Marking unit for exposure field corners

Abstract

The application provides a mark unit for exposure field corner, comprising active layer marks, metal gate layer marks, via layer marks and isolation layer marks; the active layer marks and the metal gate layer marks are staggered, and the metal gate layer marks and the active layer marks are internally provided with blank areas; the via layer marks are arranged in the blank areas, and the overall shape of the via layer marks is adapted to the shape of the blank areas; the via layer marks and the isolation layer marks are arranged in the blank areas, and the overall shape of the via layer marks and the overall shape of the isolation layer marks are adapted to the shape of the blank areas; the isolation layer marks are arranged outside the via layer; the marks do not overlap with each other, and the problem of defects caused by overlapping of several layer marks is solved; the isolation layer marks are arranged to isolate the active layer marks and the via layer marks, so that the via layer marks and the active layer marks are clearly delimited.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of integrated circuit manufacturing lithography technology, and in particular to a marking unit of a field exposure corner. BACKGROUND

[0002] The position of the field exposure corner (Locking Corner) is used to distinguish the boundary between fields, and is formed by the superposition of the cutting track patterns of the four fields above and below and on the left and right. A pattern alignment mark is generally placed at this position to distinguish the boundary between fields. This pattern alignment mark is used in the process result measurement of many modules. For example, the lithography module uses this position as a pre-alignment mark for overlay accuracy and line width size measurement, and the vapor deposition and grinding module also uses this position as a pre-alignment mark for film thickness measurement. The traditional pattern mark placed at this position is a square frame with a size of tens of microns x tens of microns, and the inside of the square frame is a cross with a size of several microns or tens of microns. The inside part of the square frame forms a groove on the silicon wafer, and the other part forms a bump on the silicon wafer. Many layers overlap at the same position.

[0003] As the process nodes in the integrated circuit manufacturing process continue to shrink, the process flow of integrated circuits becomes more and more complex, the number of process layers also increases, and one process layer needs to be divided into several different mask plates. In the prior art Locking Corner, the mark patterns of several layers overlap, and need to be etched at the same position multiple times, which will affect the underlying film layer and have defects such as peeling pattern, residue or particles.

[0004] Therefore, it is necessary to provide a marking unit of a field exposure corner to solve the problem of defects caused by the overlap of mark patterns of several layers. SUMMARY

[0005] The purpose of the present application is to provide a marking unit of a field exposure corner to solve the problem of defects caused by the overlap of mark patterns of several layers.

[0006] The marking unit of the field exposure corner of the present application comprises an active layer mark, a metal gate layer mark, a via layer mark and an isolation layer mark.

[0007] The active layer mark and the metal gate layer mark are arranged alternately in a coverage area of the field exposure corner, and a blank area is arranged inside the coverage area.

[0008] The via layer mark and the isolation layer mark are both arranged in the blank area, and the overall shape of the via layer mark and the overall shape of the isolation layer mark both match the shape of the blank area.

[0009] The isolation layer mark is arranged outside the via layer.

[0010] The marking unit of the exposure field corner of the present application has the following advantages:

[0011] By setting the active layer mark and the metal gate layer mark, setting a blank area inside the active layer mark and the metal gate layer mark, and setting the via layer mark inside the blank area, and the overall shape of the via layer mark and the overall shape of the isolation layer mark are both adapted to the shape of the blank area, so that the active layer mark, the via layer mark and the isolation layer mark do not overlap each other, and the metal gate layer mark, the via layer mark and the isolation layer mark do not overlap each other, that is, the active layer mark or the metal gate layer mark is staggered and separated from the isolation layer mark and the via layer mark, avoiding the overlap of patterns, solving the problem of defects caused by the overlap of several layer marks; by setting the isolation layer mark, the via layer mark and the active layer mark are clearly delimited, ensuring the quality of semiconductor processing.

[0012] Optionally, the active layer mark includes four first marks, any two of which are symmetric about the center of the blank area, and a first gap is provided between adjacent two first marks.

[0013] The metal gate layer mark includes four second marks, any two of which are symmetrically arranged about the center of the blank area, and a second gap is provided between adjacent two second marks. Its beneficial effect is to avoid the overlap of the mark structure after the self-aligned multiple pattern process.

[0014] Optionally, the first mark includes a plurality of first cutting lines, the second mark includes a second cutting line, the first cutting line is arranged transversely, the second cutting line is arranged longitudinally, and the second cutting line is staggered and connected with the first cutting line.

