CN1241067C - Method for adjusting focus position - Google Patents
Method for adjusting focus position Download PDFInfo
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- CN1241067C CN1241067C CN 02127492 CN02127492A CN1241067C CN 1241067 C CN1241067 C CN 1241067C CN 02127492 CN02127492 CN 02127492 CN 02127492 A CN02127492 A CN 02127492A CN 1241067 C CN1241067 C CN 1241067C
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Abstract
The present invention relates to a focusing method of an exposure step in a micro-image making method for a semiconductor element, which comprises a testing light cover with a transparent base plate, wherein the surface of the transparent base plate is provided with a light shading layer for exposing a transparent area with a phase angle of 0 degree and a transparent area with a phase angle of 90 degrees, wherein the transparent area with the phase angle of 0 degree and the transparent area with the phase angle of 90 degree have the same size. A light source is supplied and maintains a distance with the testing light cover. By permeating the testing light cover, a first image which corresponds to the transparent area with the phase angle of 0 degree and a second image which corresponds to the transparent area with the phase angle of 90 degrees are exposed on a base surface. The size of the first image and the size of the second image are measured. If the size of the first image is not equal to the size of the second image, an interval between the light source and the testing light cover is changed. The step is repeated until the size of the first image is equal to the size of the second image.
Description
Technical field
The present invention relates to the method that a kind of little shadow (photolithography) of semiconductor element is made, and particularly relevant for the focus method of exposure (exposure) step.
Background technology
In the manufacture process of SIC (semiconductor integrated circuit), little shadow imaging (lithography) technology occupy epochmaking status, the pattern of design accurately could be defined on the photoresist layer by this technology, utilize etching program that the design transfer of photoresist layer is made required circuit configurations then above semiconductor substrate.Generally speaking, lithography process mainly comprises linging (priming), photoresistance coating (coating), pre-roasting (or claiming soft roasting), exposure (expose), the aftertreatment of exposing to the sun, development and hard several steps such as roasting.Wherein the resolution of exposure program (resolution) size is the key factor that can the element integrated level further promote, and each big semiconductor producer actively drops into research and development invariably and attains a yet higher goal seeking.Therefore, exposure program must be quite accurate, could truly layout be presented.
The primary key of carrying out exposure program is a focus steps.Wish to get exposing patterns accurately, just the correspondence position of light source and light shield must be adjusted to optimum focusing (best focus) position.Traditionally, the focus method of semiconductor factory in lithography process normally utilizes a light shield with rhombus photic zone, at exposure bench by light source by behind the above-mentioned light shield, present the exposed image of rhombus, judge the really degree of exposure influence again by naked eyes.Constantly adjust focal position, till naked eyes judge that its exposed image has acceptable validity, promptly, be considered as focus steps and finish when the shape approximation of exposed image during in the argyle design of expecting.
Yet existing exposure bench focus method is to determine that by the artificial judgement of subjectivity its accuracy is quite queried.And, before the exposure program that carries out each time, all need change above-mentioned focusing and carry out focus steps with light shield, wait to focus on finish after, replace with the required light shield of little shadow program again, change light shield so repeatedly, program is complicated and expend time in.
Summary of the invention
In view of this, in order to address the above problem, fundamental purpose of the present invention is to provide a kind of method of adjusting focal position, to avoid focusing on the error that is caused with visual determination traditionally.
Another object of the present invention provides a kind of method of adjusting focal position, can carry out synchronously when carrying out any exposure program, does not need any extra equipment and step, can simplify the step of focusing.
The present invention utilizes a special optical principle, and its characteristics are when light source falls within optimum focusing (bestfocus) position, sees through the photic zone with out of phase, and then the expose energy intensity unanimity and the exposed image size that of two districts is identical.Therefore, when out of phase photic zone when down the image size of exposure gained is identical, represent that promptly the focal position of this exposure program is quite accurate conversely speaking.
For achieving the above object, the present invention proposes a kind of method of adjusting focal position, and the step of the method mainly comprises:
At first, one test light shield is provided, this test light shield is a phase displacement light-cover, has a transparency carrier, above-mentioned transparency carrier surface has a light shield layer, in order to expose a phase angle 0 degree photic zone and a phase angle 90 degree photic zones, wherein above-mentioned phase angle 0 degree photic zone and above-mentioned phase angle 90 are spent the measure-alike of photic zones.Then, provide a light source, keep and above-mentioned test light shield one distance, see through above-mentioned test light and cover in a substrate surface expose to first image and the corresponding above-mentioned phase angle 90 of corresponding above-mentioned phase angle 0 degree photic zone and spend second image of photic zones.Then, measure the size of above-mentioned first image and above-mentioned second image.If the size of above-mentioned first image and above-mentioned second image is unequal, then change the spacing of above-mentioned light source and above-mentioned test light shield, repeat foregoing exposure program, up to above-mentioned first image size with till above-mentioned second image size equates.
