JPH07201698A - Method for forming photosensitive layer for pattern exposure and semiconductor circuit using the same - Google Patents

Abstract

(57) [Abstract] [Purpose] When exposing an LSI finer than half micron with light, it is possible to expose the entire surface of the wafer with high resolution even if the step difference of the pattern in the exposure chip is more than the depth of focus To [Structure] A photosensitive object or a medium having high etching resistance is filled in a gap between a flat reference object and a wafer, and is cured and peeled to flatten the uppermost surface of the photosensitive object or a medium having high etching resistance on the wafer. To In the case of a medium having high etching resistance, a photosensitive layer is formed thereon by coating or the like. [Effect] Since the uppermost surface of the photosensitive layer on the wafer becomes flat,
A fine pattern with a shallow depth of focus can be formed with a high yield regardless of the unevenness of the wafer surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to semiconductor circuits, especially patterns.
The present invention relates to a semiconductor circuit having a line width of sub-half micron or less, and in particular, a method for forming a photosensitive layer for pattern exposure necessary for manufacturing a semiconductor circuit having a relatively large pattern step and a method for producing the same by using this method. Semiconductor circuits.

[0002]

2. Description of the Related Art In the conventional exposure of a semiconductor wafer having a line width pattern of 0.35 .mu.m, a resist is applied to the wafer by using a spin coater. With this coating, a fluid resist solution is dropped on the center of the rotating wafer, and the resist is made to flow from the center to the periphery by centrifugal force, so that a resist of uniform thickness is formed along the wafer surface as much as possible. It has gained. An original image of the circuit pattern on the reticle is projected and exposed on the wafer by using the i-line reduction projection exposure apparatus on the wafer thus coated with the resist to form the circuit pattern.

[0003]

As shown in FIG. 7, the surface shape 211 of the resist 1 applied by the above method,
221, there is unevenness on the surface of the underlying pattern already formed on the wafer. Therefore, it is applied to the underlying pattern portion with minute unevenness close to the size of the minimum circuit pattern. The resist surfaces 211 and 221 are uneven with a step difference Δh smaller than the uneven step h ″ of the underlying pattern, whereas in the case of a memory circuit, for example, in the case of a memory cell part and a peripheral circuit part. As described above, since the unevenness of the step h is generated over a relatively wide range, the step h exactly equal to this step h is applied to the resist surface 21 applied here.
It also occurs between 1 and 221.

Such a step difference becomes large in the wafer in the final step among a plurality of exposures performed by changing the reticle in the step of manufacturing one semiconductor circuit. However, as in the conventional case, when the line width of the circuit pattern is larger than the wavelength, even if there is such a large step, the circuit pattern is sufficiently resolved above and below the step. No particular problems occurred in the exposure process.

However, as the miniaturization of semiconductor circuits progresses, the minimum pattern line width w of the circuit is the wavelength λ used for pattern exposure.
It's about the same. As a result, the range in which the pattern is resolved, that is, the depth of focus DF, is equal to or less than the step d of the resist. As a result, for example, when focusing on the memory cell portion, a phenomenon that the peripheral circuit portion is not resolved occurs, and the yield of the exposure process is significantly reduced.

In the future, when a device having a line width pattern smaller than that of a quarter micron is manufactured or a device having a large step d is manufactured in the future, such a phenomenon becomes practically impossible. It causes the problem of being lost.

[0007]

The present invention has the following means in order to solve the above-mentioned problems. That is, when a photosensitive layer made of a photosensitive medium such as a resist is formed on an exposed object such as a wafer forming a semiconductor circuit pattern, the exposed surface on the exposed object and the exposed surface A reference object having a flat surface facing each other is arranged at a desired interval, and a photosensitive medium is filled between the two facing surfaces so that a photosensitive layer for pattern exposure is formed. did.

When the photosensitive layer is formed on the uppermost surface like a so-called multi-layered resist, it is made of a medium having a high etching resistance such as a resist for flattening under the uppermost layer. To form the planarization layer,
By filling this medium having high etching resistance between two opposing surfaces, a photosensitive layer for pattern exposure was formed. In this case, the uppermost photosensitive layer is usually formed later on the thus formed medium having high etching resistance.

In order to fill the photosensitive medium or the medium having high etching resistance, the reference object and the exposed object are placed in a clean sealed container in which the pressure of the gas inside can be controlled. Then, the filling between the two facing surfaces is performed. The specific means of filling this medium is as follows. The above-mentioned sealing is performed before the two surfaces are in contact with the photosensitive medium or the medium having a high etching resistance by including the medium between the two opposite surfaces and facing each other. The pressure P ₁ of the gas in the container is such that P ₁ <P ₂ with respect to the pressure P ₂ of the gas in the sealed container when both surfaces are in contact with each other. In addition, the photosensitive medium or the medium having high etching resistance before reaching the filled state is usually in a fluid state.

After reaching the filled state, the photosensitive medium or the medium having high etching resistance is cured. There are several methods of this curing, but as one method, the reference object is made transparent to light of a desired wavelength, and after reaching the filling state, light of this desired wavelength is irradiated, The photosensitive medium or the medium having high etching resistance is cured. After curing the photosensitive medium in this manner, the photosensitive medium or the medium having high etching resistance is further peeled off from the reference object.

