Method for removing lattice defect in bonding pad region of semiconductor device
Technical Field
The present invention relates to a method for removing lattice defects in a PAD (PAD) area of a semiconductor device, and more particularly, to a method for removing lattice defects in a PAD (PAD) area of a semiconductor device using an organic solvent (EKC, ACT, etc.) cleaning and an argon plasma sputter repair process, and more particularly, to a method for removing lattice defects in a PAD (PAD) area of a dynamic random access memory (hereinafter, referred to as DRAM) using an organic solvent (EKC, ACT, etc.) cleaning and an argon plasma sputter repair process.
Background
Semiconductor devices include various types of active devices, for example, a Dynamic Random Access Memory (DRAM) is a semiconductor device having a multi-layer structure, and in order to connect members formed in respective film layers together to constitute a complete DRAM and to connect the DRAM with other semiconductor devices or other electronic components to constitute a desired electronic circuit module, a number of pads, which are extremely important connecting members, must be formed to accomplish the connections, and thus, good conductivity and high reliability of the pads are required, and lattice defects in pad regions adversely affect the conductivity and high reliability of the pads.
The pad forming process of the general semiconductor device includes the following steps; step 1, forming a conductive layer, for example, an aluminum or aluminum alloy layer, on a substrate on which other members of a semiconductor device have been formed; step 2, coating Photoresist (PR) on the aluminum or aluminum alloy layer; step 3, photoetching and corroding the conducting layer by using a mask with a pad pattern, and patterning the conducting layer to form the pad; step 4, performing Ashing (Ashing) treatment to remove the photoresist on the conductive layer; step 5, cleaning with an organic solvent to remove the photoresist; step 6, forming an aluminum alloy passivation layer on the formed conducting layer with the pad pattern; and 7, forming a polyimide protective layer on the conductive pad on which the aluminum alloy passivation layer is formed, thereby forming the pad.
In the existing pad forming process, since the etchant used in step 3 of lithographically etching and patterning the conductive layer is fluorine-containing etchant, fluorine ions escaping from the etchant can cause lattice defects to occur in the pad region in the subsequent process step, and the lattice defects in the pad region can negatively affect the conductivity and high reliability of the pad. In order to prevent the generation of lattice defects in the pad region, the interval time (Q time) between step 6 (forming an aluminum alloy passivation layer on the conductive layer having the pad pattern formed) and step 7 (forming a polyimide protective layer on the conductive pad having the aluminum alloy passivation layer formed) is strictly controlled in the conventional process. However, this method of defining the interval time (Q time) between the aluminum alloy passivation layer forming step (step 6) and the polyimide protective layer forming step (step 7) is not particularly reliable, and once the Q time is exceeded, Crystals Defect may be generated in the pad region. Further, lattice defects were found in the pad region even after the formation of the polyimide protective layer. These defects can negatively impact the reliability of the DRAM.
Disclosure of Invention
The method of the present invention is proposed to overcome the above-mentioned drawbacks. The invention aims to provide a method for removing lattice defects in a pad area by using organic solvent (EKC, ACT and the like) cleaning and argon plasma sputtering repair treatment.
The method for removing lattice defects in a pad region according to the present invention is to perform step S1 after the aluminum alloy passivation layer forming step (step 6) of the above-described conventional pad forming method and before the polyimide protective layer forming step (step 7), to detect whether or not lattice defects exist in the pad region, and if lattice defects exist in the pad region, to perform step S2, to perform cleaning treatment using an organic solvent (EKC, ACT, etc.), that is, cleaning treatment of the pad region where the aluminum alloy passivation layer is formed using an Amine-based organic solvent containing an Amine (Amine) group, to remove the lattice defects in the pad. If lattice defects are present in the pad region after the polyimide protective layer is formed on the pad region subjected to the cleaning treatment with the organic solvent (EKC, ACT, etc.), it is checked in step S3 whether lattice defects are present in the pad region, and if lattice defects are still present in the formed pad region, in this case, in order to remove the lattice defects in the pad region, it is necessary to perform step S4 to perform the argon (Ar) plasma sputtering repair treatment to further remove the lattice defects in the pad region.
According to one technical scheme of the invention, after the step of forming the aluminum alloy passivation layer of the bonding pad and before the step of forming the polyimide protective layer on the aluminum alloy passivation layer, whether lattice defects exist in the bonding pad area or not is detected, and if the lattice defects exist in the bonding pad area, cleaning treatment of organic solvent (EKC, ACT and the like) is carried out to remove the lattice defects in the bonding pad area. The organic solvent (EKC, ACT, etc.) cleaning treatment is carried out with an amine base, i.e., an organic solvent containing an amine group, e.g., EKC-270/265 or ACT-940. Removing fluorine ions (F) evolved by the etchant+) Lattice defects are generated in the pad region. If lattice defects still exist in the formed pad region after the polyimide protective layer is formed on the pad region subjected to the cleaning treatment with an organic solvent (BKC, ACT, etc.), argon (Ar) plasma is necessary to remove the lattice defects in the pad regionAnd carrying out bulk sputtering repair treatment to further eliminate lattice defects in the pad area.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the principles and features of the invention and, together with the description, serve to explain the principles and features of the invention. Wherein,
FIG. 1 is a flow chart of a prior art pad formation process for a semiconductor device;
FIG. 2 is a flow chart of a pad formation process for a semiconductor device in accordance with the present invention;
FIG. 3 is a flow chart of an organic solvent (EKC, ACT, etc.) cleaning process;
fig. 4 is a photomicrograph of a lattice defect in a pad region taken with an Optical Microscope (OM);
FIG. 5 is a photomicrograph of a lattice defect in a pad region taken with a tiltable electron scanning microscope (Jo-SEM); and
FIG. 6 is a photograph of a spectrum of the result of analyzing a component by energy dispersive X-ray spectroscopy (EXD) analysis.
