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;
        }