids 20, 21 enclosed and guided in suitable guiding or enclosing means 22, 23 are in contact. Conductive liquid
20 and 21 may be mercury, Ga / In alloy, or an appropriate ionic solution, or the like, as long as they can be in a liquid phase at least at the ambient temperature at the time of measurement or the intentional heating temperature. However, when carrying out various evaluation methods using the device of the present invention, the material may be specified on a case-by-case basis for the reason necessary for the method, and particularly when using various ionic solutions, Due to the restrictions on the frequency response characteristics, there are cases where the liquid quality that can be used is limited.

Although not shown, the other ends of the conductive liquids 20 and 21 can be appropriately connected to an electric bias source or a measuring device at the time of measurement, which will be described later.

On the other hand, on the main surface of the subject 10, the intensity-modulated light 40 guided by the optical fiber 50 which is schematically shown in the illustrated embodiment is locally minute between the pair of contact portions 30 and 31. It is incident on a part.

The intensity-modulated light referred to in the present invention is a general term for those whose intensity changes intentionally or in a known manner in accordance with a predetermined frequency on the time axis, and therefore, is typically a known constant frequency or a known method. A sine waveform or a repetitive pulse waveform train that is frequency-modulated by is considered. In other words, single light pulses and the like are excluded. Actually, as the intensity-modulated light, a constant intensity output light from a light-emitting diode or a laser diode driven by direct current, a halogen lamp, a xenon lamp, or the like is chopped by a chopper or passed through a modulator, and is particularly high in intensity. In the case of a color light source, it is often convenient to use it as monochromatic light through a spectroscope if necessary. If the light emitting diode or the laser diode is pulse-driven or AC-driven, it has a frequency corresponding to the frequency of the pulse power source or the AC power source,
Since the light intensity-modulated can be obtained, this can also be used appropriately.

Thus, as a method of introducing the intensity-modulated light, as shown in the embodiment of FIG.
There is also a method in which the sheet 60 is used as a waveguide and the edge portion is subjected to a reflection process, and the intensity-modulated light 40 inserted into the plastic sheet 60 is irradiated from the reflection surface 70 to the semiconductor wafer 11 or the subject 10.

Furthermore, a base member or a supporting member (not shown) on which the subject 10 is placed is a light-transmissive plate-like member, and the modulated light is incident from the side end face thereof, and the modulated light is reflected to cause the subject 10 to move. In order to irradiate a predetermined portion, a reflection surface similar to the reflection surface 70 shown in FIG.
The plate-shaped support member may be cut or embedded. This method is also simple and can be adopted for introducing bias light described later.

Not limited to this case, the analyte support member (not shown) naturally needs a through hole through which the conductive liquid guides 22 and 23 are inserted. Further, although the example of the optical fiber is given as the optical waveguide in the first illustrated embodiment, a low-quality optical waveguide made of plastic and called a so-called optical rod can be guided by this type of device system. The distance is short,
The loss can be used in the same way, since it is less of a problem.

Further, as shown in FIG. 3, one of the pair of conductive liquid guides 22, 23 is a conductive liquid guide, for example, a guide.
It is also possible to pass the optical fiber 51 through the inside of the guide 22 and irradiate the contact portion 31 itself between the conductive liquid 21 inside the guide 22 and the surface of the subject 10 with the intensity modulated light 40 of a predetermined frequency. The intensity-modulated light 40 can also be incident on the subject 10 on the main surface opposite to the side where the conductive liquids 20 and 21 are in contact. This pattern is shown in FIGS. However, in these examples, the intensity-modulated light 40 sandwiches the subject 10 and is incident on a position corresponding to the contact portion 31 of one of the conductive liquids 21 although it is from the opposite side. Is shown. However, as described above, this may be applied to an appropriate place with an appropriate irradiation area (spot diameter).

On the other hand, FIGS. 3, 5 and 6 also show some forms of applying bias light from an appropriate bias source (not shown) as preferred embodiments.

Such bias light cannot obtain good ohmic contact between the conductive liquid contact portions 30 and 31 and the subject 10 (or the semiconductor 11), as seen in each measurement example described later, and rather, Although a Schottky junction or an electrical barrier similar to this is formed, a low contact resistance equivalent to ohmic contact is required for at least one or both contact portions for the convenience of measurement, or the carrier is It is used to reasonably meet these requirements when it is desired to mitigate the effects of being trapped in the semiconductor 11.

In order to ensure particularly low resistance, the photocurrent generated by the bias light is adjusted so that the photocurrent generated by the bias light is substantially sufficient to reduce the contact resistance between the conductive liquid and the subject. It is only necessary to select the intensity, and in terms of frequency, it is possible to use AC light having a frequency different from that of the intensity modulated light 40 and having the same phase.

