CN103000616B

CN103000616B - The manufacture method of thin metal layer photoetching alignment mark

Info

Publication number: CN103000616B
Application number: CN201110272670.5A
Authority: CN
Inventors: 童宇锋; 李伟峰; 陈福成
Original assignee: Shanghai Huahong Grace Semiconductor Manufacturing Corp
Current assignee: Shanghai Huahong Grace Semiconductor Manufacturing Corp
Priority date: 2011-09-15
Filing date: 2011-09-15
Publication date: 2015-12-02
Anticipated expiration: 2031-09-15
Also published as: CN103000616A

Abstract

The invention discloses a kind of manufacture method of thin metal layer photoetching alignment mark, the method is before the long-pending thin metal layer of pad, further comprising the steps of: 1) on substrate dielectric layer, the position corresponding with the photoetching alignment mark that will make, coating photoresist is as barrier layer, and exposure, etches; 2) with the metal or alloy filling step 1 different from the material of thin metal layer) region that etches away; 3) surface, cmp fill area, makes it lower than described dielectric layer.The method is by changing the substrat structure of thin metal layer photoetching alignment mark, improve difference of height and the light and shade contrast of thin metal layer photoetching alignment mark, thus achieve rear layer and aim at the direct of thin metal layer, improve the alignment precision of front and back layer, ensure that the design performance of product.

Description

The manufacture method of thin metal layer photoetching alignment mark

Technical field

The present invention relates to field of semiconductor manufacture, particularly relate to a kind of manufacture method of thin metal layer photoetching alignment mark.

Background technology

In semiconductor fabrication process, lithography alignment accuracy is one of key factor of restriction smaller szie technique.Due to the front and back layer relevance of layout design, in later process, rear layer usually can be adopted directly to the way of the photoetching alignment mark of front layer, to promote the alignment precision of front and back layer, ensure the performance of product.

In the technique platform that some are special, thin metal layer can be introduced to connect upper and lower medium layer in later process.Such as, the self-registered technology introduced in the technique platform of embedded flash memory (EmbeddedFlash), its committed step is exactly oxide layer and metal level Alignment Process, as shown in Figure 1, wherein, metal layer process uses the titanium nitride (TiN) on the 900 Izod right sides.Due to this kind of metal level very thin (thickness is generally less than 2000 dusts), cause the step difference of height of the photoetching alignment mark formed after etching very little, poor with the light and shade contrast of surrounding oxidic silicon layer.And according to the normal setting of Nikon photoetching equipment, the step difference of height of photoetching alignment mark is good to be not less than 5000 dusts; Close to during 3000 dust can by open phase shift function strengthen signal; When difference of height be less than 2000 dusts even lower time, photoetching alignment mark produce signal (signal indicated by point as red in Fig. 2) excessively weak, board cannot be analyzed accurately it and read.Therefore, lower one deck of thin metal layer, on time, cannot adopt the method for directly aiming at.

In order to realize the lithography alignment of lower one deck, usually adopt the method for indirectly aiming at present, namely to the photoetching alignment mark of front layer (that one deck before thin metal layer).But the method for this indirect aligning exists following shortcoming: 1, aim at less stable, if create impact to front layer mark in thin metal layer technique, then occur reporting to the police to being easy on time in later layer; 2, when thin metal layer is contrary with later layer alignment compensation value direction, aim at and there will be deviation, increase the rework rate of goods, even affect the performance of subsequent product.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of manufacture method of thin metal layer photoetching alignment mark, and it can improve the alignment precision of layer after thin metal layer, ensures the performance of subsequent product.

For solving the problems of the technologies described above, the manufacture method of thin metal layer photoetching alignment mark of the present invention, before the long-pending thin metal layer of pad, further comprising the steps of:

1) on substrate dielectric layer, the position corresponding with the photoetching alignment mark that will make, coating photoresist is as barrier layer, and exposure, etches;

2) with the metal or alloy filling step 1 different from the material of thin metal layer) region that etches away;

3) surface, cmp fill area, makes it lower than described dielectric layer.

