Image sensor and method for manufacturing the same
View Patent ↗An image sensor and a method for manufacturing an image sensor that has an increased aspect ratio. An image sensor and a method for manufacturing an image sensor that have a relatively large process margin (e.g. even in high level pixels), which may reduce and/or eliminate restrictions in downscaling an image sensor. An image sensor may include at least one of a first unit pixel including a first transfer transistor, a second unit pixel including a second drive transistor, and a contact electrically connecting a floating diffusion region of the first unit pixel with the second drive transistor of the second unit pixel. A method of manufacturing an image sensor including at least one of forming a first unit pixel including a first transfer transistor, forming a second unit pixel including a second drive transistor, and forming a contact electrically connecting a floating diffusion region of the first unit pixel with the second drive transistor of the second unit pixel.
1. A method for manufacturing an image sensor, comprising:
forming a first unit pixel including a first transfer transistor;
forming a second unit pixel including a second drive transistor; and
forming a contact that electrically connects a floating diffusion region of the first unit pixel with the second drive transistor of the second unit pixel,
wherein said forming the contact comprises:
forming a first insulator over a first unit pixel region and a second unit pixel region;
forming a first contact hole by selectively removing the first insulator over a floating region of the first pixel region;
forming a contact that electrically connects the second drive transistor by filing the first contact hole,
wherein the contact comprises under insulators between the bottom of the contact and a substrate on which the first unit pixel is formed,
wherein a width of the first contact hole is smaller than a width of a top side of the contact, and
wherein an outer distance between the under insulators is same as the width of the top side of the contact.
2. The method according to claim 1 , wherein said forming the contact is processed at the same time as said forming the first unit pixel and said forming the second unit pixel.
3. The method according to claim 1 , wherein said forming the contact comprises:
forming a polysilicon layer on the first contact hole and the first insulator;
forming a second photoresist pattern on the polysilicon layer that selectively exposes the polysilicon layer of both a transistor region and a contact region;
forming a gate of the first transfer transistor, a gate of the second drive transistor and the contact at the same time by selectively etching the exposed polysilicon layer and the first insulator using the second photoresist pattern as an etch mask.
4. The method according to claim 3 , wherein the contact hole has a smaller horizontal width than a gate of the first transfer transistor.
5. The method according to claim 3 , wherein the contact hole has substantially the same horizontal width as a gate of the first transfer transistor.
6. The method according to claim 1 , wherein the contact comprises polysilicon.
7. The method according to claim 1 , wherein the first unit pixel is a main pixel and the second unit pixel is a dummy pixel.
8. The method according to claim 1 , wherein the contact is formed contacted with side wall of the second drive transistor.
9. The method according to claim 1 , wherein said forming the contact is processed after said forming the first unit pixel and said forming the second unit pixel.
10. The method according to claim 9 , wherein said forming the contact comprises:
forming a inter metal dielectric over the first unit pixel and the second unit pixel;
forming a second contact hole by selectively removing the inter metal dielectric over a floating region of the first pixel; and
forming a contact that electrically connects a second drive transistor by filling the second contact hole.