JP2638561B2 - Mask formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a size of 0.2 .mu.m to 0.1 .mu.m.
The present invention relates to a method for manufacturing a semiconductor or a superconducting element having an ultrafine pattern of μm or less, and particularly to a pattern forming method suitable for these elements.

[0002]

2. Description of the Related Art In the manufacture of quantum effect devices such as permeable base transistors (PBT) or various quantum well array devices, super-matrix solid-state oscillators, lateral superlattice FETs, resonance tunneling effect devices, etc. It is necessary to produce a set of fine lattice, stripe, or point patterns. Many of these devices aim at the quantum effect, and the pattern period is desired to be about 0.1 μm or less.

[0003] Conventionally, these elements are EB (electron beam).
Alternatively, it has been manufactured by direct writing of FIB (focused ion beam). Regarding the fabrication of quantum effect devices using EB, for example, Solid State Technology,
October 1985, pages 125 to 129 (So
lid State Technology / Octover, 1985, pp125
-129).

On the other hand, the limit resolution of photolithography by the reduced projection light method is proportional to the exposure wavelength and inversely proportional to the numerical aperture of the reduction lens. At present, about 0.3 μm is achieved by using an excimer laser (KrF laser, wavelength 248 nm) and a reducing lens having a numerical aperture of 0.4 to 0.5. The numerical aperture is 0.5
Reflective optical system and ArF excimer laser (wavelength 193n)
There is an example in which 0.13 μm is resolved using m). (Journal of Vacuum Science and Technology B5 (1), 1987, January / February, No.3
Pages 89 to 390 (J. Vac. Sci. Technol. B5 (1),
Jan / Feb 1987, pp 389-390)).

Incidentally, there is a phase shift method as a method for improving the resolution limit in the reduced projection exposure method. According to the phase shift method, the resolution limit is improved about twice as much as the case where the exposure method using a normal transmission mask is used. Therefore, according to this, it is possible to form a fine pattern of 0.15 μm to 0.1 μm or less. This phase shift method does not require a special exposure apparatus, and can be performed only by changing a conventional transmission mask (reticle) to a phase shift mask (reticle) in a normal reduction projection exposure apparatus.
Regarding the phase shift method, see, for example, IEE, Transaction on Electron Devices, Eday 31, Number 6 (1984), pp. 753 to 763 (IEEE, Trans. Electron Devices, Vo.
1, DE-31, No. 6 (1984), pp. 753-76.
3).

Another method for forming a pattern below the resolution limit of the reduced projection exposure method using light is a holography method. This holography method requires a special exposure apparatus, and the pattern is a wafer. Cannot be aligned with the pattern already existing on the substrate. Such a holography method is discussed, for example, in the fall of 1984, in the 45th Annual Meeting of the Japan Society of Applied Physics, Preliminary Lecture Book, p. 242.

[0007]

It takes a lot of time to draw and form an ultra-fine pattern using the above-described EB and FIB.
There was a problem that the economy was poor.

On the other hand, the limit resolution of the reduced projection exposure method is P
It is very difficult to form a pattern of 0.1 μm or less required for BTs, quantum effect devices and the like.

This can be achieved by using the phase shift method. However, the weak point of the phase shift method is that it is difficult to deal with a complicated mask pattern such as an actual LSI pattern. The phase shift method uses a simple line-and-space pattern (hereinafter, L /
This is a very effective technique for producing S), lattice patterns, point patterns, and the like.

It is an object of the present invention to solve the above-mentioned problems in forming a pattern of a device having an extremely fine pattern, and to provide a simple and high-throughput method for forming a fine element excellent in economy.

[0011]

The object of the present invention is to provide a phase shift mask for exposing an extremely fine pattern area (for example, a grid portion of a PBT) of the device when forming the pattern of the device, and to provide another pattern area. Is achieved by applying a reduced projection exposure using a normal transmission mask.

[0012]

The pattern of the device to which the present invention is applied is divided into two regions: a dense region of an extremely fine pattern having a simple repetitive structure, and a circuit region having a relatively complicated structure such as control electrodes and wirings. These two regions may coexist in the same layer in the device manufacturing process, or may exist as separate layers.

The former ultrafine pattern region has a simple L / S,
A set of point-like patterns and lattice-like patterns with dimensions of 0.1μ
m or less, and its shape is relatively simple. Pattern formation in this region can be performed by a reduced projection exposure method using a phase shift mask (reticle).

