Patent Application
20080261384
1. Field of the Invention
The present invention relates to a method of fabricating an integrated circuit, and more particularly to a method of removing a photoresist layer and a method of fabricating a semiconductor device using the same.
2. Description of Related Art
In a process of manufacturing semiconductors, a great number of integrated circuits are frequently formed on substrates. A plurality of electronic devices such as transistors, diodes, capacitors, resistors and the like is often included in the integrated circuits. Fabrication of the electronic devices usually involves depositing, removing, and implanting ions at certain locations which can be facilitated by a photolithography process.
The photolithography process includes depositing a layer of photoresist material on a substrate at first. Then, patterns on a photomask are transferred to the photoresist material layer after being exposed to radiation passing through the photomask. Next, a portion of the photoresist material layer is removed by a developer, such that photoresist patterns are formed. The typical photoresist material is composed of photosensitive polymers, resin, and solvents. With a positive photoresist material, the exposed resist undergoing pyrolysis is removed by the developer. Conversely, with a negative photoresist material, the unexposed resist experiencing no cross-linking effect is removed by the developer. After the photoresist patterns are formed, a subsequent process such as an etching of a dielectric layer, the etching of a metal layer, or the ion implantation process is then be performed with use of the photoresist patterns as masks. The photoresist layer must be removed after the subsequent process is completed, and a dry etching method or a wet etching method may be adopted to remove the photoresist layer. In most cases, oxygen plasma may be employed in the dry etching method to oxidize the photoresist layer, while an organic solution or any other acid solution may be utilized in the wet etching method to remove the same. Afterwards, a cleaning process is carried out to remove the residual photoresist layer on a surface of the substrate or the impurities.
However, referring to
Referring to
The present invention provides a method of effectively removing a photoresist layer so as to avoid contamination of machinery or yield loss due to a popping defect of the photoresist layer.
The present invention provides a method of fabricating a semiconductor device so as to effectively remove a photoresist layer and to avoid contamination of machinery or yield loss due to a popping defect of the photoresist layer.
The present invention provides a method of removing a photoresist layer on which a process is performed to transform a surface of the photoresist layer to a crust. The crust covers a soft photoresist layer. Said method includes performing a first removing step and a second removing step. The first removing step denotes a removal of the crust so as to expose the soft photoresist layer, while the second removing step refers to a removal of the soft photoresist layer. The first and the second removing steps are performed in different chambers, and a temperature for performing the first removing step is lower than that for performing the second removing step and lower than a gasification temperature of a solvent in the soft photoresist layer.
According to one embodiment of the present invention, the temperature for performing the first removing step is lower than a gasification temperature of a solvent in the soft photoresist layer.
According to one embodiment of the present invention, the process is an ion implantation process.
According to one embodiment of the present invention, a dry stripping process is adopted in both the first removing step and the second removing step.
According to one embodiment of the present invention, the dry stripping process includes a plasma stripping process.
According to one embodiment of the present invention, the plasma stripping process adopted in the first removing step is performed in a pinning-down manner.
According to one embodiment of the present invention, the temperature at which the dry stripping process adopted in the first removing step is performed ranges from about 30° C. to 100° C.
According to another embodiment of the present invention, a wet stripping process is adopted in both the first removing step and the second removing step.
According to another embodiment of the present invention, the temperature at which the wet stripping process adopted in the first removing step is performed ranges from about 50° C. to 140° C.
According to still another embodiment of the present invention, a dry stripping process is adopted in one of the first and the second removing steps, and a wet stripping process is adopted in the other.
According to still another embodiment of the present invention, the dry stripping process includes a plasma stripping process.
According to still another embodiment of the present invention, the plasma stripping process adopted in the first removing step is performed in a pinning-down manner.
According to still another embodiment of the present invention, the dry stripping process is adopted in the first removing step and the temperature at which the dry stripping process is performed ranges from about 30° C. to 100° C.
According to still another embodiment of the present invention, the wet stripping process is adopted in the first removing step and the temperature at which the wet stripping process is performed ranges from about 50° C. to 140° C.
According to still another embodiment of the present invention, the process includes an ion implantation process.
The invention provides a method of fabricating a semiconductor device. The method includes forming a photoresist material layer on a substrate and patterning the photoresist material layer to form a first patterned photoresist layer and a second patterned photoresist layer. An area occupied by the first patterned photoresist layer is smaller than that occupied by the second patterned photoresist layer. Next, the first patterned photoresist layer and the second patterned photoresist layer are used as masks to perform an ion implantation process, such that a doped region is formed in the substrate. Here, a first crust is completely formed by the first patterned photoresist layer. A second crust is formed on a surface of the second patterned photoresist layer and a soft photoresist layer remains underlying the second crust. Thereafter, a first removing step is performed to remove the first crust and the second crust, such that the soft photoresist layer is exposed. Afterwards, a second removing step is performed to remove the soft photoresist layer. The first and the second removing steps are performed in different chambers, and a temperature for performing the first removing step is lower than that for performing the second removing step and lower than a gasification temperature of a solvent in the soft photoresist layer.
