CN111474833A - Photoetching wetting liquid and application thereof - Google Patents

Abstract

The invention discloses a photoetching wetting liquid, which contains water, organic alkali and an active agent; the organic alkali is guanidine organic alkali or piperazine organic alkali; the activator is a composition of an EO/PO block copolymer and a water-soluble polymer. The photoetching wetting liquid is suitable for 45 nm, especially 14nm and below photoetching process, can further reduce the collapse rate of the photoresistance and improve the roughness of the pattern, forms more precise and complete photoresistance pattern, achieves the technical index of the process requirement, and improves the yield and the reliability.

Description

Photoetching wetting liquid and application thereof

Technical Field

The invention relates to a photoetching wetting liquid and application thereof.

Background

The photoetching process plays a crucial role in the manufacture of semiconductor chips, and mainly comprises steps of photoresist spin coating, exposure, development, cleaning and the like, the photoetching process before 14nm can enter the next procedure after being directly spin-dried by ultrapure water after development, but with the rapid improvement of technical nodes and integration level, the extreme miniaturization of patterns not only raises higher requirements on the performance of the photoresist, but also makes more strict requirements on the photoresist patterns after development, especially 14nm and the following process nodes, with the extreme reduction of line width and the increase of depth-to-width ratio, defects are easily caused by collapse of the photoresist, and in addition, the line edge roughness L ER (line edge roughness) and L WR (line width roughness) after exposure also need to be controlled more precisely so as to avoid the deterioration of yield.

Disclosure of Invention

In order to further reduce the collapse rate of the light resistance and improve the roughness of the pattern so as to form a more fine and complete light resistance pattern, achieve the technical index of the process requirement and improve the yield and the reliability, the invention provides a photoetching wetting liquid, which contains water, organic alkali and an active agent; the organic alkali is guanidine organic alkali or piperazine organic alkali; the activator is a composition of an EO/PO block copolymer and a water-soluble polymer.

Preferably, the guanidine organic base is selected from monoguanidine and derivatives thereof, and the chemical structural formula is as follows:

wherein, R1, R2, R3 are each independently H, hydrocarbyl, or heterocyclic substituent;

or the guanidine organic base is selected from biguanide and derivatives thereof, and the chemical structural formula is as follows:

wherein Ra, Rb, Rc, Rd are each independently H, a hydrocarbyl group, an aromatic group, or a heterocyclic substituent.

Preferably, the piperazine organic base is selected from piperazine and derivatives thereof, and the chemical structural formula is as follows:

wherein Rs1, Rs2 are each independently H, methyl, ethyl, amino, hydroxymethyl, or hydroxyethyl.

Preferably, the EO/PO block copolymer has the formula:

RO-[-(EO)m(PO)n-]-H

wherein R is a hydrocarbon chain with 5-20 carbon atoms, m is the number of EO repeating units, n is the number of PO repeating units, and the sum of m and n is less than 20;

the water-soluble polymer is polyethylene glycol (PEG); the molecular weight of the polyethylene glycol is 200-600.

Preferably, the organic base is contained in an amount of 0.05 to 1% by mass (more preferably 0.05 to 0.1%) by mass, the EO/PO block copolymer is contained in an amount of 0.001 to 1% by mass (more preferably 0.02 to 0.1%) by mass, and the water-soluble polymer is contained in an amount of 0.001 to 1% by mass (more preferably 0.01 to 0.05%) by mass.

Preferably, the photoetching wetting liquid also contains a high-boiling-point organic solvent; the high boiling point organic solvent is selected from propylene glycol, ethylene glycol, propylene glycol and glycerol; the content of the high-boiling-point organic solvent is 0.5-5% (more preferably 1.0-2.0%) by mass.

Preferably, the photoetching wetting liquid also contains a mildew-proof bactericide; the mildew-proof bactericide is a quaternary ammonium salt bactericide; the mass percentage of the mildew-proof bactericide is 0.001-0.005%.

The invention also provides a semiconductor photoetching process, after the photoresistance is developed, the photoetching wetting liquid is adopted to spin-wash the surface of the photoresistance, so as to remove impurities in the structure and form clear and complete photoresistance patterns.

