The present disclosure relates to a wafer-level packaged (WLP) bulk acoustic wave (BAW) device, which includes a BAW resonator, a WLP enclosure, and an interconnect. The BAW resonator includes a piezoelectric layer with an opening, a bottom electrode lead underneath the opening, and an interface str
The present disclosure relates to a wafer-level packaged (WLP) bulk acoustic wave (BAW) device, which includes a BAW resonator, a WLP enclosure, and an interconnect. The BAW resonator includes a piezoelectric layer with an opening, a bottom electrode lead underneath the opening, and an interface structure extending over the opening and in contact with the bottom electrode lead through the opening. The WLP enclosure includes a cap, an outer wall that extends from the cap toward the piezoelectric layer to form a cavity, and a through-WLP via that extends through the cap and the outer wall and is vertically aligned with the opening of the piezoelectric layer. A portion of the interface structure is exposed to the through-WLP via. The interconnect is formed in the through-WLP via and electrically connected to the interface structure.
대표청구항▼
1. An apparatus comprising: a piezoelectric layer with a first interface opening;a bottom electrode over a bottom surface of the piezoelectric layer;a bottom electrode lead over the bottom surface of the piezoelectric layer and extending from the bottom electrode, wherein a portion of the bottom ele
1. An apparatus comprising: a piezoelectric layer with a first interface opening;a bottom electrode over a bottom surface of the piezoelectric layer;a bottom electrode lead over the bottom surface of the piezoelectric layer and extending from the bottom electrode, wherein a portion of the bottom electrode lead is exposed through the first interface opening of the piezoelectric layer;a first interface structure extending over the first interface opening and in contact with the exposed portion of the bottom electrode lead;a top electrode over a top surface of the piezoelectric layer, wherein: the top surface of the piezoelectric layer is opposite the bottom surface of the piezoelectric layer; andan active region for a resonator is formed where the bottom electrode and the top electrode overlap; anda Wafer-Level-Packaged (WLP) enclosure comprising a WLP cap, an outer wall, and a first through-WLP via, wherein: the outer wall extends from the WLP cap toward the top surface of the piezoelectric layer to form a cavity, and the top electrode resides in the cavity;the first through-WLP via extends vertically through the WLP cap and the outer wall, and is encompassed by the outer wall; andthe first through-WLP via of the WLP enclosure is vertically aligned with the first interface opening of the piezoelectric layer, and a portion of the first interface structure is exposed to the first through-WLP via; anda first interconnect formed in the first through-WLP via and electrically connected to the first interface structure. 2. The apparatus of claim 1 further comprising a passivation layer, wherein: the passivation layer is directly over the top electrode and a portion of the top surface of the piezoelectric layer, such that a bottom surface of the outer wall is in contact with the passivation layer; andthe passivation layer has a first passivation opening that is vertically aligned between the first through-WLP via of the WLP enclosure and the first interface opening of the piezoelectric layer, such that the portion of the first interface structure is exposed to the first through-WLP via of the WLP enclosure through the first passivation opening of the passivation layer. 3. The apparatus of claim 2 wherein a width of the first passivation opening of the passivation layer is no greater than a width of the first interface opening of the piezoelectric layer. 4. The apparatus of claim 3 wherein the width of the first interface opening of the piezoelectric layer is between 1.0 μm and 100 μm. 5. The apparatus of claim 3 wherein the width of the first passivation opening of the passivation layer is between 1.0 μm and 100 μm. 6. The apparatus of claim 2 wherein the passivation layer is formed of Silicon Nitride (SiN), SiO2, or Silicon Oxynitride (SiON), with a thickness between 10 Å and 5000 Å. 7. The apparatus of claim 2 further comprising a first seed layer, wherein: the first seed layer continuously extends over exposed surfaces within the first through-WLP via, such that the first seed layer is in contact with the exposed portion of the first interface structure through the first passivation opening of the passivation layer; andthe first interconnect is formed over the first seed layer. 8. The apparatus of claim 7 wherein the first seed layer is formed of Titanium (Ti) or Titanium Tungsten (TiW). 9. The apparatus of claim 1 wherein the WLP cap has a height between 5 μm and 60 μm, and the outer wall has a thickness between 5 μm and 60 μm and a height between 10 μm and 60 μm. 10. The apparatus of claim 1 wherein the first interconnect is formed of copper (Cu), Tin (Sn), or Tin Silver (SnAg). 