[0015] Optionally, the marking unit of the exposure field corner further includes a trench layer mark, which is arranged inside the blank area and outside the isolation layer.

[0016] Optionally, the trench layer mark includes four third marks, any two of which are symmetric about the center of the blank area, and a third gap is provided between adjacent two third marks.

[0017] Optionally, the third mark includes a plurality of first trenches and a plurality of second trenches, and the first trenches and the second trenches are arranged in intervals. Its beneficial effect is that the first trenches and the second trenches are arranged in intervals, and when spin-coating photoresist material, the trench layer can be filled with photoresist material, thereby avoiding the residual of thin film in the subsequent pattern etching step caused by the large thickness of the carbon layer caused by the over-deep front layer trench, ensuring the etching quality of the pattern.

[0018] Optionally, the mark unit of the exposure field corner further comprises an isolation layer mark, which is arranged between the isolation layer mark and the via layer mark.

[0019] Optionally, the isolation layer mark comprises four fourth marks, any two of which are symmetric about the center of the blank area, and a fourth gap is arranged between any two adjacent fourth marks.

[0020] Optionally, the fourth mark comprises a plurality of third grooves and a plurality of fourth grooves, and the third grooves and the fourth grooves are arranged at intervals.

[0021] Optionally, the isolation layer mark and the via layer mark have a mark space for accommodating the staggered process layer mark. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Structure diagram of the mark unit of the exposure field corner according to the first embodiment of the present application.

[0023] Figure 2 Structure diagram of the mark unit of the exposure field corner according to the first embodiment of the present application. Figure 1 Structure diagram of the mark unit of the exposure field corner according to the first embodiment of the present application.

[0024] Figure 3 Structure diagram of the mark unit of the exposure field corner according to the second embodiment of the present application.

[0025] Figure 4 Structure diagram of the mark unit of the exposure field corner according to the third embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application. Unless otherwise defined, the technical terms or scientific terms used herein should be understood as the common meanings thereof by those of ordinary skill in the art to which the present application belongs. The words such as “comprise” and the like used herein mean that the elements or objects before the words encompass the elements or objects listed after the words and their equivalents, and do not exclude other elements or objects.

[0027] Figure 1 Structure diagram of the mark unit of the exposure field corner according to the first embodiment of the present application.

[0028] Some embodiments of the present application provide a mark unit of an exposure field corner.

[0029] Referring to Figure 1 , the first exposure field corner marking unit of the present application comprises active layer marks 1, metal gate layer marks 2, isolation layer marks 3 and via layer marks 4;

[0030] The active layer marks 1 and the metal gate layer marks 2 are staggered in the coverage area 13 of the exposure field corner, and a blank area 11 is arranged in the inside of the coverage area 13;

[0031] The isolation layer marks 3 and the via layer marks 4 are both arranged in the blank area 11, and the overall shape of the via layer marks 4 and the overall shape of the isolation layer marks 3 both match the shape of the blank area 11;

[0032] The isolation layer marks 3 are arranged outside the via layer 4.

[0033] The exposure field corner marking unit of the present application has the advantage that the marks do not overlap each other, i.e. the active layer marks 1 or the metal gate layer marks 2 are staggered and separated from the isolation layer marks 3 and the via layer marks 4, thus solving the problem of defects caused by the overlapping of several layers of marks; the isolation layer marks 3 are arranged to make the boundary between the via layer marks 4 and the active layer marks 1 clear.

[0034] In some embodiments, the metal gate layer marks 2 are arranged on top of the active layer marks 1.

[0035] In some embodiments, the distance between the left boundary and the right boundary of the outside of the active layer marks 1 is greater than the distance between the left boundary and the right boundary of the outside of the metal gate layer marks 2, and the distance between the left boundary and the right boundary of the inside of the active layer marks 1 is less than the distance between the left boundary and the right boundary of the inside of the metal gate layer marks 2; this ensures that the metal gate layer marks 2 can be completely supported by the active layer marks 1, thus making the focal plane of the metal gate layer marks 2 consistent with the focal plane of the actual pattern area of the device during exposure, thereby avoiding the defocus phenomenon caused by the inconsistency between the metal gate layer marks 2 and the focal plane of the actual pattern area of the device, and avoiding the problem of pattern peeling.

[0036] As an optional embodiment of the present application, the overall shape of the active layer marks 1 and the metal gate layer marks 2 is rectangular, and the shape of the via layer marks 4 and the blank area 11 is a "cross".

