JP2780265B2 - Pattern formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] Regarding a pattern forming method, another pattern is formed on a substrate with an accurate size, shape, and position regardless of the size of a step existing on the substrate. The object of the present invention is to provide a pattern forming method capable of performing the following steps. In forming another pattern on a patterned substrate, an index region having a flat upper surface having the same height as the another pattern is provided in advance. After focusing using the index area, exposure, development, etching, and resist removal are performed.

[Industrial applications]

 The present invention relates to a pattern forming method.

[Conventional technology]

In a pattern forming method using a photographing exposure apparatus or the like, it is frequently performed to form another pattern on a substrate on which a pattern has already been formed.

For example, a semiconductor device is generally manufactured by forming a multilayer pattern by photolithography.

In order to print a device pattern on a resist layer on a substrate, it is necessary to focus (focus) a projection exposure apparatus to clearly form a pattern image on the surface of the resist layer. Therefore, the projection exposure apparatus is designed to have a considerably deep depth of focus.

However, when the size of the step of the pattern existing on the substrate exceeds this depth of focus, a necessary pattern image is not clearly formed, and when exposed in such an out-of-focus (out-of-focus) state, development and etching are performed. , And the device pattern obtained by removing the resist, the exact dimensions, shape,
There was a problem that it was not formed at the position.

[Problems to be solved by the invention]

The present invention provides a pattern forming method capable of forming another pattern with accurate dimensions, shape, and position on a substrate regardless of the size of the step of the pattern existing on the substrate. Aim.

[Means for solving the problem]

According to the present invention, in forming another pattern on a patterned substrate according to the present invention, an index region having a flat upper surface having the same height as the another pattern is provided in advance, After focusing using the area,
This is achieved by a pattern forming method characterized by performing exposure, development, etching, and resist removal.

The pattern forming method of the present invention is extremely advantageous when applied to pattern formation of a semiconductor device.

The timing for providing the index region is an appropriate stage before exposure for a pattern to be formed.

For example, simultaneously with the previously formed device pattern (pre-existing pattern) (that is, by using the material of the layer of this device pattern), an index pattern having a shape defining the index region is formed, and then another device pattern is formed. When a layer of the substance forming the (subsequent pattern) is formed, the surface height of this layer is equal on the pre-existing pattern and on the index pattern.
Therefore, the layers formed on both of them by the same process have the same height in principle. Therefore, when forming a subsequent pattern on top of a pre-existing pattern,
Instead of focusing on the resist layer above the pre-existing pattern, the resist layer above the index pattern (index area)
You can focus with. Conversely, when a succeeding pattern is to be formed at the bottom of a valley between the pre-existing patterns, if the index region is provided at the same height as the pre-existing pattern (the bottom of the pre-existing pattern), the resist is formed in the same manner as described above. Focus can be achieved in the index area of the layer.

The area of the index region may be at least approximately equal to the diameter of the laser beam or the like used for the focus operation. Usually, the focusing operation is performed using a helium neon laser having a diameter of about 100 μm or the like. In that case, it is sufficient that the area of the index region is about 100 μm × about 100 μm.

(Operation)

According to the pattern forming method of the present invention, since the focus is performed using the index region provided in advance at the same height as the pattern to be formed, the necessary pattern is sharp regardless of the size of the step of the existing pattern. Therefore, a pattern can be formed with accurate dimensions, shapes, and positions.

Example 1 According to the present invention, another pattern was formed on a patterned Si substrate according to the procedure shown in FIGS. 1 (a) to 1 (g).

In this embodiment, a device pattern 20 was formed as shown in FIG. 1C, and another device pattern P was formed on the device pattern 20 as shown in FIG. 1G.

First, FIG. 1A shows that an SiO ₂ insulating film 2 is formed on a Si substrate, a negative resist layer 3 is formed thereon, and then a device pattern 4 and an index pattern 4 ′ are formed on the resist layer 3.
Shows the baked state. This is developed and etched (FIG. 1 (b)), the resist is removed, and the SiO ₂ device pattern 20 and the SiO ₂ index pattern 20 '(area: about 100 μm)
× 100 μm) (FIG. 1 (c)). On top of this, A
An l layer 5 (FIG. 1 (d)) and a negative resist layer 6 (FIG. 1 (e)) were further formed. Due to the formation of the index pattern 20 ', the Al layer formed thereon has the same height as the device region P' which will later become the Al device pattern P (FIG. 1 (g)), that is, An Al index region PX having the same height as the device pattern P is formed. The level relationship between the Al device pattern P ′ and the Al index region PX is maintained also in the negative resist layer 6 (FIG. 1E) formed thereon, and the device pattern of the resist layer is maintained. An index region RX of the resist layer having the same height as the region R is formed.

In this state (FIG. 1 (e)), the laser beam for focusing (diameter: about 100 μm) is focused on the index region RX, and then the device pattern 7 is focused on the device pattern region R (FIG. 1 (f)). Was baked.

This was developed, etched, and the resist was removed to form a device pattern P shown in FIG. 1 (g).

Example 2 In accordance with the present invention, another pattern was formed on a patterned Si substrate according to the procedure shown in FIGS. 2 (a) to 2 (g).

In the present embodiment, a device pattern 120 is formed as shown in FIG. 2C, and another device pattern Q is formed at a valley bottom between the device patterns 120 as shown in FIG. 2G. .

First, FIG. 2A shows that an SiO ₂ insulating film 12 is formed on a Si substrate 11.
After forming a negative resist layer 13 thereon,
5 shows a state where the device pattern 14 is baked on the resist layer 13. This is developed and etched (FIG. 2 (b)), the resist is removed, and the SiO ₂ device pattern 12 is removed.
0 was formed (FIG. 2 (c)). An Al layer 15 (second
(FIG. 2 (d)) and a negative resist layer 16 (FIG. 2 (e)).
Was formed. The Al index region QX and the resist index region SX have the same height as the Al device pattern region Q ′ (Al device pattern Q) and the resist device pattern region S, respectively. In this case, the index area is maintained in the same area as the index pattern 20 'of the first embodiment in a state where nothing is formed at the stage of FIG. 2 (c).

After the formation of the resist layer 16 (FIG. 2 (e)), the index region SX of the resist is focused by applying a focusing laser beam, and then the device pattern 17 (FIG. 2 (f)) is Baked.

This was developed, etched, and the resist was removed to form a device pattern Q shown in FIG. 2 (g).

[Effects of the Invention] As described above, the pattern forming method of the present invention includes:
Since out-of-focus (out-of-focus) at the time of pattern printing is eliminated in principle, any other pattern can be formed with accurate dimensions, shape, and position on a substrate on which a pattern including any step is formed. Extremely high pattern formation accuracy can be realized. The present invention is particularly effective in the manufacture of semiconductor devices.

[Brief description of the drawings]

1 and 2 are sectional views showing an example of a procedure for forming a pattern according to the present invention. 1,11 ... Si substrate, 2,12 ... SiO ₂ insulating film, 3,6,13,16 ... Resist layer, 20,120, P, Q ... Device pattern, PX, SX ... Indicator area of resist layer .

Claims (1)

(57) [Claims] When forming another pattern on a substrate on which a pattern has been formed, an index region having a flat upper surface having the same height as the another pattern is provided in advance, and focusing is performed using the index region. From, exposure, development, etching,
And a resist forming step.