Name: 斯坦福納米加工設備：幹法蝕刻 - 幹法蝕刻機制（第 3 部分，共 4 部分） (Stanford Nanofabrication Facility: Dry Etching - Dry Etching Mechanisms (Part 3 of 4))
Uploaded: 2025-06-07T15:31:59.000Z
Duration: 18 min 38 s

Hi, I'm Derek Bitty of the Stanford Nanofabrication Facility here at Stanford University.

大家好，我是斯坦福大學斯坦福納米加工設施的德里克-比蒂。

This is part three of a four-part lecture series on dry etching.

這是幹法蝕刻四部曲系列講座的第三部分。

In this presentation, I'm going to cover dry etching mechanisms.

在本講座中，我將介紹幹蝕刻機制。

Previously, the first lecture was on introduction to dry etching.

在此之前，第一場講座是關於幹蝕刻的介紹。

The second was on the basics of plasmids and the types of dry etch tools.

第二個主題是質粒的基礎知識和幹蝕刻工具的類型。

And the next lecture after this one will be on choosing a dry etching processing tool.

在這次講座之後，下一次講座的主題是選擇幹蝕刻加工工具。

In this presentation, I'm going to cover the following areas.

在本講座中，我將介紹以下幾個方面。

Followed by ion-enhanced chemical etching.

I'm then going to talk about x-configuration and x-mechanism comparisons.

接下來，我將談談 x 配置和 x 機制的比較。

And finally, non-ideal pattern transfer issues in dry etching.

最後是幹蝕刻中的非理想圖案轉移問題。

I'm going to start with physical spotting.

Which is, I think, well, an ion knocking atoms off a surface, or can be thought of as atomic sandblasting.

我認為，這就是離子將原子從表面擊落，也可以認為是原子噴砂。

The diagram here shows an ion coming in and material coming off the surface.

圖中顯示的是離子進入和物質從表面流出的情況。

Now, the sputtering tools, I'm going to say, typically use argon, but any ion can cause sputtering.

我要說的是，濺射工具通常使用氬氣，但任何離子都可能導致濺射。

We like argon because it has no chemistry and all that, and we tend to get it for the same power condition, we get higher ion fluxes with argon and other things.

我們喜歡氬氣，因為它不產生化學反應，而且在相同的功率條件下，我們往往能得到氬氣，氬氣和其他物質能產生更高的離子通量。

Physical sputtering tends to be used for anisotropic etching, but it has issues of damage, low selectivity, redeposition.

物理濺射通常用於各向異性蝕刻，但存在損壞、低選擇性和再沉積等問題。

And we typically use physical sputtering when there's no volatile byproducts.

在沒有揮發性副產品的情況下，我們通常使用物理濺射。

So we prefer using chemistry because chemistry, I'll go along and show you, gives you a lot of advantages in terms of rate and profile control.

是以，我們更傾向於使用化學方法，因為化學方法在速率和輪廓控制方面有很多優勢，我會一一向你展示。

But sometimes there's no byproduct that comes off the surface, so it has to be all physical.

但有時表面上並不會產生副產品，所以必須全部採用物理方法。

I want to show you some typical rates for sputtering.

我想向大家展示一些典型的濺射率。

So here's a case of rates dependent on ion current, energy, and the material.

是以，這裡的速率取決於離子電流、能量和材料。

So I'm going to show you a case of 500 eV argon at 1 milliamp per square centimeter. 1 milliamp per square centimeter corresponds to 10 to the 15th ions per centimeter squared per second.

是以，我將向你們展示一個每平方釐米 1 毫安的 500 eV 氬氣案例。每平方釐米 1 毫安相當於每平方釐米每秒產生 10 到 15 個離子。

So here I have a list of materials and x-rays of sputter rates.

是以，我這裡有一份材料和濺射率 X 射線的清單。

The first thing we see is that the numbers are relatively low in terms of rates.

我們首先看到的是，就比率而言，數字相對較低。

它們的組織、部門都是納米/分鐘。

The second thing I want to show you is that when you talk about the comparison of a sputter rate of metal versus metal oxides, you tend to have big differences.

