KR20030087677A - Method and apparatus for measuring resistance of semiconductor film - Google Patents

Abstract

PURPOSE: A method for measuring the resistance of a semiconductor thin film and a resistance measuring apparatus of the semiconductor thin film using the same are provided to be capable of easily measuring the resistance of the semiconductor thin film by generating photoelectric current at the semiconductor thin film. CONSTITUTION: Photoelectric current is generated at a semiconductor thin film sample by irradiating measuring light at the semiconductor thin film sample. Measuring current is applied to the predetermined portion located between the first and second position by using a current supply part(430). The voltage between the third and fourth position, is measured by using a voltage measuring part(330). At this time, the third and fourth position are located between the first and second position. The resistance of the semiconductor thin film sample is calculated by using the measuring current and the measure voltage.

Description

METHOD AND APPARATUS FOR MEASURING RESISTANCE OF SEMICONDUCTOR FILM}

The present invention relates to a semiconductor thin film resistance measuring method and a semiconductor thin film resistance measuring apparatus using the same, and more particularly, a method for measuring the thin film resistance of a semiconductor thin film by the optical current formed in the semiconductor thin film by the light irradiated to the semiconductor thin film; The present invention relates to a semiconductor thin film resistance measuring apparatus using the same.

In general, a "semiconductor film" means a thin film having conductor characteristics when a strong electric field having a positive polarity is applied from the outside and having a non-conducting characteristic when an electric field having a positive polarity from the outside is interrupted. do. Such a semiconductor thin film is mainly used as a channel layer of a thin film transistor used as a thin film type diode and a switching element.

The semiconductor thin film having such characteristics may be implemented with amorphous silicon, polysilicon, and single crystal silicon. Among them, the electrical properties are the best with single crystal silicon, and have the order of polysilicon and amorphous silicon.

That is, in order to fabricate a thin film transistor or a thin film diode having very excellent operating characteristics, polysilicon or single crystal silicon having excellent electrical characteristics is used.

However, very high process temperatures are required to fabricate thin film transistors using polysilicon or single crystal silicon, which have superior electrical properties as compared to amorphous silicon.

For this reason, a thin film transistor using polysilicon or single crystal silicon has a problem that it is very difficult to manufacture on a glass substrate having a low melting point as in a liquid crystal display device which has been rapidly developed recently.

On the other hand, in the case of amorphous silicon, the electrical property is not as good as that of polysilicon and single crystal silicon, but has an advantage that it can be realized in a thin film form at a low process temperature, for example, below the melting point of glass. Recently, a process temperature of n ⁺ amorphous silicon by implanting ions into the n ⁺ amorphous silicon in order to improve the electrical properties of amorphous silicon low development bar.

In fact, the resistance of amorphous silicon is very important when fabricating a thin film diode or a thin film transistor with amorphous silicon having such characteristics. For example, if the resistance of amorphous silicon is higher than the allowable value, the thin film transistor may not operate even if the specified electric field is applied. If the resistance of amorphous silicon is lower than the allowable value, the thin film transistor may malfunction even if an electric field lower than the specified electric field is applied. Can be.

Therefore, after forming a thin film from amorphous silicon, it is very important to measure what the thin film resistance of an amorphous silicon thin film is. At this time, the thin film resistance of amorphous silicon is about 10 ¹⁴ Ω per unit area.

A well-known method for measuring semiconductor thin film resistance so far is a four point probe type. 1 is a conceptual diagram illustrating a conventional semiconductor thin film resistance measuring apparatus for measuring the resistance of a semiconductor thin film by a 4-point probe method.

The semiconductor thin film resistance measuring apparatus 100 using the four-point probe method includes four first probes 10, second probes 20, third probes 30, and fourth probes 40 fixed at regular intervals. Have The spacing of these first to fourth probes 10, 20, 30, 40 is generally 1 mm. In this case, the second probe 20 and the third probe 30 are disposed inside the first to fourth probes 10, 20, 30, and 40.

In this case, reference numeral 1 denotes a semiconductor thin film, and reference numeral 3 denotes a base substrate on which a semiconductor thin film is formed.

On the other hand, the first probe 10 and the fourth probe 40 positioned outside apply a specified current between the first probe 10 and the fourth probe 40 of the semiconductor thin film 1.

In order to implement this, a voltage measuring device 50 for measuring a voltage is connected to the second probe 20 and the third probe 30, and a specified current is supplied to the first probe 10 and the fourth probe 40. The power applying device 60 is connected so that it can be applied.

