JPH11311611A - Electron spectroscopic analysis method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron spectroscopic analysis method, whereby a sample surface is prevented from being charged by an excitation source irradiation the sample, thereby enabling correct analyses. SOLUTION: A conductive film 5 is formed on a sample 1, where an insulating foreign matter 4 is present on an insulating film 3 on a substrate 2. Only the conductive film 5 on the foreign matter 4 are irradiated by ion beams 6 to remove the conductive film 5. The conductive film 5 is electrically connected to a stage 7 at a ground potential. An is the foreign matter 4 is irradiated by an electron beam 9. Auger electrons 10 emitted from the foreign matter 4 are detected to carry out an Auger electron spectroscopic analysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electron spectroscopy, and more particularly to a technique for preventing electrification in the method.

[0002]

2. Description of the Related Art In the production of liquid crystal display elements (ie, liquid crystal display panels or LCDs (liquid crystal displays)) and semiconductor devices, various thin films are deposited on a substrate, processed into a predetermined pattern, and sequentially processed. Form the required film.

For example, of two liquid crystal display substrates constituting an active matrix type liquid crystal display element having a TFT (thin film transistor) as a switching element,
In a process of forming an FT substrate (a substrate on which a TFT is formed), each thin film such as a gate wiring, a gate insulating film, a semiconductor film, a drain wiring, a pixel electrode, and a protective film is generally formed, and a photolithography process is performed. Is used to process each thin film into a predetermined pattern. In this photolithography step, deposition and development of a resist film, wet or dry etching of each thin film, and the like are performed.

In these steps, several μm to
Various foreign substances of about several hundred μm may be formed (for example, remaining film-forming substance), and a defect may occur due to the presence of the foreign substances. It needs to be analyzed. Conventionally, electron spectroscopy has been used to perform this analysis. Electron spectroscopy includes Auger electron spectroscopy and X-ray photoelectron spectroscopy.

Auger electron spectroscopy, as generally known, is a type of electron spectroscopy, usually 3 to 25 k.
By irradiating the sample surface with an electron beam of about eV, detecting Auger electrons emitted by the Auger effect, measuring the energy inherent in the substance, and analyzing the energy spectrum, the foreign substance existing near the solid surface can be detected. Elemental analysis is possible and is an established technology. The Auger electron energy spectrum changes depending on the element and its compound state, and exhibits a characteristic aspect, whereby elemental analysis can be performed. Further, the Auger effect means that when an atom in an excited state transitions to a ground state,
Instead of emitting a photon of energy equal to the energy difference between the levels, it gives the other electrons in the atom that energy and returns non-radiatively to the ground state, in which a single electron is emitted. is there.

In X-ray photoelectron spectroscopy using X-rays instead of an electron beam as an excitation source, X-rays are used.
The sample is irradiated with a line, and the energy of photoelectrons emitted from the surface of the sample is analyzed.

[0007]

When performing Auger electron spectroscopic analysis or the like, if foreign matter on the sample surface is insulating and the foreign matter is present on an insulating material such as an insulating film, the electron irradiation on the sample is performed. The sample surface is charged by the incident electrons of the beam,
There has been a problem that the measured value of the energy changes, so that an accurate energy spectrum cannot be obtained or that a normal measurement of the energy spectrum becomes difficult.

An object of the present invention is to provide an electron spectroscopic analysis method capable of preventing the charging of a sample surface due to the influence of an excitation source irradiating the sample and performing accurate analysis.

[0009]

In order to solve the above-mentioned problems, an electron spectroscopy method according to the present invention comprises exposing a surface of an insulating analyzing portion of a sample and forming a conductive film around the analyzing portion. ,
Electron spectroscopy is performed with the conductive film connected to a ground potential.

In addition, a conductive film is formed on a region including an analysis portion on an insulating film of a sample, and the conductive film of the analysis portion is selectively removed to expose a surface of the analysis portion, and the conductive film is formed. Is connected to a ground potential to perform electron spectroscopic analysis.

