Single poly CMOS imager

• US 6,998,657 B2
• Filed: 10/21/2003
• Issued: 02/14/2006
• Est. Priority Date: 10/21/2003
• Status: Expired due to Fees

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Rhodes, Howard E.
• Primary Examiner(s): Tran, Minhloan
• Assistant Examiner(s): Wilson, Scott R.
• Application Number:
  US10/688,974
• Publication Number:
  US 20050082582A1
• Time in Patent Office: 847 Days
• Field of Search: 257/291, 257/59, 257/72, 257/222, 257/225, 257/232, 257/234, 257/E31.075, 257/E31.078, 257/E31.081, 257/E31.084, 257/E27.153, 257/E27.154, 257/E27.159, 257/E27.133, 257/E27.141, 257/E27.148, 257/E27.13, 257/E27.16, 257/E27.15, 257/E29.233, 257/E29.234, 257/E29.235, 257/E29.236, 257/E21.617, 428/60, 428/75, 428/144, 428/48, 428/FOR.213, 377 57- 63
• US Class Current: 257/222
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 27/14689 MOS based technologies

Abstract

More complete charge transfer is achieved in a CMOS or CCD imager by reducing the spacing in the gaps between gates in each pixel cell, and/or by providing a lightly doped region between adjacent gates in each pixel cell, and particularly at least between the charge collecting gate and the gate downstream to the charge collecting gate. To reduce the gaps between gates, an insulator cap with spacers on its sidewalls is formed for each gate over a conductive layer. The gates are then etched from the conductive layer using the insulator caps and spacers as hard masks, enabling the gates to be formed significantly closer together than previously possible, which, in turn increases charge transfer efficiency. By providing a lightly doped region on between adjacent gates, a more complete charge transfer is effected from the charge collecting gate.

Claims

1. A semiconductor device comprising:

a substrate; and

at least two non-overlapping gate structures formed in a single layer on said substrate, said gate structures being spaced apart by a gap measuring less than 1300 Angstroms, wherein at least one of the gate structures is a transistor gate structure.

2. The semiconductor device according to claim 1, wherein said gap measures no less than approximately 300 Angstroms.

3. The semiconductor device according to claim 1, wherein the at least two gate structures are formed of a conductive material selected from polysilicon, silicide, metal, polysilicon and silicide, and polysilicon and metal.

4. The semiconductor device according to claim 1, wherein the gate structures are transistor gates in a CCD imager.

5. The semiconductor device according to claim 1, wherein the gate structures are transistor gates in a CMOS imager.

6. The semiconductor device according to claim 5, wherein the CMOS imager has one of a 3T, 4T, 5T, 6T or 7T architecture.

7. The semiconductor device according to claim 5, wherein the transistor gates include at least two of a transfer gate, a reset gate, a source follower gate, a row select gate, and a storage gate.

8. The semiconductor device according to claim 1, further comprising a lightly doped region between two adjacent ones of the gate structures.

9. The semiconductor device according to claim 8, wherein the lightly doped region is implanted with ions in the range of about 3·

10¹¹ ions/cm² to about 1·

10¹⁴ ions/cm².

10. The semiconductor device according to claim 9, wherein the lightly doped region is implanted with ions in the range of about 1·

10¹² ions/cm² to about 1·

10¹³ ions/cm².

11. The semiconductor device according to claim 8, wherein the at least two gate structures are transistor gates for a CCD imager.

12. The semiconductor device according to claim 8, wherein the at least two gate structures are transistor gates for a CMOS imager and the two adjacent gate structures having the lightly doped region therebetween are selected from among a transfer gate, a reset gate, a source follower gate, a row select gate and a storage gate.

13. The semiconductor device according to claim 12, wherein the two adjacent gate structures having the lightly doped region therebetween include a transfer gate or a storage gate.

14. The semiconductor device according to claim 12, wherein the two adjacent gate structures having the lightly doped region therebetween are n-channel gates and the lightly doped region therebetween is an n-type region.

15. The semiconductor device according to claim 12, wherein the two adjacent gate structures having the lightly doped region therebetween are p-channel gates and the lightly doped region therebetween is a p-type region.

