JP2013076857A - Photomask manufacturing method and charged particle beam drawing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photomask manufacturing method which implements a photomask of high precision.SOLUTION: In the photomask manufacturing method, a photomask blank having a chemically amplified resist applied thereto is carried into a charged particle beam drawing device, and the chemically amplified resist is irradiated with a charged particle beam to successively draw patterns in a plurality of regions on the photomask blank. Then the photomask blank is carried out from the charged particle beam drawing device, and an elapsed time from the start of drawing to the start of post-exposure baking is calculated for each of the plurality of regions, and a process condition of post-exposure baking for each of the plurality of regions is determined on the basis of the elapsed time calculated for each of the plurality of regions. A post-exposure baking device capable of changing a process condition for each of a plurality of sections is used, and post-exposure baking is performed under the process condition determined for each of the plurality of regions to develop the chemically amplified resist.

Description

  The present invention relates to a photomask manufacturing method and a charged particle beam writing method.

  Lithography technology is used to form a desired circuit pattern on a semiconductor device. In the lithography technique, a pattern is transferred using an original image pattern called a photomask (hereinafter also simply referred to as a mask). In order to manufacture a highly accurate mask, an electron beam (electron beam) drawing technique having excellent resolution is used.

  In electron beam writing, a chemically amplified resist that achieves high resolution is used. The chemically amplified resist is characterized in that post-exposure baking (PEB) is performed after the electron beam irradiation, whereby the acid generated during the irradiation diffuses and reacts to complete the pattern formation.

  Some chemically amplified resists have characteristics that the acid diffuses in the resist during the elapsed time from electron beam irradiation to post-exposure bake, and the pattern of the resist that is formed changes due to the variation in this elapsed time. There is. When such a resist is used, it is important to manage the elapsed time from electron beam irradiation to post-exposure baking.

  In electron beam drawing, it is necessary to maintain beam accuracy in order to perform high-precision drawing. For this purpose, for example, during the drawing on the sample, so-called drift correction is performed in which the drawing is interrupted and the fluctuation of the electron beam irradiation position is corrected. When drawing is interrupted for such drift correction, the elapsed time from drawing by electron beam irradiation to post-exposure baking is the same for the area drawn before the interruption and the area drawn after the interruption. Nevertheless, there is a risk that it will be very different.

JP-A-8-111370

  The present invention has been made in consideration of the above circumstances, and the object of the present invention is to manage the time from irradiation of a charged particle beam to post-exposure baking for each of a plurality of regions on the same sample. An object of the present invention is to provide a photomask manufacturing method and a charged particle beam drawing apparatus that realizes an accurate photomask.

  According to another aspect of the present invention, there is provided a photomask manufacturing method comprising: a charged particle beam lithography apparatus that carries a photomask blank coated with a chemically amplified resist; and irradiating the chemically amplified resist with a charged particle beam. A drawing process for sequentially drawing a pattern in a plurality of regions on the photomask blanks, a carrying-out step for carrying out the photomask blanks from the charged particle beam drawing apparatus, and the carrying-out from the drawing start for each of the plurality of regions. Based on the calculation process for calculating the elapsed time from the time until the process is completed and the time from the completion of the unloading process to the start time of the post-exposure baking, and the elapsed time calculated for each of the plurality of areas, A process condition determining step for determining a process condition of post-exposure baking for each area, and a process A post-exposure bake process for performing post-exposure bake on the photomask blank under the process conditions determined for each of the plurality of regions, using a post-exposure bake device capable of changing the exposure condition for each of a plurality of sections; and the photomask blanks And a developing step for developing the chemically amplified resist.

  In the photomask manufacturing method according to the above aspect, a drawing order determining step of determining a drawing order of the plurality of regions based on a division of the changeable region of the process condition in the post-exposure baking apparatus before the drawing step. It is desirable to further provide.

  In the photomask manufacturing method of the above aspect, based on the elapsed time calculated for each of the plurality of regions and the elapsed time from the completion of the unloading step to the start time of the post-exposure baking step, It is desirable to determine process conditions.

  A charged particle beam drawing apparatus according to an aspect of the present invention includes a carry-in unit that carries a photomask blank into the charged particle drawing apparatus, and an input unit that inputs drawing data defining a pattern to be drawn on the photomask blank. A shot data generation unit that converts the drawing data into shot data configured with charged particle beam shots as a unit, and sequentially irradiates a plurality of regions on the photomask blank using the shot data A drawing unit that performs drawing, a carry-out unit that carries out the photomask blank out of the charged particle beam drawing apparatus, and the photomask blanks out of the charged particle drawing apparatus from the start of drawing for each of the plurality of regions. It has a monitor part which monitors time until it is carried out.

