JP5104192B2 - Heat treatment apparatus for resist coated substrate and heat treatment method thereof - Google Patents

Description

  The present invention relates to a heat treatment apparatus substrate for a resist-coated substrate and a heat treatment method therefor.

  In the manufacture of semiconductor devices or photomasks, etc., a manufacturing process in which heat treatment is performed on a semiconductor substrate, a photomask substrate (hereinafter referred to as a substrate) or the like, particularly when the resist applied to the substrate uses a chemically amplified resist. The post-printing exposure or post-drawing heat treatment, such as PEB (Post Exposure Baking), is very important because it greatly affects the resist sensitivity after the heat treatment, and thus the resist shape, for example, the resist line width. .

  In a photolithography process in manufacturing a semiconductor device, a photomask, or the like, heat treatment (pre-baking) for evaporating the solvent in the resist solution applied to the surface of the substrate, or the resist-coated substrate (hereinafter referred to as a substrate) After the exposure of the pattern, various heat treatments such as a resist solidification treatment after development of a heat treatment (PEB) for promoting a chemical reaction of a coating film on the substrate, for example, a resist film, are performed.

  Such heat treatment is performed in the PEB apparatus, and is performed by placing the substrate on a heating unit heated to a predetermined temperature. Conventionally, a thick plate-like integral type is used for the heating unit, and a heater or the like serving as a heat source is built in the heating unit. Moreover, the heat processing of a board | substrate is the process for predetermined time normally in the range of about 50 to 150 degreeC.

  In recent years, with the diversification of resist substrates and the like, the necessity of heating the substrate to a higher temperature, for example, about 150 ° C., has increased. Furthermore, it is important to heat the substrate to a more uniform temperature. Speaking of uniform heat treatment, if the conventional heating unit is used as it is, the heat from the heating unit is conducted non-uniformly to the substrate, so the substrate is not heated uniformly and the resist on the substrate itself is altered. I know you will. Such alteration of the substrate causes a decrease in device accuracy, which is not preferable because it causes a decrease in yield. In particular, in recent years, there has been a tendency for substrates to become larger due to demands for improving productivity, etc., and more uniform heating to the substrates is desired, and improvement of the heating apparatus, that is, the substrate heat treatment method is desired. .

  Here, an outline of a system configuration of a coating process and a development process equipped with a heat treatment apparatus, which is a part of a photolithography process in manufacturing a conventional semiconductor device or a photomask, will be described.

  FIG. 4 is a plan view showing a schematic diagram of an example of a configuration of a coating processing and developing processing system on which a PEB device 50 of a heat treatment apparatus, which is a part of a photolithography process in manufacturing a conventional photomask, is mounted. .

  The conventional coating processing and development processing system includes a cassette transfer device 11 that carries in and out of the coating development processing system from the outside in units of a cassette 10 that accommodates the substrate 1, and carries in and out the coating processing and development processing steps. The inter-device transfer apparatus 13 that transfers the substrate between the substrate transfer apparatus 12 that performs the single wafer processing and the exposure apparatus 40 provided adjacent to the substrate transfer apparatus is integrated. It has a connected configuration.

In the coating processing and development processing system, a resist coating processing device 20 that coats a resist solution on a substrate to form a resist film, and a development processing device 30 that develops the substrate after exposure are arranged.

  As shown in FIG. 4, in the resist coating apparatus 20, a cooling apparatus 21 for cooling the substrate and a pre-baking apparatus 22 for evaporating the solvent in the resist solution are arranged.

  In the development processing device 30, a post-baking device 32 that performs a heat treatment after the development processing and a cooling device 33 are disposed.

  In the vicinity of the exposure device 40, a cooling device 23 that naturally cools the placed substrate, a post-exposure baking device 50 (hereinafter referred to as a PEB device 50) as a heat treatment device, and a cooling device 43 are arranged.

  Next, the configuration of the PEB apparatus 50 will be described.

  FIG. 5 is a partial side sectional view for explaining a conventional PEB apparatus. As shown in FIG. 5, the PEB apparatus 50 includes a processing chamber 59, and includes a door body 58 that can be opened and closed on the front side and a heat treatment apparatus 57 that performs heat treatment on the lower side.

