1. A method for forming a composite semiconductor wafer in the form of a laminate from first and second wafers of semiconductor material, the method comprising the step of forming a peripheral recess in a first major surface of the first wafer adjacent a peripheral edge thereof corresponding to respective peripheral areas of the first major surfaces of the first and second wafers where a surface imperfection may occur go that the surface imperfection does not interfere with the formation of the laminate of the first and second wafers with the first major surface of the respective first and second wafers facing in directions towards each other.
2. A method as claimed in claim 1 in which the peripheral recess is formed into the first wafer to a depth from the first major surface which is at least equal to the thickness to which the first wafer is to be subsequently finished after the laminate of the first and second wafers has been formed so that at least a portion of the periphery of the finished first wafer is defined by the peripheral recess.
3. A method as claimed in claim 2 in which the peripheral recess is formed into the first wafer to a depth from the first major surface which is greater than the thickness to which the first wafer is to be subsequently finished after the formation of the laminate of the first and second wafers.
4. A method as claimed in claim 1 in which at least one layer of material is formed on the first major surface of at least one of the first and second wafers to form a buried layer between the first major surfaces of the first and second wafers when the laminate of the first and second wafers has been formed.
5. A method as claimed in claim 4 in which each layer which is to form the buried layer is an oxide layer.
6. A method as claimed in claim 4 in which each layer which is to form the buried layer is a grown layer.
7. A method as claimed in claim 4 in which each layer which is to form the buried layer is a deposited layer.
8. A method as claimed in claim 4 in which the layer which is to form the buried layer is formed on the first wafer.
9. A method as claimed in claim 4 in which the layer which is to form the buried layer is formed on the second wafer.
10. A method as claimed in claim 4 in which the layer which is to form the buried layer is formed on the first wafer subsequent to the formation of the peripheral recess.
11. A method as claimed in claim 4 in which the layer which is to form the buried layer is formed on the first wafer prior to the formation of the peripheral recess, and the peripheral recess is formed through the said layer.
12. A method an claimed in claim 1 in which the peripheral recess is formed by etching the first wafer through the first major surface thereof.
13. A method as claimed in claim 12 in which the peripheral recess is formed by wet etching.
14. A method as claimed in claim 12 in which the peripheral recess is formed by dry etching.
15. A method as claimed in claim 12 in which the peripheral recess is etched through a patterned layer formed on the first major surface defining the peripheral recess.
16. A method as claimed in claim 1 in which the peripheral recess is formed by machining.
17. A method as claimed in claim 1 in which the surface imperfection is on the first major surface of the first wafer.
18. A method as claimed in claim 1 in which the surface imperfection comprises a ridge extending from and around the first major surface adjacent the peripheral edge thereof.
19. A method as claimed in claim 1 in which the first major surface of the first wafer is a polished surface, and the surface imperfection results from the polishing process.
20. A method as claimed in claim 1 in which the first major surface of the second wafer is a polished surface, and the surface imperfection results from the polishing process.
21. A method as claimed in claim 20 in which a protective layer is formed on the polished surface of at least one of the first and second wafers.
22. A method as claimed in claim 1 in which the peripheral recess is formed to extend completely around the first wafer.
23. A method as claimed in claim 1 in which the material of the first wafer is silicon.
24. A method as claimed in claim 1 in which the material of the second wafer is silicon.
25. A method as claimed in claim 1 in which the first wafer is machined to a desired thickness after the laminate of the first and second wafers has been formed, the desired thickness being not greater than the depth to which the peripheral recess is etched into the first wafer from the first major surface thereof.
26. A method as claimed in claim 1 in which the second wafer is provided to form a handle layer of the composite wafer, and the first wafer is provided to form a device layer of the composite wafer in which devices are formed subsequent to the forming of the laminate of the first and second wafers.
27. A method as claimed in claim 25 in which the devices are micro-mechanical devices.
28. A method as claimed in claim 25 in which the devices are electronic devices.
29. A composite semiconductor wafer in the form of a laminate comprising:
a first wafer of semiconductor material having a first major surface, and
a second wafer of semiconductor material having a first major surface, the first major surface of the second wafer facing in a direction towards the first major surface of the first wafer,
wherein at least a portion of the periphery of the first wafer is defined by a peripheral recess, which had been formed in the first wafer through the first major surface adjacent a peripheral edge thereof prior to the laminate of the first and second wafers being formed, so that any surface imperfection on the first major surfaces of the first and second wafers in the area corresponding to the area where the peripheral recess had been formed does not interfere with the formation of the laminate of the first and second wafers.
30. A composite semiconductor wafer as claimed in claim 29 in which the thickness to which the first wafer is finished after the formation of the laminate of the first and second wafers does not exceed the depth to which the peripheral recess had been formed into the first wafer through the first major surface thereof so that at least a portion of the periphery of the finished first wafer is defined by the peripheral recess.
