Method for manufacturing semiconductor device and method for manufacturing solid state image sensor using multiple insulation films

1. A method for manufacturing a semiconductor device, the method comprising

preparing a structure including a semiconductor substrate having a first region and a second region, a first insulating film arranged on the first region of the semiconductor substrate, a second insulating film arranged on the first insulating film, a third insulating film arranged on the second insulating film, a fourth insulating film arranged on the second region of the semiconductor substrate, a fifth insulating film arranged on the fourth insulating film, and a sixth insulating film arranged on the fifth insulating film;

forming first contact holes extending through the first insulating film, the second insulating film, and the third insulating film; and

forming second contact holes extending through the fourth insulating film, the fifth insulating film, and the sixth insulating film,

wherein the first insulating film, the third insulating film, the fourth insulating film, and the sixth insulating film have a first composition, and the second insulating film and the fifth insulating film have a second composition different from the first composition,

the forming the first contact holes comprises etching the third insulating film using the second insulating film as an etching stopper, etching the second insulating film, and then etching the first insulating film under an etching condition different from an etching condition for the second insulating film, and

the forming the second contact holes comprises etching the sixth insulating film using the fifth insulating film as an etching stopper, and then continuously etching the fifth insulating film and the fourth insulating film under the same etching condition for the fifth insulating film and the fourth insulating film.

2. The method according to claim 1 , wherein the forming the second contact holes is performed after forming contact plugs in the first contact holes.

3. The method according to claim 1 , wherein the forming the first contact holes is performed after forming contact plugs in the second contact holes.

4. The method according to claim 1 , wherein the first insulating film, the third insulating film, the fourth insulating film, and the sixth insulating film comprise silicon oxide films, and the second insulating film and the fifth insulating film comprise silicon nitride films, respectively.

5. The method according to claim 1 , wherein the forming the first contact holes comprises:

etching the third insulating film using a first photoresist pattern formed on the third insulating film to form openings in the third insulating film;

removing the first photoresist pattern after the etching the third insulating film; and

etching the second insulating film and the first insulating film under different etching conditions through the openings formed in the third insulating film after the removing the first photoresist pattern.

6. The method according to claim 1 , wherein the forming the second contact holes comprises:

etching the sixth insulating film using a second photoresist pattern formed on the sixth insulating film to form openings in the sixth insulating film;

removing the second photoresist pattern after the etching the sixth insulating film; and

etching the fifth insulating film and the fourth insulating film under the same etching condition for the fifth insulating film and the fourth insulating film, through the openings formed in the sixth insulating film after the removing the second photoresist pattern.

7. The method according to claim 1 , wherein the forming the second contact holes comprises forming the second contact holes so as to expose one of a metal silicide and a metal.

8. The method according to claim 1 , wherein the semiconductor device includes a solid state image sensor, and

the first region includes a pixel area having pixels each including a photoelectric converter, and the second region includes a peripheral area which reads out signals from the pixels.

9. A method for manufacturing a solid state image sensor, the method comprising:

preparing a structure including a semiconductor substrate having a pixel area having pixels each including a photoelectric converter and a peripheral area including a circuit containing a silicide layer to read out signals from the pixels, a first insulating film arranged on the pixel area of the semiconductor substrate, a second insulating film arranged on the first insulating film, a third insulating film arranged on the second insulating film, a fourth insulating film arranged on the peripheral area of the semiconductor substrate, a fifth insulating film arranged on the fourth insulating film, and a sixth insulating film arranged on the fifth insulating film;

forming first contact holes extending through the first insulating film, the second insulating film, and the third insulating film; and

forming second contact holes extending through the fourth insulating film, the fifth insulating film, and the sixth insulating film,

wherein the first insulating film, the third insulating film, the fourth insulating film, and sixth insulating film have a first composition, and the second insulating film and the fifth insulating film have a second composition different from the first composition,

the forming the first contact holes comprises etching the third insulating film using the second insulating film as an etching stopper, etching the second insulating film, and then etching the first insulating film under an etching condition different from an etching condition for the second insulating film, and

the forming the second contact holes comprises etching the sixth insulating film using the fifth insulating film as an etching stopper, and then continuously etching the fifth insulating film and the fourth insulating film under the same etching condition for the fifth insulating film and the fourth insulating film.

10. The method according to claim 9 , wherein the forming the second contact holes is performed after forming contact plugs in the first contact holes.

11. The method according to claim 9 , wherein the forming the first contact holes is performed after forming contact plugs in the second contact holes.

12. The method according to claim 9 , wherein the first insulating film, the third insulating film, the fourth insulating film, and the sixth insulating film comprise silicon oxide films, and the second insulating film and the fifth insulating film comprise silicon nitride films, respectively.