EP0732733A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
HF vapour selective etching method and apparatus
Assignee: NEC Corp
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Filing: 1993-12-07
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Granted: —
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Expires: 2013-12-07
Abstract
Abstract In order to study an etching rate difference of a layer formed mainly with silicon dioxide on a wafer, a thermal oxide film (113) and layers of BSG (117), BPSG (125), and PSG (129) are laminated on a wafer and are etched in a gaseous etching atmosphere consisting essentially of hydrogen fluoride or a mixture of hydrogen fluoride and water vapour. The layers are etched with various etching rates which are higher than that of the thermal oxide film. The etching rate difference is a difference between the etching rate of each layer and an etching rate of the thermal oxide film. The layers may include impurities, such as boron and phosphorus, collectively as a part of a layer material of each layer. The etching rate difference depends on the layer material. Preferably, the gaseous etching atmosphere should have a reduced pressure. Alternatively, a water vapour partial pressure should not be greater than 2000 Pa. As a further alternative, either the layer or the gaseous etching atmosphere should be heated.
Inventors
- 👤 Hirohito C/O Nec Corporation Watanabe
- 👤 Mitsusuke C/O Asm Japan K.K. Kyogoku
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 15:01
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H10P72/00; H10P72/04; H10P72/0402; H10P72/0418; H10P72/0421; H10P72/0441; H10P72/30; H10P72/33; H10P72/34
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
97 words
A method of etching a silicon dioxide layer formed on a wafer in a gaseous etching atmoshphere consisting essentially of hydrogen fluoride or a mixture of hydrogen fluoride and water vapour, said silicon oxide layer being doped with an impurity into a doped oxide layer and left undoped as an undoped oxide layer, said silicon oxide layer being etched at a temperature higher than room temperature in order to increase an etching rate difference between said doped oxide layer and said undoped oxide layer and to selectively etch the doped oxide layer of a specific impurity concentration.
Claim 2
Dependent Claim
16 words
A method as claimed in claim 1, wherein said etching atmosphere is given a reduced pressure.
Claim 3
Independent Claim
96 words
A method of etching a silicon oxide layer formed on a wafer in a gaseous etching atmoshphere consisting essentially of hydrogen fluoride or mixture of hydrogen fluoride and water vapour, said silicon oxide layer being doped with an impurity into a doped oxide layer and left undoped as an undoped oxide layer, said gaseous etching atmosphere being heated to a temperature higher than room temperature in order to increase an etching rate difference between said doped oxide layer and said undoped oxide layer and to selectively etch the doped oxide layer of a specific impurity concentration.
Claim 4
Dependent Claim
16 words
A method as claimed in claim 3, wherein said etching atmoshpere is given a reduced pressure.
Claim 5
Dependent Claim
125 words
Apparatus for etching a silicon oxide layer formed on each of wafers in a gaseous etching atmosphere consisting essentially of hydrogen fluoride or a mixture of hydrogen fluoride and water vapour, said aparatus comprising: a reaction chamber in which an etching process takes place; a wafer boat for holding said wafers with a predetermined space left between two adjacent ones of said wafers; a transfer chamber which is located below said reaction chamber and in which said wafer boat is loaded with said wafers; a boat transfer machanism for transferring said wafer boat from said transfer chamber to said reaction chamber; and a sealing mechanism for isolating said reaction chamber from said transfer chamber; said wafer boat comprising heating means for individually heating said wafers.
Claim 6
Dependent Claim
60 words
Apparatus as claimed in claim 5, wherein said reaction chamber comprises an external tube and an inner tube placed in said external tube, said inner tube having openings through its peripheral wall to supply the etching gas from said reaction chamber into said inner tube through a space between said external tube and said inner tube and through said openings.
Claim 7
Dependent Claim
59 words
Apparatus as claimed in claim 5, wherein: said reaction chamber comprises an external tube and an inner tube placed in said external tube and provided with an aperture; said apparatus further comprising: means for introducing said gaseous etching atmosphere into said inner tube through said aperture and through a space left between said inner tube and said external tube.
Claim 8
Dependent Claim
14 words
Apparatus as claimed in claim 6, further comprising means for heating said reaction chamber.
Claim 9
Dependent Claim
37 words
Apparatus as claimed in claim 6, further comprising: gas supplying means for supplying said gaseous etching atmosphere into said reaction chamber; and a heater unit connected to said gas supplying means for heating said gaseous etching atmosphere.
Claim 10
Dependent Claim
34 words
Apparaturs as claimed in claim 6, further comprising: a gas inlet for introducing said gaseous etching atmosphere into said etching chamber; and heating means located inside of said reaction chamber for heating said wafers.
Claim 11
Dependent Claim
58 words
Apparatus as claimed in claim 6, further comprising: a gas mixing chamber which is connected to said reaction chamber, to which a plurality of individual etching gases are supplied, in which said individual etching gases are mixed into a gas mixture, and from which said gas mixture is supplied to the reaction chamber as said gaseous etching atmosphere.
Claim 12
Dependent Claim
40 words
Apparatus as claimed in claim 6, further comprising: gas adding means for adding to the gaseous etching atmosphere a gas which causes a liquid adsorption layer comprising hydrogen fluoride and water and formed on said undoped oxide layer to volatilize.
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