Low-etching cleaning solution for removing photoresist etching residues
Technical Field
The invention relates to a cleaning solution for removing photoresist etching residues.
Background
In the manufacture of semiconductor components, the application, exposure and imaging of photoresist layers are essential process steps for the patterning of the components. The residues of the resist material are removed completely before the next process step is performed at the end of the patterning, i.e. after coating, imaging, ion implantation and etching of the resist layer. Ion bombardment hardens the photoresist layer polymer during the doping step, thus making the photoresist layer less soluble and more difficult to remove. Heretofore, a two-step process (dry ashing and wet etching) has been generally used in the semiconductor manufacturing industry to remove this photoresist layer film. The first step is to remove most of the photoresist layer (PR) by dry ashing; the second step is to remove and clean the remaining photoresist layer by using a wet etching/cleaning process of the corrosion inhibitor composition, which is generally a cleaning solution cleaning/rinsing/drying process. In this process only the residual polymer resist layer and inorganic substances are removed and cannot attack the metal layer, e.g. the aluminium layer.
In the current wet cleaning process, the most used cleaning solution is a cleaning solution containing hydroxylamines and fluorine-containing substances, and typical patents of hydroxylamines cleaning solution include US6319885, US5672577, US6030932, US6825156, US5419779, and the like. Through continuous improvement, the corrosion rate of the solution to metal aluminum is greatly reduced, but the cleaning solution uses hydroxylamine which has the problems of single source, easy explosion and the like. Although the existing fluoride cleaning solution has great improvement, such as U.S. Pat. No. 5,972,862, U.S. Pat. No. 6,828,289, etc., the corrosion of metal and non-metal substrates cannot be well controlled, and the change of the characteristic dimension of the channel is easily caused after cleaning; on the other hand, wet cleaning equipment in some semiconductor enterprises is made of quartz, and the fluorine-containing cleaning solution corrodes the quartz and is corroded more rapidly along with the rise of temperature, so that the wide use of the equipment is influenced due to the incompatibility problem with the existing quartz equipment.
Although hydroxylamine and fluorine-containing cleaning solutions have been used relatively successfully in the semiconductor industry, due to their respective limitations and disadvantages, a third type of cleaning solution has been developed that does not contain either hydroxylamine or fluoride. For example, US5988186 discloses a cleaning solution containing a solvent, alcohol amine, water and gallic acid and esters thereof, which solves the problems of single source of hydroxylamine, safety and environmental protection, and unstable non-metal corrosion rate of fluorine-containing cleaning solutions. However, such cleaning solutions have limitations in their use due to their inclusion of neither hydroxylamine nor fluoride. Thus, despite the disclosure of some cleaning solution compositions, there is a need, and more recently, a need to prepare such cleaning solutions with a broader range of applications.
Disclosure of Invention
The invention aims to provide a low-cost semiconductor wafer cleaning solution capable of removing photoresist residues on a wafer, which does not contain hydroxylamine and fluoride; the corrosion rate to metal and nonmetal is low; and is compatible with quartz equipment.
The cleaning liquid of the present invention contains:
i. 40-70% of alcohol amine, preferably 50-65%;
alcohol ethers 10-40%, preferably 15-30%;
water 10-30%, preferably 15-25%;
0.1-10%, preferably 0.5-5%, of pyrogallol and its derivatives;
gallic acid and esters thereof, 0.1-5%, preferably 0.5-3%;
the contents are all mass percent contents, and the hydroxylamine and the fluoride are not contained.
In the present invention, the alcohol amine is preferably monoethanolamine, N-methylethanolamine, diethanolamine, triethanolamine, isopropanolamine, ethyldiethanolamine, N-diethylethanolamine, N- (2-aminoethyl) ethanolamine and diglycolamine.
In the present invention, the alcohol ether is preferably diethylene glycol monoalkyl ether and dipropylene glycol monoalkyl ether. Wherein, the diethylene glycol monoalkyl ether is preferably diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether; the dipropylene glycol monoalkyl ether is preferably dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether and dipropylene glycol monobutyl ether. From the viewpoint of environmental protection of alcohol ether, the alcohol ether is preferably dipropylene glycol monoalkyl ether; the alcohol ether is more preferably dipropylene glycol monomethyl ether in terms of all alcohol ether efficiency for removing photoresist residues.
