Available Technology

ARTICLE AND PROCESS FOR SELECTIVE DEPOSITION

Currently, a density gradient in silicon can be made by deep reactive ion etching or dicing a silicon wafer with a dicing saw. However, these methods provide a relatively course gradient and are not suited for creating a density gradient in a curved surface.  Additionally, chemical vapor deposition process operates under harsh chemical environments, including high temperatures, high energy plasmas and dangerous gasses.  These harsh conditions limit what type of substrates can be used and increase cost. Therefore, a new method for providing density gradients in materials has been developed utilizing a deposition of metal as follows:

  • disposing an activating catalyst on a substrate;
  • contacting the activating catalyst with a metal cation from a vapor deposition composition;
  • contacting the substrate with a reducing anion from the vapor deposition composition;
  • performing an oxidation-reduction reaction between the metal cation and the reducing anion in a presence of the activating catalyst; and
  • forming a metal from the metal cation to deposit the metal on the substrate.

The advantages to using this process are:

  • deposition occurs under low temperature, benign chemical environments
  • chemical precursors are cheap and readily available
  • reaction chamber is cheaper than traditional chemical vapor deposition chambers
  • site selective deposition
  • can fill ultra-small openings
  • do not have to worry about wetting properties of substrate
  • void free filling for micro-via applications
  • easily fabricate 3D metallic nanostructures
  • wide range of metal precursors
  • deposit alloys
  • carbon free metals

Figure 29 illustrates the results of this process by forming etch void and metal in etch void. Additional illustration are located in the patent:

A complex shape is fabricated in a substrate using a catalyst with a complex shape. With reference to FIGS. 29A, 29B, 29C, and 29D, a “star” shaped catalyst is fabricated using electron beam lithography and electron beam deposition. The catalyst is composed of two layers, a first layer of Ti and a second layer of Au. The substrate and catalyst are immersed in a ρ=90[13.8] etchant solution at room temperature for a few minutes. The resulting etch void is shaped like a spiraling star. The catalyst is left in a bottom of the etch void and is a whitish region in a center of the void. The spiraling structure rotates counter-clockwise as shown by “shadows” in the scanning electron microscope image. Varying the shape of the catalyst, composition of the etchant, and phase of the etchant affects the shape of the etch void.

 

Abstract: 

A process for depositing a metal includes disposing an activating catalyst on a substrate; contacting the activating catalyst with a metal cation from a vapor deposition composition; contacting the substrate with a reducing anion from the vapor deposition composition; performing an oxidation-reduction reaction between the metal cation and the reducing anion in a presence of the activating catalyst; and forming a metal from the metal cation to deposit the metal on the substrate. A system for deposting a metal includes an activating catalyst to deposit on a substrate; and a primary reagent to form: a metal cation to deposit on the substrate as a metal; and a reducing anion to provide electrons to the activating catalyst, the metal cation, the substrate, or a combination thereof, wherein the primary reagent forms the metal cation and the reducing anion in response to being subjected to a dissociating condition.

Inventors: 
Hildreth Owen
Patent Number: 
9,809,882
Technology Type(s): 
Analytical Chemistry, Biochemical Science, Chemical Sciences, Surface and Microanalysis Science
Internal Laboratory Ref #: 
14-008
Patent Issue Date: 
November 7, 2017
Lab Representatives
Share to Facebook Share to Twitter Share to Google Plus Share to Linkedin