WO2014088794A1

WO2014088794A1 - Diborane storage

Info

Publication number: WO2014088794A1
Application number: PCT/US2013/070667
Authority: WO
Inventors: Jack M. FAUGHT
Original assignee: Linde Aktiengesellschaft
Priority date: 2012-12-05
Filing date: 2013-11-19
Publication date: 2014-06-12

Abstract

To avoid the decomposition of diborane during storage, the diborane is absorbed by absorption media in a vessel. The vessel is then pressurized with hydrogen. Pure diborane may be stored for extended periods of time in this manner.

Description

DIBORANE STORAGE

(001) The invention relates to methods and apparatus for the storage of diborane gas.

BACKG ROUND OF THh IN VENTIO

(002) Diborane (B₂H₆) is ilammable gas which is useful as a F-type dopant material for semiconductor and solar cell devices. For these applications, diborane is delivered to a vacuum chamber and implanted into the silicon layer using pulsed laser ablation or son implant processes. In addition, diborane is used in boron-phosphate-silicate glass formation and can be complexed with a wide variety of lewis bases, e.g. borane- tetrhydromran, borane dimethyl sulfide, etc., and a variety of amine boranes that are useful as reducing agents in the synthesis of pharmaceuticals, organic chemicals and electroless plating baths.

(003) While the most desirable form of diborane for the above applications is pure diborane gas, unfortunately, diborane is relatively unstable and over time decomposes to higher boranes in both gas and solid forms and hydrogen, As diborane decomposes, it gives off hydrogen with the remaining material reacting to form B₄H₁₀ or higher B_xH_y compounds.

(004) The decomposition of diborane can cause serious problems for the processes using the diborane, including deleterious variations to the process and equipment malfunctions. Several proposals have been made to alleviate or reduce decomposition of diborane, For example, diborane may be shipped as a mixture with an inert gas or at low temperature, e.g. about -75°. Alternatively, point-of-use diborane generation has been proposed. A number of different generation methods have been described, but all of them encounter problems associated with synthesis or purification making point-of-use generation unfeasible.

(005) There remains a need in the art for improvements to the storage of diborane.

(006) The invention provides methods and apparatus for storing diborane.

{007} According to the invention, a vessel containing an absorption media, such as a carbon based or zeolite based absorption media, is used to store diborane. The diborane is absorbed b the absorption media and the vessel is then pressurized with hydrogen. It has been found that by mixing hydrogen with the diborane, the diborane remains stable for extended periods of time of at least two years. The absorption media provides a useful means for storage of the diborane and allows .for a relatively easy process for delivering the diborane to equipment when needed.

(ΘΘ8) In particular, the diborane is absorbed by the absorption media and the vessel is pressurized with hydrogen. When equipment requires the diborane, the hydrogen is vented from the vessel and a vacuum is applied to the absorption media. Any remaining hydrogen continues to vent. When the pressure reaches the point where diborane begins to release from the absorption media, the vent is closed and delivery of diborane to the equipment begins, Upon completing the delivery of the required amount of diborane, the delivery system (the vessel and associated piping, etc) is isolated from the equipment and the absorption media is repressurized with hydrogen so that the remaining diborane remains in storage without decomposition. (009) The system of the invention allows for the use of pure diborane without the risk of decomposition. Storage at cold temperatures is not necessary. Further, the problems associated with point-of-tise diborane generation are avoided.

(010) It is anticipated thai other embodiments and variations of the present invention will become readily apparent to the skilled artisan in the light of the foregoing description, and it is intended that such embodiments and variations likewise be included within the scope of the invention as set out rrs the appended claims.

Claims

CLAIMS What is claimed:

1 . A method of storing diborane comprising:

providing a storage vessel containing absorption media;

delivering d borane to the storage vessel and absorbing the diborane into the absorption media; and

pressurizing the storage vessel with hydrogen.

2. The method of claim 1 wherein the absorption media is zeolite.

3. A method of delivering diborane to a process comprising:

providing a source of diborane wherein the diborane is absorbed into absorption media contained in a vessel that has been pressurized with hydrogen;

opening a vent of the storage vessel and venting hydrogen from the storage vessel until the pressure within the storage vessel reaches a level at which diborane is released from the absorption media;

closing the vent; and

delivering the released diborane from the storage vessel to the process,

4. The method of claim 3 wherein the absorption media is zeolite.

5. The method of claim 3 further comprising following completion of delivery of diborane to the process:

isolating the storage vessel from the process; and

repressurizing the storage vessel with hydrogen,