In the present invention, the pyrogallol and/or the derivative thereof is preferably one or more selected from the group consisting of pyrogallol, 5-methylphthalic triphenol, 5-methoxyphthalic triphenol, 5-t-butylphthalic triphenol and 5-hydroxymethylpyrogallol.
In the present invention, the gallic acid and/or its ester is preferably one or more selected from gallic acid, methyl gallate, ethyl gallate, butyl gallate, octyl gallate, lauryl gallate and 1-gallic acid glyceride.
The cleaning solution of the invention can clean the photoresist residues on the wafer at 50 ℃ to 80 ℃. The specific method comprises the following steps: and soaking the wafer containing the photoresist residues in the cleaning solution at 50-80 ℃ for a proper time, taking out, rinsing and drying by using high-purity nitrogen.
The invention has the technical effects that:
1) the cleaning solution disclosed by the invention can effectively remove light resistance residues on metal wires (metal), through holes (via) and metal pads (Pad) wafers and simultaneously realize the inhibition on the corrosion of metal aluminum and nonmetal by binary compounding of pyrogallol and derivatives thereof with gallic acid and esters thereof;
2) the cleaning solution solves the problems of single hydroxylamine source, high price, easy explosion and the like in the traditional hydroxylamine cleaning solution;
3) the cleaning liquid has low non-metal corrosion rate; solves the problem of unstable nonmetal corrosion rate of the traditional fluorine cleaning solution, and is compatible with the quartz cleaning tank commonly used by the current semiconductor manufacturers.
Detailed Description
The reagents and starting materials used in the present invention are commercially available. The cleaning fluid can be prepared by simply and uniformly mixing the components.
TABLE 1 compositions and amounts of cleaning solutions in the Examples (EXAMPLES)
TABLE 2 Components and contents of cleaning solutions in respective proportions
Effects of the embodiment
In order to further examine the cleaning condition of the cleaning liquid, the invention adopts the following technical means: respectively immersing a metal wire (metal) wafer, a via (via) wafer and a metal Pad (Pad) wafer containing photoresist residues into cleaning solution, oscillating for 10-30 minutes at 50-80 ℃ by using a constant temperature oscillator at a vibration frequency of about 60 revolutions per minute, rinsing, washing and drying by using high-purity nitrogen. The cleaning effect of the photoresist residue and the etching of the wafer by the cleaning solution are shown in table 2.
TABLE 3 part of the cleaning conditions of the wafers of the examples and comparative examples
As can be seen from Table 3, the cleaning solution of the present invention has good cleaning effect on metal line (metal) wafers, via (via) wafers and metal Pad (Pad) wafers containing photoresist residues, has a wide range of use temperature, and does not corrode metal aluminum and non-metal silicon dioxide. As can be seen from comparative example 1 and example 11, the photoresist residue on the wafer is not completely removed by using the commonly used dimethylsulfoxide solvent, and the removal of the photoresist residue is facilitated by using alcohol ether as the solvent. As can be seen from comparative example 2, comparative example 3 and example 11, in the case where other components are identical and the cleaning operation conditions are also identical, if pyrogallol and its derivatives are not added, the photoresist residue on the wafer is not completely removed; if gallic acid and its ester are not added, corrosion of metallic aluminum will occur. The two substances are added simultaneously, so that the photoresist residues on the wafer can be removed simultaneously, and the problem of metal aluminum can not be caused. It can be seen from comparative example 4 and example 11 that, in addition to being less environmentally friendly, the addition of conventional pyrocatechol causes corrosion of the metallic aluminium.
It should be understood that wt% in the present invention refers to mass percentage.
The embodiments of the present invention have been described in detail, but the embodiments are merely examples, and the present invention is not limited to the embodiments described above. Any equivalent modifications and substitutions to those skilled in the art are also within the scope of the present invention. Accordingly, equivalent changes and modifications made without departing from the spirit and scope of the present invention should be covered by the present invention.