Name: 斯坦福納米加工設備：幹法蝕刻 - 簡介（第 1 部分，共 4 頁） (Stanford Nanofabrication Facility: Dry Etching - Introduction (Part 1 of 4))
Uploaded: 2025-06-07T15:27:48.000Z
Duration: 13 min 11 s

Hi, I'm Jim McVitie of Stanford's Nanofabrication Facility at Stanford University.

大家好，我是斯坦福大學納米加工設施的吉姆-麥克維蒂。

In this series of four short presentations, I'm going to discuss the basics of dry or plasma etching and give some information to help you choose the right type of plasma etched tool and process for fabricating your nanostructures.

在本系列的四個簡短介紹中，我將討論幹法或等離子刻蝕的基礎知識，並提供一些資訊，幫助您選擇合適的等離子刻蝕工具和工藝來製造納米結構。

So in this first lecture, I'm going to have the introduction of dry etching.

是以，在第一講中，我將介紹幹蝕刻法。

Following lecture will be on the basics of plasma and the type of dry etching tools, dry etching mechanisms, and choosing a dry etching process and tool.

接下來的講座將介紹等離子體的基礎知識和幹蝕刻工具的類型、幹蝕刻機制以及選擇幹蝕刻工藝和工具。

In the presentation, I'm going to cover first, what is dry etching, second, where dry etching is used in fabrication, third, etch profile control and selectivity definitions, and finally, why use plasma for etching.

在演講中，我將首先介紹什麼是幹蝕刻，其次介紹幹蝕刻在製造中的應用，第三介紹蝕刻曲線控制和選擇性定義，最後介紹為什麼要使用等離子體進行蝕刻。

In nanofabrication, etching is the process of removing regions of deposited films or subgrades.

在納米制造中，蝕刻是去除沉積薄膜或子級區域的過程。

Two of the other major processes used in nanofabrication, deposition, the process of laying down films, and lithography, the process of patterning the matte, usually films of fold resist, will be covered in other units of this course.

本課程的其他單元還將介紹納米制造中使用的其他兩個主要工藝，即沉積（鋪膜工藝）和光刻（圖案化亞光（通常是摺疊抗蝕劑薄膜）工藝）。

As I mentioned, here we are covering the important process of dry etching.

如前所述，我們在這裡介紹的是重要的幹蝕刻工藝。

Basically dry etching is vapor or gas-based etching.

基本上，幹蝕刻是基於蒸汽或氣體的蝕刻。

Etching come in as a gas and byproduct leave as a gas.

蝕刻以氣體形式進入，副產品以氣體形式離開。

So having a volatile byproduct is essential for dry etching.

是以，揮發性副產品對於幹法蝕刻至關重要。

Down here I show a diagram of the basics of dry etching.

下面是幹蝕刻的基礎知識圖解。

We have a reaction, in this case fluorine, coming down the surface, etching, reacting with the surface, and a byproduct, silicon tetrafluoride, coming off.

在這種情況下，會有一種反應物，即氟，從表面下來，蝕刻，與表面發生反應，然後產生副產品，即四氟化硅。

In this lecture, I'm going to limit our discussion to plasma dry etching.

在本講座中，我將只討論等離子幹蝕刻。

In this case, the plasma offers an extra control not available by wet etching where we use liquids.

在這種情況下，等離子體提供了額外的控制能力，這是使用液體的溼法蝕刻所無法提供的。

So down in the diagram here we have an extension.

在圖中，我們有一個擴展部分。

Rather than going out with fluorine, we start out with CF4, which is a very stable gas.

我們一開始使用的不是氟，而是 CF4，它是一種非常穩定的氣體。

We use a plasma to break up the gas and generate ions, electrons, but also react with free fluorine that then does the etching that I showed you before.

我們使用等離子體來分解氣體，產生離子和電子，同時與遊離氟發生反應，然後進行蝕刻，我之前已經向你們展示過了。

Where is dry etching used in the fabrication?

