Gap adjustment apparatus and gap adjustment method for adjusting gap between two objects

• US 20050005707A1
• Filed: 08/05/2004
• Published: 01/13/2005
• Est. Priority Date: 11/28/2000
• Status: Active Grant

• Current Assignee: Sumitomo Heavy Industries Limited
• Original Assignee: Sumitomo Heavy Industries Limited
• Inventors: Li, Xuan
• Granted Patent: US 7,225,048 B2
• Time in Patent Office: Days
• US Class Current: 73/832
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G03F 7/7035 Proximity or contact printers
• CPC Class Codes: G03F 7/70775 Position control, e.g. interferometers or encoders for determining the stage position
• CPC Class Codes: H01J 37/3174 Particle-beam lithography, e.g. electron beam lithography
• CPC Class Codes: H01L 21/682 Mask-wafer alignment in general G03F7/70, G03F9/70

Abstract

A first stage and a second stage are disposed to face each other. A first object is fixed on the first stage. A first displacement sensor attached on the first stage is used to measure a distance extending from the first displacement sensor to a plane disposed in front of the first displacement sensor. A second object is fixed on the second stage. A second displacement sensor attached on the second stage is used to measure a distance extending from the second displacement sensor to a plane disposed in front of the second displacement sensor. A moving mechanism is provided to move one of the first stage and the second stage, with the movement of one stage being relative to the other stage.

Claims

1. A gap adjustment apparatus comprising:

a first stage defining a first reference surface;

a second stage defining a second reference surface, the second stage being opposite to the first stage in a manner such that the second reference surface becomes parallel to the first reference surface;

a first chuck for fixing a first object having a main surface on the first stage, in a manner such that the main surface of the first object faces towards the second stage and becomes parallel to the first reference surface;

a first displacement sensor attached on the first stage and adapted to measure a distance between the first displacement sensor and a certain plane disposed in front of the first displacement sensor and parallel to the second reference surface;

a second chuck for fixing a second object having a main surface on the second stage, in a manner such that the main surface of the second object faces towards the first stage and becomes parallel to the second reference surface;

a second displacement sensor attached on the second stage and capable of measuring a distance between the second displacement sensor and a certain plane disposed in front of the second displacement sensor and parallel to the first reference surface;

an eddy current sensor attached on the first stage and having a sensor reference surface parallel to the first reference surface;

an eddy current sensor target attached on the second stage and having a target reference surface parallel to the second reference surface;

a moving mechanism for moving one of the first stage and the second stage in a direction parallel to the first reference surface and in another direction perpendicular to the first reference surface, with the movement of one stage being relative to the other stage;

a controller which is adapted to drive the moving mechanism in a manner such that the target can be located in front of the first displacement sensor, to measure a distance extending from the first displacement sensor to the target reference surface of the target, to drive the moving mechanism in a manner such that the second main surface can be located in front of the first displacement sensor, to measure a distance extending from the first displacement sensor to the second main surface, to drive the moving mechanism in a manner such that the eddy current sensor can be located in front of the second displacement sensor, to measure a distance extending from the second displacement sensor to the sensor reference surface of the eddy current sensor, to drive the moving mechanism in a manner such that the first main surface can be located in front of the second displacement sensor, to measure a distance extending from the second displacement sensor to the first main surface, to drive the moving mechanism in a manner such that the target can be located in front of the eddy current sensor, and to measure an distance between the sensor reference surface and the target reference surface.

2. A gap adjustment apparatus according to claim 1, further comprising:

a first height adjusting mechanism capable of adjusting a height from the first reference surface to the sensor reference surface of the eddy current sensor; and

a second height adjusting mechanism capable of adjusting a height from the second reference surface to the target reference surface of the target;

wherein the controller is adapted to drive the second height adjusting mechanism in accordance with a measurement result of the first displacement sensor, in a manner such that the height from the second reference surface to the target reference surface becomes equal to a height from the second reference surface to the main surface of the second object, and to drive the first height adjusting mechanism in accordance with a measurement result of the second displacement sensor, in a manner such that the height from the first reference surface to the sensor reference surface becomes equal to a height from the first reference surface to the main surface of the first object.

3. A gap adjustment method comprising:

a first step of fixing a first object on a first stage defining a first reference surface, in a manner such that a main surface of the first object becomes parallel to the first reference surface;

a second step of fixing a second object on a second stage defining a second reference surface parallel to the first reference surface, in a manner such that a main surface of the second object becomes parallel to the second reference surface;

a third step of calculating or adjusting a relationship between a sensor reference surface'"'"'s height from the first reference surface and a height from the first reference surface to the main surface of the first object, a position of the sensor reference surface being fixed relative to a reference surface of an eddy current sensor attached on the first stage;

a fourth step of calculating or adjusting a relationship between a target reference surface'"'"'s height from the second reference surface and a height from the second reference surface to the main surface of the second object, the target reference surface being a target reference surface of an eddy current sensor target being fixed relative to the second stage; and

a fifth step of measuring a distance extending from the sensor reference surface of the eddy current sensor to the target reference surface, and for adjusting a distance between the first stage and the second stage so as to enable a measurement result to be closer to a desired value.

