WO2019003845A1

WO2019003845A1 - Semiconductor inspection device and semiconductor inspection method

Info

Publication number: WO2019003845A1
Application number: PCT/JP2018/021796
Authority: WO
Inventors: 伊藤　明; 英俊中西; 敏光望月; 白澤　勝彦; 秀尚高遠
Original assignee: 株式会社Ｓｃｒｅｅｎホールディングス; 国立研究開発法人産業技術総合研究所
Priority date: 2017-06-29
Filing date: 2018-06-07
Publication date: 2019-01-03
Also published as: JP2019012728A; JP6958833B2

Abstract

Provided is a technique capable of inspecting the characteristics of a passivation film in an early stage of a semiconductor manufacturing process. This semiconductor inspection device 1 is provided with: an ion imparting unit 60 for performing a treatment for imparting ions to a passivation film 95 of a semiconductor sample 9; a light irradiation unit 20 for irradiating the semiconductor sample 9 with inspection light LP11 that generates electromagnetic waves; a detector 31 for detecting electromagnetic waves LT1 radiated from the semiconductor sample 9 due to the irradiation of the inspection light LP11; and a comparison and evaluation unit 706 which evaluates the characteristics of the passivation film 95. The comparison and evaluation unit 706 compares the electromagnetic waves LT1 radiated from the semiconductor sample 9 before the treatment by the ion imparting unit 60 and those after a predetermined time t has elapsed from the imparting of the ions.

Description

Semiconductor inspection apparatus and semiconductor inspection method

The present invention relates to a technique for inspecting defects, deterioration, etc. of a semiconductor sample.

In recent years, a phenomenon (voltage induced degradation, potential induced degradation (PID)) in which the output is reduced in a relatively short time due to application of high system voltage and environmental conditions such as high temperature and high humidity especially in mega solar etc. is known (for example, Patent Document 1).

FIG. 11 is a schematic view showing the structure of a general solar cell module 900. As shown in FIG. The solar cell module 900 includes a plurality of solar cells 902 electrically connected to one another by an interconnector 901. The plurality of solar cells 902 (for example, crystalline silicon solar cells) are sealed in EVA (Ethylene-Vinyl Acetate: ethylene vinyl acetate copolymer resin) 903. Among the main surfaces of the EVA 903, a reinforced white sheet glass 904 is attached as a surface material to the light receiving surface side, and a back sheet 905 as a back surface material is attached to the back surface side. Further, a reinforced white sheet glass 904, EVA 903 and a back sheet 905 are assembled to an Al (aluminum) frame 906. All of the solar cells 902 are electrically connected to a terminal box 907 provided on the back side of the solar cell module 900 through the interconnector 901.

The PID is considered to be one cause of generation of metal ions mainly composed of sodium (Na) ions of the reinforced white sheet glass 904. For example, a circuit may be formed from the Al frame 906, through the reinforced white sheet glass 904, the EVA 903 to the solar battery cell 902, which may cause a negative high voltage to be applied to the solar battery cell 902 (for example, -600 V of the system voltage) , -1000V, etc.). In such a state, metal ions such as Na ions can diffuse from the reinforced white sheet glass 904 into the EVA 903 of the encapsulant and reach the surface of the solar cell 902. Then, the Na ion or the like interacts with the electrons in the n-type layer of Si to reduce the bending of the band due to the pn junction which is important for photoelectric conversion, which may lower the power generation efficiency. In addition, the generation efficiency can be reduced by Na ions or the like entering the crystal defects of Si and becoming recombination centers. In addition, this hypothesis is not necessarily sufficiently verified, and further investigation of the cause of the PID is desired.

Usually, evaluation of the presence or absence of PID tolerance produces a solar cell module as shown in FIG. 11, and performs an accelerated test (PID test and Damp-Heat test) for exclusive use, and evaluates. It has been reported that it is preferable to increase the refractive index of the anti-reflection film (passivation film, silicon nitride (SiNx) film) of the solar cell as a means for suppressing the PID (Non-Patent Document 1).

Specifically, in order to confirm the PID, a PID acceleration test is performed on each of the solar cell modules having passivation films having a refractive index of 2.2 and 2.03. Then, PID occurred at a refractive index of 2.03 but was suppressed at a refractive index of 2.2. That is, it is considered possible to inspect the presence or absence of deterioration resistance such as PID by thus inspecting the characteristics of the passivation film.

JP, 2015-162488, A

However, the conventional PID test and Dmap-Heat test are performed on the fabrication of a solar cell module and a dedicated accelerated test, and it is extremely difficult to test the solar cell substrate when the passivation film is formed. Have difficulty. In order to manufacture a solar cell module, the back surface electrode formation process, the surface electrode formation process, the baking process, etc. are required with respect to a photovoltaic cell, and there existed a problem of taking time until it became testable. In addition, passivation films may be formed on the surface of semiconductor devices other than solar cell modules (for example, LSIs and power devices), and a technique for early and appropriate inspection of the characteristics of such passivation films is required. It is done.

Therefore, an object of the present invention is to provide a technology capable of carrying out a characteristic inspection of a passivation film at an early stage of a semiconductor manufacturing process.

A first aspect is a semiconductor inspection apparatus for inspecting a semiconductor sample having a passivation film having a fixed charge formed on the surface, the sample holding unit for holding the semiconductor sample, and a process for applying ions to the passivation film An ion applying unit to perform, a light irradiating unit to irradiate an inspection light for generating an electromagnetic wave to the semiconductor sample, a detector to detect the electromagnetic wave emitted by the semiconductor sample in response to the irradiation of the inspection light; A comparison evaluation unit for evaluating the characteristics of the passivation film by comparing each of the electromagnetic waves emitted by the semiconductor sample before the processing by the processing unit and after a predetermined time t after the ion application and after the processing for a predetermined time has elapsed .

A second aspect is the semiconductor inspection apparatus according to the first aspect, further comprising a scanning mechanism that scans the surface of the semiconductor sample with the inspection light emitted from the light irradiator.