The conductive film is formed by a sputtering method or a vacuum evaporation method. As the conductive film, various conductive films such as a carbon film, a platinum film, a chromium film, a molybdenum film, and an aluminum film can be used.

Further, in order to selectively remove the conductive film in the analysis section, an ion beam is selectively irradiated to the analysis section. At this time, a conductive ion beam of gallium or the like is selectively irradiated and removed, and conductive ions are implanted into a surface region of the analysis unit.

In the electron spectroscopy of the present invention, the surface of the insulating foreign matter to be analyzed is exposed, and a conductive film is formed around the surface and connected to the ground potential, so that the incident electrons of the electron beam are grounded through the conductive film. Since the charge escapes to the potential, charging of the sample surface due to irradiation of the excitation source can be prevented. Therefore, electron spectroscopy can be accurately performed.
In addition, by selectively irradiating the analyzer with a conductive ion beam such as gallium to remove the conductive film of the analyzer, and by implanting conductive ions into the surface area of the analyzer, the antistatic effect can be enhanced. it can.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings described below, those having the same functions are denoted by the same reference numerals, and the repeated description thereof will be omitted.

1 (a) to 1 (c) are schematic sectional views showing the steps of Auger electron spectroscopy according to an embodiment of the present invention.

In FIG. 1A, 1 is a sample, 2 is a substrate (eg, a glass substrate in the case of a liquid crystal display element, a semiconductor wafer in the case of a semiconductor device), and 3 is an insulating film formed on the substrate 2 Reference numeral 4 denotes an insulating foreign substance such as an organic substance (for example, carbon or a carbon compound) to be subjected to Auger electron spectroscopic analysis.

First, as shown in FIG. 1B, a film forming apparatus is formed on the entire surface of an insulating film 3 provided on a substrate 2 or on a predetermined region including a portion where a foreign substance 4 is present (referred to as an analysis section). Is used to form the conductive film 5. As the conductive film 5, various conductive films such as a carbon film, a platinum film, a chromium film, a molybdenum film, and an aluminum film can be used, and the film thickness is, for example, 10 nm. As a method for forming the conductive film 5, a sputtering method, a vacuum evaporation method, or the like can be used.

Next, while monitoring with a scanning electron microscope (SEM) using an ion milling (ion thinning) apparatus or the like, as shown in FIG. Ion beam 6 only on conductive film 5
Is selectively irradiated. In order to selectively irradiate the ion beam 6 only to the analysis unit, as shown in (b), the ion beam 6 may be irradiated only to the analysis unit using a focused ion beam device or the like, or may correspond to the analysis unit. Using a mask (not shown) having an opening having a size to be measured, the mask is placed so that the opening is located at the analysis section by monitoring with a scanning electron microscope, and the ion beam 6 is irradiated through the mask. Is also good.

By this irradiation, as shown in (c), the conductive film 5 on the foreign material 4 is selectively removed, and the surface of the foreign material 4 is exposed. Further, when the conductive film 5 of the analysis section is removed, when a conductive ion beam such as gallium (Ga) is irradiated, the conductive film 5 is removed and the conductive foreign matter 4 such as gallium (Ga) is Is driven. Thereby, the antistatic effect can be further enhanced.

Next, as shown in FIG.
Is set in a stage 7 in a scanning Auger electron spectrometer (to be described later with reference to FIG. 2), and the conductive film 5 provided on the substrate 2 is connected to the ground potential. The conductive film 5 is connected to the ground potential using, for example, an electrical connection means 8 such as a silver paste adhesive or a conductive wire.

Next, as shown in FIG. 3C, the analyzer is irradiated with the electron beam 9, the Auger electrons 10 emitted from the analyzer are detected, and Auger electron spectroscopy is performed.

