Method for monitoring metal deposition spalling defect of contact hole
By depositing titanium and titanium nitride films on test wafers and detecting peeling defects, the problem of wafer edge peeling defects during contact hole metal deposition was solved, achieving safety monitoring of the process environment and stability assurance before production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-29
- Publication Date
- 2026-03-13
AI Technical Summary
Existing technologies cannot effectively monitor the peeling defects of the metal layer at the edge of the wafer during the metal deposition process of the contact hole, which makes it difficult to guarantee the stability of the process. Furthermore, it requires small-batch trial production testing, which is time-consuming, labor-intensive, and can easily lead to product yield loss.
A method for monitoring metal deposition peeling defects in contact holes is provided. By depositing titanium film and titanium nitride film on a test piece and detecting peeling defects, the method determines whether the process environment is safe and ensures that the titanium film thickness is within a threshold range without peeling defects. An offline detection method is used to ensure process safety.
This allows for early detection of process environment safety before formal production, avoiding product yield loss caused by process instability and improving process stability and efficiency.
Smart Images
Figure CN121666035A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor technology, and in particular to a method for monitoring metal deposition peeling defects in contact holes. Background Technology
[0002] Contact hole metal layer deposition typically begins with the deposition of a titanium (Ti) film using physical vapor deposition (PVD), followed by the deposition of a titanium nitride (TiN) film on the titanium film surface using physical organic chemical vapor deposition (MOCVD). During metal layer deposition within the contact holes, the metal layer can extend to cover the wafer surface. The metal layer deposited on the wafer surface is prone to peeling defects at the wafer edge, typically between 0 and 0.2 mm.
[0003] Currently, there is no effective method in the industry to monitor the generation of peeling defects. The only way to determine the stability of the current stage of the process is through online defect detection of the product. However, because there is no clear indicator to characterize whether the current process environment will produce peeling defects, the only way to determine the stability of the process is to conduct small-batch pilot production (pi-run) to test it. But this method still cannot guarantee the stability of the process, and it is time-consuming, labor-intensive, and prone to causing product yield loss. Summary of the Invention
[0004] The purpose of this invention is to provide a method for monitoring metal deposition peeling defects in contact holes, in order to solve one or more problems in the prior art.
[0005] To address the aforementioned technical problems, this invention provides a method for monitoring metal deposition peeling defects in contact holes, comprising:
[0006] Provide test pieces;
[0007] A contact hole metal deposition process is performed on the test piece in a first process environment. The contact hole metal deposition process includes sequentially depositing a titanium film layer and a titanium nitride film layer. Specifically, when performing the contact hole metal deposition process on the test piece, the thickness of the deposited titanium film layer is a first thickness, which is less than or equal to a second thickness. The second thickness is the thickness of the titanium film layer deposited when performing the contact hole metal deposition process on a product piece.
[0008] The test piece is inspected for peeling defects after the contact hole metal deposition process is performed, and the safety of the first process environment is determined based on the inspection results.
[0009] Optionally, in the method for monitoring contact hole metal deposition peeling defects, the method is an offline detection method, which is performed before the contact hole metal deposition process is performed on the product sheet.
[0010] Optionally, in the method for monitoring metal deposition peeling defects in contact holes, the method further includes:
[0011] If the first process environment is determined to be safe, then the contact hole metal deposition process is performed on the product wafer under the first process environment.
[0012] Optionally, in the method for monitoring metal deposition peeling defects in contact holes, the method for determining whether the first process environment is safe based on the detection results includes:
[0013] If the test results show that there is a peeling defect, the first process environment is determined to be unsafe.
[0014] If the test results show that there are no peeling defects, then the first process environment is determined to be safe.
[0015] Optionally, in the method for monitoring metal deposition peeling defects in contact holes, the first thickness is less than the second thickness.
[0016] Optionally, in the method for monitoring metal deposition peeling defects in contact holes,
[0017] The method further includes performing the contact hole metal deposition process on the product wafer in a second process environment, wherein the first process environment is inferior to the second process environment.
[0018] Optionally, in the method for monitoring metal deposition peeling defects in contact holes, the method further includes:
[0019] When performing the contact hole metal deposition process on the product wafer in the first process environment, the actual environmental values are monitored, and the first process environment is adjusted according to the monitoring results to maintain the stability of the first process environment.
[0020] Optionally, in the method for monitoring contact hole metal deposition peeling defects, before performing the contact hole deposition process on the test piece, the method further includes:
[0021] The test piece is pre-cleaned to at least remove silicon oxide from its surface.