A third aspect is the semiconductor inspection device according to the second aspect, wherein the ion application unit further includes an application region displacement mechanism that displaces the region to which the ions are applied relative to the surface of the semiconductor sample. .

A fourth aspect is the semiconductor inspection device according to any one of the first aspect to the third aspect, wherein the control unit that controls the ion applying unit and the light emitting unit and the time t based on a predetermined operation input. A time setting unit for setting the inspection light to the light irradiation unit after the time t set by the time setting unit after the ion applying unit applies the ions Irradiate.

A fifth aspect is the semiconductor inspection device according to any one of the first aspect to the fourth aspect, wherein ion applying conditions for setting the ions to be applied by the ion applying unit are set based on a predetermined operation input. The apparatus further comprises a setting unit.

A sixth aspect is the semiconductor inspection device according to any one of the first aspect to the fifth aspect, wherein the ion applying part is a needle-like discharge electrode, and a voltage capable of discharging the discharge electrode to the discharge electrode And a power supply unit to be applied.

A seventh aspect is the semiconductor inspection device according to any one of the first aspect to the sixth aspect, wherein the inspection light is pulsed light, and the detector is responsive to incident pulsed light for detection. A photoconductive antenna for detecting the intensity of the electromagnetic wave, and the semiconductor inspection apparatus further includes a delay unit for delaying the input time of the pulse light for detection with respect to the electromagnetic wave incident on the photoconductive antenna Prepare.

An eighth aspect is the semiconductor inspection device according to any one of the first aspect to the seventh aspect, wherein the ion application unit applies ions of the opposite sign to the fixed charge, and the comparison evaluation unit The characteristics of the passivation film are evaluated based on the sign of the polarity of the electromagnetic wave.

A ninth aspect is the semiconductor inspection device according to the eighth aspect, wherein the passivation film includes silicon nitride, and the ion applying unit can apply ions having a charge density of −1 × 10 ¹³ q / cm ² or less. It is configured.

A tenth aspect is the semiconductor inspection apparatus according to any one of the first aspect to the ninth aspect, wherein a portion of the sample holding portion in contact with the semiconductor sample is made of resin.

An eleventh aspect is a semiconductor inspection method for inspecting a semiconductor sample on the surface of which a passivation film having a fixed charge is formed, wherein (a) the semiconductor sample is irradiated with inspection light and the semiconductor sample emits an electromagnetic wave A step of detecting the intensity, (b) a step of applying ions to the passivation film after the step (a), and (c) the inspection light on the semiconductor sample after the step (b). And detecting the intensity of the electromagnetic wave emitted by the semiconductor sample in response to the irradiation emitted by the semiconductor sample; (d) the electromagnetic waves detected in the steps (b) and (d) Evaluating the characteristics of the passivation film in the semiconductor sample by comparing.

According to the semiconductor inspection device of the first aspect, if the formation of the passivation film is defective, the applied ions are retained to change the band structure in the vicinity of the passivation film and change the intensity of the radiated electromagnetic wave. It can. Therefore, the characteristics of the passivation film can be properly evaluated by comparing the intensity of the electromagnetic wave before and after the treatment of ion application. In addition, since the performance can be inspected when the passivation film is formed on the semiconductor, the characteristics of the passivation film can be evaluated at an early stage of the semiconductor manufacturing process.

According to the semiconductor inspection apparatus of the second aspect, since the inspection light can be irradiated to different parts of the semiconductor sample, the characteristics of the passivation film can be evaluated for each different part.

According to the semiconductor inspection device of the third aspect, ions can be applied to different portions of the semiconductor sample.

According to the semiconductor inspection device of the fourth aspect, the operator can appropriately set the time t in accordance with the type of the passivation film and the like.

According to the semiconductor inspection device of the fifth aspect, the operator can appropriately set the conditions of the ions to be applied according to the type of the passivation film and the like.

According to the semiconductor inspection device of the sixth aspect, ions generated by discharge can be applied to the passivation film.

According to the semiconductor inspection apparatus of the seventh aspect, since the time waveform can be restored, the deterioration resistance can be analyzed in more detail.

According to the semiconductor inspection device of the eighth aspect, the band structure on the surface of the passivation film can be reversed by applying ions of the opposite sign to the fixed charge of the passivation film. In this case, if there is a defect in the passivation film, the sign of the polarity of the electromagnetic wave emitted from the semiconductor sample may be reversed. Therefore, the characteristics of the passivation film can be properly evaluated only by comparing the signs of the polarities of the electromagnetic waves.

According to the semiconductor inspection device according to a ninth aspect, the charge density of fixed charges passivation film in the case of less than ^{^{1 × 10 13 q / cm 2}} , to impart ion of -1 × ¹⁰ 13 q / cm ² or less charge density By this, the electric field on the surface of the passivation film can be reversed. Thus, the positive and negative of the intensity of the electromagnetic wave emitted by the semiconductor sample can be reversed.

According to the semiconductor inspection apparatus of the tenth aspect, since the portion of the sample holder in contact with the semiconductor sample is made of resin, damage to the semiconductor sample can be reduced. For this reason, the semiconductor sample which is an unfinished product before becoming a product can be inspected nondestructively.

According to the semiconductor inspection method of the eleventh aspect, if the formation of the passivation film is defective, the applied ions are retained, whereby the band structure in the vicinity of the passivation film changes, and the intensity of the radiated electromagnetic wave changes. It can. Therefore, the characteristics of the passivation film can be properly evaluated by comparing the intensity of the electromagnetic wave before and after the treatment of ion application. In addition, since the performance can be inspected when the passivation film is formed on the semiconductor, the characteristics of the passivation film can be evaluated at an early stage of the semiconductor manufacturing process.

