Testkey and application method for characterizing the accuracy of overlay error measurement in self-aligned imaging process

Abstract

The present invention provides a testkey and application method for characterizing the accuracy of measuring the overlay error of a self-aligned imaging process, including a horizontal direction and a vertical direction perpendicular to the horizontal direction; two layers of data consisting of a cutting layer pattern and a mandrel pattern; the central axis pattern consists of a central pattern and two side patterns; the central pattern consists of a plurality of polygons distributed at intervals along the horizontal direction; the cutting layer pattern consists of a plurality of polygons distributed at intervals along the vertical direction, and the cutting layer pattern is superimposed on the central pattern; the two side patterns are located on both sides of the central pattern; the central pattern consists of a plurality of polygons distributed at intervals along the horizontal direction X. The present invention uses the design of the testkey to produce an imprint after etching the SADP cutting layer, while keeping the etching behavior of the testkey consistent with the central pattern; the overlay error of the cutting layer is directly measured by the measurement of the testkey; the accuracy of the indirect measurement method of the overlay error can be characterized by the measurement result of the testkey.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a testkey for characterizing the measurement accuracy of overlay errors in a self-alignment imaging process and an application method thereof. Background Art

[0002] The existing overlay error measurement methods IBO / DBO are both indirect measurements, which require the design of different marks and the use of direct measurement results to evaluate these marks and confirm their measurement accuracy. The commonly used evaluation method is to compare with the results of SEMOVL mark. SEM OVL mark uses CDSEM to measure the specially designed front and back layer structures to directly obtain the overlay error.

[0003] The SADP process first defines the global structure, and then removes the redundant structure through the cut layer. Due to the three-dimensional structure of the bottom layer, the cut layer parallel to the bottom layer structure cannot leave an imprint. The present invention provides a testkey design and method for characterizing the accuracy of the overlay error measurement of the FinFET self-aligned imaging process. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a testkey and application method for characterizing the accuracy of overlay error measurement in a self-aligned imaging process, so as to solve the problem that the cutting layers parallel to the underlying structure cannot leave marks in the overlay error measurement in the prior art.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a testkey for characterizing the accuracy of overlay error measurement in a self-aligned imaging process, comprising at least:

[0006] A horizontal direction X and a vertical direction Y perpendicular to the horizontal direction X;

[0007] Two layers of data consisting of cutting layer graphics and mandrel graphics;

[0008] The mandrel pattern is composed of a central pattern and two side patterns; the central pattern is composed of a plurality of polygons spaced apart along the transverse direction X; the cutting layer pattern is composed of a plurality of polygons spaced apart along the longitudinal direction Y, and the cutting layer pattern is superimposed on the central pattern;

[0009] The two side graphics are located on both sides of the central graphic; the two side graphics are composed of a plurality of polygons distributed at intervals along the longitudinal direction Y.

[0010] Preferably, the mandrel pattern is made on the substrate

[0011] Preferably, the cutting layer pattern is used to etch the central pattern so that an etching mark is left on the central pattern.

[0012] Preferably, the cutting layer pattern and the mandrel pattern are strip structures.

[0013] Preferably, the number of the strip structures of the cutting layer pattern, the central pattern and the two side patterns is at least 5 respectively.

[0014] Preferably, the self-aligned imaging process includes SADP and SAOP.

[0015] Preferably, the graphics on both sides are graphics used for scaling.

[0016] The present invention also provides a testkey application method for characterizing the accuracy of overlay error measurement in a self-aligned imaging process, which at least comprises:

[0017] Step 1: Before the trial production of the mask, a testkey is designed to obtain the testkey;

[0018] Step 2: during trial production of the photomask, place the testkey close to the IBO or DBO photomask of the corresponding level;

[0019] Step 3: In actual production, after the cutting layer of the testkey is completed, the testkey is measured using CDSEM to obtain a direct representation value of the overlay error;

[0020] Step 4: perform point-to-point comparison of the overlay error obtained by the testkey with IBO or DBO to obtain the measurement accuracy of indirect measurement methods such as IBO or DBO.

[0021] Preferably, in step three, a direct representation value of the overlay error is obtained by the difference between the etching mark of the cutting layer on the central pattern in the testkey and the CD measurement value between the two side patterns in the testkey.

