Method for manufacturing semiconductor device with pixel electrode over gate electrode of thin film transistor

A method for manufacturing a semiconductor device, comprising the steps of:

• forming a first transparent conductive film and a first metal film sequentially over a substrate;
• forming a first resist by using a first photomask which is a multi-tone mask, the first resist having different thicknesses in a first portion and in a second portion;
• forming a gate electrode by shaping the first transparent conductive film and the first metal film with the first resist so that a stack of the first transparent conductive film and the first metal film remains in the first portion and only the first transparent conductive film remains in the second portion;
• forming an insulating film over the gate electrode;
• forming a third semiconductor film over the insulating film;
• forming a first semiconductor film, a second semiconductor film, and a second metal film sequentially over the third semiconductor film;
• forming a second resist by using a second photomask which is a multi-tone mask, the second resist having different thicknesses in a channel region formation portion and in a source region formation portion and a drain region formation portion;
• forming a third semiconductor layer, a first semiconductor layer, a second semiconductor layer, and a second metal layer by shaping the third semiconductor film, the first semiconductor film, the second semiconductor film, and the second metal film, respectively, with the second resist;
• ashing the second resist to form a third resist;
• forming a channel region, a source region, a drain region, a source wiring, and a drain wiring of a thin film transistor by etching the third semiconductor layer, the first semiconductor layer, the second semiconductor layer, and the second metal layer with the third resist;
• forming a protective film over the thin film transistor;
• forming a fourth resist in a region so as not to cover a contact hole formation portion by using a third photomask;
• forming a contact hole in the protective film by shaping the protective film with the fourth resist;
• forming a second transparent conductive film over the protective film;
• forming a fifth resist in a pixel electrode formation portion by using a fourth photomask;
• and
• forming a pixel electrode by shaping the second transparent conductive film with the fifth resist.

A method for manufacturing a semiconductor device, comprising the steps of:

• forming a gate electrode;
• forming an insulating film over the gate electrode;
• forming a third semiconductor film over the insulating film;
• forming a first semiconductor film, a second semiconductor film, and a metal film sequentially over the third semiconductor film;
• forming a resist by using a photomask which is a multi-tone mask, the resist having different thicknesses in a channel region formation portion and in a source region formation portion and a drain region formation portion;
• forming a third semiconductor layer, a first semiconductor layer, a second semiconductor layer, and a metal layer by shaping the third semiconductor film, the first semiconductor film, the second semiconductor film, and the metal film, respectively, with the resist;
• and
• forming a channel region, a source region, a drain region, a source wiring, and a drain wiring of a thin film transistor by etching the third semiconductor layer, the first semiconductor layer, the second semiconductor layer, and the metal layer.