Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of... – Insulative material deposited upon semiconductive substrate
Reexamination Certificate
2001-05-22
2003-06-17
Cuneo, Kamand (Department: 2829)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
Insulative material deposited upon semiconductive substrate
C438S197000, C438S689000, C438S696000, C438S704000, C438S703000, C438S706000, C438S723000, C438S724000, C438S725000, C438S740000, C438S745000
Reexamination Certificate
active
06579812
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method for removing a polymer, and more particularly to a process for removing a polymer and reducing oxide loss.
2. Description of the Prior Art
As semiconductor devices, such as Metal-Oxide-Semiconductor devices, become highly integrated the area occupied by the device shrinks, as well as the design rule. With advances in the semiconductor technology, the dimensions of the integrated circuit (IC) devices have shrunk to the deep sub-micron range. When the semiconductor device continuously shrinks in the deep sub-micron region, some problems described below are incurred due to the process of scaling down.
The evolution of integrated circuits has evolved such that scaling down the device geometry is required. In the deep sub-micron technology of semiconductors, it's necessary that the protected layer of polymer be formed on the etched sidewall by way of using a reactive gas with a high Carbon/Fluorine (C/F) ratio in order to control the etched profile. Nevertheless, before the next process, the protected layer of polymer has to be stripped, otherwise poor results during the follow-up processes may occur. In general, the method for stripping the protected layer of polymer is a wet etching process. For the conventional wet etching process, a large amount of the oxide layer will be lost when the polymer is stripped. Controlling the thickness of the oxide layer is very important in the below deep sub-micron region. Especially, when the design rule is scaled down, it is more difficult to control or keep the thickness of the oxide layer.
Furthermore, in the conventional wet etching process, the sacrificing oxide layer reduces about 20 to 30 Å during the polymer stripping, with a possibility of the oxide layer being totally removed. If the thickness of the sacrificing oxide layer is to thin, it will affect the follow-up implanting process. On the other hand, the Oxide-Nitride-Oxide layer that is the stacked structure on the memory array or periphery region, the thickness of the oxide layer must be exactly controlled. If the thickness of the oxide layer experiences a great loss during the conventional wet etching process, a possible shift in electricity will reduce the performance of the device. Therefore, the conventional process for removing the polymer is a complex process. The thickness of the oxide layer is hard to control, and will not rework, this in return increases cost.
In accordance with the above description, a new and improved method for removing the residual polymer is therefore necessary, so as to raise the yield and quality of the follow-up process.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method is provided for removing the residual polymer that substantially overcomes the drawbacks of the above mentioned problems that arise from conventional methods.
Accordingly, it is a main object of the present invention to provide a method for removing the polymer. This invention can strip the polymer protected layer by way of using the Ultra Dilute Hydrofluoric Acid (UDHF) with high flow rate, so as to reduce the loss of the oxide layer. Hence, the present invention is appropriate for deep sub-micron technology in providing semiconductor devices.
Another object of the present invention is to provide a process for removing the residual polymer. The present invention can perform a wet etching process as a Standard Clean 1 (SC1) with a low temperature by way of using a solution of mixed-acid (Amonia Peroxide Mixture; APM) to completely remove the protected layer of polymer and hence a decrease in oxide loss. Furthermore, this invention can reduce the particles from Sulfuric acid Peroxide Mixture (SPM), and keep the thickness of oxide so that the characteristics of the devices does not shift. Therefore, this invention can reduce the complexity of the conventional process and hence reduce costs. Thus, the present invention can correspond to economic effect.
In accordance with the present invention, a new method for forming the semiconductor devices is disclosed. First of all, a semiconductor substrate that has a memory array and a periphery region thereon is provided, wherein the memory array and the periphery region have a conducted layer, individually. Then an oxide layer or an oxide-nitride-oxide layer is formed on the conducted layer. Afterward, forming a photoresist layer on the oxide layer and defining the photoresist layer of the periphery region. The oxide layer and the conducted layer of the periphery region are etched until exposing the substrate surface of the periphery region by way of using a dry etching process and the photoresist layer as an etching mask. After the dry etching process is finished, a protected layer of the polymer will be formed on the etched sidewalls, so as to keep the etched profile. A wet etching process having a ultra dilute hydrofluoric acid (UDHF) or a mixed-acid solution SC1 is then performed to strip the protected layer of the polymer, so as to avoid the oxide loss.
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patent: 6242350 (2001-06-01), Tao et al.
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Cuneo Kamand
Kilday Lisa
Macronix International Co Ltd.
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