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SEMI C56-0305 © SEMI 2005 2 Table 1 Impurity a nd Other Requirements for Various Grades of Dichlorosilane Previous SEMI Reference # C3.18-1102 (Specification) C3.31-1102 (Specification) Purity 97% 99% Impurities Maximu m…

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SEMI C56-0305 © SEMI 2005 1
SEMI C56-0305
SPECIFICATIONS AND GUIDELINES FOR DICHLOROSILANE (SiH
2
Cl
2
)
This specification was technically approved by the Global Gases Committee and is the direct responsibility of
the North American Gases Committee. Current edition approved by the North American Regional Standards
Committee on November 4, 2004. Initially available at
www.semi.org January 2005; to be published March
2005.
NOTICE: This document replaced C3.18 and C3.31 in 2005.
1 Purpose
1.1 The purpose of this document is to provide a series of specifications for different grades of dichlorosilane
(SiH
2
Cl
2
) that are used in the semiconductor industry.
2 Scope
2.1 This document covers requirements for all grades of dichlorosilane (SiH
2
Cl
2
) used in the semiconductor
industry.
2.2 If analytical methods are not complete, the requirements are presented as a guideline.
NOTICE: This standard does not purport to address safety issues, if any, associated with its use. It is the
responsibility of the users of this standard to establish appropriate safety and health practices and determine the
applicability of regulatory or other limitations prior to use.
3 Description
3.1 Dichlorosilane is a flammable, corrosive, colorless liquid which hydrolizes in the presence of moisture. It
oxidizes readily and rapidly to release hydrogen chloride. It is easily ignited in the presence of air.
4 Referenced Standards
4.1 SEMI Standards
SEMI C1 — Specifications for Reagents
SEMI C3 — Specifications for Gases
NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.
5 Terminology
5.1 Terminology appropriate to this standard is defined in SEMI C3.
6 Requirements
6.1 Purity and other requirements for the various grades of dichlorosilane are given in Table 1.
SEMI C56-0305 © SEMI 2005 2
Table 1 Impurity and Other Requirements for Various Grades of Dichlorosilane
Previous SEMI Reference #
C3.18-1102
(Specification)
C3.31-1102
(Specification)
Purity 97% 99%
Impurities Maximum Acceptable Level
#1
All Other Chlorosilanes
(Monochlorosilane, Silicon
Tetrachloride, Trichlorosilane)
3% (liquid phase) 1% (liquid phase)
#2
Aluminum 1.0 ppbw (vapor phase derived) 1.0 ppbw (vapor phase derived)
Arsenic 0.5 ppbw (vapor phase derived) 0.2 ppbw (vapor phase derived)
Boron 0.3 ppbw (vapor phase derived) 0.1 ppbw (vapor phase derived)
Carbon 10 ppmw (vapor phase derived) 1 ppmw (vapor phase derived)
Iron 50 ppbw (liquid phase) 50 ppbw (liquid phase)
Phosphorus 0.3 ppbw (vapor phase derived) 0.3 ppbw (vapor phase derived)
#1
An analysis of significant figures has not been considered. The number of significant figures will be based on analytical accuracy and the
precision of the provided procedure.
#2
Monochlorosilane not to exceed 0.5%
#3
This specification applies to the appropriate phase of the cylinder as delivered.
#4
The liquid phase purity is to be based on the chlorosilane determination. In addition, argon + helium are to be controlled in the vapor phase to
less than 0.5%. This argon + helium determination will not affect the percent purity determination.
#5
Initial purging of the vapor phase is recommended to reduce inert gas content used in the cylinder fill procedure.
#6
Analytical procedures for the doping elements, metals and selected impurities are to be determined between the user and supplier at the present
time.
7 Electrical Requirements
7.1 Electrical requirements for the various grades of dichlorosilane are given in Table 2
Table 2 Electrical Requirements for Various Grades of Dichlorosilane
Previous SEMI Reference #
C3.18-1102
(Specification)
C3.31-1102
(Specification)
Resistivity
#1
Greater than 50 ohm-cm (n-type)
#2
Greater than 150 ohm-cm (n-type)
#2
#1
The resistivity measurement technique is to be determined between supplier and user.
#2
Monocrystalline silicon formed from this material, not the material itself.
8 Physical Constants
8.1 The physical constants of dichlorosilane are given in Table 3 (for information only).
Table 3 Physical Constants of Dichlorosilane (for information only)
Metric Units US Units
Molecular weight 100.99 100.99
Boiling point at 1 atm 8.2°C 46.8°F
Density of gas at 25°C (77°F) and 1 atm 4.168 kg/m
3
0.260 lb/ft
3
Specific gravity of gas at 21.1°C (70°F) and 1 atm
(air = 1)
3.48 3.48
Density of liquid at 25°C (77°F) 122 kg/m
3
7.62 lb/ft
3
SEMI C56-0305 © SEMI 2005 3
9 Analytical Procedures for Purity of 97% of Dichlorosilane
NOTE 1: The sample is extremely flammable and corrosive. Test for leaks before sampling. Ensure good electrical grounding.
9.1 Other Chlorosilanes — This procedure is for the determination of other chlorosilanes (monochlorosilane,
trichlorosilane and silicon tetrachloride) in dichlorosilane using a gas chromatograph with a thermal conductivity
detector.
9.1.1 Detection Limit — 10 ppm.
9.1.2 Instrument Parameters
9.1.2.1 Column: 3.05 m (10 ft) by 3.2 mm (1/8 in) stainless steel tubing packed with 20% OV-101 on 80/100
Chromosorb W-HP or equivalent.
9.1.2.2 Carrier Flow: 20 mL/min helium.
9.1.2.3 Sample Volume: 0.5 to 1.0 mL.
9.1.2.4 Temperatures:
Detector 350°C
Column 60°C ramped to 325°C at 10°C/min
Inlet 300°C
9.1.3 Operating Procedure
9.1.3.1 Inject a known sample of monochlorosilane, trichlorosilane and silicon tetrachloride in dichorosilane into
the column using a gas sampling valve. Record the retention times and peak areas. The order of elution is
monochlorosilane, dichlorosilane, trichlorosilane, silicon tetrachloride.
9.1.3.2 Inject the sample to be tested in the same manner as in ¶9.1.3.1. Record the areas of the peaks which have
the same retention times as those in ¶9.1.3.1.
9.1.3.3 Repeat ¶9.1.3.1.
9.1.3.4 Calculate the purity of dichlorosilane in the sample, using the equations stated below. The result may not
exceed the specification in Table 1 of this standard.
9.1.4 Calculations
9.1.4.1 Determine the total area of the chlorosilane peaks (A
T
) by adding the areas of the four peaks.
9.1.4.2 Divide the area of the dichlorosilane peak by A
T
. Multiply the result by 100% to obtain the purity of the
dichlorosilane.
10 Analytical Procedures for Purity of 99% of Dichlorosilane (see Note 1 in §9)
10.1.1 Other Chlorosilanes — Follow the procedure in §9 except add the following calculation for
monochlorosilane.
10.1.2 Calculations for monochlorosilane
10.1.2.1 Calculate the percentage the monochlorosilane in the sample using the equation stated below. The result
may not exceed the specification in table 1 of this standard.
10.1.2.2 Divide the area of the monochlorosilane peak by A
T
. Multiply the result by 100% to obtain the percentage
of monochlorosilane.