JP2001203161A - Projection aligner and manufacturing method of semiconductor element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a projection aligner and a manufacturing method of semiconductor elements using it, which can realize relative positioning of a reticle and a wafer with high precision by moving a stage with high accuracy, in manufacturing semiconductor elements. SOLUTION: This aligner is provided with an original having a patter to be transferred by exposure, a projection lens for projecting the pattern of the original to the object to be exposed, a positioning means, which relatively positions the original and the object to be exposed, an X-Y table on which the original and the object are mounted, a rotating table which rotates within the plane parallel to the X-Y plane, a position detecting means for detecting the positions of the original and the object regarding each X-direction and Y-direction using a laser interference meter, and a control means which controls the stepped movement of the X-Y table, so as to move the table in the direction that the stepping time is reduced or/and in the direction such that the table is moved from a distant position toward a nearer position regarding the laser interference meter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus for forming a pattern on a flat object such as a wafer or a liquid crystal display panel for manufacturing a semiconductor device, and a method for manufacturing a semiconductor device using the same. In the manufacture of a high-density integrated circuit chip such as a computer or an arithmetic unit, the positioning between a reticle on which a circuit pattern is formed and a wafer can be performed with high accuracy.

[0002]

2. Description of the Related Art Conventionally, a projection exposure apparatus of this kind, for example, a projection exposure apparatus such as a stepper for projecting a pattern drawn on a reticle onto a wafer, has a function of aligning the reticle with the wafer. Exposure was performed after the alignment was performed.

In such alignment, generally, the amount of displacement between an original plate such as a reticle on which a pattern to be projected is drawn and an object to be exposed such as a wafer is measured, and the object to be exposed is measured based on the result. Is moved by wavelength control by a laser interferometer, or by moving an original plate and an object to be exposed.

The apparatus (wafer stage) is positioned by a laser interferometer that measures the length of each of the X and Y axes using a laser beam. The table is used for detecting yaw (rotation) fluctuation components. Two lasers were incident from two laser interferometers parallel to one axis. The detection and control of the yawing fluctuation component during the movement in the XY plane are performed by the measurement values based on the one set (two) of the laser beams.

[0005] In particular, when performing position detection and control by a laser interferometer, as is well known, changes in temperature and pressure on the optical path change the refractive index (INDEX) of air, causing an error in the detected value of the laser interferometer. There is a problem of doing. For this purpose, the conventional apparatus uses a method of monitoring the temperature and the atmospheric pressure, or providing a reference interferometer and feeding back the fluctuation to the laser interferometer.

[0006]

In a conventional apparatus that performs positioning using a laser interferometer, all of the temperature distributions on the optical path are actually realistic even for the installation position of the laser interferometer and the installation position of the thermometer. It is becoming more difficult to be constantly constant.

In particular, in a sequence in which the step direction is separated from the laser interferometer, a change in magnification of the laser interferometer causes a positioning error to be more remarkable. One of the required elements of a stepper is its productivity. In order to increase the productivity, the step time of the wafer stage (XY stage) has been reduced.

However, shortening of the stage positioning time is limited, and further weight increase by adding a function is considered in the future. Therefore, increasing the productivity has become a serious problem with the improvement of the positioning accuracy.

According to the present invention, the reticle and the wafer are aligned with high accuracy by moving the stage with high accuracy without much influence on the alignment accuracy even when the temperature and the atmospheric pressure change in a short time. And a projection exposure apparatus capable of projecting a pattern on a reticle surface onto a wafer surface with high resolution, and a method for manufacturing a semiconductor element using the same.

[0010]

According to the present invention, there is provided a projection exposure apparatus comprising: (1-1) an original plate having a pattern to be exposed and transferred; a projection lens for projecting the pattern of the original plate onto an object to be exposed; Positioning means for mutually aligning the object to be exposed, an XY table on which the original plate or the object to be exposed is mounted, a rotary table rotatable in a plane parallel to the XY plane, Position detecting means for detecting the position of the body in each of the XY directions using a laser interferometer, and a step time for moving the XY table in a stepwise manner when exposing the pattern of the original plate to the object to be exposed step by step. And / or control means for controlling the laser interferometer to move in a direction from a distance to a position closer to the laser interferometer.

In particular, the present invention is characterized in that the X axis of the original plate and the X axis of the XY table are offset by a predetermined angle with respect to the rotation direction in the XY plane.

The method of manufacturing a semiconductor device according to the present invention includes the following steps: (1-2) After detecting a relative position between a reticle and a wafer, a pattern on the reticle surface is stepped on the wafer surface by a projection lens. Successively, and then,
When manufacturing the semiconductor device through the developing process of the wafer, the step movement of the XY table on which the wafer is mounted is moved in a direction to shorten the step time or / and the position information of the XY table is detected. The method is characterized in that a step of moving the laser interferometer from a far side to a near side is used.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of an embodiment of the present invention.

