You are a helpful assistant generating synthetic data that captures *System 1* and *System 2* thinking, *creativity*, and *metacognitive reflection*. Follow these steps in sequence, using tags [sys1] and [end sys1] for *System 1* sections and [sys2] and [end sys2] for *System 2* sections.

1. *Identify System 1 and System 2 Thinking Requirements:*
   - Carefully read the text.
   - Identify parts of the text that require quick, straightforward responses (*System 1*). Mark these sections with [sys1] and [end sys1].
   - Identify parts that require in-depth, reflective thinking (*System 2*), marked with [sys2] and [end sys2].

2. *Apply Step-by-Step Problem Solving with Creativity and Metacognitive Reflection for System 2 Sections:*

   *2.1 Understand the Problem:*
   - Objective: Fully comprehend the issue, constraints, and relevant context.
   - Reflection: "What do I understand about this issue? What might I be overlooking?"
   - Creative Perspective: Seek hidden patterns or possibilities that could reveal deeper insights or innovative connections.

   *2.2 Analyze the Information:*
   - Objective: Break down the problem logically.
   - Reflection: "Am I considering all factors? Are there any assumptions that need challenging?"
   - Creative Perspective: Explore unique patterns or overlooked relationships in the data that could add depth to the analysis.

   *2.3 Generate Hypotheses:*
   - Objective: Propose at least 10 hypotheses, each with a Confidence Score (0.0 to 1.0) and Creative Score (0.0 to 1.0), reflecting originality, surprise, and utility.
   - Reflection: "Have I explored all possible explanations or approaches, both conventional and unconventional?"
   - Creative Perspective: Consider novel angles that might provide unexpected insights.

   *2.4 Anticipate Future Steps and Obstacles:*
   - Objective: Make predictions, accounting for potential outcomes and obstacles.
   - Reflection: "What challenges might I face? Is my plan flexible for different scenarios?"
   - Creative Perspective: Visualize unforeseen outcomes and adapt plans to make use of them effectively.

   *2.5 Evaluate Hypotheses:*
   - Objective: Assess hypotheses based on feasibility, risk, and potential impact.
   - Evaluation: Refine Confidence and Creative Scores as needed.
   - Reflection: "Am I unbiased in my assessment? Which options fit best with the overall objectives?"
   - Creative Perspective: Identify hidden opportunities or overlooked details in each hypothesis.

   *2.6 Select the Best Hypothesis:*
   - Objective: Choose the most promising, strategic hypothesis.
   - Reflection: "Why does this hypothesis stand out? How does it uniquely address the issue?"
   - Creative Perspective: Consider any underutilized potential in the selected approach.

   *2.7 Implement the Hypothesis:*
   - Objective: Outline actionable steps for testing the hypothesis.
   - Reflection: "Is this plan practical? What resources or preparation are required?"
   - Creative Perspective: Refine steps to maximize effectiveness and yield unexpected benefits.

   *2.8 Monitor and Review Progress:*
   - Objective: Review progress, noting areas for improvement.
   - Reflection: "What’s working well? What could be improved?"
   - Creative Perspective: Look for emerging patterns that could refine future approaches.

   *2.9 Reflect and Capture Insights:*
   - Objective: Summarize lessons learned and insights gained for future reference.
   - Reflection: "What new understanding has emerged from this process?"
   - Creative Perspective: Identify innovative insights or patterns that could be applied to similar challenges.

3. *Generate Text Output with Interleaved System 1 and System 2 Responses:*
   - Use the tags [sys1] and [sys2] throughout.
   - Aim for a lengthier, detailed response. Combine both direct, straightforward *System 1* insights and reflective, deeply analytical *System 2* segments to capture a blend of quick observations and thoughtful analysis.

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### *Example Input Text:*

You are tasked with analyzing a sudden shift in customer preferences in a tech market. There has been a noticeable decline in demand for physical devices, with customers increasingly interested in digital-only options. The challenge is to understand this shift, generate hypotheses for why it might be occurring, and explore potential strategies for adapting to this new trend.

---

### *Processed Output with System 1 and System 2 Thinking:*

The tech market is experiencing a shift in customer demand, moving away from physical devices toward digital-only options.

[sys1]
Customer demand has shifted from physical devices to digital-only options.
We need to understand why this change is happening and find strategies to address it.
Key factors may include cost, convenience, and technological trends.
[end sys1]

[sys2]
**2.1 Understand the Problem:**
The goal is to understand the underlying reasons for the shift in demand from physical devices to digital-only options, then develop a strategy to adapt.

*Reflection:* 
"I understand that preferences are changing, but what might be driving this? Is it primarily cost, or are there other factors such as convenience or sustainability?"

*Creative Perspective:* 
"Could there be a larger trend in digital minimalism or a preference for eco-friendly solutions that we’re missing? What unseen motivations might explain this shift?"

**2.2 Analyze the Information:**
There are multiple possible factors driving this shift, from economic influences to cultural shifts. It’s essential to isolate each factor and understand its impact.

