JPH1172927A - Method for dimensional control of resist pattern and heating treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the dimensional controllability of a chemical amplification type resist. SOLUTION: This dimensional control method includes a stage of subjecting the chemical amplification type resist applied on a surface to BEP processing to induce reaction using the acid in the resist as a catalyst by heating a substrate on which prescribed patterns are exposed (step S1), an intensity distribution measuring stage for executing irradiation with light of the wavelength at which the chemical amplification type resist is not sensitized and scanning (step S2) and measuring the intensity distribution of the reflected light (step S3), a stage for detecting the size of at least either of the part where the reaction occurs and the unreacted part (step S4), a stage for comparing the detected size and the set size (step S5), a stage for returning to the step S2 when the detected size and the set size are different in the step S5 and a stage for ending the BEP processing when the detected size and the set size are equal in the step S5 (step S6).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the size of a resist pattern using a chemically amplified resist and a heat treatment apparatus.

[0002]

2. Description of the Related Art In recent years, progress in miniaturization of patterns in the semiconductor industry has been remarkable, and it is said that a pattern line width required for manufacturing a DRAM of 1 Gbit or more is 0.15 μm or less. Therefore, the development of high precision and high resolution of a drawing apparatus, improvement of PEB processing, development or etching process, development of a resist having high sensitivity and high resolution, and the like have been actively performed for miniaturization.

[0003] Particularly, in recent years, a chemically amplified resist has suddenly attracted attention as a high-sensitivity and high-resolution resist. Chemically-amplified resists have an acid generated by exposure to PE.
During the B treatment, it acts as a catalyst for the change in polarity of the resin and the crosslinking reaction. The change in polarity gives a positive image by the reaction of eliminating the dissolution inhibiting group which originally suppresses the dissolution of the alkali-soluble resin. In the case of a negative chemically amplified resist, the acid generated by exposure serves as a catalyst to cause a crosslinking reaction.

[0004] However, it is known that the acid generated by exposure to a chemically amplified resist is deactivated by surrounding basic substances (such as ammonia present in the air). The deactivation of the acid causes a variation in the pattern profile and the resist sensitivity, and also affects the pattern dimension. Therefore, there is a problem that it is very difficult to control the pattern dimension of the chemically amplified resist.

Another problem is that the resist line width and shape change over time due to the acid chain reaction (withdrawal characteristics). Regarding the retention characteristics of the chemically amplified resist, efforts have been made to reduce the sensitivity of the resist due to the influence of the environment, for example, by setting up an environment in a clean room.

However, the change in sensitivity due to the retention characteristics and acid deactivation also depends on the ammonia concentration in the clean room, the retention time, and the type of resist, so it is very difficult to control the dimensions of the resist pattern. Difficult
Actually, sufficient control of the pattern size is not performed.

In the process of managing the pattern size in a process using a chemically amplified resist, the pattern size is measured by a laser microscope or a size SEM after development. However, with the conventional method of observing the pattern dimensions after development, if the resist sensitivity fluctuates,
A resist pattern having the desired dimensions could not be obtained.

On the other hand, with the increase in the diameter of a wafer or a mask accompanying an increase in memory capacity, there is also a problem that in-plane baking temperature unevenness occurs, which causes dimensional in-plane variation. I have.

[0009]

As described above, when a chemically amplified resist is used, there is a problem that the resist sensitivity fluctuates due to the deactivation of the acid and the lay-down characteristics, resulting in poor pattern dimensional controllability. Was.

[0010] Further, as the size of the wafer or the mask increases, there is another problem that the baking temperature in the plane becomes uneven and the resist pattern dimension varies. An object of the present invention is to form a resist pattern in consideration of fluctuations in resist sensitivity depending on acid deactivation and withdrawal characteristics, and in-plane temperature unevenness, and to improve resist pattern dimensional controllability. And a heat treatment apparatus.

