JP3205663B2 - Charged particle beam equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle beam apparatus such as an electron beam lithography apparatus, and more particularly to a charged particle beam apparatus capable of smoothly moving a sample under a high vacuum or a specific gas atmosphere.

[0002]

2. Description of the Related Art In an electron beam writing apparatus, a sample is placed on a moving stage arranged in a sample chamber evacuated to a vacuum, and a desired writing is performed on the sample by an electron beam while moving the stage. I have. The degree of vacuum around the sample is desirably set to a high vacuum (low pressure) so as not to contaminate the sample. In some cases, the sample is subjected to a process such as drawing in a specific gas atmosphere. In this case, too, the specific gas is introduced into the sample chamber after the sample chamber is evacuated to a high vacuum.

[0003] A moving mechanism for moving the stage in the horizontal direction is arranged in the sample chamber. For example, as the driving mechanism, a mechanism is used in which a stage is mounted on a rail and the stage is moved by a feed screw rotated by a motor provided outside the sample chamber.

[0004]

In general, it is difficult to operate the stage system sufficiently under a high vacuum, and it is particularly difficult to satisfy the operating conditions for continuously moving the stage at a high speed under a high vacuum. difficult. When the sample chamber is set to a specific gas environment, depending on the nature of the gas, the gas and a lubricant provided between the moving part and the fixed part of the stage, or each component of the stage reacts, Adhesion occurs. For this reason, it is difficult to maintain high movement accuracy of a stage system having a relative motion unit, particularly a sliding motion unit such as a ball bearing.

[0005] The present invention has been made in view of such a point, and an object of the invention is to provide a charged stage capable of moving a sample stage with high movement accuracy even when the sample is placed in a high vacuum or a specific gas atmosphere. The object is to realize a particle beam device.

[0006]

According to the present invention, there is provided a charged particle beam apparatus comprising: a stage on which a sample to be irradiated with a charged particle beam is mounted; a moving mechanism for moving the stage in a horizontal direction; A first chamber, a second chamber in which the moving mechanism is placed, a first exhaust system for exhausting the inside of the first chamber, a second exhaust system for exhausting the inside of the second chamber, and a first and a second exhaust system. A partition disposed between the first and second chambers and having an opening through which a part of the stage moved by the moving mechanism penetrates; and a flat plate disposed opposite to the partition at a periphery of the opening and moved with the stage. And a gap of a small exhaust conductance communicating between the inside of the first chamber and the inside of the second chamber is provided between the partition and the flat plate.

[0007]

According to the charged particle beam apparatus of the present invention, the first chamber in which the sample is placed and the second chamber in which the moving mechanism is placed communicate with only a small exhaust conductance gap. A relatively high vacuum is maintained in the first chamber and a relatively low vacuum is maintained in the second chamber.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a main part of one embodiment of the present invention,
FIG. 2 is a partially enlarged view of FIG. In these figures,
Reference numeral 1 denotes a main chamber wall in which the inside becomes a main chamber Mc, and a base member 2 is disposed at the bottom of the inside. A moving stage 4 is mounted on an upper portion of the base member 2 via a guide 3. The stage 4 is formed from a plurality of members, and a female screw is cut into a lower member, and a feed screw 5 is screwed into the female screw.
The feed screw 5 is connected to a motor (not shown) outside the main chamber Mc. By rotating the feed screw 5 by a motor, the stage 4 moves along the guide 3 on the base member 2. In FIG. 1, for simplicity of description, a direction perpendicular to the paper surface (X direction)
Although only the mechanism for moving the stage 4 is shown in the figure, a mechanism for moving the stage 4 in the left-right direction (Y direction) of the drawing is actually added. To realize this movement in the Y direction,
For example, a mechanism similar to the X-direction drive mechanism described above may be provided between the base member 2 and the main chamber wall 1 so as to move the base member 2 in the Y direction.

A sub-chamber wall 6 forming a sub-chamber Sc is provided above the main chamber Mc.
A flat flange 7 is provided at the lower end of the sub-chamber wall 6.
Is provided. A relatively large opening 8 is formed in the center of the flange 7, and the stage 4 is disposed in the sub-chamber Sc through the opening 8. Stage 4
Is provided with a ring-shaped flat plate member 9 facing the lower surface of the flange 7. The distance between the fixed flange 7 and the moving flat plate member 9 is set to be extremely small, and a ring-shaped orifice O is formed between the flange 7 and the flat plate member 9 by this gap (in FIG. Is emphasized). On the upper surface of the stage 4, a sample holder H on which the sample to be drawn 10 is mounted is provided.

