CN102590291A

CN102590291A - Method for manufacturing improved humidity sensor

Info

Publication number: CN102590291A
Application number: CN2012100130805A
Authority: CN
Inventors: 宁文果; 罗乐; 徐高卫; 朱春生; 李珩
Original assignee: Shanghai Institute of Microsystem and Information Technology of CAS
Current assignee: Shanghai Institute of Microsystem and Information Technology of CAS
Priority date: 2012-01-16
Filing date: 2012-01-16
Publication date: 2012-07-18
Anticipated expiration: 2032-01-16
Also published as: CN102590291B

Abstract

The invention relates to a method for manufacturing an improved humidity sensor. The method is characterized by comprising the following steps of: coating a polyimide film serving as a humidity sensitive material between electrode plates, making a cavity in the polyimide layer by using a photoetching technology, and forming silicon through holes in the bottom of the cavity by using a corrosion method. The contact area between the sensor and the surrounding environment is enlarged, and simultaneously gas conveniently passes through the sensor; and the sensor has the characteristic of short response time.

Description

A kind of method for making of modified humidity sensor

Technical field

The present invention relates to a kind of method for making of modified humidity sensor, relate to a kind of humidity sensor method for making or rather, belong to sensor field based on polyimide and back side corrosion silicon.

Background technology

Humidity sensor mainly contains two big types of resistance-type, condenser types.

The characteristics of resistance-type humidity sensor are on substrate, to cover the film that one deck is processed with wet sensory material, and when airborne water vapor adsorption was on humidity-sensitive film, the resistivity and the resistance value of element all changed, and utilized this characteristic to get final product humidity measuring.

Capacitance type humidity sensor is generally processed with macromolecule membrane electric capacity, and macromolecular material commonly used has polystyrene, polyimide, butyric acid acetate fiber etc.When ambient humidity changed, the specific inductive capacity of humicap changed, and its electric capacity is also changed, and its capacitance change is directly proportional with relative humidity.

The performance index of humidity sensor mainly contain the measuring accuracy response time etc.

The advantage of capacitance type humidity sensor is that capacitance variations and humidity present the highly linear relation, has occupied about 75% the market share.

In capacitance type sensor, often use polyimide as thin-film capacitor, this material and ic process compatibility, stable chemical performance, water permeability is good.

Shortcomings such as traditional capacitance type humidity sensor generally is made up of two-layer electrode and one deck macromolecular material, and this sensor and surrounding environment contact area are limited, and the response time is long.

From capacitance equation, the method that improves the performance of humidity sensor mainly contains two kinds, and a kind of is the wet sensing performance that improves macromolecular material, thereby after material is confirmed, can only change the performance of the structure raising humidity sensor of sensor.

Traditional humidity sensor, basic structure are between electrode, to make macromolecular material as wet sensory material, on macromolecular material, do not make figure usually.Patent of the present invention changes traditional humidity sensor construction, in polyimide material, makes cavity by lithography, has improved the contact area of film and surrounding environment.The position of corresponding cavity makes the silicon through hole on silicon chip simultaneously, compares with the sensor that does not have the silicon through hole, and this sensor is convenient to gas and is passed through smoothly, thereby has reduced the response time of humidity sensor; Thereby be guided out design of the present invention.

Summary of the invention

In order to reduce the response time; Improve the performance of humidity sensor structure; The present invention proposes a kind of method for making of modified humidity sensor structure; The polyimide layer that it is characterized in that between battery lead plate, applying utilizes photoetching technique to make cavity in polyimide film layer as the humidity sensitive material then, and the bottom respective production has the silicon through hole of being made by caustic solution; Improved the contact area of film and surrounding environment, be convenient to gas simultaneously and pass through sensor.

Concrete making step of the present invention: 1. at first on silicon wafer, make the silicon through hole; Then 2. on silicon chip the splash-proofing sputtering metal layer as Seed Layer; 3. electroplate out capacitance electrode then; 4. 5. coating polyimide utilizes photoetching technique to make cavity at silicon through hole correspondence position in polyimide as the dielectric material of electric capacity and the humidity sensitive material of sensor at last again.Also be that the bottom respective production has the silicon through hole of being made by caustic solution.This method improves the contact area of thin-film dielectric material and surrounding environment, has deepened the passage of ambient gas entering sensor, is convenient to gas through sensor (seeing embodiment for details).

This shows that cavity of the present invention is characterised in that:

1. described cavity is to make single cavity along the electroplax direction.

2. described cavity is to make a plurality of cavitys along the electroplax direction.

3. described cavity is that vertical electroplax direction is made a plurality of cavitys.