After the above-mentioned filling of the medium, in order to perform good peeling as required, the photosensitive medium or the above-mentioned medium having high etching resistance has a certain degree of strong adhesion to the wafer and a proper degree. Although it is necessary to select a material having viscosity and curing performance, the above-mentioned medium material selected based on such a standard is used, and in the present invention, the following means are usually applied.

First, a medium that allows desired atoms or molecules to pass therethrough is used as the reference object. The surface of the reference object other than the desired second portion other than the portion in contact with the medium of the reference object is subjected to a surface treatment that seals against the desired atom or molecule. Further, a supply / exhaust means for supplying or exhausting the desired atom or molecule to the reference object is connected to the second portion.

With such a structure, the desired atoms or molecules are supplied from the air supply / exhaust means when the reference object and the photosensitive medium are separated or separated from each other. Further, the supply gas pressure P ₃ of the desired atom or molecule is set to P ₃ > P ₂ ′ with respect to the pressure P ₂ ′ of the gas in the sealed container at the time of peeling or separating. The pressure P ₂ 'of the gas of the sealed container when the peeling or separation, to the pressure P ₂ of the gas of the sealed container when allowed to reach the filling state,
Make sure that P ₂ '<P ₂ is satisfied. The desired atom or molecule at the time of peeling or separating is a rare gas such as He or a gas having a small molecule diameter such as H _{2 and the} medium for passing the desired atom or molecule is made of, for example, high-purity quartz glass. To do so.

A semiconductor circuit is manufactured by irradiating an object to be exposed having a photosensitive layer for exposure formed on it by the method described above with a particle beam containing light. The semiconductor circuit thus manufactured has a pattern minimum line width w even though it is manufactured by irradiating an electromagnetic wave containing light of wavelength λ, and the pattern with the minimum line width is The maximum step difference between the two surfaces is h, and h ≧ 1.4w ²
/ Λ is satisfied. Moreover, a semiconductor circuit satisfying such a structure is effectively formed by one exposure using one mask or reticle.

In the method for forming a photosensitive layer for pattern exposure of the present invention, if a semiconductor circuit pattern is drawn on the surface of the reference object having the flat surface facing the exposed object, After filling the photosensitive medium, a desired pattern can be exposed and formed on the photosensitive medium by simply irradiating the exposure light without using the projection optical system.

Further, in the method of forming a photosensitive layer for pattern exposure of the present invention, the shape of the surface of the reference object having the above-mentioned flat surface facing the object to be exposed is formed by the projection optical system used for exposure. If the surface shape is made to match, even if the field curvature of the projection optical system is large, it is possible to perform imagewise exposure on the surface of the photosensitive medium in the best focus state.

[0017]

Since the photosensitive medium or the medium having high etching resistance is filled between the two surfaces facing each other, the surface of the object to be exposed such as the wafer is not affected by the unevenness of the surface of the object to be exposed such as the wafer. The uppermost surface of the photosensitive medium or the medium having a high etching resistance, that is, the surface not in contact with the surface of the object to be exposed such as a wafer, is flat because it follows the surface of the reference object. As a result, if the circuit pattern is image-projected or projected onto this flat surface, no matter how the depth of focus DF is smaller than the step d of the underlying pattern, the circuit pattern is formed on the surface of the photosensitive layer. Can be formed.

By forming the photosensitive layer having such a flat uppermost surface by the method under the above-mentioned pressure condition,
The photosensitive medium or the medium having high etching resistance is formed into a top surface shape having good adhesion with the surface of the exposed object and following the flatness of the reference surface without causing so-called bubbles. It becomes possible.

That is, if the pressure P ₁ of the gas in the sealed container just before filling between the two surfaces is sufficiently low, for example, in a state close to vacuum, no bubbles will be generated after filling. Further, even if the filling medium contains a solvent even if it is not a vacuum, the pressure P of the gas in the sealed container immediately before the filling is increased.
_{If 1} has almost no molecular gas other than the solvent to an extent almost equal to the partial pressure of this solvent, bubbles will not be generated after filling. It is necessary that the pressure P ₁ immediately before this filling is smaller than the pressure P ₂ in the contact state after filling,
The smaller the size, the less the generation of bubbles.

After reaching the filling state, the photosensitive medium or the medium having high etching resistance is cured. There are several methods of this curing, but as one method, the reference object is made transparent to light of a desired wavelength, and after reaching the filling state, light of this desired wavelength is irradiated, The photosensitive medium or the medium having high etching resistance is cured. By curing in this way, the pattern will not be locally distorted after the pattern is formed.

After the photosensitive medium is hardened in this way, when a circuit pattern is drawn on the reference object, the reference object on which the circuit pattern is drawn is peeled off. Instead, by irradiating the photosensitive medium with the exposure light while being filled with the photosensitive medium, the circuit pattern drawn on the reference object can be exposed on the photosensitive medium with high resolution.

When the circuit pattern is not drawn on the reference object, the reference object is generally separated from the photosensitive medium or the medium having high etching resistance. Since the top surface of the photosensitive medium or medium with high etching resistance after peeling has a shape that follows the reference object plane, even if there is a large step on the wafer surface, it is imaged with electromagnetic waves including light Fine pattern using an optical system
It is possible to expose the image with high resolution.