[0011]

[Means for Solving the Problems]

[Configuration] The present invention is configured as described below to achieve the above object. (1) The method for controlling the size of a resist pattern according to the present invention (claim 1) comprises heating a substrate on which a predetermined pattern has been exposed to a chemically amplified resist applied to the surface, and using an acid in the resist as a catalyst. Performing a PEB process to cause the irradiation of the chemically amplified resist on the surface of the substrate during the PEB process and repeating the irradiation and scanning of light having a wavelength at which the chemically amplified resist is not exposed, and from the surface of the substrate. The step of sequentially measuring the intensity distribution of the reflected light, and the portion where the reaction has occurred from the intensity distribution sequentially measured at each repetition,
Or a step of detecting at least one dimension of an unreacted portion, comparing the dimension detected at each repetition with a set dimension, and ending the PEB process when the detected dimension becomes equal to the set dimension. And characterized in that: (2) In the method of controlling the size of a resist pattern according to the present invention (claim 2), a substrate in which a predetermined pattern is exposed on a chemically amplified resist applied to a surface is heated, and a reaction using an acid in the resist as a catalyst is performed. Performing a PEB treatment to cause the irradiation, and irradiating and scanning light having a wavelength at which the chemically amplified resist is not exposed to the surface of the substrate during the PEB treatment, and measuring an intensity distribution of reflected light. From the measurement step, from the measured intensity distribution, the portion where the reaction occurred,
Or, the step of detecting at least one dimension of the unreacted portion, and comparing the detected dimension and the set dimension, if the detected dimension and the set dimension are different, return to the intensity distribution measurement step, it was detected A step of terminating the PEB process when the dimension is equal to the set dimension. (3) In the method of controlling the size of a resist pattern according to the present invention (claim 3), a substrate in which a predetermined pattern is exposed on a chemically amplified resist applied on a surface is heated using a plurality of heaters, Performing a PEB process to cause a reaction using an acid as a catalyst, and a wavelength corresponding to each of the heaters, at which the chemically amplified resist is not exposed to the surface of each heating region of the substrate during the PEB process. Performing light irradiation and scanning, and measuring the intensity distribution of the reflected light in each heating area, from the measured intensity distribution, at least one of the portion where the reaction occurred in each heating region, or the unreacted portion A step of detecting a dimension, comparing the dimension detected in each heating area with a set dimension, and in the case of a heating area in which the detected dimension and the set dimension are different, the intensity distribution in the heating area; Returning to the measurement step, ending the PEB process in the heating area when the detected area is equal to the set dimension in the heating area. (3-1) Control the temperature of each heating area independently according to the detected dimensions. (1,2,3-1) Development conditions are determined according to the dimensions detected at the end of the PEB processing. (1,2,3-2) The light irradiation and scanning are performed on a dimension monitoring pattern other than the predetermined pattern of the chemically amplified resist, which is exposed. (4) The heat treatment apparatus of the present invention (Claim 7) heats a substrate on which a predetermined pattern has been exposed to a chemically amplified resist applied on the surface, and causes a reaction using an acid in the resist as a catalyst. A heater unit, a light source unit for irradiating and scanning the substrate with light having a wavelength to which the chemically amplified resist is not exposed, a unit for measuring an intensity distribution of light reflected from the substrate, and a measured intensity. It is characterized by comprising a detection unit for detecting at least one dimension of a portion where the reaction has occurred or an unreacted portion from the distribution, and a control unit for controlling the heater unit according to a detection result. And (5) The heat treatment apparatus of the present invention (claim 8) heats a substrate having a predetermined pattern exposed on a chemically amplified resist applied on the surface, and causes a reaction using an acid in the resist as a catalyst. A heater section comprising a plurality of heaters, and a light source section for irradiating and scanning light having a wavelength at which the chemically amplified resist is insensitive to a surface of each heating region of the substrate corresponding to each heater of the heater section. Measuring means for measuring the intensity distribution of the reflected light from each heating region of the substrate, and, from the measured intensity distribution, at least one of a portion where the reaction has occurred in each heating region, or an unreacted portion. It is characterized by comprising a detection unit for detecting a dimension, and a control unit for independently controlling each heater in accordance with the detection result of the dimension in each heating area. (4,5-1) It is provided with a developing condition determining means for determining a developing condition according to the dimension calculated by the calculating unit.

