JPS58107535A - Formation of negative type resist film - Google Patents

Abstract

PURPOSE:To obtain a negative type resist having high reliability efficiently, by placing a base plate on the grounded electrode of parallel flat plate type electrodes facing each other in a reaction chamber, and forming a polymerization film on said base plate by a small amt. of high frequency wave power, in forming a resist film by a plasma polymn. method. CONSTITUTION:A silicon base plate 2 is placed on a stand in a reaction chamber 1, the stand is also used as a grounded electrode, cooled by passing cooling water, and a flat plate electrode 3 is connected through a regulation circuit 4 with a high-frequency wave power supply 5. The inside of the chamber is evacuated to 2X10<-5>Torr, and a gaseous monomer is introduced from a monomer source 8 through a valve 9 and a tube 6 together with a carrier gas supplied through a valve 10. <=1W/cm<2> high frequency wave power is applied to the electrode 3 and the electrode used also as the stand to produce a plasma polymn. film on the base plate 2, thus permitting negative type resist film soluble in a developing soln. to be efficiently formed in a short time, and this resist film to be suitable for the lithographic technique usable for fabrication of semiconductor integrated circuits.

Description

[Detailed description of the invention] (1) Technical field of the invention Himi 911 is an electron beam, X*, ion beam, and ultraviolet.

This article relates to a method for forming a resist film used in phosphorography technology that uses radiation such as deep ultraviolet radiation.

I! In detail, only the areas that were irradiated with radiation!
It relates to an improvement in the method of forming a negative resist film by the Goodsma polymerization method to form a pattern. Currently, photolithography is widely used in the production of semiconductor integrated circuits.In some areas, even higher-precision electron beam mist light has begun to be adopted.Resist materials and resist forming techniques for this purpose In the manufacturing process of electronic components, the so-called dry process is often used due to its high-precision fine pattern formation and various ease of use, and there are also proposals to use the dry process to form resists. A0 (3) Conventional technology and problems The conventional method for forming a resist film is resist poly!
There is a spin coding method that uses a solution of - dissolved in a coating solvent such as an organic solvent.The disadvantages of this method are as follows.
(1) The synthesis of the above resist polymer is a mono! - Purification 0 polymerization reaction of poly! Resist
If the polymer solution is stored and dust etc. gets mixed in between VHB or some of the dissolved polymer becomes sticky and becomes a gel-like substance, the solution should be filtered, centrifuged, etc. before application. It is necessary to remove these impurities by treatment.0(3)
It is necessary to perform a heat treatment called pre-bake before irradiation with radiation to remove the coating solvent and remove the narrow distortion introduced during coating. (4) As the film thickness decreases, defects called pinholes increase. 0 Especially when the film thickness is less than several thousand λ, the occurrence of pinholes becomes noticeable.◎ On the other hand, attempts have been made to form negative resists by applying plasma polymerization methods (Japanese Patent Laid-Open No. 134366/1983, etc.)
These methods apply electric power from the outside of the reaction vessel using a coil or the like, which causes the problem that the rate of formation of the membrane is extremely slow. When 1 to 8 is formed using the installed plasma polymerization method, the polymer film is highly crosslinked and becomes insoluble in solvents.
It is difficult to form a negative resist film.The purpose of the present invention is to eliminate each of the disadvantages of the conventional technology,
Another object of the present invention is to provide a method for forming a negative temperature resist film that is efficient and highly reliable.

(5) Structure of the Invention The above object is to provide a method for forming a resist film by plasma polymerization according to the present invention, in which a KI&plate is installed on the ground side electrode of opposing parallel plate type electrodes in a reaction vessel. , the image-wave power applied to the parallel plate electrodes is approximately I W/C
This can be achieved by using a method for forming a negative resist film, which is characterized in that a polymer film soluble in a developer is formed on a substrate using a predetermined small electric power of 11 or less.

As a result of intensive study on plasma polymerization method, the present inventor found that the high-frequency power applied to the l[O solubility formed by plasma polymerization method, mono! They discovered that the pressure and flow rate of - greatly depended on the flow rate, and took advantage of this phenomenon.6 In other words, a polymer film was formed by plasma polymerization using a reactor equipped with parallel plate type electrodes facing each other in a reaction vessel. When doing so, the substrate is installed on the ground side electrode, and the polymer film formed is soluble in the developer, and the applied power is small and monolithic, at about IW/m or less! -The pressure is less than a few Torr, and it's monotonous! - Plasma polymerization is carried out under polymerization conditions where the flow rate is relatively large. 4$K. There are unique characteristics regarding the applied power, and even when the applied power is low, the formation rate of the polymer - Compared to when high power is applied, the resistance may be equal to or more than twice as high, but a polymeric film soluble in a developing solution can be obtained as a negative resist.

