Semiconductor device manufacturing: process – Making passive device – Trench capacitor
Reexamination Certificate
2000-02-25
2001-10-16
Bowers, Charles (Department: 2823)
Semiconductor device manufacturing: process
Making passive device
Trench capacitor
C438S386000, C438S387000, C438S391000
Reexamination Certificate
active
06303456
ABSTRACT:
BACKGROUND OF THE INVENTION
Modern desktop microprocessors draw as much as 30 amps of current. Therefore, filtering the power supply for modern desktop microprocessors becomes a problem.
There is a need for a bypass capacitor to absorb current surges. There is also a need for precision capacitors for analog applications. Analog applications require precision capacitors with minimal parasitic capacitance between either of the capacitor's nodes and yet other circuit nodes. High dielectric constants help minimize the size of the precision capacitors and thus tend to minimize parasitic elements. However, integrated capacitors having a high dielectric constant have been impractical due to integration difficulties. In addition, the variability of high dielectric constant materials has made these materials unattractive for analog work.
SUMMARY OF THE INVENTION
By the present invention, capacitors having a high dielectric constant are integrated in silicon substrates having integrated circuits. Furthermore, the capacitors can be tuned, that is, their effective dielectric constant and, thus, their capacitance can be selected precisely to have any value between a minimum and a maximum. Through such a selection, the variability associated with high dielectric constant materials can be tuned out.
The above advantages are obtained by forming a plurality of conductive strips in a substrate having a first dielectric constant to define finger capacitors, removing a portion of the substrate material between the conductive strips to define a space and then filling the space with a material having a second dielectric constant which is greater than the first dielectric constant. In this way, the capacitance of the finger capacitors can be selected to have any value from a minimum, in which very little of the original first dielectric constant material is removed and replaced by the second dielectric constant material, to a maximum, in which all of the first dielectric constant material between the finger capacitors is removed and replaced with the second dielectric constant material, which has a greater dielectric constant. The substrate material can be removed and the resulting spaces can be filled with a material having a second dielectric constant using conventional semiconductor fabrication techniques.
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Pricer Wilbur David
Stamper Anthony Kendall
Bowers Charles
Brewster William M.
Henkler Richard A.
International Business Machines - Corporation
Venable Baetjer Howard & Civiletti LLP
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