[Operation] The present invention has the following operation and effects by the above configuration. From the reflected light from the substrate during the PEB processing, while measuring at least one dimension of the reacted portion or the unreacted portion in-situ, the PEB
By performing the processing, a resist pattern having a desired dimension can be efficiently obtained. In other words, the PEB process is performed in consideration of the change in the sensitivity of the resist which depends on the deactivation of the acid of the chemically amplified resist and the retraction which could only be detected by measuring the resist dimensions after development with a dimension SEM or the like. be able to.

Further, by heating with a plurality of heaters, independently detecting dimensions at a number of points corresponding to each heater, and controlling each heater, it is expected that uniformity in the dimension plane by baking will be improved. Further, by controlling each heater based on the detected dimensions to adjust the baking temperature, the in-plane uniformity of the pattern is further improved.

Since the developing time is determined according to the dimension reacted during the baking, a resist pattern having a desired dimension can be obtained. By providing the dimension monitoring pattern on the substrate, the dimension can be measured in-situ without exposing the resist pattern at all.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 shows a heat treatment apparatus with a dimension monitor according to a first embodiment of the present invention.

A mask 16 is placed on the heater 15 that generates heat. The mask 16 is made of a positive chemically amplified resist (resist film thickness of 500) on a 6-inch Cr mask.
nm) and an electron beam lithography system (50 Kev, 84
(C / cm ² ).

The wavelength of 235.
He-Cd laser light source 11 for irradiating 8 nm laser light
Is provided. A polygon mirror 12 and a half mirror 13 are provided on an optical path between the laser light source 11 and the mask 16.
Is arranged. The polygon mirror 12 changes the optical path of the laser light at a cycle set by a clock in the control computer 14 and scans a predetermined area of the mask 16 at a cycle of 1 Hz.

A photomultiplier 17 for measuring the light intensity of the reflected light from the mask 16 is provided. Note that P
The acid generated by exposure to light by the EB treatment reacts with the dissolution inhibiting group. However, since the intensity of the reflected light differs between the reacted part and the unreacted part, the dimensions of the reacted part and the unreacted part described below are determined from the intensity distribution of the reflected light. Can be measured.

The control computer unit 14 is connected to the photomultiplier 17. The control computer unit 14 includes a detection unit that calculates an intensity distribution from the intensity of the reflected light measured by the photomultiplier 17 and detects the size of the reaction unit from the intensity distribution. Further, the control calculator 14 internally includes a heater control unit that compares the detected size with a preset size and controls the heater unit 15 based on the comparison result.

Next, PEB processing (90 ° C.,
A measurement example when the routine condition is performed for 600 seconds will be described with reference to the flowchart in FIG. First, the heater unit 15 is turned on, and the mask 16 is heated to 90 ° C. to start the PEB process (step S1).

Next, with respect to a predetermined region of the mask 16,
The optical path of the laser light emitted from the laser light source 11 is changed using the polygon mirror 12, and scanning is performed at a cycle of 1 Hz set by a clock in the control computer 14 (step S2).

Next, the reflected light from the mask 16 is reflected by the half mirror 13 and the intensity of the reflected light incident on the photomultiplier 17 is measured with high sensitivity, and the measurement result is output to the control computer unit 14. The control calculator 14 obtains the intensity distribution of the reflected light based on the measurement result and the set scanning cycle (step S3).

