Deposition of protective material at wafer level in front end for early stage particle and moisture protection

Patent metadata

Field	Value
Publication number	US-10858245-B2
Application number	US-201916447036-A
Country	US
Kind code	B2
Filing date	Jun 20, 2019
Priority date	Nov 30, 2017
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

A semiconductor device and a method of manufacturing the same are provided such that a microelectromechanical systems (MEMS) element is protected at an early manufacturing stage. A method for protecting a MEMS element includes: providing at least one MEMS element, having a sensitive area, on a substrate; and depositing, prior to a package assembly process, a protective material over the sensitive area of the at least one MEMS element such that the sensitive area of at least one MEMS element is sealed from an external environment, where the protective material permits a sensor functionality of the at least one MEMS element.

First claim

What is claimed is:

1. A method of protecting a microelectromechanical systems (MEMS) element, comprising:
integrating at least one MEMS element, comprising a sensitive area, at a main surface of a semiconductor substrate such that the at least one MEMS element is coplanar with the main surface;
forming at least one stop frame on the main surface of the semiconductor substrate at a region that surrounds the at least one MEMS element; and
depositing a protective material on the main surface of a semiconductor substrate including over the sensitive area of the at least one MEMS element such that the sensitive area of at least one MEMS element is sealed from an external environment, wherein the protective material permits a sensor functionality of the at least one MEMS element, and wherein the protective material is confined to inside the region defined by the at least one stop frame.

2. The method of claim 1 , further comprising:
forming at least one bond pad at the main surface of the semiconductor substrate; and
coupling each bond pad of the at least one bond pad to at least one bond wire,
wherein the at least one stop frame is disposed between the at least one bond pad and the at least one MEMS element such that the at least one stop frame prevents the protective material from coming in contact with any of the at least one bond pad and any of the at least one bond wire.

3. The method of claim 1 , further comprising:
preventing the protective material from contacting any bond wire and any bond pad.

4. The method of claim 1 , wherein depositing the protective material over the sensitive area of the at least one MEMS element is performed prior to any back-end process to the semiconductor substrate.

5. The method of claim 1 , wherein depositing the protective material over the sensitive area of the at least one MEMS element is performed prior to wire bonding.

6. The method of claim 1 , wherein depositing the protective material includes depositing the protective material onto a portion of the main surface of the semiconductor substrate.

7. The method of claim 1 , wherein the at least one stop frame is coupled directly to the main surface of the semiconductor substrate.

8. The method of claim 1 , wherein the semiconductor substrate forms a single semiconductor chip, and the at least one stop frame and the at least one MEMS element are integrated with the single semiconductor chip.

9. The method of claim 8 , wherein the protective material does not contact any electrical connection of the single semiconductor chip.

10. The method of claim 8 , further comprising:
forming at least one bond pad at the main surface of the semiconductor substrate; and
coupling each bond pad of the at least one bond pad to at least one bond wire,
wherein the at least one stop frame is disposed between the at least one bond pad and the at least one MEMS element such that the at least one stop frame prevents the protective material from coming in contact with any of the at least one bond pad and any of the at least one bond wire.

11. The method of claim 1 , wherein the at least one stop frame comprises imide, SU-8, or silicone, each having a higher degree of elastic modulus than the protective material.

12. The method of claim 1 , further comprising:
separating a portion of the semiconductor substrate that includes the at least one MEMS element and the at least one stop frame to form a semiconductor chip comprising the at least one MEMS element and the at least one stop frame;
forming at least one bond pad at the main surface of the semiconductor substrate; and
coupling each bond pad of the at least one bond pad to at least one bond wire,
wherein the at least one stop frame is disposed between the at least one bond pad and the at least one MEMS element such that the at least one stop frame prevents the protective material from coming in contact with any of the at least one bond pad and any of the at least one bond wire.

13. The method of claim 1 , further comprising:
separating a portion of the semiconductor substrate that includes the at least one MEMS element and the at least one stop frame to form a semiconductor chip comprising the at least one MEMS element and the at least one stop frame, wherein the semiconductor chip includes at least one stress-decoupling trench at an edge of the region such that the at least one stop frame is formed proximate to the at least one stress-decoupling trench and is configured to prevent the protective material from entering the at least one stress-decoupling trench.

14. The method of claim 1 , further comprising:
subsequent to depositing the protective material, performing a package assembly process, including mounting a chip to a package, wherein the chip includes a portion of the semiconductor substrate that includes the at least one MEMS element, the at least one stop frame, and the protective material.

15. The method of claim 1 , wherein the protective material is a temperature hardening gel or an ultraviolet (UV) hardening gel.

16. The method of claim 1 , wherein protective material permits full sensor functionality of the MEMS element, including mechanical functionality and electrical functionality, while sealing an entire surface of the at least one MEMS element.

17. The method of claim 1 , wherein depositing the protective material comprises:
dispensing the protective material over the sensitive area of the at least one MEMS element in one or more droplets such that the sensitive area of at least one MEMS element is sealed from the external environment.

18. The method of claim 1 , wherein depositing the protective material comprises:
dispensing the protective material such that it flows over the sensitive area of the at least one MEMS element such that the sensitive area of at least one MEMS element is sealed from the external environment.

19. A method of protecting a microelectromechanical systems (MEMS) element, comprising:
integrating at least one MEMS element, comprising a sensitive area, in a semiconductor substrate;
forming at least one stop frame on a main surface of the semiconductor substrate at a region that surrounds the at least one MEMS element;
depositing a protective material over the sensitive area of the at least one MEMS element such that the sensitive area of at least one MEMS element is sealed from an external environment, wherein the protective material permits a sensor functionality of the at least one MEMS element, and wherein the protective material is confined to inside the region defined by the at least one stop frame; and
separating a portion of the semiconductor substrate that includes the at least one MEMS element and the at least one stop frame to form a semiconductor chip comprising the at least one MEMS element and the at least one stop frame, wherein the semiconductor chip includes at least one stress-decoupling trench laterally spaced from the at least one MEMS element and extending into the semiconductor substrate.

20. The method of claim 19 , wherein:
the at least one stop frame is formed at an inner periphery of the at least one stress-decoupling trench.

21. A semiconductor device comprising:
a semiconductor chip comprising:
a semiconductor substrate having a main surface;
at least one microelectromechanical systems (MEMS) element, comprising a sensitive area, integrated at the main surface of the semiconductor substrate such that the at least one MEMS element is coplanar with the main surface;
at least one sto

Assignees

• Infineon Technologies Ag

Inventors

• Brandl Florian
• Fries Manfred
• Kalz Franz-Peter

Classifications

• H10W95/00

  Packaging processes not covered by the other groups of this subclass · CPC title

• H10W76/60

  Seals · CPC title

• H10W76/12

  characterised by their shape · CPC title

• B81B7/0048

  between the MEMS die and the substrate · CPC title

• B81B7/0025 Primary

  Protection against chemical alteration · CPC title