News Column

Patent Issued for Vibration Noise Shield in a Semiconductor Sensor

July 16, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- Moxtek, Inc. (Orem, UT) has been issued patent number 8766396, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventors are Decker, Keith (Pleasant Grove, UT); Hullinger, Derek (Orem, UT).

This patent was filed on November 2, 2012 and was published online on July 1, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "Shown in FIGS. 10-11 is a semiconductor device 100. The semiconductor device 100 can be a PIN diode. The semiconductor device 100 comprises a substrate 12, a cathode 23, an outer ring 22, an anode 14, and a guard ring 13.

"The substrate has a first face 12f and a second face 12s, with the second face 12s being substantially parallel to the first face 12f.

"The cathode 23 can be disposed at the second face 12s of the substrate 12. The outer ring 22 can be disposed at an outer perimeter of the first face 12f of the substrate 12. The anode 14 can be disposed at the first face 12f of the substrate 12 within an inner perimeter 22i of the outer ring 22. The guard ring 13 can be disposed at the first face 12f of the substrate 12 between the outer ring 22 and the anode 14. The guard ring 13 can be separated from the anode 14 by substrate 12b and from the outer ring 22 by substrate 12a. A purpose of the outer ring 22 is to prevent a depletion region which may be formed in the substrate from extending to an edge of the semiconductor device 100. The guard ring 13 can capture leakage current originating from an outer periphery of the semiconductor device 100.

"The cathode 23, the outer ring 22, the anode 14, and the guard ring 13 can be embedded in the substrate 12 such as by implantation. The substrate 12, the cathode 23, and the outer ring 22 can comprise a semiconducting material having a first conduction type, such as n for example. The cathode 23 and the outer ring 22 can be more highly doped than the substrate 12 (n+ for example). The anode 14 and the guard ring 13 can be more highly doped than the substrate 12, and can be a second conduction type (p+ for example). The first conduction type can be opposite of the second conduction type. One conduction type may be a material that tends to have an excess of electrons, and the other conduction type may be a material that tends to have an excess of holes.

"Following is an example of one use of the semiconductor device 100 for x-ray fluorescence analysis of elements in a sample, such as to determine element concentration. The anode 14 can have a voltage that is zero or close to zero. The cathode 23 can be connected to a positive voltage of around 120 volts. Due to temporary flow of electrical current through the substrate 12, the outer ring 22 can have a voltage similar to that of the cathode 23 (about 120 volts in this example).

"The sample can absorb x-rays from an x-ray source. The sample can then emit elemental-specific x-rays which can impinge on the semiconductor device 100. The elemental-specific x-rays can be absorbed by the substrate 12, resulting in formation of free electrons and holes. Due to the large positive voltage on the cathode 23, and the less positive voltage (or even negative voltage) on the anode 14, the free electrons can flow to the anode 14.

"The anode 14 can be connected by a wire bond 15 to an outer circuit 16. The wire bond 15 can extend over the outer ring 22 without touching the outer ring 22. Free electrons can flow from through the wire bond 15 between the anode 14 and the outer circuit 16. The free electrons are a signal that can be analyzed by the outer circuit 16 to determine elemental-specific x-ray energy, and from this elemental-specific x-ray energy, the element that emitted the x-ray.

"There is a capacitance C between the wire bond 15, with a voltage typically around zero volts, and the outer ring 22, with a voltage of 120 volts in this example. A problem with operation of the semiconductor device 100 is that the wire bond 15 is typically made of very fine gage wire, which can easily vibrate 111. This wire vibration 111 can cause the capacitance C, between the wire bond 15 and the outer ring 22, to change or oscillate. A distance d between two conductors is one factor that determines capacitance. Thus a change in distance d between the outer ring 22 and the wire bond 15, due to movement or vibration of the wire bond 15, can cause a change in capacitance between the outer ring 22 and the wire bond 15.

"Changing capacitance C can induce noise into the wire bond 15 as indicated by the equation Q=CV, in which Q is charge and V is voltage differential between the two conductors (120 volts in this example). Because the voltage differential V is high, changes in capacitance can result in substantial changes in charge Q. The changes in charge Q will be analyzed by the outer circuit 16. The outer circuit 16 cannot distinguish between electrons resulting from x-rays absorbed by the substrate 12 and electrons resulting from the changing capacitance. Thus, the changing capacitance C can introduce undesirable electronic noise into the signal, adversely affecting analysis of the signal, such as by causing poor resolution. This poor resolution can make it difficult to distinguish different elements in the sample. It would be beneficial to eliminate or reduce this electronic noise induced into the signal due to the changing capacitance C between the wire bond 15 and the outer ring 22."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "It has been recognized that it would be advantageous to eliminate or reduce electronic noise induced into a signal, from an anode to an outer circuit through a wire bond, due to changing capacitance between the wire bond and an outer ring. The present invention is directed to a semiconductor device that satisfies this need. The semiconductor device comprises a substrate, a cathode, an outer ring, an anode, an electrically insulating layer, and an electrically conducting layer. The substrate includes a semiconducting material having a first conduction type. The substrate has a first face and a second face substantially parallel to the first face. A cathode can be disposed at the second face of the substrate and can have the first conduction type. An outer ring, having the first conduction type, can be disposed at an outer perimeter of the first face of the substrate. An anode, having the second conduction type, can be disposed at the first face of the substrate within an inner perimeter of the outer ring. An electrically insulating layer can be disposed over the outer ring. An electrically conducting layer can be disposed over the electrically insulating layer and over the outer ring. The electrically conducting layer can be electrically insulated from the outer ring by the electrically insulating layer."

For the URL and additional information on this patent, see: Decker, Keith; Hullinger, Derek. Vibration Noise Shield in a Semiconductor Sensor. U.S. Patent Number 8766396, filed November 2, 2012, and published online on July 1, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8766396.PN.&OS=PN/8766396RS=PN/8766396

Keywords for this news article include: Electronics, Moxtek Inc., Semiconductor.

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Source: Electronics Newsweekly


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