Semiconductor device manufacturing: process – With measuring or testing
Reexamination Certificate
1998-10-20
2001-02-13
Bowers, Charles (Department: 2813)
Semiconductor device manufacturing: process
With measuring or testing
C134S002000, C148S033200
Reexamination Certificate
active
06187600
ABSTRACT:
This application Is based on Japanese patent application Hei 10-119254 filed on Apr. 28, 1998, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a silicon substrate evaluation method, and more particularly to a silicon substrate evaluation method which can prevent a lowering of the yield of semiconductor IC devices.
2. Description of the Related Art
With the recent high-density integration and miniaturization of dynamic random access memories (DRAMs), etc., it has been strongly required to reduce a microscopic warp which occurs in the surfaces of silicon substrates while being processed, as well as crystal defects in the silicon substrates and the surface contamination of the silicon substrates. The techniques for evaluating the microscopic warp, the crystal defects and the surface contamination in advance are needed.
According to one known method for evaluating any crystalline imperfection in a silicon substrate surface, an oxide film is removed after an oxidization process, etching is conducted through the use of an acid selective etchant, and thereafter the pits which have occurred in the substrate surface are detected. According to another known method for evaluating the crystalline imperfection, the half width of the rocking curve, obtained by the X-ray diffraction of the surface layer portion of a silicon substrate, is measured.
However, the crystal imperfection cannot be satisfactorily evaluated by the method adopting the acid selective etchant or the method using the rocking curve obtained by the X-ray diffraction. The presence of the crystal imperfection in the silicon substrate surface cannot be detected until any inconvenience occurs during a semiconductor IC manufacturing process.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a silicon substrate evaluation method by which the crystal quality, etc. of a silicon substrate is evaluated before a process for manufacturing semiconductor devices using such silicon substrates, in order to avoid a lowering of the yield of the semiconductor devices.
It is another object of the present invention to provide a semiconductor device manufacturing method which utilizes the aforementioned evaluation method in order to avoid a lowering of the yield of the semiconductor devices.
According to one aspect of the present invention, there is provided a method for evaluating a silicon substrate, comprising an etching step of etching a surface layer portion of the silicon substrate with a mixed solution which contains ammonium hydroxide (NH
4
OH), hydrogen peroxide (H
2
O
2
) and water (H
2
O) at a weight ratio of 1:(1.3 to 2.65):(275 to 433), and a measurement step of measuring a density of pits which have occurred in a surface of the silicon substrate subjected to the etching step.
When etching is performed using the above-described solution, pits occur in correspondence with any crystal defects, etc. By measuring the density of the pits, therefore, the crystal quality, etc. of the silicon substrate can be evaluated.
According to another aspect of the present invention, there is provided a method for evaluating a silicon substrate, comprising an etching step of etching a surface layer portion of the silicon substrate with a mixed solution which contains ammonia, hydrogen peroxide and water, a first oxidation step of oxidizing a surface of the silicon substrate subjected to the etching step, a heat treatment step of heating the silicon substrate oxidized by the first oxidation step to a temperature higher than an oxidation temperature in the first oxidation step, a second oxidation step of oxidizing the surface of the silicon substrate subjected to the heat treatment step, and a measurement step of measuring a density of pits which have occurred in the surface of the silicon substrate subjected to the second oxidation step.
Conducting the first oxidation step, the heat treatment and the second oxidation step results in the detection of the pits being facilitated so as to permit the crystal quality, etc. of the silicon substrate to be evaluated more easily.
As described above, the surface of the silicon substrate is etched with the mixed solution which contains ammonia, hydrogen peroxide and water. The silicon substrate is evaluated based on the density of the pits which have occurred in the surface. This enables any inappropriate silicon substrates, which are not proper as those for use in semiconductor devices, to be discriminated from the appropriate substrates in order to prevent a lowering of the manufacturing yield of the semiconductor devices.
REFERENCES:
patent: 3920492 (1975-11-01), Sugita et al.
patent: 3997368 (1976-12-01), Petroff et al.
patent: 5176756 (1993-01-01), Nakashima et al.
patent: 5508800 (1996-04-01), Miyashita et al.
patent: 5656097 (1997-08-01), Olesen et al.
patent: 5908509 (1999-06-01), Olesen et al.
patent: 5946543 (1999-08-01), Kimura et al.
P. Wagner, M. Brohl, D. Graf, and U. Lambert, “Surfaces and Crystal Defects of Silicon” in Materials Research Society Symposium Proceedings, vol. 378, Materials Research Society, pp. 17-22, 1995.
Werner Kern, “The Evolution of Silicon Wafer Cleaning Technology” in J. Electrochem. Soc., vol. 137(6), pp. 1887-1892, Jun. 1990.
Fujisawa Yoichi
Hikazutani Ken-ichi
Ogawa Kaoru
Armstrong, Westerman Hattori, McLeland & Naughton
Bowers Charles
Fujitsu Limited
Kielin Erik
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