  An exhaust part 67 is provided at the top of the processing chamber. The atmosphere in the processing chamber is exhausted from the exhaust unit.

  On the other hand, the heat treatment apparatus 57 is provided with a heating unit 52 for placing and heating the substrate. The heating unit 52 is formed in a thin plate shape as a whole, and has a single plate shape.

  The heat treatment apparatus 57 includes a single heat source 56 and has a temperature control apparatus that can control the temperature. The temperature control device includes, for example, a heater serving as a heat source, a power source that supplies power, a control unit that controls the voltage of each power source, and a temperature sensor that detects the temperature of the heating unit 52.

  The effects of the PEB apparatus configured as described above and the process of the photolithography process performed in the coating and developing treatment system will be described. This will be described with reference to FIGS.

  In the photolithography process, one unprocessed substrate is first taken out, and the substrate is transferred to the cooling device 21 and cooled to a predetermined temperature (see FIG. 4).

  Thereafter, the resist film is transferred to the resist coating apparatus 20 to form a resist film. The substrate on which the resist film is formed is sequentially transferred to the pre-baking device 22 and the cooling device 23, and is subjected to predetermined processing in each device.

  Next, the substrate 1 is taken out and conveyed to the exposure apparatus 40. The substrate after the exposure processing is transferred to the PEB apparatus 50. In the PEB apparatus, the substrate that has been subjected to the heat treatment at a predetermined temperature is transferred to the cooling apparatus 43 and subjected to a predetermined process in each apparatus.

  Thereafter, it is conveyed to the development processing apparatus 30. The developed substrate is sequentially transported to the post-baking device 32 and the cooling device 33, and predetermined processing is performed in each device. Thereafter, the substrate 1 is returned to the cassette 10, and a series of photolithography steps is completed.

In the heat treatment of the PEB apparatus according to the prior art, the heat plate 56 is heated by one heat source (for example, a heater), and the surface of the heating unit 52 is heated by one heat source to be placed on the heating unit 52. The temperature in the surface of the mounted substrate is set to be uniform (see FIG. 5).

  However, for example, when a chemically amplified resist is used, if the temperature of the heat treatment in the PEB process varies, the resist size in the resist development process is affected.

  FIG. 7 is a side sectional view for explaining a conventional heat treatment method for PEB of a resist-coated substrate. FIG. 7A shows a case where the temperature in the heat treatment of PEB is uniform, and FIG. It is a case where it is uniform and is a sectional side view explaining after exposure and after development.

  FIG. 7A shows an example in which the substrate surface is uniformly heated at a temperature T ° C. when the temperature in the heat treatment of PEB is uniform. a1 is the resist 80 after the exposure processing with a line width of D μm. In a <b> 2, the exposed portion resist 80 a after the heat treatment of PEB is maintained including the resist sensitivity in the line width D′ μ. a3 is a resist after development, and the resist opening is formed with a line width D μm in both the peripheral part and the central part.

  FIG. 7B shows an example in which the temperature in the heat treatment of PEB is non-uniform, in which the center portion of the substrate is heat-treated at the temperature T ° C. and the peripheral portion of the substrate is heat-treated at the temperature T ′ ° C. b1 is the resist 80 after the exposure process with a line width of D μm. In the exposed portion resist 80a after the heat treatment of PEB, the resist sensitivity varies from a line width D μm to a line width d ′ μm. That is, the sensitivity does not increase at low temperatures, and the sensitivity increases at high temperatures. Reference numeral b2 denotes a developed resist, in which the peripheral resist opening is formed with a line width d ′ μm, and the central resist opening is formed with a line width D μm. In b2, the variation in temperature distribution causes a change in the dimension of the resist opening.

  However, even if the heat treatment after exposure or lithography in the photolithography process is performed uniformly, for example, with PEB, in the subsequent process, for example, in the manufacturing process of the etching process, pattern formation is performed on the central portion and the outer peripheral portion of the substrate. Etching rate differences due to the influence of density and the like, for example, variations in the substrate width of the line width occur. That is, even if the resist line width is uniform in the plane, the in-plane variation may occur in the etching line width due to the influence of the etching rate difference. Therefore, in this case, correction for fine adjustment of the resist line width is required.

