Manufacturing process of integrated semiconductor light sensor device

Abstract

A process for manufacturing a light sensor device in a standard CMOS process, including at least the following phases: implanting active areas on a semiconductor substrate to obtain at least a first, a second and a third integrated region of corresponding photosensors; forming a stack of layers of different thickness and refractive index layers over the photosensors to provide an interferential filter to said photosensors. The stack is obtained by a deposition of a first oxide stack including a first, a second and a third oxide layer over at least one photosensor; moreover, this third oxide layer is obtained by a deposition step of an protecting undoped premetal dielectric layer.

1 . A process for manufacturing a light sensor device by a standard CMOS process, comprising: 
 implanting active areas on a semiconductor substrate to obtain at least a first, a second, and a third integrated region of corresponding photosensors;    forming a stack of layers having different thickness and refractive index over said photosensors to provide an interferential filter for said photosensors; said stack of layers having different thickness and refractive index is obtained by a deposition of a first oxide stack including at least a first, a second and a third oxide layer over at least one photosensor, said third oxide layer being obtained by a deposition step of a protecting premetal dielectric layer.    
     
     
         2 . The process of  claim 1 , wherein said premetal dielectric layer is undoped.  
     
     
         3 . The process of  claim 1 , wherein said premetal dielectric layer is a conformal USG.  
     
     
         4 . The process of  claim 1 , wherein said stack of oxide layers has a thickness of about 1500 Å (150 nm).  
     
     
         5 . The process of  claim 1 , wherein said third oxide layer is not etched between two adjacent photosensors.  
     
     
         6 . The process of  claim 1 , wherein said third oxide layer brings the total thickness of the oxide stacks to a value multiple of L/2, wherein L is a given wavelength of the incident light that is wanted to be transmitted to the sensor.  
     
     
         7 . The process of  claim 1 , wherein a thin conductive layer is deposited over said third oxide layer.  
     
     
         8 . The process of  claim 6 , wherein said thin conductive layer is polysilicon.  
     
     
         9 . The process of  claim 6 , wherein a further deposition step of a silicon nitride layer is provided over said thin conductive layer.  
     
     
         10 . The process of  claim 9 , wherein a final planarization step is performed by a deposition of a single planarizing metal dielectric layer.  
     
     
         11 . The process of  claim 10 , wherein said single planarizing metal dielectric layer is BPSG.  
     
     
         12 . A light sensor device obtained by a standard CMOS process, comprising: 
 a first, a second and a third integrated region on a semiconductor substrate for corresponding photosensors;    a stack of layers having different thickness and refractive index over said photosensors to provide an interferential filter for said photosensors, said stack of layers comprises at least a first oxide stack including a first, a second and a third oxide layer over at least one photosensor, said third oxide layer being an protecting premetal dielectric layer.    
     
     
         13 . A process for manufacturing a light sensor device, comprising: 
 implanting active areas on a semiconductor substrate to obtain at least a first, a second, and a third integrated region of corresponding photosensors; and    forming a stack of layers having different thicknesses and refractive index over said photosensors to provide an inferential filter for said photosensors by depositing a first oxide stack including at least a first, a second, and a third oxide layer over at least one photosensor, said third oxide layer being obtained by a deposition step of a protecting premetal dielectric layer.    
     
     
         14 . An integrated light sensor device, comprising: 
 a first integrated photosensor region, a second integrated photosensor region, and a third integrated photosensor region implanted on a semiconductor substrate; and    a stack of layers having different thicknesses and refractive index formed over said first, second and third integrated photosensor regions to provide an inferential filter, said stack of layers formed by a first oxide stack including at least a first, a second, and a third oxide layer, the third oxide layer formed by a deposition step of a protecting premetal dielectric layer.