CN1101600C - Temp sensor (F element) with analog, binary and frequency outputs - Google Patents

Abstract

The present invention relates to a temperature sensor (F element) with the output of analog values, switching values and frequency. The element is made of an N type Si sheet of which one side is polished, and the electric resistivity of the Si sheet is form 40 to 200 omega cm. The flow paths comprises oxidation, photoetching, the predeposition of boron, the redistribution and the oxidation of boron, photoetching, the predeposition of phosphorus, the redistribution and the oxidation of phosphorus, pin hole carving, aluminium evaporation, inverse carving of aluminium, aluminium alloyage, back plating of nickel, scribing, sheet adhesion, wire jointing, encapsulation, etc. The element has the advantages of simple making technology, low cost, convenient application and strong interference rejection, and is suitable for long distance transmission.

Description

Temperature sensor F-elements with analog, switching and frequency outputs

The invention relates to a temperature sensitive element, which has temperature sensitive characteristics of analog quantity, switch quantity and frequency output.

Temperature is one of the very important physical parameters, which needs to be measured and controlled in many occasions. Now, there are many types of temperature sensors, such as: thermocouples, thermistors (NTCR and PTCR), infrared devices, etc. However, these sensors are all analog outputs, which need to be amplified and A/D converted in applications such as industrial control and intelligent systems. This increases the cost of the application and causes inconvenience. The invention designs and develops a novel element as a temperature sensor. It has the characteristics of analog quantity, switch quantity and frequency output. When this component is used as an analog output and switching device, the temperature coefficient is very high. This has unique advantages for the application of some special occasions, such as: as a fire alarm sensor, the locking can be omitted, and the reset only needs to press the power switch without a special circuit. In addition, due to the advantage of frequency output, amplification and A/D conversion can be omitted when digital signals are required. The Z element invented by Professor V.ZOTOV of the former Soviet Union also has similar performance, (see "Z element technical data compilation" P1-2 edited by Harbin Novick Sensor Technology Co., Ltd., a Sino-Russian joint venture in July 1997), but There is an essential difference between the F element and the Z element of the present invention. 1. The production methods are different, and Z components need to expand deep-level impurities such as gold. F elements do not require deep-level impurities. 2. The waveforms of the frequency output are different. The shape of the F component is regular and easy to shape, while the waveform of the Z component is complex and not conducive to application. Therefore, the F element and the Z element cannot be equated.

The purpose of the present invention is to provide a temperature-sensitive sensor F element with analog quantity, switch quantity and frequency output. Compared with other elements, the F element has the advantages of simple structure and preparation process, low cost, and analog quantity, switch quantity and frequency output. Frequency output, convenient application, strong anti-interference ability, suitable for long-distance transmission.

A kind of temperature sensor F element with analog quantity, switch quantity and frequency output of the present invention, this sensor F element is to make with the N-type silicon wafer of one-sided polishing, and silicon wafer resistivity is between 40-200Ωcm, and its process The process is: oxidation, photolithography, boron pre-deposition, boron redistribution and oxidation, photolithography phosphorus pre-deposition, redistribution and oxidation, engraving lead holes, aluminum evaporation, reverse etching aluminum, aluminum alloying, nickel plating on the back, Dicing, bonding, wire bonding, and packaging are all that is required. A PN junction is made on the polished surface of the N-type silicon wafer polished on one side, and the PN junction adopts boron diffusion. The N region on the same side of the P-type of the PN junction is used as an electrode and connected to the P region of the PN junction as the positive electrode of the two-terminal device, and the other side is used as the negative electrode. The volt-ampere curve has a threshold voltage and a maintenance voltage in a negative resistance state, and at the same time, the volt-ampere curve includes three intervals as the element current increases: a high resistance area of positive resistance, a negative resistance area, and a low resistance area of positive resistance. The two-terminal device whose output frequency is sensitive to temperature is a combined device in which a capacitor is connected in parallel with the negative resistance device, and its capacitance is a surface-mounted capacitor between 1 nanofarad and 1000 nanofarads.