Further, this bias light is emitted from the conventional publication mentioned above:
Unlike the bias light in the method disclosed in JP-A-59-181549, it is not irradiated to reduce the surface recombination velocity of a semiconductor wafer, and is not irradiated together with a single light pulse. In principle, the intensity-modulated light intensity of 1 can have independent intensities, and its variable range can be set wider in practice than the method disclosed in the conventional publication.

Even in the method of applying the bias light, in the third embodiment, the bias light 80 uniformly irradiates the surface of the subject 10 opposite to the surface on which the intensity modulated light 40 is incident. However, as shown in the fifth embodiment, two bias lights (81, 82) are used and the contact parts 30, 31 are respectively formed.
It is also possible to irradiate locally on one side, and depending on the measurement, as shown in FIG.
It is also possible to irradiate the bias light 81 only to.

Furthermore, it is obvious that the contact portions 30 and 31 are not limited to the indirect irradiation with the subject 10 sandwiched as shown in the figure, but may be replaced with direct irradiation. As I mentioned earlier,
In the same way that the intensity-modulated light is guided by the optical fiber 51 passing through the liquid guide 22 in FIG. 3, this bias light can also be introduced in this way, and is shown in FIGS. As described above, through the light guide means such as an optical fiber or a plastic sheet, the contact portion is mechanically indirect but not incident to the contact portion itself, so that the contact portion is substantially irradiated by being incident in the vicinity thereof. It may be.

Further, in FIG. 7, not only the object 10 is the semiconductor 1 but
High resistance film intentionally or unintentionally formed on the surface
It is also shown that it contains 12 mag. The intentionally or unintentionally formed high resistance film 12 may include a silicon oxide film, mylar, etc., and in a special case, an air layer etc. may be included. However, as will be described later, the evaluation device of the present invention can effectively function for grasping some basic constants thereof.

In the above, first, various examples of the evaluation apparatus of the present invention were shown in its static configuration. Next, a usage example of the apparatus of the present invention, that is, a method of measuring various basic constants will be described.

First of all, according to the device of the present invention, the dynamic behavior of carriers generated by time-varying generation of intensity-modulated light locally or uniformly irradiating the subject surface is non-destructive. Can be measured. For example, now, any one of the configurations shown in the first to sixth embodiments shown as the embodiment of the evaluation apparatus of the present invention is selected, and the contact portion 30 between the conductive liquids 20 and 21 and the semiconductor 11 as the subject 10 itself is selected. , 31, ohmic contact is obtained, or the bias light 80, 81, 82 described above is obtained.
Sufficiently low resistance contact is obtained by the selective use of Under these circumstances, the following measurements are possible.

Between the pair of contact portions 30, 31 in which the conductive liquids 20, 21 made of mercury or the like are in contact with the semiconductor 11 as the subject 10, the conductive liquids 20, 20 are supplied from a voltage bias source (not shown).
A voltage sufficient to generate an electron-hole pair in the semiconductor 11 with respect to the semiconductor 11 after applying an electric field E by applying a DC or pulse voltage via 21. When the intensity-modulated light 40 is repeatedly irradiated in a pulsed manner at a predetermined frequency, the carriers generated thereby diffuse the carrier at a speed proportional to the applied electric field E and the carrier mobility μ, and move between the pair of contact portions 30, 31. Flowing.

Therefore, the distance x _m between the contact portion 31 on one side and the incident position of the intensity-modulated light 40, and the electric signal obtained between the intensity-modulated light 40 and the pair of contact portions 30, 31 (converted voltage via current or resistance). delay from the time _{t d} of), based on _{x m = μ · E · t} d ...... becomes equation may determine the carrier mobility mu. This is famous as an experiment of highness shock ray, but since the apparatus of the present invention further performs this for each repetitive pulse of a predetermined frequency, it can be obtained with high accuracy.

Similarly, a pair of conductive liquids 20 and 21 or a pair of contact portions 3
When the intensity-modulated light 40 having a frequency is applied to an appropriate place between the two contact portions 30 and 31 while the voltage V is applied between 0 and 31, a voltage change ΔV or a current obtained between the contact portions 30 and 31 is obtained. The change ΔI changes depending on the frequency of the intensity modulated light 40, and a phase difference ΔP occurs between the voltage change ΔV or the current change ΔI of the intensity modulated light 40. However, this change amount Δ
From the dependence of V and ΔP on the intensity-modulated optical frequency, Δ
Frequency _a that is -3 dB lower than when V is low frequency,
Alternatively, the effective carrier life can be obtained as 1 / (2π _a ) or 1 / (2π _p ) by obtaining the frequency _{p at} which the phase difference ΔP becomes π / 4. It can be seen that it can also be used for nondestructively and simply and accurately calculating the carrier lifetime.

