Method for measuring the electrical and optical performance of on-wafer microwave devices
First Claim
1. A method for on-wafer testing of microwave devices comprising:
- (a) providing a wafer of the type having a lower side with a ground plane and an opposing upper side and having a microwave device connected between a first probeable contact on the upper side of said wafer and said ground plane on the lower side thereof;
(b) providing a diode arranged side-by-side with said microwave device and connected between a second probeable contact on the upper side of said wafer and said ground plane on the lower side thereof, said first and second probeable contacts having a predetermined side-b-side spacing therebetween;
(c) providing a microwave probe having a signal conductor in coplanar relation with a ground conductor, said signal conductor and ground conductor having a side-by-side spacing corresponding to said predetermined side-by-side spacing between said first and second probeable contacts;
(d) placing the diode in a forward biased condition by applying a first voltage between said ground conductor and the ground plane of the wafer; and
(e) during step (d), measuring via said signal conductor and said ground conductor a performance parameter characterizing said microwave device.
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Accused Products
Abstract
A method for on-wafer testing of microwave devices, such as photodiodes, including a biasing method applicable when the device has a lower end connected to the ground plane of the wafer. Elements having a diode-like characteristic, such as photodiodes, are arranged side-by-side with the device, each preferably being of like geometry with the device, and each having an end connected to the ground plane. A first voltage is applied between the ground conductors of the probe and the ground plane of the wafer to place each element in forward-biased condition thereby creating a return path for the lower end of the device to the ground conductors located on the upper side of the wafer. The method further includes a calibration method for accurate measurements of photodetectors particularly when they are biased as described above, including measuring a performance parameter, such as responsivity, that characterizes the optical performance of the photodetector, measuring a network parameter, such as a reflection coefficient, that characterizes the electrical performance of the photodetector, and determining an adjusted value for the performance parameter based on the network parameter in which the reference plane of the measured performance parameter has been shifted so as to better characterize the intrinsic response of the photodetector without interference by the surrounding measurement environment. Specific steps for removing probe effects and return path diode effects are described.
37 Citations
24 Claims
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1. A method for on-wafer testing of microwave devices comprising:
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(a) providing a wafer of the type having a lower side with a ground plane and an opposing upper side and having a microwave device connected between a first probeable contact on the upper side of said wafer and said ground plane on the lower side thereof; (b) providing a diode arranged side-by-side with said microwave device and connected between a second probeable contact on the upper side of said wafer and said ground plane on the lower side thereof, said first and second probeable contacts having a predetermined side-b-side spacing therebetween; (c) providing a microwave probe having a signal conductor in coplanar relation with a ground conductor, said signal conductor and ground conductor having a side-by-side spacing corresponding to said predetermined side-by-side spacing between said first and second probeable contacts; (d) placing the diode in a forward biased condition by applying a first voltage between said ground conductor and the ground plane of the wafer; and (e) during step (d), measuring via said signal conductor and said ground conductor a performance parameter characterizing said microwave device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for on-wafer testing of microwave photodetectors comprising:
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(a) providing a wafer supporting a photodetector thereon, (b) providing light emitting means for selectively applying an optical signal to said photodetector; (c) providing a microwave probe for measuring said photodetector and for applying an electrical signal to said photodetector; (d) probing said photodetector with the microwave probe including measuring a performance parameter characterizing the response of said photodetector to said optical signal from a first reference plane; (e) probing said photodetector with the microwave probe including measuring a network parameter characterizing the response of said photodetector to said electrical signal; and (f) determining an adjusted value for said performance parameter based on said network parameter so that the response of said photodetector to said optical signal is characterized from a second reference plane nearer to said photodetector than said first reference plane. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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Specification