Detailed Description
Fig. 2 is a flow chart of a pad formation process of a semiconductor device according to the present invention. The pad forming process flow of the semiconductor device according to the present invention shown in fig. 2 is to add step S1 (detecting whether there is lattice defect in the pad region) between step 6 and step 7 of the pad forming process flow of the conventional semiconductor device shown in fig. 1; and a step S2 (when it is detected in step S1 that there is a lattice defect in the pad region, an organic solvent (EKC, ACT, etc.) cleaning process is performed). If, after step 7, i.e., after forming the polyimide protective layer on the pad region, step S3 is performed to detect whether there is a lattice defect in the pad region, and if it is detected that there is still a lattice defect in the pad region in step S3, step S4 is performed to perform an argon (Ar) plasma sputtering repair process on the pad region to remove the lattice defect in the pad region.
Fig. 2 is a flow chart of a pad formation process of a semiconductor device according to the present invention. The pad forming process flow of the semiconductor device according to the present invention shown in fig. 2 is to add step S1 (detecting whether there is lattice defect in the pad region) between step 6 and step 7 of the pad forming process flow of the conventional semiconductor device shown in fig. 1; and step S2 (when the presence of lattice defects in the pad region is detected in step S1, NEKC cleaning process is performed), and added after step 7 of the pad formation process flow of the conventional semiconductor device shown in fig. 1: step S3 (test for the presence of lattice defects in the pad region; and step S4 (argon (Ar) plasma sputtering repair process when the presence of lattice defects in the pad region is detected in step S3. steps S1 and S3 therein test for the presence of lattice defects in the pad region using an Optical Microscope (OM), and when lattice defects are found in the pad region, take a photomicrograph of the lattice-defective pad, and take a photomicrograph of the lattice-defective pad region using a tiltable electron scanning microscope (Jo-SEM).
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The method of removing lattice defects in a PAD Area (PAD) of a semiconductor device using organic solvent (EKC, ACT, etc.) cleaning and argon (Ar) plasma sputter repair process according to the present invention is described in detail below with reference to fig. 2 and 3. Fig. 2 is a flow chart of a pad formation process of a semiconductor device according to the present invention. FIG. 3 is a flow chart of an organic solvent (EKC, ACT, etc.) cleaning process.
The pad forming process flow of the semiconductor device according to the present invention shown in fig. 2 is to add step S1 (detecting whether there is a lattice defect in the pad region) between step 6 and step 7 of the pad forming process flow of the conventional semiconductor device shown in fig. 1; and a step S2 (when it is detected in step S1 that there is a lattice defect in the pad region, an organic solvent (EKC, ACT, etc.) cleaning process is performed). In step S1, an Optical Microscope (OM) is used to detect whether there is a lattice defect in the pad area, when the lattice defect is found in the pad area, a microscope photograph of the pad with the lattice defect is taken, and a tiltable electron scanning microscope (Jo-SEM) is used to take a microscope photograph of the pad area with the lattice defect. Then, step S2 is performed to perform EKC cleaning processing. Figure 3 is an EKC cleaning process flow diagram.
The following steps included in the EKC cleaning process flow shown in figure 3 were performed:
step S2-1, soaking the substrate with the aluminum alloy passivation layer formed on the pad conductive layer in an organic solvent, wherein the cleaning agent is amine base, namely an amine group-containing organic solvent, such as EKC270/265 or ACT 940, and when the substrate is soaked in the organic solvent, the temperature range of the organic solvent is 40-75 ℃, the preferred temperature range of the organic solvent is 65 ℃, the soaking time is 5-40 minutes, and the preferred soaking time is 20 +/-5 minutes;
step S2-2: soaking in NMP for 5-10 min at normal temperature;
step S2-3: rinsing with deionized water for 5-10 min
Step S2-4: drying the isopropanol (for 5-10 minutes at normal temperature); and (6) ending.
After the entire EKC cleaning process flow of step S2 is completed, step S7 is performed to form a polyimide passivation layer on the pad of the semiconductor device subjected to the cleaning process with an organic solvent (EKC, ACT, etc.), and then step S3 is performed to detect whether there is a lattice defect in the pad region, and if there is a lattice defect in the pad region, step S4 is performed to perform an argon (Ar) plasma sputtering repair process to further remove the lattice defect in the pad region.
The processing conditions in the argon (Ar) plasma sputtering repair process were:
the degree of vacuum in the argon (Ar) plasma sputter repair chamber was: the temperature of the liquid crystal is 50-200mTorr,
the electrical power used in the argon (Ar) plasma sputter repair process was: 300-500W of the reaction kettle is adopted,
argon (Ar) is flowed in the argon (Ar) plasma sputtering repair treatment,
the loss amount of the aluminum in the pad conducting layer after argon (Ar) plasma sputtering repair treatment is less than 1000 *.
By the above-described sputtering repair process with argon (Ar) plasma, lattice defects existing in the pad region are further eliminated, and it is possible to ensure that the pads of the semiconductor device have good conductivity and high reliability, whereby a semiconductor device with high reliability can be constructed.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the foregoing embodiments and descriptions are provided only to illustrate the principles of the invention, and that various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.