我想告訴大家的第二件事是，在比較金屬與金屬氧化物的濺射率時，往往會出現很大的差異。

金屬氧化物的濺射速度要慢得多。

In the case of aluminum, the ratio between the oxide and aluminum, all are 10 to 1.

就鋁而言，氧化物和鋁的比例都是 10 比 1。

So aluminum sputters 10 times faster than the oxide.

是以，鋁的噴濺速度比氧化物快 10 倍。

The other point to look at here is the low selectivity.

還有一點需要注意的是，選擇性很低。

For the most part, they're not that different.

在大多數情況下，它們並沒有什麼不同。

Silicon and silicon oxide sputter rates are not that much different from photoresist.

硅和氧化硅的濺射率與光刻膠沒有太大區別。

Let's go on here and talk about the next case of pure chemical etching.

下面我們繼續討論純化學蝕刻的下一個案例。

Here we have radicals reacting spontaneously with terrific atoms.

在這裡，自由基會自發地與原子發生反應。

The typical case we use a lot is fluorine, CF4 from fluorine, basically etching silicon.

我們經常使用的典型情況是氟，即氟的 CF4，基本上是蝕刻硅。

Fluorine will spontaneously etch with silicon.

So you don't need any ion bombardment with this.

是以，你不需要用它進行任何離子轟擊。

In this process, we're basically getting a neutral coming down and forming a byproduct.

在這個過程中，我們基本上是讓一種中性物質降下來，形成一種副產品。

We typically use it with free fluorine for silicon etching and free oxygen for polymer etching.

我們通常將其與遊離氟一起用於硅蝕刻，與遊離氧一起用於聚合物蝕刻。

They tend to show strong temperature and loading dependence.

它們往往表現出強烈的溫度和負載依賴性。

By this, I mean as the rate increases significantly with temperature, typically an activation energy of about 1 eV, and the rate decrease which increases both areas.

我的意思是，隨著溫度的升高，速率會顯著增加，通常活化能約為 1 eV，而速率的降低會增加這兩個方面。

So basically, as your larger area, your radical density has to be used, your source of radicals have to be used over a larger area, so the rate goes down.

是以，基本上，隨著面積的增大，必須使用自由基密度，必須在更大的面積上使用自由基源，是以速率會下降。

It can be a lot faster in the etching than sputtering, but a lot of times we need something more than isotropic.

它的蝕刻速度比濺射快得多，但很多時候我們需要的不是各向同性。

So that's where some of the next mechanisms will come into play.

是以，接下來的一些機制就會發揮作用。

And the characteristics of the pure etching is it's stopped by any surface deposition or any formation of non-volatile products.

純蝕刻的特點是，任何表面沉積或非揮發性產物的形成都會阻止它。

Say you have a contaminate in the material you're etching, and that contaminate can build up to the surface and finally stop the etching.

如果您正在蝕刻的材料中含有汙染物，汙染物可能會堆積到表面，最終導致蝕刻停止。

Here's an example of near-pure chemical etching.

下面是一個近乎純化學蝕刻的例子。

This was done on our LAM ICP etcher using SFC and fluorine, but it was set up to be a very isotropic etching, so we see here that the lateral etch rate is almost equal to the vertical etch rate.

這是在我們的 LAM ICP 蝕刻儀上使用 SFC 和氟完成的，但它被設置為非常各向同性的蝕刻，是以我們可以看到橫向蝕刻率幾乎等於縱向蝕刻率。

是以，我們這裡的比例幾乎是 1。

Now I'm going to talk about the next two mechanisms I'm calling mixed mechanisms.

現在我要談談接下來的兩種機制，我稱之為混合機制。

The first one is going to be the ion-enhanced chemical etching, and then I'm going to talk about inhibitor or deposition-controlled etching.

首先是離子增強化學蝕刻，然後是抑制劑或沉積控制蝕刻。

So here I show that I have a nucleus coming in, the ions coming down, activating.