FIG. 3A shows the intensity distribution of the reflected light. In FIG. 3A, the horizontal axis indicates the length measurement range when scanning with laser light, and the vertical axis indicates the intensity of light reflected from the mask 16. From FIG. 3 (a), it can be seen that the difference between the portion where the acid and the dissolution inhibiting group have reacted by baking and the unreacted portion are observed.

Next, the detection unit in the control computer unit 14
The size of the reaction part is detected from the detected intensity distribution (step S4). The dimension of the reaction part calculated from the intensity distribution of the reflected light in FIG. 3A is 0.51 μm, while the cross section SEM
Was 0.57 μm. Therefore, a correction for adding an offset of 0.06 μm to the pattern dimension obtained from the intensity distribution was performed.

When calculating the size from the intensity distribution of the reflected light, the width at which an intermediate value between the maximum value and the minimum value is taken is defined as the size. The pitch calibration used for obtaining the dimensions from the cross-sectional SEM means that one pitch (line width + space width), line width and space width of the L & S pattern are determined by the SEM.
This is a method of measuring from a photograph using calipers and obtaining dimensions from the respective ratios.

Then, the detected size is compared with a set size previously set in the internal memory of the control computer unit 14 (step S5). If the detected size is different from the set size, the PEB process is further continued and the process returns to step S2.
The intensity distribution of the dimension is measured (Step S3), detected (Step S4), and compared (Step S5).

When the dimension after the correction becomes the set dimension (0.57 μm after the correction), the heater control section in the control computer section 14 determines that the PEB process has ended, and the heater section 15
Is turned off, and the PEB process is automatically terminated (step S6).

FIG. 3B shows the result of monitoring the pattern dimensions which change every moment by scanning the laser every second. The horizontal axis shows the baking time, and the vertical axis shows the pattern dimensions.

In this embodiment, as shown in FIG. 3B, when the baking time reaches 520 seconds, the dimension of the reaction portion becomes 0.57 μm, and the PEB process is stopped.
Since the baking time under the routine condition was 600 seconds, it can be seen that the sample had extremely improved resist sensitivity.

The wavelength of the laser beam applied to the mask is determined with respect to the base polymer and the acid generator (PAG).
For example, it is possible to select a wavelength at which a compound constituting the resist is not exposed, and at which a thinner line width can be measured.

The size of the reaction section obtained by baking the present apparatus is 0.57 μm (design is 0.60 m).
From this, a resist pattern having a desired size (0.60 μm) was obtained by setting the developing time to 115 seconds from an empirical developing speed. By determining the development time in accordance with the size of the reaction portion after the PEB processing, a resist pattern having a desired size can be obtained even when the set size and the size of the reaction portion are different.

The function of the present invention is to control the dimension of a chemically amplified resist by PEB, which is one step before the conventional developing process.
It is characterized by processing. Specifically, an acid is generated by the exposure, and the dissolution inhibiting group reacts with the acid to change the optical refractive index between the portion where the dissolution inhibitor is decomposed and the unreacted portion. Therefore, it is possible to detect a region where the decomposition reaction of the inhibiting group has progressed, and it is possible to monitor the size of the resist pattern in the baking stage before the development process.

[Second Embodiment] FIG. 4 is a diagram showing a schematic configuration of a heat treatment apparatus according to a second embodiment of the present invention. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The feature of this embodiment is that the heater section 22 is divided into three blocks each having an independent heat source, as shown in FIG. Further, the mask 1 corresponding to the three blocks A to C of the heater unit 22 is formed by the beam splitter 20 including the half mirrors 21 a to 21 c.
6 is irradiated with laser light, and the intensity of reflected light corresponding to each of the blocks A to C of the heater unit 22 is measured by the photomultipliers 17a to 17c.
Is used to determine the intensity distribution. Then, the dimensions of the reaction portion are detected from the obtained intensity distributions, the detected dimensions are compared with the set dimensions, and the blocks A to C of the heater unit 22 are independently controlled according to the comparison result. I have.