[0023]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 is a diagram showing a method of forming a photosensitive layer for pattern exposure according to the present invention, wherein 1 is a photosensitive medium and 1'is a medium having high etching resistance. An initially fluid photosensitive medium or medium 1 or 1'having a high etching resistance is supplied to the exposed surface above the exposed object 2, and the reference object 3 facing the exposed surface has a flat surface. The photosensitive medium is filled between the two surfaces so that the distance between the surfaces is a desired distance.

When the filled photosensitive medium 1 or the medium 1'having a high etching resistance and the reference object 3 are separated (released) by the method described later, the surface is uneven as shown in FIG. 1 (b). A photosensitive medium 1 having a flat uppermost surface or a medium 1 ′ having high etching resistance is formed on the object to be exposed. When using the medium 1'having high etching resistance,
On this medium, as shown in FIG.
Is formed by coating, vapor deposition or sputtering. The wafer on which the photosensitive layer is thus formed is carried into an exposure device such as a reduction exposure device (not shown), and the pattern of the mask or reticle is overlaid on the photosensitive layer.

FIG. 2 shows an embodiment of a method for forming a photosensitive layer for pattern exposure according to the present invention and a semiconductor circuit using the method. The reference object 3'has a circuit pattern 31 drawn on the surface facing the wafer 2 having irregularities. As shown in the embodiment of FIG. 1, the resist supplied on the upper surface of the wafer 2 is
The circuit pattern surface 31 and the pattern surface of the wafer are set in a desired space, and after being filled in the desired space, exposure light 5'is irradiated. Before or after this exposure, the filled resist is cured by applying light or heat which does not expose the resist.

After the exposure and curing are completed, when the reference object is peeled off, the surface of the resist on the wafer is flat and the circuit pattern is already exposed as shown by the dotted line in FIG. 2 (b). As a result, by developing it, as shown in FIG.
As shown in FIG. 7, even if there is a step between the portions 21 and 22, the resist circuit pattern is formed in the sharp, and the subsequent etching can form a pattern with high resolution.

FIG. 2D shows the method of forming the photosensitive layer for pattern exposure described in FIG. 1 or FIG. 2 and the sectional structure of the semiconductor circuit manufactured by this method. For example, if a semiconductor memory circuit is taken as an example, the pattern 211 of the memory section has a base portion h higher than the pattern 221 of the peripheral circuit section, and effectively the base of the peripheral circuit section is high. In the highest part of the memory cell part with respect to the memory cell, h'is higher.

When the conventional resist coating method is used, the height difference between the resist surfaces is h'-h. Even if such a wafer is exposed using a conventional semiconductor exposure apparatus, assuming that the exposure wavelength λ and the minimum dimension of the exposure pattern are w, the depth of focus DF of the exposure optical system is given by Equation 1, Under the conditions of No. 2, a pattern cannot be formed.

[0030]

[Equation 1]

Condition 1: When exposure is performed without using a phase shift reticle In this case, the formula 1 is established, and the focused width is 2D.
However, considering the focus detection / control accuracy L of the exposure apparatus, the flatness F in the exposure area of the wafer, and the curvature C of the image plane of the projection optical system, the allowable value of h or h '. Becomes Equation 2.

[0032]

[Equation 2]

When the exposure wavelength is i-line (λ = 0.365 nm) and the pattern width w = 0.5 μm, DF = ±
0.95 μm, L = ± 0.1 μm, F = 0.4 μm
m and C = 0.4 μm, h ≦ 0.
It becomes 9 μm. The exposure wavelength is KrF excimer laser (λ =
0.248 nm), the pattern width is w = 0.35μ
If m, then DF = ± 0.69 μm, and h ≦ 0.4 μm from Equation 2.

Condition 2: When exposure is performed using a phase shift reticle

[0035]

[Equation 3]

In this case, the formula of the depth of focus DF 'is the above formula 3. The exposure wavelength is i-line (λ = 0.365 nm),
If the pattern width is w = 0.35 μm, DF = ±
0.75 μm, L = ± 0.1 μm, F = 0.4 μm
m and C = 0.4 μm, h ≦ 0.
It becomes 5 μm. The exposure wavelength is KrF excimer laser (λ =
0.248 nm), the pattern width is w = 0.25
DF = ± 0.53 μm, and h ≦ 0.1 μm from (Equation 2).

As can be seen from the above example, when trying to expose a sub-harf micron (finer than 0.5 μm) pattern, the circuit pattern is exposed unless h ≦ 1.4w ² / λ is satisfied. Can not do. In other words, conversely, the pattern step h (or effective pattern step h ′) of the wafer is h ≧ 1.4w ^{2 for the} first time by using the method for forming a photosensitive layer for pattern exposure of the present invention. It becomes possible to form a semiconductor circuit satisfying / λ.

FIG. 3 shows an embodiment of the method for forming a photosensitive layer for pattern exposure according to the present invention and an example in which a circuit pattern is exposed to the photosensitive layer for pattern exposure using a reduction lens by this method.
As emphasized in FIG. 3B, the image plane of the reduction lens is not a plane but a curved surface. Therefore, even if the wafer surface is flat in the exposure shot area, if the best focus surface is curved, as described in the previous embodiment,
It effectively reduces the depth of focus. Therefore, in this embodiment, the shape 13 of the surface 32 of the reference object 3 ″ facing the wafer is used.
2 is matched with the field curvature shape 632 of the exposure apparatus.

In this way, even if there is a curvature of field, even if the pattern of the flat reticle 4 that is normally used is projected and exposed by the reduction lens 6, the image forming surface 632 thereof is the resist surface 132. In principle, the entire surface of the exposure area can be exposed in the best focus state.