Furthermore, when the wavelength (frequency) of the intensity-modulated light 40 is changed, the voltage change ΔV or the current change ΔI between the two contact portions 30 and 31 accompanying it changes according to the absorption coefficient α of the intensity-modulated light. If it stands, it becomes like the following formula.

However, in the above formula, τ is the carrier lifetime, D is the carrier diffusion coefficient, L is the carrier diffusion distance, S is the surface recombination velocity, and α is
Is the absorption coefficient of light, and C is a constant.

Therefore, the wavelength (frequency) of the intensity-modulated light is changed,
If the absorption coefficient α is changed by this and the relationship between ΔV and 1 / α is taken, as clearly shown in FIG. 8, the tangent line at the portion where 1 / α is small is extrapolated to the 1 / α axis. Is -D
/ S is given and 1 / α of the point where a straight line passing through the intersection of this tangent and the ΔV axis and having a slope half that of the tangent intersects the characteristic curve
The coordinates give L.

However, Since the above relationship is already known, the carrier diffusion coefficient D can be known from the value τ and the formula that can be known as described above, and the surface recombination velocity S is already known τ, It can be easily calculated from L and D / S.

In this way, it is understood that by using the evaluation device of the present invention, an extremely large amount of information can be obtained easily and nondestructively regarding each basic constant of the semiconductor depending on how it is used.

When obtaining the carrier mobility, carrier lifetime, carrier diffusion distance or diffusion coefficient, surface recombination velocity, etc. of the semiconductor as described above, the intensity-modulated light 40 with which the semiconductor is irradiated has the light intensity Although it is required to have energy equal to or greater than the forbidden band width, conversely, if the intensity-modulated light 40 having an energy equal to or less than the energy corresponding to the forbidden band width of the semiconductor is used, the forbidden band gap, etc. It is also possible to evaluate the posture of the obi.

By the way, in the above, any one of the constitutions of the first to sixth drawings shown as the embodiment of the evaluation apparatus of the present invention is selected, and the contact portion 3 between the conductive liquids 20 and 21 and the subject 10 or the semiconductor 11 is selected.
Various measurement examples in the case where an ohmic contact is obtained at 0, 31 or a sufficiently low resistance contact is obtained by selectively using the bias light 80, 81, 82 described above are described. On the contrary, the contact portions 30 and 31 between the surface of the subject 10 or the semiconductor 11 and the conductive liquids 20 and 21 are not ohmic contacts, but are Schottky barriers or barriers equivalent thereto and have photosensitivity. Even in the case where the electrical barrier having the above is formed, the evaluation device of the present invention can effectively utilize by effectively utilizing the barrier with at least one contact portion being formed.

For example, when the intensity-modulated light 40 is applied to a place where the Schottky barrier is formed on the contact portions 30 and 31, an open circuit voltage is induced like the solar cell. Therefore, one contact part,
For example, the carrier life can be obtained by measuring the dependence of the electric signal obtained on the contact portion 31 on the intensity-modulated optical frequency. At this time, the other contact portion 30 can be irradiated with the bias light 81 according to the configuration shown in FIG. 6 to have a substantially low contact resistance.

Regarding this measuring method, one experimental example is given below.
The structure of the experimental apparatus is basically the same as the structure shown in FIG. 6, and an n-type, (100) surface, 2 Ω-cm Si wafer is used as the object 10, and mercury is used as the conductive liquids 20 and 21. Using.
However, unlike FIG. 6, both conductive liquid contact parts 30, 31
Bias light 81 from a halogen lamp was applied to the entire wafer including the above.

FIG. 9 shows the experimental results, and FIG. 9 (A) shows the current-voltage (IV) characteristic between the ohmic contact 90 and the mercury contact provided on the opposite side of the subject for reference. When there is no bias light 81, the characteristic is when the bias light 81 is irradiated. As seen in these characteristic diagrams, a Schottky barrier is formed on the wafer surface at the contact portion, and the so-called solar cell characteristic is shown by the bias light 81.