幹蝕刻在製造過程中的哪些地方使用？

First, it's used for removing blanket layers, such as, well, we can use it for removing resist and their process or other things.

首先，它用於去除空白層，比如，我們可以用它來去除抗蝕劑及其工藝或其他東西。

Secondly, and most importantly, for patterning.

其次，也是最重要的一點，那就是模式化。

In patterning, we use a mask to block the reaction in ions so that we can duplicate a copy of the mask in the material on the surface of our wafer.

在圖案化過程中，我們使用掩膜來阻止離子反應，這樣就可以在晶圓表面的材料中複製一份掩膜。

And we usually, the mask is often a full resist.

而我們通常，面具往往是一個完整的抵抗。

So let's show a diagram of how this works.

讓我們用圖表來說明其工作原理。

So here, let's say I start out with a substrate with a uniform film, and I want to pattern that film on the top.

在這裡，假設我一開始使用的是帶有均勻薄膜的基底，我想在上面對薄膜進行圖案化。

And the way I get there, first I put out a photoresist layer and pattern it typically with optical beams or electron beams.

我的方法是，首先塗上一層光刻膠，然後用光束或電子束對其進行圖案化。

And then I expose it to my plasma etching process that selectively removes the film and then opens the area.

然後，我將其暴露在等離子蝕刻工藝中，選擇性地去除薄膜，然後打開該區域。

And then I remove the photoresist, so now I have my patterned film on my substrate.

然後去除光刻膠，現在基底上就有了圖案薄膜。

Okay, here I want to do some definitions for X-profile control.

好的，我想在這裡為 X 配置文件控制做一些定義。

So typically, X-profile is critical to the structure we want.

是以，通常情況下，X-profile 對我們想要的結構至關重要。

So for nanostructures, I want to have a high-fidelity reproduction of the structure or pattern in my mask layer in the underlying structure, whereas in other cases, I want to have some slope and maybe a little bit undercut, typically because of step coverage issues.

是以，對於納米結構，我希望能在底層結構中高保真地再現掩膜層中的結構或圖案，而在其他情況下，我希望能有一些斜度，也許會有一點下切，這通常是因為臺階覆蓋問題。

So here I show the case I'm going to define, making anisotropic etching with completely vertical etching, and it completely replicates the mask in the film.

是以，我在這裡展示了我要定義的案例，用完全垂直的蝕刻製作各向異性蝕刻，它完全複製了膠片中的掩膜。

The second case is isotropic etching, and this is where we get the pure chemical etching, where you have undercut equal to the X-depth.

第二種情況是各向同性蝕刻，也就是我們所說的純化學蝕刻，在這種情況下，下切深度等於 X 深度。

So if I go down a nanometer thick, I go sideways a nanometer.

是以，如果我向下移動一納米厚，就會向旁邊移動一納米。

And again, this can be very useful for some structures where we really have a difficult time getting step coverage.

同樣，這對某些結構非常有用，因為在這些結構中，我們確實很難獲得階躍覆蓋。

And lastly, I want to talk about the neo-anisotropic or directional etching.

最後，我想談談新各向異性或定向蝕刻。

This is a little probably more typical of a lot of things we're going to actually see.

這可能是我們將要看到的很多事情中比較典型的一點。

We have a little bit of undercut, and we have some slope.

我們有一點下切，還有一些坡度。

And a lot of times we want to do this intentionally because, like I say, step coverage, when we have a film going over a sharp step, having some slope improves our ability, well, reduces the chance of having a breakage of the film at the corners.

很多時候，我們都想故意這樣做，因為，就像我說的，在臺階覆蓋時，當我們的膠片經過一個急劇的臺階時，有一些坡度可以提高我們的能力，以及減少膠片在拐角處破損的機會。

Okay, let's have a definition of X-selectivity.

好吧，我們來給 X 選擇性下個定義。

Selectivity is the ratio of the X-rate of the material to be removed, divided by the material to remain.