As a result, the resistance of the semiconductor thin film 1 can be accurately calculated by the intensity of the current flowing through the semiconductor thin film 1 and the measured voltage according to the relationship between the voltage, the current, and the resistance.

The measurement range of the semiconductor thin film resistance measuring apparatus using the conventional four-point probe method is about a few mΩ to about 10 ¹¹ Ω. This measurement limit is determined by the impedance of the probe and the voltage measurement device.

However, amorphous silicon, one of the semiconductor thin films, has a thin film resistance of more than 10 ¹⁴ Ω. Therefore, it is very difficult to measure the thin film resistance of amorphous silicon using a real 4-point probe method. It is mainly used to measure low n ⁺ amorphous silicon.

The resistance of amorphous silicon, which is difficult to measure the resistance by a four-point probe method, is measured using a C-V capacitance-voltage meter (C-V meta) that applies voltage and current. In this case, in order to measure the resistance of amorphous silicon using C-V meta, a contact portion treated with mercury is formed on the surface of the amorphous silicon, and then the resistance of the amorphous silicon is measured.

In the case of using the C-V meta, the reliability of the measured resistance value is high, but it is difficult to use the sample due to mercury treatment, and there is another problem that it is difficult to know the distribution of resistance throughout the sample.

Accordingly, the present invention has been made in view of such a conventional problem, and a first object of the present invention is to provide a semiconductor thin film resistance measuring method capable of measuring a resistance value of an amorphous silicon thin film by forming a photocurrent in the amorphous silicon thin film. have.

A second object of the present invention is to provide a semiconductor thin film resistance measuring apparatus capable of measuring a resistance value of an amorphous silicon thin film by forming a photocurrent in the amorphous silicon thin film.

1 is a conceptual diagram showing a part of a conventional four-point probe type semiconductor thin film resistor device.

2 is a block diagram of a semiconductor thin film resistance measuring apparatus according to an embodiment of the present invention.

3 is a conceptual diagram illustrating a probe housing according to an embodiment of the present invention.

4 is a cross-sectional view of a semiconductor thin film resistance measuring apparatus according to an exemplary embodiment of the present invention.

5 is a cross-sectional view of a semiconductor thin film resistance measuring apparatus according to another exemplary embodiment of the present invention.

The semiconductor thin film resistance measuring method for implementing the first object of the present invention is irradiated with the measurement light so that the first position and the second position of the semiconductor thin film sample in which the photocurrent is generated by light to the semiconductor thin film sample Generating a preset photocurrent, applying a current for measurement between the first position and the second position, measuring voltage at a third position and a fourth position corresponding between the first position and the second position The resistance of the semiconductor thin film sample is calculated by the step and the measurement current and the measured voltage.

In addition, the semiconductor thin film resistance measuring apparatus for implementing the second object of the present invention is installed in the housing, the housing having a storage space therein, the first position and the second position of the semiconductor thin film sample in which photocurrent is generated by light Is installed in the photocurrent generator for generating a photocurrent to the semiconductor thin film sample by irradiating light so as to include a, a current applying device for applying a current for measurement between the first position and the second position, the housing, A voltage measuring device for measuring a voltage at a third position and a fourth position between the first position and the second position, a voltage calculating means for calculating a resistance of the semiconductor thin film sample by the current and the measured voltage, and a photocurrent generator; And a control unit for controlling the current application device and the voltage calculation device.

Hereinafter, a unique operation and effects of the semiconductor thin film resistance measuring method and the thin film resistance measuring apparatus according to the preferred embodiment of the present invention will be described with reference to the accompanying drawings.

Hereinafter, after describing the semiconductor thin film resistance measuring method, a semiconductor thin film resistance measuring apparatus will be described.

First, a process of forming an amorphous silicon thin film sample on a substrate is performed by a semiconductor thin film forming process such as chemical vapor deposition as a prior step. Of course, the amorphous silicon thin film formed on the substrate to be applied to the actual product can also be used as it can be measured.

In the state where the amorphous silicon thin film sample to be measured is prepared, generating a photocurrent in an area including an arbitrary first position and a second position formed at a predetermined distance apart from the first position in the amorphous silicon thin film sample.

The generating of the photocurrent in the region including the first position and the second position of the amorphous silicon thin film sample may more particularly include blocking external light reaching the measurement site again and removing the amorphous silicon thin film while the external light is blocked. And scanning light having a constant illuminance in the region including the first position and the second position of the sample.