On the other hand, FIG. 9 (B) shows an IV characteristic between the mercury contact portions 30 and 31. In this case, the Schottky barriers formed on both mercury contact parts 30 and 31 are connected together in series in the opposite direction, so that almost no current flows in the absence of bias light. So high resistance. Even if one of the mercury contact portions is irradiated with the modulated light 40 in this state, the open circuit voltage Vo is high because the time response is high resistance.
The carrier life cannot be obtained from the transient response of c. On the other hand, when bias light is applied in accordance with the gist of the present invention, a sufficiently low resistance characteristic is obtained as shown by the characteristic in FIG. 9 (B), and in this state, only one mercury contact portion, When the intensity-modulated light 40 having a frequency is irradiated, the carrier life can be obtained from the frequency characteristic of the open circuit voltage Voc at that time.

A pulse-driven GaAs light emitting diode (center wavelength: 925 nm) was used for the modulated light. The transient response is as shown in FIG. 10 per one pulse, and the carrier lifetime obtained from this is about 8 μsec. From the above, it can be seen that according to the present invention, the carrier lifetime, which is one of the main semiconductor constants, can be evaluated easily without breaking the wafer as it is.

Further, as shown in FIG. 7, the surface of the subject 10 on which the contact portions 30 and 31 are formed is not the surface of the exposed semiconductor 11 but is formed intentionally or unintentionally on the semiconductor surface. The evaluation device shown in the drawing is also applicable to the case where the surface of the high-resistance film 12 such as a silicon oxide film or mylar, and optionally an air layer. For example, first, the conductive liquid 21
When a suitable voltage is applied to the contact portions 30 and 31 via the, the one is biased in the forward direction and the other is biased in the reverse direction through the high resistance film 12. At this time, if the voltage is applied in a stepwise manner, the majority of the carriers biased in the forward direction immediately respond and the semiconductor surface in the vicinity thereof is in the accumulation state of the majority carriers, but in the opposite direction. In the biased case, the minority carriers cannot immediately follow the voltage immediately after the application of the voltage, so that the depletion layer spreads deeply from the surface of the semiconductor 11 to the inside of the semiconductor, and then, with a certain time constant, it is thermally The generated minority carriers are collected on the surface of the semiconductor, the width of the depletion layer is reduced in the process, and finally a thermal equilibrium state is reached to form an inversion layer.

Therefore, by measuring the time change of the depletion layer width, in other words, the time change of the capacitance, the time constant of generation of minority carriers in the semiconductor, that is, the carrier generation life can be obtained. Although only this measurement method has been well known in the conventional MOS structure, the following measurement can be performed by using light irradiation in accordance with the gist of the present invention.

That is, while the above-described method measures the transient response due to the thermally generated minority carriers, the minority carriers can also be generated by light irradiation. When the depletion layer and the semiconductor in the vicinity of the depletion layer are irradiated with light having an energy higher than the band gap of the semiconductor, electron-hole pairs are generated, and the minority carriers are the thermally-generated minority. Like the carriers, they are collected on the semiconductor surface. On the other hand, by changing the wavelength (frequency) of the irradiation light,
The distribution of carriers generated in the semiconductor can be changed. For example, if relatively long-wavelength light is used, carriers can be generated at a position deeper inside the semiconductor. Some of the minority carriers generated near the depletion layer reach the end of the depletion layer by diffusion and are collected on the semiconductor surface. The diffusion of the carriers is determined by the carrier diffusion length L or the carrier diffusion constant D. Therefore, conversely, when the wavelength of the irradiation light is changed and the time change of the capacitance or the photocurrent is repeatedly measured, the carrier diffusion length L or the carrier diffusion constant D can be evaluated with high accuracy.

Even when the semiconductor surface has the high-resistance film 12, when the intensity-modulated light having a frequency (with bias light if necessary) is irradiated, electrons generated on the semiconductor surface when the semiconductor surface is in a depleted or inverted state are generated. The charge distribution changes due to the hole pairs, and as a result, the surface potential changes. This means that an alternating voltage change or current change appears due to the intensity-modulated light frequency. Therefore, similarly to the case where the semiconductor and the conductive liquid are in contact with each other by the Schottky junction, the carrier lifetime can be obtained by measuring the dependency of this voltage or current on the intensity-modulated optical frequency. When the high-resistance film 12 is on the semiconductor surface, the minority carriers do not flow into the conductive liquid, so that there is an advantage that the influence on the semiconductor surface is reduced.

Furthermore, in the case of a high-resistance semiconductor, the resistance can be substantially lowered by irradiating the entire surface with bias light. It is also possible to obtain the carrier lifetime from the phase difference by measuring the AC modulated photoconductivity depending on the.

As described above, even when the high resistance film 12 is formed intentionally or unintentionally on the surface of the semiconductor 11, the evaluation apparatus of the present invention enables various measurements. On the contrary,
The fact that an electric field can be applied to the semiconductor surface via the high-resistance film 12 means that it is possible to evaluate the surface recombination rate and the like with respect to the change in the surface electric field by intentionally changing the electric field. Further, as described in the summary configuration, even if the film formed on the semiconductor surface and different from the semiconductor is not the high resistance film 12, but a film made of another material, it is inferred from the above-mentioned place. The evaluation device of the present invention can be effectively applied.