選擇性是待去除材料的 X 速率除以剩餘材料的比率。

And so let's say here is my diagram of the substrate, the film, and the photoresist pattern.

比方說，這是我繪製的基底、薄膜和光刻膠圖案的示意圖。

Now I've shown some etching, so I've removed some of my photoresist, and I've etched in the material.

現在，我展示了一些蝕刻，是以我去掉了一些光刻膠，並在材料上進行了蝕刻。

And the reason I want selectivity is I don't want to lose the matte material before I get all the way through the film I'm etching.

我之所以要有選擇性，是因為我不想在蝕刻完所有膠片之前就失去啞光材料。

Secondly, a second selectivity is when I go all the way through the material and I hit the substrate material.

其次，第二種選擇性是當我一路穿過材料並撞擊到基底材料時。

And there the selectivity can also be very important, such as if I'm etching a gate over a gate oxide, a thin gate oxide, I have to stop immediately before going through that thin oxide.

選擇性也非常重要，例如，如果我在柵極氧化物（薄柵極氧化物）上蝕刻柵極，我必須在蝕刻過薄氧化物之前立即停止。

So therefore I want a very high selectivity to the material removed to my underlying gate oxide.

是以，我希望在柵極底層氧化物上去除的材料具有極高的選擇性。

So normally we want a high selectivity, we want the rate of removal of my film to be much greater than the removal rate of my mask layer.

是以，通常情況下，我們需要高選擇性，希望膠片的去除率遠遠高於掩膜層的去除率。

So here's an example of the etching of polysilicon over a silicon dioxide layer.

下面是一個在二氧化硅層上蝕刻多晶硅的例子。

是以，這是一個接近各向異性的蝕刻案例。

Here I have a top layer right here is the photoresist layer.

這裡有一個頂層，就是光刻膠層。

Below that I have the polysilicon layer that I'm patterning.

下面是我正在繪製圖案的多晶硅層。

And finally I have the silicon dioxide layer down below.

And for this process we have a polysilicon to photoresist selectivity of 6 and a polysilicon oxide selectivity ratio of 13.

在該工藝中，多晶硅對光刻膠的選擇性為 6，多晶硅對氧化物的選擇性為 13。

These numbers, these selectivity ratios can be from 1 to over 100, even up to 1000 depending on the process and the details.

這些數字、這些選擇性比率可以從 1 到 100 以上，甚至高達 1000，具體取決於工藝和細節。

First we can use it for generating local sources.

首先，我們可以用它來生成在地資源。

So like I say before I showed etching of silicon with free fluorine.

就像我之前說的，我展示了遊離氟對硅的蝕刻。

Free fluorine is very reactive and it's much easier and safer to generate the fluorine locally using a PLAPA.

遊離氟的反應性很強，使用 PLAPA 在在地生成氟要容易得多，也安全得多。

Second, PLAPA etching is often much easier to do than wet.

其次，PLAPA 蝕刻通常比溼法蝕刻容易得多。

Case in point is the case of polysilicon etching.

多晶硅蝕刻就是一個很好的例子。

Wet polysilicon etching is very difficult to do with a mask layer.

溼法多晶硅蝕刻很難使用掩膜層。

Next we can get very high aspect ratios using PLAPA etching.

接下來，我們可以利用 PLAPA 蝕刻技術獲得極高的高寬比。

So an aspect ratio is a ratio of the depth divided by the width.

是以，長寬比是深度除以寬度的比值。

So here I'm showing an etch into silicon of an aspect ratio of 40 and 1.

是以，我在這裡展示的是長寬比為 40 和 1 的硅蝕刻圖。

In PLAPA etching we have ions and the ion can be used to bombard the surface and can do a number of useful things.

在 PLAPA 蝕刻中，我們有離子，離子可以轟擊表面，並能做很多有用的事情。

One, the ion can clean the surface, remove oxide, polymers left over from lithography before your etching process.

