Trapped sacrificial structures and methods of manufacturing same using thin-film encapsulation

Patent metadata

Field	Value
Publication number	US-9422149-B2
Application number	US-201414532723-A
Country	US
Kind code	B2
Filing date	Nov 4, 2014
Priority date	Jul 25, 2014
Publication date	Aug 23, 2016
Grant date	Aug 23, 2016

Abstract

Trapped sacrificial structures and thin-film encapsulation methods that may be implemented to manufacture trapped sacrificial structures such as relative humidity sensor structures, and spacer structures that protect adjacent semiconductor structures extending above a semiconductor die substrate from being contacted by a molding tool or other semiconductor processing tool in an area of a die substrate adjacent the spacer structures.

First claim

What is claimed is:

1. A trapped sacrificial structure, comprising:
a MEMS region disposed over a substrate, the MEMS region including a MEMS structural layer;
a portion of a first sacrificial layer and a portion of a second sacrificial layer disposed over the MEMS structural layer;
an upper microshell layer disposed over the portions of the first and second sacrificial layers, the first sacrificial layer portion and/or a second sacrificial layer portion being configured to form at least one trapped sacrificial structure under the upper microshell layer; and
one or more upper release holes defined in the upper microshell layer.

2. The structure of claim 1 , where the portion of the first sacrificial layer is disposed partially over and in contact with the MEMS structural layer; where the portion of the second sacrificial layer is disposed over and in contact with the portion of the first sacrificial layer; where the upper microshell layer is disposed over the portions of the first and second sacrificial layers to trap the first and second sacrificial layer portions within a cavity filled with first and second sacrificial material under the upper microshell layer to form the at least one trapped sacrificial structure under the upper microshell layer; and where the trapped sacrificial structure further comprises:
one or more open cavities or open areas defined under the upper microshell layer and over the MEMS structural layer; and
a sealing layer that seals the upper release holes in the upper microshell layer.

3. The structure of claim 2 , further comprising a semiconductor device die that includes the substrate, the semiconductor device die having multiple individual spacer structures disposed in spaced relationship with each other over the semiconductor device die, each of the spacer structures comprising trapped sacrificial structures; and wherein a top of each of the spacer structures extends to a height above the substrate that is greater than a height of tops of one or more other structures that are disposed over the substrate in an area defined between the multiple spacer structures.

4. The structure of claim 3 , where the multiple spacer structures are spaced such that the spacer structures act to prevent a molding tool from contacting the tops of the other structures disposed over the substrate in the area defined between the multiple spacer structures when the molding tool is brought together with the semiconductor device die to contact the tops of the spacer structures.

5. The structure of claim 4 , where the other structures disposed over the substrate in the area defined between the multiple spacer structures comprise at least one membrane transducer structure.

6. The structure of claim 2 , where the trapped sacrificial structure is configured as a humidity-sensitive capacitor structure; and
where the MEMS structural layer is configured as a first sensor electrode, the MEMS structural layer having one or more sensor electrode openings defined to extend through the first sensor electrode of the MEMS structural layer;
where a portion of the second sacrificial layer is disposed over and in contact with the portion of the first sacrificial layer to form a humidity-sensitive capacitor dielectric structure disposed over the sensor electrode openings defined in the MEMS structural layer;
where the upper microshell layer is configured as a second sensor electrode over and in contact with the humidity-sensitive capacitor dielectric structure, the upper microshell layer being configured to trap the first and second sacrificial layer portions within a cavity filled with the first and second sacrificial material of the humidity-sensitive capacitor dielectric structure disposed under the upper microshell layer;
where an open fluid communication path is defined under the MEMS structural layer and through the sensor electrode openings to the underside of the humidity-sensitive capacitor dielectric structure; and
where one or more inlet openings are defined in the sealing layer and upper microshell layer that are in fluid communication with the open fluid communication path under the MEMS structural layer and through the sensor electrode openings to the underside of the humidity-sensitive capacitor dielectric structure.

7. The structure of claim 6 , where the first sacrificial layer portion trapped within the cavity under the upper microshell layer comprises polyimide.

8. The structure of claim 6 , where each of the first and second sacrificial layer portions trapped within the cavity under the upper microshell layer comprises polyimide.

9. The structure of claim 6 , where the capacitor dielectric structure has an outer periphery; and where the method further comprises creating the inlet openings in the sealing layer and upper microshell layer outside the outer periphery of the capacitor dielectric structure.

10. The structure of claim 6 , further comprising an additional trapped sacrificial structure configured as a non-humidity sensitive matched capacitor structure disposed over the same substrate as the humidity-sensitive capacitor structure; and
where a portion of a MEMS structural layer configured as a first sensor electrode having no sensor electrode openings;
where a portion of the second sacrificial layer is disposed over and in contact with the portion of the first sacrificial layer to form a matching capacitor dielectric structure disposed over the portion of the MEMS structural layer having no sensor electrode openings; and
where the upper microshell layer is configured as a second sensor electrode over and in contact with the matching capacitor dielectric structure, the upper microshell layer being configured to trap the first and second sacrificial layer portions within a cavity filled with the first and second sacrificial material of the matching capacitor dielectric structure disposed under the upper microshell layer.

11. The structure of claim 1 , where the second sacrificial layer is thicker than the first sacrificial layer.

Assignees

• Semiconductor Mfg Int Shanghai Corp

Inventors

• Quevy Emmanuel P
• Nervegna Louis
• Hui Jeremy R

Classifications

• B81C1/00285

  using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters · CPC title

• B81C1/0038

  Processes for creating layers of materials not provided for in groups B81C1/00357 - B81C1/00373 · CPC title

• B81B2201/0235

  Accelerometers · CPC title

• B81B2201/0214

  Biosensors; Chemical sensors · CPC title

• B81B7/0077

  Other packages not provided for in groups B81B7/0035 - B81B7/0074 · CPC title