Back to results
US 8,796,157 B2Granted
Method for selective etching
AssigneeLam Research Corporation
InventorGerald Wagner
Life of this patent
Estimating the term…
Abstract
Method of selectively etching a first material on a substrate with a high selectivity towards a second material by flowing a liquid etchant across a substrate surface at a flow sufficiently fast to generate a minimum mean velocity parallel to the substrate's surface, wherein the first material is selected from a group including materials with semiconducting properties based on at least two different chemical elements.
Claims11
A method of selective etching comprising:
- providing a substrate comprising a surface layer formed by first material and an intermediate layer formed by a second layer, said intermediate layer immediately adjacent to said surface layer and between said substrate and said surface layer, said first material comprising at least two different chemical elements and having semiconducting properties based on said at least two different chemical elements, and said second material being strained silicon;
- and
- providing strained silicon as a second material selected;
- and
- selectively etching said first material with a selectivity of at least 15:1 towards said second material by a liquid etchant flowing across and directly contacting the substrate surface layer at a flow sufficiently fast to generate a mean velocity v parallel to the substrate's surface layer of at least 0.1 m/s,
- wherein said substrate is rotated while exposed to said liquid etchant,
- wherein said liquid is dispensed onto the surface layer of the substrate in a continuous flow as a free beam having a defined axis such that the liquid contacts the substrate's surface at a point of impact defined as an intersection of the axis of the free beam and the substrate's surface, and the liquid is spread over the substrate's surface layer from said point of impact,
- wherein said point of impact of the liquid stream is moved across the surface layer of the substrate in a time sequence so as to provide uniform etching,
- wherein said liquid is dispensed at a volume flow from 0.05 l/min to 0.5 l/min.
6 more elements
A method of selective etching comprising:
- providing on a substrate comprising a surface layer of a first material and a layer of a second material immediate adjacent to said surface layer,
- said first material having semiconducting properties and being based on at least two different elements:
- (i) one being at least one of metals, semimetals and Se, and (ii) one being at least one element selected from the group consisting of B, Si, Ge, As, Se, Sb, Te, Bi and Po,
- said second material being strained silicon;
- and
- selectively etching said first material with a selectivity of at least 15:1 towards said second material by contacting the substrate surface layer with a liquid etchant, said liquid etchant flowing across the substrate surface layer at a flow sufficiently fast to generate a mean velocity v parallel to the substrate's surface of minimum 0.1 m/s,
- wherein the liquid etchant comprises a (a) a source of fluorine selected from the group consisting of hydrofluoric acid (HF), ammonium fluoride (NH4F), ammonium hydrogen difluoride (NH4HF2), fluoroboric acid (H2BO2F), and fluorosulphonic acid (HSO3F), and (b) an oxidizing agent selected from the group consisting of nitric acid (HNO3), nitrous acid (HNO2), hydrogen peroxide (H2O2), ozone (O3), perchloric acid (HClO4) and percarboxylic acid,
- wherein said substrate is rotated while exposed to said liquid etchant,
- wherein said liquid is dispensed from a location onto the surface layer of the substrate in a continuous flow as a free beam having a defined axis such that the liquid contacts the substrate's surface at a point of impact defined as an intersection of the axis of the free beam and the substrate's surface, and the liquid is spread over the substrate's surface layer from said point of impact,
- wherein said point of impact of the liquid stream is moved across the surface layer of the substrate in a time sequence by moving the location from which the liquid stream is dispensed to provide uniform etching,
- wherein said liquid is dispensed at a volume flow from 0.05 l/min to 0.5 l/min.
8 more elements
Dependencies are inferred from the claim text.