CN201522471U

CN201522471U - Capacitance type relative humidity sensor

Info

Publication number: CN201522471U
Application number: CN2009202337118U
Authority: CN
Inventors: 赵成龙; 黄庆安; 秦明
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2009-07-23
Filing date: 2009-07-23
Publication date: 2010-07-07
Anticipated expiration: 2019-07-23

Abstract

The utility model relates to a capacitance type relative humidity sensor which consists of a substrate, an oxidation layer, capacitance electrodes and a humidity sensitive medium, wherein the oxidation layer is arranged on the substrate, the capacitance electrodes are arranged on the oxidation layer, the capacitance electrodes are led out by a pressure welding block, the humidity sensitive medium is arranged between the capacitance electrodes and above the capacitance electrodes, thereby eroding the substrate and the oxidation layer thereabove, forming a cavity and leading the lower surface of the humidity sensitive medium between the capacitance electrodes to be also in the contact with air; the capacitance electrodes are interdigital electrodes and arranged in a staggered manner, and public ends of each group of the interdigital electrodes and free ends of the interdigital electrodes are fixed on the oxidation layer, thereby ensuring the mechanical strength of the electrodes. The capacitance type relative humidity sensor adopts polyimide as the humidity sensitive medium for eroding the substrate and the oxidation layer thereabove, thereby forming the cavity; and the air is distributed above and below the humidity sensitive medium between the capacitance electrodes, and the sensor has the advantages of fast response speed, high sensitivity, small substrate parasitics and the like.

Description

Relative Humidity Sensor

Technical field

The utility model relates to a kind of relative humidity sensor based on standard CMOS process, especially a kind of CMOS relative humidity sensor of quick response.

Background technology

Moisture measurement has a wide range of applications in fields such as national defence aviation, weather forecast, industrial manufacturing, agricultural production, health care, food processings.Humidity sensor has developed a lot of years as the important component part in the humidity measurement system.Develop at present the miniature humidity sensor that can make with standard CMOS process by traditional humidity sensors such as initial psychrometer, hair hygrometers.The humidity sensor that processes with standard CMOS process has that volume is little, and price is low, and advantages such as good product consistency are the focuses of humidity sensor research in recent years.In addition, utilize standard CMOS process easily that humidity sensor and testing circuit monolithic is integrated, can improve the stability and the antijamming capability of Humidity Detection system like this.Calendar year 2001, Y.Y.Qiu (name) has proposed to utilize the humidity sensor of CMOS technology making, this humidity sensor adopts polyimide as the humidity sensitive medium, testing circuit and humidity sensitive electric capacity monolithic is integrated, the humidity sensitive changes in capacitance is converted into change in voltage output, be convenient to the rear end detection system and carry out signal sampling and processing, but the humidity sensor response speed of this structure is slower.2004, Chinese Gu Lei has proposed the humidity sensor that a kind of CMOS of utilization technology is made, the sensing unit of this humidity sensor is the interdigital capacitor structure, palisade polysilicon heating resistor is placed the below of interdigital electrode, adopt polyimide as the humidity sensitive medium, highly sensitive, the linearity is good, but the hysteresis characteristic of sensor is not fine, and response is slower, heater circuit work can improve the temperature of humidity sensitive unit, and then accelerates the response speed of sensor, but the power consumption of sensor is increased.

Summary of the invention

Technical scheme: the utility model is a kind of Relative Humidity Sensor, by substrate, oxide layer, capacitance electrode, the humidity sensitive medium is formed, oxide layer is located on the substrate, capacitance electrode is located on the oxide layer, and capacitance electrode is drawn by press welding block, and the humidity sensitive medium is located between the capacitance electrode and the capacitance electrode top, the oxide layer of corrosion substrate and top thereof, form cavity, make the lower surface of the humidity sensitive medium between the capacitance electrode also contact with air, capacitance electrode is interdigited electrode and is staggered, the common port of every group of interdigited electrode and the free end of interdigited electrode all are fixed on the oxide layer, to guarantee the physical strength of capacitance electrode.

Relative Humidity Sensor of the present utility model comprises substrate, oxide layer, first capacitance electrode, second capacitance electrode and humidity sensitive medium, oxide layer is located on the substrate, first capacitance electrode, second capacitance electrode is located on the oxide layer, first capacitance electrode and second capacitance electrode are drawn respectively by first press welding block and second press welding block, the humidity sensitive medium is located between first capacitance electrode and second capacitance electrode and first capacitance electrode and second capacitance electrode top, the oxide layer of corrosion substrate and top thereof, form cavity, the lower surface of the humidity sensitive medium between the capacitance electrode and second capacitance electrode of winning is also contacted with air.

First capacitance electrode, second capacitance electrode are interdigited electrode and are staggered, first common port of every group of interdigited electrode and first free end of second common port and interdigited electrode and second free end all are fixed on the oxide layer, to guarantee the physical strength of first capacitance electrode, second capacitance electrode.

The humidity sensitive medium is a polyimide.

First capacitance electrode, second capacitance electrode are the aluminium electrode.

