A kind of capacitive humidity sensor with temperature drift compensation and preparation method thereof
Technical field
The present invention relates to the humidity sensor technical field, particularly a kind of capacitive humidity sensor with temperature drift compensation and preparation method thereof that adopt surface micromachined to realize.
Background technology
Humidity sensor is widely used, and traditional humidity sensor is taking hygristor etc. as main, although this class sensor cost is low, precision is poor.Capacitance type humidity sensor is another kind of common humidity sensor structure, and such transducer sensitivity is high, is the principal mode of current humidity sensor.Capacitor type humidity sensor structure adopts macromolecular material as humidity-sensitive medium conventionally, also changes because the thermal expansivity of wet sensory material causes more greatly humidity sensing characteristic, therefore needs to do temperature compensation.Form humidity sensitive head as the humidity sensor of Switzerland Sensirion adopts two consistent interdigitated configuration, one of them is to humidity sensitive, and one insensitive.Owing to thering is same temperature characterisitic, when measurement, by electric capacity difference, compensate the impact of temperature on humidity sensitive.But the defect of this structure is: the one, account for chip area large, and the 2nd, need complicated circuit to realize electric capacity difference compensation problem.Therefore how designing sensor can test simply again in satisfied temperature compensation, is still the emphasis of current industry research.
Summary of the invention
The object of this invention is to provide a kind of capacitive humidity sensor with temperature drift compensation, it is simple in structure, and in can normally perception humidity changing, the temperature can compensative material temperature effect causing is floated problem.In addition the present invention also provides the method for making of this capacitive humidity sensor with temperature drift compensation.
For achieving the above object, the technical scheme that the present invention takes is: a kind of capacitive humidity sensor with temperature drift compensation, and it comprises semiconductor substrate layer, insulation course, the wet cantilever of sense and induction electrode; Wherein:
Insulation course is covered in the upper surface of semiconductor substrate layer;
One end of the wet cantilever of sense is fixed on insulation course, and the other end is positioned at the top of insulation course unsettled; The wet cantilever of sense by from top to bottom successively stacked the first humidity-sensitive material layer, moisture barrier and the second humidity-sensitive material layer form, wherein the first humidity-sensitive material layer is identical with the thickness of the second humidity-sensitive material layer;
Induction electrode comprises top electrode and bottom electrode; Top electrode covers the lower surface of the first humidity-sensitive material layer in the wet cantilever of sense, and fixing; Bottom electrode is fixed on insulation course; And the unsettled one end of top electrode is parallel to bottom electrode, and be positioned at the top of bottom electrode.
For the stress that more obviously delivery context humidity causes, increase the sensitivity of humidity sensor, in the wet cantilever of sense, the thickness of the first humidity-sensitive material layer, the second humidity-sensitive material layer is greater than the thickness of moisture barrier, top electrode.
The method of the above-mentioned capacitive humidity sensor with temperature drift compensation of manufacture provided by the invention, comprises the following steps:
(1) choose the material of silicon chip as semiconductor substrate layer;
(2) semiconductor substrate layer is oxidized, makes to form insulation course in the upper surface oxidation of semiconductor substrate layer;
(3) sputter layer of metal film on insulation course, and chemical wet etching forms bottom electrode;
(4) spin coating photoresist on insulation course, and photoetching forms sacrifice layer; Sacrifice layer covers an end of bottom electrode;
(5) at sacrifice layer upper surface sputter layer of metal film, and metallic film is carried out to photoetching form top electrode, and one end of top electrode is parallel to bottom electrode, and be positioned at the top of bottom electrode;
(6) at upper surface spin coating one deck humidity-sensitive material of top electrode, as the first humidity-sensitive material layer; And form every wet film, as moisture barrier by plasma reinforced chemical meteorology deposition method at the upper surface of the first humidity-sensitive material layer; Again at upper surface spin coating one deck humidity-sensitive material of moisture barrier, as the second humidity-sensitive material layer;
(7) the stacked entirety of putting formation of the first humidity-sensitive material layer, moisture barrier and the second humidity-sensitive material is carried out to photoetching, make top electrode cover the lower surface of the first humidity-sensitive material layer;
(8) utilize the sacrifice layer forming in propyl alcohol release steps (4), make the first humidity-sensitive material layer, moisture barrier, the second humidity-sensitive material layer and top electrode be positioned at the end of sacrifice layer top unsettled; The stacked entirety of putting formation of the first humidity-sensitive material layer, moisture barrier and the second humidity-sensitive material is cantilever design, is the wet cantilever of sense.
The capacitive humidity sensor with temperature drift compensation of the present invention is in the time of application, and the top electrode on the wet cantilever of sense and the bottom electrode on insulation course form a sensitization capacitance.In the time that ambient humidity changes, above being arranged in, be exposed to environment and must can be subject to ambient humidity impact by the second humidity-sensitive material layer, thereby cause volume change; The first humidity-sensitive material layer at moisture barrier between top electrode can not be subject to ambient humidity impact, or impact is very little, and therefore its constancy of volume or variation are also very little; But due to the first humidity-sensitive material layer between the second humidity-sensitive material layer for interfixing, two-layer volume change is inconsistent must cause the distortion of the wet cantilever entirety of sense, thereby drives the distortion of top electrode, has also just changed the capacitance of sensitization capacitance.