是以，我在這裡展示的是一個原子核進入，離子下來並激活。

I've talked about this in some of the earlier lectures.

我在之前的一些講座中已經談到過這一點。

So the ion activates or gets the process going, and then we form the volatile byproduct coming off.

是以，離子激活或啟動了這一過程，然後我們就形成了揮發性副產品。

Radicals, so we basically talk about radicals going down to the surface, but the reactant can be blocked.

自由基，所以我們基本上說的是自由基向下到達表面，但反應物可以被阻斷。

Maybe it can't break, let's say, a silicon and chlorine.

比方說，它可能無法分解硅和氯。

The chlorine cannot break the silicon-silicon bond, so it gets stopped, or it can be a deposition going on.

氯氣無法破壞硅-硅鍵，是以會被阻止，也可能是沉積正在進行。

So the ions break the reaction-blocking bonds and help the byproduct get off the surface.

是以，離子會打破阻礙反應的鍵，幫助副產品離開表面。

So here I'm saying chlorine, silicon with chlorine, and the ion coming in, basically forming silicon dichloride, or silicon tetrachloride, coming off the surface.

是以，在這裡我說的是氯、硅與氯，以及離子進入，基本上形成二氯化硅或四氯化硅，從表面脫落。

The process tends to be less dependent on temperature, less loading-dependent, and less dependent on surfactant oxides than the pure chemical case.

與純化學過程相比，該過程對溫度的依賴性較小，對裝載量的依賴性較小，對錶面活性劑氧化物的依賴性也較小。

You can get good selectivity, good anisotropic, but it is subject to some secondary effect, and I'll show that later on.

你可以獲得很好的選擇性和各向異性，但它會受到一些次要效應的影響，我稍後會介紹這一點。

The second mechanism is ion-enhanced inhibitor etching.

第二種機制是離子增強抑制劑蝕刻。

And this is where we have simultaneous deposition and etching going on at the same time.

這就是我們同時進行沉積和蝕刻的地方。

The diagram here I'm showing, here I have ions coming in, I have a neutral coming down, and I'm showing here a little inhibitor layer here, where the ions are coming in, breaking through the inhibitor layer, allowing the radical to come down and react with the material we want to etch, and then the radical product coming off.

在我展示的圖表中，有離子進入，有中性物質下來，這裡還有一個小的抑制層，離子進入抑制層，突破抑制層，讓自由基下來，與我們要蝕刻的材料發生反應，然後自由基產物脫落。

So typically what we do, let's say chlorine chemistry or something, we add another gas element to promote deposition, and that can be hydrogen, it can be carbon fluoride, CHF3, O2, nitrogen, and boron trichloride can help us.

是以，我們通常要做的，比方說氯化學或其他，就是加入另一種氣體元素來促進沉積，可以是氫氣，也可以是氟化碳、CHF3、氧氣、氮氣，三氯化硼也可以幫助我們。

I'll tell you there are cases where boron trichloride is helpful in etching.

我會告訴你，在某些情況下，三氯化硼有助於蝕刻。

So we basically use local deposition to block or slow etching, and then we use ion bombardment to remove the deposition on the horizontal surfaces.

是以，我們基本上使用局部沉積來阻止或減緩蝕刻，然後使用離子轟擊來清除水準表面上的沉積。

Temperature, the process tends to show temperature and loading dependencies, not as bad as a pure chemical case, but the typical is temperature dependence.

溫度，該過程往往顯示出溫度和負載依賴性，不像純化學過程那麼糟糕，但典型的是溫度依賴性。

You can get good selectivity, good anisotropy, and the process is somewhat tunable by how much deposition we put in.

你可以獲得良好的選擇性和各向異性，而且我們可以根據沉積量對工藝進行調整。

Here in the diagram I'm showing a case where we have a low amount of deposition, so we're not quite isocropic, but we still have a certain amount undercut.

在圖中，我展示的是一種沉積量較低的情況，是以我們並不完全等向，但仍有一定量的下切。

As we increase the deposition, we can go from this case to a pure anisotropic, and if we keep on increasing deposition, then we get sloped walls.

