JP2010074046A - Charged particle beam-drawing method and charged particle beam-drawing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charged particle beam-drawing method and an charged particle beam-drawing device that securely obtain electric conduction by dielectric breakdown, and suppress damage to a mask and a terminal and the generation of particles when a grounding terminal is made electrically conductive by dielectric breakdown to achieve high drawing precision. <P>SOLUTION: In the charged particle beam-drawing method, a first grounding terminal and a second grounding terminal are arranged on a sample having a conductive film and a resist film formed in this order on a substrate, a voltage is applied between the first grounding terminal and second grounding terminal and gradually increased to break the resist film, and the first grounding terminal and second grounding terminal are electrically connected to each other to ground the sample through the first grounding terminal and second grounding terminal, thereby performing drawing by irradiation with an electrically charged particle beam. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a charged particle beam drawing method and a charged particle beam drawing apparatus used for forming a lithography mask in a semiconductor manufacturing process, for example.

  In recent years, with higher integration of semiconductor devices, there is a demand for miniaturization of mask patterns for forming circuit patterns. A charged particle beam drawing apparatus having excellent resolution is used to form a fine mask pattern.

  With such a charged particle beam drawing apparatus, a pattern drawing is performed by irradiating a charged particle beam such as an electron beam onto a sample in which, for example, a Cr film (light-shielding / conductive film) and a resist film are sequentially formed on a quartz glass substrate. Then, the resist film is exposed to a predetermined pattern. Then, a light shielding pattern (mask pattern) of Cr is formed by development and etching.

  When the mask pattern is formed in this way, the charged particle beam trajectory is bent or the beam blur occurs due to the charge-up of the resist film during pattern drawing, and the mask pattern drawing accuracy deteriorates. Problem occurs. Therefore, it is necessary to bring the conductive member into contact with the Cr film and ground it. Therefore, grounding is performed by penetrating the resist film using a terminal processed into a needle shape or a blade shape.

However, when the sharp terminal is brought into direct contact with the Cr film, the glass substrate is damaged, and there is a problem that the drawing accuracy is deteriorated due to contact failure or generation of particles due to wear or chipping of the contact portion. In view of this, it has been proposed that terminals are placed on a resist film, and a terminal is made conductive by applying a voltage to cause dielectric breakdown of the resist film (see, for example, Patent Document 1).
JP-A-9-205050 (Claim 1 etc.)

  As described above, electrical continuity between the sample and the grounding terminal can be obtained by dielectric breakdown of the resist film. However, if a voltage higher than the withstand voltage of the resist film is suddenly applied for dielectric breakdown, a large current flows suddenly, and a burst phenomenon occurs between the sample and the terminal. Due to the burst phenomenon, not only the resist film but also the Cr film and the glass substrate are destroyed, and further, the terminal itself is also damaged. And the problem that drawing precision falls by contact failure and generation | occurrence | production of a particle has arisen.

  Further, even when a constant voltage is applied, dielectric breakdown does not occur and conduction between the sample and the grounding terminal may not be obtained.

  Therefore, the present invention can reliably obtain conduction by dielectric breakdown in charged particle beam drawing, and suppresses mask and terminal damage and particle generation when conducting a grounding terminal by dielectric breakdown, and high drawing. An object of the present invention is to provide a charged particle drawing method and a charged particle drawing apparatus capable of obtaining accuracy.

  In the charged particle beam writing method according to the present invention, a first grounding terminal and a second grounding terminal are arranged on a sample in which a conductive film and a resist film are sequentially formed on a substrate. Between the first grounding terminal and the second grounding terminal, by applying a voltage between the first grounding terminal and the second grounding terminal by applying a voltage between the first grounding terminal and the second grounding terminal. Drawing is performed by grounding a sample with a first grounding terminal and a second grounding terminal and irradiating a charged particle beam.

  In the charged particle beam drawing method of the present invention, after the first grounding terminal and the second grounding terminal are conducted, the current value between the first grounding terminal and the second grounding terminal is measured. It is preferable to confirm the continuity.

  In the charged particle beam writing method of the present invention, it is preferable that the voltage increased stepwise does not exceed a predetermined voltage set in advance.

  A charged particle beam drawing apparatus according to the present invention includes a first chamber in which a first ground terminal and a second ground terminal are disposed on a sample in which a conductive film and a resist film are sequentially formed on a substrate; The first chamber includes a variable voltage application mechanism for applying a voltage stepwise between the first grounding terminal and the second grounding terminal arranged, and a grounding terminal, and a charged particle beam is placed on the sample. And a second chamber for irradiation.

  The charged particle beam drawing apparatus of the present invention preferably includes a current detection mechanism for detecting a current between the first grounding terminal and the second grounding terminal arranged in the first chamber.