11. The apparatus of claim 1 wherein the first interface structure comprises a lower interface layer, a middle interface layer, and an upper interface layer, wherein: the lower interface layer extends over the first interface opening of the piezoelectric layer and is in contact with the exposed portion of the bottom electrode lead;the middle interface layer is formed over the lower interface layer, and the upper interface layer is formed over the middle interface layer;a portion of the upper interface layer is exposed to the first through-WLP via of the WLP enclosure and electrically connected to the first interconnect; andthe lower interface layer is formed of Tungsten (W) or Molybdenum (Mo), the middle interface layer is formed of Aluminum Copper (AlCu), and the upper interface layer is formed of W or Mo. 12. The apparatus of claim 11 wherein: the lower interface layer has a thickness between 100 Å and 10000 Å;the middle interface layer has a thickness between 100 Å and 10000 Å; andthe upper interface layer has a thickness between 100 Å and 10000 Å. 13. The apparatus of claim 11 wherein the bottom electrode and the bottom electrode lead are formed from a common first bottom electrode layer and a common second bottom electrode layer, wherein: the first bottom electrode layer is formed over the bottom surface of the piezoelectric layer, and a portion of the first bottom electrode layer is in contact with the lower interface layer of the first interface structure through the first interface opening of the piezoelectric layer;the second bottom electrode layer is formed underneath the first bottom electrode layer; andthe first bottom electrode layer is formed of W or Mo, and the second bottom electrode layer is formed of AlCu. 14. The apparatus of claim 13 wherein: the first bottom electrode layer has a thickness between 100 Å and 10000 Å; andthe second bottom electrode layer has a thickness between 100 Å and 10000 Å. 15. The apparatus of claim 2 wherein the first interface structure comprises a lower interface layer, a middle interface layer, and an upper interface layer, wherein: the lower interface layer extends over the first interface opening of the piezoelectric layer and is in contact with the exposed portion of the bottom electrode lead;the middle interface layer is formed over the lower interface layer, and the upper interface layer with a layer opening formed over the middle interface layer;the layer opening of the upper interface layer is vertically aligned with the first passivation opening of the passivation layer, and has essentially a same size as the first passivation opening of the passivation layer;a portion of the middle interface layer is exposed to the first through-WLP via of the WLP enclosure through the first passivation opening of the passivation layer and the layer opening of the upper interface layer, and is electrically connected to the first interconnect; andthe lower interface layer is formed of W or Mo, the middle interface layer is formed of AlCu, and the upper interface layer is formed of W or Mo. 16. The apparatus of claim 2 wherein the first interface structure comprises a lower interface layer, a middle interface layer, and an upper interface layer, wherein: the lower interface layer extends over the first interface opening of the piezoelectric layer and is in contact with the exposed portion of the bottom electrode lead;the middle interface layer with a first layer opening is formed over the lower interface layer, and the upper interface layer with a second layer opening is formed over the middle interface layer;the first layer opening of the middle interface layer and the second layer opening of the upper interface layer are vertically aligned with the first passivation opening of the passivation layer;the first layer opening of the middle interface layer and the second layer opening of the upper interface layer have essentially a same size as the first passivation opening of the passivation layer;a portion of the lower interface layer is exposed to the first through-WLP via of the WLP enclosure through the first passivation opening of the passivation layer, the second layer opening of the upper interface layer, and the first layer opening of the middle interface layer, and is electrically connected to the first interconnect; andthe lower interface layer is formed of W or Mo, the middle interface layer is formed of AlCu, and the upper interface layer is formed of W or Mo. 17. The apparatus of claim 1 further comprising a top electrode lead, a second interface structure, and a second interconnect, wherein: the piezoelectric layer further includes a second interface opening;the top electrode lead is formed over the top surface of the piezoelectric layer and extends from the top electrode;the second interface structure extends from the top electrode lead, and extends over the second interface opening of the piezoelectric layer;the WLP enclosure further includes a second through-WLP via, wherein the second through-WLP via extends through the WLP cap and the outer wall, is encompassed by the outer wall, and is vertically aligned with the second interface opening of the piezoelectric layer;a portion of the second interface structure is exposed to the second through-WLP via of the WLP enclosure; andthe second interconnect formed in the second through-WLP via of the WLP enclosure and is electrically connected to the second interface structure. 18. The apparatus of claim 17 further comprising a passivation layer with a first passivation opening and a second passivation opening, wherein: the passivation layer is directly over the top electrode, the top electrode lead, and a portion of the top surface of the piezoelectric layer, such that a bottom surface of the outer wall is in contact with the passivation layer;the first passivation opening is vertically aligned between the first through-WLP via of the WLP enclosure and the first interface opening of the piezoelectric layer, such that the portion of the first interface structure is exposed to the first through-WLP via of the WLP through the first passivation opening of the passivation layer; andthe second passivation opening is vertically aligned between the second through-WLP via of the WLP enclosure and the second interface opening of the piezoelectric layer, such that the portion of the second interface structure is exposed to the second through-WLP via of the WLP enclosure through the second passivation opening of the passivation layer. 