Method and device for monitoring the contamination of substrate wafers
A device is used to measure contamination directly in transport enclosures of FOUP or SMIF type, for example. The transport enclosure is placed on an adapter that sets up direct communication between it and an external gas analyzer. The gas analyzer ionizes the sampled gases and performs the analysis by measuring a parameter of the ions resulting from this ionization. This measures very low levels of gaseous contamination in real time.
1. A device operable to monitor contamination of substrate wafers or other parts in semiconductor or electromechanical microsystem fabrication processes comprising:
a gas analyzer comprising means for ionizing gases and means for identifying the ionized gases by measuring a parameter of the ions, wherein the means for ionizing gases ionize gases at atmospheric pressure;
a transport enclosure for said substrate wafers and said other parts;
an interface means for establishing direct communication between said gas analyzer and an internal atmosphere of said transport enclosure; and
means for selectively injecting a purging neutral gas into said gas analyzer.
2. A device according to claim 1 , wherein said interface means are configured to convey a flow of gas to be analyzed from said internal atmosphere of said transport enclosure to said gas analyzer directly and without significant external input.
3. A device according to claim 1 , wherein said interface means comprises a material which is perfluoroalkoxy (PFA).
4. A device according to claim 1 , wherein said gas analyzer is operable to measure the mobility of said ions.
5. A device according to claim 1 , wherein said gas analyzer is operable to measure the flight time of said ions.
6. device according to claim 1 , wherein said gas analyzer is operable to measure the mass of said ions.
7. A device according to claim 4 , wherein said gases are ionized by electron bombardment.
8. A device according to claim 4 , wherein said gases are ionized by bombardment with alkaline ions that become attached to the molecules of said gases.
9. A device according to claim 1 , wherein said interface means comprises: a passage through the wall of said transport enclosure; and an adapter conformed so that said transport enclosure can be coupled to said adapter with said passage selectively placed in communication with a pipe leading to said gas analyzer.
10. A device according to claim 1 , wherein said means for selectively injecting a purging neutral gas into said gas analyzer comprises a source of nitrogen.
11. A device according to claim 1 , further comprising means for selectively setting up direct communication between an Inlet of said gas analyzer and an atmosphere surrounding said transport enclosure.
12. A device according to claim 1 , further comprising electronic control means for controlling the operation of said gas analyzer and said interface means.
13. A device according to claim 1 , further comprising electronic processing means for processing and storing measurement results supplied by said gas analyzer.
14. A device according to claim 12 , wherein said electronic control means comprises a processor and an associated program, said associated program comprising a measurement sequence in which said processor commands communication between said transport enclosure and said gas analyzer and at least one of the following sequences: a purge sequence in which said processor commands the injection of a neutral gas into said gas analyzer; a calibration sequence in which said processor commands the injection of a reference gas into said gas analyzer; and an external monitoring sequence in which said processor commands the setting up of communication between said gas analyzer and the surrounding atmosphere.
15. A device operable to monitor contamination of substrate wafers or other parts in semiconductor or electromechanical microsystem fabrication processes comprising:
a gas analyzer comprising means for ionizing gases and means for identifying the ionized gases by measuring a parameter of the ions, wherein the means for ionizing gases ionize gases at atmospheric pressure;
a transport enclosure for said substrate wafers and said other parts; and
an interface means that establishes direct communication between said gas analyzer and an internal atmosphere of said transport enclosure, and is configured to convey a flow of gas to be analyzed from said internal atmosphere of said transport enclosure to said gas analyzer; wherein the interface means comprises: (a) a passage through the wall of said transport enclosure; (b) an adapter connected to said passage which is conformed such that said wall of said transport enclosure couples to said adapter; and (c) a pipe connected to said adapter leading to said gas analyzer, wherein said adapter further comprises locating means for positioning said transport enclosure onto said adapter so that said passage faces the orifice of said pipe leading to said gas analyzer.
16. A device according to claim 15 , wherein said locating means comprises a lug adapted to engage in a corresponding hole.
17. A device according to claim 15 , wherein said adapter is integrated directly into a transport pod loading means.
18. A device operable to monitor contamination of substrate wafers or other parts in semiconductor or electromechanical microsystem fabrication processes comprising:
a gas analyzer comprising means for ionizing gases and means for identifying the ionized gases by measuring a parameter of the ions, wherein the means for ionizing gases ionize gases at atmospheric pressure;
a transport enclosure for said substrate wafers and said other parts comprising a pierceable wall; and
an interface means that establishes direct communication between said gas analyzer and an internal atmosphere of said transport enclosure, and is configured to convey a flow of gas to be analyzed from said internal atmosphere of said transport enclosure to said gas analyzer, wherein the interface means comprises a needle connected to said gas analyzer, said needle being configured to pierce said pierceable wall of said transport enclosure.
19. A method of monitoring contamination of substrate wafers or other parts in semiconductor or electromechanical microsystem fabrication processes performed in a transport enclosure, said method comprising:
a measurement step in which gases are sampled from an interior atmosphere of said transport enclosure and isolated, the sampled gases are ionized and said ionized sampled gases are analyzed by measuring a parameter of the ions obtained by the ionization by a gas analyzer; and
an external analysis step during which gases are sampled in the atmosphere surrounding said transport enclosure, the sampled gases are ionized and said sampled gases are analyzed by measuring a parameter of the ions obtained by the ionization by said gas analyzer.
20. A method according to claim 19 , further comprising a purge step during which a neutral gas is injected into said gas analyzer.
21. A method according to claim 19 , further comprising a calibration step during which a reference gas is injected into said gas analyzer.
22. A method according to claim 19 , further comprising a differential measurement sequence including measurement of the contamination in said transport enclosure before a treatment process is applied to said substrate wafers contained in said transport enclosure and measurement of the contamination in said transport enclosure after said transport process and reintroduction of the treated substrate wafers into said transport enclosure.
23. A method according to claim 19 , further comprising a preliminary monitoring step during which the contamination in the open or closed transport enclosure is measured before introducing said substrate wafers or said other parts into it.