  The charged particle beam drawing apparatus according to the aspect described above further includes a drawing order determining unit that determines a drawing order of the plurality of regions based on the division of the changeable region of the process condition when performing post-exposure baking on the photomask blank. It is desirable.

  According to the present invention, a method for manufacturing a photomask that realizes a highly accurate photomask and a charged particle beam by managing the time from irradiation of a charged particle beam to post-exposure baking for each of a plurality of regions on the same sample. A drawing apparatus can be provided.

It is process drawing of the photomask manufacturing method of 1st Embodiment. It is a schematic block diagram of the charged particle beam drawing apparatus of 1st Embodiment. It is a schematic diagram of an example of the pattern drawn on the mask blank of 1st Embodiment. It is explanatory drawing of the post-exposure baking apparatus of 1st Embodiment. It is a figure which shows an example of the process condition determination of 1st Embodiment. It is process drawing of the photomask manufacturing method of 2nd Embodiment. It is explanatory drawing of an example of the drawing order of the manufacturing method of the photomask of 2nd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to the electron beam, and may be a beam using charged particles such as an ion beam.

  In the present specification, the drawing data is basic data of a pattern drawn on a sample. The drawing data is data obtained by converting the format of design data generated by a designer using CAD or the like so that arithmetic processing can be performed in the drawing apparatus. A drawing pattern such as a figure is defined by coordinates such as a vertex of the figure, for example.

  Further, in this specification, a shot means a region where charged particles are irradiated by a single irradiation of a charged particle beam.

  Further, in this specification, shot data means data having shot information and having a final data format for drawing with a charged particle beam.

(First embodiment)
The photomask manufacturing method of the present embodiment includes a carrying-in process of carrying a photomask blank coated with a chemically amplified resist into a charged particle beam lithography apparatus, and a photon irradiation by irradiating the chemically amplified resist with a charged particle beam. A drawing process for sequentially drawing patterns in a plurality of areas on the mask blank, a carrying-out process for carrying out the photomask blank from the charged particle beam drawing apparatus, and a time from the start of drawing to the completion of the carrying-out process for each of the plurality of areas Multiple areas using a calculation process that calculates the elapsed time from the time from the completion of the unloading process to the start time of post-exposure bake, and a post-exposure bake device that can change process conditions in multiple sections on photomass blanks Based on the elapsed time calculated for each, determine the process conditions for each of the multiple sections, O comprising a post exposure bake step for bets mask blank to post-exposure baking, and developing step of developing the chemically amplified resist on a photomask blank, a.

  In the photomask manufacturing method of this embodiment, the elapsed time from drawing by electron beam irradiation to the end of carrying out the sample is calculated for each region on the sample. By reflecting this elapsed time on the post-exposure baking process conditions, each pattern on the sample is post-exposure baked under appropriate conditions. Therefore, each pattern is formed in a desired shape and size, and a highly accurate photomask is realized.

  FIG. 2 is a schematic configuration diagram of an electron beam lithography apparatus that executes the photomask manufacturing method of the present embodiment. The electron beam drawing apparatus 100 is an example of a charged particle beam drawing apparatus. The electron beam drawing apparatus 100 includes a drawing unit 102 and a control unit 104 that controls the drawing operation of the drawing unit 102. The electron beam drawing apparatus 100 draws a predetermined pattern on the sample 110.

  A stage 112 on which the sample 110 is placed is accommodated in the sample chamber 108 of the drawing unit 102. The stage 112 is driven by the control unit 104 in the X direction (left and right direction in the drawing), Y direction (front and back direction in the drawing), and Z direction (up and down direction in the drawing). The sample 110 is, for example, photomask blanks (hereinafter also simply referred to as mask blanks) for manufacturing a photomask for transferring a pattern onto a wafer on which a semiconductor device is formed.

  In the mask blank, for example, chromium serving as a light shielding film is coated on quartz glass. When placed on the stage 112 of the electron beam drawing apparatus, a chemically amplified resist is applied.

