The CAP_TOP_METAL layer is used exclusively for the construction of metal-to-metal capacitors. The bottom plate of the capacitor is one of the regular metal layers, as specified below. CAP_TOP_METAL is the upper plate of the capacitor; it is sandwiched physically between the bottom plate metal and the next metal layer above, with a thin dielectric between the bottom plate and the upper (CAP_TOP_METAL) plate.
The CAP_TOP_METAL can only be contacted from the metal above; the bottom plate metal can be contacted from below or above (subject, in either case, to rule 28.5), and/or by bottom metal extending outside of the capacitor region (rule 28.7). Use of all (legal) upward vias within that region should be maximized. CAP_TOP_METAL must always be contained entirely within the bottom plate metal.
These are generic design rules. For TSMC02d, you need to use the rule numbers in the DEEP column and multiply the values by λ=0.09μm.
| Process | Bottom Plate | Top Plate | Top Plate Contact |
| TSMC_025 | METAL4 | CAP_TOP_METAL | VIA4 and METAL5 |
| TSMC_018 | METAL5 | CAP_TOP_METAL | VIA5 and METAL6 |
| Rule | Description | Lambda | ||
| SCMOS | SUBM | DEEP | ||
| 28.1 | Minimum Width, Capacitor | n/a | 40 | 45 |
| 28.2 | Minimum Spacing (2 capacitors sharing a single bottom plate) | n/a | 12 | 14 |
| 28.3 | Minimum bottom metal overlap (including dummy shapes) | n/a | 4 | 5 |
| 28.4 | Minimum overlap of via | n/a | 3 | 3 |
| 28.5 | Minimum spacing to bottom metal via | n/a | 4 | 5 |
| 28.6 | Minimum bottom metal overlap of its via | n/a | 2 | 2 |
| 28.7 | Rule applicability region extends beyond bottom plate | n/a | 25 | 25 |
| 28.8 | Minimum width, dummy shapes (having no vias) | n/a | 4 | 5 |
| 28.9 | Minimum bottom plate to other bottom plate metal | n/a | 8 | 9 |
| 28.10 | Minimum via separation, on CAP_TOP_METAL | n/a | 20 | 23 |
| 28.11 | Minimum (upward) via separation on bottom metal | n/a | 40 | 45 |
| 28.12 | Maximum CAP_TOP_METAL width and length | n/a | 30 um | |
| 28.13 | Maximum bottom metal plate width and length | n/a | 35 um | |
| 28.14 | No vias from bottom plate downward, directly under top plate CAP_TOP_METAL; dummy metal shapes under capacitor region, discouraged. | |||
| 28.15 | No active or passive circuitry under capacitor region | |||