CN111477610B - Alignment structure - Google Patents

Abstract

The invention provides an alignment structure, which comprises a substrate, an alignment part and an extension part. The alignment part is arranged on the substrate, the extension part is arranged on the substrate, at least part of the extension part surrounds the alignment part, and a gap is formed between the extension part and the alignment part. Wherein one side of the extension part close to the alignment part and one side of the alignment part close to the extension part are conformal with each other.

Description

Alignment structure

technical field

The present invention relates to an alignment structure.

Background technique

Alignment structure (Alignment structure or Alignment key) plays an important role in the process, such as photolithography (photolithography) alignment, generally by direct metal plating or etching a pattern to make the alignment structure, but , After some processes, the metal or pattern will not be visible, or the photoresist coating around the alignment structure will be thinner due to the height difference between the alignment structure and its surrounding structures, resulting in uneven coating. The chromatic aberration makes the identification of the alignment structure inaccurate, thereby causing the problem of poor yield.

SUMMARY OF THE INVENTION

The present invention is directed to an alignment structure that utilizes an extension to avoid the problem of uneven coating of photoresist.

According to an embodiment of the present invention, an alignment structure is provided, including a substrate, an alignment portion, and an extension portion. The alignment portion is arranged on the substrate, the extension portion is arranged on the substrate, and the extension portion at least partially surrounds the alignment portion and is spaced from the alignment portion by a gap. The side of the extension part close to the alignment part and the side of the alignment part close to the extension part are conformal to each other.

Based on the above, compared with the existing alignment structure, the alignment structure provided by the embodiment of the present invention further includes an extension part, in order to prevent the thin photoresist from appearing around the alignment part used for lithography alignment. condition, to avoid the occurrence of chromatic aberration, which affects the identification of the alignment part.

Description of drawings

FIG. 1A is a plan view of the alignment structure after coating a photoresist according to the first embodiment of the present invention.

Fig. 1B is a cross-sectional view taken along the dotted line II-II' of Fig. 1A.

1C is a plan view of an alignment structure after coating a photoresist according to an embodiment of the present invention.

1D is a cross-sectional view of an alignment structure after coating a photoresist according to an embodiment of the present invention.

FIG. 1E is a plan view illustrating the arrangement of an alignment portion and an extension portion according to an embodiment of the present invention.

2 is a cross-sectional view of an alignment structure according to a second embodiment of the present invention.

3 is a cross-sectional view of an alignment structure according to a third embodiment of the present invention.

Description of reference numbers:

100,200,300,400: Alignment structure;

101, 201, 301, 401: substrates;

205: photoresist;

102, 202, 302, 402, 502, 602: Alignment section;

103,203,303,403,503,603: extensions;

104,204,304,404: voids;

206: Outside of the extension.

Detailed ways

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used in the drawings and description to refer to the same or like parts.

Please refer to FIGS. 1A and 1B. FIG. 1A is a plan view of an alignment structure after coating a photoresist according to a first embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along the dotted line II-II' of FIG. 1A.

According to the first embodiment of the present invention, the alignment structure 200 includes a substrate 201 , an alignment portion 202 and an extension portion 203 . The alignment portion 202 is disposed on the substrate 201 , and the extension portion 203 is disposed on the substrate 201 . The extension portion 203 at least partially surrounds the alignment portion 202 and is spaced from the alignment portion 202 by a gap 204 . The side of the extension portion 203 close to the alignment portion 202 and the side of the alignment portion 202 close to the extension portion 203 are conformal to each other, that is, as shown in FIG. 1A , the alignment portion 202 is close to the extension portion 203 One side of the extension portion 203 is in the shape of a cross, and the side of the extension portion 203 close to the alignment portion 202 is also in the shape of a cross.

Referring to FIG. 1B , it can be seen that the photoresist 205 does not have a thin photoresist coating above the gap 204 between the alignment portion 202 and the extension portion 203 , but only on the outside of the extension portion 203 (as shown in FIG. 1B ). In the dotted line), the photoresist 205 is thinner. On the other hand, in the absence of the extension portion 203, the photoresist coating will be thin on the outside of the alignment portion 202. When performing photolithography alignment, a color difference will occur at the thin coating, resulting in inability to accurately align the photoresist. bit status. Therefore, when viewing the alignment structure 200 provided in this embodiment in a plan view ( FIG. 1A ), the side edges of the alignment portion 202 and the side edges of the extension portion 203 adjacent to the gap 204 will not appear chromatic aberration, but only There is a chromatic aberration on the outer side 206 of the extension portion (in FIG. 1A , the outer side 206 of the extension portion is represented by a black point where there is a chromatic aberration), especially in the case of conformal, the photoresist coating on the outer side of the alignment portion 202 can be more uniform, and the alignment The shape of the side of the portion 202 close to the extension portion 203 (when viewed in plan view, this shape is the "outline" of the alignment portion 202 ) is clearly displayed, allowing accurate alignment. Specifically, the substrate 201 may be a temporary substrate, such as a silicon substrate, a plastic substrate, a glass substrate, or a sapphire substrate. The alignment structure 200 is used to provide alignment recognition for the photolithography process during the process of the semiconductor device. Wherein, there may be an adhesive layer between the alignment portion and the extension portion and the substrate, so that when the alignment portion is unclear due to the adhesive layer, the extension portion can also be used as an auxiliary to enable the alignment portion to be accurately aligned .