  Therefore, in another prior art, for example, when a chemically amplified resist is used, correction for fine adjustment of the resist line width is performed by dividing the heat source of the hot plate into a plurality of heat sources in the PEB heat treatment apparatus, There has been proposed a method of finely adjusting the resist line width by finely adjusting the set temperature every time to adjust the temperature difference between the heat sources.

  When the heat source of the heat plate is divided into a plurality of parts and the set temperature is finely adjusted for each divided heat plate, it is necessary to provide a plurality of heat sources and their temperature control devices, and the temperature change at the boundary of each heat source becomes abrupt. Since the temperature difference between the adjacent heat sources changes abruptly, the heat treatment for finely adjusting the resist line width becomes rather difficult to make fine adjustment due to the large temperature difference.

  By dividing the heat source, the maintenance and management of the apparatus are complicated, and the temperature control is also complicated.

  6A and 6B illustrate a heat treatment method for such a resist-coated substrate. FIG. 6A is a side cross-sectional view during heating, and FIG. 6B is a temperature distribution graph after heating.

  FIG. 6 (a) shows the heating, with the central heat sources 56b and 56c set to 110 ° C. and the peripheral heat sources 56a and 56d set to 100 ° C. for heating. In the heating part 52, the surface temperature of the central part is T ° C., for example. In this state, the substrate 1 is placed on the heating unit 52 and subjected to heating for a predetermined time, for example, heat treatment at the central part 100 ° C., peripheral part 90 ° C., 10 minutes, and PEB.

  FIG. 6B shows the temperature distribution after heating, and is a graph showing the results of actual measurement of the surface temperature of the substrate 1. In the graph, the horizontal axis is from one end of the substrate to the other end, and the center is the central portion of the substrate. The vertical axis represents the actually measured temperature, and is shown in the temperature range from the maximum temperature, T ° C. to the minimum temperature, T ′. The central part of the substrate is in the vicinity of the temperature T ° C., and the peripheral part has the lowest temperature T ′. Further, as can be seen from the graph, the temperature change from T ° C. to T ′ ° C. has a rapid temperature drop in the peripheral portion, and the rapid change becomes a problem.

The known literature is described below.
JP 2002-353110 A

  An object of the present invention is a heat treatment method for a resist-coated substrate in which maintenance and management of the apparatus are not complicated and temperature control is simple, and the temperature distribution of a hot plate heated from a heat source is accompanied by a rapid temperature change. First, it is to provide a heat treatment method for a resist-coated substrate and a heat treatment apparatus therefor for arbitrarily changing the in-plane temperature distribution of PEB.

A heat treatment apparatus for a resist-coated substrate according to the present invention comprises:
A heating unit that heats the resist-coated substrate and is heated by a single heat source is divided into a plurality of central portions and outer end portions of the portions,
In the upper position of the plurality of heating units, a single plate-like heat conductive upper plate is provided in which the material is selected from stainless steel, aluminum, an alloy containing at least one of them, or ceramic,
Each of the divided heating units is provided with a vertical lifting mechanism with respect to the upper plate on which a resist coating substrate is placed,
By finely adjusting the height position of each heating part, the temperature distribution set according to the change in the etching rate in the resist-coated substrate surface is gently adjusted, and the dimensions of the resist opening are adjusted to adjust the resist-coated substrate. It has a function of correcting the resist sensitivity in the plane.

A heat treatment method using a heat treatment apparatus for a resist-coated substrate according to the present invention is as follows:
The temperature change in the surface of the upper plate is moved up and down at the center or end of the divided heating unit, and the gap between the heating unit and the upper plate is adjusted, thereby adjusting the etching rate in the substrate surface. The resist sensitivity after the exposure processing is corrected by gently adjusting the temperature distribution set according to the change of the above and adjusting the size of the resist opening.