The application method of the F element of the present invention: for the analog quantity and the switching element, the resistance of the F element before the upper threshold voltage _Vp of the volt-ampere characteristic varies with temperature, and the current of the sharp rise section of the current after the negative resistance It can be used for analog output measurement as the temperature changes. Since V _p decreases with the increase of temperature, the F element can be used as a temperature switch output element by setting the working voltage to realize the control and measurement of temperature. The temperature coefficient of the threshold voltage _Vp of the F element produced by this patent can reach tens of millivolts to hundreds of millivolts per degree according to the structural design. It is essentially derived from the PN junction voltage and the body resistance of the element. Due to the amplification of the component itself, the frequency output F component can output pulse signals on the current limiting resistor or F component under the appropriate working voltage and current limiting resistance, and its frequency has a high linearity to temperature changes. The temperature coefficient of the pulse output can reach tens of Hz to several thousand Hz per degree, and the working temperature is between -40°C and 80°C.

see attached image

Fig. 1 is the structural representation of the chip with negative resistance volt-ampere characteristic of the present invention;

Fig. 2 is negative resistance volt-ampere characteristic curve among the present invention;

Fig. 3 is the pulse waveform of embodiment 1 frequency output F element among the present invention;

Fig. 4 is the variation of the frequency of the frequency output F element with temperature in Embodiment 1 of the present invention.

The invention is a design and manufacture method of a temperature-sensitive F element with analog quantity, switch quantity and frequency output. As we all know, the forward voltage drop of PN junction is affected by temperature, which can be used for temperature measurement, but its sensitivity is low. The present invention can use a single PN junction through an appropriate structure to obtain a negative resistance device (F element with analog output and switch output) with a higher temperature coefficient, and its threshold voltage has a higher temperature coefficient. The threshold voltage and temperature coefficient of the F element of analog and switch output can be adjusted through the structural design of the element. The frequency output can be generated by connecting a capacitor in parallel to the F element of analog and switch output, and the device at both ends after the parallel capacitor is called the F element of frequency output. Because its output frequency is closely related to the threshold voltage, and the threshold voltage is sensitive to temperature, the pulse frequency of the F component of the frequency output is sensitive to temperature.

Example 1:

Using an N-type silicon wafer with a thickness of 430 microns and a resistivity of about 80 Ωcm, after oxidation, photolithography, boron pre-deposition, boron redistribution and oxidation, photolithography, phosphorus pre-deposition, phosphorus redistribution and oxidation, and wire engraving Hole, aluminum steaming 1, anti-etching aluminum, aluminum alloying, nickel plating on the back, and scribing to obtain a chip of a negative resistance device, and the chip size is 0.8×0.8 mm. The F components of analog and switching values are obtained by bonding the chip, wire bonding, plastic packaging and other processes. Its threshold voltage _Vp has a temperature coefficient of about 65 millivolts per degree. Bond 100 nanofarad surface mount capacitors in parallel with this chip, and obtain F components with frequency output through processes such as chip bonding, wire bonding, and plastic packaging. Its frequency temperature coefficient is about 135Hz per degree.

Example 2:

Using an N-type silicon wafer with a thickness of 430 microns and a resistivity of about 80 Ωcm, after oxidation, photolithography, boron pre-deposition, boron redistribution and oxidation, photolithography, phosphorus pre-deposition, phosphorus redistribution and oxidation, and wire engraving Holes, aluminum steaming, aluminum reverse engraving, aluminum alloying, nickel plating on the back, and scribing to obtain a chip of a negative resistance device with a chip size of 0.8×0.8 mm. The F components of analog and switching values are obtained by bonding the chip, wire bonding, plastic packaging and other processes. Its threshold voltage _Vp has a temperature coefficient of about 65 millivolts per degree. Bonding 1 nanofarad surface mount capacitors in parallel with this chip, through bonding chip, wire bonding, plastic packaging and other processes, to obtain frequency output F components. Its frequency temperature coefficient is about 5000Hz per degree.