[0022] Optionally, in the method for monitoring metal deposition peeling defects in contact holes, detecting whether the test piece has peeling defects includes:
[0023] Detect whether there are unexpected pores; and / or,
[0024] Detect the presence of unexpected particles.
[0025] Optionally, in the method for monitoring metal deposition peeling defects in contact holes, the test piece may or may not have contact holes.
[0026] In summary, this invention provides a method for monitoring contact hole metal deposition peeling defects, comprising: providing a test piece; depositing a metal layer on the surface of the test piece in a first process environment, including depositing a titanium film layer of a threshold thickness on the surface of the test piece, and depositing a titanium nitride film layer on the titanium film layer; and detecting whether the test piece with the deposited metal layer has peeling defects, and determining whether the first process environment is safe based on the detection results. The method provided by this invention, by determining whether the first process environment meets the requirement that no peeling defects will occur under the threshold thickness condition of the titanium film layer, can guarantee or improve the safety of performing contact hole metal deposition on product pieces in the first process environment. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the structure after a metal layer is deposited on the surface of a wafer.
[0028] Figure 2 This is a schematic diagram of the structure after the metal layer deposited on the wafer surface undergoes a reaction;
[0029] Figure 3 A flowchart illustrating the steps of a method for monitoring metal deposition peeling defects in contact holes, as provided in an embodiment of the present invention. Detailed Implementation
[0030] Please see Figure 1 and Figure 2 The inventors discovered that the peeling defects that occur during the contact hole metal deposition process are due to:
[0031] N ions in the titanium nitride (TiN) film diffuse into the titanium (Ti) film under high temperature and plasma conditions to form titanium nitride. At the same time, titanium reacts with exposed silicon (Si) at the edge of the wafer to form titanium silicide (TiSi). The stress difference between titanium nitride and titanium silicide makes it easy to produce peeling defects.
[0032] Therefore, the thickness of the titanium film layer is crucial to whether peeling defects occur. In view of this, the present invention aims to provide a method for monitoring metal deposition peeling defects in contact holes. This method can ensure or improve the safety of the current process environment by determining whether the current process environment meets the requirement that no peeling defects will occur under the threshold thickness of the titanium film layer.
[0033] The method for monitoring metal deposition peeling defects in contact holes provided by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and use non-precise scales, used only to facilitate and clarify the illustration of the embodiments of the present invention. Furthermore, the structures shown in the drawings are often part of the actual structure. In particular, different figures may have different emphases and sometimes use different scales. It should be understood that relative terms such as "above," "below," "top," "bottom," and "upper" shown in the drawings can be used to describe the relationships between various elements. These relative terms are intended to cover different orientations of elements other than those depicted in the drawings. For example, if the device is inverted relative to the view in the drawings, an element described as "above" another element will now be below that element. It should also be understood that, unless specifically stated or indicated, the terms "first," "second," "third," etc., in the specification are only used to distinguish the various components, elements, steps, etc., in the specification, and are not used to indicate logical or sequential relationships between the various components, elements, steps, etc.
[0034] Example 1
[0035] Please see Figure 3 This embodiment provides a method for monitoring metal deposition peeling defects in contact holes, comprising the following steps:
[0036] S1 provides test pieces;
[0037] S2, In a first process environment, a contact hole metal deposition process is performed on the test piece, the contact hole metal deposition process including sequentially depositing a titanium film layer and a titanium nitride film layer; wherein, when the contact hole metal deposition process is performed on the test piece, the thickness of the deposited titanium film layer is a first thickness, the first thickness is less than or equal to a second thickness, and the second thickness is the thickness of the deposited titanium film layer when the contact hole metal deposition process is performed on the product piece;
[0038] S3, detect whether there are peeling defects in the test piece after performing the contact hole metal deposition process, and determine whether the first process environment is safe based on the detection results.
[0039] The method provided in this embodiment of the invention refers to the process environment in which the contact hole metal deposition process is performed on the product wafer. By determining whether the first process environment meets the requirement that no peeling defects will occur under the threshold thickness condition of the titanium film layer, the safety of performing the contact hole metal deposition process on the product wafer in the first process environment can be guaranteed.
[0040] Preferably, the method provided in this embodiment is an offline inspection method, which is performed before the contact hole metal deposition process is carried out on the product wafer. That is, before the contact hole metal deposition process is formally performed on the product wafer, the offline inspection method provided in this embodiment ensures the safety of the process environment for the contact hole metal deposition process.
[0041] First, ensure the safety of the process environment through offline testing before starting the formal contact hole metal deposition process. Compared with judging the stability of the process through small-batch trial production, this method can save time and effort and will not lead to product yield loss.
