Role of mask on the contact etching for 14nm nodes MEBARKI Mokrane - - PowerPoint PPT Presentation

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Role of mask on the contact etching for 14nm nodes MEBARKI Mokrane - - PowerPoint PPT Presentation

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Role of mask on the contact etching for 14nm nodes MEBARKI Mokrane 1,2,3 Maxime Darnon 2 , Cecile Jenny 1 , Nicolas Posseme 3 , Delia Ristoiu 1 ,Germain Servanton 1 , Olivier Joubert 2 1 ST Microelectronics 2 Laboratoire des technologies de la

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SLIDE 1

Role of mask on the contact etching for 14nm nodes

PESM

Monday, May 12 2014

Grenoble, France

MEBARKI Mokrane1,2,3 Maxime Darnon2, Cecile Jenny1, Nicolas Posseme3, Delia Ristoiu1,Germain Servanton1, Olivier Joubert2

1 ST Microelectronics 2 Laboratoire des technologies de la microélectronique (LTM) CNRS 3 CEA LETI

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SLIDE 2

PESM 2014- mokrane.mebarki@st.com

2

Outline

Double patterning for contact etching

  • Double patterning strategy

Mask Opening

  • Comparison between N2/H2 vs COS/O2

Silicon oxide etching

  • Interaction with OPL mask opening process

Conclusion

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SLIDE 3

Double patterning for contact etching:

3

Increase the number of transistors on a chip Reduce the transistors dimension Change of contacts patterning strategy

Double patterning

PESM 2014- mokrane.mebarki@st.com

Si3N4

  • 1. TiN deposition

First patterning

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SLIDE 4

Double patterning for contact etching:

3

Increase the number of transistors on a chip Reduce the transistors dimension Change of contacts patterning strategy

Double patterning

Cross section post OPL etching

PESM 2014- mokrane.mebarki@st.com

First patterning

  • 1. TiN deposition
  • 2. Trilayer line

pattern

Si3N4

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SLIDE 5

Double patterning for contact etching:

3

Increase the number of transistors on a chip Reduce the transistors dimension Change of contacts patterning strategy

Double patterning

Cross section post OPL etching

PESM 2014- mokrane.mebarki@st.com

Si3N4 TiN Hard mask

  • 1. TiN deposition
  • 3. Post etching of

TiN hard mask

  • 2. Trilayer line

pattern First patterning

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SLIDE 6

Double patterning for contact etching:

4

Increase the number of transistors on a chip Reduce the transistors dimension Change of contacts patterning strategy

Double patterning

Cross section post OPL etching

PESM 2014- mokrane.mebarki@st.com

Second patterning (Cross section)

TiN Hard mask

  • 1. Post etching of

TiN hard mask

  • 2. Trilayer OPL

mask pattern

TiN Hard mask

Si3N4

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SLIDE 7

Double patterning for contact etching:

4

Increase the number of transistors on a chip Reduce the transistors dimension Change of contacts patterning strategy

Double patterning

PESM 2014- mokrane.mebarki@st.com

Second patterning (Cross section)

TiN Hard mask

  • 1. Post etching of

TiN hard mask

  • 2. Trilayer OPL

mask pattern

TiN Hard mask

  • 3. Post OPL

mask etching

Si3N4

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SLIDE 8

Double patterning for contact etching:

4

Increase the number of transistors on a chip Reduce the transistors dimension Change of contacts patterning strategy

Double patterning

PESM 2014- mokrane.mebarki@st.com

Second patterning (Cross section)

TiN Hard mask

  • 1. Post etching of

TiN hard mask

  • 2. Trilayer OPL

mask pattern

  • 3. Post OPL mask

etching

TiN Hard mask Contact

  • 4. Post Silicon
  • xide etching

Si3N4

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SLIDE 9

Double patterning for contact etching:

5

TEOS

TiN

  • pening

SEM Top view post contact etching PESM 2014- mokrane.mebarki@st.com SEM cross section post contact etching TiN TEOS TiN Contact

  • pening

Double patterning

OPL strip Post contact etching

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SLIDE 10

Double patterning for contact etching:

