Method of increasing capacitance by surface roughening in semiconductor wafer processing

Abstract

A method of increasing capacitance by surface roughening in semiconductor wafer processing includes the following steps: a) applying a first layer of material atop a substrate thereby defining an exposed surface; b) incontinuously adhering discrete solid particles to the first layer exposed surface to roughen the exposed surface; and c) applying a second layer of material atop the first layer and adhered solid particles to define an outer surface, the particles adhered to the first layer reducing roughness into the outer surface thereby increasing its surface area and accordingly capacitance of the second layer in the final wafer structure.

We claim: 
     
       1. A method of increasing capacitance by surface roughening in semiconductor wafer processing comprising the following steps: applying a first layer of material atop a substrate thereby defining an exposed surface;   incontinuously adhering discrete solid particles to the first layer exposed surface to roughen the exposed surface; and   applying a second layer of material atop the first layer and the adhered discrete solid particles to define an outer surface, the discrete solid particles adhered to the first layer inducing roughness into the outer surface thereby increasing its surface area and accordingly capacitance of the second layer in a final wafer structure.   
     
     
       2. The method of increasing capacitance by surface roughening of claim 1 wherein the discrete solid particles have an average diameter ranging from 30 Angstroms to 3,000 Angstroms. 
     
     
       3. The method of increasing capacitance by surface roughening of claim 1 wherein the discrete solid particles are of a material selected from the group consisting of SiO 2  and Al 2  O 3 . 
     
     
       4. The method of increasing capacitance by surface roughening of claim 1 wherein, the discrete solid particles have an average diameter ranging from 30 Angstroms to 3,000 Angstroms; and the discrete solid particles are of a material selected from the group consisting of SiO 2  and Al 2  O 3 .   
     
     
       5. The method of increasing capacitance by surface roughening of claim 1 further comprising etching the first layer having the adhered discrete solid particles with an etch chemistry that etches the first layer material but is selective to the adhered discrete solid particles to roughen the exposed first layer area not covered by the adhered discrete solid particles. 
     
     
       6. The method of increasing capacitance by surface roughening of claim 5 wherein the discrete solid particles have an average diameter ranging from 30 Angstroms to 3,000 Angstroms. 
     
     
       7. The method of increasing capacitance by surface roughening of claim 5 wherein the discrete solid particles are of a material selected from the group consisting of SiO 2  and Al 2  O 3 . 
     
     
       8. The method of increasing capacitance by surface roughening of claim 1 wherein the step of adhering the discrete solid particles comprises dipping the substrate into a slurry of a solution containing the discrete solid particles suspended therein, removing the substrate from the slurry with the discrete solid particles adhering to the first layer, and rinsing remaining solution from the wafer. 
     
     
       9. The method of increasing capacitance by surface roughening of claim 8 wherein the discrete solid particles have an average diameter ranging from 30 Angstroms to 3,000 Angstroms. 
     
     
       10. The method of increasing capacitance by surface roughening of claim 8 wherein the discrete solid particles are of a material selected from the group consisting of SiO 2  and Al 2  O 3 . 
     
     
       11. The method of increasing capacitance by surface roughening of claim 8 further comprising etching the first layer having the adhered discrete solid particles with an etch chemistry that etches the first layer material but is selective to the adhered discrete solid particles to roughen the exposed first layer area not covered by the adhered discrete solid particles. 
     
     
       12. The method of increasing capacitance by surface roughening of claim 1 wherein, the step of adhering the discrete solid particles comprises dipping the substrate into a slurry of a solution containing the discrete solid particles suspended therein, removing the substrate from the slurry with the discrete solid particles adhering to the first layer, and rinsing remaining solution from the wafer; and   the slurry solution being comprised of a chemistry that chemically etches the exposed first layer material during the dipping step to further roughen the exposed surface.   
     
     
       13. The method of increasing capacitance by surface roughening of claim 12 wherein the discrete solid particles have an average diameter ranging from 30 Angstroms to 3,000 Angstroms. 
     
     
       14. The method of increasing capacitance by surface roughening of claim 12 wherein the discrete solid particles are of a material selected from the group consisting of SiO 2  and Al 2  O 3 . 
     
     
       15. The method of increasing capacitance by surface roughening of claim 12 further comprising an additional step of etching the first layer having the adhered discrete solid particles with an etch chemistry that etches the first layer material but is selective to the adhered discrete solid particles to roughen the exposed first layer area not covered by the adhered discrete solid particles. 
     
     
       16. The method of increasing capacitance by surface roughening of claim 15 wherein the discrete solid particles have an average diameter ranging from 30 Angstroms to 3,000 Angstroms. 
     
     
       17. The method of increasing capacitance by surface roughening of claim 15 wherein the discrete solid particles are of a material selected from the group consisting of SiO 2  and Al 2  O 3 . 
     
     
       18. A method of forming a capacitor in semiconductor wafer processing comprising the following steps: providing a layer of insulating dielectric atop a partially processed semiconductor wafer;   etching a contact opening in the dielectric layer which aligns with an active area beneath the dielectric layer;   applying a first layer of polysilicon to a thickness of from about 100 to 2,000 Angstroms atop the etched dielectric layer thereby defining an exposed surface of polysilicon, the polysilicon making contact with the active area;   incontinuously adhering discrete solid particles to the polysilicon exposed surface to roughen the exposed surface;   applying a second layer of polysilicon to a thickness of from about 300 to 2000 Angstroms atop the first polysilicon layer and adhered discrete solid particles to provide a lower capacitor plate having an outer surface, the discrete solid particles adhered to the first polysilicon layer inducing roughness into the outer surface thereby increasing its surface area and accordingly capacitance of the lower capacitor plate in a final wafer structure;   applying a layer of capacitor dielectric atop the outer surface, the roughness of the outer surface at least in part being transferred to the capacitor dielectric layer; and   applying a third layer of polysilicon atop the capacitor dielectric layer, the roughness of the capacitor dielectric layer at least in part being transferred to the third layer of polysilicon.   
     