[0022] As described above, the testkey and application method for characterizing the accuracy of measuring the overlay error of the self-aligned imaging process of the present invention have the following beneficial effects: first, through the design of the testkey, an imprint is produced after the SADP cutting layer is etched, while keeping the etching behavior of the testkey consistent with the central pattern; second, the overlay error of the cutting layer is directly measured through the measurement of the testkey; third, the accuracy of the indirect measurement method of the overlay error can be characterized through the measurement results of the testkey. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1Shown is a schematic diagram of the layout structure of the testkey in the present invention;

[0024] Figure 2 Shown is a schematic diagram of the measurement position of the present invention;

[0025] Figure 3 It is a schematic diagram showing the comparison results of the IBO and CDSEM marking measurements in the horizontal direction in the present invention;

[0026] Figure 4 It is a schematic diagram showing the comparison results of the longitudinal measurements of IBO and CDSEM markers in the present invention. DETAILED DESCRIPTION

[0027] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] See also Figures 1 to 4 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0029] The present invention provides a testkey for characterizing the accuracy of overlay error measurement in a self-aligned imaging process, such as Figure 1 As shown, Figure 1 Shown is a schematic diagram of the layout structure of the testkey in the present invention. At least including:

[0030] A horizontal direction X and a vertical direction Y perpendicular to the horizontal direction X;

[0031] Two layers of data consisting of cutting layer graphics and mandrel graphics;

[0032] The mandrel pattern is composed of a central pattern and two side patterns; the central pattern is composed of a plurality of polygons spaced apart along the transverse direction X; the cutting layer pattern is composed of a plurality of polygons spaced apart along the longitudinal direction Y, and the cutting layer pattern is superimposed on the central pattern;

[0033] The two side graphics are located on both sides of the central graphic; the two side graphics are composed of a plurality of polygons distributed at intervals along the longitudinal direction Y.

[0034] Wherein the lateral direction X is Figure 1The horizontal direction in the horizontal direction; the longitudinal direction Y perpendicular to the horizontal direction X is Figure 1 The vertical direction within the paper that is perpendicular to the horizontal direction;

[0035] The cut layer pattern and the mandrel pattern are composed of two layers of data; therefore, the cut layer pattern and the mandrel pattern are two layers in the layout.

[0036] The mandrel pattern is composed of a central pattern 01 and two side patterns (Mandrel); the central pattern 01 is composed of a plurality of polygons spaced apart along the transverse direction X; the cut layer pattern is composed of a plurality of polygons spaced apart along the longitudinal direction Y, and the cut layer pattern is superimposed on the central pattern 01;

[0037] The two side graphics (Mandrel) are located on both sides of the central graphic 01; the central graphic 01 is composed of a plurality of polygons distributed at intervals along the horizontal direction X.

[0038] According to a further aspect of the present invention, the mandrel pattern of this embodiment is fabricated on a substrate.

[0039] Furthermore, in the present invention, the cutting layer pattern (cut layer) of this embodiment is used to etch the central pattern 01, so that the central pattern 01 leaves an etching mark.

[0040] The present invention further provides that the cutting layer pattern and the mandrel pattern of this embodiment are as follows: Figure 1 The bar structure shown.

[0041] According to the present invention, the number of the strip structures of the cutting layer pattern (cut layer), the center pattern 01 and the two side patterns (Mandrel) of this embodiment is at least 5 respectively.

[0042] Furthermore, in the present invention, the self-aligned imaging process of this embodiment at least includes SADP, SADP, and SAOP.

[0043] Furthermore, in the present invention, the two side graphics of this embodiment are graphics used for sizing.

[0044] The present invention also provides an application method of the testkey for characterizing the overlay error measurement accuracy of the self-aligned imaging process, which at least comprises:

[0045] Step 1: Before the trial production of the mask, the testkey design is performed to obtain the testkey; Step 1 of the present invention: Before the trial production of the mask, the testkey design is performed to obtain the testkey (test key);

[0046] Step 2: during trial production of the photomask, place the testkey close to the IBO or DBO photomask of the corresponding level;

[0047] Step 3: In actual production, after the cutting layer of the testkey is completed, the testkey is measured using CDSEM to obtain a direct representation value of the overlay error;

[0048] The present invention further provides that in step 3 of this embodiment, the direct representation value of the overlay error is obtained by the difference between the etching mark of the cutting layer on the central pattern in the testkey and the CD measurement value between the two side patterns in the testkey. Figure 2 As shown, Figure 2 Shown is a schematic diagram of the measurement position of the present invention.