A 0.6 μm L / S pattern 31 as a dimension monitoring pattern is formed on the resist on the mask 16 at the position where the laser beam irradiation and scanning are performed, as shown in FIG. . Dimension monitor pattern 3
By irradiating and scanning the laser beam 1, the actual pattern is not changed at all by the laser beam irradiation.

FIG. 7 shows how dimensions change at each measurement point. FIG. 7A is a diagram showing measurement points of the mask 16, and FIG. 7B is a diagram showing bake time dependence of dimensions at each measurement point. As the distance from the vicinity of the center of the mask 16 increases (points A → B → C), it can be seen that the size of the reaction portion becomes smaller.

In the actual flow of the PEB processing, first, laser light is scanned on each of the points A to C of the mask 16 and the size of the reaction portion at each of the points A to C is detected from the reflected light intensity distribution. Then, the size detected at each of the points A to C is compared with the set size previously input to the memory of the control computer, and the continuation or end of the PEB process is determined for each point.

The actual baking time was 560 seconds at point A, 620 seconds at point B, and 800 seconds at point C. After completion of the PEB treatment, the dimensions of the reaction portion were set to 0.
It was 57 μm.

The mask 16 was developed for a predetermined developing time of 115 seconds, and a desired resist pattern size of 0.60 μm with very uniform uniformity in a 6-inch mask plane was obtained.

It should be noted that the heater unit 2 depends on the detected size.
2 by controlling the temperature of each block.
It is also possible to control the processing. Whether or not to control the bake temperature can be selected by inputting the allowable bake time and the allowable bake temperature in the memory of the control computer in advance as necessary. For example, the bake allowable temperature is
The temperature does not exceed the glass transition temperature of the resist.
The method of dividing the heater can also change the shape of the heater and the division grid according to the required dimensional accuracy and the object to be heated.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, only the dimensions of the reaction part are detected, but it is also possible to detect the dimensions of the unreacted part or the dimensions of the reaction part and the unreacted part.

Alternatively, the entire surface of the mask may be irradiated with light, and the intensity distribution of the reflected light from the mask may be measured using a CCD camera. Further, a confocal optical system may be arranged on the optical path of the laser beam irradiated on the mask. When a confocal optical system is used, reflected light from a substrate can be detected with high sensitivity. In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0043]

As described above, according to the present invention, the sensitivity fluctuation depending on the withdrawal characteristic of the chemically amplified resist, which could only be detected by measuring the resist dimensions after development with a dimension SEM or the like, can be reduced. By performing the PEB process while detecting at least one dimension of the reacted portion or the unreacted portion during the PEB process, a desired size can be obtained. Further, by taking the development time into consideration from the dimensions obtained in the PEB stage, the desired resist pattern dimensions can be obtained efficiently.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a heat treatment apparatus according to one embodiment.

FIG. 2 is a view showing a flowchart of PEB processing according to the first embodiment;

FIG. 3 is a diagram showing a reflected light intensity from a pattern at a certain time, and a diagram showing a relationship between a baking time and a dimension.

FIG. 4 is a diagram showing a schematic configuration of a heat treatment apparatus according to a second embodiment.

FIG. 5 is a diagram showing a configuration of a heater unit in FIG. 3;

FIG. 6: Pattern dimensions

FIG. 7 is a diagram showing measurement points in a mask, and a diagram showing bake time dependence of a pattern dimension based on the measurement points.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... He-Cd laser light source 12 ... Polygon mirror 13 ... Half mirror 14 ... Control computer part 15 ... Heater part 16 ... Mask 17 ... Photomultiplier 20 ... Beam splitters 21a-c ... Half mirror 22 ... Heater part 31 ... For dimension monitor pattern

Claims (9)

[Claims] 1. A step of heating a substrate on which a predetermined pattern is exposed on a chemically amplified resist applied to a surface thereof, and performing a PEB treatment for causing a reaction using an acid in the resist as a catalyst; Repeating the irradiation and scanning of light having a wavelength at which the chemically amplified resist is insensitive to the surface of the substrate at a constant period, and sequentially measuring the intensity distribution of light reflected from the substrate surface; A step of detecting at least one dimension of the part where the reaction has occurred or an unreacted part from the intensity distribution sequentially measured for each, comparing the dimension detected at each repetition with a set dimension, and detecting When the dimensions become equal to the set dimensions, the PE
A step of ending the B process. 2. A step of heating a substrate on which a predetermined pattern has been exposed on the chemically amplified resist applied on the surface thereof, and performing a PEB process for causing a reaction using an acid in the resist as a catalyst; An intensity distribution measuring step of irradiating and scanning light having a wavelength at which the chemically amplified resist is not exposed to the surface of the substrate, and measuring the intensity distribution of the reflected light. Detecting the dimension of at least one of the generated portion and the unreacted portion; comparing the detected dimension with the set dimension; if the detected dimension and the set dimension are different, return to the intensity distribution measuring step. If the detected dimension is equal to the set dimension, the PEB
And a step of ending the processing. 3. A plurality of heaters are used to heat a substrate on which a predetermined pattern has been exposed on a chemically amplified resist applied on the surface, and a PEB process is performed to cause a reaction using an acid in the resist as a catalyst. The step, the surface of the heating region corresponding to each heater of the substrate during the PEB processing, irradiation and scanning of light of a wavelength that the chemically amplified resist is not sensitive, and the reflected light in each heating region Measuring the intensity distribution; detecting, from the measured intensity distribution, at least one dimension of a portion where the reaction has occurred in each heating region or an unreacted portion; and a dimension detected in each heating region. And the set dimensions, and if the detected area is different from the set dimensions in the heating area,
Returning to the intensity distribution measuring step in the heating area, in the case of a heating area in which the detected dimension is equal to the set dimension,
Ending the PEB process in the heating region. 4. The apparatus according to claim 2, wherein the temperature of each heating zone is independently controlled according to the detected size.
3. The method for controlling the dimension of a resist pattern according to item 1. 5. The method for controlling the size of a resist pattern according to claim 1, wherein the developing condition is determined according to the size detected at the end of the PEB processing. 6. The method according to claim 1, wherein said light irradiation and scanning are performed on a dimension monitoring pattern other than said predetermined pattern of said chemically amplified resist.
The method for controlling the size of a resist pattern according to any one of the above. 7. A heater section for heating a substrate on which a predetermined pattern has been exposed to a chemically amplified resist applied on the surface thereof to cause a reaction using an acid in the resist as a catalyst; A light source unit that irradiates and scans light with a wavelength at which the chemically amplified resist is insensitive, and a unit that measures an intensity distribution of light reflected from the substrate; and, from the measured intensity distribution, a portion where the reaction occurs, or A heat treatment apparatus comprising: a detection unit that detects at least one dimension of an unreacted portion; and a control unit that controls the heater unit according to a detection result. 8. A heater section comprising a plurality of heaters for heating a substrate on which a predetermined pattern has been exposed to a chemically amplified resist applied on the surface thereof, and causing a reaction using an acid in the resist as a catalyst. A light source unit for irradiating and scanning light having a wavelength at which the chemically amplified resist is insensitive to the surface of each heating region of the base corresponding to each heater of the heater unit; and A measuring unit for measuring the intensity distribution of the reflected light; a detection unit for detecting at least one dimension of a portion where the reaction has occurred or an unreacted portion in each heating region from each measured intensity distribution; A heat treatment apparatus comprising: a control unit that independently controls each heater in accordance with a result of detecting a dimension in a region. 9. The heat processing apparatus according to claim 7, further comprising a developing condition determining means for determining a developing condition in accordance with the dimension calculated by said calculating unit.