Negative resist or dry develop process for forming middle of line implant layer
US7112489B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 3, 2004 |
| Grant date | Sep 26, 2006 |
| Priority date | — |
| Expiry date | Jan 7, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10B69/00
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method of implanting a middle of line (MOL) implant layer of a flash memory device that does not require a descumming step is disclosed. In a first embodiment, the method includes depositing a negative tone resist over the MOL implant layer. Portions of the negative tone resist in and above a plurality of trenches are not exposed to optical radiation, while portions surrounding the plurality of trenches are exposed. The unexposed portions are developed out thereby leaving a bottom surface of each trench substantially free of a resist residue. Implants can be placed in the MOL implant layer without the need for a descumming step. In a second embodiment, a bi-layer resist is deposited on the MOL implant layer, wherein the bi-layer resist includes a silicon containing top layer and a bottom layer. The bi-layer resist is patterned to expose a portion of the bottom layer that resides in and above a plurality of trenches. The bottom layer is dry etch developed using oxygen plasma as the etchant, thereby leaving a bottom surface of each trench substantially free of a resist residue. Implants can be placed in the MOL implant layer without the need for a descumming step.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.