It should be noted that although the extension portion 203 in FIG. 1A completely surrounds the alignment portion 202 , the present invention is not limited thereto, and the extension portion may only partially surround the alignment portion. As shown in FIG. 1C , the alignment structure 100 includes The substrate 101 , the alignment portion 102 and the extension portion 103 , and the extension portion 103 partially surrounds the alignment portion 102 . It can be seen that although the chromatic aberration represented by black dots appears around the periphery of the extension portion 103 and the partial outline of the alignment portion 102 , the A gap 104 is formed between the outline of other parts of the alignment part 102 and the extension part 103 , so that the outline of this part can be clearly presented without chromatic aberration, and alignment errors can be avoided.

1B, the height of the extension portion 203 in the normal direction of the substrate 201 is equal to the height of the alignment portion 202, but the present invention is not limited to this, please refer to FIG. 1D correspondingly, in FIG. 1D, the extension portion If the height of 503 is greater than the height of the alignment portion 502 , the photoresist coating of the alignment portion 502 will be more uniform, chromatic aberration is less likely to occur, and the definition of the outline of the alignment portion 502 will be better. Preferably, the height ratio of the alignment portion and the extension portion in the normal direction of the substrate falls within the range of 0.5 to 1, the height difference between the two is less than 1 μm, and the height of the extension portion 203 is less than or equal to 20 μm, and the height of the extension portion is greater than 1 μm. 20um may cause identification errors. When the height ratio of the alignment part and the extension part is too small, it will affect the recognition of the alignment part. When the height ratio is too large, the effect of improving the uniformity of photoresist coating is not enough.

Referring back to FIG. 1B , the width A of the extension portion 203 in the direction perpendicular to the normal of the substrate 201 is smaller than the width W of the alignment portion 202 in this direction, so as to avoid the extension portion 203 taking up too much space in this direction and Interfere with alignment work. Preferably, the width ratio (A/W) of the extension portion 203 to the alignment portion 202 in this direction is greater than or equal to 0.2 and less than or equal to 10. Less than 0.2 photoresist coating uniformity effect is not enough, more than 10 will take up too much space. However, in the embodiment not shown, the width A of the extension portion 203 in the direction perpendicular to the normal line of the substrate 201 may be greater than the width W of the alignment portion 202 in the direction, which is not limited herein. In addition, in the direction perpendicular to the normal of the substrate 201 , the width A of the extension 203 and the width B of the gap 204 satisfy the following relationship, so that the extension 203 and the gap 204 do not take up too much space to enhance the light Uniformity of resist coating:

5μm≤A;

0.001μm<B<50μm

In addition, in FIG. 1A , the side of the extension portion 203 away from the alignment portion 202 is a quadrilateral, rather than a cross pattern, that is, the side of the extension portion 203 away from the alignment portion 202 and the alignment portion 202 are shaped differently from each other, which is In order to avoid that the extension portion 203 is mistaken for the alignment portion 202 during photolithography alignment. However, the present invention is not limited thereto. Referring to FIG. 1E, the side of the extension portion 603 close to the alignment portion 602 is a quadrilateral, rather than a cross pattern like the outline of the alignment portion 602, that is, the side of the extension portion close to the alignment portion is opposite to the alignment portion 602. The side of the standard portion close to the extension portion may also be shaped. Wherein, the shape of the alignment portion is not necessarily a cross shape, but may also be a polygon such as a rhombus, a square, etc., which is sufficient to provide alignment, which is not limited here.

According to an embodiment of the present invention, the extension portion may include semiconductor material, metal, dielectric material, organic material, or be formed from the material constituting the alignment portion to simplify the process and increase the yield. More preferably, the alignment portion and the extension portion are formed in the same process.

In FIGS. 1A and 1B , the voids 204 may be filled with materials different from those of the alignment portion 202 and the extension portion 203 , such as metal. In this case, the reflectivity of the material in the voids 204 may be used to form the alignment portions 202 and 203 . The characteristic of the different reflectivity of the materials of the extension portion 203 improves the recognition degree of the outline of the alignment portion 202 .

Next, please refer to FIG. 2 , which shows a cross-sectional view of an alignment structure 300 according to a second embodiment of the present invention. In order to facilitate the understanding of the concept of the present invention, in the second embodiment, only the parts different from the first embodiment will be described, and the same or similar parts as the first embodiment will not be repeated.

In FIG. 2 , the widths of the alignment portion 302 and the extension portion 303 in the direction perpendicular to the normal line of the substrate 301 increase as the distance from the substrate 301 increases, and both are formed in the shape of an inverted trapezoid, and in this direction, the gap is The width of 304 decreases away from the substrate 301 .