The resist film formed by plasma polymerization has a significantly lower pinhole density. In our comparative experiments, at a film thickness of 0.2 μm, the pinhole density of the resist film formed by plasma polymerization was lower than that of that formed by conventional spin cording. 7/10 G
And, at a film thickness of 1j+m%'C, the pinhole density of the film formed by the plasma polymerization method is 41 when compared to the film formed by the spin code method: II The advantage is when the thickness is thin. ◎Although it is said that there are no pinholes in the film formed by the plasma polymerization method due to the formation mechanism described in Section 7, in reality, there are no pinholes in the film formed by the plasma polymerization method. , pinholes are generated depending on the polymerization conditions ◎Furthermore, the characteristic property of the resist produced by plasma polymerization is that it adheres to the irregularities of the substrate with almost the same thickness, and the conventional spin; This is in contrast to the fact that the resist film has a nearly flat surface regardless of the unevenness of the substrate.
When performing line pattern exposure on a resist whose resist film thickness partially changes in relation to the Fi resist film thickness, a line pattern with a partially changed width differs from a line pattern with a desired conductivity. There is a drawback.

On the other hand, in dry etching such as reactive ion etching using a resist as a mask, the resist film is etched from a direction perpendicular to the substrate and the film thickness decreases. When forming a resist, the resist becomes extremely thin at the stepped portions, which can cause an accident where the substrate side is etched due to excessive etching, but when the resist is formed by plasma polymerization, Even on the surface, the resist grows with almost the same thickness as on the flat part, and the above-mentioned O-slip accident does not occur. (6) Embodiments of the invention The inside of reaction chamber 1 was evacuated at 2X10-" Torrt. Cooling water was passed through the reactor (the base that supports 2 also serves as the ground electrode) and the alIQ was 60 wm (). JPI
A high-frequency power source S is connected to the Il electrode 3 via a matching circuit 4, and a high-frequency power of 6 MHz is applied to it.The gap between the electrodes is 3 s.
In the reaction chamber Bi, an inlet pipe 6 equipped with a spout for spouting out monomer gas is connected to a seven-tube chamber 8, which houses a seven-tube tube 7, through a pulp 9. Depending on the type of monomer being used, a carrier gas may be introduced through the pulp 10 to supply peak gas. Adjust the pulp 9 without introducing styrene as a 7-mer gas until the predetermined pressure is reached, and 1346
High frequency power of MHx was applied and the flow rate of styrene at this time was 80 mj/min. - Plasma polymerized styrene solubility Table 1 shows the polymerization conditions and solubility of the plasma polymerized styrene film. As shown in Table 1, the monoyer pressure is 0.15 Torr.
It can be seen that it is soluble in cyclohexane formed at an applied power of 0.06 W/d, and becomes insoluble as the applied power is increased. Also, when the applied power is increased at a pressure of 0.3 Torr, , the solubility of the membrane tends to decrease.

@t y Tsuzuma Jyukai Sterey @0 Jyusha conditions and membrane OII
Electron layer exposure characteristics of decomposable plasma-polymerized styrene film Negative-tone resists are necessary because the polymeric film dissolves in a given solution. Shown in Table 2・Dg in the figure
u is the electron beam exposure amount at a normalized residual film thickness of 0.5 K, and represents the sensitivity.
The sensitivity curve of the film formed with 3 Torr a applied power of 0 and 8 W/clf is shown. The horizontal axis of Fig. 2 shows the electron beam exposure amount (
C/d) is taken, and the vertical axis is the normalized residual lll [thickness is taken as 0, acceleration voltage is 1! OKV, the initial film thickness is 1 μm, and the current value is cyclohexane (20°C) for 20 seconds.The sensitivity of this film is 8xlO-'or value Fi.
3 no o' de aame・! It can be seen that all the cyclohexane-soluble polymerized films can form negative carbon dioxide as shown in Table 2.
Comparing the results when the e-summer pressure is constant at 0.3 Torr, the film formed with an applied power of 0.8 W/c11 is the same as the film formed with an applied power of 0.3 Torr.
The sensitivity is about twice as high as that of the film induced by 2W/cI&.The reason for this M is that I[ formed under high applied power conditions has a lot of energy given to the membrane molecules, and the active ingredient It is thought that because the density k is high, the polymerization reaction progresses and the molecular weight becomes high. In the Goodsma polymerized styrene resist of this example, the width is 1. A negative cut resist pattern of B μm can be formed.