According to one embodiment of the present invention, the temperature for performing the first removing step is lower than a gasification temperature of a solvent in the soft photoresist layer.
According to one embodiment of the present invention, a dry stripping process is adopted in both the first removing step and the second removing step.
According to one embodiment of the present invention, the dry stripping process includes a plasma stripping process.
According to one embodiment of the present invention, the plasma stripping process adopted in the first removing step is performed in a pinning-down manner.
According to one embodiment of the present invention, the temperature at which the dry stripping process adopted in the first removing step is performed ranges from about 30° C. to 100° C.
According to another embodiment of the present invention, a wet stripping process is adopted in both the first removing step and the second removing step.
According to another embodiment of the present invention, the temperature at which the wet stripping process adopted in the first removing step is performed ranges from about 50° C. to 140° C.
According to still another embodiment of the present invention, a dry stripping process is adopted in one of the first and the second removing steps, and a wet stripping process is adopted in the other.
According to still another embodiment of the present invention, the dry stripping process includes a plasma stripping process.
According to still another embodiment of the present invention, the plasma stripping process adopted in the first removing step is performed in a pinning-down manner.
According to still another embodiment of the present invention, the dry stripping process is adopted in the first removing step and the temperature at which the dry stripping process is performed ranges from about 30° C. to 100° C.
According to still another embodiment of the present invention, the wet stripping process is adopted in the first removing step and the temperature at which the wet stripping process is performed ranges from about 50° C. to 140° C.
According to still another embodiment of the present invention, the first patterned photoresist layer covers an active region of the substrate.
The method of removing the photoresist layer disclosed in the present invention is capable of preventing contamination of machinery or yield loss of the substrate due to the popping defect of the photoresist layer.
The method of fabricating the semiconductor device disclosed in the present invention is able to effectively remove the photoresist layer and to avoid contamination of machinery or yield loss due to the popping defect of the photoresist layer.
In order to the make the aforementioned and other objects, features and advantages of the present invention comprehensible, a preferred embodiment accompanied with figures are described in detail below.
such that a crust covering a soft photoresist layer is formed on the surface of the photoresist layer. The process performed by using the solvent is, for example, an ion implantation process. The implanted ions are, for example, phosphorus, nitrogen, arsenic, antimony, carbon, germanium, boron, gallium, indium ions, and so forth.
In step 200, a first removing step is performed to strip the crust on the surface of the photoresist layer, such that the soft photoresist layer is exposed. A dry stripping process or a wet stripping process may be adopted in the first removing step. A temperature at which the dry stripping process is performed is lower than a gasification temperature of the solvent in the soft photoresist layer. In one embodiment, the temperature at which the dry stripping process is carried out ranges from about 30° C. to 100° C., for example. The dry stripping process is, for example, a plasma stripping process, which may be implemented in a machine having a single reaction chamber or a plurality of the reaction chambers. Gases adopted in said process are, for example, oxygen/hydrogen/nitrogen or oxygen/nitrogen. A pressure thereof, for example, should be more than 1.5 torr, preferably more than 5 torr. In one embodiment, said process is performed in a pinning-down manner, such that a predetermined temperature is closer to an actual temperature of the substrate. The temperature at which the wet stripping process is performed ranges from about 50° C. to 140° C. In one embodiment, the wet stripping process is performed in a chemical tank containing an organic solution or an inorganic solution. The organic solution may result in a structural damage to the photoresist so as to dissolve the same in the organic solution. The typical organic solution is, for example, acetone or aromatic solvents. On the contrary, the inorganic solution operates in a different way to remove the photoresist layer. Since the photoresist combining carbon, hydrogen and the like is organic, the inorganic solution is capable of dissolving the photoresist. The inorganic solution is, for example, sulfuric acid or hydrogen peroxide.
