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Overview of Etchers Available at SNF

The following is a detailed overview of all the etchers aat SNF. This list is courtesy of Jim McVittie

 

Overview of Etchers Available at SNF

 

MRC- Simple manual load RIE (parallel plate with power to wafer electrode) without load lock
and without He back side cooling.

 ·         It is for non-critical etching using oxygen and F chemistry only.

 ·         No endpoint detection.

 ·         Pressure: 5 to 100 mT using diffusion pump.

·         This is considered a low plasma density tool.

 ·         General purpose tool open to all materials with no toxic products.

 ·         Gases: O2, Ar, SF6 and CHF3

 

 P5000- 3 chamber auto load locked MERIE (magnetically enhance RIE) etcher with clamping and He
backside cooling. The chambers are dedicated to;

 ·         A - Metals  -- Mainly uses for Al. Great for TiN. Has Ar, Cl2, BCl3, N2, CF4 and SF6

 ·         B - Oxide -- Mainly used for SiO2 and Si2N3 etching. Has Ar, CF4, CHF3, N2 and O2

 ·         C - Si -- Mainly used for Poly Si and Si trench etching.  Has Ar, Cl2, HBr, NF3, SF6
and He/O2

 

This tool is restricted to "clean" ( no Au) materials.

 Each chamber has its own OES spectrometer for endpoint.

 

 Although we do breakthrough steps at 30 mT for increased ion energy, the tool has small turbo
pumps so most for the processes are done higher pressures, typically in the 200 mT range.  The
rotated magnetic field yields higher plasma densities (higher rates), lower bias voltage for a
given power and more ion directionality for a given pressure than RIE.  The tool can be operated
as a pure RIE tool by turning off the magnetic field. This tool is considered a medium plasma
density tool because of the effect of the magnetic field. This is the workhorse etcher for the
standard Si processing. While lower pressure tools, such as the Lam TCP/ICP, can achieve smaller
line widths, the P5000 meets most of small CMOS as needs.

 

 Pquest- Load locked ECR (magnetic field used to couple uwave power to plasma) etcher dedicated
mainly to III-V etching with other materials allows on limit basis.

 ·         It uses a mechanical clamp with He.

 ·         It has a separate rf bias supply to control ion energy.

 ·         Like the STS2, it uses multipole magnetic confinement around the outside of the
chamber, to minimize plasma wall loss between the ECR zone and the wafer.

 ·         Gases include: Ar, Cl2, BCL3, N2, H2, O2, CF4 and SF6.

 ·         The III-V users are concerned about F and Cl interaction so they divide the tool time
between F only and Cl only periods and require a wet clean after the F use period.

 

Lam Poly- ICP (inductive coupled plasma) etcher with a load lock, mechanical clamp and He
cooling. For marketing purposing the flat ICP coil design is referred to as TCP (transform
coupled plasma) although all ICPs can be describes as TCPs. 

 ·         Has large turbo pump so it can work at low pressures where the mean free path lengths
are longer so one gets more directional ions, which means it can etch smaller line widths.

 ·         Because the inductive coupling allows high plasma density at low plasma potentials,
a second rf supply can be used with capacitive coupling to control the sheath voltage at the
wafer to control ion energy and directionality at the wafer surface.

 ·         The Lam is a "clean" tool dedicated to poly and Si etching.

 ·         It has very good line width resolution.

 ·         Its gases include: Cl2, HBr, C2F6, Cf4, SF6, O2, N2 and He/O2.

 ·         The SF6/O2 process tends to have grass (micro-masking) because Al2O3/Al sputtering
from the clamp. SF6/Cl2 gets around the grass problem because the Cl removes the Al.

 ·         It has narrow band optical filters for OES endpoint.

 

STS1- First generation switched Bosch process (repeated cycle of separate deposition and etch
steps) deep Si etcher.

 ·         600w ICP tool with mechanical clamp, He cooling and wafer bias (13.56MHz).