[0037] As an optional embodiment of the present application, referring to Figure 1 , the active layer marks 1 comprise four first marks 10, any two first marks 10 are symmetric about the center of the blank area, and a first gap a is arranged between adjacent two first marks 10, to avoid the overlapping of the mark structure.

[0038] As an optional embodiment of the present application, referring to Figure 1The metal gate layer mark 2 comprises four second marks 20, any two of the second marks 20 are symmetric about the center of the blank area, and a second gap b is arranged between adjacent two of the second marks 20 to avoid overlapping of the mark structures.

[0039] In some embodiments, the active layer mark 1 is arranged on the exposure field corner of the silicon wafer, the active layer mark 1 is an alignment mark corresponding to the active layer; the first mark 10 is arranged through the mask plate, four first marks 10 are arranged at four corners of the exposure field corner respectively, and the active layer mark 1 as shown in Figure 1 is obtained through combination of patterns after exposure, the center of the active layer mark 1 is an uncovered area, i.e., the blank area 11;

[0040] The second mark 20 is arranged through the mask plate, four second marks 20 are arranged at four corners of the exposure field corner respectively, and the metal gate layer mark 2 as shown in Figure 1 is obtained through combination of patterns after exposure.

[0041] As an optional embodiment of the present application, referring to Figure 1 , the first mark 10 comprises a plurality of first cutting line bars 101, the second mark 20 comprises a plurality of second cutting line bars 201, the first cutting line bars 101 are arranged transversely, the second cutting line bars 201 are arranged longitudinally, and the second cutting line bars 201 are connected to the first cutting line bars 101 in a staggered manner.

[0042] In some embodiments, referring to Figure 1 , each first cutting line bar 101 is connected to and arranged perpendicularly to at least one second cutting line bar 201, and each second cutting line bar 201 is connected to and arranged perpendicularly to at least one first cutting line bar 101.

[0043] In some embodiments, the first cutting line bar 101 and the second cutting line bar 201 are both in the shape of a line bar with a line width, and the size of the first cutting line bar 101 and the second cutting line bar 201 is consistent with the actual pattern size in the device.

[0044] In some embodiments, the isolation layer 3 is formed by four mask plates into isolation line bars, including a first isolation line bar, a second isolation line bar, a third isolation line bar and a fourth isolation line bar, and the four isolation line bars can be arranged in an overlapping manner along the height direction of the mask plate.

[0045] In some specific embodiments, referring to Figure 1 , the overall shape of the isolation layer mark 3 is a "cross" shape, the overall length thereof is 20-90 microns, and the line width thereof is 2-9 microns.

[0046] Figure 2 is an enlarged structure schematic view of the through-hole layer mark in Figure 1 .

[0047] In some embodiments, referring to Figure 2 , the through-hole layer mark 4 comprises a trench pattern, which comprises a first trench pattern 41, a second trench pattern 42, a third trench pattern 43 and a fourth trench pattern 44, which are sequentially nested from outside to inside.

[0048] In some embodiments, a mask plate is provided, and etching is sequentially performed on the first mask plate, the second mask plate, the third mask plate and the fourth mask plate to sequentially obtain the trench pattern.

[0049] In some embodiments, the length of the trench pattern is 2-9 microns; the width of the trench pattern length is 200-900 nanometers; and the distance between adjacent two trenches is also 200-900 nanometers, so that after etching, the adjacent trenches and the adjacent mask plate marks do not contact each other when they are superimposed, thereby avoiding mutual influence.

[0050] The present application changes the pattern of the through-hole layer mark 4 at the corner of the exposure field into a pattern with a line width of several hundred nanometers and offsets it from other patterns, so that the surface depression of the metal layer can be avoided.

[0051] Figure 3 It is a structural schematic diagram of the mark unit of the second embodiment of the present application at the corner of the exposure field.

[0052] In some embodiments, referring to Figure 3 , the mark unit at the corner of the second exposure field of the present application comprises an active layer mark 1, a metal gate layer mark 2, an isolation layer mark 3 and a through-hole layer mark 4, the metal gate layer mark 2 and the active layer mark 1 are arranged in a coverage area 13, a blank area 11 is arranged inside the coverage area, the isolation layer mark 3 and the through-hole layer mark 4 are arranged in the blank area 11. Figure 1 and Figure 3 , the difference between the mark unit at the corner of the second exposure field and the mark unit at the corner of the first exposure field is that the mark unit at the corner of the second exposure field further comprises a trench layer mark 5, the trench layer mark 5 is arranged in the blank area 11, and the trench layer mark 5 is located outside the isolation layer 3.

