Method of producing thin films

• US 20070128858A1
• Filed: 12/05/2005
• Published: 06/07/2007
• Est. Priority Date: 12/05/2005
• Status: Active Grant

• Current Assignee: ASM International NV
• Original Assignee: ASM International NV
• Inventors: Haukka, Suvi, Huotari, Hannu
• Granted Patent: US 7,563,715 B2
• Time in Patent Office: Days
• US Class Current: 438/656
• CPC Class Codes: C23C 16/34 Nitrides C23C16/303 takes precedence
• CPC Class Codes: C23C 16/45525 Atomic layer deposition [ALD]
• CPC Class Codes: C23C 16/45531 specially adapted for making ternary or higher compositions
• CPC Class Codes: C23C 16/45542 Plasma being used non-continuously during the ALD reactions
• CPC Class Codes: H01L 21/28088 the final conductor layer next to the insulator being a composite, e.g. TiN
• CPC Class Codes: H01L 21/28562 Selective deposition
• CPC Class Codes: H01L 21/823842 gate conductors with different gate conductor materials or different gate conductor implants, e.g. dual gate structures
• CPC Class Codes: H01L 29/4966 the conductor material next to the insulator being a composite material, e.g. organic material, TiN, MoSi2 H01L29/4908, H01L29/4983 take precedence
• CPC Class Codes: H01L 29/517 the insulating material comprising a metallic compound, e.g. metal oxide, metal silicate H01L29/518 takes precedence
• CPC Class Codes: H01L 29/6659 with both lightly doped source and drain extensions and source and drain self-aligned to the sides of the gate, e.g. lightly doped drain [LDD] MOSFET, double diffused drain [DDD] MOSFET
• CPC Class Codes: H01L 29/7833 with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's for thin film transistors H01L29/78618

Abstract

A process for producing metal nitride thin films comprising doping the metal nitride thin films by atomic layer deposition (ALD) with silicon or boron or a combination thereof. The work function of metal nitride thin films, which are used in metal electrode applications, can efficiently be tuned.

Claims

1. A process for producing a boron or silicon doped metal nitride thin film on a substrate in a reaction chamber by atomic layer deposition, the process comprising:

providing a first vapor phase reactant pulse comprising a metal precursor into the reaction chamber to form no more than about a single molecular layer of the metal precursor on the substrate;

removing excess first reactant from the reaction chamber;

providing a second vapor phase reactant pulse comprising a nitrogen precursor to the reaction chamber such that the nitrogen precursor reacts with the metal precursor on the substrate;

removing excess second reactant and any reaction by-products from the reaction chamber;

providing a third vapor phase reactant pulse comprising a silicon or boron precursor to the reaction chamber;

removing excess third reactant and any reaction by-products from the reaction chamber;

providing a fourth vapor phase reactant pulse comprising a nitrogen precursor to the reaction chamber;

removing excess fourth reactant and any reaction by-products from the reaction chamber; and

repeating said providing and removing steps until a thin film of a desired thickness and composition is obtained.

2. The process according to claim 1, wherein the second vapor phase reactant and fourth vapor phase reactant comprise NH₃.

3. The process according to claim 1, wherein the second vapor phase reactant and fourth vapor phase reactant both comprise nitrogen and hydrogen containing plasma.

4. The process according to claim 1, wherein the fourth vapor phase reactant is hydrogen containing plasma.

5. The process according to claim 1, comprising using as a precursor of silicon or boron a compound according to formula I

R¹_pAX_q 

 

I

wherein

A stands for silicon or boron;

R¹ stands for an organic ligand bonded to A by a carbon-A bond;

X stands for a halogen;

q is an integer having a value in the range from 1 to the valence of A; and

p is an integer having a value in the range from 0 to q−

1.

6. The process according to claim 5, comprising using a compound of formula I, wherein q has a value in the range from 2 to the valence of A, and X is selected from the group of chloro, bromo, iodo and fluoro.

7. The process according to claim 5, comprising using a compound of formula I, wherein R¹ is selected from the group of

linear or branched C₁-C₂₀ alkyl or alkenyl groups;

halogenated alkyl or alkenyl groups, wherein at least one hydrogen atom is replaced with a fluorine, chlorine, bromine or iodine atom;

carbocyclic groups; and

heterocyclic groups.

8. The process according to claim 5, comprising using a compound selected from the group of SiCl₄ and BCl₃ as the precursor of silicon or boron.

9. The process according to claim 5, wherein the fourth vapor phase reactant pulse is introduced into the reactor over a time interval which is 2 to 20 times longer than the time interval for the introduction of the second vapor phase reactant pulse.

10. The process according to claim 1, wherein the metal precursor is selected from precursors of niobium, tantalum, titanium, tungsten and molybdenum and mixtures thereof.

11. The process according to claim 10, wherein the metal precursor is a chloride compound of the metal.

12. The process according to claim 1, wherein the substrate is maintained at temperature of 300-500°

C.

13. A method of fabricating a semiconductor device, comprising

depositing a gate dielectric layer over a semiconductor substrate;

forming a gate electrode comprising a lower part and an upper part over the gate dielectric layer, the gate dielectric layer and the gate electrode forming a gate stack; and

tuning the overall electronegativity of the lower part of the gate electrode to provide a desired work function of the gate stack,

wherein at least the lower part of the gate electrode is formed by an atomic layer deposition (ALD) type process comprising one or more deposition cycles, each cycle comprising a sequence of alternating and repeated exposure of the substrate to two or more different reactants to form an elemental metal film or a compound film of at least binary composition, and wherein the work function of the lower part of the electrode is tuned by adjusting the deposition cycles by introducing at least one pulse of a precursor of silicon or boron or a combination thereof in selected deposition cycles, wherein the precursor of silicon or boron is a compound having the formula I

R¹_pAX_q 

 

I

wherein

A stands for silicon or boron;

R¹ stands for an organic ligand bonded to A by a carbon-A bond;

X stands for halo;

q is an integer having a value in the range from 1 to the valence of A; and

p is an integer having a value in the range from 0 to q−

1.

14. The process according to claim 13, comprising using a compound selected from the group of SiCl₄ and BCl₃ as the precursor of silicon or boron.

15. A process for producing metal nitride thin films having enhanced barrier properties, comprising doping the metal nitride thin films with silicon or boron or a combination thereof by an atomic layer deposition (ALD) type process using as a precursor of silicon or boron a compound having the formula I

R¹_pAX_q 

 

I

wherein

A stands for silicon or boron;

R¹ stands for an organic ligand bonded to A by a carbon-A bond;

X stands for halo;

q is an integer having a value in the range from 1 to the valence of A; and

p is an integer having a value in the range from 0 to q−

1.

16. The process according to claim 15, comprising using a compound selected from the group of SiCl₄ and BCl₃ as the precursor of silicon or boron.

17. An atomic layer deposition type process for producing doped metal nitride thin films for electrodes in capacitor structures, comprising doping the metal nitride thin films using precursors of silicon or boron or a combination thereof, said precursors having the formula I

R¹_pAX_q 

 

I

wherein

A stands for silicon or boron;

R¹ stands for an organic ligand bonded to A by a carbon-A bond;

X stands for halo;

q is an integer having a value in the range from 1 to the valence of A; and

p is an integer having a value in the range from 0 to q−

1.

18. The process according to claim 17, comprising using a compound selected from the group of SiCl₄ and BCl₃ as a precursor or silicon or boron.