CN202433334U - Piezoresistive type humidity sensor with low temperature drift - Google Patents
Piezoresistive type humidity sensor with low temperature drift Download PDFInfo
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- CN202433334U CN202433334U CN2011205590223U CN201120559022U CN202433334U CN 202433334 U CN202433334 U CN 202433334U CN 2011205590223 U CN2011205590223 U CN 2011205590223U CN 201120559022 U CN201120559022 U CN 201120559022U CN 202433334 U CN202433334 U CN 202433334U
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Abstract
The utility model discloses a piezoresistive type humidity sensor with low temperature drift. The humidity sensor comprises a semiconductor substrate, a cantilever beam, a piezoresistor and an electrode lead which is connected with the piezoresistor, wherein the cantilever beam comprises a first humidity-sensitive material layer, a first isolating layer, a second humidity-sensitive material layer and a second isolating layer, which are arranged in sequence in an overlapped way; each layer of the cantilever beam is finished by a spin-coating process and fixed on the semiconductor substrate; the piezoresistor is formed in the semiconductor substrate below the cantilever beam in the form of ion implantation or diffusion; through photoetching the semiconductor substrate, one end of the cantilever beam is fixed on the semiconductor substrate and the other end of the cantilever beam is suspended; the piezoresistor is positioned below the fixed end of the cantilever beam; and when ambient humidity varies, the cantilever beam can apply a stress to the piezoresistor so that the variation of the ambient humidity can be reflected through measuring piezoresistance variation. The piezoresistive type humidity sensor with low temperature drift, disclosed by the utility model, has the advantage of simple manufacture craft; and by adopting the structure of the cantilever beam, the temperature can be effectively compensated, so as to realize the low temperature drift performance of the sensor.
Description
Technical field
The utility model relates to the humidity sensor technical field, the low temperature drift pressure drag humidity sensor that the pressure drag semi-girder that particularly adopts silicon micromachining technique to realize combines ELECTRODE WITH BILAYER POLYMERIC thing material to constitute.
Background technology
Humidity sensor is widely used, and traditional humidity sensor is main with the hygristor type, though this type sensor cost is low, measuring accuracy is relatively poor.Capacitance type humidity sensor is another kind of common humidity sensor structure, though such sensor is highly sensitive, interface circuit is complicated, and receives effect of parasitic capacitance easily.And that the resistance pressure type humidity sensor that utilizes the responsive principle of pressure drag counter stress to realize has an interface circuit is simple, and metering circuit element and the isolation of humidity environment electricity are applicable to the moisture measurement under the rugged surroundings such as inflammable and explosive, etc. advantage.But because such sensor adopts polymeric material, have big temperature and float, therefore how to design structure and test circuit is simple, and the humidity sensor of low temperature drift is still the key of present research.
Summary of the invention
The purpose of the utility model provides a kind of low temperature drift pressure drag humidity sensor, remedies in the prior art pressure drag humidity sensor temperature and floats bigger defective.
For realizing above-mentioned purpose, the technical scheme that the utility model is taked is: a kind of low temperature drift pressure drag humidity sensor, and it comprises Semiconductor substrate, semi-girder, voltage dependent resistor (VDR), and the contact conductor that connects voltage dependent resistor (VDR); Semi-girder one end is fixed on the upper surface of Semiconductor substrate, and the other end is unsettled;
Semi-girder is by the first humidity-sensitive material layer of overlapping placement, first separation layer, the second humidity-sensitive material layer and second separation layer are formed successively from bottom to up; And the first humidity-sensitive material layer is identical with the thickness of the second humidity-sensitive material layer;
Voltage dependent resistor (VDR) is positioned at the Semiconductor substrate of semi-girder below, and voltage dependent resistor (VDR) contacts with first separation layer of semi-girder.
In the utility model, in the semi-girder first separation layer and second separation layer be provided for cover the first humidity-sensitive material layer, when making ambient humidity change; The second humidity-sensitive material layer absorbs moisture; Volume changes, and the first humidity-sensitive material layer is because the covering of separation layer changes very little.Two humidity-sensitive material layers that interfix are because volume change is inconsistent up and down; Then can produce stress in the fixing end of semi-girder; And the voltage dependent resistor (VDR) that is positioned at below the semi-girder stiff end can induce stress, thereby changes resistance sizes, goes between through the external circuit connection electrode; Measure the size of pressure drag, can reflect the variation of ambient humidity.Simultaneously because two humidity-sensitive material layers have identical thermal expansivity, when two humidity-sensitive material layer thicknesses identical; During variation of ambient temperature; The flexible amplitude of two-layer up and down humidity-sensitive material layer is identical, just can not produce stress in fixing end, has well realized temperature compensation.