As described above, when performing an Auger electron spectroscopic analysis of the insulating foreign material 4 present on the insulating film 3, the surface of the foreign material 4 is exposed, and a conductive film 5 is formed around the surface of the foreign material 4 to form an electrical connection means. By connecting to the ground potential of the stage 7 and the like via the 8, the incident electrons incident on the foreign matter 4 escape to the ground potential through the conductive film 5, so that the surface of the sample 1 is prevented from being charged by the incident electrons and accurate. An energy spectrum is obtained, and Auger electron spectroscopy can be accurately performed.

FIG. 2 is a diagram showing an example of the basic configuration of a scanning Auger electron spectrometer.

11 is a scanning Auger electron spectrometer,
Reference numeral 12 denotes an electron gun as an electron beam source, 13 denotes an electron beam irradiation / scanning device that irradiates and scans an electron beam 9 generated from the electron gun 12, and 14 denotes a super-equipped with a sample stage 7 on which the sample 1 is placed. A high vacuum sample chamber, 15 is an Auger electron detector, 16 is an Auger electron signal processing system, 18 is a microbeam ion gun, 19 is a secondary electron detector, and 20 is a secondary electron signal processing system.

That is, of the conductive film provided on the entire surface of the sample 1 having the insulating film on the surface, the microbeam ion gun 18 irradiates only the analysis portion with the ion beam and removes the ion beam. Auger electrons generated by the irradiation of the electron beam 9 are detected by an Auger electron detector 15 and enter an Auger electron signal processing system 16 to obtain an Auger spectrum, a depth profile, and an Auger image 17. Secondary electrons generated by the irradiation of the electron beam 9 are detected by a secondary electron detector 19, enter a secondary electron signal processing system 20, and a secondary electron image 21 of the surface of the sample 1 is obtained. Based on this, selective irradiation of one surface of the sample with the ion beam by the micro beam ion gun 18 is performed.

Next, as an example of an object to be analyzed by the electron spectroscopy according to the present invention, a structure and a manufacturing process of an active matrix type color TFT liquid crystal display device will be briefly described.

<< Structure of Liquid Crystal Display Element >> FIG. 3 (a) is a cross-sectional view near the liquid crystal display element angle, FIG. 3 (b) is a cross-sectional view near the pixel portion of the matrix portion of the liquid crystal display element, and FIG. It is.

As shown in FIG. 3, a thin film transistor TFT and a transparent pixel electrode ITO1 are formed on the lower transparent glass substrate SUB1 side with respect to the liquid crystal layer LC, and a color filter FIL and a light-shielding element are formed on the upper transparent glass substrate SUB2 side. A black matrix pattern BM is formed. A silicon oxide film SIO formed by dipping or the like is provided on both surfaces of the transparent glass substrates SUB1 and SUB2.

On the inner surface (the liquid crystal LC side) of the upper transparent glass substrate SUB2, a light shielding film BM and a color filter FI are provided.
L, protective film PSV2, common transparent pixel electrode ITO2 (CO
M) and an upper alignment film ORI2 are sequentially laminated.

<< Manufacturing Process >> Next, a manufacturing process of the substrate SUB1 constituting the liquid crystal display element shown in FIG. 3 will be described with reference to FIGS. In the figure,
The characters in the center are abbreviations of the process names, and the left side shows the pixel portion shown in FIG. 3B, and the right side shows the processing flow as viewed from the cross-sectional shape near the gate terminal. Except for the process D, the processes A to I are classified according to the respective photographic processes, and any cross-sectional view of each process shows a stage where the processing after the photographic process is completed and the photoresist is removed. In the present description, photographic processing refers to a series of operations from application of a photoresist to selective exposure using a mask to development thereof, and a repeated description will be omitted. The description will be given below according to the divided steps.