According to the present embodiment, the ratio of the minimum width B' and the maximum width E of the void 304 in the direction perpendicular to the normal of the substrate 301 is greater than or equal to 0.3 and less than 1, because the minimum width B' of the void 304 If it is too small, the photoresist will not be able to fill the bottom of the void 304 stably when the photoresist is applied. According to this embodiment, the minimum value B' of the width of the gap 304 is greater than 0.001 μm and less than 50 μm, so as to obtain better photoresist coating uniformity and identification accuracy of the alignment portion 302 . According to the present embodiment, the minimum width A" and the maximum width A' of the extension portion 303 in the direction perpendicular to the normal of the substrate 301 satisfy the following conditional expressions:

5μm≤A’;

0.001μm≤A”<A’; and

0.3≤A”/A’≤1

According to the present embodiment, the angle D between the inverted trapezoidal structure of the alignment portion 302 and the substrate 301 conforms to the relationship 30°<D<90°, so as to avoid that the photoresist cannot be stably and completely filled in the gap 304 due to the too small angle D bottom.

Next, please refer to FIG. 3 , which shows a cross-sectional view of an alignment structure 400 according to a third embodiment of the present invention. In FIG. 3 , the widths of the alignment portion 402 and the extension portion 403 in the direction perpendicular to the normal line of the substrate 401 decrease as the distance from the substrate 401 decreases, and both are formed in a trapezoidal shape, and in this direction, the width of the gap 404 The width increases away from the substrate 401 .

According to the present embodiment, the ratio of the minimum width B" to the maximum width E' of the void 404 in the direction perpendicular to the normal of the substrate 401 is greater than or equal to 0.3 and less than 1, because the minimum width B of the void 404 "If it is too small, the effect of improving the uniformity of photoresist coating is not enough. According to the present embodiment, the maximum width E' of the voids 404 is greater than 0.001 μm and less than 50 μm, and the minimum width B″ of the voids 404 is greater than 0.001 μm and less than the maximum width E′, in order to obtain better photoresist coating uniformity, and the recognition accuracy of the alignment portion 402. According to the present embodiment, the minimum width F″ and the maximum width F′ of the extension portion 403 in the direction perpendicular to the normal of the substrate 401 satisfy the following conditional expressions:

5μm≤F’;

0.001μm≤F”<F’; and

0.3≤F”/F’≤1

According to the present embodiment, the angle D' between the trapezoidal structure of the alignment portion 402 and the substrate 401 conforms to the relational formula 90°<D'≤150°, so as to avoid that the effect of improving the uniformity of photoresist coating is insufficient due to the excessively large angle D .

To sum up, compared with the prior art, the alignment structure provided by the embodiment of the present invention further includes an extension portion, and the arrangement of the extension portion makes the photoresist coating more uniform and improves the accuracy of identifying the alignment portion.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (9)

1. an alignment structure, is characterized in that, comprises: substrate; an alignment portion disposed on the substrate; and an extension part disposed on the substrate, the extension part at least partially surrounding the alignment part and spaced from the alignment part by an air gap, wherein A height of the extension portion surrounding the alignment portion in a first direction is greater than a height of the alignment portion in the first direction, the first direction being parallel to the normal direction of the substrate. 2 . The alignment structure according to claim 1 , wherein a height ratio of the alignment portion and the extension portion in the first direction falls within a range greater than 0.5 and less than 1. 3 . 3 . The alignment structure according to claim 1 , wherein a width ratio of the extending portion in the second direction to the alignment portion in the second direction is greater than or equal to 0.2 and less than or equal to 10, 3 . And the second direction is perpendicular to the normal direction of the substrate. 4 . The alignment structure according to claim 1 , wherein widths of the alignment portion and the extension portion in the second direction increase as they move away from the substrate, and the air gap is in the second direction. 5 . The width in the second direction decreases gradually, and the second direction is perpendicular to the normal direction of the substrate. 5 . The alignment structure according to claim 1 , wherein widths of the alignment portion and the extension portion in the second direction decrease as the distance from the substrate decreases, and the air gap is in the second direction. 6 . The width increases in a second direction, and the second direction is perpendicular to the normal direction of the substrate. 6 . The alignment structure according to claim 1 , wherein the ratio of the minimum value and the maximum value of the width of the air gap in the second direction is greater than or equal to 0.3 and less than or equal to 1, and the second The direction is perpendicular to the normal direction of the substrate. 7. The alignment structure of claim 6, wherein the minimum value of the air gap is greater than 0.001 microns and less than 50 microns. 8 . The alignment structure according to claim 1 , wherein a side of the extension portion away from the alignment portion and a side of the alignment portion close to the extension portion are shaped differently from each other. 9 . 9 . The alignment structure of claim 1 , wherein a side of the extension portion close to the alignment portion and a side of the alignment portion close to the extension portion are conformal to each other. 10 .

Images