Electro-optical device and semiconductor circuit

• US 6,303,963 B1
• Filed: 12/01/1999
• Issued: 10/16/2001
• Est. Priority Date: 12/03/1998
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ohtani, Hisashi, Koyama, Jun, Yamazaki, Shunpei
• Primary Examiner(s): Ng&ocirc ;, Ng&acirc ;n V.
• Application Number:
  US09/452,390
• Time in Patent Office: 685 Days
• Field of Search: 257/57, 257/59, 257/70, 257/72, 257/350, 257/627
• US Class Current: 257/350
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• CPC Class Codes: H01L 21/02381 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02425 Conductive materials, e.g. metallic silicides
• CPC Class Codes: H01L 21/02488 Insulating materials
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02609 Crystal orientation
• CPC Class Codes: H01L 21/02672 using crystallisation enhancing elements
• CPC Class Codes: H01L 27/1277 using a crystallisation promoting species, e.g. local introduction of Ni catalyst
• CPC Class Codes: H01L 27/1296 adapted to increase the uniformity of device parameters
• CPC Class Codes: H01L 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/78627 with a significant overlap between the lightly doped drain and the gate electrode, e.g. GOLDD
• CPC Class Codes: H01L 29/78684 having a semiconductor body comprising semiconductor materials of Group IV not being silicon, or alloys including an element of the group IV, e.g. Ge, SiN alloys, SiC alloys H01L29/7869 takes precedence

Abstract

A high performance circuit is formed by using a TFT with less fluctuation in characteristics, and a semiconductor device including such a circuit is formed. When the TFT is formed, first, a base film and a semiconductor film are continuously formed on a quartz substrate without exposing to the air. After the semiconductor film is crystallized by using a catalytic element, the catalytic element is removed. In the TFT formed in such a process, fluctuation in electrical characteristics such as a threshold voltage and a subthreshold coefficient is extremely small. Thus, it is possible to form a circuit, such as a differential amplifier circuit, which is apt to receive an influence of characteristic fluctuation of a TFT.

Claims

1. A semiconductor device comprising a plurality of thin-film transistors formed over a same substrate, said thin-film transistors comprising:

a crystalline semiconductor film having a {110} plane orientation in channel formation regions of said thin-film transistors,

wherein 90% or more of crystal lattices have continuity at any crystal grain boundaries in said channel formation regions, and

wherein a standard deviation is 0.1 V or less when a collective of threshold voltages exhibited by the plurality of the respective thin-film transistors is made a population.

7. A semiconductor device of claim 1 wherein said threshold voltage is a value of a point where a tangential line having a maximum slope among tangential lines of a curve obtained by plotting gate voltages in an X axis and square roots of drain currents in a Y axis intersects with the X axis when a measurement is made under a condition that a source voltage is 0 V, a drain voltage is 11 V, and a gate voltage is −

20 to 20 V.

13. A semiconductor device of claim 1 wherein said semiconductor device is an active matrix type EL display device.

19. A semiconductor device of claim 1 wherein said semiconductor device is one selected from the group consisting of a video camera, a digital camera, a projector, a goggle-type display, a personal computer, and a mobile telephone.

25. A semiconductor device of claim 1 wherein said semiconductor film comprises Si_xGe₍₁₋

x)(0<

x<

1).

2. A semiconductor device comprising a plurality of thin-film transistors formed over a same substrate, said thin-film transistors comprising:

a crystalline semiconductor film having a {110} plane orientation in channel formation regions of said thin-film transistors,

wherein a standard deviation is 0.1 V or less when a collective of threshold voltages exhibited by the plurality of the respective thin-film transistors is made a population.

8. A semiconductor device of claim 2 wherein said threshold voltage is a value of a point where a tangential line having a maximum slope among tangential lines of a curve obtained by plotting gate voltages in an X axis and square roots of drain currents in a Y axis intersects with the X axis when a measurement is made under a condition that a source voltage is 0 V, a drain voltage is 11 V, and a gate voltage is −

20 to 20 V.

14. A semiconductor device of claim 2 wherein said semiconductor device is an active matrix type EL display device.

20. A semiconductor device of claim 2 wherein said semiconductor device is one selected from the group consisting of a video camera, a digital camera, a projector, a goggle-type display, a personal computer, and a mobile telephone.

26. A semiconductor device of claim 2 wherein said semiconductor film comprises Si_xGe₍₁₋

x)(0<

x<

1).

3. A semiconductor device comprising a plurality of thin-film transistors formed over a same substrate, said thin-film transistors comprising:

a crystalline semiconductor film having a {110} plane orientation in channel formation regions of said thin-film transistors,

wherein said {110} plane orientation is observed by an electron beam diffraction pattern when an electron beam is vertically irradiated to said channel formation regions, and

wherein a standard deviation is 0.1 V or less when a collective of threshold voltages exhibited by the plurality of the respective thin-film transistors is made a population.