On the other hand, the size of the pattern in the latter circuit area is larger than that of the former, and the conventional transmission mask (reticle) is used.
It is suitable to form by a reduced projection exposure method using.

When exposing the above two regions separately,
It is necessary to align both. Usually the alignment accuracy must be kept at least below half of the minimum dimension.
Therefore, an alignment accuracy of 0.05 μm or less is required for a 0.1 μm pattern, but there is no exposure apparatus having such an accuracy at present. However, the alignment accuracy between the two regions in the present invention is sufficient if the value is assured by a normal exposure apparatus. The reason is that the micropatterns in the device targeted by the present invention function as a whole, so that the relative positions of the micropattern region and the circuit pattern region need to be within a predetermined range, but each of the micropatterns Is not required to be so precise.

When the two regions are mixed in the same layer, the phase shift mask region and the transmission type mask region can be mixed on one mask. If this is used, the extremely fine pattern region and the circuit pattern region can be simultaneously exposed with one mask. However, in this case,
There is a risk that poor resolution may occur at the connection between the two regions. That is, when two translucent portions having different phases come into contact with each other, the light intensity is reduced here due to interference. Such pattern arrangement must be avoided.

According to the present invention, since the exposure of the pattern is performed by the reduced projection exposure method, it can be completed in a much shorter time than the method of direct writing of the electron beam and the focused ion beam.

Further, according to the present invention, it is possible to form an extremely fine pattern at a desired position in an exposure field without requiring a special exposure apparatus, which is more advantageous than the holographic method.

[0019]

【Example】

(Embodiment 1) Hereinafter, an embodiment of a method for manufacturing a PBT using the present invention will be described.

First, Ga formed on the carrier collecting electrode layer
A W thin film was further formed on an As substrate, and a so-called three-layer resist having a three-layer structure of a lower organic film / intermediate inorganic film / upper resist film was formed thereon. PMMA (polymethyl methacrylate sheet) was used as the upper resist. Next, exposure was performed using a phase shift reticle having only a very small L / S in the control electrode region of the PBT as shown in FIG. Fine L / S of phase shift reticle
Adjacent to each other, the phases of the illumination light
It is arranged to be inverted by 0 °. Next, the reticle was replaced with a transmissive reticle having a control electrode peripheral circuit pattern as shown in FIG.

Exposure to the two regions is performed continuously while only the reticle is changed while the substrate is fixed on the substrate stage of the exposure apparatus. It goes without saying that a positioning operation is performed in each exposure. Alternatively, the order of exposure for the two regions is not particularly defined. The light source of the exposure apparatus used was a KrF excimer laser, and the numerical aperture of the optical system was 0.6. The time required for exposure of each of the two reticles in one exposure field was about 5 seconds. On the other hand, when the same pattern was exposed using an electron beam lithography apparatus, the time required for the exposure was about 600 seconds.

Next, the upper layer redest is developed,
An upper resist pattern as shown in FIG. 1 (c) was obtained. This was sequentially transferred to the intermediate layer and the lower layer by reactive ion etching. As a result, in the lower organic film, both the L / S pattern having a rectangular cross-sectional shape having a high aspect ratio in the ultrafine control electrode pattern region and the peripheral circuit pattern were obtained.

Using the lower organic layer pattern thus formed as a mask, dry etching of the W film is performed to form a control electrode pattern. After that, GaAs is grown on the control electrode pattern, and the control electrode is buried. The PBT was formed. All the exposures other than the control electrode pattern used a transmission mask. As a result of evaluating the electrical characteristics of the produced PBT, the expected performance was obtained.

FIG. 1 is a schematic plan view for explanation, and does not always show an actual transistor layout. Further, the device structure, substrate material, control electrode material, resist material and process, exposure apparatus, and the like can be used without being limited to those described in the present embodiment.

The exposure process of this embodiment can be applied not only to PBT but also to other devices in which a simple ultrafine L / S pattern and peripheral circuits are mixed, such as a lateral one-dimensional superlattice FET.

(Embodiment 2) In a PBT, since a very fine pattern region and a circuit pattern region are mixed in the same layer (control electrode layer), the phase shift mask region and the transmission type mask region correspond to each of the above regions. A pattern can be formed by a reticle in which is mixed. FIG. 2 shows a mask for this purpose. In Example 1, the shape of the control electrode was a comb shape as shown in FIG. However, in this method, in order to completely separate the phase shift mask region and the transmission mask region, the phase shift mask region (within a dotted line in FIG. 2) is arranged in a complete light shielding portion in the transmission mask region.