Next, in step 202, a second removing step is performed to remove the soft photoresist layer. The dry stripping process or the wet stripping process may be adopted in the second removing step which is performed at a higher temperature than the first removing step 200 and in a different reaction chamber from the one used in the first removing step 200. Here, the reaction chamber may refer to the reaction chamber in which the dry stripping process is performed or to the chemical tank in which the wet stripping process is carried out. In one embodiment, the second removing step 202 is a dry stripping process, and a temperature at which the dry stripping process is carried out is more than 200° C. The dry stripping process is, for example, a plasma stripping process, which may be implemented in a single reaction chamber or a machine having a plurality of the reaction chambers. Gases adopted in said process are, for example, oxygen/hydrogen/nitrogen or oxygen/nitrogen. A pressure thereof, for example, should be more than 1.5 torr, preferably more than 5 torr. In one embodiment, the wet stripping process is performed in a chemical tank containing an organic solution or an inorganic solution. The typical organic solution is, for example, acetone or aromatic solvents. The typical inorganic solution is, for example, sulfuric acid or hydrogen peroxide.
In one embodiment, a dry stripping process may be adopted in both the first removing step 200 and the second removing step 202. For example, an in-situ plasma stripping process is implemented in different reaction chambers of the same machine or an ex-situ plasma stripping process is carried out in the different reaction chambers of different machines in similar or dissimilar types or configurations. Gases adopted in said process are, for example, oxygen/hydrogen/nitrogen or oxygen/nitrogen. The first removing step is performed in a pinning-down manner. A temperature at which the first removing step 200 is implemented is lower than both the temperature at which the second removing step 202 is carried out and a gasification temperature of the solvent in the soft photoresist layer.
In another embodiment, a wet stripping process may be adopted in both the first removing step 200 and the second removing step 202. For example, the process of removing the photoresist layer is performed in different chemical tanks containing similar or dissimilar chemicals. The chemicals in the chemical tanks are, for example, the organic solution or the inorganic solution. The typical organic solution is, for example, acetone or aromatic solvents. The typical inorganic solution is, for example, sulfuric acid or hydrogen peroxide. A temperature at which the first removing step 200 is implemented is lower than both the temperature at which the second removing step 202 is carried out and a gasification temperature of the solvent in the soft photoresist layer.
In still another embodiment, a dry stripping process e.g. a plasma stripping process is adopted in the first removing step 200. Gases adopted in said process are, for example, oxygen/hydrogen/nitrogen or oxygen/nitrogen, and the first removing step 200 is performed in a pinning-down manner to remove the crust. On the other hand, a wet stripping process including stripping the soft photoresist layer in a chemical tank having chemicals may be adopted in the second removing step 202. Said wet stripping process is performed in the chemical tank containing an organic solution or an inorganic solution. The typical organic solution is, for example, acetone or aromatic solvents. The typical inorganic solution is, for example, sulfuric acid or hydrogen peroxide. A temperature at which the first removing step 200 is implemented is lower than both the temperature at which the second removing step 202 is carried out and a gasification temperature of the solvent in the soft photoresist layer.
Referring to
Next, referring to
Thereafter, referring to
Afterwards, referring to
Then, referring to
With lower temperature, lower than 100° C., for example, the first removing step of the present invention prevents contamination of machinery or yield loss due to a popping defect of the photoresist layer. The popping defect is caused by evaporation of the solvent in the photoresist layer. On the contrary, the second removing step is performed at a higher temperature, and thus the residual soft photoresist layer is effectively stripped. In comparison with a process of removing the photoresist layer with use of a high-temperature RCA, the stripping process of the photoresist layer disclosed in the present invention prevents a significant loss of an oxide layer due to the use of the high-temperature RCA.
Moreover, in comparison with a process of removing the photoresist layer with use of a low-temperature RCA, the stripping process of the photoresist layer disclosed in the present invention avoids incomplete removal of the photoresist layer on account of the use of the low-temperature RCA. In addition, since the first and the second removing steps are implemented in different reaction chambers, contamination caused by the popping defect of the photoresist layer can be avoided, and the throughput can also be increased.
A substrate is provided. A patterned photoresist layer is already formed on the substrate, and an ion implantation process is already performed thereon. Next, a first removing step is performed in a first chamber of a plasma machine in a pinning-down manner. A temperature at which the first removing step is performed is 90° C. Gases adopted in said step is O2 and N2H2. A pressure thereof is 5 torr. Thereafter, a second removing step is performed in a different chamber of the same plasma machine The temperature at which the second removing step is performed is 250° C. The gases adopted in said step is O2 and N2H2. The pressure thereof is 5 torr. Afterwards, defects on the substrate are measured. Finally, a cleaning process is performed, and the defects on the substrate are again measured. The test results are shown in table 1. Comparative Example 1 is performed using the prior art method.
It is understood from table 1 that the present invention can significantly reduce the defects arisen from the popping defect of the photoresist layer and further raise yield of the fabricating process.
Although the present invention has been disclosed above by the preferred embodiments, they are not intended to limit the present invention. Anybody skilled in the art can make some modifications and alteration without departing from the spirit and scope of the present invention. Therefore, the protecting range of the present invention falls in the appended claims.
