"""Bondpad components for IHP PDK."""
import math
from typing import Literal
import gdsfactory as gf
from gdsfactory import Component
from gdsfactory.typings import LayerSpec
from kfactory.schematic import DSchematic
_XS = "metal1_routing"
def regular_octagon_points(diameter: float):
"""Create a regular octagon"""
side = diameter / (1 + math.sqrt(2))
R = side / (2 * math.sin(math.pi / 8))
start_angle = math.pi / 8
return [
(
R * math.cos(start_angle + i * math.pi / 4),
R * math.sin(start_angle + i * math.pi / 4),
)
for i in range(8)
]
def bondpad_schematic(
shape: Literal["octagon", "square", "circle"] = "octagon",
diameter: float = 80.0,
) -> DSchematic:
_shape_map = {"octagon": 0, "square": 1, "circle": 2}
s = DSchematic()
s.info["tags"] = ["IHP", "bondpad"]
s.info["symbol"] = "pad"
s.info["ports"] = [{"name": "PAD", "side": "top", "type": "electric"}]
s.info["models"] = [
{
"language": "spice",
"name": "bondpad",
"spice_type": "SUBCKT",
"library": "ihp/models/ngspice/models/sg13g2_bondpad.lib",
"sections": [],
"port_order": ["PAD"],
"params": {
"size": "diameter * 1e-6",
"shape": str(_shape_map[shape]),
"padtype": "0",
},
}
]
s.create_port(name="PAD", cross_section=_XS, x=0, y=1, orientation=90)
return s
[docs]
@gf.cell(schematic_function=bondpad_schematic)
def bondpad(
shape: Literal["octagon", "square", "circle"] = "octagon",
diameter: float = 80.0,
layer_top_metal: LayerSpec = "TopMetal2drawing",
layer_top_metal_pin: LayerSpec = "TopMetal2pin",
layer_passiv: LayerSpec = "Passivpillar",
layer_dfpad: LayerSpec = "dfpaddrawing",
bbox_offsets: tuple[float, ...] | None = (-2.1, 0),
flip_chip: bool = False,
) -> gf.Component:
"""Create a bondpad for wire bonding or flip-chip connection.
Args:
shape: Shape of the top-metal bondpad ("octagon", "square", or "circle").
diameter: Interpreted as across-flats for octagons / squares, and diameter for circles.
layer_top_metal: Top metal layer.
layer_passiv: Passivation-opening layer.
layer_dfpad: Deep-fill or density-fill support layer.
bbox_offsets: Per-layer expansion distances in micrometers, applied to the passivation and dfpad layers.
flip_chip: If True, suppress passivation opening for flip-chip bumps.
Returns:
Component containing the complete bondpad stack.
"""
c = gf.Component()
d = float(diameter)
# Add top metal layer
if shape == "square":
c.add_ref(
gf.components.rectangle(size=(d, d), layer=layer_top_metal, centered=True)
)
elif shape == "octagon":
pts = regular_octagon_points(d)
c.add_polygon(points=pts, layer=layer_top_metal)
elif shape == "circle":
c.add_ref(gf.components.circle(radius=d / 2, layer=layer_top_metal))
else:
raise ValueError(f"Unknown shape: {shape}")
# Add additional layers
if flip_chip:
# Skip passivation opening for flip-chip
bbox_layers = (layer_dfpad,)
bbox_offsets = (bbox_offsets or ())[1:]
else:
bbox_layers = (layer_passiv, layer_dfpad)
for layer, offset in zip(bbox_layers, bbox_offsets or ()):
new_d = d + float(offset * 2)
if shape == "square":
c.add_ref(
gf.components.rectangle(size=(new_d, new_d), layer=layer, centered=True)
)
elif shape == "circle":
c.add_ref(gf.components.circle(radius=new_d / 2, layer=layer))
elif shape == "octagon":
c.add_polygon(points=regular_octagon_points(new_d), layer=layer)
# Add port
c.add_port(
name="pad",
center=(0, 0),
width=d,
orientation=0,
layer=layer_top_metal_pin,
port_type="electrical",
)
# Add metadata
c.info["shape"] = shape
c.info["diameter"] = diameter
c.info["top_metal"] = layer_top_metal
return c
[docs]
@gf.cell
def bondpad_array(
n_pads: int = 4,
pad_pitch: float = 100.0,
pad_diameter: float = 80.0,
shape: Literal["octagon", "square", "circle"] = "octagon",
layer_top_metal: LayerSpec = "TopMetal2drawing",
layer_top_metal_pin: LayerSpec = "TopMetal2pin",
layer_passiv: LayerSpec = "Passivpillar",
layer_dfpad: LayerSpec = "dfpaddrawing",
bbox_offsets: tuple[float, ...] | None = (-2.1, 0),
) -> Component:
"""Create an array of bondpads.
Args:
n_pads: Number of bondpads.
pad_pitch: Pitch between bondpad centers in micrometers.
pad_diameter: Diameter of each bondpad in micrometers.
shape: Shape of the bondpads.
layer_top_metal: Top metal layer for the bondpad.
layer_passiv: Passivation layer.
layer_dfpad: Deep fill pad layer.
bbox_offsets: Offsets for each additional layer.
Returns:
Component with bondpad array.
"""
c = Component()
for i in range(n_pads):
pad = bondpad(
shape=shape,
diameter=pad_diameter,
layer_top_metal=layer_top_metal,
layer_top_metal_pin=layer_top_metal_pin,
layer_passiv=layer_passiv,
layer_dfpad=layer_dfpad,
bbox_offsets=bbox_offsets,
)
pad_ref = c.add_ref(pad)
pad_ref.movex(i * pad_pitch)
# Add port for each pad
c.add_port(
name=f"pad_{i + 1}",
center=(i * pad_pitch, 0),
width=pad_diameter,
orientation=0,
layer=pad.ports["pad"].layer,
port_type="electrical",
)
c.info["n_pads"] = n_pads
c.info["pad_pitch"] = pad_pitch
c.info["pad_diameter"] = pad_diameter
# TODO: Bondpad array VLSIR Metadata
return c