(Embodiment 3) An embodiment of a method for manufacturing a super-matrix solid-state oscillation device using the present invention will be described. G
A positive resist PMMA was applied on the aAs substrate, and FIG.
Exposure was performed using a phase shift mask having a set of dot-shaped translucent portions as shown in FIG. Thereafter, development was performed to obtain resist openings corresponding to each of the light transmitting portions in FIG. Each translucent portion of the phase shift mask is arranged (in a checkerboard pattern) so that the phase of the illumination light is alternately inverted by 180 ° in both the upper, lower, left and right directions. The phase shift mask may be provided with a finer light-transmitting portion pattern for phase inversion around each dot-shaped light-transmitting portion shown in FIG.

Next, metallization was carried out, and after depositing metal on the resist and on the substrate at the resist opening, the resist was removed and a metal dot matrix was formed on the substrate by a lift-off method. Subsequently, electrodes and the like were formed to manufacture a super-matrix solid-state oscillation device.

Although the embodiment for manufacturing the solid-state oscillation element has been described here, the resist pattern forming step of this embodiment is performed by using GaAs.
Instead of metallization on the s-substrate, it can be applied to various devices by combining with various other processes. For example, GaAlAs on a GaAs substrate
After the growth of the thin film, pattern formation is performed using a negative resist and the phase shift mask according to the present embodiment.
The resist pattern remains corresponding to each of the dot-shaped light transmitting portions. The quantum well matrix can be formed by performing anisotropic etching of GaAlAs using this as a mask and performing appropriate post-processing. Similarly, application to a lateral FET superlattice, a resonant tunneling effect transistor, or the like is possible.

(Embodiment 4) Another embodiment relating to a method for manufacturing a super-matrix solid-state oscillation device using the present invention will be described.

The positive resist in Example 3 was replaced with a negative resist, and the exposure process was changed as follows. First, a mask A, a mask B, and a mask C as shown in FIG. 4 were prepared. The masks A and B are L / S phase shift masks, and the L / S in each is orthogonal to each other or has a different angle with respect to a reference direction. Using the three masks A, B, and C, the same resist film was overexposed to obtain the same resist pattern as in Example 3. That is, the dot matrix is formed at the overlapping portion of L / S in the masks A and B, and the mask C defines the range of the dot matrix area. According to the present embodiment,
The period of the dot matrix can be made smaller as compared with the third embodiment, and the planar shape of the resist can be made square.

It goes without saying that the pattern type process of this embodiment can be applied to various devices as in the third embodiment.

[0033]

As described above, according to the method of manufacturing a semiconductor or superconductor device according to the present invention, 0.1% in a quantum effect element or the like is used.
In the process of forming a circuit pattern including a micropattern region composed of a pattern having a size of about μm or less, the exposure of the ultrafine pattern region is performed by a reduced projection exposure method using a phase shift method, thereby exposing other circuit patterns. By independently performing each of them by a normal exposure method, the time required for forming the pattern can be significantly reduced, and the cost of the apparatus can be reduced.

This makes it possible to improve the economical efficiency in mass production of the semiconductor / superconductor element. Also,
These effects become more remarkable when the above elements are integrated.

[Brief description of the drawings]

FIG. 1 is a plan view of a mask pattern according to an embodiment of the present invention.

FIG. 2 is a diagram showing that a phase shift mask region is arranged in a light shielding region in a transmission type mask region.

FIG. 3 is a diagram showing a set of dot-shaped light transmitting portions.

FIG. 4 is a plan view of a mask pattern.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshihiko Tanaka 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd. Central Research Laboratory (72) Inventor Taku Oshima 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo Hitachi, Ltd. Central Research Laboratory (56) References JP-A-58-173744 (JP, A) JP-A-62-189468 (JP, A)

Claims (2)

(57) [Claims] A step of decomposing an exposure area of a mask pattern that gives a desired pattern into a first exposure area and a second exposure area; a first mask including the first exposure area and a second exposure area Forming a second mask including at least one of the first mask and the second mask,
A method for forming a mask, comprising: a phase shift mask including a phase shift pattern for inverting the phase of light passing through an adjacent light transmitting portion. 2. The method according to claim 1, wherein the desired pattern coincides with a sum area of a non-exposure area substantially formed by the first mask and a non-exposure area substantially formed by the second mask. 2. The method according to claim 1, wherein the mask is formed.