  According to the present invention, charged particle drawing capable of reliably obtaining conduction by dielectric breakdown, and suppressing damage to a mask and a terminal when conducting a grounding terminal by dielectric breakdown and obtaining high drawing accuracy. A method and a charged particle beam drawing apparatus can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic configuration of an electron beam drawing apparatus according to the present embodiment. The electron beam drawing apparatus 11 of the present embodiment shown in FIG. 1 includes a load lock chamber 12 for carrying a sample 10 and the like and switching to a vacuum state, and a robot arm 13 for carrying the carried sample 10 and the like. A mask cover for attaching the mask cover 17 to a predetermined position on the sample 10 is provided with an alignment chamber 15 for aligning the sample 10 and an external power source, circuit and stage 16a, which will be described later. A storage chamber 16 and a stage 18b for placing a sample provided with a ground terminal 18a are installed, and are composed of a drawing chamber 18 for drawing on the sample 10 and the like.

  FIG. 2 shows a conceptual configuration diagram of the mask cover storage chamber 16. As shown in the figure, a DC power source 21 and a controller 22 connected to the DC power source 21 are disposed outside the mask cover storage chamber 16. The controller 22 is provided with a variable voltage control circuit 22a and a current control circuit 22b that can change the voltage. The variable voltage control circuit 22a and the current control circuit 22b can be connected to a ground plate to be described later through terminals 23a and 23b.

  Using such an electron beam drawing apparatus, drawing is performed on the sample as follows.

  First, as shown in FIG. 3, the ground plates 32a and 32b, to which the ground terminals 31a and 31b are attached, are fixed to the frame-like frame having an opening at the center by a screw or the like. A cover 17 is configured. At this time, the grounding terminals 31 a and 31 b are attached so as to protrude into the opening of the mask cover 17.

  Then, the sample 10 in which the Cr film and the resist film are sequentially laminated on the glass substrate is carried from the load lock chamber 12 and is carried by the robot arm 13 to the alignment chamber 15 through the carrying chamber 14. In the alignment chamber 15, edge scan using a CCD camera (not shown) or the like is used to detect and correct the positional deviation or rotational deviation of the sample 10.

  The sample 10 in which the positional deviation and the rotational deviation are corrected is transferred to the mask cover storage chamber 16 by the robot arm 13 via the transfer chamber 14. After the transported sample 10 is placed on the stage 16 a, a mask cover 17 is attached on the sample 10. At this time, the tips of the ground terminals 31a and 31b are in contact with the resist film. Then, the ground terminals 31 a and 31 b are connected to the DC power source 21 via the controller 22.

  As shown in the flowchart in FIG. 4, the controller 22 controls the variable voltage control circuit 22a to apply a voltage of 1 V, for example, between the ground terminals 31a and 31b connected to the terminals 23a and 23b, respectively (S11). At this time, the current value and the resistance value are measured simultaneously. Then, it is determined whether or not the current is detected and the threshold value has been reached (S12). If not, the set voltage is increased by, for example, 1V (S13). Then, it is determined whether or not the set voltage is not more than a specified voltage (for example, 50V) (S14). If the set voltage is not more than the specified voltage, the set voltage is applied as it is (S11). If the set voltage exceeds the specified voltage, an error occurs and the mask cover 17 is temporarily released (S15). Then, for example, it is newly attached to the sample 10 and a voltage is applied again.

  In this way, the voltage is increased stepwise, and voltage application and current measurement are repeated. When the voltage exceeds the withstand voltage of the resist film, conduction is obtained by dielectric breakdown, the voltage is detected, and the current value reaches a threshold value.

  When the voltage is detected and the current value reaches the threshold value, continuity is confirmed next. Next, using the current control circuit 22b, a constant voltage (for example, 10V) is applied between the ground terminals 31a and 31b (S21), and the current value and the resistance value are measured (S22). It is determined whether or not the current value or the resistance value is within a specified range (S23). If it is within the specified range, the conduction check is terminated. If it is outside the specified range, an error occurs and the mask cover 17 is released (S15). Then, for example, the sample 10 is carried out, a new sample is carried in, the mask cover 17 is similarly attached, and a voltage is applied for confirming dielectric breakdown and conduction.

Examples of the relationship between voltage, current value, resistance value, and time when dielectric breakdown and conduction confirmation are performed in this manner are shown in FIGS. 5A, 5B, and 5C, respectively. As shown in the figure, when the voltage is increased step by step from the time t _{0 at} the time of the dielectric breakdown, the current value exceeds the threshold due to the dielectric breakdown at the time t ₁ when the voltage becomes equal to or higher than the withstand voltage of the resist film. The resistance value has dropped rapidly. Further, when confirming the continuity, a constant voltage is applied from time t ₀ ′ to t ₁ ′, and the current value and resistance value that are constant are measured.

  The sample 10 / mask cover 17 that has been confirmed to be conductive is transferred to the drawing chamber 18 by the robot arm 13 via the transfer chamber 14.

  The sample 10 / mask cover 17 conveyed to the drawing chamber 18 is placed on the stage 18b and grounded via the ground terminal 18a. A desired pattern is drawn by irradiating a desired position of the sample 10 with an electron beam emitted from an electron gun (not shown) and shaped into a desired shape.

