Fingerprint sensor device and method for manufacturing a semiconductor sensor device comprising a cover layer having an anisotropic dielectric constant

1. A method for manufacturing a fingerprint sensor device, the method comprising:

providing a fingerprint sensor chip comprising a capacitive sensing array being arranged on a first side of the fingerprint sensor chip, the sensing array comprising a plurality of electrically conductive sensing elements, the fingerprint sensor chip being configured to acquire an image of a finger placed on a sensing surface of the fingerprint sensor device;

arranging the fingerprint sensor chip on a carrier with a second side of the fingerprint sensor chip facing the carrier, the second side being opposite of the first side;

depositing a cover layer on the first side of the fingerprint sensor chip, the cover layer comprising a polarizable material;

moving a top electrode into contact with a top surface of the cover layer; and

applying a voltage between the top electrode and a bottom electrode located below the cover layer and comprised in a material stack between the bottom of the carrier and the cover layer, creating an electric field in the cover layer, thereby poling the cover layer such that a dielectric constant of the cover layer in a direction perpendicular to the sensing array is higher than a dielectric constant in a direction parallel to the sensing array, thereby forming a cover layer having an anisotropic dielectric constant.

2. The method according to claim 1 , wherein the bottom electrode is a metal layer integrated in the carrier.

3. The method according to claim 1 , further comprising arranging an adhesive conductive die attach film on the carrier and attaching the fingerprint sensor chip to the carrier by means of the adhesive conductive die attach film, the adhesive conductive die attach film thereby acting as the bottom electrode.

4. The method according to claim 1 , further comprising depositing a metal layer on the second side of the fingerprint sensor chip, the metal layer acting as the bottom electrode.

5. The method according to claim 1 , wherein the bottom electrode is a metal layer integrated in the fingerprint sensor chip.

6. The method according to claim 5 , wherein the bottom electrode comprises the plurality of electrically conductive sensing elements of the sensing array.

7. The method according to claim 1 , wherein the bottom electrode is a homogeneous metal layer.

8. The method according to claim 1 , further comprising heating the cover layer simultaneously to applying a voltage, thereby annealing the molding material.

9. The method according to claim 1 , further comprising heating the top electrode simultaneously to applying a voltage, thereby annealing the molding material.

10. The method according to claim 1 , wherein applying a voltage between the top electrode and the bottom electrodes comprises grounding the bottom electrode and applying a voltage to the top electrode.

11. The method according to claim 1 , further comprising a controlling a voltage between the top electrode and the bottom electrode such that an electric field over the fingerprint sensor chip is below 25 V/μm.

12. A fingerprint sensor device comprising:

a fingerprint sensor chip comprising a capacitive sensing array being arranged on a first side of the fingerprint sensor chip, the sensing array comprising a plurality of electrically conductive sensing elements, the sensor device being configured to acquire an image of a finger placed on a sensing surface of the fingerprint sensor module;

an electrically conductive layer configured to act as a bottom electrode;

a cover layer arranged over the capacitive sensing array, the cover layer comprising a polarized material, wherein the cover layer is a poled layer having an anisotropic dielectric constant such that a dielectric constant of the cover layer in a direction perpendicular to the sensing array is higher than a dielectric constant in a direction parallel to the sensing array, wherein the electrically conductive layer configured to act as a bottom electrode is comprised in a material stack between the bottom of the fingerprint sensor chip and the cover layer.

13. The fingerprint sensor device according to claim 12 , wherein the electrically conductive layer configured to act as a bottom electrode is a metal layer located on a second side of the fingerprint sensor chip, the second side being opposite of the first side.

14. The fingerprint sensor device according to claim 12 , wherein the electrically conductive layer configured to act as a bottom electrode is a metal layer integrated in the fingerprint sensor chip.

15. The fingerprint sensor device according to claim 12 , wherein the electrically conductive layer configured to act as a bottom electrode is a homogeneous metal layer.

16. The fingerprint sensor device according to claim 12 , wherein the electrically conductive layer configured to act as a bottom electrode comprises the plurality of electrically conductive sensing elements of the sensing array.