Preferably, in the semi-girder thickness of the first humidity-sensitive material layer and the second humidity-sensitive material layer greater than the thickness of first separation layer and second separation layer.Specifically, first separation layer and second separation layer intercept the steam that gets into the first humidity-sensitive material layer on the one hand, another convenient stress that transmits the generation of second humidity-sensitive material layer volume change, and the words effect that the thickness of selection separation layer is too thick can be poor.
Further, an end of definition voltage dependent resistor (VDR) respective cantilevered beam free end is first end, and the other end is second end; The Semiconductor substrate thickness of voltage dependent resistor (VDR) first end below is less than the Semiconductor substrate thickness of second end below.This structure setting can make stress concentrate on the bigger end of voltage dependent resistor (VDR) lower semiconductor substrate thickness, and pressure drag changes more obvious, can increase the sensitivity of sensor.
Further, the material of Semiconductor substrate is the silicon in [100] crystal orientation in the utility model.[100] the silicon face density in crystal orientation is less, is more conducive to utilize ion to inject or diffusion way formation pressure drag structure.
Make the method for above-mentioned low temperature drift pressure drag humidity sensor, may further comprise the steps:
(1). Semiconductor substrate is carried out oxidation, make each self-forming isolating oxide layer of upper and lower surface of Semiconductor substrate;
(2). the oxide layer to the Semiconductor substrate upper surface is carried out photoetching corrosion, to form pressure drag diffusion window; Inject or diffusion way through ion then, in the Semiconductor substrate of pressure drag diffusion beneath window, form the voltage dependent resistor (VDR) structure; Again the upper surface of oxide-semiconductor substrate makes the oxide layer that produces once more cover pressure drag diffusion window again;
(3). from lower surface Semiconductor substrate is carried out photoetching corrosion, form trapezoidal corrosion window, and make voltage dependent resistor (VDR) have only an end to be positioned at the top on base on the trapezoidal corrosion window; And the top of corrosion window and the distance between the voltage dependent resistor (VDR) are greater than zero;
(4). the upper surface in Semiconductor substrate carries out photoetching, forms fairlead, and splash-proofing sputtering metal aluminium in fairlead, and photoetching then forms the contact conductor that connects voltage dependent resistor (VDR);
(5). with the isolating oxide layer of Semiconductor substrate upper surface as first separation layer, at upper surface spin coating one deck humidity-sensitive material of first separation layer, as the first humidity-sensitive material layer; Utilize the plasma enhanced chemical vapor deposition method again, at the upper surface of the first humidity-sensitive material layer, sputter one deck isolating oxide layer is as second separation layer; Then at upper surface spin coating one deck humidity-sensitive material of second separation layer, as the second humidity-sensitive material layer; Integral body to first separation layer, the first humidity-sensitive material layer, second separation layer, the second humidity-sensitive material laminated form is carried out etching, forming semi-girder, and makes one of them end of semi-girder be positioned at the top of voltage dependent resistor (VDR); This end is defined as first end of semi-girder, and its opposite end is defined as second end of semi-girder; Second end of semi-girder is positioned at the top of corrosion window;
(6). the Semiconductor substrate between corrosion window and semi-girder second end is carried out photoetching and etching, makes that the second end end of semi-girder is unsettled.
Preferably, in the above-mentioned steps (3), to make voltage dependent resistor (VDR) be positioned at the length range of the end of top, base on the trapezoidal corrosion window to the etching of corrosion window; Be 2/3 ~ 4/5 of voltage dependent resistor (VDR) total length; When ambient humidity changed, the stress that semi-girder produces was concentrated in the position of pressure drag resistance other 1/3 ~ 5/5, and stress is more concentrated; Make that the variation of voltage dependent resistor (VDR) is more obvious, thereby improved the sensitivity of sensor.
The beneficial effect of the utility model is: the semi-girder that the utility model utilizes humidity-sensitive material to process obtains variation of ambient temperature; During the semi-girder volume change; Can be to the voltage dependent resistor (VDR) stress application; Thereby can reflect the variation of ambient humidity through the change in resistance of voltage dependent resistor (VDR), realize the basic function of humidity sensor.Because the material of two humidity-sensitive material layers is identical in the semi-girder, has identical expansion coefficient, the degree of therefore when temperature variation, stretching is identical, has realized temperature compensation, also is the low temperature drift performance of humidity sensor.
Description of drawings
Shown in Figure 1 is the structural representation of the low temperature drift pressure drag humidity sensor of the utility model;
Fig. 2 .1-Fig. 2 .5 is the method for making schematic flow sheet of the utility model low temperature drift pressure drag humidity sensor.
Embodiment
For the content that makes the utility model is more obviously understandable, further describe below in conjunction with accompanying drawing and embodiment.
