US2021280726A1PendingUtilityA1

Spacer formation in a solar cell using oxygen ion implantation

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Assignee: SUNPOWER CORPPriority: Sep 28, 2012Filed: May 25, 2021Published: Sep 9, 2021
Est. expirySep 28, 2032(~6.2 yrs left)· nominal 20-yr term from priority
Inventors:Seung Bum RimDavid D. Smith
H10F 77/703H10F 77/219H10F 71/121H10F 10/146H10F 77/14Y02P70/50Y02E10/547Y02E10/52Y02E10/546H01L 31/0682H01L 31/022441H01L 31/02363H01L 31/1804H01L 31/035272
69
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Claims

Abstract

A solar cell is disclosed. The solar cell has a front side facing the sun during normal operation, and a back side facing away from the sun. The solar cell comprises a silicon substrate, a first polysilicon layer with a region of doped polysilicon on the back side of the substrate. The solar cell also comprises a second polysilicon layer with a second region of doped polysilicon on the back side of the silicon substrate. The second polysilicon layer at least partially covers the region of doped polysilicon. The solar cell also comprises a resistive region disposed in the first polysilicon layer. The resistive region extends from an edge of the second region of doped polysilicon. The resistive region can be formed by ion implantation of oxygen into the first polysilicon layer.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
         1 . A solar cell comprising:
 a solar cell substrate having a front side and a back side opposite the front side, wherein the front side faces the sun during normal operation;   a polysilicon layer disposed over the back side of the solar cell substrate;   a P-type diffusion region disposed in the polysilicon layer;   an N-type diffusion region disposed in the polysilicon layer;   a separation region disposed in the polysilicon layer between the P-type diffusion region and the N-type diffusion region, the separation region having higher resistivity than either the P-type diffusion region or the N-type diffusion region, the separation region extending from a side of the P-type diffusion region to a side of the N-type diffusion region;   a first metal grid disposed over the polysilicon layer and is electrically connected to the P-type diffusion region; and   a second metal grid disposed over the polysilicon layer and is electrically connected to the N-type diffusion region.   
     
     
         2 . The solar cell of  claim 1 , further comprising:
 a first dielectric layer disposed between the polysilicon layer and the back side of the solar cell substrate, wherein the polysilicon layer is continuous.   
     
     
         3 . The solar cell of  claim 2 , wherein the first dielectric layer comprises silicon dioxide. 
     
     
         4 . The solar cell of  claim 3 , wherein the solar cell substrate comprises silicon. 
     
     
         5 . The solar cell of  claim 1 , further comprising a second dielectric layer disposed over the polysilicon layer. 
     
     
         6 . The solar cell of  claim 5 , wherein the second dielectric layer comprises silicon nitride. 
     
     
         7 . The solar cell of  claim 5 , further comprising:
 a first metal plug disposed in a contact hole in the second dielectric layer,   wherein the first metal grid is electrically connected to the P-type diffusion region by way of the first metal plug.   
     
     
         8 . The solar cell of  claim 7 , wherein the first metal plug comprises aluminum. 
     
     
         9 . A solar cell comprising:
 a solar cell substrate having a front side and a back side opposite the front side, wherein the front side faces the sun during normal operation;   a polysilicon layer disposed over the back side of the solar cell substrate;   a P-type diffusion region disposed in the polysilicon layer;   an N-type diffusion region disposed in the polysilicon layer;   a separation region disposed in the polysilicon layer between the P-type diffusion region and the N-type diffusion region, the separation region having higher resistivity than either the P-type diffusion region or the N-type diffusion region, the separation region extending from a side of the P-type diffusion region to a side of the N-type diffusion region;   a trench structure formed over the separation region and disposed between the P-type diffusion region and the N-type diffusion region;   a first contact plug that is electrically connected to the P-type diffusion region; and   a second contact plug that is electrically connected to the N-type diffusion region.   
     
     
         10 . The solar cell of  claim 9 , further comprising:
 a first metal finger that is electrically connected to the first contact plug; and   a second metal finger that is electrically connected to the second contact plug.   
     
     
         11 . The solar cell of  claim 9 , wherein the first and second metal contact fingers are interdigitated. 
     
     
         12 . The solar cell of  claim 9 , further comprising:
 an antireflective coating disposed over the trench structure.   
     
     
         13 . The solar cell of  claim 9 , further comprising:
 a dielectric layer disposed between the polysilicon layer and the solar cell substrate.   
     
     
         14 . The solar cell of  claim 9 , wherein the trench structure is textured. 
     
     
         15 . The solar cell of  claim 9 , further comprising:
 an oxide layer over the front side of the solar cell substrate.   
     
     
         16 . The solar cell of  claim 15 , further comprising:
 an antireflective coating over the oxide layer.   
     
     
         17 . A solar cell comprising:
 a solar cell substrate having a front side and a back side opposite the front side, wherein the front side faces the sun during normal operation;   a polysilicon layer disposed over the back side of the solar cell substrate;   a P-type diffusion region disposed in the polysilicon layer;   an N-type diffusion region disposed in the polysilicon layer;   a separation region disposed in the polysilicon layer between the P-type diffusion region and the N-type diffusion region, the separation region having higher resistivity than either the P-type diffusion region or the N-type diffusion region, the separation region extending from a side of the P-type diffusion region to a side of the N-type diffusion region;   a first metal grid disposed over the polysilicon layer and is electrically connected to the P-type diffusion region;   a second metal grid disposed over the polysilicon layer and is electrically connected to the N-type diffusion region;   a front side diffusion region disposed on the front side of the solar cell substrate; and   an oxide layer disposed over the front side diffusion region.   
     
     
         18 . The solar cell of  claim 17 , wherein the front side of the solar cell substrate is textured. 
     
     
         19 . The solar cell of  claim 17 , further comprising:
 an antireflective coating over the oxide layer.   
     
     
         20 . The solar cell of  claim 17 , further comprising:
 a trench structure formed over the separation region.

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