[0042] The method provided in this embodiment further includes: if it is determined that the first process environment is safe, then performing a contact hole metal deposition process on the product wafer in the first process environment.
[0043] Since the value of the first thickness determines the accuracy of the final judgment, to further improve the safety of the process environment, preferably, the first thickness is smaller than the second thickness.
[0044] Furthermore, it is understood that both the test wafer and the product wafer are silicon wafers or silicon-containing wafers. During the contact hole metal deposition process, the product wafer has already formed contact holes through etching, with the metal layer covering the sidewalls and bottom wall of the contact holes, as well as the surface of the product wafer; however, the test wafer may not have contact holes formed through etching, and the metal layer only covers the surface of the test wafer. Since peeling defects generally occur at the wafer edge (0-0.2 mm), using a test wafer without contact holes for testing can also serve to determine whether the first process environment is safe. Of course, in some other embodiments, the test wafer may also be a wafer with contact holes formed.
[0045] The method for determining whether the first process environment is safe based on the detection results may specifically include:
[0046] If the test results show the presence of peeling defects, the first process environment is deemed unsafe; if the test results show the absence of peeling defects, the first process environment is deemed safe.
[0047] The detection of whether the test piece has peeling defects includes: detecting whether there are unexpected pores (pores mainly exist between the test piece and the metal layer); and / or, detecting whether there are unexpected particles.
[0048] In this embodiment, the equipment for detecting whether the test piece is defective includes, but is not limited to, a scanning electron microscope (SEM), and this application does not impose any restrictions on it.
[0049] Preferably, the method provided in this embodiment further includes the following step: pre-cleaning the test piece to at least remove silicon oxide from the surface of the test piece.
[0050] When wafers are exposed to air, they react with the air to form silicon oxide. Pre-cleaning the test wafers can prevent the surface silicon oxide from affecting the test results.
[0051]
Example 2
[0052] As mentioned earlier, nitrogen ions in the titanium nitride film diffuse into the titanium film under high temperature and plasma conditions to form titanium nitride. Simultaneously, titanium reacts with exposed silicon at the wafer edge to form titanium silicide. Therefore, it can be understood that, in addition to the thickness of the titanium film, the environment is also a crucial factor affecting the degree of nitrogen ion diffusion and the extent of the reaction between titanium and silicon.
[0053] For contact hole metal deposition processes, fixed environmental values are typically provided, such as fixed temperature and pressure settings. However, the inventors have discovered that as the reaction proceeds, factors such as heat accumulation within the reaction chamber can cause deviations between the actual temperature and pressure and the set values. This can lead to discrepancies between the actual diffusion of nitrogen ions and the actual reaction degree between titanium and silicon. Consequently, even if the first process environment is deemed safe using the method described in Example 1, performing the contact hole metal deposition process on the product wafer under the first process environment may still result in the production of a product wafer with peeling defects.
[0054] Therefore, unlike Embodiment 1, in this embodiment, the contact hole metal deposition process is performed on the product wafer in a second process environment. The first process environment is inferior to the second process environment.
[0055] Since the test piece is tested in the degraded first process environment, when performing the contact hole metal deposition process on the product piece, even if the process environment deteriorates as production progresses and the actual process environment differs from the second process environment, it can be guaranteed that no peeling defects will occur.
[0056] It is understood that the first process environment and the second process environment are determined by multiple environmental values (including but not limited to the temperature and pressure mentioned above) set by each. For example, the first process environment may be inferior to the second process environment by setting the temperature value corresponding to the first process environment to be greater than the temperature value corresponding to the second process environment; or by setting the pressure value corresponding to the first process environment to be greater than the temperature value corresponding to the second process environment; or by setting the temperature and pressure values corresponding to the second process environment to be greater than the temperature and pressure values corresponding to the second process environment, respectively.
[0057] It should be noted that, in addition to what was mentioned above, temperature and pressure may increase as production progresses, leading to a deterioration of the process environment. There may also be other environmental values that decrease as production progresses, which also leads to a deterioration of the actual process environment. In this case, the environmental value set for the first process environment can be set to be lower than the environmental value set for the second process environment, so that the first process environment is inferior to the second process environment.
[0058] Using the method provided in this embodiment, even if the actual environmental values inside the reaction chamber change during formal production, the actual process environment can still be guaranteed to be safe.
[0059]
Example 3
[0060] As described in Example 2, the inventors discovered that as the reaction proceeds, factors such as heat accumulation in the reaction chamber can cause deviations between the actual temperature and pressure and the set values. This can lead to discrepancies between the actual diffusion of nitrogen ions and the actual reaction degree between titanium and silicon. Consequently, even if the method described in Example 1 is used to determine that the first process environment is safe, it may still result in the production of product wafers with peeling defects.