As shown in Figure 1, the low temperature drift pressure drag humidity sensor of the utility model comprises Semiconductor substrate 1, semi-girder 3, voltage dependent resistor (VDR) 2, and the contact conductor 4 that connects voltage dependent resistor (VDR) 2; Semi-girder 3 one ends are fixed on the upper surface of Semiconductor substrate 1, and the other end is unsettled;
Semi-girder 3 is by first separation layer 31 of overlapping placement, the first humidity-sensitive material layer 33, second separation layer 32 and the second humidity-sensitive material layer 34 are formed successively from the bottom to top; And the first humidity-sensitive material layer 33 is identical with the thickness of the second humidity-sensitive material layer 34, and greater than the thickness of first separation layer 31 and second separation layer 32;
Voltage dependent resistor (VDR) 2 is positioned at the Semiconductor substrate 1 of semi-girder 3 belows, and voltage dependent resistor (VDR) 2 contacts with first separation layer 31 of semi-girder 3.As an end that defines voltage dependent resistor (VDR) 2 respective cantilevered beams 3 free ends is first end, and the other end is second end; The Semiconductor substrate thickness of voltage dependent resistor (VDR) 2 first ends below is less than the Semiconductor substrate thickness of second end below.This structure setting can make stress concentrate on the bigger end of voltage dependent resistor (VDR) 2 lower semiconductor substrate thickness, and pressure drag changes more obvious, can increase the sensitivity of sensor;
In addition, the material of Semiconductor substrate 1 is the silicon in [100] crystal orientation in the utility model, and the silicon face density in [100] crystal orientation is less, is more conducive to utilize ion to inject or diffusion way formation pressure drag structure.
In conjunction with Fig. 2 .1-Fig. 2 .5, make the method for the utility model low temperature drift pressure drag humidity sensor, may further comprise the steps:
(1). Semiconductor substrate 1 is carried out oxidation, make each self-forming isolating oxide layer of upper and lower surface of Semiconductor substrate 1;
(2). the oxide layer to Semiconductor substrate 1 upper surface is carried out photoetching corrosion, to form pressure drag diffusion window; Inject or diffusion way through ion then, in the Semiconductor substrate of pressure drag diffusion beneath window, form voltage dependent resistor (VDR) 2 structures; Again the upper surface of oxide-semiconductor substrate 1 makes the oxide layer that produces once more cover pressure drag diffusion window, shown in Fig. 2 .1 again;
(3). from lower surface Semiconductor substrate 1 is carried out photoetching corrosion, form trapezoidal corrosion window 101, and make voltage dependent resistor (VDR) 2 have only an end to be positioned at the top on base on the trapezoidal corrosion window 101; And the distance between the top of corrosion window 101 and the voltage dependent resistor (VDR) 2 is greater than zero; In addition; Etching to corrosion window 101 will make voltage dependent resistor (VDR) 2 be positioned at the length range of the end of top, base on the trapezoidal corrosion window; For 2/3 ~ 4/5 of voltage dependent resistor (VDR) total length, when ambient humidity changed, the stress that semi-girder produces was concentrated in the position of pressure drag resistance other 1/3 ~ 5/5; Stress is concentrated can make that the variation of voltage dependent resistor (VDR) is more obvious, thereby improves the sensitivity of sensor; Shown in Fig. 2 .2;
(4). the upper surface in Semiconductor substrate 1 carries out photoetching, forms fairlead, and splash-proofing sputtering metal aluminium in fairlead, and photoetching then forms the contact conductor 4 that connects voltage dependent resistor (VDR); Shown in Fig. 2 .3;
(5). with the isolating oxide layer of Semiconductor substrate 1 upper surface as first separation layer 31, at upper surface spin coating one deck humidity-sensitive material of first separation layer 31, as the first humidity-sensitive material layer 33; Utilize the plasma enhanced chemical vapor deposition method again, at the upper surface of the first humidity-sensitive material layer 33, sputter one deck isolating oxide layer is as second separation layer 32; Then at upper surface spin coating one deck humidity-sensitive material of second separation layer 32, as the second humidity-sensitive material layer 34; Integral body to first separation layer 31, the first humidity-sensitive material layer 33, second separation layer 32, the 34 stacked formation of the second humidity-sensitive material layer is carried out etching, forming semi-girder 3, and makes one of them end of semi-girder 3 be positioned at the top of voltage dependent resistor (VDR) 2; As this end being defined as first end of semi-girder 3, its opposite end is defined as second end of semi-girder 3, and then second end of semi-girder is positioned at the top of corrosion window 101; Shown in Fig. 2 .4;
(6). the Semiconductor substrate between corrosion window 101 and semi-girder second end is carried out photoetching and etching, makes that the second end end of semi-girder is unsettled, shown in Fig. 2 .5.