[0053] In some embodiments, the generation step of the isolation layer mark 3 is:

[0054] Before forming the trench layer mark 5, a bump is arranged at the corresponding position of the isolation layer mark 3, and the bump will block the etching when etching the mask plate of the isolation layer mark 3, thereby achieving the cutting of the trench layer mark 5 by the isolation layer mark 3.

[0055] In some embodiments, the isolation layer mark 3 comprises isolation marks stacked from top to bottom, specifically comprising a first isolation mark, a second isolation mark, a third isolation mark and a fourth isolation mark, the shapes and sizes of the isolation marks are consistent, and the projections of the isolation marks can overlap.

[0056] As an optional embodiment of the present application, referring to Figure 3 , the trench layer mark 5 comprises four third marks 50, any two third marks 50 are symmetric about the center of the blank area 11, and a third gap d is arranged between adjacent two third marks 50.

[0057] As an optional embodiment of the present application, referring to Figure 3 , the third mark 50 comprises a plurality of first trenches 501 and a plurality of second trenches 502, and the first trenches 501 and the second trenches 502 are arranged alternately. The advantage is that the first trenches 501 and the second trenches 502 are arranged alternately, and the trench layer can be filled with photoetching material when the photoetching material is spin-coated, thereby avoiding the problem that the carbon layer thickness is large due to the over-deep front layer trench in the spin-coating process, and ensuring the etching quality of the pattern.

[0058] In some embodiments, the fifth mask and the sixth mask are arranged, the first trench 501 is obtained by etching the fifth mask, and the second trench 502 is obtained by etching the sixth mask.

[0059] In some embodiments, the period length of the third mark 50 is four times the line width of the first trench 501 and the line width of the second trench 502; for example, the line width of the first trench 501 is 100 nm, the line width of the second trench 502 is 100 nm, and the interval between the first trench 501 and the second trench is also 100 nm, and the repeat period length of the trench block is 400 nm.

[0060] The present application avoids the corrosion of the connecting layer by the grinding liquid by staggering the positions of the via layer mark 4 and the trench layer mark 5 through the isolation layer mark 3 and reasonably setting the size thereof.

[0061] In the prior art, the line width size of the trench layer mark in the device is below 30 nm, and the trench depth is deep; after the thin film and the metal are grown in the trench, the surface metal that is not needed is ground away through the grinding process and a certain height requirement is reached; however, the metal grown on the trench layer mark is more easily ground than the adjacent dielectric layer, the pattern size in the device is small, and when the pattern in the device is ground to the specified thickness, the surface metal at the exposure field corner is ground more due to the large pattern size, and a recess is formed;

[0062] The present application changes the line width size of the trench layer mark 5 at the exposure field corner to 30-90 nm, and the trench layer mark 5 comprises the first trench 501 and the second trench 502, the first trench 501 and the second trench 502 are arranged alternately, the line width size of the first trench 501 and the second trench 502 is larger than the line width size of the trench layer mark 5 in the device in the prior art, a sufficient photoetching process window is met, and it is ensured that the recess is not generated during the grinding.

[0063] Figure 4 The structure diagram of the marking unit of the exposure field corner of the third embodiment of the present application.

[0064] As an optional embodiment of the present application, referring to Figure 3 and Figure 4 , the marking unit of the third exposure field corner is different from the marking unit of the second exposure field corner in that the marking unit of the third exposure field corner further comprises an isolation layer mark 6, which is arranged between the isolation layer mark 3 and the via layer mark 4.

[0065] As an optional embodiment of the present application, the isolation layer mark 6 and the via layer mark 4 have a mark space for accommodating the staggered process layer mark, that is, the mark space can be provided with other process layer exposure field corner marks.

[0066] As an optional embodiment of the present application, referring to Figure 4 , the isolation layer mark 6 comprises four fourth marks 61, and any two fourth marks 61 are symmetric about the center of the blank area 11, and a fourth gap c is arranged between the adjacent two fourth marks 61.

[0067] As an optional embodiment of the present application, referring to Figure 4 , the fourth mark 61 comprises a plurality of third grooves 601 and a plurality of fourth grooves 602, and the third grooves 601 and the fourth grooves 602 are arranged at intervals.