     
       19. The method of forming a capacitor of claim 18 wherein the discrete solid particles have an average diameter ranging from 30 Angstroms to 3,000 Angstroms. 
     
     
       20. The method of forming a capacitor of claim 18 wherein the discrete solid particles are of a material selected from the group consisting of SiO 2  and Al 2  O 3 . 
     
     
       21. The method of increasing capacitance by surface roughening of claim 18 further comprising etching the first layer having the adhered discrete solid particles with an etch chemistry that etches the first layer material but is selective to the adhered discrete solid particles to roughen the exposed first layer area not covered by the adhered discrete solid particles. 
     
     
       22. The method of forming a capacitor of claim 21 wherein the discrete solid particles have an average diameter ranging from 30 Angstroms to 3,000 Angstroms. 
     
     
       23. The method of forming a capacitor of claim 21 wherein the discrete solid particles are of a material selected from the group consisting of SiO 2  and Al 2  O 3 . 
     
     
       24. The method of increasing capacitance by surface roughening of claim 18 wherein the step of adhering the discrete solid particles comprises dipping the substrate into a slurry of a solution containing the discrete solid particles suspended therein, removing the substrate from the slurry with the discrete seolid particles adhering to the first layer, and rinsing remaining solution from the wafer. 
     
     
       25. The method of forming a capacitor of claim 24 wherein the discrete solid particles have an average diameter ranging from 30 Angstroms to 3,000 Angstroms. 
     
     
       26. The method of forming a capacitor of claim 24 wherein the discrete solid particles are of a material selected from the group consisting of SiO 2  and Al 2  O 3 . 
     
     
       27. The method of increasing capacitance by surface roughening of claim 24 further comprising etching the first layer having the adhered discrete solid particles with an etch chemistry that etches the first layer material but is selective to the adhered discrete solid particles to roughen the exposed first layer area not covered by the adhered discrete solid particles. 
     
     
       28. The method of forming a capacitor of claim 18 wherein, the step of adhering the discrete solid particles comprises dipping the substrate into a slurry of a solution containing the discrete solid particles suspended therein, removing the substrate from the slurry with the discrete solid particles adhering to the first layer, and rinsing remaining solution from the wafer; and   the slurry solution being comprised of a chemistry that chemically etches polysilicon during the dipping step to further roughen the exposed surface.   
     
     
       29. The method of forming a capacitor of claim 28 wherein the discrete solid particles have an average diameter ranging from 30 Angstroms to 3,000 Angstroms. 
     
     
       30. The method of forming a capacitor of claim 28 wherein the discrete solid particles are of a material selected from the group consisting of SiO 2  and Al 2  O 3 . 
     
     
       31. The method of increasing capacitance by surface roughening of claim 28 further comprising an additional step of etching the first layer having the adhered discrete solid particles with an etch chemistry that etches the first layer material but is selective to the adhered discrete solid particles to roughen the exposed first layer area not covered by the adhered discrete solid particles. 
     
     
       32. The method of forming a capacitor of claim 31 wherein the discrete solid particles have an average diameter ranging from 30 Angstroms to 3,000 Angstroms. 
     
     
       33. The method of forming a capacitor of claim 31 wherein the discrete solid particles are of a material selected from the group consisting of SiO 2  and Al 2  O 3 . 
     
     
       34. A method of increasing capacitance by surface roughening in semiconductor wafer processing comprising the following steps: applying a first layer of material atop a substrate thereby defining an exposed surface;   incontinuously adhering discrete solid particles to the first layer exposed surface, such step of adhering the discrete solid particles comprising dipping the substrate into a slurry of a solution containing the discrete solid particles suspended therein, removing the substrate from the slurry with the discrete solid particles adhering to the first layer, and rinsing remaining solution from the wafer; and   etching the first layer having the adhered discrete solid particles with an etch chemistry that etches the first layer material but is selective to the adhered discrete solid particles to etch into and roughen the exposed first layer area not covered by the adhered discrete solid particles.   
     
     
       35. The method of increasing capacitance by surface roughening of claim 34 whereto the slurry solution is comprised of a chemistry that chemically etches the exposed first layer material during dipping to further roughen the exposed surface. 
     
     
       36. A method of increasing capacitance by surface roughening in semiconductor wafer processing comprising the following steps: applying a first layer of material atop a substrate thereby defining an exposed surface;   incontinuously adhering discrete solid particles to the first layer exposed surface, such particles comprising SiO 2  ; and   etching the first layer having the adhered discrete solid particles with an etch chemistry that etches the first layer material but is selective to the adhered discrete solid particles to etch into and roughen the exposed first layer area not covered by the adhered discrete solid particles.   
     
     
       37. A method of increasing capacitance by surface roughening in semiconductor wafer processing comprising the following steps: applying a first layer of material atop a substrate thereby defining an exposed surface;   incontinuously adhering discrete solid particles to the first layer exposed surface, such particles comprising Al 2  O 3  ; and   etching the first layer having the adhered discrete solid particles with an etch chemistry that etches the first layer material but is selective to the adhered discrete solid particles to etch into and roughen the exposed first layer area not covered by the adhered discrete solid particles.