It is a schematic block diagram of semiconductor inspection device 1 of an embodiment. FIG. 5 is a schematic cross-sectional view showing a semiconductor sample 9; It is a schematic block diagram which shows the light irradiation part 20 and the electromagnetic wave detection part 30 of the semiconductor inspection apparatus 1 of embodiment. It is a figure which shows the time waveform of electromagnetic wave LT1 which the semiconductor sample 9 (refractive index 2.1) before and after the process of ion provision emits. It is a figure which shows the time waveform of electromagnetic wave LT1 which the semiconductor sample 9 (refractive index 2.0) before and after the process of ion provision emits. It is a figure which shows the relationship between the charge density of provision ion, and electromagnetic wave intensity. It is a figure which shows the band structure of surface vicinity of the passivation film 95 (refractive index 2.1) before and after the process of ion provision. It is a figure which shows the band structure of surface vicinity of the passivation film 95 (refractive index 2.0) before and after the process of ion provision. It is a figure showing the flow of operation of semiconductor inspection device 1 of an embodiment. It is a figure which shows electromagnetic wave intensity distribution image WID1, WID2 in the semiconductor sample 9 before an ion provision process and after an ion provision process. It is a schematic diagram which shows the structure of the general solar cell module 900. As shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The constituent elements described in this embodiment are merely examples, and the scope of the present invention is not limited to them. In the drawings, for the sake of easy understanding, the dimensions and the numbers of the respective parts may be exaggerated or simplified as necessary.

<1. First embodiment>
FIG. 1 is a schematic block diagram of a semiconductor inspection apparatus 1 of the embodiment. FIG. 2 is a schematic cross-sectional view showing the semiconductor sample 9. FIG. 3 is a schematic configuration view showing the light irradiation unit 20 and the electromagnetic wave detection unit 30 of the semiconductor inspection device 1 of the embodiment.

The semiconductor inspection apparatus 1 irradiates light (pulse light in this case) having a predetermined wavelength to a semiconductor sample which is an inspection object, and the electromagnetic wave LT1 (specifically, the semiconductor sample emits in response to the irradiation of the light). By detecting a terahertz wave having a frequency of 0.1 THz to 10 THz), the characteristics and the like of the semiconductor sample are inspected.

Here, the semiconductor sample may include a semiconductor device and a photo device. A semiconductor device is an electronic device that includes a transistor constituted by a semiconductor, an integrated circuit (IC or LSI), a resistor or a capacitor. The photo device is an electronic device that utilizes the photoelectric effect of a semiconductor, such as a photodiode, an image sensor such as a CMOS sensor or a CCD sensor, a solar cell or an LED. Below, the case where semiconductor sample 9 is a silicon substrate for solar cells is mainly explained.

As shown in FIG. 2, the semiconductor sample 9 is a member for a solar battery cell, and is formed in a flat plate shape. The semiconductor sample 9 has a p-type silicon layer 91, an n-type silicon layer 93, and a passivation film 95 in order. The passivation film 95 is a so-called antireflective film, and is, for example, a silicon oxide film (SiOx film) or a silicon nitride film (SiNx film). Further, a junction portion of the p-type silicon layer 91 and the n-type silicon layer 93 is a pn junction portion 97.

A back surface electrode and a front surface electrode are formed on this semiconductor sample 9 and fired to complete a solar battery cell. Furthermore, the solar battery module is completed by performing soldering, laminate formation, and lamination on the solar battery cell.

As shown in FIG. 1, the semiconductor inspection apparatus 1 includes a stage 10, a light irradiation unit 20, an electromagnetic wave detection unit 30, a delay unit 40 (see FIG. 3), a stage drive unit 50, an ion application unit 60, and a control unit 70. ing.

The stage 10 holds the semiconductor sample 9 by fixing means (not shown). As a fixing means, various means such as a holding tool for holding the both ends of the semiconductor sample 9, a pressure-sensitive adhesive sheet adhering to the back main surface of the semiconductor sample 9, and a means for sucking air from suction holes formed on the surface of the stage 10 Things can be considered. When the semiconductor sample 9 is to be held like the holding tool, the holding tool is preferably made of resin rather than metal. Since the portion of the sample holder in contact with the semiconductor sample 9 is made of resin, damage to the semiconductor sample 9 can be reduced. For this reason, the semiconductor sample 9 which is an unfinished product before becoming a product can be inspected nondestructively.

<Light irradiation unit 20>
As shown in FIG. 3, the light irradiation unit 20 includes a femtosecond laser 21. The femtosecond laser 21 outputs, for example, pulsed light LP1 of a wavelength including a visible light range of 300 nm (nanometers) or more and 1.5 μm (micrometers) or less. In a preferred example, linearly polarized pulsed light having a center wavelength of about 800 nm, a period of several kHz to several hundreds of MHz, and a pulse width of about 10 to 150 femtoseconds is emitted from the femtosecond laser. Of course, pulsed light of other wavelength regions (for example, visible light wavelengths of blue wavelength (450 to 495 nm) and green wavelength (495 to 570 nm)) may be emitted.

The pulsed light LP1 emitted from the femtosecond laser 21 is split into two by the beam splitter BE1. One pulse light is irradiated to the surface of the semiconductor sample 9 as the inspection light LP11. The stage 10 holds the semiconductor sample 9 so that the inspection light LP 11 is incident on the passivation film 95 side of the semiconductor sample 9. The light irradiation unit 20 irradiates the semiconductor light 9 with the inspection light LP11 so that the optical axis of the inspection light LP11 is oblique to the surface of the passivation film 95. In the present embodiment, the incident angle of the inspection light LP11 is 45 °, but is not limited to this, and may be set within the range of 0 ° to 90 °. In addition, the light irradiation unit 20 may be configured so that the incident angle of the inspection light LP11 can be changed.

The inspection light LP11 is irradiated to the passivation film 95 in a spot shape. The spot diameter (irradiation diameter) of the inspection light LP11 in the passivation film 95 is, for example, 1 μm to 10 mm, but is not limited to this.

