Repeatable end point method for anisotropic etch of inorganic buried anti-reflective coating layer over silicon
First Claim
1. The process of etching a first and second layer on a multilayer self aligned gate structure on a suitable substrate through a patterned resist layer which will have a repeatable end point and reduced etch end point time which process comprises:
- etching said layers with a gas flow mixture of chlorine (Cl2) and carbon tetrafluoride (CF4) and helium (He) gases into a plasma reactive etching chamber containing said gate structure;
detecting the etch endpoint of said first layer;
etching said second layer of said gate structure with the same gas mixture;
detecting the endpoint of said second layer etch;
performing a 100% over etch to assure no residue of said layers remains;
completing the etching and fabrication of said gate structure.
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Abstract
A method for anisotropically etching a partially manufactured semiconductor structure, more specifically, a stacked FET gate structure containing a bottom anti-reflective coating (Barc) layer is described. The structure is covered with a photoresist layer which is patterned to defines the gate region. The processing chemistry is predominantly carbon tetrafluoride, (CF4) with the inclusion of chlorine (Cl2) where fluorine (F) is generated in the plasma as the etchant for the structure. During processing, the wafer is cooled with helium (He) that lowers the wafer temperature and promotes sidewall deposition from the fluorine species which acts as a passivation layer producing a anisotropic or vertical etch profile. The process reduces etch time and results in very repeatable end point control of the Bark etch and poly cap etch improving the control of the structure critical dimensions and improving process throughput. The reduction in the use of fluorine based species reduces any potential environmental impact.
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Citations
31 Claims
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1. The process of etching a first and second layer on a multilayer self aligned gate structure on a suitable substrate through a patterned resist layer which will have a repeatable end point and reduced etch end point time which process comprises:
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etching said layers with a gas flow mixture of chlorine (Cl2) and carbon tetrafluoride (CF4) and helium (He) gases into a plasma reactive etching chamber containing said gate structure;
detecting the etch endpoint of said first layer;
etching said second layer of said gate structure with the same gas mixture;
detecting the endpoint of said second layer etch;
performing a 100% over etch to assure no residue of said layers remains;
completing the etching and fabrication of said gate structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. The process of etching a SAG gate structure from a multilayer structure patterned with photoresist on top of a first layer consisting of a Barc material, and a second layer consisting of polysilicon cap, which said process minimizes or eliminates the undercutting of the polysilicon layer and minimizes Barc etch time which process consists of:
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etching said first layer with a gas flow mixture of chlorine (Cl2) and carbon tetrafluoride (CF4) and helium (He) gases into a plasma reactive etching chamber containing said gate structure;
detecting the etch endpoint of said first layer;
etching said second layer of said gate structure with the same gas mixture;
passivating a sidewall with a polymer coating created by the fluorine based species while cooling the structure with He providing an anisotropic etch profile;
detecting the endpoint of said second layer etch;
performing an 100% over etch to assure no residue of said layers remains;
completing the etching and fabrication of said gate structure. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. The process of etching a SAG gate from a multilayer structure containing a top first Barc layer followed by tungsten silicide, polysilicon and gate oxide layers which process minimizes the variation in structure critical as well as dimensions as well as preserving the proper integrity of the multilayer elements by producing a well controlled Barc etch which process consists of:
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etching said first Barc layer with a gas flow mixture of chlorine (Cl2) and carbon tetrafluoride (CF4) and helium (He) gases into a plasma etching chamber containing said gate structure;
detecting the etch endpoint of said first Barc layer;
cooling said gate structure with He to enable sidewall passivation from polymer created by said fluorine species during etching providing an anisotropic etch profile;
performing an 100% over etch to assure no residue of said first layer remains;
completing the etching and fabrication of said gate structure. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification