固定電荷膜

US2019157330(JP)
"16. A method for manufacturing an imaging device, the method comprising:
a first step of forming a first trench and a second trench in respective predetermined positions on a first pattern between a photoelectric conversion unit and an electric-charge holding unit configured to hold an electric charge generated by the photoelectric conversion unit, the first pattern covering a first surface of a semiconductor substrate in which the photoelectric conversion unit and the electric-charge holding unit are formed, the first surface being at a light receiving side of the semiconductor substrate;
【請求項１６】
  光電変換部及び前記光電変換部により生成された電荷を保持する電荷保持部が形成されている半導体基板の光が入射する側の第１の面を覆う第１のパターンの前記光電変換部と前記電荷保持部との間の所定の位置に、第１の溝及び第２の溝をそれぞれ形成する第１の工程と、

a second step of filling the first trench with a second pattern;
前記第１の溝を第２のパターンで塞ぐ第２の工程と、

a third step of digging the second trench down to a middle of the semiconductor substrate;
前記第２の溝を前記半導体基板の途中まで掘り下げる第３の工程と、

a fourth step of, after removing the second pattern, digging down the first trench and the second trench until the second trench penetrates the semiconductor substrate and reaches an insulation film layer formed on a second surface of the semiconductor substrate opposite to the first surface of the semiconductor substrate;
前記第２のパターンを除去した後、前記第１の溝及び前記第２の溝を掘り下げ、前記第２の溝を、前記半導体基板を貫通させ、前記半導体基板の前記第１の面と反対の第２の面に形成されている絶縁膜層に到達させる第４の工程と、

a fifth step of forming a multi-layer film so as to cover the first surface of the semiconductor substrate, inner walls and a bottom of the first trench, and inner walls and a bottom of the second trench, the multi-layer film including a fixed electric charge film, an anti-reflection film, and an insulation film;
前記半導体基板の第１の面、前記第１の溝の内壁及び底、並びに、前記第２の溝の内壁及び底を覆うように、固定電荷膜、反射防止膜、及び、絶縁膜を含む多層膜を形成する第５の工程と、

a sixth step of filling the first trench with a third pattern;
 前記第１の溝を第３のパターンで塞ぐ第６の工程と、

a seventh step of, while removing the third pattern, digging the second trench down until the second trench penetrates the multi-layer film and the insulation film layer and reaches a first light-shielding film stacked on the insulation film layer;
前記第３のパターンの除去と並行して、前記第２の溝を、前記多層膜及び前記絶縁膜層を貫通させ、前記絶縁膜層に積層されている第１の遮光膜まで掘り下げる第７の工程と、

and
an eighth step of forming a second light-shielding film in the first trench and the second trench."

前記第１の溝内及び前記第２の溝内に第２の遮光膜を形成する第８の工程と
  を含む撮像素子の製造方法。