FIG. 4 shows a more specific method of forming a photosensitive layer for pattern exposure in an embodiment of the present invention. 70 is clear
It is a sealed container (chamber) and has a space 71 inside the container.
The pressure P of the gas is measured by the pressure gauge 74, and the pressure control system 7
2 and the valve 721. In addition, a desired gas molecule 84 is introduced from an inlet 841 to fill the inside of the sealed container with a desired partial pressure. A gate valve 731 is provided in the sealed container with a passage 73 for loading and unloading wafers.
Is installed through. A wafer supplied from the outside of the hermetically sealed container into the container through a gate valve supplies a desired amount of resist to the surface of the wafer by a resist supply device 83 according to the surface irregularity of the wafer. The supplied resist is low in viscosity and rich in fluidity, so that it is uniformly spread on the wafer with the help of the wafer driving mechanism 82 to a degree close to the final resist thickness.

As shown in the flow chart of FIG. 6, the pressure P in the hermetically sealed container is set at P ₁ close to a vacuum at this time. However, this pressure is determined in consideration of the volatility of the solvent dissolved in the resist, and in order to control this volatilization as necessary, the gas of the solvent is introduced into the inlet port 841 so as to have a desired partial pressure P ₁ ′. Supplied from The reference object 3 is brought close to the wafer held on the wafer holding mechanism 85 by the reference object holding drive mechanism 81 as shown in the flowchart of FIG. , The thickness of the resist reaches a desired thickness ΔG, and the resist is filled between both surfaces. At this stage, the pressure P inside the sealed container is set to P ₂ which is higher than the pressure P ₁ mentioned above.

Thereafter, light for curing the resist is irradiated from above the reference object to cure the resist, and then the reference object holding drive mechanism 81 is used to separate the reference object from the resist on the wafer. In order to facilitate this peeling, it is advisable to thinly coat the surface of the reference object, which comes into contact with the resist, with a release agent having a small adhesion to the resist. Further, if a reference object having a structure as shown in FIG. 8 is used, it can be peeled off more easily.

In FIG. 8, the reference object 3 is made of high-purity quartz. High-purity quartz has a small molecule diameter such as He gas and H ₂
Allow gas to pass through. The part of the surface of this quartz that comes into contact with the wafer remains this quartz. Except for this part, except for the second part 303, the surface is treated so that gas with a small diameter of these molecules does not pass through. deep. In this way 3
The pipe 03 is connected to a pipe 304 for supplying a gas having a small diameter of these molecules. In this way, when the reference object is peeled from the resist on the wafer, the pipe 304
Supply He or H ₂ gas. The supply gas pressure P ₃ is set sufficiently higher than the pressure P ₂ ′ in the sealed container at the time of peeling.

By setting such a pressure relationship and a force other than the self-gravitational force of the reference object to a negligible level, gas exudes between the resist and the reference object, which are in close contact with each other, so that the reference object can be easily separated. It will be possible. The reference object capable of supplying gas in FIG. 8 is entirely made of quartz, but with such a structure, the path through the quartz portion becomes long, and sufficient gas cannot be supplied in a short time.

FIG. 9 shows an embodiment of the present invention, in which a flat base 310 having high rigidity is cut at the same height to form a conical spacer 312 whose cut surface is parallel to the bottom surface. A plurality of side-by-side adhesives are adhered, and a highly parallel reference object is adhered under the spacer. The space containing the spacer is connected to the tube 304. With the medium 1'having high etching resistance filled in the wafer, ultraviolet rays are irradiated through the transparent side wall 311 using the optical fiber 5 "to cure the medium 1'having high etching resistance. Is done effectively,
The spacer-side surface of the flat base 310 having high rigidity is processed to diffusely reflect ultraviolet rays.

Further, although only one fiber is shown in FIG. 9, the fiber ends are arranged in the periphery, and uniform ultraviolet irradiation is performed. He gas is supplied from the tube 304 in order to separate the medium 1 ′ having a high etching resistance that has been cured in this way from the reference object. He
Since the reference object made of quartz that passes through the substrate is thin, the wafer can be separated from the reference object in a short time. In order to apply the photosensitive substance on the medium 1 ′ having a flat surface that is peeled off and having a high etching resistance, a photosensitive layer is formed by using, for example, a spin coater or the like.

FIG. 10 shows an embodiment of the present invention, which uses a material having high air permeability and high rigidity, for example, sintered metal 320. The lower surface of this material is made flat, and a breathable reference object is partially bonded to this flat surface so as to maintain breathability. The surfaces other than the adhesive surface are covered with a material 301 having a high sealing property. A tube 304 is connected in the same manner as in FIGS. 8 and 9, and a gas having a small molecular diameter is supplied to remove the resist from the reference object. Peel off.

FIG. 11 shows an embodiment of the present invention. In this embodiment, the strain of the reference object is used as a method of filling and peeling the photosensitive layer or the medium having high etching resistance. Figure 11
(A) is a mechanism diagram for realizing this method. The reference object 3 is fixed around the reference object holding mechanism 330 having high rigidity. On the back surface of this reference object, a piezo element 331
Are arranged at substantially equal intervals. One end of this piezo element is fixed to the reference object holding mechanism 330, and the other ends are in contact with each other by pushing the back surface of the reference object. An electric wire for driving the piezo element is wired from the inside of the reference object holding mechanism 330 to the outside and is connected to the drive control circuit 333. Each piezo element is driven by the drive control circuit 333 so that the reference object 3 has a desired shape.