  The sample 10 on which the pattern has been drawn is unloaded from the drawing chamber 18 while being attached to the mask cover 17, and is loaded into the mask cover storage chamber 16 via the transfer chamber 14 by the robot arm 13. Then, after removing the mask cover 17, the mask cover 17 is unloaded from the mask cover storage chamber 16, and is unloaded from the electron beam drawing apparatus 11 through the transfer chamber 14 and the load lock chamber 12.

  According to the present embodiment, the burst phenomenon between the mask and the terminal due to a rapid voltage application can be suppressed by performing the dielectric breakdown of the resist film in this way. Due to the occurrence of the burst phenomenon, the resist film is largely broken to about 120 μm, for example, and the resist is denatured around the opening. Furthermore, not only the resist film but also the Cr film and the glass substrate are destroyed, and further, the terminal itself is also damaged. However, according to the present embodiment, due to normal dielectric breakdown, an appropriate opening of the resist film having a diameter of, for example, about 30 μm can be obtained to obtain conduction. And it becomes possible to suppress the fall of drawing precision by contact failure and generation | occurrence | production of a particle.

  In addition, conduction can be reliably obtained by dielectric breakdown. For example, when a constant voltage (for example, 10V) is applied as in the prior art, continuity can be obtained only with a probability of, for example, about 50%, whereas according to the present embodiment, a probability of almost 100% is obtained. Conductivity can be obtained.

  In the present embodiment, the maximum voltage at the time of dielectric breakdown is defined as 50 V, for example, but the maximum voltage is set as appropriate. Usually, when the contact state of each terminal is good, conduction can be confirmed at a relatively low voltage (for example, about 1 to 5 V), although it depends on the thickness and type of the resist film. However, when the contact state is poor, conduction may not be confirmed even when a relatively high voltage (for example, 80 V) is applied. In such a case, even if the voltage is increased step by step, a burst phenomenon may occur if a certain value is exceeded. Therefore, as in the present embodiment, by setting a limit on the maximum voltage, it is possible to suppress the occurrence of a burst phenomenon due to a poor contact state.

  Further, since damage to the grounding terminal is suppressed, contact failure is suppressed, high drawing accuracy can be obtained, and maintenance time can be shortened by reducing the replacement frequency.

  In the present embodiment, the grounding terminals are provided in two places, but may be provided in three places or more.

  In this embodiment, the electron beam drawing apparatus has been described, but the present invention can be applied to a drawing apparatus using a charged particle beam including an ion beam.

  In addition, this invention is not limited to embodiment mentioned above. Various other modifications can be made without departing from the scope of the invention.

1 is a schematic configuration diagram of an electron beam drawing apparatus according to an embodiment of the present invention. The conceptual block diagram of the alignment chamber which concerns on embodiment of this invention. The top view which shows the mask cover which concerns on embodiment of this invention. The flowchart of the electron beam drawing process which concerns on embodiment of this invention. The figure which shows the relationship between the voltage and time when performing the dielectric breakdown and conduction | electrical_connection confirmation which concern on embodiment of this invention. The figure which shows the relationship between the electric current value and time when performing the dielectric breakdown and conduction | electrical_connection confirmation which concern on embodiment of this invention. The figure which shows the relationship between resistance value when performing dielectric breakdown and conduction | electrical_connection confirmation which concern on embodiment of this invention, and time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Sample 11 ... Electron beam drawing apparatus 12 ... Load lock chamber 13 ... Robot arm 14 ... Transfer chamber 15 ... Alignment chamber 16 ... Mask cover storage chamber 17 ... Mask cover 16a, 18b ... Stage 18 ... Drawing chamber 18a ... Grounding terminal 21 ... DC power supply 22 ... Controller 22a ... Variable voltage control circuit 22b ... Current control circuits 23a and 23b ... Terminals 31a and 31b ... Grounding terminals 32a and 32b ... Earth plate

Claims (5)

A first grounding terminal and a second grounding terminal are disposed on a sample in which a conductive film and a resist film are sequentially formed on a substrate,
A voltage is applied between the first grounding terminal and the second grounding terminal;
Increasing the voltage stepwise,
By conducting a breakdown of the resist film, the first grounding terminal and the second grounding terminal are electrically connected,
A charged particle beam drawing method, wherein drawing is performed by grounding the sample by the first grounding terminal and the second grounding terminal and irradiating a charged particle beam.   After conducting between the first grounding terminal and the second grounding terminal, measuring the current value between the first grounding terminal and the second grounding terminal to confirm conduction. The charged particle beam drawing method according to claim 1.   The charged particle beam drawing method according to claim 1, wherein the voltage increased stepwise does not exceed a predetermined voltage set in advance. A first chamber in which a first grounding terminal and a second grounding terminal are disposed on a sample in which a conductive film and a resist film are sequentially formed on a substrate;
A variable voltage applying mechanism for applying a voltage stepwise between the first grounding terminal and the second grounding terminal arranged in the first chamber;
A charged particle beam drawing apparatus comprising: a second chamber that includes a ground terminal and irradiates the sample with a charged particle beam.   5. The charged particle beam according to claim 4, further comprising a current detection mechanism configured to detect a current between the first grounding terminal and the second grounding terminal arranged in the first chamber. Drawing device.

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