When the inspection light LP11 (pulsed light) having energy exceeding the forbidden band width is irradiated to a portion where the internal electric field of the semiconductor sample 9 exists, photoexcited carriers (free electrons and free holes) are generated. The photoexcited carriers are accelerated by the internal electric field of the semiconductor sample 9. As a result, a pulsed current is generated, and in response, a pulsed electromagnetic wave LT1 (terahertz wave) having a wavelength range different from that of the inspection light LP11 is generated. Therefore, by measuring the electromagnetic wave LT1, the state of the internal electric field (such as the strength and the direction of the electric field) can be inspected.

<Electromagnetic wave detection unit 30>
The electromagnetic wave detection unit 30 includes a detector 31 that detects the electromagnetic wave LT1 emitted by the semiconductor sample 9. The detector 31 here is constituted by a photoconductive antenna. The detection light LP21, which is the other pulse light split by the beam splitter BE1, is incident on the detector 31. The detector 31 detects the intensity of the electromagnetic wave LT1 at the timing when the detection light LP21 is incident.

As a photoconductive antenna, a dipole type, a bow-tie type and a spiral type are known. For example, a dipole-type photoconductive antenna includes a photoconductive film that generates electrons and holes when the detection light LP21 is incident, and a pair of parallel transmission lines (electrodes) formed in parallel on the photoconductive film. And A central portion of each of the pair of parallel transmission lines is provided with a protrusion (antenna) extending inward to form a gap. In addition, an ammeter is provided between the pair of parallel transmission lines.

When the detection light LP21 is irradiated to the gap between the antennas, photoexcited carriers are generated in the photoconductive film. Even if the photoexcited carrier is generated, no current is generated in the state where the electromagnetic wave LT1 is not incident, since no potential difference is generated between the gaps. On the other hand, when the electromagnetic wave LT1 is incident at a timing overlapping the detection light LP21, a potential difference proportional to the intensity of the electromagnetic wave LT1 is instantaneously generated between the gaps, and a current is instantaneously generated. This current value is appropriately converted into a digital value through a lock-in amplifier, an A / D conversion circuit, etc. (not shown).

As described above, by providing the photoconductive antenna, the electromagnetic wave detection unit 30 detects the electric field intensity of the electromagnetic wave LT1 emitted by the semiconductor sample 9 in response to the irradiation of the detection light LP21. The detector 31 may be configured by an element different from the photoconductive antenna. For example, non-linear optical crystals or Schottky barrier diodes may also be employed.

<Delay unit 40>
The delay unit 40 is a delay mechanism that delays the detection light LP21. The delay unit 40 includes a delay stage 41 and a delay stage driver 43.

The delay stage 41 is provided on the optical path of the detection light LP21. The delay stage 41 is provided with a reflection mirror 41M that reflects the detection light LP21 in parallel with the incident direction thereof and offset from the optical axis at the time of the incident light. The LP 21 reflected by the reflection mirror 41 M is reflected by a group of mirrors disposed on the optical path, and is guided to the detector 31.

The delay stage drive unit 43 linearly reciprocates the delay stage 41 along the optical path of the detection light LP21 incident on the reflection mirror 41M. As a result, the optical path length of the detection light LP21 is changed, and the time for the detection light LP21 to reach the detector 31 is delayed. That is, the timing at which the detector 31 detects the electromagnetic wave LT1 is delayed. The electromagnetic wave LT1 emitted by the semiconductor sample 9 is a pulse wave. Therefore, the intensity of the electromagnetic wave LT1 can be detected for each phase by delaying the detection light LP21.

In the present embodiment, the delay unit 40 delays the detection light LP21. However, a delay may be given to the inspection light LP11. Specifically, the delay stage 41 may be provided on the optical path of the LP 11 and the delay stage 41 may be moved by the delay stage drive unit 43 to change the optical path length of the inspection light LP 11. As a result, the timing at which the inspection light LP11 (pulsed light) is incident on the semiconductor sample 9 can be delayed, and thus the timing at which the electromagnetic wave LT1 is generated and hence the timing at which the electromagnetic wave LT1 reaches the detector 31 can be delayed. Therefore, the intensity of the electromagnetic wave LT1 can be detected for each phase by delaying the inspection light LP11.

<Stage driver 50>
The stage drive unit 50 moves the stage 10 relative to the light irradiation unit 20 and the electromagnetic wave detection unit 30 along a horizontal plane parallel to the upper surface thereof. Thus, the semiconductor inspection apparatus 1 scans the passivation film 95 of the semiconductor sample 9 held on the upper surface of the stage 10 with the inspection light LP11. Thus, the stage drive unit 50 is an example of a scanning mechanism.

The scanning mechanism is not limited to the configuration such as the stage driving unit 50. For example, a mechanism for moving the light irradiation unit 20 and the electromagnetic wave detection unit 30 in a horizontal plane may be provided as a scanning mechanism. By moving the light irradiator 20 in a horizontal plane, the surface of the semiconductor sample 9 held on the stage 10 can be scanned with the inspection light LP11. Further, as a scanning mechanism, changing means (a galvano mirror or the like) for changing the optical path of the inspection light LP11 may be provided. The passivation film 95 of the semiconductor sample 9 can be scanned with the inspection light LP11 by changing the optical path of the inspection light LP11 by this changing means.

<Ion imparting unit 60>
The ion applying unit 60 is a device that performs processing for applying positive ions or negative ions to the semiconductor sample 9. Here, the ion applying unit 60 is configured as a corona discharge device having the discharge electrode 61 and the power supply unit 63.

The discharge electrode 61 is a conductive member formed in a needle shape, and is disposed above the semiconductor sample 9 held by the stage 10 at a distance above the semiconductor sample 9. The tip of the discharge electrode 61 is directed to the passivation film 95 of the semiconductor sample 9 held by the stage 10. The power supply unit 63 is a device that applies a high voltage to the discharge electrode 61. The operation of the power supply unit 63 is controlled by the ion application control unit 701 of the control unit 70.