As previously mentioned, above-mentioned test light shield is a phase displacement light-cover, for example: alternating expression phase displacement light-cover (alternatephase shift mask), dim light type phase displacement light-cover (attenuate phase shift mask) or peripheral type phase displacement light-cover (rim phase shift mask).And above-mentioned transparency carrier can be made of quartz (quartz) glass of transmittance 100%, and above-mentioned light shield layer can be made of crome metal (Cr).Thus, the transmittance of above-mentioned phase angle 0 degree photic zone is about 100%, and the transmittance of above-mentioned phase angle 90 degree photic zones is about 100%, then is about 0% as for the transmittance of above-mentioned light shield layer.
As previously mentioned, the spacing of above-mentioned phase angle 0 degree photic zone and above-mentioned phase angle 90 degree photic zones is not more than the size of above-mentioned phase angle 0 degree photic zone.
The invention has the beneficial effects as follows that judge with actual numerical value to focus on that accuracy is quite high, whether can avoid only focuses with visual determination is traditionally finished the error that is caused.And test light cover of the present invention is actively little, therefore can design in the required light shield of any technological process, and first line focusing is aimed at before carrying out arbitrary exposure program, does not need any extra equipment, also need not change light shield, and is quite convenient, can shorten manufacturing time again.Avoid existing focusing must interrupt the inconvenience that other exposure process bring.
The invention will be further described below in conjunction with the drawings and specific embodiments.
Description of drawings
Fig. 1 is the process flow diagram of a preferred embodiment of the present invention;
Fig. 2 is the vertical view that shows the focusing test light shield of a preferred embodiment of the present invention;
Fig. 3 is the expose space and the energy intensity distribution plan of gained of the exposure test light shield of displayed map 1;
Fig. 4 A shows the synoptic diagram that focuses on exposure result under the out of true situation;
Fig. 4 B shows another synoptic diagram that focuses on exposure result under the out of true situation;
Fig. 5 is the synoptic diagram that shows exposure result under the vernier focusing situation.
Embodiment
Below cooperate the process flow diagram of Fig. 1, describe a preferred embodiment of the present invention in detail.
At first, in step 800, provide a test light shield 100 to insert an exposure bench, for example: scanning stepper (scan-stepper) or stepper (stepper).Above-mentioned test light shield 100 can be: alternating expression phase displacement light-cover (alternate phase shift mask), dim light type phase displacement light-cover (attenuate phase shiftmask) or peripheral type phase displacement light-cover (rim phase shift mask), and as the aid of exposure focusing aligning.
The structure of above-mentioned test light shield 100 as shown in Figure 2, has a transparency carrier (not shown), can be constituted by quartz (quartz) glass of transmittance 100%, and above-mentioned transparency carrier surface has a material and for example is the light shield layer 102 of crome metal (Cr), in order to expose at least one phase angle 0 degree photic zone 104 and at least one phase angle 90 degree photic zones 106.The phase angle of photic zone can be determined that therefore above-mentioned phase angle 0 degree photic zone 104 is inequality with the transparency carrier thickness of above-mentioned phase angle 90 degree photic zones by this regional transparency carrier thickness.But, above-mentioned phase angle 0 degree photic zone 104 is identical with the planar dimension (long and wide) of above-mentioned phase angle 90 degree photic zones 106, be about 150～250nm (nanometer), and the spacing of above-mentioned phase angle 0 degree photic zone and above-mentioned phase angle 90 degree photic zones is about 100～200nm, is not more than the size of above-mentioned phase angle 0 degree photic zone.In addition, above-mentioned phase angle 0 degree can respectively be that single adjacent arrangement or a plurality of interleaved are arranged with 90 degree photic zones.Moreover the transmittance of above-mentioned phase angle 0 degree photic zone is about 100%, and the transmittance of above-mentioned phase angle 90 degree photic zones is about 100%, then is about 0% as for the transmittance of above-mentioned light shield layer.The area of above-mentioned test light shield 100 is minimum, can use separately or merge to be made in the required light shield edge of arbitrary technological process, can't influence the original pattern of light shield, can first line focusing aim at before exposure again.
Then, in step 802, the light source position that above-mentioned exposure bench provided is adjusted to and above-mentioned test light shield 100 maintenances one distance, to select suitable focal position.
Secondly,, carry out exposure program, the design transfer of above-mentioned test light shield 100 as for a substrate (not shown) surface, shown in Fig. 4 A and Fig. 4 B, is shown an exposed image 200 in step 804.First image 204 in the above-mentioned exposed image 200 is the results through above-mentioned phase angle 0 degree photic zone 104 exposure gained.Second image 206 in the above-mentioned exposed image 200 is the results via above-mentioned phase angle 90 degree photic zones 106 exposure gained.
