Method for producing a dielectric layer on a component
A method for producing a dielectric layer on the surface of a component is described. In particular embodiments, a dielectric layer having a planar surface can be generated over a substrate topography having raised structures. In a trimming process, a component property, which depends on the thickness or the third topography of the dielectric layer, is adjusted.
1. A method for producing a dielectric layer on a surface of a component, the surface having a first topography with elevated structures, the method comprising:
forming a dielectric layer over the structures over an entire area of the first topography, such that the surface of the dielectric layer has a second topography, wherein forming the dielectric layer comprises forming a silicon dioxide layer, wherein the component comprises a piezoelectric layer on a substrate or a piezoelectric substrate and also comprises an electrode structure disposed above a surface of the substrate that forms the first topography, the electrode structure is configured to excite acoustic waves in the component, wherein the dielectric layer is in direct contact with the structures and encapsulates all exposed surfaces of all the structures across the substrate,
forming a polymer layer having a planar surface over the dielectric layer over the entire area,
performing an etching method, wherein a desired etching rate ratio of dielectric layer to resist layer is set,
continuing the etching method until a surface of the dielectric layer has a desired third topography after complete removal of the resist layer;
forming a trimming layer having a higher stiffness than a stiffness of the dielectric layer, the trimming layer formed on the dielectric layer over the third topography; and
reducing a thickness of the trimming layer until a predefined center frequency of the combined dielectric layer and trimming layer is attained.
2. The method according to claim 1 , wherein forming the dielectric layer comprises performing a deposition process.
3. The method according to claim 1 , wherein a temperature dependence of a frequency of the component is reduced with the dielectric layer.
4. The method according to claim 1 ,
wherein all of the method steps are carried out on a wafer on which electrode structures of a plurality of components are arranged,
wherein a center frequency of individual components is determined at a method stage between producing the third topography and etching back the trimming layer, wherein the center frequency of individual components is determined from selected measurements by interpolation,
wherein a distribution of deviations from a desired center frequency is determined, and
wherein the thickness of the trimming layer is reduced location-selectively in a manner dependent on the deviation determined at a respective location, such that the deviations are leveled and the center frequencies of all of the components are set to a desired value within a tolerance.
5. The method according to claim 1 , wherein the trimming layer comprises a layer comprising a material selected from the group consisting of silicon nitride, silicon oxynitride, aluminum oxide, diamond like carbon and diamond.
6. The method according to claim 4 , wherein a thickness of the trimming layer is reduced by a scanning action of an ion beam on the surface of the trimming layer.
7. The method according to claim 6 , wherein a desired change in the center frequency at a specific location is effected by a corresponding exposure time relative to the ion beam at this specific location, wherein the exposure time is set by way of a respective speed at which the wafer is guided past below the ion beam at the respective specific location.
8. The method according to claim 1 , wherein the etching rate ratio is set to a value of about 1.
9. The method according to claim 1 , wherein a substantially planar surface of a remaining dielectric layer is obtained as second topography.
10. The method according to claim 1 , wherein the etching rate ratio is set to a value of greater than 1.
11. The method according to claim 10 , wherein a remaining dielectric layer obtains a second topography which is the inverse of the first topography and which has depressions above the elevated structures of the first topography.
12. The method according to claim 1 , wherein the etching rate ratio is set to a value of less than 1.
13. The method according to claim 12 , wherein the structures of the second topography are partly leveled.