JPH10242020A - X-ray exposure apparatus and x-ray exposure mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately align a mask and a wafer even if the wafer is deformed and improve exposure accuracy. SOLUTION: The apparatus is constituted so that an X-ray exposure mask 10 and a wafer 20 are faced to each other via a minute gap to transfer a pattern of the mask 10 onto the wafer 20. A frame 13 of the mask 10 is formed of a conductive material to be heated with electric power. Moreover, the wafer 20 is also constituted to be heated with electric power. A temperature difference is given rise to between the wafer 20 and mask frame 13, so that the pattern on the mask 10 can be registered to a lower pattern on the wafer 20 with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray exposure technique, and more particularly to an X-ray exposure apparatus and an X-ray exposure mask in which an alignment method of a mask / wafer is improved.

[0002]

2. Description of the Related Art As a technique for transferring an LSI pattern, a reduction exposure apparatus utilizing light in a visible region has been conventionally used. In this apparatus, C is placed on a glass mask substrate.
An r thin film is formed, a resist is applied, a 4-5-fold original of the actual pattern on the wafer is drawn by an electron beam drawing apparatus or the like, and then a mask pattern is formed through development and etching steps. The reduction exposure apparatus forms a reduction optical system using elements such as a lens and a reflecting mirror, and transfers a pattern on a mask onto a wafer. At this time, it is an important performance required for the exposure apparatus to align the pattern on the mask with the lower layer pattern on the wafer with high accuracy.

A pattern on a wafer may be slightly deformed by various processing processes for imparting an LSI function. In the reduction exposure apparatus, the alignment between the mask and the wafer lower layer pattern is improved by adjusting the reduction ratio as needed.

With the miniaturization of LSI, higher resolution is required for an exposure apparatus. In a conventional reduction exposure apparatus, high accuracy has been realized by shortening the wavelength of light to be used and by giving phase information to light transmitted through a mask (use of a so-called phase shift mask). However, even if such a means is used, it is extremely difficult to resolve the pattern with a sufficient depth of focus and a sufficient irradiation dose when a fine pattern of 0.15 μm or less is targeted.

An X-ray exposure apparatus is a means for overcoming this situation. The mask used for X-ray exposure is an X-ray transparent thin film (SiN or SiC film of about 1 to 2 μm is used)
On top, a heavy metal film (0.3-0.5 μm
W, Ta, etc.), and a pattern is formed using an electron beam drawing apparatus or the like in the same manner as the mask for light exposure light.
The X-ray transmitting thin film is held on a substrate frame made of Si or the like, and the substrate frame is generally fixed to a strong frame.

[0006] Since X-rays cannot utilize a so-called lens function, a mask and a wafer are opposed to each other at an extremely small interval (about 10 to 30 µm) during exposure, and the exposure is performed 1: 1.
Is generally performed. That is, when transferring the pattern on the mask onto the wafer, the pattern does not pass through the reduction optical system. Therefore, when a subtle deformation occurs in a processing process for imparting an LSI function to a pattern on a wafer, it is necessary to correct the pattern of the mask itself.

[0007] If the degree of deformation of the wafer is constant and known in advance, it is possible to correct the pattern when drawing the pattern on the X-ray absorber, but it takes time to grasp the situation, especially in the development stage of the process. , With difficulties. Since the necessary correction amount is on the order of 1 ppm, it has been found that the pattern can be deformed by applying an expanding force or a tightening force to the mask frame. However, it is extremely difficult to attach an X-ray mask having a film structure to an exposure apparatus in a state of almost no distortion and apply a force to the mask to give a desired deformation.

[0008]

As described above, in the conventional X-ray exposure apparatus, since the mask and the wafer are opposed to each other by 1: 1 without using an optical system, the wafer is deformed and the It is difficult to correct this misalignment.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to enable accurate alignment between a mask and a wafer even when the wafer is deformed, thereby improving the exposure accuracy. An object of the present invention is to provide an X-ray exposure apparatus and an X-ray exposure mask that can contribute to improvement.