其一，離子可以清潔表面，去除光刻過程中留下的氧化物和聚合物。

In addition they can activate chemical reactions.

此外，它們還能激活化學反應。

So I'll show you how sometimes the chemical, the radicals will just sit on the surface and do nothing and the ion can come in, break bonds and allow the reaction to proceed.

所以，我將向你展示，有時化學物質、自由基只是停留在表面，什麼也不做，而離子可以進入，打破鍵，讓反應繼續進行。

And ions are nice in that we can control the ion energy and the directionality by using the geometry of the system and by having, by judicial use of RF power.

離子的好處在於，我們可以通過使用系統的幾何形狀和射頻功率來控制離子的能量和方向性。

Ion energy and directionality are key to anisotropic etching.

離子能量和方向性是各向異性蝕刻的關鍵。

Higher energy means more directional ions and that leads to more anisotropic etch problems.

更高的能量意味著更多的定向離子，從而導致更多的各向異性蝕刻問題。

In this diagram I show symbolically the etching process and role of ions.

在這幅圖中，我象徵性地展示了蝕刻過程和離子的作用。

So here on the top part here I'm saying here I have an electron colliding with a source molecule generating a free radical.

是以，在上半部分，我說的是電子與源分子碰撞產生自由基。

This free radical then diffuses to the surface that I want to etch, it absorbs in the surface and if it's like chlorine it'll just sit there.

然後，這些自由基會擴散到我要蝕刻的表面，被表面吸收，如果它像氯一樣，就會停留在那裡。

But we have an ion come in, the ion can actually create site by breaking bonds, let's say silicon bonds, and when the bonds are broken the absorbed etching can then react with the materials, let's say silicon, and then form a volatile product or lead to a chain reaction of spontaneous reactions that form a volatile product.

但是，我們有一個離子進來，這個離子實際上可以通過斷裂鍵（比如硅鍵）來產生位點，當鍵被斷裂時，吸收的蝕刻物就會與材料（比如硅）發生反應，然後形成揮發性產物，或者導致自發反應的連鎖反應，形成揮發性產物。

And so the product then comes off and we're then removing, let's say silicon, we remove silicon from the surface.

這樣，產品就會脫落，然後我們就可以去除，比方說硅，我們從表面去除硅。

Here I show an example reaction here of chlorine.

這裡我展示了一個氯反應的例子。

So we have chlorine gas going into the plasma, electrons in the plasma breaking the chlorine gas into two chlorine atoms, then on the surface silicon plus an ion plus the chlorine atoms yield silicon dichloride, that comes off, we can either have dichloride or trichloride come off, and if you have the dichloride case then it can react in the gas phase to form the more stable form of silicon tetrachloride.

是以，氯氣進入等離子體，等離子體中的電子將氯氣分解成兩個氯原子，然後在表面硅加離子加氯原子生成二氯化硅，二氯化硅脫落後，可以生成二氯化物或三氯化物，如果是二氯化物，則可以在氣相中反應生成更穩定的四氯化硅。

Etching, a dry etching is a gas phase etching, byproduct of volatility is essential.

蝕刻，幹蝕刻是一種氣相蝕刻，副產品的揮發是必不可少的。

Plasmas offer lots of advantages over wet etching.

與溼蝕刻相比，等離子體具有很多優勢。

And one of the big advantages is the flexibility of the etch profile, we have isocropic, anisocropic, near anisocropic, and we have local generation of reaction for radicals.

其中一個最大的優勢是蝕刻曲線的靈活性，我們有各向同性、各向異性、接近各向異性的蝕刻曲線，我們還能在局部產生自由基反應。

And we have controlled ion bombardment, which can be used to activate surfaces in addition to cleaning, and the ions have directionality.

我們還擁有可控離子轟擊技術，除清潔外，還可用於活化表面，而且離子具有方向性。

In the next video, I'll talk about the basics of plasmas and the types of dry etching tools.

在下一個視頻中，我將介紹等離子體的基礎知識和幹蝕刻工具的類型。