COMPARISON OF THICK COPPER PLATINGRESULTS WITH LABORATORY AND INDUSTRIAL
ELECTROPLATING TOOLSDavid Bourrier, Arnaud Durlach

To cite this version:
David Bourrier, Arnaud Durlach. COMPARISON OF THICK COPPER PLATING RESULTS WITHLABORATORY AND INDUSTRIAL ELECTROPLATING TOOLS. Journées Nationales sur les
Technologies Emergentes en micro-nanofabrication (JNTE 2017), Oct 2017, Orléans, France. 1p.,
2017. �hal-01873753�

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COMPARISON OF THICK COPPER PLATING RESULTS WITHLABORATORY AND INDUSTRIAL ELECTROPLATING TOOLS.
David Bourrier, Arnaud Durlach
LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, Francee-mail of contact author: bourrier@laas.fr

INTRODUCTION
New power components, 3D inter-connexion, RDL, TSV… needs thicker and thicker metal layer. Electrochemistry is one of the most appropriate technology able to answer theseneeds by supplying metal plating from 1um to 500um thickness in accordance to any resist mold, design and shape, especially very high aspect ratio. However, the difficulty ofelectroplating processes resides in plating very thick metal layer while keeping a good inhomogeneity rate on the whole surface.
In order to reach this goal and complete our electroplating facilities, we purchased a new plating tool made by a Japanese company called YAMAMOTO. This paper will introduce
the first experiments we made with this equipment on thick copper plating and compare the results between our actual facilities and this new reactor.

EQUIPMENTBEAKER

INDUSTRIAL RENA

- Basic hand-made reactor
for 4”- 2,5L Table-top equipment.
- Flow ensured by magneticstirring- Wafer stand motionless infront of the anode- Use soluble copper
anode.
- Four metallic electriccontact.

YAMAMOTO PLATING SET- 4” and 6” industrial equipment.
- 13L Table-top equipment,- Flow ensured by electrolyte
pumping.
- Stirring ensured by a rocking
paddle.
- Wafer motionless in front of theanode.
- Use soluble copper anode.
- Adaptable distance between thewafer and the anode.
- Eight electric contacts- Industrial reactor for 4” and 6”
wafers.
- 25L integrated equipment.
- Flow ensured by electrolyte
pumping.
- Wafer motionlessperpendicularly to the flow.
- Use insoluble platinum anode.
- Adaptable distance between thewafer and the anode.
- Electric contact crown.

METHODOLOGYSETTINGS ADJUSTABLE ON EQUIPMENT
In order to conduct this study on each tool, we varied the following parameters using
two different mask design:

RESULTSBy varying each parameter, we were able to find the optimum plating parameterswhich allow us to reach the best metal distribution rate on 45 um thickness copper
layer and 20um thickness (non-ideally dispersed design) :Optimum parameters
Flow rate
Distance wafer/anodeStirring speedBeakernono1000 rpmVertical RENA
22L/min
2,7mm
noYamamoto
no21,5mm
105 rpm

IDEALLY DISPERSED DESIGNYAMAMOTO PLATING SET(from0to130rpm),apump
takescareofthebath
re-circulation
andyThen we used these optimum parameters to do a 20um thickness plating on nonandideallycan dispersed
be installed
directly on a workbench.
design.
The wafer is connected to the power supply by eight electrical contacts.
NON-IDEALLY DISPERSED DESIGN
The second mask has design with different
shapes (lines, squares, circles...) and sizes (from5um to 60um) non-ideally dispersed on thewafer, according to micro fabrication processes
with different sized components.
On the second mask, we measured the thickness of all the 5,10,15,20,30 and 60um
lines dispersed on the wafer which represent 120 measurements points.

CALCULATION METHOD
𝑚𝑎𝑥 𝑣𝑎𝑙𝑢𝑒 − 𝑚𝑖𝑛 𝑣𝑎𝑙𝑢𝑒
𝐼𝑛ℎ𝑜𝑚𝑜𝑔𝑒𝑛𝑒𝑖𝑡𝑦 % =× 100
𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑣𝑎𝑙𝑢𝑒

BEAKER:
Metal distribution according to stirring speed
18

RENA TOOL:
Metal distribution according to flow rate and distance

16,96%

1412,13%12107,96%864200200% inhomogeneity Vs Paddle Speed
9,00
8,007,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00

8,40

4,2
3,07
2,27

50

25,0

16

400

600

800

1000

1200

65

105

105

% inhomogeneity Vs Distance

20,0
15,01cm
1.4cm

10,0

1.7cm
5,02cm

5,5

8
7
6
5
4
32
1
0

7,32

20,5

21

21,5Stirring speed in rpm

22

22,5

23

23,5

7,2
5
4,2

60,0

78

10

% inhomogeneity

24

Flow rate in L/min

NON-IDEALLY DISPERSED DESIGN
Metal distribution according to design width

The following figure show theinhomogeneity evolution
according to design width on nonideally dispersed design.
We can notice that inhomogeneity
gap between biggest and smallest
design is clearly more importanton the beaker, than with otherequipment.

16Beaker
1412

Metal distribution in %With this mask, we varied several parameters on each toolaccordingto our bath
before motionlessmeasuring thickness” wafers. During a platingprocess,
therestrictions
wafer stands
in front
on 9 points ideally dispersed on the wafer, theseof the soluble anode,
itispossible
tovarythedistance
betweenthemeasurements allowed us to determine the optimum
wafer and this anodeby movingthetheanode(fromdistribution
15 to 100mm).
parameters
to reachbest metal
rate withThedispersed
design:stirring is made by aideallyrockingpaddle
which is moving parallel to the wafer

Metal distribution in %The first mask design has 2.5mm squares ideally dispersed on the wafer.

The following figure show the metal distribution according
to several parameters on ideally dispersed design, thesefigure allowed us to find the optimum parameters:

Metal distribution in %IDEALLY DISPERSED DESIGN

108Yamamoto

64

RENA vertical20102030
Design widthness40
in um5060

Global Inhomogeneity

Beaker

Vertical RENA

Yamamoto

Ideally dispersed design
non-ideally dispersed design

7,9%
32,8%

5,5%
23,5%

2,3%
8%

70

CONCLUSION AND PERSPECTIVESOur experiment helped us to determine that all our plating tools are able to reach a good metal distribution rate, even if our results are unequal. In fact, Beaker and RENA tools
are efficient, but still have an important inhomogeneity on non-ideally dispersed design. To fill this gap, we tried the YAMAMOTO Japanese plating set which has just come to theEuropean market.
Even with our first experiment, we already obtained as good or better results than with our actual equipment. We succeeded not only to reach the best metal distribution
thickness rate with any design shape or width, but we also found the most flexible equipment which allow us to easily transfer optimum parameters to a new design while
keeping good results without doing a new optimization each time. Last but not least, the compact shape of the YAMAMOTO plating set allows us to easily change the plating bathand give us a full access if maintenance is needed.
LAAS-CNRS/ Laboratoire d’analyse et d’architecture des systèmes du CNRS

Laboratoire conventionné
avec l’Université Fédérale
Toulouse Midi-Pyrénées