Beneficial effect: the utility model processing step is simple, utilizes standard CMOS process to combine with the MEMS process technology and makes, and cost is low, the precision height, and long-time stability are good.The humidity sensor that the present invention proposes adopts polyimide as the humidity sensitive medium, highly sensitive, the oxide layer corrosion of substrate and top thereof is formed cavity, the above and below of the humidity sensitive medium between the capacitance electrode is air like this, make the response speed of sensor accelerate, the substrate ghost effect reduces.

Description of drawings

Fig. 1 is a vertical view of the present utility model, have among the figure: oxide layer 2, the first capacitance electrodes 3, the second capacitance electrodes 4, first common port 31 of interdigited electrode, second common port 41 of interdigited electrode, first free end 32 of interdigited electrode, second free end 42 of interdigited electrode, first press welding block 33, second press welding block 43, humidity sensitive medium 5, cavity 6.

Fig. 2 is a sectional view of the present utility model, has among the figure: substrate 1, oxide layer 2, the first capacitance electrodes 3, the second capacitance electrodes 4, humidity sensitive medium 5, cavity 6.

Embodiment

The utility model is a kind of Relative Humidity Sensor, by substrate 1, oxide layer 2, first capacitance electrode 3, second capacitance electrode 4, humidity sensitive medium 5 is formed, oxide layer 2 is located on the substrate 1, first capacitance electrode 3 and second capacitance electrode 4 are located on the oxide layer 2, first capacitance electrode 3 and second capacitance electrode 4 are drawn respectively by first press welding block 33 and second press welding block 43, humidity sensitive medium 5 is located between first capacitance electrode 3 and second capacitance electrode 4 and first capacitance electrode 3 and second capacitance electrode, 4 tops, the oxide layer 2 of corrosion substrate 1 and top thereof, form cavity 6, the lower surface of the humidity sensitive medium 5 between the capacitance electrode 3 and second capacitance electrode 4 of winning is also contacted with air, first capacitance electrode 3 and second capacitance electrode 4 are interdigited electrode and are staggered, first common port 31 of every group of interdigited electrode and first free end 32 of second common port 41 and interdigited electrode and second free end 42 all are fixed on the oxide layer 2, to guarantee the physical strength of first capacitance electrode 3 and second capacitance electrode 4.

Substrate 1 is a body silicon in the present embodiment, oxide layer 2 is a silicon dioxide, first capacitance electrode 3 and second capacitance electrode 4 are the aluminium electrode, humidity sensitive medium 5 is a polyimide, the present invention can make of following technology: growth layer of oxide layer 2 on silicon substrate 1, sputtered aluminum and etching form first capacitance electrode 3 and second capacitance electrode 4 and first press welding block 33 and second press welding block 43, utilize spin-coating method spin coating one deck polyimide, the photoetching polyimide, imidization, then in silicon substrate 1 back side deposit one deck silicon nitride barrier and etch the corrosion window of silicon substrate 1, utilize the body silicon anisotropic etching to corrode then from silicon substrate 1 back side to oxide layer 2 directions, the etchant solution of selecting for use to the corrosion rate of oxide layer 2 much smaller than the corrosion rate of this etchant solution to substrate 1, when being corroded to oxide layer 2, substrate 1 thinks that the corrosion of substrate 1 finishes, at this moment in substrate 1, obtain a cavity, the oxide layer 2 of this cavity top eroded just obtain cavity 6, the lower surface of the humidity sensitive medium 5 between this moment first capacitance electrode 3 and second capacitance electrode 4 also contact with air, the silicon nitride barrier at substrate 1 back side is eroded at last again.

The electric capacity that first capacitance electrode 3 and second capacitance electrode 4 constitute with polyimide as the humidity sensitive medium, when ambient humidity changes, the specific inductive capacity of polyimide humidity sensing layer can change, thereby make the humidity sensitive capacitance change, utilize capacitive detection circuit the humidity sensitive changes in capacitance to be detected the information that just can obtain ambient humidity again.

Claims

1. Relative Humidity Sensor, it is characterized in that this sensor comprises substrate (1), oxide layer (2), first capacitance electrode (3), second capacitance electrode (4) and humidity sensitive medium (5), oxide layer (2) is located on the substrate (1), first capacitance electrode (3), second capacitance electrode (4) is located on the oxide layer (2), first capacitance electrode (3) and second capacitance electrode (4) are drawn respectively by first press welding block (33) and second press welding block (43), humidity sensitive medium (5) is located between first capacitance electrode (3) and second capacitance electrode (4) and first capacitance electrode (3) and second capacitance electrode (4) top, the oxide layer (2) of corrosion substrate (1) and top thereof, form cavity (6), the lower surface of the humidity sensitive medium (5) between capacitance electrode of winning (3) and second capacitance electrode (4) is also contacted with air.

2. Relative Humidity Sensor according to claim 1, it is characterized in that first capacitance electrode (3), second capacitance electrode (4) are interdigited electrode and are staggered, first common port (31) of every group of interdigited electrode and first free end (32) of second common port (41) and interdigited electrode and second free end (42) all are fixed on the oxide layer (2), to guarantee the physical strength of first capacitance electrode (3), second capacitance electrode (4).

3. Relative Humidity Sensor according to claim 1 and 2 is characterized in that humidity sensitive medium (5) is a polyimide.

4. Relative Humidity Sensor according to claim 1 and 2 is characterized in that first capacitance electrode (3), second capacitance electrode (4) are the aluminium electrode.