An electron beam column 11 is connected to the upper part of the sub-chamber wall 6 forming the sub-chamber Sc via a vacuum joint 20. In FIG. 1, the electron beam column 11
Is partially shown, but the electron beam column 11
Although not shown, an electron gun, a condenser lens, an objective lens, and the like are provided therein. A tube 12 forming an electron beam passage is provided at the center of the electron beam column 11, and an orifice 1 having a small opening through which the electron beam passes is provided at the bottom of the tube 12.
3 is attached.

The interior of the main chamber Mc is evacuated to a vacuum by an exhaust system (not shown) through an exhaust port 14 provided in the wall 1 of the main chamber. Also, the sub-chamber Sc
The inside is connected to an exhaust system (not shown) via an exhaust pipe 15, and the inside of the sub-chamber Sc is evacuated to a high vacuum as appropriate. The inside of the tube 12 forming an electron beam passage in the electron beam column 11 is connected to an exhaust system (not shown) for the electron beam column via an exhaust pipe 16. The subchamber Sc has a tube 1 for sample exchange.
7 is connected. Although not shown, the pipe 17 is connected to the sample exchange chamber via a gate valve. The operation of such a configuration will now be described.

For writing on the sample to be drawn 10, an electron beam is generated from an electron gun in the electron beam column 11, and this electron beam is focused finely by a condenser lens or an objective lens, and is irradiated onto the sample 10. In addition, column 1
The electron beam is deflected in accordance with a drawing pattern by a deflection coil provided in the unit 1. In addition, this drawing sample 10
The drawing of the desired pattern is performed while, for example, the feed screw 5 is rotated by a motor (not shown) to move the stage 4 precisely.

The drawing operation is performed by the electron beam column 11.
, The main chamber Mc, and the sub-chamber Sc are evacuated. Column 11 and both chambers Mc, Sc
The inside of each chamber is independently exhausted, but an orifice 13 is provided between the inside of the electron beam column 11 and the sub-chamber Sc, and the exhaust conductance between the two chambers is significantly reduced. The sub-chamber Sc and the main chamber Mc communicate with each other by a ring-shaped orifice O between the flange 7 and the flat plate member 9.
The conductance of the orifice O is significantly reduced. As a result, the inside of the sub-chamber Sc is evacuated to a high degree of vacuum. Then, the inside of the main chamber Mc is maintained at a relatively low degree of vacuum.

FIG. 3 is a schematic diagram of the configuration shown in FIGS. As shown in FIG. 3, the conductance of the ring-shaped orifice O is C ₁ , the conductance of the orifice 13 is C ₂ , the exhaust speed of the main chamber Mc is S ₁ ,
The ultimate pressure of the main chamber Mc is P ₁ , the exhaust speed of the electron beam column 11 is S ₂ , the ultimate pressure of the electron beam column 11 is P ₂ , the exhaust speed of the sub-chamber Sc is S ₀ , and the ultimate pressure of the sub-chamber Sc is P. ₀ , the released gas amount in the sub-chamber Sc is q.

As a result, the electron beam column 11
Flow into the chamber Sc through the ring-shaped orifice O
The amount of gas to be used is P₁・ C₁, And Also the main chamber
From the Mc to the sub-chamber Sc, a ring-shaped orifice O
The amount of gas flowing through _Two・ C_TwoBecomes Therefore,
Ultimate pressure P in the chamber Sc₀Is expressed as
Can be.

P ₀ = (P ₁ · C ₁ + P ₂ · C ₂ + q) / S ₀ For example, P ₁ = 2 × 10 ⁻⁷ (Torr) P ₂ = 1 × 10 ⁻⁷ (Torr) C ₁ = 2 × 10 ⁻¹ (l / s) C ₂ = 1 × 10 ⁻¹ (l / s) q = 1 × 10 ⁻⁷ (Torr l / s) S ₀ = 1.5 × 10 ² (l / s) Then, the ultimate pressure P ₀ in the sub-chamber Sc is as follows.