When the discharge electrode 61 starts discharge, molecules in the air are ionized. As shown in FIG. 1, the generated ions are applied to the semiconductor sample 9 through the electrode 65 having a hole formed in the center. By charging the electrode 65 positively or negatively, negative ions or positive ions of the opposite pole are absorbed. In this way, either positive ions or negative ions can be selectively applied to the semiconductor sample 9.

The ion applying unit 60 applies ions not to the entire surface of the passivation film 95 of the semiconductor sample 9 but to a limited region. Hereinafter, the region to which the ion applying unit 60 applies ions is referred to as a applying region. As the stage driving unit 50 moves the stage 10 and the semiconductor sample 9 in the horizontal plane, the position of the semiconductor sample 9 relative to the ion applying unit 60 changes relatively. Therefore, the application region can be displaced relative to the semiconductor sample 9 by moving the semiconductor sample 9. The stage drive unit 50 constitutes an application area displacement mechanism.

The application area displacement mechanism is not limited to the configuration such as the stage drive unit 50. For example, a mechanism for moving the discharge electrode 61 of the ion applying unit 60 in a horizontal plane may be used as the application region displacement mechanism. Even when such a mechanism is employed, the application region can be displaced with respect to the surface of the semiconductor sample 9.

<Control unit 70>
The control unit 70 controls the operation of the semiconductor inspection device 1. The control unit 70 has a configuration (CPU, ROM, RAM, etc.) as a general computer. Further, the control unit 70 includes a storage unit 72. The storage unit 72 may temporarily store information such as a RAM. Further, the control unit 70 is connected to a display unit 74 configured of a liquid crystal display for displaying various information, and an operation unit 76 configured of various input devices such as a keyboard and a mouse.

As shown in FIG. 1, when the CPU of the control unit 70 operates according to a predetermined program, the control unit 70 controls the ion application control unit 701, the stage drive control unit 702, the delay stage drive control unit 703, and the time waveform restoration unit 704. These functions as the comparison evaluation unit 705, the time setting unit 706, and the image generation unit 707.

The ion application control unit 701 controls the discharge from the discharge electrode 61 by controlling the power supply unit 63 of the ion application unit 60. Further, the ion application control unit 701 controls the amount of ions applied by the ion applying unit 60 to the semiconductor sample 9 by controlling the voltage applied to the discharge electrode 61 by the power supply unit 63. Further, the ion application control unit 701 controls the polarity (positive or negative) of the electrode 65 to control the polarity of ions to be applied to the semiconductor sample 9.

The ion application control unit 701 receives, through the operation unit 76, an operation input by the operator for specifying the amount of ions to be applied to the semiconductor sample 9 or the polarity of the ions. The ion deposition control unit 701 controls the ion deposition unit 60 based on the received operation input.

The stage drive control unit 702 controls the stage drive unit 50. The stage drive control unit 702 receives, through the operation unit 76, an operation input by the operator for specifying a position to be inspected on the semiconductor sample 9. The stage drive control unit 702 controls the stage drive unit 50 based on the received operation input to move the stage 10 so that the inspection target portion matches the incident position of the inspection light LP11. Further, the stage drive control unit 702 receives an operation input for designating an inspection target range that the operator wants to inspect. Then, the stage 10 is moved so that the received inspection target range is scanned by the inspection light LP11.

The delay stage drive control unit 703 moves the delay stage 41 by controlling the delay stage drive unit 43, and adds a time delay to the detection light LP21. Thereby, the electric field strength for each phase is detected for the electromagnetic wave LT1 generated in a pulse shape.

The time waveform restoration unit 704 restores the time waveform of the electromagnetic wave LT1 based on the electric field strength for each phase of the electromagnetic wave LT1 collected by the delay stage drive control unit 703 controlling the delay stage drive unit 43. More specifically, the time waveform restoration unit 704 plots the time waveform of the electromagnetic wave LT1 by plotting the detected electric field strength on a two-dimensional coordinate with the horizontal axis representing phase (time) and the vertical axis representing the electric field strength. Restore.

The comparative evaluation unit 705 evaluates the characteristics of the passivation film 95 in the semiconductor sample 9. Here, the comparative evaluation unit 705 evaluates the passivation film 95 by comparing each of the electromagnetic wave intensities emitted by the semiconductor sample 9 before and after the treatment by the ion application unit.

The time setting unit 706 sets a time t until the ion applying unit 60 performs the ion application and measures the electromagnetic wave LT1. The time setting unit 706 receives a designation input of the operator via the operation unit 76, and sets a time t based on the designation input. In the latter case, the control unit 70 may receive a designation input of the operator via the operation unit 76. Specifically, the operator may arbitrarily designate the time t, or if the operator designates the type of the passivation film 95 and the conditions for ion deposition, the time t is automatically determined accordingly. You may The time t may be a fixed value stored in advance in the storage unit 72. In this case, the time setting unit 706 may be omitted.

The image generation unit 707 generates an image to be displayed on the display unit 74. The image generation unit 707 generates, for example, an electric field strength distribution image. The electric field intensity distribution image is an image that visually represents the distribution of the electric field intensity of the electromagnetic wave LT1 generated at each inspection target location by color or pattern when the inspection target range in the semiconductor sample 9 is scanned with the inspection light LP11. It is.

<About inspection of passivation film>
Next, the inspection principle of the passivation film 95 will be described.

FIG.4 and FIG.5 is a figure which shows the time waveform of electromagnetic wave LT1 which the semiconductor sample 9 before and after the process of ion provision radiates | emits. 4 shows time waveforms TW10 and TW12 of the electromagnetic wave LT1 emitted by the semiconductor sample 9 having a refractive index of 2.1, and FIG. 5 shows an electromagnetic wave LT1 emitted by the semiconductor sample 9 having a refractive index of 2.0. The time waveforms TW20 and TW22 are shown.

