Micro device transfer head assembly

Abstract

A method of transferring a micro device and an array of micro devices are disclosed. A carrier substrate carrying a micro device connected to a bonding layer is heated to a temperature below a liquidus temperature of the bonding layer, and a transfer head is heated to a temperature above the liquidus temperature of the bonding layer. Upon contacting the micro device with the transfer head, the heat from the transfer head transfers into the bonding layer to at least partially melt the bonding layer. A voltage applied to the transfer head creates a grip force which picks up the micro device from the carrier substrate.

What is claimed is: 
     
         1 . A micro device transfer head array comprising;
 a base substrate;   an array of mesa structures, each mesa structure including sidewalls and a top surface;   an array of electrodes, each electrode formed on the top surface of a mesa structure;   an array of vias through the array of mesa structures, each via connecting an electrode to an electrode lead; and   a dielectric layer covering the array of mesa structures and the array of electrodes.   
     
     
         2 . The micro device transfer head array of  claim 1 , wherein the array of electrodes does not span the sidewalls of the array of mesa structures. 
     
     
         3 . The micro device transfer head array of  claim 1 , wherein each electrode comprises a material selected from the group consisting of platinum, titanium, vanadium, chromium, zirconium, niobium, molybdenum, ruthenium, rhodium, hafnium, tantalum, tungsten, rhenium, osmium, iridium and alloys thereof. 
     
     
         4 . The micro device transfer head array of  claim 1 , wherein each electrode comprises TiW. 
     
     
         5 . The micro device transfer head array of  claim 1 , wherein the dielectric layer comprises a dielectric material selected from the group consisting of silicon oxide, aluminum oxide, and tantalum oxide. 
     
     
         6 . The micro device transfer head array of  claim 1 , wherein the dielectric layer is 0.5 µm - 2.0 µm thick. 
     
     
         7 . The micro device transfer head array of  claim 1 , wherein each mesa structure top surface has rectangular x-y dimensions. 
     
     
         8 . The micro device transfer head array of  claim 7 , wherein each mesa structure top surface has square x-y dimensions. 
     
     
         9 . The micro device transfer head array of  claim 1 , wherein each mesa structure has x-y dimensions, each x dimension and y dimension of 1 to 100 µm. 
     
     
         10 . The micro device transfer head array of  claim 1 , wherein the base substrate and the array of mesa structures each comprise silicon. 
     
     
         11 . The micro device transfer head array of  claim 1 , further comprising a second array of second electrodes, each second electrode formed on the top surface of a corresponding mesa structure, wherein the dielectric layer covers the second electrode for each mesa structure. 
     
     
         12 . The micro device transfer head array of  claim 11 , further comprising an array of second vias through the array of mesa structures, each second via connecting a second electrode to a second electrode lead. 
     
     
         13 . The micro device transfer head array of  claim 12 , wherein the array of electrodes and the second array of second electrodes do not span the sidewalls of the array of mesa structures. 
     
     
         14 . The micro device transfer head array of  claim 13 , wherein the dielectric layer comprises a dielectric material selected from the group consisting of silicon oxide, aluminum oxide, and tantalum oxide. 
     
     
         15 . The micro device transfer head array of  claim 13 , wherein the dielectric layer is 0.5 µm -2.0 µm thick. 
     
     
         16 . The micro device transfer head array of  claim 13 , wherein each mesa structure top surface has rectangular x-y dimensions. 
     
     
         17 . The micro device transfer head array of  claim 16 , wherein each mesa structure top surface has square x-y dimensions. 
     
     
         18 . The micro device transfer head array of  claim 13 , wherein each mesa structure has x-y dimensions, each x dimension and y dimension of 1 to 100 µm. 
     
     
         19 . The micro device transfer head array of  claim 13 , wherein the base substrate and the array of mesa structures each comprise silicon. 
     
     
         20 . The micro device transfer head array of  claim 13 , wherein each electrode and each second electrode comprises a material selected from the group consisting of platinum, titanium, vanadium, chromium, zirconium, niobium, molybdenum, ruthenium, rhodium, hafnium, tantalum, tungsten, rhenium, osmium, iridium and alloys thereof.