[0010]

[Means for Solving the Problems]

(Structure) In order to solve the above problem, the present invention employs the following structure. (1) An X-ray exposure apparatus in which a mask for X-ray exposure, in which a thin film mask body is held by a frame, and a wafer are opposed through a minute gap, and a pattern formed on the mask is transferred onto the wafer, The method is characterized in that a temperature difference is applied between the wafer and the mask frame by using a conductive material and electrically heating the mask frame.

(1-1) Electric heating of the wafer if necessary. (1-2) Flowing a temperature-controlled gas into the space where the mask and wafer face each other. (1-3) A part of the thin film mask body is set back from the facing wafer surface except for the vicinity of the X-ray transmitting portion. (1-4) There are means for detecting alignment signals of the mask and the wafer at two locations in one direction, and after performing alignment of one of the two locations, the other alignment signal has a predetermined size. To control the current flowing through the mask frame to satisfy the accuracy.

(2) A thin film mask body supporting an X-ray transmitting thin film having a device pattern formed by an X-ray absorber and supported by a thin film support frame is opposed to a wafer via a minute gap.
An X-ray exposure apparatus for transferring a pattern formed on a mask onto a wafer is characterized in that a temperature difference is imparted between the wafer and the thin film support frame by electrically heating the thin film support frame.

(2-1) Electric heating of the wafer as required. (2-2) Flowing a temperature-controlled gas into the space where the mask and wafer face each other. (2-3) The thin-film support frame is configured to recede from the confronting wafer surface except for the vicinity of the X-ray transmitting portion. (2-4) Means for detecting alignment signals of the mask and the wafer at two locations in one direction, and performing alignment of one of the two locations, and the other alignment signal having a predetermined size To control the current flowing through the thin film support frame so as to satisfy the accuracy.

(3) An X-ray exposure apparatus for transferring an X-ray exposure mask holding a thin film mask body by a frame and a wafer through a minute gap and transferring a pattern formed on the mask onto the wafer. Means for giving a predetermined temperature difference between the frame and the wafer, and means for flowing a gas whose temperature is controlled into a space where the mask and the wafer are opposed to each other.

(3-1) A part of the thin film mask body is set back from the confronting wafer surface except for the vicinity of the X-ray transmitting portion. (3-2) Energizing and heating at least one of the mask frame and the wafer to impart a predetermined temperature difference between the mask frame and the wafer. (3-3) To provide a predetermined temperature difference between the mask frame and the wafer, a heating lamp for heating the mask frame is provided on the side opposite to the wafer with respect to the mask. (3-4) There is a means for detecting alignment signals of the mask and the wafer at two locations in one direction, and after performing alignment of one of the two locations, the other alignment signal has a predetermined size. To control the temperature difference between the mask frame and the wafer to meet the accuracy. (3-5) There are means for detecting alignment signals of the mask and the wafer at two locations in one direction, and after performing alignment of both at one of the two locations, the other alignment signal has a predetermined size. To control the power of the heating lamp to meet the accuracy.

(4) An X-ray exposure apparatus for causing an X-ray exposure mask holding a thin film mask body by a mask frame to face a wafer through a minute gap and transferring a pattern formed on the mask onto the wafer. A heating lamp is provided on a side of the mask not facing the wafer.

(5) An X-ray exposure mask comprising a thin-film mask having a pattern of an X-ray absorber formed on an X-ray transmitting thin film and a frame for holding the thin-film mask. Characterized in that it is made of a material having

(6) In an X-ray exposure apparatus for transferring an X-ray exposure mask holding a thin film mask body by a frame and a wafer through a minute gap and transferring a pattern formed on the mask onto the wafer, Means for providing a predetermined temperature difference between the frame and the wafer, and a flow path through which a temperature-controlled medium is flown is provided in at least one of the mask stage and the wafer stage.