The ion applying treatment is performed by the ion applying unit 60, and after the application applying treatment, measurement is performed for a predetermined time (here, after 1 to 2 minutes) after the ions are applied by the ion applying unit 60. The results are shown. Further, here, the polarity of the ions applied by the ion applying unit 60 is opposite in sign to the fixed charge of the passivation film 95. The charge density (corona charge density) of the ions given to the passivation film 95 is −1 × 10 ¹³ q / cm ² . This charge density is the opposite sign of the charge density (about 1 × 10 ¹² q / cm ² ) of the passivation film 95 and has a large absolute value.

As shown in FIG. 4, when the refractive index is relatively high (refractive index 2.1), almost no change is observed when the time waveform TW10 before processing and the time waveform TW12 after processing are compared. On the other hand, as shown in FIG. 5, in the case where the refractive index is relatively low (refractive index 2.0), when comparing the time waveform TW20 before processing and the time waveform TW22 after processing, positive and negative signs Is inverted. This is because the charge density (-1 × 10 ¹³ q / cm ² ) of the applied ions is larger than the charge density (1 × 10 ¹² q / cm ² ) of the passivation film 95 and has the opposite sign. It is guessed.

FIG. 6 is a view showing the relationship between the charge density of the imparted ions and the electromagnetic wave intensity. In FIG. 6, the abscissa represents the charge density of the applied ions, and the ordinate represents the peak intensity. The peak intensity is the electric field intensity at which the absolute value of the electric field intensity is maximum in the time waveform. In FIG. 6, the open squares correspond to the semiconductor sample 9 having a refractive index of 2.1, and the open triangles correspond to the semiconductor sample 9 having a refractive index of 2.0.

As shown in FIG. 6, in the semiconductor sample 9 having a refractive index of 2.1, almost no change in peak intensity is observed even if the charge density of ions is changed. On the other hand, in the semiconductor sample 9 having a refractive index of 2.0, the peak intensity is reversed as the charge density of ions is made negative to increase the absolute value.

FIG. 7 and FIG. 8 are diagrams showing the band structure near the surface of the passivation film 95 before and after the treatment of ion application. FIG. 7 shows the band structure of the semiconductor sample 9 in which the passivation film 95 having a refractive index of 2.1, that is, the good passivation film 95 having a relatively high PID resistance is formed. Further, FIG. 8 shows the band structure of the defective passivation film 95 having a refractive index of 2.0, that is, a relatively low PID resistance.

Usually, the band structure near the surface of the passivation film 95 of the semiconductor sample 9 which is a silicon substrate for solar cells collects electrons on the surface electrode, and as shown in the upper part of FIGS. It has a structure.

Then, as shown in FIG. 7, when the passivation film 95 is formed well, when the ions are applied, the ions can be diffused without being retained at the sites where the ions are applied. For this reason, it is considered that the band structure hardly changes. Therefore, as shown in FIG. 4, it is presumed that the intensity of the electromagnetic wave LT1 emitted from the semiconductor sample 9 before and after the treatment of ion application hardly changes.

On the other hand, when the passivation film 95 is defective in formation, when ions are applied, the surface of the passivation film 95 is likely to be charged by staying at the site to which the ions are applied. Therefore, it is considered that the band structure in the vicinity of the surface of the passivation film 95 is changed by the fact that the ions do not diffuse even after a predetermined time has elapsed. In the example shown in FIG. 8, since an ion (here, a negative ion) having a charge density of the opposite sign to the fixed charge is applied to the passivation film 95, it has a band structure bent upward. Therefore, when the passivation film 95 is defective in formation, as shown in FIG. 5, it is presumed that the sign of the electromagnetic wave LT1 radiated from the semiconductor sample before and after the process of ion application is reversed.

Based on the above principle, the characteristics of the passivation film 95 can be evaluated by comparing the intensity of the electromagnetic wave LT1 emitted by the semiconductor sample 9 before and after the treatment of ion application. In particular, the presence or absence or degree of PID resistance can be properly evaluated by evaluating the characteristics of the passivation film 95 with respect to the semiconductor sample 9 which is an incomplete product before the product to be a solar battery cell or a solar cell module. That is, the characteristic inspection of the passivation film can be carried out at an early stage of the semiconductor manufacturing process.

<Description of operation>
Next, the flow of inspection of the semiconductor sample 9 will be described. FIG. 9 is a diagram showing the flow of the operation of the semiconductor inspection device 1 of the embodiment.

When the inspection is started, the semiconductor sample 9 is first held on the stage 10 (step S1). In detail, the semiconductor sample 9 is held at a predetermined position on the stage 10 by fixing means (not shown) on the stage 10.

Subsequently, electromagnetic wave measurement is performed on the inspection target portion of the semiconductor sample 9 (step S2). Specifically, the stage drive unit 50 moves the stage 10 such that the inspection target portion coincides with the incident position of the inspection light LP11. The inspection target location may be a location designated by the operator or a predetermined location. Then, the light irradiation unit 20 irradiates the surface of the passivation film 95 of the semiconductor sample 9 with the inspection light LP 11 in a spot shape with a predetermined irradiation diameter. Furthermore, the detector 31 detects the electric field intensity of the electromagnetic wave LT1 emitted from the semiconductor sample 9 at the timing when the detection light LP21 is incident. At this time, the delay stage drive control unit 703 controls the delay stage 41 to delay the detection light LP21. Thereby, the electromagnetic wave intensity of the electromagnetic wave LT1 is detected for each phase. The time waveform restoration unit 704 restores the time waveform from the electromagnetic wave LT1 from the collected electromagnetic wave intensity.

Subsequently, quality determination of the semiconductor sample 9 is performed based on the electromagnetic wave intensity acquired in step S2 (step S3). Specifically, for example, in the time waveform of the restored electromagnetic wave LT1, when the control unit 70 determines whether the polarity (positive or negative) of the peak intensity or the absolute value thereof satisfies a predetermined reference. Good. If the criteria are satisfied (Yes in step S3), a positive evaluation is given, and the next step S4 is performed. If the reference is not satisfied (No in step S3), a negative evaluation is given to the semiconductor sample 9 (step S31), and the inspection of the semiconductor sample 9 ends.