Table 1 Plasma-polymerized desert terene lea electron = m photoresistivity Example 2 After dropping the silicon substrate in the same manner as in Example 1 and evacuating the inside of the reaction vessel, α-chloroacrylic acid was used as a monomer.
) A riller was introduced at a pressure of 0.45 Torr, and high frequency power was applied. At this time, the flow rate of α-chloroacrylonitrile was 70 mj/m, and the applied power was 0.15 W/m.
m and discharged for 2.5 minutes, the discharge was 0.8μ
A polymer film with a thickness of m was obtained. Electron beam irradiation was carried out in the same manner as in Example 1, with an irradiation dose of 2.5 x 10""07 m, and solution 1 was added to the current solution using N,N-dimethylformamide.
When developed at 120'C for 20 seconds, a negative resist pattern with a width of 2 μm could be formed.

Example 3 A silicon substrate was placed in the same manner as in Example 1, the inside of the reaction vessel was evacuated, and methyl acrylate was added as a monomer.
A high frequency was applied so that it was a'rorr. Flow rate of methyl acrylate at this time Fi30m I7m
l n *applied power riO, 2W/cd and sita. When the discharge was carried out for 30 minutes, a polymer film with a thickness of 0.9βm was obtained, and the polymer film was irradiated with an electron beam in the same manner as in Example 1.
L radiation amount: I X 1 G-'C'/cd), current 11
When I developed it for 30 seconds at a solution temperature of 20°C using Vinegar 114 Soardel as a solution, the width was 2. ．． A negative resist pattern of 5 μm was formed - Example 4 A silicon substrate was placed in the same manner as in Example 1, and the inside of the reaction vessel was evacuated, then monocool benzene was introduced as a monomer to a pressure of 0.3 Torr. High frequency was applied and the flow rate of monocool benzene at this time was 80 mj/m1
The applied power was 0.5 W/(31) and 90 discharge was performed for 2 minutes, and a polymer film of SamoaK thickness was obtained.The electron beam was irradiated in the same manner as in Example 1. Irradiation amount:
When developed for 20 seconds at a solution temperature of 20"C using n-propyl acetate in the lXl0-"C/If)It image solution, the width was 2μ.
Example 5 A silicon substrate was placed in the same manner as in Example 1, and the inside of the reaction vessel was evacuated. − as allylbenzene as 0.
The flow rate of allylbenzene was introduced at a pressure of 2 Torr and a high frequency was applied.FiSOml/m1
n + applied power ti 0.1'W/C1F ◎ When discharge was performed for 15 minutes, a polymer film with a thickness of 1.3 μm was obtained ◎ The electron beam was irradiated in the same manner as in Example 1. : 6 x 10-'C/(d)% When the developer was developed using cyclohexane at a temperature of 20°C for 20 seconds, a negative resist pattern with a width of 2 μm could be formed.90 Example 6 Same as Example 1 After setting up a silicon substrate and evacuating the inside of the reaction vessel, add 0 of triethylsilane as a monomer.
．． The pressure was set to 9 Torr and high frequency was applied◎
The amount of triethylsilane at this time is 40 mj/m1ne
After 40 minutes of zero discharge with an applied power of 0.3 W/d, a polymer film with a thickness of 0.9 μm was obtained.90 Electron irradiation was performed in the same manner as in Example 1. Irradiation amount: 5×10−
'C/c11), using cyclohexane as the developer and developing for 20 seconds at a solution temperature of 20°C, a negative resist pattern with a width of 2.5 Jm could be formed. In the above example, in developing a negative resist, Although the development was carried out using a normal developer for convenience, it is also possible to carry out the development by a well-known dry development.

(Effects of the Invention In the present invention, since plasma polymerization is performed using a parallel plate reactor, a higher film formation rate can be achieved compared to a method in which high frequency power is applied from an external coil. In the conventional method, it was difficult to form a polymer film that was soluble in solvents, but by controlling the pressure and flow rate of the monomer supplied, it was possible to form a Takaoka-type resist film.◎In this way, Since it is possible to form an efficient and reliable negative resist film, the yield of products manufactured using phosphorography technology, such as semiconductor devices, is improved.9. Improved reliability and productivity! $
1) The i-polymerization conditions, etc. that can be used in the present invention are not limited to those described in the examples, but can be appropriately selected according to the above purpose.

[Brief explanation of drawings]

Claims (1)

[Claims] In the method of forming a resist film by the Goodsma polymerization method, a substrate is placed on the ground side electrode of parallel plate electrodes facing each other in a reaction vessel, and the high frequency power applied to the parallel plate electrodes is set at approximately IW/m or less. A method for forming a negative resist film, which is characterized by forming a polymer film on a substrate that is soluble in a current liquid with a small amount of electric power.