Method of forming contact holes of reduced dimensions by using reverse-transcription process

First, a photoresist layer is formed on the substrate, wherein the photoresist layer has a plug-like structure. Then, an oxide layer is deposited on the plug-like structure. The oxide layer is etched to expose a portion of the plug-like structure. The plug-like structure is removed to formed a hole. Next, a conformal layer is deposited on the oxide layer and hole. Finally, the conformal oxide layer is etched, then the width of hole is smaller then original hole.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention provides a method of forming cavities such as contact holes, line spacing or trenches of reduced dimensions in a semiconductor device by using reverse-transcription process. In order to be formed cavities such as contact holes, line spacings or trenches in the dielectric layer. First, a photoresist layer must be deposited on the substrate. The photoresist layer can be of the type that is suitable for optical lithographic technique that utilizes I-line ultraviolet wavelength and that can be exposed and developed at relatively low cost. Referring initially to FIG. 3 where an enlarged, cross-sectional view is shown. First step, a photoresist layer 110 is deposited on substrate 100 wherein the photoresist layer 110 has a plug-like structure 100 act as island. Substrate 100 may be formed on a silicon layer or connections to a first level metal. The photoresist layer 110 region may as line. Next, as Shown in FIG. 4, a first oxide layer 120 is formed as a dielectric material layer. The first oxide layer 120 can be formed by a thermal oxidation process or can be suitably deposited of any other dielectric material such as nitride or BPSG (boro-phosphor-silicate glass). Other suitable dielectric materials can also be deposited or spin on glass (SOG). And other method can used mixing of silane(SiH 4 ) and hydrodioxide (H 2 O 2 ) solution deposited on the substrate 100 formed siliconoxide(SiO 2 ) layer. The operate temperature can controlled under room temperature, and backing temperature remained about 100° C. In this embodiment deposition of silane with hydrodioxide is preferred method. FIG. 5 shows a subsequent illustrative stage in this invention. The first oxide layer 120 is etched anisotropically or isotripically, using known methods, then exposing part of plug-like structure 110 . Next, like as reverse-transcription, the plug-like structure 110 is then removed from first oxide layer 120 formed cavity (hole) 115 . The width of cavity (hole) 115 is W 2 , referring to FIG. 6 . Next, shown in FIG. 7, a conformal second oxide layer 130 is deposited over the remaining portions of first oxide layer 120 and the cavity (hole) 115 . The second oxide layer 130 is formed as a dielectric material layer. Dielectric material such as nitride or BPSG (boro-phosphor-silicate glass). Other suitable dielectric materials can also be deposited. Second oxide layer 130 has a thickness W 3 . Shown in FIG. 8 , next step, the second oxide layer 130 is etched anisotropically, using known methods, to form sidewall spacer 140 a , 140 b in the cavity (hole) 115 . The width of each spacer 140 a , 140 b is W 3 . Thus, original cavity (hole) 115 width is W 2 , the width of two spacer of cavity inside is double W 3 . So, when width W 2 of cavity (hole) 115 subtract width double W 3 of spacer 140 a and 140 b , finally formed width W 4 of cavity 150 . The width W 4 of cavity 150 is than original cavity (hole) 115 smaller. Use this method, that can controlled thickness of deposited second oxide layer 130 obtained to expect the width of cavity 150 . Therefor, the resolution of lithographic techniques are not limited. Apply to this invention make down size of a contact hole, the smallest line width or line-to-line separation. While the present invention has been described in an illustrative manner, it should be understood that the terminology used is intended to be in a nature of words of description rather than of limitation. Furthermore, while the present invention has been described in terms of a preferred embodiment, it is to be appreciated that those skilled in the art will readily apply these teachings to other possible variations of the inventions.