Aluminum Etchants

Etchant for Aluminum Metallizations in Microelectronics

Chemical etchants compatible with negative and positive photoresists for developing ohmic contacts and interconnections in integrated circuits, transistors, diodes, MOD and FET devices.

ALUMINUM ETCHANT – TYPE A
Standard aluminum etchant for use on silicon devices and other microelectronic applications

ALUMINUM ETCHANT – TYPE D
Standard aluminum etchant for use on gallium arsenide, arsenide and gallium phosphide devices and for aluminum metallizations on nichrome resistors. Nitric acid-free.

FEATURES

  • Controlled etch rates
  • Selective etching: will not attack SiO2 or Si3N4
  • Offers high resolution with minimal undercutting
  • Eliminates smut formation
  • Economical; reusable

ALUMINUM ETCHANTS
DESCRIPTION:

Transene Aluminum Etchants are stable, non-toxic preparations used to etch aluminum metallizations on silicon devices and in integrated circuit applications. Aluminum contacts are defined, and interconnections are formed. These Aluminum Etchants, formulated with unique properties, easily overcome many of the difficulties experienced in aluminum etch processes.

The aluminum metallization and etching process using photo-lithographic techniques is basic to semiconductor and microelectronic technology. Transene Aluminum Etchants are highly compatible with commercial photoresists (KTFR, AZ, Hunt, Waycoat, etc.) and permit delineation into high resolution patterns. Metal line width of 1 mil and separations less than 5 microns are feasible. High resolution is practical with Transene Aluminum Etchants because lifting of photoresist patterns does not occur and undercutting is minimized. Furthermore, the etchants do not attack silicon, silicon dioxide, silicon nitride or nichrome resistor films.

Two aluminum etchants are offered for use in microelectronics. Type A is recommended for use on silicon devices. Type D is recommended for use on gallium arsenide and gallium phosphide devices to avoid attack of the etchant on the intermetallic compound. It is also recommended for etching aluminum metallizations on nichrome thin film resistors.

PROPERTIES OF TRANSENE ALUMINUM ETCHANT TYPE A

How do I increase the etch rate? 1. The rate will approximately double with every 10°C increase in temperature.
2. Increase the rate of stirring or agitation.
How do I reduce the etch rate? Adding 1 part deionized water to 2 parts etchant will reduce the etch rate approximately 50%.
Do I need to dilute the etchant? No, it is ready to use.
How do I reduce undercutting? Increase the rate of stirring or agitation.
Appearance Water-white to light yellow
pH Strongly acidic
Etch Rate at 25°C
40°C
30 Å/sec.
80 Å/sec
Etch Capacity (rate declines at ~70%) 60 g/gallon
Shelf Life 1 year
Storage Conditions Ambient
Filtration 0.2 um
Recommended Operating Temperatures 20-80oC (30-40oC most common)
Rinse Deionized water; may be followed by alcohol rinse if desired.
Photoresist Recommendations KLT6000 Series, KLT 5300 Series, HARE SQ (SU-8 type), TRANSIST, or PKP II
Select Compatible Materials Silicon oxide, gold, nichrome

See http://transene.com/etch-compatibility/ for more details.

Select Incompatible Materials Aluminum oxide, silicon nitride
Compatible Plastics HDPE, PP, Teflon, PFA, PVC
Country of Origin USA
Availability Stock item
Available Sizes Quart, Gallon, 5 Gallon, 55 Gallon
Packaging HDPE
Packing 4 gallons/case
Isotropy Isotropic
Incompatible Chemicals Strong bases
Additional Information

PROPERTIES OF TRANSENE ALUMINUM ETCHANT TYPE D

How do I increase the etch rate? 1. The rate will approximately double with every 10°C increase in temperature.
2. Increase the rate of stirring or agitation.
How do I reduce the etch rate? Adding 1 part deionized water to 2 parts etchant will reduce the etch rate approximately 50%.
Do I need to dilute the etchant? No, it is ready to use.
How do I reduce undercutting? Increase the rate of stirring or agitation.
Appearance Water-white to light yellow
pH Strongly acidic
Etch Rate at 25°C
40°C
40 Å/sec.
125Å/sec
Etch Capacity (rate declines at ~70%) 60 g/gallon
Shelf Life 1 year
Storage Conditions Ambient
Filtration 0.2 um
Recommended Operating Temperatures 20-80oC (30-40oC most common)
Rinse Deionized water; may be followed by alcohol rinse if desired.
Photoresist Recommendations KLT 6000 Series, TRANSIST, PKP II
Select Compatible Materials Silicon oxide, gold

See http://transene.com/etch-compatibility/ for more details.

