Convert string to list of words

private static List<string> stringToWordArray(string s)
{
    List<string> words = new List<string>();
    string word;
    s = s.ToUpper();
    s = s.Trim(',', '.', '"', '-', ' ', ':', ';', '\n', '!', '?');
    while (s.Length > 0)
    {
        if (s.Contains(' '))
        {
            word = s.Substring(0, s.IndexOf(" "));
            s = s.Substring(s.IndexOf(" ") + 1);
            s = s.Trim();
        }
        else
        {
            word = s;
            s = "";
        }
        word = word.Trim(',', '.', '"', '-', ' ', ':', ';', '\n', '!', '?');
        if (word.Length > 0)
            words.Add(word);
        else
            return words;

    }
    return words;
}