At this time, the photosensitive layer or the medium 1 having high etching resistance and the reference object 3 are brought into contact with each other, and finally,
This measurement information is transmitted to the drive control circuit 333 while performing the following measurement so that the thickness of the photosensitive layer or the medium having high etching resistance filled between both objects will be a desired value as a whole. Then, using this information, the piezo element 331 is driven and the wafer holding mechanism 85 is driven in the vertical (z) direction.

This measurement includes the measurement of the shape of the reference object and the measurement of the distance between the surface of at least one part of the reference object 3 and the holding surface of the wafer or the wafer holding mechanism in the z direction. As the latter gap measuring machine 334, an optical gap sensor, an air microsensor, a capacitance sensor, etc. are used in addition to the widely used laser interferometer. It is preferable to install this gap measuring machine at three locations around the wafer,
If the shape information of the reference object shape measuring machine is used, it is not always necessary to perform a plurality of measurements, and only one position may be used.

Next, the former measurement is performed as shown in FIGS.
Will be explained. This measuring method is disclosed in JP-A-3-40417.
The method of which the details are given in, etc. is used to obtain the inclination and height of the surface by using the interference of the laser. This shape measuring machine is provided in two places, and 337 is the lower surface of the reference object.
47 measures the upper surface of the reference object. 337 or 347
Has a laser light source (not shown), and the laser light is made into a desired beam diameter by a beam expander (not shown). This beam is divided into two by a beam splitter, and the reference object holding mechanism 33 is fed from the shape measuring machine 337 or 347.
Two beams bisected into the reference object are made incident through a window on the side surface of 0 (which is also a portion which holds the side surface of the reference object at the same time).

The light emitted from the shape measuring instrument 337 advances in the x direction, and the light emitted from the shape measuring instrument 347 advances in the y direction.
The two bisected beams emitted from the shape measuring instrument 337 are wide in the y direction shown in FIG. 11, and their width is w _y .
It is narrow in the z direction and has a width w _z . w _y is almost equal to the diameter D _{w of the} wafer, and w _z is the angle of incidence on the lower surface of the reference object plane θ.
Then, w _z = D _w / cos θ.

A measuring method using this interference will be described with reference to FIG. One of the two divided lights is the object to be measured (Fig. 12).
O, and in FIG. 11, the object light (or measurement light) 338 or 34 radiated on the lower surface or the upper surface of the reference object 3
The other light is used as the interference reference light 339 or 349. The object light is reflected by the object to be measured O and then reflected by the mirror M or 3371 or 34.
The light that is vertically incident on 71 and is specularly reflected returns to the original path.

On the surface of Σ shown in FIG. 12A, the two lights are overlapped with each other, and interference fringes are generated. This interference fringe is used to form the imaging lens 3
If an image is formed on the CCD image pickup device 3377 at 36, FIG.
An interference signal as shown in (b) is obtained. A of this interference signal
The portions A and B substantially correspond to the portions A and B of the object to be measured O. Since the phase of the interference fringe represents the height of the object to be measured, the information of the interference fringe of FIG.
The shape of the surface of the measured object in (c) can be obtained.
Although only one interference signal is shown in FIG. 12, the CCD
Since 3377 (or 3477) can be two-dimensionally imaged, this interference fringe signal can be obtained on the entire surface of the reference object. The obtained signal is processed by the height measurement processing circuit 300 to measure the height of the entire reference object, that is, the surface shape.

As shown in FIGS. 11B and 11C,
The lower and upper surfaces of the reference object are measured separately and independently. The purpose is to measure the shape of the lower surface, but when the reference object comes into contact with the photosensitive object on the wafer or a medium resistant to etching, there is almost no reflection on the reference object surface,
The main reflection is from the uneven surface of the wafer. Therefore, after the contact, at least 33 of FIG. 11B is obtained by using the shape information of the upper surface of the reference object measured by 347 of FIG. 11C.
7 supplements the measurement of the contact part that cannot be measured. Further, the piezo 331 is driven based on the measurement information, and the moment when the reference object and the resist or the medium having high etching resistance shift from the non-contact state to the contact state can be detected by the shape measuring machine 337.

That is, as shown in FIG. 14 (a), in the non-contact state, the light is totally reflected on the lower surface of the reference object 3, so that in the A ₁ A ₂ cross section of the detection light, as shown in FIG. 14 (b), Although it has such a distribution (a part of Gaussian distribution), in the contact state as shown in FIG. 14C, the reference object 3 is transmitted between the contact portions B ₁ 'B ₂ ' and the wafer surface Since the light is radiated to the irregularities of and scattered here, the portion corresponding to this area is shown in FIG.
As shown in FIG. 4 (d), the number of detected pieces is weakened, and it can be seen that they are in contact with each other.

Since not only the detected light amount described above but also the shape measurement result changes abruptly, the moment when the detected light amount or the shape measurement result changes is captured, and the shape information of the reference object and the reference object at this time are detected. By using the information on the distance to the wafer or the wafer holding mechanism, the piezo 33
1 and the wafer holding mechanism 85 are vertically moved more accurately,
Control the film thickness of the packing so that it becomes a desired constant value.
It becomes possible to

In this way, when the filling is completed, ultraviolet rays are radiated from above through the reference object to cure the filling substance. When the curing is completed, the process just opposite to the one in which the non-contact state is brought into the contact state is followed, and the contact state is separated (released).