In the utility model, in the semi-girder 3 first separation layer 31 and second separation layer 32 be provided for cover the first humidity-sensitive material layer, when making ambient humidity change; The second humidity-sensitive material layer absorbs moisture; Volume changes, and the first humidity-sensitive material layer is because the covering of separation layer changes very little.Two humidity-sensitive material layers that interfix are because volume change is inconsistent up and down; Then can produce stress in the fixing end of semi-girder; And the voltage dependent resistor (VDR) that is positioned at below the semi-girder stiff end can induce stress, thereby changes resistance sizes, goes between through the external circuit connection electrode; Measure the size of pressure drag, can reflect the variation of ambient humidity.Simultaneously because two humidity-sensitive material layers have identical thermal expansivity, when two humidity-sensitive material layer thicknesses identical; During variation of ambient temperature; The flexible amplitude of two-layer up and down humidity-sensitive material layer is identical, just can not produce stress in fixing end, has well realized temperature compensation.
The case of practical implementation described in the utility model is merely the preferable case study on implementation of the utility model, is not the practical range that is used for limiting the utility model.Be that all equivalences of doing according to the content of the utility model claim change and modification, all should be as the technological category of the utility model.
Claims (4)
1. a low temperature drift pressure drag humidity sensor is characterized in that, comprises Semiconductor substrate, semi-girder, voltage dependent resistor (VDR), and the contact conductor that connects voltage dependent resistor (VDR); Semi-girder one end is fixed on the upper surface of Semiconductor substrate, and the other end is unsettled;
Semi-girder is by the first humidity-sensitive material layer of overlapping placement, first separation layer, the second humidity-sensitive material layer and second separation layer are formed successively from bottom to up; The first humidity-sensitive material layer is identical with the thickness of the second humidity-sensitive material layer;
Voltage dependent resistor (VDR) is positioned at the Semiconductor substrate of semi-girder below, and voltage dependent resistor (VDR) contacts with first separation layer of semi-girder.
2. low temperature drift pressure drag humidity sensor according to claim 1 is characterized in that the thickness of the first humidity-sensitive material layer and the second humidity-sensitive material layer is greater than the thickness of first separation layer and second separation layer in the semi-girder.
3. low temperature drift pressure drag humidity sensor according to claim 1 is characterized in that, an end of definition voltage dependent resistor (VDR) respective cantilevered beam free end is first end, and the other end is second end; The Semiconductor substrate thickness of voltage dependent resistor (VDR) first end below is less than the Semiconductor substrate thickness of second end below.
4. according to claim 1 or 2 or 3 described low temperature drift pressure drag humidity sensors, it is characterized in that the material of Semiconductor substrate is the silicon in [100] crystal orientation.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2011205590223U CN202433334U (en) | 2011-12-29 | 2011-12-29 | Piezoresistive type humidity sensor with low temperature drift |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2011205590223U CN202433334U (en) | 2011-12-29 | 2011-12-29 | Piezoresistive type humidity sensor with low temperature drift |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102565142A (en) * | 2011-12-29 | 2012-07-11 | 东南大学 | Low-temperature drift piezoresistive humidity sensor and manufacturing method thereof |
| CN102914623A (en) * | 2012-10-19 | 2013-02-06 | 南京信息工程大学 | Fusing method of temperature compensation of humidity sensor |
| CN104614079A (en) * | 2015-02-10 | 2015-05-13 | 东南大学 | Infrared sensor |
| CN114018991A (en) * | 2021-09-18 | 2022-02-08 | 中国科学院微电子研究所 | Humidity sensor and preparation method thereof |
-
2011
- 2011-12-29 CN CN2011205590223U patent/CN202433334U/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102565142A (en) * | 2011-12-29 | 2012-07-11 | 东南大学 | Low-temperature drift piezoresistive humidity sensor and manufacturing method thereof |
| CN102914623A (en) * | 2012-10-19 | 2013-02-06 | 南京信息工程大学 | Fusing method of temperature compensation of humidity sensor |
| CN102914623B (en) * | 2012-10-19 | 2014-12-10 | 南京信息工程大学 | Fusing method of temperature compensation of humidity sensor |
| CN104614079A (en) * | 2015-02-10 | 2015-05-13 | 东南大学 | Infrared sensor |
| CN104614079B (en) * | 2015-02-10 | 2017-10-03 | 东南大学 | A kind of infrared sensor |
| CN114018991A (en) * | 2021-09-18 | 2022-02-08 | 中国科学院微电子研究所 | Humidity sensor and preparation method thereof |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120912 Termination date: 20131229 |