MgO Deposition: (CpEt)2Mg + H2O

April 2014

A. O’Mahony, A. Mane, J. Elam

Early Attempt at Uniform MgO• 70 cycles (EtCp)2Mg/H2O: 6-35-1.5-30 @200oC• MgO measured on Si and MCP• MCP located at centre of 9 x MCP holder

• Expected GPC 1.4 Å/cycle: Up to 2x higher GPC on back of MCP compared to front• Non-uniformity in thickness will affect MCP gain

0 0.5 1 1.5 2 2.5 3 3.5 4 4.50

0.5

1

1.5

2

2.5

3

3.5

Top of MCPBottom of MCP

Precursor flow

Gro

wth

per

cyc

le (Å

/cyc

le)

Location on MCP (cm)

Front of MCPBack of MCP

20 μm monitor MCPs

10 μm dummy MCPs

10 μm dummy MCPs

Optimized Process

• Wedged holder with 9 x 9” holder for 53 mm MCPs

• 30 cycles (EtCp)2Mg/H2O:2-120-1-60 @200oC

inlet outlet

top

bottom

Substrate Layout:

MgO thickness measured:• On Si positioned beneath 9 MCP holder (8 x 8” Si)• On front and back surfaces of MCP – 5 points in each direction (2 x 2” MCP)

Measurement of MgO Thickness

Inlet Centre Outlet

topThickness measurement

on MCP

inlet to outlet

top

to b

ottom

• Si along length of reactor, 9 x MCPs: 1 monitor (centre)• Si std variation = 4%, GPC = 1.3 Å/cycle (direction: inlet-outlet)• Si std variation = 13%, GPC = 1.5 Å/cycle (direction: top-bottom)• Higher GPC on MCPs than on Si but good uniformity on both MCP surfaces

Run 040214-1 MgO: (CpEt)2Mg + H2O

Precursor flow

Thickness on Si (8 x 8” Si) Thickness on Centre MCP (2 x 2” MCP)

MCP front MCP back

Precursor flow

Precursor flow

• Si along length of reactor, 9 x MCPs: inlet and outlet monitors• Si std variation = 9.0%, GPC = 1.3 Å/cycle (direction: inlet-outlet)• Si std variation = 9.8%, GPC = 1.5 Å/cycle (direction: top-bottom)

Run 040214-2 MgO: (CpEt)2Mg + H2O

Thickness on Si (8 x 8” Si)

Precursor flow

Thickness on Inlet MCP (2 x 2” MCP) MCP front MCP back

Thickness on Outlet MCP (2 x 2” MCP) MCP front MCP back

• Reproducible MgO thickness on Si with 9 x MCPs • Slight depletion in precursor at outer most point of holder (run 2)• Decrease in MgO thickness from inlet to outlet but good uniformity

across MCP top and bottom surfaces for all 3 monitor MCPs

All data: Runs 1 + 2

Conclusions • Uniform deposition on individual MCPs (front and back surfaces) located

at inlet, centre and outlet positions• Decrease in MgO thickness across reactor but precursor depletion only

evident at outermost point on outlet MCP

Challenges:• Scaling to larger batches of 2 x 2” MCPs or 8 x 8” MCP• Substrates – require NiCr coated substrates for process optimization (need

reflective surface for ellipsometry to measure thickness)