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US 8,133,755 B2Granted
Avalanche photodiode having controlled breakdown voltage
AssigneePrinceton Lightwave, Inc.
InventorMark Allen Itzler
Life of this patent
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Abstract
Avalanche photodiodes and methods for forming them are disclosed. The breakdown voltage of an avalanche photodiode is controlled through the inclusion of a diffusion sink that is formed at the same time as the device region of the photodiode. The device region and diffusion sink are formed by diffusing a dopant into a semiconductor to form a p-n junction in the device region. The dopant is diffused through a first diffusion window to form the device region and a second diffusion window to form the diffusion sink. The depth of the p-n junction is based on an attribute of the second diffusion window.
Claims19
A method comprising:
- determining a first desired diffusion depth to which a dopant is to be diffused through a first diffusion window, at a first location, into a semiconductor layer;
- determining a first attribute for a second diffusion window located at a second location, wherein the first attribute is based on the first desired diffusion depth and a pre-established relationship between the diffusion depth at the first location and the first attribute for the second diffusion window;
- forming a diffusion mask over the semiconductor layer, wherein the diffusion mask comprises the first diffusion window and the second diffusion window, and wherein the second diffusion window is characterized by the first attribute;
- and
- diffusing the dopant into the semiconductor layer through the first diffusion window and the second diffusion window, wherein the dopant is diffused through the first diffusion window to substantially the first desired diffusion depth.
2 more elements
A method comprising:
- determining a first desired breakdown voltage for an APD, wherein the APD comprises a device region formed in a semiconductor layer;
- determining a desired diffusion depth for a dopant in the device region, wherein the desired diffusion depth is based on the desired breakdown voltage;
- forming a diffusion mask over the semiconductor layer, wherein the diffusion mask comprises;
- a plurality of first diffusion windows for forming a plurality of device regions in the semiconductor layer;
- and
- a second diffusion window for forming a diffusion sink, wherein the second diffusion window comprises a plurality of window regions, and wherein each pair of first diffusion windows of the plurality of first diffusion windows is interposed by a window region of the plurality of window regions, and further wherein each of the plurality of window regions is characterized by an attribute that is based on the desired diffusion depth and a pre-established relationship between diffusion depth in a first portion of a diffusion region comprising the first portion and a second portion that is characterized by the first attribute;
- and
- diffusing the dopant into the semiconductor layer at each of the plurality of first diffusion windows and the second diffusion window, wherein the dopant is diffused into the semiconductor layer to substantially the desired diffusion depth at each of the plurality of first diffusion windows.
5 more elements
A method comprising:
- determining a first desired diffusion depth to which a dopant is to be diffused into a semiconductor layer to form a first device region of a first APD characterized by a first desired breakdown voltage;
- determining a second desired diffusion depth to which the dopant is to be diffused into the semiconductor layer to form a second device region of a second APD characterized by a second desired breakdown voltage;
- forming a diffusion mask over the semiconductor layer, wherein the diffusion mask comprises;
- a first pixel, wherein the first pixel comprises a first mask region that separates a first open region and a second open region that surrounds the first open region, and wherein at least a portion of the first mask region has a first minimum width that is based on (1) the first desired diffusion depth and (2) a first pre-established relationship between diffusion depth in a first portion of a diffusion region and the separation distance between the first portion and a second portion of the diffusion region;
- and
- a second pixel, wherein the second pixel comprises a second mask region that separates a third open region and a fourth open region that surrounds the third open region, and wherein at least a portion of the second mask region has a second minimum width that is based on (1) the second desired diffusion depth and (2) the first pre-established relationship;
- and
- diffusing the dopant into the semiconductor layer at the first open region and the third open region, wherein the dopant is diffused to substantially the first desired diffusion depth at the first open region, and wherein the dopant is diffused to substantially the second desired diffusion depth at the third open region.
5 more elements
Dependencies are inferred from the claim text.