  If the heat treatment method for a resist-coated substrate and the heat treatment apparatus therefor according to the present invention are used, the temperature distribution in the substrate surface can be adjusted to an optimum state because it is a heat treatment method using a heating unit having a plurality of lifting mechanisms. In addition, since the temperature change in the substrate surface becomes gradual, the resist width can be optimized by correcting the resist sensitivity in advance, and by controlling the dimensional variation of the line width after dry etching. In-plane variation in line width can be reduced.

  If the heat treatment method for a resist-coated substrate and the heat treatment apparatus therefor according to the present invention are used, a heating part having a plurality of elevating mechanisms, and a heat treatment method having a structure equipped with an upper plate above the heating part, the upper plate and the heating part Can be easily changed to a large temperature distribution, and the temperature change in the substrate surface becomes gradual, so that the resist width can be corrected by correcting the resist sensitivity in advance. Can be made the optimum width, and the line width variation in the plane can be reduced by controlling the line width variation after dry etching.

  If the heat treatment method for a resist-coated substrate and the heat treatment apparatus therefor according to the present invention are used, a heating part having a plurality of elevating mechanisms, and a heat treatment method having a structure equipped with an upper plate above the heating part, the upper plate and the heating part Can be easily changed to a large number of temperature distributions by changing the distance to the elevating mechanism, so that the temperature of the heat source of the heating unit can be kept constant, making unitization easy, and its operation also This simplifies the operation efficiency of the apparatus.

  A heat treatment apparatus and a heat treatment method for a resist-coated substrate according to the present invention will be described below based on an embodiment.

  FIG. 1 is a side sectional view of an embodiment of a heat treatment apparatus used for heat treatment of a resist-coated substrate of the present invention. (A) The heat treatment apparatus is provided only on the lower side, and (b) is a heat treatment apparatus on both upper and lower sides. I have it.

  FIG. 1A to FIG. 1B are heat treatment apparatuses for a resist-coated substrate according to the present invention, which are heat treatment apparatuses for heating a resist-coated substrate. The heat treatment apparatus for the resist coated substrate has a heating unit 2 for heating the resist coated substrate, and the heating unit 2 heated by one heat source 6 includes, for example, a plurality of central portions 2b and 2c and an outer side of the portion. It is the structure divided | segmented into the edge parts 2a and 2d, and it is cut | disconnected by each heating part 2a, 2b, 2c, 2d.

  The plurality of heating units 2a to 2d are provided with a single plate-like heat conductive upper plate at an upper position thereof, and heat-treat the resist substrate placed through the upper plate. It is characterized by.

Each of the divided heating units 2a, 2b, 2c, and 2d includes an elevating mechanism 4 that moves the heating unit up and down, and changes the interval between the upper plate and the heating unit. It is possible to finely adjust the temperature of the plate.

  The upper plate 3 is made of stainless steel, aluminum, an alloy containing at least one of them, or ceramic.

  The heating unit is provided with a cooling pipe 5 through which a cooling gas or liquid passes.

  The gas is nitrogen, helium, or a mixture thereof.

  FIG. 1B shows a heat treatment apparatus for a resist-coated substrate according to the present invention, in which a heating unit 2 and an elevating mechanism 4 are disposed above a resist substrate 1 placed on an upper plate 3 so as to face the substrate. It is the heat processing apparatus of the resist coating substrate of this invention which attaches and heat-processes the resist substrate 1 from the heating part 2 of the downward direction and the upper direction.

  FIG. 2 is a conceptual diagram for explaining an embodiment of a heat treatment method for a resist-coated substrate according to the present invention, (a) is a side sectional view at the time of heating, and (b) is a top view of the heating portion. (C) is a graph of measured values of the temperature of the upper plate during heating.

  A resist-coated substrate heat treatment method using the resist-coated substrate heat treatment apparatus of the present invention shown in FIGS. 2A to 2C will be described. In FIG. 2A, the resist-coated substrate 1 is placed on a single plate-like upper plate 3 having thermal conductivity. Next, the heating units 2a, 2d, 2b, and 2c heated by a single heat source 6 are divided into heating units 2b and 2c at the central portion and heating units 2a and 2d at the outer end portions of the portions. Yes. The heating parts 2b and 2c at the central part are raised by the lifting mechanism, and the heating parts 2a and 2d at the end parts are lowered by the lifting mechanism. The central portion adjacent to the upper plate is stabilized at a higher temperature, and the end portion away from the upper plate is stabilized at a lower temperature, and the temperature distribution in the surface of the upper plate is changed to the optimum temperature. In other words, this is a method for heat-treating a resist-coated substrate, which has a gradual temperature change from the vicinity of the center to the end portion and heats the resist-coated substrate while reducing the rapid temperature change of the upper plate.

