CN201181387Y - Dual-stage exchange device for silicon wafer stage of lithography machine using cross guide rail - Google Patents

Abstract

The utility model relates to a dual-table exchanging device for silicon wafer stages of a lithography machine using cross guide rails, which is mainly used in semiconductor lithography machines. The utility model comprises a silicon wafer table running on a pretreatment station, a silicon wafer table running on an exposure station and two cross guide rail drive units, each cross guide rail drive unit includes an X-direction linear motor, a Y-direction linear motor and a The push rod used to push the movement of the silicon wafer stage; the cross rail drive unit and the silicon wafer stage are sucked by vacuum bearings to drive the silicon wafer stage to move in a large range of X and Y directions. The utility model adopts two double-degree-of-freedom drive units, which greatly simplifies the structure of the device and effectively reduces the requirement for synchronous control.

Description

Dual-stage exchange device for silicon wafer stage of lithography machine using cross guide rail

technical field

The utility model relates to a dual-table exchanging device for photolithography machines, which is mainly used in semiconductor photolithography machines and belongs to the technical field of semiconductor manufacturing equipment.

Background technique

In the production process of integrated circuit chips, the exposure transfer (photolithography) of the design pattern of the chip on the photoresist on the surface of the silicon wafer is one of the most important processes. The equipment used in this process is called a photolithography machine (exposure machine). The resolution and exposure efficiency of the lithography machine greatly affect the characteristic line width (resolution) and productivity of the integrated circuit chip. As the key device of the lithography machine, the motion accuracy and work efficiency of the silicon wafer ultra-precision motion positioning device (hereinafter referred to as the wafer stage) largely determine the resolution and exposure efficiency of the lithography machine.

The basic principle of the step-and-scan projection lithography machine is shown in Figure 1. The deep ultraviolet light from the light source 45 passes through the reticle 47 and the lens device 49 to image a part of the pattern on the reticle on a certain chip of the silicon wafer 50 . The reticle and the silicon wafer move synchronously in reverse at a certain speed ratio, and finally image all the patterns on the reticle on a specific chip (Chip) of the silicon wafer.

The basic function of the movement positioning device of the silicon wafer stage is to carry the silicon wafer and move according to the set speed and direction during the exposure process, so as to realize the precise transfer of the mask pattern to each area on the silicon wafer. Since the line width of the chip is very small (currently the minimum line width has reached 45nm), in order to ensure the overlay accuracy and resolution of lithography, the silicon wafer stage is required to have extremely high motion positioning accuracy; since the movement speed of the silicon wafer stage is within It greatly affects the productivity of lithography, and from the perspective of improving productivity, it also requires the movement speed of the silicon wafer table to be continuously increased.

In the traditional wafer stage, as described in patent EP 0729073 and patent US 5996437, there is only one wafer motion positioning unit in the lithography machine, that is, a wafer stage. The preparatory work such as leveling and focusing must be done on it. These tasks take a long time, especially for alignment. Due to the requirement of extremely high-precision low-speed scanning (typical alignment scanning speed is 1mm/s), so It takes a long time. It is very difficult to reduce their working hours. In this way, in order to improve the production efficiency of the lithography machine, it is necessary to continuously increase the moving speed of the stepping of the silicon wafer stage and the exposure scanning. The increase in speed will inevitably lead to the deterioration of the dynamic performance of the device. It is necessary to take a large number of technical measures to ensure and improve the movement accuracy of the wafer stage, and the price to be paid to maintain the existing accuracy or achieve higher accuracy will be greatly increased.

The structure described in patent W098/40791 (publication date: 1998.9.17; country: the Netherlands) adopts a double wafer stage structure, and transfers exposure preparations such as loading and unloading, pre-alignment, and alignment to the second wafer stage on, and move independently with the exposure wafer stage at the same time. On the premise of not increasing the movement speed of the wafer stage, a large amount of preparation work for the exposure wafer stage is shared by the second wafer stage, thus greatly shortening the working time of each wafer on the exposure wafer stage and greatly improving production efficiency. However, the main disadvantage of this device is the non-centroid driving problem of the wafer stage device.

