Radiant energy – Inspection of solids or liquids by charged particles – Electron probe type
Reexamination Certificate
2000-01-27
2001-10-30
Arroyo, Teresa M. (Department: 2881)
Radiant energy
Inspection of solids or liquids by charged particles
Electron probe type
C250S310000, C250S294000, C250S299000, C250S427000, C250S492300
Reexamination Certificate
active
06310343
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hydrogen atom analyzer for analyzing hydrogen distribution in a specimen containing hydrogen. More particularly, the present invention relates to an electron impact elastic recoil hydrogen atom analyzer for analyzing hydrogen distribution in a specimen containing hydrogen by measuring elastic recoil hydrogen atoms emitted from the specimen by electron impact.
2. Description of the Related Art
Hydrogenated semiconductors containing hydrogen are used prevalently as materials for solar cells, liquid crystal displays, video cameras, telecopying sensors and the like. Quality improvement of such hydrogenated semiconductors has become important in recent years. Accurate analysis of hydrogen distribution at the surface and interior places of a sample hydrogenated semiconductor, and the accurate control of hydrogen distribution in the hydrogenated semiconductor are very important for the improvement of the quality of the hydrogenated semiconductor. Practically, it is desirable that the analysis of hydrogen distribution in the sample can simply be achieved and that manufacturing conditions for manufacturing the hydrogenated semiconductor can precisely be controlled through the in situ observation of the manufacturing process.
Incidentally, an Auger electron spectrometric method is a generally known surface analyzing method for analyzing the surface of a specimen, capable of simply achieving the qualitative and quantitative analysis of elements in the surface of a specimen through in situ observation. Although the Auger electron spectrometric method is applied to the analysis of elements from lithium of atomic number
3
through uranium of atomic number
92
, the same cannot be applied to the analysis of hydrogen of atomic number
1
.
Generally known surface analyzing methods applied to the analysis of specimens containing hydrogen include a secondary ion mass spectrometric method, an infrared absorption method, a high-speed ion impact recoil method, a nuclear reaction spectrometric method and an electron impact hydrogen desorption method. The secondary ion mass spectrometric method bombards the surface of a specimen by primary ions, such as cesium ions, and detects hydrogen ions sputtered as secondary ions from the surface of the specimen by a mass spectrometric method. The infrared absorption method detects hydrogen ions by using an infrared absorption spectrum. The high-speed ion impact recoil method bombards the surface of a specimen by high-speed ions accelerated by an accelerator and detects recoil hydrogen ions sputtered from the surface of the specimen. The nuclear reaction spectrometric method bombards the surface of a specimen by high-speed nitrogen ions and detects a rays emitted from the surface of the specimen by nuclear reaction. The electron impact hydrogen desorption method excites a molecular orbital of hydrogens and host atoms by bombardment with electrons with an energy on the order of 200 eV to cut the bonds between hydrogens and host atoms and detects hydrogen ions of 2 to 3 eV desorbed from the specimen.
The secondary ion mass spectrometric method is unable to achieve analysis through in situ observation. A hydrogen concentration measured by the infrared absorption method includes an error as large as 50% and the infrared absorption method is incapable of accurate analysis.
The high-speed ion impact recoil method and the nuclear reaction spectrometric method do not have drawbacks as those of the secondary ion mass spectrometric method and the infrared absorption method and are capable of accurately determining hydrogen distribution inside the specimen over the depth of about 1 &mgr;m with a depth resolution in the range of 50 to 500 Å. However, these two methods, unlike the Auger electron spectrometric method, need a large apparatus like an accelerator and cannot be easily equipped and handeld.
The electron impact hydrogen desorption method does not have any drawbacks like those in the secondary ion mass spectrometric method and the infrared absorption method and is capable of accurate, simple analysis through in situ observation. However, the electron impact hydrogen desorption method is able to analyze only a very thin hydrogen-containing layer of a thickness in the range of 2 to 3 Å and is incapable of analyzing inside of the specimen containing hydrogen.
SUMMARY OF THE INVENTION
The present invention has been made in view of those problems and it is therefore an object of the present invention to provide an electron impact elastic recoil hydrogen atom analyzer capable of achieving accurate depth distribution analysis of a specimen containing hydrogen through in situ observation.
According to one aspect of the present invention, an electron impact elastic recoil hydrogen atom analyzer comprises an electron beam projecting unit that projects an electron beam on the surface of a specimen containing hydrogen, for electron bombardment to make recoil hydrogen atoms emit from the specimen, and a hydrogen detecting unit that detects hydrogen atoms emitted from the specimen. Preferably, the electron impact elastic recoil hydrogen atom analyzer further comprises a data processing unit that determines the depth-distribution of hydrogen atoms contained in the specimen.
According to the present invention, the surface of the specimen is irradiated with the electron beam and energy distribution in the recoil hydrogen atoms emitted from the specimen is measured. Thus, hydrogen atoms contained in the specimen can accurately and easily be analyzed through practically useful in situ observation. Since the depth-distribution of hydrogen atoms in the specimen is determined on the basis of the result of detection, the hydrogen atoms contained inside the specimen, as well as those contained in a surface layer of the specimen, can accurately be analyzed with an appropriate depth resolution.
REFERENCES:
patent: 4352985 (1982-10-01), Martin
patent: 4393311 (1983-07-01), Feldman et al.
patent: 5528034 (1996-06-01), Yamazaki et al.
Horiki Tsuyoshi
Koyama Akio
Yoneda Akira
Arroyo Teresa M.
Jacobson & Holman PLLC
Quash Anthony
Riken
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