FIG. 13 shows an embodiment of the present invention. Since a wafer is usually thin and therefore easily deformed, a method for contacting and peeling a reference object is shown. In this embodiment, the reference object 3 or the reference object 3'on which the pattern is drawn is sufficiently thick and has rigidity. The flat lower surface is brought into contact with a low-viscosity, fluid photosensitive object coated on a wafer or an etching resistant medium. At this time, the wafer deforming chuck 20 is brought into contact with the shape of the chuck while controlling the shape. At this time, as shown in FIG. 13A, the deformation chuck is controlled and the wafer holding mechanism 85 is vertically controlled while monitoring the contact state.

First, as shown in FIG. 13A, each piezo 331 'is controlled so that the deformable chuck is in a state of being convex upward. In the state of being convex upward, the expansion of each piezo,
The strain gauge 3311 'is used for the measurement.

Next, the wafer holding mechanism is gradually raised and the amount of movement is measured by a length measuring machine (not shown).
The contact state detection system 35 constantly monitors the contact surface. In the contact state detection system 35, highly directional light from the illumination system 352 is emitted to the contact area through the side surface of the reference object, reflected light is also extracted through the side surface of the reference object, and the imaging lens 350 causes the imaging device to pick up the image. An image of the contact area is formed on the imaging surface of 351. Since the incident angle θ of the illumination light on the contact area is larger than the critical angle θ _c , it is totally reflected in the non-contact state, and the intensity distribution of the illumination light is exactly the same as that of the illumination light on the imaging device 351. When it comes into contact with a photosensitive object or a medium having high etching resistance, total reflection does not occur at that portion, so the intensity of that portion becomes weak and the contact portion can be easily detected.

While keeping the height of the contacting portion unchanged, that is, the contact state is always detected, and the control system 333 'moves the wafer holding mechanism slightly upward based on the detected information. , Only the amount corresponding to this movement amount,
The piezo in the contact area is shortened. In this way, FIG.
As shown in FIG. 3 (b), if the photosensitive object or the medium having high etching resistance is uniformly filled, the exposure light is used in the case of the reference object 3'with the circuit pattern drawn. Irradiate 5'and expose. A medium 1'having a high etching resistance is used, and in the case of a transparent reference object 3, ultraviolet rays 5 are irradiated to cure the medium. After that, the wafer is separated from the reference object by following a process opposite to the process leading to the contact.

In the filling method and the peeling method described with reference to FIGS. 11 and 13, only the deformation of the contact object is used. However, by combining the peeling using the gas shown in FIGS. In addition, it is possible to release the mold without causing surface deformation.

FIG. 15 shows an embodiment of the present invention and shows a method of filling a medium having high etching resistance to form a photosensitive layer for pattern exposure. First, benzophenone and benzoin isopropyl are added to a medium which is curable to ultraviolet rays and has high etching resistance, such as 1,6 hexanediol dimethacrylate, 1,10 decandiol dimethacrylate, dicyclopetane diacrylate and the like. A spin coater 100 is used to apply a photopolymerization initiator such as ether or Michler's ketone.

As described above, the wafer on which the medium, which is still in a fluid state and has a high etching resistance, is placed is carried into the clean container 70 through the gate valve 731, and the wafer deformation chuck on the wafer vertical drive mechanism 851. It is mounted on 20. The wafer deformation chuck 20 is first held in a non-deformed state, and while measuring the surface shape using the shape measuring machine 357 whose detection principle is described in FIG.
As shown in, the shape is deformed into a convex shape, and the deformed shape is measured.

By this measurement, the unevenness on the wafer, especially the concave portion, can be found.
The medium having the same high etch resistance as that coated with No. 00 is supplied while controlling the position of the minute amount feeder 83 and selectively controlling the minute amount. Further, since this recessed portion can be seen from the design data instead of the above-mentioned shape measurement, a minute amount of a medium having high etch resistance is selectively changed by changing the position of the feeder 83 based on this data. A small amount may be supplied while controlling.

By doing so, the wafer is supplied to the extent that it fills the recessed portion, so at this stage the wafer vertical drive mechanism 851 is driven to move the wafer upward until it contacts the reference object. At this time, the contact state between the reference object 3 and the medium 1 ′ having high etching resistance is detected by using the contact state detection system 35 described in the embodiment of FIG.

When the contact state is first detected, the contact amount detection system 35 is used to constantly monitor the contact state, and the drive amount of the wafer vertical drive mechanism 851 and the deformation amount of the deformable chuck are controlled to control the etching resistance. The high-density medium 1'is filled with a uniform thickness. In this process, the pressure in the clean container 70 is kept as low as possible.

After the medium 1'is filled by the above method, ultraviolet rays are irradiated from the curing ultraviolet light source 50 through the windows 19 ', 19 "to cure the medium 1'. When the curing is completed, the wafer vertical drive mechanism The wafer is peeled off from the periphery of the wafer while controlling the driving amount of 851 and the deformation of the deformation chuck.In parallel with this peeling, the pressure of the clean container 70 is made larger than that of the pressure control system 72 '. When the peeling is completed, the wafer is returned to the spin coater 100 again, and the photosensitive object is coated on the medium having high etching resistance, and the control circuit 355 controls the above steps.