The manufacture method of thin metal layer photoetching alignment mark of the present invention, by changing the substrat structure of thin metal layer photoetching alignment mark, improve difference of height and the light and shade contrast of thin metal layer photoetching alignment mark, thus when lower one deck is aimed at, adopted the way of directly aiming at, and then improve the alignment precision of front and back layer, ensure that the design performance of product.

Accompanying drawing explanation

Fig. 1 is the fabrication processing of existing thin metal layer photoetching alignment mark;

Fig. 2 is the signal of the thin metal layer photoetching alignment mark adopting existing method to make;

Fig. 3 is the fabrication processing of thin metal layer photoetching alignment mark of the present invention;

Fig. 4 is after thin metal layer photoetching alignment mark of the present invention completes, and in later process, the top dielectric layer of thin metal layer carries out the schematic diagram aimed to the photoetching alignment mark of thin metal layer;

Fig. 5 is the signal of the thin metal layer photoetching alignment mark adopting method of the present invention to make.

Description of reference numerals

1,4: dielectric layer

2: thin metal layer

3: photoetching alignment mark

Embodiment

Understand more specifically for having technology contents of the present invention, feature and effect, now in conjunction with illustrated execution mode, details are as follows:

The manufacture method of the thin metal layer photoetching alignment mark of the present embodiment, its concrete technology flow process is as follows:

Step 1, the dielectric layer 1 of long-pending thin metal layer 2 lower floor of pad, as shown in Fig. 3 (a);

Step 2, on described dielectric layer 1, corresponds to the position of thin metal layer 2 photoetching alignment mark 3 that will make, and coating photoresist, then exposes, etch away the region not having photoresist to stop, as shown in Fig. 3 (b).

Step 3, the region etched away with tungsten (W) filling step 2.In this step, also can fill with other metal or alloy, but filling material can not be identical with the material of thin metal layer.

Step 4, using described dielectric layer 1 as barrier layer, carries out cmp (CMP) to surface, tungsten fill area, makes tungsten fill area surface planarisation, and a little less than the height of dielectric layer 1, as shown in Fig. 3 (c).

Step 5, the long-pending thin metal layer 2 of pad.Thin metal layer 2 is less than or equal to 1: 3 with the thickness ratio of dielectric layer 1.The material of thin metal layer 2 can be aluminium, copper, aluminium copper or other metal materials.

Step 6, thin metal layer 2 will make the position of photoetching alignment mark 3, and coating photoresist, as barrier layer, then exposes, etches away the region not having photoresist to stop, forms the photoetching alignment mark 3 of thin metal layer 2.The size of photoetching alignment mark 3 can be corresponding with it the size of underlying dielectric layers identical, also can there is difference (difference general control is within ± 15%).

Said method, by placing the onesize but mark that light and shade is contrary (namely underlying dielectric layers 1 exceeds the part of tungsten fill area) at photoetching alignment mark 3 place of thin metal layer 2, improves the light and shade contrast of photoetching alignment mark 3.In last part technology, dielectric layer 4 (identical with underlying dielectric layers 1 material) when thin metal layer 2 upper strata carries out on time to the photoetching alignment mark 3 of thin metal layer 2, the registration signal produced obtains obvious enhancing (as shown in Figure 4,5), thus enable photoetching equipment grab desirable signal, and Direct Analysis is carried out to signal, obtain accurate pattern and the information of thin metal layer.

Claims

1. the manufacture method of thin metal layer photoetching alignment mark, is characterized in that, before the long-pending thin metal layer of pad, comprises the following steps:

3) surface, cmp fill area, makes it lower than described dielectric layer;

After the long-pending thin metal layer of pad, thin metal layer will make the position of photoetching alignment mark, coating photoresist, as barrier layer, then exposes, etches away the region not having photoresist to stop, forms the photoetching alignment mark with thin metal layer.

2. method according to claim 1, is characterized in that, the material of described thin metal layer is aluminium, copper or aluminium copper.

3. method according to claim 1, is characterized in that, step 2) in, fill with tungsten.

4. method according to claim 1, is characterized in that, the thickness ratio of described thin metal layer and described dielectric layer is less than or equal to 1:3.