In FIG. 1, reference numeral 9 denotes an original plate (reticle) having a pattern to be exposed and transferred, and is illuminated with a light beam from an exposure illumination system (not shown). Reference numeral 8 denotes a projection lens which projects and exposes a pattern on the reticle 9 surface onto a wafer W on which a resist as an object to be exposed is mounted on a wafer chuck 11. The resist on the surface of the wafer W is subjected to a known developing process, thereby manufacturing a semiconductor device.

1X is a laser interferometer for measuring the length in the X direction,
1Y is a laser interferometer for measuring the length in the Y direction, and 2Yθ is a laser interferometer for performing yawing measurement. Reference numeral 3 denotes a mirror (measured surface XY) which is mounted on the θ rotary table 5.

The θ rotation table 5 is an XY table (X, Y
Stage) 4. Reference numeral 6 denotes a rotary drive mechanism, which comprises a piezoelectric element and rotates the θ-rotation table 5. Reference numerals 7a and 7b denote X and Y driving units (motors), respectively, which drive the XY table 4.

Reference numeral 10 denotes a control box, which includes a drive circuit and the like.

In this embodiment, when the position of a stage is detected and controlled using a laser interferometer, the laser interferometers 1X, 1Y,
In parallel with the correction of the 2Yθ detection error, the rotational positional relationship between the reticle 9 and the XY stage 4 around the Z-axis is set intentionally with an offset, and the shot layout and the direction of the step movement are defined to reduce the step time. The accuracy is improved by shortening (high productivity) and reducing the influence of temperature (atmospheric pressure) change.

In this embodiment, the elements 7a, 7b, 10 and the like constitute one element of the control means.

Next, the features of this embodiment will be described.

FIG. 2 is a schematic view showing an example of a conventional shot arrangement on a wafer surface for transferring a reticle. FIG. 3 is a schematic view showing an example of a shot arrangement by θ angle offset in the XY plane between the reticle stage and the XY stage according to the present invention. 4 and 5 are explanatory views of a laser interferometer and a shot arrangement for reducing an error of the laser interferometer according to the present invention.

First, referring to FIG. 1, the reduction of the stage positioning time (high productivity) will be described.

The X-axis (and Y-axis) of the reticle 9 is offset from the X-axis (and Y-axis) of the XY stage 4 by an angle θ ₁ . Here, a case where a 45 ° offset is provided will be described.

In the conventional projection exposure apparatus, as shown in FIG. 2, the running (X-axis and Y-axis) of the XY stage 4 and the X-axis (and Y-axis) of the reticle 9 are made to coincide with each other and the wafer W is stepped as shown by an arrow. The pattern was transferred to

Here, assuming that step exposure is performed in the arrangement and order as shown in the figure, the XY stage requires a positioning time for at least 20 mm steps for each shot.

On the other hand, in the present embodiment, as shown in FIG. 3, the axes of the reticle and the XY stage are offset (here, 45 °) so that the shot arrangement and the set state of the wafer W are both in the orientation flat section as shown in the figure. the W ₀ and to have a 45-degree offset that is arranged.

Thus, the steps of the XY stage are, for example,

[0028]

(Equation 1)

The above step amount is sufficient, and the same purpose as that of the conventional 20 mm driving of the adjacent shot step amount can be achieved, and the positioning time is greatly reduced.

Next, a description will be given of a step definition for reducing the error effect of the laser interferometer in the present embodiment.

In FIG. 4 and FIG. 5, the X direction changes for each row, and the Y direction error when the Y direction is always stepped in one direction. , 2Yθ) and the case of stepping from the B shot.

Now, assuming that the fluctuation at the start of the step is 0, the step is performed in the Y direction and an error of the laser interferometer occurs. Then, the magnification error Δβ becomes Δβ = AY (A is a coefficient), and the error of the laser interferometer can be considered as a function of Y.

4 and 5, when the initial position is A, L + 1
Assuming that L is 00 and B, the error δ when starting from the shot of A is approximately δ = (L + 100−Y) AY. In the case of B, δ = (L + Y) AY.

Here, L is assumed to be 100 mm and the Y direction is 0 mm.
If the displacement is 100 mm from

[0035]

(Equation 2)

The calculation shows that the error is smaller when starting from A.

As a simpler concept, it is assumed that a laser interferometer error of 0.1 ppm occurs when the movement amount in the Y direction is 100 mm (L is also set to 100 mm).

When A is the starting point, the optical path of the laser interferometer is 2
The starting point is 00 mm, the point is 0, and the error is 0.1 ppm at the position where the optical path of the laser interferometer becomes 100 mm. Therefore, the error amount is 100 mm × 0.1 × 10 ^-6 and 0.01 μm.
m position error.