6

Increase the number of transistors on a chip Reduce the transistors dimension Change of contacts patterning strategy

Double patterning

PESM 2014- mokrane.mebarki@st.com

Second patterning (Cross section)

TiN Hard mask

  • 1. Post etching of

TiN hard mask

  • 2. Trilayer OPL

mask pattern

TiN Hard mask Contact

  • 4. Post Silicon oxide

etching

Si3N4

TiN Hard mask

  • 3. Post OPL

mask etching

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SLIDE 11

7

Characteristics of OPL etching:

TEOS

PESM 2014- mokrane.mebarki@st.com

OPL TiN

TEOS

SiARC

TEOS

SiARC TiN OPL

TEOS

SiARC TiN OPL

OPL etching With N2/H2 OPL etching With COS/O2(5%) OPL etching With COS/O2(17%) and shorter over etch Consumption of SiARC Presence of undercut on sidewalls of OPL mask

The increase of COS ratio leads a better conservation of OPL mask.

Etch rate of OPL according the COS ratio

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SLIDE 12

8

Characteristics of OPL etching:

TEOS

PESM 2014- mokrane.mebarki@st.com

EDX analysis after OPL etching with COS/O2(5%)chemistry :

EDX analysis for Ti element

  • bservation :

Presence of Ti elements

Ti

OPL TiN

SiARC

TEOS

EDX analysis for S element

S

TiN

OPL

SiARC

TEOS Si3N4

EDX analysis

SiARC

OPL TEOS TiN OPL

TiN

TEOS

EDX analysis after OPL etching with N2/H2 chemistry :

No significant TiN sputtering

TEM cross section

Interaction between OPL etching and TiN hard mask

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SLIDE 13

Double patterning for contact etching:

9

Increase the number of transistors on a chip Reduce the transistors dimension Change of contacts patterning strategy

Double patterning

PESM 2014- mokrane.mebarki@st.com

Second patterning (Cross section)

TiN Hard mask

  • 1. Post etching of

TiN hard mask

  • 2. Trilayer OPL

mask pattern

  • 3. Post OPL mask

etching

TiN Hard mask Contact

  • 4. Post Silicon
  • xide etching

Si3N4

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SLIDE 14

The contacts are open after contact etching for the OPL opening with N2/H2

10

Interaction with mask opening process:

Etch-stop presence after contact etching for the OPL opening with COS/O2(5%)

TiN TEOS

OPL etching with COS/O2 :

TiN TEOS

Taper profiles

OPL etching with N2/H2 :

Correct profiles

TiN

TEOS

PESM 2014- mokrane.mebarki@st.com

Post contact etching Post contact etching

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SLIDE 15

11

Interaction with mask opening process:

PESM 2014- mokrane.mebarki@st.com

EDX analysis after oxyde etching :

EDX after oxide etching with COS/O2 (5%) for OPL Opening TiOF

OPL OPL TiN TiN TEOS TEOS Contact Contact

Veil formation of TiOxFy on the holes patterned

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SLIDE 16

12

PESM 2014- mokrane.mebarki@st.com

Origin of veil formation:

No TiOF veil

Lower OE Lower TiN sputtering

OPL etching with COS/O2(5%)

Ti

OPL TiN

SiARC

TEOS

EDX analysis EDX analysis

SiARC

OPL TEOS TiN

OPL etching with N2/H2

TiN sputtering Ti residue No significant TiN sputtering

Decrease OE time

After contact etching for OPL etching with COS/O2(5%)

Hypothesis : Ti sputtering during OPL Over Etch induces veil formation during SiO2 etching

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SLIDE 17

Conclusion:

PESM 2014- mokrane.mebarki@st.com

OPL etch

N2/H2 COS/O2

Taper OPL mask profile Straight OPL mask profile

  • Increase ratio of COS/O2

TiN sputter Low TiN sputter

Oxyde etch

Correct Etching Etch stop At long OE Veil formation Contacts open At short OE

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SLIDE 18

Thank you for your attention !

PESM 2014- mokrane.mebarki@st.com

PESM

Monday , May 12 2014

Grenoble, France