Metal Etching

icp-al

Aluminum (Al)

This BCl3/Cl2 based process is a very chemical etch. Pure aluminum, by itself, etches readily in a Cl2 plasma. However, a native oxide layer covers all aluminum films, so BCl3 is added to increase the amount of sputtering and to scavenge the oxygen in the aluminum oxide layer. A burst step may be required to break through any native oxides that may have formed on the surface. Processes have been developed with etch rates of over 2,000 Å /min


Gold (Au)

Using a low pressure ICP-based process involving chlorine and argon is sufficient to etch this metal at room temperature at rates of up to 700 Å /min. Higher temperature will increase the rate.


cu

Copper (Cu)

Copper processing has specific challenges with respect to etching because it requires low volatility for CuClx (for chlorine etching) species, it has a high oxidation rate, and it does not self-passivate. The industry has conducted many tests to address these issues, and Trion has developed a “formula” that works. This Chlorine based process requires the sample to be heated above 150C and can produce etch rates of over 5,000 Å /min.


cr

Chrome (Cr)

This Chlorine based process will etch Chrome controllably. The process is dominated by both a kinetic, and reactive mechanism at rates of over 800 Å /min. There is a wide process window under optimized process conditions as we see no trace of either photo resist burning or any visible roughness in the form of micro-masking.


pt

Platinum (Pt)

Using a low pressure ICP-based process involving chlorine and argon is sufficient to etch this metal at room temperature at rates over 1100 Å /min. Higher temperature will increase the rate if using an oxide mask.


 

Platinum 3000 Hardmask

Platinum (Pt)

Platinum with 3000 Å SiO2 hard mask. Argon, Cl2, RIE turbo pump, heated chuck, rate ~1000 Å/minute. Temperature – 90C, Selectivity (Pt:SiO2) = 20:1


APPLICATION NOTES

Aluminum Etch
Application: Failure Analysis; Metal Etching Aluminum
Trion Tool: Minilock-Phantom RIE or Oracle
“Etching was done using Boron Tri-chloride (BCl3) and Chlorine (Cl2) gas …”

Aluminum Etch
Application: Failure Analysis; Metal Etching Aluminum
Trion Tool: Minilock-Phantom RIE
“Aluminum etching is one of the most difficult processes. However, if done correctly very good etch results can be obtained. A good starting recipe for more uniform but isotropic etching of the Al is: …”
Copper Etch using Trion Minilock-Phantom RIE
Gold and Platinum Etch using Trion Minilock-Phantom RIE
Metal Etch using Minilock-Phantom RIE ICP

PAPERS

Planar Deprocessing Of Advanced VLSI Devices
by K. Wills, Texas Instruments
Application: Failure Analysis; Dielectric Etching; Metal Etching Copper

Reliability Issues And Advanced Failure Analysis Deprocessing Techniques For Copper/Low-K Technology
by H. Wu, J. Cargo, C. Peridier and J. Serpiello (Agere Systems, IC Quality Organization, Product Analysis Lab, Allentown, PA)
Application: Failure Analysis; Dielectric Etching; Metal Etching Copper
Trion Tool: Phantom RIE

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