Inter-strip capacitance measurments
Measurements performed by Alex Chilingarov, University of Lancaster and analysis is done by Lars Eklund, University of Glasgow.
Reverse current vs. voltage and vs. time, w14 (6 um BCB)
Explanation of plot legend, see below
Reverse current vs. voltage and vs. time, w09 (12 um BCB)
Explanation of plot legend, see below
Inter-strip capacitance measurements, w14 (6 um BCB)
Capacitance was measured between one strip and its two nearest neighbours at 100 kHz and 1 MHz.
The measurement consists of a bias voltage ramp, then the sensor is kept at maximal voltage.
See below for plot legend
Plot legend description: XNYM-KK-A/B/C/D-GNDPlaneType
Coordinates on the wafer are given by
N and
M and the number of the measured strip is given by
KK
The measurements were done in four different configurations of the bias rail connection:
| A | Ampere meter and 1 MOhm connected between bias rail and HV return | GND plane floating (DC)
|
| B | Ampere meter and 1 MOhm connected between bias rail and HV return | GND plane bonded to bias rail
|
| C | Bias rail connected directly to HV return
| GND plane floating (DC) |
| D | Bias rail connected directly to HV return | GND plane bonded to bias rail |
The GND plane types are:
bcb
| Sensor covered only by BCB layer (6+3 um)
|
| m25/30 | Sensor with meshed GND plane (25 % fill factor and 30 um line width)
|
| m50/30 | Sensor with meshed GND plane (50 % fill factor and 30 um line width) |
| m50/80 | Sensor with meshed GND plane (50 % fill factor and 80 um line width) |
| solid | Sensor solid solid GND plane
|
| bare | No BCB and no GND plane: sensors from an old production batch |
Inter-strip capacitance measurements, w09 (12 um BCB)
Capacitance was measured between one strip and its two nearest neighbours at 100 kHz and 1 MHz.
The measurement consists of a bias voltage ramp, then the sensor is kept at maximal voltage.
See below for plot legend
Plot legend description: XNYM-KK-A/B/C/D-GNDPlaneType
Coordinates on the wafer are given by
N and
M and the number of the measured strip is given by
KK
The measurements were done in four different configurations of the bias rail connection:
| A | Ampere meter and 1 MOhm connected between bias rail and HV return | GND plane floating (DC)
|
| B | Ampere meter and 1 MOhm connected between bias rail and HV return | GND plane bonded to bias rail
|
| C | Bias rail connected directly to HV return
| GND plane floating (DC) |
| D | Bias rail connected directly to HV return | GND plane bonded to bias rail |
The GND plane types are:
bcb
| Sensor covered only by BCB layer (12+3 um)
|
m25/30
| Sensor with meshed GND plane (25 % fill factor and 30 um line width)
|
| m50/30 | Sensor with meshed GND plane (50 % fill factor and 30 um line width) |
| m50/80 | Sensor with meshed GND plane (50 % fill factor and 80 um line width) |
| solid | Sensor covered by a solid GND plane
|
| bare | No BCB and no GND plane: sensors from an old production batch |
Comparison tables and plots
Histogram of final values of the inter-strip capacitance. For the solid ground plane sensors the two grounding schemes A and D as described above are included.
Summary of the final interstrip capacitance values for both thicknesses, mean values extracted from the histogram above.
| Wafer | Cis - no BCB
| Cis - only BCB
| Cis - Solid GND (scheme D) | Cis - Solid GND (scheme A)
|
w09 (12 um BCB)
| 0.97 pF
| 1. 05pF | 0.75 pF
| 0.82 pF
|
| w14 (6 um BCB) | 1.02 pF
| 0.63 pF
| 0.78 pF
|
--
LarsEklund - 16 Dec 2008
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