Select Incompatible Materials Aluminum oxide, silicon nitride, GaAs
Compatible Plastics HDPE, PP, Teflon, PFA, PVC
Country of Origin USA
Availability Stock item
Available Sizes Quart, Gallon, 5 Gallon, 55 Gallon
Packaging HDPE
Packing 4 gallons/case
Isotropy Isotropic
Incompatible Chemicals Strong bases
Additional Information

APPLICATION:

Aluminum metallizations up to 25,000 Å are vacuum deposited on the silicon slice, coated with a photoresist, and UV exposed using an appropriate photographic mask. The resist is developed to protect the aluminum where interconnections are desired. Then the unprotected areas of the aluminum are removed by etching with Transene Aluminum Etchant, followed by a water rinse.

Etching time is dependent upon the etchant temperature and the aluminum film thickness. When etching thick aluminum films, a higher etch rate is required; thus a higher etchant temperature should be used. Likewise, for thinner aluminum films, slower etch rates are desired and a lower etchant temperature should be chosen.

Aluminum Etchant Type F

Etchant for Al and Al-Si Metallizations. Chemical etchant compatible with negative and positive photoresists for etching aluminum or aluminum/1% Si deposits. Glass or Pyrex beakers should not be used for storing Aluminum Etchant Type F.

DESCRIPTION:

Transene Aluminum Etchant Type F is a stable preparation used to etch aluminum or aluminum-silicon metallizations on silicon devices and in integrated circuit applications. Aluminum contacts are defined and interconnections are formed. Aluminum Etchant Type F is formulated with unique properties easily overcome many of the difficulties experienced in aluminum etch processes such as residue. The aluminum metallization and etching process using photo-lithographic techniques is basic to the semiconductor and microelectronic technology. Transene Aluminum Etchant Type F is highly compatible with commercial photoresists (KTFR, AZ, Hunt, Waycoat, etc.) and permit delineation into high resolution patterns. Metal line width of 1 mil and separations less than 5 microns are feasible. The high resolution is practical with Transene Aluminum Etchant Type F because lifting of photoresist patterns does not occur and undercutting is minimized.

PROPERTIES OF TRANSENE ALUMINUM ETCHANT TYPE F

How do I increase the etch rate? 1. The rate will approximately double with every 10°C increase in temperature.
2. Increase the rate of stirring or agitation.
How do I reduce the etch rate? Adding 1 part deionized water to 2 parts etchant will reduce the etch rate approximately 50%.
Do I need to dilute the etchant? No, it is ready to use.
How do I reduce undercutting? Increase the rate of stirring or agitation.
Appearance Clear, colorless-to-light yellow liquid
pH Strongly acidic
Etch Rate at 25°C
40°C
50°C
65°C
75°C
30 Å/sec.
80 Å/sec
100 Å/sec
240 Å/sec
550 Å/SEC
Etch Capacity (rate declines at ~70%) 80 g/gallon
Shelf Life 1 year
Storage Conditions Ambient
Filtration 0.2 um
Recommended Operating Temperatures 20-80oC (30-40oC most common)
Rinse Deionized water; may be followed by alcohol rinse if desired.
Photoresist Recommendations KLT6000 Series, KLT 5300 Series, HARE SQ (SU-8 type), TRANSIST, or PKP II
Select Compatible Materials Gold, titanium, silicon dioxide

See http://transene.com/etch-compatibility/ for more details.

Select Incompatible Materials Nickel, copper, alumina
Compatible Plastics HDPE, PP, Teflon, PFA, PVC
Country of Origin USA
Availability 1-2 Business Days
Available Sizes Quart, Gallon, 5 Gallon, 55 Gallon
Packaging HDPE
Packing 4 gallons/case
Isotropy Isotropic
Incompatible Chemicals Strong bases
Additional Information Etch rate may vary with aluminum purity.

APPLICATION:

Aluminum metallizations up to 25,000 A are vacuum deposited on the silicon slice, coated with a photoresist, and UV exposed using an appropriate photographic mask. The resist is developed to protect the aluminum where interconnections are desired. Then the unprotected areas of the aluminum are removed by etching with Transene Aluminum Etchant Type F, followed by a water rinse. Etching time is dependent upon the etchant temperature and the aluminum film thickness. When etching thick aluminum films, a higher etch rate is required; thus a higher etchant temperature should be used. Likewise, for thinner aluminum films, slower etch rates are desired and a lower etchant temperature should be chosen. At a specific etchant temperature, the etching time is given by the following formula:

Etching time (second) + Film Thickness (Å)
Etch Rate (Å/sec)