31. A composite semiconductor wafer as claimed in claim 29 in which at least one buried layer is located between the first major surfaces of the first and second wafers.
32. A composite semiconductor wafer as claimed in claim 31 in which the buried layer is an oxide layer.
33. A composite semiconductor wafer as claimed in claim 31 in which the area of the buried layer is similar to the area of the first major surface of the first wafer defined by the peripheral recess so that the peripheral edge of the first wafer defined by the peripheral recess and the adjacent peripheral edge of the buried layer coincide.
34. A composite semiconductor wafer as claimed in claim 29 in which the semiconductor material of at least one of the first and second wafers is silicon.
35. A composite semiconductor wafer as claimed in claim 29 in which a component is formed in one of the first and second wafers.
36. A composite semiconductor wafer as claimed in claim 35 in which the component is a micro-mechanical component.
37. A composite semiconductor wafer as claimed in claim 35 in which the component is an electronic device.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for controlled production of security documents, especially banknotes, wherein said security documents are subjected to a plurality of successive printing and processing operations on a plurality of processing stations, said method comprising:
providing a computer network comprising a central server station coupled via a data network to a plurality of local computer stations, one local computer station being operatively coupled to each processing station,
defining at least one production order, which production order involves the production of a desired volume of security documents according to a defined production workflow, said production order being subdivided into a plurality of production loads each being assigned a machine-readable load identifier;
assigning selected processing stations among available processing stations to carry out processing of said production order according to said production workflow; and
selectively processing each production load through the processing stations depending on the determined production workflow of the corresponding production order defined for each production load, whereby each production load is first subjected to a load acceptance procedure based on said machine-readable load identifier before being authorized to be processed on a selected processing station among said available processing stations.
2. The method according to claim 1, wherein said selective processing of each production load includes:
reading the machine-readable load identifier of the production load at the selected processing station where the production load is supposed to be processed;
checking whether the production state of the production load is such that the load can be processed on said selected processing station andor whether the selected processing station has been assigned to process the production load; and
preventing or authorizing processing of the load on the said selected processing station depending on the result of the checking.
3. The method according to claim 1, wherein defining said at least one production order includes:
defining a desired volume of security documents to be produced;
defining a determined production workflow according to which the production order will be processed;
subdividing the production order into said plurality of production loads; and
generating the machine-readable load identifiers for each production load.
4. The method according to claim 3, wherein defining the determined production workflow includes defining a plurality of successive workflow steps and wherein at least one selected processing station among the available processing stations is assigned to carry out each workflow step.
5. The method according to claim 4, wherein a production load is eligible for processing on a selected one of the processing stations only if the selected processing station has previously been assigned to carry out the corresponding workflow step for that production load.
6. The method according to claim 1, further comprising the step of defining production jobs within a given production order, which production jobs involve distinct groupings of production loads which are to be processed according to a corresponding production workflow defined for the production order.
7. The method according to claim 6, further comprising the step of defining at least one derived production workflow from a reference production workflow, a distinct production job being defined and associated to each derived production workflow.
8. The method according to claim 1, wherein said production loads are at least temporarily stored in at least one storage vault or safe and wherein an additional local computer station, attributed to said storage vault or safe, is provided for recording when a production load is stored in said storage vault or safe andor taken away from said storage vault or safe.
9. The method according to claim 8, wherein yet unprocessed production loads consisting of unprinted paper are stored in at least one white-paper storage vault or safe and wherein partly processed production loads are stored in at least one additional storage vault or safe.
10. The method according to claim 1, wherein said production loads are processed according to a handoff responsibility rule whereby responsibility associated to a given production load is transmitted together with the said given production load.
11. The method according to claim 1, wherein said security documents are printed onto sheets, each sheet holding a plurality of security documents and wherein each production load encompasses a plurality of said sheets.
12. The method according to claim 11, wherein each production load is defined at the start of the production process as a batch containing a predetermined number of sheets, which number of sheets is preferably selected to be comprised in the range of 7,500 to 10,000 sheets.
13. The method according to claim 11, wherein, as a result of each production step, each production load is subdivided into good sheets and waste sheets and wherein the production load is further processed with only the good sheets.
14. The method according to claim 13, wherein the number of good sheets and waste sheets is communicated to said central server station following processing of the production load.
15. The method according to claim 1, wherein a status of each production load is calculated on-the-fly based on load processing history of the production load
16. The method according to claim 1, wherein load processing data is stored locally at each processing station if said central server station is off-line and is transmitted to the central server station when said central server station is on-line.
17. The method according to claim 1, wherein said machine-readable load identifier is a barcode tag or an RFID tag.
18. A system for carrying out the method according to claim 1, said system including a plurality of processing stations and a computer network comprising a central server station coupled via a data network to a plurality of local computer stations, one local computer station being operatively coupled to each processing station, each local computer station being provided with means for reading said machine-readable load identifiers.
19. The system according to claim 18, wherein said computer network implements web-browsing technology to provide access to functionalities of the system at said local computer stations.