隨著沉積量的增加，我們可以從這種情況變為純粹的各向異性，如果我們繼續增加沉積量，就會得到傾斜的牆壁。

Sometimes we want sloped walls, but a lot of times we want the anisotropic behavior.

有時我們需要傾斜的牆壁，但很多時候我們需要各向異性的行為。

And here's some SEMs of a case of silicon etching using HBR, so it's a bromine-NF3-fluorine-oxygen combination, and we had an oxide mask, and this was done in our P5000 etching tool.

這是使用 HBR（溴-NF3-氟-氧組合）蝕刻硅的一些掃描電子顯微鏡照片，我們有一個氧化物掩膜，這是在我們的 P5000 蝕刻工具上完成的。

And we show here ag-etched, you see the wall closer, so basically in the process we actually form the oxide, so we go in and with a 51-HF dip, it removes this oxide-like material on the side, and so here it's down to the mask material, and you see we get a fairly anisotropic, and this process, if we tune it right, we can get all the vertical sidewalls, very anisotropic behavior.

我們在這裡展示了蝕刻，你可以看到更接近的壁，所以基本上在這個過程中，我們實際上形成了氧化物，所以我們進入並使用 51-HF 浸漬，它可以去除側面的氧化物狀物質，所以在這裡它是向下到掩膜材料，你可以看到我們得到了一個相當各向異性，這個過程，如果我們調整得當，我們可以得到所有的垂直側壁，非常各向異性的行為。

But it's a combination of fluorine and bromine chemistry with oxide formation.

但這是氟和溴化學與氧化物形成的結合。

And the oxide formation, we have oxygen reacting with the silicon coming off to form this silicon dioxide-like material on the sidewall.

氧化物的形成，是氧氣與脫落的硅發生反應，在側壁上形成類似二氧化硅的物質。

So here I want to show mechanisms and configuration comparisons.

是以，我想在這裡展示機制和配置的比較。

So here I'm talking about we have physical processes versus chemical processes.

所以在這裡，我說的是物理過程和化學過程。

At higher pressures, we tend to show much more chemical processes, higher energy, if not more physical processes.

在更高的壓力下，我們往往會看到更多的化學過程、更高的能量，甚至更多的物理過程。

The chemical processes give a better selectivity.

The physical processes, as we go more to ion-driven processes, we get the anisotropic behavior.

在物理過程中，隨著離子驅動過程的增加，我們會發現各向異性的行為。

And so here, I mentioned sputtering on the more physical end, pure chemical, and then the mixed region where we have a lot to control.

是以，在這裡，我提到的濺射是更物理的一端，純化學的一端，然後是混合區域，在這裡我們有很多需要控制的地方。

This is where we like to operate with the chemistry and the ion bombardment to give a control of what we selectively, high selectivity, good profile control.

這就是我們喜歡使用化學和離子轟擊來控制選擇性、高選擇性和良好輪廓控制的原因。

And here I show the different configurations.

在這裡，我展示了不同的配置。

So I'm saying downstream action is mainly for chemical processes.

所以我說下游作用主要是針對化學過程的。

And ICP, well, ICP allows us to give a very broad range.

而 ICP 可以讓我們提供非常廣泛的範圍。

We can go in and tune the amount of ion energy, and we can run...

我們可以調整離子能量的大小，也可以運行...

ICP can actually run from low pressures down to a few millitor, all the way up to 100 millitor.

實際上，ICP 可以從低壓到幾毫微克，一直運行到 100 毫微克。

And then in between, we have the CCP modes, the plasma and the RIE, where the plasma mode tends to be lower ion energies, where the RIE mode tends to be the higher ion energies.

在這兩種模式之間，我們有 CCP 模式、等離子模式和 RIE 模式，其中等離子模式傾向於較低的離子能量，而 RIE 模式傾向於較高的離子能量。

So I want to talk about some of the non-ideal pattern cramp for issues.

是以，我想談談一些非理想模式的抽筋問題。