JPS6216415B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a master mask, which is sometimes used in manufacturing semiconductor integrated circuit devices.

In the manufacturing process of semiconductor integrated circuit devices, photosensitive agents are used as resists for etching and selective plating. The process of selectively diffusing the photosensitive agent or forming desired patterns such as electrodes or wiring is carried out in various steps. A mask is used to form a desired pattern on the photosensitive agent. A mask is usually formed by repeatedly arranging a pattern for one semiconductor integrated circuit device vertically and horizontally on a transparent substrate. 1 for 1 mask
Normally, the patterns for one manufacturing process for one device are arranged in an array, but some patterns are not formed in one part of the array, or other patterns are inserted into the part where no pattern is formed. It may be formed in one piece. To briefly explain the mask manufacturing procedure, first, a master reticle that is usually 10 times the size of the desired pattern is created, and then mastered using an optical machine called a photorepeater (a trademark of MANN Rroducts, a GCA company in the United States). Reticle pattern 1/10
A master mask with patterns arranged vertically and horizontally is obtained by reducing exposure. This master mask is optically exposed to close contact to produce a working mask. Although the above-mentioned master mask may be used in the manufacture of semiconductor integrated circuit devices, a working mask is usually used. Therefore, it is the master mask manufacturing process that obtains the pattern that is repeatedly arranged vertically and horizontally.
When obtaining this master mask, if the pattern to be arranged is for one production process, it can be made with one master reticle, but try to obtain a master mask that inserts patterns for other production processes into the array. If so, a master reticle for the other production processes will also be required. In this way, when manufacturing a master mask containing two or more types of patterns, first set the master reticle for one manufacturing process on a photorepitter, and perform reduction exposure in a preset arrangement on the plate that will become the master mask. do. Next, the master reticle containing the manufacturing process pattern to be inserted is replaced with the previously used master reticle, set on the photorepeater, and subjected to reduction exposure on the master mask again. In this case, since the previously exposed pattern is set to be exposed in an array excluding the areas to be exposed later, the next pattern is set to expose the removed areas. This operation of exchanging the master reticle, setting it on the photorepeater, and reducing exposure onto the master mask can be repeated as many times as necessary for patterns.
The method for manufacturing a master mask including two or more types of patterns has been described above. Considering here, when producing one master mask containing two or more types of patterns, the number of times the master reticle for the number of patterns (N) must be replaced is 1 x N times ^/ sheet = N times, but 1
For example, when producing M master masks, the master reticle must be replaced M times N times ^/ sheet = M.N times. In this way, setting and removing the master reticle from the photorepeater for each pattern exposure causes the generation and adhesion of dust, which is the worst thing to do in the manufacture of semiconductor integrated circuits, and also increases the likelihood of scratches. If a defect occurs due to dust or scratches on the master reticle, a common defect will occur in the pattern on the master mask that has been exposed in a reduced size and arranged, and the master mask will be used in the manufacture of semiconductor integrated circuit devices. As a result, it becomes unusable.
Therefore, under the condition that the master reticle must be replaced many times to make one master mask, it becomes difficult to obtain a high quality master mask. In such a case, a desirable method is to set the master reticle for one production process in the photorepeater, expose the required number of master masks one after another, and then change to the second master reticle and set it in the photorepeater. Then, the previously exposed master mask may be exposed one after another. However, as a condition for adopting this desirable method, the master mask must be removed from the stage of the photorepeater every time the master reticle pattern is exposed for one manufacturing process. Currently, the photorepeater stage in use only has the function of simply placing the master mask plate, so once the plate is removed from the stage, it can be returned to its original position with an accuracy of at least 1 micron or less. It becomes impossible to set the Therefore, as long as the currently used mask plates and equipment are used, this desirable method cannot be adopted. In other words, the manufacturing of semiconductor integrated circuits requires combinations of masks ranging from several steps to more than ten steps, so if there is a misalignment of more than 1 micron between the patterns arranged and exposed on the master mask, the mask cannot be used again. This is because they do not.

Therefore, when manufacturing a master mask containing two or more types of patterns, the present invention minimizes the number of exchanges of the master reticle, and removes the master mask that has already been pattern-exposed from the stage of the photorepeater and places it on the stage again. The object of the present invention is to provide a manufacturing method that allows setting at almost the same position with an accuracy of 1 micron or less even when setting. The present invention will be explained below using figures.