After the medium 1'having a high etching resistance is brought into contact with the reference object, a releasing agent is coated on the reference object surface so that the medium 1'can be easily separated from the reference object without distortion. For example, a film of several hundred liters is coated by plasma polymerization using CF ₂ = CF ₂ and octafluorocyclobutane as a monomer, or a silicon-based polymer is dissolved in an appropriate solvent and spin-coated.

By doing so, it is possible to cleanly separate from the reference object. However, although with a very low probability, peeling may not be successful and a very small amount of medium having high etching resistance may remain on the reference object. Therefore, Figure 1
The foreign substance monitor 36 in the clean container 5 detects this. It is desirable to perform this detection before filling and after peeling,
It is sufficient even after peeling.

[0072]

According to the method for forming a photosensitive layer for pattern exposure of the present invention, even for a wafer having a large pattern step, the uppermost surface of the photosensitive layer formed thereon becomes flat on the wafer, For example, there is a large pattern step generated in the memory cell section of the memory circuit and the peripheral circuit section, and even if this exceeds the depth of focus of the exposure system, it becomes possible to perform exposure with a sufficient focus margin.

As a result, it becomes possible to produce a circuit having a line width smaller than 0.5 μm with a high yield. Especially when trying to form a thinner line width pattern using light,
Conventionally, it was not possible to form a circuit having a pattern step difference larger than 1.4 w ² / λ, but such a limitation of the step difference is virtually eliminated, which is very advantageous in pattern design and manufacture.

[Brief description of drawings]

FIG. 1 is an example of the present invention showing a method for forming a photosensitive layer for pattern exposure.

FIG. 2 shows a method using a reference object on which a pattern is drawn and a pattern formed by the method according to an embodiment of the present invention.

FIG. 3 is an example of the present invention applied to a reduction lens having a field curvature.

FIG. 4 is a diagram showing an embodiment of the present invention, showing a method for forming a photosensitive layer for pattern exposure in a pressure-controlled clean container.

FIG. 5 is an embodiment diagram of the present invention showing a method for forming a layer in a clean container.

6 is a diagram showing a flow chart of the method of the embodiment of FIG.

FIG. 7 shows a surface shape of a wafer and a shape of a photosensitive layer formed by a conventional method.

FIG. 8 is a method of peeling off particles having a small molecular diameter according to an embodiment of the present invention.

FIG. 9 is a method of exfoliating by holding a residue having a small molecular diameter in the example of the present invention.

FIG. 10 is a method of exfoliating by holding a residue having a small molecular diameter in the example of the present invention.

FIG. 11 is a diagram illustrating a method using distortion of a reference object according to an embodiment of the present invention.

12 is a diagram for explaining the surface shape measuring method of FIG.

FIG. 13 is a method of using distortion of an object to be exposed in an embodiment of the present invention.

FIG. 14 is an explanatory diagram of a method of detecting contact with a reference object.

FIG. 15 is a diagram showing a method from application of a medium having an etching resistance field to formation of a photosensitive layer in an example of the present invention.

[Explanation of symbols]

1 is a photosensitive object such as a resist, 1'is an object having high etching resistance, 2 is a wafer, 20 is a wafer deformation chuck, 2
1 is a memory cell part, 22 is a peripheral circuit part, 3 is a reference object,
3'is a reference object on which a pattern is drawn, 4 is a reticle,
5'and 51 are exposure lights, 6 is a reduction lens, and 632 is an image plane. 7 is a clean sealed container, 72 is a pressure control system, 8
1 is a reference object holding drive mechanism, 82 is a wafer drive mechanism, 8
Reference numeral 3 represents a resist supplier, and reference numeral 84 represents a desired gas flow.
300 is a height measurement processing circuit, 331, 331 'are piezo elements, 333 is a drive control circuit, 337, 347 is a shape measuring instrument, 355 is a control circuit, 334 is a gap measuring instrument, 3
04 is a gas supply pipe, 320 c is a breathable rigid material, 331
1'is a strain gauge. Reference numeral 100 is an apparatus for applying a medium having a high etching resistance and a photosensitive layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Watanabe Inventor Masahiro 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock Manufacturing Research Institute, Hitachi, Ltd. (72) Inventor Yasuhiko Nakayama 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Production Engineering Laboratory, Hitachi, Ltd. (72) Masaki Yoshii, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock Production Laboratory, Hitachi, Ltd.

Claims (24)

