05 Making it

From powder to chip

Process viewer: 30 steps, 2 device routes

L1. Every lithium niobate device starts as two white powders, lithium carbonate and niobium pentoxide, melted near 1255 °C and pulled into a single crystal on a rotating seed. The crystal is sawn into wafers, and for modern photonics a layer about 600 nm thick is peeled off a wafer, bonded to oxidized silicon, and etched into waveguides narrower than a micrometre.

Process viewer: x-cut TFLN Mach-Zehnder modulator, charge to fibered chip01/23

t 0.00

#	STEP	TOOL	T_PROC	STATUS MIX
01	Weigh and react Li2CO3 + Nb2O5 to a congruent charge	crucible charge	n/a	1r 3d 0t 1n a1
02	Melt the charge	Cz puller	n/a	1r 0d 1t 1n a1
03	Czochralski growth (seed, neck, shoulder, body, tail)	Cz puller	55–110 h	5r 2d 2t 0n a5
04	Anneal and pole the boule to a single domain	poling furnace	n/a	1r 0d 1t 2n a1
05	Orient, flat, and slice into x-cut wafers	wire saw	n/a	2r 0d 1t 2n a1
06	Lap and polish (optical grade)	CMP polisher	n/a	0r 0d 0t 1n
07	Prepare the handle wafer (Si with thermal SiO2)	oxidation furnace	n/a	2r 0d 0t 1n
08	He+ implantation into the LN donor	ion implanter	n/a	6r 0d 1t 1n a6
09	Clean, plasma-activate, flip, and bond donor to handle at room temperature	wafer bonder	n/a	4r 0d 0t 0n a4
10	Strengthening anneal, then split at the implanted plane	anneal oven	n/a	4r 1d 0t 0n a4
11	Edge removal and CMP of the split surface to target thickness	CMP polisher	n/a	3r 1d 2t 0n a2
12	Recovery anneal of the film (wafer supplier step)	anneal oven	n/a	0r 0d 0t 1n
13	PECVD SiO2 hard mask	PECVD	n/a	1r 0d 0t 1n
14	Spin ARC and DUV photoresist	spin coater	n/a	2r 0d 0t 1n
15	DUV stepper exposure, step-and-repeat	stepper	< 1 min	4r 1d 0t 0n
16	Develop; etch ARC (Ar/O2) and SiO2 (C3F8)	RIE	n/a	2r 0d 0t 0n
17	Ar ICP-RIE of LN (ridge)	ICP RIE	12.5 min	6r 0d 1t 0n a2
18	Strip resist and SiO2 hard mask in HF	wet bench	n/a	1r 0d 0t 1n
19	PECVD SiO2 cladding	PECVD	n/a	1r 0d 0t 0n
20	Au traveling-wave electrodes by lift-off	e-beam evaporator	n/a	4r 0d 0t 1n a4
21	Dice and polish facets	dicing saw	n/a	0r 0d 1t 1n
22	Align and attach fibers to edge couplers	fiber aligner	n/a	1r 0d 0t 1n a1
23	RF probe or wire bond to the electrode pads	RF probe	n/a	0r 0d 0t 1n

Weigh and react Li2CO3 + Nb2O5 to a congruent charge

                                                
                                                
                                                
                                                
                                                
                                                
                                                
                                                
                                                
                                                
                                                
                                                
                                                
                                                
                                                
                                                
                                                
                                                
U                                              U
U                                              U
U                                              U
U                                              U
U::::::::::::::::::::::::::::::::::::::::::::::U
UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU

boule scale: crystal 153 mm × 110 mm to scale; 1 row = 10 mm

U crucible: powder charge

Step	01/23
Route	Ridge, DUV + SiO2 mask (Luke 2020)
Equipment	crucible charge: crucible with powder charge
Process time	n/a not reported	n/a
composition Li₂O	48.45 mol%	reportedanalog
Li₂CO₃ per kg LN	0.25 kg/kg	derived
Nb₂O₅ per kg LN	0.899 kg/kg	derived
CO₂ released per kg LN	0.149 kg/kg	derived
calcination temperature	n/a	n/a

No time profile for this step.

Badges: reported (anchor or analog paper at the locator), derived (computed from other step values), template (not reported; illustrative), n/a (not reported, not drawn). Playback: 6 s per step at 1x; real process time in the HUD. Stepper fields per 100 mm wafer: 6 (derived).

01/23Crystal

Weigh and react Li2CO3 + Nb2O5 to a congruent charge

2D cross-section; no 3D model for this step

cruciblepowder charge

boule scale: crystal 153 mm × 110 mm to scale; 1 row = 10 mm.

Badges: reported anchor or analog paper at the locator, derived computed from other step values, template not reported, illustrative; n/a: not reported, not drawn. Status mix: reported, derived, template, n/a, and analog count. Playback 6 s per step at 1×; real process time in the HUD. Stepper fields per 100 mm wafer: 6 (derived). Keys with the viewer focused: space, arrows, shift+arrows, [ ].

Sections

No.	Section	Figures	Process viewer steps
5.1	Raw materials: Li2CO3 and Nb2O5	From rock to chip	01
5.2	Growing the crystal	Czochralski growth and composition	02 03 04
5.3	Wafers	Wafer cut and crystal axes	05 06
5.4	Waveguides in bulk wafers (1974 to today)	Proton-exchange depth, Ti recipes	–
5.5	Thin film: lithium niobate on insulator (LNOI)	Ion slicing: implant depth and heat steps; CMP thickness and film colour	07 08 09 10 11 12
5.6	Wafer sizes and suppliers (as of 2026-10-24)	–	–
5.7	Patterning: lithography, masks, and etching	Pattern writing time; Argon etching: sidewall and redeposition; Loss by fabrication route	13r 14r 15r 16r 17r 18r 13s 14s 15s 16s 17s
5.8	Cladding and annealing	–	19r
5.9	Electrodes	–	20r 18s
5.10	Periodic poling of thin films	Thin-film poling field	–
5.11	Dicing, facets, packaging, fiber attach	–	21r 19s 22 23
5.12	The Process viewer	Process viewer	–

Step numbers follow the ridge route (r: ridge only, s: strip only). Each viewer value has a status badge: reported, derived, or template; analog values come from a paper other than the route's anchor or from LiTaO₃.