Shader shadow anti-aliasing problem

If i write a shader code for a sprite as below, the edges of the shadow appear as dots. Setting the Shadow option of Directional Light and QualitySettings does not show any change. I think there is a problem with the shader code, what should I do? To briefly describe the code below, i put shadows in the sprite, turn off lighting to prevent lighting from affecting the color, and display the color with Emission.

Shader "Custom/Sprites/Shadow"
		[PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
		_Color ("Color", Color) = (1,1,1,1)
		_Cutoff ("Shadow alpha cutoff", Range(0, 1)) = 0.5

			"Queue"				= "Transparent" 
			"RenderType"		= "Transparent" 
			"IgnoreProjector"	= "True" 
			"PreviewType"		= "Plane"
			"CanUseSpriteAtlas"	= "True"

		Cull Off
		Lighting Off
		ZWrite Off
		Blend One OneMinusSrcAlpha

		#pragma vertex vert
		#pragma surface surf Lambert alpha addshadow

		sampler2D _MainTex;
		fixed4 _Color;

		struct Input
			float2 uv_MainTex;
			fixed4 color;
		void vert (inout appdata_full v, out Input o)
			o.color = _Color;

		void surf (Input IN, inout SurfaceOutput o)
			fixed4 c	= tex2D (_MainTex, IN.uv_MainTex) * IN.color;
			o.Emission	= c.rgb;
			o.Alpha		= c.a;

	Fallback "Transparent/Cutout/VertexLit"


There’s no problem with the shader. It’s using bilinear filtering to determine which points are transparent enough to cast a shadow. The pixellated nature of the target is causing the uneven edges.

If you want to remove those artifacts, increase the source resolution of the circle image.