FIG. 1 is a schematic diagram of a photorepeater. Light is emitted from a light source 1 and the pattern on a master reticle 2 is passed through a reduction optical system 3 and onto a master mask 4.
Form an image. Since the master mask 4 is placed on the stage 5, patterns arranged vertically and horizontally are created by sequentially moving the stage 5 in the X and Y directions. FIG. 2 shows an example in which two or more types of patterns are formed on the same master mask 6. In FIG. This is a master mask in which another pattern 62 is inserted into an array of main patterns 61. Similarly, FIG. 3 shows a state in which a main pattern 71 and other patterns 72 are arranged on the same master mask. FIG. 4 shows a mask plate used in practicing the present invention. The mask plate 8 has a mask forming layer 81 on its front surface, and has at least one alignment pattern section 82 on its back surface. The mask forming layer 81 is formed of a photosensitive layer such as a silver halide emulsion, or is formed of a metal such as chromium or a metal oxide. The alignment pattern portion 82 is a portion in which an alignment pattern is formed using silver halide emulsion, photoresist, metal or metal oxide, or by directly etching the plate. FIG. 5 is a top view of stage 5 of a photorepeater used in carrying out the present invention. stage 5
There is a position mark 51 that serves as a guide when placing the mask plate. If the mask plate is set on the stage in alignment with this position mark 51, rough alignment can be achieved. Next, the alignment sensor section 9 is used to finely adjust and align the mask plate. There is at least one alignment sensor section 9 on the stage and maintains a position at a synchronous interval relative to the alignment pattern section 82 provided on the mask plate 8. Alignment sensor section 9
The structure of will be explained using FIG. FIG. 6 shows a cross-sectional state taken along line A-A' in FIG. Fine alignment adjustment is performed as follows.
First, light is emitted from the light source 91 of the alignment sensor section 9 and illuminates the alignment pattern section 82 . The light reflected by the alignment pattern section 82 is transmitted to the alignment aperture 9 using a lens 92.
3 Tie on top. A sensor 94 is installed under the alignment aperture 93 to detect changes in the amount of light. The light amount level detection by the sensor 94 during fine adjustment alignment can be set so that the amount of light passing through the aperture 93 becomes maximum or minimum when alignment is achieved, or it can be set to an appropriate light amount level. This light amount level selection can be designed by a pattern combination of the alignment pattern section 82 and the alignment aperture 93.
During fine adjustment alignment, the positioning arm 10 reads the signal of the change in light amount from the sensor 94 and moves the mask plate 8 back and forth, left and right, or rotationally. The mask plate 8 is vacuumed by the positioning arm 10 and is controlled to move forward, backward, left, right, or rotationally based on a light intensity signal from a sensor 94.
FIG. 7 is a top plan view of the state shown in FIG. 6.

The above is the stage structure of a mask plate having an alignment pattern for positioning and a photorepeater having an automatic positioning alignment function used in the present invention. Therefore, when using the mask plate and master mask manufacturing equipment of the present invention, the master reticle for one manufacturing process having the main pattern is set on the photorepeater, and then the mask plate is positioned using the alignment mechanism. It is set on a stage and exposed to light in a preset array. This operation of setting and exposing the mask plates is repeated as many times as necessary. Once the main pattern has been exposed, a master reticle having other patterns to be formed on the same master mask is set in the photorepeater. The master mask plate, on which the main pattern has been exposed, is repositioned and set on the stage using an alignment mechanism, and other patterns are exposed at designated locations. This operation may be repeated for the number of exposed master masks for the main pattern. If a master mask is manufactured by this method using the present invention, the number of exchanges of the master reticle set in the photorepeater is equal to the number of master retakes (N) for the number of patterns (N) in the required manufacturing process. It is sufficient to exchange only N times. Since there is no need to take the master reticle in and out of the photorepeater for each pattern exposure, generation and adhesion of dust can be prevented, and scratches etc. are less likely to occur. This results in a high quality master mask. In the above description, an alignment pattern for positioning was provided on the back surface of the mask plate, but the same effect can be obtained even if this alignment pattern is provided on the front surface of the mask plate.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a photorepeater, FIGS. 2 and 3 are plan views showing an example of having two or more types of patterns on the same master mask, and FIG. 4 is an explanation of a mask plate according to an embodiment of the present invention. 5 is a plan view of a stage of another embodiment of the present invention having a positioning alignment mechanism, FIG. 6 is an explanatory diagram of the positioning alignment mechanism, and FIG. 7 is a plan view of the positioning alignment mechanism. be. In the figure, 1... light source, 2... master reticle, 3... reduction optical system, 4... master mask,
5...Stage, 51...Position mark, 6 and 7...
... Master mask, 61 and 71 ... Main patterns, 62 and 72 ... Other patterns, 8 ... Mask plate, 81 ... Mask forming layer, 82 ... Alignment pattern section, 9 ... Alignment sensor section , 91... light source, 92... lens, 93...
Alignment aperture, 94...sensor section, 10...positioning arm.

Claims (1)

[Claims] 1. In a method for manufacturing a master mask in which a plurality of master masks having two or more different patterns are manufactured, a master reticle with a first type of pattern is set in a reduction exposure device, thereby forming a plurality of master plates. A surface of the plurality of master plates on which the pattern of the first type has been exposed in a reduced size, and then a master reticle of a second type of pattern is set in the reduction exposure device, and a pattern of the first type has been exposed in a reduced size. The second type of pattern is reduced and exposed, and an alignment pattern is provided on the back surface of the master plate to provide positional accuracy, and this alignment pattern is used to expose the first and second types of patterns. A method for manufacturing a master mask, characterized in that positioning during reduction exposure is automatically performed.