As described above, blocking the external light in the step of generating the photocurrent in the amorphous silicon thin film may cause the intensity of the light current to be changed by the external light when the external light reaches the amorphous silicon thin film, thereby changing the voltage to be measured later. Because.

At this time, the light supplied to the amorphous silicon thin film sample in a state in which the external light is blocked so that the illuminance is always constant and localized illumination is possible.

Meanwhile, a step of applying a measurement current in a direction from the first position to the second position of the amorphous silicon thin film while generating a photocurrent in a region including the first position and the second position of the amorphous silicon thin film is performed. .

In a state where a current is applied in a direction from the first position to the second position of the amorphous silicon thin film, a step of measuring a voltage is performed at third and fourth positions corresponding to the first and second positions.

As described above, the step of calculating the resistance of the thin film by the relationship between the voltage, the current, and the resistance in the state where the voltage is measured at the third position and the fourth position is sequentially performed.

The resistance value of the thin film measured by this method is somewhat different from the resistance value calculated in the absence of light at all due to the influence of photocurrent. However, such a method may be particularly useful for measuring the resistance of amorphous silicon used as a channel layer of a thin film transistor used in a place requiring light, such as in a liquid crystal display.

Hereinafter, a semiconductor thin film resistance measuring apparatus will be described with reference to the accompanying drawings. 2 is a conceptual diagram showing the configuration of a semiconductor thin film resistance measuring apparatus according to an embodiment of the present invention.

Referring to FIG. 2 or FIG. 3, the semiconductor thin film resistance measuring apparatus 900 is again a control unit 200, a probe current applying device 400, a voltage measuring device 300, and a probe housing 500 in which a probe is installed. 3), a photocurrent generating unit 600, a data storage unit 700, and a data processing unit 800.

In this case, the control unit 200, the probe current applying device 400, the voltage measuring device 300, the photocurrent generating unit 600, the data storage unit 700, and the data processing unit 800 are the data bus 210. Data is input and output by the control bus, and the control signal is input and output by the control bus 220.

Among them, the data storage unit 700 includes the strength of the current applied to the semiconductor thin film, the magnitude of the measured voltage, and a calculation program. The data processing unit 800 includes the current data and the voltage data stored in the data storage unit 700. Thereby calculating the resistance of the semiconductor thin film. At this time, the semiconductor thin film is an amorphous silicon thin film in which a photocurrent is generated by light in one embodiment.

FIG. 3 shows a probe housing 500 for applying a current supplied from the probe current applying device 400 to the semiconductor thin film and measuring the voltage of the semiconductor thin film.

The probe housing 500 has a hollow pipe shape, and at the end thereof, the first probe coupling hole 510, the second probe coupling hole 520, the third probe coupling hole 530, and the fourth probe coupling hole ( 540 is formed. On the other hand, the probe housing 500 is formed with an external light blocking cap 550 to block external light incident on the semiconductor thin film.

Meanwhile, as illustrated in FIG. 4, the probe current measuring apparatus 400 may include a first probe 410, a second probe 420, and a current applying device 430. In this case, the current applying device 430 serves to generate a flow of the measurement current from the first probe 410 to the second probe 420.

The first probe 410 of the probe current measuring device 400 having such a configuration is again coupled to the first probe coupling hole 510 of the probe housing 500 to protrude out of the probe housing 500. The second probe 420 is again coupled to the second probe coupling hole 520 of the probe housing 500 to protrude out of the probe housing 500.

On the other hand, the voltage measuring device 300 is composed of a third probe 310, the fourth probe 320 and the voltage meter 330 as shown in FIG.

The third probe 310 is again coupled to the third probe coupling hole 530 of the probe housing 500, and the fourth probe 320 is again coupled to the fourth probe coupling hole 540 of the probe housing 500. do. In this case, the heights of the third probe 310 and the fourth probe 320, the first probe 410, and the second probe 420 are all set the same.

On the other hand, the external light blocking cap 550 formed on the end portion of the probe housing 500 is a concave ball (block 3) to block external light from reaching the semiconductor thin film shown by reference numeral 120 as shown in FIG. bowl) is formed. At this time, the semiconductor thin film is an amorphous silicon thin film in one embodiment. In addition, reference numeral 130 is a substrate on which a semiconductor thin film is formed.

On the other hand, the photocurrent generating unit 600 is composed of a light generating unit (not shown) for generating light again and the optical fiber 610 which is a medium for transmitting the light generated in the light generating unit.