Beneficial effect of the present invention is: when perception ambient humidity that can be sensitiveer changes, the present invention can overcome the temperature that material temperature effect causes and float problem.In the time that environment temperature changes, because the first humidity-sensitive material layer in the wet cantilever of sense is identical in the material of the second humidity-sensitive material layer, and consistency of thickness, therefore there is identical expansion coefficient, volume change is consistent, can not exert an influence to top crown, also just can not change the electric capacity of top crown between bottom crown, there is the excellent properties of Low Drift Temperature.
In addition, the present invention is simple in structure, can utilize surface to manufacture for Machining Technology, and technique is also very simple.
Brief description of the drawings
Figure 1 shows that the structural representation of the capacitive humidity sensor with temperature drift compensation of the present invention.
Embodiment
For content of the present invention is become apparent more, be further described below in conjunction with the drawings and specific embodiments.
As shown in Figure 1, the capacitive humidity sensor with temperature drift compensation of the present invention comprises semiconductor substrate layer 1, insulation course 2, the wet cantilever of sense and induction electrode; Wherein:
Insulation course 2 is covered in the upper surface of semiconductor substrate layer 1;
One end of the wet cantilever of sense is fixed on insulation course 2, and the other end is positioned at the top of insulation course 2 unsettled; The wet cantilever of sense by from top to bottom successively stacked the first humidity-sensitive material layer 41, moisture barrier 42 and the second humidity-sensitive material layer 43 form, wherein the first humidity-sensitive material layer 41 is identical with the thickness of the second humidity-sensitive material layer 43;
Induction electrode comprises top electrode 31 and bottom electrode 32; Top electrode 31 covers the lower surface of the first humidity-sensitive material layer 41 in the wet cantilever of sense, and fixing; Bottom electrode 32 is fixed on insulation course 2; And the unsettled one end of top electrode 31 is parallel to bottom electrode 32, and be positioned at the top of bottom electrode 32.
For the stress that more obviously delivery context humidity causes, increase the sensitivity of humidity sensor, in the wet cantilever of sense, the thickness of the first humidity-sensitive material layer 41, the second humidity-sensitive material layer 43 is greater than the thickness of moisture barrier 42, top electrode 31.
The method of manufacturing the above-mentioned capacitive humidity sensor with temperature drift compensation, comprises the following steps:
(1) choose the material of silicon chip as semiconductor substrate layer 1;
(2) semiconductor substrate layer 1 is oxidized, makes to form insulation course 2 in the upper surface oxidation of semiconductor substrate layer;
(3) sputter layer of metal film on insulation course 2, and chemical wet etching forms bottom electrode 32;
(4) spin coating photoresist on insulation course 2, and photoetching forms sacrifice layer; Sacrifice layer covers an end of bottom electrode 32;
(5) at sacrifice layer upper surface sputter layer of metal film, and metallic film is carried out to photoetching form top electrode 31, and one end of top electrode 31 is parallel to bottom electrode 32, and be positioned at the top of lower electric 32 utmost points;
(6) at upper surface spin coating one deck humidity-sensitive material of top electrode 31, as the first humidity-sensitive material layer 41; And form every wet film, as moisture barrier 42 by plasma reinforced chemical meteorology deposition method at the upper surface of the first humidity-sensitive material layer 41; Again at upper surface spin coating one deck humidity-sensitive material of moisture barrier 42, as the second humidity-sensitive material layer 43;
(7) entirety of the first humidity-sensitive material layer 41, moisture barrier 42 and the second humidity-sensitive material layer 43 stacked formation is carried out to photoetching, make top electrode 32 cover the lower surface of the first humidity-sensitive material 41;
(8) utilize the sacrifice layer forming in propyl alcohol release steps (4), make the first humidity-sensitive material layer 41, moisture barrier 42, the second humidity-sensitive material layer 43 and top electrode 31 be positioned at the end of sacrifice layer top unsettled; The entirety of the first humidity-sensitive material layer 41, moisture barrier 42 and the second humidity-sensitive material layer 43 stacked formation is cantilever design, is the wet cantilever of sense.
Have the capacitive humidity sensor of temperature drift compensation in the time of application, the top electrode on the wet cantilever of sense and the bottom electrode on insulation course form a sensitization capacitance.In the time that ambient humidity changes, above being arranged in, be exposed to environment and must can be subject to ambient humidity impact by the second humidity-sensitive material layer, thereby cause volume change; The first humidity-sensitive material layer at moisture barrier between top electrode can not be subject to ambient humidity impact, or impact is very little, and therefore its constancy of volume or variation are also very little; But due to the first humidity-sensitive material layer between the second humidity-sensitive material layer for interfixing, two-layer volume change is inconsistent must cause the distortion of the wet cantilever entirety of sense, thereby drives the distortion of top electrode, has also just changed the capacitance of sensitization capacitance.
And in the time that environment temperature changes, because the first humidity-sensitive material layer in the wet cantilever of sense is identical in the material of the second humidity-sensitive material layer, and consistency of thickness, therefore there is identical expansion coefficient, volume change is consistent, can not exert an influence to top crown, also just can not change the electric capacity of top crown between bottom crown, there is the excellent properties of Low Drift Temperature.
Described in the present invention, concrete case study on implementation is only better case study on implementation of the present invention, is not used for limiting practical range of the present invention.Be that all equivalences of doing according to the content of the present patent application the scope of the claims change and modify, all should serve as technology category of the present invention.