 ·         Does not have pulsed low frequency biasing for eliminating notching with SOI wafers.

 ·         This tool is still the workhorse for deep Si etching in the lab.

 ·         Gases: Ar, SF6, C4F8 and O2. It has no endpoint monitoring.

 

 STS2- 2nd generation switched Bosch process deep Si etcher. 3000w ICP tool with mechanical clamp, He cooling and wafer bias (13.56MHz).

 ·         It has both high frequency (13.56MHZ) and low frequency (350KHz) bias power. The low
frequency can be pulsed for eliminating notching in SOI wafers.

 ·         It also has heaters to minimize polymer deposition on the walls and ICP ceramic.

 ·         Has suffered from poor ICP RF power matching during switched process. Labmembers must consult with responsible staff member before running a new recipe.

 ·         Tool gives good results for users who spend the time to tune the process for their
needs.

 ·         Currently, there is lots time available on this tool.

 ·         It is presently a "clean" tool so it is restricted to clean materials. We have both
4" and 6" wafer chucks for this tool.

 ·         The chuck temperature can be controlled from 40 to -20C although the actual wafer
temperature is 100C or higher for typical ICP powers.

 ·         Gases: Ar, SF6, C4F8 and O2. It has no endpoint monitoring.

 

PT-DSE- 3rd generation switched Bosch process deep Si etcher.  3000w ICP tool with mechanical clamp, He cooling and wafer bias (100KHz). This tool is made by PlasmaTherm (PT)

 ·         To get fast stable switching it has ALD style gas switching, ICP frequency tuning
during the switched process and an improved pressure switching algorithm.

 ·         In addition, the bias power has pulse modulation for processing SOI wafers.

 ·         Like STS2, it has a complement of heaters to minimize chamber deposition. This is a
new tool whose initial etch results look great.

 ·         Users are just beginning to use it.

 ·         This is a "gold" machine for non-CMOS compatible wafers.

 ·         Gases: Ar, SF6, C4F8 and O2.

 ·         The chuck temperature can be controlled from 40 to -40C although we have not tested
the actual wafer temperature during an etch process.

 

 PT-Metal- New ICP etcher dedicated for etching metals and process related material.

 ·         It has a large turbo pump so it can be operate down a few mT.

 ·         The ICP has a 2500w generator (2MHz) with a 600w bias generator (13.56MHz).

 ·         Like our other PT etchers, it has wall and ICP heaters to minimize chamber deposition.

 ·         The wafer chuck has a mechanical clamp with He cooling and has temperature is control
from 10 to 60C. 

 ·         Like STS2, we have both 4" and 6" wafer chucks for this tool.

 ·         Initially, it has Al and Ti/W etch processes. Al process should be great for TiN
etching. It has a Cr process still to be tested.

 ·         This is a "gold" machine for non-CMOS compatible wafers.

 ·         Gases: Cl2, BCl3, SF6, O2, N2, Ar, CF4, and CH4.

 ·         For endpoint control it has an Ocean Optic spectrometer for OES and a laser for
interferometry.

 

PT-Dielectric- New ICP etcher dedicated for etching dielectrics and process related material.

 ·         It has a large turbo pump so it can operate down a few mT.

 ·         The ICP has a 2500w generator (2.5MHz) with a 600w bias generator (13.56MHz).

 ·         Like our other PT etchers, it has a wall and ICP heaters to minimize chamber deposition.

 ·         The chuck has a mechanical with He cooling and temperature control from 40 to -40C.

 ·         Initially, it has Al and Ti/W etch processes.

 ·         This is a "gold" machine for non-CMOS compatible wafers.

 ·         Gases: Cl2, BCl3, SF6, O2, N2, Ar, CF4, and CH4.

 ·         It has an Ocean Optic spectrum for OES endpoint in addition to laser interferometry.

 

Oxford III-V- New ICP etcher dedicated for etching III-V materials. Like the other ICP tools,
it has a load lock, a mechanical clamp and He backside cooling.