19. The apparatus of claim 18 further comprising a first seed layer and a second seed layer, wherein: the first seed layer continuously extends over exposed surfaces within the first through-WLP via, such that the first seed layer is in contact with the exposed portion of the first interface structure through the first passivation opening of the passivation layer;the first interconnect is formed over the first seed layer;the second seed layer continuously extends over exposed surfaces within the second through-WLP via, such that the second seed layer is in contact with the exposed portion of the second interface structure through the second passivation opening of the passivation layer; andthe second interconnect is formed over the second seed layer. 20. The apparatus of claim 17 wherein: the first interface structure includes a lower interface layer, a middle interface layer, and an upper interface layer, wherein: the lower interface layer extends over the first interface opening and is in contact with the exposed portion of the bottom electrode lead;the middle interface layer is formed over the lower interface layer, and the upper interface layer is formed over the middle interface layer;a portion of the upper interface layer is exposed to the first through-WLP via of the WLP enclosure and electrically connected to the first interconnect; andthe lower interface layer is formed of W or Mo, the middle interface layer is formed of AlCu, and the upper interface layer is formed of W or Mo;the bottom electrode and the bottom electrode lead are formed from a common first bottom electrode layer and a common second bottom electrode layer, wherein: the first bottom electrode layer is formed over the bottom surface of the piezoelectric layer, and a portion of the first bottom electrode layer is in contact with the lower interface layer of the first interface structure through the first interface opening of the piezoelectric layer;the second bottom electrode layer is formed underneath the first bottom electrode layer; andthe first bottom electrode layer is formed of W or Mo, and the second bottom electrode layer is formed of AlCu, andthe top electrode, the top electrode lead, and the second interface structure are formed from a common first top electrode layer, a common second top electrode layer, and a common third top electrode layer, wherein: the first top electrode layer extends over a portion of the top surface of the piezoelectric layer and over the second interface opening;the second top electrode layer is formed over the first top electrode layer, and the third top electrode layer is formed over the second top electrode layer;a portion of the third top electrode layer is exposed to the second through-WLP via of the WLP enclosure and electrically connected to the second interconnect; andthe first top electrode layer is formed of W or Mo, the second top electrode layer is formed of AlCu, and the third top electrode layer is formed of W or Mo. 21. An apparatus comprising: a piezoelectric layer with an interface opening;a bottom electrode over a bottom surface of the piezoelectric layer;a top electrode over a top surface of the piezoelectric layer, wherein: the top surface of the piezoelectric layer is opposite the bottom surface of the piezoelectric layer; andan active region for a resonator is formed where the bottom electrode and the top electrode overlap;a top electrode lead over the top surface of the piezoelectric layer and extending from the top electrode;an interface structure extending from the top electrode lead, and extending over the interface opening;a Wafer-Level-Packaged (WLP) enclosure comprising a WLP cap, an outer wall, and a through-WLP via, wherein: the outer wall extends from the WLP cap toward the top surface of the piezoelectric layer to form a cavity, and the top electrode resides in the cavity;the through-WLP via extends through the WLP cap and the outer wall and is encompassed by the outer wall; andthe through-WLP via of the WLP enclosure is vertically aligned with the interface opening of the piezoelectric layer, and a portion of the interface structure is exposed to the through-WLP via; andan interconnect formed in the through-WLP via of the WLP enclosure and electrically connected to the interface structure. 22. The apparatus of claim 21 wherein the top electrode, the top electrode lead, and the interface structure are formed from a common first top electrode layer, a common second top electrode layer, and a common third top electrode layer, wherein: the first top electrode layer extends over a portion of the top surface of the piezoelectric layer and over the interface opening;the second top electrode layer is formed over the first top electrode layer, and the third top electrode layer is formed over the second top electrode layer;a portion of the third top electrode layer is exposed to the through-WLP via of the WLP enclosure and electrically connected to the interconnect; andthe first top electrode layer is formed of W or Mo, the second top electrode layer is formed of AlCu, and the third top electrode layer is formed of W or Mo. 23. The apparatus of claim 21 further comprising a passivation layer with a passivation opening, wherein: the passivation layer is directly over the top electrode, the top electrode lead, and a portion of the top surface of the piezoelectric layer, such that a bottom surface of the outer wall is in contact with the passivation layer; andthe passivation opening is vertically aligned between the through-WLP via of the WLP enclosure and the interface opening of the piezoelectric layer, such that the portion of the interface structure is exposed to the through-WLP via of the WLP enclosure through the passivation opening of the passivation layer. 24. The apparatus of claim 23 further comprising a seed layer, wherein: the seed layer continuously extends over exposed surfaces within the through-WLP via, such that the seed layer is in contact with the exposed portion of the interface structure through the passivation opening of the passivation layer; andthe interconnect is formed over the seed layer.
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