Patent Application
20070217248
Embodiments of the invention relate generally to the field of integrated circuit design, specifically to methods, apparatuses, and systems associated with and/or having fuse cells.
Increasingly, metal fuses are being incorporated into integrated circuit design. These types of metal fuses may be formed by running a sustained large current through a metal line eventually resulting in a void or open in the metal line. The void or open creates an increased resistance.
After programming, a fuse cell comprising one or more fuses is generally in either a sensing or standby mode. Sensing generally only happens during power on and reset. However, after sensing, a fuse cell may be in a standby mode for sustained periods of time. During a standby mode, a large voltage drop may be present across the fuse which may cause electrons in certain metal species to migrate and gradually reduce the resistance of the programmed fuse. This reduced resistance may eventually lead to fuse cell state flipping and/or circuit malfunctioning.
Embodiments of the present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings. Embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings.
Illustrative embodiments of the present invention include but are not limited to methods for prediction-based processing, components contributing to the practice of these methods, in part or in whole, and systems endowed with such components.
In the following detailed description, reference is made to the accompanying drawings which form a part hereof and in which is shown by way of illustration embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments in accordance with the present invention is defined by the appended claims and their equivalents.
Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments of the present invention; however, the order of description should not be construed to imply that these operations are order dependent.
The description may use perspective-based descriptions such as up/down, back/front, and top/bottom. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of embodiments of the present invention.
The description may use the phrases “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present invention, are synonymous.
The phrase “A/B” means “A or B”. The phrase “A and/or B” means “(A), (B), or (A and B)”. The phrase “at least one of A, B and C” means “(A), (B), (C), (A and B), (A and C), (B and C) or (A, B and C)”. The phrase “(A) B” means “(B) or (A B)”, that is, A is optional.
Referring now to
Standby circuitry 120 may be variously configured. For example, in some embodiments, standby circuitry 120 may be configured to provide a standby supply voltage to the fuse device 105 when the fuse cell 10 is in a standby mode to reduce a voltage drop value across the fuse device 105. In various ones of these embodiments, standby circuitry 120 may be configured to reduce the voltage drop value across fuse device 105 to the threshold voltage value of one or more switchable conductive path devices 130 of the standby circuitry 120. For example, if the supply voltage and one or more switchable conductive path devices 130 of standby circuitry 120 have a threshold value, providing a standby supply voltage to fuse device 105 using the standby circuitry 120 may reduce the voltage drop value across fuse device 105 to the threshold voltage value.
Still further, in various embodiments, standby circuitry 120 may be coupled to a standby signal source 125. In some of these embodiments, standby circuitry 120 may be coupled to a standby signal source 125 to receive a standby signal from the standby signal source 125 to indicate to the standby circuitry 120 that fuse cell 10 is in standby mode. As mentioned earlier, fuse cell 10 may be configured to provide a standby supply voltage to fuse device 105 when the fuse cell 10 is in standby mode to reduce a voltage drop value across fuse device 105.
In some embodiments and as shown if
In some of these embodiments, standby circuitry 120 may further include another switchable conductive path device 130. In various ones of these embodiments, the two switchable conductive path devices 130 may be NMOS transistor devices serially arranged between another supply voltage source 135 and the fuse device 105. In these embodiments, a first of the NMOS transistor devices may be configured to receive another supply voltage from the other supply voltage source 135, and a second of the NMOS transistor devices may be configured to provide the standby supply voltage to the fuse device 105. This stacking configuration may be used for various reasons including, for example, increasing tolerance to high voltages. In various embodiments and depending on the applications, supply voltage sources 115 and 135 may be the same supply voltage source or may be different supply voltage sources.
In various embodiments, fuse cell 10 may also comprise various programming circuitry 140 and/or other circuitry 145. Other circuitry 145 may include, for example, sense amplifier circuitry. In some embodiments and as shown in
Referring now to
Systems 30 in accordance with various embodiments of the present invention may be variously configured. For example, standby circuitry may be variously configured. In various embodiments, standby circuitry may be configured to reduce the voltage drop value across fuse device to the threshold voltage value of the standby circuitry. Still further, in various embodiments, standby circuitry may be coupled to a standby signal source. In some of these embodiments, standby circuitry may be coupled to a standby signal source to receive a standby signal from the standby signal source to indicate to the standby circuitry the fuse cell 305 is in standby mode. As mentioned earlier, fuse cell 305 may be configured to provide a standby supply voltage to fuse device when the fuse cell 305 is in standby mode to reduce a voltage drop value across a fuse device.
In some embodiments, standby circuitry in accordance with the present invention may include one or more switchable conductive path devices. In various embodiments, switchable conductive path device may be either a PMOS transistor device or an NMOS device. In some of these embodiments, switchable conductive path device may be coupled to the standby signal source to receive a standby signal. In various ones of these embodiments, switchable conductive path device may be configured to switch on when switchable conductive path device receives a standby signal. For example, switchable conductive path device may be configured to switch on when switchable conductive path device receives a logic-high standby signal. Still further, in various embodiments, switchable conductive path device may be configured to switch off during certain processes. For example, switchable conductive path device may be configured to switch off during programming and/or reading of fuse device.
In various other embodiments, standby circuitry may further include another switchable conductive path device. In various ones of these embodiments, the two switchable conductive path devices may be NMOS transistor devices serially arranged between another supply voltage source and the fuse device. In these embodiments, a first of the NMOS transistor devices may be configured to receive another supply voltage from the other supply voltage source, and a second of the NMOS transistor devices may be configured to provide the standby supply voltage to the fuse device.
Illustrated in
Embodiments of methods in accordance with the present invention may further comprise reducing the voltage drop value across the fuse device to a threshold voltage value of the standby circuitry. As mentioned previously, reducing the voltage drop value across the fuse device to a threshold voltage value of standby circuitry may be done, for example, by providing a supply voltage to a fuse device, and providing a standby supply voltage to fuse device using the standby circuitry.
In some embodiments, method 40 may further comprise sending a standby signal to the standby circuitry to indicate to the standby circuitry the fuse cell is in standby mode. In various ones of these embodiments, standby signal may be sent to a switchable conductive path device of standby circuitry. In various ones of these embodiments, standby signal may be sent to a PMOS transistor device or an NMOS transistor device of standby circuitry. In these embodiments, sending a standby signal to a switchable conductive path device of the standby circuitry may comprise switching on the switchable conductive path device. In still other embodiments, the method may further comprise switching off switchable conductive path device during programming and/or reading of fuse device.
Although certain embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope of the present invention. Those with skill in the art will readily appreciate that embodiments in accordance with the present invention may be implemented in a very wide variety of ways. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments in accordance with the present invention be limited only by the claims and the equivalents thereof.