4. described cavity is to make a plurality of independently cavitys in the polyimide between battery lead plate

5. described a plurality of cavitys are more than 2 or 2; The quantity of cavity is many more, and the cavity opening is more little, and then the performance of humidity sensor is good more.

Description of drawings

Fig. 1 is that humidity sensor is made process flow diagram, the silicon chip of wherein a) making, b) the positive SiO that makes ₂Layer, c) splash-proofing sputtering metal Seed Layer d) is electroplated out capacitor plate, e) applies PI, f) makes cavity.

Fig. 2 is a three-dimensional plot after sensor production is accomplished.

Fig. 3 makes a plurality of cavitys (plan view) along the battery lead plate direction in the polyimide between battery lead plate.

Fig. 4 is that vertical electrical pole plate direction is made a plurality of cavitys (sensor upper surface vertical view) in the polyimide between battery lead plate

Fig. 5 keeps a plurality of independently polyimide block (sensor upper surface vertical view) in the polyimide between battery lead plate

Embodiment

For advantage of the present invention and good effect are found full expression, substantive distinguishing features of the present invention and obvious improvement are described further below in conjunction with accompanying drawing and embodiment.

Embodiment 1

At first, prepare to make the silicon chip 1 (like Fig. 1 (a)) of humidity sensor;

The positive SiO that makes ₂Layer 2, shown in Fig. 1 (b),

(2) follow splash-proofing sputtering metal Seed Layer 3 on silicon chip 1, typical seed layer materials comprises TiW/Cu (like Fig. 1 (c));

(3) yet, electroplate out capacitive electrode plates 4 and erode unnecessary Seed Layer, typical battery lead plate material comprises (like Fig. 1 (d)) such as Au;

(4) coating polyimide 5, make capacitor dielectric material (like Fig. 1 (e));

(5) in polyimide, utilize photoetching technique to make cavity 6, and solidify (like Fig. 1 (f);

In Fig. 1 (g), in polyimide, make the silicon through hole with cavity 6 correspondence positions, can make by wet method or dry method.

Humidity sensor three-dimensional plot after the making is as shown in Figure 2, and vertical view is as shown in Figure 3, and plan view is as shown in Figure 4, and upward view is as shown in Figure 5.

Embodiment 2

As shown in Figure 3, make a plurality of cavitys along the battery lead plate direction in the polyimide between battery lead plate.More than 2 or 2, under the condition that satisfies the lithographic accuracy requirement, number of cavities is many more single for number of cavities, and the opening of cavity is more little, and the performance of sensor should be good more.

Embodiment 3

Cavity among the embodiment 1 is as shown in Figure 4, and vertical electrical pole plate direction is made a plurality of cavitys in the polyimide between battery lead plate.Number of cavities is more than 2 or 2, and under the condition that satisfies the lithographic accuracy requirement, number of cavities is many more, and the opening of cavity is more little, and the performance of sensor should be good more.

Embodiment 4

Cavity among the embodiment 1 is as shown in Figure 5, makes a plurality of independently cavitys in the polyimide between battery lead plate.Number of cavities is more than 2 or 2, and under the condition that satisfies the lithographic accuracy requirement, number of cavities is many more, and the opening of cavity is more little, and the performance of sensor should be good more.

Claims

1. the method for making of a follow-on humidity sensor; The polyimide layer that it is characterized in that between battery lead plate, applying is as the humidity sensitive material; In polyimide film layer, utilize photoetching technique to make cavity then, the bottom respective production has the silicon through hole of being made by caustic solution; Concrete steps are:

1. at first on silicon wafer, make the silicon through hole;

2. on silicon chip the splash-proofing sputtering metal layer as Seed Layer;

3. electroplate out capacitance electrode then;

4. again coating polyimide as the dielectric material of electric capacity and the humidity sensitive material of sensor;

5. in Kapton, utilize photoetching technique to make cavity at last at silicon through hole correspondence position.

2. by the described method of claim 1, it is characterized in that described cavity is to make single cavity along the electroplax direction.

3. by the described method of claim 1, it is characterized in that described cavity is to make a plurality of cavitys along the electroplax direction.

4. by the described method of claim 1, it is characterized in that described cavity is that vertical electroplax direction is made a plurality of cavitys.

5. by the described method of claim 1, it is characterized in that described cavity is to make a plurality of independently cavitys in the polyimide between battery lead plate.

6. by any described method among the claim 3-5, it is characterized in that:

1. a plurality of cavitys are more than 2 or 2;

2. the quantity of cavity is many more, and the cavity opening is more little, and then the performance of humidity sensor is good more.