9. A semiconductor device of claim 3 wherein said threshold voltage is a value of a point where a tangential line having a maximum slope among tangential lines of a curve obtained by plotting gate voltages in an X axis and square roots of drain currents in a Y axis intersects with the X axis when a measurement is made under a condition that a source voltage is 0 V, a drain voltage is 11 V, and a gate voltage is −

20 to 20 V.

15. A semiconductor device of claim 3 wherein said semiconductor device is an active matrix type EL display device.

21. A semiconductor device of claim 3 wherein said semiconductor device is one selected from the group consisting of a video camera, a digital camera, a projector, a goggle-type display, a personal computer, and a mobile telephone.

27. A semiconductor device of claim 3 wherein said semiconductor film comprises Si_xGe₍₁₋

x)(0<

x<

1).

4. A semiconductor device comprising a plurality of thin-film transistors formed over a same substrate, said thin-film transistors comprising:

a crystalline semiconductor film having a {110} plane orientation in channel formation regions of said thin-film transistors,

wherein 90% or more of crystal lattices have continuity at any crystal grain boundaries in said channel formation regions, and

wherein a standard deviation is 10 mV/dec or less when a collective of subthreshold coefficients exhibited by the plurality of the respective thin-film transistors is made a population.

10. A semiconductor device of claim 4 wherein said subthreshold coefficient is a reciprocal of a slope of a tangential line having a maximum slope among tangential lines of a curve obtained by plotting gate voltages in an X axis and square roots of drain currents in a Y axis when a measurement is made under a condition that a source voltage is 0 V, a drain voltage is 1 V, and a gate voltage is −

20 to 20 V.

16. A semiconductor device of claim 4 wherein said semiconductor device is an active matrix type EL display device.

22. A semiconductor device of claim 4 wherein said semiconductor device is one selected from the group consisting of a video camera, a digital camera, a projector, a goggle-type display, a personal computer, and a mobile telephone.

28. A semiconductor device of claim 4 wherein said semiconductor film comprises Si_xGe₍₁₋

x)(0<

x<

1).

5. A semiconductor device comprising a plurality of thin-film transistors formed over a same substrate, said thin-film transistors comprising:

a crystalline semiconductor film having a {110} plane orientation in channel formation regions of said thin-film transistors,

wherein a standard deviation is 10 mV/dec or less when a collective of subthreshold coefficients exhibited by the plurality of the respective thin-film transistors is made a population.

11. A semiconductor device of claim 5 wherein said subthreshold coefficient is a reciprocal of a slope of a tangential line having a maximum slope among tangential lines of a curve obtained by plotting gate voltages in an X axis and square roots of drain currents in a Y axis when a measurement is made under a condition that a source voltage is 0 V, a drain voltage is 1 V, and a gate voltage is −

20 to 20 V.

17. A semiconductor device of claim 5 wherein said semiconductor device is an active matrix type EL display device.

23. A semiconductor device of claim 5 wherein said semiconductor device is one selected from the group consisting of a video camera, a digital camera, a projector, a goggle-type display, a personal computer, and a mobile telephone.

29. A semiconductor device of claim 5 wherein said semiconductor film comprises Si_xGe₍₁₋

x)(0<

x<

1).

6. A semiconductor device comprising a plurality of thin-film transistors formed over a same substrate, said thin-film transistors comprising:

a crystalline semiconductor film having a {110} plane orientation in channel formation regions of said thin-film transistors,

wherein said {110} plane orientation is observed by an electron beam diffraction pattern when an electron beam is vertically irradiated to said channel formation regions, and

wherein a standard deviation is 10 mV/dec or less when a collective of subthreshold coefficients exhibited by the plurality of the respective thin-film transistors is made a population.

12. A semiconductor device of claim 6 wherein said subthreshold coefficient is a reciprocal of a slope of a tangential line having a maximum slope among tangential lines of a curve obtained by plotting gate voltages in an X axis and square roots of drain currents in a Y axis when a measurement is made under a condition that a source voltage is 0 V, a drain voltage is 1 V, and a gate voltage is −

20 to 20 V.

18. A semiconductor device of claim 6 wherein said semiconductor device is an active matrix type EL display device.

24. A semiconductor device of claim 6 wherein said semiconductor device is one selected from the group consisting of a video camera, a digital camera, a projector, a goggle-type display, a personal computer, and a mobile telephone.

30. A semiconductor device of claim 6 wherein said semiconductor film comprises Si_xGe₍₁₋

x)(0<

x<

1).