  Adjacent to the sample chamber 108, a carry-in section 106 for carrying the mask blanks 110 from outside the apparatus into the drawing apparatus is provided. The mask blank is provided with a function of transporting the mask blank to the sample chamber 108 by the carry-in unit 106. Further, an unloading unit 107 for unloading the mask blanks from the drawing apparatus to the outside of the drawing apparatus is provided adjacent to the sample chamber 108.

  An electron beam optical system 114 is installed above the sample chamber 108. The electron beam optical system 114 performs drawing with an electron beam on the sample. The electron beam optical system 114 includes an electron gun 116, various lenses 118, 120, 122, 124, 126, a blanking deflector 128, a beam size variable deflector 130, a beam scanning sub deflector 132, and a beam scanning. The main deflector 134, and a first aperture 136 and a second aperture 138 for beam shaping for drawing with a variable shaped beam.

  The control unit 104 has a function of controlling the electron beam optical system 114. An input unit 150, a shot data generation unit 152, a control circuit 154, and a monitor unit 156 are provided.

  The input unit 150 has a function of inputting drawing data defining a pattern to be drawn on the photomask blank. For example, a reading device for a memory element in which drawing data is stored.

  The shot data generation unit 152 has a function of converting drawing data into shot data configured with a shot of a charged particle beam as a unit.

  The control circuit 154 controls electron beam drawing in the drawing unit 102 based on the shot data.

  The monitor unit 156 has a function of monitoring the time from drawing until the mask blank is carried out of the electron beam drawing apparatus 100 for each of a plurality of areas drawn on the mask blank.

  The processing in the shot data generation unit 152, the control circuit 154, and the monitoring unit 156 is performed using, for example, an arithmetic processing device such as a CPU or hardware such as an electric circuit. Alternatively, a combination of software and hardware may be used.

  FIG. 1 is a process diagram of the photomask manufacturing method of the present embodiment. A carrying-in process (S110), a drawing process (S120), a carrying-out process (S130), a calculating process (S140), a process condition determining process (S150), a post-exposure baking process (S160), and a developing process (S170) are provided.

  In the photomask manufacturing method of the present embodiment, first, in the carry-in process (S110), the mask blanks 110 coated with the chemically amplified resist is carried into the electron beam lithography apparatus 100 from the carry-in unit 106. The loaded mask blanks 110 are transported into the sample chamber 108 by the loading unit 106 and placed on the stage 112. This chemically amplified resist is a chemically amplified resist having the property that the pattern shape changes depending on the elapsed time from the electron beam irradiation to post-exposure baking.

  In addition, drawing data, which is basic data of a pattern to be drawn on the mask blanks 110, is input and stored in the electron beam drawing apparatus 100 in advance. The shot data generation unit 152 converts the drawing data into shot data configured with an electron beam shot as a unit.

  Next, in the drawing step (S120), the drawing unit 102 irradiates the chemically amplified resist with an electron beam to sequentially draw patterns in a plurality of regions on the mask blank 110.

  FIG. 3 is a schematic diagram of an example of a pattern drawn on the mask blank of the present embodiment. As shown in FIG. 3, for example, a plurality of regions A to F are drawn in a predetermined order on the mask blank.

  Then, the mask blanks 110 for which drawing has been completed are carried out of the electron beam drawing apparatus 100 by the carry-out unit 107 in the carry-out step (S130).

  In the calculation step (S140), the mask blanks are carried out of the electron beam drawing apparatus 100 from the start of drawing for each of a plurality of areas drawn on the mask blanks by the monitor unit 156, for example, for each of the areas A to F in FIG. Calculate the time to complete. In the calculation step (S140), the elapsed time from the start of drawing to post-exposure bake is calculated by adding the time from the completion of the carry-out step to the start time of post-exposure bake to the time from the start of drawing to the carry-out. As the time from the completion of the unloading process to the start time of post-exposure baking, an estimated time may be used, or an actually measured time may be used.

  Note that the processing of the calculation step (S140) may all be performed by the monitor unit 156, or may be realized in combination with a processing device outside the electron beam drawing apparatus 100.

  Next, in the process condition determining step (S150), the optimum post-exposure bake process conditions for each region are determined based on the elapsed time from the drawing start to the post-exposure bake calculated in the calculation step (S140). The parameter of this process condition is, for example, the post exposure bake time or temperature.

  For example, for a region with a long elapsed time, a short-time or low-temperature process condition is selected and determined. Further, for example, for a region having a short elapsed time, a long or high temperature process condition is selected and determined.

