Solid-state imaging device and method for manufacturing the same
Provided is a solid-state imaging device capable of reducing bonding defects when two substrates are bonded to each other, and a method for manufacturing the solid-state imaging device. The solid-state imaging device includes a first substrate including a first electrode formed with a metal, and a second substrate that is a substrate bonded to the first substrate, the second substrate including a second electrode formed with a metal, the second electrode being bonded to the first electrode. In at least one of the first substrate or the second substrate, a diffusion preventing layer of the metal is formed for a layer formed with the metal filling a hole portion, the metal forming the electrodes.
1. A solid-state imaging device, comprising:
a first substrate that includes a first electrode, wherein the first electrode includes a metal; and
a second substrate bonded to the first substrate, wherein
the second substrate includes a second electrode, wherein the second electrode includes the metal,
the second electrode is bonded to the first electrode, and
at least one of the first substrate or the second substrate includes:
a first layer that includes a first metal seed film and a first hole portion, wherein the first hole portion includes the metal;
a diffusion preventing layer on a surface of the first layer; and
a second layer on the surface of the first layer, wherein
the second layer includes a second metal seed film,
the diffusion preventing layer is between the first layer and the second layer,
the diffusion preventing layer includes a portion of the second metal seed film,
the first metal seed film includes:
a first region; and
a second region spaced apart from the first region, and
each of the first region and the second region of the first metal seed film is in contact with the portion of the second metal seed film in the diffusion preventing layer.
2. The solid-state imaging device according to claim 1 , wherein
the second layer includes a second hole portion,
the second hole portion includes the metal, and
the second hole portion that includes the metal is a connecting pad portion.
3. The solid-state imaging device according to claim 2 , wherein
the first metal seed film is between a side surface of the first hole portion and the metal in the first hole portion, and
the second metal seed film is between a side surface of the second hole portion and the metal in the second hole portion.
4. The solid-state imaging device according to claim 2 , wherein a diameter of the second hole portion in the second layer is greater than a diameter of the first hole portion in the first layer.
5. The solid-state imaging device according to claim 4 , wherein the diameter of the first hole portion has a shape different from the diameter of the second hole portion.
6. The solid-state imaging device according to claim 2 , wherein the second layer further includes a bonding surface opposite to the diffusion preventing layer.
7. The solid-state imaging device according to claim 2 , wherein the diffusion preventing layer further includes an insulating film.
8. The solid-state imaging device according to claim 7 , wherein the insulating film includes silicon oxide.
9. The solid-state imaging device according to claim 3 , wherein the first metal seed film includes one of tantalum (Ta) or titanium (Ti).
10. The solid-state imaging device according to claim 1 , wherein the first electrode and the second electrode include copper (Cu).
11. The solid-state imaging device according to claim 1 , wherein
the diffusion preventing layer is for prevention of diffusion of the metal at a time of heat treatment after the first substrate is bonded to the second substrate.
12. The solid-state imaging device according to claim 1 , wherein
the first substrate is a sensor substrate having a pixel region,
the pixel region includes a plurality of pixels,
each of the plurality of pixels includes a photoelectric conversion unit,
pixels of the plurality of pixels are in a two-dimensional arrangement, and
the second substrate is a circuit substrate including a determined circuit.