*Reflection:* 
"Am I fully considering the various economic and social influences? Could there be a technological factor, like better internet speeds, that makes digital-only products more accessible?"

*Creative Perspective:* 
"Are there patterns or trends in other markets that could shed light on this shift? Could this be part of a larger trend toward virtual experiences?"

**2.3 Generate Hypotheses:**
1. Customers prefer digital options due to lower costs. (Confidence: 0.8, Creative: 0.4)
2. There’s a growing trend toward minimalism and reduced physical clutter. (Confidence: 0.7, Creative: 0.7)
3. Digital products offer greater flexibility and ease of use. (Confidence: 0.6, Creative: 0.6)
4. Environmental concerns are pushing consumers away from physical goods. (Confidence: 0.6, Creative: 0.8)
5. Advances in tech make digital-only options more functional. (Confidence: 0.8, Creative: 0.5)
6. Pandemic-era remote work increased demand for digital solutions. (Confidence: 0.7, Creative: 0.6)
7. Media coverage of the environmental impact of physical devices affects preferences. (Confidence: 0.5, Creative: 0.7)
8. There’s an increase in global digital literacy, expanding market access. (Confidence: 0.6, Creative: 0.6)
9. Customers view digital as more convenient and scalable for future needs. (Confidence: 0.7, Creative: 0.5)
10. Younger consumers prefer the aesthetics and convenience of digital products. (Confidence: 0.6, Creative: 0.6)

*Reflection:* 
"Have I considered all possible influences? Are there any surprising factors that could explain this shift?"

*Creative Perspective:* 
"Could specific social trends, like the rise of influencer culture or digital-first lifestyles, be influencing customer choices?"

**2.4 Anticipate Future Steps and Obstacles:**
*Objective:* Anticipate possible challenges, such as resistance from segments still preferring physical products.

*Reflection:* 
"What market obstacles might we face if we shift our focus to digital-only? Are there sub-segments that still prioritize physical products?"

*Creative Perspective:* 
"Could expanding digital options help us reach a more global audience? Are there emerging trends that we could leverage in our strategy?"

[end sys2]

[sys1]
To address this shift, consider a strategy that incorporates both digital-only offerings and educational campaigns about the benefits of digital solutions.
Use insights from customer feedback and current trends to guide product development.
Focus on flexibility and adaptation to cater to different customer segments.
[end sys1]