[Claims] 1. The surface of the photosensitive layer by pressing the flat surface of a reference object having a flat surface on the surface of the photosensitive layer for pattern exposure of the exposed object to cure the photosensitive layer. The method for forming a photosensitive layer for pattern exposure, comprising: 2. A photosensitive medium is supplied onto the exposed surface of an exposed object, and a reference object having a flat surface is provided at a desired distance from the exposed surface with the flat surface sandwiching the photosensitive medium. The photosensitive medium sandwiched between the exposed surface and the flat surface is disposed so as to face each other, and the filled photosensitive medium is cured, and after curing the photosensitive medium, A method for forming a photosensitive layer for pattern exposure, which comprises forming the photosensitive layer for pattern exposure by removing the reference object from the exposed surface. 3. The reference object is transparent to exposure light, and a circuit pattern to be exposed is drawn on one surface of the reference object so that the drawing surface and the exposed surface on the exposed object face each other. 3. The photosensitive layer for pattern exposure according to claim 2, wherein the photosensitive layer for pattern exposure is formed by arranging the photosensitive layer and the photosensitive medium between the two opposing surfaces. Method. 4. A method for forming a photosensitive layer for pattern exposure, which comprises forming a flattening layer made of a medium having high etching resistance on an exposed object and then forming a photosensitive layer on the flattening layer. The medium having high etching resistance is filled between two facing surfaces of the exposed object and a reference object having a flat surface facing the exposed surface with a desired interval. The method for forming a photosensitive layer for pattern exposure according to claim 1, wherein a photosensitive layer for pattern exposure is formed. 5. The method for forming a photosensitive layer for pattern exposure according to claim 1, 2 or 4, wherein said flat surface is a flat surface. 6. The pattern exposure photosensitive material according to claim 1, wherein the shape of the flat surface is the same as the shape of the image plane of the image formed by the projection exposure optical system used for exposure. Layer forming method. 7. The reference object and the object to be exposed are arranged in a clean sealed container in which the pressure of the gas inside can be controlled.
5. The photosensitive medium or the medium having high etching resistance is filled.
The method for forming a photosensitive layer for pattern exposure as described above. 8. The photosensitive medium or the medium having high etching resistance is disposed between the flat surface of the reference object and the object to be exposed, and the photosensitive medium or the medium is arranged so that both surfaces face each other, and the photosensitive medium or the photosensitive medium or the photosensitive medium is provided. The pressure P ₁ of the gas in the sealed container before the surface of the medium having high etching resistance is in contact with the flat surface of the reference object is the gas pressure in the sealed container when both surfaces are in contact with each other. Pressure P ₂
On the other hand, the method for forming a photosensitive layer for pattern exposure according to claim 7, wherein the filling is performed so that P ₁ <P ₂ . 9. The photosensitive layer for pattern exposure according to claim 2, 3 or 4, wherein the photosensitive medium or the medium having high etching resistance before reaching the filled state is in a fluid state. Forming method. 10. The method for forming a photosensitive layer for pattern exposure according to claim 8, wherein the photosensitive medium or the medium having high etching resistance is cured after reaching the filled state. 11. The reference object is transparent to light having a desired wavelength, and is irradiated with the light after reaching the filling state to cure the photosensitive medium or the medium having high etching resistance. The pattern according to claim 10, characterized in that
Method for forming photosensitive layer for exposure. 12. The photosensitive layer for pattern exposure according to claim 10, wherein after the photosensitive medium is cured, the photosensitive medium or the medium having high etching resistance is peeled off from the reference object. Forming method. 13. The method for forming a photosensitive layer for pattern exposure according to claim 1, 2, 3 or 4, wherein the reference object is a medium which allows desired atoms or molecules to pass therethrough. 14. The surface of the reference object other than the desired second portion other than the portion in contact with the photosensitive medium or the medium having high etching resistance of the reference object has the desired atoms or 14. The method for forming a photosensitive layer for pattern exposure according to claim 13, wherein the molecule is subjected to a surface treatment having a sealing property. 15. The pattern according to claim 14, wherein the second portion is connected to an air supply / exhaust means for supplying the desired atom or molecule to the reference object or for exhausting the desired atom or molecule from the reference object. -Method for forming photosensitive layer for exposure. 16. The pattern according to claim 15, wherein the desired atoms or molecules are supplied from the air supply / exhaust means when the reference object and the photosensitive medium are separated or separated from the contact state. Method for forming photosensitive layer for exposure. 17. The supply gas pressure P ₃ of the desired atom or molecule at the time of peeling or separating is P ₃ > P with respect to the pressure P ₂ 'of the gas in the sealed container at the time of peeling or separating. _The method of forming a photosensitive layer for pattern exposure according to claim 16, wherein the photosensitive layer is ₂ '. 18. The pressure P ₂ 'of the gas in the sealed container at the time of peeling or separating is P ₂ '<with respect to the pressure P ₂ of the gas in the sealed container when the filled state is maintained.
18. The pattern according to claim 17, wherein P ₂ is satisfied.
Method for forming photosensitive layer for exposure. 19. The photosensitive material for pattern exposure according to claim 13, wherein the desired atom or molecule at the time of peeling or separating is a rare gas such as He or a gas such as H _{2 having} a small molecular diameter. Layer forming method. 20. The method for forming a photosensitive layer for pattern exposure according to claim 13, wherein the medium through which the desired atoms or molecules pass is made of quartz glass. 21. A particle beam containing light is applied to an object to be exposed having an exposure photosensitive layer formed on the surface thereof by the method for forming a pattern exposure photosensitive layer according to any one of claims 1 to 20. A semiconductor circuit manufactured by irradiation. 22. The minimum line width of the pattern is w, and the step difference between the two surfaces on which the pattern of the minimum line width is formed is maximum h.
The semiconductor circuit produced by irradiating an electromagnetic wave containing light, characterized in that the pattern is formed by exposure using light of wavelength λ, and h ≧ 1.4w ² / λ. . 23. The semiconductor circuit according to claim 22, wherein the patterns on the two surfaces having the interval of h are formed by exposure using one mask or reticle. 24. The semiconductor circuit according to claim 22, wherein the patterns on the two surfaces having the interval of h are effectively formed by one exposure.