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667498

Sigma-Aldrich

Tungsten etchant

Synonym(s):

Tungsten etch

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About This Item

MDL number:
MFCD08705365
UNSPSC Code:
12352300
NACRES:
NA.23
Pricing and availability is not currently available.

General description

Tungsten etchant is a mixture of potassium hydroxide and potassium ferricyanide based solution that facilitates the removal of tungsten and other materials like aluminium by dipping the substrate into the etching solution.[1][2][3]

Application

Selective etchants for tungsten thin-film metallizations used in semiconductor and microelectronics technology. Etchants are buffered, mildly alkaline ferricyanide-based formulations providing high resolution patterns with minimal undercutting and photoresist compatibility. Etchant is ready to use (no dilution required). Controlled, uniform etching is achieved by immersion or spray etch technique. Etch Capacity (rate declines at ∼70%) of 64 g/gallon. Recommended Operating Temperatures: 20-80 °C (30-40 °C most common).

Preparation Note

1. Select your etching method according to the table below
Etch Rate (Immersion) Etch Rate (Spray)
  • 20°C = 30 Å/second
  • 30°C = 140 Å/second 20°C = 80 Å/second
  • 60°C = 250 Å/second

2. Rinse with DI water

Pictograms

Corrosion
GHS05

Signal Word

Danger

Hazard Statements

H290,H314,H412

Hazard Classifications

Aquatic Chronic 3 - Eye Dam. 1 - Met. Corr. 1 - Skin Corr. 1A

Supplementary Hazards

EUH032

Storage Class Code

8B - Non-combustible corrosive hazardous materials

WGK

WGK 2

Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

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Certificates of Analysis (COA)

Lot/Batch Number
MKCV5289
MKCW0376
MKCS8109
MKCR3849
MKCQ1447

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Pattern processing results and characteristics for SCALPEL masks.
Novembre AE, et al.
Microelectronic Engineering, 46(1-4), 271-274 (1999)
Microstructure Evolution of W-Cu Alloy Wire.
Shao F, et al.
Materials Sciences and Applications, 3(03), 157-157 (2012)
Electrostatically actuated copper-blade microrelays.
Lee H, et al.
Sensors and actuators A, Physical, 100(1), 105-113 (2002)

Questions

1–8 of 8 Questions  

  1. Is this etchant etch photoresist? Can I use photoresist as a mask?

    1 answer

    1. This etchant is compatible with negative photoresist and can be used with photoresist as a mask.

      Helpful?

  2. Is it compatible with gold and copper?

    1 answer

    1. The product will etch Aluminum, Carbon, Chromium, Iron, Gallium Arsenide, and Zinc oxide. The material is also compatible with Alumina (Al2O3), Gold, Cobalt, Copper, Magnesium, Magnesium oxide, Niobium, Nickel, Palladium, Platinum, Ruthenium, Silicon nitride (Si3N4), Steel, Tantalum, and Titanium.

      Helpful?

  3. Is it compatible with oxides and nitrides?

    1 answer

    1. This Tungsten etchant has the following information on compatibility for the listed Oxides and Nitrides:
      Al2O3: more than 20:1 selectivity or no etching
      MgO: more than 20:1 selectivity or no etching
      Si3N4: more than 20:1 selectivity or no etching
      SiO2: Slight etch, selectivity less than 20:1
      TaN: more than 20:1 selectivity or no etching
      ZnO: etch, significant attack

      Selectivity is the ratio of etch rates between different layers of materials, typically a mask (used for patterning), and the etch rate of the material of interest.
      Selectivity = Etch Rate A / Etch Rate B
      In general, selectivity of >5:1 is considered high selectivity, and equal rate etching when selectivity is 1:1 is considered low selectivity.

      Helpful?

  4. What is the proper neutralization and disposal process?

    1 answer

    1. Please refer to section 13 of the Safety Data Sheet for disposal information. Consult with facility or municipal EHS authorities to assure proper guidelines are followed. The SDS may be accessed by using the link provided in the upper left tool bar of the product detail page.

      Helpful?

  5. Do I need to dilute the etchant?

    1 answer

    1. No, it is ready to use.

      Helpful?

  6. How do I reduce the etch rate?

    1 answer

    1. Adding 1-part deionized water to 2 parts etchant will reduce the etch rate approximately 50%.

      Helpful?

  7. How do I increase the etch rate?

    1 answer

    1. 1.The rate will approximately double with every 10°C increase in temperature. 2. Increase the rate of stirring or agitation.

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  8. How do I reduce undercutting?

    1 answer

    1. Increase the rate of stirring or agitation.

      Helpful?

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