Specific Process Knowledge/Etch/DRIE-Pegasus/processB

Process B

Process B is labelled Via (30μm diameter) 100μm depth. In the acceptance test the process was run on a 150 mm SPTS wafer with 12-13 % etch load.

Process B specifications

Parameter	Specification	Average result
Etch rate (µm/min)	> 10	10.7
Etched depth (µm)	100	107
Scallop size (nm)	< 800	685
Profile (degs)	91 +/- 1	90.7
Selectivity to AZ photoresist	> 100	183
Undercut (µm)	<1.5	0.89
Uniformity (%)	< 3.5	2.7
Repeatability (%)	<4	0.47

Process B recipe

Main etch (D->E)	Etch	Dep
Gas flow (sccm)	SF6 350 O2 35	C4F8 200
Cycle time (secs)	7.0	4.0
Pressure (mtorr)	20 (1.5 s) 100	25
Coil power (W)	2800	2000
Platen power (W)	130 (1.5) 40	0
Cycles	55 (process time 10:05)
Common	Temperature 10 degs, HBC 10 torr, Short funnel, with baffle & 5mm spacers

Experiment with process B performance

Purpose

Perhaps the most commonly occuring question posed by users of the dry etch tools is something like ' I want to etch my trenches down to a depth of 40 microns, how long should I etch?'. The answer is that it depends on the width of the trench and on the etch load of your design (that is how many percent of the wafer it etched).

An experiment has been set up to investigate the etched depth of a number of different trenches (with widths ranging from 2 microns to 300 microns) as a function of etch load (the exposed area ranges from 5 % to 65 %)

Results

A number of wafers are patterned with the travka masks.

• The results of the nano1.0 recipe
• 
• 
  The 60 nm trenches