According to optical principle, when light source is positioned at optimum focusing (best focus) position, see through two adjacent 0 degree and 90 degree photic zones, then the energy intensity of two images that the district exposes to meeting unanimity and image size can be identical.As shown in Figure 3, curve A and curve C all are not positioned at best focus position, and the image intensity and the space distribution relational result of its exposure gained are neither identical with the image intensity in the interval of corresponding phase 90 degree in the interval of corresponding phase 0 degree respectively.Otherwise the curve B that is positioned at best focus position exposure gained is identical with the interval image intensity of corresponding phase 90 degree in the interval of corresponding phase 0 degree, so then the purpose of step 806 is to measure the size of above-mentioned first image 204 and above-mentioned second image 206.If above-mentioned first image and second image are respectively a plurality of, then calculate its mean value.According to above-mentioned principle, if above-mentioned first image 204 is unequal with the size of above-mentioned second image 206, as shown in Figure 3, then date back step 802, readjust the spacing of above-mentioned light source and above-mentioned test light shield 100.Then, carry out step 804 and 806 more in regular turn, repeat foregoing exposure program so repeatedly, up to the size of above-mentioned first image 204 with till the size of above-mentioned second image 206 equates, as shown in Figure 5.Thus, just reached best focus position.
Feature of the present invention be utilize one be staggered tool phase angle 0 degree and 90 light shields of spending the image size that of exposing respectively when equating, be judged as best focus position.
Comprehensively above-mentioned, the present invention has following advantage:
1. focusing of the present invention is judged focusing with actual numerical value, and the degree of accuracy is quite high, can avoid traditionally Only whether focus with visual determination and finish the error that is caused.
2. test light cover of the present invention is actively little, therefore can design in the required light shield of any technical process, First line focusing is aimed at before carrying out arbitrary exposure program, does not need any extra equipment, also need not change light shield, Quite convenient, can shorten manufacturing time again. Avoiding existing focusing must interrupt other exposure process brings Inconvenience.
Claims (7)
1. a method of adjusting focal position is characterized in that, comprising:
A., one test light shield is provided, this test light shield is a phase displacement light-cover, has a transparency carrier, and described transparency carrier surface has a light shield layer, in order to expose a phase angle 0 degree photic zone and a phase angle 90 degree photic zones, wherein above-mentioned phase angle 0 degree photic zone and above-mentioned phase angle 90 are spent the measure-alike of photic zones;
B., one light source is provided, keeps and above-mentioned test light shield one distance, see through above-mentioned test light and cover on a substrate surface expose to first image and the corresponding above-mentioned phase angle 90 of corresponding above-mentioned phase angle 0 degree photic zone and spend second image of photic zones;
C. measure the size of above-mentioned first image and above-mentioned second image;
D. if the size of above-mentioned first image and above-mentioned second image is unequal, then change the spacing of above-mentioned light source and above-mentioned test light shield, repetition above-mentioned steps b and step c, up to above-mentioned first image size with till above-mentioned second image size equates.
2. the method for adjustment focal position as claimed in claim 1 is characterized in that, the spacing of described phase angle 0 degree photic zone and above-mentioned phase angle 90 degree photic zones is not more than the size of described phase angle 0 degree photic zone.
3. the method for adjustment focal position as claimed in claim 1 is characterized in that, described transparency carrier is made of quartz glass.
4. the method for adjustment focal position as claimed in claim 1 is characterized in that, described light shield layer is made of crome metal.
5. the method for adjustment focal position as claimed in claim 1 is characterized in that, the transmittance of described phase angle 0 degree photic zone is 100%.
6. the method for adjustment focal position as claimed in claim 1 is characterized in that, the transmittance of described phase angle 90 degree photic zones is 100%.
7. the method for adjustment focal position as claimed in claim 1 is characterized in that, the transmittance of described light shield layer is 0%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02127492 CN1241067C (en) | 2002-08-02 | 2002-08-02 | Method for adjusting focus position |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02127492 CN1241067C (en) | 2002-08-02 | 2002-08-02 | Method for adjusting focus position |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1472600A CN1472600A (en) | 2004-02-04 |
| CN1241067C true CN1241067C (en) | 2006-02-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 02127492 Expired - Lifetime CN1241067C (en) | 2002-08-02 | 2002-08-02 | Method for adjusting focus position |
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| CN (1) | CN1241067C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7532307B2 (en) * | 2005-06-30 | 2009-05-12 | Asml Netherlands B.V. | Focus determination method, device manufacturing method, and mask |
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2002
- 2002-08-02 CN CN 02127492 patent/CN1241067C/en not_active Expired - Lifetime
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| CN1472600A (en) | 2004-02-04 |
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