Geometry (2) Separate r-phi detectors (recommended!) –Alignment features? –1 r and 1 phi Divisions and breaks at radii –Final specification minimum/max pitch (manufacturer dependent) –Final Envelope from Physics Studies c.f. TDR Final Stereo Angle –Note included angle prototype may be necessary Inner cut hole –Specification on cut distance from guard ring
Technology+Design Mask –Sole contractual responsibility of manufacturer –Approval by VELO group in writing R/O and implanted strips –2048 r and phi –AC coupled –Bias : polysilicon (see later)
Design(2) Maximum distance to edge from active region 1mm(?) –Dependent on manufacture+cutting HV contact –Backside Bond Pads –Double set
Design(3) Bias contacts –Available at each corner –Propose more contacts for grounding near to chip (16 to be precise) Probe pad contacts –Implants - how many? Passivation –Moment none – not quite true
Design (4) Numbering –Start at 1, Size etc. Fiducials for Pattern Recognition –Manufacturer + Bonding Machine compatibility (K&S 8090)
Test Structures Precise list needed –Manufacturer dependent/provided but what do we need –Mini detectors for batch testing
Mechanical Properties Quality of cut edge –50 microns crack (ATLAS spec) –Laser or mechanical? Cut tolerance –Inner r -200microns –All others 50 microns Thickness –Batch Tolerance –Sensor Tolerance
Mechanical Properties(2) Bond Pad adhesion –Metal quality and strength (max 12g bonds?) Flatness –Tolerance (depends on thickness AND manufacturing process) –Specify unconstrained
Electrical Properties Dielectric layers –Voltage hold-off for AC coupling (10,100V)? Metal insulation (>2 microns) Non-irradiated bulk leakage? –Temp, voltage Breakdown voltage –Time, testing method and thickness
Electrical Properties Good strips > 98%(?), 99%(?) –Definition of bad strips 1. Coupling dielectric: short through dielectric with 100V applied between the metal 1 and the substrate 2. Defective metal strips (Metal 1): breaks or shorts to neighbours 3. Defective metal strips (Metal 2): breaks or shorts to neighbours or broken via to layer 1. 4. Defective implants: Implant breaks or shorts to neighbours. 5. Resistor Connection: Implant strip connection via resistor to bias rail broken.
Testing Precise nature of QA needs to be decided
Summary Final geometrical choice Refinement of specifications –Attempt to be manufacturer friendly Thickness Testing and Qualification What does a Pre-Production detector need to be????
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