Method for via formation by micro-imprinting

Abstract

A method and apparatus for forming a plurality of vias in panels for advanced packaging applications is disclosed, according to one embodiment. A redistribution layer is deposited on a substrate layer. The redistribution layer may be deposited using a spin coating process, a spray coating process, a drop coating process, or lamination. The redistribution layer is then micro-imprinted using a stamp inside a chamber. The redistribution layer and the stamp are then baked inside the chamber. The stamp is removed from the redistribution layer to form a plurality of vias in the redistribution layer. Excess residue built-up on the redistribution layer may be removed using a descumming process. A residual thickness layer disposed between the bottom of each of the plurality of vias and the top of the substrate layer may have thickness of less than about 1 μm.

What is claimed is: 
     
         1 . A method of forming a plurality of vias in a substrate, comprising:
 micro-imprinting a flowable epoxy layer with a stamp inside a chamber, the flowable epoxy layer comprising silica particle fillers;   baking the flowable epoxy layer and the stamp inside the chamber; and   removing the stamp from the flowable epoxy layer to form the plurality of vias in the flowable epoxy layer.   
     
     
         2 . The method of  claim 1 , wherein the stamp has a multi-stamp layout or a full field layout. 
     
     
         3 . The method of  claim 1 , further comprising:
 exposing the flowable epoxy layer and the stamp to UV light prior to removing the stamp from the flowable epoxy layer; and   performing an oven curing process on the flowable epoxy layer after removing the stamp from the flowable epoxy layer.   
     
     
         4 . The method of  claim 1 , wherein the flowable epoxy layer comprises one or more materials that are flowable at a temperature between about 90-180 degrees Celsius, and wherein the flowable epoxy layer is curable at a temperature greater than or equal to about 180 degrees Celsius. 
     
     
         5 . The method of  claim 1 , wherein the flowable epoxy layer and the stamp are baked inside the chamber at a temperature between about 180-200 degrees Celsius for about 1-5 minutes. 
     
     
         6 . The method of  claim 1 , further comprising depositing the flowable epoxy layer on a substrate layer prior to micro-imprinting the flowable epoxy layer, wherein the flowable epoxy layer is deposited by lamination. 
     
     
         7 . The method of  claim 1 , wherein micro-imprinting the flowable epoxy layer comprises:
 laminating the flowable epoxy layer on the stamp;   attaching the stamp to a substrate layer; and   baking the flowable epoxy layer and the stamp inside the chamber at a temperature between about 140-180 degrees Celsius.   
     
     
         8 . The method of  claim 1 , wherein the stamp is removed from the flowable epoxy layer at a temperature between about 140-180 degrees Celsius. 
     
     
         9 . The method of  claim 1 , wherein the stamp comprises a plurality of pillars having a height equal to or greater than a thickness of the flowable epoxy layer. 
     
     
         10 . A method of forming a plurality of vias in a substrate, comprising:
 depositing a polyimide layer on a substrate layer;   pre-baking the polyimide layer;   micro-imprinting the polyimide layer with a stamp inside a chamber;   baking the polyimide layer and the stamp inside the chamber;   exposing the polyimide layer and the stamp to a UV light curing process;   removing the stamp from the polyimide layer to form the plurality of vias in the polyimide layer;   performing an oven curing process on the polyimide layer; and   descumming the polyimide layer to remove excess residue.   
     
     
         11 . The method of  claim 10 , wherein the polyimide layer is deposited using a spin coating process or a spray coating process. 
     
     
         12 . The method of  claim 10 , wherein the pre-baking the polyimide layer is performed at a temperature between about 75 to 90 degrees Celsius. 
     
     
         13 . The method of  claim 10 , wherein micro-imprinting the polyimide layer is performed at a pressure of about 1 bar or greater. 
     
     
         14 . The method of  claim 13 , wherein micro-imprinting the polyimide layer is performed at a temperature between about 50 degrees to 100 degrees Celsius. 
     
     
         15 . The method of  claim 10 , wherein baking the polyimide layer is performed at a temperature between about 80 degrees to 200 degrees Celsius. 
     
     
         16 . The method of  claim 10 , wherein exposing the polyimide layer and the stamp to a UV light curing process comprises exposing the polyimide layer and the stamp to UV light having a wavelength between about 360 to 370 nm, and a temperature between about 25 to 100 degrees Celsius. 
     
     
         17 . The method of  claim 10 , wherein descumming the polyimide layer is performed at a temperature between about 0 to 20 degrees Celsius. 
     
     
         18 . The method of  claim 17 , wherein the descumming the polyimide layer comprises:
 etching the excess residue one or more times;   performing a cooling process after each etch of the excess residue; and   performing a cleaning process.   
     
     
         19 . A method of forming a plurality of vias in a substrate, comprising:
 depositing a polyimide layer on a substrate layer via a spray coating or spin coating process;   pre-baking the polyimide layer at a temperature between about 75 to 90 degrees Celsius;   micro-imprinting the polyimide layer with a transparent stamp inside a chamber;   baking the polyimide layer and the transparent stamp inside the chamber at a temperature between about 80 degrees to 200 degrees Celsius;   exposing the polyimide layer and the transparent stamp to a UV light curing process;   removing the transparent stamp from the polyimide layer to form the plurality of vias in the polyimide layer;   performing an oven curing process on the polyimide layer; and   descumming the polyimide layer at a temperature between about 0 to 20 degrees Celsius to remove excess residue.   
     
     
         20 . The method of  claim 10 , wherein micro-imprinting the polyimide layer is performed at a pressure of about 1 bar or greater and at a temperature between about 50 degrees to 100 degrees Celsius.