Method to form S/D contact with negligible SAC cap erosion.

Title Method to form S/D contact with negligible SAC cap erosion Abstract Disclosed is a method to form Co source/drain (S/D) contact metallization with negligible self-aligned contact (SAC) cap erosion. Problem The Middle-of-Line (MOL) module is one of the key processes determining device yield. Co-metallization poses another challenge due to its difficulty to control Co Chemical Mechanical Planarization (CMP) without eroding self-aligned contact (SAC) cap (i.e., too much SAC cap erosion can lead to CA to Gate shorting). High SAC cap erosion requires tall dummy PC, which causes many process challenges including in dummy PC reactive ion etch (RIE), spacer module, POC module, and replacement metal gate (RMG) module to take into account high SAC cap erosion. Figure 1: POR TS(S/D) Co CMP

Figure 2 illustrates the problem: Co/TiN liner can be selectively polished to SiO2 ILD or SiN SAC Cap. Buff CMP is a non-selective process that has to remove a total step height of 30nm of Co/TiN/ Oxide/ SiN with selectivity to one (1) for all materials. There is no such CMP process, thus leading to excessive cap SiN loss and non-uniformity that leads to TS to PC shorts.

Figure 2: Problem Statement

Solution/Novel Contribution The novel solution provides a method to form Co source/drain (S/D) contact metallization with negligible SAC cap erosion. Prior Art/Existing Solution:

1. TS RIE TiN liner / Co deposition

2. Main (P1) CMP 3. Over (P2) CMP (uncontrollable)

Novel Solution:

1. TS RIE 2. TiN li...