The applicant applied for a utility model patent in 2003, "Double Stepper Projection Lithography Machine Rotating Exposure Ultra-Precise Positioning Silicon Wafer Device" (patent application number: ZL03156436.4) discloses a double-silicon wafer with double-sided linear guide rail The wafer stage exchange structure, the double wafer stage device does not overlap in the working space, so no collision prevention device is required. However, there are also some problems in this double wafer stage device. First, the device requires extremely high butt joint precision of the guide rails; This is undoubtedly very important for semiconductor chip factories with high space utilization requirements. The 3rd, need adopt the bridging device with driving device when this device silicon chip stage is exchanged, increased the complexity of device.

In 2007, the applicant applied for a utility model patent "a device for exchanging silicon wafer stages for lithography machines" (patent application number: 200710119275.7), which discloses a dual-stage silicon wafer stage realized by 4 sets of dual-degree-of-freedom drive units. The structure of the exchange, the device has the advantages of simple structure, small size and the like. However, since the movement of the silicon wafer stage is realized by the synchronous movement of two adjacent two-degree-of-freedom drive units, the device has high requirements for synchronous control.

Utility model content

The utility model aims at the shortcomings and defects of the complex structure of the above-mentioned utility model application and high requirements for the synchronous control of the device, and proposes a double-swap exchange device for the silicon chip table of the lithography machine using a cross guide rail

The technical scheme of the utility model is as follows:

A dual wafer stage exchange device for photolithography machines using cross guide rails, the device includes a wafer stage operating at a pretreatment station and a wafer stage operating at an exposure station, the two wafer stages are set On an abutment, and suspended on the surface of the abutment by an air bearing, it is characterized in that: the device adopts two cross guide rail drive units, which are respectively arranged on the edges of the opposite sides of the abutment, and each cross guide rail drive unit contains X The stator of the X-direction linear motor is installed in the groove on the edge of the abutment, and the mover is installed on the lower bottom of the cross rail drive unit; the Y-direction linear motor and the X-direction linear motor are stacked. Arranged in layers and perpendicular to the X-direction linear motor; the cross rail drive unit and the wafer stage are sucked by vacuum bearings, and the vacuum bearings are arranged on the side of the push rod and the wafer stage.

Compared with the dual-stage exchanging device for lithography machine silicon wafer tables (application number: 200710119275.7) previously applied by the applicant, the utility model reduces two sets of double-degree-of-freedom drive units, greatly simplifies the device structure, and effectively reduces the synchronous control requirements.

Description of drawings

Figure 1 shows the basic working principle of a step-and-scan projection lithography machine.

Fig. 2 is a motion positioning device for a single wafer stage.

Fig. 3 is a motion positioning device for double silicon wafer stages provided by the utility model.

Figure 4a shows the installation position of the X-direction and Y-direction linear motors in the cross rail drive unit.

Fig. 4b is a structural schematic diagram of the push rod.

Fig. 5a, Fig. 5b and Fig. 5c respectively show the state schematic diagrams during the exchange process of the double silicon wafer stage.

In the picture:

1-wafer stage; 4-cross rail drive unit; 5-X-direction linear motor; 7-Y-direction linear motor; 8-push rod; 11-base platform; 45-light source; 47-mask plate; ; 50-wafer.

Detailed ways

The traditional step-and-scan projection lithography machine wafer stage is shown in Figure 2. There is only one wafer movement positioning device in the lithography machine, that is, there is only one wafer stage. Preparations such as leveling, focusing, and alignment are all done on the same wafer stage, and these tasks take a long time, especially for alignment, which requires extremely high-precision low-speed scanning (typical alignment The scanning speed is 1mm/s), so it takes a long time. In order to improve the exposure efficiency of the lithography machine, a silicon wafer table rotation exposure device for the lithography machine described in the utility model with a simple structure transfers the exposure preparation work such as leveling, focusing and alignment to the silicon wafer stage of the pretreatment station. On the wafer stage, and work independently with the wafer stage of the exposure station at the same time, thus greatly shortening the working time of the silicon wafer on the exposure wafer stage.

