JPH023044A - Exposure method - Google Patents

Abstract

PURPOSE:To perform highly accurate exposure by a contact system by employing a photomask possessing a step of height similar to a semiconductor substrate when a photolithographic stage where the semiconductor substrate possessing a step is exposed. CONSTITUTION:When the photolithographic stage where the semiconductor substrate 10 possessing the step is exposed, the photomask 20 possessing the step similar to the substrate is employed. The height h1 of a higher plane 13 made by a mesa part 12 is 2mum from the lower plane 11 of the substrate 10, and the width W1 of the mesa part is 30mum. The height h2 of the lower plane 2 made by the mesa part 21 of the photomask 20 is set almost the same as the height of the mesa part 12 on the side of the substrate 10, and mask metals 25 and 26 are applied to the lower and higher planes 23 and 26 of the photomask 20, respectively. Consequently, the semiconductor substrate 10 possessing a step can be exposed accurately by a contact system.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an exposure method in (e) IJ sogerafue process during the manufacture of semiconductor devices.

(B) Conventional technology In this type of exposure method, the contact method has been known for a long time.

The contact method is 1% way. It has the advantage of high throughput because pattern exposure is performed on the entire surface at once, but if there are steps on the exposed surface, high exposure resolution cannot be achieved because the photoscreen and the exposed surface cannot be in close contact. .

I/C Problems to be Solved by the Invention The present invention aims to provide a method that can accurately expose a semiconductor substrate having a step using a contact method.

B) Means for Solving the Problems The exposure method of the present invention includes the use of a photomask having a step approximately the same height as the step when exposing a semiconductor substrate having a step in a photolithography process. Features.

(E) Function According to the present invention, the steps on the exposed surface and the steps on the photomask mesh with each other, and the photomask comes into close contact with the exposed surface.

(F) Embodiment To explain the exposure method 87 of the embodiment of the present invention, this field piece, as shown in FIG. 3, is a semiconductor substrate tfz! having a low-level surface 111 and a high-level surface αJ formed by the mesa portion α2. V-shaped pI (+4
1 (to), the exposure method of the present invention is applied.

Such a V-groove is used to simultaneously accommodate two types of semiconductor laser diodes in the same base ff1Ilα. That is, since the surface of the substrate 1101 shown in FIG. 6 is successively liquid-phase epitaxially improved with well-known Rade structural layers such as a first cladding layer, an active layer, and a second cladding layer, the thickness of the active layer is at a high level [ It is small above 10aJ, and the lower surface (
! l) Becomes larger at the top. The former active layer enables high-output laser oscillation i1, and the latter enables low-noise laser oscillation.

In the process shown in FIG.
Three tfitlα are prepared, and a photoresist film 0υ is deposited on the surface of the substrate. High surface rJ31 created by mesa part
The height hl is 2 μm with respect to the lower surface (11) of the substrate, and the width Wt of the mesa portion is 60 μm.

In the step shown in FIG. 1, a photomask is further prepared. The mask includes a glass mask substrate having a downward facing mesa. The height hl of the lower lower surface (toward) formed by the mesa part @ is set equal to the height K of the mesa part α2 on the substrate 11α side, and in this case, the height hl of the lower lower surface (toward) of the mask substrate □□□ is set equal to y. The photomask (A) further includes a mask metal (to) ridge made of cr, and these metals correspond to the lower surface +111 and the higher surface a3 of the base ffz +lα, respectively, and the lower surface of the photomask ridge is 2 μm. - Mask metal (2I5
) The appropriate width W1 of the wire is about 2 μm.

In step 21aK, the substrate 1101 in FIG.
Exposure is carried out by bringing the lower surface of a photomask into contact with the surface of the window, and then only the unexposed portions are removed by developing the photoresist film αυ, leaving the window fin (c). In this process, the contact between the substrate and the (H) and (W) steps was made despite the fact that there is a step on the substrate side due to the mesa part O2.
There is also a step on the photomask side due to the downward facing mesa part (of the same height), so the f! M-suitable.

Note that the width of the window pattern formed in the photoresist film 061 is 1
．． It is about 2 μm.

In the step shown in FIG. 6, the window (
27IQ811: As a result, a 7-figure groove (14
1CLf9 is formed simultaneously. A phosphoric acid-based etchant is used, and the opening width and depth of each V-shaped groove obtained are approximately 22 μm and 1.5 μm, respectively.

The present invention can also be applied to a substrate made of the same material as the GaA4 plate used in the above actual example, and exposure can be performed with high precision using the contact method.

[Brief explanation of the drawing]

FIGS. 1 to 6 are cross-sectional views showing steps of an embodiment of the present invention. 11α-semiconductor substrate, α2-mesa part, -1 photoresist film, -1 photomask, ? B-Downward mesa part, (C) (B)-Risk metal.

Claims (1)

[Claims] (1) An exposure method characterized by using a photomask having a step approximately the same height as the step when exposing a semiconductor substrate having a step in a photolithography process.