When the positive evaluation is made in step S3 (Yes in step S3), the ion imparting condition that the ion applying unit 60 applies to the inspection target portion of the semiconductor sample 9 is set (step S4). As the conditions for ion application, for example, the polarity (positive or negative) and ion amount (charge density) of the ions to be applied are set. Specifically, the ion deposition control unit 701 receives a setting input from the operator via the operation unit 76, and sets the polarity and amount of ions based on the setting input. Note that the ion application control unit 701 may directly receive the input of the polarity and the ion amount of the ion as a numerical value or the like. Alternatively, the ion application control unit 701 may receive designation of the type of the passivation film 95, and automatically determine the polarity and amount of ions corresponding to the designated type. In this case, it is preferable to create a table in which ion application conditions predetermined for each type of passivation film 95 are predetermined, and store the table in the storage unit 72.

Subsequently, ion imparting processing is performed on the semiconductor sample 9 (step S5). Specifically, the ion application control unit 701 applies ions to the passivation film 95 in accordance with the ion application conditions set in step S4.

Subsequently, it is determined whether or not a predetermined time t has elapsed after the ion applying process of step S5 (step S6).

When the time t has elapsed (Yes in step S6), electromagnetic wave measurement is performed on the measurement target portion of the semiconductor sample 9 (step S7). Specifically, in step S7, as in step S2, the electric field intensity of the electromagnetic wave LT1 emitted from the semiconductor sample 9 in response to the irradiation of the inspection light LP11 is detected by the detector 31. Further, the delay is given to the detection light LP21, whereby the electric field strength for each phase of the electromagnetic wave LT1 is acquired. The time waveform restoration unit 704 restores the time waveform from the electromagnetic wave LT1 from the collected electromagnetic wave intensity.

Subsequently, comparative evaluation processing is performed to evaluate the characteristics of passivation film 95 (step S8). Specifically, the comparative evaluation unit 705 determines the electric field intensity of the electromagnetic wave LT1 emitted by the semiconductor sample 9 before the ion applying treatment (the electric field intensity measured in step S2) and the predetermined time t after the ion applying treatment. The electric field strengths of the electromagnetic waves LT1 emitted by the semiconductor samples 9 are compared.

When comparing the intensities, it is preferable to compare peak intensities before and after treatment as described above. Specifically, it is conceivable to evaluate the characteristics of the passivation film 95 based on the sign of the polarity of the peak intensity. In this case, in step S5, it is preferable to apply, to the semiconductor sample 9, ions of a polarity opposite to that of the fixed charge of the passivation film 95 and larger than the absolute value of the fixed charge. If the passivation film 95 is defective, it is expected that the sign of the peak intensity is reversed as described in FIGS. 4 and 5. Therefore, the quality of the passivation film 95 can be properly evaluated only by determining the sign of the peak intensity.

Further, in step S5, ions of a polarity opposite to that of the fixed charge and smaller than the absolute value of the fixed charge may be applied to the semiconductor sample 9. In this case, if there is a defect in the passivation film 95, it is expected that the absolute value of the peak intensity after processing will be smaller according to the amount of ions applied than before processing. Therefore, the quality of the passivation film 95 can be properly evaluated by comparing the absolute values of the peak intensities.

Furthermore, in step S5, ions of the same sign as the fixed charge may be provided. In this case, if there is a defect in the passivation film 95, it is expected that the peak intensity will be increased according to the amount of ion applied after the treatment as compared to before the treatment. Therefore, the quality of the passivation film 95 can be properly evaluated by comparing the magnitudes of the peak intensities.

Further, as shown in FIG. 6, the peak intensity for each ion amount may be confirmed by shaking the amount of ions to be applied. In this case, since the characteristic change of the passivation film 95 due to the ion application process and the characteristic change of the passivation film 95 depending on the amount of ions can be analyzed, the characteristic of the passivation film 95 can be appropriately evaluated.

In step S2 and step S7, the delay unit 40 is operated to collect the electric field intensity for each phase, and the time waveform restoration unit 704 restores the time waveform. However, restoration of this time waveform is not essential. That is, the timing at which the detector 31 detects the electromagnetic wave LT1 may be fixed without operating the delay unit 40. For example, the timing p1 (phase) at which the peak intensity is obtained can be specified from the time waveform restored in step S2 (see FIGS. 4 and 5). Therefore, in step S7, the delay stage 41 may be fixed at a position corresponding to the timing p1 and the electric field strength of the electromagnetic wave LT1 may be measured. As a result, since the peak intensity can be measured without operating the delay unit 40, the time taken for the measurement can be shortened.

Moreover, although the said embodiment demonstrated the case where a test object location was one place, it is also considered to make several places on the semiconductor sample 9 into test object. In this case, the stage driving unit 50 may be operated to measure electromagnetic waves at a plurality of locations of the semiconductor sample 9. At this time, for example, by fixing the detection timing of the detector 31 to the timing p1, the peak intensity of the electromagnetic wave LT1 can be measured in a short time at each inspection target location.

When inspection is performed on a plurality of inspection target parts, it is preferable to first perform electromagnetic wave measurement on all the inspection target parts first, and then alternately perform the ion applying process and the electromagnetic wave measurement for each inspection part. By performing the electromagnetic wave measurement first, the distribution of the electromagnetic wave intensity without the influence of the ion application can be obtained, so the characteristics of the plurality of portions of the passivation film 95 can be appropriately evaluated.

FIG. 10 is a view showing the electromagnetic wave intensity distribution images WID1 and WID2 of the semiconductor sample 9 before and after the ion applying process. As shown in FIG. 10, by generating the electromagnetic wave intensity distribution images WID1 and WID2, it is possible to evaluate the characteristics of the passivation film 95 for each part. In addition, it is easy to identify the portion where the passivation film 95 is defective.

