One embodiment of this invention provides a method of making a device in which an oxide hard mask layer is used below a thin DARC layer. This is believed to be the main cause of defects including pattern collapse, sloped resist profiles, critical diameter variations, and other abnormalities.

However, the addition of a BARC layer generally requires thicker resists, and ultimately leads to increased aspect ratio of lithographic features. In the prior art configuration, the thick DARC layer 106 serving as a hard mask in etching steps is used together with the organic BARC layer 109 to provide satisfactory anti-reflection properties required for photolithography. 7A, and a pillar-shape module is used for simulations in FIG. A rail-shape module is used for simulations in FIG.

7A and 7B are simulation results showing substrate reflectivity as a function of thickness, real refractive index (n), and imaginary refractive index (k) of the DARC layer. 6A, and a pillar-shape module is used for simulations in FIG. 6A and 6B are simulation results showing substrate reflectivity as a function of DARC layer thickness. 5 is a side cross-sectional view illustrating a hard mask configuration of a fourth embodiment of the invention.ДЇIGS.

4 is a side cross-sectional view illustrating a hard mask configuration of a third embodiment of the invention.ДЇIG. 3 is a side cross-sectional view illustrating a hard mask configuration of a second embodiment of the invention.ДЇIG. 2 is a side cross-sectional view illustrating a hard mask configuration of a first embodiment of the invention.ДЇIG. 1 is a side cross-sectional view illustrating a prior art hard mask configuration.ДЇIG. One embodiment of the invention provides a method of making a device comprising forming a device layer, forming an organic hard mask layer over the device layer, forming a first oxide hard mask layer over the organic hard mask layer, forming a silicon oxynitride DARC layer over the first oxide hard mask layer, forming a photoresist layer over the DARC layer, patterning the photoresist layer to form a photoresist pattern, and transferring the photoresist pattern to the device layer using the DARC layer, the first oxide hard mask layer and the organic hard mask layer. 1, DARC layer 106 may be 60 nm thick and have a refractive index of real part (n) of 1.82 and imaginary part (k) of 0.175. The thickness of the DARC 106 layer generally ranges from 60 to 80 nm, primarily driven by the need of providing sufficient masking for patterning the organic hard mask 103. Resist patterns 111 are first used to define the BARC 109 and the DARC 106 that in return is used to define the organic hard mask 103, followed by patterning a device layer 101. A photoresist 111 is located above the BARC layer.ДЄ combination of the DARC 106 and the BARC 109 layers are used to ensure proper suppression of wafer reflectivity. The stack consists of a layer of organic hard mask 103, also called advanced patterning film (APF), a layer of Dielectric Anti-Reflective Coating (DARC) 106, such as silicon oxynitride, on top of organic hard mask 103, and a Bottom Anti-Refection Coating (BARC) 109 layer, such as an organic BARC layer, on top of DARC layer 106. In order to fabricate 45 nm and 80 nm features, one prior art process uses a hard mask stack shown in FIG. The invention relates generally to a photolithography method for making a semiconductor device, for example, a diode containing nonvolatile memory array.

Darc effect stack