omponents maintains a short path having low inductance from the voltage regulator to the die. Further, the voltage regulator control loop bandwidth is increased by the higher switching frequency and shortened feedback path between the voltage regulator and the die.
Larger inductance values are achieved by embedding passive components in comparison to conventional parasitic air-core inductors in packaging substrate routing or PCB routing. Embedding passive components also reduces die size by reducing or eliminating discrete passive components of the voltage regulator, which may otherwise be located side-by-side with the die.
FIG. 4 is a cross-sectional view illustrating an exemplary voltage regulator on a die according to a first embodiment. An IC product 400 includes a packaging substrate 420 coupled to a PCB 410 through a packaging connection 422 such as bumps or pillars. The packaging substrate 420 includes embedded passive components that may store energy in magnetic or electric form. For example, an embedded inductor 450 and an embedded capacitor 460 are at least partially embedded in the packaging substrate 420. The embedded inductor 450 and/or the embedded capacitor 460 may use embedded die substrate (EDS) technology. In one embodiment, the embedded capacitor 460 may have capacitance values in the hundreds of nanoFarads and provide decoupling capacitance to a die 430. The die 430 is coupled to the packaging substrate 420 through an interconnect structure 432 such as bumps or pillars.
Manufacturing the embedded inductor 450 and the embedded capacitor 460 in the packaging substrate 420 may use a lamination process according to one embodiment. For example, the packaging substrate 420 may start as a core with two internal layers separated by a thick dielectric layer. Holes are placed in the substrate using a laser drilling process and tape placed on a backside of the core. The holes are filled to form the embedded inductor 450 and the embedded capacitor 460, and a top side of the core is laminated. The embedded inductor 450 may be, for example, non air-core inductors to obtain higher inductance values than air-core inductors. Next, tape is peeled off the back side of the core, and the back side of the core is laminated. The inductance of the embedded inductor 450 and the capacitance of the embedded capacitor 460 are selected, in part, from parameters including a supply voltage of the die 430 and an operating frequency of the die 430. Passive components located in the packaging substrate 420 may use thicker copper than passive components located in a die and thus have smaller losses and a higher quality (Q) factor.
An active portion of a voltage regulator 440 is fabricated on the die 430 and includes, for example, a driver stage, a feedback stage, and/or a digital controller. The active portion of the voltage regulator 440 communicates with the embedded inductor 450 through an electrical path 426. An electrical path 427 couples the embedded inductor 450 to the embedded capacitor 460. An electrical path 428 couples the embedded capacitor 460 to the die 430. An electrical path 424 enables communication from the die 430 to the PCB 410. The electrical path 424 may be used, for example, to provide voltage to the active portion of the voltage regulator 440. That is, regulated voltage provided to the die 430 passes through the electrical path 424 to the active portion of the voltage regulator 440, then to the embedded inductor 450, and the embedded capacitor 460.
In one embodiment, the active portion of the voltage regulator 440 is integrated in the die 430. Thus, the active portion of the voltage regulator 440 responds quickly to current transients that occur in the die 430. According to one embodiment, the active portion of the voltage regulator 440 has a response frequency of approximately 200 MHz. Additionally, embedded passive components such as the embedded inductor 450 and the embedded capacitor 460 in the packaging substrate 420 reduce area on the die 430 that would otherwise be occupied by passive components. The volt