Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of... – Insulative material deposited upon semiconductive substrate
Reexamination Certificate
2000-07-21
2001-07-10
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
Insulative material deposited upon semiconductive substrate
C438S758000, C438S800000, C427S255250, C427S255320
Reexamination Certificate
active
06258733
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to method and apparatus for depositing thin films for use in integrated circuits by forming a mist of a liquid, and depositing the mist or a vapor formed from the mist on an integrated circuit substrate, and more particularly to such a fabrication process which increases both the step coverage and deposition rate of such a process.
2. Statement of the Problem
U.S. Pat. No. 5,456,945 issued Oct. 10, 1995 describes a method of misted deposition that has proven to provide thin films of complex materials that are of the high quality necessary for integrated circuit electronic devices. The misted deposition process also achieves deposition rates that are significantly higher then the deposition rates in other methods of depositing complex materials, such as chemical vapor deposition. One reason why the method provides high quality films is that it is a low energy process, therefore the complex organic solvents and chemical compounds that are used in the process are not carbonized or otherwise destroyed in the process. However, over extreme topological features, the misted deposition process of forming the film does not provide step coverage as good as the best alternative integrated circuit fabrication process, chemical vapor deposition. Attempts have been made to improve the step coverage by using conventional methods of adding energy used in chemical vapor deposition processes, such as heating the substrate sufficiently to significantly increase the yield. These attempts have lead to films that are carbonized, fractured and of a generally low quality that is not suitable for the fabrication of integrated circuit electronic devices. The more complex the compounds one is attempting to form, the more serious the problems. Since integrated circuit materials are tending to become more complex, and liquid source deposition processes are turning out to be the most reliable for forming thin films of very high quality, it would be highly desirable to have a liquid source deposition process that retained the high quality and high deposition rates of the lower energy misted deposition process, but at the same time was capable of the excellent step coverage available in the CVD process.
Electric fields have also been used to assist in deposition of mists. However, mists used in making electrical components for integrated materials consist of metal-organic compounds, such as alkoxides and carboxylates carried by inert gases. The gases must be inert, since otherwise they can combine with the reactive metal-organic compounds and alter the deposition process. However, both the metal-organic compounds and the inert gases do not ionize well, and thus it is difficult or impossible to use the electric field for anything more than mild poling of the mists.
SUMMARY OF THE INVENTION
The invention solves the above problem by providing apparatus and methods of depositing misted liquid precursors in a controlled manner that greatly enhances both the step coverage and the deposition rate. The invention also provides apparatus and methods of adding energy to the mist particles in a misted deposition process in a controlled manner that does not break down the chemical bonds that lead to high quality films.
The mist is created in a venturi that also ionizes the particles. An electrical mist filter is utilized to obtain a mist of predominantly one polarity.
The invention utilizes a velocity reduction chamber and a “showerhead” type inlet plate located above and parallel to the substrate to provide a uniform flow of mist to the substrate. The showerhead is relatively large, preferably the area over which the ports in the showerhead are distributed being equal to or larger than the area of the substrate. Preferably, the mist enters the velocity reduction chamber in a direction substantially perpendicular to the direction the mist exits the velocity reduction chamber. The openings in the “showerhead” are as close together as possible, without affecting the mechanical stability of the showerhead, preferably 0.020 inches or less, edge-to-edge. Alternatively, they are uniformly distributed in a randomized manner.
The invention also utilizes a mist particle electrical accelerator to add energy to the particles. Oxygen is added to the mist to enhance the charging of the mist. The inlet plate acts as one electrode of the accelerator. The invention also utilizes an exhaust port that is in the form of a channel about the periphery of and below the plane of the substrate.
The invention also utilizes a mass flow controller for precisely controlling the flow of precursor liquid to the mist generator. This significantly enhances the repeatability of the deposition process.
The invention also provides apparatus and methods for deposition that result in a very fine and uniform mist; i.e. a mist in which the vast majority of the mist particles are less than a micron in diameter, and the mean particle diameter is less than half a micron.
The invention provides apparatus for fabricating an integrated circuit comprising: (a) a mist generator for forming a mist of a liquid precursor; (b) a deposition chamber; (c) a substrate holder located within the deposition chamber for supporting a substrate, the substrate holder defining a substrate plane; (d) the deposition chamber including: a mist inlet assembly in fluidic communication with the mist generator, the mist inlet assembly comprising a mist inlet plate, the mist inlet plate having a plurality of inlet ports defining an inlet plane substantially parallel to the substrate plane and distributed over an area of the inlet plate to provide a substantially uniform deposition of the mist on the substrate; (e) an exhaust port for withdrawing exhaust from the deposition chamber; and (f) the substrate plane located between the mist inlet plane and the exhaust port. Preferably, the plurality of inlet ports are distributed randomly over the area of the mist inlet plate. Preferably, the plurality of inlet ports are uniformly distributed in a randomized manner over the area of the mist inlet plate. Preferably, the area of the inlet plate over which the plurality of inlet ports are distributed is substantially equal to the area of the substrate. Preferably, the apparatus includes a velocity reduction chamber located between the mist generator and the mist inlet plate. Preferably, the mist inlet plate forms a partition between the velocity reduction chamber and the deposition chamber. Preferably, the velocity reduction chamber further comprises a velocity reduction chamber inlet port located so that mist enters the velocity reduction chamber in a direction substantially perpendicular to the direction the mist exits the velocity reduction chamber. Preferably, the inlet plate is located substantially directly above the substrate whereby gravity assists the deposition of the mist on the substrate. Preferably, the exhaust port substantially defines a channel about the periphery of an exhaust plane parallel to the substrate plane. Preferably, the deposition chamber further includes a mist particle electrical accelerator for electrically accelerating mist particles in a direction substantially perpendicular to the substrate plane, and the inlet plate comprises an electrode of the electrical accelerator. Preferably, the mist inlet plate is transparent to ultraviolet radiation. Preferably, the mist inlet plate includes a conductive coating. Preferably, the mist particle electrical accelerator comprises a first electrode substantially parallel to the substrate plane and having a plurality of mist inlet ports. Preferably, the first electrode is transparent to ultraviolet radiation. Preferably, the mist particle electrical accelerator further comprises a second electrode substantially parallel to the substrate plane and located on the opposite side of the substrate from the first electrode, and a voltage source for applying an electrical voltage to the second electrode. Preferably, the first electrode is located above the substrat
Grant Robert W.
McMillan Larry D.
Paz De Araujo Carlos A.
Solayappan Narayan
Ghyka Alexander G.
Niebling John F.
Patton & Boggs LLP
Sand hill Capital II, LP
LandOfFree
Method and apparatus for misted liquid source deposition of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for misted liquid source deposition of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for misted liquid source deposition of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2451174