In this case, the use of the optical fiber 610 is to be able to supply light having a constant illuminance to the semiconductor thin film 120 and at the same time to be locally supplied to a narrow area.

In one embodiment, the end of the optical fiber 610 to perform such a role is installed at a designated position of the interior of the external light blocking cap 550 through the through hole 555 formed in the external light blocking cap 550.

Alternatively, the optical fiber 610 may be supplied to the semiconductor thin film 120 through the probe housing 500 as shown in FIG. In order to implement this, an optical fiber insertion hole 560 is formed between the second probe 310 and the third probe 320 of the probe housing 500, and the optical fiber 610 is formed in the optical fiber insertion hole 560. ) Is inserted to supply light to the semiconductor thin film 120.

C-V measurement (where there is light) The present invention (four measurements) Amorphous Silicon (4000 Å) 5.95 × 10 ¹¹ 6.18 × 10 ¹⁴ 6.43 × 10 ¹⁴ 5.80 × 10 ¹⁴ 5.78 × 10 ¹⁴

<Table 1> measures the resistance of the amorphous silicon thin film which has a thickness of 4000 kPa by the C-V system and the method and apparatus by this invention.

In order to make the experimental conditions the same, the photocurrent was measured in the amorphous silicon in the C-V method, and in the present invention, it was used four times.

Experimental results As shown in Table 1, the resistance of the amorphous thin film in the C-V method and the present invention was measured almost similarly.

As described above, the semiconductor thin film having a high resistance of 10 ¹¹ Ω or more, for example, an amorphous silicon thin film, is irradiated with light so that a specified light current flows in the amorphous silicon thin film so that the resistance of the amorphous silicon thin film can be measured. Has an effect.

In the detailed description of the present invention described above with reference to a preferred embodiment of the present invention, those skilled in the art or those skilled in the art having ordinary knowledge in the scope of the invention described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

Claims (11)

Irradiating measurement light to include a first position and a second position of the semiconductor thin film sample in which the photo current is generated by the light to generate a predetermined photo current in the semiconductor thin film sample; Applying a current for measurement between the first position and the second position; Measuring a voltage at a third position and a fourth position corresponding between the first position and the second position; And And calculating the resistance of the semiconductor thin film sample based on the measurement current and the measured voltage. The method of claim 1, wherein the generating of the photocurrent further comprises blocking external light so that only the measurement light designated to the semiconductor thin film sample is scanned. The semiconductor thin film resistance measurement method according to claim 1, wherein the semiconductor thin film sample is an amorphous thin film. Housing with storage inside: Photocurrent generating means installed in the housing and irradiating light to include a first position and a second position of a semiconductor thin film sample in which a photo current is generated by light, thereby generating a photo current in the semiconductor thin film sample; A current application means installed in the housing for applying a measurement current between the first position and the second position; Voltage measuring means installed in the housing and measuring voltage at a third position and a fourth position between the first position and the second position; Voltage calculation means for calculating a resistance of the semiconductor thin film sample based on the current and the measured voltage; And And a control unit for controlling said photocurrent generating means, said current applying means, and said voltage calculating means. 5. The semiconductor thin film resistance measuring apparatus according to claim 4, wherein the photocurrent generating means includes an optical fiber and a light generating device for supplying light to the semiconductor thin film sample. The apparatus of claim 5, wherein an end portion of the optical fiber is emitted from the inside of the housing to the outside of the housing to supply light to the semiconductor thin film sample. The semiconductor thin film resistance measuring apparatus of claim 5, wherein an external light blocking cap is formed on the housing to prevent external light from being incident on the semiconductor thin film sample. The apparatus of claim 7, wherein a through hole is formed in the external light blocking cap, and the optical fiber is coupled through the through hole to supply light to the semiconductor thin film sample. The method according to claim 4, wherein the current applying means comprises: a first probe in contact with the first position of the semiconductor thin film sample, a second probe in contact with the second position, and the first probe from the first probe to the second probe; And a current supply device for supplying current so that the measurement current flows. The voltage measuring device of claim 4, wherein the voltage measuring means measures a voltage between the third probe formed at the third position, the fourth probe formed at the fourth position, and the third probe and the fourth probe. A semiconductor thin film resistance measurement apparatus comprising a meter). 5. The apparatus of claim 4, wherein the voltage calculating means includes a data storage device in which the strength of the current and the magnitude of the measured voltage are stored, and a calculation program for calculating the current data and voltage data stored in the data storage device. A semiconductor thin film resistance measuring apparatus comprising a computing device.