How to smoothen/sharpen edges while using alphatest

I am using a masking shader on which I have used alphatest to cutout solid colors.. But the Edges are crooked and pixelated.. I want the edges to be sharp and smooth.. Any work around would be helpful and greatly appreciated..

I am using this

 Shader "Masked/MaskedTexture" {
    Properties { 
       _Mask ("Culling Mask", 2D) = "white" {} 
    } 
 
     SubShader { 
         Tags {"Queue" = "Geometry-1" "RenderType"="Transparent"}
         Alphatest Greater 0.95
         ZWrite Off ColorMask RGB
         ZWrite On
         Pass{
             Blend  OneMinusSrcAlpha SrcAlpha 
             SetTexture [_Mask]
         }
     } 
 }