-continued  -continued  124  US 8,900,791 B2  123  [6] Acid Crosslinking Agent (D) Capable ofCrosslinking  with the Alkali-Soluble Resin by the Action of an Acid  Hereinafter, this agent is also referred to as "component  (D)" or "crosslinking agent."  A crosslinking agent is used in the negative photosensitive  composition of the present invention.  Any crosslinking agent can be used as long as it is a com› pound capable of crosslinking with the resin soluble in an  alkali developer by the action of an acid. However, com› pounds (1) to (3) below are preferred.  (1) A hydroxymethylated form, alkoxymethylated or acy› loxymethylated form of phenol derivative.  (2) A compound having an N-hydroxymethyl group, an  N-alkoxymethyl group or an N-acyloxymethyl group.  (3) A compound having an epoxy group.  The alkoxymethyl group preferably has 6 or less carbon  atoms, and the acyloxymethyl group preferably has 6 or less  carbon atoms.  Those especially preferred among these crosslinking  agents will be shown below.  L1  L4  HO  OH  OH  L1  L4  OH  OH  ~coo,B"  HO  HO  OH  Ls  L4  OH  OH  OH  OH  OH  OH  Ls  OH  L1  OH  L2 