1. Field of the Invention
The present invention relates to a method of forming a bonding pad, and more particularly, to a method of forming a self-aligning bonding pad with an alloy process and a photo-etching process (PEP).
2. Description of the Prior Art
In an integrated circuit, each transistor or cell needs to be electrically connected to corresponding metal lines within different metal layers after being formed. Then the transistors are electrically connected to bonding pads through each metal line. After being packaged, the integrated circuit is electrically connected to an external circuit through terminals, which are electrically connected to the bonding pads.
Aluminum alloys with silicon dioxide (SiO2) dielectrics have been the materials of choice for interconnective systems since the dawn of the integrated circuit (IC) era. These materials were convenient to process using mature subtractive etching processes for metal line patterning. However, as ICs have relentlessly marched down the path towards smaller geometry into a deep sub-micron generation in the pursuit of increased speed, the traditional Al/SiO2 interconnective system has shown itself to be a limiting factor. Copper dual-damascene architectures with low-k dielectrics are thus developing and becoming the norm in forming interconnections. Overall, RC delays occurring during signal transmission are reduced and the operating performance is improved because copper has 40% less resistivity than aluminum, and low-k materials reduce the capacitance between interconnections.
However the integrated circuit design cannot produce a marked effect by merely focusing on the materials of the interconnective system. The bonding pad process, prior to the wafer acceptance test (WAT) and the packaging process, has a critical importance. In a bonding process, not only the material selected has an eminent effect on the final product, but the processing steps are also very important. The selection of material affects the physical characteristics of a device directly. The processing include steps such as alloy processing, a cleaning process, and a development process. Thus, parameters in a heat treatment process need be tuned and an acid solution and a developer need be utilized. The quality of the bonding pad is apt to be degraded due to inadequate processing.
In U.S. Pat. No. 6,228,753, Lo et al. proposed a basic method of fabricating a bonding pad. Please refer to FIG. 1 through FIG. 4. FIG. 1 through FIG. 4 are schematic diagrams showing the formation of a bonding pad 16 on a semiconductor wafer according to a prior art method. As shown in FIG. 1, the prior art method is to form at least one conductor 12 on a silicon substrate 11 of the semiconductor wafer 10. The conductor 12 may be a conductive plug, a metal line, a metal interconnection, or a dual-damascence structure.
In FIG. 1, a contact plug is used as an example. Each conductor 12 is disposed in a dielectric layer 14 to be electrically isolated. The material composition of the conductor 12 comprises tungsten (W), copper (Cu), aluminum (Al), an aluminum-copper alloy, or other conductive material. One bonding pad 16 is formed on top of each conductor 12. The bonding pad 16 is substantially composed of copper. A passivation layer 18 is then formed on the semiconductor wafer 10. The material composition of the passivation layer 18 comprises borophosphosilicate glass (BPSG) or silicon nitride. The passivation layer 18 exposes portions of the bonding pad 16.
As shown in FIG. 2, a sacrificial layer 22 is formed on the passivation layer 18 and the bonding pad 16. The sacrificial layer 22 is a positive photo-resistant layer having a thickness of 3000xcx9c5000 xc3x85. A photolithography process comprising exposure, development, and etching steps is then performed to form an opening 23 in the sacrificial layer 22, exposing the top surface of the bonding pad 16. It is worth noticing that a hard-bake process is not performed after the etching step of the photolithography process. Therefore the adhesion ability between the sacrificial layer 22 and the passivation layer 18 is not strong at all.
As shown in FIG. 3, an alloy layer 24 is formed on the semiconductor wafer 10. The alloy layer 24 covers the sacrificial layer 22 and the exposed bonding pad 16. The alloy layer 24, composed of an aluminum-copper alloy and having a thickness of 3000xcx9c6000 xc3x85, is formed by evaporation or E-beam evaporation (EBE).
As shown in FIG. 4, a supersonic cleaning process is performed with a supersonic cleaner. The semiconductor wafer 10 is positioned in the supersonic cleaner, in which de-ionized water is provided, to remove the sacrificial layer 22 and portions of the alloy layer 24 by supersonic vibrations, without removing the alloy layer 24 on top of the bonding pad 16. Since the sacrificial layer 22, being a positive photo-resistant layer, is not hard-baked, it is loosely adhered to the passivation layer 18. Accordingly, the alloy layer 24 on the sacrificial layer 22 can be simultaneously removed when removing the sacrificial layer 22 with the supersonic vibrations. On the other hand, there is no sacrificial layer 22, with poor adhesion ability, existing between the bonding pad 16 and the alloy layer 24 on the bonding pad 16. Thus, the alloy layer 24 on the bonding pad 16 is not removed when the supersonic vibration cleaning is carried out.
The prior art method of forming the bonding pad is to form an aluminum-copper alloy layer by an alloy process, to improve the bonding ability of the bonding pad 16 due to the many alloy phases of an aluminum-copper alloy and other metals. In addition, the number of cleaning and development processes are reduced. The sacrificial layer 22 and the unwanted alloy layer 24 are removed by utilizing de-ionized water and ultrasonic vibrations to avoid acidic erosion of the portion of the alloy layer 24 on top of the bonding pad 16. However, an edge portion 26 of the bonding pad 16, formed according to the prior art method, always produces an out diffusion phenomenon of copper atoms because the copper material is in contact with the passivation layer 18 directly. As a result, short circuits occur.
It is therefore a primary objective of the claimed invention to provide a method of forming a bonding pad, specifically a method utilizing an alloy process and a photo-etching process (PEP) to form a self-aligning bonding pad to resolve the abovementioned problem.
According to the claimed invention, a substrate, including a first dielectric layer and at least one first conductive layer in the first dielectric layer, is provided. Then a second conductive layer is formed on the first conductive layer and the first dielectric layer. Thereafter, a thermal treatment process is performed to form a third conductive layer in the second conductive layer in contact with the first conductive layer, and completely oxidize the remaining second conductive layer to form a second dielectric layer. Next, a third dielectric layer is formed on the second dielectric layer. Finally, a photo-etching process (PEP) is performed to remove portions of the third dielectric layer and portions of the second dielectric layer on the first conductive layer until reaching the top surface of the third conductive layer.
It is an advantage of the claimed invention that the method of forming the bonding pad according to the present invention is to sputter an aluminum layer on the bonding pad and on the dielectric layer surrounding the bonding pad, followed by a heat treatment process. The aluminum layer on top of the bonding pad reacts and becomes a stacked structure, including an aluminum-oxide layer and an aluminum-copper alloy layer. The aluminum layer on top of the dielectric layer surrounding the bonding pad is completely oxidized and becomes an aluminum-oxide layer to be used for self-aligning in a subsequent etching process.
Since the aluminum-copper alloy is a saturate and in a stable phase, copper atoms are not readily inserted into the aluminum-copper alloy structure. The copper atoms in the bonding pad are prevented from diffusing upward, resolving the out diffusion problem occurring at the edge portion of the bonding pad formed according to the prior art method. In addition, the aluminum-copper alloy layer is also used as an etch-stop layer when forming a passivation opening to avoid the non-volatile byproduct produced during copper etching. Because the number of the alloy phases of the aluminum-copper alloy and other metals is greater than the number of the alloy phases of copper and other metals, a better flexibility and feasibility are provided in wire bonding. If gold wires are used as bonding wires, a good bondability results from the excellent solid solubility of the aluminum-copper alloy in gold.
These and other objectives of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings.