TW508656B - Contact lithography process applying photoresist reflow to enhance process window - Google Patents

Abstract

There are disclosed a mask manufacturing method capable of enhancing process window and the related photolithography process. The method comprises, at first, establishing an optical proximity model for providing a relation between the critical dimension of developed pattern and the pitch of pattern, and establishing a hotoresist reflow model for providing a relation between the critical dimension of reflowed pattern and the pitch of pattern; then, forming a lithography mask based on the optical proximity model and the photoresist reflow model, wherein the critical dimension of the pattern on the lithography mask can be determined from the critical dimension and pitch of the pattern to be defined; then, using a mask to perform an exposure procedure to the photoresist material, wherein the exposed dense contact pattern and exposed isolated pattern have the same process window; then, developing the photoresist material to form the dense contact and isolated contact, wherein the isolated contact has a larger critical dimension than the dense contact; and performing a photoresist reflow procedure to reduce the critical dimensions of the dense contact and isolated contact, respectively.

Description

508656 V. Description of the invention (1) Field of the invention: The present invention relates to a semiconductor process, in particular, a lithography process using a photoresist reflow (ref low) technology to improve the process window. Background of the Invention: With the development, the accumulation of high-accumulation is also more and more important. The main thing is that micro-determines the structure of the product. First, the pattern, such as a stepper, has a semiconductor bottom that is close to the mask semiconductor. The key is in the production of the film circuit on the exposure material. The above is the same body circuit, which is used for the lithography to transfer the layers of each layer. The device on the photomask will be the same. The scale of the reduced accumulation piece is measured in a semiconducting process (1 transfers the pattern to the half. Then the photomask The development pattern has been continuously improved. In addition, the size of the chip has been reduced, and in terms of the component system process, the ability to determine the element (thography) needs to be patterned on the semiconductor substrate and the process of forming the entire semiconductor substrate In the exposure process, the borrowed pattern is transferred to the full coat ^ After the step is completed, the photoresistor ’s space between the symbols is accumulated 3, one by one. The force is applied again, and the resistive layer is often used in the body circuit. However, as semiconductor components are being transferred and defined, they are: extremely severe challenges. And Japanese clothing: Interfacing with technology needs to face solutions: translating and 'in the graph --- ---% resolution, focus depth

Relevant lithography process, both sides: continuous shrinking of the reticle 50S656 5. Invention description (2) (DOF), numerical aperture (NA), etc. trade off of process parameters, in order to maximize the process tolerance. For example, when making contact holes on a semiconductor substrate, when the contact hole pattern to be defined is dense, in order to increase the tolerance of the process, an off-axis illumination (0AI) method is often used, or ^ System ^ Improve the degree of coherence (sigma, σ, degree of coherence) in the lighting mode. However, in this way, for isolated contact patterns with larger pitches, their process tolerance will be reduced. In other words, in order to improve the process tolerance of the isolated contact hole pattern, the degree of interference can be reduced. However, this will cause a decrease in the density of the dense contact hole pattern, and increase the difficulty of the lithography process. He devoted himself to the key dimensions (CD) of process conditions and parameters, and maintained the tolerance of the process; after carrying the contact holes into the specifications below 0 · 18 "m, it was passed on again and again, when Dang Fan The size of the pieces are all bottlenecked, which makes the off-axis Zhao Mingcheng, * ... machinery and lithography process in this development trend, how to become an indispensable means of exposure procedures. In the process of 'improving process tolerance, has become: 3 holes The problem of pattern lithography. It is extremely important in the process of lithography conductors. In the traditional lithography process, the process is also used to prevent the reflow to define the contact hole pattern. Guangshi t described the problem. # 中 ， 可 _ On the material section, go back through the high-temperature program. Page 5 508656 5. Description of the invention (3) The size of the contact hole pattern is reduced. Because of the isolated contact hole pattern In terms of size reduction, it will be more obvious than the dense contact hole pattern. Therefore, when defining an isolated contact hole pattern, you can first define a larger size opening, and then reduce the size of the contact hole pattern to the size required by the reflow process. . As a result, By defining a contact hole with a larger size, the tolerance of the lithography process is improved. The purpose and summary of the invention: The purpose of the present invention is to provide a method for making a photomask. Another object of the present invention is to provide a method capable of simultaneously forming dense A method for opening patterns and isolated opening patterns in a photoresist material, wherein the dense opening patterns and the isolated opening patterns have the same absolute size, and their process tolerances are also equal. The present invention provides a method for making photomasks and related lithographic processes. Method. First, establish an optical proximity database. Among them, first use a test mask with a variety of test patterns to expose the photoresist material. The test patterns have different sizes, shapes, and spacings, and the exposure procedures meet the process specifications (spec ). Next, develop the photoresist material to form a test pattern. Then, based on the development of the test pattern, the absolute size of the test pattern changes with the pitch, and establish an optical proximity database. Then, create photoresistance reflow data. Library, in which a photoresist material having an opening pattern is reflowed

Page 6 5. Description of the invention (4) Procedure. According to the situation of the reflow connection, the optical limit reflow is established ;: Case J :: The size of the photoresistance reflow database system is changed with the distance ^ absolute size, pitch and preview of the optical proximity database used in light; capacity% is acceptable; Define the order of the patterns as you want, and develop the photoresist; use it! The photoresist is exposed to the photoresist material and the material is subjected to a reflow process; an opening diagram is formed: in it. # 对光 = The absolute size of the meaning pattern. The size of the mouthpiece pattern is small, and it meets the above-mentioned requirements. Detailed description of the invention: The present invention provides-种 制 # Wherein, by establishing light ;;;; mask: method and related lithography process. The relationship between spacing ,. And C shows the relationship between the size and the distance after the pattern is developed '. This way & fork type 'to display the size of the pattern after reflow. The door distance can be wrong. Based on these two models, the photo on the photomask is determined. As described below. The combination of Xiao + Zhi a, according to the method for making a lithographic mask in the present invention, first of all, an optical proximity model is established. Among them, a mask with a variety of test patterns can be used. The photoresist material on the substrate is subjected to the exposure procedure. Generally speaking, these test patterns have different sizes, shapes, and pattern pitches (p 丨 t ch). Take the first A, b picture as an example, 508656

(isolated) contact The contact hole patterns with smaller adjacent isolated contact hole patterns have a dense (d e n s e) arrangement and isolated hole patterns. In the first A diagram, the pitch P1 is densely connected. As for the first β picture, the phase 'has a larger pitch ρ 2. After conforming to the process specifications, the photoresist is used for pattern exposure. Use the above contact hole pattern == test pattern to form contact holes on the material. In particular, the above should be explained: the photoresistance range should be used; the idea is to make the focus value (F) and the exposure value (attUude) are in line with the specifications of the system (energy chart) Right # 人. In turn, the test conducted was "Hang Xu," which has a process tolerance that meets the needs.

After Ik, based on the results of the various tests described above, the association between the micro-obtainment (CD) and the pitch of the optical mouth tea into the political film production process was established for ten years. Taking the above-mentioned first alpha size example, before performing the exposure and development procedures, the absolute size of the pattern and the change in adjacent pitches are used to contact the hole library. In the first A and β diagrams, only two #quote sub-close-up data are shown. However, in practical applications, test patterns with various pitches can be used to obtain relevant data. Ding U shirt Refer to the second picture to connect the model. Among them, this figure and this optical display show the behavior curve of the optical proximity model made according to the above method, and

Page 8 V. Description of the invention (6) Under the conditions of the process specifications, after exposing the test patterns of the different μ, μ, and the same electricity, the absolute pattern of the development pattern on the light I and the material is only drawn. -A behavior curve comes in. It is worth noting that White 2 is 'Although the size of the test pattern' in the figure, the shape J, but in cross-applications, when the m curve. Therefore, in the established optical proximity database, multiple behavior curves will be reduced and changed by the manufacturer's manufacturing process. One: to provide absolute light, f @ 一 Λ ^ ”shoulder shirt pattern absolute Correlation between size and pitch. Taking the contact hole pattern of 庠 ί :: as an example, in the process of exposure and development, the process is as shown in the third figure. In #, the coating on the net j For the photoresist material layer 12, it will have dense contact 1 / t on the left side and isolated contact holes 16 on the right side, and both contact holes 14 and 16 have absolute dimensions M. After the photoresist material layer 12 can be subjected to a heating and reflow process to cause reflow during the melting process. When the photoresist material solidifies again, the sidewall of the contact hole will relax and form a dashed line in the figure. Shape. Among them, for dense = contact hole 14, the opening size will be reduced after reflow, but from D1 to]) 2. As for the isolated contact hole 16, the opening size will be significant. Zoom out, from the original D1 to D3. In other words, the original absolute size As for the contact holes 14 and 16, after the thermal reflow process, its absolute size will be reduced and there will be a difference. Therefore, after the photoresist reflow process is determined according to different photoresist material characteristics and process parameters,

508656 V. Description of the invention (7) The situation that the absolute size of the developed pattern changes with the pitch, and collect relevant data and information to establish a photoresistive reflow database. As mentioned above, subject to the minimum line width of the current semiconductor manufacturing process, off-axis lighting is widely used in lithography programs. Although it can improve the tolerance of dense pattern manufacturing, relatively isolated patterns with larger spacing have a poorer manufacturing process. Tolerance. In this regard, the present invention can be overcome by combining the above-mentioned optical proximity model and photoresistive reflow model. After determining the absolute size and pitch of the pattern to be made, the behavior curve in the optical proximity model and photoresistive reflow model can be referred to to determine the pattern size, pitch and shape on the photomask. With the optical proximity model, the relationship between the developed pattern and the pitch can be determined under the conditions that meet the process specifications. In this way, the pattern size can be selected according to the pitch of the pattern to be defined. Then, referring to the photoresist reflow model, we can know that the pattern size of the developed pattern is reduced after the reflow process. In this way, as long as the absolute size and pitch of the final pattern are determined in advance, the size and pitch of the mask pattern that meets the process specifications can be determined through the above two model data. In addition, 'it should be particularly pointed out' that due to the isolated pattern on the photoresist material, the pattern size will be greatly reduced after the reflow process, so when defining an isolated pattern, the larger size pattern can be exposed first (for example, 0 . 1 5 // m), and then reduce the size of the pattern through the reflow process (for example, to 0. 1 1 //

Page 10 508656 V. Description of the invention (8) m). Of course, for patterns with larger absolute sizes, the process tolerance will also be relatively increased. For isolated patterns with a large pattern pitch, it is possible to increase the depth of focus and allowable exposure energy by increasing the absolute size of the pattern. As for the definition of dense patterns, subject to the small reduction in the pattern size in the reflow process, when the pattern size for exposure is 0.13 // m, the pattern size may only be reduced to 0.1 by the reflow process. // m. Thus, although the sizes of the formed patterns are different in the exposure process, the same-sized patterns can be obtained after the thermal reflow process. Therefore, the operator can determine the size of the pattern on the photomask and the corresponding pitch according to the optical proximity database and the photoresistive reflow database, and make the required photomask. Please refer to the fourth figure, which shows the relationship between the absolute size of the pattern and the pitch after the photomask made according to the present invention is subjected to exposure development and reflow. After the photoresist material is exposed and developed, as shown by line A in the figure, the size of the developed pattern can increase with the pattern pitch. That is, the absolute size of the pattern will increase with the pitch on the produced mask. Then, a photoresistive thermal reflow procedure is performed. As mentioned above, since the size of the isolated pattern with a larger pitch is reduced more, the distribution of the absolute size of the pattern after reflow will be shown as line segment B. Obviously, the absolute size of the dense or isolated pattern on the photoresist material will be reduced to X after the photoresist return process. In other words, when the final absolute size of the pattern defined on the photoresist material is set to X, the produced mask pattern need only have the size distribution of the line segment A.

Page 11 508656

V. Description of the invention (9) When it is large, it can be used as a lithographic reference to the isolated picture, or it can be increased, that is, the process can be made to expose the pattern. The fifth pattern pitch is used in the pitch process. In accordance with the size tolerance of light, or, the larger the change in the focus of illumination, the larger the size of the invention will also increase in the process is displayed in the depth of focus, its exposure depth will also make Then, a pattern can be made by the method. In addition, the tolerance of system lighting according to the linearity of the light pattern will be larger. The isolated image makes the absolute size of the various patterns even more. Even if the off-axis lighting method is used to increase the degree of interference (σ), it can be maintained at a considerable level.诮 When the exposure procedure is performed in section A, follow. It can be clearly seen from the figure that the larger the size is, the more it is carried out. Therefore, although the focus depth of the increased interference scheme is reduced, the pattern definition processes under the pitch are all

With the same depth of focus, the distribution is horizontal as shown in the fifth figure. In other words, for exposure processes with different pattern pitches, the process tolerance can be maintained within a certain range, and patterns with different pitches but the same absolute size can be made in the photoresist material through subsequent reflow procedures.

The invention has considerable advantages. When the operator wants to define a pattern of any size and shape, he can use the optical proximity model and photoresistance reflow model described above to find a lithography method with optimized process tolerance, and thus = make corresponding light cover. Especially when the pattern to be defined includes non-f & set and isolated patterns, the absolute size of the pattern after lithography and reflow can be obtained through the two models mentioned above, and in accordance with the requirements of the process specifications Common process tolerance for dense and isolated patterns

Page 12 508656 V. Description of invention (ίο) w i n d 〇 w) can be increased as much as possible. Although the present invention is explained as above with a preferred example, it is not intended to limit the spirit and the inventive substance of the present invention, but only to this embodiment. For those skilled in the art, modifications made without departing from the spirit and scope of the present invention should be included in the scope of patent application described below.

Page 508656 Brief description of the diagrams Through the following detailed description combined with the attached drawings, the above content and the many advantages of this invention can be easily understood, of which: The first A and B diagrams show the exposure process according to the present invention The dense contact hole pattern and the isolated contact hole pattern; the second figure shows the behavior curve diagram of the optical proximity model made according to the present invention to show the relationship between the pattern size and the pitch after development; the third figure shows the relationship between the The photoresist material of the contact hole pattern undergoes the thermal reflow process; the fourth figure shows the relationship between the pattern size and the pitch before and after the photoresist reflow process according to the present invention; and the fifth figure shows the lithography process according to the method of the present invention. The relationship between focus depth and pattern spacing. Drawing number comparison table 1 0 Semiconductor substrate 1 2 Photoresistive material 1 4 Dense contact hole 1 6 Isolated contact hole «

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Claims (1)

1 · A method for making a mask of M scene, Fang, & includes the following steps: 4 method at least the case door: Γ f learns the close-type branch to provide the absolute size of the pattern P1 pitch after development Correlation; Ding Xingtu established a photoresistive reflow model, pe _ ^ α is the correlation between the absolute size of the pattern and the respacing of the pattern after reflow; and b. Xingtu is based on the optical proximity model and the cover, which can be defined according to the desire The absolute size of the pattern on the pattern shadow mask. The absolute size and pitch of the micro-parameters produced by this photoresistive reflow model will affect the optical, shape, and process machines mentioned above. 2. As described in item 丨 of the patent application, the proximity of the model should be at least a spoon. I includes the pattern rule d. If the reason for the patent application reflow model, the method of at least spoon = item, which affects the above light to 乂 includes the characteristics and process parameters of the photoresist i. Taimu, Mu, Gansu L connection model also includes the following steps. // //, the above-mentioned light is used to have an exposure program with a variety of reading maps, where: 光: mask, the photoresist on the substrate tea Pitch, and the size and shape of the exposure program, I j, the development of the photoresist material 2 H meets the requirements; medium; and y Wang Xu, and the test pattern is formed in 508656 6. Scope of patent application The optical proximity model is established based on the absolute size and pitch of the test pattern after development. 5. For the method in the fourth item of the patent application, in which the focus depth and exposure energy allowable value of the above-mentioned exposure procedure all meet the requirements of the process specifications. 6. The method according to item 4 of the patent application, wherein establishing the photoresist reflow model further includes the following steps: a thermal reflow process is performed on the photoresist material, wherein the absolute size of the test pattern is reduced; and The absolute size and pitch of the test pattern is used to establish the photoresist reflow model. Fan Li specially asked Shen Ru to have a pole cover, a contact cover, and a light cover on the middle and large poles. The distance from the French side and the project hole contact the dense large picture hole. The contact set Mihai = ° is better than the contact with the pattern hole. In addition, the rule of the case must be applied to the picture. Fan Li specially requested to apply such a sequence. Cheng Wei 8. The travel mask is as small as the light to use it. The following steps are included in the steps below: The exposure is the same as that of the medium, and the ordering process is to make the exposure of the exposure line to the receiving material stand alone. The light and the exposure mask and the light case use the hole to make the contact set its hole. The contact dense forming is made of materials to block the light, and the shadow shows tolerance. Page 16 508656 VI. The isolated contact hole in the scope of the patent application has a larger absolute dimension than the contact hole I t %% μ and also sets the contact hole reflow procedure, and the absolute size of the contact hole is like ^ ^ ^ . 〃 m Xuanxiong 1 contact hole and the isolation 9. The method according to item 8 of the patent application scope, wherein after performing the above-mentioned light sequence, the dense contact hole has the same size as the isolated contact hole. 10 coating light construction pattern construction light construction mask, the process capacity is profitable, small, and 11 light is close. A resist material stands for the optical distance of the phase, the phase of the optical distance is the tolerance of the light, use the The lithography, photoresist, and photoresist meet the above definition. The near-contact reflow method is based on the method of determining the pattern of the photoresist material on the substrate. The method on the substrate includes at least the following steps: database, To provide the absolute size of the pattern after development and the material library, to provide the absolute size of the pattern after reflow and the connection database and the photoresistive reflow database to make a lithography. To define the absolute size, pitch and predetermined lithography mask of the pattern The size of the pattern on the mask; the mask performs an exposure procedure on the photoresist material; Φ material to form an opening pattern therein; and a reflow process is performed to reduce the size of the opening pattern to define the absolute size of the pattern. -• Times! The method of applying for item 10 in the scope of patent application, wherein the establishment of the library, library, and library mentioned above further includes the following steps: Page 17 508656 VI. Patent application scope Use a test mask with multiple test patterns to perform an exposure procedure on the first photoresist material, where the test patterns have different sizes, shapes, and spacings, and the exposure procedure meets process specifications ( spec) requirements; developing the first photoresist material to form the test pattern therein; and establishing the optical proximity database according to a situation where the absolute size of the test pattern after development changes with the pitch. 12. For the method according to item 11 of the scope of patent application, in which the above-mentioned focus depth and exposure energy allowable value of the first photoresist material are in accordance with the process specifications. || 13. If the method of applying for item 10 of the patent scope, wherein establishing the photoresistive reflow database, further includes the following steps: a reflow procedure is performed on the second photoresist material, wherein the second photoresist material has an opening pattern And according to the situation that the absolute size of the opening pattern after reflow varies with the distance, 'the photoresist reflow tribune is established. 14. For the method of applying for item 10 of the patent scope, in establishing the above-mentioned optical proximity database, the classification is based on different test pattern sizes, shapes, and P-process tools. 15. For the method of applying for item 10 of the patent scope, in which the above Page 18 508656 VI. Scope of patent application In the photoresistive reflow database, classification is based on different photoresist material characteristics and process parameters. Guang Liying solitaryly described the middle distance of the upper pole, and the method of the project item hole 10 touched the second set of fans. Fan Mili's special school please ask for a distance of 16 including the cover hole contact set. Mihai = ° It is better to have a hole in the picture and contact it. The size and scale of the case must be completely clear, and the case should be displayed in the hole. The medium touches the connection dimension, the hole with the lonely method and the large contact hole 14 contact the first set of enclosing dense Fan Chengli shape. This can be compared. If there is a hole, the material touches 17 The blocking phase of Guang Li San Gu Su Ju Ju ’s advancement phase has a hole in it, and touches the method of Fang Li ’s solitary item. The 15 and the hole surrounds Fan Fan Li Ji. Secret Master Yue Xuan-Φ 5, as follows sequence. 18 Cheng inch flow ruler back to right ♦ page 19