Example 3:

Using an N-type silicon wafer with a thickness of 430 microns and a resistivity of about 80 Ωcm, after oxidation, photolithography, boron pre-deposition, boron redistribution and oxidation, photolithography, phosphorus pre-deposition, phosphorus redistribution and oxidation, and wire engraving Holes, aluminum steaming, aluminum reverse engraving, aluminum alloying, nickel plating on the back, and scribing to obtain a chip of a negative resistance device with a chip size of 0.8×0.8 mm. The F components of analog and switching values are obtained by bonding the chip, wire bonding, plastic packaging and other processes. Its threshold voltage _Vp has a temperature coefficient of about 65 millivolts per degree. Bond 1000 nanofarad surface mount capacitors in parallel with this chip, and obtain F components with frequency output through processes such as chip bonding, wire bonding, and plastic packaging. Its frequency temperature coefficient is about 30Hz per degree.

Example 4:

Using an N-type silicon wafer with a thickness of 430 microns and a resistivity of about 40 Ωcm, after oxidation, photolithography, boron pre-deposition, boron redistribution and oxidation, photolithography, phosphorus pre-deposition, phosphorus redistribution and oxidation, and wire engraving Holes, aluminum steaming, aluminum reverse engraving, aluminum alloying, nickel plating on the back, and scribing to obtain a chip of a negative resistance device with a chip size of 0.8×0.8 mm. The F components of analog and switching values are obtained by bonding the chip, wire bonding, plastic packaging and other processes. Its threshold voltage _Vp has a temperature coefficient of about 30 millivolts per degree. Bond 100 nanofarad surface mount capacitors in parallel with this chip, and obtain F components with frequency output through processes such as chip bonding, wire bonding, and plastic packaging. Its frequency temperature coefficient is about 40Hz per degree.

Example 5:

Using an N-type silicon wafer with a thickness of 430 microns and a resistivity of about 200 Ωcm, after oxidation, photolithography, boron pre-deposition, boron redistribution and oxidation, photolithography, phosphorus pre-deposition, phosphorus redistribution and oxidation, and wire engraving Holes, aluminum steaming, aluminum reverse engraving, aluminum alloying, nickel plating on the back, and scribing to obtain a chip of a negative resistance device with a chip size of 0.8×0.8 mm. The F components of analog and switching values are obtained by bonding the chip, wire bonding, plastic packaging and other processes. Its threshold voltage _Vp has a temperature coefficient of about 20 millivolts per degree. Bond 100 nanofarad surface mount capacitors in parallel with this chip, and obtain F components with frequency output through processes such as chip bonding, wire bonding, and plastic packaging. Its frequency temperature coefficient is about 150Hz per degree.

Claims (3)

1, a kind of temperature sensor F element with analog quantity, switching value and frequency output, it is characterized in that, this transducer F element is to make on the N type silicon wafer polishing face of single-sided polishing, makes a PN junction on the N of single-sided polishing type silicon wafer polishing face, and PN junction adopts boron diffusion; Be connected at electrode of the N district of the P of PN junction type homonymy work and with the P district of PN junction, as the positive pole of two terminal device, another side nickel plating is as negative pole; Silicon chip resistivity is between 40-200 Ω cm; Its technological process is: oxidation, photoetching, boron pre-deposited, and boron distributes and oxidation again, photoetching, phosphorus pre-deposited distributes and oxidation again, carves fairlead, and evaporation of aluminum anti-carves aluminium, aluminium alloying, back side nickel plating, scribing, bonding die, bonding wire, encapsulation get final product.

2, the temperature sensor F element with analog quantity, switching value and frequency output according to claim 1, it is characterized in that, volt-ampere curve has the voltage of keeping of a threshold voltage and negative resistance state, and the increase volt-ampere curve along with element current comprises three intervals simultaneously: the high resistance area that is just hindering, negative differential resistance region and the low-resistance region that is just hindering.

3, the temperature sensor F element with analog quantity, switching value and frequency output according to claim 1, it is characterized in that the thermally sensitive two terminal device of its output frequency is that its electric capacity is that 1 nanofarad is to the mounted on surface electric capacity between 1000 nanofarads with the electric capacity assembling device of negative resistance device parallel connection therewith.

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