4. A gap adjustment method according to claim 3, wherein the third step is provided to effect an adjustment such that the sensor reference surface and the main surface of the first object can be in exactly the same plane, while the fourth step is provided to effect an adjustment such that the target reference surface and the main surface of the second object can be in exactly the same plane.

5. A gap adjustment apparatus comprising:

a mask chuck for holding a mask having a mask pattern formed thereon;

a first leveling mechanism for holding the mask chuck and capable of moving the mask chuck in a first direction perpendicular to a surface on which the mask pattern of the mask fixed on the mask chuck has been formed;

a mask stage for supporting the first leveling mechanism;

a wafer chuck for holding the wafer in a manner such that an exposure surface of the wafer is caused to face towards the mask;

a second leveling mechanism capable of moving the wafer chuck in the first direction;

a wafer stage for holding the second leveling mechanism;

a first distance sensor attached on the mask stage and capable of measuring a distance in the first direction, the distance extending to the exposure surface of the wafer held on the wafer chuck; and

a second distance sensor attached on the wafer stage and capable of measuring a distance in the first direction, the distance extending to the surface of the mask fixed on the mask chuck, and also capable of measuring another distance in the first direction, the other distance extending to the first distance sensor.

6. A gap adjustment apparatus according to claim 5, further comprising a first two-axis moving mechanism which is so formed that when the relative positions of the mask chuck and the first distance sensor have been fixed, both the mask chuck and the first distance sensor are moved in a direction perpendicular to the first direction.

7. A gap adjustment apparatus according to claim 5, further comprising a second two-axis moving mechanism for moving the wafer in a direction perpendicular to the first direction, without having to move the second sensor.

8. A gap adjustment apparatus according to claim 6, further comprising a second two-axis moving mechanism for moving the wafer in a direction perpendicular to the first direction, without having to move the second sensor.

9. A gap adjustment apparatus according to claim 5, further comprising a controlling device such that when DA represents a distance extending from the second distance sensor to the first distance sensor, DB represents a distance extending from the second distance sensor to the surface of the mask, and DD represents a distance extending from the first distance sensor to the exposure surface of the wafer, DD−

(DA−

DB) is compared with a desired value, and the first leveling mechanism or the second leveling mechanism is operated so that DD−

(DA−

DB) becomes closer to the desired value.

10. A gap adjustment apparatus according to claim 6, further comprising a controlling device such that when DA represents a distance extending from the second distance sensor to the first distance sensor, DB represents a distance extending from the second distance sensor to the surface of the mask, and DD represents a distance extending from the first distance sensor to the exposure surface of the wafer, DD−

(DA−

DB) is compared with a desired value, and the first leveling mechanism or the second leveling mechanism is operated so that DD−

(DA−

DB) becomes closer to the desired value.

11. A gap adjustment method comprising:

a step of disposing a first measurement object having a first surface and a second measurement object having a second surface so that the first surface and the second surface face each other, in a manner such that the first surface of the first measurement object and the second surface of the second measurement object become perpendicular to a first direction;

a step of measuring a distance DA in the first direction, the distance extending from a first distance sensor to a second distance sensor;

a step of measuring a distance DB in the first direction, the distance extending from the second distance sensor to the surface of the first measurement object;

a step of measuring a distance DD in the first direction, the distance extending from the first distance sensor to the second surface of the second measurement object; and

a step of moving at least one of the first measurement object and the second measurement object in the first direction to make DD−

(DA−

DB) closer to a desired value.

12. A gap adjustment apparatus comprising:

a first holding member for fixing and holding a first measurement object having a first surface;

a first leveling mechanism capable of holding the first holding member and moving the first holding member in a first direction perpendicular to the first surface of the first measurement object fixed on the first holding member;

a first stage for holding the first leveling mechanism;

a second holding member for holding a second measurement object having a second surface, in a manner such that second surface faces towards the first surface;

a second leveling mechanism capable of moving the second holding member in the first direction;

a second stage for holding the second leveling mechanism;

a first distance sensor attached on the first stage, capable of measuring a distance in the first direction extending to the second surface of the second measurement object fixed on the second holding member; and

a second distance sensor attached on the second stage, for measuring a distance in the first direction extending to the first surface of the first measurement object fixed on the first holding member, and another distance in the first direction extending to the first distance sensor.

13-24. -24. (Canceled).