Hermetically sealed package with window

Abstract

A method for manufacturing a cover assembly including a transparent window portion and a frame of gas-impervious material that can be hermetically attached to a micro-device package base to form a hermetically sealed micro-device package. First a frame of gas-impervious material is provided the frame having a continuous sidewall defining a frame aperture there through. The sidewall includes a frame seal-ring area circumscribing the frame aperture. A sheet of a transparent material is also provided, the sheet having a window portion defined thereupon. The window portion has finished top and bottom surfaces. A sheet seal-ring area is prepared on the sheet, the sheet seal-ring area circumscribing the window portion. The frame is positioned against the sheet such that at least a portion of the frame seal-ring area and at least a portion of the sheet seal-ring area contact one another along a continuous junction region that circumscribes the window portion. The frame is pressed against the sheet with sufficient force to produce a predetermined contact pressure between the frame seal-ring area and the sheet seal-ring area along the junction region. The junction region is heated to produce a predetermined temperature along the junction region. The predetermined contact pressure and the predetermined temperature are maintained until a diffusion bond is formed between the frame and sheet all along the junction region.

1 . A method for manufacturing a cover assembly that can be hermetically attached to a base to form a unit having a hermetically sealed interior cavity, the cover assembly including a transparent window portion and a frame, the method comprising the following steps:
 providing a frame of gas-impervious metallic material having a continuous sidewall defining a frame aperture therethrough;   providing a sheet of a transparent material having a window portion defined thereupon;   positioning the frame against the sheet such that at least a portion of the frame and at least a portion of the sheet contact one another along a junction region that circumscribes the portion of the window portion that is aligned with the frame aperture;   pressing the frame against the sheet with sufficient force to produce a predetermined contact pressure between contacting portions of the frame and the sheet;   heating the contacting portions of the frame and sheet to produce a predetermined temperature therein; and   maintaining the predetermined contact pressure and the predetermined temperature until a material originally in one of the frame and the sheet diffuses into the other of the frame and the sheet creating a hermetically sealed diffusion bond between the frame and the sheet.   
     
     
         2 . A method in accordance with  claim 1 , wherein the step of pressing the frame is performed before the step of heating the contacting portions. 
     
     
         3 . A method in accordance with  claim 1 , wherein the step of heating the contacting portions is performed before the step of pressing the frame. 
     
     
         4 . A method in accordance with  claim 1 , wherein the steps of pressing the frame and of heating the contacting portions are performed simultaneously. 
     
     
         5 . A method in accordance with  claim 1 , wherein the transparent material of the sheet is a glass. 
     
     
         6 . A cover assembly that can be hermetically sealed to a base to form a hermetically sealed unit having an interior cavity, the cover assembly including:
 a frame of gas-impervious material having a continuous sidewall defining a frame aperture therethrough;   a sheet of a transparent material having a window portion defined thereupon, the sheet being hermetically bonded to the frame by positioning the frame against the sheet such that at least a portion of the frame and at least a portion of the sheet contact one another along a function region that circumscribes the portion of the window portion that is aligned with the frame aperture; pressing the frame against the sheet with sufficient force to produce a predetermined contact pressure between contacting portions of the frame and the sheet; heating the contacting portions of the frame and sheet to produce a predetermined temperature therein; and maintaining the predetermined contact pressure and the predetermined temperature until a hermetically sealed diffusion bond is formed between the frame and the sheet; and   wherein the cover assembly includes a region at the junction of the frame and the sheet exhibiting diffusion of a material originally in one of the frame and the sheet into the other of the frame and the sheet.   
     
     
         7 . A cover assembly in accordance with  claim 6 , wherein the pressing of the frame is performed before the heating of the contacting portions. 
     
     
         8 . A cover assembly in accordance with  claim 6 , wherein the heating of the contacting portions is performed before the pressing of the frame. 
     
     
         9 . A cover assembly in accordance with  claim 6 , wherein the pressing of the frame and the heating of the contacting portions are performed simultaneously. 
     
     
         10 . A cover assembly in accordance with  claim 6 , wherein the transparent material of the sheet is a glass. 
     
     
         11 . A cover assembly in accordance with  claim 6 , wherein during the heating of the contacting portions, the temperature of the window portion of the sheet remains below the glass transition temperature (T.sub.G) of the transparent material. 
     
     
         12 . A hermetically sealed unit including:
 a base;   a device mounted on the base; and   a cover assembly hermetically sealed to the base so as to encapsulate the device in a hermetically sealed cavity formed therebetween, the cover assembly including a frame of gas-impervious material having a continuous sidewall defining a frame aperture therethrough, a sheet of a transparent material having a window portion defined thereupon, the sheet being hermetically bonded to the frame by positioning the frame against the sheet such that at least a portion of the frame and at least a portion of the sheet contact one another along a junction region that circumscribes the portion of the window portion that is aligned with the frame aperture, pressing the frame against the sheet with sufficient force to produce a predetermined contact pressure between contacting portions of the frame and the sheet, heating the contacting portions of the frame and sheet to produce a predetermined temperature therein, and maintaining the predetermined contact pressure and the predetermined temperature until a hermetically sealed diffusion bond is formed between the frame and the sheet;   wherein the cover assembly includes a region at the junction of the frame and the sheet exhibiting diffusion of a material originally in one of the frame and the sheet into the other of the frame and the sheet.   
     
     
         13 . A hermetically sealed unit in accordance with  claim 12 , wherein the base is formed of a transparent material. 
     
     
         14 . A hermetically sealed unit in accordance with  claim 13 , wherein the device is an active device. 
     
     
         15 . A hermetically sealed unit in accordance with  claim 13 , wherein the device is a passive device. 
     
     
         16 . A hermetically sealed unit in accordance with  claim 15 , wherein the passive device has a height equal to the spacing between the sheet and the base. 
     
     
         17 . A hermetically sealed unit in accordance with  claim 15 , wherein the passive device affects the passage of visible light through the unit. 
     
     
         18 . A hermetically sealed unit in accordance with  claim 15 , wherein the passive device does not affect the passage of visible light through the unit.