  This process condition determination step (S150) is performed by an arithmetic processing device such as a computer outside the electron beam drawing apparatus 100, for example. For example, it is performed by an arithmetic processing unit in the electron beam drawing apparatus 100 or an arithmetic processing unit in the post-exposure baking apparatus.

  Next, in the post-exposure baking step (S160), post-exposure baking is performed on the mask blanks under the process conditions determined for each of the plurality of regions. For example, process conditions determined for each of a plurality of areas are stored as a recipe in a post-exposure baking apparatus, and post-exposure baking is performed using this recipe. At this time, a post-exposure baking apparatus that can change the process conditions for each of a plurality of sections is used.

  Next, in the developing step (S170), the chemically amplified resist on the mask blank is developed. For development, a known developing device and a known developer are used.

  FIG. 4 is an explanatory diagram of the post-exposure baking apparatus according to the present embodiment. FIG. 4 is a schematic top view of a hot plate on which the mask blanks of the post-exposure baking apparatus are placed. As shown in FIG. 4, the post-exposure bake apparatus according to the present embodiment is designed so that process condition parameters, for example, process time or process temperature can be changed for every 16 sections a1 to d4 on the hot plate. Yes.

  FIG. 5 is a diagram illustrating an example of process condition determination according to the present embodiment. FIG. 5A is an explanatory diagram showing an arrangement and a drawing order of a plurality of areas drawn on the mask blank. FIG. 5B is an explanatory diagram of setting process conditions for each post-exposure bake area.

For example, each of the areas A to F is drawn in the drawing order of A → B → D → C → E → F.
In this case, for example, when the drawing of the region C is completed, it is determined that the drift of the electron beam has occurred, and the drift correction process is performed before the drawing of the region E. If it does so, the waiting time of drawing will arise between the drawing of the area | region C and the area | region E, As a result, a difference will arise for every area | region in the elapsed time from drawing to post-exposure baking.

  That is, the elapsed time of the areas A, B, C, and D is long, and the elapsed time of the areas E and F is short. For this reason, when post-exposure baking is performed under the same process conditions, there is a possibility that a difference in pattern shape occurs between regions.

  Therefore, in the photomask manufacturing method of the present embodiment, as shown in FIG. 5B, the sections a1 to a4 and b1 to b2 on the hot plate corresponding to the areas A, B, C, and D, and the areas The parameters of the post-exposure baking process conditions are changed in the sections b3 to b4, c1 to c4, and d1 to d4 on the hot plate corresponding to E and F.

  For example, in the sections a1 to a4 and b1 to b2, the post-exposure baking temperature is lowered or the post-exposure baking time is shortened. On the other hand, in the sections b3 to b4, c1 to c4, and d1 to d4, the temperature of post-exposure baking is increased or the time of post-exposure baking is increased. Thus, by changing the process condition for each region, it is possible to suppress a difference in pattern shape between the regions.

  According to the photomask manufacturing method of the present embodiment, even if there is a difference in the elapsed time from drawing to post-exposure baking for a plurality of regions drawn on the photomask blanks, there is a difference in pattern shape between the regions. Can be prevented from occurring. In particular, the present embodiment is effective when drawing interruption that cannot be specified before drawing starts occurs, such as drift correction.

  Moreover, according to the electron beam lithography apparatus 100 of the present embodiment, the photomask manufacturing method of the present embodiment can be easily realized.

(Second Embodiment)
In the photomask manufacturing method according to the present embodiment, the drawing order determining unit determines the drawing order of a plurality of areas based on the division of the changeable area of the process conditions in the post-exposure baking apparatus before the drawing process. It is the same as that of 1st Embodiment except providing the order determination process further. Therefore, the description overlapping with that of the first embodiment is omitted.

  FIG. 6 is a process diagram of the photomask manufacturing method of the present embodiment. Loading step (S110), drawing order determining step (S112), drawing step (S120), unloading step (S130), calculating step (S140), process condition determining step (S150), post-exposure baking step (S160), developing step (S170).

  FIG. 7 is an explanatory diagram of an example of the drawing order of the photomask manufacturing method of the present embodiment. For example, it is assumed that the hot plate of the post-exposure baking apparatus is divided into partitions as shown in FIG.