[0049] Step 4: perform point-to-point comparison of the overlay error obtained by the testkey with IBO or DBO to obtain the measurement accuracy of indirect measurement methods such as IBO or DBO.

[0050] That is to say, provide the design rule designrule of mandrel and cut layer parallel to the global structure;

[0051] Then design the test key, such as Figure 1 , is a schematic diagram of the actual test key placed on the mask in the X direction; then the test key is placed on the mask and printed; photolithography and etching processes are performed, and the test key is detected using CDSEM, OVLx = X1-X2; OVLy = Y1-Y2. Figure 3 As stated, Figure 3 It is a schematic diagram showing the comparison results of the IBO and CDSEM markings in the horizontal direction in the present invention. Figure 4 The figure shows the comparison results of the IBO and CDSEM markings in the longitudinal direction in the present invention. The CDSEM measurement results of the testkey are compared with the IBO measurement to obtain the accuracy of the IBO measurement results.

[0052] In summary, the present invention firstly produces an imprint after etching the SADP cutting layer through the design of the testkey, while keeping the etching behavior of the testkey consistent with the central pattern; secondly, directly measures the overlay error of the cutting layer through the measurement of the testkey; thirdly, the accuracy of the indirect measurement method of the overlay error can be characterized by the measurement result of the testkey. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0053] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A testkey for characterizing the accuracy of overlay error measurement in self-aligned imaging process, characterized in that: At least: A horizontal direction X and a vertical direction Y perpendicular to the horizontal direction X; Two layers of data consisting of cutting layer graphics and mandrel graphics; The mandrel pattern is composed of a central pattern and two side patterns; the central pattern is composed of a plurality of polygons spaced apart along the transverse direction X; the cutting layer pattern is composed of a plurality of polygons spaced apart along the longitudinal direction Y, and the cutting layer pattern is superimposed on the central pattern; The two side graphics are located on both sides of the central graphic; the two side graphics are composed of a plurality of polygons distributed at intervals along the longitudinal direction Y.

2. The testkey for characterizing the overlay error measurement accuracy of the self-aligned imaging process according to claim 1, characterized in that: The mandrel pattern is formed on a substrate.

3. The testkey for characterizing the overlay error measurement accuracy of the self-aligned imaging process according to claim 1, characterized in that: The cutting layer pattern is used to etch the central pattern so that an etching mark is left on the central pattern.

4. The testkey for characterizing the overlay error measurement accuracy of the self-aligned imaging process according to claim 1, characterized in that: The cutting layer pattern and the mandrel pattern are strip structures.

5. The testkey for characterizing the overlay error measurement accuracy of the self-aligned imaging process according to claim 4, characterized in that: The number of the strip structures of the cutting layer pattern, the central pattern and the two side patterns is at least 5 respectively.

6. The testkey for characterizing the overlay error measurement accuracy of the self-aligned imaging process according to claim 1, characterized in that: The self-aligned imaging process includes SADP and SAOP.

7. The testkey for characterizing the overlay error measurement accuracy of the self-aligned imaging process according to claim 1, characterized in that: The graphics on both sides are graphics used for scaling.

8. An application method of the testkey for characterizing the overlay error measurement accuracy of the self-aligned imaging process according to claim 1, characterized in that: At least: Step 1: Before the trial production of the mask, a testkey is designed to obtain the testkey; Step 2: during trial production of the photomask, place the testkey close to the IBO or DBO photomask of the corresponding level; Step 3: In actual production, after the cutting layer of the testkey is completed, the testkey is measured using CDSEM, and the direct representation value of the overlay error is obtained through the difference between the etching mark of the cutting layer on the central pattern in the testkey and the CD measurement value between the two side patterns in the testkey; Step 4: perform point-to-point comparison of the overlay error obtained by the testkey with IBO or DBO to obtain the measurement accuracy of the IBO or DBO indirect measurement method.

9. The testkey application method for characterizing the overlay error measurement accuracy of the self-aligned imaging process according to claim 8, characterized in that: In step three, a direct representation value of the overlay error is obtained by the difference between the etching mark of the cutting layer on the central pattern in the testkey and the CD measurement value between the two side patterns in the testkey.

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