Prevent Excel from opening while creating excel file using interop

Hi all am creating a excel using Microsoft office interop.and it creates files successfully.But the problem is that when it creates a files it just opens excel adds the value in to excel and saves it in the specified name.Any accidental typing at that time results leads to a exception.Am creating nearly 75 files with many rows from database and hence takes time.During the processing am unable to do any task since it creates exception if its typed in the excel.Is there any way to run the process in background so that excel application does not open for each file creation.

Excel.Application oXL;
Excel.Workbook oWB;
Excel.Worksheet oSheet;
Excel.Range oRange;

// Start Excel and get Application object. 
oXL = new Excel.Application();

// Set some properties 
oXL.Visible = true;
oXL.DisplayAlerts = false;

// Get a new workbook. 
oWB = oXL.Workbooks.Add(Missing.Value);

// Get the active sheet 
oSheet = (Excel.Worksheet)oWB.ActiveSheet;
oSheet.Name = "Sales";

// Process the DataTable 
// BE SURE TO CHANGE THIS LINE TO USE *YOUR* DATATABLE 
DataTable dt = dtt;

int rowCount = 1;
foreach (DataRow dr in dt.Rows)
{
    rowCount += 1;
    for (int i = 1; i < dt.Columns.Count + 1; i++)
    {
        // Add the header the first time through 
        if (rowCount == 2)
        {
            oSheet.Cells[1, i] = dt.Columns[i - 1].ColumnName;
        }
        oSheet.Cells[rowCount, i] = dr[i - 1].ToString();
    }
}

// Resize the columns 
//oRange = oSheet.get_Range(oSheet.Cells[1, 1],
//              oSheet.Cells[rowCount, dt.Columns.Count]);


oRange = oSheet.Range[oSheet.Cells[1, 1], oSheet.Cells[rowCount, dt.Columns.Count]];
oRange.EntireColumn.AutoFit();

// Save the sheet and close 
// oSheet = null;
oRange = null;

oWB.SaveAs("" + username + " .xls", Excel.XlFileFormat.xlWorkbookNormal,
    Missing.Value, Missing.Value, Missing.Value, Missing.Value,
    Excel.XlSaveAsAccessMode.xlExclusive,
    Missing.Value, Missing.Value, Missing.Value,
    Missing.Value, Missing.Value);
oWB.Close(Missing.Value, Missing.Value, Missing.Value);
oWB = null;
oXL.Quit();

// Clean up 
// NOTE: When in release mode, this does the trick 
GC.WaitForPendingFinalizers();
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();