(6-1) Flowing a temperature-controlled gas into a space where the mask and the wafer face each other. (6-2) A part of the thin film mask body is set back from the facing wafer surface except for the vicinity of the X-ray transmitting portion. (6-3) Flow a gas whose temperature is controlled in the non-confronting space to the mask wafer as necessary. (6-4) At least one of the mask frame and the wafer is electrically heated in order to provide a predetermined temperature difference between the mask frame and the wafer. (6-5) To provide a predetermined temperature difference between the mask frame and the wafer, a heating lamp for heating the mask frame is provided on the side opposite to the wafer with respect to the mask. (6-6) There is a means for detecting alignment signals of the mask and the wafer at two locations in one direction, and after performing alignment of both at one of the two locations, the other alignment signal has a predetermined size. To control the temperature difference between the mask frame and the wafer to meet the accuracy. (6-7) There is means for detecting alignment signals of the mask and the wafer at two locations in one direction, and after performing alignment of both at one of the two locations, the other alignment signal has a predetermined size. To control the power of the heating lamp to meet the accuracy.

(Function) The basic principle of the present invention is that the mask pattern formed on the X-ray transparent thin film has the highest rigidity among the mask structures since the X-ray exposure mask is a thin film structure. Focusing on following the deformation of the frame, if the mask pattern needs to be deformed in the enlargement direction, the temperature of the mask frame rises.If the lower layer pattern on the wafer needs to be deformed in the enlargement direction, the wafer must be deformed. The purpose is to give a necessary amount of deformation by increasing the temperature.

According to the present invention, the mask and the wafer can be deformed independently by controlling the temperature of the mask frame and the wafer independently by applying electric current to the mask frame and the wafer. Therefore, the coordinates of the coordinates of the lower layer pattern and the mask pattern on the wafer can be made to coincide with each other to a necessary degree, and high-precision alignment can be performed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. 1 to 3 illustrate an X-ray exposure apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a mask and a wafer stage, FIG. 2 is a cross-sectional view of a portion where the mask and the wafer face each other with a small gap, and FIG. 3 is a schematic diagram showing an arrangement of alignment marks for aligning the mask and the wafer.

The X-ray transparent thin film 11 having a device pattern formed of an X-ray absorber is a Si substrate frame (thin film support frame).
The Si substrate frame 12 is further fixed to a Si reinforcing frame 13. Here, a thin film mask body is composed of the X-ray transmitting thin film 11 and the substrate frame 12,
X-ray exposure mask 1 from thin film mask body and frame 13
0 is configured. The mask frame 13 is fixed to the mask stage 14 with no distortion by three-point support. This fulcrum also serves as an electrode, and can apply a voltage so that substantially the same current flows between the three fulcrums.

The mask stage 4 is provided with a flow path 15 through which a medium having a temperature determined at the entrance can flow in order to take a starting point of the mask temperature as required. Further, in order to secure a base point of the temperature, a gas having a temperature determined by the blowing unit 16 is circulated as necessary. The circulating gas is designed so that it hardly leaks into the space where the wafer 20 is placed.

Si substrate frame 1 supporting X-ray transmitting thin film 11
As shown in FIG. 2, as shown in FIG. 2, the wafer 2 is processed so as to recede from the facing wafer surface except in the very vicinity of the X-ray transmitting portion, and is defined by the blowing portion 18 in a space where the wafer and the mask face each other as necessary. The gas of the specified temperature can be flowed. Note that the gas at the determined temperature functions as thermal insulation between the wafer and the mask.

The wafer 20 is fixed to a wafer stage 21 by a vacuum chuck. The wafer stage 21 is provided with electrodes 22 and, if necessary, a flow path 23 through which a medium having a temperature determined at the entrance can flow in order to take the base point of the temperature of the wafer 20. Then, the wafer 20
A required voltage can be applied through the electrode 22.

As shown in FIG. 3, the mask 10 and the wafer 20 are provided with alignment marks 31 at two locations in one direction along the periphery of the exposure area. Mask 10
If the pattern information and the coordinate information of the lower layer pattern on the wafer 20 are unknown, first, alignment is performed on one of the alignment marks 31, and then the mask frame 13 is adjusted so that desired alignment accuracy is obtained at the other mark position. Alternatively, the voltage applied to the wafer is adjusted.