The 14nm and below photoetching process has higher requirements on the collapse rate and the intra-cluster roughness, particularly the 7 nm technology photoetching process, the formula of the photoresist is changed, and the collapse rate and the surface roughness caused by the fine pattern become more and more key factors influencing the yield, so that the performance needs to be further improved to meet the more advanced process. The method of forming a pattern on a silicon substrate of the present invention is as follows: firstly, spin-coating a photoresist material on a substrate to form a film, then exposing and developing, and then processing by using the photoetching wetting liquid to obtain a cleaning pattern. The photoetching wetting liquid is suitable for 45 nm, especially 14nm and below photoetching process, can further reduce the collapse rate of the photoresistance and improve the roughness of the pattern, forms more precise and complete photoresistance pattern, achieves the technical index of the process requirement, and improves the yield and the reliability. The photoetching wetting liquid has outstanding cost performance, and all the additives are environment-friendly additives and can be biodegraded.

Organic alkali (guanidine organic alkali or piperazine organic alkali) is added into the formula of the photoetching wetting liquid, and the organic alkali can generate cross-linking reaction with functional groups on the surface of the photoresistor, so that the mechanical property of the surface of the photoresistor is improved, collapse or deformation is avoided, and the collapse rate can be improved.

The EO/PO segmented copolymer is added into the formula of the photoetching wetting liquid, so that the dynamic and static surface tension of the wetting liquid can be reduced, the deformation and the breakage of a light resistance caused by a capillary phenomenon are eliminated, and the collapse rate is reduced.

The water-soluble polymer (polyethylene glycol) is added into the formula of the photoetching wetting liquid, so that the effect of solubilizing the active agent can be achieved, and the solubility and uniformity of the active agent are improved.

The high boiling point organic solvent (propylene glycol, ethylene glycol, propylene glycol and glycerol) is added into the formula of the photoetching wetting liquid, so that the dual functions of defoaming and dissolving assisting can be achieved, and the surface tension fluctuation caused by foam can be further inhibited.

The formula of the photoetching wetting liquid is added with the mildew-proof bactericide (quaternary ammonium salt bactericide) to prevent bacteria and mildew from forming in a high-temperature and high-humidity environment, and the aim of sterilizing is achieved by inhibiting the growth environment of the bacteria through the chamber resistance generated by the comprehensive action of electrostatic force, hydrogen bonds and active agent molecule protein molecules.

The photoetching wetting liquid avoids the influence of capillary phenomenon by changing the surface tension, enhances the mechanical strength of the photoresistor at the same time, further avoids the collapse of the photoresistor, and slightly changes the appearance of the surface of the photoresistor after the surface of the photoresistor is contacted by the active agent, thereby improving the roughness.

Detailed Description

The following further describes embodiments of the present invention with reference to examples. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

The forming method of forming the photoresist pattern on the silicon substrate comprises the following steps: spin coating a photoresist material on a silicon substrate to form a film, using an ArF ultraviolet light source or an electron beam light source for exposure, baking and developing, and further using the photoetching wetting liquid for treatment. The size of the finally formed pattern (including line width, space width, plug through hole and connecting through hole) is 7 nm, the collapse rate and surface roughness of the pattern area are obviously improved, and specific test results are shown in table 1.

Table 1 test results of collapse Rate and surface roughness of Pattern region

In table 1:

the percentage contents are all mass percentage contents.

The general formula of the EO/PO block copolymer is as follows: RO- [ - (EO) m (PO) n- ] -H; wherein R is a hydrocarbon chain having 5 to 20 carbon atoms, m is the number of repeating units of EO, n is the number of repeating units of PO, and the sum of m and n is less than 20.

The collapse rate of the photoresist: the ratio of collapse rates of the photoresist after wetting and cleaning with different aspect ratios is defined, and the larger the aspect ratio is, the smaller the collapse rate is, which indicates that the technical effect of the photoetching wetting liquid is better;

a: the depth-to-width ratio is 5, and the collapse rate of the light resistor is obviously improved;

b: the depth-to-width ratio is more than 3 and less than 5, and the collapse rate of the light resistance is obviously improved;

c: the depth-to-width ratio is less than 3, and the collapse rate of the photoresistance is obviously improved.