Step A, FIG. 4 After a silicon oxide film SIO is provided on both surfaces of a lower transparent glass substrate SUB1 made of 7059 glass (trade name) by dipping, baking is performed at 500 ° C. for 60 minutes. The film thickness is 1100Å on the lower transparent glass substrate SUB1.
The first conductive film g1 made of chromium is provided by sputtering, and after the photographic processing, the first conductive film g1 is selectively etched with a ceric ammonium nitrate solution as an etchant. Thereby, an anodized bus line SHg connecting the gate terminal GTM, the drain terminal DTM, the gate terminal GTM, a bus line SHd short-circuiting the drain terminal DTM, and an anodized pad (not shown) connected to the anodized bus line SHg. To form

Step B, FIG. 4 Al-Pd, Al-Si, Al-S having a thickness of 2800 °
Second conductive film g2 made of i-Ti, Al-Si-Cu, or the like
Is provided by sputtering. After the photographic processing, the second conductive film g2 is selectively etched with a mixed acid solution of phosphoric acid, nitric acid, and glacial acetic acid.

Step C, FIG. 4 After photographic processing (after forming the above-described anodic oxidation mask AO), 3
The substrate SUB1 is immersed in an anodic oxidizing solution consisting of a solution prepared by diluting a solution obtained by adjusting a pH of 6.25 ± 0.05% with ammonia to 1:25 with an ethylene glycol solution, and the formation current density is 0.5 mA / cm. ² so as to adjust (constant current Kasei). Next, anodic oxidation is performed until the formation voltage 125 V necessary for obtaining a predetermined Al ₂ O ₃ film thickness is reached.
Thereafter, it is desirable to hold this state for several tens of minutes (constant voltage formation). This is important for obtaining a uniform Al ₂ O ₃ film. Thereby, the conductive film g2 is anodized, and the scanning signal line GL, the gate electrode GT, and the electrode PL1 are oxidized.
An anodic oxide film AOF having a thickness of 1800 ° is formed thereon.

Step D, FIG. 5 Ammonia gas, silane gas, and nitrogen gas are introduced into the plasma CVD apparatus to provide a 2000-nm thick Si nitride film, and silane gas and hydrogen gas are introduced into the plasma CVD apparatus. After providing an i-type amorphous Si film having a thickness of 2000 °, a hydrogen gas and a phosphine gas are introduced into a plasma CVD apparatus to form an N ⁺ -type amorphous Si film having a thickness of 300 °.

Step E, FIG. 5 After photographic processing, SF ₆ and CC are used as dry etching gases.
By selectively etching the N ⁺ -type amorphous Si film and the i-type amorphous Si film using l ₄ , the i-type semiconductor layer AS
Form an island.

Step F, FIG. 5 After the photographic processing, the Si nitride film is selectively etched using SF ₆ as a dry etching gas.

Step G, FIG. 6 A first conductive film d1 made of an ITO film having a thickness of 1400 ° is provided by sputtering. After the photographic processing, the first conductive film d1 is selectively etched with a mixed acid solution of hydrochloric acid and nitric acid as an etchant, thereby forming the uppermost layer of the gate terminal GTM and the drain terminal DTM and the transparent pixel electrode ITO1.
To form

Step H, FIG. 6 A second conductive film d2 made of Cr having a thickness of 600 ° is provided by sputtering, and a second conductive film d2 having a thickness of 4000 ° is further formed.
Pd, Al-Si, Al-Si-Ti, Al-Si-C
A third conductive film d3 made of u or the like is provided by sputtering. After the photographic processing, the third conductive film d3 is etched with the same liquid as in the step B, and the second conductive film d2 is etched with the same liquid as in the step A to form the video signal line DL, the source electrode SD1, and the drain electrode SD2. I do. Next, CCl ₄ and SF ₆ are introduced into a dry etching apparatus, and N ⁺ type amorphous Si is introduced.
By etching the film, the N ⁺ type semiconductor layer d0 between the source and the drain is selectively removed.

Step I, FIG. 6 An ammonia gas, a silane gas, and a nitrogen gas are introduced into a plasma CVD apparatus to form a 1 μm-thick Si nitride film. After the photo processing, the protective film PSV1 is formed by selectively etching the Si nitride film by a photo etching technique using SF ₆ as a dry etching gas.