More specifically, the mask 10 and the wafer 20
Means for detecting both alignment signals at two locations in one direction, and performing alignment of the two at one of the two locations so that the other alignment signal satisfies predetermined dimensional accuracy. Alternatively, by controlling the value of the current flowing through the wafer 20, accurate alignment between the mask 10 and the wafer 20 becomes possible.

As means for heating the mask frame 13, a heating lamp 24 may be provided on the side of the mask 10 opposite to the wafer 20. Also in this case, the lamp power may be controlled based on the output of the alignment signal detecting means so that the two alignment signals give a matching signal equal to or less than the reference value.

As described above, according to the present embodiment, the mask 1
If there is a slight inconsistency between the position coordinates of the pattern on the wafer 0 and the pattern on the wafer 20, the mask frame 1
By giving an appropriate temperature difference between the wafer 3 and the wafer 20, the position coordinate systems of the two can be matched within a necessary range. Therefore, even if the wafer 20 is deformed, the mask 10
And the wafer 20 can be aligned with high accuracy, which can contribute to an improvement in exposure accuracy.

The present invention is not limited to the above embodiment. In the embodiment, both the mask frame and the wafer are configured to be energized and heated, but only one of them may be configured to be energized and heated. The temperature-controlled gas flowing between the mask and the wafer or on the back side of the mask can be omitted as necessary.

The substrate frame supporting a thin film such as X-rays is S
A conductive material such as an i-wafer may be configured to heat the substrate frame instead of heating the mask frame. In addition, various modifications can be made without departing from the scope of the present invention.

[0033]

As described above, according to the present invention, the mask and the wafer can be independently deformed by independently controlling the temperature of the mask frame and the wafer by conducting heating of the mask frame and the like. Even if the deformation occurs, the alignment between the mask and the wafer can be performed with high accuracy, and it is possible to contribute to the improvement of the exposure accuracy by the X-ray exposure apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an X-ray exposure apparatus according to one embodiment of the present invention.

FIG. 2 is a sectional view of a portion where the mask and the wafer face each other in the embodiment.

FIG. 3 is a schematic diagram showing the arrangement of alignment marks in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... X-ray exposure mask 11 ... X-ray transmission thin film 12 ... Si substrate frame 13 ... mask frame 14 ... mask stage 15, 23 ... medium flow path 16, 18 ... constant temperature gas blowing part 20 ... wafer 21 ... wafer stage 22 ... Electrode 30 Exposure area 31 Mark

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/30 531M

Claims (5)

[Claims] 1. An X-ray exposure apparatus for transferring an X-ray exposure mask holding a thin film mask body by a mask frame and a wafer via a minute gap and transferring a pattern formed on the mask onto the wafer. An X-ray exposure apparatus, wherein a temperature difference is applied between the wafer and the mask frame by using a conductive material for the frame and electrically heating the mask frame. 2. A thin film mask body in which an X-ray transmitting thin film having a device pattern formed by an X-ray absorber is supported by a thin film support frame, and a wafer are opposed to each other through a minute gap. An X-ray exposure apparatus for transferring images onto an upper surface, wherein a temperature difference is applied between the wafer and the thin-film support frame by electrically heating the thin-film support frame. 3. An X-ray exposure mask holding a thin film mask body by a frame and a wafer are opposed to each other through a minute gap.
An X-ray exposure apparatus for transferring a pattern formed on a mask onto a wafer, comprising: means for imparting a predetermined temperature difference between the frame of the mask and the wafer; and a gas whose temperature is controlled in a space where the mask and the wafer face each other. An X-ray exposure apparatus comprising: a flowing unit. 4. An X-ray exposure apparatus for transferring an X-ray exposure mask holding a thin film mask body by a mask frame and a wafer via a minute gap and transferring a pattern formed on the mask onto the wafer. An X-ray exposure apparatus comprising a heating lamp provided on a side not facing the wafer. 5. A thin film mask having a pattern of an X-ray absorber formed on an X-ray transmitting thin film, and a frame for holding the thin film mask, wherein the frame is formed of a conductive material. An X-ray exposure mask, characterized in that the mask is configured to be energized.