 ·         Has processes for GaAs, GaAlAs, GaP, InP and GaN.

 ·         InP can be etched hot (170C) using Cl2 based process and room temperature using a
CH4/H2 process. Sample heating can be done either by heating the chuck or by plasma heating.

 ·         Has laser interferometry for endpoint.

 ·         The large turbo pump allows processing down to 2 mT.

 ·         Gases include: BCl3, SF6, Cl2, HBr, H2, Ar, N2, and CH4.

 ·         There are heaters for heaters for the chamber and ICP source to minimize deposition.

 

AMT Etcher- This an old Applied Material 8110 Hexode (SS bell jar with center electrode) for
batch RIE processing.

 ·         It is a “clean” tool dedicated to oxide and nitride etching which has etch rate
about 10X less that the P5000 but a bit better selectivity but can 20 wafers at a time. It
also does great anisotropic (low selectivity and low rate) Si etching using NF3.

 ·         It has a medium sized turbo pump so it works well down to 20 mT.

 ·         It has laser interferometry which is currently not used.

 ·         Its gases are Ar, N2, CHF3, O2, SF6 and NF3.

 

Drytek2- Plasma mode (wafers on ground electrode) non-load lock and unclamped for F bases
etching of poly-Si, Si, nitride and related materials.

 ·         Also used for descuming resist and removal of plasma damage such as after oxide
etching in AMT etcher.

 ·         Has laser interferometry which is not currently used. It has 6 electrodes (4 for
clean work) for batch processing.

 ·         It uses a wet mechanical pump and blower so it is limited to pressures above 100 mT.

 ·         It was purchased in 1981.

 ·         Its poly etch(SF6/F22)process is semi-anistropic with a 0.1 um undercut.

 ·         Its isotropic Si/Poly etch (CF4/O2 at 700 mT) is extremely isotropic (same etch
rate everywhere in a structure).

 ·         Gases: CF4, SF5, F22 (CHClF2) and O2  

 ·         It is both a "clean" and “contaminated” tool.

 

 Drytek4- RIE mode non-load lock and unclamped for F bases etching.

 ·         This tool is an open tool mainly used by III-V users for nitride mask etching. The
III-V user will probably mover to one of the new PT tools.

 ·         Like the other Drytek it has a mechanical pump but because of its small chamber, it
is operated below 100 mT.

 ·         Gases: Ar, SF6, CHF3, and O2.

 

Matrix- Downstream plasma tool for O2 plasma resist stripping for general use.

 ·         This is a single wafer tool with auto load from a 25 wafer cassette

 ·         Downstream means that there are baffles between the wafer and the rf generated plasma
so reactive Ox radicals can make it to the wafer but not the plasma. This eliminates plasma
damage to sensitive surfaces.

 ·         It has programmable lift pins, which allow the wafer to be either room temperature
(pins up) or hot (pins down) with the wafer in contact with a 180C heated stage.

 ·         Resist stripping is strong temperature activated.  With the pins down the strip
rate > 1 um/min, but with pins up the rate is a few hundred A/min.

 ·         While a plasma stripper can remove organic polymers, such as resist, it does remove
metals which will often remain on the surface as a metal oxide. This is why one usually needs
to do a wet clean after a plasma strip. A descum process can be done at lower power and pressure.

 ·         This is an open tool so Au is allowed.

 ·         It only has one gas, O2.

 

Gasonics- Downstream plasma tool for O2 plasma resist stripping for “clean” wafers.

 ·         This is a single wafer tool with auto load from a 25 wafer cassette

 ·         Like the Matrix, there are baffles between the wafer and the plasma but this tool
uses microwave power to generate the plasma.

 ·         This system uses lamps for the heating. The caution with using lamp heating is that
the heating depends on what is on the wafer surface. Oxide, metal poly-Si and implantation can
all affect the wafer temperature and thus the strip rate.

 ·         This is an “clean”.

 ·         Gases: N2 and O2

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