Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
1999-05-18
2001-10-09
Turner, Archene (Department: 1775)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S698000, C117S012000, C117S013000
Reexamination Certificate
active
06299982
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a silicon single crystal wafer wherein a size of crystal defect inside the crystal, called grown-in defect, is decreased to the smallest by doping nitrogen and optimizing a cooling rate, a nitrogen concentration and an oxygen concentration when pulling a silicon single crystal by a Czochralski method (hereinafter referred to as “CZ method”), and a method for producing it.
2. Description of the Related Art
As a wafer for fabrication of a device such as a semiconductor integrated circuit, a silicon single crystal wafer grown by a Czochralski method (CZ method) is mainly used. If crystal defects are present in such a silicon single crystal wafer, pattern failure is caused when a semiconductor device is fabricated. Particularly, the pattern width of devices which is highly integrated in recent years is very fine as 0.3 &mgr;m or less. Accordingly, even small crystal defects as 0.1 &mgr;m may cause defects such as pattern failures in the device, and may remarkably lower a yield and characteristics of the device. Accordingly, a size of the crystal defects in the silicon single crystal wafer have to be decreased as thoroughly as possible.
Recently, it has been reported that the above-mentioned crystal defects called grown-in defect incorporated during growth of the crystal are found in the silicon single crystal grown by CZ method by various measurement methods. For example, these crystal defects in a single crystal grown at a general growth rate in commercial production (for example, about 1 mm/min or more) can be detected as a pit by subjecting the surface of the crystal to preferential etching (Secco etching) with Secco solution (a mixture of K
2
Cr
2
O
7
, hydrofluoric acid and water) (See Japanese Patent Application Laid-open (kokai) No.4-192345).
The main cause of generation of such a pit is considered to be a cluster of vacancies which are aggregated during manufacture of single crystal or an oxide precipitate which is an agglomerate of oxygen atoms getting in from a quartz crucible. When these crystal defects are present in the surface portion (at a depth of 0 to 5 &mgr;m) in which a device is fabricated, they come to harmful defect to degrade characteristics of the device.
Accordingly, it is desirable to reduce these crystal defects.
For example, it is known that a concentration of the above-mentioned cluster of vacancies can be lowered by decreasing a growth rate of the crystal extremely (for example, to 0.4 mm/min or less) (See Japanese Patent Application Laid-open (kokai) No.2-267195). However, adopting this method, there is generated a crystal defect which is considered to be a dislocation loop formed as a result of new aggregation of excess interstitial silicon atoms, which may degrade characteristics of a device significantly. Accordingly, the problem cannot be solved by the method. Furthermore, productivity of the single crystal and cost performance are extremely decreased in the method, since the growth rate of the crystal is decreased from about 1.0 mm/min as usual or more to 0.4 mm/min or less.
SUMMARY OF THE INVENTION
The present invention has been accomplished to solve the above-mentioned problems, and the prime object of the present invention is to provide in high productivity by CZ method a silicon single crystal wafer for a device wherein formation of crystal defects is suppressed.
To achieve the above object, the present invention provides a silicon single crystal wafer produced by processing a silicon single crystal ingot grown by Czochralski method with doping nitrogen, characterized in that a size of grown-in defects in the silicon single crystal wafer is 70 nm or less.
As described above, when the silicon single crystal wafer is produced by processing a silicon single crystal ingot grown by Czochralski method with doping nitrogen, the size of Grown-in defect in the wafer can be reduced to 70 nm or less. Since such a fine crystal defect hardly gives a harmful influence on fabrication of the device, the silicon single crystal wafer can be improved yield and quality of device.
Preferably, in the silicon single crystal wafer produced by processing a silicon single crystal ingot grown by Czochralski method with doping nitrogen, the silicon single crystal ingot is grown with controlling a rate of cooling from 1150 to 1080° C. to be 2.3° C./min or more.
As described above, in the silicon single crystal wafer produced by processing a silicon single crystal ingot grown by CZ method with doping nitrogen, grown-in defects present on the wafer is very few due to presence of doped nitrogen. When the crystal ingot is grown with controlling the rate of cooling from 1150° C. to 1080° C. at 2.3° C./min or more, the size of the crystal defects can be extremely decreased to have almost no harmful influence on fabrication of the device. Furthermore, since growth of crystal defects can be suppressed, it is possible to grow crystal at high speed, so that productivity can also be improved.
In the above case, the nitrogen concentration in the above-mentioned silicon single crystal wafer is preferably in the range of 0.2 to 5×10
15
atoms/cm
3
.
In order to suppress growth of crystal defect, the nitrogen concentration is preferably 1×10
10
atoms/cm
3
or more. In order not to prevent crystallization of single crystal, the nitrogen concentration is preferably 5×10
15
atoms/cm
3
or less. However, the nitrogen concentration in the range of 0.2 to 5×10
15
atoms/cm
3
is the most effective for suppression of growth of crystal defects, and therefore growth of crystal defects can be sufficiently suppressed when the nitrogen concentration is in the range.
During growth of the silicon single crystal ingot by Czochralski method with doping nitrogen, a concentration of oxygen in the single crystal ingot is preferably controlled to be 1.0×10
18
atoms/cm
3
(ASTM '79 value) or less. When the oxygen concentration is low as above, growth of the crystal defects can be further suppressed, and formation of oxide precipitates in the surface layer can be prevented.
A silicon single crystal wafer as described above has very few crystal defects on the surface. Particularly, since the density of the crystal defects can be decreased to 40 number/cm
2
or less, yield can be improved significantly in fabrication of the device so that productivity of the crystal can be significantly improved.
The present invention also provides a method for producing a silicon single crystal wafer wherein a silicon single crystal ingot is grown with doping nitrogen and controlling a rate of cooling from 1150 to 1080° C. to be 2.3° C./min or more, and is then processed to provide a silicon single crystal wafer.
As described above, in CZ method for growing a silicon single crystal ingot, growth of crystal defects incorporated during growth of crystal can be suppressed by doping nitrogen. Furthermore, since growth of crystal defects can be suppressed by growing crystal with controlling a rate of cooling from 1150 to 1080° C. to be 2.3° C./min or more, crystal defects become very fine. Since growth of the crystal defects can be significantly suppressed, crystal can be grown at high speed, so that productivity of the crystal can be significantly improved.
The nitrogen concentration doped in the single crystal ingot is preferably 0.2 to 5×10
15
atoms/cm
3
. The concentration of oxygen in the single crystal ingot is preferably 1.0×10
18
atoms/cm
3
or less.
As described above, when cooling is performed at high speed and the concentration of doped nitrogen and the concentration of oxygen are controlled to be in the optimum range in production of silicon single crystal by CZ method with doping nitrogen, the silicon single crystal wafer having high quality and few crystal defects can be produced in high productivity.
In the silicon single crystal wafer produced by processing a silicon single crystal ingot grown by Czochralski method with doping nitrogen, a size of grown-in defects in the silic
Iida Makoto
Kimura Akihiro
Miki Katsuhiko
Tamatsuka Masaro
Hogan & Hartson L.L.P.
Shin-Etsu Handotai & Co., Ltd.
Turner Archene
LandOfFree
Silicon single crystal wafer and method for producing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Silicon single crystal wafer and method for producing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Silicon single crystal wafer and method for producing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2579696