[0068] In some embodiments, the line width dimension of the third groove 601 and the fourth groove 602 is 30-90 nanometers.

[0069] In some embodiments, the period length of the fourth mark 61 is four times the line width of the third groove 601 and the line width of the fourth groove 602, and the period length of the cutting strip is the length of the area occupied by each cutting strip.

[0070] The present application changes the line width dimension of the third groove 601 and the fourth groove 602 at the exposure field corner to 30-90 nanometers, and the third groove 601 and the fourth groove 602 are staggered alternately, which ensures that the thin film can be filled as much as possible when filling the groove; because the position of the exposure field corner may have a difference in focal plane height from the actual device, the line width of the third groove 601 and the fourth groove 602 is larger than the size in the actual device, and the increase of the line width dimension correspondingly increases the process window of photolithography, thereby avoiding defects caused by poor defocus patterns.

[0071] The third groove 601 and the fourth groove 602 are arranged alternately and staggeredly with the active layer mark 1, the metal gate layer mark 2, the isolation layer mark 3, the via layer mark 4 and the groove layer mark 5, and the marks do not overlap in the mark alignment of the multi-layer pattern, the third groove 601 and the fourth groove 602 are arranged alternately and staggeredly, and the depth of the groove is not increased, so that the problem of the residual of the thin film is avoided.

[0072] The mark unit of the exposure field corner in the application can reasonably optimize the line width of each process layer mark according to the process characteristics, so as to avoid the problem of defects caused by too large or too small pattern.

[0073] Although the embodiments of the application have been described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to the embodiments. However, it should be understood that such modifications and changes are within the scope and spirit of the application described in the claims. Moreover, the application described herein can have other embodiments and can be implemented or realized in various ways.

Claims

1. A marking unit for the corner of an exposure field, characterized in that: Including active layer marking, metal gate layer marking, through-hole layer marking and isolation layer marking; The active layer mark and the metal gate layer mark are alternately arranged in a coverage area at a corner of the exposure field, and a blank area is arranged inside the coverage area; The through-hole layer mark and the isolation layer mark are both arranged in the blank area, and the overall shape of the through-hole layer mark and the overall shape of the isolation layer mark are both adapted to the shape of the blank area; The isolation layer mark is arranged on the outside of the through-hole layer.

2. The marking unit for the corner of the exposure field according to claim 1, characterized in that: The active layer mark includes four first marks, any two of the first marks are symmetrically arranged about the center of the blank area, and a first gap is set between two adjacent first marks; The metal gate layer mark includes four second marks, any two of the second marks are symmetrical about the center of the blank area, and a second gap is set between two adjacent second marks.

3. The marking unit for the corner of the exposure field according to claim 2, characterized in that: The first mark includes a plurality of first cutting lines, and the second mark includes a plurality of second cutting lines. The first cutting lines are arranged horizontally, and the second cutting lines are arranged vertically. The second cutting lines are staggered and connected with the first cutting lines.

4. The marking unit for the corner of the exposure field according to claim 1, characterized in that: The invention also includes a groove layer mark, wherein the groove layer mark is arranged in the blank area and is located outside the isolation layer.

5. The marking unit for the corner of the exposure field according to claim 4, characterized in that: The groove layer mark includes four third marks, any two of the third marks are symmetrical about the center of the blank area, and a third gap is set between two adjacent third marks.

6. The marking unit for the corner of the exposure field according to claim 5, characterized in that: The third mark includes a plurality of first grooves and a plurality of second grooves, and the first grooves are spaced apart from the second grooves.

7. The marking unit for the corner of the exposure field according to claim 1, characterized in that: It also includes an isolation layer mark, which is arranged between the isolation layer mark and the through-hole layer mark.

8. The marking unit for the corner of the exposure field according to claim 7, characterized in that: The isolation layer mark includes four fourth marks, any two of the fourth marks are symmetrical about the center of the blank area, and a fourth gap is set between two adjacent fourth marks.

9. The marking unit for the corner of the exposure field according to claim 8, characterized in that: The fourth mark includes a plurality of third grooves and a plurality of fourth grooves, and the third grooves are spaced apart from the fourth grooves.

10. The marking unit for the corner of the exposure field according to claim 7, characterized in that: A marking space for accommodating staggered process layer marks is provided between the isolation layer mark and the through-hole layer mark.

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