Precision creation of inter-gates insulator

• US 20050106793A1
• Filed: 11/19/2003
• Published: 05/19/2005
• Est. Priority Date: 11/19/2003
• Status: Active Grant

• Current Assignee: ProMOS Technologies, Inc.
• Original Assignee: Mosel Vitelic Incorporated
• Inventors: Dong, Zhong, Huang, Chunchieh, Jang, Chuck
• Granted Patent: US 7,229,880 B2
• Time in Patent Office: Days
• US Class Current: 438/197
• CPC Class Codes: H01L 29/40114 the electrodes comprising a conductor-insulator-conductor-insulator-semiconductor structure
• CPC Class Codes: H01L 29/511 with a compositional variation, e.g. multilayer structures H01L29/516 takes precedence

Abstract

An ONO-type inter-poly insulator is formed by depositing intrinsic silicon on an oxidation stop layer. In one embodiment, the oxidation stop layer is a nitridated top surface of a lower, and conductively-doped, polysilicon layer. In one embodiment, atomic layer deposition (ALD) is used to precisely control the thickness of the deposited, intrinsic silicon. Heat and an oxidizing atmosphere are used to convert the deposited, intrinsic silicon into thermally-grown, silicon dioxide. The oxidation stop layer impedes deeper oxidation. A silicon nitride layer and an additional silicon oxide layer are further deposited to complete the ONO structure before an upper, and conductively-doped, polysilicon layer is formed. In one embodiment, the lower and upper polysilicon layers are patterned to respectively define a floating gate (FG) and a control gate (CG) of an electrically re-programmable memory cell. In an alternative embodiment, after the middle, silicon nitride of the ONO structure is defined, another layer of intrinsic silicon is deposited, by way of for example, ALD. Heat and an oxidizing atmosphere are used to convert the second deposited, intrinsic silicon into thermally-grown, silicon dioxide. An ONO structure with two thermally-grown, and spaced apart, silicon oxide layers is thereby provided.

Claims

1. An isolation providing method comprising:

(a) defining a first oxidation stop layer above a first conductively-doped semiconductor layer;

(b) providing a first intrinsic silicon layer on the first oxidation stop layer;

(c) oxidizing at least a sublayer portion of the first intrinsic silicon layer so as to thereby create a corresponding and thermally-grown, first intrinsic silicon oxide sublayer over the first semiconductor layer; and

(d) disposing a second conductively-doped semiconductor layer above the first intrinsic silicon oxide sublayer so that the first intrinsic silicon oxide sublayer provides isolation between the first and second conductively-doped semiconductor layers.

2. The isolation providing method of claim 1 wherein:

(c.1) said thermally-grown, first intrinsic silicon oxide sublayer includes stoichiometric silicon dioxide (SiO₂).

3. The isolation providing method of claim 1 wherein:

(b.1) said providing of the first intrinsic silicon layer includes using atomic layer deposition (ALD) to define a thickness of the first intrinsic silicon layer.

4. The isolation providing method of claim 3 wherein:

(b.2) said thickness of the first intrinsic silicon layer is in a range of about 15 Å

to about 50 Å

.

5. The isolation providing method of claim 4 wherein:

(a.1) said defining of the first oxidation stop layer includes creating a first silicon nitride composition having a nitrogen concentration of at least about 5% atomic.

6. The isolation providing method of claim 5 wherein:

(a.1a) said first silicon nitride composition has a nitrogen concentration of at least about 10% atomic.

7. The isolation providing method of claim 5 wherein:

(a.2) said creating of the first silicon nitride composition includes using Decoupled Plasma Nitridation (DPN) to introduce nitrogen into the first conductively-doped semiconductor layer.

8. The isolation providing method of claim 5 wherein:

(a.2) said creating of the first silicon nitride composition includes using Remote Plasma Nitridation (RPN) to introduce nitrogen into the first conductively-doped semiconductor layer.

9. The isolation providing method of claim 5 wherein:

(a.2) said creating of the first silicon nitride composition includes using ion implant to introduce nitrogen into the first conductively-doped semiconductor layer.

10. The isolation providing method of claim 1 and further characterized by:

(c.1) continuing said oxidizing of the first intrinsic silicon layer at least until a corresponding first oxidation front crosses into the first oxidation stop layer so as to thereby perfect formation of silicon dioxide in the thermally-oxidized, first intrinsic silicon layer.

11. The isolation providing method of claim 10 and further characterized by:

(c.2) continuing said oxidizing of the first intrinsic silicon layer yet further so as to consume silicon atoms within the first oxidation stop layer and so as to thereby produce additional silicon oxide from the consumed silicon atoms.

12. The isolation providing method of claim 10 and further comprising:

(e) providing a silicon nitride layer between the first and second conductively-doped semiconductor layers so that the combination of the silicon nitride layer and the perfected silicon dioxide in the thermally-oxidized, first intrinsic silicon layer provide isolation between the first and second conductively-doped semiconductor layers.

13. The isolation providing method of claim 12 and further comprising:

(f) providing a second silicon oxide layer between the silicon nitride layer and the second conductively-doped semiconductor layer so that the combination of the second silicon oxide layer, the silicon nitride layer and the perfected silicon dioxide in the thermally-oxidized, first intrinsic silicon layer provide isolation between the first and second conductively-doped semiconductor layers.

14. The isolation providing method of claim 1 and further comprising:

(e) providing a silicon nitride layer between the first and second conductively-doped semiconductor layers so that the combination of the silicon nitride layer and the first intrinsic silicon oxide sublayer provide isolation between the first and second conductively-doped semiconductor layers.

15. The isolation providing method of claim 14 and further comprising:

(f) providing a second silicon oxide layer between the silicon nitride layer and the second conductively-doped semiconductor layer so that the combination of the second silicon oxide layer, the silicon nitride layer and the first intrinsic silicon oxide sublayer provide isolation between the first and second conductively-doped semiconductor layers.

16. An insulating structure comprising:

(a) an oxidation stop layer; and

(b) a thermally-grown, intrinsic, silicon oxide layer which has been grown from ALD deposited intrinsic, silicon that had been deposited on said oxidation stop layer.

17. The insulating structure of claim 16 wherein:

(a.1) said oxidation stop layer includes a nitridated surface of a floating gate electrode.

18. The insulating structure of claim 16 wherein:

(a.1) said oxidation stop layer includes a silicon nitride composition having at least 5% atomic concentration of nitrogen.

19. The insulating structure of claim 18 wherein:

(a.1) said oxidation stop layer has a thickness of no less than about 5 Å and

no more than about 30 Å

.

20. The insulating structure of claim 19 wherein:

(b.1) said thermally-grown, intrinsic, silicon oxide layer has a thickness of no less than about 30 Å and

more than about 100 Å

.

21. The insulating structure of claim 16 wherein:

(b.1) said thermally-grown, intrinsic, silicon oxide layer has a thickness of no less than about 30 Å and

more than about 100 Å

.