However, when B is the viewpoint, an error of 0.1 ppm occurs when the optical path of the laser interferometer is 100 mm at 0 mm and 200 mm, so that a positional error of 0.02 μm occurs at 200 mm × 0.1 × 10 ^-6. It will be.

From the above, in the present embodiment, the stepping direction is more advantageous as defined in the direction approaching the laser interferometer. Therefore, in FIG. 2, stepping is performed from S1 and in FIG. 3, stepping is performed from S1 (or (S1)). I have.

Next, another method of reducing the positioning time in this embodiment will be described. In the third embodiment, the rotation offset of the reticle and the XY stage around the Z axis is 45 °.
As described above, this is effective when the moving times of the X step and the Y step are the same.

For example, when there is a difference between the step positioning times in the X direction and the Y direction, the value of the θ rotation offset may be determined according to the difference in the positioning time.

In other words, the reticle set is preferably set at 15 ° or 30 °, and the shot arrangement and the wafer are preferably determined according to the values.

As another method for reducing the influence of the error of the laser interferometer, in the case of FIG. 2, in the X direction, instead of moving from shot S6 to shot S7, go from shot S6 to shot S12. A step operation returning to S6 may be performed. According to this, if the throughput (productivity) is somewhat reduced, it is advantageous for the error of the laser interferometer.

As described above, according to this embodiment, the shot layout and the step moving direction are defined by giving an offset to the rotational direction position of the reticle and the XY stage about the Z axis, thereby reducing the step time. The positioning accuracy is improved by reducing the influence of the high productivity of the apparatus and the change in temperature (atmospheric pressure).

Next, an embodiment of a method of manufacturing a semiconductor device using the above-described exposure apparatus will be described.

FIG. 6 shows a flow of manufacturing a semiconductor device (a semiconductor chip such as an IC or an LSI, or a liquid crystal panel or a CCD).

In step 1 (circuit design), a circuit of a semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design.

In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4
The (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer.

The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes an assembly process (dicing and bonding) and a packaging process (chip encapsulation). And the like.

In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 7 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. Step 14
In (ion implantation), ions are implanted into a wafer. In step 15 (resist processing), a photosensitive agent is applied to the wafer.

In step 16 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the exposure apparatus described above. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed.

By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device which has been conventionally difficult to manufacture.

[0056]

According to the present invention, by setting each element as described above, the productivity is high, and even if the temperature or the atmospheric pressure changes in a short time, the positioning accuracy is not greatly affected. Projection exposure apparatus capable of moving a stage with high precision, aligning a reticle with a wafer with high precision, and projecting a pattern on a reticle surface onto a wafer surface with high resolution, and a semiconductor device using the same. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of an embodiment of the present invention.

FIG. 2 is an explanatory view of a conventional shot layout on a wafer surface.

FIG. 3 is an explanatory view of a shot layout on a wafer surface according to the present invention.

FIG. 4 is an explanatory view of a part of FIG. 1;

FIG. 5 is an explanatory view of a part of FIG. 1;

FIG. 6 is a flowchart of manufacturing a semiconductor device according to the present invention.

FIG. 7 is a flowchart of manufacturing a semiconductor device of the present invention.

[Explanation of symbols]

 1X, 1Y, 2Yθ Laser interferometer 3 Mirror 4 XY table 5 θ rotation table 6 Rotation drive mechanism 7a, 7b XY drive unit 8 Projection lens 9 Reticle W Wafer 10 Control unit θM, XYM Detection mark

Claims (3)

[Claims] 1. An original plate having a pattern to be exposed and transferred, a projection lens for projecting the pattern of the original plate onto an object to be exposed, positioning means for mutually aligning the original plate and the object to be exposed, and the original plate Or, an XY table on which the object to be exposed is mounted, a rotary table rotatable in a plane parallel to the XY plane, and a position for detecting the position of the original plate or the object to be exposed in each of the XY directions using a laser interferometer. Detecting means for moving the XY table in a stepwise manner when sequentially exposing the pattern of the original plate to the object to be exposed in a stepwise direction and / or in a direction from a distance to the laser interferometer from a distance. A control unit for controlling the moving direction of the projection exposure apparatus. 2. The X-axis of the original plate and the X-axis of the XY table
2. The projection exposure apparatus according to claim 1, wherein an axis and an axis are offset by a predetermined angle with respect to a rotation direction in the XY plane. 3. After detecting the relative position between the reticle and the wafer, the pattern on the reticle surface is sequentially projected and exposed on the wafer surface by a projection lens in a stepwise manner. When manufacturing a semiconductor device via the XY table, the step movement of the XY table on which the wafer is mounted is moved in a direction to shorten the step time or / and the laser interferometer for detecting the position information of the XY table. A method for manufacturing a semiconductor device, wherein a method for moving a semiconductor device from a distance to a near position is used.