[0061] Therefore, unlike Example 2, in this example, the same process environment is used when performing the contact hole metal deposition process on the test piece and the product piece. On this basis, the stability of the process environment is maintained to avoid the actual results deviating from expectations due to environmental changes.
[0062] Specifically, in this embodiment, the method further includes: when performing the contact hole metal deposition process on the product wafer in the first process environment, monitoring the actual environmental values, and adjusting the first process environment according to the monitoring results to maintain the stability of the first process environment.
[0063] This ensures that the process environment during formal production is consistent with that during offline testing. Therefore, after confirming the safety of the current process environment through offline testing, it can be guaranteed that the product wafers undergoing the contact hole metal deposition process will not develop peeling defects under the current process environment.
[0064] In summary, embodiments of the present invention provide a method for monitoring contact hole metal deposition peeling defects, comprising: providing a test piece; performing a contact hole metal deposition process on the test piece in a first process environment, the contact hole metal deposition process comprising sequentially depositing a titanium film layer and a titanium nitride film layer; wherein, when performing the contact hole metal deposition process on the test piece, the thickness of the deposited titanium film layer is a first thickness, the first thickness is less than or equal to a second thickness, the second thickness being the thickness of the deposited titanium film layer when performing the contact hole metal deposition process on a product piece; and detecting whether the test piece after performing the contact hole metal deposition process has peeling defects, and determining whether the first process environment is safe based on the detection result. The method provided by embodiments of the present invention, by determining whether the first process environment meets the requirement that no peeling defects will occur under the titanium film layer threshold thickness condition, can guarantee or improve the safety of performing a contact hole metal deposition process on a product piece in the first process environment.
[0065] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to mutually. In addition, different parts between embodiments can also be combined with each other, and this invention does not limit this.
[0066] Furthermore, it should be understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention shall still fall within the scope of protection of the present invention.
Claims
1. A method for monitoring metal deposition peeling defects in contact holes, characterized in that, include: Provide test pieces; A contact hole metal deposition process is performed on the test piece in a first process environment. The contact hole metal deposition process includes sequentially depositing a titanium film layer and a titanium nitride film layer. Specifically, when performing the contact hole metal deposition process on the test piece, the thickness of the deposited titanium film layer is a first thickness, which is less than or equal to a second thickness. The second thickness is the thickness of the titanium film layer deposited when performing the contact hole metal deposition process on a product piece. The test piece is inspected for peeling defects after the contact hole metal deposition process is performed, and the safety of the first process environment is determined based on the inspection results.
2. The method for monitoring metal deposition peeling defects in contact holes as described in claim 1, characterized in that, The method is an offline inspection method, which is performed before the contact hole metal deposition process is carried out on the product sheet.
3. The method for monitoring metal deposition peeling defects in contact holes as described in claim 1, characterized in that, The method further includes: If the first process environment is determined to be safe, then the contact hole metal deposition process is performed on the product wafer under the first process environment.
4. The method for monitoring metal deposition peeling defects in contact holes as described in claim 1, characterized in that, The method for determining whether the first process environment is safe based on the detection results includes: If the test results show that there is a peeling defect, the first process environment is determined to be unsafe. If the test results show that there are no peeling defects, then the first process environment is determined to be safe.
5. The method for monitoring metal deposition peeling defects in contact holes as described in claim 1, characterized in that, The first thickness is less than the second thickness.
6. The method for monitoring metal deposition peeling defects in contact holes as described in claim 1, characterized in that, The method further includes performing the contact hole metal deposition process on the product wafer in a second process environment, wherein the first process environment is inferior to the second process environment.
7. The method for monitoring and controlling metal deposition spalling defects in wells as described in claim 1, characterized in that, The method further includes: When performing the contact hole metal deposition process on the product wafer in the first process environment, the actual environmental values are monitored, and the first process environment is adjusted according to the monitoring results to maintain the stability of the first process environment.
8. The method for monitoring metal deposition peeling defects in contact holes as described in claim 1, characterized in that, Before performing the contact hole deposition process on the test piece, the method further includes: The test piece is pre-cleaned to at least remove silicon oxide from its surface.
9. The method for monitoring metal deposition peeling defects in contact holes as described in claim 1, characterized in that, Detecting whether the test piece has peeling defects includes: Detect whether there are unexpected pores; and / or, Detect the presence of unexpected particles.
10. The method for monitoring metal deposition peeling defects in contact holes as described in claim 1, characterized in that, The test piece may or may not have contact holes.