The wafer platform double exchange device is shown in Figure 3, the device includes a wafer platform 1 running in the pretreatment station and a wafer platform 1 running in the exposure station, the two wafers The stage 1 is set on a base 11 and is suspended on the surface of the base 11 through an air bearing. The air bearing is arranged on the bottom surface of the wafer stage 1 to balance the gravity of the wafer stage 1 and suspend the wafer stage 1 on the base 11 . The upper surface of the abutment 11 is used as an air bearing surface, which requires a higher flatness. The air bearing only plays the role of balancing the gravity of the silicon wafer stage 1 , and the movement of the silicon wafer stage 1 on the upper surface of the base 11 is realized by pushing or pulling the cross rail driving unit 4 .

The wafer stage 1 is driven by two cross rail drive units 4 , and each cross rail drive unit 4 is composed of an X-direction linear motor 5 , a Y-direction linear motor 7 and a push rod 8 . A linear motor consists of a stator and a mover. The stator of the X-direction linear motor 5 is installed in the edge groove of the base 11 , and the mover is located at the bottom of the lower layer of the cross rail drive unit 4 . The Y-direction linear motor 7 is stacked with the X-direction linear motor 5 and is orthogonal to the X-direction linear motor 5 . Its stator is located at the bottom of the upper layer of the cross rail drive unit 4, and the mover is installed in the push rod 8 used to push the movement of the silicon wafer stage. The cross rail driving unit 4 is disposed on two opposite edges of the base 11 .

The cross rail driving unit 4 and the wafer stage 1 are sucked by a vacuum bearing, and the vacuum bearing is arranged on the side of the push rod 8 and the wafer stage 1 . Unless it needs to be exchanged, the push rod 8 and the wafer stage 1 are always sucked together, and under the action of the cross rail drive unit 4 X-direction linear motor 5 and Y-direction linear motor 7, the wafer stage 1 is driven to move in the X direction or Y direction in a large range. sports.

When exchanging, the air source of the vacuum bearing is cut off, and the push rod 8 and the wafer stage 1 are loosened.

The process of exchanging two silicon wafer stages is shown in Fig. 8 . After the wafer stage 1 completes exposure preparations such as leveling, focusing, and alignment, the wafer stage 1 moves to the side-by-side position in the middle of the base 11. When the space is released, the cross rail drive unit 4 moves to the side of the other wafer stage 1, and the two are sucked again by the vacuum bearing, thereby driving the movement of the other wafer stage 1 to complete the two-stage exchange.

Claims (1)

1. A double-stage exchanging device for a lithography machine silicon wafer stage using a cross guide rail, the device contains a silicon wafer stage (1) operating at a pretreatment station and a silicon wafer stage (1) operating at an exposure station, so The two wafer stages described above are arranged on a base (11), and are suspended on the surface of the base through an air bearing, and are characterized in that: the device adopts two cross rail drive units (4), which are respectively arranged on the base (11) On the edges of the opposite sides, each cross rail drive unit (4) includes an X-direction linear motor (5), a Y-direction linear motor (7) and a push rod (8), and the stator of the X-direction linear motor (5) Installed in the groove on the edge of the abutment, the mover is installed on the lower bottom of the cross guide rail drive unit; the Y-direction linear motor (7) and the X-direction linear motor (5) are stacked, and are arranged with the X-direction linear motor (5) Orthogonal; the cross rail drive unit and the wafer stage are sucked by a vacuum bearing, and the vacuum bearing is arranged on the side of the push rod and the wafer stage.

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