P ₀ = (4 × 10 ⁻⁸ + 1 × 10 ⁻⁸ + 1 ×
10 ⁻⁷ ) / (1.5 × 10 ² ) = (1.5 × 10 ⁻⁷ )
/(1.5×10 ² ) = 1 × 10 ⁻⁹ (Torr) Ultimate pressure P ₁ in the main chamber Mc = 2 × 10 ⁻⁷
(Torr) is a pressure at which sufficient performance can be maintained by using a conventional vacuum lubricant for the stage system. Further, the ultimate pressure P ₀ in the sub-chamber Sc = 1 × 10 ⁻⁹ (Torr)
Is a pressure that is sufficient to prevent contamination of the sample and perform precise writing.

Incidentally, the ultimate pressure P of the sub-chamber Sc
Obviously, in order to make ₀ sufficiently low, it is important to reduce the amount of released gas q. Under the specific conditions described above, the amount of released gas is set to 2.5 × 10 ⁻⁸ (Torr
(rl / s), the ultimate pressure P ₀ in the sub-chamber Sc is as follows.

P ₀ = (4 × 10 ⁻⁸ + 1 × 10 ⁻⁸ +2.
5 × 10 ⁻⁸ ) / (1.5 × 10 ² ) = (7.5 × 10 ² )
⁻⁸ ) / (1.5 × 10 ² ) = 5 × 10 ⁻¹⁰ (Torr) In order to reduce the amount of released gas q, baking is necessary. There are some limitations when assembling each component after baking and baking the whole. First,
In addition, it is necessary to limit the temperature rise of the mirror for laser measurement (not shown) provided in the stage system. When the mirror is fixed by bonding, the temperature is several tens of degrees, and there is a limitation on the relative movement part of the stage system. Second, the baking time is generally long, and there is a constant flow of heat into the proximity. Therefore, a method for removing this heat is needed.

Therefore, the sub-chamber Sc of the stage 4
It is effective to thermally insulate the portion in contact with (the portion to be baked) from the portion in the main chamber Mc (the portion where heating is not preferable) and cool the portion in the main chamber Mc. As a result, it is possible to prevent the mirror portion and the like of the laser measurement system provided in the portion of the stage 4 in the main chamber Mc from being heated to a high temperature and the accuracy from being lowered.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, the drawing apparatus has been described as an example, but the present invention can also be applied to other charged particle beam apparatuses having a mechanism for moving a sample in a vacuum such as a scanning electron microscope. Also, an example in which the inside of the sub-chamber is evacuated to a high vacuum has been described, but the present invention can be applied to a case where a specific gas is introduced after the inside of the sub-chamber is evacuated to a high vacuum.

[0022]

As described above, in the charged particle beam apparatus according to the present invention, only a small exhaust conductance gap is provided between the first chamber in which the sample is placed and the second chamber in which the moving mechanism is placed. And the first chamber is maintained at a relatively high degree of vacuum by differential pumping, and the second chamber is maintained at a relatively low degree of vacuum. As a result, the slide drive unit of the stage system and the sample peripheral part can be substantially vacuum-separated,
While sufficient lubrication for driving the stage system can be ensured, the periphery of the sample can be brought into a high vacuum state. Therefore, there is no need to develop a stage compatible with high vacuum.

Further, since an orifice is provided between the subchamber and the electron beam column, and an exhaust system is provided on the electron gun side of the orifice, the subchamber is easily evacuated to a high vacuum, and gas is supplied to the subchamber. Even if inserted, the effect on the electron gun can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing an electron beam writing apparatus according to one embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a schematic diagram of the configuration of FIGS. 1 and 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main chamber wall 2 Base member 3 Guide 4 Moving stage 5 Feed screw 6 Sub-chamber wall 7 Flange 8 Opening 9 Plate member 10 Sample 11 Electron beam column 12 Tube 13 Orifice 14 Exhaust port 15, 16 Exhaust pipe

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-26665 (JP, A) JP-A-55-59719 (JP, A) JP-A-56-1448827 (JP, A) 186425 (JP, U) Actually open 63-36035 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027

Claims (1)

(57) [Claims] 1. A stage on which a sample to be irradiated with a charged particle beam is mounted, a moving mechanism for moving the stage in a horizontal direction, a first chamber in which the sample is placed, and a second chamber in which the moving mechanism is placed. A first exhaust system that exhausts the inside of the first chamber, a second exhaust system that exhausts the inside of the second chamber, and the first and second chambers. A partition having an opening through which a part of the stage to be penetrated, and a flat plate that is arranged to face the partition at the periphery of the opening and moves together with the stage, and between the partition and the flat plate. A charged particle beam apparatus, wherein a small exhaust conductance gap communicating between the inside of the first chamber and the inside of the second chamber is provided.