I. Hietanen

Advanced Photodiode Detector For Medical CT Imaging: Design and Performance

This paper presents an advanced photodiode detector design for medical imaging applications, especially computerized tomography. The detector is silicon based and integrates the through-wafer interconnection technology into conventional front illuminated photodiode. The number of photodiode elements in the detector can be extended in 2D without reducing the photodiode active area. The signal of each photodiode element can be directly read out from the backside of the detector. Moreover, detectors can be tiled together in 2D without any physical limitation. A test photodiode detector was designed and demonstrated with 3times3 photodiode matrix arrangement in this paper. Different parameters were measured and analyzed from the demonstrated chip and test structures. The results show that the detector inherits most of the performance advantages from the conventional front illuminated photodiode, and all the parameters can either meet or exceed the requirements of modern CT systems.

Measurement of spatial resolution of a double-sided AC-coupled microstrip detector

Abstract Capacitively coupled Si strip detectors with readout on both the p-side and the n-side have been developed. A novel scheme to separate strips ohmically on the n-side by means of field depletion via a suitable potential applied to the readout strips has been successfully demonstrated. Results on the spatial resolution of these detectors for both sides measured in a high energy beam are presented. The spatial resolution of the n-side has been measured at different incident angles of the beam tracks with respect to a vertical plane through the n + strips at 0°, 20° and 40°.

Ion-implanted capacitively coupled silicon strip detectors with integrated polysilicon bias resistors processed on a 100 mm wafer

Abstract Double-sided silicon strip detectors with integrated coupling capacitors and polysilicon resistors have been processed on a 100 mm wafer. A detector with an active area of 19 × 19 mm 2 was connected to LSI readout electronics and tested. The strip pitch of the detector is 25 μm on the p-side and 50 μm on the n-side. The readout pitch is 50 μm on both sides. The number of readout strips is 774 and the total number of strips is 1161. On the p-side a signal-to-noise of 35 has been measured using a 90 Sr β-source. The n-side has been studied using a laser.

Ion-implanted silicon detectors processed on a 100 mm wafer

Abstract A planar process for manufacturing large silicon detectors on a 100 mm wafer has been developed. Several oxidation and annealing temperatures were studied in order to optimize detector performance. A strip detector with an active area of 32 × 58 mm2 together with various single detector diodes were processed and tested. The 1280 strip detector with 25 μm strip and readout pitch was connected to multiplexing LSI electronics and tested with tracks from a 90Sr beta source. The most probable signal pulse height was found to be 14 times the σnoise of any individual channel.

Beam test results of an ion-implanted capacitively coupled silicon strip detector processed on a 100 mm silicon wafer

Abstract A capacitively coupled silicon strip detector with 50 μm readout pitch has been tested in a pion beam at CERN. The spatial resolution of the detector equipped with LSI readout chips was 4.9 μm and the most probable signal-to-single-channel noise ratio was 31.

Beam test results of an ion-implanted silicon strip detector on a 100 mm wafer

Abstract Results are presented from a beam test in the CERN SPS North Area of a silicon strip detector. The detector is directly coupled and has an active area of 32 × 58 mm and a strip pitch of 25 μm. It is processed on a 100 mm wafer. Spatial resolution of the detector equipped with LSI readout chips was measured to be 3.9 μm and the most probable signal to single channel noise ratio was 20.

Double-sided capacitively coupled silicon strip detectors on a 100mm water

Abstract Silicon strip detectors with double-sided readout have been designed and processed on 100 mm silicon wafers. Detectors with integrated coupling capacitors and polysilicon bias resistors were tested by static electrical measurements, laser illumination and with tracks from a 90 Sr source. Strip separation on the detector n-side has been achieved by the use of capacitively coupled readout electrodes as field-plates. Interstrip resistance of > 10 Mω has been measured in all detector designs. Measurements with 90 Sr tracks show S/N = 21 on the detector p-side and S/N = 18 on the n-side.

Via-in-Pixel Design of Truly 2D Extendable Photodiode Detector for Medical CT Imaging

This paper presents an advanced design of the photodiode detector for medical imaging, especially for the X-ray computed tomography applications. In this paper, through wafer interconnection technology with via-in-pixel design is utilized to achieve the truly 2D extendable feature of the photodiode detector. The active area of each photodiode element on the detector can achieve the maximum active area with the fixed pitch size. Comparing to the via-off-pixel design, different parameters of the photodiode with via-in-pixel design were measured and analyzed from the demonstrated samples. The results show that the performances of the samples either meet or exceed the requirements of the modern X-ray computed tomography applications.