Granted Patent B2

US 12,690,199 · App. 18/476,521 · Granted Jul 21, 2026

Inventors: Matt Bauer (Melbourne, FL); Jamel Burruss (Palm Bay, FL); Steven Kobosko (Vienna, VA)

Assignee: Eagle Technology, LLC

H10D1/474H01C1/01H01C17/22H01C17/30H10D86/85H10W70/05H10W70/688H01C7/006H10W70/69

Abstract

Claims (55)

1 . A method comprising:

forming a polyimide layer;

forming a thin film resistor on the polyimide layer;

forming, on the thin film resistor and the polyimide layer, a metallization layer that includes metal contacts on opposing ends of the thin film resistor but leaves an exposed surface of the polyimide layer;

baking the polyimide layer, the thin film resistor, and the metallization layer to remove water from the polyimide layer;

forming, on the exposed surface of the polyimide layer, a hydrophobic moisture barrier layer that prevents absorption of water into the polyimide layer to avoid blistering of the thin film resistor during subsequent laser trimming of the thin film resistor; and

laser trimming a resistance of the thin film resistor between the metal contacts.

2 . The method of claim 1 , wherein:

forming the hydrophobic moisture barrier layer includes forming a fluorinated moisture barrier layer on the exposed surface of the polyimide layer.

3 . The method of claim 2 , wherein:

forming the fluorinated moisture barrier layer includes plasma treating the exposed surface of the polyimide layer with carbon tetrafluoride to produce the fluorinated moisture barrier layer on the exposed surface.

4 . The method of claim 3 , wherein:

plasma treating includes plasma treating at a power, a pressure, and a gas flow rate configured to produce the fluorinated moisture barrier layer with a roughened surface to enhance hydrophobic properties of the fluorinated moisture barrier layer.

5 . The method of claim 1 , wherein laser trimming includes:

laser trimming the thin film resistor while measuring a resistance of the thin film resistor between the metal contacts; and

when measuring indicates the resistance is equal to a target resistance within a tolerance, stopping laser trimming.

6 . The method of claim 1 , wherein:

forming the thin film resistor includes forming the thin film resistor to include a trim pad; and

laser trimming includes laser trimming the trim pad.

7 . The method of claim 1 , wherein:

forming the polyimide layer includes baking the polyimide layer to evaporate solvent from the polyimide layer; and

after baking, curing the polyimide layer.

8 . The method of claim 1 , further comprising:

providing a substrate and forming the polyimide layer on the substrate.

9 . The method of claim 8 , wherein the substrate includes silicon.

10 . The method of claim 8 , further comprising:

forming alternated metallization layers and polyimide layers on the thin film resistor, the metallization layer, and the hydrophobic moisture barrier layer to produce a stack.

11 . The method of claim 10 , further comprising:

removing the substrate from the stack, leaving a flexible stack for an IC.

12 . An integrated circuit stack comprising:

a polyimide layer;

a thin film resistor formed on the polyimide layer;

a metallization layer having metal contacts formed on opposing ends of the thin film resistor and that leave an exposed surface of the polyimide layer; and

a hydrophobic moisture barrier layer formed on the exposed surface of the polyimide layer and that prevents absorption of water into the polyimide layer to avoid blistering of the thin film resistor when the thin film resistor is laser trimmed,

wherein the thin film resistor is laser trimmed to a target resistance between the metal contacts.

13 . The integrated circuit stack of claim 12 , wherein:

the hydrophobic moisture barrier layer includes a fluorinated moisture barrier layer.

14 . The integrated circuit stack of claim 12 , wherein:

the thin film resistor includes a trim pad that is laser trimmed to the target resistance.

15 . The integrated circuit stack of claim 12 , wherein:

the thin film resistor comprises one of nickel chromium, tantalum nitride, and chrome silicide.

16 . The integrated circuit stack of claim 15 , wherein the integrated circuit stack does not include a silicon substrate.

17 . The integrated circuit stack of claim 12 , further comprising:

alternated metallization layers and polyimide layers on the thin film resistor, the metallization layer, and the hydrophobic moisture barrier layer that collectively form the integrated circuit stack.

18 . The integrated circuit stack of claim 17 , wherein:

the alternated metallization layers, the polyimide layers on the thin film resistor, the metallization layer, and the hydrophobic moisture barrier layer collectively form flex redistribution layers.

19 . A method comprising:

forming a polyimide layer;

forming multiple thin film resistors on the polyimide layer;

forming, on the multiple thin film resistors and the polyimide layer, a metallization layer that includes metal contacts on opposing ends of each thin film resistor but leaves an exposed surface of the polyimide layer;

baking the polyimide layer, the multiple thin film resistors, and the metallization layer to remove water from the polyimide layer;

forming, on the exposed surface of the polyimide layer, a hydrophobic moisture barrier layer that prevents absorption of water into the polyimide layer to avoid blistering of the multiple thin film resistors during subsequent laser trimming of the multiple thin film resistors; and

laser trimming a resistance of each thin film resistor between the metal contacts for each thin film resistor.

20 . The method of claim 19 , wherein:

forming the hydrophobic moisture barrier layer includes forming a fluorinated moisture barrier layer on the exposed surface of the polyimide layer.

Assignments (1)

Continuity (1)

References Cited (20)