Specific Process Knowledge/Thin film deposition/Electroplating-Ni

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Technotrans microform.200

Electroplating-Ni positioned in cleanroom A-1

The Technotrans microform.200 (Electroplating-Ni in LabManager) is a machine capable of depositing nickel electrochemically. This is done by lowering the sample into an electrolyte containing nickel ions and then apply a voltage across the sample and the anode. The anode is a titanium basket filled with nickel pellets. The cathode is the sample to be coated with nickel.

At the anode metallic nickel is oxidized to nickel ions:

Ni (s) ⇒ Ni²⁺ (aq) + 2 e^-

At the cathode (the sample surface), nickel ions from solution are reduced to metallic nickel:

Ni²⁺ (aq) + 2 e^- ⇒ Ni (s)

The minimal charge accepted by the software on the machine is 0.1 Ah (Ampere-hours). This corresponds to roughly 2 µm of nickel on a four inch wafer. You can abort a program prematurely to achieve even lower thicknesses, but this requires manual control of the machine.

The maximum allowed thickness is ~1,4 mm (1400 µm), since a higher thickness will make the release of the sample difficult and likely damage the sample holder. This corresponds to a charge of 53-54 Ah on a four inch wafer. Please contact Danchip before processing your wafer if you intend to deposit more than ~500 µm of nickel, since this can involve special challenges regarding uniformity, roughness and sample release after plating.

The plating bath is an aqueous solution of nickel sulfamate, boric acid and sulfamic acid. The bath is moderately acidic (pH = 3,70). The pH is kept constant by an automatic pH measurement and sulfamic acid dosing module. The temperature of the bath is 52°C. The sample will spin at 60 RPM during deposition.

Uniformity across a 4" wafer is around 5% for the standard processes (the edge being slightly thicker than the center of the sample). Running at high current densities will deposit a nickel layer that is quite soft. Decreasing current density will increase tensile strength of the deposited nickel.

The user manual(s), quality control procedure(s) and results, user APV(s), technical information and contact information can be found in LabManager:

Electroplating-Ni Info on LabManager

Process information

• Description of standard processes

Equipment performance and process related parameters

Parameter		Value
Sample dimensions	Diameter	50, 100 or 150 mm (~ 2", 4" or 6")
	Sample thickness	Maximum 1,0 mm
Process parameters	Temperature	52°C
	pH	3,5 - 3,8
Sample requirements	Seed metal	Most commonly ~85 nm of NiV
	Allowed materials	Most materials allowed. See below.
	Forbidden materials	Copper, cobalt. See machine manual on LabManager for details

Equipment		Electroplating-Ni
Purpose		Electrochemical deposition of nickel
Performance	Thickness	0 - 1400 µm
	Uniformity	Around 5-10% (depending on sample and process)
Process parameter range	Temperature	52°C
	pH	3,75 (3,5 - 3,8 recommended by manufacturer)
Substrates	Batch size	# 1 x 50 mm wafer # 1 x 100 mm wafer # 1 x 150 mm wafer Maximum sample thickness: 1,0 mm
	Allowed materials	Most materials except copper and cobalt. Ask Danchip for details.