Use of specific resistivity measurement for indirect determination of the purity of silanes and germanes and a corresponding process
View Patent ↗The invention relates to a method for indirectly determining the purity of silanes and germanes using a device for measuring specific resistance. The invention further relates to a system for industrially producing and/or filling containers with silanes or germanes, including a quality control in which a device is used for measuring specific resistance.
1. A process for indirectly determining purity, the process comprising:
industrially producing and/or dispensing a silane or germane comprising impurities from main groups 3 and 5 of the periodic chart;
extracting an amount of the silane or germane from the production and/or dispensing;
depositing, by chemical vapour deposition, a silicon layer or a germanium layer on a surface of a silicon or germanium wafer with at least a portion of the extracted amount of the silane or germane in a gaseous state, wherein the silicon layer or the germanium layer comprises impurities from main groups 3 and 5 of the periodic chart;
measuring a specific resistivity of the silicon layer or the germanium layer;
recording a profile of the specific resistivity as a function of a height of the silicon or germanium layer by repeated measurement at different heights of the layer, measured from an original wafer surface; and
determining the purity based on the specific resistivity and at least one reference value, wherein specific resistivities measured and recorded as a function of layer height are attributed to a degree of purity, wherein the purity relates to a total content of elements of main groups 3 and 5, including an attribution to main group 3 and/or 5.
2. The process according to claim 1 , comprising depositing the silicon layer with the gaseous silane to determine the purity of the silane,
wherein the silane is an unsubstituted mono-, di- or trisilane; or a singly, multiply or fully halogen-substituted mono-, di- or trisilane.
3. The process according to claim 1 , wherein the purity includes an attribution to main group 3.
4. The process according to claim 1 , wherein the purity includes an attribution to main group 5.
5. The process according to claim 1 , comprising depositing the silicon layer with the gaseous silane onto the silicon wafer to determine the purity of the silane.
6. The process according to claim 5 , wherein:
the silicon wafer is a doped wafer having a specific resistivity of <1000 Ωcm, and the silicon layer has a thickness of 5 to 100 μm; or
the silicon wafer is a lightly doped wafer having a specific resistivity of >1000 Ωcm, and the silicon layer has a thickness of 1 to 50 μm.
7. The process according to claim 1 , wherein the process occurs repeatedly during the industrial production and/or dispensing.
8. The process of claim 1 , which indirectly determines the purity of silanes and germanes.
9. The process according to claim 8 , wherein the measuring of the specific resistivity occurs simultaneous with, or subsequent to, the depositing of the silicon layer or the germanium layer.
10. The process according to claim 1 , comprising depositing the germanium layer with the gaseous germane to determine the purity of the germane,
wherein the gaseous germane is: an unsubstituted mono-, di- or trigermanes; or a singly, multiply or fully halogen-substituted mono-, di- or trigermane.
11. The process according to claim 1 , comprising depositing the germanium layer with the gaseous germane onto the germanium wafer to determine the purity of the germane.
12. The process according to claim 11 , wherein:
the germanium wafer is a doped wafer having a specific resistivity of <1000 Ωcm, and the germanium layer has a thickness of 5 to 100 μm; or
the germanium wafer is a lightly doped wafer having a specific resistivity of >1000 Ωcm, and the germanium layer has a thickness of 1 to 50 μm.
13. The process according to claim 1 , comprising:
depositing a silicon layer on a surface with a gaseous silane; and then
measuring a specific resistivity of the layer and determining the purity of the silane based on the specific resistivity and at least one reference value.
14. The process according to claim 1 , comprising:
depositing a germanium layer on a surface with a gaseous germane; and then
measuring a specific resistivity of the layer and determining the purity of the germane based on the specific resistivity and at least one reference value.
15. The process according to claim 2 , wherein the gaseous silane is selected from the group consisting of SiH 4 , SiH 3 Cl, SiH 2 Cl 2 , SiHCl 3 , SiCl 4 , Si 2 H 6 , Si 2 Cl 6 , Si 3 H 8 , and Si 3 Cl 8 .
16. The process according to claim 10 , wherein the gaseous germane is selected from the group consisting of GeH 4 and GeCl 4 .
17. The process according to claim 1 , wherein the purity includes an attribution to main group 3 and main group 5.
18. The process according to claim 1 , wherein the thickness of the silicon layer or the germanium layer is such that the specific resistivity measured is influenced exclusively by the extracted silane or germane employed in the chemical vapour deposition.