Although several measurement examples using the semiconductor evaluation device according to the present invention have been described above, the present invention device can be applied in various ways other than the above, and the number of contact portions with the conductive liquid can be increased. Measurement is also possible. In this case, for example, with the tool of intensity-modulated light having a frequency added by the device of the present invention, not only the one-point measurement of the various basic constants described above but also the local constant even in the same semiconductor wafer is measured. It is also possible to two-dimensionally evaluate various basic constants that may differ from each other.

[Brief description of drawings]

1 to 7 are schematic configuration diagrams of respective embodiments of a semiconductor evaluation device according to the present invention, and FIG. 8 is a diagram showing a case where a specific constant group is obtained from experimental values by using the embodiment device of the present invention. Explanatory diagram, FIG. 9 is a characteristic diagram of current-voltage characteristics obtained in a Schottky barrier having photosensitivity and current-voltage characteristics obtained between a pair of mercury as a pair of conductive liquids, and FIG. FIG. 5 is an explanatory diagram of an experiment for obtaining the carrier lifetime of a semiconductor by using the apparatus of the embodiment of the present invention. In the figure, 10 is a subject, 11 is a semiconductor, 20 and 21 are conductive liquids,
Reference numerals 22 and 23 are guides for the conductive liquid, 30 and 31 are contact portions between the conductive liquid and the subject, 40 is intensity-modulated light, and 80, 81, and 82 are bias lights.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-181549 (JP, A) JP-A-60-103636 (JP, A) JP-A-62-131531 (JP, A) JP-A-62- 43551 (JP, A) Actually opened 56-61462 (JP, U) Actually opened 61-156237 (JP, U)

Claims (6)

[Claims] 1. A semiconductor surface is exposed, or at least two different locations on a main surface of a subject on which a film made of a material different from the semiconductor is formed on the surface of the semiconductor are electrically connected to each other. At least one pair of conductive liquids; and an irradiation device for irradiating at least one portion of the subject with intensity-modulated light of a predetermined frequency; and the intensity modulation obtained through the at least one pair of conductive liquids. An apparatus for evaluating the semiconductor by measuring an evaluation electric signal having a frequency dependent on an optical frequency, and a semiconductor evaluation apparatus comprising: 2. The semiconductor evaluation device according to claim 1, wherein an electrical barrier having photosensitivity is formed at the electrical contact portion between the subject and the conductive liquid; The evaluation electric signal is a signal obtained by modulating the electric signal obtained in the electric barrier with the frequency of the intensity-modulated light; 3. The semiconductor evaluation device according to claim 1, wherein an electrical barrier having photosensitivity is formed at the electrical contact portion between the subject and the conductive liquid. The intensity-modulated light effectively lowers the contact resistance of the contact portion by causing a photocurrent to flow through the electrical barrier.
Irradiating the electrical contact portion on which the electrical barrier is formed; 4. The semiconductor evaluation device according to claim 1, wherein an electrical barrier having photosensitivity is formed at the electrical contact portion between the subject and the conductive liquid. Irradiating the electrical contact portion on which the electrical barrier is formed with bias light that effectively reduces the contact resistance of the electrical contact by causing a photocurrent to flow through the electrical barrier; Characteristic semiconductor evaluation device. 5. The semiconductor evaluation device according to claim 1, wherein an electrical barrier having photosensitivity is provided at each of the electrical contact portions of the subject and the at least one pair of conductive liquids. A pair of electric contact portions each having the electric barrier formed therein, and a photocurrent is caused to flow through the electric barrier of one of the electric contact portions to effectively increase the contact resistance of the contact portion. In order to reduce the resistance of the other contact portion, the intensity-modulated light is applied to the one contact portion, and a photocurrent is caused to flow to the other contact portion against the electrical barrier of the other contact portion Irradiating with bias light that effectively lowers the contact resistance of the semiconductor evaluation device. 6. The semiconductor evaluation device according to claim 1, wherein an electrical barrier having photosensitivity is provided at each of the electrical contact portions of the subject and the at least one pair of conductive liquids. The electric signal for evaluation is an electric signal obtained by irradiating one of the pair of electric barriers with the intensity-modulated light. While being modulated by the frequency of the intensity-modulated light; a photocurrent is caused to flow through each of the electrical contacts of the pair of contact portions to generate a photocurrent. Irradiating with bias light that effectively lowers the contact resistance.