  In FIG.2 (b), the heating parts 2b and 2c were set to 110 degreeC, and the heating parts 2a and 2d of the edge part were also set to 110 degreeC. Next, when the temperature change in the surface of the upper plate is set to a temperature difference between the center portion and the end portion, for example, 1.5 ° C., the heating portion 2a, 2d at the end portion is lowered while the temperature change is 1.5 ° C. The height position of each heating unit was finely adjusted while widening the gap between the upper plate and each heating unit to a position where the temperature decreased.

  In the graph of FIG. 2C, the upper limit temperature 8 is the upper plate temperature of the heating parts 2b and 2c, and the lower limit temperature 9 is the heating parts 2a and 2d at the end portions. The vertical axis of the graph is temperature, and the horizontal axis of the graph is the in-plane position of the upper plate. When the temperature change in the surface of the upper plate is set to a temperature difference 7 between the central portion and the end portion, for example, ΔT, the upper limit temperature is expressed by adjusting the set temperature of the heating unit 2, and the adjusting temperature is the lifting mechanism. 4. While lowering the heating portions 2a and 2d at the end portion by 4, widen the gap between the upper plate and each heating portion 2a and 2d to a position where the temperature of ΔT ° C. decreases, the height position of each heating portion is adjusted. Tweaked. In the graph of FIG. 2 (c), the center of the upper plate becomes the upper limit temperature, and the temperature gradually decreases as it moves away from both ends of the substrate, and both ends of the upper plate become the lower limit temperature due to a gradual change in temperature.

  In the heat treatment method for a resist-coated substrate according to the present invention, the temperature distribution in the substrate surface can be changed to an optimum state because of the heat treatment method using a plurality of heating units having lifting mechanisms. Since the temperature change in the substrate surface becomes gentle, this is an optimum method for the heat treatment of PEB for correcting the resist sensitivity in advance.

  In the heat treatment method for a resist-coated substrate of the present invention, the resist width can be optimized by correcting the resist sensitivity after the exposure process, and the dimensional variation of the line width after dry etching is controlled, and the in-plane dimension Variations can be reduced.

  For example, the edge width of the substrate can be changed by changing the heating temperature at the edge and finely adjusting the temperature lower than the temperature at the center to heat the PEB. The etching rate is corrected by changing, that is, by forming the resist width thick. That is, at the end portion, the etching opening is thicker by the higher etching rate, so the resist opening is narrowed in advance by that amount. The method of adjusting the size of the resist opening is the heat treatment method for the resist-coated substrate of the present invention. The size of the resist opening is adjusted by heating the PEB to correct the etching rate change in the substrate surface. The temperature distribution inside is fine-tuned.

  FIG. 3 is a side sectional view for explaining the heat treatment method of the resist coated substrate of the present invention. 3A shows the substrate after the exposure processing, FIG. 3B shows the PEB processing, FIG. 3C shows the substrate after development, and FIG. 3D shows the substrate after etching.

  In FIG. 3A, a chemically amplified resist 80 is formed on the light shielding film 81, and an exposed resist portion 80a subjected to exposure processing is formed on the resist. The exposure resist portion 80a has the same size, for example, D. Next, in (b), the heat treatment of the PEB of the present invention is performed. At the end, the distance between the heating unit 2 and the upper plate 3 is wide, the center is close, and the heating temperature is finely adjusted. In this heat treatment, the sensitivity is slightly higher at the center and the edges are slightly lower, and the resist dimensions in the development process change. Next, (c) is a substrate after development processing, and the dimension of the resist opening is slightly smaller at the center with D and at the end with D '. Next, in (d), after the light shielding film is etched, the edge has an etching width that is increased by the higher etching rate, and the dimension of the light shielding film opening is D. The fine adjustment of the heating temperature in the plane is to adjust the height of the heating section, and the temperature adjustment method is easy and simple.

