CN102590291B

CN102590291B - Method for manufacturing improved humidity sensor

Info

Publication number: CN102590291B
Application number: CN201210013080.5A
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: 2014-03-12
Anticipated expiration: 2032-01-16
Also published as: CN102590291A

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 improved humidity sensor

Technical field

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

Background technology

Humidity sensor mainly contains resistance-type, the large class of condenser type two.

The feature of resistance-type humidity sensor is on substrate, to cover the film that one deck is made with wet sensory material, and when airborne water vapor adsorption is on humidity-sensitive film, resistivity and the resistance value of element all change, and utilize this characteristic can measure humidity.

Capacitance type humidity sensor is generally made with macromolecule membrane electric capacity, and conventional macromolecular material has polystyrene, polyimide, butyric acid acetate fiber etc.When ambient humidity changes, the specific inductive capacity of humicap changes, and its electric capacity is also changed, and its capacitance change is directly proportional to 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 highly linear relation, has occupied approximately 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.

The shortcomings such as traditional capacitance type humidity sensor is generally comprised 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 decision, can only change the performance of the structure raising humidity sensor of sensor.

Traditional humidity sensor, basic structure, for to make macromolecular material as wet sensory material between electrode, is not made figure conventionally on macromolecular material.Patent of the present invention changes traditional humidity sensor construction, makes cavity in polyimide material by lithography, has improved the contact area of film and surrounding environment.On silicon chip, the position of corresponding cavity makes silicon through hole simultaneously, does not compare with there is no the sensor of 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 improved humidity sensor structure, it is characterized in that the polyimide layer applying is as humidity sensitive material between battery lead plate, then in polyimide film layer, utilize photoetching technique to make cavity, cavity 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. first make silicon through hole on silicon wafer, then 2. on silicon chip splash-proofing sputtering metal layer as Seed Layer, 3. then electroplate out capacitance electrode, 4. coating polyimide, as the dielectric material of electric capacity and the humidity sensitive material of sensor, 5. finally utilizes photoetching technique to make cavity at silicon through hole correspondence position in polyimide again.Also be that cavity 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, deepened the passage that ambient gas enters sensor, is convenient to gas by sensor (referring to embodiment).

As can be seen here, cavity of the present invention is characterised in that:

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

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

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

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

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

Accompanying drawing explanation

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) electroplates out capacitor plate, e) applies PI, f) making cavity.

Fig. 2 is three-dimensional plot after sensor production completes.

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

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

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

Embodiment

In order to make advantage of the present invention and good effect find full expression, below in conjunction with drawings and Examples, substantive distinguishing features of the present invention and significant progress are described further.

Embodiment 1

First, prepare to make the silicon chip 1 (as Fig. 1 (a)) of humidity sensor;

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

(2) follow splash-proofing sputtering metal Seed Layer 3 on silicon chip 1, typical seed layer materials

Comprise TiW/Cu (as Fig. 1 (c));

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

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

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

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

As shown in Figure 2, as shown in Figure 3, as shown in Figure 4, upward view as shown in Figure 5 for plan view for vertical view for humidity sensor three-dimensional plot after making.

Embodiment 2

As shown in Figure 3, in the polyimide between battery lead plate, along battery lead plate direction, make a plurality of cavitys.Number of cavities more than 2 or 2, is meeting under the condition of lithographic accuracy requirement single, and number of cavities is more, and the opening of cavity is less, and the performance of sensor should be better.

Embodiment 3

As shown in Figure 4, in the polyimide between battery lead plate, vertical electrode plate direction is made a plurality of cavitys to cavity in embodiment 1.Number of cavities, more than 2 or 2, is meeting under the condition of lithographic accuracy requirement, and number of cavities is more, and the opening of cavity is less, and the performance of sensor should be better.

Embodiment 4

Cavity in embodiment 1 as shown in Figure 5, is made a plurality of independently cavitys in the polyimide between battery lead plate.Number of cavities, more than 2 or 2, is meeting under the condition of lithographic accuracy requirement, and number of cavities is more, and the opening of cavity is less, and the performance of sensor should be better.

Claims

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

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

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

3. then electroplate out capacitance electrode;

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

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

2. by method claimed in claim 1, it is characterized in that described cavity is to make single cavity along battery lead plate direction.

3. by method claimed in claim 1, it is characterized in that described cavity is to make a plurality of cavitys along battery lead plate direction.

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

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

6. by the method described in any one in 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 more, and cavity opening is less, and the performance of humidity sensor is better.