16. A semiconductor device comprising:

a substrate;

a plurality of non-overlapping conductive gates formed over the substrate; and

a lightly doped region in the substrate between two adjacent ones of the plurality of conductive gates, the two adjacent ones of the plurality of conductive gates being formed in a single layer and separated by a gap of less than 1300 Angstroms, wherein at least one of the two adjacent ones of the plurality of gates is a transistor gate.

17. The semiconductor device according to claim 16, wherein the lightly doped region is implanted with ions in the range of about 3·

10¹¹ ions/cm² to about 1·

10¹⁴ ions/cm².

18. The semiconductor device according to claim 17, wherein the lightly doped region is implanted with ions in the range of about 1·

10¹² ions/cm² to about 1·

10¹³ ions/cm².

19. The semiconductor device according to claim 16, wherein the plurality of conductive gates includes transistor gates for a CCD imager.

20. The semiconductor device according to claim 16, wherein the plurality of conductive gates includes transistor gates for a CMOS imager and the two adjacent conductive gates having the lightly doped region therebetween are selected from among a photogate, a transfer gate, a reset gate, a source follower gate, a row select gate and a storage gate.

21. The semiconductor device according to claim 20, wherein the two adjacent conductive gates having the lightly doped region therebetween include a photogate and either a transfer gate or a storage gate.

22. The semiconductor device according to claim 20, wherein the two adjacent conductive gates having the lightly doped region therebetween are n-channel gates and the lightly doped region is an n-type region.

23. The semiconductor device according to claim 20, wherein the two adjacent conductive gates having the lightly doped region therebetween are p-channel gates and the lightly doped region is a p-type region.

24. An image processing apparatus comprising:

an image sensor for detecting an image and outputting image signals corresponding to the detected image; and

an image processor for processing the image signals outputted from the image sensor,

wherein the image sensor comprises;

a substrate; and

at least two non-overlapping gate structures formed in a single layer on said substrate, said gate structures being spaced apart by a gap measuring less than 1300 Angstroms, wherein at least one of the gates structures is a transistor gate.

25. The image processing apparatus according to claim 24, said gap measuring no less than approximately 300 Angstroms.

26. The image processing apparatus according to claim 24, wherein the image sensor is a CCD image sensor.

27. The image processing apparatus according to claim 24, wherein the image sensor is a CMOS image sensor.

28. The image processing apparatus according to claim 24, further comprising a lightly doped region between two of the gate structures.

29. An image processing apparatus comprising:

an image sensor for detecting an image and outputting image signals corresponding to the detected image; and

an image processor for processing the image signals outputted from the image sensor,

wherein the image sensor comprises;

a substrate;

a plurality of conductive gates formed over the substrate; and

a lightly doped region in the substrate between at least one pair of adjacent non-overlapping conductive gates formed in a single layer and separated by a gap of less than 1300 micrometers.

30. A processing system, comprising:

a processor for receiving and processing image data; and

an image data generator for supplying image data to the processor, the image data generator comprising

an image sensor for obtaining an image and outputting an image signal,

an image processor for processing the image signal, and

a controller for controlling the image sensor and the image processor,

wherein the image sensor comprises;

a substrate, and

at least two non-overlapping gate structures formed in a single layer on said substrate, said gate structures being spaced apart by a gap measuring less than 1300 Angstroms, wherein at least one of the gate structures is a transistor gate.

31. The processing system according to claim 30, wherein the image sensor is a CCD imager.

32. The processing system according to claim 30, wherein the image sensor is a CMOS imager.

33. The processing system according to claim 30, further comprising a lightly doped region between at least one pair of adjacent gate structures.

34. A processing system, comprising:

a processor for receiving and processing image data; and

an image data generator for supplying image data to the processor, the image data generator comprising

an image sensor for obtaining an image and outputting an image signal,

an image processor for processing the image signal, and

a controller for controlling the image sensor and the image processor,

wherein the image sensor comprises;

a substrate;

a plurality of non-overlapping conductive gates formed over the substrate; and

a lightly doped region in the substrate between two adjacent ones of the plurality of conductive gates, the adjacent conductive gates being formed in a single layer and separated by a gap of less than 1300 Angstroms.