BRIEF DESCRIPTION OF THE DRAWINGS It is a sectional side view of one Example of the heat processing apparatus used for the heat processing of the resist coating board | substrate of this invention, (a) It is a heat processing apparatus only of lower side, (b) is the heat processing apparatus of the upper and lower sides. It is a conceptual diagram explaining the heat processing method of the resist coating substrate of this invention, (a) is a sectional side view at the time of a heating, (b) is a top view of the heating part, (c), It is a graph of the measured value of the temperature of the upper board at the time of a heating. (A)-(d) is a sectional side view explaining the heat processing method of the resist coating substrate of this invention. It is a top view which shows the schematic of the structure of the system of the application | coating process with which the heat processing apparatus is mounted, and the image development process which are an example of the photolithography process in manufacture of the conventional photomask. It is a fragmentary sectional side view explaining the conventional PEB apparatus. It is a sectional side view explaining the conventional heat processing method of a resist coating substrate, (a) is at the time of a heating, (b) is after a heating. It is a sectional side view explaining the conventional heat processing method of a resist coating substrate, (a) is a case where the temperature of the heat processing after an exposure process is uniform, (b) is a case where temperature is non-uniform | heterogenous.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Resist substrate 2 ... Heating part 3 ... Upper plate 4 ... Elevating mechanism 5 ... Cooling pipe 6 ... Heat source 7 ... Temperature difference 8 ... Upper limit temperature 9 ... Lower limit temperature 10 ... Cassette 11 ... Cassette transfer device 12 ... Substrate transfer Apparatus 13 ... Transfer apparatus 20 ... Resist coating apparatus 21 ... Cooling apparatus 22 ... Prebaking 23 ... Cooling apparatus 30 ... Development processing apparatus 32 ... Post baking apparatus 33 ... Cooling apparatus 40 ... Exposure apparatus 43 ... Cooling apparatus 50 ... PEB device 52 ... heating unit 56 ... heat source 57 ... heat treatment device 58 ... door body 67 ... exhaust unit 80 ... (chemically amplified) resist 80a ... exposed portion resist 81 ... light shielding film 82 ... resist opening

Claims (5)

A heat treatment apparatus for a resist-coated substrate,
A heating unit that heats the resist-coated substrate and is heated by a single heat source is divided into a plurality of central portions and outer end portions of the portions ,
In the upper position of the plurality of heating units, a single plate-like heat conductive upper plate is provided in which the material is selected from stainless steel, aluminum, an alloy containing at least one of them, or ceramic,
Each of the divided heating units is provided with a vertical lifting mechanism with respect to the upper plate on which a resist coating substrate is placed,
By finely adjusting the height position of each heating part, the temperature distribution set according to the change in the etching rate in the resist-coated substrate surface is gently adjusted, and the dimensions of the resist opening are adjusted to adjust the resist-coated substrate. A resist-coated substrate heat treatment apparatus characterized by having a function of correcting in-plane resist sensitivity . A heating unit and an elevating mechanism are provided above the resist-coated substrate placed on the upper plate so as to face the substrate, and the resist-coated substrate is subjected to heat treatment from the lower and upper heating units. The heat treatment apparatus for a resist-coated substrate according to claim 1. The heating unit, a heat treatment apparatus of the resist coating a substrate according to claim 1 or 2, characterized in that the that internal cooling gas or a cooling pipe through which a liquid is provided. The gas is nitrogen, helium, or resist heat treatment apparatus of the coating substrate according to claim 1 or 2, characterized in that the a mixture. A heat treatment method using the heat treatment apparatus of the resist coating a substrate according to any one of claims 1 to 4,
The temperature change in the surface of the upper plate is moved up and down at the center or end of the divided heating unit, and the gap between the heating unit and the upper plate is adjusted, thereby adjusting the etching rate in the substrate surface. A method for heat-treating a resist-coated substrate, wherein the resist sensitivity after the exposure processing is corrected by gently adjusting the temperature distribution set according to the change in the size and adjusting the size of the resist opening .