MonolithIC 3D Inc., Patents Pending MonolithIC 3D ICs RCAT Flow 1 MonolithIC 3D Inc., Patents Pending

Monolithic 3D ICs Using SmartCut technology - the ion cutting process that Soitec uses to make SOI wafers for AMD and IBM (million of wafers had utilized the process over the last 20 years) - to stack up consecutive layers of active silicon (bond first and then cut). Soitec’s Smart Cut Patented* Flow (access the link for video).SmartCut Soitec’s Smart Cut Patented* Flow MonolithIC 3D Inc., Patents Pending 2 *Soitec’s fundamental patent US 5,374,564 expired Sep. 15, 2012

Monolithic 3D ICs Ion cuttingIon cutting: the key idea is that if you implant a thin layer of H+ ions into a single crystal of silicon, the ions will weaken the bonds between the neighboring silicon atoms, creating a fracture plane (Figure 3). Judicious force will then precisely break the wafer at the plane of the H+ implant, allowing you to in effect peel off very thin layer. This technique is currently being used to produce the most advanced transistors (Fully Depleted SOI, UTBB transistors – Ultra Thin Body and BOX), forming monocrystalline silicon layers that are less than 10nm thick. MonolithIC 3D Inc., Patents Pending 3

Figure 3 Using ion-cutting to place a thin layer of monocrystalline silicon above a processed (transistors and metallization) base wafer MonolithIC 3D Inc., Patents Pending 4 p- Si Oxide p- Si Oxide H Top layer Bottom layer Oxide Hydrogen implant of top layer Flip top layer and bond to bottom layer Oxide p- Si Oxide H Cleave using <400 o C anneal or sideways mechanical force. CMP. Oxide Similar process (bulk-to-bulk) used for manufacturing all SOI wafers today p- Si

MonolithIC 3D – The RCAT path  The Recessed Channel Array Transistor (RCAT) fits very nicely into the hot-cold process flow partition  RCAT is the transistor used in commercial DRAM as its 3D channel overcomes the short channel effect  Used in DRAM 90nm, 60nm, 50nm nodes  Higher capacitance, but less leakage, same drive current The following slides present the flow to process an RCAT without exceeding the 400ºC temperature limit MonolithIC 3D Inc., Patents Pending 5

RCAT – a monolithic process flow MonolithIC 3D Inc., Patents Pending 6 Wafer, ~700µm ~100nm P- N+ P- Using a new wafer, construct dopant regions in top ~100nm and activate at ~1000º C Oxide

MonolithIC 3D Inc. Patents Pending 7 ~100nm P- N+ P- Oxide Implant Hydrogen for Ion-Cut H+ Wafer, ~700µm

MonolithIC 3D Inc. Patents Pending 8 ~100nm P- N+ P- ~10nm H+ Oxide Hydrogen cleave plane for Ion-Cut formed in donor wafer Wafer, ~700µm

MonolithIC 3D Inc. Patents Pending 9 ~100nm N+ P- Oxide 1µ Top Portion of Base Wafer H+ Flip over and bond the donor wafer to the base (acceptor) wafer Base Wafer, ~700µm Donor Wafer, ~700µm

MonolithIC 3D Inc. Patents Pending 10 ~100nm N+ P- Oxide 1µ Top Portion of Base Wafer Perform Ion-Cut Cleave Base Wafer ~700µm

11 ~100nm N+ P- Oxide 1µ Top Portion of Base Wafer MonolithIC 3D Inc. Patents Pending Complete Ion-Cut Base Wafer ~700µm

12 ~100nm N+ P- Oxide 1µ Top Portion of Base Wafer MonolithIC 3D Inc. Patents Pending Etch Isolation regions as the first step to define RCAT transistors Base Wafer ~700µm

13 ~100nm N+ P- Oxide 1µ Top Portion of Base Wafer MonolithIC 3D Inc. Patents Pending Fill isolation regions (STI-Shallow Trench Isolation) with Oxide, and CMP Base Wafer ~700µm

14 ~100nm N+ P- Oxide 1µ Top Portion of Base Wafer MonolithIC 3D Inc. Patents Pending Etch RCAT Gate Regions Base Wafer ~700µm Gate region

15 ~100nm N+ P- Oxide 1µ Top Portion of Base Wafer MonolithIC 3D Inc. Patents Pending Form Gate Oxide Base Wafer ~700µm

16 ~100nm N+ P- Oxide 1µ Top Portion of Base Wafer MonolithIC 3D Inc. Patents Pending Form Gate Electrode Base Wafer ~700µm

17 ~100nm N+ P- Oxide 1µ Top Portion of Base Wafer MonolithIC 3D Inc. Patents Pending Add Dielectric and CMP Base Wafer ~700µm

18 ~100nm N+ P- Oxide 1µ Top Portion of Base Wafer MonolithIC 3D Inc. Patents Pending Etch Thru-Layer-Via and RCAT Transistor Contacts Base Wafer ~700µm

19 ~100nm N+ P- Oxide 1µ Top Portion of Base Wafer MonolithIC 3D Inc. Patents Pending Fill in Copper Base Wafer ~700µm

20 ~100nm N+ P- Oxide 1µ Top Portion of Base (acceptor) Wafer MonolithIC 3D Inc. Patents Pending Add more layers monolithically Base Wafer ~700µm Oxide ~100nm N+ P-