<2. Modified example>
As mentioned above, although embodiment was described, this invention is not limited to the above things, A various deformation | transformation is possible.

In the above embodiment, the characteristics of the passivation film 95 formed on the n-type silicon layer 93 are inspected. However, the semiconductor inspection apparatus 1 can also be applied to inspection of a passivation film formed on a p-type silicon layer. In addition, the semiconductor sample 9 is not limited to one for a solar cell module.

In the above embodiment, the ion applying unit 60 is configured to apply the ions generated by the corona discharge to the passivation film 95. However, ions may be applied by another method. For example, ionizing radiation may be emitted toward the semiconductor sample 9 to ionize and ionize gas molecules in the vicinity of the semiconductor sample 9. In this case, ions of unnecessary polarity may be removed by electrodes or the like disposed around the periphery. Further, it is preferable to control the amount of applied ions by adjusting the dose of ionizing radiation.

Although the present invention has been described in detail, the above description is an exemplification in all aspects, and the present invention is not limited thereto. It is understood that countless variations not illustrated are conceivable without departing from the scope of the present invention. The configurations described in the above-described embodiments and the modifications can be appropriately combined or omitted as long as no contradiction arises.

Reference Signs List 1 semiconductor inspection apparatus 10 stage 20 light irradiation unit 21 femtosecond laser 30 electromagnetic wave detection unit 31 detector 40 delay unit 41 delay stage 43 delay stage drive unit 50 stage drive unit 60 ion application unit 61 discharge electrode 63 power supply unit 70 control unit 701 Ion application control unit 702 Stage drive control unit 703 Delay stage drive control unit 704 Time waveform restoration unit 705 Comparison evaluation unit 706 Time setting unit 707 Image generation unit 72 Storage unit 74 Display unit 76 Operation unit 9 Semiconductor sample 91 p-type silicon layer 93 n-type silicon layer 95 passivation film 97 pn junction 900 solar cell module LP1 pulse light LP11 inspection light LP21 detection light LT1 electromagnetic wave TW10, TW12, TW20, TW22 time waveform WID1, WID2 electromagnetic wave intensity distribution image

Claims

A semiconductor inspection apparatus for inspecting a semiconductor sample on the surface of which a passivation film having a fixed charge is formed,
A sample holding unit for holding the semiconductor sample;
An ion applying unit performing a process of applying ions to the passivation film;
A light irradiator for irradiating an inspection light for generating an electromagnetic wave on the semiconductor sample;
A detector for detecting the electromagnetic wave emitted by the semiconductor sample in response to the irradiation of the inspection light;
A comparative evaluation unit that evaluates the characteristics of the passivation film by comparing each of the electromagnetic waves emitted by the semiconductor sample before the treatment by the ion application unit and after a predetermined time t after the ion application and after the treatment. When,
A semiconductor inspection apparatus comprising:
The semiconductor inspection apparatus according to claim 1, wherein
A scanning mechanism for scanning the surface of the semiconductor sample with inspection light emitted from the light irradiator;
The semiconductor inspection apparatus further comprising:
The semiconductor inspection apparatus according to claim 2, wherein
The ion applying unit is
An application area displacement mechanism which displaces the area to which the ions are applied relative to the surface of the semiconductor sample,
The semiconductor inspection apparatus further comprising:
The semiconductor inspection apparatus according to any one of claims 1 to 3, wherein
A control unit that controls the ion applying unit and the light emitting unit;
A time setting unit configured to set the time t based on a predetermined operation input;
Equipped with
The control unit
The semiconductor inspection apparatus which makes the said light irradiation part irradiate the said inspection light after the said time t set by the said time setting part after the said ion provision part applies the said ion.
The semiconductor inspection apparatus according to any one of claims 1 to 4, wherein
An ion applying condition setting unit that sets application conditions of the ions to be applied by the ion applying unit based on a predetermined operation input,
The semiconductor inspection apparatus further comprising:
The semiconductor inspection apparatus according to any one of claims 1 to 5, wherein
The ion applying unit is
Needle-like discharge electrodes,
And a power supply unit that applies a voltage capable of discharging the discharge electrode to the discharge electrode.
The semiconductor inspection apparatus according to any one of claims 1 to 6, wherein
The inspection light is pulsed light,
The detector includes a photoconductive antenna that detects the intensity of the electromagnetic wave in response to the incidence of pulse light for detection.
The semiconductor inspection apparatus
A delay unit that delays an input time of the pulse light for detection with respect to the electromagnetic wave incident on the photo conductive antenna;
The semiconductor inspection apparatus further comprising:
The semiconductor inspection apparatus according to any one of claims 1 to 7, wherein
The ion applying unit applies ions of the opposite sign to the fixed charge,
The said comparison evaluation part evaluates the characteristic of the said passivation film based on the code | symbol of the polarity of the said electromagnetic waves, The semiconductor test | inspection apparatus.
The semiconductor inspection apparatus according to claim 8, wherein
The passivation film comprises silicon nitride,
The semiconductor inspection device, wherein the ion applying unit is configured to be capable of applying ions of a charge density of −1 × 10 13 q / cm 2 or less.
The semiconductor inspection apparatus according to any one of claims 1 to 9, wherein
The semiconductor inspection apparatus whose part in the said sample holding part which contacts the said semiconductor sample is resin.
A semiconductor inspection method for inspecting a semiconductor sample on the surface of which a passivation film having a fixed charge is formed,
(A) irradiating the inspection light to the semiconductor sample to detect the intensity of an electromagnetic wave emitted by the semiconductor sample;
(B) performing a process of applying ions to the passivation film after the step (a);
(C) irradiating the inspection light to the semiconductor sample after the step (b), and detecting the intensity of the electromagnetic wave emitted by the semiconductor sample in response to the irradiation emitted by the semiconductor sample;
(D) evaluating the characteristics of the passivation film in the semiconductor sample by comparing each of the electromagnetic waves detected in the step (b) and the step (d);
Semiconductor inspection methods, including: