JP3672529B2 - Film quality evaluation method and apparatus, line width variation evaluation method and apparatus, and processing method and apparatus having line width variation evaluation function - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a film quality evaluation method and apparatus for a substrate to be processed such as a semiconductor wafer on which a resist film is formed, a line width variation evaluation method and apparatus, a processing method having a film quality evaluation function, and an apparatus therefor.
[0002]
[Prior art]
In general, in the manufacturing process of a semiconductor wafer, a photolithography technique is used to form a resist pattern on the surface of a semiconductor wafer, an LCD substrate, or the like (hereinafter referred to as a wafer). In this photolithography technique, a resist film is formed on a surface of a wafer or the like by supplying (discharging, applying) a resist solution, a resist film forming process for exposing the circuit pattern to the formed resist film, and a post-exposure process. A developing process for supplying (discharging, applying) a developing solution to the wafer or the like and performing a developing process.
[0003]
In addition, between the above processing steps, for example, a heat treatment performed between the resist coating step and the exposure processing step to evaporate the residual solvent in the resist film and improve the adhesion between the wafer and the resist film. {Pre-bake (PAB)}, in order to prevent the generation of fringe between the exposure process and the development process, or to induce an acid-catalyzed reaction in a chemically amplified resist (CAR) The residual solvent in the resist and the rinsing liquid taken into the resist during the development are removed after the heat treatment {post-exposure bake (PEB)} and the development process, thereby improving the penetration during wet etching. Various heat treatments such as heat treatment (post-bake) are performed.
[0004]
In the photolithography process, as the circuit pattern and line width (CD) become finer, the uniformity of the pattern line width in the wafer surface (CD uniformity) is strictly demanded, which greatly affects the pattern dimension. In addition to the development process and the PEB process which have been performed, it is required to improve the line width variation factor in the process before exposure.
[0005]
Therefore, in the past, line width variation was improved by improving the film thickness uniformity of the resist film formed on the wafer surface. However, in recent years, even if the film thickness of the resist film is uniform, for example, the amount distribution of the resist constituents such as the amount of the solvent remaining in the resist film, the ratio distribution difference of the protecting groups in the resist, the polymer in the resist Variation in the line width due to film quality changes due to differences in the chemical and physical properties (hereinafter referred to as film quality) of the resist film, such as differences in the concentration state, has been confirmed, affecting the film quality uniformity of the resist film. It is very important to elucidate the factors.
[0006]
[Problems to be solved by the invention]
Conventionally, however, in order to evaluate the influence of factors such as processing temperature and processing atmosphere in the pre-exposure process on the film quality uniformity, as shown in FIG. Since the line width in the wafer surface had to be measured using an SEM (scanning electron microscope) after performing the above, there was a problem that it took much time and labor. In addition, when the entire process of photolithography technology is performed on a wafer or the like, the factors that affect the line width are not only the factors in the pre-exposure process, but also the factors of the entire process, and therefore the line width variation is affected. There is a problem that the contribution of the pre-exposure factor is unclear.
[0007]
The present invention has been made in view of the above circumstances, and the film quality evaluation method capable of evaluating the film quality uniformity of a resist film in a simple and short time while the process factor given to the line width variation can be separated before and after the exposure. Providing an apparatus, and further, a line width variation evaluation method and apparatus capable of predicting line width from evaluation of film quality uniformity, and a process having a film quality evaluation function capable of improving line width from line width prediction It is an object to provide a method and apparatus thereof.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the film quality evaluation method of the present invention comprises a step of supplying a resist solution to the surface of a substrate to be processed to form a resist film, and heating the substrate to be processed to remove a solvent in the resist film. A first film thickness measuring step for measuring the film thickness of the resist film at a plurality of locations on different concentric circles after the evaporation, and a step for performing a developing process by supplying a developer to the surface of the substrate to be processed And a second film thickness measuring step for measuring the film thickness of the resist film at a plurality of locations on the different concentric circles of the substrate to be processed, and the first film thickness measurement and the second film thickness. And a step of calculating a film reduction amount at a plurality of locations on different concentric circles based on a difference in measurement values obtained by the measurement, and evaluating a film quality based on the film reduction amount (claim 1). ).
[0009]
The line width variation evaluation method of the present invention includes a step of supplying a resist solution to the surface of a substrate to be processed to form a resist film, and heating the substrate to be processed to evaporate a solvent in the resist film. A first film thickness measuring step of measuring the film thickness of the resist film at a plurality of locations on different concentric circles, a step of supplying a developing solution to the surface of the substrate to be processed, and a developing process, and a developing process Obtained by the second film thickness measurement step for measuring the film thickness of the resist film, the first film thickness measurement, and the second film thickness measurement at a plurality of locations on the different concentric circles of the processed substrate. A step of calculating the amount of film reduction for a plurality of locations on different concentric circles due to the difference in the measured value, the above-mentioned film thickness reduction amount, correlation information between the film thickness reduction amount and the line width obtained in advance, and the line width fluctuation allowable range, And a step of evaluating line width variation based on Characterized in that (claim 2).
[0010]
The processing method having the film quality evaluation function of the present invention includes a resist film forming step of forming a resist film by supplying a resist solution to the surface of the substrate to be processed, and a first heating step of heating the substrate to be processed. Then, an exposure process for exposing the pattern to the substrate to be processed, a second heating process for heating the substrate to be processed after the exposure, and development for supplying a developer to the surface of the substrate to be processed for development processing And a step of supplying a resist solution to the surface of the substrate to be evaluated to form a resist film, and heating the substrate to be evaluated to remove the solvent in the resist film. After the evaporation, a first film thickness measurement step for measuring the film thickness of the resist film at a plurality of locations on different concentric circles, and then a developer is supplied to the surface of the substrate to be evaluated for development processing. A process of performing A second film thickness measuring step for measuring the film thickness of the resist film at a plurality of locations on the different concentric circles of the substrate to be evaluated for image evaluation, the first film thickness measurement and the second film; The step of calculating the film thickness for a plurality of locations on different concentric circles due to the difference in the measurement values obtained by the thickness measurement, the above-mentioned film thickness, the correlation information between the previously obtained film thickness and the line width, and the line A step of evaluating line width variation based on the width variation allowable range, and a resist film forming step, a first heating step, an exposure step, a second heating step, and a development step based on the evaluation of the line width variation. Any one or more of the processing temperature, the processing atmosphere, and the exposure amount of the exposure process are controlled to correct the line width variation within the allowable range of the line width (Claim 3).
[0011]
The film quality evaluation apparatus of the present invention embodies the film quality evaluation method according to claim 1, comprising a resist film forming means for forming a resist film by supplying a resist solution to the surface of a substrate to be processed; A heating means for heating the substrate to evaporate the solvent in the resist film, a development processing means for supplying a developing solution to the surface of the substrate to be processed and performing a developing process, and a plurality of locations on different concentric circles of the substrate to be processed The film thickness measurement means for measuring the film thickness of the resist film before the development process and the film thickness of the resist film after the development process, and on different concentric circles due to the difference in the measurement values obtained by the film thickness measurement means And a means for evaluating the film quality based on the film thickness reduction amount. (Claim 4)
[0012]
A line width variation evaluation apparatus according to the present invention embodies the line width variation evaluation method according to claim 2 and provides a resist film forming means for forming a resist film by supplying a resist solution to the surface of a substrate to be processed. And a heating means for heating the substrate to be processed to evaporate a solvent in the resist film, a developing processing means for supplying a developing solution to the surface of the substrate to be processed and performing a developing process, and the substrate to be processed are different. The difference between the film thickness measurement means for measuring the film thickness of the resist film before the development process and the film thickness of the resist film after the development process, and the measurement values obtained by the film thickness measurement means for a plurality of locations on the concentric circles. To calculate the amount of film reduction for a plurality of locations on different concentric circles, and to calculate the line width variation based on the above-mentioned film thickness reduction amount, the correlation information between the film thickness reduction amount and the line width obtained in advance, and the line width variation allowable range. And an evaluation means for evaluating To (claim 5).
[0013]
A processing apparatus having a line width variation evaluation function according to the present invention embodies the processing method having a film quality evaluation function according to claim 3, and a resist film forming means for supplying a resist solution to the surface of a substrate to be processed. A first heating unit for heating the substrate to be processed, an exposure unit for exposing the pattern to the substrate to be processed, a second heating unit for heating the substrate to be processed after the exposure, and the substrate to be processed In a processing apparatus comprising: a development processing means for developing a film thickness measurement for measuring a thickness of a resist film before and after the development processing of the evaluation target substrate developed by the development processing means The film thickness reduction is calculated for a plurality of locations on different concentric circles by the difference between the measurement value obtained by the measurement means and the film thickness measurement means, and the film thickness reduction is correlated with the previously obtained film thickness reduction and the line width. Information and line width variation allowance And an evaluation unit that evaluates the line width variation based on the range, and based on the evaluation of the line width variation, the resist film forming unit, the first heating unit, the exposure unit, the second heating unit, and the development Any one or more of each processing temperature of the processing means, processing atmosphere, and exposure amount of the exposure means can be controlled (claim 6).
[0014]
According to the first and fourth aspects of the present invention, the film quality can be evaluated based on the amount of film reduction of the substrate to be processed without going through the exposure process or the PEB process, so that the line width is affected in the exposure process or the PEB process. Factors can be excluded, and film quality evaluation before exposure can be performed easily and accurately in a short time.
[0015]
According to the second and fifth aspects of the present invention, the line width can be predicted by the amount of film reduction without going through the exposure process or the PEB process. The status of the subsequent device can be confirmed easily and in a short time.
[0016]
According to the third and sixth aspects of the present invention, since the film thickness measuring means is mounted in the apparatus, the line width can be predicted from the amount of film reduction, and each process of the photolithography technique can be controlled. The wafer in-plane uniformity (CD uniformity) can be quickly corrected by a simple method.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings.
[0018]
1 is a schematic plan view of an embodiment of a resist solution coating / development processing system, FIG. 2 is a front view of FIG. 1, and FIG. 3 is a rear view of FIG.
[0019]
In the above processing system, a plurality of semiconductor wafers W (hereinafter referred to as “wafers W”) as substrates to be processed are loaded into or out of the system from the outside in units of a plurality of wafer cassettes, for example, 25 wafers. A cassette station 10 (carrying unit) for carrying W in and out, and various single-wafer processing units for performing predetermined processing on the wafer W one by one in the coating and developing process are arranged in multiple stages at predetermined positions. The processing station 20 having the processing apparatus of the present invention and the interface unit 30 for transferring the wafer W between the processing station 20 and an exposure apparatus 40 (EXP) provided adjacent to the processing station 20 are mainly used. The part is composed.
[0020]
As shown in FIG. 1, the cassette station 10 includes a plurality of, for example, up to four wafer cassettes 1 at the position of the projection 3 on the cassette mounting table 2 with the respective wafer entrances facing the processing station 20 side. Wafer transfer tweezers 4 mounted in a line along the direction and movable in the cassette arrangement direction (X direction) and in the wafer arrangement direction (Z direction) of the wafer W accommodated in the wafer cassette 1 along the vertical direction. Is configured to be selectively transferred to each wafer cassette 1. Further, the wafer transfer tweezers 4 are configured to be rotatable in the horizontal θ direction, and include an alignment unit (ALIM) and an extension unit (EXT) belonging to a multi-stage unit portion of a third group G3 on the processing station 20 side to be described later. ) Can also be transported.
[0021]
As shown in FIG. 1, the processing station 20 is provided with a vertical transfer type main wafer transfer mechanism 21 at the center, and a set of all the processing units around a chamber 22 that accommodates the main wafer transfer mechanism 21. Alternatively, they are arranged in multiple stages over a plurality of sets. In this example, five sets G1, G2, G3, G4 and G5 have a multistage arrangement, and the first and second sets G1, G2 are arranged in parallel on the front side of the system (front side in FIG. 1). The multistage unit of the third group G3 is arranged adjacent to the cassette station 10, the multistage unit of the fourth group G4 is arranged adjacent to the interface part 30, and the multistage unit of the fifth group G5 is arranged on the back side. Is arranged.
[0022]
In this case, as shown in FIG. 2, in the first group G1, two spinner type processing units that perform predetermined processing by placing the wafer W on a spin chuck (not shown) in the cup 23, for example, A resist coating unit (COT) for supplying a resist solution to the surface of the wafer W to form a resist film, and a developing unit (DEV) for supplying a developing solution to the surface of the wafer W to perform a development process are vertically arranged in two stages. It is superimposed on. Similarly, in the second group G2, two spinner type processing units, for example, a resist coating unit (COT) and a developing unit (DEV) are stacked in two stages from the bottom in the vertical direction. The reason why the resist coating unit (COT) is arranged on the lower side in this way is that the drain of the resist solution is troublesome both in terms of mechanism and maintenance. However, the resist coating unit (COT) can be arranged in the upper stage as required.
[0023]
As shown in FIG. 3, in the third group G3, an oven-type processing unit that performs a predetermined process by placing the wafer W on the wafer mounting table 24, for example, a cooling unit (COL) that cools the wafer W, and the wafer W Adhesion unit (AD) for performing hydrophobic treatment, alignment unit (ALIM) for aligning wafer W, extension unit (EXT) for loading / unloading wafer W, and four hot plate units for baking wafer W (HP) is stacked, for example, in eight steps in order from the bottom in the vertical direction. Similarly, the fourth group G4 is an oven-type processing unit such as a cooling unit (COL), an extension / cooling unit (EXTCOL), an extension unit (EXT), a cooling unit (COL), and two chilling hot plate units having a rapid cooling function. (CHP) and two hot plate units (HP) are stacked in, for example, eight stages in order from the bottom in the vertical direction.
[0024]
As described above, the cooling unit (COL) and the extension cooling unit (EXTCOL) having a low processing temperature are arranged in the lower stage, and the hot plate unit (HP), the chilling hot plate unit (CHP) and the adhesion unit having a high processing temperature. By disposing (AD) in the upper stage, it is possible to reduce thermal mutual interference between units. Of course, a random multi-stage arrangement is also possible.
[0025]
As shown in FIG. 1, in the processing station 20, the third and fourth sets G3 and G4 of multistage units (spinner type processing units) adjacent to the first and second sets of G1 and G2 (spinner type processing units) ( Ducts 65 and 66 are vertically cut in the side walls of the oven-type processing unit. Downflow clean air or specially temperature-adjusted air flows through these ducts 65 and 66. By this duct structure, the heat generated in the oven type processing units of the third and fourth groups G3 and G4 is cut off and does not reach the spinner type processing units of the first and second groups G1 and G2. ing.
[0026]
Further, in this processing system, a fifth stage G5 multi-stage unit can be arranged on the back side of the main wafer transfer mechanism 21 as shown by a dotted line in FIG. The multistage units of the fifth group G5 can move sideways along the guide rail 67 as viewed from the main wafer transfer mechanism 21. Therefore, even when the multi-stage unit of the fifth group G5 is provided, the space portion is secured by sliding the unit, so that the maintenance work can be easily performed from the back with respect to the main wafer transfer mechanism 21.
[0027]
The interface unit 30 has the same dimensions as the processing station 20 in the depth direction, but is made small in the width direction. A portable pickup cassette 31 and a stationary buffer cassette 32 are arranged in two stages on the front part of the interface part 30, a peripheral exposure device 33 is arranged on the back part, and a wafer is located in the center part. A transfer arm 34 is provided.
[0028]
As shown in FIG. 6, the peripheral exposure apparatus 33 has a casing 79 having an intake fan 77 on one side wall and an exhaust port 78 on the opposite side wall, and a casing 79 provided in the casing 79. It is mainly composed of a mounting table 71 that is held by suction and is rotatable by a driving means such as a motor 74, and an irradiation unit 76 that emits light for exposure. Further, the peripheral exposure apparatus 33 is provided with a film thickness measuring device 25 (film thickness measuring means) capable of measuring the film thickness of the resist film.
[0029]
The film thickness measuring instrument 25 includes a film thickness sensor 72 that measures the film thickness of the resist film, the above-described mounting table 71 shared for peripheral exposure, and a guide rail 75 that can move the mounting table 71 horizontally, for example, horizontally. And a moving means constituted by a ball screw mechanism (not shown) and the like, and a wafer position detection sensor 73 capable of detecting the position of the wafer W.
[0030]
The film thickness sensor 72 is provided above the mounting table 71. The film thickness sensor 72 irradiates the resist film of the wafer W with light such as laser light, senses the reflected light, and utilizes the interference of the reflected light. It is formed so that the film thickness can be measured. The film thickness sensor 72 is electrically connected to the CPU 100 and is formed so that the detected film thickness data can be transmitted to the CPU 100.
[0031]
The wafer position detection sensor 73 is, for example, a light emitting unit 73a that emits light such as laser from above the mounting table 71, and light that is emitted from the light emitting unit 73a at a position facing the wafer W, such as a CCD sensor. The light receiving unit 73b is formed so that the position of the wafer W in the radial direction can be accurately detected. Further, the wafer position detection sensor 73 is electrically connected to the CPU 100 and is formed so that the detected position data can be transmitted to the CPU 100.
[0032]
According to the film thickness measuring instrument 25 configured as described above, the mounting table 71 is rotated and moved horizontally, the film thickness of the resist film is measured at a plurality of locations on different concentric circles of the wafer W, and the film thickness uniformity is measured. Can be inspected.
[0033]
The wafer transfer arm 34 is configured to move in the X and Z directions and transfer the cassettes 31 and 32 and the peripheral exposure apparatus 33. Further, the wafer transfer arm 34 is configured to be rotatable in the θ direction, and the wafer delivery on the extension unit (EXT) belonging to the multi-stage unit of the fourth group G4 on the processing station 20 side and on the adjacent exposure apparatus 40 (EXP) side. It is comprised so that it can also convey also to a stand (not shown).
[0034]
The processing system configured as described above is installed in the clean room 50, and the cleanliness of each part is increased by an efficient vertical laminar flow method in the system.
[0035]
Next, the operation of the processing system will be described. First, in the cassette station 10, the tweezers 4 for wafer transfer access the cassette 1 containing unprocessed wafers W on the cassette mounting table 2, and take out one wafer W from the cassette 1. When the wafer tweezers 4 takes out the wafer W from the cassette 1, it moves to the alignment unit (ALIM) arranged in the multi-stage unit of the third group G3 on the processing station 20 side, and in the unit (ALIM) A wafer W is placed on the wafer mounting table 24. The wafer W undergoes orientation flat alignment and centering on the wafer mounting table 24. Thereafter, the main wafer transfer mechanism 21 accesses the alignment unit (ALIM) from the opposite side, and receives the wafer W from the wafer mounting table 24.
[0036]
In the processing station 20, the main wafer transfer mechanism 21 first carries the wafer W into an adhesion unit (AD) belonging to the multistage unit of the third group G3. Within this adhesion unit (AD), the wafer W is subjected to a hydrophobic treatment. When the hydrophobization process is completed, the main wafer transfer mechanism 21 unloads the wafer W from the adhesion unit (AD), and then cools the cooling units (belonging to the third group G3 or the fourth group G4 multi-stage unit). COL). In this cooling unit (COL), the wafer W is cooled to a set temperature before the resist coating process, for example, 23 ° C. When the cooling process is completed, the main wafer transfer mechanism 21 unloads the wafer W from the cooling unit (COL), and then to the resist coating unit (COT) belonging to the multistage unit of the first group G1 or the second group G2. Carry in. In this resist coating unit (COT), the wafer W is coated with a resist with a uniform film thickness on the wafer surface by spin coating.
[0037]
When the resist coating process is completed, the main wafer transfer mechanism 21 unloads the wafer W from the resist coating unit (COT) and then loads it into the hot plate unit (HP). In the hot plate unit (HP), the wafer W is mounted on a mounting table and pre-baked at a predetermined temperature, for example, 100 ° C. for a predetermined time. Thus, the residual solvent (solvent) can be removed by evaporation from the coating film on the wafer W. When pre-baking is completed, the main wafer transfer mechanism 21 unloads the wafer W from the hot plate unit (HP), and then transfers the wafer W to the extension cooling unit (EXTCOL) belonging to the multistage unit of the fourth group G4. Within this unit (COL), the wafer W is cooled to a temperature suitable for the peripheral exposure process in the next process, that is, the peripheral exposure apparatus 33, for example, 24 ° C. After this cooling, the main wafer transfer mechanism 21 transfers the wafer W to the extension unit (EXT) immediately above, and places the wafer W on a mounting table (not shown) in the unit (EXT). When the wafer W is mounted on the mounting table of the extension unit (EXT), the wafer transfer arm 34 of the interface unit 30 accesses from the opposite side to receive the wafer W. Then, the wafer transfer arm 34 carries the wafer W into the peripheral exposure apparatus 33 in the interface unit 30. Here, the wafer W is exposed to the edge portion. In the peripheral exposure apparatus 33, it is possible to periodically measure the film thickness of the wafer W using the film thickness measuring device 25 and perform the film thickness uniformity inspection.
[0038]
When the peripheral exposure is completed, the wafer transfer arm 34 unloads the wafer W from the peripheral exposure apparatus 33 and transfers it to a wafer receiving table (not shown) on the side of the adjacent exposure apparatus 40 (EXP). In this case, the wafer W may be temporarily stored in the buffer cassette 32 before being transferred to the exposure apparatus 40 (EXP).
[0039]
When the entire exposure is completed in the exposure apparatus 40 (EXP) and the wafer W is returned to the wafer receiving table on the exposure apparatus 40 (EXP) side, the wafer transfer arm 34 of the interface unit 30 accesses the wafer receiving table. The wafer W is received, and the received wafer W is loaded into an extension unit (EXT) belonging to the multi-stage unit of the fourth group G4 on the processing station 20 side, and placed on the wafer receiving table. Also in this case, the wafer W may be temporarily stored in the buffer cassette 32 in the interface unit 30 before being transferred to the processing station 20 side.
[0040]
The wafer W placed on the wafer receiving table is transferred to the chilling hot plate unit (CHP) by the main wafer transfer mechanism 21 to prevent fringes, or an acid catalyst in the chemically amplified resist (CAR). A post-exposure bake (PEB) treatment is applied to induce the reaction.
[0041]
Thereafter, the wafer W is carried into a developing unit (DEV) belonging to the multistage unit of the first group G1 or the second group G2. In the developing unit (DEV), the wafer W is placed on a spin chuck, and the developer is uniformly applied to the resist on the surface of the wafer W by, for example, a spray method. When the development is completed, a rinse solution is applied to the surface of the wafer W to wash away the developer.
[0042]
When the developing process is completed, the main wafer transfer mechanism 21 unloads the wafer W from the developing unit (DEV), and then the hot plate unit (HP) belonging to the third group G3 or the multistage unit of the fourth group G4. Carry in. In this unit (HP), the wafer W is post-baked for a predetermined time at 100 ° C., for example. Thereby, the resist swollen by development is cured, and chemical resistance is improved.
[0043]
When the post-baking is completed, the main wafer transfer mechanism 21 unloads the wafer W from the hot plate unit (HP), and then loads it into one of the cooling units (COL). Here, after the wafer W returns to room temperature, the main wafer transfer mechanism 21 next transfers the wafer W to the extension unit (EXT) belonging to the third group G3. When the wafer W is mounted on a mounting table (not shown) of the extension unit (EXT), the wafer transfer tweezers 4 on the cassette station 10 side accesses from the opposite side and receives the wafer W. The wafer transfer tweezers 4 put the received wafer W into a predetermined wafer storage groove of the processed wafer storage cassette 1 on the cassette mounting table, and the processing is completed.
[0044]
◎ Film quality evaluation
As described above, in the normal photolithography process of the wafer W, the exposed portion of the positive resist is a developer by exposing the pattern to the surface of the wafer W coated with the resist and then developing the pattern. It is dissolved and removed. However, even if this positive resist is not exposed to light, it is recognized that it is slightly dissolved in the developer, and the amount of dissolution varies depending on the difference in film quality. Therefore, if the wafer W coated with the resist is developed without being exposed, and the amount of dissolution is expressed by using the difference in film thickness of the resist film before and after the development process (hereinafter referred to as the amount of film reduction), The film quality can be evaluated.
[0045]
Further, there is a correlation between the line width of the circuit pattern and the amount of film reduction. For example, as shown in FIGS. 4A and 4B, the line width becomes thicker at a position where the amount of film reduction is small. The line width becomes thinner at positions where the amount is large. Therefore, in order to make the line width of the circuit pattern uniform, it is important to evaluate the uniformity of the film reduction amount (film quality uniformity).
[0046]
An embodiment of the film quality evaluation apparatus of the present invention for evaluating the film quality of the wafer W processed by the resist solution coating / development processing system and the like will be described below with reference to FIG.
[0047]
As shown in FIG. 5, the film quality evaluation apparatus includes a resist coating unit (COT) that supplies (drops and coats) a resist solution to the surface of the wafer W to form a resist film, and heats the wafer W in the resist film. A hot plate unit (HP) that evaporates the solvent (solvent), a developing unit (DEV) that performs development processing by supplying (dropping and applying) a developing solution to the surface of the wafer W, and different concentric circles on the wafer W The film thickness measuring device 25 (see FIG. 6) for measuring the film thickness of the resist film before the development processing and the film thickness of the resist film after the development processing, and the film thickness measuring device 25 were obtained. Based on the difference in measurement values, the amount of film reduction is calculated for a plurality of locations on different concentric circles, and the evaluation means for evaluating the film quality based on the amount of film reduction, for example, CPU 100 is configured.
[0048]
In this case, the film quality evaluation apparatus can share the resist coating unit (COT), the hot plate unit (HP), and the developing unit (DEV) of the resist solution coating / development processing system.
[0049]
Further, the film thickness measuring device 25 can be provided as an independent unit, or for example, the one provided in the peripheral exposure apparatus 33 described above can be used (see FIG. 6). It is of course possible to provide the film thickness measuring device 25 in another unit.
[0050]
Next, a film quality evaluation method for the wafer W using the film quality evaluation apparatus will be described with reference to FIG.
[0051]
First, an evaluation wafer W (hereinafter referred to as a dummy wafer DW) is prepared {FIG. 7 (a)}, and a positive resist solution is supplied (dropped and applied) to the surface of the dummy wafer DW by a resist coating unit (COT). Thus, the resist film 80 is formed so as to be as uniform as possible (FIG. 7B).
[0052]
Next, after heating the dummy wafer DW in the hot plate unit (HP) and evaporating the solvent (solvent) in the resist film 80 {FIG. 7 (c)}, the film thickness measuring device 25 is used to form different concentric circles. The film thickness of the resist film 80 is measured at a plurality of locations {FIG. 7 (d)}.
[0053]
Next, the dummy wafer DW is transported to the development unit (DEV), and the developer is supplied to the surface of the dummy wafer DW for development processing {FIG. 7 (e)}, and then the film thickness is measured again before the development processing. The film thickness of the resist film 80 is measured using the film thickness measuring instrument 25 on the same circumference as the broken part, preferably the same part {FIG. 7 (f)}.
[0054]
The measurement value obtained as described above is sent to the CPU 100 (evaluation means), and the amount of film reduction is calculated based on the difference in film thickness before and after the development process, and the film quality uniformity is based on the amount of film reduction at a plurality of locations. Is evaluated {FIG. 7 (g)}.
[0055]
That is, if the amount of film reduction is uniform, it is evaluated that the film quality is uniform, and if the amount of film reduction is nonuniform, it is evaluated that the film quality is also nonuniform.
[0056]
By evaluating the film quality in this way, the film quality can be easily and accurately evaluated in a short time by the amount of film reduction of the dummy wafer DW without going through the exposure process or the PEB process. It can be used for studies on factors such as processing temperature and processing humidity that affect the film quality, that is, the line width.
[0057]
In addition, according to this film quality evaluation method, the film thickness uniformity after the PAB process can be simultaneously evaluated from the measurement result of the film thickness before development.
[0058]
◎ Evaluation of line width fluctuation
There is a different correlation between the line width of the circuit pattern and the amount of film reduction depending on the type of resist. For example, with respect to the resist A and the resist B to be used, the PAB processing temperature is changed by ± 2 to 5 ° C. and the processing time is changed by about ± 5 to 15 sec. As shown in FIG. 8, there is a proportional relationship between the film thickness and the amount of film reduction. Therefore, in the wafer W plane, the range in which the non-uniformity of the line width is allowed in the device design, in other words, the range in which the error between the maximum line width and the minimum line width in the wafer plane is allowed (hereinafter referred to as the line width). If the fluctuation allowable range is obtained, the fluctuation allowable range of the film thickness can be calculated, and the line width fluctuation can be evaluated by the film thickness.
[0059]
In the following, an embodiment of the line width variation evaluating apparatus of the present invention for evaluating the line width of the wafer W processed by the resist solution coating / developing system or the like will be described.
[0060]
Similar to the film quality evaluation apparatus described above, the line width variation evaluation apparatus heats the wafer W with a resist coating unit (COT) for supplying a resist solution to the surface of the wafer W (dropping and coating) to form a resist film. A hot plate unit (HP) for evaporating the solvent (solvent) in the resist film, a developing unit (DEV) for supplying (dropping, applying) a developing solution to the surface of the wafer W and performing a developing process, A film thickness measuring device 25 (film thickness measuring means) for measuring the film thickness of the resist film before development processing and the film thickness of the resist film after development processing at a plurality of locations on different concentric circles, and this film thickness measuring device The CPU 100 is electrically connected to the CPU 100 and calculates the amount of film reduction based on the difference between the measurement values obtained by the film thickness measuring instrument. Further, the CPU 100 stores the line width variation allowable range and correlation information between the film thickness and the line width obtained in advance, and the line width variation can be evaluated based on the information and the film thickness. It is configured as follows.
[0061]
Next, a line width variation evaluation method for the wafer W using the line width variation evaluation apparatus will be described with reference to FIG. 8 or FIG.
[0062]
First, the CPU 100 obtains an in-plane variation allowable range of the film reduction amount from the line width variation allowable range based on the correlation information between the film decrease amount and the line width obtained in advance. For example, since the correlation value of the amount of film reduction with respect to the line width variation of the resist A (the reciprocal of the slope of the solid line in FIG. 8) is 2 nm / nm from FIG. 8, the line width variation allowable range of the wafer W is 10 nm. Then, the allowable variation range of the film thickness reduction amount of the resist A is 20 mm.
[0063]
Next, the amount of film reduction is detected at a plurality of locations on different concentric circles of the dummy wafer DW by the same method as the film quality evaluation method described above (see FIG. 7).
[0064]
Next, the line width variation is evaluated by comparing whether or not the film thicknesses at a plurality of locations on different concentric circles of the dummy wafer DW are within the film thickness variation allowable range. For example, as shown by the solid line in FIG. 9, when the film thickness of the resist A is within the in-plane variation allowable range of 20 mm, it can be determined that the processing by the resist solution coating / developing processing system is normal. As shown by the one-dot chain line in FIG. 9, when the film thickness of the resist A is not within the in-plane variation allowable range of 20 mm, it can be determined that the pre-exposure unit and the process need to be confirmed. .
[0065]
The expected line width (line width fluctuation) is calculated based on the detected film thickness and the correlation information between the film thickness obtained in advance and the line width, and the expected line width is within the line width fluctuation allowable range. It is also possible to evaluate the line width variation depending on whether or not there is.
[0066]
By evaluating the line width in this way, the width of the in-plane film reduction amount of the wafer W is monitored when the resist solution coating / development system is started up, when the chemical solution is replaced, or after a certain period of time elapses. The coating / developing system can be checked.
[0067]
◎ Processing device and processing method having line width variation evaluation function
As described above, there is a different correlation between the line width of the circuit pattern and the amount of film reduction depending on the type of resist. In addition, from the conventional research, the circuit pattern line widths of the resist coating unit (COT), the hot plate unit (HP), the exposure device 40 (EXP), the chilling hot plate unit (CHP), and the developing unit (DEV) are as follows. It has also been clarified that it varies depending on the processing temperature, the processing atmosphere, and the exposure amount of the exposure apparatus 40 (EXP).
[0068]
Therefore, the line width variation of the pattern is evaluated from the amount of film reduction, and based on the evaluation, a resist coating unit (COT), a hot plate unit (HP), an exposure apparatus 40 (EXP), a chilling hot plate unit (CHP), By controlling any one or more of each processing temperature of the developing unit (DEV), processing atmosphere, and exposure amount of the exposure apparatus 40 (EXP), the wafer surface uniformity (CD uniformity) of the pattern line width can be simplified. Can be corrected.
[0069]
Hereinafter, an embodiment of a processing apparatus having a line width variation evaluation function of the present invention will be described.
[0070]
The processing apparatus having the line width variation evaluation function of the present invention is at least Wafer W A resist coating unit (COT) {resist film forming means} for supplying a resist solution to the surface of Wafer W A hot plate unit (HP) {first heating means} for heating Wafer W An exposure apparatus 40 (EXP) {exposure means} for exposing a pattern to Wafer W A chilling hot plate unit (CHP) {second heating means} for heating Wafer W Development unit (DEV) {development processing means}. Accordingly, the processing apparatus having the line width variation evaluation function according to the present invention can be configured by a processing apparatus such as the resist solution coating / development processing system described above. That is, in the processing apparatus, a resist film is formed by a resist coating unit (COT), heated by a hot plate unit (HP) to evaporate a solvent (solvent) in the resist film, and then developed by a developing unit (DEV). Reduced by the difference between the film thickness measuring device 25 (film thickness measuring means) for measuring the film thickness of the resist film before and after the development processing of the dummy wafer DW to be processed, and the measurement value obtained by the film thickness measuring device 25 A CPU 100a (evaluation means) that calculates the film amount and evaluates the line width variation based on the film thickness amount and the correlation information between the film thickness amount and the line width determined in advance is used to evaluate the line width variation. Based on the resist coating unit (COT), hot plate unit (HP), exposure apparatus 40 (EXP), chilling hot plate unit (CHP), development unit (D Each treatment temperature V), is intended to be capable of controlling any one or more of the exposure amount of the processing atmosphere and the exposure apparatus 40 (EXP).
[0071]
Next, a processing method using the processing apparatus having the line width variation evaluation function will be described with reference to FIGS. 1 to 3 and FIG. Here, the solid line in FIG. 10 indicates the flow of the dummy wafer DW, and the broken line indicates the flow of the wafer W in a normal photolithography process. A two-dot chain line indicates a transmission direction of an electric signal (detection signal and control signal). The case where the film thickness measuring instrument 25 provided in the peripheral exposure apparatus 33 is used will be described.
[0072]
When the dummy wafer DW is loaded into the resist solution coating / development processing system, the resist solution is supplied to the surface of the dummy wafer DW in the resist coating unit (COT) to form a resist film. Next, the dummy wafer DW is transferred into a hot plate unit (HP) and subjected to a pre-baking process in order to evaporate the solvent in the resist film. When the pre-baking process is completed, the film is then transferred into the peripheral exposure apparatus 33, and the film thickness of the resist film is measured at a plurality of locations on different concentric circles of the wafer W by the film thickness measuring device 25 in the peripheral exposure apparatus 33. . Next, the dummy wafer DW is transported into the developing unit (DEV), supplied with a developing solution, subjected to development processing, and then transported again into the peripheral exposure device 33, and film thickness measurement is performed before the development processing. The film thickness is measured on the same circumference as the broken part, preferably the same part.
[0073]
Thus, the film thickness measured before and after the development processing is transmitted to the CPU 100 as an electric signal, and the film thickness reduction is calculated at a plurality of locations on different concentric circles.
[0074]
Next, the CPU 100 calculates an expected line width (line width variation) based on the above-mentioned film thickness reduction amount and the correlation information between the film thickness reduction amount and the line width obtained in advance, and the expected line width is the line width variation. Evaluate whether it is within the acceptable range.
[0075]
If the expected line width is within the line width variation allowable range, the processing of the wafer W is continued without correcting each unit of the resist solution coating / development processing system.
[0076]
If the expected line width is not within the line width variation allowable range, the resist coating unit (COT), the hot plate unit (HP), the exposure apparatus 40 (EXP), the chilling hot plate unit based on the line width variation. (CHP), each processing temperature of the developing unit (DEV), processing atmosphere, and exposure amount of the exposure apparatus 40 (EXP) are controlled so that the line width variation falls within the line width variation allowable range. to correct.
[0077]
In this way, by providing the line width variation evaluation function in the resist solution coating / development processing system and processing the wafer W, the wafer surface uniformity (CD uniformity) of the pattern line width can be corrected quickly by a simple method. Therefore, a more uniform circuit pattern can be formed.
[0078]
In the above embodiment, the case where the substrate to be processed is a semiconductor wafer has been described. However, it goes without saying that the present invention can be applied to, for example, an LCD substrate in addition to the wafer.
[0079]
【The invention's effect】
As described above, according to the present invention, since it is configured as described above, the following effects can be obtained.
[0080]
1) According to the first and fourth aspects of the present invention, the film quality is evaluated based on the amount of film reduction of the substrate to be processed, and the film quality before exposure is excluded by excluding factors that affect line width variation in the exposure process and PEB process. Since the evaluation can be performed easily and accurately in a short time, it can be used for research, development, etc. for improving the line width uniformity of the circuit pattern.
[0081]
2) According to the inventions of claims 2 and 5, the line width can be predicted by the amount of film reduction without going through the exposure process or the PEB process. Since the state of the apparatus after the elapse of the period can be confirmed easily and in a short time and the line width variation can be corrected, the line width uniformity of the circuit pattern can be improved.
[0082]
3) According to the invention described in claims 3 and 6, since the film thickness measuring means is mounted in the apparatus, the line width is predicted from the amount of film reduction, and each step of the photolithography technique is controlled. The wafer in-plane uniformity (CD uniformity) can be quickly corrected by a simple method, and a more uniform circuit pattern can be formed.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing an example of a resist solution coating / development processing system according to the present invention.
FIG. 2 is a schematic front view of the resist solution coating / developing system.
FIG. 3 is a schematic rear view of the resist solution coating / developing system.
FIG. 4 is a graph showing the relationship between the measurement position on the substrate to be processed, the line width of the circuit pattern, and the amount of film reduction.
FIG. 5 is a schematic configuration diagram showing a film quality evaluation apparatus of the present invention.
FIG. 6 is a schematic configuration diagram showing a film thickness measuring means in the present invention.
FIG. 7 is a schematic explanatory view showing a film quality evaluation method of the present invention.
FIG. 8 is a graph showing the relationship between the pattern line width of a substrate to be processed and the amount of film reduction.
FIG. 9 is a graph illustrating a method for evaluating line width variation.
FIG. 10 is a schematic configuration diagram showing a processing method having a line width variation evaluation function.
FIG. 11 is a schematic configuration diagram showing a conventional film quality evaluation method.
[Explanation of symbols]
W Semiconductor wafer (substrate to be processed)
DW dummy wafer (target substrate for evaluation)
COT resist coating unit (resist film forming means)
DEV development unit (development processing means)
HP hot plate unit (heating means / first heating means)
CHP chilling hot plate unit (second heating means)
EXP exposure equipment (exposure means)
25 Film thickness measuring instrument (film thickness measuring means)
80 resist film
100 CPU (evaluation means)

Claims (6)

Supplying a resist solution to the surface of the substrate to be processed to form a resist film;
A first film thickness measurement step of measuring the film thickness of the resist film at a plurality of locations on different concentric circles after heating the substrate to be processed and evaporating the solvent in the resist film;
Next, a process of supplying a developer to the surface of the substrate to be processed and performing a development process;
A second film thickness measurement step for measuring the film thickness of the resist film for a plurality of locations on the different concentric circles of the substrate to be processed,
A step of calculating a film thickness for a plurality of locations on different concentric circles based on a difference between measurement values obtained by the first film thickness measurement and the second film thickness measurement, and evaluating a film quality based on the film thickness reduction When,
A film quality evaluation method characterized by comprising: Supplying a resist solution to the surface of the substrate to be processed to form a resist film;
A first film thickness measurement step of measuring the film thickness of the resist film at a plurality of locations on different concentric circles after heating the substrate to be processed and evaporating the solvent in the resist film;
Next, a process of supplying a developer to the surface of the substrate to be processed and performing a development process;
A second film thickness measurement step for measuring the film thickness of the resist film for a plurality of locations on the different concentric circles of the substrate to be processed,
A step of calculating the amount of film reduction for a plurality of locations on different concentric circles due to a difference in measurement values obtained by the first film thickness measurement and the second film thickness measurement;
A step of evaluating line width variation based on the above-mentioned film thickness reduction amount, correlation information between the previously obtained film thickness reduction amount and line width, and a line width variation allowable range;
A line width variation evaluation method characterized by comprising: A resist film forming step of forming a resist film by supplying a resist solution to the surface of the substrate to be processed; a first heating step of heating the substrate to be processed; and an exposure step of exposing a pattern to the substrate to be processed; In a processing method comprising: a second heating step of heating the substrate to be processed after exposure; and a developing step of supplying a developing solution to the surface of the substrate to be processed to perform a developing process.
Supplying a resist solution to the surface of the substrate to be processed for evaluation to form a resist film;
A first film thickness measurement step of measuring the film thickness of the resist film at a plurality of locations on different concentric circles after heating the substrate to be processed for evaluation and evaporating the solvent in the resist film;
Next, a step of supplying a developer to the surface of the substrate to be evaluated and performing a development process;
A second film thickness measurement step for measuring the film thickness of the resist film at a plurality of locations on the different concentric circles of the substrate to be processed for evaluation that has been developed;
A step of calculating the amount of film reduction for a plurality of locations on different concentric circles due to a difference in measurement values obtained by the first film thickness measurement and the second film thickness measurement;
A step of evaluating line width variation based on the above-mentioned film thickness reduction amount, correlation information between the previously obtained film thickness reduction amount and line width, and a line width variation allowable range;
Based on the evaluation of the line width variation, any one of the resist film forming step, the first heating step, the exposure step, the second heating step, the processing temperature in the development step, the processing atmosphere, and the exposure amount in the exposure step. A processing method having a line width variation evaluation function characterized by controlling the above and correcting the line width variation within a line width variation allowable range. A resist film forming means for forming a resist film by supplying a resist solution to the surface of the substrate to be processed;
Heating means for heating the substrate to be processed and evaporating the solvent in the resist film;
Development processing means for supplying a developer to the surface of the substrate to be processed and performing development processing;
Film thickness measuring means for measuring the film thickness of the resist film before development processing and the film thickness of the resist film after development processing for a plurality of locations on different concentric circles of the substrate to be processed,
An evaluation means for calculating a film thickness for a plurality of locations on different concentric circles based on a difference in measured values obtained by the film thickness measuring means, and evaluating a film quality based on the film thickness. Film quality evaluation device. A resist film forming means for forming a resist film by supplying a resist solution to the surface of the substrate to be processed;
Heating means for heating the substrate to be processed and evaporating the solvent in the resist film;
Development processing means for supplying a developer to the surface of the substrate to be processed and performing development processing;
Film thickness measuring means for measuring the film thickness of the resist film before development processing and the film thickness of the resist film after development processing for a plurality of locations on different concentric circles of the substrate to be processed,
Due to the difference in the measurement values obtained by the film thickness measuring means, the amount of film reduction is calculated for a plurality of locations on different concentric circles, and the film thickness reduction amount, the correlation information between the film thickness reduction amount and the line width obtained in advance, An evaluation means for evaluating the line width variation based on the line width variation allowable range;
A line width variation evaluation apparatus comprising: A resist film forming means for supplying a resist solution to the surface of the substrate to be treated; a first heating means for heating the substrate to be treated; an exposure means for exposing a pattern on the substrate to be treated; In a processing apparatus comprising: a second heating unit that heats a substrate; and a development processing unit that develops the substrate to be processed.
Film thickness measuring means for measuring the film thickness of the resist film before and after the development processing of the evaluation target substrate developed by the development processing means,
Due to the difference in the measurement values obtained by the film thickness measuring means, the amount of film reduction is calculated for a plurality of locations on different concentric circles, and the film thickness reduction amount, the correlation information between the film thickness reduction amount and the line width obtained in advance, An evaluation means for evaluating the line width variation based on the line width variation allowable range,
Based on the evaluation of the line width variation, any one of the resist film forming means, the first heating means, the exposure means, the second heating means, the processing temperature of the development processing means, the processing atmosphere, and the exposure amount of the exposure means A processing apparatus having a line width variation evaluation function, wherein one or more can be controlled.

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