  In this case, for example, when the areas A to F are drawn in the order shown in FIG. 5A, the area D is drawn between the areas B and C arranged at positions corresponding to the same section. For this reason, the probability that a drawing interruption that cannot be specified before the start of drawing occurs between the region B and the region C is higher than when the region B and the region C are continuously drawn. If drawing interruption that cannot be specified before the drawing start occurs between the region B and the region C, it becomes difficult to cope with the process conditions in the subsequent post-exposure baking process.

  In the present embodiment, in the drawing order determining step (S112), the drawing order of each area is determined in advance by taking into account the division of the process condition changeable area in the post-exposure baking apparatus. For example, as shown in FIG. 7, the areas A to F are drawn in the drawing order of A → B → C → D → E → F.

  Thus, by continuously drawing the region B and the region C arranged on the same partition division a4, the elapsed time difference between the region B and the region C can be suppressed. Therefore, the possibility that the process conditions in the subsequent post-exposure baking process can be dealt with is improved.

  Therefore, according to the photomask manufacturing method of the present embodiment, even if there is a difference in the elapsed time from drawing to post-exposure baking for a plurality of regions drawn on the photomask blanks, the pattern shape between the regions It is even easier to suppress the difference between the two.

  It is desirable that the electron beam drawing apparatus 100 shown in FIG. 1 further includes a drawing order determination unit (not shown). The drawing order determination unit has a function of determining the drawing order of a plurality of areas based on the division of the process condition changeable area in the post-exposure baking apparatus.

  The processing in the drawing order determination unit is performed using, for example, an arithmetic processing device such as a CPU or hardware such as an electric circuit. Alternatively, a combination of software and hardware may be used.

  By further including a drawing order determination unit, the photomask manufacturing method of this embodiment can be easily realized.

  The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

  In addition, although descriptions are omitted for parts and the like that are not directly required for the description of the present invention, such as a device configuration and a control method, a required device configuration and a control method can be appropriately selected and used. In addition, all photomask manufacturing methods or charged particle beam writing methods that include elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Electron beam drawing apparatus 102 Drawing part 104 Control part 106 Carry-in part 107 Carry-out part 110 Mask blanks (sample)
112 Sample chamber 150 Input unit 152 Shot data generation unit 154 Control circuit 156 Monitor unit

Claims (5)

A carrying-in process for carrying a photomask blank coated with a chemically amplified resist into a charged particle beam drawing apparatus;
A drawing step of sequentially drawing a pattern in a plurality of regions on the photomask blanks by irradiating the chemically amplified resist with a charged particle beam;
An unloading step of unloading the photomask blank from the charged particle beam drawing apparatus;
For each of the plurality of regions, a calculation step of calculating an elapsed time from a time from the start of drawing to the completion of the unloading step and a time from the completion of the unloading step to the start time of post-exposure baking,
Based on the elapsed time calculated for each of the plurality of regions, a process condition determining step for determining a process condition for post-exposure baking for each of the plurality of regions;
A post-exposure bake step for performing post-exposure bake on the photomask blanks under the process conditions determined for each of the plurality of regions, using a post-exposure bake device capable of changing process conditions for each of a plurality of sections;
A development step of developing the chemically amplified resist on the photomask blank;
A method for producing a photomask, comprising:   The drawing order determining step of determining a drawing order of the plurality of regions based on a division of the changeable region of the process condition in the post-exposure baking apparatus before the drawing step. A method for producing a photomask according to 1.   3. The method of manufacturing a photomask according to claim 1, wherein the parameter of the process condition for each of the plurality of regions is a post exposure bake time or temperature. A carry-in unit for carrying the photomask blanks into the charged particle drawing apparatus;
An input unit for inputting drawing data defining a pattern to be drawn on the photomask blank;
A shot data generation unit that converts the drawing data into shot data configured with a shot of a charged particle beam as a unit;
A drawing unit that performs drawing by sequentially irradiating a plurality of regions on the photomask blanks with a charged particle beam using the shot data;
An unloading section for unloading the photomask blanks from the charged particle beam drawing apparatus;
A charged particle beam drawing apparatus, comprising: a monitor unit that monitors a time period from the start of drawing until the photomask blank is carried out of the charged particle drawing apparatus for each of the plurality of regions. 5. The drawing order determining unit according to claim 4, further comprising: a drawing order determining unit that determines a drawing order of the plurality of areas based on a partition ratio of changeable areas of a process condition when post-exposure baking is performed on the photomask blanks. Charged particle beam lithography system.

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