Spawn object near the moving camera

Hi, i need to spawn an object every second as child of my camera, and the object must spwan on this relatives coordinates: x = 0, y = 5, z = 0 then it can be free from scripts so the camera can move over it.

This is the (partial) code. It works, but the script force to stay the cube at y = 5 instead of makes the cube free from scripts.

I tried to make an image to explain this, but i don't know if this is a good image :S

Sorry for my bad english but this is my main language

 using UnityEngine;
 using System.Collections;
 
 public class Game : MonoBehaviour {
     public float speed = 5;
     public GameObject cubo;
     bool cubbbo = false;
     public Vector3 posizionea;
     public Vector3 posizioneb;
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
         transform.Translate(speed * 0f, Time.deltaTime*20, 0f);
         StartCoroutine(Spawncubo());
     }
 
     IEnumerator Spawncubo()
     {
         if (cubbbo == false)
         {
             cubbbo = true;
             while (true)
             {
                 yield return new WaitForSeconds(1);
                GameObject clone = Instantiate(cubo) as GameObject;
                clone.transform.parent = this.transform;
                clone.transform.localPosition = Vector3.Lerp(posizionea, posizioneb, Time.deltaTime * 50);
 
             }
         }
     }
 
 }