Various insulating films generated during the manufacturing process of the two transparent glass substrates SUB1 and SUB2 constituting the liquid crystal display element as shown in FIG. 3, for example, a silicon oxide film SIO and an anodic oxide film AOF of the substrate SUB1 , Gate insulating film G
I, protective film PSV1, alignment film ORI1, silicon oxide film SIO of substrate SUB2, black matrix BM formed of black resin film, color filter film FIL, color filter protection film PSV2, insulating foreign material on alignment film ORI2 Can be accurately performed by using the electron spectroscopy of the embodiment shown in FIG.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the gist of the present invention. It is. For example, the analysis target of the electron spectroscopic analysis method of the present invention includes, in addition to the active matrix type liquid crystal display elements shown in FIGS. 3 to 6, simple matrix type liquid crystal display elements, semiconductor elements such as LSIs, optical elements, and magnetic elements. The present invention is applicable to various elements such as a body element, a magneto-optical element, and a molecular recognition element. Also, the sample 1 shown in FIG.
In the above, the foreign substance 4 on the insulating film 3 provided on the substrate 2 was analyzed. However, the present invention can be applied to the analysis of the foreign substance on the insulating substrate.

[0042]

As described above, according to the electron spectroscopy of the present invention, it is possible to prevent the surface of the sample from being charged by the excitation source irradiating the sample, and to perform the electron spectroscopy accurately. .

[Brief description of the drawings]

1 (a) to 1 (c) are schematic cross-sectional views of main steps in Auger electron spectroscopy according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a basic configuration of a scanning Auger electron spectrometer.

FIG. 3 is a cross-sectional view of a main part of an active matrix type liquid crystal display element as an example of an inspection target of the electron spectroscopic analysis according to the present invention, showing a panel corner and a video signal terminal on both sides with a pixel portion of a matrix in the center. FIG.

4 is a flowchart of a cross-sectional view of a pixel portion and a gate terminal portion showing a manufacturing process of processes A to C on the substrate SUB1 side shown in FIG.

FIG. 5 is a flowchart of a cross-sectional view of a pixel portion and a gate terminal portion showing a manufacturing process of processes D to F on the substrate SUB1 side.

FIG. 6 is a flowchart of a cross-sectional view of a pixel portion and a gate terminal portion showing a manufacturing process of processes G to I on the substrate SUB1 side.

[Explanation of symbols]

1 ... sample, 2 ... substrate, 3 ... insulating film, 4 ... insulating foreign matter, 5
... conductive film, 6 ... ion beam, 7 ... stage, 8 ... electric connection means, 9 ... electron beam, 10 ... Auger electron.

Claims (8)

[Claims] An electron spectroscopy is performed in a state where a surface of an insulating analysis portion of a sample is exposed, a conductive film is formed around the analysis portion, and the conductive film is connected to a ground potential. Electron spectroscopy. 2. A conductive film is formed on a region including an analysis portion on an insulating film of a sample, and the conductive film of the analysis portion is selectively removed to expose a surface of the analysis portion. An electron spectroscopy method, wherein is connected to a ground potential and electron spectroscopy is performed. 3. An electron spectroscopic analysis method according to claim 1, wherein said conductive film is formed by a sputtering method or a vacuum evaporation method. 4. The method according to claim 1, wherein the conductive film is a carbon film, a platinum film, a chromium film, a molybdenum film, or an aluminum film. 5. The electron spectroscopic analysis method according to claim 2, wherein the selective removal of the conductive film of the analysis section is performed by selectively irradiating the analysis section with an ion beam. . 6. When selectively removing the conductive film of the analysis section, the conductive ion beam is selectively irradiated to the analysis section to remove the conductive film, and conductive ions are deposited on a surface region of the analysis section. 3. The method according to claim 2, wherein the method is performed. 7. The method according to claim 6, wherein said conductive ion is gallium. 8. The method according to claim 1, wherein the sample is a liquid crystal display substrate.