Line deviation: the line width deviation of dense lines and sparse lines after exposure is referred to;

d1: the deviation meets the process requirements;

d2, deviation exists, but the process requirement is basically met;

d3: the deviation is large and can not meet the process requirement.

Hole roundness: the shape deviation degree of the fine hole and the roughness of the edge are shown;

y1: the roundness reaches the standard, and the edge is clear;

y2; the roundness has a small deviation and the edge is clear;

y3: the roundness deviation is large, and the edge is fuzzy.

Surface roughness: it means the roughness and fineness of the end face of the line;

r1: the roughness meets the process requirements;

r2: the roughness is slightly poor, but the yield is not influenced;

r3: the roughness is poor and can not meet the process requirement.

In addition, the solubilizing and foam suppressing effects of PEG and glycerol are shown in table 2:

TABLE 2 solubilization and foam inhibition of PEG and Glycerol

In table 2:

the percentage contents are all mass percentage contents.

The general formula of the EO/PO block copolymer is as follows: RO- [ - (EO) m (PO) n- ] -H; wherein R is a hydrocarbon chain having 5 to 20 carbon atoms, m is the number of repeating units of EO, n is the number of repeating units of PO, and the sum of m and n is less than 20.

Solubility:

a: insufficient dissolution and oil content; b: the solubility is improved; c: a true solution was formed.

Foaming:

a: the foam is heavy; b: improving foam; c: substantially free of foam.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the technical principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. A lithographic fountain solution comprising water, an organic base, and an activator;

the organic alkali is guanidine organic alkali or piperazine organic alkali;

the activator is a composition of an EO/PO block copolymer and a water-soluble polymer.

2. The lithographic fountain solution of claim 1, wherein the guanidine organic base is selected from the group consisting of monoguanidine and its derivatives, and has the following chemical formula:

wherein, R1, R2, R3 are each independently H, hydrocarbyl, or heterocyclic substituent;

or the guanidine organic base is selected from biguanide and derivatives thereof, and the chemical structural formula is as follows:

wherein Ra, Rb, Rc, Rd are each independently H, a hydrocarbyl group, an aromatic group, or a heterocyclic substituent.

3. The lithographic fountain solution of claim 1, wherein the piperazine-based organic base is selected from piperazine and its derivatives, and has the following chemical formula:

wherein Rs1, Rs2 are each independently H, methyl, ethyl, amino, hydroxymethyl, or hydroxyethyl.

4. The lithographic fountain solution of claim 1, wherein the EO/PO block copolymer has the following general formula:

RO-[-(EO)m(PO)n-]-H

wherein R is a hydrocarbon chain with 5-20 carbon atoms, m is the number of EO repeating units, n is the number of PO repeating units, and the sum of m and n is less than 20;

the water-soluble polymer is polyethylene glycol; the molecular weight of the polyethylene glycol is 200-600.

5. The lithographic fountain solution of claim 1, wherein the organic base is present in an amount of 0.05 to 1% by mass, the EO/PO block copolymer is present in an amount of 0.001 to 1% by mass, and the water-soluble polymer is present in an amount of 0.001 to 1% by mass.

6. The lithographic fountain solution of claim 1, further comprising a high boiling point organic solvent; the high boiling point organic solvent is selected from propylene glycol, ethylene glycol, propylene glycol and glycerol.

7. The lithographic fountain solution of claim 6, wherein the high boiling point organic solvent is present in an amount of 0.5-5% by weight.

8. The lithographic fountain solution of claim 1, further comprising a mildewcide; the mildew-proof bactericide is a quaternary ammonium salt bactericide.

9. The lithographic fountain solution of claim 8, wherein the anti-mold bactericide is present in an amount of 0.001-0.005% by weight.

10. A semiconductor lithography process, characterized in that after developing a photoresist, the photoresist surface is spin-washed using the lithography fountain solution of any one of claims 1 to 9 to remove impurities in the structure and form a clear and complete photoresist pattern.